Possible Relation between Vitamin D and Interleukin-17 in the Pathogenesis of Lichen Planus

Lichen planus (LP) is a chronic autoimmune inflammatory mucocutaneous disease. Interleukin (IL)-17 is the signature cytokine of T-helper 17 cells, involved in the aetiology of many autoimmune and inflammatory disorders. Vitamin D has an immune-regulatory role and suppresses IL-17 production via direct transcriptional inhibition of IL-17 gene expression.

To explore the relationship of IL-17 and vitamin D levels with LP, and the possible inter-relationship between IL-17 and vitamin D.

The study enrolled 30 patients with LP and 30 healthy controls. Blood samples and skin biopsies were taken from all participants for evaluation of serum vitamin D, and serum and tissue IL-17 levels using enzyme-linked immunosorbent assay (ELISA).

Patients had significantly higher serum and tissue IL-17 (p < 0.001 for both), as well as significantly lower serum vitamin D levels and more deficient patterns of vitamin D status than controls (p < 0.001 for both). In the patient group, there was a statistically significant positive correlation between extent of the disease and serum IL-17. There was no direct statistical correlation between IL-17 levels and serum vitamin D in either patients or controls.

This study confirms a previously suggested role of IL-17 in the pathogenesis of LP and suggests its relation to the extent and severity of the disease. We also found an association between vitamin D deficiency and LP. However, a direct relationship between IL-17 and vitamin D deficiency could not be clarified.