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Query: UMLS:C0019158 (hepatitis)
 30,205 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tumor necrosis factor (TNF, TNFalpha) is implicated in various pathophysiological processes and can be either protective, as in host defense, or deleterious, as in autoimmunity or toxic shock. To uncover the in vivo functions of TNF produced by different cell types, we generated mice with TNF ablation targeted to various leukocyte subsets. Systemic TNF in response to lipopolysaccharide was produced mainly by macrophages and neutrophils. This source of TNF was indispensable for resistance to an intracellular pathogen, Listeria, whereas T-cell-derived TNF was important for protection against high bacterial load. Additionally, both T-cell-derived TNF and macrophage-derived TNF had critical and nonredundant functions in the promotion of autoimmune hepatitis. Our data suggest that T-cell-specific TNF ablation may provide a therapeutic advantage over systemic blockade.
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PMID:Distinct and nonredundant in vivo functions of TNF produced by t cells and macrophages/neutrophils: protective and deleterious effects. 1566 62

Apoptosis mediated via extrinsic or intrinsic pathways is essential for maintaining cellular homeostasis in the liver. The extrinsic pathway is triggered from the cell surface by engagement of death receptors as CD95, TRAIL (TNF-related apoptosis inducing ligand) and TNF (tumour necrosis factor) or TGF-beta (transforming growth factor beta) receptors. The intrinsic pathway is initiated from the mitochondria and can be influenced by Bcl-2 family members. Both pathways are intertwined and play a physiological role in the liver. Dysregulation of apoptosis pathways contributes to diseases as hepatocellular carcinoma, viral hepatitis, autoimmune hepatitis, ischaemia-reperfusion injury, iron or copper deposition disorders, toxic liver damage and acute liver failure. The apoptosis defects are often central pathogenetic events; hence molecular mechanisms of apoptosis give not only insight into disease mechanisms but also provide potential corresponding therapeutic candidates in liver disease. The focus of this review is the identification of apoptotic signalling components in the liver as therapeutic targets.
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PMID:Modulation of apoptosis as a target for liver disease. 1575 84

Imatinib exerts potent antileukemic effects in vitro and in vivo. Despite its well known antitumor activity, the potential of imatinib for the treatment of inflammatory diseases remains elusive so far. Our current report provides strong evidence that imatinib has potent antiinflammatory effects. It potently inhibits LPS- and Con A-induced TNF-alpha production by human myeloid cells in vitro (peripheral blood mononuclear cells, CD14-selected monocytes, and monocyte-derived macrophages). Of note, the production of the antiinflammatory cytokine IL-10 was not significantly regulated by imatinib. In line with this observation, phosphorylation of IkappaB and subsequent DNA binding of NF-kappaB, which is critically involved in TNF-alpha, but not IL-10 expression, was reduced by imatinib. Using several murine models of acute hepatitis, we could corroborate our in vitro findings, as imatinib prevented macrophage- and TNF-alpha-dependent inflammatory damage of the liver induced by injection of either Con A or d-galactosamine/LPS by inhibition of hepatic TNF-alpha production. Of note, d-galactosamine/TNF-induced hepatitis was not affected, showing that imatinib does not directly inhibit TNF-alpha-induced hepatocellular cell death. These findings suggest a potent antiinflammatory role of imatinib by modulation of TNF-alpha production in monocytes/macrophages. This observation might be of therapeutic value for the treatment of TNF-mediated diseases.
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PMID:The kinase inhibitor imatinib mesylate inhibits TNF-{alpha} production in vitro and prevents TNF-dependent acute hepatic inflammation. 1617 51

Acute fulminant liver failure is a serious worldwide health problem. Despite maximal supportive intensive care treatment, the disease offers a poor prognosis, with mortality rates of >80%. We have previously shown that a broad-spectrum inhibitor of matrix metalloproteinases (MMPs) confers complete protection in a mouse model of TNF-induced lethal hepatitis, thereby suggesting the possibility of protecting cancer patients against the deleterious side effects of TNF therapy. In our search for the individual matrix metalloproteinases involved, we found that the recently generated MMP-8-deficient mice are significantly protected against TNF-induced acute hepatitis. In contrast to their wild-type counterparts, MMP-8-null mice display very little hepatocyte necrosis and apoptosis, resulting in a much better survival outcome. We found that these animals clearly display impaired leukocyte influx into the liver and no release of the neutrophil-specific, LPS-induced CXC chemokine. Our findings provide evidence that MMP-8 plays an essential role in acute liver failure and might be a promising new target for the treatment for this illness.
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PMID:Resistance of collagenase-2 (matrix metalloproteinase-8)-deficient mice to TNF-induced lethal hepatitis. 1630 74

The present report is devoted to drawing up and disseminating specific recommendations for the use of anti-TNF-alpha therapies in patients with rheumatoid arthritis (RA) in Italy. The document reports and discusses the published literature concerning the criteria for inclusion, assessment of response and for withdrawal of treatment with TNF blocking agents in RA. Several specific points concerning more sensitive warnings are discussed: tuberculosis, hepatitis, lymphoma, and cardiovascular risk and induction of autoimmunity. The recommendations are summarized in an 8-point table approved by the executive committee of the Italian Society for Rheumatology.
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PMID:Recommendations for the use of biologic (TNF-alpha blocking) agents in the treatment of rheumatoid arthritis in Italy. 1695 32

LIGHT is a member of the TNF superfamily, which is transiently expressed on the surface of activated T lymphocytes and immature dendritic cells. Its known receptors are herpesvirus entry mediator (HVEM) prominently in T lymphocytes, and lymphtoxin beta receptor (LTbetaR) in stromal cells or nonlymphoid hematopoietic cells. Previous studies have shown that overexpression of LIGHT on T cells could lead to autoimmune reaction including lymphocytes activation, inflammation, and tissue destruction. To address the role of LIGHT/HVEM signaling in autoimmune hepatitis, an experimental colitis model induced by intravenous administration of concanavalin A (ConA) was given a soluble LTbetaR-Ig fusion protein as a competitive inhibitor of LIGHT/HVEM pathway. Marked elevation of LIGHT expression was detected in isolate intrahepatic leukocytes (IHLs) of the experimental animal. Treatment with LTbetaR-Ig significantly attenuated the progression and histological manifestations of the hepatic inflammation and reduced the production of inflammatory cytokines including TNF-alpha, IFN-gamma. Moreover, LTbetaR-Ig treatment significantly down-regulated LIGHT expression, leading to reduced lymphocytes (particularly CD4+ T cells), infiltrating into the hepatic inflammation and inhibited NF-kappaB activation and expression. We postulated that blockade of LIGHT/HVEM signaling by LTbetaR-Ig may ameliorate hepatitis by down-regulating LIGHT expression, and therefore we envision that LTbetaR-Ig would prove to a promising strategy for the clinical treatment of human autoimmune hepatitis.
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PMID:Lymphtoxin beta receptor-Ig protects from T-cell-mediated liver injury in mice through blocking LIGHT/HVEM signaling. 1701 45

Regional differences in the manifestations of autoimmune hepatitis underscore the importance of genetic and/or environmental factors in its expression. The -308 polymorphism of TNF-A increases susceptibility to type 1 autoimmune hepatitis; HLA DRB1*13 is an important risk factor in South America; and DRB1*07 characterizes type 2 autoimmune hepatitis. Minocycline and mesalazine can trigger the disease, and interferon therapy can accentuate autoimmune manifestations. Autoimmune cholangitis in Japan is similar to primary biliary cirrhosis, and assays for carbonic anhydrase II lack diagnostic specificity. Perinuclear antineutrophil cytoplasmic antibodies are reactive to diverse nuclear antigens, but high mobility nonhistone chromosomal proteins may be important targets in autoimmune hepatitis. T cells can cross-react with viral and host peptides, and the candidacy of glutathione S-transferases as target autoantigens has been weakened. A murine model of PBC will be useful in studying mechanisms of autoreactivity, and cyclosporine has shown promise in the treatment of children with autoimmune hepatitis. Recurrence after liver transplantation is common, and it may require retransplantation. The human transplantation model will be valuable in understanding the host-and organ-specific contributions to disease expression.
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PMID:Autoimmune liver disease. 1702 84

LT, LIGHT, and TNF are core family members of the TNFR superfamily of cytokines. LT and LIGHT, produced primarily by lymphocytes, interact with LTbetaR expressed by stromal and epithelial cells. Extensive studies over the last decade have revealed a critical role of LT-LTbetaR interactions for organogenesis and maintenance of the secondary lymphoid organs and in the generation of an efficient humoral immune response to various pathogens. LTbetaR's function beyond the lymphoid organs shows valuable potential yet remains largely undefined. Recent studies indicate that LTbetaR signaling is required for liver regeneration, hepatitis, and hepatic lipid metabolism. The balance of beneficial and detrimental effects of LTbetaR is critical for understanding the mechanisms of autoimmune disease and liver function and may open a new avenue for therapeutic intervention. This review will discuss recent advances in understanding LTbetaR's role in various human and murine disease models while focusing on its regulation of and implications in various liver related diseases.
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PMID:The role of lymphotoxin receptor signaling in diseases. 1789 93

Conserved molecular patterns of microbial pathogens, such as lipopolysaccharide (LPS) and cytosine-phosphate-guanine (CpG) DNA motifs are important signals for receptor-mediated activation of innate immune cells. It has been shown that the liver-specific transcription-blocking d-galactosamine (D-GalN) severely sensitizes to the lethal effects of LPS and CpG DNA. Lethality of LPS or CpG DNA in GalN-treated mice is entirely due to TNF-alpha, which leads to liver cell apoptosis and acute liver failure. We report that also polyinosinic-polycytidylic acid [poly(I:C)], a TLR-3 agonist, induces systemic TNF in mice. The increases of hepatic enzymes and induction of death induced by LPS, CpG DNA, and poly(I:C) in D-GalN sensitized mice are completely blocked by neutralizing anti-TNF-alpha antibodies and absent in TNF receptor p55-knockout mice. Our results provide direct evidence that poly(I:C) induces TNF-alpha in d-GalN sensitized mice, which leads to severe, acute, and TNF-dependent lethal hepatitis.
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PMID:Tumor necrosis factor alpha mediates the lethal hepatotoxic effects of poly(I:C) in D-galactosamine-sensitized mice. 1833 98

Anti-TNF agents are increasingly being used for a rapidly expanding number of rheumatic and systemic autoimmune diseases. As a result of this use, and of the longer follow-up periods of treatment, there are a growing number of reports of the development of autoimmune processes related to anti-TNF agents. The clinical characteristics, outcomes, and patterns of association with the different anti-TNF agents used in all reports of autoimmune diseases developing after TNF-targeted therapy, were analyzed through a baseline Medline search of articles published between January 1990 and May 2008 (www.biogeas.org). A total of 379 cases of autoimmune diseases secondary to TNF-targeted therapies were identified. The anti-TNF agents were administered for rheumatoid arthritis in more than 80% of cases. The use of anti-TNF agents has been associated with an increasing number of cases of autoimmune diseases, principally cutaneous vasculitis, lupus-like syndrome, systemic lupus erythematosus and interstitial lung disease. Other autoimmune diseases associated with TNF-targeted therapies have been recently described, e.g. sarcoidosis, antiphospholipid syndrome-related features, and autoimmune hepatitis or uveitis. Large, prospective, postmarketing studies are required to evaluate the risk of developing autoimmune diseases in patients receiving TNF-targeted therapies.
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PMID:Autoimmune diseases induced by TNF-targeted therapies. 1902 67


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