Early inflammatory changes in radiation-induced oral mucositis : Effect of pentoxifylline in a mouse model.

PURPOSE: Early inflammation is a major factor of mucosal reactions to radiotherapy. Pentoxifylline administration resulted in a significant amelioration of radiation-induced oral mucositis in the mouse tongue model. The underlying mechanisms may be related to the immunomodulatory properties of the drug. The present study hence focuses on the manifestation of early inflammatory changes in mouse tongue during daily fractionated irradiation and their potential modulation by pentoxifylline. MATERIALS AND METHODS: Daily fractionated irradiation with 5 fractions of 3 Gy/week (days 0-4, 7-11) was given to the snouts of mice. Groups of 3 animals per day were euthanized every second day between day 0 and 14. Pentoxifylline (15 mg/kg, s. c.) was administered daily from day 5 to the day before sacrifice. The expression of the inflammatory proteins TNFα, NF-κB, and IL-1ß were analysed. RESULTS: Fractionated irradiation increased the expression of all inflammatory markers. Pentoxifylline significantly reduced the expression of TNFα and IL-1ß, but not NF-κB. CONCLUSION: Early inflammation, as indicated by the expression of the inflammatory markers TNFα, NF-κB, and IL-1ß, is an essential component of early radiogenic oral mucositis. Pentoxifylline differentially modulated the expression of different inflammatory markers. The mucoprotective effect of pentoxifylline does not appear to be based on modulation of NF-κB-associated inflammation.