NLRP3 inflammasome inhibitor(Exscientia/University of Oxford)

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.

The NLR family pyrin domain-containing 3 (NLRP3) inflammasome is responsible for various pathogenic and non-pathogenic damage signals and plays a critical role in host defense against pathogens and physiological damage. However, inflammasome activation and its subsequent effects also lead to a variety of inflammatory diseases. In this study, we identified broxyquinoline, an FDA-approved antimicrobial drug, as a effective NLRP3 inflammasome inhibitor. Broxyquinoline suppressed NLRP3 inflammasome-dependent interleukin-1β (IL-1β) release, but did not affect NLRC4 or AIM2 inflammasome activation. Mechanistically, broxyquinoline directly targets Arg165 of NLRP3 protein, thus preventing NEK7-NLRP3 interaction, NLRP3 oligomerization, and ASC speck formation, without affecting the NF-κB pathway. Consequently, broxyquinoline significantly attenuated the progression of monosodium urate (MSU)-induced peritonitis and myelin oligodendrocyte glycoprotein (MOG_35-55)-induced experimental autoimmune encephalomyelitis (EAE) in murine models. In conclusion, we demonstrated that broxyquinoline directly targets the NLRP3 protein to suppress the activation of NLRP3 inflammasome and provide a promising therapeutic agent for NLRP3 inflammasome-associated diseases.