Abstract:

Objective To assess the role of imbalance between regulatory T （Treg） cells and T helper 17 （Th17） cells in the pathogenesis of atopic dermatitis（AD）. Methods Peripheral blood was obtained from 41 patients with AD and 38 age- and sex-matched healthy controls. Flow cytometry was performed to determine the percentage of Treg cells （CD4+CD25+Foxp3+ T cells） and Th17 cells（CD4+IL17+ T cells）, real-time quantitative reverse transcription （RT）-PCR to detect the mRNA expressions of Foxp3 and RORγt, which are the specific transcription factors of Treg and Th17 cells respectively. Serum concentrations of transforming growth factor （TGF）-β, IL-17 and IL-23 were measured by enzyme linked immunosorbent assay（ELISA）. Data were statistically assessed by independent-samples t test and Pearson correlation analysis. Results The patients with AD showed an obvious decrease in Treg cell percentage, transcription factor Foxp3 mRNA level and Treg/Th17 ratio （2.01% ± 0.57% vs. 5.04% ± 1.44%, t = 12.47, P ＜ 0.01; 0.65 ± 0.19 vs. 1.71 ± 0.69, t = 9.47, P ＜ 0.01; 1.26 ± 0.61 vs. 14.53 ± 5.77, t = 14.11, P ＜ 0.01）, but a significant increase in peripheral Th17 cell percentage and transcription factor RORγt mRNA level（1.77% ± 0.55% vs. 0.39% ± 0.15%, t = 14.82, P ＜ 0.01; 5.97 ± 1.45 vs. 1.49 ± 0.57, t = 17.78, P ＜ 0.01） compared with the healthy controls. Further comparison revealed that Treg/Th17 ratio was significantly lower in patients with acute AD than in those with subacute AD（0.88 ± 0.04 vs. 1.29 ± 0.11, t = 4.02, P ＜ 0.01） and those with chronic AD（2.05 ± 0.24, t = 4.83，P ＜ 0.01）, statistically different between patients with subacute AD and chronic AD（t = 2.89，P ＜ 0.05）. There was no significant difference in the serum concentration of TGF-β between patients with AD and healthy controls （（15.28 ± 2.34） μg/L vs. （16.56 ± 3.27） μg/L, t = 1.96, P ＞ 0.05）. A significant increase was observed in the serum levels of IL-17 and IL-23 in patients with AD compared with those in the healthy controls（（33.24 ± 7.06） ng/L vs. （11.68 ± 2.67） ng/L, t = 17.96, P ＜ 0.01； （56.35 ± 12.16） ng/L vs. （18.43 ± 3.90） ng/L, t = 18.36, P ＜ 0.01）. In patients with moderate and severe AD, SCORing atopic dermatitis （SCORAD） index was negatively correlated with the percentage of Treg cells （r = －0.40, P ＜ 0.05）, but positively correlated with that of Th17 cells（r = 0.42, P ＜ 0.05）. Conclusions There exists a change in Treg/Th17 ratio, mRNA expressions of RORγt and Foxp3, and serum levels of relevant cytokines in patients with AD, which may lead to immune imbalance and subsequently contribute to the development of AD.

Key words: Th17 cells