TLR4 and post-traumatic stress disorder: Based on the observed TLR4 suppression and gut microbiota remodeling, we propose that electroacupuncture associates microbiota with TLR4 via dual mechanisms: (1) reducing pro-inflammatory bacterial colonization and endotoxin (e.g., LPS) release, thereby attenuating TLR4-mediated inflammation; and (2) modulating microbiota-derived metabolites (e.g., SCFAs) to inhibit TLR4 signaling via portal circulation and vagal afferent pathways, ultimately influencing brain function to alleviate PTSD [50].