title: Pro-inflammatory pattern of IgG1 Fc glycosylation in multiple sclerosis cerebrospinal fluid.
abstract: BACKGROUND
  Immunoglobulin G (IgG) effector functions are regulated by the composition of glycans attached to a conserved N-glycosylation site in the Fc part. Intrathecal production of IgG, especially IgG1, is a hallmark of multiple sclerosis (MS), but nothing is known about IgG Fc glycosylation in MS and in cerebrospinal fluid (CSF) in general.
  
  
  METHODS
  We applied mass spectrometry of tryptic Fc glycopeptides to analyze IgG Fc glycosylation (sialylation, galactosylation, fucosylation, and bisecting N-acetylglucosamine (GlcNAc)) in 48 paired CSF and serum samples from adult patients with MS or a first demyelinating event highly suggestive of MS (designated as MS cases), and from healthy volunteers and patients with other non-inflammatory diseases (control group). p values were adjusted for multiple testing.
  
  
  RESULTS
  Our experiments revealed four main results. First, IgG1 glycosylation patterns were different in CSF vs. serum, in the MS group and even in control donors without intrathecal IgG synthesis. Second, in MS patients vs. controls, IgG1 glycosylation patterns were altered in CSF, but not in serum. Specifically, in CSF from the MS group, bisecting GlcNAc were elevated, and afucosylation and galactosylation were reduced. Elevated bisecting GlcNAc and reduced galactosylation are known to enhance IgG effector functions. Third, hypothesis-free regression analysis revealed that alterations of afucosylation and bisecting GlcNAc in CSF from MS cases peaked 2-3 months after the last relapse. Fourth, CSF IgG1 glycosylation correlated with the degree of intrathecal IgG synthesis and CSF cell count.
  
  
  CONCLUSIONS
  The CNS compartment as well as the inflammatory milieu in MS affect IgG1 Fc glycosylation. In MS, the CSF IgG1 glycosylation has features that enhance Fc effector functions.
authors.affiliation: Center for Proteomics and Metabolomics, Leiden University Medical Center, Leiden, The Netherlands. M.Wuhrer@lumc.nl.|Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, The Netherlands. M.Wuhrer@lumc.nl.|Division of BioAnalytical Chemistry, VU University Amsterdam, Amsterdam, The Netherlands. M.Wuhrer@lumc.nl.
authors.forename: Manfred
authors.initials: M
authors.lastname: Wuhrer
authors.affiliation: Center for Proteomics and Metabolomics, Leiden University Medical Center, Leiden, The Netherlands. mauriceselman@yahoo.com.
authors.forename: Maurice H J
authors.initials: MH
authors.lastname: Selman
authors.affiliation: Center for Proteomics and Metabolomics, Leiden University Medical Center, Leiden, The Netherlands. l.a.mcdonnell@lumc.nl.
authors.forename: Liam A
authors.initials: LA
authors.lastname: McDonnell
authors.affiliation: Institute of Clinical Neuroimmunology, Biomedical Center (BMC) and University Hospital, Campus Martinsried-Grosshadern, LMU Munich, Munich, Germany. Tania.Kuempfel@med.uni-muenchen.de.
authors.forename: Tania
authors.initials: T
authors.lastname: Kümpfel
authors.affiliation: Departments of Neurology and Biomedicine, University Hospital, Basel, Switzerland. Tobias.Derfuss@usb.ch.
authors.forename: Tobias
authors.initials: T
authors.lastname: Derfuss
authors.affiliation: Department of Clinical Neuroscience, Neuroimmunology Unit, Karolinska University Hospital, Stockholm, Sweden. Mohsen.Khademi@ki.se.
authors.forename: Mohsen
authors.initials: M
authors.lastname: Khademi
authors.affiliation: Department of Clinical Neuroscience, Neuroimmunology Unit, Karolinska University Hospital, Stockholm, Sweden. Tomas.Olsson@ki.se.
authors.forename: Tomas
authors.initials: T
authors.lastname: Olsson
authors.affiliation: Institute of Clinical Neuroimmunology, Biomedical Center (BMC) and University Hospital, Campus Martinsried-Grosshadern, LMU Munich, Munich, Germany. Reinhard.Hohlfeld@med.uni-muenchen.de.|Munich Cluster of Systems Neurology (SyNergy), Munich, Germany. Reinhard.Hohlfeld@med.uni-muenchen.de.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Hohlfeld
authors.affiliation: Institute of Clinical Neuroimmunology, Biomedical Center (BMC) and University Hospital, Campus Martinsried-Grosshadern, LMU Munich, Munich, Germany. Edgar.Meinl@med.uni-muenchen.de.
authors.forename: Edgar
authors.initials: E
authors.lastname: Meinl
authors.affiliation: Institute of Clinical Neuroimmunology, Biomedical Center (BMC) and University Hospital, Campus Martinsried-Grosshadern, LMU Munich, Munich, Germany. markus.krumbholz@uni-tuebingen.de.|Department of Neurology and Stroke, and Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany. markus.krumbholz@uni-tuebingen.de.
authors.forename: Markus
authors.initials: M
authors.lastname: Krumbholz
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood / Q000134:cerebrospinal fluid; D005260:Female; D006031:Glycosylation; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood* / Q000134:cerebrospinal fluid*; D018836:Inflammation Mediators / Q000097:blood* / Q000134:cerebrospinal fluid*; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000097:blood* / Q000134:cerebrospinal fluid* / Q000175:diagnosis
chemical_list: D015415:Biomarkers; D007074:Immunoglobulin G; D018836:Inflammation Mediators