Abstract
The prevalence of chronic kidney disease (CKD) is increasing owing to the elderly population. Here, we investigated the effects of heat-treated Enterococcus faecalis (FK-23) and lysozyme-treated FK-23 (LFK) on the progression of CKD in rats. A CKD model was established using male Wistar rats by subjecting them to right nephrectomy (1K), followed by ischemia and reperfusion (IR). FK-23 or LFK was fed ad libitum as a mixed diet after right nephrectomy. Animals subjected to renal ischemia-reperfusion injury (IRI) showed increased plasma creatinine and blood urea nitrogen levels. Furthermore, in the kidneys, collagen accumulation and α-smooth muscle actin, indicative of fibroblast activation and fibrosis-related gene and protein expression, increased 3 weeks after IRI. FK-23 and LFK suppressed the increase in the mRNA levels of some of these genes. The increase in oxidative stress markers, 4-hydroxy-2-nonenal, endothelial nitric oxide synthase, and nitrotyrosine in the kidney, as well as increased plasma uremic toxins after IRI, were also ameliorated by FK-23 and LFK. Metagenomic analysis of fecal samples revealed that gut microbial alteration caused by IRI was also ameliorated by LFK treatment. These results suggest that Enterococcus faecalis ingredients may improve CKD progression by suppressing oxidative stress and correcting the balance of the intestinal microflora.