Study On The Relationship Between Serum Lipoprotein-Associated Phospholipase A2 Activity And Systemic Lupus Erythematosus

Background:systemic lupus erythematosus(SLE)is a common rheumatic disease,involving multiple systems,is prevalent in young women,and the basic pathological changes of SLE are vascular anomalies and inflammation.Lipoprotein-associated phospholipase A2(LP-PLA2)is a member of the phospholipase A2 superfamily,and LP-PLA2 mainly exerts pro-inflammatory effects which is clinically used to assess the occurrence of cardiovascular events.Owing SLE is essentially a process of inflammation,LP-PLA2 is likely to be involved in the progression of SLE.Objective:To study role the serum LP-PLA2 plays in SLE.Methods:(1)According to the document WS/T 420-2013 formulated by National Health and Family Planning Commission,we conducted the Performance verification of LP-PLA2 test kit.(2)A total of 154 patients diagnosed to have SLE from June 2016 to February 2017 in Chinese PLA general hospital(China)were enrolled,and 55 age-,sex-,and body mass index-matched healthy controls were included,and we detect serum Lp-PLA2 activity and biochemical index,collecting clinical data.The difference between the experimental group and the control group was compared.The correlations between LP-PLA2 and SLE patients’complications,autoantibodies and laboratory indexes were analyzed.(3)SLE patients were divided into SLE group(without lupus nephritis patients)and LN group(lupus nephritis)by pathological results,detecting LP-PLA2 activity and cystatin C(CysC)of two groups.Using Logistic regression and ROC curve to assess the power of test combined detection of LP-PLA2 and CysC played for LN in SLE patients.Results:(1)The performance evaluation of LP-PLA2 Kit:In terms of precision,intra-and inter-batch offset of low value serum were 0.88%and 1.1%,respectively,both intra-and inter-batch offset of high value serum were 1.3%,meeting the validation ’criteria 5%for intra-batch offset and 10%for inter-batch offset.In terms of linearity,the linear correlation coefficient of the reagent is 0.9991,which is higher than the verification standard of 0.99.The 95%confidence interval of serum LP-PLA2 activity levels in healthy subjects were 83-299 U/L.(2)Compared with the control group,the multi-system indexes of the study group were abnormal,ALB and TP were decreased,the blood lipid index was disorder(LDL,LP(a)and TG increased),the renal function index CysC was increased,and the antioxidant capacity was decreased(SOD decreased).The serum LP-PLA2 activity level in the experimental group was 221 ±56 U/L,which was higher than the 160±37 U/L in the control group(P<0.OO1).The LP-PLA2 activity of SLE patients with lupus nephritis,anemia and coagulation activation was increased(P<0.05),and when using 24-hour urinary protein,hemoglobin concentration and D dimer as a reflection of the severity of nephritis,anemia and coagulation in SLE patients.LP-PLA2 is positively correlated with 24 hours urinary protein(rho=0.472,P<0.001)and D dimer(rho=0.387,P<0.001),negatively correlated with hemoglobin concentration(rho=-0.312,P<0.001).In the Spearman analysis of the correlation between serum LP-PLA2 levels and other indicators,we found complement markers(C3,C4),HDL,TP and ALB were negatively correlated with LP-PLA2(P<0.05),and serum lipids[CHO,LDL,LP(a)and TG],renal function(Cre,CysC,UA and BUN),GLU,ESR and SLEDAI-2K positively correlated with LP-PLA2(P<0.05).In binary logistic regression analysis,serum LP-PLA2 activity was an independent risk factor for active SLE(OR 1.049;95%CI:1.026-1.074,P<0.001).(3)The AUC areas for LN assessment of patients with SLE using LP-PLA2 and CysC alone were 0.688(95%confidence interval 0.604-0.771;P<0.001)and 0.757(95%confidence interval 0.682-0.832,P<0.001),the combined AUC area of the two indicators was 0.841(95%confidence interval:0.778-0.905;P<0.001).Conclusions:(1)The test results of the LP-PLA2 kit met the standard of WS/T 420-2013,as well as the scope of the manufacturer’s statement,and it could be used for the detection of clinical samples.At the same time,when using the kit,the 95%confidence interval of LP-PLA2 activity in healthy subjects were 83-299 U/L.(2)LP-PLA2 is related to the degree of disease activity and the severity of complications in SLE patients.LP-PLA2 may be involved in the development of SLE disease,and which provide a new insight for the mechanism of SLE.(3)In the risk assessment of LN in SLE patients,diagnostic efficiency of combined detection of LP-PLA2 and CysC was significantly higher than that of each indicator alone,which has a certain clinical application value.