Funded Projects

Spinal cord injury (SCI) impairs sensory transmission and leads to chronic, debilitating neuropathic pain. While our understanding of the development of chronic pain has improved, the available therapeutics provide limited relief. We will examine the peripheral immune and inflammatory response. Secondary inflammation in response to SCI is a series of temporally ordered events: an acute, transient upregulation of chemokines, followed by the recruitment of monocytes/macrophages and generation of an inflammatory environment at the lesion site in the spinal cord, but also surrounding primary nociceptors in the dorsal root ganglia (DRG). These events precede neuropathic pain development. Previous work indicates that after SCI, macrophage presence in the DRG correlates with neuropathic pain. We propose to study: 1) whether the phenotype of macrophages that infiltrate the DRG is different than those that persist chronically after SCI and 2) how manipulation of macrophage phenotype affects nociceptor activity and pain development.

Cerebral palsy (CP), the leading cause of childhood disabilities in the United States, refers to a group of neurological disorders that appear in infancy or early childhood and permanently affect body movement and muscle coordination. The experience of pain is one of the most common, poorly understood, and inadequately treated conditions in CP, impairing health and quality of life for both patients and caregivers. To understand why pain and motor dysfunction occur together, a model that accurately replicates both is needed. This project will validate an established, rabbit model of CP motor dysfunction for use in studying and developing effective treatments for CP-associated pain.

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.

This project aims to validate Peptidase Inhibitor 16 (PI16) as a novel target for the treatment of chronic pain using mouse models and tissues of human patients with neuropathy. PI16 was identified as a novel regulator of chronic pain in preclinical bench studies. PI16 is a small molecule that has not been studied in the context of pain. Mice that are deficient for PI16 function are protected against mechanical allodynia (tactile pain from light touch) in spared nerve injury (SNI) and paclitaxel models of neuropathic pain. PI16 is only detectable in fibroblasts around peripheral nerves (perineurium), and in the meninges of dorsal root ganglia (DRG), spinal cord, and brain, but not in neurons, glia or leukocytes. PI16 levels in perineurial and DRG meningeal fibroblasts increase during neuropathic pain. Increased PI16 secretion by DRG meningeal and perineurial fibroblasts may promote chronic pain by increasing blood nerve barrier (BNB) permeability and leukocyte trafficking into nerve and DRG.

Chronic pain is a major health burden associated with immense economic and social costs. Predictive biomarkers that can identify individuals at risk of developing severe and persistent pain, which is associated with worse disability and greater reliance on opioids, would promote aggressive, early intervention that could halt the transition to chronic pain. The applicant’s team uncovered evidence of a unique cortical biomarker signature that predicts pain susceptibility (severity and duration). This biomarker signature could be capable of predicting the severity of pain experienced by an individual minutes to months in the future, as well as the duration of pain (time to recovery). Analytical validation of this biomarker will be conducted in healthy participants using a standardized model of the transition to sustained myofascial temporomandibular pain. Specifically the biomarker signature will be tested for its ability to predict an individual’s pain sensitivity, pain severity, and pain duration and will perform initial clinical validation.

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.

Researchers will develop a novel transcranial focused ultrasound (tFUS) device for pain treatment and establish its effectiveness for treating sickle cell disease (SCD) pain in humanized mice. The tFUS will target the specific cortical regions involved in SCD pain using a novel non-invasive electrophysiological source imaging technique. The project’s goals have several aims. Aim 1: Develop tFUS devices for pain treatment. The mouse-scale system will be designed to validate the therapeutic effect of stimulating the anticipated cortical targets. This will inform development of the simpler human-scale system, which will use models of the skull to select cost-effective transducers to reach the targets. Aim 2: Evaluate tFUS effectiveness and optimize stimulation parameters in an SCD mice model. Researchers will determine effective tFUS parameters to chronically reduce SCD pain in mice and validate this using behavioral measures. Aim 3: Use electrophysiological source imaging to target and trigger closed-loop tFUS in animal models. This aim also includes performing safety studies to prepare for human trials. The project will develop a transformative, noninvasive tFUS device to effectively and safely treat pain in SCD. 

Head and neck cancer is particularly susceptible to nociceptive and neuropathic pains because it is dense with sensitive anatomic structures and richly innervated. Transcranial magnetic resonance imaging–guided focused ultrasound (FUS) is a new stereotactic modality capable of delivering high-intensity energy through the intact human skull with submillimeter precision. This clinical trial will target the spinothalamic and spinoreticular pain circuits by unilateral FUS mesencephalotomy, an effective procedure for cancer pain but limited by the accuracy of its era. The primary aim is to assess the safety and preliminary effectiveness in six head and neck cancer patients with opioid-resistant pain. Researchers will investigate the potential mechanism of pain relief as the mesencephalotomy target involves the confluence of the ascending and descending pain systems. Aims 2 and 3 will investigate these systems with electrophysiology specific for the spinothalamic tract and carfentenil positron emission tomography imaging that measures the brain’s endogenous opioids.

Chronic pain severely reduces the quality of life and ability to work for millions of Americans. Because misuse of opioids for chronic pain treatment contributes to opioid addiction and opioid overdose, there is an urgent need to study novel non-opioid mechanisms, targets, and treatment strategies for chronic pain. Many ion channels control the flow of electrical signals in peripheral sensory neurons and are thus key targets for understanding and treating chronic pain. This project will conduct detailed studies to identify major ion channel-related molecular activities, targets, and treatment strategies for chronic pain. In particular, this research will explore the role of a specific ion channel (lysosomal mechanosensitive ion channel, orTmem63A) in neuropathic pain resulting from nerve injury.

While traditional epidural spinal cord stimulation (SCS) for intractable pain has been very efficacious for the patients responsive to it, the success rate has held at approximately 55%. Dorsal root ganglion (DRG) stimulation has shown promise in early trials to provide greater pain relief. Although the decrease in back pain at 3 months was significantly greater in the DRG arm vs. SCS, the adverse event rate related to the device or implant procedure was significantly higher in the DRG arm. Researchers will develop the “Injectrode” system to make the procedure simpler and safer by using an alternative to implantation: using an injectable pre-polymer liquid composite that cures quickly after injection adjacent to the DRG. They will compare an Injectrode-based system with traditional electrode stimulation at the DRG as an alternative to opioid administration. Researchers will perform benchtop characterization and refinement as a precursor to a clinical study, use modeling and animal testing to refine the efficiency of energy transfer from a transcutaneous electrical nerve stimulation unit to an Injectrode/Injectrode collector concept, and optimize the procedure for the complex anatomy of the human DRG.

This project will establish a rapid research pipeline for linking plant-derived compounds to nociception (pain) and to G Protein-Coupled Receptors (GPCRs) and ion channels in the druggable human genome. As more than 80% of these membrane proteins are conserved in the C. elegans nematodes, the study will screen for compounds and genes affecting nociception as well as to identify novel ligand-receptor pairs using this model organism. The study will test which understudied GPCRs and ion channels are involved in nociception as well as attraction or repulsion behaviors. This research has the potential to reveal novel ligand-receptor pairs that could serve as new entry points for improved or alternative pain treatments.

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.

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.