Repurposing the K_Ca3.1 Blocker Senicapoc for Ischemic Stroke

Area of Science:

• Neuroscience
• Pharmacology
• Immunology

Background:

• Senicapoc is a KCa3.1 channel inhibitor previously studied for sickle cell anemia.
• KCa3.1 inhibition and genetic deletion show potential in reducing neuroinflammation and improving recovery in rodent models.
• Neuroinflammation plays a critical role in ischemic stroke pathogenesis.

Purpose of the Study:

• To evaluate the repurposing potential of senicapoc for treating ischemic stroke.
• To investigate senicapoc's effects on microglial activation and inflammatory responses in vitro.
• To assess senicapoc's efficacy in reducing infarct volume and improving neurological deficits in a mouse model of ischemic stroke.

Main Methods:

• In vitro studies using cultured microglia to assess KCa3.1 inhibition, calcium signaling, inflammatory cytokine expression, and inflammasome activation.
• In vivo studies using a transient middle cerebral artery occlusion (tMCAO) mouse model.
• Administration of senicapoc at different time points and doses post-reperfusion.
• Assessment of infarct volume using T2-weighted MRI and neurological deficit scoring.
• Analysis of brain drug concentrations, immune cell infiltration, activation markers, and neuronal death.
• In vitro assessment of senicapoc's effect on tissue plasminogen activator (tPA) activity.

Main Results:

• Senicapoc effectively inhibited KCa3.1 currents (IC50 = 7 nM) and suppressed ATP-induced Ca2+ signaling, pro-inflammatory cytokine/enzyme expression (iNOS, COX-2), and NLRP3 inflammasome activation in microglia.
• Twice-daily senicapoc administration (10 and 40 mg/kg) post-tMCAO dose-dependently reduced infarct area and improved neurological deficits.
• Sufficient KCa3.1 target engagement in the brain was confirmed by LC-MS analysis.
• Senicapoc treatment significantly decreased microglia/macrophage and T cell infiltration and activation, and attenuated neuronal death.
• Early senicapoc treatment (3h post-reperfusion) reduced secondary infarct growth and suppressed brain inflammation markers, including T cell cytokines.
• Senicapoc did not impair tPA proteolytic activity in vitro.

Conclusions:

• Senicapoc demonstrates significant immunomodulatory and neuroprotective effects in preclinical models of ischemic stroke.
• Repurposing senicapoc as an adjunctive therapy for ischemic stroke is a viable strategy.
• Senicapoc could be combined with reperfusion therapies like tPA to enhance treatment outcomes by providing immunocytoprotection.