Could resistant starch supplementation improve inflammatory and oxidative stress biomarkers and uremic toxins levels in hemodialysis patients? A pilot randomized controlled trial.

An imbalance of gut microbiota is considered a new cardiovascular risk factor for chronic kidney disease (CKD) patients, since it is directly associated with increased uremic toxin production, inflammation and oxidative stress. Strategies such as prebiotic supplementation have been suggested to mitigate these complications. We hypothesized that prebiotic-resistant starch could ameliorate uremic toxins levels, oxidative stress, and inflammatory states in hemodialysis (HD) patients. This pilot study evaluated 31 HD patients assigned to either resistant starch (16 g of resistant starch Hi-Maize® 260) or placebo (manioc flour) supplementation, which they received for 4 weeks on alternate days through cookies on dialysis days and powder in a sachet on non-dialysis days. Levels of interleukin (IL)-6, high-sensitive C-reactive protein, thiobarbituric acid reactive substances plasma (TBARS), protein carbonylation, indoxyl sulfate (IS) and p-cresyl sulfate were measured. Anthropometric and biochemical parameters, as well as, food intake were also evaluated. As expected, resistant starch group increased fiber intake (p > 0.01), in addition the prebiotic supplementation reduced IL-6 (p = 0.01), TBARS (p > 0.01), and IS (p > 0.01) plasma levels. No significant differences were evident in the placebo group. Prebiotic-resistant starch supplementation seems to be a promising nutritional strategy to improve inflammation, oxidative stress and to reduce IS plasma levels in CKD patients on HD.

Probiotic Supplementation in Chronic Kidney Disease: A Double-blind, Randomized, Placebo-controlled Trial.

OBJECTIVE: The objective of the study was to evaluate the effects of probiotic supplementation on the gut microbiota profile and inflammatory markers in chronic kidney disease patients undergoing maintenance hemodialysis (HD). DESIGN AND METHODS: This was a randomized, double-blind, placebo-controlled study. Forty-six HD patients were assigned to receive 1 of 2 treatments: probiotic (n = 23; Streptococcus thermophilus, Lactobacillus acidophilus e Bifidobacterialongum, 90 billion colony-forming units per day) or placebo (n = 23) daily for 3 months. Blood and feces were collected at baseline and after intervention. The inflammatory markers (C-reactive protein and interleukin-6) were analyzed by immunoenzymatic assay (enzyme-linked immunosorbent assay). Uremic toxins plasma levels (indoxyl sulfate, p-cresyl sulfate, and indole-3-acetic acid) were obtained by Reversed-Phase High-Performance Liquid Chromatography. Routine laboratory parameters were measured by standard techniques. Fecal pH was measured by the colorimetric method, and the gut microbiota profile was assessed by Denaturing Gradient Gel Electrophoresis analysis. RESULTS: Sixteen patients remained in the probiotic group (11 men, 53.6 ± 11.0 year old, 25.3 ± 4.6 kg/m2) and 17 in the placebo group (10 men, 50.3 ± 8.5 year old, 25.2 ± 5.7 kg/m2). After probiotic supplementation there was a significant increase in serum urea (from 149.6 ± 34.2 mg/dL to 172.6 ± 45.0 mg/dL, P = .02), potassium (from 4.4 ± 0.4 mmol/L to 4.8 ± 0.4 mmol/L, P = .02), and indoxyl sulfate (from 31.2 ± 15.9 to 36.5 ± 15.0 mg/dL, P = .02). The fecal pH was reduced from 7.2 ± 0.8 to 6.5 ± 0.5 (P = .01). These parameters did not change significantly in placebo group. Changes in the percentage delta (Δ) between groups were exhibited with no statistical differences observed. The inflammatory markers and gut profile were not altered by supplementation. CONCLUSIONS: Aprobiotic supplementation failed to reduce uremic toxins and inflammatory markers. Therefore, probiotic therapy should be chosen with caution in HD patients. Further studies addressing probiotic therapy in chronic kidney disease patients are needed.

From bench to the hemodialysis clinic: protein-bound uremic toxins modulate NF-κB/Nrf2 expression.

PURPOSE: Uremic toxins produced by gut microbiota (indoxyl sulfate-IS, p-cresyl sulfate-p-CS, and indole-3-acetic acid-IAA) accumulate in hemodialysis (HD) patients and exhibit potent inflammatory effects. However, the impact of these toxins on nuclear E2-related factor 2 (Nrf2) and nuclear factor-kappa B (NF-κB) expression in HD patients remains poorly defined. The aim of this study was to evaluate the association between uremic toxins and Nrf2/NF-κB expression in vitro (RAW 264.7 macrophage-like cells) and in peripheral blood mononuclear cells from HD patients. METHODS: Uremic toxins, C-reactive protein (CRP), interleukin-6 (IL-6) and malondialdehyde (MDA) levels were measured in fifteen HD patients and nine healthy individuals. RAW 264.7 macrophage-like cells were incubated with IS, as a prototype of protein-bound uremic toxin. Nrf2 and NF-κB expressions were analyzed by RT-qPCR. RESULTS: HD patients presented high levels of inflammatory markers, MDA and uremic toxins. In addition, they presented high NF-κB and low Nrf2 expression. Uremic toxins were positively correlated with NF-κB expression (IS, ρ = 0.58, p < 0.003; p-CS, ρ = 0.71, p < 0.001; IAA, ρ = 0.62, p < 0.001) and negatively with Nrf2 (IS, ρ = - 0.48, p = 0.01; p-CS, ρ = - 0.46, p < 0.02). Uremic toxins also exhibited positive correlations with CRP and MDA levels. Multivariate analysis revealed that p-CS is a determinant factor of NF-κB expression. In RAW 264.7 culture, NF-κB mRNA expression was stimulated by IS, while Nrf2 was downregulated. CONCLUSIONS: Thus, uremic toxins may stimulate NF-κB mRNA and decrease Nrf2 expression in HD patients and, consequently, trigger inflammation and oxidative stress.

Protein-Bound Uremic Toxins from Gut Microbiota and Inflammatory Markers in Chronic Kidney Disease.

OBJECTIVE: Protein-bound uremic toxins from gut microbiota tend to accumulate in chronic kidney disease (CKD) patients and are poorly removed by current dialysis techniques. These toxins induce inflammation and are associated with cardiovascular disease (CVD). The aim of this study was to report the relationship between uremic toxins and inflammatory and cardiovascular markers in CKD patients. DESIGN: This was a cross sectional study. SUBJECTS: Twenty-one nondialysis patients were included (43% men, 63.0 ± 7.8 years, glomerular filtration rate: 34.4 ± 12.5 mL/min) as well as 29 hemodialysis (HD) patients [58% men, 52.7 ± 10.3 years, time on dialysis 54 (31-94.5 months)]. MAIN OUTCOME MEASURE: Total levels of uremic toxins (IS, p-CS, and IAA) were assessed by high-performance liquid chromatography with fluorescence detection. C-reactive protein, Interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), and calprotectin plasma levels were determined by immunometric assays. RESULTS: HD patients presented higher inflammatory markers and uremic toxins levels than nondialysis patients. IL-6 levels were positively correlated with IS (r = 0.49; P = .03), p-CS (r = 0.35; P = .04) and IAA (r = 0.36; P = .03). A positive correlation was also observed between MCP-1 levels with IS (r = 0.72; P = .001), p-CS (r = 0.48; P = .001) and IAA (r = 0.75; P = .0001). Linear regression showed that IS was an independent predictor for IL-6 and MCP-1 levels after adjustment. CONCLUSION: Plasma uremic toxins were associated with higher IL-6 and MCP-1 levels in CKD patients, potentially playing a role in the development of CVD.