title: Roles of hepatocyte and myeloid CXC chemokine receptor-2 in liver recovery and regeneration after ischemia/reperfusion in mice.
abstract: Previous studies have demonstrated the significance of signaling through the CXC chemokine receptor-2 (CXCR2) receptor in the process of recovery and regeneration of functional liver mass after hepatic ischemia/reperfusion (I/R). CXCR2 is constitutively expressed on both neutrophils and hepatocytes; however, the cell-specific roles of this receptor are unknown. In the present study, chimeric mice were created through bone marrow transplantation (BMT) using wild-type and CXCR2-knockout mice, yielding selective expression of CXCR2 on hepatocytes (Hep) and/or myeloid cells (My) in the following combinations: Hep+/My+; Hep-/My+; Hep+/My-; and Hep-/My-. These tools allowed us to assess the contributions of myeloid and hepatocyte CXCR2 in the recovery of the liver after I/R injury. Flow cytometry confirmed the adoption of the donor phenotype in neutrophils. Interestingly, Kupffer cells from all chimeras lacked CXCR2 expression. Recovery/regeneration of hepatic parenchyma was assessed by histologic assessment and measurement of hepatocyte proliferation. CXCR2(Hep+/My+) mice showed the least amount of liver recovery and hepatocyte proliferation, whereas CXCR2(Hep-/My-) mice had the greatest liver recovery and hepatocyte proliferation. CXCR2(Hep+/My-) mice had enhanced liver recovery, with hepatocyte proliferation similar to CXCR2(Hep-/My-) mice. Myeloid expression of CXCR2 directly regulated CXC chemokine expression levels after hepatic I/R, such that mice lacking myeloid CXCR2 had markedly increased chemokine expression, compared with mice expressing CXCR2 on myeloid cells.
  
  
  CONCLUSIONS
  The data suggest that CXCR2 on myeloid cells is the predominant regulator of liver recovery and regeneration after I/R injury, whereas hepatocyte CXCR2 plays a minor, secondary role. These findings suggest that myeloid cell-directed therapy may significantly affect liver regeneration after liver resection or transplantation.
authors.affiliation: Department of Surgery, University of Cincinnati, Cincinnati, OH 45267, USA.
authors.forename: Heather L
authors.initials: HL
authors.lastname: Van Sweringen
authors.forename: Nozomu
authors.initials: N
authors.lastname: Sakai
authors.forename: Ralph C
authors.initials: RC
authors.lastname: Quillin
authors.forename: Jeff
authors.initials: J
authors.lastname: Bailey
authors.forename: Rebecca
authors.initials: R
authors.lastname: Schuster
authors.forename: John
authors.initials: J
authors.lastname: Blanchard
authors.forename: Holly
authors.initials: H
authors.lastname: Goetzman
authors.forename: Charles C
authors.initials: CC
authors.lastname: Caldwell
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Edwards
authors.forename: Alex B
authors.initials: AB
authors.lastname: Lentsch
mesh_terms: D000818:Animals; D016026:Bone Marrow Transplantation; D049109:Cell Proliferation; D022781:Hepatocytes / Q000378:metabolism*; D008099:Liver / Q000473:pathology; D008115:Liver Regeneration; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D022423:Myeloid Cells / Q000378:metabolism*; D009504:Neutrophils / Q000378:metabolism; D023063:Receptors, Interleukin-8B / Q000378:metabolism*; D015427:Reperfusion Injury
chemical_list: D023063:Receptors, Interleukin-8B