The Immunomodulatory effect of Vitamin D in Osteoimmunology

Background and the purpose of the study: The aim of this study was to investigate whether Peripheral blood mononuclear cells from osteoporotic patients have a different expression profile of inflammatory and osteoimmunology markers. In addition, the in vitro anti-inflammatory properties of 1,25(OH)2D3 in osteoporotic patients was assessed. For this purpose, cytokines profile and RANKL/OPG system in osteoporotic patients in comparison with healthy controls was investigated.Methods: Monocytes were isolated from peripheral blood of participants by the Ficoll density method, cultured and induced with vitamin D. Cells were harvested several times. RNA was extracted and then cDNA was synthesized. Inflammatory markers (IL-1β, IL- 6 and TNFα), bone metabolism markers (Osteoprotegrin and RANKL), vitamin D receptor (VDR) and β-actin genes were quantified by quantitative real-time reverse transcriptase.Results and major conclusion: The expressions of the cytokines IL-6, TNF-α, IL-1, were all down regulated by 1,25(OH)2D3 in monocytes of all participants. Monocytes from healthy control in comparison to osteoporotic patients had a clear suppression pattern of inflammatory cytokines upon vitamin D3 incubation. Of noteworthy is that mRNA expressions of inflammatory cytokines in osteoporotic patients were clearly higher than controls. Results indicated that inflammation may have critical role in osteoporosis whereas osteoporotic patients have elevated pro- inflammatory profile. Vitamin D and its receptor may have Immunomodulatory effects in osteoimmunology. This regulatory function of VDR adds substance to the inflammatory theory behind osteoporosis pathogenesis.