Targeting the MLKL-F-actin-NLRP3 axis attenuates arsenic-induced myocardial necroinflammation

Arsenic, an environmental toxicant, causes myocardial inflammatory injury upon chronic low-dose exposure, though its mechanisms are not fully understood. Necroptosis, mediated by Mixed Lineage Kinase domain-like protein (MLKL), promotes necroinflammation by activating the NOD-like Receptor family pyrin domain containing 3 (NLRP3) inflammasome. Since F-actin depolymerization may regulate NLRP3, this study investigates its role in arsenite-induced cardiac injury. Wild-type (WT) and Mlkl-knockout (Mlkl^-/-) C57BL/6 mice were exposed to arsenite (2.8-25.2 mg/L) for 8 weeks, while H9C2 cardiomyocyte were treated with arsenite (8-32 μM) for 24 h. Inhibitors targeting MLKL (Nec-1, GSK-872, NSA), NLRP3 (MCC950), and F-actin stabilization (Jasplakinolide) were employed. Arsenite dose-dependently upregulated p-MLKL and NLRP3 protein expression in myocardial tissues and H9C2 cells. Mlkl knockout or inhibition of Necroptosis (Nec-1, GSK-872, and NSA) significantly suppressed NLRP3 activation and attenuated cardiac injury. Arsenite dose-dependently induced F-actin depolymerization and reduced actin expression, which was partially reversed in Mlkl^-/- mice and Necroptosis inhibitors. F-actin stabilizer Jasplakinolide markedly inhibited NLRP3 without affecting MLKL phosphorylation. Thus, chronic arsenite exposure promotes NLRP3 inflammasome activation via p-MLKL-mediated F-actin disruption, forming a "necroptosis-cytoskeletal disruption-inflammation" cascade. Targeting the MLKL-F-actin-NLRP3 axis offers a novel strategy for preventing and treating arsenic-induced myocardial damage.