Reactive oxygen species and EGR-1 gene expression in surgical postoperative peritoneal adhesions

Postoperative peritoneal adhesions are common and serious complications of general abdominal and gynecological surgery that can lead to chronic abdominal pain, small-bowel obstruction and infertility. The specific pathophysiology of peritoneal adhesions remains elusive and current treatment is relegated to prevention through meticulous surgical technique and protective physical barriers, gels and solutions. We have reported that reactive oxygen species (ROS), generated by phagocytic cells at the site of tissue injury, serve as major signaling molecules regulating the expression of vascular endothelial growth factor (VEGF) and subsequent wound repair. We hypothesized that peritoneal adhesions are a product of over-healing surgical wounds and that, like in wound healing, ROS are implicated in their pathogenesis. We examined the presence of footprints of ROS and the ROS-inducible angiogenic factor VEGF in human adhesion tissue. An experimental model of peritoneal adhesion was established in rodents to study of the dynamics of ROS-induced gene expression during de novo adhesion tissue formation. Immunohistochemical analysis demonstrated presence of ROS/oxidant and macrophages in human peritoneal tissue. The presence of ROS and ROS-sensitive transcription factor EGR-1 was also evident in an experimental rodent peritoneal adhesion model. Along with ROS, VEGF, and a large number of mature and immature CD31/vWF positive blood vessels were present in the adhesion tissue. These observations are not consistent with the contention that adhesions are non-functional scar tissue. The newly developed rodent model of adhesion may present a useful approach to reproducibly and objectively study molecular mechanisms underlying the dynamic process of de novo adhesion tissue formation.