Abstract
Gut microbiota is involved in generation of uremic toxins in chronic kidney disease (CKD) patients on hemodialysis (HD), like indoxyl sulfate (IS) that is originated from tryptophan amino acid fermentation. To evaluate the tryptophan intake by chronic renal failure patients on HD and its possible relationship with IS plasma levels. Participated of the study 46 patients with CKD on HD regular program (56.5% men; 52.7 ± 10.3 years; 63 (32.2-118.2) months on HD; BMI 25.6 ± 4.9 kg/m2). The tryptophan intake was evaluated by a 24-hours dietary recall (R-24h) performed on 3 different days. Routine biochemical tests and anthropometric measurements were evaluated. IS plasma levels were determined by High Performance Liquid Chromatography (HPLC) with fluorescent detection and the interleukin-6 (IL-6) plasma levels by immunoenzymatic method (ELISA, Enzyme Linked Immunosorbent Assay). The average of tryptophan intake was according to recommendation, but IS plasma levels (35.0 ± 11.9 mg/L) were elevated, however according to the EUTox values for uremic individuals. There was no correlation between the tryptophan intake and IS plasma levels. However, there was positive correlation between protein intake and tryptophan and variables used to evaluate lean body mass, and moreover, IS levels were positively associated with IL-6 (r = 0.6: p = 0.01). The present study suggests that tryptophan dietary intake may not be a determinant factor to IS levels. However, it suggests that gut microbiota may play an important role in systemic inflammation in patients with CKD.
Highlights
Gut microbiota is involved in generation of uremic toxins in chronic kidney disease (CKD) patients on hemodialysis (HD), like indoxyl sulfate (IS) that is originated from tryptophan amino acid fermentation
Tryptophan is often present in one’s diet. Intake levels of this amino acid may be related to the determination of IS serum levels, as metabolites derived from tryptophan such as IS result from the metabolism of dietary tryptophan by gut bacteria. Considering that this uremic toxin has been related to increased risk of cardiovascular disease in patients with CKD, and that cardiovascular disease is the main cause of death of individuals with CKD, this study aimed to assess tryptophan intake levels in patients with CKD on HD and the possible correlations with IS serum levels
Since tryptophan is metabolized by gut bacteria into a substrate for the synthesis of uremic toxin indoxyl sulfate, the present study aimed to verify whether the intake of this amino acid by patients with CKD on HD was correlated with total IS serum levels
Summary
Gut microbiota is involved in generation of uremic toxins in chronic kidney disease (CKD) patients on hemodialysis (HD), like indoxyl sulfate (IS) that is originated from tryptophan amino acid fermentation. Objective: To evaluate the tryptophan intake by chronic renal failure patients on HD and its possible relationship with IS plasma levels. Conclusion: The present study suggests that tryptophan dietary intake may not be a determinant factor to IS levels. It suggests that gut microbiota may play an important role in systemic inflammation in patients with CKD. Patients with CKD are affected by changes in gut microbiota, characterized by the growth of bacterial species that increase the production of toxic gases, uremic toxins, amines, ammonia, and elevate the concentrations of pathogenassociated molecular patterns (PAMPs) such as lipopolysaccharides (LPS)
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