Abstract More than 90% of individuals experience a substantial traumatic stress exposure (TSE) in their lifetime. While most individuals recover following TSE, a substantial subset develop chronic musculoskeletal pain (CMSP). Despite growing evidence that mechanisms driving CMSP are vastly different in men and women, sex-specific mechanisms that drive the transition from acute to chronic pain following TSE remain poorly understood. This lack of knowledge is an important barrier to the discovery of novel therapeutics for the prevention/treatment of CMSP. The proposed work will help address this barrier by evaluating sex-specific, highly influential microRNA (miRNA) regulatory mechanisms affecting CMSP development. Experiments will center on miR-19, a miRNA repeatedly demonstrated to have an important sex-dependent influence on the pathogenesis of chronic pain and related neuropsychiatric disorders. Based on substantial preliminary data from the investigative team, experiments will evaluate the overarching hypothesis that miR-19 drives CMSP development differently in men vs. women via sex-dependent effects on circadian rhythm biology and TLR4-driven innate immune responses. Proposed experiments will leverage the translational research expertise of the study team by performing causation and mechanistic studies using both human cohort data and animal model systems. Human cohort data analyses will include first-in-kind transcriptomic, physiologic, and neuroimmune data collected as part of the AURORA study, a forty-million-dollar study that enrolled thousands of men and women trauma survivors and followed them prospectively over the course of one year. Objective accelerometry-based measures of circadian rhythmicity, measures of immune cell profiling/intracellular signaling (via mass cytometry), RNA and microRNA sequencing data, cytokine profiles of AURORA samples, and self-report pain and quantitative sensory testing of study participants will provide a unique opportunity to comprehensively evaluate study hypotheses. In addition, results from human cohort analyses will be supported by miR-19 knock-down, rescue, and gene expression studies in a well-validated and robust animal model of TSE-induced enduring stress induced hyperalgesia. By the end of the award period, we will have gained important new insights into sex-specific mechanisms of CMSP development and will elucidate exciting new therapeutic strategies for men and women.