Hepatocyte‐Derived Extracellular Vesicles Deliver miR‐328‐3p to Trigger PP2A‐B56δ–Mediated p‐NLRP3 ^S295 ‐Dependent Metaflammation in Macrophages upon Microcystin‐LR Exposure

Abstract Microcystin‐LR (MC‐LR) exacerbates metabolic dysfunction‐associated steatotic liver disease (MASLD) by inducing histopathological damage and lipid metabolism disorders. Inducible hepatocyte‐derived extracellular vesicles (iHD‐EVs) released after xenobiotic exposure activate the macrophage NOD‐like receptor protein 3 (NLRP3) inflammasome. Suppression of NLRP3 phosphorylation at serine 295 (p‐NLRP3 ^S295 ) is previously shown to alleviate MASLD progression. Here, it is demonstrated that microcystin‐LR (MC‐LR)‐induced iHD‐EVs reduced deliver of miR‐328‐3p to macrophages, thereby upregulating protein phosphatase 2A (PP2A)‐B56δ. Consequent PP2A‐B56δ activation disrupts inositol 1,4,5‐triphosphate receptor and voltage‐dependent anion channel 1 coupling, evokes mitochondria‐associated endoplasmic reticulum membrane (MAM) calcium (Ca ²⁺ ) overload, and recruits p‐NLRP3 ^S295 into the inflammasome. Neutralization of p‐NLRP3 ^S295 with a site‐specific monoclonal antibody (anti‐p‐NLRP3 ^S295 mAb) markedly attenuates liver inflammation and injury in MC‐LR‐exposed mice. Collectively, the miR‐328‐3p/PP2A‐B56δ/p‐NLRP3 ^S295 axis is identified as a crucial driver of metaflammation and establishes circulating EV‐miR‐328‐3p as a novel biomarker and anti‐p‐NLRP3 ^S295 mAbs as translational tools for MC‐LR‐associated MASLD.