title: Induction of heme oxygenase-1 attenuates lipopolysaccharide-induced inflammasome activation in human gingival epithelial cells.
abstract: Interleukin-1β (IL-1β) is a pathogenic factor for the destruction of periodontal tissue in periodontitis. The processing of IL-1β is regulated by cytosolic machinery termed as the inflammasome, which recruits and activates caspase-1 and then cleaves pro-IL-1β to produce mature IL-1β. Porphyromonas gingivalis (P. gingivalis) infection and lipopolysaccharide (LPS) have been shown to activate the NLRP3 inflammasome and stimulate IL-1β production in human oral cells. Heme oxygenase-1 (HO-1) is an ubiquitous cytoprotective enzyme. The products of HO-1 exhibit protective biological activities, including antioxidant and anti-inflammatory effects. In the present study, we investigated the hypothesis that the induction of HO-1 inhibits the activation of the inflammasome and protects against LPS-induced inflammatory damage in cultured human gingival epithelial cells (GECs). Our results revealed that LPS induced the overexpression of the inflammasome components, NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) and caspase-1, by western blot analysis. Co-immunoprecipitation analysis indicated that LPS increased the binding of NLRP3 and ASC, and confocal imaging revealed that LPS increased the immunostaining and co-localization of ASC and caspase-1, indicating that LPS enhanced the assembly/formation of the inflammasome components. Hemin, a potent HO-1 inducer, blocked the LPS-induced overexpression and the formation of the NLRP3 inflammasome. Furthermore, hemin also inhibited the LPS-induced increase in the production of IL-1β, as shown by enzyme-linked immunosorbent assay and blocked the nuclear translocation of pro-inflammatory nuclear factor-κB (NF-κB), as shown by confocal assays. As a result, hemin protected the cells from LPS-induced damage, which was demonstrated by the immunostaining pattern of the cell junction protein, E-cadherin. LPS produced a disturbed staining pattern of E-cadherin, suggesting the disruption of epithelial integrity, which was abolished in the hemin-treated cells. In conclusion, our data demonstrate that the induction of HO-1 by hemin attenuates LPS-induced inflammatory damage in human GECs through the inhibition of inflammasome activation.
authors: Department of Stomatology, The First Affiliated Hospital, Henan University of Science and Technology, Luoyang, Henan 471003, P.R. China.
authors: Hong
authors: H
authors: Li
authors: Department of Stomatology, The First Affiliated Hospital, Henan University of Science and Technology, Luoyang, Henan 471003, P.R. China.
authors: Xiaoli
authors: X
authors: Zhou
authors: Department of Stomatology, The First Affiliated Hospital, Henan University of Science and Technology, Luoyang, Henan 471003, P.R. China.
authors: Jianli
authors: J
authors: Zhang
mesh_terms: D053468:CARD Signaling Adaptor Proteins; D015820:Cadherins / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D020170:Caspase 1 / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004790:Enzyme Induction / Q000187:drug effects; D004847:Epithelial Cells / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology*; D005881:Gingiva / Q000473:pathology*; D051547:Heme Oxygenase-1 / Q000096:biosynthesis*; D006427:Hemin / Q000494:pharmacology; D006801:Humans; D058847:Inflammasomes / Q000378:metabolism*; D053583:Interleukin-1beta / Q000096:biosynthesis; D008070:Lipopolysaccharides / Q000494:pharmacology*; D016328:NF-kappa B / Q000378:metabolism; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein
chemical_list: D053468:CARD Signaling Adaptor Proteins; D015820:Cadherins; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D058847:Inflammasomes; D053583:Interleukin-1beta; D008070:Lipopolysaccharides; D016328:NF-kappa B; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C453881:NLRP3 protein, human; C402202:PYCARD protein, human; D006427:Hemin; D051547:Heme Oxygenase-1; D020170:Caspase 1