Elastase as a potential biomarker for radiation-induced gut wall injury of the distal bowel in an experimental mouse model.

ABSTRACT

BACKGROUND AND PURPOSE: Traditionally, elastase has been used to study exocrine activity of the pancreas in patients with chronic pancreatitis and cystic fibrosis, and calprotectin as a marker for gut-wall inflammation in patients with inflammatory bowel disease. The aim of the study was to find out whether elastase and calprotectin could be used as inflammatory markers for radiation-induced gut wall injury of the distal bowel. MATERIAL AND METHODS: Adult male mice were exposed to two, three, or four fractions of 6 Gy or 8 Gy irradiation to the sigmoid and rectum of the large bowel, using a linear accelerator. Fecal samples were collected from mice at 1, 3, and 6 weeks post-irradiation. The fecal levels of elastase and calprotectin were analyzed using ELISA. RESULTS: Three and 6 weeks after irradiation, we found a dose-effect relationship between dose of ionizing radiation and the fecal level of elastase; that is significantly higher levels of elastase were observed in mice that had received a high irradiation dose. We also found that irradiated mice hosted in the same cage had a comparable level (either high or low) of elastase. No significant differences were observed from the calprotectin data. CONCLUSIONS: We found a clear association between the dose of ionizing radiation to the distal colon and the level of elastase in the fecal samples.