title: Identification of QS-21 as an Inflammasome-activating Molecular Component of Saponin Adjuvants.
abstract: Many immunostimulants act as vaccine adjuvants via activation of the innate immune system, although in many cases it is unclear which specific molecules contribute to the stimulatory activity. QS-21 is a defined, highly purified, and soluble saponin adjuvant currently used in licensed and exploratory vaccines, including vaccines against malaria, cancer, and HIV-1. However, little is known about the mechanisms of cellular activation induced by QS-21. We observed QS-21 to elicit caspase-1-dependent IL-1β and IL-18 release in antigen-presenting cells such as macrophages and dendritic cells when co-stimulated with the TLR4-agonist adjuvant monophosphoryl lipid A. Furthermore, our data suggest that the ASC-NLRP3 inflammasome is responsible for QS-21-induced IL-1β/IL-18 release. At higher concentrations, QS-21 induced macrophage and dendritic cell death in a caspase-1-, ASC-, and NLRP3-independent manner, whereas the presence of cholesterol rescued cell viability. A nanoparticulate adjuvant that contains QS-21 as part of a heterogeneous mixture of saponins also induced IL-1β in an NLRP3-dependent manner. Interestingly, despite the role NLRP3 plays for cellular activation in vitro, NLRP3-deficient mice immunized with HIV-1 gp120 and QS-21 showed significantly higher levels of Th1 and Th2 antigen-specific T cell responses and increased IgG1 and IgG2c compared with wild type controls. Thus, we have identified QS-21 as a nonparticulate single molecular saponin that activates the NLRP3 inflammasome, but this signaling pathway may contribute to decreased antigen-specific responses in vivo.
authors.affiliation: From the Program in Innate Immunity, Division of Infectious Diseases and Immunology and.
authors.forename: Robyn
authors.initials: R
authors.lastname: Marty-Roix
authors.affiliation: From the Program in Innate Immunity, Division of Infectious Diseases and Immunology and.
authors.forename: Gregory I
authors.initials: GI
authors.lastname: Vladimer
authors.affiliation: From the Program in Innate Immunity, Division of Infectious Diseases and Immunology and.
authors.forename: Kimberly
authors.initials: K
authors.lastname: Pouliot
authors.affiliation: From the Program in Innate Immunity, Division of Infectious Diseases and Immunology and.
authors.forename: Dan
authors.initials: D
authors.lastname: Weng
authors.affiliation: the Laboratory of Nucleic Acid Vaccines, Department of Medicine, University of Massachusetts Medical School Worcester, Massachusetts 01605.
authors.forename: Rachel
authors.initials: R
authors.lastname: Buglione-Corbett
authors.affiliation: the Laboratory of Nucleic Acid Vaccines, Department of Medicine, University of Massachusetts Medical School Worcester, Massachusetts 01605.
authors.forename: Kim
authors.initials: K
authors.lastname: West
authors.affiliation: the Department of Microbial Pathogenesis, Boyer Center for Molecular Medicine, Yale University School of Medicine, New Haven, Connecticut 06510, and.
authors.forename: John D
authors.initials: JD
authors.lastname: MacMicking
authors.affiliation: the Department of Microbial Pathogenesis, Boyer Center for Molecular Medicine, Yale University School of Medicine, New Haven, Connecticut 06510, and.
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Chee
authors.affiliation: the Laboratory of Nucleic Acid Vaccines, Department of Medicine, University of Massachusetts Medical School Worcester, Massachusetts 01605.
authors.forename: Shixia
authors.initials: S
authors.lastname: Wang
authors.affiliation: the Laboratory of Nucleic Acid Vaccines, Department of Medicine, University of Massachusetts Medical School Worcester, Massachusetts 01605.
authors.forename: Shan
authors.initials: S
authors.lastname: Lu
authors.affiliation: From the Program in Innate Immunity, Division of Infectious Diseases and Immunology and the Centre of Molecular Inflammation Research, Department of Cancer and Molecular Medicine, NTNU, 7491 Trondheim, Norway egil.lien@umassmed.edu.
authors.forename: Egil
authors.initials: E
authors.lastname: Lien
mesh_terms: D016915:AIDS Vaccines / Q000819:agonists / Q000276:immunology; D000276:Adjuvants, Immunologic / Q000032:analysis / Q000737:chemistry / Q000494:pharmacology*; D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000166:cytology / Q000187:drug effects* / Q000276:immunology; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D015699:HIV Envelope Protein gp120 / Q000819:agonists / Q000276:immunology; D007113:Immunity, Innate / Q000187:drug effects*; D007074:Immunoglobulin G / Q000032:analysis / Q000096:biosynthesis; D058847:Inflammasomes / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D008050:Lipid A / Q000819:agonists / Q000031:analogs & derivatives / Q000494:pharmacology; D008264:Macrophages / Q000166:cytology / Q000187:drug effects* / Q000276:immunology; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; D012503:Saponins / Q000032:analysis / Q000737:chemistry / Q000494:pharmacology*; D012995:Solubility; D018417:Th1 Cells / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D018418:Th2 Cells / Q000187:drug effects / Q000276:immunology / Q000378:metabolism
chemical_list: D016915:AIDS Vaccines; D000276:Adjuvants, Immunologic; D002352:Carrier Proteins; D015699:HIV Envelope Protein gp120; C082068:HIV-1 IIIB gp120 subunit vaccine; D007074:Immunoglobulin G; D058847:Inflammasomes; D008050:Lipid A; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C492716:Nlrp3 protein, mouse; D012503:Saponins; C078785:saponin QA-21V1; D019204:GTP-Binding Proteins; C472531:Gbp5 protein, mouse; C048436:monophosphoryl lipid A
keywords: NLRP3; Toll-like receptor 4 (TLR4); adjuvants*; caspase 1 (CASP1); human immunodeficiency virus (HIV); inflammasome; monophosphoryl lipid A; saponin; vaccine