International immunopharmacology
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Int. Immunopharmacol. · Mar 2001
ReviewFunctions of anaphylatoxin C5a in rat liver: direct and indirect actions on nonparenchymal and parenchymal cells.
Growing evidence obtained in recent years indicates that anaphylatoxin C5a receptors (C5aR) are not restricted to myeloid cells but are also expressed on nonmyeloid cells in different tissues such as brain, lung, skin and liver. In contrast to its well-defined systemic functions, the actions of anaphylatoxins in these organs are poorly characterized. The liver can be a primary target organ for the C5a anaphylatoxin since the liver is directly connected to the gut, via the mesenteric veins and portal vein which is a main source of complement activating lipopolysaccharides (LPS). ⋯ Under pathological conditions, C5aR was found to be upregulated in various organs including the liver. Simulation of inflammatory conditions by treatment of rats with IL-6, a main inflammatory mediator in the liver, caused a de novo expression of functional C5aR in HC. In livers of IL-6-treated rats, C5a initiated glucose output from HC and perhaps other HC-specific defense reactions directly without the intervention of soluble mediators from nonparenchymal cells.
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Int. Immunopharmacol. · Jan 2001
Comparative StudyDifferential effect of thalidomide and dexamethasone on the transcription factor NF-kappa B.
Thalidomide was initially used as a sedative during pregnancy but was withdrawn from the market due to its teratogenic effects. In vitro studies have shown that thalidomide inhibits tumour necrosis factor alpha (TNF-alpha) mRNA expression and protein production by mitogen-stimulated macrophages and activated T cells. Even at the highest concentration (10-1 mM) tested, however, TNF-alpha levels are inhibited only partially and the mechanism of action is unknown. ⋯ In concurrent experiments, dexamethasone was found to reduce NF-kappa B expression in a dose-dependent manner with maximal inhibition at the highest dose tested (10(-1) mM). TNF-alpha gene expression is controlled by at least three separate transcription factors that are involved in binding to the promoter region. These observations suggest that thalidomide does not act directly on NF-kappa B and therefore inhibits TNF-alpha production through another independent mechanism.