Article pubs.acs.org/jpr
IgG Fc N‑Glycosylation in Guillain−Barré Syndrome Treated with Immunoglobulins Willem-Jan R. Fokkink,†,‡ Maurice H. J. Selman,∥ Juliette R. Dortland,†,‡ Büsŗ a Durmuş,§ Krista Kuitwaard,‡ Ruth Huizinga,† Wouter van Rijs,†,‡ Anne P. Tio-Gillen,†,‡ Pieter A. van Doorn,‡ André M. Deelder,∥ Manfred Wuhrer,∥ and Bart C. Jacobs*,†,‡ †
Department of Immunology, ‡Department of Neurology, and §Department of Epidemiology, Erasmus MC, University Medical Center Rotterdam, Dr. Molewaterplein 50, 3000 CA Rotterdam, The Netherlands ∥ Center for Proteomics and Metabolomics, Leiden University Medical Center, 2300 RC Leiden, The Netherlands ABSTRACT: Intravenous immunoglobulin (IVIg) is the treatment of choice for Guillain−Barré syndrome (GBS), an immune-mediated peripheral neuropathy causing rapidly progressive limb weakness and respiratory failure. The working mechanism of IVIg in autoimmune diseases has not been elucidated, but previous studies indicate that some anti-inflammatory effects may be mediated by the N-glycosylation of the Fc-portion of IgG. GBS is a model disease to investigate these effects because GBS is an acute and monophasic disorder usually affecting healthy persons, which is treated with a standard course of IVIg, although the clinical response is highly variable. In the current study, the N-glycosylation of the Fc-portion of serum IgG was investigated in patients with GBS before and after treatment with IVIg in relation to clinical course and outcome. Glycoforms of serum IgG1 and IgG2 were determined separately by liquid chromatography mass spectrometry. These IgG subclasses were purified from the serum of 174 GBS patients before and in 150 patients 2 weeks after standard IVIg treatment regimen. Treatment-naive GBS patients compared with ageand sex-matched controls had lower levels of galactosylation of IgG1 and IgG2. IVIg preparations contained relatively high levels of galactosylated and sialylated IgG Fc glycoforms compared with serum IgG in patients. Treatment with IVIg resulted in an increase in serum of the Fc-galactosylation and -sialylation of both IgG1 and IgG2. The extent of normalization in serum IgG Fc glycosylation varied between patients. Multiple logistic regression analysis showed that patients with persistent low IgG galactosylation and sialylation despite IVIg treatment had the most severe forms of GBS and needed ventilator support more often. Kaplan−Meier analysis showed that these patients also needed more time to be able to walk again compared with patients with a normalized IgG Fc glycosylation profile. In conclusion, our results suggest that serum IgG Fc glycosylation in GBS is related to disease severity and clinical recovery after IVIg and may help to develop new measures to monitor the efficacy of treatment. KEYWORDS: Guillain−Barré syndrome, antibody glycosylation, biomarker, intravenous immunoglobulin, glycopeptides, mass spectrometry
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for patients with GBS.6 IVIg has pleiotropic immune-modulatory effects that may contribute to clinical recovery in GBS.7 Despite the proven therapeutic effect of IVIg in GBS, the clinical course is highly variable between patients.8 A large proportion of patients shows a poor outcome after IVIg: 25% require artificial ventilation, 10−20% remain disabled, and 3−10% die. 8 Previously, we showed that the level of IgG in serum varies between patients after treatment with a standard dosage of IVIg.9 Patients with a lower increase in serum IgG levels after treatment showed a significantly poorer outcome.8,9 Biomarkers like serum IgG that reflect disease activity and response to treatment in the future could help to optimize the treatment of individual patients with GBS.
INTRODUCTION
Immunoglobulin G (IgG) plays a key role in both pathogenesis and treatment of the Guillain−Barré syndrome (GBS), an immune-mediated disorder of peripheral nerves causing rapidly progressive muscle weakness of the limbs and respiratory failure. Serum IgG autoantibodies to various gangliosides are present in the acute phase of disease in up to half of the patients with GBS.1,2 Some of these antibodies have been raised in response to a preceding infection with Campylobacter jejuni and other microbes that express carbohydrate structures mimicking gangliosides.1,3 Cross-reactive IgG frequently binds to gangliosides at the peripheral nerves and has various deleterious effects at the nodes of Ranvier or nerve terminals, which may initiate the onset of acute polyradiculoneuropathy and rapidly progressive weakness.4,5 IgG is also important as the main component of intravenous immunoglobulins (IVIg), the first-choice treatment © 2014 American Chemical Society
Received: December 9, 2013 Published: February 17, 2014 1722
dx.doi.org/10.1021/pr401213z | J. Proteome Res. 2014, 13, 1722−1730
Journal of Proteome Research
Article
versus plasma exchange (N = 147)25 and (2) IVIg and placebo versus IVIg and methylprednisolone (N = 225).26 All patients fulfilled the diagnostic criteria for GBS27 and were admitted to the hospital within 2 weeks of onset of weakness and were unable to walk 10 meters independently. Patients were included between July 1986 and August 2000. Clinical data and serum samples were collected prospectively in these patients at standard time points during a follow-up of 6 months. From 174 (46.8%) of the total of 372 trial patients, a sufficient amount of pretreatment serum was available to participate in the current study. The demographic and clinical characteristics of these 174 patients are described in Table 1 and did not differ from the excluded patients. To
IgGs are highly diverse regarding specificity, subclass, and glycosylation. Previous studies indicated that the glycosylation of a single amino acid in the Fc-region of human IgG (Asn297) influences the activity of the immunoglobulins, leading to proand anti-inflammatory effects.10 It consists of two N-glycans with a variable number of galactose and sialic acid residues, which give rise to various IgG glycoforms (Figure 1).11,12 The Fc
Table 1. Demography, Clinical Course, and Outcome of 174 Patients with GBSa Demographic Features age (years) males Symptoms of Preceding Infections diarrhea upper respiratory tract infection Clinical Severity at Entry GBS disability scoreb GBS disability score ≥4 MRC sum scorec MRC sum score
