TLR4 and Insulin resistance: B. vulgatus and E. coli promote hepatic fat accumulation and exacerbate insulin resistance by producing lipopolysaccharides (LPS), which activates the Toll-like receptor 4 (TLR4) pathway in the liver and nuclear factor kappa B (NF-κB) signaling pathways (Aron-Wisnewsky et al., 2020; Shi et al., 2006; Cai et al., 2005).