Feasibility of up-regulating CD4+CD25+ Tregs by IFN-γ in myasthenia gravis patients

Background: In myasthenia gravis (MG) patients, the dysfunction of CD4(+)CD25(+) regulatory T cells (CD4(+)CD25(+) Tregs) may be one of the important pathogenesis of MG. Currently, the role of IFN-gamma in autoimmune diseases is still controversial and needs further exploration. In this study, whether IFN-gamma can induce CD4(+)CD25(-) T cells into CD4(+)CD25(+) Tregs in MG in vitro was investigated systematically. Methods: Flow cytometry was used to analyze the number of CD4(+)CD25(+) Tregs in MG patients and healthy controls (HCs). CD4(+)CD25(-) T cells were separated from the peripheral blood mononuclear cells of MG patients and HCs, and the CD4(+)CD25(+) Tregs were separated from HCs by Magnetic cell sorting (MACS). IFN-gamma with different concentrations was used to stimulate CD4(+)CD25(-) T cells. The percentages of the induced CD4(+)CD25(+) T cells were detected by flow cytometry. The FoxP3 expression of the induced CD4(+)CD25(+) T cells in MG patients was detected by real-time PCR at mRNA level. The induced CD4(+)CD25(+) T cells were co-cultured with autologous CD4(+)CD25(-) T cells to estimate the suppressive ability of the induced CD4(+)CD25(+) T cells to CD4(+)CD25(-) T cells. Results: It shows the percentages of CD4(+)CD25(+) T cells among CD4(+) T cells have no significant difference in MG patients compared with those in HCs. There is also merely no difference in the percentages of CD4(+)CD25(+) T cells between thymectomized and non-thymectomized MG patients. CD4(+)CD25(-) T cells can be induced to CD4(+)CD25(+) T cells after applying IFN-gamma in MG patients and HCs. The proportion and FoxP3 expression of the induced CD4(+)CD25(+) T cells are the highest at the level of 40 ng/ml IFN-gamma, and the suppressive function of the CD4(+)CD25(+) T cells induced by 40 ng/ml IFN-gamma is the strongest in MG patients. Conclusions: This subject will further reveal the role of IFN-gamma in the pathogenesis of MG from a new perspective. It will also provide the scientific basis for the clinical targeted therapy of MG.