[Role of Imbalance between Th17 Cells and Treg Cells in the Pathogenesis of Children with Henoch-Schonlein Purpura]. OBJECTIVE
 To explore the role of Th17 cells, CD4⁺ CD25⁺ regulatory Treg cells (Treg) and its transcription factor RORγt and FoxP3 in the pathogenesis of children with Henoch-Schonlein purpura (HSP) so as to provide a new strategy for treatment of children with Henoch-Schonlein purpura by regulating the balance of Th17 and Treg cells.


 Forty children with Henoch-Schonlein purpura in acute phase admitted in our hospital from February 2012 to March 2013 were enrolled in this study, forty healthy children were simultaneously used as controls.  The expression of RORγt mRNA and FoxP3 mRNA in peripheral blood mononuclear cells was detected by real-time PCR using SYBR Green I.  The levels of IL-17A, TGF-β1, IL-2 and IL-6 in serum were measured by ABC-ELISA.  The ratio of Th17 cells to Treg cells in peripheral blood T lymphocytes was detected by flow cytometry.


 The levels of Th17 cells (2.75 ± 0.60%) and RORγt mRNA (1.11 ± 0.51) in HSP group were significantly higher than levels of Th17 cells (1.41 ± 0.29%) and RORγt mRNA (0.65 ± 0.24) (P < 0.01) in control group, but the levels of Treg cells (4.56 ± 1.26%) and FoxP3 mRNA (1.15 ± 0.45) in HSP group were lower than those of Treg cells (7.85 ± 1.97%) and FoxP3 mRNA (2.32 ± 1.1) (P < 0.01) in the control group.  The relative levels of serum IL-17A, IL-6, TGF-β1 (40.40 ± 11.81 pg/ml, 75.38 ± 27.19 pg/ml, 309.41 ± 81.03 pg/ml) in the HSP group were significantly higher than those in the control group [IL-17A (20.32 ± 10.70 pg/ml), IL-6 (25.16 ± 8.31 pg/ml), TGF-β1 (236.34 ± 66.01 pg/ml)] (P < 0.01), but the level of serum IL-2 (25.60 ± 13.19 pg/ml) in the HSP group was lower than that (34.42 ± 11.69 pg/ml) in the control group (P < 0.01).  The further detection demonstrated that in the children with acute HSP, the expression of Th17 cells positively correlated with RORγt mRNA, IL-17A and IL-6 with the correlation coefficients of 0.887, 0.938 and 0.934 (P < 0.01), respectively.  The positive correlation was also shown between the Treg cells and FoxP3 mRNA, IL-2 with the correlation coefficients of 0.834 and 0.932 (P < 0.01), respectively.


 CONCLUSION
 There are higher expression levels of Th17 cells, RORγt mRNA and IL-17A, and lower expression levels of Treg cells, FoxP3 mRNA of children with HSP in acute phase, which shows that Th17/Treg imbalance exists in children with HSP in acute phase.  The levels of serum IL-6, TGF-β1 increase and the serum IL-2 decrease in children with HSP in acute phase, moreover, there are the positive correlations between the levels of Th17 cells and expression of IL-6, as well as the level of Treg cells and expression of IL-2 in children with HSP in acute phase.
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