Investigation Of The Potential Effects Of T And B Lymphocytes And Related Immune Molecules In The Pathogenesis Of Immunoglobulin-G4 Related Disease

Objective: IgG4-related disease is an autoimmune disease entity characterized by significantly elevated serum IgG4 level,tume-factive enlargement of involved organs and dense infiltration of IgG4 positive staining lymphocytes,which can involve multiple organs including salivary glands,lacrimal glands,pancreas,kidneys and etc.As a result of the fact,that IgG4-RD was just newly defined at the beginning of this century,limited number of patients and the absence of appropriate animal models,people’s understanding to the pathogenesis and potential therapeutic strategies of IgG4-RD is very limited.This research aims to illustrate the potential pathogenic mechanisms of IgG4-RD via investigating the molecular signatures in the involved tissues of IgG4-RD,the potential pathogenic mechanisms of its major immune cell subsets,and the therapeutic response of IgG4-RD patients to targeted medicine(Telitacicept),which may provide useful information for deepening the understanding to,and the therapeutic innovations of this mysterious disease.Methods: Serum,PBMC were extracted from peripheral blood of IgG4-RD patients.Freshly isolated tissues of submandibular glands were obtained from IgG4-RD patients undergoing surgery biopsies.Multi-color flow cytometry was used to analyze the composition of T/B cell subsets in the peripheral blood of IgG4-RD patients at the status of treatment na?ve and after telitacicept treatment;the immune phenotypes and characteristics of involved tissue in IgG4-RD were investigated via transcriptomic sequencing at the level of tissue and single cells combined with information of immune repertoire;B cells from IgG4-RD patient and healthy control were immortalized with EBV,and were used to investigate the response of B cells to IFN-γ and IL-4 in in-vitro assays via RT-q PCR and flow cytometry;The potential pathogenesis and therapeutic targets of IgG4-RD were studied via the integrative analysis with transcriptomic and proteomic data.Results: 1、 Treatment na?ve IgG4-RD patients can be grouped into 2 phenotypes based on the level of Th1-and Th2-type cells in their peripheral bloods,and patients with increased level of both Th1-type and Th2-type CD4+ T cells possess relatively higher disease activity.2、 Th2 and Th1 cells are the major Th subsets in IgG4-RD tissue,and the related molecular signals of corresponding Th2-and Th1-type reactions are significantly enriched in involved tissues from IgG4-RD patients.A large amont of germinal center B cell-like cells can be observed in IgG4-RD,in which both of the IFN-γ and IL-4 signaling are highly enriched.3、 No specific pattern can be observed in the usage of V genes of TCR and BCR clones in IgG4-RD tissues,and the complexity of clonetypes are escalated when the disease status goes severer.These indicate the strong germinal center reactions in involved tissues of IgG4-RD resulted from interactions betweent T and B cells.4、 Th1-and Th2-type responses can influence the CSR processes and the expression of germinal center reaction-related molecules;IFN-γ and IL-4 can potentially promote the formation of TLS in involved tissues via promoting the expression of IL7 R,LTBR and LTB in different types of cells,or increase the risk of fibroblasts and epithelial cells to be the target of CD4+ CTL via enhancing their expression of MHC-II molecules.5、 Some clinical immunologic indices IgG4-RD patients,including hs CRP,serum IgM,IgA,IgG level and ratio of CD24-CD38 hi plasmablast in CD19+ B cells,show a significant decreasing tendency after treatment of telitacicept,however,some patients responded poorly to that treatment.In patients responded good to telitacicept,their serum level of immunoglobulin and ratio of plasmablasts in CD19+ B cells are relatively higher at baseline.These patients are therefore defined as “plasmablast-predominant” phenotype.In patients responded poor to telitacicept,however,significantly higher T/B cell counts in their peripheral blood at baseline can be observed(“non-plasmablastpredominant” phenotype).6、 Biological processes including antibody mediated autoimmune response,potential infection and infection simulating response,platelet activation related events,and signaling pathways including NF-κB signaling and Rap1 signaling may participate the pathogenesis of IgG4-RD.Molecules,including SRC and RAC1,are identified as potential therapeutic targets of IgG4-RD: these molecules can be the components of various biological processes or signaling pathways potentially involved in the pathogenesis of IgG4-RD,and some of them also have corresponding targeted medicines,which have already been applied in the treatment of other disease.Conclusion: Strong germinal center reactions can be observed in involved tissue of IgG4-RD;Th1-and Th2-type immune response can synergistically promote the pathogenesis of IgG4-RD;Telitacicept can exert some therapeutic effect on “plasmablast-predominant” IgG4-RD patients,while its therapeutic effect on “non-plasmablast-predominant” patients may be limited;Multiple biological processes and signaling pathways may be involved in the pathogenesis of IgG4-RD,and some molecules,which are the components of multiple signaling pathways or biological processes,have the potential to be future therapeutic targets of IgG4-RD.