title: Adenovirus membrane penetration activates the NLRP3 inflammasome.
abstract: Adenovirus type 5 (Ad5) infection of macrophages results in rapid secretion of interleukin-1β (IL-1β) and is dependent on the inflammasome components NLRP3 and ASC and the catalytic activity of caspase-1. Using lentivirus-expressed short hairpin RNA (shRNA) and competitive inhibitors, we show that Ad-induced IL-1β release is dependent upon Toll-like receptor 9 (TLR9) sensing of the Ad5 double-stranded DNA (dsDNA) genome in human cell lines and primary monocyte-derived macrophages but not in mouse macrophages. Additionally, a temperature-sensitive mutant of Ad5 unable to penetrate endosomal membranes, ts1, is unable to induce IL-1β release in TLR2-primed THP-1 cells, suggesting that penetration of endosomal membranes is required for IL-1β release. Disruption of lysosomal membranes and the release of cathepsin B into the cytoplasm are required for Ad-induced NLRP3 activation. Ad5 cell entry also induces reactive oxygen species (ROS) production, and inhibitors of ROS prevent Ad-induced IL-1β release. Ad5 activation of NLRP3 also induces necrotic cell death, resulting in the release of the proinflammatory molecule HMGB1. This work further defines the mechanisms of virally induced inflammasome activation.
authors.affiliation: Department of Microbiology and Immunology, Loyola University Chicago, Stritch School of Medicine, Building 105, Room 3818, 2160 S. First Avenue, Maywood, IL 60153, USA.
authors.forename: A U
authors.initials: AU
authors.lastname: Barlan
authors.forename: T M
authors.initials: TM
authors.lastname: Griffin
authors.forename: K A
authors.initials: KA
authors.lastname: McGuire
authors.forename: C M
authors.initials: CM
authors.lastname: Wiethoff
mesh_terms: D000260:Adenoviruses, Human / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity*; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002401:Cathepsin B / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000821:virology*; D002478:Cells, Cultured; D024243:HMGB1 Protein; D006801:Humans; D007249:Inflammation / Q000276:immunology* / Q000821:virology; D053583:Interleukin-1beta / Q000378:metabolism; D008264:Macrophages / Q000276:immunology* / Q000821:virology*; D051379:Mice; D009000:Monocytes / Q000166:cytology / Q000276:immunology; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; D015398:Signal Transduction; D051217:Toll-Like Receptor 9 / Q000235:genetics / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D024243:HMGB1 Protein; D053583:Interleukin-1beta; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C453881:NLRP3 protein, human; D051217:Toll-Like Receptor 9; D002401:Cathepsin B