Inflammatory cytokines, pleuropneumonia infection and the effect of dexamethasone.
OBJECTIVE
Actinobacillus pleuropneumoniae causes an often fatal infection of swine due to pleuropneumonia. To determine if inflammatory cytokines are associated with A. pleuropneumoniae-induced pneumonia, infected and noninfected animals were concomitantly administered saline or dexamethasone.


METHODS
Twenty-four swine were treated with saline, A. pleuropneumoniae, dexamethasone, or A. pleuropneumoniae and dexamethasone (n = 6). The plasma levels of TNF-alpha, IL-1beta, IL-6, IL-8, and IL-10 were examined through time of necropsy (72 h). Gross pathology and histopathology was performed on all animals.


RESULTS
Dexamethasone had no effect on A. pleuropneumoniae-induced increases in lung/body weight ratios. Gross pathology of the infected pigs included fibrinous pleuropneumonia with necrosis and hemorrhage in a focal to a multifocal pattern. Histopathology of infected pig lungs revealed necrotizing extensive, fibrinopurulent pneumonia with edema and fibrinopurulent pleuritis. Plasma IL-6 levels were elevated in A. pleuropneumoniae-infected animals beginning 6 h after infection. Dexamethasone treatment did not alter A. pleuropneumoniae-induced plasma IL-6 levels. A. pleuropneumoniae infection did not elicit plasma levels of TNF-alpha, IL-1beta, IL-8, or IL-10.


CONCLUSIONS
These results suggest that the pneumonia caused by A. pleuropneumoniae infection is not due to the release of systemic inflammatory cytokines.
Myers
Michael J
MJ
Division of Animal Research, US FDA, Center for Veterinary Medicine, Laurel, MD 20708, USA. mmeyers@cvm.fda.gov
Farrell
Dorothy E
DE
Snider
T G Ron
TG
Post
Lynn O
LO
D016977:Actinobacillus pleuropneumoniae / Q000276:immunology; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use; D016207:Cytokines / Q000097:blood / Q000187:drug effects* / Q000276:immunology; D003907:Dexamethasone / Q000627:therapeutic use*; D007249:Inflammation / Q000276:immunology; D008168:Lung / Q000187:drug effects / Q000276:immunology / Q000473:pathology*; D010994:Pleura / Q000187:drug effects / Q000276:immunology / Q000473:pathology; D011001:Pleuropneumonia / Q000188:drug therapy* / Q000276:immunology / Q000662:veterinary*; D013552:Swine
D000893:Anti-Inflammatory Agents; D016207:Cytokines; D003907:Dexamethasone