The role of T-regulatory cells and Toll-like receptors 2 and 4 in atopic dermatitis.

Regulatory T cells (Tregs), toll-like receptors (TLRs) and interleukin-17 (IL-17) play important role in inflammatory diseases; however, their relevance in atopic dermatitis (AD) pathogenesis is not clear. The aim of study was to evaluate the number of circulating Tregs and peripheral blood mononuclear cells (PBMC) expressing TLR2 and TLR4 receptors in patients with AD. PBMC and CD4+/CD25(high) + Tregs were isolated from the whole blood of 32 AD patients and 36 healthy volunteers. Expression of CD4+CD25+, TLR2 and TLR4 receptors and IL 17+ was assessed with the flow cytometry. In the peripheral blood of AD patients, the percentage of Tregs was significantly higher when compared with the controls (P=0.0003). The number of TLR2+PBMC and TLR4+ PBMC in AD patients was significantly lower than in the controls (P=0.035; P=0.001, respectively). Also the percentages of Tregs with expression of both TLR2+ and TLR4+ in AD patients were significantly lower than in the control (3.85 versus 21.6, P<0.0001; 2.2 versus 17.6, P<0.0001, simultaneously). The percentage of CD4+/CD25high+/FOXP3+ Treg lymphocytes with expression of IL-17 was significantly higher in AD group than in healthy subjects (0.3% versus 0.06%; P=0.011). Distinct number of Tregs and various distribution of TLR2 and TLR4 expression on PBMC in AD patients suggest their contribution in the pathogenesis of AD.