N-acetylcysteine inhibits endothelial tissue factor upregulation by the uremic toxin indoxyl sulfate

Le risque d’événement cardiovasculaire majeur est augmenté chez les patients atteints de maladie rénale chronique (MRC). Les ligands endogènes du facteur de transcription aryl hydrocarbon receptor (AhR) comme la toxine urémique indoxyl sulfate (IS) s’accumulent chez ces patients. L’IS induit une dysfonction vasculaire, un stress oxydant et un état prothrombotique notamment via l’activation dufacteur tissulaire (FT) endothélial. L’antioxydant La N‐acétylcystéine (NAC), précurseur du glutathion réduit (GSH), diminue les évènements cardiovasculaires chez les patients en hémodialyse chronique et pourrait être un traitement prometteur réduisant l’activation du FT endothélial par l’IS. L’IS induit une surexpression de l’ARNm, de la protéine et de l’activité procoagulante du FT et active AhR dans des conditions de shear stress. La NAC inhibe l’activation du FT. Elle inhibe aussi l’activation d’AhR et de NF‐ᴋB induite par l’IS. Nous avons inclus 47 patients dans l’essai clinique RENACTIF. Il n’y a pas d’effet significatif de la NAC sur la réduction des taux plasmatiques de FT. En analyse post‐HOC, les taux plasmatiques de FT diminuent dans le groupe traité par NAC (113 pg/ml (IQ 96‐133) vs 104 pg/ml (IQ 92‐122), p=0.002) mais pas dans le groupe placebo (p=0.42). L’activation du FT par l’IS dans les cellules endothéliales est inhibée par la NAC via un effet sur la voie AhR‐NF‐ᴋB. Nous observons une réduction des taux plasmatiques de FT chez les patients en hémodialyse chronique traités par NAC. La NAC pourrait réduire les évènements thrombotiques chez les patients IRC en inhibant la voie glutathion/AhR/NF‐kB/FT.The risk of major cardiovascular event MCE increased in patients with chronic kidney disease (CKD). Endogenous agonists of the transcription factor aryl hydrocarbon receptor (AhR) such as the indolic uremic toxin, indoxyl sulfate (IS), accumulate in patient with CKD. IS induced vascular dysfunction, oxidative stress and a prothrombotic state, especially via endothelial tissue factor (FT) induction. The antioxidant N‐acetylcysteine (NAC), a glutathione reduced (GSH) precursor, decreased MCE in patients on chronic hemodialysis and could be a promising treatment for reduce endothelial FT induction by IS. IS induced TF mRNA, protein expression and TF activity and upregulate AHR target genes on SS condition. TF activation by IS was inhibed by NAC. NAC inhibits IS activation of AhR and NF‐ᴋB. Finally, IS induced NF‐ᴋB activation via an AhR dependent pathway. 47 patients were enrolled in the cross over clinical trial. NAC has no effects on plasma TF reduction. In post hoc analysis, plasma TF concentration decreased with NAC (113 (IQ 96‐133) pg/ml vs 104 (IQ 92‐122) pg/ml, p=0.002) but not with placebo. FT activation by IS in endothelial cells is inhibited by NAC, via the AhR‐NF‐KB signaling pathway. We observed a reduction in plasma TF concentration in patients on chronic hemodialysis treated by NAC. NAC could reduce the thrombotic events in patients with CKD by targeting the glutathione/AhR/NFkB/TF pathway

Volume plaquettaire moyen et dysfonction de la fistule artério-veineuse dans une cohorte prospective de patients hémodialysés chroniques

Thèse présentée sous la forme d'une" thèse article"Introduction: Arteriovenous fistula (AVF) is the vascular access of 78% of haemodialysis patients in France. AVF dysfunctions such as thrombosis or stenosis are common complications. They are responsible for 30% of hospitalizations of chronic haemodialysis patients. One of the main factors behind these dysfunctions is an abnormality of hyperactive platelet-dependent coagulation during chronic renal failure. The more excitable young platelets are larger. Mean platelet volume (MPV) is a risk marker for major cardiovascular events.Objectives: Prospectively study MPV in our cohort of chronic haemodialysis as predictive marker of AVF dysfunction (occurrence of stenosis and acute thrombosis). We will study the mortality, the occurrence of cardiovascular events and serious haemorrhagic events.Materials and methods: The study included all chronic haemodialysis patients from the Conception Hospital at the CHU of Marseille between June 2014 and June 2016, component 226 patients. The main objective was to observe if there is a difference in the incidence of events on the AVF as dependent of the MPV. The population was divided according to 4 MPV levels determined by MPV quartiles in our cohort. The primary endpoint is a composite element called " AVF event" grouping: AVF acute thrombosis and AVF dysfunction requiring fistulography with endovascular treatment. Statistical analysis was done univarially by a Kaplan-Meier survival model and multivariate by a COX modelResults: 193 patients were included in the study with a median follow-up of 620 days. The median VPM was 10.8 fl [7.8-13.5] and the following quartiles: group 1: VPM ≤ 10fl, group 2: 10.1fl ≤ VPM <10.7fl, group 3: 10.7fl ≤ VPM <11, 5fl, group 4: VPM ≥ 11.5 fl. There was no difference in the characteristics of these 4 groups. There was a higher incidence (p = 0.001) in group 4 with 23 events (59%), 14 (34%) in group 3, 11 (27%) in group 2 and 6 (18%) in group 1. The multivariate analysis shows an independent association between the MPV and the risk of occurrence of an event, the OR is 1.66 [1.24-2.23] p = 0.0007. There was no significant difference in mortality, occurrence of cardiovascular events or serious bleeding events.Conclusion: We have shown in our cohort of chronic haemodialysis that the risk of occurrence of an event on arteriovenous fistula (dysfunction requiring the realization of fistulography or acute thrombosis) is predicted by measuring the MPV. It thus makes it possible to identify the patients at risk of events on the AVF. This population could benefit from enhanced surveillance or anti-aggregating or anticoagulant therapies. Limiting the number of events on the AVF would reduce the occurrence of thrombosis or even loss of vascular access exposing the patient to a vital risk.Introduction : la fistule artérioveineuse (FAV) est la voie d’abord vasculaire de 78% des patients en hémodialyse en France. Les dysfonctions de la FAV à type de thrombose ou de sténose sont des complications fréquentes. Elles sont responsables de 30% des hospitalisations des hémodialysés chroniques. Un des principaux facteurs à l’origine de ces dysfonctions est une anomalie de la coagulation dépendante des plaquettes hyperactives au cours de l’insuffisance rénale chronique. Les plaquettes jeunes plus excitables sont de plus grande taille. Le volume plaquettaire moyen (VPM) est un marqueur de risque d’événements cardiovasculaires majeurs. Objectifs : étudier prospectivement le VPM dans notre cohorte d’hémodialysés chronique comme marqueur prédictif de dysfonction de la FAV (survenue de sténose et de thrombose aiguë). Nous étudierons la mortalité, la survenue d’événements cardio-vasculaires et d’événements hémorragiques graves.Matériels et méthodes : l’étude inclus l’ensemble des patients hémodialysés chronique de l’hôpital de la Conception au CHU de Marseille entre Juin 2014 et Juin 2016, soit 226 patients. L’objectif principal était d’observer s’il existe une différence d’incidence des évènements sur la FAV en fonction du VPM. La population était divisée selon 4 niveau de VPM déterminés selon les quartiles du VPM dans notre cohorte. Le critère de jugement principal est un élément composite dénommé « évènement de FAV » regroupant : thrombose aigue de FAV et dysfonction de FAV ayant nécessité une fistulographie avec traitement endovasculaire. L’analyse statistique a été faite de façon univariée par un modèle de survie Kaplan-Meier et de façon multivariée par un modèle de COXRésultats : 193 patients ont été inclus dans l’étude avec une médiane de suivi de 620 jours. Le VPM moyen était de 10,8 fl [7.8-13.5] et les quartiles suivants : groupe 1 : VPM ≤ 10fl, groupe 2 : 10,1fl ≤ VPM < 10,7fl, groupe 3 : 10,7fl ≤ VPM < 11,5fl, groupe 4 : VPM ≥ 11,5fl. Il n’existait pas de différence concernant les caractéristiques de ces 4 groupes. On note une incidence plus grande (p=0,001) dans le groupe 4 avec 23 évènements (59%), 14 (34%) dans le groupe 3, 11 (27%) dans le groupe 2 et 6 (18%) dans le groupe 1. L’analyse multivariée montre une association indépendante entre le VPM et le risque de survenue d’un événement, l’OR est de 1,66 [1,24-2,23] p=0.0007. Il n’existait pas de différence significative concernant la mortalité, la survenue d’événements cardio-vasculaires ou d’événements hémorragiques graves.Conclusion : nous avons montré dans notre cohorte d’hémodialysés chronique que le risque de survenue d’un évènement sur fistule artérioveineuse (dysfonction nécessitant la réalisation d’une fistulographie ou thrombose aigue) est prédit par la mesure du VPM. Il permet ainsi d’identifier les patients à risque d’évènements sur la FAV. Cette population à risque pourrait bénéficier d’une surveillance renforcée voir de thérapeutiques antiagrégantes ou anticoagulantes. Limiter le nombre d’évènements sur la FAV permettrait de réduire la survenue de thromboses voire de perte de l’accès vasculaire exposant le patient à un risque vital

Indoxyl Sulfate, a Uremic Endotheliotoxin

International audienceChronic kidney disease (CKD) is associated with a high prevalence of cardiovascular diseases. During CKD, the uremic toxin indoxyl sulfate (IS)-derived from tryptophan metabolism-accumulates. IS is involved in the pathophysiology of cardiovascular complications. IS can be described as an endotheliotoxin: IS induces endothelial dysfunction implicated in cardiovascular morbidity and mortality during CKD. In this review, we describe clinical and experimental evidence for IS endothelial toxicity and focus on the various molecular pathways implicated. In patients with CKD, plasma concentrations of IS correlate with cardiovascular events and mortality, with vascular calcification and atherosclerotic markers. Moreover, IS induces a prothrombotic state and impaired neovascularization. IS reduction by AST-120 reverse these abnormalities. In vitro, IS induces endothelial aryl hydrocarbon receptor (AhR) activation and proinflammatory transcription factors as NF-kappa B or AP-1. IS has a prooxidant effect with reduction of nitric oxide (NO) bioavailability. Finally, IS alters endothelial cell and endothelial progenitor cell migration, regeneration and control vascular smooth muscle cells proliferation. Reducing IS endothelial toxicity appears to be necessary to improve cardiovascular health in CKD patients

Hepatitis E virus genotype 4 in Southeastern France: still around

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Pseudo-hyperkalaemia in ambulatory samples: the never-ending story?

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Mean Platelet Volume Predicts Vascular Access Events in Hemodialysis Patients

Arteriovenous fistula (AVF) and arteriovenous graft (AVG) is the vascular access (VA) of 78% of hemodialysis patients (HD) in France. VA dysfunction corresponding to either stenosis requiring angioplasty or acute thrombosis is responsible for 30% of hospitalizations. Mean platelet volume (MPV) is a biological marker of cardiovascular events. We studied MPV in a cohort of HD patients as a predictive marker of VA dysfunction. We conducted a prospective monocentric cohort study that included patients with AVF or AVG on chronic HD (n = 153). The primary outcome was the incidence of VA dysfunction regarding MPV value. The median MPV was 10.8 fL (7.8&#8722;13.5), and four groups were designed according to MPV quartiles. Fifty-four patients experienced the first event of VA dysfunction. The incidence of VA dysfunction was higher in patients with the highest MPV: 59% (23 events), 34% (14 events), 27% (11 events), and 18% (6 events), respectively, for the fourth, third, second, and first quartiles (p = 0.001). Multivariate analysis confirmed an independent association between MPV and VA dysfunction&#8212;OR 1.52 (1.13&#8722;2.07), p &lt; 0.001. VA dysfunction is predicted by MPV level. Patients with the highest MPV have the highest risk of VA events

Neutrophil:lymphocyte ratio correlates with the uremic toxin indoxyl sulfate and predicts the risk of death in patients on hemodialysis

International audienceABSTRACT Background Chronic kidney disease (CKD) is a major public health issue associated with increased cardiovascular, infectious and all-cause mortality. The neutrophil:lymphocyte ratio (NLR) is a predictive marker of the risk of death and cardiovascular events. Uremic toxins, notably indoxyl sulfate (IS), are involved in immune deficiency and cardiovascular complications associated with CKD. The aim of this study was to assess whether the NLR was related to uremic toxins and could predict clinical outcome in hemodialysis (HD) patients. Methods We conducted a prospective cohort study of 183 patients on chronic HD. The main objective was to study the correlation between the NLR and uremic toxin serum levels. The secondary objective was to test if the NLR can predict the incidence of mortality, cardiovascular events and infectious events. Results Patients were separated into two groups according to the NLR median value (3.49). The NLR at inclusion was correlated with the NLR at the 6-month (r = 0.55, P &lt; 0.0001) and 12-month (r = 0.62, P &lt; 0.0001) follow-up. Among uremic toxins, IS levels were higher in the group with high NLR (104 µmol/L versus 81 µmol/L; P = 0.004). In multivariate analysis, the NLR remained correlated with IS (P = 0.03). The incidence of death, cardiovascular events and severe infectious events was higher in the group with high NLR [respectively, 38% versus 18% (P = 0.004), 45% versus 26% (P = 0.01) and 33% versus 21% (P = 0.02)] than in the low NLR group. Multivariate analysis showed an independent association of the NLR with mortality (P = 0.02) and cardiovascular events (P = 0.03) but not with severe infectious events. Conclusions In HD patients, the NLR predicted mortality and cardiovascular events but not severe infections and correlated positively with the level of the uremic toxin IS. The NLR could be an interesting marker for monitoring the risk of clinical events in CKD patients

Aryl Hydrocarbon Receptor Activation and Tissue Factor Induction by Fluid Shear Stress and Indoxyl Sulfate in Endothelial Cells

International audienceEndogenous agonists of the transcription factor aryl hydrocarbon receptor (AHR) such as the indolic uremic toxin, indoxyl sulfate (IS), accumulate in patients with chronic kidney disease. AHR activation by indolic toxins has prothrombotic effects on the endothelium, especially via tissue factor (TF) induction. In contrast, physiological AHR activation by laminar shear stress (SS) is atheroprotective. We studied the activation of AHR and the regulation of TF by IS in cultured human umbilical vein endothelial cells subjected to laminar fluid SS (5 dynes/cm2). SS and IS markedly increased the expression of AHR target genes PTGS2 (encoding for COX2), AHRR, CYP1A1, and CYP1B1, as well as F3 (encoding for TF), in an AHR-dependent way. IS amplified SS-induced TF mRNA and protein expression and upregulation of AHR target genes. Interestingly, tyrosine kinase inhibition by genistein decreased SS-but not IS-induced TF expression. Finally, the increase in TF expression induced by laminar SS was not associated with increased TF activity. In contrast, IS increased TF activity, even under antithrombotic SS conditions. In conclusion, IS and SS induce AHR activation and AHR-dependent TF upregulation by different mechanisms. Impairment of the antithrombotic properties of shear stressed endothelium by toxic AHR agonists could favor cardiovascular diseases in CKD

Humoral response after SARS-CoV-2 vaccination in patients undergoing maintenance haemodialysis: loss of immunity, third dose and non-responders

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Stability Study of Parenteral N-Acetylcysteine, and Chemical Inhibition of Its Dimerization

Parenteral N-acetylcysteine has a wide variety of clinical applications, but its use can be limited by a poor chemical stability. We managed to control parenteral N-acetylcysteine stability, and to study the influence of additives on the decrease of N-acetylcysteine degradation. First, an HPLC-UV dosing method of N-acetylcysteine and its main degradation product, a dimer, was validated and the stability without additive was studied. Then, the influence of several additives (ascorbic acid, sodium edetate, tocopherol and zinc) and of temperature on N-acetylcysteine dimerization was evaluated. Finally, the influence of zinc gluconate at different concentrations (administrable to patients) was investigated. Zinc gluconate at 62.5 µg·mL−1 allows the stabilization of 25 mg·mL−1 N-acetylcysteine solution for at least 8 days when stored at 5 ± 3 °C