P-selectin mediates leukocyte rolling in concanavalin-A-induced hepatitis.
Concanavalin-A (Con-A)-induced hepatitis is an experimental model of human autoimmune hepatitis characterized by leukocyte activation and infiltration of the liver. The aim of the present study was to evaluate the role of P-selectin on leukocyte-endothelial interactions within the hepatic microvasculature in response to Con-A.


METHODS
The study was performed in P-selectin-deficient mice and wild-type mice pretreated with anti-P-selectin blocking monoclonal antibody (mAb) or vehicle. After 2 h of Con-A (20 mg/kg i.v.) or PBS administration, leukocyte rolling and adhesion and the index of sinusoidal perfusion were evaluated using the intravital microscopy technique in the liver. Apoptosis was determined by flow cytometry analysis of caspase-3 activity assayed on freshly isolated hepatocytes.


RESULTS
Con-A induced a significant increase in leukocyte rolling, mainly located at the central venule (2.1+/-0.4 vs 0.6+/-0.2 cells/min in wild-type mice treated with vehicle) and less marked, but still significant, in portal venules. This was associated with a significant increase in leukocyte adhesion. In P-selectin-deficient mice treated with Con-A, leukocyte rolling in portal and central venules was markedly reduced. However, leukocyte adhesion was only partially attenuated. A few sinusoids were perfused in wild-type mice treated with Con-A (26%). The percentage of perfused sinusoids was significantly higher in P-selectin-deficient mice (45%; P<0.05 vs wild-type). Similar effects were noted after the simultaneous injection of Con-A and anti-P-selecting mAb in wild-type mice. After Con-A treatment, apoptosis was markedly reduced in isolated hepatocytes of P-selectin-deficent mice (37+/-7% vs 75+/-5% in wild type).


CONCLUSIONS
The results of this intravital microscopy study clearly demonstrate that P-selectin is involved in the initial leukocyte rolling that leads to the development of Con-A-induced liver injury.
March
Sandra
S
Immunology Unit, Department of Cellular Biology and Pathology, Medical School, University of Barcelona, Villaroel 170, Barcelona, Spain.
Garcia-Pagán
Joan-Carles
JC
Massaguer
Anna
A
Pizcueta
Pilar
P
Panés
Juliàn
J
Engel
Pablo
P
Bosch
Jaume
J
D000818:Animals; D017209:Apoptosis; D002448:Cell Adhesion; D002450:Cell Communication; D002465:Cell Movement; D003208:Concanavalin A / Q000633:toxicity*; D042783:Endothelial Cells / Q000502:physiology; D019693:Hepatitis, Autoimmune / Q000097:blood / Q000209:etiology* / Q000473:pathology; D007962:Leukocytes / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D019007:P-Selectin / Q000502:physiology*
D019007:P-Selectin; D003208:Concanavalin A