Peripheral RIPK2 degradation improves neurological outcomes after experimental ischemic stroke

Receptor-interacting serine/threonine kinase 2 (RIPK2) is an important modulator of the inflammatory response in many disease states, including ischemic stroke. Here, we utilized, for the first time, a proteolysis targeting chimera (PROTAC) to specifically degrade RIPK2 in vivo in a rodent model of ischemic stroke. First, we established a dose-response curve for RIPK2 degradation following treatment with the RIPK2 PROTAC in naïve mice. Then, we assessed the time course of RIPK2 degradation and resolution to determine our optimal dosing paradigm for the acute ischemic stroke study. Interestingly, we saw significant degradation in peripheral organs but not in the brain. Using the transient middle cerebral artery occlusion (tMCAO) model of ischemic stroke, we assessed the efficacy of RIPK2 PROTAC degradation as a potential therapeutic approach for ischemic stroke. While we did not see reductions in infarct volume, we did find significant improvements in behavioral outcomes using the open field test, weight grip test, vertical grid test, and neurological deficit scoring. This study adds to the literature supporting RIPK2 as an important mediator of the post-stroke inflammatory response and further demonstrates the importance of the peripheral immune response, specifically involving the spleen, in secondary injury after ischemic stroke.