Clinical Significance Of The Elevated Serum IL-33 Levels In Patients With Systemic Lupus Erythematosus

Objective To measure the serum levels of interleukin (IL)-33 in systemic lupus erythematosus (SLE) patients and analyze the correlation between serum levels of IL-33 with disease activity as well as clinical features.Methods From March 2014 to April 2015,a total of 70 patients with SLE (including 50 treatment-naive active and 20 inactive) and 30 normal controls were recruited from the Division of Rheumatology and Immunology, The First Affiliated Hospital of Guangxi Medical University. All patients with SLE recruited into the study met the 2009 revised Systemic Lupus International Coll-aborating Clinics SLE criteria. Serum levels of IL-33 were measured by enzyme linked immunosorbent assay (ELISA) in SLE patients and 30 healthy controls. Physical examination and laboratory investigations including blood routine, albumin, C reactive protein(CRP), erythrocyte sedimentation rate(ESR), complements, immunoglobulin G(IgG), immunoglobulin A(IgA), immunoglob-ulin M(IgM) and autoantibodies were performed at study visits.Results1.Serum IL-33 level was significantly higher in patients with SLE(987.0±336.2 pg/ml)compared with healthy controls(777.5±238.8 pg/ml) (P<0.05); The serum levels of IL-33 were significantly higher in treatment-naive active SLE patients(1055.9±356.7 pg/ml) compared with inactive patients(814.6±196.9 pg/ml)(P<0.05); Serum IL-33 between inactive SLE patients and controls was not statistically significant (P>0.05).2.1n SLE patients, serum DL-33 level was significantly higher in patients with pulmonary arterial hypertension(PAH)(1496.1±236.9 pg/ml) compared with patients without PAH(964.1±322.8 pg/ml)(P<0.05),there were no statistically significant associations between the levels of IL-33 and other clinical parameters(P>0.05).3.In active SLE patients, serum IL-33 level was significantly higher in patients with positive anti-SSB antibodies(1315.4±306.7 pg/ml) compared with patients without positive anti-SSB antibodies(998.9±344.3 pg/ml) (P<0.05), serum IL-33 level was significantly lower in patients with positive anti-ribosomal P protein antibodies (897.5±291.5 pg/ml) compared with patients without positive anti-ribosomal P protein antibodies(1152.9±362.2 pg/ml) (P<0.05), there were no statistically significant associations between the levels of IL-33 and other autoantibodies(P>0.05).4.Serum IL-33 was positively correlated with systemic lupus erythematosus disease activity index(SLEDAI) score(r=0.375, P<0.05), The serum levels of IL-33 were negatively correlated with C4(r=-0.294, P>0.05),hemoglobin (r=-0.224, P<0.05) and albumin(r=-0.331, P<0.05). There were no statistically correlations between serum levels of IL-33 and complements 3,anti-dsDNA antibodies,24 hour urinary protein, CRP, ESR, IgG, IgA,IgM (P>0.05).Conclusions1. Serum IL-33 level in patients with SLE was elevated.2. The serum levels of IL-33 were significantly higher in treatment -naive active SLE patients compared with inactive patients and were correlated with disease activity. Serum IL-33 level was positively correlated with SLEDAI score, and was negatively correlated with C4, hemoglobin and albumin in SLE patients.3. The levels of IL-33 were associated with anti-SSB antibodies and anti-ribosomal P protein antibodies in treatment-naive active SLE patients.