Funded Projects

Debilitating pain is the most common complication of sickle cell disease (SCD), but there is significant variability in pain expression in these patients. Currently, there is no plasma biomarker that can prognosticate which patients are likely to experience pain. The overall goal of this proposed research is to develop a biomarker that prognosticates the clinical expression of pain in SCD. Project aims are to (1) derive the inflammatory index for pain by identifying inflammatory and immune regulatory gene probe sets that will distinguish healthy controls, patients with SCD in baseline health, and patients with SCD in acute pain and (2) determine whether co-expressed genes from patients with SCD correlate with clinical pain data. Subsequent aims are to (1) determine the clinically meaningful changes of the index in patients with SCD and (2) investigate the preliminary clinical validity of the index as a prognostic biomarker for pain in patients with SCD.

Effective treatments are elusive for the majority of patients with neuropathic pain. Reactive oxygen and nitrogen species (ROS/RNS) are involved in neuropathic pain, because they drive mitochondrial dysfunction, cytokine production, and neuronal hyperexcitability; therefore, stimulation of endogenous antioxidants is predicted to simultaneously resolve multiple neuropathic pain mechanisms. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor that is a potential therapeutic target because it regulates the expression of a large number of endogenous antioxidant-related genes and can be activated with a single drug. This project will test the hypothesis that Nrf2 activation increases multiple endogenous antioxidants, therefore reversing neuropathic pain behaviors and counteracting neuropathic pain mechanisms that are driven by ROS/RNS and could provide an effective pain therapy, with minimal abuse/addictive potential.

Efforts to identify non-opioid analgesics for treatment of chronic pain have identified a protein, carbonic anhydrase-8 (CA8), in pain-sensing nerve cells in the spinal cord (dorsal root ganglion cells) whose expression regulates analgesic responses. Gene therapy delivering CA8 to dorsal root ganglion cells through clinically relevant routes of administration functions as a “local anesthetic” that induces long-lasting pain relief in animal models of chronic pain. This project will further develop CA8 gene therapy with the goal of treating chronic knee osteoarthritis pain. It will assess several gene therapy constructs to determine the doses needed, safety, efficacy, and specificity to nerve cells for each construct. It will then select the safest and most effective construct that can be administered via the least invasive route for further development. The project will include all steps necessary to identify one candidate gene therapy construct that will be suitable to begin clinical trials in patients with chronic knee osteoarthritis 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.

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.

Multi-protein complexes have emerged as a mechanism for spatiotemporal specificity and efficiency in the function and regulation of myriad cellular signals. In particular, 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 the AKAP79/150 protein that is a focus of this research. This research will focus on three different channels critical to nervous function. One is the"M-type" (KCNQ, Kv7) K+ channel that plays fundamental roles in the regulation of excitability in nerve and muscle. It is thought to associate with Gq/11- coupled receptors, protein kinases, calcineurin (CaN), calmodulin (CaM) and phosphoinositides via AKAP79/150. Another channel of focus is TRPV1, a nociceptive channel in sensory neurons that is also thought to be regulated by signaling proteins recruited by AKAP79/150. The third are L-type Ca2+ (CaV1.2) channels that are critical to synaptic plasticity, gene regulation and neuronal firing. This research will probe complexes containing AKAP79/150 and these three channels using"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, breaking the diffraction barrier of physics. The researchers hypothesize that AKAP79/150 brings several of these channels together to enable functional coupling, which the researchers will examine by patch-clamp electrophysiology of the neurons. Förster resonance energy transfer (FRET) will also be performed under total internal reflection fluorescence (TIRF) or confocal microscopy, further testing for complexes containing KCNQ, TRPV1 and CaV1.2 channels. Since all three of these channels bind to AKAP79/150, the researchers hypothesize that they co-assemble into complexes in neurons, together with certain G protein-coupled receptors. Furthermore, the researchers hypothesize these complexes to not be static, but rather to be dynamically regulated by other cellular signals, which the researchers will examine using rapid activation of kinases or phosphatases. Several types of mouse colonies of genetically altered AKAP150 knock-out or knock-in mice will be utilized.

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.

Neuropathic corneal pain (NCP) causes patients to have severe discomfort and a compromised quality of life (QoL). The lack of signs observed by standard examination has resulted in misdiagnosis as dry eye disease (DED). An optical biopsy using laser in vivo confocal microscopy (IVCM) revealed that microneuromas (bulbs at the ends of severed nerves caused by buildup of molecular constituents) are present in NCP but not DED and may serve as a biomarker for NCP. The aims are to (1) use a database of more than 2,000 DED/NCP subjects and more than 500,000 IVCM images to confirm that the presence of microneuromas is an appropriate biomarker for NCP, (2) provide biological validation of microneuromas, (3) develop a validated artificial intelligence (AI) program for automated identification of microneuromas, and (4) establish the clinical utility of microneuromas observed by IVCM as a biomarker for NCP in a prospective, multicenter study.

The primary goal of the PRECISION Human Pain network and its participating centers is to generate comprehensive datasets of molecular signatures and cellular function phenotypes or signatures of various cell types that underlie transmission and processing of pain signals in humans. To maximize the impact of the data generated through this effort, it is vital to standardize and integrate all data generated by the various centers and make these data available in a meaningful way to the larger scientific community. As the Data Coordination and Integration Center, this project will support the network to curate, harmonize, and effectively integrate center-generated datasets as well as provide operational support for the network and conduct educational and outreach efforts.

The research team will develop stimulation control algorithms to treat chronic pain using a novel device that allows longitudinal intracranial signal recording in an ambulatory setting. Subjects with refractory chronic pain syndromes will undergo bilateral surgical implant of temporary electrodes in the thalamus, anterior cingulate, prefrontal cortex, insula, and amygdala to identify candidate biomarkers of pain and optimal stimulation parameters. Six patients will proceed to chronic implantation of “optimal” brain regions for long-term recording and stimulation. The team will first validate biomarkers of low- and high-pain states to define neural signals for pain prediction in individuals. They will then use these pain biomarkers to develop personalized closed-loop algorithms for deep-brain stimulation (DBS) and test the feasibility of closed-loop DBS for chronic pain in weekly blocks. Researchers will assess the efficacy of closed-loop DBS algorithms against traditional open-loop DBS or sham in a double-blinded cross-over trial and measure mechanisms of DBS tolerance.

Neuropathic pain is a debilitating and complex medical condition for which safe and non-addictive treatment options are urgently needed. Preliminary studies have found that lysophosphatidic acid receptor 5 (LPA5) is present in areas of the body that signal pain, including at high levels in rodent models of neuropathic pain. This project will use genetic and pharmacological approaches to determine whether blocking LPA5 signaling reduces neuropathic pain toward future testing in humans.  

Persistent pain states arising from inflammatory conditions, such as in arthritis, diabetes, HIV, and chemotherapy, exhibit a common feature in the release of damage-associated molecular pattern molecules, which can activate toll-like receptor-4 (TLR4). Previous studies suggest that TLR4 is critical in mediating the transition from acute to persistent pain. TLR4 as well as other inflammatory receptors localize to lipid raft microdomains on the plasma membrane. We have found that the secreted apoA-I binding protein (AIBP) accelerates cholesterol removal, disrupts lipid rafts, prevents TLR4 dimerization, and inhibits microglia inflammatory responses. We propose that AIBP targets cholesterol removal to lipid rafts harboring activated TLR4. The aims of this proposal are to: 1) determine whether AIBP targets lipid rafts harboring activated TLR4; 2) test whether AIBP reduces glial activation and neuroinflammation in mouse models of neuropathic pain; and 3) identify the origin and function of endogenous AIBP in the spinal cord.

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.