title: Single-cell imaging of caspase-1 dynamics reveals an all-or-none inflammasome signaling response.
abstract: Inflammasome-mediated caspase-1 activation is involved in cell death and the secretion of the proinflammatory cytokine interleukin-1β (IL-1β). Although the dynamics of caspase-1 activation, IL-1β secretion, and cell death have been examined with bulk assays in population-level studies, they remain poorly understood at the single-cell level. In this study, we conducted single-cell imaging using a genetic fluorescence resonance energy transfer sensor that detects caspase-1 activation. We determined that caspase-1 exhibits all-or-none (digital) activation at the single-cell level, with similar activation kinetics irrespective of the type of inflammasome or the intensity of the stimulus. Real-time concurrent detection of caspase-1 activation and IL-1β release demonstrated that dead macrophages containing activated caspase-1 release a local burst of IL-1β in a digital manner, which identified these macrophages as the main source of IL-1β within cell populations. Our results highlight the value of single-cell analysis in enhancing understanding of the inflammasome system and chronic inflammatory diseases.
authors.affiliation: Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Ting
authors.initials: T
authors.lastname: Liu
authors.affiliation: Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan; PRESTO, Japan Science and Technology Agency, Chiyoda-ku, Tokyo 102-0076, Japan. Electronic address: bunbun@mol.f.u-tokyo.ac.jp.
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Yamaguchi
authors.affiliation: Laboratory for Integrative Genomics, RIKEN Center for Integrative Medical Sciences (IMS-RCAI), Yokohama, Kanagawa 230-0045, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Shirasaki
authors.affiliation: Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Shikada
authors.affiliation: Laboratory for Integrative Genomics, RIKEN Center for Integrative Medical Sciences (IMS-RCAI), Yokohama, Kanagawa 230-0045, Japan.
authors.forename: Mai
authors.initials: M
authors.lastname: Yamagishi
authors.affiliation: Department of Immunology, Faculty of Medicine, Kagawa University, Kita-gun, Kagawa 761-0793, Japan; Laboratory for Immune Regulation, World Premier International Research Center Initiative Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0861, Japan; Laboratory for Host Defense, RIKEN Research Center for Allergy and Immunology, Yokohama, Kanagawa 230-0045, Japan.
authors.forename: Katsuaki
authors.initials: K
authors.lastname: Hoshino
authors.affiliation: Laboratory for Immune Regulation, World Premier International Research Center Initiative Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0861, Japan; Laboratory for Host Defense, RIKEN Research Center for Allergy and Immunology, Yokohama, Kanagawa 230-0045, Japan.
authors.forename: Tsuneyasu
authors.initials: T
authors.lastname: Kaisho
authors.affiliation: PRESTO, Japan Science and Technology Agency, Chiyoda-ku, Tokyo 102-0076, Japan; Department of Physiology, Graduate School of Medicine, Yokohama City University, Yokohama, Kanagawa 236-0004, Japan.
authors.forename: Kiwamu
authors.initials: K
authors.lastname: Takemoto
authors.affiliation: Department of Molecular Bacteriology and Immunology, Graduate School of Medicine, University of the Ryukyus, Nakagami-gun, Okinawa 903-0125, Japan.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Suzuki
authors.affiliation: Laboratory for Histogenetic Dynamics, RIKEN Center for Developmental Biology, Chuo-ku, Kobe 650-0047, Japan.
authors.forename: Erina
authors.initials: E
authors.lastname: Kuranaga
authors.affiliation: Laboratory for Integrative Genomics, RIKEN Center for Integrative Medical Sciences (IMS-RCAI), Yokohama, Kanagawa 230-0045, Japan; Department of Human Genome Research, Kazusa DNA Research Institute, Kisarazu, Chiba 292-0818, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Ohara
authors.affiliation: Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan; CREST, Japan Science and Technology Agency, Chiyoda-ku, Tokyo 102-0076, Japan. Electronic address: miura@mol.f.u-tokyo.ac.jp.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Miura
mesh_terms: D000818:Animals; D020170:Caspase 1 / Q000502:physiology*; D002478:Cells, Cultured; D004789:Enzyme Activation; D006801:Humans; D058847:Inflammasomes / Q000378:metabolism*; D053583:Interleukin-1beta / Q000502:physiology; D007700:Kinetics; D008070:Lipopolysaccharides / Q000494:pharmacology; D017737:Macrophages, Peritoneal / Q000201:enzymology / Q000276:immunology; D008822:Mice, Transgenic; D015398:Signal Transduction; D059010:Single-Cell Analysis
chemical_list: D058847:Inflammasomes; D053583:Interleukin-1beta; D008070:Lipopolysaccharides; D020170:Caspase 1