title: Pore-forming toxin-mediated ion dysregulation leads to death receptor-independent necroptosis of lung epithelial cells during bacterial pneumonia.
abstract: We report that pore-forming toxins (PFTs) induce respiratory epithelial cell necroptosis independently of death receptor signaling during bacterial pneumonia. Instead, necroptosis was activated as a result of ion dysregulation arising from membrane permeabilization. PFT-induced necroptosis required RIP1, RIP3 and MLKL, and could be induced in the absence or inhibition of TNFR1, TNFR2 and TLR4 signaling. We detected activated MLKL in the lungs from mice and nonhuman primates experiencing Serratia marcescens and Streptococcus pneumoniae pneumonia, respectively. We subsequently identified calcium influx and potassium efflux as the key initiating signals responsible for necroptosis; also that mitochondrial damage was not required for necroptosis activation but was exacerbated by MLKL activation. PFT-induced necroptosis in respiratory epithelial cells did not involve CamKII or reactive oxygen species. KO mice deficient in MLKL or RIP3 had increased survival and reduced pulmonary injury during S. marcescens pneumonia. Our results establish necroptosis as a major cell death pathway active during bacterial pneumonia and that necroptosis can occur without death receptor signaling.
authors.affiliation: Department of Microbiology, The University of Alabama at Birmingham, 845 19th Street South, Birmingham, AL 35294-2170, USA.
authors.forename: Norberto
authors.initials: N
authors.lastname: González-Juarbe
authors.affiliation: Department of Microbiology, The University of Alabama at Birmingham, 845 19th Street South, Birmingham, AL 35294-2170, USA.
authors.forename: Kelley Margaret
authors.initials: KM
authors.lastname: Bradley
authors.affiliation: Department of Microbiology, The University of Alabama at Birmingham, 845 19th Street South, Birmingham, AL 35294-2170, USA.
authors.forename: Anukul Taranath
authors.initials: AT
authors.lastname: Shenoy
authors.affiliation: Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, 8403 Floyd Curl Drive, San Antonio, TX 78229, USA.
authors.forename: Ryan Paul
authors.initials: RP
authors.lastname: Gilley
authors.affiliation: Division of Pulmonary Diseases and Critical Care Medicine, Department of Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA.
authors.forename: Luis Felipe
authors.initials: LF
authors.lastname: Reyes
authors.affiliation: Division of Pulmonary Diseases and Critical Care Medicine, Department of Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA.
authors.forename: Cecilia Anahí
authors.initials: CA
authors.lastname: Hinojosa
authors.affiliation: Division of Pulmonary Diseases and Critical Care Medicine, Department of Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA.|Division of Pulmonary Diseases and Critical Care Medicine, South Texas Veterans Health Care System, San Antonio, TX 78229, USA.
authors.forename: Marcos Ignacio
authors.initials: MI
authors.lastname: Restrepo
authors.affiliation: Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, 8403 Floyd Curl Drive, San Antonio, TX 78229, USA.
authors.forename: Peter Herman
authors.initials: PH
authors.lastname: Dube
authors.affiliation: Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, 8403 Floyd Curl Drive, San Antonio, TX 78229, USA.
authors.forename: Molly Ann
authors.initials: MA
authors.lastname: Bergman
authors.affiliation: Department of Microbiology, The University of Alabama at Birmingham, 845 19th Street South, Birmingham, AL 35294-2170, USA.|Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, 8403 Floyd Curl Drive, San Antonio, TX 78229, USA.
authors.forename: Carlos Javier
authors.initials: CJ
authors.lastname: Orihuela
mesh_terms: D000072283:A549 Cells; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001427:Bacterial Toxins / Q000633:toxicity*; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002463:Cell Membrane Permeability; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism* / Q000382:microbiology; D005260:Female; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D017136:Ion Transport; D008168:Lung / Q000187:drug effects / Q000378:metabolism / Q000382:microbiology; D051379:Mice; D008810:Mice, Inbred C57BL; D009336:Necrosis / Q000139:chemically induced / Q000235:genetics* / Q000473:pathology; D010215:Papio; D018410:Pneumonia, Bacterial / Q000235:genetics* / Q000382:microbiology / Q000401:mortality / Q000473:pathology; D052899:Pore Forming Cytotoxic Proteins / Q000633:toxicity*; D011188:Potassium / Q000378:metabolism; D011494:Protein Kinases / Q000172:deficiency / Q000235:genetics; D053422:Receptor-Interacting Protein Serine-Threonine Kinases / Q000172:deficiency / Q000235:genetics; D053218:Receptors, Death Domain / Q000235:genetics / Q000378:metabolism; D012706:Serratia marcescens / Q000472:pathogenicity / Q000502:physiology; D013296:Streptococcus pneumoniae / Q000472:pathogenicity / Q000502:physiology; D016019:Survival Analysis
chemical_list: D001427:Bacterial Toxins; D020690:GTPase-Activating Proteins; D052899:Pore Forming Cytotoxic Proteins; C490620:Ralbp1 protein, mouse; D053218:Receptors, Death Domain; C570694:MLKL protein, mouse; D011494:Protein Kinases; D053422:Receptor-Interacting Protein Serine-Threonine Kinases; C485615:Ripk3 protein, mouse; D011188:Potassium; D002118:Calcium