title: Protectin D1 promotes resolution of inflammation in a murine model of lipopolysaccharide-induced acute lung injury via enhancing neutrophil apoptosis.
abstract: BACKGROUND
  Protectin D1 (PD1), derived from docosahexaenoic acid, has been shown to control and resolve inflammation in some experimental models of inflammatory disorders. We investigated the protective roles of protectin D1 in pulmonary inflammation and lung injury induced by lipopolysaccharide (LPS).
  
  
  METHODS
  Mice were randomly assigned to six groups (n = 6 per group): sham-vehicle group, sham-PD1 group, sham-zVAD-fmk group, LPS-vehicle group, LPS-PD1 group, and LPS-PD1-zVAD-fmk group. Mice were injected intratracheally with 3 mg/kg LPS or saline, followed 24 hours later by intravenous injection of 200 µg/mouse PD1 or vehicle. At the same time, some mice were also injected intraperitoneally with the pan-caspase inhibitor zVAD-fmk. Seventy-two hours after LPS challenge, samples of pulmonary tissue and bronchoalveolar lavage fluid were collected. Optical microscopy was used to examine pathological changes in lungs. Cellularity and protein concentration in bronchoalveolar lavage fluid were analyzed. Lung wet/dry ratios and myeloperoxidase activity were measured. Apoptosis of neutrophils in bronchoalveolar lavage fluid (BALF) was also evaluated by flow cytometry.
  
  
  RESULTS
  Intratracheal instillation of LPS increased neutrophil counts, protein concentration in bronchoalveolar lavage fluid and myeloperoxidase activity, it induced lung histological injury and edema, and also suppressed apoptosis of neutrophils in BALF. Posttreatment with PD1 inhibited LPS-evoked changes in BALF neutrophil counts and protein concentration and lung myeloperoxidase activity, with the outcome of decreased pulmonary edema and histological injury. In addition, PD1 promoted apoptosis of neutrophils in BALF. The beneficial effects of PD1 were blocked by zVAD-fmk.
  
  
  CONCLUSIONS
  Posttreatment with PD1 enhances resolution of lung inflammation during LPS-induced acute lung injury by enhancing apoptosis in emigrated neutrophils, which is, at least in part, caspase-dependent.
authors.affiliation: Department of Anesthesiology, Second Hospital, Wenzhou Medical College, Wenzhou, Zhejiang 325027, China.
authors.forename: Xingwang
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Anesthesiology, Clinical Medical School, Mudanjiang Medical College, Mudanjiang, Heilongjiang 157011, China.
authors.forename: Chunlai
authors.initials: C
authors.lastname: Li
authors.affiliation: College of Life Science, Zhejiang Provincial Key Laboratory of Medical Genetics, Wenzhou Medical College, Wenzhou, Zhejiang 325027, China.
authors.forename: Wandong
authors.initials: W
authors.lastname: Liang
authors.affiliation: School of Basic Medical Science, Wenzhou Medical College, Wenzhou, Zhejiang 325027, China.
authors.forename: Yuntian
authors.initials: Y
authors.lastname: Bi
authors.affiliation: Department of Neurosurgery, Centre Hospital of Wenzhou, Wenzhou, Zhejiang 325000, China.
authors.forename: Maohua
authors.initials: M
authors.lastname: Chen
authors.affiliation: Department of Cardiothoracic Surgery, Fourth Hospital of Harbin Medical University, Harbin, Heilongjiang 150001, China. Email: dongsheng1031@163.com.
authors.forename: Sheng
authors.initials: S
authors.lastname: Dong
mesh_terms: D055371:Acute Lung Injury / Q000139:chemically induced* / Q000188:drug therapy* / Q000276:immunology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D004281:Docosahexaenoic Acids / Q000627:therapeutic use*; D007249:Inflammation / Q000188:drug therapy*; D008070:Lipopolysaccharides / Q000633:toxicity*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009504:Neutrophils / Q000166:cytology* / Q000187:drug effects*; D009195:Peroxidase / Q000378:metabolism
chemical_list: D008070:Lipopolysaccharides; C487679:protectin D1; D004281:Docosahexaenoic Acids; D009195:Peroxidase