Inhibiting RIPK1 with Necrostatin-1 for Safe and Effective Pain Treatment
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Chronic pain affects millions of Americans and costs more than $635 billion annually. Identification of therapeutic targets for effective pain treatment with minimal potential for addiction is urgently warranted. This proposal is in response to RFA-NS-21-029 to develop a multidisciplinary team for the feasibility and validity of a novel therapeutic target of pain with minimal potential of addiction. Recent studies have reported that neuropathic pain involves microglial changes in central nervous system, linked to necroptosis (programmed necrotic cell death) and release of cellular components that facilitate neuroinflammation. Specifically, necroptosis is a type of necrotic cell death that can be mediated by the receptor-interacting serine/threonine-protein kinase 1 (RIPK1 or RIP1). In preliminary RNA Seq studies, our data showed that RIPK1 was upregulated after induction of pain, in key brain regions implicated in pain processing. Moreover, we found that RIPK1 protein expression was upregulated in two mouse neuropathic pain models and that RIPK1 upregulation was associated with increased microglial necroptosis. Necrostatin-1 (Nec-1) is a RIPK1 inhibitor which crosses the blood-brain barrier, with strong potential of modulating neuroinflammation. More importantly, targeting RIPK1 with Nec-1 attenuated pain- related nociceptive behaviors in rats. Recently, our team has synthesized, evaluated and identified a promising compound, [11C]CNY-06, which is a radioisotope labeled Nec-1. [11C]CNY-06 allows us to perform positron emission tomography (PET) -CT studies which provides unprecedented opportunities to image RIPK1 and necroptosis in the brain, to characterize and validate RIPK1 as a therapeutic target for pain. Specifically, we have established that [11C]CNY-06 has excellent brain uptake and high specific binding in mice. Using a mouse neuropathic pain model we have captured imaging features of RIPK1/necroptosis, and compared them with established markers of neuroinflammation. Based on these preliminary data, we hypothesize that targeting RIPK1 through Nec-1 is a safe and effective treatment for neuropathic pain, with minimal potential for addiction. We will carry out two Specific Aims to test this hypothesis. Aim 1: To thoroughly characterize RIPK1 expression and to test Nec-1 in three rodent neuropathic pain models. Aim 2: To interrogate if Nec-1 leads to addiction or if it enhances other medication’s addiction potential. Combining pain mechanistic studies, behavioral testing, and novel molecular imaging using PET-CT, this R61 proposal will generate pivotal data regarding RIPK1 in pain, by rigorously testing our central hypothesis that inhibiting RIPK1 through Nec-1 is a safe and effective treatment for pain. This proposal will not only provide robust data on the efficacy and side effects of Nec-1 for pain treatment, but also establish a multidisciplinary research team with extensive experience in translational pain research for the subsequent U19 Team Research phase.
