Vitamin D Deficiency Causes Immune Dysfunction and Enables or Perpetuates the Development of Rheumatoid Arthritis

Arthritis, Rheumatoid, Vitamin D Deficiency

Rheumatoid Arthritis, Vitamin D

Recent studies have demonstrated that subjects with low blood levels of vitamin D are at a higher risk of developing autoimmune diseases such as Rheumatoid Arthritis (RA). We are pursuing these studies to test the hypothesis that restoration of vitamin D levels ameliorates the manifestations of RA. We will test this hypothesis by inviting patients with RA to participate in a trial that examines the effects of oral vitamin D administration on the clinical expression of this disease. For this purpose, the participants of this trial will be asked to take an oral dose of 2,000 units of vitamin D daily for 6 months. We will examine the participant's joints, assess disease activity measures, and determine his/her blood levels of vitamin D before starting this treatment and periodically thereafter.

Rationale : Low vitamin D levels hinders the ability of the macrophage to produce activated 1-25Dihydroxyvitamin at sites of inflammation. 1-25Dihydroxyvitamin D has important immunoregulatory functions including down-regulation of antigen-presenting cells such as dendritic cells. Under the influence of 1-25Dihydroxyvitamin D, these dendritic cells become tolerogenic - as opposed to immunogenic - and abrogate an immune response at early stages. Immunogenic dendritic cells play a key role in the development of autoimmune diseases such as Rheumatoid Arthritis (RA) by presenting self-antigens to the immune system. Vitamin D levels are frequently low in patients with RA. Restoring vitamin D availability to normal levels in patients with RA may induce improvement of disease manifestations through expansion of the tolerogenic dendritic cell subset. Key Objectives: * Conduct a double-blind randomized clinical trial, to test the hypothesis that vitamin D administered to patients with active RA has beneficial effects on this disease. * Determine if vitamin D administered to patients with RA. induces expansion of the tolerogenic dendritic cell subset by analyzing patterns of cell surface marker expression on dendritic cells at different time points during the clinical trial (translational studies). Study Population: We will recruit early RA patients (not more that 12 month duration of disease)with active joint inflammation cared for at this institution.Participants must be subjects with active RA at the time of inclusion, who are 18 years of age or older and have no history of other autoimmune disorders or other disorders such as cancer or osteoporosis which are also linked to vitamin D deficiency. The eligible patients with active RA should be on treatment for RA with Methotrexate at the time of inclusion. Patients taking anti-cytokine treatments (considered not standard) would be excluded. Other exclusions include hypercalcemia, and a history of renal failure or renal stones. 20-25 participants will be allocated to the Vitamin D Group, Arm A. 20-25 participants will be allocated to Placebo Group Arm B Allocation will be conducted in a randomized, double-blind fashion. Summary of Procedures : After signing a written consent, all potential candidates will undergo a screening interview with the PI and screening blood tests (a blood sample of 20 ml is required). RA subjects who qualify to receive the study treatment will be randomized to receive oral vitamin D 2,000 units or placebo daily for 6 months. Patients will be examined on a monthly basis and will be drawn a 20 ml blood sample every 2 months for monitoring purposes for a period of 12 month. The participants within the clinical trial who also participate in the translational studies on dendritic cells, will be drawn an additional blood sample of 40 ml on the first month and at the end of the study to isolate their blood dendritic cells. We will study the expression of different activation markers on dendritic cells from consenting participants using various immunologic techniques. This will allow us to identify and quantify the tolerogenic dendritic cells..

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