Evaluation of balance between regulatory T cells and T helper 17 cells in patients with atopic dermatitis

[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 Thl7 cells (CD4+ILl7+ 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 ceils (r =-0.40,P＜ 0.05 ),but positively correlated with that of Th17 cells (r =0.42,P ＜ 0.05 ).[Conclusion]s There exists a change in Treg/Th 17 ratio,mRN A 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: Dermatitis; atopic; CD4-positive T-lymphocytes; T-lymphocytes; regulatory; Th17 cells