AKT Mediates Adiponectin-Dependent Regulation of VSMC Phenotype. Cells Adiponectin (adipoq), the most abundant hormone in circulation, has many beneficial effects on the cardiovascular system, in part by preserving the contractile phenotype of vascular smooth muscle cells (VSMCs). However, the lack of adiponectin or its receptor and treatment with recombinant adiponectin have shown contradictory effects on plaque in mice. RNA sequence of and VSMCs from male aortas identified a critical role for adiponectin in AKT signaling, the extracellular matrix (ECM), and TGF-β signaling. Upregulation of AKT activity mediated proliferation and migration of cells. Activation of AMPK with metformin or AdipoRon reduced AKT-dependent proliferation and migration of cells but did not improve the expression of contractile genes. Adiponectin deficiency impaired oxidative phosphorylation (OXPHOS), increased expression of glycolytic enzymes, and elevated mitochondrial reactive oxygen species (ROS) (superoxide, and hydrogen peroxide). Anti-atherogenic mechanisms targeted the ECM in cells, downregulating MMP2 and 9 and upregulating decorin (DCN) and elastin (ELN). In vivo, the main sex differences in protein expression in aortas involved a more robust upregulation of MMP3 in females than males. Females also showed a reduction in DCN, which was not affected in males. Our study uncovered the AKT/MAPK/TGF-β network as a central regulator of VSMC phenotype. 10.3390/cells12202493

Loss of Macrophage mTORC2 Drives Atherosclerosis via FoxO1 and IL-1β Signaling. Circulation research BACKGROUND:The mTOR (mechanistic target of rapamycin) pathway is a complex signaling cascade that regulates cellular growth, proliferation, metabolism, and survival. Although activation of mTOR signaling has been linked to atherosclerosis, its direct role in lesion progression and in plaque macrophages remains poorly understood. We previously demonstrated that mTORC1 (mTOR complex 1) activation promotes atherogenesis through inhibition of autophagy and increased apoptosis in macrophages. METHODS:Using macrophage-specific Rictor- and mTOR-deficient mice, we now dissect the distinct functions of mTORC2 pathways in atherogenesis. RESULTS:In contrast to the atheroprotective effect seen with blockade of macrophage mTORC1, macrophage-specific mTORC2-deficient mice exhibit an atherogenic phenotype, with larger, more complex lesions and increased cell death. In cultured macrophages, we show that mTORC2 signaling inhibits the FoxO1 (forkhead box protein O1) transcription factor, leading to suppression of proinflammatory pathways, especially the inflammasome/IL (interleukin)-1β response, a key mediator of vascular inflammation and atherosclerosis. In addition, administration of FoxO1 inhibitors efficiently rescued the proinflammatory response caused by mTORC2 deficiency both in vitro and in vivo. Interestingly, collective deletion of macrophage mTOR, which ablates mTORC1- and mTORC2-dependent pathways, leads to minimal change in plaque size or complexity, reflecting the balanced yet opposing roles of these signaling arms. CONCLUSIONS:Our data provide the first mechanistic details of macrophage mTOR signaling in atherosclerosis and suggest that therapeutic measures aimed at modulating mTOR need to account for its dichotomous functions. 10.1161/CIRCRESAHA.122.321542

Macrophage DCLK1 promotes atherosclerosis via binding to IKKβ and inducing inflammatory responses. EMBO molecular medicine Atherosclerosis is a chronic inflammatory disease with high morbidity and mortality rates worldwide. Doublecortin-like kinase 1 (DCLK1), a microtubule-associated protein kinase, is involved in neurogenesis and human cancers. However, the role of DCLK1 in atherosclerosis remains undefined. In this study, we identified upregulated DCLK1 in macrophages in atherosclerotic lesions of ApoE mice fed an HFD and determined that macrophage-specific DCLK1 deletion attenuates atherosclerosis by reducing inflammation in mice. Mechanistically, RNA sequencing analysis indicated that DCLK1 mediates oxLDL-induced inflammation via NF-κB signaling pathway in primary macrophages. Coimmunoprecipitation followed by LC-MS/MS analysis identified IKKβ as a binding protein of DCLK1. We confirmed that DCLK1 directly interacts with IKKβ and phosphorylates IKKβ at S177/181, thereby facilitating subsequent NF-κB activation and inflammatory gene expression in macrophages. Finally, a pharmacological inhibitor of DCLK1 prevents atherosclerotic progression and inflammation both in vitro and in vivo. Our findings demonstrated that macrophage DCLK1 promotes inflammatory atherosclerosis by binding to IKKβ and activating IKKβ/NF-κB. This study reports DCLK1 as a new IKKβ regulator in inflammation and a potential therapeutic target for inflammatory atherosclerosis. 10.15252/emmm.202217198

Myeloid Cell PKM2 Deletion Enhances Efferocytosis and Reduces Atherosclerosis. Circulation research BACKGROUND:The glycolytic enzyme PKM2 (pyruvate kinase muscle 2) is upregulated in monocytes/macrophages of patients with atherosclerotic coronary artery disease. However, the role of cell type-specific PKM2 in the setting of atherosclerosis remains to be defined. We determined whether myeloid cell-specific PKM2 regulates efferocytosis and atherosclerosis. METHODS:We generated myeloid cell-specific PKM2 mice on Ldlr (low-density lipoprotein receptor)-deficient background (PKM2Ldlr). Controls were littermate PKM2Ldlr mice. Susceptibility to atherosclerosis was evaluated in whole aortae and cross sections of the aortic sinus in male and female mice fed a high-fat Western diet for 14 weeks, starting at 8 weeks. RESULTS:PKM2 was upregulated in macrophages of Ldlr mice fed a high-fat Western diet compared with chow diet. Myeloid cell-specific deletion of PKM2 led to a significant reduction in lesions in the whole aorta and aortic sinus despite high cholesterol and triglyceride levels. Furthermore, we found decreased macrophage content in the lesions of myeloid cell-specific PKM2 mice associated with decreased MCP-1 (monocyte chemoattractant protein 1) levels in plasma, reduced transmigration of macrophages in response to MCP-1, and impaired glycolytic rate. Macrophages isolated from myeloid-specific PKM2 mice fed the Western diet exhibited reduced expression of proinflammatory genes, including MCP-1, IL (interleukin)-1β, and IL-12. Myeloid cell-specific PKM2 mice exhibited reduced apoptosis concomitant with enhanced macrophage efferocytosis and upregulation of LRP (LDLR-related protein)-1 in macrophages in vitro and atherosclerotic lesions in vivo. Silencing LRP-1 in PKM2-deficient macrophages restored inflammatory gene expression and reduced efferocytosis. As a therapeutic intervention, inhibiting PKM2 nuclear translocation using a small molecule reduced glycolytic rate, enhanced efferocytosis, and reduced atherosclerosis in Ldlr mice. CONCLUSIONS:Genetic deletion of PKM2 in myeloid cells or limiting its nuclear translocation reduces atherosclerosis by suppressing inflammation and enhancing efferocytosis. 10.1161/CIRCRESAHA.121.320704