title: Effect of short-term enteral feeding with eicosapentaenoic and gamma-linolenic acids on alveolar macrophage eicosanoid synthesis and bactericidal function in rats.
abstract: OBJECTIVE
  Because vasoactive eicosanoids derived from arachidonic acid present in immune cell phospholipids promote lung inflammation in critically ill patients, novel experimental diets containing eicosapentaenoic acid from fish oil and gamma-linolenic acid from borage oil have been designed to limit arachidonic acid metabolism. However, excess dietary eicosapentaenoic acid impairs superoxide formation and bacterial killing by immune cells. The present study determined whether short-term enteral feeding with diets enriched with either eicosapentaenoic acid alone or in combination with gamma-linolenic acid would modulate alveolar macrophage eicosanoid synthesis without compromising bactericidal function.
  
  
  METHODS
  Prospective, randomized, controlled, blinded study.
  
  
  METHODS
  University medical center.
  
  
  METHODS
  Adult male Sprague-Dawley rats.
  
  
  METHODS
  Rats underwent surgical placement of a gastroduodenal feeding catheter and were randomly assigned to receive one of three high-fat (55.2% of total calories), low-carbohydrate diets containing isocaloric amounts of lipids for 4 days. The control diet was enriched with linoleic acid, whereas the two test diets were low in linoleic acid and enriched with either 5 mole % eicosapentaenoic acid alone or in combination with 5 mole % gamma-linolenic acid. Alveolar macrophages were then procured to assess phospholipid fatty acid composition, eicosanoid synthesis after stimulation with endotoxin, superoxide formation and phagocytosis by flow cytometry, and killing of Staphylococcus aureus
  
  
  RESULTS
  Alveolar macrophage levels of arachidonic acid were significantly (p < .01) lower and levels of eicosapentaenoic and dihomo-gamma-linolenic acids were higher after feeding the eicosapentaenoic and gamma-linolenic acid diet vs. the linoleic acid diet. Ratios of thromboxane B2,/B3, leukotriene B4/B5, and prostaglandin E2/E1 were reduced in the macrophages from rats given either the eicosapentaenoic acid or eicosapentaenoic acid with gamma-linolenic acid diet compared with ratios from rats given the linoleic acid diet. Macrophages from rats given the eicosapentaenoic with gamma-linolenic acid diet released 35% or 24% more prostaglandin E1 than macrophages from rats given either the linoleic acid or the eicosapentaenoic acid diet, respectively. Macrophage superoxide generation, phagocytosis of opsonized zymosan, and killing of S. aureus were similar irrespective of dietary treatment.
  
  
  CONCLUSIONS
  Short-term enteral feeding with an eicosapentaenoic acid-enriched or eicosapentaenoic with gamma-linolenic acid-enriched diet rapidly modulated the fatty acid composition of alveolar macrophage phospholipids, promoted a shift toward formation of less inflammatory eicosanoids by stimulated macrophages, but did not impair alveolar macrophage bactericidal function relative to responses observed after feeding a linoleic acid diet.
authors.affiliation: Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA. jpalombo@caregroup.harvard.edu
authors.forename: J D
authors.initials: JD
authors.lastname: Palombo
authors.forename: S J
authors.initials: SJ
authors.lastname: DeMichele
authors.forename: P J
authors.initials: PJ
authors.lastname: Boyce
authors.forename: E E
authors.initials: EE
authors.lastname: Lydon
authors.forename: J W
authors.initials: JW
authors.lastname: Liu
authors.forename: Y S
authors.initials: YS
authors.lastname: Huang
authors.forename: R A
authors.initials: RA
authors.lastname: Forse
authors.forename: J P
authors.initials: JP
authors.lastname: Mizgerd
authors.forename: B R
authors.initials: BR
authors.lastname: Bistrian
mesh_terms: D000818:Animals; D001095:Arachidonic Acids / Q000378:metabolism; D001424:Bacterial Infections / Q000517:prevention & control*; D015777:Eicosanoids / Q000096:biosynthesis / Q000378:metabolism*; D015118:Eicosapentaenoic Acid / Q000627:therapeutic use*; D004750:Enteral Nutrition / Q000379:methods*; D005395:Fish Oils / Q000627:therapeutic use; D016676:Macrophages, Alveolar / Q000378:metabolism*; D008297:Male; D010587:Phagocytosis; D010936:Plant Extracts / Q000627:therapeutic use; D011446:Prospective Studies; D011458:Prostaglandins E / Q000378:metabolism; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012128:Respiratory Distress Syndrome / Q000276:immunology / Q000517:prevention & control*; D013211:Staphylococcus aureus / Q000187:drug effects; D013481:Superoxides / Q000378:metabolism; D017965:gamma-Linolenic Acid / Q000627:therapeutic use*
chemical_list: D001095:Arachidonic Acids; D015777:Eicosanoids; D005395:Fish Oils; D010936:Plant Extracts; D011458:Prostaglandins E; D013481:Superoxides; D017965:gamma-Linolenic Acid; D015118:Eicosapentaenoic Acid