Experimental Study On Peripheral Blood T And B Lymphocyte Subsets And Related Cytokines In Patients With Ocular Myasthenia Gravis

BackgroundOcular myasthenia gravis（oMG）is a common subtype of MG.Compared to generalized MG（gMG）,the lesions of oMG usually localized in extraocular muscles.Patients with oMG come to Ophthalmology Department first for complaint of ptosis and diplopia.Because the cause of MG is unknown,the current lack of specific treatment medicine,most oMG patients who have not been treated or who have poorly controlled on hormonal treatment will develop gMG.The pathogenesis of myasthenia gravis depends upon T and B cell,as well as complement and cytokines.The activation of functional subpopulations of T and B cells is the basis of immune response.However,the activation levels of T and B cell subsets remain unclear in the pathogenesis of MG.PurposeWe aim to observe the proportion of T and B cell subsets and related cytokines in oMG patients and gMG patients,and to analyze the role of T and B cell subsets in the pathogenesis of oMG.Method16 patients with oMG,31 patients with gMG,and 20 healthy controls were included in this study.Peripheral blood mononuclear cells（PBMCs）were separated from venous blood using density centrifugation.The percentage of CD3⁺CD4⁺T cells,CD3⁺CD8⁺T cells,CD4⁺CD25⁺CD127^-regulatory T cells（Tregs）,CD19⁺CD27⁺CD38^-memory B cells,CD19⁺CD24^hiCD27⁺regulatory B cells（Bregs）,CD19⁺CD38⁺CD138⁺plasma cells and CD19⁺CD40⁺B cells in PBMCs were detected by flow cytometry.The levels of IL-2,IL-4,IL-6,IL-10,IL-17 and IFN-γin serum were detected by enzyme linked immunosorbent assay（ELISA）.The differences of T and B cell subsets and related cytokines in the three groups（oMG group,gMG group and the healthy control group）were compared.ResultThe proportion of CD3⁺CD4⁺T cells in peripheral blood of oMG patients was not significantly different from that of gMG patients and healthy controls（P=0.082;P=0.878）.However,CD3⁺CD4⁺T cells in the gMG patient group were significantly higher than those in healthy controls（P=0.013）.There was no significant difference in the proportion of CD3⁺CD8⁺T cells in peripheral blood among o MG patient group,gMG patient group and healthy control group（P=0.191）.The proportion of CD4+CD25+CD127-Tregs in peripheral blood of gMG patients was significantly lower than that of oMG patients and healthy controls（P<0.001）,but there was no significant difference between oMG patients and healthy controls（P=0.059）.The proportion of CD19⁺CD27⁺CD38^-memory B cells in the oMG and gMG patient group were significantly higher than that in healthy control group（P=0.004;P<0.001）,whereas the proportion of CD19⁺CD27⁺CD38^-memory B cells in patients with oMG was significantly lower than that in patients with gMG（P<0.001）.The proportion of CD19⁺CD24^hiCD27⁺Bregs in the o MG group was significantly higher than that in the gMG group and the healthy control group（P=0.001）,whereas there were no significant differences between the oMG patient group and the gMG patient group compared with the healthy control group,respectively（P=0.103;P=0.172）.There were no statistically significant differences between oMG group and gMG group in the proportion of CD19⁺CD38⁺CD138⁺plasma cells（P=0.192）.However,no significant CD19⁺CD38⁺CD138⁺plasma cell expression was detected in the healthy control group.Compared with oMG adn the healthy controls,the proportion of CD19⁺CD40⁺B cells in peripheral blood of patients with gMG were significantly higher（P=0.001;P<0.001）.The proportion of CD19⁺CD40⁺B cells in oMG patients was significantly higher than that in healthy controls（P=0.048）.The level of serum IL-10 in the oMG patient group was significantly higher than that in the gMG patient group and the healthy control group（P<0.05）.However,the serum IL-10 level in the gMG patient group was not significantly different from that in the healthy control group（P>0.05）.Compared with the healthy control group,serum IL-2 levels were significantly increased in the oMG patient group and the gMG patient group（P=0.016;P=0.002）,but there was no significant difference between the oMG patient group and the gMG patient group（P=0.962）.Compared with the healthy control group,serum IL-2 levels were significantly increased in the oMG patient group and the gMG patient group（P=0.016;P=0.002）,but there was no significant difference between the oMG patient group and the gMG patient group（P=0.962）.Serum IL-17 levels in gMG patients were significantly higher than oMG patients and healthy controls（P=0.013;P<0.001）,but serum IL-17 levels in oMG patients were not significantly different from those in healthy controls（P=0.565）.In addition,serum IL-6 levels in gMG patients were significantly higher than those in healthy controls（P=0.005）.However,there was no significant difference in serum IL-6 levels between oMG patients groups（P=0.163;P=0.525）.Finally,there was no significant difference in serum IL-4 and IFN-γlevels among the oMG group,the gMG group,and the healthy control group（P>0.05）.ConclusionThe decrease in the ratio of Tregs and Bregs may be an important factor in the progression of oMG to gMG,and the increase in the proportion of CD3⁺CD4⁺T cells and memory B cells may also be closely related to the progression of oMG.Moreover,cytokines such as IL-2,IL-6 and IL-10 play an important role in the development of oMG.The imbalance of T and B cell-mediated immune responses triggers oMG and further induces the production of gMG.