title: Erythrophagocytosis by liver macrophages (Kupffer cells) promotes oxidative stress, inflammation, and fibrosis in a rabbit model of steatohepatitis: implications for the pathogenesis of human nonalcoholic steatohepatitis.
abstract: Nonalcoholic steatohepatitis (NASH) is a progressive fibrotic disease, the pathogenesis of which has not been fully elucidated. Here, we report a molecular aspect of this disease elucidated using rabbits fed a cholesterol-rich high-fat diet and exhibiting insulin resistance. The liver in this model showed steatohepatitis with fibrosis and high mRNA expression for some cytokines, heme oxygenase-1, transforming growth factor-beta1, and collagen alpha1(I). Erythrocytes isolated from the model showed marked fragility and the externalization of phosphatidylserine (PS) on the outer leaflet of the membrane and were frequently engulfed by Kupffer cells/macrophages in the hepatic sinusoids. Expression of milk fat globule-epidermal growth factor (EGF)-factor 8, a PS-binding protein, was augmented in the liver. In culture, RAW 264.7 cells engulfed erythrocytes oxidized by tert-butyl hydroperoxide, a process that was inhibited by anti-milk fat globule-EGF-factor 8 antibody. In addition, PS-positive erythrocytes appeared entrapped in the model liver in ex vivo perfusion experiments. Finally, in specimens from NASH patients, the aggregation of erythrocytes in inflammatory hepatic sinusoids was notable. These results indicate that the engulfment of PS-externalized, apoptotic signal-positive, erythrocytes by hepatic macrophages may lead to the deposition of iron derived from hemoglobin in the liver and be involved in the pathogenesis of steatohepatitis.
authors.affiliation: Department of Hepatology, Graduate School of Medicine, Osaka City University, 1-4-3, Asahimachi, Abeno, Osaka 545-8585, Japan.
authors.forename: Kohji
authors.initials: K
authors.lastname: Otogawa
authors.forename: Kohji
authors.initials: K
authors.lastname: Kinoshita
authors.forename: Hideki
authors.initials: H
authors.lastname: Fujii
authors.forename: Masahide
authors.initials: M
authors.lastname: Sakabe
authors.forename: Ryoko
authors.initials: R
authors.lastname: Shiga
authors.forename: Kazuki
authors.initials: K
authors.lastname: Nakatani
authors.forename: Kazuo
authors.initials: K
authors.lastname: Ikeda
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nakajima
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Ikura
authors.forename: Makiko
authors.initials: M
authors.lastname: Ueda
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Arakawa
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Hato
authors.forename: Norifumi
authors.initials: N
authors.lastname: Kawada
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D017209:Apoptosis / Q000502:physiology; D002460:Cell Line; D016207:Cytokines / Q000032:analysis; D017931:DNA Primers; D004195:Disease Models, Animal; D004912:Erythrocytes / Q000378:metabolism* / Q000473:pathology; D005260:Female; D005355:Fibrosis; D005434:Flow Cytometry; D006505:Hepatitis / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D007249:Inflammation / Q000378:metabolism* / Q000473:pathology; D007501:Iron / Q000378:metabolism; D007728:Kupffer Cells / Q000378:metabolism*; D008099:Liver / Q000378:metabolism / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D046529:Microscopy, Electron, Transmission; D008875:Middle Aged; D018384:Oxidative Stress / Q000502:physiology*; D010587:Phagocytosis / Q000502:physiology*; D010718:Phosphatidylserines / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D011817:Rabbits; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D016207:Cytokines; D017931:DNA Primers; D010718:Phosphatidylserines; D012333:RNA, Messenger; D007501:Iron