INTRODUCTION: Peritoneal adhesions are a major cause of morbidity after laparotomy. Transforming growth factor beta-1 (TGF-b1) is a well-described mediator of scar formation. Multiple animal studies have confirmed its role in the formation of abdominal adhesions, but the importance of TGF-b1 in human abdominal adhesions has never been verified. We hypothesized that TGF-b1 in humans is differentially expressed in adhesions and healthy peritoneum. Furthermore, differential TGF-b1 expression may occur on a systemic as well as a local level.
METHODS: Eleven study patients (with previous laparotomy), and 10 controls (no previous operations) were recruited from patients scheduled for elective open abdominal procedures. Serum and healthy peritoneal tissue were collected from all patients at the time of surgery. Scar tissue from the study patients was harvested as well. The severity of adhesions was recorded. Peritoneal and serum TGF-b1 protein levels were then determined by enzyme-linked immunoasorbent assay (ELISA). Statistical analysis was performed using analysis of variance and an unpaired t-test.
RESULTS: TGF-b1 levels were significantly elevated in scar tissue (0.237pg/ml) compared to healthy tissues from both study (0.146pg/ml, p<0.05) and control patients (0.087pg/ml, p<0.05). While TGF-b1 protein expression in healthy tissue from study patients (0.146pg/ml) was higher that in controls (0.087pg/ml), this difference did not reach statistical significance (p=0.14). Similarly, serum TGF-b1 protein levels were increased in study patients (1.036pg/ml) compared to controls (0.766pg/ml), but the difference did not reach statistical significance (p=0.16). There was no correlation between the severity of adhesions and peritoneal or serum TGF-b1 protein expression.
CONCLUSION: While many studies have demonstrated elevated TGF-b1 levels in the peritoneal scar tissue of animals, this is the first study to confirm increased TGF-b1 levels in human abdominal adhesions. Furthermore, the relatively increased expression of TGF-b1 in the serum and healthy tissue of previously operated patients, while it did not reach statistical significance, suggests TGF-b1 regulation may not be confined to the locally irritated tissues. Eventually, with an improved understanding of the molecular mechanisms of peritoneal adhesion formation, we may develop techniques to prevent such complications.