Preoperative application of CPSI 2364 per os prevents postoperative ileus in rodents and swine

Abstract

BackgroundThe mechanical trauma of the gut is an unavoidable consequence of abdominal surgery leading to massive inflammation of the entire bowel wall and subsequently in postoperative ileus [1]. Further studies revealed the activation of the resident macrophages in the tunica muscularis as an initial step in the inflammatory cascade [2]. The aim of this study was to investigate the effectivity of the macrophage-specific c-Raf-Kinase Inhibitor CPSI 2364 in preventing postoperative ileus in rodents and swine.Materials and methodsC57BL6/J mice were treated with placebo or CPSI 2364 p.o. 90 minutes before intestinal manipulation (IM) or sham operation. Animals were sacrificed 24 h after IM and tunica muscularis was prepared for further investigations. Production of NO as the major intestinal inhibitory neurotransmitter was measured in supernatants from small intestinal muscle specimen cultures by the Griess-Reaction. The infiltration of neutrophils in the tunica muscularis was detected by MPO-staining and counted to quantify the inflammatory extend. Subsequently, contractility of muscularis strips was examined in an in vitro organ bath and gastrointestinal transit was measured to analyze the motility function in vivo.In addition to this small animal model further experiments in swine were performed to have a transfer model to human organism: After intestinal manipulation the animals were monitored at our intensive care unit. In addition to defecation several laboratory parameters were applied to screen out severe organ dysfunction. 24 hours later swine were killed and further investigated: Inflammatory activity in the tunica muscularis of the small bowel was measured using a myeloperoxidase assay. To examine smooth muscle function, muscularis strips were exposured to an increasing concentration of a muscarinic agonist in an in vitro organ bath and contractility was analyzed. Furthermore gastrointestinal transit was measured in vivo as described from Metcalf et al. [3].Results Rodent model: Infiltration of neutrophile granulocytes and NO production were significantly reduced after preoperative blocking of the c-Raf-Kinase pathway by CPSI 2364. Furthermore jejunal contractility and gastrointestinal transit were nearly normalized after treatment. Large animal model: In CPSI 2364 treated swine, myeloperoxidase-activity in the tunica muscularis was significantly reduced compared to the Placebo group. In addition the onset of defecation was earlier after CPSI 2364 treatment. Functional studies showed an improved contractility of jejunal muscularis strips in vitro and an accelerated gastrointestinal transit time in vivo after application of the drug. Laboratory parameters and clinical examination showed no severe organ disturbances after drug treatment.ConclusionOur results demonstrate that postoperative inflammation of the tunica muscularis after intestinal manipulation can be reduced by specific blocking of c-Raf-Kinase pathway in macrophages. This inhibition prevents development of postoperative ileus in rodents and swine. Therefore CPSI 2364 seems to be a promising drug for the prophylaxis of postoperative intestinal dysmotility following abdominal surgery.