A Murine Model for the Study of Molecular Pathogenesis of Radiation Proctitis

Zvi Symon*, Yifat Goldshmidt, Orit Picard, Miri Yavzori, Shomron Ben-Horin, Dror Alezra, Iris Barshack, Yehuda Chowers

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

Purpose: To establish a novel mouse brachytherapy model with which to study the role of inflammation in the pathogenesis of radiation proctitis. Methods and Materials: The distal rectums of BALB/c and C57BL/6 mice were irradiated with three to five fractions of 5.5 to 8 Gy. Tissues were harvested and evaluated for histopathology, using the radiation injury score (RIS). Cytokine mRNA expression was assessed using real-time PCR. Results: Fifty percent of the mice treated with 22 Gy delivered in four fractions of 5.5 Gy died as a result of anorectal stenosis and distal bowel obstruction prior to the time of scheduled sacrifice, with a latency period of 4 to 10 weeks for the BALB/c and 3 to 4 weeks for the C57BL/6 mice. The RISs were 7, 12, and 8 at 2, 6, and 11 weeks, respectively, in the BALB/c mice and was 8.7 in the C57BL/6 mice on week 6. A 100- to 300-fold increase in interleukin-1β (IL-1β) (p = 0.04) and IL-6 mRNA (p = 0.07) and a 5- to 6-fold increase in transforming growth factor (TGF) and tumor necrosis factor-α mRNA expression levels (p < 0.001 and p = 0.01) were observed at 2 to 6 weeks after radiation. Cytokine mRNA tissue expression correlated positively with radiation dose (p < 0.0001). The RIS correlated well with IL-1β and IL-6 mRNA levels in the BALB/c mice and with IL-1β, IL-6, and TGF mRNA levels in C57BL/6 mice. Analysis of receiver operating characteristic curve showed that IL-1β and IL-6 have the largest area under the curve and therefore are good markers of radiation proctitis (p < 0.001). Conclusions: Radiation-induced proctitis was associated with a dose-dependent, characteristic proinflammatory cytokine response pattern in a novel mouse model suitable for interventional studies.

Original languageEnglish
Pages (from-to)242-250
Number of pages9
JournalInternational Journal of Radiation Oncology Biology Physics
Volume76
Issue number1
DOIs
StatePublished - Jan 2010
Externally publishedYes

Keywords

  • Chronic radiation proctitis
  • Murine model

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