The proteolytic effects of MMPs were modulated mainly by TIMPs

ll types. In our study, inhibition of the IB kinase by PS-1145 prevented upregulation of VCAM-1 and ICAM-1 in shVDR endothelial cells, suggesting that upregulation of adhesion molecules in these cells was mediated via NF-B signaling. To substantiate the involvement of the canonical NF-B pathway in VDR knockdownmediated endothelial cell activation, we stably overexpressed a super-repressor IB in both shc002 and shVDR cells. Inhibition of NF-B activation with super-repressor IB markedly blunted all signs of endothelial cell activation induced by VDR knockdown such as overexpression of VCAM-1, ICAM-1, IL-6, as well as leukocyte-endothelial cell interactions, adding a new piece of evidence regarding the involvement of the canonical NF-B pathway. To study the effects of VDR deletion on atherosclerotic plaque development in vivo, we combined a genetic model of VDR deletion with a mouse model of experimental atherosclerosis, PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19729642 the apolipoprotein E knockout mouse. We acknowledge that the model of the VDR KO is an absolute model that can give interesting information, but that cannot be compared to real situations of patients with a deficit of vitamin D. However, we 480-44-4 chemical information demonstrated that deletion of VDR increased atherosclerotic lesion formation in apoE-/-VDR-/- mice fed a HFRD. Furthermore, apoE-/-VDR-/- mice showed significant changes in the lesion cellular content seen as an increase in the number of Mac-3+ macrophages in the aortic arch and aortic root regions, along with a higher immunoreactivity for MCP-1. There were no differences in TUNEL-positive apoptotic cells. Therefore, the enhanced plaque formation with abundant macrophage infiltration found in apoE-/-VDR-/- mice could be due to enhanced leukocyte recruitment into the vascular wall. Owing to the nature of a total knockout mouse model, the possible effect of lacking VDR in other cell types, such as macrophages and VSMCs, should not 13 / 20 VDR Signaling Inhibits Endothelial Cell Activation be neglected. Previous studies have shown the role of vitamin D and the VDR in the process of atherosclerosis. In a very recent paper of Weng et al., using mouse model of dietinduced vitamin D deficiency, the authors demonstrated the importance of vitamin D in the protection against atherosclerosis, highlighting vitamin D replacement as a potential therapy to attenuate this disease. In accordance with our findings, Szeto et al. showed that genetic lack of VDR led to a significant acceleration of plaque formation in LDLR-/- mice, accompanied by increases in inflammatory PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19728767 molecules in the aorta and cholecterol influx in macrophages. The authors pointed out to macrophage VDR signaling, specifically suppression of local RAS, as responsible for the inhibition of atherosclerosis in LDLR-/- mice. Our results, on the apoE-/- model of atherosclerosis, agree with these previous reports and provide information on plaque size and composition in two highly susceptible areas for atherosclerosis, aortic arch and aortic root, in vivo. By dissecting the role of lacking VDR in endothelial cells in vitro, our data give a new perspective on the role of VDR in the atherogenesis process. Interestingly, accelerated lesion formation in apoE-/-VDR-/- mice was not correlated with serum lipid levels, known to be the major risk factor for atherosclerosis. Namely, apoE-/-VDR-/mice showed remarkably lower levels of total, LDL and HDL cholesterol than apoE-/-mice, alongside strikingly normal serum triglyceride levels, suggesting that l