Funded Projects

Peripheral nerve injury-induced upregulation of three axonal guidance phosphoproteins correlates with the development of neuropathic pain through an unidentified mechanism: 1) collapsin response mediator protein 2 (CRMP2); 2) the N-type voltage-gated calcium (CaV2.2); 3) the NaV1.7 voltage-gated sodium channel. Injury induced phosphorylated-CRMP2/CaV2.2 and phosphorylated-CRMP2/NaV1.7 upregulation in the sensory pathway may promote abnormal excitatory synaptic transmission in spinal cord that leads to neuropathic pain states. This project will validate CRMP2 phosphorylation as a novel target in neuropathic pain using innovative tools. Examples include a genetic approach (crmp2S522A) in mice as well as a non-opioid pharmacological approach (a novel CRMP2-phsphorylation targeting compound). Demonstrating that inhibition of CRMP2 phosphorylation reverses or prevents neuropathic pain will promote the discovery and validation of a novel therapeutic target (CRMP2-phosphorylation) to facilitate the development of novel pain therapeutics.

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.

There is an urgent unmet need for more efficacious analgesics that act via a non-opioid pathway. Mitogen Activated Protein Kinase-interacting kinase 2 (MNK2) is an enzyme that has been implicated in pain signaling, and there is compelling evidence that inhibiting MNK2 has significant pain-reducing effects with few side-effects. Since MNK2 selective inhibitors have not yet been identified, selective inhibition of MNK2 with a small molecule has not been possible. The development of such compounds will enable studies that will illuminate key differences between MNK2 and MNK1. More importantly, from a therapeutic standpoint, highly selective MNK2 inhibitors may prove to have enhanced efficacy and a more favorable side-effect profile than molecules that inhibit both MNK2 and MNK1. This project will support the design and synthesis of at least one MNK2 inhibitor, with >100-fold selectivity over MNK1, that may be developed into a lead compound for treating neuropathic pain.

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.

A substantial proportion of Americans seeking emergency care after traumatic stress exposure (TSE) are at a high risk of chronic pain and opioid use/misuse. Physiologic systems involved in the stress response could possibly play a critical role in the development of chronic pain after TSE. FK506-binding protein 51 (FKBP51) is an intracellular protein known to affect glucocorticoid negative feedback inhibition and component of stress response, provides an important non-opioid therapeutic target for such chronic pain. This project will test the hypothesis that functional inhibition of FKBP51 prevents or reduces enduring stress-induced hyperalgesia in a timing, dose, and duration-dependent manner in animal models of single prolonged stress alone and in combination with surgery. This project will also test if FKBP51 inhibition enhances recovery following TSE via reduction in pro-inflammatory responses in peripheral and central tissues. It will also test whether FKBP51 inhibition effects cardiotoxicity or addiction. Completion of these studies will increase understanding of FKBP51 as a novel therapeutic target for the prevention of chronic pain and opioid use/misuse resulting from TSE.

There is a distinct neural ensemble in the brain that encodes the negative affective valence of pain. This project will identify novel targets to treat pain by determining the molecular identity of these BLA nociceptive cells via in situ hybridization and single cell RNAsequencing (scRNA-seq). Resolving the molecular identity of these ACC nociceptive cells will also reveal new targets to treat pain affect. To achieve these results the project will catalog candidate Gi/o-GPCR targets in BLA and ACC, test their utility to treat pain, and verify these new targets have no effect in the brain?s reward and breathing circuitry. The experiments in this project will also evaluate each target for abuse potential and effects on breathing by using behavioral assays for reward processing and whole-body plethysmography, respectively. To evaluate whether our results in rodents are likely to translate clinically, there will be an analysis of expression patterns of these drug targets in human tissue using in situ hybridization.

Neuropathic pain conditions are difficult to treat, and novel non-narcotic analgesics are desperately needed. The G protein-coupled receptor 160 (GPR160) has emerged as a novel target for analgesic development, as GPR160 in the spinal cord may play a role in the transition from acute to chronic pain. Cocaine- and Amphetamine-Regulated transcript peptide (CARTp) was identified as a ligand for GPR160. Blocking endogenous CARTp signaling in the spinal cord attenuates neuropathic pain, whereas intrathecal injection of CARTp evokes painful hypersensitivity in rodents through GPR160-dependent extracellular signal-regulated kinase (ERK) and cyclic AMP response element-binding pathways (CREB). This project will isolate and biochemically characterize GPR160 and establish methods for biochemical characterization of GPR160 interaction with CARTp activator. Researchers will miniaturize and optimize biochemical assay and scale up protein production for future high throughput biochemical screening to identify potent inhibitors of GPR160 activation. These studies are critical for defining the molecular mechanism of CARTp/GPR160 interactions and initiating large-scale screens for new inhibitors to develop novel therapeutics.

A key marker of inflammation in Osteoarthritis (OA) is accompanied by significantly increased sensory innervation within the diseased joint. This study aims to validate the hypothesis that defective bone resorbing cells are responsible for the enlarged bone cavity, giving rise to the inflammatory marker causing further increases in levels sensory innervation and resulting in increased OA pain perception.

Chemotherapy-induced painful peripheral neuropathy (CIPN) is the most common toxicity associated with widely used chemotherapeutics. CIPN accounts for significant dose reductions and/or discontinuation of these life-saving treatments. Unfortunately CIPN can also persist in cancer-survivors, adversely affecting their quality of life. CIPN is not well-managed with existing pain therapeutics. Recent preliminary findings suggest that the transcription factor hypoxia-inducible factor alpha (HIF1A) is the target for the chemotherapeutic bortezomib, a proteasome inhibitor. This project will test the hypothesis that bortezomib chemotherapy-induced expression of HIF1A, PDHK1 and LDHA constitute an altered metabolic state known as aerobic glycolysis (AG) that leads to the initiation and maintenance of peripheral neuropathy and pain using a novel tumor-bearing animal model of CIPN. This project aims to validate HIF1A as a therapeutic target for the prevention of CIPN, as well as validate PDHK1 and LDHA as non-opioid therapeutic targets for chronic or established CIPN in animal models.

A major recent advancement for the field of pain research is the recognition of immune system dysregulation as a contributor to the most serious adverse consequences of pain from injury. Accumulating data from clinical and laboratory studies place the activation of B lymphocytes at the center of much of this work, particularly with respect to chronic pain and disability-related outcomes. Validation of this B cell hypothesis could lead directly to trials testing the efficacy of novel or existing immunomodulating agents on posttraumatic pain. To achieve these goals a well-validated core mouse model of limb fracture will be employed with additional studies to be conducted in incisional and nerve injury models to broaden the assessment of B cell mediated effects on pain. Age and sex will be included as variables to enhance rigor.

There is an urgent need for new non-opioid therapeutic agents that treat the pain associated with Osteoarthritis (OA) ? a chronic, progressive disease that leads to pain in weightbearing joints, pain during movement, and pain at rest. This project will refine techniques for targeting several proteins expressed in sensory neurons associated with OA pain, with the goal of testing the potential of these proteins to serve as targets for development of effective, non-opioid painkillers.

Neuropathic pain is a debilitating affliction present in 26% of diabetic patients, with substantial impact on the quality of life. Despite this significant impact and prevalence, current therapies for painful diabetic neuropathy (PDN) are only partially effective, and the molecular mechanisms underlying neuropathic pain in diabetes are not well understood. Our long-term goal is to elucidate the molecular mechanisms responsible for PDN in order to provide targets for the development of therapeutic agents. Our objective is to identify the molecular cascade linking CXCR4/SDF-1 chemokine signaling to DRG nociceptor hyper-excitability, neuropathic pain, and small fiber degeneration. Our aims will determine: 1) the ion-channel current profile of the nociceptor hyper-excitable state produced by CXCR4/SDF-1 signaling in PDN; 2) the gene expression profile of the nociceptor hyper-excitable state produced by CXCR4/SDF-1 signaling in PDN; and 3) the specific features of nociceptor mitochondrial dysfunction produced by CXCR4/SDF-1 signaling in PDN.

Mismanagement of orofacial chronic pain, such as temporomandibular joint and muscle disorders (TMJD) and oral cancer, substantially contributes to opioid overuse; overdose-related deaths; and cardiovascular, renal, and neurological complications at epidemic proportions. The current paradigm implies that orofacial conditions could trigger maladaptation of the immune system and plasticity supporting persistent inflammation, which influences the development and maintenance of orofacial chronic pain. LIGHT (TNFSF14) and Lymphotoxin-beta (LT?), members of the tumor necrosis factor superfamily, provide a balance between protective immunity and immunopathology during chronic inflammatory diseases. This project will test the hypothesis that targeting LIGHT and LT? signaling could prevent the development and inhibit the maintenance of chronic pain produced by TMJD and oral cancer, via peripheral mechanisms involving plasticity of immune, stromal, and tumor cells, as well as sensory neurons. The proposed research is significant as it advances our understanding of mechanisms regulating the development and maintenance of orofacial pain and offers new therapeutic targets and an immunotherapeutic approach for preventing and blocking chronic pain during TMJD and oral cancer.