Macrophage and cardiomyocyte roles in cardioprotection: Exploiting the NLRP3 Inflammasome inhibitor INF150

Cardiovascular diseases remain the leading cause of disability and death in the Western world. Effective cardioprotection involves limiting ischemia/reperfusion injury (IRI), including cell death (pyroptosis) driven by the NLRP3 inflammasome. While various cardiac resident cellular populations contribute to cardioprotection, it remains unclear whether targeting resident macrophages is inherently cardioprotective. Given that INF150, an NLRP3 inhibitor, exhibits varying abilities to penetrate cardiomyocytes and macrophages, we sought to address this question.

We studied the cardioprotective potential of INF150, the potent metabolite of the NLRP3 inhibitor INF195, in isolated hearts or cells. In isolated hearts, we measured infarct size, caspase-1 cleavage, and interleukins (IL) release, while in macrophages, naïve H9c2 and differentiated H9c2 cells, we analyzed cell viability, and pyroptosis markers, including IL-1β release and Gasdermin D cleavage, following hypoxia/reoxygenation (H/R).

While INF150 effectively shielded macrophages from LPS/ATP challenges, it failed to penetrate H9c2 and differentiated H9c2, even at high concentrations (no changes in pyroptosis markers induced by H/R). In the isolated mice heart model, INF150 did not demonstrate cardioprotective effects: infarct size, IL-1β, cleaved caspase-1 levels did not change significantly across tested concentrations of INF150. These findings suggest that while INF150 shows promise in macrophage/phagocytic models, its inability to penetrate cardiomyocytes limits its effectiveness in the whole cardiac tissue. Our results underscore the importance of cardiomyocyte uptake for effective cardioprotection, highlighting the need for NLRP3 inhibitors capable of targeting these cells directly. Future research should focus on enhancing the delivery and cardiomyocyte uptake of NLRP3 inhibitors to achieve cardioprotection. Unlike its precursor, INF195, which penetrates H9c2 cells, INF150 does not appear to offer cardioprotection in the whole organ.