Microglial TLR4 Mediates Post-UTI Chronic Pelvic Pain

Urinary tract infections (UTIs) are a major risk factor for interstitial cystitis/bladder pain syndrome (IC/BPS), yet the mechanisms driving chronic pelvic pain and associated symptoms remain poorly understood. Here, we investigated the role of microglia and Toll-like receptor 4 (TLR4) in a mouse model of post-UTI chronic pelvic pain (PUPP). Infection with E. coli induced persistent pelvic allodynia that was significantly attenuated by microglial depletion (PLX5622) or inhibition (minocycline), indicating a key role for microglia in pain maintenance. In contrast, microglial depletion did not improve urinary dysfunction or anxiety– and depression-like behaviors. Prefrontal cortex microglia of PUPP mice exhibited reduced microglial branching complexity and a less ramified phenotype, indicative of an activated microglial state. Transcriptomic profiling of brain CD11b+ cells revealed a reactive microglial signature enriched for chemokines, NFΚB-related genes, and immediate early response genes, alongside pathways involved in immune regulation and leukocyte recruitment. Both general and microglia-specific TLR4 deletion reduced pelvic allodynia and reduced microglial morphological features of activation. Consistent with this, pharmacological TLR4 inhibition in vitro suppressed LPS-induced NFΚB activation, cytokine secretion, and CD68 expression. Together, these findings identify microglial TLR4 as a critical mediator of post-UTI chronic pelvic pain.