1-Phosphatidylinositol 3-Phosphate 5-Kinase Inhibition by Apilimod Promotes an Adipocyte-Like Vascular Smooth Muscle Cell Phenotype and Prevents Arterial Calcification

BACKGROUND: Cardiovascular calcification is a significant predictor and contributor to cardiovascular diseases. Vascular smooth muscle cell (SMC)-derived extracellular vesicles (EVs) play a crucial role in microcalcification formation. EVs can originate from the endosomal system, and PIKFYVE (1-phosphatidylinositol 3-phosphate 5-kinase), a lipid kinase, plays a key role in endomembrane maturation. We hypothesize that PIKFYVE inhibition will modulate EV cargo and, thereby, arterial calcification. METHODS: -deficient mice fed a high-fat, high-cholesterol diet received apilimod for 5 weeks. RESULTS: Calcified human arteries and SMCs exhibited increased PIKFYVE protein expression compared with controls. In calcifying SMCs, phosphatidylinositol 3-phosphate levels were reduced but restored by apilimod. Apilimod prevented matrix mineralization and collagen deposition in calcifying SMCs, accompanied by reduced procollagen 1A1 secretion. Apilimod inhibited TNAP (tissue-nonspecific alkaline phosphatase) at mRNA, protein, and activity levels. EVs released from apilimod-treated calcifying SMCs exhibited lower mineral cargo, reduced aggregation potential, and diminished TNAP cargo. Phenotypic omics analyses revealed that apilimod induced a shift toward an adipocyte-like SMC phenotype, marked by upregulation of adipogenic TFs (transcription factors), fatty acid metabolism genes, and increased fatty acid uptake. Reactivation of YAP (Yes-associated protein)-TEAD (transcriptional enhancer factor) signaling partially reversed these phenotypic changes. In vivo, apilimod reduced vascular calcification and plaque TNAP activity but increased plaque lipid accumulation. CONCLUSIONS: Pharmacological inhibition of PIKFYVE disrupts YAP-TEAD signaling, thereby reducing arterial calcification by limiting the calcification potential of EVs and suppressing osteogenic SMC programming, but also induces an adipocyte-like SMC phenotype with lipid accumulation. These findings emphasize the need to consider SMC phenotypic plasticity and potential adverse effects when developing therapeutic strategies for arterial calcification.