Lipopolysaccharide protection from oxygen toxicity: effect on rat pulmonary selectins.
Sublethal doses of LPS result in increased tolerance to high concentrations of oxygen and this is associated with decreased pulmonary inflammation in a rat model. To investigate the mechanism of decreased neutrophil influx into the lung in this model, we measured levels of mRNA in the lung for the endothelial adhesion molecules, E-selectin and P-selectin. Immunostaining for E-selectin protein was also done in rat lungs, as well as measurement of soluble L-selectin in the blood. These levels were measured in the lungs of adult rats injected with 0.5 mg/kg LPS or placebo at 0 and 24 h and exposed to > 95% O2 for 60 h. Oxygen exposure resulted in significant increases in both E- and P-selectin mRNA and in E-selectin protein after 60 h. LPS resulted in an early rise in E-selectin protein followed by a decline to less than control (saline/O2) levels at 60 h. Messenger RNA for E-selectin followed a similar trend, although there were no differences at 60 h between LPS and control groups exposed to O2. P-selectin mRNA expression did not significantly differ between LPS and control O2 groups. Soluble L-selectin levels decreased by 6 h after LPS infusion and were significantly lower than saline/O2 controls through 24 h, suggesting binding to endothelium. In conclusion, the decrease in E-selectin expression on the surface of pulmonary endothelium after LPS could contribute to decreased inflammation in this model of oxygen toxicity. Soluble L-selectin may serve a further anti-inflammatory role after LPS infusion by binding to pulmonary endothelium.
Thompson
Lauree R
LR
Department of Pediatrics, Route 0526, University of Texas Medical Branch, Galveston, Texas 77555-0526, USA.
Keeney
Susan E
SE
Tarrant
Donna
D
Rudloff
Elizabeth
E
Dallas
Dara V
DV
Schmalstieg
Frank C
FC
D000818:Animals; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008168:Lung / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D010100:Oxygen / Q000633:toxicity*; D051381:Rats; D017207:Rats, Sprague-Dawley; D019087:Selectins / Q000096:biosynthesis / Q000378:metabolism* / Q000502:physiology
D008070:Lipopolysaccharides; D019087:Selectins; D010100:Oxygen