title: Diet restriction impairs extracellular signal-regulated kinase activation of peritoneal exudative cells after N-formyl-methionyl-leucyl-phenylalanine stimulation in a murine peritonitis model.
abstract: BACKGROUND
  Phosphorylation of extracellular signal-regulated kinase (ERK) enhances various inflammatory responses in immune cells. It is unknown whether dysfunction of immune cells during malnutrition is attributed to derangement of ERK activation.
  
  
  METHODS
  Male Institute of Cancer Research (ICR) mice received chow (146 g/kg per day, ad libitum or 36.5 g/kg per day, diet-restricted) for 7 days. Mice (n = 55) were given 6.5 mg/kg of an ERK inhibitor (PD98059) or vehicle intraperitoneally (IP), at 2 hours before cecal ligation and puncture (CLP). Survival was observed up to 60 hours. Detection of phosphorylated ERK (pERK) in the peritoneal exudative cells (PECs) was done as follows. In a separate study, PECs were harvested by peritoneal lavage 2 hours after an IP injection of 1% glycogen. PECs were incubated with or without 100 nmol/L N-formyl-methionyl-leucyl-phenylalanine (fMLP) for 1 minute. PEC ERK activation was detected with Western blot analysis (n = 38), by densitometric quantification, and with a laser scanning cytometer (LSC; n = 13). Subpopulations of PECs were determined by Wright-Giemsa staining. Unstimulated pERK expression was normalized to 100% for Western blot analysis.
  
  
  RESULTS
  Diet restriction reduced survival after CLP compared with the ad libitum mice. ERK inhibition showed no effect on survival in diet-restricted mice but reduced survival in ad libitum mice. There were no differences in subpopulations of PECs 2 hours after glycogen injection between the groups. Western blot analysis revealed that fMLP stimulation significantly increased the phosphorylation of ERK1/2 in PECs from the ad libitum group (ERK1, 199 +/- 41%; ERK2, 211 +/- 49%; p < .03) but not in those from diet-restricted mice (ERK1, 98 +/- 10%; ERK2, 91 +/- 9%). Mean fluorescence intensity (MFI) of pERK in PECs obtained by LSC was significantly elevated after fMLP in the ad libitum group (from 19.4 +/- 1.5 MFI to 22.4 +/- 1.2 MFI; p < .05) but did not change in the diet-restricted group (from 19.4 +/- 1.8 MFI to 19.1 +/- 1.5 MFI).
  
  
  CONCLUSIONS
  ERK activation is essential for survival in this murine sepsis model. Impaired ERK activation of PECs may, at least in part, impair host defense during malnutrition.
authors.affiliation: Surgical Center, The University of Tokyo, Japan.
authors.forename: Woodae
authors.initials: W
authors.lastname: Kang
authors.forename: Hideaki
authors.initials: H
authors.lastname: Saito
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Fukatsu
authors.forename: Akio
authors.initials: A
authors.lastname: Hidemura
authors.forename: Takeaki
authors.initials: T
authors.lastname: Matsuda
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002432:Cecum / Q000473:pathology / Q000601:surgery; D004038:Diet, Reducing; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D005419:Flavonoids / Q000008:administration & dosage / Q000494:pharmacology; D005434:Flow Cytometry; D007274:Injections, Intraperitoneal; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology*; D009748:Nutrition Disorders / Q000150:complications / Q000276:immunology*; D010529:Peritoneal Cavity / Q000166:cytology; D010538:Peritonitis / Q000139:chemically induced / Q000276:immunology*; D010766:Phosphorylation; D011897:Random Allocation; D015398:Signal Transduction / Q000502:physiology; D013047:Specific Pathogen-Free Organisms
chemical_list: D004791:Enzyme Inhibitors; D005419:Flavonoids; D009240:N-Formylmethionine Leucyl-Phenylalanine; D020928:Mitogen-Activated Protein Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one