Additionally, gut-derived LPS from Gram-negative bacteria such as E. coli activates Toll-like receptor 4 (TLR4), triggering the increased production of pro-inflammatory cytokines including TNF-α, IL-6, and IL-1β—all of which are elevated in the peritoneal fluid of individuals with endometriosis [53,54,55,56]. Here, TNF is linked to endometriosis.