Funded Projects

Pain associated with surgery is experienced by millions of patients every year. Although post-surgical pain usually resolves as the surgical site heals, up to half of the patients develop chronic pain after surgery. Opioids remain the mainstay treatment for post-surgical pain which are fraught with serious side-effects and abuse liabilities. The endogenous mechanism that leads to the resolution of post-surgical pain remain unclear, specifically the effects of surgery on the metabolism of sensory neurons and how those changes influence the resolution of post-surgical pain are not known. Preliminary findings suggest that surgical trauma suppresses pyruvate oxidation while increased glutamine catabolism was associated with the resolution of post-surgical pain. This project will test the hypothesis that tissue incision and surgery disrupt the expression of the glutamine transporter ASCT2, which then prevents the resolution of post-incisional pain and aims to validate ASCT2 as a therapeutic target. This project will also employ pharmacological, genetic and animal pain model studies test a novel RNA expression-based strategy to enhance ASCT2 expression in DRG sensory neurons and alleviate postoperative pain in animal model systems. Successful completion of this project would validate ASCT2 as a novel endogenous non-opioid and non-addictive mechanism-based target for the resolution of postoperative pain.

Chronic pain is a major health burden associated with immense economic and social costs. Predictive biomarkers that can identify individuals at risk of developing severe and persistent pain, which is associated with worse disability and greater reliance on opioids, would promote aggressive, early intervention that could halt the transition to chronic pain. The applicant’s team uncovered evidence of a unique cortical biomarker signature that predicts pain susceptibility (severity and duration). This biomarker signature could be capable of predicting the severity of pain experienced by an individual minutes to months in the future, as well as the duration of pain (time to recovery). Analytical validation of this biomarker will be conducted in healthy participants using a standardized model of the transition to sustained myofascial temporomandibular pain. Specifically the biomarker signature will be tested for its ability to predict an individual’s pain sensitivity, pain severity, and pain duration and will perform initial clinical validation.

This project aims to validate Peptidase Inhibitor 16 (PI16) as a novel target for the treatment of chronic pain using mouse models and tissues of human patients with neuropathy. PI16 was identified as a novel regulator of chronic pain in preclinical bench studies. PI16 is a small molecule that has not been studied in the context of pain. Mice that are deficient for PI16 function are protected against mechanical allodynia (tactile pain from light touch) in spared nerve injury (SNI) and paclitaxel models of neuropathic pain. PI16 is only detectable in fibroblasts around peripheral nerves (perineurium), and in the meninges of dorsal root ganglia (DRG), spinal cord, and brain, but not in neurons, glia or leukocytes. PI16 levels in perineurial and DRG meningeal fibroblasts increase during neuropathic pain. Increased PI16 secretion by DRG meningeal and perineurial fibroblasts may promote chronic pain by increasing blood nerve barrier (BNB) permeability and leukocyte trafficking into nerve and DRG.

Osteoarthritis (OA) is the most common form of arthritis and a leading cause of pain and disability. Current challenges of managing OA are that there is no OA disease-modifying drug available, there are few effective treatment strategies, and there is an over-reliance on the use of opioids to manage OA-related joint pain. This project aims to validate vascular endothelial growth factor receptors 1 and 2 (VEGFR 1 receptor = Flt1) and (VEGFR 2 receptor = Flk1) as novel therapeutic targets for OA. This is based on a hypothesis that blocking these two specific receptors of VEGF will inhibit cartilage tissue degeneration and alleviate pain symptoms. This study will test the role of VEGFR-1 and -2 in multiple OA animal models using multiple available VEGF inhibitor molecules. The findings from these studies will develop a rationale for future clinical trials to target VEGFR-1 and -2 for OA patients and develop a novel non-addictive treatment for both joint pain and OA pathology.

Cerebral palsy (CP), the leading cause of childhood disabilities in the United States, refers to a group of neurological disorders that appear in infancy or early childhood and permanently affect body movement and muscle coordination. The experience of pain is one of the most common, poorly understood, and inadequately treated conditions in CP, impairing health and quality of life for both patients and caregivers. To understand why pain and motor dysfunction occur together, a model that accurately replicates both is needed. This project will validate an established, rabbit model of CP motor dysfunction for use in studying and developing effective treatments for CP-associated pain.

Spinal cord injury (SCI) impairs sensory transmission and leads to chronic, debilitating neuropathic pain. While our understanding of the development of chronic pain has improved, the available therapeutics provide limited relief. We will examine the peripheral immune and inflammatory response. Secondary inflammation in response to SCI is a series of temporally ordered events: an acute, transient upregulation of chemokines, followed by the recruitment of monocytes/macrophages and generation of an inflammatory environment at the lesion site in the spinal cord, but also surrounding primary nociceptors in the dorsal root ganglia (DRG). These events precede neuropathic pain development. Previous work indicates that after SCI, macrophage presence in the DRG correlates with neuropathic pain. We propose to study: 1) whether the phenotype of macrophages that infiltrate the DRG is different than those that persist chronically after SCI and 2) how manipulation of macrophage phenotype affects nociceptor activity and pain development.