Loss of intestinal barrier function after
burn injury allows movement of intraluminal contents across the mucosa, which can lead to the development of distant organ injury and
multiple organ failure. Tight junction function is highly regulated by
membrane-associated proteins including
occludin and zonula occludens
protein 1 (ZO-1), which can be modulated by systemic
inflammation. We hypothesized that (1)
burn injury leads to gut barrier injury, and (2)
phosphodiesterase inhibition will attenuate these
burn-induced changes. Male balb/c mice undergoing a 30%
steam burn were randomized to
resuscitation with
normal saline or
normal saline +
pentoxifylline (PTX; 12.5 mg/kg). Intestinal injury was assessed by histological diagnosis and
TNF-alpha levels using
enzyme-linked
immunosorbent assay. Intestinal permeability was assessed by measuring the plasma concentration of
fluorescein isothiocyanate-dextran after intraluminal injection in the distal ileum.
Occludin and ZO-1 levels were analyzed by immunoblotting and immunohistochemistry. Thirty percent total body surface area (TBSA)
burn results in a significant increase in intestinal permeability. Treatment with PTX after
burn attenuates intestinal permeability to
sham levels.
Burn injury resulted in a marked decrease in the levels of
tight junction proteins occludin and ZO-1 at 6 and 24 h. The use of PTX after
burn significantly decreases the breakdown of
occludin and ZO-1.
Pentoxifylline also attenuates the
burn-induced increase in plasma and intestinal
TNF-alpha. Confocal microscopy demonstrates that PTX attenuates the
burn-induced reorganization of
occludin and ZO-1 away from the tight junction.
Pentoxifylline attenuates
burn-induced intestinal permeability and decreases the breakdown and reorganization of intestinal
occludin and ZO-1. Therefore,
phosphodiesterase inhibition may be a useful adjunct strategy in the attenuation of
burn-induced gut barrier injury.