Tanshinone IIA alleviates cerebral ischemia-reperfusion injury by inhibiting pyroptosis: involvement of the KLF4/CHIP/NLRP3 pathway.

Cerebral ischemia/reperfusion injury (CI/RI) is a critical pathological process in ischemic stroke. Pyroptosis plays a central role in the development of CI/RI. NOD-like receptor protein 3 (NLRP3) inflammasome is a key initiator of pyroptosis and is associated with neuroinflammation. Although Tanshinone IIA (Tan-IIA) downregulates NLRP3 expression, its role in NLRP3-mediated neuronal pyroptosis during CI/RI remains unclear. In the current study, we aimed to evaluate the neuroprotective effects of Tan-IIA on CI/RI and elucidate the underlying molecular mechanisms. We used rat middle cerebral artery occlusion/reperfusion (MCAO/R) and PC12 cell oxygen-glucose deprivation/reoxygenation (OGD/R) models to investigate the underlying mechanisms. A range of methodologies were used, including neurological function scoring, western blotting, co-immunoprecipitation (Co-IP), dual-luciferase reporter assays, chromatin immunoprecipitation (ChIP), and cycloheximide (CHX) chase. Tan-IIA substantially improved neurological function, reduced cerebral infarction volume, and mitigated neuronal necrosis in MCAO/R rats. In PC12 cells, Tan-IIA showed a pronounced protective effect against OGD/R-induced damage in OGD/R. Mechanistically, in vitro evidence suggests that Tan-IIA upregulates Krüppel-like factor 4 (KLF4) expression. This, in turn, transcriptionally activates the Carboxy-terminus of Hsc70-interacting protein (CHIP). The increased CHIP expression appeared to promote ubiquitination and degradation of the NLRP3 protein, inhibiting the NLRP3 inflammasome activation, caspase-1 cleavage, and the maturation of interleukin (IL)-1β and IL-18, suppressing neuronal pyroptosis. Our findings suggest that Tan-IIA alleviates CI/RI at least in part through a KLF4/CHIP/NLRP3-related mechanism, with strong in vitro support for this pathway. Direct causal validation in vivo remains to be established. This study provides evidence of the protective role of Tan-IIA in experimental models of CI/RI.