Platelets prevent acute hepatitis induced by anti-fas antibody.
OBJECTIVE
Platelets provide many functions in the body, especially to the liver. The purpose of this study is to investigate the effect of thrombocytosis with acute hepatitis induced by anti-Fas antibody and its mechanism.


METHODS
Acute hepatitis was induced by administration of anti-Fas antibody in normal and thrombocytotic C57BL6J mice. For thrombocytosis, thrombopoietin; PEG-rHuMGDF was injected 5 days before and just prior to administration of anti-Fas antibody. To investigate the mechanisms, hepatocyte cell line (AML12) and sinusoidal endothelial cell line (M1) were induced apoptosis by staurosporine. They were cultured with platelets or thrombopoietin. Examination items were as follows: platelet number, alanine aminotransferase (ALT), histological findings, TUNEL (TdT-mediated dUTP-biotin Nick End Labeling) staining, and the expression of proteins associated with apoptosis in vivo and in vitro.


RESULTS
Platelets were significantly increased in the thrombocytotic group (P < 0.01). Serum ALT levels were significantly reduced by thrombocytosis at 6, 24 and 72 h after the administration (P < 0.05). In histological findings, hemorrhagic necrosis was observed in the normal group, but not observed in the thrombocytotic group. TUNEL-positive hepatocytes were reduced and the expression of cleaved caspase-3 was significantly decreased in the thrombocytotic group. The phosphorylation of Akt, the increment of Bcl-xL and the decrease of cleaved caspase-3 were observed in AML12 cells cultured with platelets, but were not observed cultured with thrombopoietin. Platelets and thrombopoietin had no anti-apoptotic effect on M1 cells.


CONCLUSIONS
Increase of platelets has a preventative effect against acute hepatitis induced by the anti-Fas antibody. It is suggested that platelets have a direct protective effect against apoptosis of hepatocytes.
Department of Surgery, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan.
Katsuji
K
Hisakura
Soichiro
S
Murata
Kazuhiro
K
Takahashi
Ryota
R
Matsuo
Sugiru
S
Pak
Naoya
N
Ikeda
Takuya
T
Kawasaki
Keisuke
K
Kohno
Andriy
A
Myronovych
Yoritaka
Y
Nakano
Osamu
O
Ikeda
Motonobu
M
Watanabe
Nobuhiro
N
Ohkohchi
D000208:Acute Disease; D000410:Alanine Transaminase / Q000097:blood; D000818:Animals; D000906:Antibodies; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D002460:Cell Line; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D006505:Hepatitis / Q000097:blood / Q000276:immunology / Q000473:pathology / Q000517:prevention & control*; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D020287:In Situ Nick-End Labeling; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009336:Necrosis; D010976:Platelet Count; D011092:Polyethylene Glycols; D011994:Recombinant Proteins; D019311:Staurosporine / Q000494:pharmacology; D013921:Thrombocytopenia / Q000097:blood* / Q000139:chemically induced / Q000473:pathology; D013922:Thrombocytosis / Q000097:blood* / Q000139:chemically induced / Q000473:pathology; D034061:Thrombopoiesis; D013926:Thrombopoietin; D013997:Time Factors; D019014:fas Receptor / Q000276:immunology*
D000906:Antibodies; D051017:Apoptosis Regulatory Proteins; D011994:Recombinant Proteins; D019014:fas Receptor; C103117:polyethylene glycol-recombinant human megakaryocyte growth and development factor; D011092:Polyethylene Glycols; D013926:Thrombopoietin; D000410:Alanine Transaminase; D019311:Staurosporine