Funded Projects

There is an urgent need to find new ways to treat chronic pain through better targeting of underlying biological processes. Research shows that flexible synapses within the amygdala brain region play a role in the progression of pain from acute to chronic, but the details are not fully understood. The receptor glutamate delta 1 helps to form and maintain synapses in the amygdala in inflammatory and neuropathic pain. This project will study how the shape and characteristics of glutamate delta 1 affect pain conditions that involve the amygdala, toward informing future development of pain medications. 

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.

It is unclear what changes in the brain mediate the development of chronic pain from acute pain and how chronic pain may change responses to opioid reward for the altered liability of opioid abuse under chronic pain. Preliminary studies have found that Dnmt3a, a DNA methyltransferase that catalyzes DNA methylation for gene repression, is significantly downregulated in the brain in a time-dependent manner during the development of chronic pain and after repeated opioid treatment. This project will investigate whether Dnmt3a acts as a key protein in the brain for the development of chronic pain, and whether Dnmt3a could be a novel epigenetic target for the development of new drugs and therapeutic options for the treatment of chronic pain while decreasing abuse liability of opioids.

There is increasing evidence that satellite glial cells (SGCs) surrounding neurons in the dorsal root ganglia modulate sensory processing and are important for chronic pain. Tissue inhibitor of metalloproteinase 3 (TIMP3) signaling occurs in SGCs and has unique plethoric functions in inhibiting matrix metalloproteinases, the tumor necrosis factor-?-converting enzyme, and the vascular endothelial growth factor receptor 2, all of which have been implicated in inflammation and pain. This study will test the hypothesis that expression of TIMP3 in SGCs is critical for the neuroimmune homeostasis in sensory ganglia, as well as for the development of pain, and therefore could be a novel therapeutic target for acute and chronic pain. Given the expression of TIMP3 in human SGCs and the strong validation of multiple small molecules targeting TIMP3 signaling, including FDA-approved drugs, in various animal models of pain and in cultured human SGCs, the successful completion of this research project has a high likelihood of rapid translation into therapeutic testing in inflammatory pain conditions that are a risk for opioid abuse.

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.

Dorsal root ganglion (DRG) neuronal hyperexcitability is central to the pathology of neuropathic pain and is a target for local anesthetics, even though the efficacy of local anesthetic patches has been mixed. The coordinated movement of ion channels, especially voltage-dependent sodium channels, from intracellular pools to the sites of nerve injury has been suggested to be an underlying cause of electrogenesis and ectopic firing in neuropathic pain conditions. Recent studies identified Magi1 as a scaffold protein responsible for sodium channel targeting and membrane stabilization in DRG neurons. This project will determine whether reducing the expression Magi1 could disrupt intracellular trafficking of sodium channels in DRG neurons under neuropathic injury conditions, and could therefore serve as a potential therapeutic target for neuropathic pain.

Migraine is a painful and debilitating neurological condition, the development and maintenance of which involves the neuropeptide calcitonin gene-related peptide (CGRP). An exciting development in the treatment of migraine is the recent FDA approval of a new class of CGRP-targeted therapies designed to prevent migraine. However, these drugs meet a clinically relevant endpoint for only about half of the patients. This project will test the hypothesis that the high-affinity CGRP receptor AMY1 is a novel and unexplored target that mediates specific migraine-related behaviors in the brain and/or periphery to cause migraine. Validation of CGRP and AMY1 receptor involvement in migraines will create a new direction for the development of novel drugs and provide alternatives to opioids for management of migraine and potentially for other chronic pain conditions.

This project will identify molecular characteristics of human sensory neurons and non-neuronal cells from the human dorsal root ganglia. This structure located outside the spinal cord is integrally involved in communicating pain signals to and from the brain. The research will use molecular approaches to characterize tissues obtained from organ donors and in patients who experience chronic pain. The findings will also help generate a connectivity map, or “connectome,” of nerve cell connections between the dorsal root ganglia of the spinal cord and the brain.

Migraine is one of the most common primary headache disorders and affects one in four U.S. households; however, there are few effective treatments. Migraine is a complex neurological disorder mediated in part by alterations in the way the brain processes sensations like touch and pain (somatosensation) in the head. These sensations are transmitted by the trigeminal nerve and a cell cluster called the trigeminal ganglion. To better understand the function of the human trigeminal system and its role in migraine, this project will conduct multiple types of molecular analyses of human trigeminal ganglia from people with and without migraine. The project will also perform sensory evaluations and measure the signals sent from the trigeminal ganglion to the brain in individuals with and without migraine.

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.

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.

Multi-protein complexes have emerged as a mechanism for spatiotemporal specificity and efficiency in the function and regulation of cellular signals. Many ion channels are clustered either with the receptors that modulate them or with other ion channels whose activities are linked. Often, the clustering is mediated by scaffolding proteins, such as AKAP79/150. We will probe complexes containing AKAP79/150 and three different channels critical to nervous function: KCNQ/Kv7, TRPV1, and CaV1.2. We will use"super-resolution" STORM imaging of primary sensory neurons and heterologously expressed tissue-culture cells, in which individual complexes can be visualized at 10–20 nm resolution with visible light. We hypothesize that AKAP79/150 brings several of these channels together to enable functional coupling, which we will examine by patch-clamp electrophysiology of the neurons. Since all three of these channels bind to AKAP79/150, we hypothesize that they co-assemble into complexes in neurons and that they are dynamically regulated by other cellular signals.

Complex regional pain syndrome is a difficult-to-treat chronic condition that causes excess and prolonged pain and inflammation after injury to an arm or leg and includes damage to skin of affected limbs. Although it is known that aberrant immune system function plays a role in this condition, the details remain unclear about how this occurs – in particular, through the adaptive immune system that relies on specialized immune cells and antibodies to protect the body from harm.  This project will study the role of certain immune cells (T cells) that circulate throughout the body or reside in bone using both rat or human bone samples from patients with complex regional pain syndrome.