Background and Purpose: Peritoneal adhesions are a normal response to injury of the peritoneal surface and occurin approximately 95% of patients following abdominal surgery. Although adhesions are integral to the healing process of the peritoneum, they can occasionally cause significant morbidity, such as small-bowel obstruction, female infertility, and chronic abdominal and/or pelvic pain. Transforming growth factor-β1 (TGF-β1) is a part of the TGF-β super family of proteins that regulate a wide variety of cellular processes, such as fibrinolysis, mesothelial-to-mesenchymal transition (MMT), and extracellular matrix (ECM) synthesis and degradation, which are implicated in peritoneal adhesion formation. EW-7197 is a novel oral TGF-β type I receptor kinase inhibitor with high selectivity and low toxicity. The purpose of this study was to evaluate if EW-7197 suppresses peritoneal adhesion formation in a rat experimental model.
Materials and Methods: Thirty-six non-pregnant female Wistar rats (250-300 g; Orient Bio, Seongnam, Korea) underwent peritoneal adhesion induction by the creation of ischemic buttons within the peritoneal wall. These animals were randomly divided into three groups: control (n = 12), 10 mg EW-7197 (n = 12), and 20 mg EW-7197 (n = 12). The control group received 0.3 ml of artificial gastric juice (2 g sodium chloride, 3.2 g pepsin powder, and 80 mL hydrochloric acid) by gavage once daily for 7 days. The 10 mg EW-7197 group received a solution consisting of 0.3 ml of artificial gastric juice and 10 mg/kg EW-7197 phosphate by gavage once daily for 7 days. The 20 mg EW-7197 group received a solution consisting of 0.3 ml of artificial gastric juice and 20 mg/kg EW-7197 phosphate by gavage once daily for 7 days. After the respective periods of treatments were completed, the animals were killed by carbon dioxide asphyxiation.
Results: Peritoneal ischemic buttons creation was technically successful in all 36 rats. There were no complications related to EW-7197 administration. All animals survived until the end of the study. EW-7197 significantly decreased the incidence and severity of peritoneal adhesions in a dose-dependent manner. Histologic examination showed that fibrosis and inflammation were significantly attenuated in EW-7197 treated peritoneal ischemic buttons. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blot analyses showed that TGF-β/Smad2/3 signaling and expression of connective tissue growth factor and vascular endothelial growth factor were significantly reduced in EW-7197 treated peritoneal ischemic buttons. qRT-PCR and western blot analyses showed that markers of MMT and ECM synthesis and degradation were significantly altered in EW-7197 treated peritoneal ischemic buttons. Immunohistochemical and immunofluorescence analyses showed that MMT was inhibited in a Smad-dependent manner in EW-7197 treated peritoneal ischemic buttons.
Conclusion: In conclusion, EW-7197 suppresses peritoneal adhesion formation in a rat experimental model. The effects of EW-7197-induced suppression of peritoneal adhesion formation seems to be due to inhibition of TGF-β1/Smad2/3-induced MMT and ECM synthesis.