Defective immunoglobulin A (IgA) glycosylation and IgA deposits in patients with IgA nephropathy. 2013

Ragnhildur Kolka, and Helgi Valdimarsson, and Magnus Bodvarsson, and Sverrir Hardarson, and Thorbjorn Jonsson
Department of Immunology, Landspitali University Hospital, Reykjavik, Iceland.

Defective glycosylation and immune complex (IC) formation may be of primary importance in immunoglobulin A nephropathy (IgAN) pathogenesis. The aim of this study was to determine whether defective IgA1 glycosylation might support renal deposition of IgA and disease activity. IgA was isolated from the serum of 44 IgAN patients and 46 controls and glycosylation analysed by ELISA using glycan-specific lectins. IgA was measured by immunodiffusion and immune complexes by ELISA. IgA subclasses in IC deposits in kidney glomeruli were identified by immunohistochemical methods. A significant increase in N-acetylgalactosamine (GalNAc) in terminal position (p = 0.02) observed in some of the IgAN patients, became more pronounced when sialic acid was removed from IgA1, indicating enhanced expression of α-2,6-sialyltransferase in patients compared with controls (p < 0.0001). Patients with defective galactosylation had lower serum IgA than other IgAN patients (p = 0.003). IgAN patients with both IgA1 and IgA2 glomerular deposits (21.7%) had increased GalNAc in terminal position (p = 0.003). Taken together, our results show that increased IgA glycosylation in IgAN associates with low levels of IgA, concomitant IgA1 and IgA2 glomerular deposits and poor clinical outcome.

UI MeSH Term Description Entries
D007070 Immunoglobulin A Represents 15-20% of the human serum immunoglobulins, mostly as the 4-chain polymer in humans or dimer in other mammals. Secretory IgA (IMMUNOGLOBULIN A, SECRETORY) is the main immunoglobulin in secretions. IgA,IgA Antibody,IgA1,IgA2,Antibody, IgA
D007678 Kidney Glomerulus A cluster of convoluted capillaries beginning at each nephric tubule in the kidney and held together by connective tissue. Glomerulus, Kidney
D008297 Male Males
D008875 Middle Aged An adult aged 45 - 64 years. Middle Age
D005260 Female Females
D005922 Glomerulonephritis, IGA A chronic form of glomerulonephritis characterized by deposits of predominantly IMMUNOGLOBULIN A in the mesangial area (GLOMERULAR MESANGIUM). Deposits of COMPLEMENT C3 and IMMUNOGLOBULIN G are also often found. Clinical features may progress from asymptomatic HEMATURIA to END-STAGE KIDNEY DISEASE. Berger Disease,Immunoglobulin A Nephropathy,Nephropathy, IGA,Berger's Disease,IGA Glomerulonephritis,IGA Nephropathy,Iga Nephropathy 1,Nephritis, IGA Type,Bergers Disease,Glomerulonephritides, IGA,IGA Type Nephritis,Nephropathy 1, Iga,Nephropathy, Immunoglobulin A
D006031 Glycosylation The synthetic chemistry reaction or enzymatic reaction of adding carbohydrate or glycosyl groups. GLYCOSYLTRANSFERASES carry out the enzymatic glycosylation reactions. The spontaneous, non-enzymatic attachment of reducing sugars to free amino groups in proteins, lipids, or nucleic acids is called GLYCATION (see MAILLARD REACTION). Protein Glycosylation,Glycosylation, Protein
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000094802 beta-D-Galactoside alpha 2-6-Sialyltransferase Sialyltransferases that catalyze the transfer of N-ACETYLNEURAMINIC ACID from CYTIDINE MONOPHOSPHATE N-ACETYLNEURAMINIC ACID to the 6-OH of the GALACTOSE residue of N-GLYCANS. CMP-Acetylneuraminate Galactoside (alpha 2-6)-Sialyltransferase,CMP-N-Acetylneuraminate-Galactosylglycoprotein Sialyltransferase ST6GAL,CMP-N-Acetylneuraminate-beta-Galactoside alpha-2,6-Sialyltransferase,CMP-N-Acetylneuraminic Acid-Lactose Sialytransferase,CMP-NeuAc-Galactoside (alpha 2-6)-Sialyltransferase,CMP-Sialic Acid-N-Acetyllactosaminide alpha (2-6)-Sialyltransferase,Gal-1-4-GlcNAc alpha(2-6)-Sialyltransferase,alpha 2-6-Sialyltransferase,alpha2,6(N) Sialyltransferase,alpha6-Sialyltransferase,beta-D-Galactoside alpha-2-6-Sialyltransferase,beta-Galactoside alpha2,6-Sialyltransferase,beta-Galactosyl(1-4)N-Acetylglucosaminide alpha(2-6)-Sialyltransferase,Gal-GlcNAc(2-6)-sialyltransferase,SIAT-1,ST6(N),ST6Gal I,ST6Gal-1,2-6-Sialyltransferase, alpha,2-6-Sialyltransferase, beta-D-Galactoside alpha,Acid-Lactose Sialytransferase, CMP-N-Acetylneuraminic,CMP N Acetylneuraminate Galactosylglycoprotein Sialyltransferase ST6GAL,CMP N Acetylneuraminate beta Galactoside alpha 2,6 Sialyltransferase,CMP N Acetylneuraminic Acid Lactose Sialytransferase,SIAT 1,ST6GAL, CMP-N-Acetylneuraminate-Galactosylglycoprotein Sialyltransferase,ST6Gal 1,Sialyltransferase ST6GAL, CMP-N-Acetylneuraminate-Galactosylglycoprotein,Sialytransferase, CMP-N-Acetylneuraminic Acid-Lactose,alpha 2 6 Sialyltransferase,alpha 2-6-Sialyltransferase, beta-D-Galactoside,alpha-2,6-Sialyltransferase, CMP-N-Acetylneuraminate-beta-Galactoside,alpha-2-6-Sialyltransferase, beta-D-Galactoside,alpha2,6-Sialyltransferase, beta-Galactoside,alpha6 Sialyltransferase,beta D Galactoside alpha 2 6 Sialyltransferase,beta Galactoside alpha2,6 Sialyltransferase
D000116 Acetylgalactosamine The N-acetyl derivative of galactosamine. 2-Acetamido-2-D-galactopyranose,2-Acetamido-2-Deoxy-D-Galactose,2-Acetamido-2-Deoxygalactose,N-Acetyl-D-Galactosamine,2 Acetamido 2 D galactopyranose,2 Acetamido 2 Deoxy D Galactose,2 Acetamido 2 Deoxygalactose,N Acetyl D Galactosamine

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