High levels of peripheral serotonin, produced in the gut, are associated with increased cardiovascular disease risk and bone loss. We previously found that vascular smooth muscle and valvular cells ex Show more
High levels of peripheral serotonin, produced in the gut, are associated with increased cardiovascular disease risk and bone loss. We previously found that vascular smooth muscle and valvular cells express serotonin receptors, predominantly type 2A (HTR-2A) at baseline and type 2B (HTR-2B) upon TNF-a stimulation. Serotonin treatment augmented TNF-a-induced matrix calcification, whereas the inhibitor of gut serotonin, LP533401, blunted the initiation, but not the progression, of cardiovascular calcification in Apoe Show less
Endothelial-to-mesenchymal transition (EndMT) has been implicated in inflammatory vascular pathologies such as atherosclerosis. The nonfibrillar collagen type VIII functions as a pivotal player in ath Show more
Endothelial-to-mesenchymal transition (EndMT) has been implicated in inflammatory vascular pathologies such as atherosclerosis. The nonfibrillar collagen type VIII functions as a pivotal player in atherogenesis, but its role in EndMT is not well understood. We assessed the role of the α 1 chain of collagen type VIII (COL8A1) in inflammatory EndMT. Single-cell RNA-seq analysis of murine and human endothelial cells exposed to atherogenic stimuli in vivo revealed increased COL8A1 expression. Immunofluorescent analyses showed that COL8A1 expression was increased in murine atherosclerotic lesions, coinciding with the decreased expression of the endothelial marker platelet endothelial cell adhesion molecule-1. Treatment of human aortic endothelial cells (HAECs) with tumor necrosis factor-α (TNF-α) induced inflammatory EndMT. Interestingly, TNF-α treatment had a biphasic effect on COL8A1 expression in HAECs, with an initial downregulation followed by upregulation at 5 days of treatment. HAECs were then subjected to either exogenous recombinant COL8A1 (rcol8a1) exposure, lentiviral COL8A1 overexpression, or COL8A1 siRNA inhibition. Functionally, COL8A1 knockdown in HAECs suppressed endothelial gene programs, impaired tube formation, and enhanced NF-κB/Snail activation. Conversely, recombinant COL8A1 or lentiviral overexpression preserved endothelial morphology and markers and attenuated TNF-α-induced EndMT. Our findings suggest that COL8A1 is a key regulator of endothelial stability during inflammatory stress. Its transient inhibition facilitates early EndMT via NF-kB/Snail signaling, whereas its later induction in advanced disease reflects endothelial remodeling within atherosclerotic lesions. These findings identify COL8A1 as both a biomarker and a potential therapeutic target in vascular disease. Show less
Vascular calcification is recognized as an independent predictor of cardiovascular mortality, particularly in subjects with chronic kidney disease. However, the pathways by which dysregulation of lipi Show more
Vascular calcification is recognized as an independent predictor of cardiovascular mortality, particularly in subjects with chronic kidney disease. However, the pathways by which dysregulation of lipid and mineral metabolism simultaneously occur in this particular population remain unclear. We have shown that activation of the farnesoid X receptor (FXR) blocks mineralization of bovine calcifying vascular cells (CVCs) and in ApoE knock-out mice with 5/6 nephrectomy. In contrast to FXR, this study showed that liver X receptor (LXR) activation by LXR agonists and adenovirus-mediated LXR overexpression by VP16-LXRα and VP16-LXRβ accelerated mineralization of CVCs. Conversely, LXR inhibition by dominant negative (DN) forms of LXRα and LXRβ reduced calcium content in CVCs. The regulation of mineralization by FXR and LXR agonists was highly correlated with changes in lipid accumulation, fatty acid synthesis, and the expression of sterol regulatory element binding protein-1 (SREBP-1). The rate of lipogenesis in CVCs through the SREBP-1c dependent pathway was reduced by FXR activation, but increased by LXR activation. SREBP-1c overexpression augmented mineralization in CVCs, whereas SREBP-1c DN inhibited alkaline phosphatase activity and mineralization induced by LXR agonists. LXR and SREBP-1c activations increased, whereas FXR activation decreased, saturated and monounsaturated fatty acids derived from lipogenesis. In addition, we found that stearate markedly promoted mineralization of CVCs as compared with other fatty acids. Furthermore, inhibition of either acetyl-CoA carboxylase or acyl-CoA synthetase reduced mineralization of CVCs, whereas inhibition of stearoyl-CoA desaturase induced mineralization. Therefore, a stearate metabolite derived from lipogenesis might be a risk factor for the development of vascular calcification. Show less