Background In addition to the classical role on bone metabolism, recent studies highlight that vitamin D (VD) may have an immunomodulatory action on T cells, inhibiting Th-1 and Th-17 response and enhancing Th-2 and T-regulatory (Treg) function. After repeated antigenic presentation, T cells undergo different functional and phenotypical modifications, leading to the differentiation into highly experienced memory T cells (CD45RA+CCR7-) and to the down-modulation of CD28. It may lead to the peripheral expansion of the CD28- T cells, a subpopulation with peculiar effector activities (high g-IFN production) .
Systemic Lupus Erythematosus (SLE) is an autoimmune disease in which activation of autoreactive T and B lymphocytes and alteration of Treg functionality may have a pathogenic role . A great prevalence of VD insufficiency has been described in SLE patients (pts), probably due to the low direct sunlight exposition.
Objectives To study the effect of VD supplementation on the circulating levels of different T-cells subsets and on cytokines production in patients with SLE.
Methods 51 female SLE pts with a clinically quiescent but serologically active disease were enrolled. 33 pts were supplemented with an intensive regimen (IR) of colecalciferol (300.000UI for the first month and 50.000UI/monthly as maintenance), whereas 18 pts were supplemented with a standard regimen (SR) (25.000UI monthly). Phenotypic analysis of peripheral T lymphocyte and the intracytoplasmatic production of IL-4 and g-IFN from peripheral blood mononuclear cells was evaluated by flow-cytometry.
Results After 12 months of treatment, a significant increase in the percentage of peripheral induced Treg cells (CD25highCD127lowCCR7-) was observed independently from the regimen of supplementation and a gain of recent thymic emigrants (RTE) Treg cells (CD25highCD127lowCD31+) was detected in pts of IR (table 1).
We also observed an increase in the total amount of circulating CD4+CD45RA+CCR7- T cells, whereas a significative reduction of the CD8+CD28- T cells in SLE pts on SR was seen (table 1).
In the IR group of patients evaluated for cytokines production (n=8), a reduction of g-IFN/IL-4 (from 12.1 to 3.2; p=0.01) among CD8+ T cells was detected.
Conclusions VD may have immunomodulatory properties on T cells, enhancing an increase of different subpopulations of Treg cells and promoting the production of Th2 cytokines.
Strioga M. Immunology 2011; 134 (1): 17-32;
Terrier B et al. Arthritis Res Ther 2012; 14: R221.
Disclosure of Interest None declared