Intestinal Irradiation and Fibrosis in a Th1-Deficient Environment
- Institut de Radioprotection et de Surete Nucleaire, Fontenay-aux-Roses (France)
Purpose: Changes in the Th1/Th2 immune balance may play a role in increasing the incidence of radiation-induced toxicity. This study evaluates the consequences of Th1 deficiency on intestinal response (fibrosis and T cell trafficking) to abdominal irradiation and examines in mucosa and mesenteric lymph nodes (MLN) the differential involvement of the two Th1 pathways, T-bet/STAT1 and IL-12/STAT4, in controlling this balance in mice. Methods and Materials: Using T-bet-deficient mice (T-bet{sup -/-}), we evaluated the mRNA and protein expression of the Th1 pathways (IFN-{gamma}, T-bet/STAT1, and IL-12/STAT4) and the CD4{sup +} and CD8{sup +} populations in ileal mucosa and MLN during the first 3 months after 10 Gy abdominal irradiation. Results: The T-bet-deficient mice showed an increased fibrotic response to radiation, characterized by higher TGF-{beta}1, col3a1 expression, and collagen deposition in mucosa compared with wild-type mice. This response was associated with drastically lower expression of IFN-{gamma}, the hallmark Th1 cytokine. Analysis of the Th1 expression pathways, T-bet/STAT1 and IL-12/STAT4, showed their equal involvement in the failure of Th1 polarization. A minimal IFN-{gamma} level depended on the IL-23-p19/STAT4 level. In addition, the radiation-induced deficiency in the priming of Th1 by IFN-{gamma} was related to the defective homing capacity of CD8{sup +} cells in the mucosa. Conclusion: Irradiation induces Th2 polarization, and the Th2 immune response may play a role in potentiating irradiation-induced intestinal collagen deposition.
- OSTI ID:
- 22149482
- Journal Information:
- International Journal of Radiation Oncology, Biology and Physics, Vol. 84, Issue 1; Other Information: Copyright (c) 2012 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0360-3016
- Country of Publication:
- United States
- Language:
- English
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