Effects of Sevelamer Hydrochloride on Uremic Toxins Serum Indoxyl Sulfate and P-Cresyl Sulfate in Hemodialysis Patients.
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ABSTRACT: Beside the phosphate binding effect, non-calcium non-aluminum phosphate binder, namely sevelamer hydrochloride (SH), has many other effects in dialysis patients. It can absorb many other compounds, decrease low-density lipoprotein cholesterol (LDL-C) level, and attenuate the progression of vascular calcification; it has been reported to have anti-inflammatory effect. However, it is not clear whether it has any effect on uremic toxins, i.e. serum indoxyl sulfate (IS) and p-cresyl sulfate, (PCS) in hemodialysis (HD) patients. This study was carried out to appraise the effect of sevelamer on serum IS and PCS in HD patients.Five adult HD patients from a single medical center were enrolled in this study; these patients were treated with 800 mg of sevelamer thrice per day for 3 months; a series of biochemical parameters, serum IS and PCS were monitored concurrently.There was a significant reduction in the mean level of phosphate from 7.20 ± 0.70 mg/dL (mean ± SD) before treatment to 5.40 ± 0.50 mg/dL (mean ± SD) after treatment, total cholesterol from 151.00 ± 37.40 mg/dL (mean ± SD) before treatment to 119.20 ± 29.40 mg/dL (mean ± SD) after treatment, and PCS from 31.30 ± 10.60 mg/L (mean ± SD) before treatment to 19.70 ± 10.50 mg/L (mean ± SD) after treatment. On the contrary, this treatment had no effect on IS.A statistically significant reduction of serum phosphate and PCS in HD patients treated with SH suggests that beside the action of lowering serum phosphate, sevelamer may have an important role in the treatment of uremic syndrome by decreasing the uremic toxin.
Project description:Background and hypothesisPruritus is a common and distressing symptom that affects patients with chronic kidney disease. The concentration of protein bounded uremic toxin was associated with the uremic pruritus. The aim is to assess the efficacy of AST-120 for uremic pruritus in hemodialysis patients.Materials and methodsThe participants were enrolled and then divided into the AST-120 treatment group and control group with a ratio of 2:1. All participants underwent pre-observation screenings two weeks before the study with three visits. In the treatment phase (week 1 to week 4), the treatment group added 6g/day of AST-120 along with routine anti-pruritic treatment. Visual analog scale (VAS) and biochemical parameters were measured.ResultsThe VAS score began to be lower in the AST-120 treatment group after the 5th visiting (p < 0.05). The reduction in indoxyl sulfate (IS) at 5th week along with TNF-alpha. The reduction ratio of indoxyl sulfate correlated with reduction of parathyroid hormone.ConclusionThis study has demonstrated that the four-week treatment of AST-120 decreased the severity of uremic pruritus in patients with ESRD. The concentration of IS and TNF-alpha decreased in the AST-120 treatment group. The reduction of iPTH correlated with the reduction of IS in the AST-120 treatment.
Project description:Background and objectivesIndoxyl sulfate and p-cresyl sulfate are important representatives of the protein-bound uremic retention solutes. Serum levels of p-cresyl sulfate and indoxyl sulfate are linked to cardiovascular outcomes and chronic kidney disease progression, respectively. They share important features such as the albumin-binding site, low dialytic clearance, and both originate from protein fermentation. Whether serum concentrations are related is, however, not known.Design, setting, participants, & measurementsIn an observational study in 75 maintenance hemodialysis patients, we studied agreement between indoxyl sulfate and p-cresyl sulfate serum concentrations, dialytic reduction rates, and dialytic clearances. Concentrations were determined by HPLC. Dialytic clearances were determined from total spent dialysate collections. In vitro spiking experiments were performed to explore protein binding characteristics.ResultsIndoxyl sulfate and p-cresyl sulfate total serum concentrations were not related (r = 0.02, P = 0.9), whereas free serum concentrations were only moderately related (r = 0.53, P < 0.001). Indoxyl sulfate and p-cresyl sulfate share the same albumin binding site, for which they are competitive binding inhibitors. Intriguingly, indoxyl sulfate and p-cresyl sulfate reduction rates (r = 0.91, P < 0.001) and dialytic clearances (r = 0.97, P < 0.001) correlated tightly.ConclusionsIndoxyl sulfate and p-cresyl sulfate serum concentrations are not associated, suggesting different metabolic pathways. Indoxyl sulfate and p-cresyl sulfate are both valid markers to monitor behavior of protein-bound solutes during dialysis. Finally, they are competitive binding inhibitors for the same albumin binding site.
Project description:Protein-bound uremic toxins are associated with cardiovascular disease and mortality in patients with chronic kidney disease. We investigated their association with clinical outcomes in patients undergoing chronic hemodialysis (CHD). A prospective cohort study was conducted on 86 Taiwanese patients undergoing CHD. The predictors were indoxyl sulfate and p-cresyl sulfate concentrations, with each analyzed as three tertiles. Outcomes were cardiovascular events and all-cause mortality. During a 25-month follow up period, there were 23 cardiovascular events and seven all-cause mortality events. In the crude survival analysis, the second indoxyl sulfate tertile was shown to be a powerful predictor of cardiovascular events compared with the third tertile (hazard ratio (HR), 3.14; 95% confidence interval (CI), 1.10-8.94), and the first tertile was shown to have a poor but insignificant cardiovascular outcome (HR, 1.09; 95% CI, 0.30-4.00). Moreover, the predictive power of the second indoxyl sulfate tertile for cardiovascular events remained after adjustment for confounders (HR, 5.42; 95% CI, 1.67-17.60). An inverse U-curve relationship was observed between the total serum indoxyl sulfate level and cardiovascular events in our CHD patients. A large-scale study is needed to confirm this relationship.
Project description:A growing number of publications supports a biologic effect of the protein-bound uremic retention solutes indoxyl sulfate and p-cresyl sulfate. However, the use of unrealistically high free concentrations of these compounds and/or inappropriately low albumin concentrations may blur the interpretation of these results. Here, we performed a systematic review, selecting only studies in which, depending on the albumin concentration, real or extrapolated free concentrations of indoxyl sulfate and p-cresyl sulfate remained in the uremic range. The 27 studies retrieved comprised in vitro and animal studies. A quality score was developed, giving 1 point for each of the following criteria: six or more experiments, confirmation by more than one experimental approach, neutralization of the biologic effect by counteractive reagents or antibodies, use of a real-life model, and use of dose-response analyses in vitro and/or animal studies. The overall average score was 3 of 5 points, with five studies scoring 5 of 5 points and six studies scoring 4 of 5 points, highlighting the superior quality of a substantial number of the retrieved studies. In the 11 highest scoring studies, most functional deteriorations were related to uremic cardiovascular disease and kidney damage. We conclude that our systematic approach allowed the retrieval of methodologically correct studies unbiased by erroneous conditions related to albumin binding. Our data seem to confirm the toxicity of indoxyl sulfate and p-cresyl sulfate and support their roles in vascular and renal disease progression.
Project description:Protein binding prevents uremic toxins from removal by conventional extracorporeal therapies leading to accumulation in maintenance dialysis patients. Weakening of the protein binding may enhance the dialytic elimination of these toxins. In ultrafiltration and equilibrium dialysis experiments, different measures to modify the plasma binding affinity and capacity were tested: (i), increasing the sodium chloride (NaCl) concentration to achieve a higher ionic strength; (ii), increasing the temperature; and (iii), dilution. The effects on the dissociation constant K(D) and the protein bound fraction of the prototypical uremic toxin indoxyl sulfate (IS) in plasma of healthy and uremic individuals were studied. Binding of IS corresponded to one site binding in normal plasma. K(D) increased linearly with the NaCl concentration between 0.15 (K(D) = 13.2 ± 3.7 µM) and 0.75 M (K(D) = 56.2 ± 2.0 µM). Plasma dilution further reduced the protein bound toxin fraction by lowering the protein binding capacity of the plasma. Higher temperatures also decreased the protein bound fraction of IS in human plasma. Increasing the NaCl concentration was effective to weaken the binding of IS also in uremic plasma: the protein bound fraction decreased from 89% ± 3% to 81% ± 3% at 0.15 and 0.75 M NaCl, respectively. Dilution and increasing the ionic strength and temperature enhance the free fraction of IS allowing better removal of the substance during dialysis. Applied during clinical dialysis, this may have beneficial effects on the long-term outcome of maintenance dialysis patients.
Project description:The gut microbiota is important for maintaining the integrity of the intestinal barrier, promoting immunological tolerance and carrying out metabolic activities that have not evolved in hosts. Intestinal dysbiosis is associated with chronic kidney disease and probiotic supplementation has been shown to be beneficial. However, it is not known whether gut microorganisms‑specifically, lactic acid bacteria (LAB) can protect against acute kidney injury (AKI). To address this issue, the present study investigated the effects of Lactobacillus salivarius BP121, an intestinal LAB isolated from the feces of newborns, in a rat model of cisplatin‑induced AKI and also in Caco‑2 human intestinal epithelial cells. BP121 prevented cisplatin‑induced AKI in rats, as demonstrated by decreases in inflammation and oxidative stress in kidney tissue and in serum levels of uremic toxins such as indoxyl sulfate (IS) and p‑cresol sulfate (PCS). BP121 also reduced intestinal permeability, as determined using fluorescein isothiocyanate‑dextran by immunohistochemical detection of tight junction (TJ) proteins such as zona occludens‑1 and occludin. The abundance of Lactobacillus spp., which are beneficial intestinal flora, was increased by BP121; this was accompanied by an increase in the concentrations of short‑chain fatty acids in feces. Additionally, H2O2‑induced TJ protein damage was reduced in Caco‑2 cells treated with BP121 culture supernatant, an effect that was reversed by the 5' AMP‑activated protein kinase (AMPK) inhibitor Compound C and Toll‑like receptor (TLR)4 inhibitor TLR4‑IN‑C34. In conclusion, this study demonstrated that L. salivarius BP121 protects against cisplatin‑induced AKI by decreasing inflammation and oxidative stress and this renoprotective effect is partially mediated by modulating the gut environment and thereby suppressing IS and PCS production as well as by regulating AMPK and TLR4 dependent TJ assembly.
Project description:Protein-bound uremic toxins (Indoxyl sulfate [IS] and p-cresyl sulfate [PCS]) are both associated with cardiovascular (CV) and all-cause mortality in subjects with chronic kidney disease (CKD). Possible mechanisms have not been elucidated. In hemodialysis patients, we investigated the relationship between the free form of IS and PCS and 181 CV-related proteins. First, IS or PCS concentrations were checked, and high levels were associated with an increased risk of acute coronary syndrome (ACS) in 333 stable HD patients. CV proteins were further quantified by a proximity extension assay. We examined associations between the free form protein-bound uremic toxins and the quantified proteins with correction for multiple testing in the discovery process. In the second step, the independent association was evaluated by multivariable-adjusted models. We rank the CV proteins related to protein-bound uremic toxins by bootstrapped confidence intervals and ascending p-value. Six proteins (signaling lymphocytic activation molecule family member 5, complement component C1q receptor, C-C motif chemokine 15 [CCL15], bleomycin hydrolase, perlecan, and cluster of differentiation 166 antigen) were negatively associated with IS. Fibroblast growth factor 23 [FGF23] was the only CV protein positively associated with IS. Three proteins (complement component C1q receptor, CCL15, and interleukin-1 receptor-like 2) were negatively associated with PCS. Similar findings were obtained after adjusting for classical CV risk factors. However, only higher levels of FGF23 was related to increased risk of ACS. In conclusion, IS and PCS were associated with several CV-related proteins involved in endothelial barrier function, complement system, cell adhesion, phosphate homeostasis, and inflammation. Multiplex proteomics seems to be a promising way to discover novel pathophysiology of the uremic toxin.
Project description:The NLRP3 inflammasome is responsible for the maturation of caspase-1 and interleukin-1β (IL-1β). Despite the study about basal activity of the NLRP3 inflammasome in hemodialysis (HD) patients, little is known about its inducibility in the milieu of uremia. Peripheral blood mononuclear cells (PBMCs) isolated from 11 HD patients and 14 volunteers without a history of chronic kidney disease, as well as macrophages with or without the uremic toxin indoxyl sulfate (IS) pretreatment, underwent canonical NLRP3 inflammasome induction. Despite the high plasma levels of IL-1β in HD patients, caspase-1 and IL-1β in the PBMCs of HD patients remained predominantly immature and were not secreted in response to the canonical stimulus. In addition, while IS alone facilitated the inflammasome-independent secretion of IL-1β from macrophages, IS exposure before induction reduced the inducibility of the NLRP3 inflammasome, characterized by insufficient maturation of caspase-1. The low expression of inflammasome components, which was observed in both IS-pretreated cells and the PBMCs of HD patients, was probably responsible for the low inducibility.
Project description:BackgroundUremic toxins are associated with various chronic kidney disease-related comorbidities. Indoxyl sulfate (IS), a protein-bound uremic toxin, reacts with vasculature, accelerating atherosclerosis and/or vascular calcification in animal models. Few studies have examined the relationship of IS with clinical outcomes in a large cohort of hemodialysis (HD) patients.MethodsWe included 1170 HD patients from the Japan Dialysis Outcomes and Practice Patterns Study Phase 5 (2012-15). We evaluated the associations of serum total IS (tIS) levels with all-cause mortality and clinical outcomes including cardiovascular (CV)-, infectious- and malignancy-caused events using Cox regressions.ResultsThe median (interquartile range) serum tIS level at baseline was 31.6 μg/mL (22.6-42.0). Serum tIS level was positively associated with dialysis vintage. Median follow-up was 2.8 years (range: 0.01-2.9). We observed 174 deaths (14.9%; crude rate, 0.06/year). Serum tIS level was positively associated with all-cause mortality [adjusted hazard ratio per 10 μg/mL higher, 1.16; 95% confidence interval (CI) 1.04-1.28]. Association with cause-specific death or hospitalization events, per 10 μg/mL higher serum tIS level, was 1.18 (95% CI 1.04-1.34) for infectious events, 1.08 (95% CI 0.97-1.20) for CV events and 1.02 (95% CI 0.87-1.21) for malignancy events after adjusting for covariates including several nutritional markers.ConclusionsIn a large cohort study of HD patients, serum tIS level was positively associated with all-cause mortality and infectious events.
Project description:Hydrogen sulfide (H2S) was the third gasotransmitter to be recognized as a cytoprotectant. A recent study demonstrated that exogenous supplementation of H2S ameliorates functional insufficiency in chronic kidney disease (CKD). However, how the H2S system is impaired by CKD has not been elucidated. The uremic toxin indoxyl sulfate (IS) is known to accumulate in CKD patients and harm the renal tubular cells. This study therefore treated the proximal tubular cells, LLC-PK1, with IS to see how IS affects H2S formation. Our results showed that H2S release from LLC-PK1 cells was markedly attenuated by IS when compared with control cells. The H2S donors NaHS and GYY-4137 significantly attenuated IS-induced tubular damage, indicating that IS impairs H2S formation. Interestingly, IS downregulated the H2S-producing enzymes cystathionine β-synthase (CBS), cystathionine γ-lyase (CSE), and 3-mercaptopyruvate sulfurtransferase (3-MST), and these effects could be reversed by inhibition of the IS receptor, aryl hydrocarbon receptor (AhR). As transcription factor specificity protein 1 (Sp1) regulates the gene expression of H2S-producing enzymes, we further showed that IS significantly decreased the DNA binding activity of Sp1 but not its protein expression. Blockade of AhR reversed low Sp1 activity caused by IS. Moreover, exogenous H2S supplementation attenuated IS-mediated superoxide formation and depletion of the cellular glutathione content. These results clearly indicate that IS activates AhR, which then attenuates Sp1 function through the regulation of H2S-producing enzyme expression. The attenuation of H2S formation contributes to the low antioxidant defense of glutathione in uremic toxin-mediated oxidative stress, causing tubular cell damage.