MP07-19 ACYLOXYACYL HYDROLASE REGULATES MICROGLIAL PHENOTYPE IN A MOUSE MODEL OF INTERSTITIAL CYSTITIS

Abstract

INTRODUCTION AND OBJECTIVE: Interstitial cystitis/bladder pain syndrome (IC/BPS) is a devastating condition of chronic pelvic pain. We previously linked a locus encoding acyloxyacyl hydrolase (Aoah) with pain severity in a murine model of IC. AOAH-deficient mice develop pelvic allodynia and exhibit symptoms co-morbid with IC/BPS, such as altered voiding and a depressive phenotype. Microglia are the resident immune cells of the central nervous system (CNS), and studies have linked altered microglial morphology and activation to neuropathic pain and depression. It is also well established that microglial activation can be modulated by the gut microbiota, and AOAH dysbiosis has been reported in IC/BPS patients. Therefore, we examined the microglial phenotype in AOAH-deficient mice and the potential role of microglia in modulating pelvic pain. METHODS: To analyze changes in microglial morphology, brains from wild type (WT) C57BL/6 and AOAH-deficient mice were sectioned and stained for the microglial marker P2RY12. Following immunohistochemistry, z-stacks were acquired and skeletal analyses were performed using Image J. Activation of microglia was measured through Western blotting and a proteome profiler array of mouse cytokines using brain lysates. To address the functional role of microglia in pelvic pain, microglia were eliminated from the CNS of AOAH-deficient and WT mice by oral administration of chow containing PLX5622. Mice were exposed to mechanical stimulation of the pelvic area with von Frey filaments prior to and following microglial elimination. RESULTS: Our preliminary data revealed altered microglial morphology in AOAH-deficient mice compared to WT mice. AOAH-deficient mice exhibited hyper-ramified microglia, suggesting a surveillance phenotype, in the cortex and Barrington’s nucleus, an essential region for micturition. We also observed hyper-ramified microglia in the paraventricular nucleus, a regulator of stress and depression. Microglia were less ramified in the hippocampus, consistent with an activated phenotype. Due to the morphological changes, we expect to observe differences in cytokine release between WT and AOAH-deficient mice, reflecting these differential activation states. In addition, we expect that microglia elimination will alleviate pelvic allodynia and depression in AOAH-deficient mice. CONCLUSIONS: Overall, we observed that microglial phenotype is dependent on AOAH, suggesting microglia-specific receptors or cytokines may be considered as future therapeutic targets for treating IC/BPS. Source of Funding: NIDDK awards U01 DK082342 and R01 DK066112-06S1