Specific IgG glycosylation differences precede relapse in PR3-ANCA associated vasculitis patients with and without ANCA rise

• Published in: Frontiers in immunology Vol. 14; p. 1214945
• Main Authors: Wojcik, Iwona, Wuhrer, Manfred, Heeringa, Peter, Stegeman, Coen A., Rutgers, Abraham, Falck, David
• Format: Journal Article
• Language: English
• Published: Frontiers Media S.A 29.09.2023
• Subjects: anti-neutrophil cytoplasmic antibody–associated vasculitis; fucosylation; glycopeptides; glycosylation; immunoglobulin G; Immunology; mass spectrometry
• ISSN: 1664-3224; 1664-3224
• DOI: 10.3389/fimmu.2023.1214945

Introduction Immunoglobulin G (IgG) contains a conserved N-glycan in the fragment crystallizable (Fc), modulating its structure and effector functions. In anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) alterations of IgG Fc-glycosylation have been observed to correlate with the disease course. Here, we examined longitudinal changes in N - linked Fc glycans of IgG in an AAV patient cohort and their relationship with disease flares. Methods Using liquid chromatography coupled with mass spectrometry, we analysed IgG Fc-glycosylation in 410 longitudinal samples from 96 individuals with AAV. Results Analysis of the cross-sectional differences as well as longitudinal changes demonstrated that IgGs of relapsing PR3-ANCA patients have higher ΔFc-bisection at diagnosis ( P = 0.004) and exhibit a decrease in Fc-sialylation prior to the relapse ( P = 0.0004), discriminating them from non-relapsing patients. Most importantly, PR3-ANCA patients who experienced an ANCA rise and relapsed shortly thereafter, exhibit lower IgG Fc-fucosylation levels compared to non-relapsing patients already 9 months before relapse ( P = 0.02). Discussion Our data indicate that IgG Fc-bisection correlates with long-term treatment outcome, while lower IgG Fc-fucosylation and sialylation associate with impending relapse. Overall, our study replicated the previously published reduction in total IgG Fc-sialylation at the time of relapse, but showed additionally that its onset precedes relapse. Furthermore, our findings on IgG fucosylation and bisection are entirely new. All these IgG Fc-glycosylation features may have the potential to predict a relapse either independently or in combination with known risk factors, such as a rise in ANCA titre.