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

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-γ in autoimmune diseases is still controversial and needs further exploration. In this study, whether IFN-γ can induce CD4⁺CD25⁻ T cells into CD4⁺CD25⁺ Tregs in MG in vitro was investigated systematically.

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-γ 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.

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-γ 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-γ, and the suppressive function of the CD4⁺CD25⁺ T cells induced by 40 ng/ml IFN-γ is the strongest in MG patients.

This subject will further reveal the role of IFN-γ in the pathogenesis of MG from a new perspective. It will also provide the scientific basis for the clinical targeted therapy of MG.