Disorder of gut amino acids metabolism during CKD progression is related with gut microbiota dysbiosis and metagenome change.

Chronic kidney disease (CKD) is a worldwide public health problem. Uremic retention solutes such as indoxyl sulfate (IS) and p-cresyl sulfate (PCS) are accumulated in CKD patients and are associated with the incidence of CKD progression. Amino acids are the major precursors of uremic retention solutes in gut. The dynamic change of amino acid metabolism in the gut during CKD progression has not been reported previously. In this paper, we studied the dynamic change of gut IS/PCS precursor and amino acid metabolism profile during CKD progression in 5/6 nephrectomized (5/6Nx) rats model. The related gut microbiota and metagenome profile was also studied. Rat plasma, urine and feces were collected at different time points after nephrectomization. Plasma IS and PCS, fecal indole (the precursor of IS), p-cresol (the precursor of PCS) and 19 kinds of amino acids were analyzed by LC-MS. During CKD progression, 5/6 Nx rats showed increased plasma IS, PCS concentration and increased fecal indole, p-cresol concentration. 5/6 Nx rats also showed disordered gut amino acids metabolism profile which became more significant along with the progession of CKD. The abundance of some specific gut bacteria also changed significantly in 5/6 Nx rats. The 16S rDNA sequencing data of gut microbiota was further analyzed by an online tool PICRUSt, a large-scale computational method for metagenomes prediction with 16S rDNA sequencing data. The content of each gene was compared between the two groups by Mann-Whitney U test, and then the significantly regulated genes in 5/6 Nx group were subjected to KEGG website. The amino acid metabolism related genes were picked out. Most of these genes are more abundant in 5/6 Nx groups. Our study showed that gut amino acids metabolism profile was disordered with CKD progression, which was highly related to the gut microbiota dysbiosis and metagenome change. And that regulation of gut amino acids metabolism pathway may be a possible way to intervene the progression of CKD.