Strategy to delay the progression of chronic kidney disease by targeting gut microbiota and uremic toxins metabolism pathway / 药学学报

Chronic kidney disease (CKD) is a serious chronic disease with high incidence, poor prognosis, and a variety of complications. Indoxyl-sulfate (IS) and p-cresol sulfate (PCS) are two typical gut-derived uremic toxins, which are produced by the co-metabolism of intestinal microbes and the host. With the progression of CKD, gut-derived uremic toxins such as IS and PCS accumulate in patients with CKD and thereafter accelerate the progression of CKD. Gut microbiota is closely related with CKD, and targeting gut microbiota to regulate gut-derived uremic toxins synthesis and metabolic pathways may be a promising strategy to delay the progression of CKD. In this paper, the relationship between gut microbiota, gut-derived uremic toxins, and CKD was analyzed, and the strategy to delay the progression of CKD by targeting gut microbiota and uremic toxins metabolism pathway was proposed.

Effect of indoxyl sulfate on proliferation and expression of inflammatory cytokines and ROS in human periodontal ligament cells / 上海交通大学学报（医学版）

Objective : To explore the effects of Indoxyl sulfate (IS) on proliferation activity, expression of inflammatory factors and reactive oxygen species (ROS) in human periodontal ligament cells (hPDLCs). Methods ¡¤ The primary hPDLCs were cultured by using tissue explant method in vitro. MTT assay was employed to evaluate the effect of IS on proliferation activity of hPDLCs. The mRNA and protein expressions of IL-1β, IL-6, and IL-8 were detected by using real-time PCR and ELISA assay. DCFDA fluorescence probe was used to detect intracellular ROS expression and ROS in the cytoplasm under fluorescence microscope. Results ¡¤ The viability of hPDLCs was inhibited by IS at the concentra-tion of 125 μmol/L on 24, 48 and 72 hours. The inhibitory effect was presented in a dose- and time- dependent manner. IS could upregulate the mRNA and protein expression of inflammatory cytokines including IL-1β, IL-6 and IL-8 as well as promote ROS in hPDLCs. Conclusion ¡¤ IS may play an important role in the association between chronic kidney diseases and periodontitis through inhibiting the activity of hPDLCs, pro-moting the expression of inflammatory cytokines and increasing intracellular ROS level.

Effect and mechanism of Huangkui capsuleon reduction of uremic toxin accumulation in an animal model of chronic kidney disease / 药学学报

Uremic toxins are harmful substances that accumulate in the body when the renal function declines in patients with chronic kidney disease (CKD). It is an important factor contributing to accelerated progression of CKD. There is no effective treatment for reducing uremic toxins. As an extensively used medicine for treatment of CKD in the clinic, Huangkui capsule is effective but the mechanism of its action remains unclear. This study investigated the effect of Huangkui on the accumulation of uremic toxins in CKD rats, with the discussion about its mechanism of action. UPLC-TQ/MS was used to detect the accumulation of uremic toxins in CKD rats after oral gavage with Huangkui. 16S rDNA sequencing technology was used to analyze the gut bacteria composition in rats. HPLC-FLD was used to detect the uremic toxins and their molecular precursors in feces. The effect and mechanism of Huangkui on the uremic toxin precursor in gut bacteria were studied by anaerobic culture system in vitro. All procedures were approved by the Institutional Animal Care and Use Committee of the Nanjing University of Chinese Medicine. The results showed that Huangkui (0.675 g·kg-1) could effectively inhibit the accumulation of uremic toxin indoxyl sulfate (IS) in CKD rats, with IS concentration in rat's plasma, liver and kidney decreased by 49.5%, 68.9% and 40.6%, respectively. Huangkui didn't affect the metabolic pathway of IS in host liver, didn't intervene the process of the IS precursor molecule indole conversion to IS. Instead, Huangkui significantly decreased the indole content in gut, with the indole in CKD rat's feces decreased by 46.4%, suggesting that the gut bacteria may be a target for intervene IS biosynthesis by Huangkui. Huangkui didn't affect the abundance of enterobacteriaceae bacteria (the main gut flora of indole synthesis) in CKD rats, suggesting that Huangkui didn't interfere with indole biosynthesis by directly affecting the abundance of indole synthesis related bacteria. Huangkui at 4 000, 400, 40, and 4 μg·mL-1 showed a dose-dependent inhibition of the indole production by gut bacteria in vitro. The bacteria tryptophan transport concentration decreased from 83.4 μmol·L-1 to 43.6 μmol·L-1 after co-incubated with Huangkui for 12 h, suggesting that Huangkui inhibited indole production of gut bacteria by interfering with tryptophan transportation. These results indicate that gut bacteria may be a potential target for alleviation of uremic toxin accumulation and for delaying CKD progression.

Predictive Factors for Efficacy of AST-120 Treatment in Diabetic Nephropathy: a Prospective Single-Arm, Open-Label, Multi-Center Study

BACKGROUND: Removal of uremic toxins such as indoxyl sulfate by AST-120 is known to improve renal function and delay the initiation of dialysis in patients with advanced chronic kidney disease. However, it is unclear whether the addition of AST-120 to conventional treatments is effective in delaying the progression of renal dysfunction in patients with diabetic nephropathy. METHODS: A total of 100 patients with type 2 diabetes and renal dysfunction (serum creatinine levels ranging from 1.5 to 3.0 mg/dL) were recruited from eight centers in Korea and treated with AST-120 (6 g/day) for 24 weeks. The primary endpoint was improvement in renal function measured as the gradient of the reciprocal serum creatinine level (1/sCr) over time (i.e., the ratio of 1/sCr time slope for post- to pre-AST-120 therapy). A response was defined as a ratio change of the regression coefficient of 1/sCr ≤ 0.90. RESULTS: Renal function improved in 80.3% of patients (61/76) after 24 weeks of AST-120 treatment. There were no differences between responder and non-responder groups in baseline characteristics except for diastolic blood pressure (73.5 ± 9.5 mmHg in the responder group vs. 79.3 ± 11.1 mmHg in the non-responder group; P = 0.046). Serum lipid peroxidation level decreased significantly in the responder group (from 2.25 ± 0.56 μmol/L to 1.91 ± 0.72 μmol/L; P = 0.002) but not in the non-responder group. CONCLUSION: The addition of AST-120 to conventional treatments may delay the progression of renal dysfunction in diabetic nephropathy. The antioxidant effect of AST-120 might contribute to improvement in renal function.

Assessment of Hepatic Cytochrome P450 3A Activity Using Metabolic Markers in Patients with Renal Impairment

BACKGROUND: The renal function of individuals is one of the reasons for the variations in therapeutic response to various drugs. Patients with renal impairment are often exposed to drug toxicity, even with drugs that are usually eliminated by hepatic metabolism. Previous study has reported an increased plasma concentration of indoxyl sulfate and decreased plasma concentration of 4β-hydroxy (OH)-cholesterol in stable kidney transplant recipients, implicating indoxyl sulfate as a cytochrome P450 (CYP) inhibiting factor. In this study, we aimed to evaluate the impact of renal impairment severity-dependent accumulation of indoxyl sulfate on hepatic CYP3A activity using metabolic markers. METHODS: Sixty-six subjects were enrolled in this study; based on estimated glomerular filtration rate (eGFR), they were classified as having mild, moderate, or severe renal impairment. The plasma concentration of indoxyl sulfate was quantified using liquid chromatography-mass spectrometry (LC-MS). Urinary and plasma markers (6β-OH-cortisol/cortisol, 6β-OH-cortisone/cortisone, 4β-OH-cholesterol) for hepatic CYP3A activity were quantified using gas chromatography-mass spectrometry (GC-MS). The total plasma concentration of cholesterol was measured using the enzymatic colorimetric assay to calculate the 4β-OH-cholesterol/cholesterol ratio. The correlation between variables was assessed using Pearson's correlation test. RESULTS: There was a significant negative correlation between MDRD eGFR and indoxyl sulfate levels. The levels of urinary 6β-OH-cortisol/cortisol and 6β-OH-cortisone/cortisone as well as plasma 4β-OH-cholesterol and 4β-OH-cholesterol/cholesterol were not correlated with MDRD eGFR and the plasma concentration of indoxyl sulfate. CONCLUSION: Hepatic CYP3A activity may not be affected by renal impairment-induced accumulation of plasma indoxyl sulfate.

Relationship between levels of indoxyl sulfate and severity of coronary artery disease / 实用医学杂志

Objective Indoxyl sulfate (IS) is associated with endothelial damage, NF-κB activation and induces the development of atherosclerosis. The purpose of this study was to investigate the relationship between serum IS levels and the severity of coronary artery stenosis and the relationship among IS and various cardiovascular risk factors. Methods Serum IS concentrations were measured using ultra performance liquid chromatography in 191 consecutive patients presenting with stable angina. The associations between serum IS levels and angio-graphic indexes of the number of diseased vessels, modified Gensini scores and calcium scores were determined. Results Patients with significant coronary artery stenosis were found to have higher serum IS levels than those with normal coronary arteries. Multivariate analysis showed that serum IS levels were found to be independently associated with the presence and severity of coronary artery disease (CAD). Furthermore, statistically significant correlation was observed between the serum IS levels and age, Agatston calcium score, volume calcium score, modifed Gensini score, coronary lesions, coronary disease and Framingham-10 year risk score. Conclusions Se-rum IS levels are significantly higher in the presence of CAD and correlate with the severity of the disease and coro-nary atherosclerosis scores,which suggests that increased serum IS may be involved in the pathogenesis of coronary atherosclerosis.

Klotho alleviates toxic effect of indoxyl sulfate on vascular endothelial cells and its mechanism / 中华肾脏病杂志

Objective To investigate the effect of klotho on the human vein umbilical endothelial cells (HUVECs) injury induced by indoxyl sulfate (IS) and to explore its mechanism and the role of endoplasmic reticulum stress (ERS) in this process.Methods (1) The cell vitalities of HUVECs incubated with different concentration of IS (5,25,50 mg/L) for 48 h and with 50 mg/L IS fordifferent time points (12,24,48 h) were measured by CCK-8 assay.(2) HUVECs were incubated with 50 mg/L IS and different concentration of klotho (0,1,10,100 μg/L) for 48 h and their cell viabilities were measured by CCK-8 assay.(3) HUVECs were divided into four groups:control group,IS group (50mg/L IS),klotho group (50 mg/L IS+ 100 μg/L klotho) and Compound C group (50 mg/L IS+100 μg/L klotho+ 10 μmol/L Compound C).The cell vitality and the apoptosis of HUVECs were evaluated by CCK-8 assay and flow cytometry,respectively.The mRNA and protein expressions of GRP78 and CHOP were measured by real-time PCR and Western blotting.The phosphorylation level of AMPK was tested by Western blotting.Results IS inhibited cell vitality in the time-dependent and concentration-dependent manner.The cell viability of HUVECs with 50 mg/L IS was lower than normal control (P＜0.05).The inhibited cell vitality induced by IS was partly restored by klotho in concentration-dependent manner.The cell viability was higher in 100 μg/L klotho+50 mg/L IS group than 50 mg/L IS group (P ＜ 0.05).Compared with control group,the expressions of GRP78 and CHOP and cell apoptosis increased,however,the level of phosphorylated AMPK (p-AMPK) decreased in IS group (all P ＜ 0.05).Compared with IS group,the expressions of GRP78 and CHOP and cell apoptosis decreased and the level of p-AMPK increased in klotho group (all P ＜ 0.05).Furthermore,the above effects of klotho could be partly blocked by Compound C.The above indexes showed statistical differences between Compound C group and klotho group.Conclusions IS can inhibit the HUVECs cell vitality,and induce ERS and cell apoptosis.Klotho protein could antagonize the above effects,probably through activating AMPK pathway and reducing ERS-mediated cell apoptosis.

Klotho alleviates toxic effect of indoxyl sulfate on vascular endothelial cells and its mechanism / 中华肾脏病杂志

Objective To investigate the effect of klotho on the human vein umbilical endothelial cells (HUVECs) injury induced by indoxyl sulfate (IS) and to explore its mechanism and the role of endoplasmic reticulum stress (ERS) in this process.Methods (1) The cell vitalities of HUVECs incubated with different concentration of IS (5,25,50 mg/L) for 48 h and with 50 mg/L IS fordifferent time points (12,24,48 h) were measured by CCK-8 assay.(2) HUVECs were incubated with 50 mg/L IS and different concentration of klotho (0,1,10,100 μg/L) for 48 h and their cell viabilities were measured by CCK-8 assay.(3) HUVECs were divided into four groups:control group,IS group (50mg/L IS),klotho group (50 mg/L IS+ 100 μg/L klotho) and Compound C group (50 mg/L IS+100 μg/L klotho+ 10 μmol/L Compound C).The cell vitality and the apoptosis of HUVECs were evaluated by CCK-8 assay and flow cytometry,respectively.The mRNA and protein expressions of GRP78 and CHOP were measured by real-time PCR and Western blotting.The phosphorylation level of AMPK was tested by Western blotting.Results IS inhibited cell vitality in the time-dependent and concentration-dependent manner.The cell viability of HUVECs with 50 mg/L IS was lower than normal control (P＜0.05).The inhibited cell vitality induced by IS was partly restored by klotho in concentration-dependent manner.The cell viability was higher in 100 μg/L klotho+50 mg/L IS group than 50 mg/L IS group (P ＜ 0.05).Compared with control group,the expressions of GRP78 and CHOP and cell apoptosis increased,however,the level of phosphorylated AMPK (p-AMPK) decreased in IS group (all P ＜ 0.05).Compared with IS group,the expressions of GRP78 and CHOP and cell apoptosis decreased and the level of p-AMPK increased in klotho group (all P ＜ 0.05).Furthermore,the above effects of klotho could be partly blocked by Compound C.The above indexes showed statistical differences between Compound C group and klotho group.Conclusions IS can inhibit the HUVECs cell vitality,and induce ERS and cell apoptosis.Klotho protein could antagonize the above effects,probably through activating AMPK pathway and reducing ERS-mediated cell apoptosis.

Analysis of serum protein-bound toxins levels in patients undergoing peritoneal dialysis and its influencing factors / 第二军医大学学报

Objective To compare the levels of indoxyl sulfate (IS) and p-cresyl sulfate (PCS), representative substances of serum protein-bound toxins,between patients undergoing peritoneal dialysis (PD) and healthy volunteers, and to explore the factors influencing the levels of serum IS and PCS. Methods Limosis vein blood (3 mL) were collected from 72 PD patients in Peritoneal Dialysis Center and 24 healthy voluteers in Physical Examination in Changzheng Hospital of Second Military Medical University from Feb. 2015 to Jul. 2015. The concentrations of serum total IS,total PCS,free IS and free PCS were detected by high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ES--MS/MS) method. The relationship between IS, PCS and age, gender, small molecule toxins,adequacy of PD, residual renal function,nutritional status and C-reaction protein (CRP) in PD patients were analyzed by simple correlation andmultivariable linear regression analysis. Results The concentrations of serum total IS and total PCS in PD patients were significantly lower than those in healthy volunteers (P<0. 001). Compared with PD patients without residual renal function (RRF), the concentration of serum total IS was significantly lower in PD patients with RRF (P = 0. 001). Serum total IS was positively correlated with free IS (r=0. 719,P<0. 01) and dialysis duration (r=0. 306,P<0. 01),while tt was negatively correlated with residual renal Kt/V (r=-0. 372, P<0. 01),residual renal creatinine clearance rate (Ccr) (r=-0. 515,P<0. 01),and residual renal estimated glomerular filtration rate (eGFR) (r=-0. 495,P<0 01). Serum free IS was negatively correlated with residual renal Ccr (r=-0. 430, P〈0. 01) and residual renal eGFR (r= -0. 431,P〈0. 01). Serum total IS and free IS were not related to age,hemoglobin or CRP.conclusion serum level is negatively correlated with RRF. But not with age, hemoglobin or CRP, suggesting that proection of RRF is conducive to the removal of serum IS in parients undergoing PD.

Indoxyl sulfate exerts an immunomodulatory effect on monocyte-derived-dendritic cells / 实用医学杂志

Objective To explore the effect of indoxyl sulfate (IS) on the differentiation, maturation and immunological function of human monocyte derived dendritic cells (mDCs), in order to provides evidence for mechanism of IS in atherosclerosis. Methods Human peripheral blood mononuclear cells isolated by double gradient centrifugation were cultured for immature mDCs by rhGM?CSF and rhIL?4 in vitro. All cases were randomly divided into PBS group, LPS group(1 μg/mL), IS.1 group(30 μmol/L), IS.2 group(300 μmol/L)and IS.3 group (600 μmol/L). The phenotypic maturation of mDCs was evaluated by flow cytometry (FCM) and functional maturation of mDCs was analyzed by measuring FITC?dextran uptake and ELISA. Results IS significantly upregulated the expression of CD80, CD83, CD86 and MHC II key membrane molecules on mDCs, while downregulating phagocytosis and increasing the secretion of IL?12p70 by mDCs (P<0.05). And the LPS and IS showed typical morphology with rough surface, long protrusions and fusiform. 300 μmol/L IS is the most appropriate stimulus concentration. Conclusion Stuctural, phenotypic and functional maturation of dendritic cells derived from human monocytes can be induced by indoxal sulphate at defined concentrations, which may be one of the mechanisms involved in the process of atherosclerosis.

Inhibition of indoxyl sulfate-induced intrarenal renin-angiotensin system activation: targeting the aryl hydrocarbon receptor

Indoxyl sulfate, a protein-bound uremic toxin, leads to CKD (chronic kidney disease) progression and its complications through the activation of AhR (aryl hydrocarbon receptor) and RAS (renin-angiotensin system). Inhibition of these pathways may slow the development of CKD and CKD-associated complications.

AST-120 Improves Microvascular Endothelial Dysfunction in End-Stage Renal Disease Patients Receiving Hemodialysis

PURPOSE: Endothelial dysfunction (ED) is a pivotal phenomenon in the development of cardiovascular disease (CVD) in patients receiving hemodialysis (HD). Indoxyl sulfate (IS) is a known uremic toxin that induces ED in patients with chronic kidney disease. The aim of this study was to investigate whether AST-120, an absorbent of IS, improves microvascular or macrovascular ED in HD patients. MATERIALS AND METHODS: We conducted a prospective, case-controlled trial. Fourteen patients each were enrolled in respective AST-120 and control groups. The subjects in the AST-120 group were treated with AST-120 (6 g/day) for 6 months. Microvascular function was assessed by laser Doppler flowmetry using iontophoresis of acetylcholine (Ach) and sodium nitroprusside (SNP) at baseline and again at 3 and 6 months. Carotid arterial intima-media thickness (cIMT) and flow-mediated vasodilation were measured at baseline and 6 months. The Wilcoxon rank test was used to compare values before and after AST-120 treatment. RESULTS: Ach-induced iontophoresis (endothelium-dependent response) was dramatically ameliorated at 3 months and 6 months in the AST-120 group. SNP-induced response showed delayed improvement only at 6 months in the AST-120 group. The IS level was decreased at 3 months in the AST-120 group, but remained stable thereafter. cIMT was significantly reduced after AST-120 treatment. No significant complications in patients taking AST-120 were reported. CONCLUSION: AST-120 ameliorated microvascular ED and cIMT in HD patients. A randomized study including a larger population will be required to establish a definitive role of AST-120 as a preventive medication for CVD in HD patients.

Association between indoxyl sulfate and bone histomorphometry in pre-dialysis chronic kidney disease patients / Associação entre indoxil sulfato e histomorfometria óssea em pacientes renais crônicos pré-diálise

Introduction: Experimental studies have suggested that indoxyl sulfate (IS), a protein-bound uremic toxin, may be involved in the development of renal osteodystrophy. Objective: evaluate the association between IS levels and biochemical parameters related to mineral metabolism and bone histomorphometry in a cohort of pre-dialysis chronic kidney disease (CKD) patients. Methods: This is a post-hoc analysis of an observational study evaluating the association between coronary calcification and bone biopsy findings in 49 patients (age: 52 ± 10 years; 67% male; estimated glomerular filtration rate: 36 ± 17 ml/min). Serum levels of IS were measured. Results: Patients at CKD stages 2 and 3 presented remarkably low bone formation rate. Patients at CKD stages 4 and 5 presented significantly higher osteoid volume, osteoblast and osteoclast surface, bone fibrosis volume and bone formation rate and a lower mineralization lag time than CKD stage 2 and 3 patients. We observed a positive association between IS levels on one hand and the bone formation rate, osteoid volume, osteoblast surface and bone fibrosis volume on the other. Multivariate regression models confirmed that the associations between IS levels and osteoblast surface and bone fibrosis volume were both independent of demographic and biochemical characteristics of the study population. A similar trend was observed for the bone formation rate. Conclusion: Our findings demonstrated that IS is positively associated with bone formation rate in pre-dialysis CKD patients. .

Introdução: Estudos experimentais indicam que o indoxil sulfato (IS), uma toxina urêmica ligada à proteína, pode estar envolvido no desenvolvimento da osteodistrofia renal. Objetivo: Avaliar a associação entre os níveis séricos de IS e parâmetros bioquímicos do metabolismo mineral e da histomorfometria óssea em uma coorte de pacientes com doença renal crônica (DRC) pré-diálise. Métodos: Análise post-hoc de um estudo que avaliou a associação entre calcificação coronariana e histomorfometria óssea em 49 pacientes (idade: 52 ± 10 anos; 67% sexo masculino; taxa de filtração glomerular estimada: 36 ± 17 ml/min). Os níveis séricos de IS foram dosados. Resultados: Pacientes com DRC estágio 2 e 3 apresentaram uma taxa de formação óssea baixa. Pacientes com DRC estágio 4 e 5 apresentaram volume osteoide, superfícies osteoblástica e osteoclástica, volume de fibrose e taxa de formação óssea significativamente maiores e intervalo de mineralização significativamente menor que os pacientes com DRC estágio 2 e 3. Os níveis séricos de IS associaram-se positivamente com a taxa de formação óssea, volume osteoide, superfície osteoblástica e volume de fibrose. A análise de regressão multivariada identificou que o IS é um fator independente determinante da superfície osteoblástica e fibrose. Uma tendência similar foi observada para a taxa de formação óssea. Conclusão: Nosso estudo sugere que, na DRC pré-dialítica, o IS correlaciona-se positivamente com a formação óssea. .

p-Cresyl sulfate and indoxyl sulfate in pediatric patients on chronic dialysis / 소아과

PURPOSE: Indoxyl sulfate and p-cresyl sulfate are important protein-bound uremic retention solutes whose levels can be partially reduced by renal replacement therapy. These solutes originate from intestinal bacterial protein fermentation and are associated with cardiovascular outcomes and chronic kidney disease progression. The aims of this study were to investigate the levels of indoxyl sulfate and p-cresyl sulfate as well as the effect of probiotics on reducing the levels of uremic toxins in pediatric patients on dialysis. METHODS: We enrolled 20 pediatric patients undergoing chronic dialysis; 16 patients completed the study. The patients underwent a 12-week regimen of VSL#3, a high-concentration probiotic preparation, and the serum levels of indoxyl sulfate and p-cresyl sulfate were measured before treatment and at 4, 8, and 12 weeks after the regimen by using fluorescence liquid chromatography. To assess the normal range of indoxyl sulfate and p-cresyl sulfate we enrolled the 16 children with normal glomerular filtration rate who had visited an outpatient clinic for asymptomatic microscopic hematuria that had been detected by a school screening in August 2011. RESULTS: The baseline serum levels of indoxyl sulfate and p-cresyl sulfate in the patients on chronic dialysis were significantly higher than those in the children with microscopic hematuria. The baseline serum levels of p-cresyl sulfate in the peritoneal dialysis group were significantly higher than those in the hemodialysis group. There were no significant changes in the levels of these uremic solutes after 12-week VSL#3 treatment in the patients on chronic dialysis. CONCLUSION: The levels of the uremic toxins p-cresyl sulfate and indoxyl sulfate are highly elevated in pediatric patients on dialysis, but there was no significant effect by probiotics on the reduction of uremic toxins in pediatric dialysis patients. Therefore, studies for other medical intervention to reduce uremic toxins are also necessary in pediatric patients on dialysis.