Project description:Vascular calcification is the ectopic deposition of calcium hydroxyapatite minerals in arterial wall. However, the underlying molecular mechanisms regulating vascular calcification remain incompletely understood. In this study, we applied RNA sequencing to explore the mechanism of vascular calcificaiton in both medial and atherosclerotic vascular calcification models.
Project description:Cardiovascular diseases often manifest with vascular calcification. Vascular calcification is an active process orchestrated by contractile vascular smooth muscle cell (VSMC) phenotypic switch to an osteoblast-like cell. Here, we identified that the DNA demethylase, Tet2 (Ten-eleven translation 2), safeguards VSMCs from transitioning into the osteogenic lineage and loss of Tet2 promotes development and progression of vascular calcification. Tet2 was among the most significantly downregulated epigenetic markers in calcified aortas. VSMC-specific loss of Tet2 promoted VSMC osteogenic differentiation and enhanced vascular calcification as evidenced histologically, molecularly, and hemodynamically. In vivo studies further indicated that Tet2 inhibits calcification-associated VSMC apoptosis and medial thinning. Notably, calcified regions were enriched in a Trem2hi (triggered receptor expressed on myeloid cells 2) macrophage subpopulation. Intervention studies using high-dose ascorbate to enhance Tet2 enzymatic activity resulted in significantly reduced medial aortic calcification and improved aortic structural integrity in mice. Ascorbate treatment in human aorta organ cultures was sufficient to reduce calcification development in diseased tissues, and restore contractile properties to the calcified aorta. This study highlights the potential clinical impact of modulating Tet2 activity in managing cardiovascular disorders associated with vascular calcification.
Project description:Medial artery calcification and calcific uremic arteriolopathy (CUA) are observed in patients with chronic kidney disease (CKD). They are strongly associated with increased morbidity and mortality, yet the underlying mechanisms are poorly understood, and no effective drug targets have been developed. Herein, we observed that a high phosphate, low protein (HPi-Lp) diet induced medial artery and skin arteriolar calcification in 5/6 nephrectomy (5/6 Nx) CKD mice. We further determined that p38 MAPK signaling was critical in this vasculopathy. Calcification was examined using a micro-CT scan, Alizarin Red staining, Von Kossa staining, and calcium assay. Additionally, we found that the HPi-Lp diet feeding aggravated glomerulus impairment and renal fibrosis in 5/6 Nx mice. Using RNA-Seq analysis, we identified that p38 MAPK signaling was specifically activated in the 5/6 Nx-HPi-Lp mice. Inactivation of p38 MAPK signaling using a pharmacological inhibitor SB203580 significantly reduced medial artery calcification, skin arteriolar calcium deposits, and kidney fibrosis. Collectively, our data suggest that 5/6 Nx mice fed a HPi-Lp diet can be used as a reliable mouse model for studying medial artery and CUA arteriolar calcification. Additionally, targeting p38 MAPK signaling could be a promising therapeutic strategy to mitigate these vascular disorders in patients with CKD.
Project description:Diffuse intimal thickening (DIT) is a preclinical stage of atherogenesis in humans that does not exist in commonly used mouse models of atherosclerosis. Vascular smooth muscle cells (SMCs) are the predominant cell type that occupies the intimal and medial layers of human coronary arteries. The intimal layer of DIT is particularly prone to developing atherosclerosis later in life. Differences in the molecular features between the intimal and medial layers of DIT regions may represent the earliest changes that promote atherogenesis in humans, and can be studied by spatial molecular phenotyping.