MiR-146a Suppresses Immuno-inflammatory Response In Rheumatoid Arthritis

Rheumatoid arthritis(RA)is a chronic immune system disease.The disability rate of RA is high,which seriously affect the quality of patients life.So far,the pathogenesis of RA is still unclear.Micro-RNAs(miRNA)are short non-coding RNAs involved in many autoimmune disease processes.miR-146 a is expressed at higher levels in synovial fibroblasts and synovial tissue,as well as in peripheral blood mononuclear cells of RA patients.miR-146 could be used for the early diagnosis of RA.Inhibition of NF-?B signaling pathway can significantly reduce the expression of inflammatory factors.Activation of NF-?B plays a key role in the development of RA.NF-?B activation can be detected in cultured synovial fibroblasts and synovial tissue from RA patients,and animal models of inflammatory arthritis also demonstrate the active role of NF-?B in the development and progression of RA.The time course of NF-?B activation appears to precede the onset of disease,and blockade of NF-?B by different means decreases disease severity.miR-146 a may inhibit osteoclastogenesis and the administration of double-stranded miR-146 a could prevent joint destruction in a collagen-induced arthritis(CIA)mouse model.However,the role of miR-146a-NF-?B feedback loop in RA pathogenesis or its potential as a therapeutic target remains unclear and this will require identification in vivo.miR-146 have two clusters miR-146a?miR-146 b with 91% homology in human but only miR-146 a in mouse,the mechanism of miR-155 regulating RA has been revealed.Therefore,We hypothesized that miR-146a-NF-?B feedback loop regulates inflammation in RA and serves as a novel target for RA therapy.We will tightly test this hypothesis in three specific aims.First,we detected the expression level of miR-146a?miR-146 b and miR-155 in RApatients.In the study,the expression levels of miR-146a?miR-146 b and miR-155 in plasma,PBMC and joint fluid of RA patients were detected by RT-PCR,and the correlation of RA symptoms was analyzed.The correlation with miR-146a?miR-146 b and miR-155 was used to evaluate the feasibility of miR-146a?miR-146 b and miR-155 for the diagnosis of RA.Then,we study the miR-146 a associated with susceptibility to induction of CIA,The miR-146 a knockout(KO)and wild-type(WT)C57BL/6 mice will be immunized by a chicken type II collagen(CII).The role of miR-146 a during induction of CIA will be determined by an arthritis index of CIA in the treated mice.At last,we study the role of miR-146a-NF-?B feedback loop in CIA-related inflammation.The CIA-related inflammation will be determined by immunological and pathological analyses and compared between miR-146 a KO and WT mice.We will definitively determine the functional role of miR-146a-NF-?B feedback loop during CIA development.Our study found that:(1)miR-146 a,miR-146 b,miR-155 and RA are closely related,it is useful for applying to RA diagnostic studies.The expression level of miR-146 a in synovial fluid is related to the ESR and can be used as a potential indicator of RA disease activity.(2)miR-146 a KO mice are more susceptible to CIA,it took shorter onset,and the arthritis index is significantly higher than in CIA mice.The expression levels of TNF-? and IL-6 were aslo higher in miR-146 a KO mice.(3)The loss of miR-146 a during CIA mouse induction more expression of IRAK1 and promotes the increase of Tfh,Treg,GL7+B,and promotes the accumulation of antibodies and the occurrence of inflammation,The inflammatory response of KO mice was stronger than that of CIA mice.Finally,it was concluded that miR-146 is abnormally highly expressed in RA patients,miR-146 a KO mice are more more susceptible to CIA with higher arthritis index,and high expression of inflammatory factors.IRAK1 was significantly higher in KO animal model than in normal CIA mice,and there was no significant difference in the expression of TRAF6,indicating that miR-146 a inhibited IRAK1 in CIA animal model.