The contribution of the intestinal microbiota to fracture-induced pain

Bone fractures are painful injuries that disproportionally affect Veterans. Emerging evidence suggests that the intestinal microbiota is a significant regulator of inflammatory, neuropathic, and visceral pain through production of neuroactive metabolites and inflammatory mediators. However, the contribution of the gut microbiome to pain following traumatic bone injuries has remained unexplored. Therefore, the overall goal of this proposal is to establish the gut microbiota as a therapeutic target to modulate the inflammatory pain response to and throughout fracture healing. Our central hypothesis posits that the intestinal microbiota is a critical regulator of pain following fracture through inflammatory signals and production of neuroactive metabolites, and that dietary supplementation with probiotics will alleviate pain during fracture healing. We first propose to assess post- fracture pain and function in mice with a depleted microbiome achieved through a broad-spectrum antibiotic cocktail, and whether dietary supplementation with probiotics will improve these outcomes (Aim 1). The indigenous microbiota and probiotics produce a variety of neuroactive metabolites that influence host metabolism and may contribute to pain sensitization and desensitization during bone healing. We will characterize the role of the intestinal microbiota in metabolic flexibility after fractures using serum metabolomics and metabolic phenotyping studies (Aim 2). Together the proposed experiments will determine whether the gut microbiota is a valid therapeutic target for managing pain during recovery from fractures. The candidate’s long-term career goal is to become an independent VA investigator with a research focus on identifying nutrition-based approaches to improve patient outcomes and quality of life while also enhancing healing of orthopaedic injuries. The award of a CDA-1 will enable the PI to leverage his cumulative expertise and gain new skills in the assessment of pain, function, as well as cell and tissue metabolism to develop novel, yet easily implemented approaches aimed at improving the quality of life of Veterans suffering from painful musculoskeletal injuries and ailments. The proposed work will be completed using a comprehensive training plan under the guidance of an experienced, multidisciplinary mentoring team consisting of VA investigators. This will include recurring meetings with the mentoring team and hands-on training in metabolomics and behavioral assessments of pain and function. The planned innovative research will advance the understanding of the interconnectedness between the gut microbiota, pain, and metabolism following common traumatic bone injuries experienced by Veterans. This may lead to new treatments that decrease the reliance on harmful pain-relieving pharmacological drugs throughout the post-fracture recovery period. This CDA-1 project complements his prior dissertation work that focused on the inflammatory and gut microbiota influences on fracture healing. The proposed research plan, outstanding institutional environment, and experienced mentoring team will provide the necessary skills and experiences to become a successful VA-based independent investigator.