MCP-1 production by macrophages is stimulated by neutrophil elastase and oxygen radicals generated by hypoxia, probably due to microthrombus formation after ischemia/reperfusion of the rat liver.

No abstract

Neutrophil elastase, which enhances intercellular adhesion molecule-1 (ICAM-1) expression in endothelial cells, plays an important role in ischemia/reperfusion injury. Here, we investigated signal transduction of ICAM-1 expression in endothelial cells stimulated by neutrophil elastase. Pretreatment of animals with the neutrophil elastase inhibitor, ONO-5046.Na significantly decreased the number of neutrophils or Mac-1(+) (CD11b/CD18) cells in ischemic liver lobes after reperfusion. ICAM-1 expression in the rat endothelial cell line (WK-5) was significantly upregulated after stimulation with neutrophil elastase, but this reaction was inhibited by the neutrophil elastase inhibitor ONO-5046.Na. ICAM-1 mRNA expression, which is induced by neutrophil elastase in a dose-dependent manner, was repressed by the alpha1-protease inhibitor. ICAM-1 expression, stimulated by neutrophil elastase, was partially reduced by a diacylglycerol kinase inhibitor and protein kinase C inhibitor, but was completely inhibited by a phospholipase C inhibitor, cytosolic Ca(2+) chelator, calmodulin antagonist, and nuclear transcription factor kappa B inhibitor. Binding of (125)I-neutrophil elastase to WK-5 cells was competitively inhibited by the addition of unlabeled neutrophil elastase. The neutrophil elastase inhibitor significantly reduces ICAM-1 expression and Mac-1(+) cell accumulation in ischemic liver lobes after reperfusion. Neutrophil elastase stimulates ICAM-1 expression in endothelial cells by intracellular signal transduction via activation of diacylglycerol kinase, protein kinase C, phospholipase C, Ca(2+)-calmodulin, and nuclear transcription factor kappa B.

Background/Aims: The priming mechanism of macrophages to secrete cytokines in acute pancreatitis is important for remote organ failure following septic complication. The effects of novel carboxamide derivative, IS-741, on neutrophil chemoattractant production by bronchoalveolar macrophages were studied in rats with cerulein-induced pancreatitis complicated by sepsis. Methods: Pancreatitis was induced by four intramuscular injections of cerulein (50 µg/kg at 1-hour intervals). Pancreatitis rats were injected intraperitoneally with 10 mg/kg of lipopolysaccharide (LPS) 6 h following the first cerulein injection as a septic challenge. Pancreatitis rats received a continuous intravenous injection of IS-741 (3 mg/kg/h) 30 min before the septic challenge. Results: Intense mononuclear cell infiltration and lung hemorrhage occurred in untreated pancreatitis rats complicated with sepsis, but hemorrhage was not seen in septic pancreatitis rats receiving a continuous intravenous injection of IS-741 shortly before sepsis induction. The IS-741-treated rats had lower serum concentrations of cytokine-induced neutrophil chemoattractant (CINC), as well as fewer the pulmonary neutrophils and infiltrates immunoreactive for CINC or Mac-1 (CD11b/CD18). Conclusion: The novel carboxamide derivative IS-741 reduced CINC production by bronchoalveolar macrophages and effectively prevented pancreatitis-associated lung injury following the septic challenge.

Little is known regarding the role of ␥␦ ؉ T cells in organ transplantation. We previously reported that immunologic unresponsiveness is induced by prior donor-specific blood transfusion (DST) in rat hepatic allografts. We investigated the phenotype and distribution of ␥␦ ؉ T cells in the hepatic allograft, spleen, and peripheral blood of recipient rats with immunologic unresponsiveness induced by DST. ␥␦ ؉ T cells were enumerated in allograft livers and spleens by immunostaining and in blood by flow cytometric analysis. The phenotype of ␥␦ ؉ T cells was determined using CD45RC isoforms derived from alternative mRNA splicing. The great majority of mature human T lymphocytes express the ␣␤ T-cell receptor (TCR). A small population, which represents 0.5% to 16% of T lymphocytes in peripheral blood and lymphoid tissues, express the ␥␦ TCR. 1 Despite the fact that ␥␦ ϩ T cells are mature lymphocytes and have several phenotypic similarities to ␣␤ ϩ T cells, the biologic role of this cell population is still poorly understood. 2 ␥␦ ϩ T cells recognize class I and class II major histocompatibility complex (MHC) antigens. 3,4 However, non-MHC restricted cytotoxicity of ␥␦ ϩ T cells has been reported. 5 Thus, the preferential ligands for ␥␦ ϩ T cells have not yet been identified.Alloreactive ␥␦ ϩ T cells can trigger a rejection response, 6 and in fact, ␥␦ ϩ T cells are known to be involved in human renal allograft rejection 7 and in graft vascular disease. 8 However, ␥␦ ϩ T cells also may participate in cardiac allograft tolerance. 9,10 ␥␦ ϩ T cells from mice or rats selectively depleted of ␣␤ T cells seem to be unable to mount an alloreactive response, 11 but the role of ␥␦ ϩ T cells in organ transplantation is not clear.Leukocyte common antigen (LCA), CD45, has many isoforms derived from alternative mRNA splicing. 12 Six different CD45 isoforms have been identified from cDNA clones (usage of ABC, AB, BC, B, C, and O exons), and another is inferred (A exon alone) from hybridization studies. 13 Yang et al., 14 demonstrated functional maturation of recent thymic emigrants in the periphery, showing that the development of alloreactivity correlates with cyclic expression of CD45RC isoforms. LCA isoforms are associated with functional T-cell subsets including memory, activated, and alloreactive T cells. 15 In the rat, ␥␦ ϩ T-cell subsets are distinguished by membrane expression of the high (CD45RC ϩ ) and low (CD45RC Ϫ ) molecular weight isoforms of CD45. 16 We previously showed that persistent infiltration of CD45RC Ϫ CD4 ϩ T cells, Th2-like effector cells, was associated with immunologic unresponsiveness in rat hepatic allografts when animals were pretreated with donor-specific transfusion (DST) before transplantation. 17 However, little is known about the phenotype of ␥␦ ϩ T cells based on CD45RC expression in transplant immunology. The present study was undertaken to investigate the phenotype and distribution of ␥␦ ϩ T cells in rat hepatic allografts during acute rejection and their possible role in immunologic unrespons...