Funded Projects

Cholecystokinin B receptor (CCKBR) is a molecule found in the brain that helps regulate anxiety and depression but also influences the development of tolerance to opioids. CCKBR levels are also increased in models of nerve injury-induced (neuropathic) pain. Therefore, targeting CCKBR may offer a new approach to treating neuropathic pain and the associated anxiety and depression. Researchers have developed mouse antibodies that can inactivate CCKBR. However, to be usable in humans without causing an immune response, these antibodies need to be modified to include more human sequences. This project will use a fragment of the CCKBR antibody, modify it with the addition of human antibody sequences, and then select the clones that bind most strongly and specifically to human CCKBR. These will then be tested in cell and animal models of neuropathic pain to identify the most promising candidates for further evaluation in humans.

Voltage-gated sodium channels such as Nav1.7, Nav1.8, and Nav1.9 transmit pain signals in nerve fibers and are molecular targets for pain therapy. While Nav channels have been validated as pharmacological targets for the treatment of pain, available therapies are limited due to incomplete efficacy and significant side effects. Taking advantage of recent advances in structural biology and computational-based protein design, this project aims to develop antibodies to attach to Nav channels and freeze them in an inactive state. These antibodies can then be further developed as novel treatments for chronic pain.

Chronic pain from tissue injury often stems from long-term changes in spinal cord circuits that change nerve sensation. Reversing these changes may provide better pain therapeutics. Previous work in animal models showed that activating G protein-coupled receptor 37 (GPR37) dampens nerve signal intensity after long-term stimulation and alleviates pain behavioral responses. This project aims to validate GPR37 in the spinal cord as a useful target for new treatments for neuropathic pain. The work will facilitate screening and identification of new molecules that activate GPR37, which can then be tested for efficacy and safety in further research in animal models of pain.

There is a continued need to discover and validate new targets for potential therapeutic strategies for effective and safe treatment of pain. This project focuses on the protein metadherin, also known as astrocyte elevated gene-1 protein (AEG-1), as a possible new target for pain treatment. Preliminary studies have shown that mice genetically engineered to lack metadherin had significantly lower inflammation and chronic pain-related behaviors. This project aims to further validate AEG-1 as a pain target and test whether reducing levels in white blood cells called macrophages might work as a therapeutic strategy to reduce chronic inflammatory and/or neuropathic pain using an innovative nanoparticle approach to target specific cells.

Neuropathic pain is characterized by neuronal hyperexcitability and spontaneous activity, properties associated with activity of hyperpolarization-activated, cyclic nucleotide-regulated (HCN1-4) channels, the source of the pacemaker current, Ih. Inhibition of HCN1-mediated Ih elicits marked antihyperalgesia in multiple animal models of neuropathic pain, including models for direct nerve injury and chemotherapy-induced peripheral neuropathy, and does so with little or no disruption to either normal pain processing or baseline behaviors and activities. The overall objective is to develop a peripherally restricted HCN1 inverse-agonist as a therapeutic for neuropathic pain. Researchers have generated a novel small molecule that combines an antihyperalgesic HCN1 inhibitor with a motif that controls distribution and membrane presentation and is a potential non-opioid antihyperalgesic treatment for peripheral neuropathic pain.

Recent studies have reported that neuropathic pain involves changes in the central nervous system that are linked to necroptosis (programmed necrotic cell death) and release of cellular components that create neuroinflammation. Necroptosis is a type of necrotic cell death affected by the protein receptor-interacting serine/threonine-protein kinase 1 (RIPK1 or RIP1). Preliminary studies also indicate that pain increases levels of RIPK1 in key brain regions implicated in pain processing. This project aims to further validate RIPK1 as a target for neuropathic pain using a newly developed positron emission tomography imaging approach. The work will pave the way for new brain-penetrant RIPK1 inhibitors as a safe, effective, and nonaddictive treatment approach for neuropathic pain.

MNK-eIF4E signaling is activated in nociceptors upon exposure to pain or peripheral nerve injury, promoting cytokines and growth factors and increasing nociceptor excitability, which leads to neuropathic pain. Genetic or pharmacological inhibition of MNK signaling blocks and reverses nociceptor hyperexcitability as well as behavioral signs of neuropathic pain. A clinical phase drug for cancer shows strong specificity as an MNK inhibitor but requires optimization because MNK inhibition in the central nervous system (CNS) may lead to depression, an unacceptable side effect for a neuropathic pain drug. The research team plans a targeted medicinal chemistry and screening campaign directed at generating a MNK-inhibitor-based neuropathic pain treatment with the goal of restricting its CNS penetration while retaining potency, specificity, and in vivo bioavailability and efficacy.

The development of non-addictive pain therapeutics can help counter opioid addiction and benefit patients, including those who suffer from neuropathic pain, in particular diabetic neuropathic pain (DNP). This project’s goal is to develop a safe, efficacious, and non-addictive small-molecule drug that activates Kv7 voltage-gated potassium channels to address overactive neuronal activity in DNP. Researchers will discover Kv7 activators that favor Kv7 isoforms altered in DNP and found in dorsal root ganglia, decrease off-target side effects observed with the use of earlier non-biased Kv7 activators, and optimize the absorption, distribution, metabolism, excretion, and toxicity profiles of these activators. This screening paradigm is intended to establish a clinic-ready, well-tolerated, and widely effective product to treat neuropathic pain.

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.

Pain signals originate predominantly in a subset of peripheral sensory neurons that harbor a distinct subset of voltage-gated sodium (NaV) channels; however, current NaV channel blockers, such as local anesthetics, are non-selective and also block NaV channels vital for function of the heart, muscle, and central nervous system. Genetic studies have identified human NaV1.7, NaV1.8, and NaV1.9 channel subtypes as key players in pain signaling and as major contributors to action potential generation in peripheral neurons. ProTx-II is a highly potent and moderately selective peptide toxin that inhibits human NaV1.7 activation. This study will optimize ProTx-II selectivity, potency, and stability by exploiting the new structures of ProTx-II—human NaV1.7 channel complexes, advances in rational peptide optimization, and rigorous potency and efficacy screens to generate high-affinity, selective inhibitors of human NaV1.7, NaV1.8, and NaV1.9 channels that can define a new class of biologics to treat pain.

Complex regional pain syndrome is one of the most disabling and difficult-to-treat chronic pain conditions. This project seeks to develop a novel, biological treatment for the condition using injected human bone marrow cells. that can form and repair skeletal tissues and control nervous and immune system activity. The research will determine the dose and source of clinical-grade bone marrow cells needed, toward the goal of submitting an Investigational New Drug Application to the U.S. Food and Drug Administration that will enable further clinical study.