title: Significance of smooth muscle/anti-actin autoantibodies in celiac disease.
abstract: OBJECTIVE
  Smooth muscle antibody (SMA) specific for the protein actin, a major component of the cytoskeleton of epithelial cells, is one of the most prevalent non-organ specific autoantibodies in the serum of celiac disease (CD) patients. Our aim was to explore the clinical relevance of the presence of IgA type anti-actin antibody (AAA) and SMA in a series of patients with CD.
  
  
  METHODS
  We evaluated frozen serum samples collected at diagnosis from 92 adult patients with CD and 52 control individuals in whom CD was excluded. Patients were re-evaluated a median time of 5 yr after treatment. IgA type AAA was detected using a modified commercial ELISA assay and IgA SMA was detected using indirect immunofluorescence on primate esophagus substrate.
  
  
  RESULTS
  At diagnosis, samples from CD patients had significantly higher AAA values than controls (p<0.00001). While all active CD patients had serum AAA values over the cut-off for healthy controls, we observed a very significant reduction of these antibodies after treatment (p>0.0001). AAA had a highly significant correlation with both, tissue, transglutaminase (r=0.62) and antigliadin (r=0.60, p<0.00001) antibodies as well as the severity of the intestinal injury (p<0.05). SMA was detected in sera of 35 consecutive CD patients. At diagnosis, SMA positive patients had significantly higher values of AAA (p<0.0002), increased number of autoimmune disorders (p<0.04), delayed menarche (p<0.04), lower hemoglobin levels (p<0.01), increased fecal a-I antitrypsin clearance (p<0.01) and more severe diarrhea (p<0.06). We also detected a trend to more severe complications at follow-up (p=0.059).
  
  
  CONCLUSIONS
  Based on our findings we suggest that the presence of increased IgA AAA serum levels is a highly sensitive marker of the disturbed architecture of intestinal epithelial cells of CD patients with a potential relevance to diagnosis and follow-up. The presence of SMA seems to define a distinct subset of CD patients with a more severe clinical outcome.
authors.affiliation: Small Bowel Section, Department of Medicine, Dr Carlos Bonorino Udaondo Gastroenterology Hospital, Buenos Aires, Argentina.
authors.forename: Silvia
authors.initials: S
authors.lastname: Pedreira
authors.forename: Emilia
authors.initials: E
authors.lastname: Sugai
authors.forename: María Laura
authors.initials: ML
authors.lastname: Moreno
authors.forename: Horacio
authors.initials: H
authors.lastname: Vázquez
authors.forename: Sonia
authors.initials: S
authors.lastname: Niveloni
authors.forename: Edgardo
authors.initials: E
authors.lastname: Smecuol
authors.forename: Roberto
authors.initials: R
authors.lastname: Mazure
authors.forename: Zulema
authors.initials: Z
authors.lastname: Kogan
authors.forename: Eduardo
authors.initials: E
authors.lastname: Mauriño
authors.forename: Julio C
authors.initials: JC
authors.lastname: Bai
mesh_terms: D000199:Actins / Q000276:immunology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001323:Autoantibodies / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D002446:Celiac Disease / Q000175:diagnosis / Q000178:diet therapy / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D005500:Follow-Up Studies; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009130:Muscle, Smooth / Q000276:immunology*; D012720:Severity of Illness Index
chemical_list: D000199:Actins; D001323:Autoantibodies; D015415:Biomarkers; D007070:Immunoglobulin A