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Query: UMLS:C0001511 (Adhesion)
 5,955 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Adhesion to and penetration through the sinusoidal vascular endothelium is a mandatory step for leukocyte migration and accumulation at sites of liver inflammation. This leukocyte trafficking is controlled by interactions between adhesion molecules on leukocytes and corresponding ligands on endothelial cells. We have analyzed the in situ distribution of two recently described vascular adhesion molecules (i.e., endothelial leukocyte adhesion molecule-1 and vascular cell adhesion molecule-1) and of the lymphocyte "homing" receptor cluster of differentiation antigen-44 in normal and inflamed liver biopsy specimens. Endothelial leukocyte adhesion molecule-1 and vascular cell adhesion molecule-1 were absent from normal liver tissue, but they were strongly expressed on sinusoidal lining cells in inflammatory liver disease. Endothelial leukocyte adhesion molecule-1 expression predominated diffusely throughout the liver parenchyma in acute hepatitis; in contrast, vascular cell adhesion molecule-1 was mainly expressed in areas of periportal and intralobular inflammation in chronic active and persistent hepatitis. The "homing" receptor cluster of differentiation antigen-44 was weakly expressed on scattered mononuclear cells and on sinusoidal lining cells in normal liver tissue, but it was strongly up-regulated on mononuclear inflammatory cells and sinusoidal lining cells in acute and chronic hepatitis. In addition, reactivity for the cluster of differentiation antigen-44 was found on the membranes of variously sized clusters of hepatocytes in biopsy specimens with acute hepatitis. De novo or up-regulated expression of these adhesion molecules on sinusoidal lining cells in inflamed liver biopsy specimens indicates that these cells actively modulate their phenotype in response to environmental factors, thus playing a key role in the recruitment of leukocytes in acute and chronic liver inflammation.
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PMID:Vascular adhesion molecules in acute and chronic liver inflammation. 137 Sep 47

Adhesion molecules such as intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) have been implicated in the pathogenesis of various inflammatory liver disease states, including viral and autoimmune hepatitis as well as liver allograft rejection. Tumor necrosis factor alpha (TNF-alpha) is an inflammatory cytokine known to up-regulate adhesion molecules as well as major histocompatibility complex (MHC) class I expression, and has been demonstrated to be important in the rejection of vascularized organ allografts. The current studies address the effect of TNF-alpha and the role of ICAM-1 expression on liver cell immunogenicity in vitro in mixed lymphocyte hepatocyte culture (MLHC), in vitro in mixed lymphocyte liver nonparenchymal cell culture (MLNPC), in vivo in hepatocyte sponge matrix allografts (HC-SMA), and in vivo in liver nonparenchymal cell sponge matrix allografts (NPC-SMA). Purified allogeneic hepatocytes (HC) and liver nonparenchymal cells (NPC) under naive, unstimulated conditions demonstrated different profiles of MHC antigen and adhesion molecule expression, but both liver cell populations stimulated the proliferation and development of allospecific cytotoxic effectors in vitro and in vivo. Despite significant up-regulation of MHC class I and ICAM-1 on both HC and liver NPCs by in vivo treatment with TNF-alpha, the immunogenicity of TNF-alpha-stimulated liver cells was not appreciably different from naive, unstimulated liver cells. In contrast, ICAM-1-negative HC and NPCs were significantly less immunogenic both in terms of lymphocyte proliferative responses and the generation of allospecific cytolytic effectors. These results suggest that constitutive expression of ICAM-1 enhances the immunogenicity of "donor" liver cells but is not absolutely required to elicit immune responses to allogeneic liver cells. Further studies to determine the role of adhesion molecule expression on trafficking of host immune cells to the liver and the role of adhesion molecule expression by host cells are required to clarify their role in immune responses to liver cells.
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PMID:Effect of tumor necrosis factor alpha and intercellular adhesion molecule-1 expression on immunogenicity of murine liver cells in mice. 969 13

Polymorphonuclear leukocytes (neutrophils) are a vital part of the innate immune response to microbial infections and tissue trauma, e.g., ischemia-reperfusion injury, in many organs including the liver. However, an excessive inflammatory response can lead to a dramatic aggravation of the existing injury. To design interventions, which selectively target the detrimental effects of neutrophils, a detailed understanding of the pathophysiology is critical. Systemic or local exposure to proinflammatory mediators causes activation and priming of neutrophils for reactive oxygen formation and recruits them into the vascular beds of the liver without causing tissue injury. However, generation of a chemotactic signal from the parenchyma will trigger extravasation and an attack on target cells (e.g., hepatocytes). Adhesion to the target induces degranulation with release of proteases and formation of reactive oxygen species including hydrogen peroxide and hypochlorous acid, which can diffuse into hepatocytes and induce an intracellular oxidant stress and mitochondrial dysfunction. Various neutrophil-derived proteases are involved in transmigration and cell toxicity but can also promote the inflammatory response by processing of proinflammatory mediators. In addition, necrotic cells release mediators, e.g., high-mobility group box-1, which further promotes neutrophilic hepatitis and tissue damage. On the basis of these evolving insights into the mechanisms of neutrophil-mediated liver damage, the most selective strategies appear not to interfere with the cytotoxic potential of neutrophils, but rather strengthen the target cells' defense mechanisms including enhancement of the intracellular antioxidant defense systems, activation of cell survival pathways, or initiation of cell cycle activation and regeneration.
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PMID:Mechanisms of Liver Injury. II. Mechanisms of neutrophil-induced liver cell injury during hepatic ischemia-reperfusion and other acute inflammatory conditions. 1668 79