Pyruvate dehydrogenase kinase 4 Triggers VSMCs phenotype switching and aortic aneurysm/dissection by regulating NLRP3 lactylation

Background Aortic aneurysm/dissection (AAD) represents a life-threatening cardiovascular disorder characterized by vascular smooth muscle cells (VSMCs) phenotype switching from contractile to synthetic type and inflammatory responses. Current clinical management of AAD primarily relies on surgical intervention with little effective pharmacotherapeutic regimen. Pyruvate dehydrogenase kinase 4 (PDK4) is a key metabolic enzyme that governs the balance between oxidative phosphorylation and glycolysis. However, the role of PDK4 in VSMC phenotype switching and the occurrence of AAD remains elusive. Purpose We aimed to investigate the functional role and mechanism of PDK4 in VSMC phenotype switching and AAD, providing novel targets and therapeutic strategies for preventing and treating AAD. Methods Smooth muscle cell-specific Pdk4 knockout (Pdk4SMCKO) mice were generated and subjected to β-aminopropionitrile monofumarate (BAPN) or angiotensin II (Ang II) treatment, which are the classical AAD mouse models. Vascular smooth muscle cells were primarily cultured and stimulated with IL-1β to establish VSMCs phenotype switching model in vitro. Small interfering RNA (siRNA) and overexpression plasmid of PDK4 were used to detect the functional role of PDK4 in regulating VSMC phenotype switching and NLRP3 inflammasome activation. Co-immunoprecipitation, LC-MS/MS and point mutation assays were performed to dissect the molecular mechanism of PDK4 in VSMC phenotype switching and AAD. Results PDK4 is significantly upregulated in aorta from AAD patients or BAPN/Ang II-induced AAD mice, and is negatively correlated with VSMC contractile markers. Pdk4SMCKO mice rescued the pathology of AAD. Gain- and loss-of-function studies establish PDK4 as a critical regulator of VSMCs phenotype switching, NLRP3 inflammasome activation, and lactylation modification. Mechanistically, PDK4-driven metabolic reprogramming enhances glycolytic flux in VSMCs, leading to lactate accumulation that mediates the lactylation of NLRP3 protein, which stabilizes NLRP3 protein—the core inflammasome component—and activates the NLRP3 inflammasome. Decreasing lactylation modification through siRNA silencing of PDK4 or pharmacological inhibition of lactate production inhibits NLRP3 inflammasome activation, which is rescued by exogenous lactate supplementation. Then the activation of NLRP3 inflammasome triggers the inflammatory cytokine IL-1β secretion which further upregulates PDK4 expression—thereby establishing a PDK4/NLRP3/IL-1β positive feedback loop, which drives VSMCs phenotype switching, culminating in AAD pathogenesis. Conclusion Taken together, our work establishes PDK4 as a major contributor of VSMCs phenotype switching and the occurrence of AAD. Targeting PDK4 represents a novel therapeutic strategy for preventing and treating AAD.