Abstract 14353: Deficiency of Protein Kinase Cδ Revamps Atherosclerotic Plaque Complexity by Halting Inflammasome Activation and Intensifying Mitochondrial Function

Abstract

Introduction: Plaque complexities substantially contribute to acute coronary syndrome. Inflammation and cell death in macrophages play a vital role in the formation of vulnerable plaques. Previous study had shown that protein kinase Cδ (PKCδ) is involved in the initiation and progression of atherosclerosis. However, the role of PKCδ on plaque stability remains unclear. Hypothesis: PKCδ regulates macrophage inflammation and cell death, leading to the formation of vulnerable plaques. Methods: The PKC family gene expressions in human atheroma plaques and nearby macroscopically intact tissues were analyzed from the gene expression omnibus data sets GSE43292. Two main mice models, including Ldlr -/- / PKCδ -/- mice and Ldlr -/- mice lethally irradiated and bone marrow transplanted (BMT) with either PKCδ -/- or wild type (WT), were applied to evaluate the impact of macrophages PKCδ on atherosclerosis. Blood, aorta, and aortic sinus were collected. The effects and underlying molecular mechanisms of PKCδ on inflammasome activation, pyroptosis, and mitochondrial function were explored using bone marrow-derived macrophage (BMDM) from PKCδ -/- and WT mice. Results: The gene expression of PKCδ significantly increases in human atheroma plaques, which is correlated with the expression of NLRP3 inflammasome. The deletion of PKCδ reduces plasma lipid profile and atherosclerosis in Ldlr -/- mice. Moreover, the deletion of PKCδ attenuates necrotic core formation, in both double knockout and BMT models. The RNA-seq analysis revealed that pyroptosis and mitochondrial oxidative phosphorylation (OXPHOS) are the potential mechanisms in PKCδ-regulated atherosclerosis. Additionally, knockout of PKCδ reduces expressions of LPS/IFNγ-induced TNFα, IL-6, and NLRP3 inflammasome in BMDM. Finally, the deficiency of PKCδ increases mitochondrial OXPHOS in BMDM, suggesting a potential role for PKCδ in the regulation of cellular metabolism and inflammation. Conclusions: Our findings indicate a crucial role for PKCδ in the development of complex atherosclerotic plaques, as it promotes inflammation, pyroptosis, and mitochondrial dysfunction. Targeting PKCδ could potentially be a therapeutic strategy for the treatment of atherosclerosis.