Calcitriol blunts pro-atherosclerotic parameters through NFκB and p38 in vitro

Background Disturbances in vitamin D-3 metabolism are associated with an increased cardiovascular morbidity and mortality. The aim of this study was to assess the effects of calcitriol, the active metabolite of vitamin D-3, on pro-atherosclerotic parameters in human umbilical vein cord endothelial cells (HUVEC). Materials and methods Calcitriol at 10(-10) and/or 10(-9) mol L-1 was given to cultured HUVEC which were either non-stimulated or lipopolysaccharide (LPS) stimulated. Inter cellular adhesion molecule-1 and platelet-endothelial cell adhesion molecule-1, were determined by flow cytometry analysis. The receptor of advanced glycation end product (RAGE) and interleukin-6 (IL-6) mRNA expressions by RT-PCR and IL-6 secretion by enzyme-linked immunosorbent assay (ELISA). Nuclear p65 DNA-binding activity was measured by transcription factor assay kit and the inhibitor-kappa B alpha (I kappa B alpha), phosphorylated-I kappa B alpha (P-I kappa B alpha) and phosphorylated-p38 mitogen-activated protein kinase (MAPK) protein levels were determined by Western blot. Results Calcitriol decreased the adhesion molecules expression, as well as the LPS-induced mRNA expressions of RAGE and IL-6 and LPS induced IL-6 secretion. Furthermore, the LPS induced nuclear factor kappa B (NF kappa B)-p65 DNA-binding activity was also decreased by calcitriol. I kappa B alpha levels were increased and p-I kappa B alpha levels decreased after calcitriol treatment. The increased levels of activated p38 MAPK after LPS treatment were also decreased due to pre-incubation with calcitriol. Conclusions The decreased NF kappa B and p38 activities followed by calcitriol treatment may explain the anti-inflammatory/atherosclerotic properties of calcitriol that were observed previously and were emphasized in this study, demonstrating the inhibitory effect of calcitriol on the pro-inflammatory parameters: adhesion molecules, RAGE and IL-6.