title: Endotoxin protection from oxygen toxicity: effect on pulmonary neutrophils and L-selectin.
abstract: The mechanisms by which sublethal doses of endotoxin protect against hyperoxic lung injury are not completely understood. We hypothesized that endotoxin treatment would result in a decreased inflammatory response to hyperoxia and that this would be accompanied by activation of neutrophils (as evidenced by loss of L-selectin) in the peripheral circulation. Adult rats were injected with endotoxin 0.5 mg/kg prior to and 24 hr after onset of exposure to > or = 98% O2. After 56 hr of hyperoxia, pulmonary neutrophils were lower in the O2/endotoxin group compared to O2 controls as measured by myeloperoxidase in lung homogenates and neutrophil counts in bronchoalveolar lavage fluid. Circulating neutrophils were also significantly lower in the O2/endotoxin group compared to O2 controls at 56 hr. Expression of the neutrophil adhesion molecule, L-selectin, was lower at 4 and 24 hr in the endotoxin-treated rats compared to O2 controls. There were no differences at 48 hr. Expression of CD18 rose significantly in the O2/endotoxin group after 4 hr, but thereafter did not differ from O2 controls. In summary, endotoxin protection from O2 toxicity was associated with reduced neutrophils in the lung and a loss of L-selectin from peripheral blood neutrophils.
authors.affiliation: Department of Pediatrics, University of Texas Medical Branch, Galveston 77555, USA. skeeney@utmb.edu
authors.forename: Susan E
authors.initials: SE
authors.lastname: Keeney
authors.forename: Mary J
authors.initials: MJ
authors.lastname: Mathews
authors.forename: Karen E
authors.initials: KE
authors.lastname: Shattuck
authors.forename: Dara V
authors.initials: DV
authors.lastname: Dallas
mesh_terms: D000818:Animals; D004731:Endotoxins / Q000494:pharmacology*; D018496:Hyperoxia / Q000517:prevention & control*; D019041:L-Selectin / Q000032:analysis; D007958:Leukocyte Count; D008168:Lung / Q000473:pathology*; D008297:Male; D018375:Neutrophil Activation / Q000187:drug effects; D020556:Neutrophil Infiltration / Q000187:drug effects; D009504:Neutrophils / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010100:Oxygen / Q000494:pharmacology; D020011:Protective Agents / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012486:Salmonella typhimurium / Q000737:chemistry
chemical_list: D004731:Endotoxins; D020011:Protective Agents; D019041:L-Selectin; D010100:Oxygen