Serum Levels Of Interleukin-34 And Clinical Correlation In Patients With Primary Sj(?)gren's Syndrome

Objectives:Primary Sj???gren's syndrome?pSS?is a chronic inflammmatory autoimmune disease characterized by lymphocytic infiltration of exocrine glands such as salivary glands and lacrimal glands,hyperactivity of B cells,and immune inflammation involving a variety of cytokines.Clinically,it is mainly manifested as dry eyes or dry,while systemic damage due to involvement of other exocrine glands and extraglandular organs may also occur.Interleukin?IL?-34 is an important pro-inflammatory cytokine.As an alternative ligand of colony-stimulating factor-1 receptor?CSF-1R?,it plays a key role in regulating the survival,proliferation and differentiation of monocytes,macrophages and osteoclasts.A growing body of research suggests that IL-34 is associated with disease chronicity,severity and progression.It has been shown that IL-34 mRNA is upregulated in the inflamed salivary glands of pSS patients and is correlated with the expansion of pro-inflammatory CD14^brightCD16⁺monocytes.To provide more experimental basis for the role of IL-34 in pSS,the present study determined the levels of serum IL-34 in patients with pSS and evaluated the cytokine's clinical association with the disease.Methods:Sixty-six patients with pSS from the Department of Rheumatology and Immunology,the First Affiliated Hospital of China Medical University,from November2017 to May 2018,were recruited as the experimental group.Thirty-two healthy volunteers from the physical examination center were healthy controls?HCs?.Serum samples were obtained from all subjects and the IL-34 levels were measured by the double antibody sandwich enzyme-linked immunosorbent assay?ELISA?.To analyze the correlations between serum IL-34 levels and autoantibodies,inflammatory indicators,immune markers,and the involvement of the blood system as well as the lung,the clinical parameters,including the anti-SSA antibody,anti-SSB antibody,rheumatoid factor?RF?,erythrocyte sedimentation rate?ESR?,C-reactive protein?CRP?,complement?C?3,C4,immunoglobulin?Ig?G,IgA,IgM,g-globulin?g-G?,white blood cell?WBC?counts,platelet?PLT?counts,hemoglobin?Hb?concentration,and whether combined with interstitial lung disease?ILD?,were collected simultaneously.Statistical data was presented as mean±standard deviation?mean±S.D.?,and two-sample t-test was applied for comparison between two groups.Pearson's correlation coefficient was used to assess correlations between serum IL-34 levels and above laboratory parameters.Results:The serum IL-34 levels in patients with pSS group were significantly elevated compared with HCs?P=0.0054?.Patients with anti-SSA antibody positive showed higher serum IL-34 levels than those negative?P=0.0034?,and similar finding was observed between anti-SSB-antibody positive and negative groups?P=0.0330?.What's more,the serum IL-34 levels in pSS patients were positively correlated with RF,IgG,and?-G?r=0.526,P<0.0001;r=0.377,P=0.0018;r=0.346,P=0.0063,respectively?,but not with IgA,IgM,C3,C4,ESR or CRP?P>0.05?.In addition,in comparison of pSS subgroups with and without leucopenia,thrombocytopenia,anemia or ILD,there was no significant difference of serum IL-34 levels?P>0.05?.Conclusions:The serum levels of IL-34 in patients with pSS were related to the levels of antibodies.IL-34 in serum may serve as a potential serological marker and therapeutic target for pSS.