title: Anti-SPAG16 antibodies in primary progressive multiple sclerosis are associated with an elevated progression index.
abstract: OBJECTIVE
  Sperm-associated antigen 16 (SPAG16), a sperm protein which is upregulated in reactive astrocytes in multiple sclerosis (MS) lesions, has recently been identified as a novel autoantibody target in MS. The aim of this study was to investigate whether anti-SPAG16 antibody levels differ between MS subtypes (relapsing-remitting, RR; primary or secondary progressive, PP, SP) and whether antibody positivity is associated with clinical characteristics.
  
  
  METHODS
  Plasma anti-SPAG16 antibody levels were determined by recombinant protein enzyme-linked immunosorbent assay (ELISA) in 374 MS patients (274 RRMS, 39 SPMS and 61 PPMS) and 106 healthy controls.
  
  
  RESULTS
  Significantly elevated anti-SPAG16 antibodies were found in 22% of MS patients with 93% specificity. Anti-SPAG16 seropositivity was associated with an increased Expanded Disability Status Scale (EDSS) in overall MS. A higher proportion of PPMS patients showed anti-SPAG16 antibody reactivity (34%) compared to RRMS (19%) and SPMS (26%), and presented with higher anti-SPAG16 antibody levels. Seropositive PPMS patients had a significantly increased progression index compared to seronegative patients.
  
  
  CONCLUSIONS
  Anti-SPAG16 antibodies are associated with an increased EDSS in overall MS, indicating that they are linked to a worse MS disease outcome. Moreover, the presence of anti-SPAG16 antibodies may be a biomarker for a more severe disease in PPMS patients, as indicated by an increased progression index.
authors.affiliation: Biomedical Research Institute and Transnationale Universiteit Limburg, Hasselt University, Diepenbeek, Belgium.
authors.forename: L
authors.initials: L
authors.lastname: de Bock
authors.affiliation: Biomedical Research Institute and Transnationale Universiteit Limburg, Hasselt University, Diepenbeek, Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Fraussen
authors.affiliation: Departments of Neurology and Immunology, Ramón y Cajal Hospital, Madrid, Spain.
authors.forename: L M
authors.initials: LM
authors.lastname: Villar
authors.affiliation: Departments of Neurology and Immunology, Ramón y Cajal Hospital, Madrid, Spain.
authors.forename: J C
authors.initials: JC
authors.lastname: Álvarez-Cermeño
authors.affiliation: Biomedical Research Institute and Transnationale Universiteit Limburg, Hasselt University, Diepenbeek, Belgium.|Multiple Sclerosis and Rehabilitation Center, Overpelt, Belgium.
authors.forename: B
authors.initials: B
authors.lastname: Van Wijmeersch
authors.affiliation: Institute of Neurosciences, Neurochemistry Unit, Université Catholique de Louvain, Brussels, Belgium.
authors.forename: V
authors.initials: V
authors.lastname: van Pesch
authors.affiliation: Biomedical Research Institute and Transnationale Universiteit Limburg, Hasselt University, Diepenbeek, Belgium.
authors.forename: P
authors.initials: P
authors.lastname: Stinissen
authors.affiliation: Biomedical Research Institute and Transnationale Universiteit Limburg, Hasselt University, Diepenbeek, Belgium.
authors.forename: V
authors.initials: V
authors.lastname: Somers
mesh_terms: D000328:Adult; D001323:Autoantibodies / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D018450:Disease Progression; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D008869:Microtubule-Associated Proteins / Q000276:immunology*; D008875:Middle Aged; D020528:Multiple Sclerosis, Chronic Progressive / Q000097:blood*; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000097:blood*
chemical_list: D001323:Autoantibodies; D015415:Biomarkers; D008869:Microtubule-Associated Proteins; C450619:SPAG16 protein, human
keywords: SPAG16; autoantibodies; biomarker; multiple sclerosis