L-arginine: A unique amino acid for improving depressed wound immune function following hemorrhage

Objective: To determine whether L-arginine has any salutary effects
on wound immune cell function following trauma-hemorrhage.
Background. Depressed wound immune function contributes to an
increased incidence of wound infections following hemorrhage.
Although administration of L-arginine has been shown to restore
depressed cell-mediated immune responses following hemorrhage
potentially by maintaining organ blood flow, it remains unknown
whether Larginine has any salutary effects on the depressed local
immune response at the wound site. Methods: Male mice were
subjected to a midline laparotomy and polyvinyl sponges were
implanted subcutaneously in the abdominal wound prior to hemorrhage
(35 +/- 5 mm Hg for 90 min and resuscitation) or sham operation.
During resuscitation mice received 300 mg/kg body weight L-arginine
or saline (vehicle). Sponges were harvested 24 h thereafter, wound
fluid collected and wound immune cells cultured for 24 h in the
presence of LPS. Pro- (IL-1beta, IL-6) and anti-inflammatory
(IL-10) cytokines were determined in the supernatants and the wound
fluid. In addition, wounds were stained for IL-6
immunohistochemically. In a separate set of animals, skin and
muscle blood flow was determined by microspheres. Results: The
capacity of wound immune cells to release IL-1beta and IL-6 in
vitro was significantly depressed in hemorrhaged mice receiving
vehicle. Administration of L-arginine, however, improved wound
immune cell function. In contrast, in vivo the increased IL-6
release at the wound site was decreased in L-arginine-treated mice
following hemorrhage. Moreover, IL-10 levels were significantly
increased in the wound fluid in hemorrhaged animals receiving
L-arginine compared to vehicle-treated mice. In addition, the
depressed skin and muscle blood flow after hemorrhage was restored
by L-arginine. Conclusions: Thus, L-arginine might improve local
wound cell function by decreasing the inflammatory response at the
wound site. Since L-arginine protected wound immune cell function
this amino acid might represent a novel and useful adjunct to fluid
resuscitation for decreasing wound complications following
hemorrhage. Copyright beta 2002 S. Karger AG, Basel.