The dual effect of MBD2 regulating Th2 cell differentiation
Authors: Jia Aijun , Wang Yueling , Wei Jianghong , Sun Wenjin , Xiao Bing , Qiu Lulu , Pan Xia , Liu Shaozu , Sun Jingyi , Jiang Yan , Li Linqiao , Xiang Xudong , Ma Libing 
Published: February 2022

Abstract
Background: Th2 cells and IL-4 are involved in the pathogenesis of eosinophil infiltration in almost all types of asthma.In peripheral blood of asthmatic patients, methtyl-CpG binding domain protein 2 (MBD2) expression in CD4+ T cells is increased. So, the study’s objective: 1.to investigate the expression of MBD2, IRF4, Th2 cell and IL-4 in severe asthma mice; 2. to investigate whether MBD2 affects the differentiation and function of Th2 cell in mice through IRF4.. Methods: 1. C57BL/6J mice were divided into three groups: severe asthma group, conventional asthma group, and saline group. HE pathology, immunohistochemistry and WB were used to observe the expression of eosinophil cationic protein (ECP) and IL-4 in lung tissue. The positive rate of CD4 + Th2 cell from lung and spleen were detected by flow cytometry; 2. The CD4 + T cells derived from mouse spleen were divided into control group, empty transfection group, MBD2 silencing group (M(-)), MBD2 overexpression group (M(+)), IRF4 silencing group (I(-)), IRF4 overexpression group (I(+)). Th2 cells were cultured under directed differentiation conditions. The positive rate of Th2 cell was detected by flow cytometry. The expressions of IL-4, IRF4 and MBD2 were measured by WB; 3.Mouse spleen-derived CD4 + T cells were divided into control, empty transfection(M(0)/I(0)), M(-)/I(0), M(+)/I(0), M(-)/I(-), M(-)/I(+), M(+)/I(-) and M(+)/I(+) group. Th2 cells were cultured under directed differentiation conditions. The positive rate of Th2 cell was detected by flow cytometry. The expression of IL-4, IRF4 and MBD2 were measured by WB. Data were analyzed with SPSS version 25.0. The Independent‑samples t‑test was used for comparison of continuous variables between groups. P<0.05 was considered to indicate a statistically significant difference. Results: 1. There was no significant difference in ECP, IL-4 and Th2 positive rates between severe asthma group and conventional asthma group; 2. The positive rate of Th2 cells and expression of IL-4 in M (-) group increased, while the expression of IRF4 decreased. The positive rate of Th2 cells and expression of IL-4 in M (+) group decreased, while the expression of IRF4 in M (+) group was higher than empty transfection group. The expression of IL-4 decreased in I (-) group and increased in I (+) group; 3. The positive rate of Th2 cells and expression of IL-4 in M(+)/I(-) group decreased, while the positive rate of Th2 cells and expression of IL-4 in M(-)/I(+) group increased significantly. Conclusions: 1. MBD2 inhibits the differentiation and function of Th2 cells in spleen-derived CD4 + T cells of mice directly, but MBD2 promotes the expression of IL-4 through enhancing the expression of IRF4; 2.MBD2 participates in the differentiation and function of Th2 cells in severe asthma through promotion of IRF4 indirectly and inhibition of Th2 cells directly, so IL-4 expression and Th2 positive rates were no significant difference; 3.MBD2 could play dual immune effect regulating Th2 cell differentiation through IL-4 in severe asthma.