title: CD4(+) T-lymphocytes mediate ischemia/reperfusion-induced inflammatory responses in mouse liver.
abstract: The success of orthotopic liver transplantation is dependent on multiple factors including MHC tissue compatibility and ischemic/reperfusion injury. Ischemic/reperfusion (I/R) injury in the liver occurs in a biphasic pattern consisting of both acute phase (oxygen free radical mediated) and subacute phase (neutrophil-mediated) damage. Although numerous studies have given insights into the process of neutrophil recruitment after I/R injury to the liver, the exact mechanism that initiates this subacute response remains undefined. Using a T cell-deficient mouse model, we present data that suggests that T-lymphocytes are key mediators of subacute neutrophil inflammatory responses in the liver after ischemia and reperfusion. To this end, using a partial lobar liver ischemia model, we compared the extent of reperfusion injury between immune competent BALB/c and athymic nu/nu mice. Studies evaluating the extent of liver damage as measured by serum transaminases (GPT) demonstrate similar acute (3-6 h) post-I/R responses in these two mouse models. In contrast, the subacute phase (16-20 h) of liver injury, as measured by both serum GPT levels and percent hepatocellular necrosis, was dramatically reduced in T cell-deficient mice as compared with those with an intact immune system. This reduction in liver injury seen in nu/nu mice was associated with a 10-fold reduction in hepatic neutrophil infiltration. Adoptive transfer of T cell-enriched splenocytes from immune competent mice was capable of reconstituting the neutrophil-mediated subacute inflammatory response within T cell-deficient nu/nu mice. Furthermore, in vivo antibody depletion of CD4(+) T-lymphocytes in immune competent mice resulted in a reduction of subacute phase injury and inflammation as measured by serum GPT levels and neutrophil infiltration. In contrast, depletion of CD8(+) T-lymphocytes had no effect on these indexes of subacute inflammation. Kinetic analysis of T cell infiltration in the livers of BALB/c mice demonstrated a fivefold increase in the number of hepatic CD4(+) T-lymphocytes within the first hour of reperfusion with no significant change in the number of CD8(+) T-lymphocytes. In summary, these results implicate CD4(+) T-lymphocytes as key regulators in initiating I/R-induced inflammatory responses in the liver. Such findings have implications for therapy directed at the early events in this inflammatory cascade that may prove useful in liver transplantation.
authors.affiliation: Institute for Human Gene Therapy at the University of Pennsylvania Medical Center, Department of Molecular and Cellular Engineering, Philadelphia, Pennsylvania 19104, USA.
authors.forename: R M
authors.initials: RM
authors.lastname: Zwacka
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: J
authors.initials: J
authors.lastname: Halldorson
authors.forename: H
authors.initials: H
authors.lastname: Schlossberg
authors.forename: L
authors.initials: L
authors.lastname: Dudus
authors.forename: J F
authors.initials: JF
authors.lastname: Engelhardt
mesh_terms: D019264:Adoptive Transfer; D000410:Alanine Transaminase / Q000097:blood; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D005434:Flow Cytometry; D006651:Histocytochemistry; D007150:Immunohistochemistry; D007511:Ischemia / Q000276:immunology / Q000473:pathology; D007700:Kinetics; D008099:Liver / Q000098:blood supply / Q000276:immunology* / Q000473:pathology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009504:Neutrophils / Q000276:immunology; D015427:Reperfusion Injury / Q000276:immunology* / Q000473:pathology
chemical_list: D000410:Alanine Transaminase