Changes and mechanisms of Th9, Th17 and CD4+ CD25+ Foxp3+ regulatory T cells in the development of adult primary immune thrombocytopenia

Abstract

Objective To investigate the expression and significance of Th9, Th17 and CD4+ CD25+ Foxp3+ regulatory T (Treg) cells as well as the related cytokines (IL-9, IL-17, TGF-β) in peripheral blood of patients with adult primary immune thrombocytopenia (ITP). Methods Peripheral blood samples were collected from 47 patients with ITP and 39 age- and sex-matched healthy subjects. The percentages of Th9, Th17 and CD4+ CD25+ Foxp3+ Treg cells in peripheral blood samples were detected with flow cytometry. The levels of IL-9, IL-17 and TGF-β in serum samples were detected by enzyme linked immunosorbent assay (ELISA). Results Compared with healthy subjects, the percentages of Th9 and Thl7 cells and the concentrations of IL-9 and IL-17 in patients with ITP were significantly increased [(1.27±0.31)% vs (0.71±0.26)%, P<0.05; (2.01±0.42)% vs (0.97±0.32)%, P<0.05. (26.52±7.48) ng/L vs (16.16±5.27) ng/L, P<0.05; (10.97±3.94) ng/L vs (7.14±2.73) ng/L, P<0.05]. The percentages of CD4+ CD25+ Foxp3+ Treg cells and the concentrations of TGF-β in patients with ITP were lower than those in healthy subjects [(4.69±0.85)% vs (7.16±1.92)%, P<0.05. (3.76±1.28) μg/L vs (6.41±1.83) μg/L, P<0.05]. Moreover, the blood platelet counts in patients with ITP were negatively correlated with the percentages of Th9 and Th17 cells and the concentrations of IL-9 and IL-17 (γs=-0.349, P=0.037; γs=-0.392, P=0.031; γs=-0.436, P=0.014; γs=-0.401, P=0.027), but were positively correlated with the percentages of CD4+ CD25+ Foxp3+ Treg cells and the concentrations of TGF-β (γs=0.411, P=0.024; γs=0.407, P=0.026). Conclusion The imbalanced distribution of Th9, Th17 and Treg cells and the abnormal expression of related cytokines (IL-9, IL-17 and TGF-β) in patients with ITP might be the possible immunological pathogenesis of ITP. Key words: Primary immune thrombocytopenia; Th9 cell; Th17 cell; CD4+ CD25+ Foxp3+ regulatory T cell; IL-9; IL-17; TGF-β