Submitted on February 14, 2003
Accepted on March 9, 2004
Neutrophils augment recovery of porcine ischemia-injured ileal mucosa by an IL-1
and COX-2 dependent mechanism
Donnie E. Shifflett1, Frank G. Bottone Jr.2, Karen M. Young1, Adam J. Moeser1, Samuel L. Jones1, and Anthony T. Blikslager1*
1 Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
2 Laboratory of Molecular Carcinogenesis, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA
* To whom correspondence should be addressed. E-mail: Anthony_Blikslager{at}ncsu.edu.
Neutrophils augment recovery of porcine ischemia-injured ileal mucosa by an IL-1
and COX-2 dependent mechanism. - Neutrophils (PMNs) play a critical role
in intestinal mucosal injury and repair. To study the effects of PMNs on acutely injured mucosa,
we applied PMNs isolated from circulation or peritoneal fluid from animals with chemically-induced
peritonitis to ischemic-injured porcine ileal mucosa. In preliminary experiments, PMNs
enhanced recovery of transepithelial electrical resistance (TER), and this action was inhibited by
pre-treatment with the non-selective COX inhibitor indomethacin. Because COX-2 is up-regulated
by inflammatory mediators such as IL-1, which is released by PMNs, we postulated
that PMNs enhance recovery of ischemia-injured mucosa by a pathway involving IL-1, and
COX-2. Application of 5x106 PMNs to the serosal surface of ischemia-injured mucosa
significantly enhanced recovery of TER (p<0.05), an effect that was inhibited by the selective
COX-2 inhibitor NS-398 (5µM), and by an IL-1 receptor antagonist (0.1mg/ml). Addition of
10ng/mL IL-1 to the serosal surface of injured tissues caused a significant increase in TER
(p<0.05), which was inhibited by pre-treatment with NS-398. Western blots of mucosal
homogenates revealed dramatic up-regulation of COX-2 in response to IL-1 or peritoneal
PMNs, and the latter was inhibited by an IL-1 receptor antagonist. Real time PCR revealed
increased mRNA COX-2 expression preceded increased COX-2 protein expression in response
to IL-1. We concluded that PMNs augment recovery of TER in ischemia-injured ileal mucosa
via IL-1-dependent upregulation of COX-2.
