Funded Projects

TWIK-related spinal cord K+ (TRESK) channel is abundantly expressed in all primary afferent neurons (PANs) in trigeminal ganglion (TG) and dorsal root ganglion (DRG), mediating background K+ currents and controlling the excitability of PANs. TRESK mutations cause migraine headache but not body pain in humans, suggesting that TG neurons are more vulnerable to TRESK dysfunctions. TRESK knock out (KO) mice exhibit more robust behavioral responses than wild-type controls in mouse models of trigeminal pain, especially headache. We will investigate the mechanisms through which TRESK dysfunction differentially affects TG and DRG neurons. Based on our preliminary finding that changes of endogenous TRESK activity correlate with changes of the excitability of TG neurons during estrous cycles in female mice, we will examine whether estrogen increases migraine susceptibility in women through inhibition of TRESK activity in TG neurons. We will test the hypothesis that frequent migraine attacks reduce TG TRESK currents.

Spinal cord stimulators (SCS) and related devices are commonly used for hard-to-treat pain conditions, but how they work remains unclear. This knowledge is important for improving device design and stimulation patterns, as well as for determining which patients will benefit. Through a series of clinical studies in patients with SCS devices, this project will explore the hypothesis that SCS devices reduce pain by changing the excitability of peripheral sensory nerve fibers in the spinal cord. The results should guide development of biomarkers to advance research further.

As prescription opioid drug abuse and overdose-related deaths continue to skyrocket in the United States, the need for new and more effective non-addictive pain drugs to treat chronic pain remains critical. This research is conducting studies in animal models of a small molecule that has high potential to treat chronic pain conditions associated with neuropathy and/or inflammation. The goal of this project is to conduct dosing and other studies leading up to an animal model study of the potential drug in a toxicology study for 28 days. Results may lead to Investigative New Drug regulatory clearance to begin clinical studies to validate the potential drug’s efficacy and safety.

Although opioid-based analgesics have been proven effective in reducing the intensity of pain for many neuropathic pain conditions, their clinical utility is grossly limited due to the substantial risks involved in such therapy, including nausea, constipation, physical dependence, tolerance, and respiratory depression. Cumulative evidence suggests that human Mas-related G protein-coupled receptor X1 (MRGPRX1) is a promising target for pain with limited side effects due to its restricted expression in nociceptors within the peripheral nervous system; however, direct activation of MRGPRX1 at peripheral terminals is expected to induce itch side effects, limiting the therapeutic utility of orthosteric MRGPRX1 agonists. This finding led to the exploration of positive allosteric modulators (PAMs) of MRGPRX1 to potentiate the effects of the endogenous agonists at the central terminals of sensory neurons without activating peripheral MRGPRX1. An intrathecal injection of a prototype MRGPRX1 PAM, ML382, effectively attenuated evoked, persistent, and spontaneous pain without causing itch side effects. The goal of this study is to develop a CNS-penetrant small-molecule MRGPRX1 PAM that can be given orally to treat neuropathic pain conditions.

The use of a pain imaging technology would allow for objective efficacy data (both pre-clinically and in clinical trials), and reduce costs by enabling smaller sample sizes due to more homogeneous populations; i.e. with a particular “pain signal,” and more accurate measurement of analgesic effects. This research team recently invented a novel positron emission tomography (PET) imaging agent as a tool to address these issues in pain care and therapy development. Although the ability of PET to detect pathological changes for (early) disease detection is widely used in cancer and neurological diseases, it has not yet been used for pain indications. The goals of this project are: 1) to change the evaluation of (experimental) pain therapies, and 2) the standard of care in pain assessment through molecular imaging. The proposed study is designed to determine the feasibility of our imaging agent to objectively measure pain in rodents. This will set the stage for a Phase II study that further develops this agent into a tool for quantifying pain/analgesia.

Neck pain is the fourth leading cause of disability and also a significant cause of cervicogenic headaches. Many of the currently available neck pain treatments are invasive with associated risks and complications, particularly because of the complex anatomy. Magnetic resonance guided focused ultrasound, a novel, completely noninvasive technique, can precisely target spinal facet joints to help ameliorate neck pain, potentially transforming the current practices. The goal of this study is to develop a cervical spine-specific device and demonstrate its safety and efficacy on targeting cervical sensory fibers and the third occipital nerve. The results of these studies will provide an understanding on how to best use this technology for chronic neck pain as well as a basis for translation into human use.

Despite the need for non-opioid treatments for chronic pain, few alternative treatment approaches exist. Transcutaneous auricular neurostimulation (tAN) is a safe and effective treatment for pain during opioid withdrawal; however, researchers do not understand how tAN reduces pain, which limits its clinical use. A better understanding of how tAN affects neurophysiological processes to provide pain relief would likely expand tAN development and use. This interdisciplinary project will conduct research in both healthy adults and those with chronic pain to explain the neurochemical and neurophysiological mechanisms for tAN-based pain relief, and also help optimize treatments and their use.

Patients with severe, intractable chronic pain primarily receive treatment with opioids, and non-opioid treatment options are urgently needed. These patients may be candidates for treatment using other types of pain medications administered via intrathecal injection—that is, injection directly into the fluid-filled space between the membranes surrounding the brain and spinal cord. Intrathecal injection requires much lower medication doses than systemic administration. Centrexion Therapeutics Corporation seeks to develop CNTX-3100, a highly selective and highly potent novel small molecule that activates the nociception receptor (NOPr), for intrathecal administration using a pump approved by the U.S. Food and Drug Administration. In animal studies, such NOPr agonists had powerful analgesic effects when delivered directly to the spinal cord by intrathecal administration. CNTX-3100 has ideal properties for intrathecal delivery and in animal studies provided pain relief and a safety profile that was superior to intrathecally administered morphine. This project will scale up the drug, develop a formulation that ensures a stable product for intrathecal delivery, and conduct preclinical toxicity studies to prepare for a Phase 1 clinical trial.

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.

Acute and chronic pain vary widely across patients, due in large part to genetic differences between individuals. The same variation occurs in preclinical animal models with diverse genetic backgrounds. The development of automated mouse “pain scales” using high-speed videography, machine learning, and custom software allows pain to be assessed in a quantitative manner in nonverbal animals. This technology will be used to identify genetically different mice with high or low pain sensitivity, which will facilitate the development of new therapeutic strategies to treat pain and reduce reliance on opioids.

Chronic pain is maintained, in part, by persistent changes in sensory neurons, including a pathological increase in peptides derived from the neurosecretory protein VGF (non-acronymic). Preliminary findings show that the C-terminal VGF peptide, TLQP-62, contributes to spinal cord neuroplasticity and that TLQP-62 immunoneutralization attenuates established mechanical hypersensitivity in a traumatic nerve injury model of neuropathic pain. This project will test the hypothesis that spinal cord TLQP-62 signaling can be targeted for the development of new chronic pain treatments through immunoneutralization and/or receptor inhibition. It will pursue discovery and validation of TLQP-62-based therapeutic interventions along two parallel lines: identification of TLQP-62 receptor(s) and validation of anti-TLQP-62 antibodies as a potential biological therapeutic option for chronic neuropathic pain conditions.