title: Involvement of TLR4/type I IL-1 receptor signaling in the induction of inflammatory mediators and cell death induced by ethanol in cultured astrocytes.
abstract: Activated astroglial cells are implicated in neuropathogenesis of many infectious and inflammatory diseases of the brain. A number of inflammatory mediators and cytokines have been proposed to play a key role in glial cell-related brain damage. Cytokine production seems to be initiated by signaling through TLR4/type I IL-1R (IL-1RI) in response to their ligands, LPS and IL-1beta, playing vital roles in innate host defense against infections, inflammation, injury, and stress. We have shown that glial cells are stimulated by ethanol, up-regulating cytokines and inflammatory mediators associated with TLR4 and IL-1RI signaling pathways in brain, suggesting that ethanol may contribute to brain damage via inflammation. We explore the possibility that ethanol, in the absence of LPS or IL-1beta, triggers signaling pathways and inflammatory mediators through TLR4 and/or IL-1RI activation in astrocytes. We show in this study that ethanol, at physiologically relevant concentrations, is capable of inducing rapid phosphorylation within 10 min of IL-1R-associated kinase, ERK1/2, stress-activated protein kinase/JNK, and p38 MAPK in astrocytes. Then an activation of NF-kappaB and AP-1 occurs after 30 min of ethanol treatment along with an up-regulation of inducible NO synthase and cyclooxygenase-2 expression. Finally, we note an increase in cell death after 3 h of treatment. Furthermore, by using either anti-TLR4- or anti-IL-1RI-neutralizing Abs, before and during ethanol treatment, we inhibit ethanol-induced signaling events, including NF-kappaB and AP-1 activation, inducible NO synthase, and cyclooxygenase-2 up-regulation and astrocyte death. In summary, these findings indicate that both TLR4 and IL-1RI activation occur upon ethanol treatment, and suggest that signaling through these receptors mediates ethanol-induced inflammatory events in astrocytes and brain.
authors.affiliation: Unidad de Patología Celular, Centro de Investigación Príncipe Felipe, Valencia, Spain.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Blanco
authors.forename: Soraya L
authors.initials: SL
authors.lastname: Vallés
authors.forename: Maria
authors.initials: M
authors.lastname: Pascual
authors.forename: Consuelo
authors.initials: C
authors.lastname: Guerri
mesh_terms: D000818:Animals; D019138:Antibodies, Blocking / Q000008:administration & dosage; D017209:Apoptosis / Q000187:drug effects; D001253:Astrocytes / Q000187:drug effects* / Q000276:immunology* / Q000473:pathology; D002478:Cells, Cultured; D051546:Cyclooxygenase 2 / Q000378:metabolism; D000431:Ethanol / Q000633:toxicity*; D018836:Inflammation Mediators / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D051381:Rats; D017472:Receptors, Interleukin-1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D053573:Receptors, Interleukin-1 Type I; D015398:Signal Transduction / Q000187:drug effects; D051197:Toll-Like Receptor 4 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D019138:Antibodies, Blocking; D018836:Inflammation Mediators; D017472:Receptors, Interleukin-1; D053573:Receptors, Interleukin-1 Type I; C495347:Tlr4 protein, rat; D051197:Toll-Like Receptor 4; D000431:Ethanol; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D051546:Cyclooxygenase 2; C489691:Ptgs2 protein, rat