Anti-phospholipid antibodies associated with alcoholic liver disease target oxidized phosphatidylserine on apoptotic cell plasma membranes.
OBJECTIVE
Circulating anti-phospholipid antibodies (aPL) are often present in patients with alcoholic liver disease (ALD). The observations that defects in the disposal of apoptotic corpses leads to the development of aPL prompted us to investigate whether ALD-associated aPL might recognize antigens in apoptotic cells.


METHODS
Apoptosis was induced in HuT-78 human T-lymphoma and HepG2 hepatoma cells by, respectively, FAS ligation with CH11 monoclonal antibodies or the incubation with ethanol (400 mmol/L).


RESULTS
Flow cytometry revealed that IgG from ALD patients with high aPL titers selectively bind to the surface of apoptotic, but not to viable cells. No binding was instead evident using either control or aPL-negative ALD sera. ELISA assays using different oxidized phospholipids as antigens showed that anti-phospholipid reactivity of ALD sera was mainly directed towards oxidized cardiolipin and phosphatidylserine. The pre-adsorption of aPL-positive sera with oxidized phosphatidylserine, but not with oxidized cardiolipin, lowered aPL binding to apoptotic HuT-78 cells by about 50%. No effect was instead observed by pre-adsorption with oxidation-protected phospholipids or with human serum albumin adducted with different lipid peroxidation products.


CONCLUSIONS
aPL associated with ALD target apoptotic cells by specifically recognizing oxidized phosphatidylserine, suggesting a possible link between hepatocyte apoptosis and anti-phospholipid auto-reactivity in ALD.
Vay
Daria
D
Department of Medical Sciences, University A. Avogadro of East Piedmont, Department of Medical Science, Via Solaroli 17, 28100 Novara, Italy.
Rigamonti
Cristina
C
Vidali
Matteo
M
Mottaran
Elisa
E
Alchera
Elisa
E
Occhino
Giuseppa
G
Sartori
Massimo
M
Albano
Emanuele
E
D000328:Adult; D000368:Aged; D017152:Antibodies, Antiphospholipid / Q000276:immunology*; D017209:Apoptosis / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D005260:Female; D005434:Flow Cytometry; D022781:Hepatocytes / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D015227:Lipid Peroxidation / Q000502:physiology; D008108:Liver Diseases, Alcoholic / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress / Q000502:physiology*; D010718:Phosphatidylserines / Q000378:metabolism*
D017152:Antibodies, Antiphospholipid; D010718:Phosphatidylserines