Funded Projects

This project will build overdose models for fentanyl, methadone, codeine, and morphine in a multi-organ system and evaluate the acute and repeat dose, or chronic effects, of overdose treatments as well as off-target toxicity. Researchers developed a system using human cells in a pumpless multi-organ platform that allows continuous recirculation of a blood surrogate for up to 28 days. They will develop two overdose models for male and female phenotypes based on pre-B?tzinger Complex neurons and will integrate functional immune components that enable organ-specific or systemic monocyte actuation. Models for cardiomyopathy and infection will be utilized. Researchers will establish a pharmacokinetic/pharmacodynamic model of overdose and treatment to enable prediction for a range of variables. We will use a serum-free medium with microelectrode arrays and cantilever systems integrated on chip that allow noninvasive electronic and mechanical readouts of organ function.

Many chronic pain conditions are dependent upon activity of the sympathetic nervous system. Sympathetic blockade is used clinically in chronic pain conditions, but the clinical and preclinical evidence for this practice is incomplete. We propose that certain pathological pain conditions require intact sympathetic innervation of the sensory nervous system at the level of the dorsal root ganglion (DRG) and that release of sympathetic transmitters enhances local inflammation and leads to pain. Our preliminary data show large, rapid, and long-lasting reduction of pain behaviors and inflammatory responses following a"microsympathectomy" (mSYMPX) in both neuropathic and inflammatory pain models. Our aims are to: 1) characterize the effects of mSYMPX on pain and on local inflammation in the DRG; 2) explore the molecular mechanisms for sympathetic regulation of inflammatory responses in the DRG; and 3) assess the functional role of sympathetic transmitters in the sympathetically mediated inflammatory responses in the DRG.

The clinical utility of opioids for pain treatment is limited by its risk for developing opioid usage disorders (OUD). These untoward effects impose a severe burden on society and present difficult therapeutic challenges for clinicians. We propose to extend our cerebral organoid MPS to facilitate the investigation of neuronal response to opioids and identify cellular and molecular signatures in patients vulnerable to OUD. We have assembled a team with complementary expertise in clinical characterization of OUD, cerebral organoid MPS modeling, single cell RNA-seq technology, and functional characterization of neurons in a mesolimbic reward system to test the hypothesis that midbrain MPS is a clinically relevant pre-clinical model for study of opioid usage disorder.

Validation of novel pain targets is a critical step toward the development of new non-addictive therapeutic agents for chronic pain management. Recent findings suggest that nerve injury-induced concurrent upregulation of the calcium channel alpha-2delta-1 subunit (CaValpha-2-delta-1) and thrombospondin-4 (TSP4) proteins in sensory and spinal cord neurons contributes to neuropathic pain development. Specifically, induction of aberrant excitatory synapse formation and sensitization of neurotransmission in spinal cord underlies this process; accordingly, a target site has been identified in the TSP4 that plays a critical role in mediating these pathological changes upon interaction with the CaValpha-2-delta-1 protein. This project will validate this novel target site in TSP4 for development of non-addictive pain medications, utilizing multidisciplinary approaches to investigate if blocking and genetic deletion of the target site can block or prevent the development of chronic pain state, aberrant excitatory synapse formation, and spinal cord neuron sensitization after injury in multiple rodent neuropathic pain models.

The research team will develop an implantable neural stimulation system to provide natural and intuitive sensation for prosthesis users. The nerve cuff technology meets the requirements for a sensory feedback system capable of providing consistent and controlled electrical stimulation. Coupled with a multichannel implantable stimulator, this electrode array will offer substantial improvement over existing options to treat phantom limb pain (PLP). In Phase I, researchers will finalize array architectures for evaluation in cadaver studies, complete integration of electrodes with our stimulator, conduct benchtop verification of electrical and mechanical performance, send implants for third-party evaluation of system biocompatibility, and complete a Good Laboratory Practice animal study to validate safety and efficacy. In Phase II, researchers will conduct a 5-subject clinical study to test the implantable stimulation system. Each unilateral prosthesis user will be implanted for one year as researchers evaluate the safety and efficacy of this implantable device to treat PLP.

The goal of this project is to generate data and reagents that help uncover critical functions of the poorly characterized members of ion channels. It focuses on co-perturbation of ion channel genes and their interacting genetic components as opposed to singly altering ion channel genes in mouse models. This approach will validate our proteomics approaches in the most definitive manner: in vivo. We see in vivo exploration as an essential step to evaluate ion channel function. Our major aims include mapping ion channel interactions and complexes using a high-throughput proteomics platform at UCSF. These data will be interrogated using integrative approaches established by the Monarch Initiative, where biochemical interactions will be validated and prioritized for further study. Another major aim is function-centric: We use mouse models for elucidation of human disease mechanisms, where we embrace a genetic interaction scheme to uncover ion channel redundancy and polygenic effects.

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.

This project will develop a human cell-based model of the afferent pain pathway in the dorsal horn of the spinal cord. The research team’s approach utilizes novel human pluripotent stem cell (hPSC)-derived phenotypes in a model that combines 3D organoid culture with microfabricated systems on an integrated, three-dimensional (3D) microelectrode array. Researchers will establish the feasibility of a physiologically relevant, human 3D model of the afferent pain pathway that will be useful for evaluation of candidate analgesic drugs. They will then improve the physiological relevance of the system by promoting neural network maturation before demonstrating the system’s utility in modeling adverse effects of opioids and screening compounds to validate the model. Completion of the study objective will establish novel protocols for deriving dorsal horn neurons from hPSCs and create the first human microphysiological model of the spinal cord dorsal horn afferent sensory pathway.

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.

Migraine is the most common neurological disorder. Currently available treatments fail to effectively manage migraine in most patients. Development of new therapeutics has been slow due in large part to a poor understanding of the underlying pathology of migraine. Endogenous proteases, released in the meninges by resident mast cells, have been proposed as a potential driver of migraine pain via an action on protease activated receptor type 2 (PAR2). The central hypothesis is that PAR2 expression in nociceptors that project to the meninges plays a key role in the pathogenesis of migraine pain. The aims are to: 1) use the established PAR2 development pipeline to design new PAR2 antagonists with improved drug-like properties; 2) use pharmacological tools in a novel mouse migraine model to further understand the potential role of PAR2 in migraine; and 3) use mouse genetics to study the cell type–specific role of PAR2 in migraine pain.

An extensive literature provides compelling evidence that selective antagonists or negative allosteric modulators (NAMs) of the metabotropic glutamate (mGlu) receptor, mGlu5, have exciting potential as a novel approach for treatment of multiple pain conditions that could provide sustained antinociceptive activity without the serious adverse effects and abuse liability associated with opioids. Researchers have developed a novel series of highly selective mGlu5 NAMs that are structurally unrelated to previous compounds, have properties for further development, and avoid the formation of toxic metabolites that were associated with previous mGlu5 NAMs. Based on existing preclinical models, as well as clinical trial data showing efficacy of an mGlu5 NAM in migraine patients, researchers anticipate that their compounds will have broad-spectrum analgesic activity in patients with a variety of chronic pain conditions.

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.

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.