Assay development for characterization of Adrb3 antagonists as pain therapeutics

项目总结

PROJECT SUMMARY Functional pain syndromes (FPS) affect over 100 million people, yet remain ineffectively treated by conventional pharmacotherapies, such as opioids, that have poor efficacy and adverse central side effects. Our long-term goal is to develop safer, more effective analgesics for patients with FPS, specifically peripherally-restricted antagonists of the beta-3 adrenergic receptor (Adrb3). The Adrb3 receptor is a G protein-coupled receptor that is activated by catecholamines. In clinical studies, we determined that patients with chronic FPS such as fibromyalgia, low back pain, and irritable bowel syndrome have increased levels of catecholamines alongside reduced levels of catechol-O-methyltransferase (COMT; an enzyme that metabolizes catecholamines). Consistent with clinical syndromes, we have shown that pharmacologic inhibition of COMT in rodents produces pain at multiple body sites via activation of peripheral Adrb3. The pain is initiated by peripheral adipocyte Adrb3- mediated increases in pro-inflammatory cytokines in local tissues and maintained by subsequent increases in pro-inflammatory cytokines in spinal tissues and activation of mitogen activated protein kinases (MAPKs) in the cell bodies and central terminals of pain-sensing nociceptors. Thus, Adrb3 is a novel and attractive target for the treatment of chronic functional pain and pain-relevant inflammation. However, existing tool compounds either lack selectivity for Adrb3 or have poor metabolic properties. To successfully build a robust drug discovery platform for Abrb3 antagonists, in this proposal, we will develop and validate a battery of in vitro, cell-based assays to fully characterize the pharmacology of novel Adrb3 ligands. The development of high throughput, plate-based assays is critical for accurate evaluation of novel compound affinity, potency, efficacy, selectivity, and target validation, as part of a long-term medicinal chemistry campaign that seeks to produce new analgesics with improved specificity and side-effect profiles for the treatment of functional pain syndromes.