| Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) with an as yet not fully understood etiological background. The prevalence of MS is highest where environmental supplies of vitamin D are lowest. Vitamin D deficiency is caused by lack of sunlight or by low dietary vitamin D intake. Moreover, genes may be involved in the metabolism and function of vitamin D in MS patients. A pathogenic role for vitamin D deficiency in MS is further corroborated by studies in experimental allergic encephalomyelitis (EAE), an animal model for MS. The active or hormonal form of vitamin D, 1,25-dihydroxyvitamin D (1,25-(OH)2D), is a potent regulator of the immune system. 1,25-(OH)2D induces the synthesis of proteins, including the vitamin D receptor (VDR), the anti-inflammatory cytokines IL-4, IL-10 and TGF-beta1 and suppresses the production of the pro-inflammatory cytokines IL-2, IL-12 and IFN-gamma. The concept is emerging that 1,25-(OH)2D is a prerequisite for a properly functioning immune system. It is therefore that the goal of this study is to obtain an insight into the association between vitamin D and MS by investigating the 25OHD and 1,25-(OH)2D serum concentrations in MS patients. The research questions of this study are: I.a. Does the serum 25OHD or 1,25-(OH)2D concentration of MS patients differ from that of the controls in the 'summer months' and 'winter months'? I.b. What is the seasonal variation in 25OHD or 1,25-(OH)2D serum concentration in MS patients and controls? II. What is the distribution of genetic polymorphisms of the VDR gene in MS patients and controls, and does this relate to 25OHD or 1,25-(OH)2D serum concentrations? As the circulating vitamin D metabolite levels may differ according to MS diagnosis, MS treatment, gender, menopause and contraceptives or hormonal replacement therapy (HRT), these determinants will be included in the analyses. Abbreviations: Vitamin D, generic term for all vitamin D metabolites; cholecalciferol, Vitamin D3; 25-hydroxyvitamin D3, 25-hydroxycholecalciferol, 25OHD; 1,25-dihydroxy vitamin D3, 1,25-dihydroxycholecalciferol, 1,25-(OH)2D; vitamin D-binding protein, DBP; vitamin D receptor, VDR. |
