<i>Romboutsia lituseburensis</i>JCM1404 supplementation ameliorated endothelial function via gut microbiota modulation and lipid metabolisms alterations in obese rats

Our previous study revealed moderate-intensity exercise improved endothelial function associated with decreasing Romboutsia in rats on a high-fat diet. However, whether Romboutsia influences endothelial function remains unclear. The aim of this study was to determine the effects of Romboutsia lituseburensis JCM1404 on the vascular endothelium of rats under standard diet (SD) or high-fat diet (HFD). Romboutsia lituseburensis JCM1404 had a better improvement effect on endothelial function under HFD groups, while no significant effect on small-intestinal and blood vessel morphology. HFD significantly decreased villus height of small intestine and increased outer diameter and media thickness of the vascular tissue. After the treatments by R. lituseburensis JCM1404, the expression of claudin5 was increased in the HFD groups. Romboutsia lituseburensis JCM1404 was found to increase alpha diversity in the SD groups, with an increase in beta diversity in the HFD groups. The relative abundance of Romboutsia and Clostridium_sensu_stricto_1 was decreased significantly in both diet groups after R. lituseburensis JCM1404 intervention. The functions of human diseases and endocrine and metabolic diseases significantly downregulated in the HFD groups by Tax4Fun analysis. Furthermore, we found Romboutsia was significantly associated with bile acids, triglycerides, amino acids and derivatives and organic acids and derivatives in the SD groups, while Romboutsia was significantly associated with triglycerides and free fatty acid in the HFD groups. Romboutsia lituseburensis JCM1404 significantly upregulated several metabolism-related pathways by KEGG analysis in the HFD groups, including glycerolipid metabolism, cholesterol metabolism, regulation of lipolysis in adipocytes, insulin resistance, fat digestion and absorption, thermogenesis. Overall, R. lituseburensis JCM1404 supplementation ameliorated endothelial function via gut microbiota modulation and lipid metabolisms alterations in obese rats.