title: Klebsiella pneumoniae alleviates influenza-induced acute lung injury via limiting NK cell expansion.
abstract: A protective effect induced by bacterial preinfection upon a subsequent lethal influenza virus infection has been observed, but the underlying immune mechanisms have not yet been fully elucidated. In this study, we used a mouse model of Klebsiella pneumoniae preinfection to gain insight into how bacterial preinfection influences the subsequent lethal influenza virus infection. We found that K. pneumoniae preinfection significantly attenuated lung immune injury and decreased mortality during influenza virus infection, but K. pneumoniae-specific immunity was not involved in this cross-protection against influenza virus. K. pneumoniae preinfection limited NK cell expansion, which was involved in influenza-induced immune injury and death. Furthermore, K. pneumoniae preinfection could not control NK cell expansion and death during influenza virus infection in Rag1(-/-) mice, but adoptive transfer of T cells from wild-type mice was able to restore this protective effect. Our data suggest that the adaptive immune response activated by bacterial infection limits the excessive innate immune response induced by a subsequent influenza infection, ultimately protecting mice from death.
authors.affiliation: Institute of Immunology and Chinese Academy of Sciences Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, Anhui 230027, China;
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.affiliation: Institute of Immunology and Chinese Academy of Sciences Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, Anhui 230027, China;
authors.forename: Fengqi
authors.initials: F
authors.lastname: Li
authors.affiliation: Institute of Immunology and Chinese Academy of Sciences Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, Anhui 230027, China; Hefei National Laboratory for Physical Sciences at Microscale, Hefei, Anhui 230027, China;
authors.forename: Rui
authors.initials: R
authors.lastname: Sun
authors.affiliation: Model Animal Research Center, Nanjing University, Nanjing, Jiangsu 210061, China; and.
authors.forename: Xiang
authors.initials: X
authors.lastname: Gao
authors.affiliation: Institute of Immunology and Chinese Academy of Sciences Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, Anhui 230027, China; Hefei National Laboratory for Physical Sciences at Microscale, Hefei, Anhui 230027, China;
authors.forename: Haiming
authors.initials: H
authors.lastname: Wei
authors.affiliation: Institute of Immunology and Chinese Academy of Sciences Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, Anhui 230027, China; Hefei National Laboratory for Physical Sciences at Microscale, Hefei, Anhui 230027, China; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310003, China tzg@ustc.edu.cn.
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Tian
mesh_terms: D055371:Acute Lung Injury / Q000150:complications / Q000276:immunology* / Q000473:pathology; D000818:Animals; D056738:Cross Protection / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D004195:Disease Models, Animal; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007694:Killer Cells, Natural / Q000276:immunology* / Q000473:pathology*; D007710:Klebsiella Infections / Q000150:complications / Q000276:immunology* / Q000473:pathology; D007711:Klebsiella pneumoniae / Q000276:immunology*; D008213:Lymphocyte Activation / Q000276:immunology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009976:Orthomyxoviridae Infections / Q000150:complications / Q000276:immunology* / Q000473:pathology; D018410:Pneumonia, Bacterial / Q000150:complications / Q000276:immunology / Q000473:pathology; D011024:Pneumonia, Viral / Q000150:complications / Q000276:immunology / Q000473:pathology