Abstract
Aberrant glycosylation has been observed in many autoimmune diseases. For example, aberrant glycosylation of immunoglobulin G (IgG) has been implicated in rheumatoid arthritis (RA) pathogenesis. The aim of this study is to investigate IgG glycosylation and whether there is an association with rheumatoid factor levels in the serum of RA patients. We detected permethylated N-glycans of the IgG obtained in serum from 44 RA patients and 30 healthy controls using linear ion-trap electrospray ionization mass spectrometry (LTQ-ESI-MS), a highly sensitive and efficient approach in the detection and identification of N-glycans profiles. IgG N-glycosylation and rheumatoid factor levels were compared in healthy controls and RA patients. Our results suggested that total IgG purified from serum of RA patients shows significantly lower galactosylation (p = 0.0012), lower sialylation (p < 0.0001) and higher fucosylation (p = 0.0063) levels compared with healthy controls. We observed a positive correlation between aberrant N-glycosylation and rheumatoid factor level in the RA patients. In conclusion, we identified aberrant glycosylation of IgG in the serum of RA patients and its association with elevated levels of rheumatoid factor.
Highlights
Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by activation of the immune system and secretion of autoantibodies [1]
We identified Immunoglobulin G (IgG) N-glycan profiles in the serum of patients with RA and found remarkably different profiles of glycoforms compared with healthy controls
Our results indicated significantly lower sialylation, reduced bisection, and increased fucosylation in patients with RA compared with healthy controls
Summary
Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by activation of the immune system and secretion of autoantibodies [1]. Changes of the N-linked Fc glycan on Asn 297 have been reported to affect the structural stability and functional activity of IgG, subsequently influencing the immune response [4]. There are regularly different subclasses on immunoglobulin G, the total IgG glycosylation is generally quite constant [11]. Different glycosylation patterns of total IgG have been observed in patients with a number of auto-immune diseases when compared with healthy controls, including rheumatoid arthritis [5,6], systemic lupus erythematosus [12], inflammatory bowel disease [13], primary Sjögren’s syndrome, ankyloInst.iJn. Mgosl.pScoi.
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