Vascular endothelial growth factor receptor-1 signaling promotes liver repair through restoration of liver microvasculature after acetaminophen hepatotoxicity.
Vascular endothelial growth factor (VEGF) and its receptors promote liver regeneration. The objective of the present study was to examine the role of VEGF receptor 1 (VEGFR1) signaling in hepatic tissue repair after acetaminophen (N-acetyl-para-aminophenol) (APAP)-induced liver injury. To do this, we treated VEGFR1 tyrosine kinase knockout (VEGFR1 TK(-/-)) and wild-type (WT) mice with APAP (300 mg/kg, ip). In WT mice, serum levels of alanine aminotransferase (ALT) and the necrotic area peaked between 8 and 24 h and then declined. In VEGFR1 TK(-/-) mice, ALT levels remained high at 48 h and extensive hepatic necrosis and hemorrhage were observed, as well as high mortality. Downregulation of hepatic messenger RNA expression of VEGFR1 and VEGFR2 was also noted in VEGFR1 TK(-/-) mice. VEGFR1 TK(-/-) mice displayed lower expression of proliferating cell nuclear antigen and of growth factors including hepatocyte growth factor, CD31, and basic fibroblast growth factor than WT. The hepatic microvasculature in VEGFR1 TK(-/-) was compromised as evidenced by impaired sinusoidal perfusion, suppressed endocytosis in liver sinusoidal endothelial cells (LSECs), and the formation of large gaps in LSECs. In WT mice, immunofluorescence revealed that recruited VEGFR1(+) cells in the necrotic area were positive for CD11b. VEGFR1 TK(-/-) exhibited fewer VEGFR1(+) and VEGFR2(+) cells. These results suggest that VEGFR1 signaling facilitates liver recovery from APAP hepatotoxicity by preventing excessive hemorrhage and reconstituting the sinusoids through recruitment of VEGFR1-expressing macrophages to the injured area and also through affecting expression of genes including hepatotrophic and pro-angiogenic growth factors.
Department of Pharmacology, Kitasato University School of Medicine, Kanagawa 252-0374, Japan.
Tetsuki
T
Kato
Yoshiya
Y
Ito
Kanako
K
Hosono
Tatsunori
T
Suzuki
Hideaki
H
Tamaki
Tsutomu
T
Minamino
Shintaro
S
Kato
Hiroyuki
H
Sakagami
Masabumi
M
Shibuya
Masataka
M
Majima
D000082:Acetaminophen / Q000633:toxicity*; D000818:Animals; D056486:Chemical and Drug Induced Liver Injury / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D004797:Enzyme-Linked Immunosorbent Assay; D008099:Liver / Q000098:blood supply* / Q000201:enzymology / Q000648:ultrastructure; D008115:Liver Regeneration / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008833:Microcirculation / Q000502:physiology; D008855:Microscopy, Electron, Scanning; D008856:Microscopy, Fluorescence; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000235:genetics / Q000378:metabolism*
D000082:Acetaminophen; D040281:Vascular Endothelial Growth Factor Receptor-1