Abnormal IgA1 O-glycosylation in a multi-ethnic population of IgA nephropathy patients in KwaZulu-Natal, South Africa.

Abstract

Background: The pathogenesis of IgA Nephropathy (IgAN) is poorly understood globally and curative therapy currently does not exist. Variable presentation among IgAN patients globally may be indicative of various underlying pathogenic mechanisms. Pathogenetic data on IgAN in Africa is scarce to nil. The current study provides the first O-glycosylation data for IgAN in South Africa or Africa.

Methods: An enzyme-linked immunosorbent assay-type lectin binding assay was used to compare the serum IgA1 O-galactosylation in 19 IgAN patients and 20 controls. During 2007, 2009, and 2011, blood was extracted from consenting biopsy-diagnosed South African IgAN patients of African, Caucasian, Indian (predominantly) and mixed-race descent in KwaZulu Natal. The mean absorbance value corresponding to the degree of degalactosylation for the IgAN group was compared to that of the normal control group for each test. A non-parametric Wilcoxon matched-pairs test was used accordingly. The two-tailed p-value was used to assess for statistical significance between the groups. The low number of attending and consenting IgAN patients precluded IgA1 O-galactosylation analyses between race, gender, and disease stage.

Results: The average means of the experiments for the IgAN group is 0.3678 ± 0.0790 (SEM) and is statistically significantly greater than the normal control group which is 0.2969 ± 0.0586 (SEM); (p = 0.0076).

Conclusion: Thus, IgAN patients exhibited abnormal IgA1 O-glycosylation with a greater level of terminal degalactosylation of IgA1 in comparison to controls. Such a finding is consistent with other studies in Caucasian and Asian populations globally. Future specific therapeutic strategies that target the formation of abnormal glycosylation in IgA1 may be potentially beneficial in the study population.