Frontline : Critical role for Ipaf in Pseudomonas aeruginosa-induced caspase-1 activation

Pseudomonas aeruginosa is an opportunistic Gram‐negative human pathogen that is responsible for a broad range of infections in individuals with a variety of predisposing conditions. After infection, P. aeruginosa induces a marked inflammatory response in the host. However the mechanisms involved in bacterium recognition and induction of immune responses are poorly understood. Here we report that the Nod‐like receptor family member Ipaf is required for optimal bacterial clearance in an in vivo model of P. aeruginosa lung infection. Further analysis showed that bacterial flagellin was essential for caspase‐1 and IL‐1β and this activity depended on Ipaf and the adaptor ASC but not TLR5. Notably, P. aeruginosa induced macrophage cell death and this event relied on flagellin and Ipaf but not on ASC. Analysis of Pseudomonas mutants revealed that different amino acid residues of flagellin were critical for sensing by Ipaf and TLR5. Finally, activation of caspase‐1 and IL‐1β secretion by P. aeruginosa required a functional type III secretion system, but not the effector molecules ExoS, ExoT and ExoY. These results provide new insight into the interaction of P. aeruginosa with host macrophages and suggest that distinct regions of flagellin are sensed by Ipaf and TLR5.

[1]  Graham F. Brady,et al.  Regulation of Legionella Phagosome Maturation and Infection through Flagellin and Host Ipaf* , 2006, Journal of Biological Chemistry.

[2]  P. Greenberger.  Immunologic aspects of lung diseases and cystic fibrosis. , 1997, JAMA.

[3]  D. Golan,et al.  Resistance to Pseudomonas aeruginosa Chronic Lung Infection Requires Cystic Fibrosis Transmembrane Conductance Regulator-Modulated Interleukin-1 (IL-1) Release and Signaling through the IL-1 Receptor , 2007, Infection and Immunity.

[4]  Qing Yang,et al.  Conservation of genome content and virulence determinants among clinical and environmental isolates of Pseudomonas aeruginosa , 2003, Proceedings of the National Academy of Sciences of the United States of America.

[5]  A. Hauser,et al.  Prevalence of type III secretion genes in clinical and environmental isolates of Pseudomonas aeruginosa. , 2001, Microbiology.

[6]  G. Núñez,et al.  Cell death and immunity: NODs: intracellular proteins involved in inflammation and apoptosis , 2003, Nature Reviews Immunology.

[7]  H. D. Liggitt,et al.  Redundant Toll-like receptor signaling in the pulmonary host response to Pseudomonas aeruginosa. , 2007, American journal of physiology. Lung cellular and molecular physiology.

[8]  Alan Aderem,et al.  Cytoplasmic flagellin activates caspase-1 and secretion of interleukin 1β via Ipaf , 2006, Nature Immunology.

[9]  J. Bertin,et al.  Cytosolic flagellin requires Ipaf for activation of caspase-1 and interleukin 1β in salmonella-infected macrophages , 2006, Nature Immunology.

[10]  R. Kamen,et al.  Mice deficient in IL-1β-converting enzyme are defective in production of mature IL-1β and resistant to endotoxic shock , 1995, Cell.

[11]  A. Butte,et al.  Genome‐wide analysis of host responses to the Pseudomonas aeruginosa type III secretion system yields synergistic effects , 2005, Cellular microbiology.

[12]  M. Chamaillard,et al.  NOD-LRR proteins: role in host-microbial interactions and inflammatory disease. , 2005, Annual review of biochemistry.

[13]  J. Bertin,et al.  Critical role for NALP3/CIAS1/Cryopyrin in innate and adaptive immunity through its regulation of caspase-1. , 2006, Immunity.

[14]  S. Akira,et al.  The innate immune response to bacterial flagellin is mediated by Toll-like receptor 5 , 2001, Nature.

[15]  F. Martinon,et al.  The inflammasome: a molecular platform triggering activation of inflammatory caspases and processing of proIL-beta. , 2002, Molecular cell.

[16]  A. Prince,et al.  Role of Flagella in Pathogenesis ofPseudomonas aeruginosa Pulmonary Infection , 1998, Infection and Immunity.

[17]  R. Flavell,et al.  Involvement of Toll-like receptor 5 in the recognition of flagellated bacteria , 2006, Proceedings of the National Academy of Sciences.

[18]  M. Su,et al.  Altered cytokine export and apoptosis in mice deficient in interleukin-1 beta converting enzyme. , 1995, Science.

[19]  G. Pier.  Resistance to Pseudomonas aeruginosa , 1988 .

[20]  K. O. Elliston,et al.  A novel heterodimeric cysteine protease is required for interleukin-1βprocessing in monocytes , 1992, Nature.

[21]  B. Tümmler,et al.  Epidemiology of chronic Pseudomonas aeruginosa infections in the airways of lung transplant recipients with cystic fibrosis. , 1997, Thorax.

[22]  Y. Ogura,et al.  ASC is an activating adaptor for NF-κB and caspase-8-dependent apoptosis , 2003 .

[23]  M. Paskind,et al.  Mice deficient in IL-1 beta-converting enzyme are defective in production of mature IL-1 beta and resistant to endotoxic shock. , 1995, Cell.

[24]  A. Neely,et al.  Type III secretion/intoxication system important in virulence of Pseudomonas aeruginosa infections in burns. , 2001, Burns : journal of the International Society for Burn Injuries.

[25]  S. Akira,et al.  Bacterial RNA and small antiviral compounds activate caspase-1 through cryopyrin/Nalp3 , 2006, Nature.

[26]  T. Yahr,et al.  Exoenzyme S of Pseudomonas aeruginosa is secreted by a type III pathway , 1996, Molecular microbiology.

[27]  S. Akira,et al.  A Role of Toll-IL-1 Receptor Domain-Containing Adaptor-Inducing IFN-β in the Host Response to Pseudomonas aeruginosa Lung Infection in Mice1 , 2007, The Journal of Immunology.

[28]  Y. Ogura,et al.  ASC is an activating adaptor for NF-kappa B and caspase-8-dependent apoptosis. , 2003, Biochemical and Biophysical Research Communications - BBRC.

[29]  S. Lory,et al.  Pseudolipasin A Is a Specific Inhibitor for Phospholipase A2 Activity of Pseudomonas aeruginosa Cytotoxin ExoU , 2006, Infection and Immunity.

[30]  J. Bertin,et al.  Role of the caspase-1 inflammasome in Salmonella typhimurium pathogenesis , 2006, The Journal of experimental medicine.

[31]  R. Schreiber,et al.  Evidence for a gamma-interferon receptor that regulates macrophage tumoricidal activity , 1984, The Journal of experimental medicine.

[32]  C. March,et al.  Molecular cloning of the interleukin-1 beta converting enzyme. , 1992, Science.

[33]  S. Akira,et al.  Pathogen Recognition and Innate Immunity , 2006, Cell.

[34]  David Miller,et al.  Critical Role for Cryopyrin/Nalp3 in Activation of Caspase-1 in Response to Viral Infection and Double-stranded RNA*> , 2006, Journal of Biological Chemistry.

[35]  G. Núñez,et al.  Nucleotide-Binding Oligomerization Domain-Like Receptors: Intracellular Pattern Recognition Molecules for Pathogen Detection and Host Defense1 , 2006, The Journal of Immunology.

[36]  C. Gabel,et al.  Absence of the P2X7 Receptor Alters Leukocyte Function and Attenuates an Inflammatory Response , 2002, The Journal of Immunology.

[37]  J. Engel,et al.  PepA, a secreted protein of Pseudomonas aeruginosa, is necessary for cytotoxicity and virulence , 1998, Molecular microbiology.

[38]  E. Mahenthiralingam,et al.  Nonmotility and phagocytic resistance of Pseudomonas aeruginosa isolates from chronically colonized patients with cystic fibrosis , 1994, Infection and immunity.

[39]  S. Akira,et al.  The myeloid differentiation factor 88 is dispensable for the development of a delayed host response to Pseudomonas aeruginosa lung infection in mice , 2006, Clinical and experimental immunology.

[40]  B. Iglewski,et al.  The contribution of exoproducts to virulence of Pseudomonas aeruginosa. , 1986, Canadian journal of microbiology.

[41]  J. Bertin,et al.  Nod1 Participates in the Innate Immune Response to Pseudomonas aeruginosa* , 2005, Journal of Biological Chemistry.

[42]  F. Martinon,et al.  Gout-associated uric acid crystals activate the NALP3 inflammasome , 2006, Nature.

[43]  John Bertin,et al.  Nod1 responds to peptidoglycan delivered by the Helicobacter pylori cag pathogenicity island , 2004, Nature Immunology.

[44]  J. Bertin,et al.  Distinct Roles of TLR2 and the Adaptor ASC in IL-1β/IL-18 Secretion in Response to Listeria monocytogenes1 , 2006, The Journal of Immunology.

[45]  R. Ramphal,et al.  Roles of Specific Amino Acids in the N Terminus of Pseudomonas aeruginosa Flagellin and of Flagellin Glycosylation in the Innate Immune Response , 2005, Infection and Immunity.

[46]  L. Hazlett,et al.  Prolonged Elevation of IL-1 in Pseudomonas aeruginosa Ocular Infection Regulates Macrophage-Inflammatory Protein-2 Production, Polymorphonuclear Neutrophil Persistence, and Corneal Perforation1 , 2000, The Journal of Immunology.

[47]  C. Dinarello,et al.  Biologic basis for interleukin-1 in disease. , 1996, Blood.

[48]  H. Iocca,et al.  Cutting Edge: ASC Mediates the Induction of Multiple Cytokines by Porphyromonas gingivalis via Caspase-1-Dependent and -Independent Pathways1 , 2006, The Journal of Immunology.

[49]  D. Guttridge,et al.  ASC Directs NF-κB Activation by Regulating Receptor Interacting Protein-2 (RIP2) Caspase-1 Interactions1 , 2006, The Journal of Immunology.

[50]  R. Ramphal,et al.  TLRs 2 and 4 Are Not Involved in Hypersusceptibility to Acute Pseudomonas aeruginosa Lung Infections1 , 2005, The Journal of Immunology.

[51]  V. Dixit,et al.  Cryopyrin activates the inflammasome in response to toxins and ATP , 2006, Nature.

[52]  C. Janeway,et al.  MyD88 is an adaptor protein in the hToll/IL-1 receptor family signaling pathways. , 1998, Molecular cell.

[53]  B. Cookson,et al.  Apoptosis, Pyroptosis, and Necrosis: Mechanistic Description of Dead and Dying Eukaryotic Cells , 2005, Infection and Immunity.

[54]  Yongde Peng,et al.  The Development of Early Host Response to Pseudomonas aeruginosa Lung Infection Is Critically Dependent on Myeloid Differentiation Factor 88 in Mice* , 2004, Journal of Biological Chemistry.

[55]  L. Hazlett,et al.  Regulation of Pseudomonas aeruginosa corneal infection in IL-1ß converting enzyme (ICE, caspase-1) deficient mice , 2004, Current eye research.

[56]  G. Dubyak,et al.  Differential Requirement of P2X7 Receptor and Intracellular K+ for Caspase-1 Activation Induced by Intracellular and Extracellular Bacteria* , 2007, Journal of Biological Chemistry.

[57]  M. Peters-Golden,et al.  Inhibition by methylprednisolone of zymosan-induced leukotriene synthesis in alveolar macrophages. , 1987, The American review of respiratory disease.