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Abstract: Aberrant glycosylation of serum IgA1 was considered as an initial event and involvement in the pathogenesis of IgAN. We previously demonstrated that aberrant glycosylation of serum IgA1 was associated with pathologic phenotype of IgAN. The present study is to investigate if abnormal sialylation of IgA1 affects renal survival of IgAN. 127 patients with biopsy-proven IgAN were enrolled and followed up to 8 years. Seventy-nine healthy and 75 patients with non-IgAN renal diseases were selected as controls. Alpha 2, 6 sialic acid (SA) of serum IgA1 was measured by sandwich-ELISA. Renal survival rate was estimated by Kaplan–Meier method. Alpha 2, 6 SA level in patients with IgAN was lower than that in healthy controls (0.92±0.14 vs. 0.98±0.12, P =0.001) and non-IgAN glomerulonephritis (0.92±0.14 vs. 1.00±0.18, n =53, P =0.001). Patients with IgAN in Low SA Group were no significant differences compared with patients in Normal SA Group in age, gender, hypertension, serum creatinine, and excretion of proteinuria. Renal cumulative survival rate was 53.3% in patients in Low SA Group and 83.5% in Normal SA Group (P =0.0008). The lower the alpha 2, 6 SA level of serum IgA1 in patients with IgAN was, the worse their renal survival rate was. Although patients in Low SA Group had worse renal function evaluated by eGFR, there was no significant difference in various CKD stages in non-IgAN renal function controls (n =42, P =0.352). Alpha 2, 6 SA level of serum IgA1 was associated with the prognosis of patients with IgAN and could serve as a predictor of poor prognosis in IgAN. [Copyright &y& Elsevier]

Abstract: Anti-GBM disease is a rare autoimmune condition characterized by autoantibodies targeting the α3 chain non-collagen 1 domain of type IV collagen (α3(IV)NC1). Recently, we isolated IgG reacting with α3(IV)NC1 from normal healthy human sera. The current study examined the antigen and epitope specificity of these natural autoantibodies (NAA) using recombinant human α1, 3, 5(IV)NC1 and three constructs expressing, previously defined epitope regions designated EA, EB and S2, in the α1(IV)NC1 background. The NAA preparations reacted with recombinant human α3(IV)NC1 to the same extent as with purified bovine α(IV)NC1, but not with recombinant human α1 and α5(IV)NC1. NAA preparations recognized the three chimeric proteins (EA, EB and S2) yielding similar absorbance values. We conclude that anti-GBM NAA recognize the same major epitopes as anti-GBM antibodies from patients with Goodpasture''s disease. [Copyright &y& Elsevier]