TLR2 and obesity due to melanocortin 4 receptor deficiency: Its outer membrane protein Amuc_1100 binds to Toll-like receptor-2 (TLR-2) in the intestinal epithelial cells (IECs), and the downstream signaling pathway leads to the improvement of the epithelial tight junction and triggers anti- and pro-inflammatory cytokines that prevent obesity, insulin resistance, and inflammation in the visceral adipose tissue (Si et al., 2022).