| Objectives: Rheumatoid arthritis(Rheumatoid arthritis,RA)is a chronic,systemic autoimmune disease with erosive,symmetrical polyarthritis as the main clinical symptoms.The exact pathogenesis is unknown.Several cytokines are now known to be involved in the pathogenesis of RA.Meteorin-like(Metrnl),also known as nickel pattern protein,is a newly discovered adipokine.At present,Metrnl is found to regulate its metabolism and participate in various functions such as inflammation and immune response.In autoimmune diseases,Metrnl levels was increased in psoriatic arthritis and RA.However,no search report on the expression level in RA peripheral blood.The purpose of this study is to investigate the level of Metrnl in the serum of RA patients,and its relationship with clinical indicators,disease activity and its effect on cytokines secreted by peripheral blood mononuclear cells(PBMC),so as to provide new ideas for further research on the mechanism of Metrnl and the diagnosis and treatment of RAMethods: 1.A total of 159 RA patients with RA and 28 patients with osteoarthritis(OA)who visited the inpatient department and outpatient department of Rheumatology and Immunology Department of the First Affiliated Hospital of China Medical University from December 2018 to December 2020 were recruited as the research objects,and 50 healthy volunteers from physical examination centers were recruited.Collected 5 ml of venous blood from every volunteers.Use enzyme-linked immunosorbent assay,(ELISA)to detect the Metrnl level in the serum.And simultaneously collect the laboratory indicators of RA patients,Including anti-cyclic peptide containing citrulline(Anti-CCP),rheumatoid factor(RF),immunoglobulin(Ig)G,Ig A,Ig M,erythrocyte sedimentation rate(ESR),C-reactive protein(CRP),blood index and collected swollen joint count(SJC),tender joint count(TJC).Disease activity of RA patients adopts the disease activity score28(DAS 28)to analyze the relationship between serum Metrnl level of RA patients and inflammatory index,immunoglobulin,and disease activity.Patients were also evaluated for organ involvement,and high resolution CT(HRCT)was used to assess RA patients for interstitial lung disease(ILD).Recruit 12 RA patients,peripheral blood of RA patients were collected.PBMC was extracted and stimulated with different concentrations of Metrnl(0,50,100,200 ng/ml)for72 hours,and the supernatant was collected after centrifugation.The secretion levels of inflammatory factor tumour necrosis factor-α(TNF-α),interleukin(IL)-6,IL-17 A were detected by ELISA.Results:1.The Metrnl levels were significantly higher in RA patients than in the OA and HC groups(P =0.040,P =0.029),with no difference in Metrnl levels between the OA and HC groups.There was no difference in Metrnl levels between the medicated and unmedicated patients.There was no difference in Metrnl levels in patients with long and short disease duration.2.Metrnl and RA disease activity correlation indexes CRP(r=0.2684,P=0.0015),DAS28(r=0.2413,P=0.0051),SJC(r=0.2399,P=0.0052)and TJC(r =0.0922,P= 0.0261)were positively correlated.3.The Metrnl level was positively correlated with RF(r=0.2909,P=0.0006),but showed no correlation with anti-CCP(p=0.093).At the same time,the Metrnl level of RF-positive patients was significantly higher than that of RF-negative patients(p=0.0177),and that of anti-CCP positive patients was significantly higher than that of anti-CCP negative patients(p=0.0038).4.There was no correlation between Metrnl levels and complement C3,C4 and immunoglobulin Ig M,Ig G,Ig A.5.Metrnl has no correlation between WBC,HGB,and PLT.There was no correlation between serum Metrnl levels and the presence of pulmonary interstitial fibrosis.6.The level of Metrnl tended to be negatively correlated with the inflammatory factors IL-6 and TNF-α but did not achieve statistical significance.7.The levels of TNF-α and IL-6 were reduced with different concentrations of Metrnl(0,50,100,100,200 ng/ml)in a concentration-dependent manner.However,the levels of IL-17 A did not change significantly.Conclusions:The serum Metrnl level in RA patients was significantly higher than that in the control group,and was correlated with the disease activity of RA.Metrnl inhibited the secretion of TNF-α and IL-6 in the PBMC of RA patients,suggesting that Metrnl may have a negative regulatory effect on inflammation and play a protective role in RA patients. |
