Kunihiro Sonoda

Sarcopenia, characterized by skeletal muscle atrophy, was previously considered age-related; however, it is also associated with other diseases. Nonalcoholic fatty liver disease (NAFLD) is known to cause sarcopenia, and its complications have been reported to affect prognosis. The intestinal microbiota of patients with NAFLD or sarcopenia has been found to be altered compared to that of healthy individuals. However, the alterations that occur when both diseases coexist in humans or experimental animals remain unclear. Therefore, this study aimed to determine the intestinal microbiota changes associated with NAFLD with sarcopenia in SHRSP5/Dmcr rats at the time of concomitant disease. Fecal samples were collected from the rectum of SHRSP5/Dmcr rats fed a normal diet (non-NAFLD and non-Sarcopenia, n = 5) or a high-fat and high-cholesterol diet (NAFLD and Sarcopenia, n = 5) for 20 weeks, and subjected to 16S rRNA analysis. In the NAFLD and sarcopenia group, the diversity of the intestinal microbiota was reduced; further, the bacterial species reported in patients with NAFLD or sarcopenia were also changed. At the family level, the abundances of Akkermansiaceae, Bacteroidaceae, and Tannerellaceae were significantly higher whereas Ruminococcaceae and Lactobacillaceae were decreased in the NAFLD and sarcopenia group. At the genus level, the abundances of Akkermansia , Bacteroides , Ruminococcus , and Parabacteroides were significantly higher whereas the abundance of Lactobacillus was significantly decreased in the NAFLD and sarcopenia group. Overall, these findings help improve the existing understanding regarding the intestinal microbiota changes observed in conditions where NASH and sarcopenia co-occur.

Nonalcoholic steatohepatitis (NASH) is a chronic liver disease that leads to liver cirrhosis and hepatocellular carcinoma. Endothelial dysfunction caused by hepatic lipotoxicity is an underlying NASH pathology observed in the liver and the cardiovascular system. Here, we evaluated the effect of dietary nitrite on a rat NASH model. Stroke-prone, spontaneously hypertensive 5/Dmcr rats were fed a high-fat/high-cholesterol diet to develop the NASH model, with nitrite or captopril (100 mg/L, each) supplementation in drinking water for 8 weeks. The effects of nitrite and captopril were evaluated using immunohistochemical analyses of the liver and heart tissues. Dietary nitrite suppressed liver fibrosis in the rats by reducing oxidative stress, as measured using the protein levels of nicotinamide adenine dinucleotide phosphate oxidase components and inflammatory cell accumulation in the liver. Nitrite lowered the blood pressure in hypertensive NASH rats and suppressed left ventricular chamber enlargement. Similar therapeutic effects were observed in a captopril-treated rat NASH model, suggesting the possibility of a common signaling pathway through which nitrite and captopril improve NASH pathology. In conclusion, dietary nitrite attenuates the development of NASH with cardiovascular involvement in rats and provides an alternative NASH therapeutic strategy.