Aspirin Ameliorated Lupus Manifestations In Pristane-induced Lupus Mice By Regulating CGAS-STING-IFN Pathway

BackgroundSystemic lupus erythematosus(SLE)is an autoimmune disease characterized by elevated serum levels of multiple autoantibodies and involvement of systemic organs and multiple systems.The onset of SLE is related to its autoantibody against doublestranded DNA.The dsDNA in the serum of SLE patients is significantly increased.Anti-dsDNA antibody have become a major basis for diagnosis and clinical evaluation of disease activity in patients.The importance of DNA intracellular receptor AIM2/TLR9 in disease pathogenesis has been confirmed.The other type of DNA intracellular receptor cGAS plays an important role in antiviral and tumor immunity,but its role in autoimmune diseases is less studied.Cyclic GMP-AMP synthase can bind to DNA and catalyze ATP and GTP to form a circular dinucleotide cGAMP.cGAMP acts as an endogenous secondary messenger in the cytoplasm and binds to and activates the endoplasmic reticulum resident adapter protein STING.STING can recruit and activate downstream TBK1.Activated TBK1 can phosphorylate the transcription IRF3 and further synthesize IFN-I.There is insufficient understanding of the pathogenesis of SLE,and there is still a lack of better specific treatments.As IFN-I overexpression is one of the important cause for SLE,therefore,IFN-I can be a potential therapeutic target for SLE.It has been reported that the use of IFN-I antibodies can down-regulate IFN-Induced gene expression and thus alleviate SLE.In summary,inhibiting the cGAS-STING pathway and reducing the production of IFN-I are expected to become a new method for treating systemic lupus erythematosus.Aspirin(acetylsalicylic acid)has been used to treat various inflammations since the late 1890s.At present,aspirin can be used for the acetylation of many proteins,including cGAS.Acetylation of cGAS protein can reduce its DNA binding activity and reduce cGAMP production.In the autoimmune disease Aicardi-Goutieres syndrome caused by abnormal DNA degradation,the cGAS-STING-IFN pathway is abnormally activated.Studies have shown that aspirin can inhibit its activity by acetylating cGAS,significantly reducing the expression of ISGs,thus treating AGS.We look forward to further exploring the efficacy of aspirin in treating lupus mice and its underlying mechanism..ObjectiveWe aim to understanding the importance of cGAS-STING-IFN pathway in the pathogenesis of systemic lupus erythematosus and the potential efficacy of aspirin in inhibiting cGAS activity and reducing IFN-Ⅰ production in the treatment of lupus mice.MethodsSLE patients and healthy human serum were collected to stimulate THP-1 cells,and we detected the expression of cGAS protein.The supernatant of the culture medium was retained and the IFN-Ⅰ concentration was detected.Peripheral blood mononuclear cells(PBMCs)from SLE patients and healthy people were collected,and RNA extracted to detect the relative mRNA expression levels of cGAS and STING.The peripheral blood dsDNA and IFN-Ⅰ levels in SLE patients and healthy controls were also detected.In vivo,pristine-induced systemic lupus erythematosus mice were treated with normal saline or aspirin,respectively,and urine protein levels of mice,autoantibody dsDNA antibodies in serum,type Ⅰ interferon expression in serum,and histopathology of kidneys and deposition of IgG and C3.The expression of cGAS in kidney was detected by tissue immunofluorescence.ResultsThe relative mRNA expressions of cGAS and STING in PBMCs in SLE patients were significantly higher than those in healthy controls,and the amounts of dsDNA and IFN-Ⅰ in SLE patients were higher than those in healthy controls.Aspirin treatment significantly inhibited IFN-Ⅰ production in vivo and in vitro.In pristane-induced lupus mice,aspirin treatment reduced proteinuria,circulating autoantibody levels,immune complexes and cGAS expression levels in the kidneys.Renal pathological damage was significantly improved compared with the normal saline group.ConclusionAspirin treatment can inhibit the production of IFN-I and relieve the disease in lupus mice.Both in vivo and in vitro,these inhibitory effects achieved by inhibiting the cGAS-STING pathway suggest an intrinsic link between the cGAS-STING-IFN pathway and the pathogenesis of SLE,suggesting that inhibition of cGAS activity may be a potential therapeutic target for SLE,and aspirin may have a significant therapeutic for SLE.