Résumé
Objective To explore the expression and clinical significance of soluble Axl and Tyro3 receptor tyrosine kinase in systemic lupus erythematosus (SLE).Methods Sandwich enzyme linked immunosorbent assay (ELISA) was used to detect sAxlTK and sTyro3TK in the serum of 140 SLE patients,150 disease controls and 100 healthy controls (HC).The relationships between the serum levels of sAxlTK/sTyro3TK and clinical manifestations,laboratory parameters,disease activity were analyzed in SLE patients.Analysis of variance,Dunnett's t-test,chi-square test and spearman's test were used for statistical analysis.Results The concentrations of sAxlTK [(56±18) ng/ml] and sTyro3TK [(3.9±1.6) ng/ml] were both elevated in serum of SLE patients,which were significantly higher than disease controls [sAxlTK:(41±17) ng/ml;sTyro3TK:(2.6± 1.2) ng/ml] and healthy controls [sAxlTK:(37±10) ng/ml;sTyro3TK:(2.1±0.7) ng/ml].The SLE sAxlTK levels were negatively correlated with lymphocyte count (r=-0.266,P=0.002),hemoglobin (r=-0.480,P＜0.01),platelet count (r=-0.374,P＜0.01),albumin (r=-0.465,P＜0.01),estimated glomerular filtration rate (eGFR,r=-0.230,P=0.006),complement C3 (r=-0.399,P＜0.01) and complement C4 (r=-0.374,P＜0.01).However,the levels of sAxlTK in SLE patients were positively correlated with D-dimer (r=0.371,P＜0.01),creatinine (r=0.278,P＜0.01),24-hour urinary protein quantification (r=0.383,P＜0.01),erythrocyte sedimentation rate (r=0.422,P＜0.01),titre of anti-nuclear antibodies (r=0.271,P=0.002),anti-dsDNA antibody (r=0.299,P＜0.01),anti-nucleosome antibody (r=0.263,P=0.013) and anti-cardiolipin antibody (r=0.309,P＜0.01).In addition,the levels of serum sAxlTK in SLE patients showed positive correlation with the scores of SLEDAI (r=0.307,P＜0.01).Comparisons of sAxlTK levels between patients with high and low disease activity demonstrated a higher level of sAxlTK in the former [(64±17) ng/ml vs (52±16) ng/ml;t=-3.939,P＜0.01].Conclusion The levels of sAxlTK and sTyro3TK are elevated in the serum of SLE patients.The concentration of sAxlTK is correlated with autoantibodies production,hematological and renal involvement in SLE,which may be a serolgical marker for disease activity.