PROJECT SUMMARY Inflammation is a major driver of disorders such as temporomandibular joint osteoarthritis (TMJ-OA) has been implicated in a significant cohort of patients with temporomandibular disorders (TMDs), a collective group of conditions that can lead to debilitating pain, persistent headaches, and impaired range-of-motion. Recent clinical and animal studies suggest that inflammation can perpetuate further TMJ harm, sprouting of sensory axons innervating the joint, and altered excitability of sensory neurons resulting in the formation of chronic neuropathic pain. Further, OA’s wide-ranging etiologies are further complicated by understudied sexually dimorphic elements that increase the risk of joint degeneration and hypersensitivity to pain in women. Thus, there is an urgent need for comprehensive evaluation of TMJ and innervating sensory neurons across sex in OA to determine the mechanisms that underlie sensory and neuropathic OA pain, and the associated sexual dimorphisms create significant barriers for developing targeted, mechanism-specific therapies for OA and OA pain. To fill this knowledge gap, we propose a team science proposal that will take a multidisciplinary and multi-omics approach. Taking advantage of the team’s complementary expertise in OA mouse models, single- cell transcriptomics, and musculoskeletal biology (Lim; Co-PL#1) and neural tracers, single-cell spatial proteomics, and neurobiology (Keeler; Co-PI#2), our objective is to use a multi-omic approach to identify novel target cell populations and molecular mechanisms that drive sexually dimorphic TMJ-OA pathophysiology. Ultimately, the imaging mass cytometry-based proteomic analysis of the sensory neurons that innervate joint- associate tissues will enhance our understanding of how chronic exposure to inflammatory and degenerative conditions, such as those observed in patients with osteoarthritis, impact the nature and functionality of joint- innervation neurons. In addition, understanding which transcriptomic alterations translate into changes at the protein-level will help us identify general and sex-specific therapeutic candidates to treat chronic joint pain. Alignment with the Parent Project: These cutting-edge molecular profiling technologies are distinct, yet highly complementary to the research aims proposed in the parent grant (P20GM139760; Delaware Center for Musculoskeletal Research). Future plans: We are excited to have the opportunity to build collaboration among two labs and obtain key pilot data. The completion of the supplement will lead to a larger co-PI R01 project that will determine the molecular and cellular mechanisms that drive chronic and neuropathic pain in TMJ-OA. We will leverage the resources and expertise through the parent COBRE and the existing INBRE at UD.

Project Narrative Temporomandibular (jaw) joint osteoarthritis can cause severe chronic neuropathic pain that can negatively impact quality of life. We are using a multi-omic approach using single-cell RNAseq and state-of-the-art spatial proteomics to map the immune and neural underpinnings of changes driven by osteoarthritis in the jaw joint. This application uses a cross-disciplinary strategy to tackle a substantial public health concern - jaw joint damage and pain associated with aging - that aligns well with the musculoskeletal focus of the parent COBRE grant and provides a foundation to develop a strong collaborative program to develop strategies for chronic pain treatment.