The Expression Of Interleukin-29 In The Serum Of Rheumatoid Arthritis

Backgroungd: Rheumatoid arthritis(RA)is an inflammatory autoimmune disease that may lead to progressive joint destruction.The anti-cyclic citrullinated peptide(anti-CCP)antibody is an essential peptide for the diagnosis of RA and has a crucial role in the bone destruction in RA.Recent studies have showed that interleukin(IL)-29,a vital member of type III interferons(IFNs)family,could enhance proinflammatory cytokine production and might be involved in the joint destruction in RA.Objectives: The aims of this study was to examine the serum IL-29 levels in RA patients and investigate their associations with clinical parameters;for the first time,we examined differences in serum IL-29 levels of RA patients with and without anti-CCP antibodies and observed the changes of serum IL-29 levels before and after treatment of traditional disease modifying anti-rheumatic drugs(DMARDs :iguratimod,methotrexate,leflunomide,sulfasalazine).Methods: 68 cases of newly diagnosed treatment-naive RA and 68 healthy controls(HC)were enrolled in the present study.The patientswere treated with DMARDs and followed up for six months.Clinical parameters [including age,sex,disease duration,rest pain,Disease Activity Score 28(DAS28),morning stiffness,visual analogue score(VAS),the number of tender and swollen joints,Health Assessment Questionnaire(HAQ),C-reactive protein(CRP),erythrocyte sedimentation rate(ESR),anti-CCP antibodies,rheumatoid factor(RF)and serum platelet counts ] were performed at 0,1,3 and 6 months after treatment.Serum IL-29 levels were determined using commercial enzyme-linked immunosorbent assay(ELISA).Results:(1)The result showed that the serum IL-29 levels were higher in RA patients compared with HC(p = 0.019).(2)When RA patients were divided into two groups according to anti-CCP antibodies,the serum IL-29 levels of anti-CCP-antibodies positive RA patients were significantly higher than those in HC(p = 0.004)and anti-CCPantibodies negative RA patients(p = 0.005),while the serum IL-29 levels in anti-CCP-antibodies negative RA patients and HC are comparable(p = 0.660).(3)Correlation analysis demonstrated a significant positive correlation among serum IL-29 level,RF and anti-CCP antibodies before treatment.Furthermore,the serum IL-29 levels of anti-CCP-antibodies positive RA patients were positively correlated with HAQ,ESR,CRP,DAS28(CRP),RF and serum platelet counts at baseline.However,there was no correlation observed betweenserum IL-29 levels and the clinical parameters measured in anti-CCP-antibodies negative RA patients.(4)After treatment of DMARDs,we found that the serum IL-29 levels of patients in the anti-CCP-antibodies negative group did not change after 6 months(p >0.05),while the serum IL-29 levels of the anti-CCP-antibodies positive RA patients declined significantly(p < 0.05)after only 3 months.Further comparing parameters obtained during different treatment period,we found no correlation between the reduction of serum IL-29 levels and the reduction of disease activity in the first treatment period(0 to 1month)in anti-CCP-antibodies positive RA patients.However,the changes of the serum IL-29 levels in anti-CCP-antibodies positive RA patients are well correlated with the reductions of DAS28(CRP)and DAS28(ESR)(p < 0.05)during the treatment periods of 1 to 3 months and 3 to 6 months.No statistical significance was found in the anti-CCP-antibodies negative RA patients in every treatment period.(5)To further examine the role of IL-29 in RA,we use the American College of Rheumatology(ACR)response criteria to judge the treatment response.We have compared the serum IL-29 levels between the ACR20 positive group and the ACR20 negative group at baseline.Unfortunately,there was no significant difference between these two groups(p > 0.05).Conclusions: For the first time,we find the serum IL-29 levels of anti-CCP-antibodies positive RA patients were significantly higher thananti-CCP-antibodies negative RA patients and HC.Furthermore,the serum IL-29 levels of anti-CCP-antibodies positive RA patients have been found to correlate significantly with the parameters of disease activity and declined significantly after the treatment with DMARDs.The findings indicate that IL-29 is a potential biomarker for disease activity in anti-CCP-antibodies positive RA patients,and they will not only shed light on the pathogenesis of anti-CCP-antibodies positive RA patients,but also aid the development of new therapeutic regimens.