title: Sialylated IgG-Fc: a novel biomarker of chronic inflammatory demyelinating polyneuropathy.
abstract: OBJECTIVE
  Sialylation in Fc portion of IgG plays a crucial role in the pathogenesis of autoimmune diseases and the working mechanism of intravenous immunoglobulin (IVIG). We aim to test whether IgG-Fc sialylation is a biomarker of disease activity for chronic inflammatory demyelinating polyneuropathy (CIDP).
  
  
  METHODS
  By using specific lectins for sialylation, galactosylation and agalactosylation, lectin-enzyme assay and lectin blotting with pretreatment of IgG degradating enzyme of Streptococcus pyogenes were performed to compare the glycosylation levels of serum IgG-Fc (1) between patients of untreated CIDP (n=107) and normal control subjects (n=27), (2) among patients with untreated CIDP of different clinical severities and (3) before and after IVIG treatment of patients with CIDP (n=12).
  
  
  RESULTS
  Sialylation and galactosylation of IgG-Fc were significantly reduced in patients with CIDP than normal control subjects (p=0.003 and 0.033, respectively), whereas agalactosylation was increased in CIDP (p=0.21). Ratios of sialylated/agalactosylated IgG-Fc levels were significantly reduced in CIDP (p<0.001) and inversely related to disease severity (p=0.044). After IVIG treatment, levels of sialylated IgG-Fc significantly increased (p=0.003).
  
  
  CONCLUSIONS
  Sialylation of IgG-Fc is reduced in CIDP. Its level correlated with clinical severity and increased after IVIG treatment. Sialylated as well as ratio of sialylated/agalactosylated IgG-Fc could be new measures to monitor the disease severity and treatment status in CIDP.
authors: Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
authors: Anna Hiu Yi
authors: http://orcid.org/0000-0002-3255-5073
authors: AH
authors: Wong
authors: Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
authors: Yuki
authors: Y
authors: Fukami
authors: Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
authors: Makoto
authors: M
authors: Sudo
authors: Department of Neurology, Dokkyo Medical University, Tochigi, Japan.
authors: Norito
authors: N
authors: Kokubun
authors: Department of Neurology, Hokuyukai Neurological Hospital, Sapporo, Japan.
authors: Shinsuke
authors: S
authors: Hamada
authors: Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
authors: Nobuhiro
authors: N
authors: Yuki
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood / Q000737:chemistry; D016022:Case-Control Studies; D005260:Female; D006031:Glycosylation / Q000187:drug effects; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000097:blood / Q000737:chemistry* / Q000276:immunology*; D007074:Immunoglobulin G / Q000097:blood / Q000737:chemistry* / Q000276:immunology*; D016756:Immunoglobulins, Intravenous / Q000494:pharmacology / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D020277:Polyradiculoneuropathy, Chronic Inflammatory Demyelinating / Q000097:blood* / Q000188:drug therapy / Q000276:immunology*
chemical_list: D015415:Biomarkers; D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D016756:Immunoglobulins, Intravenous
keywords: IMMUNOLOGY; NEUROPATHY