Adenovirus-Mediated Bcl-Xl Gene Therapy Combined with Pronase Treatment Protects the Small Intestine from Radiation-Induced Enteritis in Mouse Model

Kazuaki Uchimoto

doi:10.4172/2157-7412.1000239

Abstract

Intestinal injury is a major side effect of radiation treatment for many malignancies. The present study investigated whether transducing Bcl-xL, a potent anti-apoptotic gene, into intestinal epithelial cells would exert protective effects against radiation-induced acute injuries. Methods: Adenoviral vectors containing the human Bcl-xL gene (AxCABclxL) or β-galactosidase gene (AxCAlacZ) driven by the CAG promoter were generated. To increase transduction efficiency into the mucosal epithelium, the intraluminal space of the small intestine of mice was washed with buffered-saline and mucus components were digested with Pronase MS®. Gene transduction was performed by injecting 2×108 pfu adenoviral vector into the pre-treated small intestine. Transduction efficiency was examined by X-gal staining 24 hours after AxCAlacZ infection. Radiation-induced acute injury of the small intestine was induced by whole body irradiation (15 Gy) performed 24 hours after adenoviral vector infection. Apoptotic epithelial cells were visualized by TUNEL assay. Morphological analysis was assessed by histological examination. Results: Successful transduction after Pronase MS® treatment was achieved in the basal crypt epithelial cells in the ileum, thought to be the location of stem cells, as determined by X-gal staining. The AxCABclxL group demonstrated significantly fewer radiation-induced apoptotic mucosal epithelial cells when compared with the other two groups at 6 hours after irradiation (p<0.05). At 72 hours after irradiation, the morphological appearance of the small intestine in the AxCABclxL group showed significantly less radiation damage in terms of mucosal thickness (p<0.001). Conclusions: The present study indicates that Bcl-xL gene expression using adenoviral vector-mediated transduction is a valuable approach to prevent intestinal injury caused by radiation exposure.

Highlights

Radiation therapy is widely applied as a valuable treatment for abdomino-pelvic malignancies including colon, rectum, prostate and uterine carcinomas [1,2,3]
We hypothesized that the poor gene transduction observed even for direct intraluminal vector injection might be caused by mucous components within the intestinal epithelium that block viral vector infection
Morphologic preservation of the intestinal epithelium in the Pronase MS®-AxCABclxL group was observed in terms of the crypt number per circumference (Figure 3E). These findings clearly demonstrated that transducing the Bcl-xL gene could provide protective effects against semi-acute phase radiation-induced injuries leading to morphological maintenance

Summary

Introduction

Radiation therapy is widely applied as a valuable treatment for abdomino-pelvic malignancies including colon, rectum, prostate and uterine carcinomas [1,2,3]. Radiation therapy, either alone or in conjunction with chemotherapy, often requires interruption or cessation due to serious acute damage in the small intestine [1,2,3,4]. Such acute injury includes severe enterocolitis, intestinal fistulas and strictures. In order to further facilitate radiation therapy, development of therapeutic approaches that provide radio protective effects in the small intestine is required [3,4,5,6,7,8,9,10]

Methods

Results

Conclusion