Autoantibodies to muscarinic acetylcholine receptors found in patients with primary biliary cirrhosis.
BACKGROUND
Autoantibodies to the human muscarinic acetylcholine receptor of the M3 type (hmAchR M3) have been suggested to play an etiopathogenic role in Sjögren's syndrome. Primary biliary cirrhosis (PBC) often is associated with this syndrome. Therefore, we studied the co-presence of hmAchR M3 autoantibodies in patients with PBC.


METHODS
Frequency of hmAchR M3 autoantibodies was assessed by Western blotting analysis as well as by an ELISA using a 25-mer peptide of the 2nd extracellular loop of hmAchR M3. Co-localization of hmAchR M3/PBC-specific autoantibodies was studied by confocal laser scanning microscopy. Finally, sera from patients with PBC as well as from healthy controls were tested.


RESULTS
Western blotting analysis as well as results from ELISA testing revealed a significantly enhanced IgG reactivity in PBC patients in contrast to healthy controls. Co-localization of autoantibodies with the hmAchR M3 receptor-specific autoantibodies was observed in 10 out of 12 PBC-patients but none of the 5 healthy controls. Antibodies of the IgM type were not found to be affected.


CONCLUSIONS
For the first time, our data demonstrate the presence of autoantibodies to the hmAchR M3 in PBC patients. These findings might contribute to the understanding of the pathogenesis of this disease. Further studies have to focus on the functionality of hmAchR M3 autoantibodies in PBC patients.
Department of Internal Medicine I, Medical Clinic, University of Tübingen, Germany. christoph.berg@med.uni-tuebingen.de
Christoph P
CP
Berg
Karin
K
Blume
Kirsten
K
Lauber
Michael
M
Gregor
Peter A
PA
Berg
Sebastian
S
Wesselborg
Gerburg M
GM
Stein
D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000097:blood / Q000276:immunology*; D015153:Blotting, Western; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008105:Liver Cirrhosis, Biliary / Q000097:blood / Q000175:diagnosis / Q000276:immunology*; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D011976:Receptors, Muscarinic / Q000097:blood / Q000276:immunology*
D001323:Autoantibodies; D011976:Receptors, Muscarinic