title: α1-Antitrypsin promotes SPLUNC1-mediated lung defense against Pseudomonas aeruginosa infection in mice.
abstract: BACKGROUND
  Pseudomonas aeruginosa (PA) infection is involved in various lung diseases such as cystic fibrosis and chronic obstructive pulmonary disease. However, treatment of PA infection is not very effective in part due to antibiotic resistance. α1-antitrypsin (A1AT) has been shown to reduce PA infection in humans and animals, but the underlying mechanisms remain unclear. The goal of our study is to test whether a novel endogenous host defense protein, short palate, lung, and nasal epithelium clone 1 (SPLUNC1), is involved in the therapeutic effect of A1AT during lung PA infection.
  
  
  METHODS
  SPLUNC1 knockout (KO) and littermate wild-type (WT) mice on the C57BL/6 background were intranasally infected with PA to determine the therapeutic effects of A1AT. A1AT was aerosolized to mice 2 hrs after the PA infection, and mice were sacrificed 24 hrs later. PA load and inflammation were quantified in the lung, and SPLUNC1 protein in bronchoalveolar lavage (BAL) fluid was examined by Western blot.
  
  
  RESULTS
  In WT mice, PA infection significantly increased neutrophil elastase (NE) activity, but reduced SPLUNC1 protein in BAL fluid. Notably, PA-infected mice treated with A1AT versus bovine serum albumin (BSA) demonstrated higher levels of SPLUNC1 protein expression, which are accompanied by lower levels of NE activity, lung bacterial load, and pro-inflammatory cytokine production. To determine whether A1AT therapeutic effects are dependent on SPLUNC1, lung PA load in A1AT- or BSA-treated SPLUNC1 KO mice was examined. Unlike the WT mice, A1AT treatment in SPLUNC1 KO mice had no significant impact on lung PA load and pro-inflammatory cytokine production.
  
  
  CONCLUSIONS
  A1AT reduces lung bacterial infection in mice in part by preventing NE-mediated SPLUNC1 degradation.
authors.forename: Di
authors.initials: D
authors.lastname: Jiang
authors.forename: Rebecca
authors.initials: R
authors.lastname: Persinger
authors.forename: Qun
authors.initials: Q
authors.lastname: Wu
authors.forename: Ashley
authors.initials: A
authors.lastname: Gross
authors.affiliation: Department of Medicine, National Jewish Health, Denver, CO, USA. ChuHw@NJHealth.org.
authors.forename: Hong Wei
authors.initials: HW
authors.lastname: Chu
mesh_terms: D000818:Animals; D001992:Bronchoalveolar Lavage Fluid; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D006023:Glycoproteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D019272:Leukocyte Elastase / Q000378:metabolism; D008168:Lung / Q000187:drug effects / Q000378:metabolism / Q000382:microbiology; D008171:Lung Diseases / Q000378:metabolism / Q000382:microbiology* / Q000517:prevention & control*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010750:Phosphoproteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D011552:Pseudomonas Infections / Q000378:metabolism* / Q000517:prevention & control*; D011550:Pseudomonas aeruginosa; D000515:alpha 1-Antitrypsin / Q000494:pharmacology / Q000627:therapeutic use*
chemical_list: C119074:Bpifa1 protein, mouse; D016207:Cytokines; D006023:Glycoproteins; D010750:Phosphoproteins; D000515:alpha 1-Antitrypsin; D019272:Leukocyte Elastase