In conclusion, the interaction between gut microbiota Enterobacteriaceae, Enterococcaceae, Lactobacillaceae, and Bifidobacteriaceae may control the occurrence of IBD, neuroinflammation, and anxiety/depression through the regulation of gut microbiota LPS production and LPS-induced NF-κB activation-mediated BDNF expression. Here, BDNF is linked to major depressive disorder.