The Conversion Of Treg Cells To Th1-like Treg Cells Mediated By TIGIT Deficiency In SLE

Objective:Systemic lupus erythematosus(SLE)is a systemic connective tissue disease with multi-system organ involvement due to autoimmune complex deposition.Patients with SLE are highly heterogeneous,and traditional pharmacological treatments are often unsatisfactory and have strong side effects.Therefore,the search for safe and effective therapeutic targets is the focus of current SLE research.The pathogenesis of SLE is usually considered to be an abnormal activation of the immune system due to autoimmune tolerance dysregulation,with a high activation of T-B cells,triggering an excessive adaptive immune response.Regulatory T cells(Treg),a subset of CD4~+T cells,are important immunomodulatory cells that can suppress excessive activation of effector T cells,reduce inflammatory responses,and play an important role in controlling the development of autoimmune diseases.Studies have shown that Treg cells also play an active and important role in SLE,but in SLE,the number of Treg cells is not reduced,but there is a functional defect.In pathological states,Treg can acquire the phenotype of Th1 cells while maintaining FOXP3 expression,called Th1-like Treg.It is characterized by the ability to secrete IFNγ,accompanied by reduced IL-10 secretion,and therefore its immunomodulatory function is impaired.Increased numbers of Th1-like Treg cells correlate with disease severity in patients with immunodeficiency diseases such as type 1 diabetes and multiple cerebrospinal sclerosis,however,this has not been reported in SLE.The T-cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain(TIGIT),a recently identified synergistic inhibitory receptor in immune cells,was shown to be a transcriptional target of FOXP3,and expression of TIGIT and signaling pathways can promote suppressive gene expression in Treg.In SLE,a reduced number of TIGIT~+Treg cells was found,especially in patients with renal involvement.TIGIT can control the functional stability of Treg cells by inhibiting PI3K/AKT pathway activation and prevent their differentiation to Th1-like Treg subtypes.The purpose of this study was to investigate the role of TIGIT deficiency in the differentiation of Treg cells to Th1-like Treg cells in SLE patients and the related mechanisms.This will provide new ideas,new strategies and new targets for the diagnosis and treatment of SLE.Methods:1.33 patients with SLE and 15 healthy donners(HD)were enrolled,and peripheral blood specimens were collected,peripheral blood mononuclear cells(PBMCs)were isolated,and flow cytometry was applied to detect the proportion of total Treg cells,Th1-like Treg cells and non-Th1-like Treg cells,as well as the proportion of TIGIT expression on each Treg cell subtype.Treg cells and non-Th1-like Treg cells,as well as the proportion of TIGIT expression on each subtype of Treg cells by flow cytometry.2.Collect clinical data and laboratory results of patients,and analyze the correlation between TIGIT expression on Treg cells and patients’serum C-reactive protein(CRP),Erythrocyte sedimentation rate(ESR),and complement C3 and C4.3.PBMC from peripheral blood of SLE patients were isolated and cultured until day 5 after interferonα(IFNα)intervention on day 2.4.PBMC from healthy donners were isolated and cultured on day 2 with IFNαand TIGIT stimulations or blockers until day 5,and the changes in the ratio of Th1-like Treg cells and plasma cells and the phosphorylation levels of AKT and m TOR were detected by flow cytometry.5.PBMC culture supernatants were collected and the concentration of IL-10.Results:1.Compared with healthy subjects,peripheral blood Treg cells were significantly increased in SLE patients;among Treg cell subtypes,Th1-like Treg cells were significantly increased,while there was no difference in non Th1-like Treg cells.2.The expression levels of TIGIT in peripheral blood Treg cells were all reduced in SLE patients compared with healthy donners.3.The proportion of TIGIT in Treg cells was negatively correlated with serum C3 and C4 levels.4.TIGIT expression levels on Treg cells were reduced by inflammatory factor stimulation.5.TIGIT stimulation mediated a decrease in the proportion of Th1-like Treg cell transformation and plasma cells,and an increase in culture supernatant IL-10 levels.6.Upon TIGIT stimulation,there was no difference in Th1-like Treg cell differentiation induced by TIGIT was inhibited by AKT and m TOR phosphorylation levels.Conclusions:1.TIGIT deficiency is an important factor causing defective immunosuppressive function of Treg cells and is involved in the pathogenesis of SLE by promoting Th1-like Treg cell differentiation.2.TIGIT can inhibit the differentiation of Th1-like Treg cells through AKT/m TOR pathway,promote IL-10 secretion,and alleviate the autoimmune process of SLE disease autoimmune process.