Objective—To evaluate the effect of controlled exposure
to inhaled lipopolysaccharides (LPS) on the pulmonary
inflammatory response of anesthetized pigs.
Animals—Forty-seven 8- to 12-week-old domestic
Procedure—Pigs were anesthetized with pentobarbital,
instrumented for measurement of cardiopulmonary
function, and randomly assigned to receive
saline (0.9% NaCl) solution or 0.25, 0.5, or 1.0 µg of
LPS/kg/h for 2 or 6 hours via nebulization through the
endotracheal tube. Cardiopulmonary variables were
measured, ex vivo neutrophil superoxide production
determined, and postmortem assessment for pulmonary
neutrophil influx and modulation of adhesion
molecule (E-selectin) expression was done.
Results—Mild changes in cardiopulmonary function
were observed in response to inhaled LPS in the 2-
and 6-hour groups. In pigs inhaling LPS (0.5 or 1.0
µg/kg/h) for 6 hours, there was significant pulmonary
neutrophil influx observed postmortem. An increase
in expression of E-selectin on pulmonary endothelial
cells after 6 hours of LPS inhalation (0.5 µg/kg/h) was
also observed. In contrast, there was no significant
influx of neutrophils or expression of E-selectin in
lungs from pigs inhaling LPS for 2 hours.
Conclusion and Clinical Relevance—Inhalation of
LPS resulted in localized pulmonary inflammation
characterized by neutrophil influx and increased
expression of the endothelial cell adhesion molecule,
E-selectin. It may be possible to relate our experimental
findings to the clinical consequences of airborne
LPS exposure in swine confinement facilities.
(Am J Vet Res 2002;63:1302–1308)