Activation of adherent vascular neutrophils in the lung during acute endotoxemia.
BACKGROUND
Neutrophils constitute the first line of defense against invading microorganisms. Whereas these cells readily undergo apoptosis under homeostatic conditions, their survival is prolonged during inflammatory reactions and they become biochemically and functionally activated. In the present study, we analyzed the effects of acute endotoxemia on the response of a unique subpopulation of neutrophils tightly adhered to the lung vasculature.


METHODS
Rats were treated with 5 mg/kg lipopolysaccharide (i.v.) to induce acute endotoxemia. Adherent neutrophils were isolated from the lung vasculature by collagenase digestion and sequential filtering. Agarose gel electrophoresis, RT-PCR, western blotting and electrophoretic mobility shift assays were used to evaluate neutrophil activity.


RESULTS
Adherent vascular neutrophils isolated from endotoxemic animals exhibited decreased apoptosis when compared to cells from control animals. This was associated with a marked increase in expression of the anti-apoptotic protein, Mcl-1. Cells isolated 0.5-2 hours after endotoxin administration were more chemotactic than cells from control animals and expressed increased tumor necrosis factor-alpha and cyclooxygenase-2 mRNA and protein, demonstrating that they are functionally activated. Endotoxin treatment of the animals also induced p38 and p44/42 mitogen activated protein kinases in the adherent lung neutrophils, as well as nuclear binding activity of the transcription factors, NF-kappaB and cAMP response element binding protein.


CONCLUSIONS
These data demonstrate that adherent vascular lung neutrophils are highly responsive to endotoxin and that pathways regulating apoptosis and cellular activation are upregulated in these cells.
Sunil
Vasanthi R
VR
Department of Pharmacology and Toxicology, Rutgers University, 160 Frelinghuysen Road, Piscataway, New Jersey 08854-8020, USA. sunilva@eden.rutgers.edu <sunilva@eden.rutgers.edu>
Connor
Agnieszka J
AJ
Zhou
Peihong
P
Gordon
Marion K
MK
Laskin
Jeffrey D
JD
Laskin
Debra L
DL
D000208:Acute Disease; D000818:Animals; D002448:Cell Adhesion / Q000502:physiology; D002470:Cell Survival / Q000502:physiology; D019446:Endotoxemia / Q000378:metabolism* / Q000473:pathology*; D004731:Endotoxins / Q000494:pharmacology*; D005260:Female; D008168:Lung / Q000098:blood supply* / Q000378:metabolism / Q000473:pathology*; D018375:Neutrophil Activation / Q000502:physiology*; D009504:Neutrophils / Q000378:metabolism* / Q000473:pathology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D004731:Endotoxins