IgA肾病中不同电荷的IgA1糖基化谱及其与培养的系膜细胞的结合特性

Glycosylation profile of differently charged IgA1 and their binding characteristics to cultured mesangial cells in IgA nephropathy.

作者信息

Leung Joseph C K, Chan Loretta Y Y, Tang Sydney C W, Tam P C, Fenn John, Lai Kar Neng

机构信息

Department of Medicine, Queen Mary Hospital, University of Hong Kong, Hong Kong, SAR, China.

出版信息

Nephron Exp Nephrol. 2007;107(3):e107-18. doi: 10.1159/000109980. Epub 2007 Oct 23.

DOI:10.1159/000109980

PMID:17957128

Abstract

BACKGROUND

IgA nephropathy (IgAN) is characterized by mesangial deposition of polymeric IgA1 (pIgA1), yet the pathogeneic mechanism remains unresolved. In the present study, we examined the glycosylation profile of differently charged IgA1 from IgAN patients. The binding characteristics of these IgA1 fractions to cultured human mesangial cells (HMC) and hepatoma cell lines (HepG2) were studied.

METHODS

Differently charged IgA1 were isolated by ion exchange chromatography. The glycosylation profile in the carbohydrate moieties of these differently charged IgA1 was analyzed by galactose (Gal)-, galactose-acetylgalactosamine (Gal-GalNAc)-, or sialic acid-specific enzyme-linked lectin binding assays (ELLA). The binding characteristic of these IgA1 to HMC was examined by flow cytometry and competitive binding assay.

RESULTS

Anionic pIgA from IgAN patients showed less reactivity in (Gal)- and (Gal-GalNAc)-specific ELLA (p < 0.01). There was higher reactivity for anionic pIgA1 in alpha(2,6)-linked sialic acid-specific ELLA (p < 0.01). Anionic pIgA1 from IgAN patients exhibited increased binding to cultured HMC and the binding was significantly reduced after neuraminidase treatment (p < 0.05). In contrast, anionic pIgA1 from IgAN patients bound less to cultured HepG2 cells and the binding was enhanced following neuraminidase treatment (p < 0.05).

CONCLUSIONS

We demonstrated an unusual glycosylation and sialylation pattern of anionic pIgA1 in IgAN which may have an important effect on its pathogenesis.

摘要

背景

IgA 肾病（IgAN）的特征是聚合 IgA1（pIgA1）在系膜沉积，但其致病机制仍未明确。在本研究中，我们检测了 IgAN 患者不同电荷的 IgA1 的糖基化谱。研究了这些 IgA1 组分与培养的人系膜细胞（HMC）和肝癌细胞系（HepG2）的结合特性。

方法

通过离子交换色谱法分离不同电荷的 IgA1。通过半乳糖（Gal）、半乳糖 - N - 乙酰半乳糖胺（Gal - GalNAc）或唾液酸特异性酶联凝集素结合试验（ELLA）分析这些不同电荷的 IgA1 碳水化合物部分的糖基化谱。通过流式细胞术和竞争性结合试验检测这些 IgA1 与 HMC 的结合特性。

结果

IgAN 患者的阴离子 pIgA 在 Gal - 和 Gal - GalNAc - 特异性 ELLA 中反应性较低（p < 0.01）。阴离子 pIgA1 在α(2,6) - 连接的唾液酸特异性 ELLA 中反应性较高（p < 0.01）。IgAN 患者的阴离子 pIgA1 与培养的 HMC 的结合增加，神经氨酸酶处理后结合显著降低（p < 0.05）。相反，IgAN 患者的阴离子 pIgA1 与培养的 HepG2 细胞的结合较少，神经氨酸酶处理后结合增强（p < 0.05）。