α9α10 Nicotinic Acetylcholine Receptors in neuropathic pain

ABSTRACT Chronic pain represents a serious and growing health concern that affects at least one in five American adults. Despite the high risk of tolerance, physical dependence, and addiction, opioid analgesics continue to be a major component of pain management. Furthermore, opioids are only weakly effective for the approximately 30-40% of chronic pain patients suffering from neuropathic pain arising from lesions or disease of the somatosensory nervous system. Non-opioid first-line treatments for neuropathic pain are also only marginally effective and suffer from serious adverse effects. Clearly, there is an urgent need for new analgesic drug targets and for new classes of drugs that can effectively and safely treat neuropathic pain. The long-term goal of this research project is to fill this gap by establishing the role of the α9α10 nicotinic acetylcholine receptor (nAChR) in neuropathic pain and developing effective antagonists against it. Evidence from peptidic α9α10 antagonists and α9-knockout mice indicates that inhibition of α9α10 function successfully attenuates allodynia and hyperalgesia in several animal models of neuropathic pain. However, the poor drug-like properties of existing α9α10 antagonists hinders them from being easily translated into the clinic. Previous efforts to discover novel α9α10 ligands have been thwarted by technical challenges in adapting α9α10 nAChRs for high-throughput screening and compound optimization assays. Furthermore, the difficulty in expressing α9α10 in mammalian cells has left unanswered questions regarding the structure and function of this promising drug target. Building on a recent discovery that TMIE is an essential auxiliary protein for α9α10 receptor expression, we have engineered a novel HEK293 cell line that stably expresses functional α9α10 receptors. The objective of this application is to leverage this innovative cell line to develop novel α9α10 antagonists and interrogate the location, function, and structure of the receptor. Moreover, we will investigate the in vivo efficacy of pharmacological inhibition of α9α10 activity in multiple neuropathic pain models in mice, studying both spontaneous pain and evoked hypersensitivity. The results from these studies will provide strong evidence that α9α10 nAChRs play a causal role in driving neuropathic pain and represent a bona fide target for analgesia, and will deliver promising lead compounds targeting this mechanism.