Peripheral blood regulatory T cell measurements correlate with serum vitamin D level in patients with psoriasis

C. Mattozzi, G. Paolino, M. Salvi, L. Macaluso, C. Luci, S. Morrone, S. Calvieri, A.G. Richetta

Department of Dermatology and Venereology, “Sapienza” University of Rome, Rome, Italy. paolgio@libero.it

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• Dermatology

OBJECTIVE: Vitamin D is the precursor of a hormone (1,25-dihydroxyvitamin D3), which has many biological effects in the skin. The immune modulator properties of vitamin D are mediated in part through effects on regulatory T cells (T-reg). Currently, in psoriasis, the relationship between vitamin D and T-reg has not well elucidated.
We assess whether vitamin D status is correlated with circulating T-reg in patients affected by psoriasis and if there is a correlation with the severity of the disease evaluated with Psoriasis Area Severity Index (PASI) score.

PATIENTS AND METHODS: For each patient we have analyzed, PASI-score, serum levels vitamin D and regulatory T cell percentages. Spearmen’s coefficient was used between serum vitamin D levels and the predictors. Subsequently, the independent predictive factors were assessed by Multiple Regression.

RESULTS: A total of 26 patients were included in our analysis. Using no parametric Spearman’s Coefficient test between serum levels of vitamin D and the single variables, we found an association with T-reg population (p < 0.001) and with PASI-score (p = 0.04).

CONCLUSIONS: While vitamin D treatment induces a cytokine profile known to favor the differentiation of T cells with suppressive activity, at the same time, several studies showed how vitamin D can prime for tolerogenic dendritic cells able to favor the differentiation of Treg from T naïve cells. Low levels of vitamin-D may decrease the number of circulatory T-reg, disrupting the immunological homeostasis in psoriatic patients and encouraging the inflammatory activity.

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