Funded Projects

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.

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.

As many as 64% of patients with Temporomandibular Joint Disorders (TMJDs) report symptoms consistent with Irritable Bowel Syndrome (IBS). However the underlying connection between these comorbid conditions is unclear and treatment options are poor. As such, pain management for these Chronic Overlapping Pain Conditions (COPCs) is a challenge for physicians and patients. This project will determine whether the convergence of pain from different peripheral tissues and perceived stress occurs in the brain and elicits a change in central neural processing of painful stimuli. This project will identify and validate specific lipids, enzymes and metabolic pathways that change expression in the brain during the transition from acute to chronic overlapping pain that can be therapeutically targeted to treat COPCs. Multi-disciplinary approaches will be used to combine brain imaging, visualization of spatial distribution of molecules, genetics, pharmacological and behavioral research techniques.

An important component of neuropathic pain is spontaneous or ongoing pain, such as burning pain or intermittent paroxysms of sharp and shooting pain, which may result from abnormal spontaneous activity in sensory nerves. However, due to technical limitations, spontaneous activity in sensory neurons in vivo has not been well studied. Using in vivo imaging in genetically-modified mice, preliminary findings identified spontaneously-firing clusters of neurons formed within the dorsal root ganglia (DRG) after traumatic nerve injury that exhibits increased spontaneous pain behaviors. Furthermore, preliminary evidence has been collected that cluster firing may be related to abnormal sympathetic sprouting in the sensory ganglia. This project will test the hypothesis that cluster firing is triggered by abnormal sympathetic inputs to sensory neurons, and that it underpins spontaneous paroxysmal pain in neuropathic pain models. Findings from this project will identify potential novel therapeutic targets for the treatment of neuropathic pain.

Endometriosis is an often-painful disorder in which uterine tissue grows outside the uterus. Treatment of endometriosis-associated pain involves use of opioids in many women. This project aims to study a culprit gene thought to be involved with the disorder (capillary morphogenesis gene or CMG2) as a target for new, nonopioid pain medications. The research will also clarify how CMG2 s affects endometriosis-associated pain to test the effects of new medications for endometriosis 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.

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 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.

Many chronic pain conditions are dependent upon activity of the sympathetic nervous system. Sympathetic blockade is used clinically in chronic pain conditions, but the clinical and preclinical evidence for this practice is incomplete. We propose that certain pathological pain conditions require intact sympathetic innervation of the sensory nervous system at the level of the dorsal root ganglion (DRG) and that release of sympathetic transmitters enhances local inflammation and leads to pain. Our preliminary data show large, rapid, and long-lasting reduction of pain behaviors and inflammatory responses following a"microsympathectomy" (mSYMPX) in both neuropathic and inflammatory pain models. Our aims are to: 1) characterize the effects of mSYMPX on pain and on local inflammation in the DRG; 2) explore the molecular mechanisms for sympathetic regulation of inflammatory responses in the DRG; and 3) assess the functional role of sympathetic transmitters in the sympathetically mediated inflammatory responses in the DRG.

Myofascial pain syndrome is a prevalent and debilitating condition and can aggravate other conditions such as sickle cell disease. This project will use total body imaging using positron emission tomography/computed tomography (TB-PET/CT) to identify and monitor this pain syndrome and potential treatments over time. The research will use TB-PET/CT to assess myofascial tissue effects of chronic low back pain and sickle cell disease pain. The first phase of the project will assess health changes observed by TB-PET/CT imaging in painful and non-painful myofascial tissues compared to healthy myofascial tissue. The second phase of the research will be a randomized, controlled longitudinal interventional study to evaluate the effectiveness of acupuncture on myofascial pain syndrome, using TB-PET/CT imaging to assess changes.

Immune checkpoint proteins regulate the immune system to prevent it from indiscriminately attacking cells. Some cancers activate these immune checkpoints to avoid attack, and drugs that target certain immune checkpoints are approved for cancer treatment. The same pathway may also be involved in pain because immune checkpoint proteins, such as programmed death 1 (PD-1) and the molecule that binds to it (programmed death ligand 1 [PD-L1]), also are found in sensory neurons, microglia, and macrophages. This project will investigate PD-1/PD-L1 in different cell populations to determine their contribution to pain and to the effects of opioids such as morphine. This knowledge may help identify new drugs for pain management that modify immune checkpoint activity.

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.