Abnormalities In B Cell Subsets And Immunoglobulins In Patients With Premature Ovarian Insufficiency

Background:Premature ovarian insufficiency(POI)is a common reproductive endocrine disorder that causes infertility in reproductive-aged women.It is characterised by menstruation irregularities(amenorrhea,oligomenorrhea,or polymenorrhea),increased levels of folliclestimulating hormone(FSH>25 IU/L),and fluctuating oestrogen levels before the age of 40.The etiology and pathogenesis of POI are complicated,involving gene mutations,chromosomal abnormalities,autoimmune abnormalities,iatrogenic damage,and the etiology in more than half of patients remains unknown.Autoimmune abnormalities can explain about 5-30%of POI patients,including concomitant autoimmune diseases,various autoimmune antibody abnormalities,cellular immunity imbalance,and oopharitis.However,there is currently a lack of effective predicting and diagnostic indicators for autoimmune POI in clinical practice.B cells and immunoglobulins play important regulatory roles in cellular and humoral immunity,and their abnormalities are associated with autoimmune diseases,such as systemic lupus erythematosus and rheumatoid arthritis.The presence of multiple ovarian autoantibodies in the serum of patients with POI suggested that aberrant humoral immunity is involved in the pathogenesis of POI;however,the changes in total immunoglobulins in patients with POI have not been reported.In addition,the cellular immunity disturbances in patients with POI mainly focused on T cells,such as the imbalance of TH1/Treg,and it is currently unclear whether there are abnormalities in the distribution,phenotype,and function of B cell subsets in patients with POI.Therefore,the abnormalities in B cell subsets and immunoglobulins in patients with POI warrant further exploration in order to provide important insights for the etiological diagnosis,early prevention and intervention of POI.Objective:The purpose of this study is to investigate the abnormalities in B cell subsets and immunoglobulins in the periphery and ovarian microenvironment of patients with POI,and evaluate the association of abnormal immune indicators with ovarian reserve,to elucidate the humoral immune abnormalities in patients with POI.Methods:1.The number,phenotype and function of peripheral blood B cell subsets were detected with flow cytometry and compared between patients with POI and healthy controls.2.The levels of total immunoglobulins and subclasses in the serum and follicular fluid were detected with turbidimetric immunoassay and compared between patients with POI and controls.3.The relationship between abnormal immune indicators and ovarian reserve function were evaluated by correlation analysis.4.The expression and localization of different IgG receptors were examined by flow cytometry,immunohistochemistry and immunofluorescence,and compared between ovarian follicles within different developmental stages.Results:1.Compared with control women,the patients with POI showed significantly increased proportions and numbers of peripheral blood B cells,with increased proportions of immature B cells and decreased class-switched memory B cells and plasma cells.The proportions of transitional B cells and non-class-switched memory B cells showed no significant differences between the two groups.These results suggestied that patients with POI have abnormal distributions of B cell subsets.2.Compared with healthy controls,the patients with POI had significantly decreased proportions of regulatory B cells(Bregs)in peripheral blood,including CD19+IL-10+Bregs,CD19+CD24hiCD27+Bregs,and CD19+CD24hiCD38hi Bregs.Further exploration of the functional phenotypes of Bregs revealed no significant differences in the inhibitory effects of CD19+CD24hiCD27+Bregs on IFN-γ and TNF-α production of T cells between the two groups.3.Abnormalities in both B cell subsets and Bregs in patients with POI were positively correlated with disease severity.4.Compared with controls,the patients with POI had decreased levels of serum IgG and IgM,and the patients with biochemical POI(bPOI)had significantly decreased levels of serum IgG,as well as levels of IgG,IgA,and IgM in follicular fluid.All of these abnormalities were shown to be strongly associated with reduced ovarian reserve.There were no significant differences in the distribution of IgG subclasses in follicular fluid between the two groups.5.As ovarian follicles mature,the level of IgG in follicular fluid increased gradually while the level of IgM decreased.FcRn is the most highly expressed receptor of IgG in mouse ovaries.However,its expression level does not significantly increase with follicular development.Conclusion:Abnormal B-cell subsets and immunoglobulin levels have been identified in the peripheral and ovarian microenvironments of patients with POI,and are associated with disease severity,which provide new evidence of autoimmune abnormality in patients with POI.