Protected: Physical exercise in chronic kidney disease: an empty narrative or an effective intervention?

Abstract

Chronic kidney disease (CKD) is growing worldwide, with increasing numbers of patients facing end-stage renal disease, high cardiovascular risk, disability and mortality. Early recognition of CKD and improvements in lifestyle are crucial for maintaining or recovering both physical function and quality of life.

It is well known that reducing sedentariness, increasing physical activity and initiating exercise programs counteract cardiovascular risk and frailty, limit deconditioning and sarcopenia, and improve mobility, without side-effects. However, these interventions, often requested by CKD patients themselves, are scarcely available. Indeed, it is necessary to identify and train specialists on exercise in CKD and to sensitize doctors and health personnel, so that they can direct patients towards an active lifestyle. On the other hand, effective and sustainable interventions, capable of overcoming patients’ barriers to exercise, remain unexplored.

Scientific societies, international research teams and administrators need to work together to avoid that exercise in nephrology remains an empty narrative, a niche interest without any translations into clinical practice, with no benefit to the physical and mental health of CKD patients.

Keywords: chronic kidney disease; physical activity; exercise; quality of life; sarcopenia; disability; physical function; barriers.

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Atheroembolic renal disease: risk factors, diagnostics, histology, and therapeutic approaches

Abstract

The increase in patients’ average age, the enhancement of anticoagulation therapy and the growth of vascular interventions represent the perfect conditions for the onset of atheroembolic renal disease. AERD is observed in patients with diffuse atherosclerosis, generally after a triggering event such as surgery on the aorta, invasive procedures (angiography, catheterization of the left ventricle, coronary angioplasty) and anticoagulant or fibrinolytic therapy. The clinical signs are heterogeneous, a consequence of the occlusion of downstream small arterial vessels by cholesterol emboli coming from atheromatous plaques of the aorta, or one of its main branches. The proximity of the kidneys to the abdominal aorta, and the high flow of blood they receive, make them a major target organ. For this reason, AERD represents a pathological condition that always needs to be taken into account in the nephropathic patient, although its systemic nature makes the diagnosis difficult.

This manuscript presents a review of the existing literature on this pathology, to provide an updated summary of the state of the art: risk factors, diagnostics, histology and therapeutic approaches.

Keywords: atherosclerosis, cholesterol crystal embolism, contrast media, acute kidney injury, chronic kidney disease

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Introduzione

L’Atheroembolic Renal Disease (AERD) rappresenta una condizione patologica multisistemica, definita da un quadro di insufficienza renale secondaria all’occlusione dell’arteria renale, delle arteriole o dei capillari glomerulari per rottura di una placca aterosclerotica e sua successiva embolizzazione [1].

Storicamente la AERD è una entità mal definita, assimilata da alcuni autori alla “Cinderella” della Nefrologia [2], spesso trascurata, dall’incidenza imprecisa e frequentemente sottostimata [3].

L’obiettivo di questo studio è quello di dar luogo ad una revisione della letteratura sulla AERD, seguendo le linee Guida Internazionali PRISMA [4], finalizzata ad una più permeante inclusione della malattia come entità nosologica nella diagnostica differenziale e ad una maggiore sensibilità verso la diagnostica pre-mortem della malattia, valutandone la possibilità di una maggiore diffusione capillare tra le società scientifiche di nefrologia, cardiologia e radiologia interventistica. Inoltre, si ambisce a segnalare la necessità di un programma inter-societario (società scientifiche di radiologia, di cardiologia, di cardiochirurgia, di nefrologia), volto ad una informazione capillare di interesse bivalente (medico e paziente) e all’attiva sorveglianza delle possibili complicanze ateroemboliche nel corso delle procedure interventistiche.

 

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Home hemodialysis: multicenter observational study

Abstract

Home dialysis is a primary objective of Italian Ministry of Health. As stated in the National Chronicity Plan and the Address Document for Chronic Renal Disease, it is mostly home hemodialysis and peritoneal dialysis to be carried out in the patient’s home. Home hemodialysis has already been used in the past and today has found new technologies and new applications. The patient’s autonomy and the need for a caregiver during the sessions are still the main limiting factors.

In this multicenter observational study, 7 patients were enrolled for 24 months. They underwent six weekly hemodialysis sessions of 180′ each; periodic medical examinations and blood tests were performed (3, 6, 12, 18 and 24 months). After 3-6 months of home hemodialysis there was already an improvement in the control of calcium-phosphorus metabolism (improvement in phosphorus values, (p <0.01), a reduction in parathyroid hormone (p <0.01)); in the number of phosphorus binders used (p <0.02); in blood pressure control (with a reduction in the number of hypotensive drugs p <0.02). Home hemodialysis, although applicable to a small percentage of patients (10-15%), has improved blood pressure control, calcium-phosphorus metabolism and anemia, reducing the need for rhEPO. Keywords: chronic kidney disease, home dialysis, home hemodialysis

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Introduzione

Il mondo della cronicità rappresenta un’area in progressiva crescita che richiede continuità assistenziale per periodi di lunga durata, comporta un notevole impegno di risorse e richiede una forte integrazione dei servizi sanitari con quelli sociali: si crea pertanto la necessità di implementare servizi e percorsi residenziali/territoriali finora non sufficientemente sviluppati.

La gestione della cronicità rappresenta perciò una sfida importante per la sostenibilità del Servizio Sanitario Nazionale (SSN). A tal proposito il Ministero della Salute ha individuato gruppi di patologie da regolamentare sia per peso epidemiologico, assistenziale ed economico che per la difficoltà di accesso alle cure ed ha emanato, in condivisione con le Regioni, nel settembre 2016, il “Piano Nazionale della Cronicità” (PNC) [1] e quindi nel marzo 2017 il “Documento di Indirizzo per la Malattia Renale Cronica (MRC)” [2]. Questi documenti si pongono come obiettivo principale l’ottimizzazione della gestione del paziente cronico e in particolare (nel secondo caso) quello con MRC, attraverso le evidenze scientifiche emergenti, l’appropriatezza delle prestazioni e la condivisione dei Percorsi Diagnostici e Terapeutici Assistenziali (PDTA) [1]. A questo proposito, fra le principali criticità sono evidenziate una carente offerta per la dialisi peritoneale (DP) e l’emodialisi domiciliare (EDD) [1,2].

 

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The link between homocysteine, folic acid and vitamin B12 in chronic kidney disease

Abstract

Patients with chronic kidney disease or end-stage renal disease experience tremendous cardiovascular risk. Cardiovascular events are the leading causes of death in these patient populations, thus the interest in non-traditional risk factors such as hyperhomocysteinemia, folic acid and vitamin B12 metabolism is growing.  Hyperhomocysteinemia is commonly found in CKD patients because of impaired renal metabolism and reduced renal excretion. Folic acid, the synthetic form of vitamin B9, is critical in the conversion of homocysteine to methionine like vitamin B12. Folic acid has also been shown to improve endothelial function without lowering homocysteine, suggesting an alternative explanation for the effect of folic acid on endothelial function. Whether hyperhomocysteinemia represents a reliable marker of cardiovascular risk and cardiovascular mortality or a therapeutic target in this population remains unclear. However, it is reasonable to consider folic acid with or without methylcobalamin supplementation as appropriate adjunctive therapy in patients with CKD. The purpose of this review is to summarize the characteristics of homocysteine, folic acid, and vitamin B12 metabolism, the mechanism of vascular damage, and the outcome of vitamin supplementation on hyperhomocysteinemia in patients with CKD, ESRD, dialysis treatment, and in kidney transplant recipients.

Keywords: hyperhomocysteinemia, folic acid, vitamin B12, chronic kidney disease, end-stage renal disease, cardiovascular disease

Introduction

Chronic Kidney Disease (CKD) represents an important economic burden for health systems around the world, with an estimated global prevalence of between 11 and 13%. Rationalized measures are needed to slow the progression to end-stage kidney disease (ESRD) and to decrease cardiovascular mortality [1]. Mortality rates remain in fact above 20% per year with the use of dialysis, with more than half of all deaths related to cardiovascular disease [2]. The problem of peripheral arteries disease (PAD) is also emerging, which is more common in patients with CKD and is associated with lower limb amputations and increased mortality [3].

Traditional factors such as hypertension, dyslipidaemia and diabetes mellitus are not sufficient to explain the dramatically increased cardiovascular risk in the population with CKD/ESRD. Thus, much attention shifted to other less studied aspects of CKD such as oxidative stress, endothelial dysfunction, chronic inflammation, vascular calcification in chronic kidney disease-mineral and bone disorder (CKD-MBD) and finally hyperhomocysteinemia (HHcy) [4].

The latter, since its discovery, proved to be a plausible risk factor for the development of atherosclerotic vascular disease processes leading to cardiovascular disease (CVD) and stroke. Levels of homocysteine (Hcy) higher than 20.0 μmol/L are associated with mortality 4.5 times higher. The “homocysteine hypothesis” is supported by the fact that subjects with problems in the enzymatic pathway of homocysteine metabolism have a higher level of homocysteine than the general population and a faster progression of arteriosclerosis. Therefore, the link between cardiovascular mortality and arteriosclerosis has been the subject of debate with conflicting results [5].

The high prevalence of HHcy in patients with CKD generated interest in a potential role of HHcy as a risk factor for CKD progression and CVD [5,8,9,10].

Hcy is a non-essential, sulfur-containing, non-proteinogenic amino acid, synthetized by transmethylation of the essential, diet-derived amino acid methionine (Figure 1). Aberrant Hcy metabolism could lead to redox imbalance and oxidative stress resulting in elevated protein, nucleic acid and carbohydrate oxidation and lipoperoxidation, products known to be involved in cytotoxicity [11].

Hcy levels can be significantly reduced by supplementation with folic acid (FA), vitamin B12 and vitamin B6. However, in several randomized and controlled studies the impact of vitamin supplementation seems to be disappointing in terms of cardiovascular mortality [6,7]. The debate is still open: some studies have reported a null or harmful effect of supplementation with FA and B vitamins, including cyanocobalamin [10], while others have confirmed a link between the homeostasis of the vitamins, cardiovascular risk and CKD progression [12]. These two outcomes are ultimately considered the result of a complex interaction between the effects of HHcy, FA, enzymatic activity/gene variants, and FA fortification programs that exist in some countries [13].

 

B vitamins and homocysteine metabolism

Folic acid/Vitamin B9

The term “folate” includes several forms of vitamin B9, including tetrahydrofolic acid (the active form), methyltetrahydrofolate (the primary circulating form), methenyltetrahydrofolate, folinic acid, folacin and pteroylglutamic acid. Since the human body is not able to synthesize folate, it must be provided through the diet [14]. Folic acid comes from polyglutamates that are converted into monoglutamates in the intestine, and then transported through mucous epithelium by a specific vector [15].

Cobalamin/Vitamin B12

Vitamin B12, also known as cobalamin, is a nutrient with a key role in human health: it is essential as a cofactor for the enzyme methionine synthase and other biochemical reactions, such as beta oxidation of fatty acids or DNA synthesis, and in the production of red blood cells [1718]. Vitamin B12 deficiency is a common cause of HHcy and a frequent feature of patients with CKD [1416].

Cobalamin is one of the most complex coenzymes in nature. The molecule consists of a corrinic ring and a part of dimethylbenzimidazole (DMB), and the focal point of the structure is the cobalt atom, held in the center of the corrinic ring which bonds some chemical groups, the most important of which are the hydroxyl group (hydroxocobalamin, OHCbl) and group CN (cyanocobalamin, CNCbl). These are the forms most commonly used in pharmaceutical formulations for vitamin B12 supplementation.

Vitamin B12, when ingested, is complexed with salivary haptocorrin, and cobalamin is released from pancreatic proteases in the duodenum. Then, cobalamin binds to an intrinsic factor secreted by the parietal cells of the stomach: when this complex reaches the distal ileum, it is endocytosed by enterocytes through cubilin. Then, it is transported into the plasma by a plasma transport protein called transcobalamin. B12 is filtered by the glomerulus; however, urinary excretion is minimal under normal conditions, due to reabsorption in the proximal tubule [19].

Metabolism of homocysteine and folate cycle

As mentioned above, Hcy plasma levels are determined by several factors, such as genetic alterations of the methionine metabolism enzymes, and vitamin B12, vitamin B6 and folic acid deficiency. FA, playing a pivotal role in Hcy metabolism, is inert and requires to be activated in tetrahydrofolic acid, a precursor of 5-methyltetrahydrofolate (5-MTHF). Methylenetetrahydrofolate reductase (MTHFR) is a key regulatory enzyme involved in folate dependent Hcy remethylation. MTHFR catalyzes the reduction of 5,10-methyltetrahydrofolate to 5-MTHF, necessary for the normal activity of the enzyme methionine synthetase (MTS), which uses vitamin B12 as a cofactor and converts homocysteine into methionine [20]. Methionine is transformed into S-adenosylmethionine (SAM) and then converted to S-adenosylhomocysteine (SAH) through a reaction catalyzed by methionine synthase reductase (MTRR). SAM is one of the most important donors of methyl groups and is fundamental in the catabolism of various amino acids and fatty acids [21].

Hcy is the final product, derived from the hydrolysis of SAH to Hcy and adenosine, and is located at the center of two metabolic pathways: it is irreversibly degraded through the path of transsulfuration into cysteine or is remethylated to methionine (folate cycle).

  1. Transsulfuration: Firstly, Hcy combines with serine by forming cystathionine via cystathionine-beta-synthase (CBS); then, cystathionine is hydrolyzed into cysteine and alpha-ketobutyrrate from cystathionine-gamma-lyase (CTH). Human CBS is expressed in the liver, kidneys, brain and ovaries and, during the first embryogenesis, in the neural and cardiac systems.
  2. Remethylation: Hcy conversion into methionine is catalyzed by the enzyme MTS and connects the cycle of folates with Hcy metabolism. While the MTS enzyme is expressed ubiquitously, another Hcy remethylation system, betaine-Hcy methyltransferase, is expressed mainly in the liver and kidneys [1].

The main reactions of Hcy metabolism are summarized in Figure 1.

Figure 1: Schematic representation of homocysteine metabolic pathway. DHF: dihydrofolate; DMG: N,N- dimethylglycine betaine; Met: methionine; SAH: S-adenosylhomocysteine; SAM: S-adenosylmethionine; THF: tetrahydrofolate
Figure 1: Schematic representation of homocysteine metabolic pathway. DHF: dihydrofolate; DMG: N,N- dimethylglycine betaine; Met: methionine; SAH: S-adenosylhomocysteine; SAM: S-adenosylmethionine; THF: tetrahydrofolate

 

Folic acid metabolism, vitamin B12 and homocysteine in CKD

Homocysteine

Patients with CKD and ESRD have been shown to have higher blood levels of Hcy than the general population [22]. The normal plasma level is <10 μmol/L; levels of Hcy <16 μmol/L are defined as mild HHcy, while severe HHcy is diagnosed when the levels are >100 μmol/L [23]. About 80-90% of the circulating Hcy is protein-bound; 10-20% of total homocysteine (tHcy) is present as Hcy-cysteine and Hcy mixed disulfide (Hcy dimer), and <1% is present in the reduced free form [14]. In CKD, studies show that the cause of HHcy is a reduced clearance rather than an increase in production, but the exact site of altered clearance remains controversial: under physiological conditions, only non-protein related Hcy is subjected to glomerular filtration and is then mostly reabsorbed into the tubules and oxidized into carbon dioxide and sulfate in kidney cells [24]. Some data support the hypothesis that decreased Hcy removal in CKD is caused by a decreased intrarenal metabolism, through both transsulfuration and remethylation [25].

Folic acid

It has also been shown that an anionic inhibition of the membrane transport of 5-MTHF occurs in patients with CKD with a depression in the intracellular incorporation rate of folates. These results suggest that the level of folates measured in the blood of uremic individuals does not reflect its intracellular use because the uptake is altered due to anionic inhibition [26].

Vitamin B12

Mainly linked to proteins in the blood, about 20% of circulating B12 is related to holotranscobalamin (TC2). The kidney plays an important role in TC2 metabolism, as TC2 is filtered into the glomerulus and is reabsorbed into the proximal tubule. Defects in protein resorption in the proximal tubule could therefore lead to a biologically active loss of CT2 in the urine. Increased levels of TC2 were observed in patients with CKD. Despite this, there is a decrease in TC2 absorption in cells that can lead to a paradoxical increase in cell Hcy levels, despite normal total B12. Thus, a functional deficiency of B12 can occur in patients with CKD as part of an increase in TC2 leaks in the urine, lower absorption of CT2 in the proximal tubule, and lower cellular absorption of TC2.

It is also important to consider that high levels of B12 could be harmful to individuals with CKD. This is related to cyanide metabolism, which is abnormal in individuals with CKD due to the decreased glomerular filtrate. Cyanocobalamin, the most common form of B12 replacement, is metabolized into active methylcobalamin, releasing small amounts of cyanide. Under normal circumstances, methylcobalamin binds to cyanide converting it to cyanocobalamin. However, in patients with CKD, reduced cyanide clearance prevents the conversion of cyanocobalamin into the active form, and therefore integration into this form is less effective in reducing Hcy levels. In addition, the excessive amount of supplementation with cyanocobalamin can release cyanide ions that are not excreted and contribute to the onset of complications in the patient with CKD (e.g. uremic neuropathy) [2728].

 

Methylenetetrahydrofolate reductase polymorphisms

MTHFR plays a key role in Hcy metabolism and catalyzes the conversion of 5, 10-methylenetetrahydrofolate to 5-methyl-THF, the predominant circulating form of folate [29]. The MTHFR gene encodes the enzyme methyltetrahydrofolate reductase and is localized on chromosome 1 (1p36.3). Genetic polymorphisms involved in the homocysteine-methyonine route have been shown to result in HHcy. Although several MTHFR gene variants have been identified, the most characterized are single nucleotide polymorphisms (SNPs) in position 677 (MTHFR 677C>T), in position 1298 (MTHFR 129 8A>C), in position 1317 (MTHFR 1317T>C) and in position 1793 (MTHFR 1793G>A). It has been proposed that the two common mutations, MTHFR C677T and A1298C, may be associated with congenital abnormalities, cardiovascular diseases, strokes, cancer and clotting abnormalities [30,31].

C677T polymorphism is characterized by a point mutation at position 677 of the MTHFR gene that converts a cytosine into a thymine. It is known that when alanine replaces valine in the enzyme at the folate binding site, this polymorphism is commonly called thermolabile, because the activity of the encoded enzyme is reduced by 50-60% at 37°C and by 65% at 46°C. People who are homozygous for C677T tend to have slightly increased blood Hcy levels if their folate intake is insufficient, but normal Hcy levels if folate intake is adequate [32]. Substitution 677C>T is the most common missense variation of MTHFR, with a global prevalence of 40%. The frequency of C677T homozygosis varies depending on the ethnicity: from 1% or less among blacks in Africa and the United States, to 25.3% or more among Italians, Hispanic Americans and Colombians [30]. In contrast, the frequency of the mutant T allele in the MTHFR C677T gene in the Chinese population is 41.7%, higher than in other populations and could be an independent risk factors of early renal damage in the hypertensive Chinese population [33].

A1298C polymorphism is characterized by a point mutation in position 1298 in exon 7 of the MTHFR gene responsible for an amino acid substitution of a glutamine with an alanine in the enzyme regulatory domain. The activity of the encoded enzyme decreases, but to a lesser extent than in the case of C677T polymorphism. Subjects who are homozygotes for the A1298C allele do not appear to have increased serum Hcy levels [30,31]. According to Trovato et al., MTHFR 677C>T and A1298A>C gene polymorphisms could have a protective role on renal function as suggested by the lower frequency of both polymorphisms among a population of 630 dialysis patients in end-stage renal failure [34]. Regarding the other most common SNPs, MTHFR 1317T>C is a silent mutation, while MTHFR 1793G>A results in amino acid replacement, but with no impact on the functional activity of the enzyme [31].

The link between Hcy level and MTHFR gene polymorphisms has been investigated by Malinow et al.: homozygote subjects for the MTHFR T677 allele have shown an important reduction in the plasma levels of tHcy after FA integration. On the other hand, C677 allele homozygosity, especially subjects with higher basal folate levels, have shown a lesser tHcy reduction after FA supplementation. Finally, the carriers of the T/T genotype have shown the sharpest decrease of tHcy with FA integration [35]. This result was confirmed by Anchour et al: the simultaneous supplementation of folate and vitamin B12 was only useful in the homozygotes for the C allele and the reduction of Hcy was significantly higher in the carriers of the TT genotype than in other genotypes (CC/CT) [36]. These findings are consistent with the China Stroke Primary Prevention Trial (CSPPT), in which the largest decrease in serum Hcy was seen in the carriers of the TT genotype [37]. The relationship between MTHFR polymorphism and coronary heart disease severity showed that Hcy levels were significantly higher in patients with coronary arteries disease (CAD) than in control subjects and the genotype of MTHFR 677C>T was associated with increased CAD severity in patients at high risk for this pathology [38]. In summary, most available evidence suggests that MTHFR polymorphisms may influence folic acid and vitamin B12 treatment response in terms of Hcy lowering and cardiovascular risk reduction in patients with CKD and ESRD although indication of routine testing is matter of debate [39].

 

Endothelial damage of homocysteine and impact of CVD in ESRD patients

The pathogenic role of HHcy on the cardiovascular system in CKD and ESRD is related to the progression of atherosclerosis in the context of an already increased risk of vascular damage caused by the uremic syndrome. The mechanisms by which endothelial damage occurs are (Figure 2):

  • Oxidative stress. HHcy helps generate reactive oxygen species (ROS), reactive nitrogen species (RNS) and reactive species of thiol, thus decreasing the bioavailability of nitrogen monoxide (NO). These processes trigger latent matrix-metalloproteinase (MMP) and make the tissue inhibitor of metalloproteinase (TIMP) inactive. This leads to adverse cardiovascular remodelling, with increased collagen deposit [40]. HHcy significantly reduces the expression of the endothelial synthase nitric oxide protein (eNOS) in a dose-dependent manner and ultimately causes impaired basal production of NO, formation of radicals and subsequent endothelial damage by decreasing the bioavailability and bioactivity of NO [41].
  • Inflammation. Through the activation of the nuclear factor kappa B (NF-κB), a transcription factor known to stimulate the production of cytokines, chemokines, leukocyte adhesion molecules, HHcy induces the expression of proinflammatory chemokines MCP-1 and IL-8 in endothelial cells by enhancing transendothelial migration of monocytes, vascular inflammation and atherogenesis [4243]. As for low-density lipoproteins (LDL), N-homocysteination produces aggregation, thus the accumulation of cholesterol, and facilitates the mediated absorption of oxidized LDL by macrophage scavenger receptors, resulting in the formation of foam cells in atherosclerosis [4344].
  • Proliferation of smooth muscle cells. HHcy can significantly promote vascular smooth muscle cells (VSMC) proliferation, by promoting the expression of adhesion molecules, chemokines and VSMC mitogen [45]. HHcy can act directly on glomerular cells by inducing sclerosis and trigger kidney damage by reducing the plasma and tissue level of adenosine. The decrease in plasma adenosine in turn leads to a greater proliferation of VSMC, accelerating the sclerotic process in the arteries and glomeruli. In a pattern of folate-free HHcy rat, glomerular sclerosis, mesangial expansion, podocyte dysfunction, and fibrosis all occurred due to increased local oxidative stress [46].
Figure 2: Main pathogenetic pathways of endothelial damage mediated by hyperhomocysteinemia
Figure 2: Main pathogenetic pathways of endothelial damage mediated by hyperhomocysteinemia

These pathways end up amplifying the atherosclerotic process and inflammatory state present in CKD [47]. For patients with CKD and ESRD, despite the increase in Hcy levels (average level of Hcy in the general population about 10-15 μmol/L versus 25-35 μmol/L in uremic patients), the role of Hcy as a cardiovascular risk and mortality factor is still uncertain and many retrospective and interventional studies have given rise to conflicting evidence [48].

 

Folic acid supplementation in patients suffering from CKD

There is a large body of evidence indicating that folate therapy improves HHcy in the general population, but the data is less clear in CKD and ERSD patients [39,49]. The main interventional studies on the use of folic acid and vitamin B12 in CKD patients are summarized in Table 1. The benefits of folate supplementation in subjects with reduced renal function do not seem to lie entirely in the lowering of serum Hcy. Endothelial dysfunction is a key process in atherosclerosis and independently predicts cardiovascular events. High-dose FA (5 mg per day), alone or in combination with other B vitamins, appears to improve endothelial function through a largely Hcy-independent mechanism [50]. Endothelial cells can be particularly vulnerable to HHcy, as they do not express CBS, the first enzyme of the transsulfuration pathway [51]. Therefore, endothelial cells can eliminate Hcy only through remethylation, and normal activity of the enzymatic route is thus essential to prevent the increase of Hcy to a pathological level [52]. FA improves endothelial function by reducing intravascular oxidative stress; also improves intracellular superoxide generation by increasing the half-life of NO [53]. Folate therapy reduces but does not normalizes Hcy levels, frequently elevated in CKD patients. The mechanisms of this folate resistance have not been fully elucidated, yet. The entry of folate into the cell is mediated by specific folate receptors, whose expression is also modulated by the folate state, through an Hcy-dependent regulation mechanism. In peripheral mononuclear cells of hemodialysis patients, FR2 expression decreased and did not respond to changes in Hcy concentration [54].

 

Use of folate and vitamin B12 in the prevention of cardiovascular mortality and in slowing the progression of CKD

The role of folic acid and vitamin B12 supplementation in reducing mortality and preventing progression to ESRD is still to be determined. According to the meta-analysis of Heinz et al. of retrospective, prospective and observational studies on total 5123 patients, HHcy emerged as a risk factor for cardiovascular events and mortality in ESRD, especially in those subjects who do not receive additional FA (in countries without fortification programmes). Prospective studies have shown that in patients with ESRD, a 5 μmol/L increase in Hcy concentration is associated with a 7% increase in the risk of total mortality and a 9% increase in the risk of cardiovascular events. The level of Hcy in these patients seems to have decreased of 13 to 31 μmol/L due to supplementation with B vitamins in intervention studies. This was associated with a 27% reduction in the risk of cardiovascular events, although mortality had not decreased [55].

The minimum dose of folic acid to achieve a reduction of Hcy is debated: non-diabetic ESRD patients can respond to a daily dose of 5 mg FA, but diabetic patients with ESRD may need up to 15 mg to reduce the Hcy level more than 20% and have benefits on CVD risk, regardless of FA fortification. In addition, simultaneous administration with vitamin B12 is more effective in counteracting HHcy [56]. In non-diabetic patients with mild to moderate CKD a treatment strategy with pravastatin, vitamin E and Hcy reduction therapy (vitamin B12 and folate) leads to a significant reduction in the progression of carotid stenosis and a significant improvement in endothelial function and urinary excretion of albumin. However, no significant effect on the eGFR has been observed [57]. Similar results have emerged in the meta-analysis of Quin et al. including studies carried out from 1966 to 2011, for a total of 3886 patients with ESRD and CKD, where the relationship between supplementation with B12, FA and CVD had been analyzed after 24 months of treatment. FA therapy reduced the risk of CVD by 15%. Greater benefits were observed in those trials with a treatment duration >24 months, a decrease in Hcy level >20% (P = 0.007), and no or partial FA fortification (P = 0.04). The positive effect was seen when Hcy levels decreased >20%, even in the presence of FA fortification [58]. However, a reduction in Hcy secondary to high-dose FA therapy does not correspond to an increase in survival nor to a reduction of cardiovascular events according to randomized double-blind studies [59]. In the meta-analysis by Pan et al. (10 studies of patients in CKD), Hcy-lowering therapy is not associated with reduction of CVD, stroke and all-cause mortality [60]. However, the cohort of patients recruited had a high number of diabetic patients from areas with a grain fortification program.

Although HHcy is associated with increased CKD progression and albuminuria [61], the DIVINE study investigated the effects of Hcy-lowering therapy with high doses of folate (40 mg/day), vitamin B12 (1000 mg/day) and vitamin B6 (2 mg/day) in patients with diabetic nephropathy and showed that this treatment regimen does not increase survival or slow progression in ESRD, but rather leads to a higher incidence of cardiovascular events and a greater decrease in eGFR [62]. A possible explanation for these negative results can be attributed to the high load of cardiovascular comorbidity and to suboptimal therapy compliance. In addition, the study considered the CKD and ESRD population together and not separately. The above-mentioned China Stroke Primary Prevention Trial (CSPPT), a large, randomized study among adults with high blood pressure without a history of stroke or myocardial infarction, found that a therapy with ACE inhibitors and FA significantly reduced the relative risk of first stroke by 21%, more than ACE inhibitors alone. Among individuals with MTHFR 677 CC or CT genotypes, those with the lowest basal folate levels have the highest risk of stroke and benefit the most from FA therapy. In addition, individuals with the TT genotype may require a higher dosage of FA to exceed biologically insufficient levels [37]. An exploratory analysis by subgroups to assess the effect of treatment on primary outcome in various subgroups of CKD participants showed that the reduction in the risk of CKD progression was more represented in the diabetes subgroup [63]. Of note, CSPPT study selected a population without fortification of cereals with folic acid.

Several factors including age, baseline Hcy levels, FA fortification of grains, B12 status, renal function, comorbidities, and medications could modify the effects of folic acid and vitamin B12 on cardiovascular risk. The available evidence regarding the effect of Hcy lowering therapies on CKD progression is controversial and further studies are needed, with CKD progression as primary endpoint and with a more homogeneous population selection [39].

 

The role of folate and vitamin B12 therapy

ESRD patients in chronic dialysis treatment

In many cases, the literature has shown that dialysis and ESRD patients are a peculiar population whose response to certain factors is opposite to that of the general population, a condition that has been called “reverse epidemiology” [64]. A curious example is hypocholesterolemia, identified as a predictor of higher mortality in dialysis patients [65]. Similarly, data from our group have previously shown that a higher BMI protects ESRD patients from coronary artery calcifications [66], in line with a meta-analysis by Lowrie et al, based on 43,334 hemodialysis patients, indicating an improved survival associated with increased BMI values [67].

In line with this theory, very low Hcy levels appear to be associated with worse clinical outcomes, longer hospitalization, and higher mortality from all causes, and cardiovascular mortality in ESRD patients [68]. The combined effect of protein-energy malnutrition and inflammation may partly explain the apparent paradox represented by the inverse relationship between Hcy level and mortality in patients with ESRD [14].

The study of Sohoo et al. examined a cohort of 12,968 hemodialysis patients treated with vitamin B12 for 5 years, to observe the relationship between serum folate/B12 and mortality. Concentrations of B12 ≥550 pg/mL are associated with increased mortality from all causes in hemodialysis patients, regardless of sociodemographic data and laboratory variables [12]. The effectiveness of high-dose folic acid in event prevention in ESRD was evaluated in a randomized study. A total of 510 patients on chronic dialysis were randomized to 1.5 or 15 mg of FA contained in a renal multivitamin with a median follow-up of 24 months. Composite mortality rates and cardiovascular events did not differ between the FA groups. High basal Hcy was associated with lower event rates, which would confirm an inverse relationship between Hcy and events in ESRD patients. The administration of FA at high doses did not affect event rates [69]. Similar studies have come to the same conclusion: the Atherosclerosis and Folic Acid Supplementation Trial (ASFAST) recruited a total of 315 subjects with chronic kidney failure (most of them in dialysis) who were randomized to 15 mg FA per day or placebo and followed for a median of 3.6 years. Total Hcy in plasma is reduced by 19% in the FA group but this does not slow down the progression of atherosclerosis nor improve morbidity or cardiovascular mortality in patients [57].

Supplementation with B vitamins along with FA could be an alternative in reducing vascular oxidative stress. However, the randomized multicenter study conducted in double-blind by Heinz et al. on 650 patients in hemodialysis undergoing supplementation with FA, vitamin B12 and vitamin B6, showed that such therapies did not reduce total mortality and had no significant effect on the risk of cardiovascular events in patients with end-stage kidney disease [62]. Normalization of Hcy levels is difficult to achieve in dialysis patients with FA alone: according to Righetti et al., only 12% of a cohort of 81 patients in chronic dialysis has reached normal levels of Hcy. However, this condition has again shown no benefit in terms of survival [70].

The changes in the uremic patient’s metabolism described in the previous sections leave an open question regarding FA and vitamin B12 supplementation in dialysis. Another study by Righetti suggested that folate therapy to lower Hcy can reduce cardiovascular events in dialysis patients [71]. In a study by our group on a population of 341 patients in chronic dialysis, group A was treated with 50 mg i.v. of 5-MTHF, and group B was treated with 5 mg/d of oral FA. Both groups received vitamin B6 and B12. Our data showed that I.V. 5-MTHF appears to improve survival in hemodialysis patients regardless of the lowering of Hcy [72]. This latest evidence confirms that the role of FA and vitamin B12 should be better understood in this category of patients, both at the biochemical level and at the level of clinical outcomes.

Study, year Duration, design Population Treatment Outcomes

Nanayakkara PW et al, 2007 [57]

2 yrs, double-blind RCT 93 patients with mild to moderate CKD Pravastatin, vitamin E, and homocysteine lowering therapy (daily 5 mg FA + 100 mg vitamin B6 + 1 mg vitamin B12) vs placebo

In the treatment group significant reduction in CC-IMT, increase in BA-FMD, improvement in endothelial function and urinary albumin excretion, no effect on eGFR

Jamison RL et al, 2008 [58]

7 yrs, double-blind RCT 2056 patients with CKD (n=1305) or ESRD (n=751) and HHcy (> 15 mmol/L) Daily 40 mg FA + 100 mg vitamin B6 + 2 mg vitamin B12 vs placebo

In the treatment group significant lowering of Hcy levels, no effect on secondary outcomes (MI, stroke, and amputations time to dialysis and mortality)

Zoungas S et al, 2006 [61]

3.6 yrs, double-blind RCT 315 patients with CKD Daily 15 mg FA vs placebo

In the treatment group lowering by 19% of Hcy levels, no effect on secondary outcomes (change of IMT, artery function MI, stroke, cardiovascular death and overall cardiovascular events)

Heinz J et al, 2010 [62]

6 yrs, double-blind RCT 650 ESRD patients under hemodialysis treatment 5 mg FA + 50 mg vitamin B12 + 20 mg vitamin B6 (active treatment) vs or 0.2 mg FA, 4 mg vitamin B12 + 1.0 mg vitamin B6 (placebo) 3 times/week for 2 yrs

No effect on total mortality and fatal or nonfatal cardiovascular events

Xu X et al, 2016 [63]

4.5 yrs, double-blind RCT 1671 patients with CKD Daily 10 mg enalapril + 0.8 mg FA (n=7545) vs 10 mg enalapril alone (n=7559)

In patients receiving enalapril + FA   the risk for CKD progression and the rate of eGFR decline were decreased by 56% and 44%, respectively

Wrone EM et al, 2004 [63]

2 yrs, RCT 510 ESRD patients under hemodialysis treatment Daily 1, 5, or 15 mg FA contained in a renal multivitamin

No effect of high-dose FA administration on the rates of cardiovascular events and mortality

Righetti M et al, 2003 [70]

1 yr, RCT 81 ESRD patients under hemodialysis treatment Daily 15 mg FA (n=25) vs 5 mg FA (n=26) vs untreated (n=30)

No significant improvement of HHcy, regardless of FA dose, but treated patients tended towards a decreased rate of cardiovascular events.

Righetti M et al, 2006 [71]

871 days (median follow-up, range 132-1825 days), single-center, open, randomized prospective trial 114 ESRD patients under hemodialysis treatment 5 mg daily FA, or 5 mg every other day (if serum FA levels were up the normal high limit of 16.8 ng/mL) + vitamin B complex (250 mg B1 + 250 mg B6 + 500 mg B12, if plasma vitamin B12 values were below the normal limit of 200 ng/L)

Lower rate of cardiovascular events in treated patients with low Hcy levels

Cianciolo G et al, 2008 [72]

55 months, randomized prospective study 341 ESRD patients under hemodialysis treatment Patients were randomized into two groups: group A (n=174) treated with I.V. 50 mg 5-MTHF (Prefolic) three times a week (end of each dialysis session) vs group B (n=167) treated with daily 5 mg FA. Both groups also received I.V. 300 mg vitamin + 1 g vitamin B12 at the end of the dialysis session.

Both FA acid and 5-MTHF decreased Hcy levels, and I.V. 5-MTHF improved survival in hemodialysis independent from Hcy lowering. CRP but not HHcy resulted to be the main risk factor for mortality in hemodialysis patients

Buccianti G et al, 2001 [74]

6 months, cross-sectional clinical study 55 ESRD patients under hemodialysis treatment 27 patients with macrocytosis treated the end of each dialysis session with I.V. 0.9 mg folinic acid + 0.5 mg cyanocobalamin + 1.5 mg hydroxycobalamin vs 28 untreated patients

Intermittent I.V. administration of folinic acid combined with vitamin B12 resulted in lower HHCy plasma concentration, but the effect was also related to genotype and dialysis modality

Bostom AG et al, 2011 [78]

5 yrs, multi-center

double-blind RCT

4110 stable kidney transplant recipients Participants were randomized to receive either a high dose (n=2056) of FA (5.0 mg), vitamin B6 (pyridoxine; 50 mg) and vitamin B12 (cyanocobalamin; 1.0 mg) or a low dose (n=2054) of vitamin B6 (1.4 mg) and vitamin B12 (2.0 µg) and no FA.

In the high dose treatment arm, a significant reduction in Hcy level was achieved, but without any beneficial impact on cardiovascular outcomes, all-cause mortality, or allograft failure

Table 1: Summary of major interventional studies on folic acid / vitamin B12 administration in patients with CKD

BA-FMD: brachial artery flow-mediated dilatation; CC-IMT: carotid intima-media thickness; CKD: chronic kidney disease; eGFR: estimated glomerular filtration rate; ESRD: end-stage renal disease; FA: folic acid; HHcy: homocysteinemia; I.V.: intravenous; MI: myocardial infarction; RCT: randomized controlled trial; yr(s): year(s)

Role of FA and B12 supplementation in CKD anemia

In uremia-related anemia, unless patients with CKD and ESRD show significant folate depletion, additional FA supplementation does not appear to have a beneficial effect on erythropoiesis or response to recombinant human erythropoietin therapy (rHuEPO). However, measurements of folate circulating in the serum do not necessarily reflect folate reserves in tissues, and folate measurements in red blood cells provide a more accurate representation. The low concentrations of folate in red blood cells in these patients suggest the need for FA supplement [73]. Megaloblastic anemia, that occurs in vitamin deficiencies frequently found in uremic patients, results from inhibition of DNA synthesis during the production of red blood cells [74]. When cobalamin levels become inadequate, DNA synthesis is compromised, and the cell cycle cannot progress from the G2 growth phase to the mitosis phase. This leads to continuous cell growth without division, and then to macrocytosis [14]. In patients with CKD, folate and vitamin B12 deficiency may represent an important factor in renal anemia and hyporesponsiveness to rHuEPO therapy [75].

Kidney transplant recipients

In kidney transplants, several factors such as dialysis vintage, anemia, immunosuppression, inflammatory state, and dysmetabolic alterations can affect the cardiovascular risk [76,77]. The effect of supplementation of FA, vitamin B12 and vitamin B6 on CVD and mortality reduction has been studied by the Folic Acid for Vascular Outcome Reduction in Transplantation (FAVORIT) study. Kidney transplant recipients were randomized to a daily multivitamin drug containing high doses of folate (5.0 mg), vitamin B12 (1.0 mg) and vitamin B6 (50 mg), or placebo. Despite the actual lowering the Hcy, the incidence of CVD, mortality from all causes and the onset of kidney failure dependent on dialysis did not differ between the two treatment arms [78]. A longitudinal ancillary study of the FAVORIT trial has recently indicated that the integration of high-dose B vitamins results in a modest cognitive benefit in patients with high base values. It should be noted that almost all subjects had no shortage of folate or B12, thus the potential cognitive benefits of folate and B12 supplementation in individuals with poor vitamin B status remain controversial [79].

 

Future perspectives and conclusion

At present, the results from available trials do not provide complete support for considering alterations in FA and vitamin B12 as reliable indices of CVD risk in CKD and ESRD population. Moreover, these factors do not represent a validated therapeutic target to cardiovascular risk reduction and CKD progression.

However, there is some evidence to indicate that the incidence of stroke and CKD progression might be controlled using more targeted FA therapy (baseline FA levels may have an impact on the efficacy of the FA intervention therapy), in particular among those with the MTHFR 677TT genotype and low to moderate folate levels and in countries without a grain fortification program [37,63]. However, in both general population and CKD patients, it remains a matter of debate if beneficial effects of FA therapy are due to its direct antioxidant effect or to a reduction in HHcy.

Discordant results in terms of CKD progression and cardiovascular risk, in the analyzed studies, result from differences in patient characteristics and FA treatment schemes among trials and may be influenced by the degree of cardiovascular and renal impairment.

In conclusion FA with or without vitamin B12 supplementation is an appropriate adjunctive therapy in patients with CKD and ESRD on dialysis treatment, in these cases FA may be supplemented pharmacologically after careful evaluation of folate status.

 

References

  1. Hill NR, Fatoba ST, Oke JL, Hirst JA, O’Callaghan CA, Lasserson DS, Hobbs FD. Global Prevalence of Chronic Kidney Disease – A Systematic Review and Meta-Analysis. PLoS One 2016 Jul 6; 11(7):e0158765. https://doi.org/10.1371/journal.pone.0158765
  2. Go AS, Chertow GM, Fan D, McCulloch CE, Hsu CY. Chronic kidney disease and the risks of death, cardiovascular events, and hospitalization. N Engl J Med 2004 Sep 23; 351(13):1296-305. https://doi.org/10.1056/NEJMoa041031. Erratum in: N Engl J Med 2008; 18(4):4.
  3. Bourrier M, Ferguson TW, Embil JM, Rigatto C, Komenda P, Tangri N. Peripheral Artery Disease: Its Adverse Consequences With and Without CKD. Am J Kidney Dis 2020 May; 75(5):705-712. https://doi.org/10.1053/j.ajkd.2019.08.028
  4. Chrysant SG, Chrysant GS. The current status of homocysteine as a risk factor for cardiovascular disease: a mini review. Expert Rev Cardiovasc Ther 2018 Aug; 16(8):559-565. https://doi.org/10.1080/14779072.2018.1497974
  5. McCully KS. Homocysteine and vascular disease. Nat Med 1996 Apr; 2(4):386-9. https://doi.org/10.1038/nm0496-386
  6. Toole JF, Malinow MR, Chambless LE, Spence JD, Pettigrew LC, Howard VJ, Sides EG, Wang CH, Stampfer M. Lowering homocysteine in patients with ischemic stroke to prevent recurrent stroke, myocardial infarction, and death: the Vitamin Intervention for Stroke Prevention (VISP) randomized controlled trial. JAMA 2004 Feb 4; 291(5):565-75. https://doi.org/10.1001/jama.291.5.565
  7. Lonn E, Yusuf S, Arnold MJ, Sheridan P, Pogue J, Micks M, McQueen MJ, Probstfield J, Fodor G, Held C, Genest J Jr; Heart Outcomes Prevention Evaluation (HOPE) 2 Investigators. Homocysteine lowering with folic acid and B vitamins in vascular disease. N Engl J Med 2006 Apr 13; 354(15):1567-77. https://doi.org/10.1056/NEJMoa060900. Erratum in: N Engl J Med 2006 Aug 17; 355(7):746.
  8. Marti F, Vollenweider P, Marques-Vidal PM, Mooser V, Waeber G, Paccaud F, Bochud M. Hyperhomocysteinemia is independently associated with albuminuria in the population-based CoLaus study. BMC Public Health 2011 Sep 26; 11:733. https://doi.org/10.1186/1471-2458-11-733
  9. Ponte B, Pruijm M, Marques-Vidal P, Martin PY, Burnier M, Paccaud F, Waeber G, Vollenweider P, Bochud M. Determinants and burden of chronic kidney disease in the population-based CoLaus study: a cross-sectional analysis. Nephrol Dial Transplant 2013 Sep; 28(9):2329-39. https://doi.org/10.1093/ndt/gft206
  10. House AA, Eliasziw M, Cattran DC, Churchill DN, Oliver MJ, Fine A, Dresser GK, Spence JD. Effect of B-vitamin therapy on progression of diabetic nephropathy: a randomized controlled trial. JAMA 2010 Apr 28; 303(16):1603-9. https://doi.org/10.1001/jama.2010.490
  11. Škovierová H, Vidomanová E, Mahmood S, Sopková J, Drgová A, Červeňová T, Halašová E, Lehotský J. The Molecular and Cellular Effect of Homocysteine Metabolism Imbalance on Human Health. Int J Mol Sci 2016 Oct 20; 17(10):1733. https://doi.org/10.3390/ijms17101733
  12. Soohoo M, Ahmadi SF, Qader H, Streja E, Obi Y, Moradi H, Rhee CM, Kim TH, Kovesdy CP, Kalantar-Zadeh K. Association of serum vitamin B12 and folate with mortality in incident hemodialysis patients. Nephrol Dial Transplant 2017 Jun 1; 32(6):1024-1032. https://doi.org/10.1093/ndt/gfw090
  13. Cianciolo G, De Pascalis A, Di Lullo L, Ronco C, Zannini C, La Manna G. Folic Acid and Homocysteine in Chronic Kidney Disease and Cardiovascular Disease Progression: Which Comes First? Cardiorenal Med 2017 Oct; 7(4):255-266. https://doi.org/10.1159/000471813
  14. Cappuccilli M, Bergamini C, Giacomelli FA, Cianciolo G, Donati G, Conte D, Natali T, La Manna G, Capelli I. Vitamin B Supplementation and Nutritional Intake of Methyl Donors in Patients with Chronic Kidney Disease: A Critical Review of the Impact on Epigenetic Machinery. Nutrients 2020 Apr 27; 12(5):1234. https://doi.org/10.3390/nu12051234
  15. Randaccio L, Geremia S, Demitri N, Wuerges J. Vitamin B12: unique metalorganic compounds and the most complex vitamins. Molecules 2010 Apr 30; 15(5):3228-59. https://doi.org/10.3390/molecules15053228
  16. Mahajan A, Sapehia D, Thakur S, Mohanraj PS, Bagga R, Kaur J. Effect of imbalance in folate and vitamin B12 in maternal/parental diet on global methylation and regulatory miRNAs. Sci Rep 2019 Nov 26; 9(1):17602. https://doi.org/10.1038/s41598-019-54070-9
  17. Froese DS, Fowler B, Baumgartner MR. Vitamin B12, folate, and the methionine remethylation cycle-biochemistry, pathways, and regulation. J Inherit Metab Dis 2019 Jul; 42(4):673-685. https://doi.org/10.1002/jimd.12009
  18. Buccianti G, Bamonti Catena F, Patrosso C, Corghi E, Novembrino C, Baragetti I, Lando G, De Franceschi M, Maiolo AT. Reduction of the homocysteine plasma concentration by intravenously administered folinic acid and vitamin B (12) in uraemic patients on maintenance haemodialysis. Am J Nephrol 2001 Jul-Aug; 21(4):294-9. https://doi.org/10.1159/000046264
  19. Kang SS, Wong PW, Malinow MR. Hyperhomocyst(e)inemia as a risk factor for occlusive vascular disease. Annu Rev Nutr 1992; 12:279-98. https://doi.org/10.1146/annurev.nu.12.070192.001431
  20. Yi F, Li PL. Mechanisms of homocysteine-induced glomerular injury and sclerosis. Am J Nephrol 2008; 28(2):254-64. https://doi.org/10.1159/000110876
  21. Long Y, Nie J. Homocysteine in Renal Injury. Kidney Dis (Basel) 2016 Jun; 2(2):80-7. https://doi.org/10.1159/000444900
  22. Langan RC, Goodbred AJ. Vitamin B12 Deficiency: Recognition and Management. Am Fam Physician 2017 Sep 15; 96(6):384-389. PMID: 28925645.
  23. Perna AF, Ingrosso D, Satta E, Lombardi C, Acanfora F, De Santo NG. Homocysteine metabolism in renal failure. Curr Opin Clin Nutr Metab Care 2004 Jan; 7(1):53-7. https://doi.org/10.1097/00075197-200401000-00010
  24. Perna AF, Sepe I, Lanza D, Capasso R, Di Marino V, De Santo NG, Ingrosso D. The gasotransmitter hydrogen sulfide in hemodialysis patients. J Nephrol 2010 Nov-Dec; 23 Suppl 16: S92-6. PMID: 21170893.
  25. van Guldener C, Stehouwer CD. Homocysteine metabolism in renal disease. Clin Chem Lab Med 2003 Nov; 41(11):1412-7. https://doi.org/10.1515/CCLM.2003.217
  26. Jennette JC, Goldman ID. Inhibition of the membrane transport of folates by anions retained in uremia. J Lab Clin Med 1975 Nov; 86(5):834-43. PMID: 1185041.
  27. McMahon GM, Hwang SJ, Tanner RM, Jacques PF, Selhub J, Muntner P, Fox CS. The association between vitamin B12, albuminuria and reduced kidney function: an observational cohort study. BMC Nephrol 2015 Feb 2; 16:7. https://doi.org/10.1186/1471-2369-16-7
  28. Koyama K, Yoshida A, Takeda A, Morozumi K, Fujinami T, Tanaka N. Abnormal cyanide metabolism in uraemic patients. Nephrol Dial Transplant 1997 Aug; 12(8):1622-8. https://doi.org/10.1093/ndt/12.8.1622. Erratum in: Nephrol Dial Transplant 1998 Mar; 13(3):819.
  29. Cheng X. Updating the relationship between hyperhomocysteinemia lowering therapy and cardiovascular events. Cardiovasc Ther 2013 Aug; 31(4):e19-26. https://doi.org/10.1111/1755-5922.12014
  30. Sazci A, Ergul E, Kaya G, Kara I. Genotype and allele frequencies of the polymorphic methylenetetrahydrofolate reductase gene in Turkey. Cell Biochem Funct 2005 Jan-Feb; 23(1):51-4. https://doi.org/10.1002/cbf.1132
  31. Cristalli, C.P.; Zannini, C.; Comai, G.; Baraldi, O.; Cuna, V.; Cappuccilli, M.; Mantovani, V.; Natali, N.; Cianciolo, G.; La Manna, G. Methylenetetrahydrofolate reductase, MTHFR, polymorphisms and predisposition to different multifactorial disorders. Genes Genomics 2017, 39, 689–699.
  32. Böttiger AK, Hurtig-Wennlöf A, Sjöström M, Yngve A, Nilsson TK. Association of total plasma homocysteine with methylenetetrahydrofolate reductase genotypes 677C>T, 1298A>C, and 1793G>A and the corresponding haplotypes in Swedish children and adolescents. Int J Mol Med 2007 Apr; 19(4):659-65. PMID: 17334642.
  33. Yun L, Xu R, Li G, Yao Y, Li J, Cong D, Xu X, Zhang L. Homocysteine and the C677T Gene Polymorphism of Its Key Metabolic Enzyme MTHFR Are Risk Factors of Early Renal Damage in Hypertension in a Chinese Han Population. Medicine (Baltimore) 2015 Dec; 94(52):e2389. https://doi.org/10.1097/MD.0000000000002389
  34. Trovato FM, Catalano D, Ragusa A, Martines GF, Pirri C, Buccheri MA, Di Nora C, Trovato GM. Relationship of MTHFR gene polymorphisms with renal and cardiac disease. World J Nephrol 2015 Feb 6; 4(1):127-37. https://doi.org/10.5527/wjn.v4.i1.127 .
  35. Malinow MR, Nieto FJ, Kruger WD, Duell PB, Hess DL, Gluckman RA, Block PC, Holzgang CR, Anderson PH, Seltzer D, Upson B, Lin QR. The effects of folic acid supplementation on plasma total homocysteine are modulated by multivitamin use and methylenetetrahydrofolate reductase genotypes. Arterioscler Thromb Vasc Biol 1997 Jun; 17(6):1157-62. https://doi.org/10.1161/01.atv.17.6.1157
  36. Tremblay R, Bonnardeaux A, Geadah D, Busque L, Lebrun M, Ouimet D, Leblanc M. Hyperhomocysteinemia in hemodialysis patients: effects of 12-month supplementation with hydrosoluble vitamins. Kidney Int 2000 Aug; 58(2):851-8. https://doi.org/10.1046/j.1523-1755.2000.00234.x
  37. Xu X, Qin X, Li Y, Sun D, Wang J, Liang M, Wang B, Huo Y, Hou FF; investigators of the Renal Substudy of the China Stroke Primary Prevention Trial (CSPPT). Efficacy of Folic Acid Therapy on the Progression of Chronic Kidney Disease: The Renal Substudy of the China Stroke Primary Prevention Trial. JAMA Intern Med 2016 Oct 1; 176(10):1443-1450. https://doi.org/10.1001/jamainternmed.2016.4687
  38. Brustolin S, Giugliani R, Félix TM. Genetics of homocysteine metabolism and associated disorders. Braz J Med Biol Res 2010 Jan; 43(1):1-7. https://doi.org/10.1590/s0100-879×2009007500021. Epub 2009 Dec 4. PMID: 19967264; PMCID: PMC3078648.
  39. Capelli I, Cianciolo G, Gasperoni L, Zappulo F, Tondolo F, Cappuccilli M, La Manna G. Folic Acid and Vitamin B12 Administration in CKD, Why Not? Nutrients 2019 Feb 13; 11(2):383. https://doi.org/10.3390/nu11020383
  40. Steed MM, Tyagi SC. Mechanisms of cardiovascular remodeling in hyperhomocysteinemia. Antioxid Redox Signal 2011 Oct 1; 15(7):1927-43. https://doi.org/10.1089/ars.2010.3721. Erratum in: Antioxid Redox Signal 2013 Feb 10; 18(5):601.
  41. Zhang X, Li H, Jin H, Ebin Z, Brodsky S, Goligorsky MS. Effects of homocysteine on endothelial nitric oxide production. Am J Physiol Renal Physiol 2000 Oct; 279(4):F671-8. https://doi.org/10.1152/ajprenal.2000.279.4.F671
  42. Poddar R, Sivasubramanian N, DiBello PM, Robinson K, Jacobsen DW. Homocysteine induces expression and secretion of monocyte chemoattractant protein-1 and interleukin-8 in human aortic endothelial cells: implications for vascular disease. Circulation 2001 Jun 5; 103(22):2717-23. https://doi.org/10.1161/01.cir.103.22.2717
  43. Zeng XK, Guan YF, Remick DG, Wang X. Signal pathways underlying homocysteine-induced production of MCP-1 and IL-8 in cultured human whole blood. Acta Pharmacol Sin 2005 Jan; 26(1):85-91. https://doi.org/10.1111/j.1745-7254.2005.00005.x
  44. Thampi P, Stewart BW, Joseph L, Melnyk SB, Hennings LJ, Nagarajan S. Dietary homocysteine promotes atherosclerosis in apoE-deficient mice by inducing scavenger receptors expression. Atherosclerosis 2008 Apr; 197(2):620-9. https://doi.org/10.1016/j.atherosclerosis.2007.09.014
  45. Tsai JC, Perrella MA, Yoshizumi M, Hsieh CM, Haber E, Schlegel R, Lee ME. Promotion of vascular smooth muscle cell growth by homocysteine: a link to atherosclerosis. Proc Natl Acad Sci U S A 1994 Jul 5; 91(14):6369-73. https://doi.org/10.1073/pnas.91.14.6369
  46. Deussen A, Pexa A, Loncar R, Stehr SN. Effects of homocysteine on vascular and tissue adenosine: a stake in homocysteine pathogenicity? Clin Chem Lab Med 2005; 43(10):1007-10. https://doi.org/10.1515/CCLM.2005.176
  47. Colì L, Donati G, Cappuccilli ML, Cianciolo G, Comai G, Cuna V, Carretta E, La Manna G, Stefoni S. Role of the hemodialysis vascular access type in inflammation status and monocyte activation. Int J Artif Organs 2011 Jun; 34(6):481-8. https://doi.org/10.5301/IJAO.2011.8466
  48. Suliman ME, Stenvinkel P, Jogestrand T, Maruyama Y, Qureshi AR, Bárány P, Heimbürger O, Lindholm B. Plasma pentosidine and total homocysteine levels in relation to change in common carotid intima-media area in the first year of dialysis therapy. Clin Nephrol 2006 Dec; 66(6):418-25. https://doi.org/10.5414/cnp66418
  49. Perna AF, De Santo NG, Ingrosso D. Adverse effects of hyperhomocysteinemia and their management by folic acid. Miner Electrolyte Metab 1997; 23(3-6):174-8. PMID: 9387111.
  50. Doshi SN, McDowell IF, Moat SJ, Payne N, Durrant HJ, Lewis MJ, Goodfellow J. Folic acid improves endothelial function in coronary artery disease via mechanisms largely independent of homocysteine lowering. Circulation 2002 Jan 1; 105(1):22-6. https://doi.org/10.1161/hc0102.101388
  51. Finkelstein JD. Methionine metabolism in mammals. J Nutr Biochem 1990 May; 1(5):228-37. https://doi.org/10.1016/0955-2863(90)90070-2
  52. Debreceni B, Debreceni L. The role of homocysteine-lowering B-vitamins in the primary prevention of cardiovascular disease. Cardiovasc Ther 2014 Jun; 32(3):130-8. https://doi.org/10.1111/1755-5922.12064
  53. Stroes ES, van Faassen EE, Yo M, Martasek P, Boer P, Govers R, Rabelink TJ. Folic acid reverts dysfunction of endothelial nitric oxide synthase. Circ Res 2000 Jun 9; 86(11):1129-34. https://doi.org/10.1161/01.res.86.11.1129
  54. Perna AF, Lanza D, Sepe I, Conzo G, Altucci L, Ingrosso D. Altered folate receptor 2 expression in uraemic patients on haemodialysis: implications for folate resistance. Nephrol Dial Transplant 2013 May; 28(5):1214-24. https://doi.org/10.1093/ndt/gfs510
  55. Heinz J, Kropf S, Luley C, Dierkes J. Homocysteine as a risk factor for cardiovascular disease in patients treated by dialysis: a meta-analysis. Am J Kidney Dis 2009 Sep; 54(3):478-89. https://doi.org/10.1053/j.ajkd.2009.01.266
  56. Wu CC, Zheng CM, Lin YF, Lo L, Liao MT, Lu KC. Role of homocysteine in end-stage renal disease. Clin Biochem 2012 Nov; 45(16-17):1286-94. https://doi.org/10.1016/j.clinbiochem.2012.05.031
  57. Nanayakkara PW, van Guldener C, ter Wee PM, Scheffer PG, van Ittersum FJ, Twisk JW, Teerlink T, van Dorp W, Stehouwer CD. Effect of a treatment strategy consisting of pravastatin, vitamin E, and homocysteine lowering on carotid intima-media thickness, endothelial function, and renal function in patients with mild to moderate chronic kidney disease: results from the Anti-Oxidant Therapy in Chronic Renal Insufficiency (ATIC) Study. Arch Intern Med 2007 Jun 25; 167(12):1262-70. https://doi.org/10.1001/archinte.167.12.1262
  58. Qin, X., Huo, Y., Langman, C. B., Hou, F., Chen, Y., Matossian, D., Xu, X., & Wang, X. (2011). Folic acid therapy and cardiovascular disease in ESRD or advanced chronic kidney disease: a meta-analysis. CJASN; 6(3):482–488. https://doi.org/10.2215/CJN.05310610
  59. Jamison RL, Hartigan P, Kaufman JS, Goldfarb DS, Warren SR, Guarino PD, Gaziano JM; Veterans Affairs Site Investigators. Effect of homocysteine lowering on mortality and vascular disease in advanced chronic kidney disease and end-stage renal disease: a randomized controlled trial. JAMA 2007 Sep 12; 298(10):1163-70. https://doi.org/10.1001/jama.298.10.1163. Erratum in: JAMA 2008 Jul 9; 300(2):170. PMID: 17848650.
  60. Pan Y, Guo LL, Cai LL, Zhu XJ, Shu JL, Liu XL, Jin HM. Homocysteine-lowering therapy does not lead to reduction in cardiovascular outcomes in chronic kidney disease patients: a meta-analysis of randomised, controlled trials. Br J Nutr 2012 Aug; 108(3):400-7. https://doi.org/10.1017/S0007114511007033
  61. Zoungas S, McGrath BP, Branley P, Kerr PG, Muske C, Wolfe R, Atkins RC, Nicholls K, Fraenkel M, Hutchison BG, Walker R, McNeil JJ. Cardiovascular morbidity and mortality in the Atherosclerosis and Folic Acid Supplementation Trial (ASFAST) in chronic renal failure: a multicenter, randomized, controlled trial. J Am Coll Cardiol 2006 Mar 21; 47(6):1108-16. https://doi.org/10.1016/j.jacc.2005.10.064
  62. Heinz J, Kropf S, Domröse U, Westphal S, Borucki K, Luley C, Neumann KH, Dierkes J. B vitamins and the risk of total mortality and cardiovascular disease in end-stage renal disease: results of a randomized controlled trial. Circulation 2010 Mar 30; 121(12):1432-8. https://doi.org/10.1161/CIRCULATIONAHA.109.904672
  63. Xu X, Qin X, Li Y, Sun D, Wang J, Liang M, Wang B, Huo Y, Hou FF; investigators of the Renal Substudy of the China Stroke Primary Prevention Trial (CSPPT). Efficacy of Folic Acid Therapy on the Progression of Chronic Kidney Disease: The Renal Substudy of the China Stroke Primary Prevention Trial. JAMA Intern Med 2016 Oct 1; 176(10):1443-1450. https://doi.org/10.1001/jamainternmed.2016.4687
  64. Suliman M, Stenvinkel P, Qureshi AR, Kalantar-Zadeh K, Bárány P, Heimbürger O, Vonesh EF, Lindholm B. The reverse epidemiology of plasma total homocysteine as a mortality risk factor is related to the impact of wasting and inflammation. Nephrol Dial Transplant 2007 Jan; 22(1):209-17. https://doi.org/10.1093/ndt/gfl510
  65. Chmielewski M, Verduijn M, Drechsler C, Lindholm B, Stenvinkel P, Rutkowski B, Boeschoten EW, Krediet RT, Dekker FW. Low cholesterol in dialysis patients–causal factor for mortality or an effect of confounding? Nephrol Dial Transplant 2011 Oct; 26(10):3325-31. https://doi.org/10.1093/ndt/gfr008
  66. Cianciolo G, La Manna G, Donati G, Persici E, Dormi A, Cappuccilli ML, Corsini S, Fattori R, Russo V, Nastasi V, Colì L, Wratten M, Stefoni S. Coronary calcifications in end-stage renal disease patients: a new link between osteoprotegerin, diabetes and body mass index? Blood Purif 2010; 29(1):13-22. https://doi.org/10.1159/000245042
  67. Lowrie EG, Li Z, Ofsthun N, Lazarus JM. Body size, dialysis dose and death risk relationships among hemodialysis patients. Kidney Int 2002 Nov; 62(5):1891-7. https://doi.org/10.1046/j.1523-1755.2002.00642.x
  68. Kalantar-Zadeh K, Block G, Humphreys MH, McAllister CJ, Kopple JD. A low, rather than a high, total plasma homocysteine is an indicator of poor outcome in hemodialysis patients. J Am Soc Nephrol 2004 Feb; 15(2):442-53. https://doi.org/10.1097/01.asn.0000107564.60018.51
  69. Wrone EM, Hornberger JM, Zehnder JL, McCann LM, Coplon NS, Fortmann SP. Randomized trial of folic acid for prevention of cardiovascular events in end-stage renal disease. J Am Soc Nephrol 2004 Feb; 15(2):420-6. https://doi.org/10.1097/01.asn.0000110181.64655.6c
  70. Righetti M, Ferrario GM, Milani S, Serbelloni P, La Rosa L, Uccellini M, Sessa A. Effects of folic acid treatment on homocysteine levels and vascular disease in hemodialysis patients. Med Sci Monit 2003 Apr; 9(4):PI19-24. PMID: 12709680.
  71. Righetti M, Serbelloni P, Milani S, Ferrario G. Homocysteine-lowering vitamin B treatment decreases cardiovascular events in hemodialysis patients. Blood Purif 2006; 24(4):379-86. https://doi.org/10.1159/000093680
  72. Cianciolo G, La Manna G, Colì L, Donati G, D’Addio F, Persici E, Comai G, Wratten M, Dormi A, Mantovani V, Grossi G, Stefoni S. 5-methyltetrahydrofolate administration is associated with prolonged survival and reduced inflammation in ESRD patients. Am J Nephrol 2008; 28(6):941-8. https://doi.org/10.1159/000142363
  73. Bamgbola, O.F. Pattern of resistance to erythropoietin-stimulating agents in chronic kidney disease. Kidney Int 2011, 80, 464–474.
  74. Buccianti G, Bamonti Catena F, Patrosso C, Corghi E, Novembrino C, Baragetti I, Lando G, De Franceschi M, Maiolo AT. Reduction of the homocysteine plasma concentration by intravenously administered folinic acid and vitamin B(12) in uraemic patients on maintenance haemodialysis. Am J Nephrol 2001 Jul-Aug; 21(4):294-9. https://doi.org/10.1159/000046264
  75. Saifan C, Samarneh M, Shtaynberg N, Nasr R, El-Charabaty E, El-Sayegh S. Treatment of confirmed B12 deficiency in hemodialysis patients improves Epogen® requirements. Int J Nephrol Renovasc Dis 2013 Jun 5; 6:89-93. https://doi.org/10.2147/IJNRD.S44660
  76. La Manna G, Cappuccilli ML, Cianciolo G, Conte D, Comai G, Carretta E, Scolari MP, Stefoni S. Cardiovascular disease in kidney transplant recipients: the prognostic value of inflammatory cytokine genotypes. Transplantation 2010 Apr 27; 89(8):1001-8. https://doi.org/10.1097/TP.0b013e3181ce243f
  77. Korogiannou M, Xagas E, Marinaki S, Sarafidis P, Boletis JN. Arterial Stiffness in Patients With Renal Transplantation; Associations With Co-morbid Conditions, Evolution, and Prognostic Importance for Cardiovascular and Renal Outcomes. Front Cardiovasc Med 2019; 6:67. Published 2019 May 24. https://doi.org/10.3389/fcvm.2019.00067
  78. Bostom AG, Carpenter MA, Kusek JW, Levey AS, Hunsicker L, Pfeffer MA, Selhub J, Jacques PF, Cole E, Gravens-Mueller L, House AA, Kew C, McKenney JL, Pacheco-Silva A, Pesavento T, Pirsch J, Smith S, Solomon S, Weir M. Homocysteine-lowering and cardiovascular disease outcomes in kidney transplant recipients: primary results from the Folic Acid for Vascular Outcome Reduction in Transplantation trial. Circulation 2011 Apr 26; 123(16):1763-70. https://doi.org/10.1161/CIRCULATIONAHA.110.000588
  79. Scott TM, Rogers G, Weiner DE, Livingston K, Selhub J, Jacques PF, Rosenberg IH, Troen AM. B-Vitamin Therapy for Kidney Transplant Recipients Lowers Homocysteine and Improves Selective Cognitive Outcomes in the Randomized FAVORIT Ancillary Cognitive Trial. J Prev Alzheimers Dis 2017; 4(3):174-182. https://doi.org/10.14283/jpad.2017.15

Which is the role of the oral iron therapies for iron deficiency anemia in non-dialysis-dependent chronic kidney disease patients? Results from clinical experience

Abstract

Iron deficiency afflicts about 60% of dialysis patients and about 30% of non-dialysis-dependent CKD patients (ND-CKD). The role of iron deficiency in determining anemia in CKD patients is so relevant that guidelines from the Kidney Disease Improving Global Outcomes (KDIGO) initiative recommend treating it before starting with erythropoiesis-stimulating agents. KDIGO guidelines suggest oral iron therapy because it is commonly available and inexpensive, although it is often characterized by low bioavailability and low compliance due to adverse effects.

A new-generation oral iron therapy is now available and seems to be promising. We therefore conducted a study to determine whether an association of iron sucrose, folic acid and vitamins C, B6, B12, can improve anemia in ND-CKD patients, stage 3-5. Our study shows that iron sucrose is a safe and effective oral iron therapy and that it is capable of correcting anemia in ND-CKD patients, although it does not seem to replete low iron stores.

Keywords: iron deficiency, chronic kidney disease, CKD, anemia, oral iron

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Introduzione

La carenza marziale, associata o meno all’anemia, rappresenta una delle condizioni più frequenti dei pazienti affetti da malattia renale cronica (MRC), siano essi in terapia conservativa o in terapia dialitica sostitutiva [1,2].

La carenza marziale è definita dalla Organizzazione Mondiale della Sanità come una condizione caratterizzata da una quantità di ferro insufficiente a mantenere la fisiologica funzione di sangue, cervello e muscoli. Essa non sempre si associa ad anemia, soprattutto se il deficit non è sufficientemente severo o è di recente insorgenza [3].

 

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Covid-19 vaccination and renal patients: overcoming unwarranted fears and re-establishing priorities

Abstract

The SARS-CoV-2 (Covid-19) has infected about 124 million people worldwide and the total amount of casualties now sits at a staggering 2.7 million. One enigmatic aspect of this disease is the protean nature of the clinical manifestations, ranging from total absence of symptoms to extremely severe cases with multiorgan failure and death.

Chronic Kidney Disease (CKD) has emerged as the primary risk factor in the most severe patients, apart from age. Kidney disease and acute kidney injury have been correlated with a higher risk of death. Notably the Italian Society of Nephrology have reported a 10-fold increase in mortality in patients undergoing dialysis compared to the rest of the population, especially during the second phase of the pandemic (26% vs 2.4). These dramatic numbers require an immediate response.

At the moment of writing, three Covid-19 vaccines are being administered already , two of which, Pfizer-BioNTech and Moderna,  share the same mrna mechanism and Vaxzevria (AstraZeneca) based on a more traditional approach.  All of them are completely safe and reliable. The AIFA scientific commission has suggested that the mRNA vaccines should be administered to older and more fragile patients, while the Vaxzevria (AstraZeneca) vaccine should be reserved for younger subjects above the age of 18. The near future looks bright: there are tens of other vaccines undergoing clinical and preclinical validation, whose preliminary results look promising.

The high mortality of CKD and dialysis patients contracting Covid-19 should mandate top priority for their vaccination.

 

Keywords: SARS-CoV-2 (Covid-19), chronic kidney disease, vaccine

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Introduzione

L’infezione da SARS-CoV-2 (Covid-19) ha colpito circa 124 milioni di persone nel mondo e si contano a tutt’oggi circa 2.7 milioni di decessi. Una caratteristica ancora enigmatica di tale infezione è l’ampia gamma di manifestazioni cliniche che variano dalla pressoché totale assenza di sintomi a forme estremamente gravi con compromissione multiorgano dall’esito inesorabilmente fatale [1]. L’elevata frequenza di infezioni asintomatiche inoltre ha indubbiamente contribuito alla rapida diffusione mondiale di SARS-CoV-2. Il principale quesito clinico a cui dare una risposta resta quindi ancora strettamente legato alla individuazione precoce dei soggetti ad alto rischio di sviluppare malattia grave. Questi individui possono trarre particolare vantaggio dall’isolamento precauzionale e soprattutto essere un gruppo prioritario per la vaccinazione [1].

 

Sebbene l’età sia il principale fattore di rischio, è stato osservato che anche gli anziani possono essere asintomatici, paucisintomatici o presentare una malattia lieve dando origine a ulteriore diffusione del virus [2].

Il livello di esposizione al virus e la carica virale, nonché fattori genetici e immunologici ancora non del tutto delineati, molto probabilmente giocano un ruolo importante, ma è stato sicuramente osservato che alcune patologie concomitanti predispongano con una elevata probabilità a sviluppare una forma di malattia più grave e spesso mortale. Diabete, ipertensione e malattie cardiovascolari sono stati elencati come fattori di rischio per forma grave di malattia sin dalla prima segnalazione nel gennaio 2020 [2].

Analizzando infatti i dati di oltre 65.000 pazienti provenienti da 25 studi in tutto il mondo, è stato evidenziato che il rischio di morte per Covid-19 viene raddoppiato dalla presenza di altre condizioni preesistenti, in particolar modo le patologie cardiovascolari. Questo risultato è stato ottenuto grazie a una ricerca nei database MEDLINE, SCOPUS, OVID, Cochrane Library e medrxiv.org dal 1° dicembre 2019 al 9 luglio 2020.

Soltanto più recentemente, la malattia renale cronica (CKD) è stata individuata come il fattore di rischio più comune, dopo l’età avanzata, per forma severa di malattia. È emerso infatti che i soggetti affetti da CKD presentano un rischio di mortalità tre volte maggiore rispetto alla popolazione generale [3,4].

 

Malattia renale e suscettibilità alle infezioni

I pazienti affetti da malattia renale, acuta e cronica, generalmente presentano di per sé un’aumentata mortalità rispetto alla popolazione generale [5], a causa di problemi correlati all’aumentato rischio di sviluppare malattie cardiovascolari e tumorali, ma anche sicuramente alla maggiore incidenza di complicanze infettive.

È stato osservato che i pazienti affetti da CKD non in dialisi hanno un rischio 3-4 volte maggiore dei pazienti con normale funzione renale di essere ricoverati per cause infettive, rischio che diventa 8 volte maggiore nei pazienti dializzati [6]. Inoltre, i pazienti affetti da CKD presentano una mortalità maggiore per polmonite rispetto alla popolazione generale [7]. Peraltro, lo stress fisiologico causato dalla risposta infiammatoria a un processo infettivo potrebbe ulteriormente indebolire organi già deficitari a causa della malattia renale o peggiorare la funzione renale stessa [5].

Le cause di questa maggiore predisposizione possono essere molteplici e, in particolare, non vanno dimenticate le patologie alla base della CKD, come per esempio il diabete mellito o le glomerulonefriti a genesi autoimmune, per citarne alcune; tali comorbilità possono giustificare un deficit immunitario di per sé o in ragione delle terapie messe in atto. Inoltre, la stasi di fluidi a livello polmonare, caratteristica dello scompenso cardiaco (spesso associato alla CKD) o dell’uremia terminale, sono una ragione ulteriore di abbassamento delle difese locali.

Il deficit immunitario dei pazienti insufficienti renali sembra essere correlato a un deficit delle cellule presentanti l’antigene (APC), che impediscono un’adeguata attivazione T-cellulare, più che a un deficit specifico di questa popolazione linfocitaria. Tale deficit può spiegare infatti anche una ridotta risposta ai vaccini antivirali da parte dei pazienti CKD [8]. Inoltre, tali pazienti presentano anche un elevato grado di infiammazione sistemica multi-fattoriale che sopprime a sua volta la risposta immunitaria, oltre ad avere grosse implicazioni cardiovascolari, come detto sopra [9].

Ciononostante, la vaccinazione antinfluenzale sembra essere efficace nel ridurre significativamente la mortalità nei pazienti dializzati [10] e insufficienti renali in stadio avanzato, per cui ormai da anni le linee guida KDIGO la raccomandano per tutti i pazienti affetti da CKD, salvo controindicazioni specifiche [11].

 

Malattia renale e infezione da SARS-CoV-2 (Covid-19)

Nel caso di SARS-CoV-2 l’ipotesi di una particolare suscettibilità all’infezione e allo sviluppo di complicanze più gravi da parte dei pazienti affetti da malattia renale risulta ulteriormente coerente con il fatto che rene e cuore presentano la più alta espressione di recettori ACE2, a cui è stato appunto dimostrato che il virus si lega [12]. Questo si traduce clinicamente in forme più importanti di infezione e maggior tasso di ospedalizzazione e mortalità nei pazienti che presentano una preesistente nefropatia.

L’infezione da SARS-CoV-2 può essere essa stessa causa di danno renale acuto (AKI), ma è sicuramente un fattore di rischio indipendente di elevata mortalità nei pazienti con nefropatia preesistente. I recettori ACE2, il danno virale diretto e il danno immuno-mediato svolgono ruoli importanti nella correlazione tra malattia renale e infezione severa [3]. L’AKI nel corso dell’infezione potrebbe derivare dall’effetto sinergico citotropico del virus e dalla risposta sistemica infiammatoria secondaria all’attivazione citochinica. Sono stati riportati casi di Collapsing Glomerulopathy in alcune biopsie renali di pazienti, come variante della glomerulosclerosi segmentale focale indotta dal danno virale [13,14].

L’incidenza di AKI in base agli studi epidemiologici disponibili è infatti significativamente più alta nel contesto di infezione più severa [1517]. Altri possibili meccanismi responsabili di AKI potrebbero essere ricondotti a necrosi tubulare acuta (ATN), a insufficienza multiorgano e a stato di shock. Anche la tossicità delle terapie e l’eventuale esposizione al mezzo di contrasto per esami di imaging possono certamente svolgere un ruolo [18].

L’impatto dell’infezione da SARS-CoV-2 sulla CKD è parimenti molto importante. Numerosi studi hanno documentato una mortalità significativamente maggiore in questa coorte di pazienti. È stata riportato che l’incidenza di AKI è sicuramente più elevata nei pazienti già affetti da CKD. Per contro, l’incidenza di CKD residuata in seguito a danno renale acuto in corso di Covid-19 è risultata variabile dallo 0,7-47,6%, in base agli studi effettuati [19,20].

È stato inoltre osservato che la malattia renale e il danno renale acuto sono sicuramente associati a un più alto rischio di morte nei pazienti Covid-19. Un recente studio condotto nel Regno Unito in ambiente intensivo ha infatti esaminato l’associazione tra malattia renale ed esiti clinici sfavorevoli nei pazienti con Covid-19. Il lavoro, condotto all’Imperial College di Londra, ha contato 372 pazienti affetti da Covid-19 (per il 72% uomini, media di circa 60 anni) ricoverati in terapia intensiva in quattro ospedali in UK dal 10 marzo al 23 luglio 2020 [21]. Nel 58% (216) dei pazienti è stata riscontrata insufficienza renale in diverso stadio. Nel 45% si è assistito all’insorgenza di danno renale acuto (AKI), mentre il 13% era già noto per una nefropatia preesistente. Nei pazienti che hanno presentato AKI, non era nota alcuna malattia renale antecedente al loro ricovero in terapia intensiva, suggerendo che il danno sia stato direttamente indotto dall’infezione. La mortalità osservata è stata invece assolutamente maggiore nel gruppo con malattia renale preesistente, confermando questa come uno dei fattori di rischio principali per lo sviluppo di infezione grave a prognosi sfavorevole [21].

La medesima evidenza è stata confermata da Fominskiy et al [22] in uno studio condotto su 195 pazienti affetti da Covid-19 e ricoverati presso reparti di terapia intensiva dell’IRCCS Ospedale San Raffaele di Milano nel corso della prima ondata. È stato infatti riportato che 3 su 4 pazienti sottoposti a ventilazione invasiva hanno sviluppato danno renale acuto, di cui 1 su 6 è stato trattato con terapia renale sostitutiva in continuo (CRRT). I pazienti con AKI hanno presentato una mortalità approssimativamente del 40% e i pazienti trattati con CRRT di circa il 50% [22].

Gli studi hanno confermato l’età avanzata come importante fattore di rischio per AKI e necessità di CRRT, ma tale fattore di rischio è risultato nettamente aumentato se in presenza di preesistente nefropatia, confermando l’insufficienza renale come fattore prognostico assolutamente sfavorevole di per sé [15,23,24].

Certamente va ricordato che molti pazienti con malattia renale cronica presentano comorbilità multiple come diabete e ipertensione, che possono ulteriormente predisporli a Covid-19. Una recente meta-analisi ha mostrato infatti che circa il 20% dei pazienti con CKD che hanno contratto Covid-19 soffriva contestualmente di altre patologie gravi con un rischio 3 volte superiore rispetto però a quelli senza CKD [25].

Va segnalato inoltre l’impatto del Covid-19 sulla popolazione di nefropatici nel nostro paese. Gli effetti dell’epidemia sui pazienti dializzati, secondo quanto evidenziato e riportato da un’indagine dalla Società Italiana di Nefrologia, sono stati decisamente importanti. Fra i dializzati si è infatti registrata una mortalità dieci volte superiore a quella a oggi stimata nella popolazione generale, soprattutto durante la seconda fase della pandemia (26% vs 2.4%) [26]. L’analisi è stata condotta su pazienti con malattia renale in stadio avanzato, pazienti in emodialisi, emodialisi domiciliare, dialisi peritoneale e trapiantati. I dati hanno documentato che nel corso della seconda ondata il numero totale dei pazienti affetti da insufficienza renale con tampone positivo è quadruplicato: il numero dei pazienti in emodialisi positivi è passato dal 3,4% della prima ondata all’11,6% della seconda ondata; il numero dei pazienti in dialisi peritoneale e domiciliare è andato dall’1,3% al 6,8%. È stato documentato inoltre un picco pure per i pazienti trapiantati, la cui positività è passata dallo 0.8% al 5%. I dati rilevati hanno inoltre documentato un rischio di mortalità estremamente elevato per i malati affetti da CKD (soprattutto dializzati e trapiantati).

Con particolare riferimento ai pazienti trapiantati di rene, è noto da precedenti epidemie di coronavirus diverse da Covid-19 come questi pazienti siano particolarmente suscettibili, anche in relazione alle concomitanti terapie immunosoppressive [27,28]. I pazienti trapiantati sono a maggior rischio di infezione, in particolare per la depressione della risposta immunitaria T-cellulare secondaria all’immunosoppressione. Il rischio è più elevato durante i primi 3 mesi dopo il trapianto, in particolare se i pazienti ricevono una terapia di induzione con agenti che riducono i linfociti [29,30]. Pertanto, durante la pandemia Covid-19, il trapianto di rene elettivo deve essere eseguito con cautela e spesso ritardato.

Nei casi di Covid-19 relativi a pazienti trapiantati sono stati descritti sintomi iniziali lievi, come febbre di basso grado, tosse lieve e normale conteggio dei globuli bianchi, verosimilmente a causa dell’effetto inibitorio della terapia immunosoppressiva sulla tempesta citochinica [29]. Quindi, anche i sintomi lievi o atipici non dovrebbero essere sottovalutati e non possono escludere un successivo decorso insidioso e dall’esito fatale.

Pertanto, i pazienti affetti da insufficienza renale rappresentano realmente una coorte di soggetti estremamente a rischio a cui è necessario prestare massima attenzione, adottando ogni sforzo per prevenire la progressione della malattia o del danno al fine di ridurne la mortalità. L’elevata prevalenza di CKD in combinazione con l’elevato rischio di mortalità da SARS-CoV-2 richiede quindi un’azione urgente di tipo preventivo, prima ancora che terapeutico.

Figura 1: Insufficienza renale come fattore di rischio di mortalità in corso di Covid-19
Figura 1: Insufficienza renale come fattore di rischio di mortalità in corso di Covid-19

Vaccini anti SARS-CoV-2 attualmente disponibili

I vaccini si configurano da sempre come un bene fondamentale oltre che come la strategia principale con cui l’umanità è riuscita a sconfiggere molte malattie infettive. In soli undici mesi è stato ottenuto un vaccino e questo ha rappresentato una conquista senza precedenti [31].

Il vaccino Covid-19 mRNA BNT162b2 (Comirnaty), noto come Pfizer-BioNTech, è stato il primo vaccino disponibile in Italia ai soggetti a partire dai 16 anni di età per prevenire Covid-19 [32,33]. Il vaccino è stato autorizzato da EMA (European Medicines Agency – Agenzia Europea per i Medicinali) [34] e AIFA (Agenzia Italiana del Farmaco) [35,36]. Per la sua realizzazione sono state regolarmente rispettate tutte le abituali fasi di verifica finalizzate alla valutazione di sicurezza e di efficacia [37]. In Italia la sua somministrazione è stata avviata il 27 dicembre, secondo il piano nazionale di vaccinazione che prevede più tappe.

Il vaccino Covid-19 mRNA BNT162b2 (Comirnaty) è stato il primo ad arrivare in Italia, seguito da Covid-19 Vaccine mRNA-1273, noto più comunemente come vaccino Moderna e con il medesimo meccanismo d’azione [37], approvato da EMA il 6 gennaio 2021 [38] e da AIFA il giorno successivo [39].

Ma come si comporta SARS-CoV-2 all’interno dell’organismo? E come funzionano i vaccini a disposizione? La singola particella di SARS-CoV-2 ha forma rotondeggiante e sulla sua superficie presenta delle “punte” rendono il virus simile a una corona (da cui il nome Coronavirus) [37]. La proteina Spike presente sulle punte si lega all’enzima di conversione dell’angiotensina 2 (ACE2) presente sulle cellule dell’epitelio polmonare, ed entra nella cellula impedendo all’enzima di esplicare la propria funzione protettiva verso infezioni ed agenti esterni. La proteina Spike può essere quindi paragonata a una chiave che consente l’inclusione del virus nelle cellule dell’organismo. Dentro la cellula il virus rilascia la propria identità genetica (RNA) e induce la cellula alla produzione di proteine virali che generano nuovi coronavirus: questi a loro volta infettano altre cellule, sostenendo quindi il processo alla base della malattia [3,20].

I vaccini Covid-19 mRNA BNT162b2 (Comirnaty) e Covid-19 mRNA-1273 sono stati pensati per stimolare una risposta immunitaria atta a neutralizzare la proteina Spike, al fine di inibire l’infezione delle cellule. Essi contengono le molecole di RNA messaggero (mRNA), ossia le “istruzioni” necessarie per costruire le proteine Spike del virus SARS-CoV-2. Le molecole di mRNA sono inserite in una vescicola lipidica che protegge l’mRNA stesso per evitarne la degradazione da parte delle difese immunitarie, in quanto riconosciuto come estraneo all’organismo [32,33,40]. All’interno dell’organismo, il mRNA è internalizzato nel citoplasma delle cellule e induce la creazione della sola proteina Spike, che, riconosciuta estranea, stimola la produzione di anticorpi specifici. Con il vaccino quindi si inocula nelle cellule solamente l’informazione genetica fondamentale per costruire copie della proteina Spike [32,33,40]. La vaccinazione inoltre determina anche una attivazione delle cellule T che preparano le cosiddette “cellule di memoria” del sistema immunitario. Dopo aver svolto l’azione di induzione anticorpale, il mRNA del vaccino si degrada naturalmente nell’arco di pochi giorni. Non esiste pertanto alcun rischio che venga integrato nel DNA delle cellule dell’organismo in via definitiva. Il vaccino Covid-19 m RNA BNT162b2 (Comirnaty) prevede due somministrazioni a distanza di almeno 21 giorni l’una dall’altra.

Il vaccino Pfizer BioNTech e il Moderna sono sicuri, come conferma anche il New England Journal of Medicine [33]. Il dubbio mediaticamente espresso su una troppo rapida produzione e distribuzione di questo vaccino può essere facilmente fugato. Gli studi sui vaccini anti Covid-19 hanno avuto inizio nel corso della prima ondata e certamente sono durati un periodo relativamente breve rispetto ai tempi abituali. Questo perché gli studi hanno coinvolto un numero di soggetti dieci volte maggiore rispetto a quanto osservato in studi analoghi standardizzati per la messa a punto di altri vaccini. È stato pertanto condotto un lavoro di enormi proporzioni, sufficienti documentare l’efficacia e la sicurezza del vaccino, senza saltare nessuna fase sperimentale normalmente prevista [40]. A questo ha indubbiamente contribuito anche la ricerca precedentemente effettuata su altri vaccini a RNA, frequentemente usati in malattie tumorali, e anche le enormi risorse umane ed economiche messe a disposizione rapidamente, non ultima la tempestiva supervisione delle agenzie regolatorie. Tutti questi fattori insieme hanno reso possibile risparmiare anni sui tempi di approvazione, in un momento storico che rendeva necessario l’avvio della campagna vaccinale quanto prima.

Gli studi si sono svolti in sei Paesi: Stati Uniti, Germania, Brasile, Argentina, Sudafrica e Turchia, con l’adesione di più di 44mila persone. La metà dei soggetti ha ricevuto il vaccino, l’altra metà ha ricevuto un placebo. La stima dell’efficacia è stata valutata su oltre 36mila persone a partire dai 16 anni di età (compresi soggetti di età superiore ai 75 anni) in assenza di segni di precedente infezione [33]. È stato quindi dimostrato che il numero di casi sintomatici di Covid-19 si è ridotto del 95% nei soggetti che hanno ricevuto il vaccino rispetto a quelli che hanno ricevuto il placebo [41].

Il vaccino è stato somministrato inizialmente in modalità prioritaria alle categorie più a rischio, in primis agli operatori sanitari. Attualmente, è disponibile su larga scala. Va segnalato inoltre un recente studio del Centri per la Prevenzione e il Controllo delle Malattie [42] che rileva come i vaccini mRNA Covid-19 siano molto efficaci nel prevenire la malattia tra sanitari e operatori essenziali. Lo studio ha dimostrato che la vaccinazione parziale con un vaccino mRNA ha ridotto il rischio di infezione del 80% (due settimane dopo la singola dose), mentre la vaccinazione completa ha abbattuto il rischio di infezione del 90% (due settimane dopo la seconda dose).

Per quanto riguarda le prospettive future, un terzo vaccino con tecnologia RNA è il CVnCoV, sviluppato dalla farmaceutica tedesca CureVac e dalla Coalition for Epidemic Preparedness Innovation (CEPI), ed è in attesa di autorizzazione da parte di EMA dal febbraio 2021 [43].

Un’altra tipologia di vaccino anti SARS-Cov-2 attualmente a disposizione è il vaccino Covid-19 AstraZeneca, approvato in prima battuta da EMA [44] e da AIFA [36] rispettivamente in data 29 e 30 gennaio 2021, destinato ai soggetti di età pari o superiore ai 18 anni [45]. Questo vaccino ha un meccanismo sostanzialmente differente dai precedenti. È composto infatti da un adenovirus di scimpanzé incapace di replicarsi (ChAdOx1 – Chimpanzee Adenovirus Oxford 1) e modificato per veicolare l’informazione genetica destinata a produrre la proteina Spike del virus SARS-CoV-2. In sintesi, l’adenovirus è stato geneticamente modificato per sostituire una delle proteine dell’adenovirus con la proteina Spike del SARS-CoV-2, verso cui si genererà la risposta immunitaria nell’organismo ospite [45].

Quale è il potenziale vantaggio di questo approccio rispetto a quello usato per gli altri vaccini? Uno è indubbiamente la maggiore stabilità dell’“involucro” del vaccino, in quanto rappresentato da un altro agente virale: mentre gli altri vaccini richiedono per la loro conservazione temperature molto basse, questo tipo di vaccino può essere invece tranquillamente conservato sei mesi in un comune frigorifero [45].

Quattro studi clinici randomizzati, in doppio cieco, di cui due condotti nel Regno Unito, uno in Brasile e uno Sudafrica, hanno documentato che tale vaccino è sicuro ed efficace nella prevenzione della malattia sintomatica nelle persone a partire dai 18 anni di età [46]. Questi studi hanno coinvolto più di 20.000 persone. I partecipanti, di età ≥18 anni sono stati randomizzati e assegnati a uno dei due gruppi: gruppo di soggetti che hanno ricevuto il vaccino e il gruppo di controllo, che in questo caso ha ricevuto vaccino antimeningococcico coniugato ACWY o soluzione salina, con un rapporto di allocazione 1:1. I dati di sicurezza sono basati sull’analisi ad interim di dati aggregati provenienti dai quattro studi clinici di riferimento [46]. Le reazioni avverse registrate più frequentemente erano generalmente lievi-moderate e si sono risolte dopo pochi giorni dalla vaccinazione. Le più comuni sono state: dolore nel sito di iniezione, cefalea, astenia, mialgie, malessere generalizzato, brividi, febbre, artralgie e nausea [46].

I risultati ottenuti sono sicuramente confortanti; la domanda da porsi è quindi se questo vaccino sia sicuro ed efficace al pari di quelli precedentemente descritti. A questo quesito rispondono gli studi clinici. I dati di sicurezza emersi dagli studi preliminari sono risultati molto buoni. Per quanto riguarda il profilo di efficacia i dati sinora disponibili la hanno attestata a circa il 60% [46]. Seppure in termini puramente numerici, l’efficacia sembri quindi significativamente minore rispetto al vaccino Covid-19 mRNA BNT162b2; in realtà, il vaccino AstraZeneca presenta una buona efficacia, sicuramente superiore per esempio a quella del comune vaccino antiinfluenzale impiegato annualmente e che ogni anno fornisce comunque una ottima copertura contro l’influenza stagionale, in special modo nei soggetti fragili. Il vero limite che riguarda invece il vaccino AstraZeneca sembrerebbe verosimilmente correlato alla sua incapacità nel prevenire le infezioni asintomatiche. In sintesi, le persone sono protette dalla malattia, ma possono infettarsi in maniera asintomatica e forse trasmettere il virus ad altri [45].

L’AIFA aveva in prima battuta autorizzato l’utilizzo di questo vaccino sino ai 55 anni di età [36], limite attualmente in estensione a soggetti più anziani. Tuttavia, un’adeguata protezione è comunque auspicabile, sia in base all’esperienza ottenuta con altri vaccini, sia per la buona risposta immunitaria riscontrata in questa fascia di età. Poiché esistono peraltro dati attendibili sulla sicurezza in questa coorte, gli esperti dell’EMA ritengono che il vaccino possa essere perciò utilizzato a breve anche negli adulti più anziani.

Quindi, al momento attuale il vaccino AstraZeneca non può essere considerato lo strumento ideale per raggiungere l’obiettivo fondamentale dell’immunità di gregge. Tuttavia, presenta un rapporto beneficio/rischio favorevole ed è sicuramente un’arma per il contenimento dell’infezione. È bene sottolineare che la sicurezza del vaccino è stata comunque dimostrata in tutti e quattro gli studi presi in esame [46].

Il vaccino AstraZeneca non è l’unico prodotto che sfrutta la tecnologia dei vettori virali non replicanti. Su questo tipo di meccanismo d’azione si riconoscono altri vaccini come quello russo Gam-COVID-Vac (Sputnik V) [47], quello cinese AD5-nCOV Convidecia [48] e il vaccino Ad26.COV2.S progettato dalla farmaceutica belga Janssen sotto la società americana Johnson & Johnson [48]. Convidecia e il vaccino di Janssen Johnson & Johnson [48] sono entrambi vaccini “single-dose”, che offrono una logistica meno complicata, e possono essere conservati in refrigerazione ordinaria per diversi mesi. Questi ultimi vaccini non sono ancora in utilizzo in Italia, seppure la loro immissione nel programma vaccinale dovrebbe essere prevista a breve.

Va invece riportato che in seguito all’introduzione del vaccino AstraZeneca in UE sono emerse segnalazioni di eventi trombotici potenzialmente correlabili, producendo allarme generalizzato nella popolazione. Tuttavia, l’EMA ha comunicato che alla data del 10/3/2021, il sistema di vigilanza europea degli eventi avversi EudraVigilance aveva registrato 30 casi di eventi trombotici in 5 milioni di soggetti vaccinati e che tale numero risultava paragonabile al tasso di trombosi abitualmente registrato nella popolazione generale. Negli studi registrativi (condotti peraltro sotto stretta sorveglianza degli eventi avversi) non risultava segnalato alcun aumento del rischio di eventi trombotici. In data 18/3/2021 EMA e AIFA, dopo una revisione dei casi segnalati, si sono espresse nuovamente in modo favorevole verso tale vaccino definendolo sicuro ed efficace, escludendo relazioni tra casi di trombosi e la somministrazione dei sieri e reinserendolo nella campagna vaccinale.

A tutt’oggi il vaccino AstraZeneca rappresenta pertanto un’alternativa assolutamente utile. In seguito al caos conseguente allo stop imposto dall’UE per la somministrazione del vaccino, l’azienda ha deciso però di cambiarne il nome in Vaxezevria, modificando la scheda tecnica e riportando tra gli effetti collaterali anche le trombosi (seppure non siano stati dimostrata associazione causale tra i decessi e la somministrazione del vaccino).

Attualmente la Commissione tecnico-scientifica dell’AIFA ha indicato pertanto il seguente utilizzo preferenziale dei vaccini [35,36]:

  • vaccini a mRNA nei soggetti anziani e/o a più alto rischio di sviluppare una malattia grave
  • vaccino Vaxezevria nei soggetti maggiori di 18 anni, ad eccezione però dei soggetti estremamente vulnerabili tra cui vanno certamente annoverati i pazienti dializzati e trapiantati. Sulla scorta dei dati di immunogenicità e di quelli di sicurezza, il rapporto beneficio/rischio del vaccino resta comunque vantaggioso nei soggetti più anziani in assenza di specifici fattori di rischio.

 

Conclusione

La storia insegna da sempre che i vaccini sono sinonimo di vita. Non esiste malattia che sia meglio contrarre piuttosto che vaccinarsi, perché il rischio di ammalarsi supera sempre e comunque quello vaccinale.

L’elevato rischio di infezione grave e di aumentata mortalità in presenza di insufficienza renale è ormai documentato da plurime evidenze cliniche e rende il vaccino altamente raccomandato per questa coorte di pazienti, anche indipendentemente dal fattore età. È necessario quindi che in ambiente nefrologico ci si muova in un’unica direzione al fine di delineare quanto prima una regolamentazione che definisca questi pazienti come appartenenti a una categoria ad elevato rischio e di condurre a una rapida somministrazione di vaccini in modalità prioritaria, soprattutto per i soggetti affetti dalla malattia in stadio avanzato, per i pazienti dializzati e per i pazienti trapiantati.

A questo proposito va segnalato lo sforzo dimostrato dalla Società Italiana di Nefrologia che, con l’impegno congiunto di altre associazioni di settore come ANED (Associazione Nazionale Emodializzati Dialisi e Trapianto) e FIR (Fondazione Italiana del Rene), ha ottenuto l’aggiornamento del piano strategico nazionale di vaccinazione da parte del Ministero della Salute, dell’AIFA, del Comitato Tecnico Scientifico e del Commissario Straordinario per l’emergenza Covid-19. Infatti, nella lettera di impegno del 9 Febbraio firmata dal già Commissario Arcuri, vengono inseriti nella categoria di persone vulnerabili e con priorità per la vaccinazione tutti i pazienti con patologia renale, dializzati e soggetti portatori di trapianto renale. Questo importante traguardo dimostra che la collaborazione sinergica da parte di tutti gli enti coinvolti nel settore migliora la possibilità di raggiungere importanti obiettivi in modo più tempestivo ed efficace.

I malati affetti da nefropatie croniche, in dialisi o trapiantati hanno pagato un tributo molto alto alla pandemia Covid-19. Per tale motivo è necessario che questa popolazione particolarmente fragile sia non soltanto protetta nel minor tempo possibile ma anche monitorata nel tempo, per rilevare la risposta immunologica che seguirà alla vaccinazione e la sua reale efficacia.

 

Bibliografia

  1. Sciarrone Alibrandi MT, Vespa M. Perché è importante vaccinarsi per il Covid-19? AIRP onlus 2021. http://www.renepolicistico.it/2021/01/25/perche-e-importante-vaccinarsi-per-il-covid-19/
  2. Rashedi J, Mahdavi Poor B, Asgharzadeh V, Pourostadi M, Samadi Kafil H, Vegari A, et al. Risk Factors for COVID-19. Infez Med 2020; 28(4):469-74.
  3. Adapa S, Chenna A, Balla M, Merugu GP, Koduri NM, Daggubati SR, et al. COVID-19 Pandemic Causing Acute Kidney Injury and Impact on Patients With Chronic Kidney Disease and Renal Transplantation. J Clin Med Res 2020; 12(6):352-61.
  4. Gagliardi I, Patella G, Michael A, Serra R, Provenzano M, Andreucci M. COVID-19 and the Kidney: From Epidemiology to Clinical Practice. J Clin Med 2020; 9(8).
  5. Sciarrone Alibrandi MT, Vespa M. Kidney, ADPKD and Covid-19: the double role of renal fragility. G Clin Nefrol e Dial 2020; 32(1):99-101.
  6. US Renal Data System. 2016 Annual Data Report: Epidemiology of Kidney Disease in the United States. Am J Kidney Dis 2017; 69(3):A4.
  7. James MT, Quan H, Tonelli M, Manns BJ, Faris P, Laupland KB, et al. CKD and risk of hospitalization and death with pneumonia. Am J Kidney Dis 2009; 54(1):24-32.
  8. Girndt M, Köhler H, Schiedhelm-Weick E, Meyer zum Büschenfelde KH, Fleischer B. T cell activation defect in hemodialysis patients: evidence for a role of the B7/CD28 pathway. Kidney Int 1993; 44(2):359-65.
  9. Podkowińska A, Formanowicz D. Chronic Kidney Disease as Oxidative Stress and Inflammatory-Mediated Cardiovascular Disease. Antioxid Basel Switz 2020; 9(8).
  10. Bond TC, Spaulding AC, Krisher J, McClellan W. Mortality of dialysis patients according to influenza and pneumococcal vaccination status. Am J Kidney Dis 2012; 60(6):959-65.
  11. Levin A, Stevens PE, Bilous RW, Coresh J, et al. Kidney disease: Improving global outcomes (KDIGO) CKD work group. KDIGO 2012 clinical practice guideline for the evaluation and management of chronic kidney disease. Kidney Int Suppl 2013; 3(1):1-150.
  12. Hamming I, Timens W, Bulthuis MLC, Lely AT, Navis GJ, van Goor H. Tissue distribution of ACE2 protein, the functional receptor for SARS coronavirus. A first step in understanding SARS pathogenesis. J Pathol 2004; 203(2):631-7.
  13. Gaillard F, Ismael S, Sannier A, Tarhini H, Volpe T, Greze C, et al. Tubuloreticular inclusions in COVID-19-related collapsing glomerulopathy. Kidney Int 2020; 98(1):241.
  14. Larsen CP, Bourne TD, Wilson JD, Saqqa O, Sharshir MA. Collapsing Glomerulopathy in a Patient With COVID-19. Kidney Int Rep 2020; 5(6):935-9.
  15. Cheng Y, Luo R, Wang K, Zhang M, Wang Z, Dong L, et al. Kidney disease is associated with in-hospital death of patients with COVID-19. Kidney Int 2020; 97(5):829-38.
  16. Pei G, Zhang Z, Peng J, Liu L, Zhang C, Yu C, et al. Renal Involvement and Early Prognosis in Patients with COVID-19 Pneumonia. J Am Soc Nephrol 2020; 31(6):1157-65.
  17. Ali H, Daoud A, Mohamed MM, Salim SA, Yessayan L, Baharani J, et al. Survival rate in acute kidney injury superimposed COVID-19 patients: a systematic review and meta-analysis. Ren Fail 2020; 42(1):393-7.
  18. Mohamed MMB, Lukitsch I, Torres-Ortiz AE, Walker JB, Varghese V, Hernandez-Arroyo CF, et al. Acute Kidney Injury Associated with Coronavirus Disease 2019 in Urban New Orleans. Kidney360 2020; 1(7):614-22.
  19. Arentz M, Yim E, Klaff L, Lokhandwala S, Riedo FX, Chong M, et al. Characteristics and Outcomes of 21 Critically Ill Patients With COVID-19 in Washington State. JAMA 2020; 323(16):1612-4.
  20. Guan W-J, Ni Z-Y, Hu Y, Liang W-H, Ou C-Q, He J-X, et al. Clinical Characteristics of Coronavirus Disease 2019 in China. N Engl J Med 2020; 382(18):1708-20.
  21. Stephens JR, Stümpfle R, Patel P, Brett S, Broomhead R, Baharlo B, et al. Analysis of Critical Care Severity of Illness Scoring Systems in Patients With Coronavirus Disease 2019: A Retrospective Analysis of Three U.K. ICUs. Crit Care Med 2021; 49(1):e105-7.
  22. Fominskiy EV, Scandroglio AM, Monti G, Calabrò MG, Landoni G, Dell’Acqua A, et al. Prevalence, Characteristics, Risk Factors, and Outcomes of Invasively Ventilated COVID-19 Patients with Acute Kidney Injury and Renal Replacement Therapy. Blood Purif 2021; 50(1):102-9.
  23. Bruchfeld A. The COVID-19 pandemic: consequences for nephrology. Nat Rev Nephrol 2021; 17(2):81-2.
  24. Grasselli G, Zangrillo A, Zanella A, Antonelli M, Cabrini L, Castelli A, et al. Baseline Characteristics and Outcomes of 1591 Patients Infected With SARS-CoV-2 Admitted to ICUs of the Lombardy Region, Italy. JAMA 2020; 323(16):1574-81.
  25. Henry BM, Lippi G. Chronic kidney disease is associated with severe coronavirus disease 2019 (COVID-19) infection. Int Urol Nephrol 2020; 52(6):1193-4.
  26. Quintaliani G, Reboldi G, Di Napoli A, Nordio M, Limido A, Aucella F, et al. Exposure to novel coronavirus in patients on renal replacement therapy during the exponential phase of COVID-19 pandemic: survey of the Italian Society of Nephrology. J Nephrol 2020; 33(4):725-36.
  27. Kumar D, Tellier R, Draker R, Levy G, Humar A. Severe Acute Respiratory Syndrome (SARS) in a liver transplant recipient and guidelines for donor SARS screening. Am J Transplant 2003; 3(8):977-81.
  28. AlGhamdi M, Mushtaq F, Awn N, Shalhoub S. MERS CoV infection in two renal transplant recipients: case report. Am J Transplant 2015; 15(4):1101-4.
  29. Zhu L, Xu X, Ma K, Yang J, Guan H, Chen S, et al. Successful recovery of COVID-19 pneumonia in a renal transplant recipient with long-term immunosuppression. Am J Transplant 2020; 20(7):1859-63.
  30. Banerjee D, Popoola J, Shah S, Ster IC, Quan V, Phanish M. COVID-19 infection in kidney transplant recipients. Kidney Int 2020; 97(6):1076-82.
  31. Baden LR, El Sahly HM, Essink B, Kotloff K, Frey S, Novak R, et al. Efficacy and Safety of the mRNA-1273 SARS-CoV-2 Vaccine. N Engl J Med 2021; 384(5):403-16.
  32. Polack FP, Thomas SJ, Kitchin N, Absalon J, Gurtman A, Lockhart S, et al. Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine. N Engl J Med 2020; 383(27):2603-15.
  33. Anderson EJ, Rouphael NG, Widge AT, Jackson LA, Roberts PC, Makhene M, et al. Safety and Immunogenicity of SARS-CoV-2 mRNA-1273 Vaccine in Older Adults. N Engl J Med 2020; 383(25):2427-38.
  34. Glanville D. COVID-19 vaccines: key facts. European Medicines Agency 2020. https://www.ema.europa.eu/en/human-regulatory/overview/public-health-threats/coronavirus-disease-covid-19/treatments-vaccines/covid-19-vaccines-key-facts
  35. Agenzia Italiana del Farmaco. Vaccini a mRNA. https://aifa.gov.it/vaccini-mrna
  36. Agenzia Italiana del Farmaco. Vaccini a vettore virale. https://aifa.gov.it/vaccini-vettore-virale
  37. Azzolini E. Vaccino COVID Pfizer-BioNTech: cos’è, come funziona e perché è sicuro. Humanitas 2021. https://www.humanitas.it/news/vaccino-covid-pfizer-biontech-cose-come-funziona-e-perche-e-sicuro/
  38. Glanville D. EMA recommends COVID-19 Vaccine Moderna for authorisation in the EU. European Medicines Agency 2021. https://www.ema.europa.eu/en/news/ema-recommends-covid-19-vaccine-moderna-authorisation-eu
  39. Agenzia Italiana del Farmaco. COVID-19: AIFA authorizes Moderna vaccine: https://aifa.gov.it/-/covid-19-aifa-autorizza-vaccino-moderna
  40. Sharma O, Sultan AA, Ding H, Triggle CR. A Review of the Progress and Challenges of Developing a Vaccine for COVID-19. Front Immunol 2020; 11:2413.
  41. Chagla Z. The BNT162b2 (BioNTech/Pfizer) vaccine had 95% efficacy against COVID-19 ≥7 days after the 2nd dose. Ann Intern Med 2021; 174(2):JC15.
  42. Centers for Disease Control and Prevention. CDC Works 24/7. Centers for Disease Control and Prevention 2021. https://www.cdc.gov/index.htm
  43. Dimitrova EK. EMA starts rolling review of CureVac’s COVID-19 vaccine (CVnCoV). European Medicines Agency 2021: https://www.ema.europa.eu/en/news/ema-starts-rolling-review-curevacs-covid-19-vaccine-cvncov
  44. Pinho AC. EMA recommends COVID-19 Vaccine AstraZeneca for authorisation in the EU. European Medicines Agency 2021. https://www.ema.europa.eu/en/news/ema-recommends-covid-19-vaccine-astrazeneca-authorisation-eu
  45. Knoll MD, Wonodi C. Oxford-AstraZeneca COVID-19 vaccine efficacy. The Lancet 2021; 397(10269):72-4.
  46. Voysey M, Clemens SAC, Madhi SA, Weckx LY, Folegatti PM, Aley PK, et al. Safety and efficacy of the ChAdOx1 nCoV-19 vaccine (AZD1222) against SARS-CoV-2: an interim analysis of four randomised controlled trials in Brazil, South Africa, and the UK. Lancet Lond Engl 2021; 397(10269):99-111.
  47. Logunov DY, Dolzhikova IV, Shcheblyakov DV, Tukhvatulin AI, Zubkova OV, Dzharullaeva AS, et al. Safety and efficacy of an rAd26 and rAd5 vector-based heterologous prime-boost COVID-19 vaccine: an interim analysis of a randomised controlled phase 3 trial in Russia. Lancet Lond Engl 2021; 397(10275):671-81.
  48. Mercado NB, Zahn R, Wegmann F, Loos C, Chandrashekar A, Yu J, et al. Single-shot Ad26 vaccine protects against SARS-CoV-2 in rhesus macaques. Nature 2020; 586(7830):583-8.

Phosphorus binders: trigger for intestinal diverticula formation in an ADPKD patient

Abstract

Hyperphosphoremia is common in patients with chronic kidney disease and is an important risk factor in this patient population. Phosphate binding drugs are a key therapeutic strategy to reduce phosphoremia levels, although they have significant side effects especially in the gastrointestinal tract, such as gastritis, diarrhoea and constipation. We report the case of a haemodialysis-dependent patient suffering from chronic kidney disease stage V KDIGO secondary to polycystic autosomal dominant disease; treated with phosphate binders, the case was complicated by the appearance of diverticulosis, evolved into acute diverticulitis.

 

Keywords: hyperphosphoremia, phosphate binding drugs, chronic kidney disease, polycystic autosomal dominant disease, diverticulosis, acute diverticulitis

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Spett.le Editore,

Un recente evento avverso nella gestione di un paziente emodializzato presso la nostra U.O.C. di Nefrologia e Dialisi ci ha impegnati particolarmente e ci ha indotto a pubblicare questa comunicazione, per stimolare la discussione sull’uso dei chelanti del fosforo nei pazienti con insufficienza renale cronica secondaria a Rene Policistico dell’Adulto (ADPKD).

L’iperfosforemia nei pazienti con malattia renale cronica è un accertato fattore di rischio cardiovascolare [13]. La dieta ipofosforica e gli agenti chelanti del fosforo sono, infatti, prescritti nei pazienti con insufficienza renale cronica in fase conservativa ed evoluta in uremia al fine di ridurre i livelli di fosforemia, di migliorare l’iperparatiroidismo secondario ed attenuare la progressione delle calcificazioni vascolari [37]. Inoltre, gli effetti benefici dei chelanti del fosforo sono correlati ad una aumentata sopravvivenza dei pazienti in trattamento emodialitico, in maniera indipendente da altri fattori [8].

 

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Renal function performance in CKD stage 5: a sealed fate?

Abstract

Introduction and aims: Stages 4 and 5 of chronic kidney disease (CKD) have always been considered hard to modify in their speed and evolution. We retrospectively evaluated our CKD stage 5 patients (from 01/1/2016 to 12/31/2018), with a view to analyzing their kidney function evolution.

Material and Methods: We included only patients with longer than 6 months follow-up and at least 4 clinical-laboratory controls that included measured Creatinine Clearance (ClCr) and estimated GFR with CKD-EPI (eGFR). We evaluated: the agreement between ClCr and eGFR through Bland-Altman analysis; progression rate, classified as fast (eGFR loss >5ml/min/year), slow (eGFR loss 1-5 ml/min/year) and non-progressive (eGFR loss <1 ml/min/year or eGFR increase). We also evaluated which clinical-laboratory parameters (diabetes, blood pressure control, use of ACEi/ARBs, ischemic myocardiopathy, peripheral obliterant arteriopathy (POA), proteinuria, hemoglobin, uric acid, PTH, phosphorus) were associated to the different eGFR progression classes by means of bivariate regression and multinomial multiple regression model. Results: Measured CrCl and eGFR where often in agreement, especially for GFR values <12ml/min. The average slope of eGFR was -3.05 ±3.68 ml/min/1.73 m2/year. The progression of kidney function was fast in 17% of the patients, slow in 57.6%, non-progressive in 25.4%. At the bivariate analysis, a fast progression was associated with poor blood pressure control (p=0.038) and ACEi/ARBs use (p=0.043). In the multivariable model, only peripheral obliterative arteriopathy proved associated to an increased risk of fast progression of eGFR (relative risk ratio=5.97).

Discussion: Less than one fifth of our patients presented a fast GFR loss (>5 ml/min/year). The vast majority showed a slow progression, stabilisation or even an improvement. Despite the limits due to the small sample size, the data has encouraged us not to consider CKD stage 5 as an inexorable and short journey towards artificial replacement therapy.

 

Keywords: chronic kidney disease, CKD, disease progression, glomerular filtrate, chronic renal failure

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Introduzione

La malattia renale cronica (Chronic Kidney Disease, CKD) colpisce oltre 850 milioni di persone nel mondo (11% circa della popolazione mondiale) [1]; di questi, 37 milioni sono negli Stati Uniti (pari al 15% della popolazione) [2], 38 milioni in Europa (il 10% della popolazione) [3] e circa 4 milioni in Italia, pari a circa il 7% della popolazione [4]. Numerosi studi hanno approfondito i fattori di rischio e progressione del danno renale cronico, spesso includendo nel campione fasi di CKD estremamente polimorfe come fenotipo clinico, rischio cardiovascolare e complicanze in corso di malattia [58].

Agli inizi degli anni ’90, Maschio [10] considerava un valore di creatininemia di circa 2 mg/dl come un “punto di non-ritorno” della storia naturale della CKD,  al di là del quale si prevedeva un inevitabile e progressivo peggioramento della funzione renale, nonostante gli interventi di tipo dietetico e terapeutico messi in atto. Tutt’oggi si ritiene che la malattia renale cronica abbia un andamento prevalentemente lineare con una progressione più rapida nelle fasi più avanzate. Recenti studi osservazionali [11, 12] hanno evidenziato invece come nelle fasi avanzate della CKD la modalità di progressione possa essere variabile, mostrando spesso un andamento non lineare e fortemente eterogeneo.

 

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Treating anaemia in patients with chronic kidney disease: what evidence for using ESAs, after a 30-year journey?

Abstract

Erythropoiesis Stimulating Agents (ESAs) are well-tolerated and effective drugs for the treatment of anaemia in patients with chronic kidney disease.

In the past, scientific research and clinical practice around ESAs have mainly focused on the haemoglobin target to reach, and to moving towards the normality range; more cautious approach has been taken more recently. However, little attention has been paid to possible differences among ESA molecules. Although they present a common mechanism of action on the erythropoietin receptor, their peculiar pharmacodynamic characteristics could give different signals of activation of the receptor, with possible clinical differences.

Some studies and metanalyses did not show significant differences among ESAs. More recently, an observational study of the Japanese Registry of dialysis showed a 20% higher risk of mortality from any cause in the patients treated with long-acting ESAs in comparison to those treated with short-acting ESAs; the difference increased in those treated with higher doses. These results were not confirmed by a recent, post-registration, randomised, clinical trial, which did not show any significant difference in the risk of death from any cause or cardiovascular events between short-acting ESAs and darbepoetin alfa or methoxy polyethylene glycol-epoetin beta. Finally, data from an Italian observational study, which was carried out in non-dialysis CKD patients, showed an association between the use of high doses of ESA and an increased risk of terminal CKD, limited only to the use of short-acting ESAs.

In conclusion, one randomised clinical trial supports a similar safety profile for long- versus short-acting ESAs. Observational studies should always be considered with some caution: they are hypothesis generating, but they may suffer from bias by indication.

Keywords: anaemia, erythropoiesis stimulating agents, ESAs, mortality, chronic kidney disease, long acting, short acting

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Introduzione

Dalla pubblicazione dello storico lavoro di Eschbach più di 30 anni fa [1], il trattamento dell’anemia con i farmaci stimolanti l’eritropoiesi (Erythropoiesis Stimulating Agents, ESAs) ha rivoluzionato la qualità della vita dei pazienti con malattia renale cronica (Chronic Kidney Disease, CKD). In quegli anni i pazienti erano gravemente anemici e spesso sopravvivevano con livelli di emoglobina anche inferiori a 5 g/dL, ricorrendo a periodiche trasfusioni, con alto rischio di trasmissione di un’epatite allora sconosciuta, definita “non A-non B” (oggi chiamata C) e con conseguente accumulo di grandi quantità di ferro. Nei casi più gravi i nefrologi erano costretti ad intervenire con un trattamento chelante a base di desferriossamina, a sua volta gravato da serie complicanze come la mucoviscidosi. Improvvisamente, grazie all’utilizzo dell’eritropoietina, i pazienti ricominciarono a vivere. Tale era l’entusiasmo dei nefrologi nel poter finalmente correggere efficacemente la grave anemia dei loro pazienti cronici, che si fecero trascinare fino a una correzione troppo rapida dei valori di emoglobina, portando a complicanze come un aumento dei valori pressori sino a severe crisi ipertensive e, a volte, convulsioni. 

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SGLT2 inhibitors, beyond glucose-lowering effect: impact on nephrology clinical practice

Abstract

Epidemiological data show an increasing diffusion of diabetes mellitus worldwide. In the diabetic subject, the risk of onset of chronic kidney disease (CKD) and its progression to the terminal stage remain high, despite current prevention and treatment measures. Although SGLT2 inhibitors have been approved as blood glucose lowering drugs, they have shown unexpected and surprising cardioprotective and nephroprotective efficacy. The multiple underlying mechanisms of action are independent and go beyond glycemic lowering. Hence, it has been speculated to extend the use of these drugs also to subjects with advanced stages of CKD, who were initially excluded because of the expected limited glucose-lowering effect. Non-diabetic patients could also benefit from the favorable effects of SGLT2 inhibitors: subjects with renal diseases with different etiologies, heart failure, high risk or full-blown cardiovascular disease. In addition, these drugs have a good safety profile, but several post-marketing adverse event have been reported. The ongoing clinical trials will provide clearer information on efficacy, strength and safety of these molecules. The purpose of this review is to analyze the available evidence and future prospects of SGLT2 inhibitors, which could be widely used in nephrology clinical practice.

Keywords: diabetes, oral hypoglycemic agents, SGLT2 inhibitors, chronic kidney disease

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Introduzione

Il diabete mellito (DM) è una delle patologie più diffuse nel mondo: ne soffre circa l’8,5% della popolazione adulta ed il trend nelle ultime decadi mostra un progressivo aumento dell’incidenza e della prevalenza [1].

La malattia renale cronica (MRC) è frequente complicanza del DM, sia di tipo 1 (DM1) che di tipo 2 (DM2). Si calcola che tra il 40 e il 50% dei soggetti affetti da DM2 sviluppa MRC nell’arco della vita e la sua presenza e severità influenzano significativamente la prognosi [2, 3, 4]. Pochi e dibattuti sono i dati relativi alla progressione del danno renale nel diabetico fino alla malattia renale cronica terminale (ESRD). Le cifre sono sottostimate e inficiate dall’elevata mortalità di questi soggetti, molti dei quali muoiono prima di giungere alla necessità di terapia sostitutiva della funzione renale, soprattutto per patologie cardiovascolari (CV) [5, 6, 7]. Negli Stati Uniti nel 2010 la prevalenza di ESRD tra i diabetici adulti è stata di 20/10.000 [8]. Guardando all’eziopatogenesi, il DM è ormai stabilmente la causa principale dell’ESRD. È da ascrivere al DM il 23% e il 16% dei casi incidenti e prevalenti di ESRD, rispettivamente, secondo il più recente report ERA-EDTA (European Renal Association-European Dialysis and Transplant Association) [9]. 

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