| Background:Rheumatoid arthritis(RA)is an autoimmune-mediated chronic inflammatory joint disease.The incidence of rheumatoid arthritis(RA)has been reported to be correlated with a disorder of immunregulation.Rheumatoid arthritis fibroblast-like synoviocytes(RA-FLSs)play an important role in regulating the local immune microenvironment.However,However the potential mechanism of RA-FLS in regulating the immune response is not clearly understood.During the progression of RA,inflammatory microenvironment lead to the damage of blood capillary,and local blood supply was deficiency,which can form a hypoxic microenvironment.The expression of hypoxia inducible factor 1 alpha(HIF-1α)was upregulated by hypoxic microenvironment in synovial tissues of damaged joint,then related pathway of inflammation,angiogenesis,invasion and proliferation was activited,which lead to the progression of RA.Hypoxic microenvironment lead to the stress response of cells in the damaged tissue.It has been reported that hypoxic stress could effectively induce the incidence of autophagy in many cell.Autophagy is the highly conserved and destructive mechanism of the cell that disassembles unnecessary or dysfunctional components dependent on lysosome.The autophagosome eventually fuses with lysosomes and the contents are degraded and recycled.Autophagy is important for the maintainance of cellular homeostasis,which is an important mechanism of self-protection when cells under hyxia microenviroment.And many studies have indicated that autophagy plays a key role in innate immunity and adaptive immunity.In this research,we investigate the role of hypoxia microenviroment in RA-FLS,and the effect of autophagy on the immune regulation in RA-FLS.IL-6 is a 22–29 KD glycoprotein,which is produced by a variety of cells such as B cells,T cells and fibroblasts.The IL-6 receptor has two chains,IL-6-specific receptor(IL-6Ra)and a signal transducer,gp130.IL-6 binds to receptor and subsequently induces the activation of downstream signalling events.High level of IL-6 has been found in the blood and SF of many RA patients.RA patients such as elevation in C-reactive protein(CRP)levels,anemia and fatigue are thought to be mediated by IL-6.And IL-6 is related to the inflammation and tissue damage of RA.Therefore,IL-6 is considered as a target in the treatment of RA.However,the role of IL-6 in immune regulation of RA-FLS is not clear.In our present study,we found that HIF-1α was upregulated in tissue of RA rat.And then we aim to observe the effect of RA-FLS immune regulating function influenced by hypoxic microenvironment and further explore the potential mechanism.Methods: In present study,animal model of rheumatoid arthritis was constructed,and hypoxia condition was observed by examining the marker of hypoxia.RA-FLSs were isolated from rheumatoid arthritis tissues of animal model,then the effect of RA-FLSs on the immune regulation was detected through cultivated with lymphocytes by CCK-8 assay.Then we observed the level of autophagy in RA-FLSs by immunofluorescence and western blot,and the change of autophagy was detected when cells was treated by hypoxia.Next,the effect of autophay on immune regulation was confirmed by using autophay inhibitor.Futhermore,IL-6 level was detected by ELISA in RA-FLS,and IL-6 sh RNA was performed to inhibite the expression of IL-6,and then the role of IL-6 in immune regulation of RA-FLS was demonstrated by cultivated with lymphocytes.Results:1.The expression of HIF-1α was significantly up-regulated in rheumatoid arthritis tissue,which indicated that the hypoxia condition was presented in the microenvironment.2.RA-FLSs promoted the proliferation and suppresed the apoptosis of lymphocytes,and the consistent result was observed when normal FLS was treated by hypoxia.3.The level of autophagy was increased in RA-FLSs compared with control group.And we found that autophagy inhibitiors could effectively inhibit the immune activation function of RA-FLSs.4.The expression of IL-6 was up-regulated not only in RA-FLSs but also in the fibroblasts that treated with hypoxia condition.And immune activation function of RA-FLSs was inhibited by IL-6 sh RNA.Conclusion: The results we demonstrated above indicated that the hypoxia microenvironment could effectively induce the incidence of autophagy and then lead to the immune activation function of RA-FLSs medicated by IL-6.The results in this study have demonstrated the correlation of chronic inflammation and hypoxia microenvironment in RA,and the mechanism of hypoxia induced the progression of RA.The we found that autophagy play a key role in the immune regulation in RA-FLS,which indicated that autophagy-related gene might be the target of RA treatment.Beside that,the immune activation function of RA-FLSs was medicated by IL-6. |
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