Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019158 (hepatitis)
 30,205 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Concanavalin A (Con A) induces T-cell-mediated hepatic injury in vivo, although Con A-stimulated lymphocytes are not cytotoxic to normal hepatocytes in vitro. This contradiction makes the mechanism of Con A-induced hepatitis elusive. In this study, we demonstrate that Con A but not tumor necrosis factor alpha (TNF-alpha), interferon gamma (IFN-gamma), or actinomycin D (ActD) induced the susceptibility of hepatocytes to activated autologous lymphocyte cytotoxicity. Con A sensitized hepatocytes within 30 minutes after the stimulation in a dose-dependent fashion. The cytotoxicity was dose-dependently inhibited by either a Con A ligand, alpha-methyl mannoside, or a perforin inhibitor, concanamycin A (CMA), but not by anti-Fas ligand antiserum. In addition, Con A-treated hepatocytes were not sensitive to autologous activated lymphocytes from a perforin-deficient mouse, while hepatocytes from lpr mice were sensitized by Con A. In fact, Con A did not induce liver injury in perforin-deficient mice within the concentration employed in this study. Therefore, we conclude that the cytotoxicity was mediated through perforin/granzymes but not through the Fas/Fas ligand pathway. The cytotoxicity was inhibited by anti-intercellular adhesion molecule-1 (ICAM-1)/LFA-1 antibodies, but not by anti-VCAM-1/VLA-4 antibodies, both in vitro and in vivo. The cytotoxicity appears to be caused by CD8+ T cells; however, the cytokines from activated CD4+ T cells play a critical role in the pathogenesis of the hepatitis in vivo, because administration of anti-IFN-gamma antibodies inhibited the occurrence of the hepatitis. In conclusion, Con A-induced hepatitis is thought to be dominantly mediated by a perforin-dependent pathway through ICAM-1/LFA-1 interaction.
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PMID:Concanavalin A induces perforin-mediated but not Fas-mediated hepatic injury. 878 46

Mouse hepatitis virus (MHV) provides an excellent animal model for the study of the immunopathological mechanisms involved in hepatic viral diseases. We previously generated an attenuated viral variant, YAC-MHV3, which induces a subclinical disease and recovery within 15 days. In contrast, the L2-MHV3 strain induces the development of a fulminant hepatitis, leading to death within 3 days. In this paper, we document intrahepatic and splenic T cell subpopulations involved in the hepatitis process and viral elimination identified in attenuated or pathogenic MHV3-infected C57BL/6 mice. Percentages of intrahepatic CD4(+) cells decreased in attenuated YAC-MHV3-infected mice, while they increased in mice infected with pathogenic L2-MHV3, compared with uninfected animals. Moreover, in YAC-MHV3-infected mice, the percentages of intrahepatic CD8(+) cells slightly decreased at 24 h pi, then increased until 15 days pi. In contrast, the CD4/CD8 ratios of splenic lymphoid subpopulations increased in the first days of infection and returned to normal values at 15 days pi. Intrahepatic NK1.1(+)alphabeta - TCR(inter) cells decreased in both virally infected groups of mice, while CD4(+)alphabeta - TCR(inter) LFA-1(high) cells increased in L2-MHV3-infected mice, in contrast with what was seen in YAC-MHV3-infected mice. However, these cells became anergic following Con A or PHA stimulation. Ex vivo studies showed that only the intrahepatic CD8(+) cells that were increased in YAC-MHV3-infected mice could be stimulated by lectins. In addition, in vitro viral infections revealed that L2-MHV3 viral infection led to an increase of intrahepatic CD4(+)alphabeta - TCR(inter) cells in the absence of CD8(+) cells only. These results indicate that the attenuated phenotype of the YAC-MHV3 virus is related to two different mechanisms: the first involves no increase of intrahepatic CD4(+)alphabeta - TCR(inter) or NK-T cells, while the second favors the recruitment and activation of CD8(+) cells in liver. The results are discussed in relation to the integrity of intrahepatic immune tolerance mechanisms and immune-mediated viral elimination.
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PMID:Recovery from mouse hepatitis virus infection depends on recruitment of CD8(+) cells rather than activation of intrahepatic CD4(+)alphabeta(-)TCR(inter) or NK-T cells. 1172 27

Viral hepatitis affects more than 2 billion people worldwide. In particular, no effective treatment exists to abrogate death and liver damage in fulminant hepatitis. Activation of T cells is an initial and critical event in the pathogenesis of liver damage in autoimmune and viral hepatitis. The precise molecular mechanisms that induce T cell-mediated hepatocyte injury remain largely unclear. In mice, T cell-dependent hepatitis and acute liver damage can be modeled using ConA. In this study, we examined the role of the adhesion receptor LFA-1 in ConA-induced acute hepatic damage using LFA-1(-/-) (CD11a) mice. Massive liver cell apoptosis and metabolic liver damage were observed in LFA-1(+/+) mice following ConA injection. By contrast, LFA-1(-/-) mice were completely resistant to ConA-induced hepatitis and none of the LFA-1(-/-) mice showed any hepatic damage. Whereas activated hepatic T cells remained in the liver in LFA-1(+/+) mice, activated T cells were rapidly cleared from the livers of LFA-1(-/-) mice. Mechanistically, T cells from LFA-1(-/-) mice showed markedly reduced cytotoxicity toward liver cells as a result of impaired, activation-dependent adhesion. Importantly, adoptive transfer of hepatic T cells from LFA-1(+/+) mice, but not from LFA-1(-/-) mice, sensitized LFA-1(-/-) mice to ConA-induced hepatitis. Thus, LFA-1 expression on T cells is necessary and sufficient for T cell-mediated liver damage in vivo. These results provide the first genetic evidence on an adhesion receptor, LFA-1, that has a crucial role in fulminant hepatitis. These genetic data identify LFA-1 as a potential key target for the treatment of T cell-mediated hepatitis and the prevention of liver damage.
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PMID:Essential role of the adhesion receptor LFA-1 for T cell-dependent fulminant hepatitis. 1247 Nov 45

The most common organ-specific manifestation of cytomegalovirus (CMV) infection after liver transplantation is hepatitis. Here we retrospectively describe the detailed virological, histological, immunological, and clinical findings associated with CMV infection in 229 consecutive adult liver transplantation patients. CMV infection was diagnosed by pp65 antigenemia. From 439 liver biopsies, CMV antigens were demonstrated by immunohistochemistry and CMV DNA by hybridization. The Banff criteria were used for histology. The expression of various adhesion molecules (intercellular adhesion molecule-1 [ICAM-1], vascular cell adhesion molecule-1 [VCAM-1], endothelial leukocyte adhesion molecule-1 [ELAM-1]), their ligands (leukocyte function antigen-1 [LFA-1], very late antigen-4 [VLA-4], Sialyl-LewisX-molecule [SLeX]), and lymphoid activation markers (major histocompatibility complex [MHC] Class II, interleukin-2-receptor [IL-2R]) was demonstrated by immunohistochemistry. CMV infection of the transplant occurred in 26 patients (11% of all 229 patients and 17% of the 151 patients with liver biopsy). The incidence was higher among seronegative (26%) than in seropositive recipients (9%), but most cases 18/26 (70%) were reactivations. The CMV pp65 antigenemia levels were usually high in primary infections (893+/-1069, range 50-3000 pp65+cells), but varied widely in reactivations (388+/-740, range 3-3000). The histological Banff score was slightly increased (2.3+/-0.9). Microabscesses, lymphocytic infiltration, Kupffer cell reaction, and parenchymal alterations were common but viral inclusions rare. CMV significantly (P<0.05) increased ICAM-1 and VCAM-1 expression and the number of LFA-1, VLA-4, and Class II-positive lymphocytes in the graft. All CMV infections were successfully treated with antivirals. Intragraft CMV infection had no influence on the long-term outcome, but biliary complications were common. In conclusion, CMV infection of the liver transplant occurred both in primary infection and in reactivation, and also in the cases with low pp65 antigenemia levels. Microabscesses and other histological alterations were common but viral inclusions rare. Increased adhesion molecule expression was associated with lymphocyte infiltration. Successfully treated CMV hepatitis had no influence on the long-term clinical outcome.
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PMID:Cytomegalovirus infection of the liver transplant: virological, histological, immunological, and clinical observations. 1662 17