Discussion Activation And Pathogenic Role Of The Three Complement Pathways In IgA Nephropathy

Objective:To investigate the role of the three complement pathways activation in the pathogenesis of IgA nephropathy(IgAN).Methods:30patients with IgAN were sequentially enrolled as disease group,8patients with lupus nephritis(LN) as positive disease control group and30healthy adults were as normal control group. Characteristic markers of the three complement pathways include C3a,C5a and soluble membrane attack complex sC5b-9,C1q (complement classical pathway), L-ficolin (FCN2)(complement lectin pathway), C4d(product of both complement classical and lectin pathway) and complement factor Bb(complement alternative pathway) were detected by commercial Elisa kits. Urine samples were collected to detect the level of C1q. According to renal pathology, define IgAN patients with Lees Ⅰ～Ⅲ as one group, and IgAN patients with Lees IV-V group. Analysis the correlation between complement activation and the clinical items.Results:Complement activation was different among the three groups.The serum level of C3a,C5a and sC5b-9between IgAN and LN group had no difference,serum level were both higher in IgAN and LN group than that in normal control group (P＜0.05).The C1q levels in serum and urine of IgAN group were both significantly higher than that in normal control group(P< 0.05), the urine level of C1q in IgAN group was significantly lower than that in LN group(P＜0.05).The serum level of FCN2was higher in IgAN and LN group(P＜0.05). There was no statistical difference between these two groups. The serum level of C4d was statistically different among the three groups(P＜0.05).Serum Bb,C3a were positively correlated with the serum creatinine. Patients with IgAN with more severe pathological damage showed lower serum and urine C1q levels. Serum FCN2were negatively correlated with the urine red blood cell counts. The urine C1q is positively correlated with serum creatinine.Conclusion:The complement activation of the serum alternative pathway and lectin pathway were both involved in the pathogenesis of IgAN. The complement activation of classical pathway might involved in the pathogenesis of IgAN.