?As opposed to nociceptive pain which serves as an alert to injury, neuropathic pain (NP), serves no protective or warning purposes for the human body; but rather results from dysfunction in the somatosensory system that involves multiple mechanisms that can be brought about by lesions and damage to the peripheral nerves, spinal cord, brainstem, or the brain itself. Prevalence for chronic pain ranges from 14.6% to 64% in the US. The economic burden to the US (direct medical expenditure and lost wages/productivity) is staggering; with yearly financial costs between $560 billion to $635 billion. NP also exacts a terrible toll on quality of life, severely impairing a patient's ability to function productively i society and at home. Marginal efficacy coupled with serious side effects and low patient compliance render current therapies woefully inadequate. Therefore, there is a significant need to develop therapeutic agents with innovative profiles for more effective treatment of chronic NP. Rational design of drugs that can modulate multiple molecular targets would be an attractive strategy for the treatment of multi-faceted disease states such as chronic NP. Recently, rationally designed multiple ligands have been coined "master keys" due to their interaction with various molecular targets or receptors to produce an overall desirable composite modulatory effect on a disease pathway. Through careful scaffold design using merging or fusing strategies, these compounds can display two or more pharmacophores within the same scaffold core creating a molecule which is capable of interacting at several nodes within the biological network pertinent to the targeted disease pathway. In this context, activating the AMPK signaling pathway has been implicated in several multi-factorial human disease states including NP and inflammation; hence AMPK activators could represent a novel treatment modality for chronic neuropathic and inflammatory pain. AMPK activation serves as an upstream negative regulator of mTORC1 and MAPK (consisting of p38 MAPK, ERK, and JNK) signaling pathways, two kinase families that play important roles in nociceptor excitability through modulation of downstream ion channels crucial for neuronal hyperexcitability. A designed dual active compound which modulates a second validated pain target lying within the same signaling pathway could provide synergistic dampening of neuronal excitability and attenuate the propagation of NP. Thus, dual-acting therapeutics that attenuate pain signaling via multiple pathways would provide a superior modality to treat NP. As such, the goal of this application is to develop a first in class compound that would activate AMPK in neuronal cells and intersect an additional node along the pain signaling pathway in glial cells to provide innovative multi-targeted pharmacological agents to treat chronic NP. For this program, we have partnered with Professors Theodore Price and Gregory Dussor at the University of Texas, Dallas - two renowned experts in AMPK signaling pathway and its role in pain plasticity following nerve injury. The Price/Dussor labs will provide state-of-the-art biochemical, electrophysiological, and genetic tools, including transcriptome analysis to study expression levels of relevant neuronal AMPK subtypes in rat, mouse, and human DRG and trigeminal nuclei. Our newly designed dual-ligand compounds will be evaluated in relevant AMPK cellular assays using western blot and imaging techniques. Thus, the First Specific Aim of this study is to design, synthesize, and characterize prototype, structurally distinct ligands that possess dual-activity at two distinct molecular targets using the knowledge-based pharmacophore linking and merging drug discovery strategy approach. Upon identification of appropriate starting hit compounds with dual activity, we will focus on probing and establishing SAR while addressing the refinement of pharmaceutical properties with iterative small library synthesis (~3-6 compounds each library). The Second Specific Aim is to expand structure activity relationship (SAR) and structure property relationship (SPR) around selected prototype agents (3-4 structural series; with 3-6 compounds per series) emerging from Specific Aim 1 and focus on dual-actives that possess suitable pharmaceutical and drug-like properties with good potential for both peripheral and central nervous system activity. The Third Specific Aim is to focus down further from the emerging lead series in Specific Aim 2 and identify two novel structurally distinc scaffold series possessing potent dual activity which will be the entry-point into an SBIR phase 2 extension for final in vivo optimization of our lead compounds to identify innovative and disease-modifying treatments for chronic NP.
Public Health Relevance Statement: Public Health Relevance: The proposed research is relevant and extremely significant for the benefit of public health. Chronic neuropathic pain is one of the most frequent reasons that patients seek medical care and remains one of the most difficult ailments to treat. Selective, single-target agents are mostly ineffective when used to treat neuropathic pain. We aim to identify and develop novel multi-targeted compounds as an innovative new treatment option for complicated disease states and potentially provide a new class of disease modifying drugs for neuropathic pain.
NIH Spending Category: Neurodegenerative; Neurosciences; Pain Conditions - Chronic; Pain Research; Peripheral Neuropathy
Project Terms: Acids; Address; Adult; Adverse effects; Analgesics; Applications Grants; Attenuated; Biochemical; Biological; Biological Assay; Brain; Brain Stem; Businesses; Cannabinoids; Cardiovascular system; Caring; Cells; Cellular Assay; Centers for Disease Control and Prevention (U.S.); Chronic; chronic neuropathic pain; chronic pain; Coin; Compliance behavior; Coupled; design; Diabetic Neuropathies; Disease; Disease Pathway; Dose; Drug Design; drug discovery; Economic Burden; effective therapy; Erythromelalgia; Esthesia; Expenditure; Family; Fibromyalgia; Financial cost; Functional disorder; Gene Expression Profile; Generations; Genetic; Goals; Grant; Healed; healing; HIV; Home environment; Human; Human body; human disease; Imaging Techniques; immunocytochemistry; in vivo; Inflammation; inflammatory neuropathic pain; inflammatory pain; inhibitor/antagonist; injured; Injury; innovation; Ion Channel; knowledge base; Lead; lead series; Lesion; Libraries; Ligands; Link; Literature; Malignant Neoplasms; MAP Kinase Gene; MAPK14 gene; MAPK8 gene; Medical; Microglia; Modality; Modeling; Molecular Target; Mus; Nerve; nerve injury; Neuraxis; Neuroglia; neuronal excitability; Neurons; Nociception; Nociceptors; Non-Steroidal Anti-Inflammatory Agents; novel; Opioid; Pain; Pain Disorder; painful neuropathy; Parents; Pathway interactions; Patients; Peripheral; Peripheral Nerves; Pharmaceutical Preparations; Pharmacologic Substance; pharmacophore; Phase; Phosphorylation; Phosphotransferases; Play; Postherpetic neuralgia; Prevalence; Price; Productivity; professor; programs; Property; prototype; public health medicine (field); public health relevance; Pyridoxal Phosphate; Quality of life; Radiculopathy; Rattus; receptor; Reporting; Research; response; Rodent; Role; scaffold; Series; Signal Pathway; Signal Transduction; Small Business Innovation Research Grant; small molecule; Societies; somatosensory; Spinal Cord; spontaneous pain; Structure; Structure-Activity Relationship; System; Texas; Therapeutic; Therapeutic Agents; tool; treatment strategy; Trigeminal Nuclei; United States National Institutes of Health; Universities; Wages; Western Blotting
