title: Glycoprotein Nonmetastatic Melanoma B (Gpnmb)-Positive Macrophages Contribute to the Balance between Fibrosis and Fibrolysis during the Repair of Acute Liver Injury in Mice.
abstract: OBJECTIVE
  Glycoprotein nonmetastatic melanoma B (Gpnmb), a transmembrane glycoprotein that is expressed in macrophages, negatively regulates inflammation. We have reported that Gpnmb is strongly expressed in the livers of rats fed a choline-deficient, L-amino acid-defined (CDAA) diet. However, the role of macrophage-expressed Gpnmb in liver injury is still unknown. This study aimed to clarify the characteristics of infiltrating macrophages that express Gpnmb, and the involvement of Gpnmb in the repair process in response to liver injury.
  
  
  METHODS
  C57BL/6J, DBA/2J [DBA] and DBA/2J-Gpnmb+ [DBA-g+] mice were treated with a single intraperitoneal injection of carbon tetrachloride (CCl4) at a dose of 1.0 mL/kg body weight. Mice were sacrificed at predetermined time points, followed by measurement of serum alanine aminotransferase (ALT) levels and histological examination. Expression of Gpnmb, pro-/anti-inflammatory cytokines, and profibrotic/antifibrotic factors were examined by quantitative RT-PCR and/or Western blotting. Immunohistochemistry, fluorescent immunostaining and flow cytometry were used to determine the expression of Gpnmb, CD68, CD11b and α-SMA, phagocytic activity, and the presence of apoptotic bodies. We used quantitative RT-PCR and ELISA to examine TGF-β and MMP-13 expression and the concentrations and supernatants of isolated infiltrating hepatic macrophages transfected with siGpnmb.
  
  
  RESULTS
  In C57BL/6J mice, serum ALT levels increased at two days after CCl4 injection and decreased at four days. Gpnmb expression in the liver was stimulated four days after CCl4 injection. Histological examination and flow cytometry showed that Gpnmb-positive cells were almost positive for CD68-positive macrophages, contained engulfed apoptotic bodies and exhibited enhanced phagocytic activity. Isolated infiltrating hepatic macrophages transfected with siGpnmb showed high MMP-13 secretion. There was no significant difference in the magnitude of CCl4-induced liver injury between DBA-g+ and DBA mice. However, hepatic MMP-13 expression, as well as α-SMA expression and collagen production, increased significantly in DBA-g+ compared with DBA mice.
  
  
  CONCLUSIONS
  Gpnmb-positive macrophages infiltrate the liver during the recovery phase of CCl4-induced acute liver injury and contribute to the balance between fibrosis and fibrolysis in the repair process following acute liver injury.
authors.affiliation: Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
authors.forename: Kotaro
authors.initials: K
authors.lastname: Kumagai
authors.affiliation: Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Tabu
authors.affiliation: Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
authors.forename: Fumisato
authors.initials: F
authors.lastname: Sasaki
authors.affiliation: Pharmaceutical Care and Health Sciences, School of Pharmacy, Shujitsu University, Okayama, Japan.
authors.forename: Yoichiro
authors.initials: Y
authors.lastname: Takami
authors.affiliation: Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Morinaga
authors.affiliation: Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
authors.forename: Seiichi
authors.initials: S
authors.lastname: Mawatari
authors.affiliation: Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Hashimoto
authors.affiliation: Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
authors.forename: Shiroh
authors.initials: S
authors.lastname: Tanoue
authors.affiliation: Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
authors.forename: Shuji
authors.initials: S
authors.lastname: Kanmura
authors.affiliation: Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Tamai
authors.affiliation: Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Moriuchi
authors.affiliation: Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.|Center for Digestive and Liver diseases, Miyazaki Medical Center Hospital, Miyazaki, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Uto
authors.affiliation: Kagoshima City Hospital, Kagoshima, Japan.
authors.forename: Hirohito
authors.initials: H
authors.lastname: Tsubouchi
authors.affiliation: Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
authors.forename: Akio
authors.initials: A
authors.lastname: Ido
mesh_terms: D000208:Acute Disease; D000410:Alanine Transaminase / Q000378:metabolism; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism; D002251:Carbon Tetrachloride; D056486:Chemical and Drug Induced Liver Injury / Q000378:metabolism / Q000473:pathology*; D003094:Collagen / Q000378:metabolism; D005136:Eye Proteins / Q000378:metabolism*; D008099:Liver / Q000378:metabolism / Q000473:pathology; D008103:Liver Cirrhosis / Q000378:metabolism / Q000473:pathology*; D008264:Macrophages / Q000378:metabolism* / Q000473:pathology; D053509:Matrix Metalloproteinase 13 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D010587:Phagocytosis; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism; D014945:Wound Healing; D000097382:CD68 Molecule
chemical_list: D000410:Alanine Transaminase; D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D002251:Carbon Tetrachloride; D003094:Collagen; D005136:Eye Proteins; D053509:Matrix Metalloproteinase 13; D020780:Matrix Metalloproteinase 9; D008562:Membrane Glycoproteins; D019715:Tissue Inhibitor of Metalloproteinase-1; D016212:Transforming Growth Factor beta; C067980:CD68 antigen, human; D000097382:CD68 Molecule; C445671:Gpnmb protein, mouse