Fibroblast S1PR2 Amplifies NLRP3 Inflammasome Activation Under Pressure Overload

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BACKGROUND: Although NLRP3 (NOD-like receptor family pyrin domain containing 3) inflammasome activation has been implicated in pressure overload-induced cardiac hypertrophy, inflammation, and heart failure, prior studies have focused primarily on cardiomyocytes and immune cells. The potential contribution of cardiac fibroblasts to NLRP3 inflammasome activation under pressure overload remains poorly defined. Here, we investigated the role of cardiac fibroblasts in NLRP3 inflammasome activation and sought to identify its key upstream regulator in the pressure-overloaded heart. METHODS: loss- and gain-of-function mouse models. Transverse aortic constriction was used to induce pressure overload. RESULTS: We identified cardiac fibroblasts as the principal effectors of NLRP3 inflammasome activation under pressure overload. NLRP3 deficiency in fibroblasts markedly attenuated cardiac hypertrophy and inflammation under pressure overload. We further found that S1PR2 (sphingosine-1-phosphate receptor 2) is a critical upstream regulator of fibroblast NLRP3 inflammasome activation. Fibroblast-specific S1PR2 deletion suppressed inflammasome activation, mitigated hypertrophy, and preserved cardiac function, whereas S1PR2 overexpression in fibroblasts exacerbated these pathological changes under pressure overload. Further analyses revealed that S1PR2/ROCK (rho-associated coiled-coil-containing protein kinase) signaling augments DRP1 (dynamin-related protein 1)-dependent mitochondrial fission while suppressing Parkin-mediated mitophagy, thereby promoting mitochondrial damage and mitochondrial DNA leakage, which in turn culminate in NLRP3 inflammasome activation. CONCLUSIONS: This study provides in vivo evidence that cardiac fibroblasts constitute a major source of NLRP3 inflammasome activation in response to pressure overload. Fibroblast S1PR2 signaling links mitochondrial dysfunction to inflammasome activation, revealing a novel proinflammatory axis that exacerbates pressure overload-induced heart failure.

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