title: Rat liver sinusoidal endothelial cell phenotype is maintained by paracrine and autocrine regulation.
abstract: The phenotypic features of liver sinusoidal endothelial cells (SEC), open fenestrae in sieve plates and lack of a basement membrane, are lost with capillarization. The current study examines localization of CD31 as a marker for the dedifferentiated, nonfenestrated SEC and examines regulation of SEC phenotype in vitro. CD31 localization in SEC was examined by confocal microscopy and immunogold-scanning electron microscopy. SEC cultured for 1 day express CD31 in the cytoplasm, whereas after 3 days, CD31 is also expressed on cell-cell junctions. Immunogold-scanning electron microscopy confirmed the absence of CD31 surface expression on fenestrated SEC 1 day after isolation and demonstrated the appearance of CD31 surface expression on SEC that had lost fenestration after 3 days in culture. SEC isolated from fibrotic liver do show increased expression of CD31 on the cell surface. Coculture with either hepatocytes or stellate cells prevents CD31 surface expression, and this effect does not require heterotypic contact. The paracrine effect of hepatocytes or stellate cells on SEC phenotype is abolished with anti-VEGF antibody and is reproduced by addition of VEGF to SEC cultured alone. VEGF stimulates SEC production of nitric oxide. NG-nitro-L-arginine methyl ester blocked the paracrine effect of hepatocytes or stellate cells on SEC phenotype and blocked the ability of VEGF to preserve the phenotype of SEC cultured alone. In conclusion, surface expression of CD31 is a marker of a dedifferentiated, nonfenestrated SEC. The VEGF-mediated paracrine effect of hepatocytes or stellate cells on maintenance of SEC phenotype requires autocrine production of nitric oxide by SEC.
authors.affiliation: Research Center for Liver Diseases and the Division of Gastrointestinal and Liver Diseases,USC Keck School of Medicine, Div. of Gastrointestinal and Liver Diseases, 2011 Zonal Ave.-HMR 603, Los Angeles, CA 90033, USA. deleve@usc.edu
authors.forename: Laurie D
authors.initials: LD
authors.lastname: DeLeve
authors.forename: Xiangdong
authors.initials: X
authors.lastname: Wang
authors.forename: Liping
authors.initials: L
authors.lastname: Hu
authors.forename: Margaret K
authors.initials: MK
authors.lastname: McCuskey
authors.forename: Robert S
authors.initials: RS
authors.lastname: McCuskey
mesh_terms: D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D019898:Autocrine Communication / Q000187:drug effects / Q000502:physiology*; D015415:Biomarkers; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D022781:Hepatocytes / Q000166:cytology* / Q000378:metabolism*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D019899:Paracrine Communication / Q000187:drug effects / Q000502:physiology*; D010641:Phenotype; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism; D051381:Rats; D042461:Vascular Endothelial Growth Factor A / Q000276:immunology / Q000378:metabolism
chemical_list: D000906:Antibodies; D015415:Biomarkers; D004791:Enzyme Inhibitors; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D042461:Vascular Endothelial Growth Factor A; D009569:Nitric Oxide; D019331:NG-Nitroarginine Methyl Ester