Effect of vitamin D on Epstein-Barr (EBV)-specific CD8+T cells in patients with early multiple sclerosis (MS)

Background: Infection with EBV and a lack in vitamin D may be important environmental triggers of MS. 1,25-(OH)2D3 mediates a shift of antigen presenting cells (APC) and CD4+ T cells to a less inflammatory profile. Although CD8+ T cells do express the vitamin D receptor, a direct effect of 1,25(OH)2D3 on these cells has not been demonstrated until now. Since CD8+ T cells are important immune mediators of the inflammatory response in MS, we examined whether vitamin D directly affects the CD8+ T cell response, and more specifically if it modulates the EBV-specific CD8+ T cell response. Material and Methods: To explore whether the vitamin D status may influence the pattern of the EBV-specific CD8+ T cell response, PBMC of 10 patients with early MS and 10 healthy controls (HC) were stimulated with a pool of immunodominant 8-10 mer peptide epitopes known to elicit CD8+ T cell responses. PBMC were stimulated with this EBV CD8 peptide pool, medium (negative control) or anti- CD3/anti-CD28 beads (positive control). The following assays were performed: ELISPOT to assess the secretion of IFN-gamma by T cells in general; cytometric beads array (CBA) and ELISA to determine whichcytokines were released by EBV-specific CD8+ T cells after six days of culture; and intracellular cytokine staining assay to determine by which subtype of T cells secreted given cytokines. To examine whether vitamin D could directly modulate CD8+ T cell immune responses, we depleted CD4+ T cells using negative selection. Results: We found that pre-treatment of vitamin D had an antiinflammatory action on both EBV-specific CD8+ T cells and on CD3/ CD28-stimulated T cells: secretion of pro-inflammatory cytokines (IFNgamma and TNF-alpha) was decreased, whereas secretion of antiinflammatory cytokines (IL-5 and TGF-beta) was increased. At baseline, CD8+ T cells of early MS patients showed a higher secretion of TNFalpha and lower secretion of IL-5. Addition of vitamin D did not restore the same levels of both cytokines as compared to HC. Vitamin D-pretreated CD8+T cells exhibited a decreased secretion of IFN-gamma and TNF-alpha, even after depletion of CD4+ T cells from culture. Conclusion: Vitamin D has a direct anti-inflammatory effect on CD8+ T cells independently from CD4+ T cells. CD8+ T cells of patients with earlyMS are less responsive to the inflammatory effect of vitamin D than HC, pointing toward an intrinsic dysregulation of CD8+ T cells. The modulation of EBV-specific CD8+T cells by vitaminDsuggests that there may be interplay between these twomajor environmental factors of MS. This study was supported by a grant from the Swiss National Foundation (PP00P3-124893), and by an unrestricted research grant from Bayer to RDP.

High prevalence of hypovitaminosis D in a Swiss rheumatology outpatient population.

Vitamin D is important for bone metabolism and neuromuscular function. While a routine dosage is often proposed in osteoporotic patients, it is not so evident in rheumatology outpatients where it has been shown that the prevalence of hypovitaminosis D is high. The aim of the current study was to systematically evaluate the vitamin D status in our outpatient rheumatology population to define the severity of the problem according to rheumatologic diseases. During November 2009, all patients were offered a screening test for 25-OH vitamin D levels and categorised as deficient (<10 µg/l [ng/ml] [25 nmol/l]), insufficient (10 µg/l to 30 µg/l [25 to 75 nmol/l]) or normal (>30 µg/l [75 nmol/l]). A total of 272 patients were included. The mean 25-OH vitamin D level was 21 µg/l (range 1.5 to 45.9). A total of 20 patients had vitamin D deficiency, 215 patients had an insufficiency and 37 patients had normal results. In the group of patients with osteoporosis mean level of 25-OH vitamin D was 25 µg/l and 31% had normal results. In patients with inflammatory rheumatic diseases (N = 219), the mean level of 25-OH vitamin D was 20.5 µg/l, and only 12% had normal 25-OH vitamin D levels. In the small group of patients with degenerative disease (N = 33), the mean level of 25-OH vitamin D was 21.8 µg/l, and 21% had normal results. Insufficiency and deficiency were even seen in 38% of the patients who were taking supplements. These results confirm that hypovitaminosis D is highly prevalent in an outpatient population of rheumatology patients, affecting 86% of subjects. Despite oral supplementation (taken in 38% of our population), only a quarter of those on oral supplementation attained normal values of 25-OH vitamin D.