title: Regulatory T Cells Promote β-Catenin--Mediated Epithelium-to-Mesenchyme Transition During Radiation-Induced Pulmonary Fibrosis.
abstract: OBJECTIVE
  Radiation-induced pulmonary fibrosis results from thoracic radiation therapy and severely limits radiation therapy approaches. CD4(+)CD25(+)FoxP3(+) regulatory T cells (Tregs) as well as epithelium-to-mesenchyme transition (EMT) cells are involved in pulmonary fibrosis induced by multiple factors. However, the mechanisms of Tregs and EMT cells in irradiation-induced pulmonary fibrosis remain unclear. In the present study, we investigated the influence of Tregs on EMT in radiation-induced pulmonary fibrosis.
  
  
  METHODS
  Mice thoraxes were irradiated (20 Gy), and Tregs were depleted by intraperitoneal injection of a monoclonal anti-CD25 antibody 2 hours after irradiation and every 7 days thereafter. Mice were treated on days 3, 7, and 14 and 1, 3, and 6 months post irradiation. The effectiveness of Treg depletion was assayed via flow cytometry. EMT and β-catenin in lung tissues were detected by immunohistochemistry. Tregs isolated from murine spleens were cultured with mouse lung epithelial (MLE) 12 cells, and short interfering RNA (siRNA) knockdown of β-catenin in MLE 12 cells was used to explore the effects of Tregs on EMT and β-catenin via flow cytometry and Western blotting.
  
  
  RESULTS
  Anti-CD25 antibody treatment depleted Tregs efficiently, attenuated the process of radiation-induced pulmonary fibrosis, hindered EMT, and reduced β-catenin accumulation in lung epithelial cells in vivo. The coculture of Tregs with irradiated MLE 12 cells showed that Tregs could promote EMT in MLE 12 cells and that the effect of Tregs on EMT was partially abrogated by β-catenin knockdown in vitro.
  
  
  CONCLUSIONS
  Tregs can promote EMT in accelerating radiation-induced pulmonary fibrosis. This process is partially mediated through β-catenin. Our study suggests a new mechanism for EMT, promoted by Tregs, that accelerates radiation-induced pulmonary fibrosis.
authors.affiliation: Beijing Institute of Radiation Medicine, Beijing, China.
authors.forename: Shanshan
authors.initials: S
authors.lastname: Xiong
authors.affiliation: Beijing Institute of Radiation Medicine, Beijing, China.
authors.forename: Xiujie
authors.initials: X
authors.lastname: Pan
authors.affiliation: Beijing Institute of Radiation Medicine, Beijing, China.
authors.forename: Long
authors.initials: L
authors.lastname: Xu
authors.affiliation: Beijing Institute of Radiation Medicine, Beijing, China.
authors.forename: Zhihua
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan.
authors.forename: Renfeng
authors.initials: R
authors.lastname: Guo
authors.affiliation: Beijing Institute of Radiation Medicine, Beijing, China.
authors.forename: Yongqing
authors.initials: Y
authors.lastname: Gu
authors.affiliation: Beijing Institute of Radiation Medicine, Beijing, China.
authors.forename: Ruoxi
authors.initials: R
authors.lastname: Li
authors.affiliation: Beijing Institute of Radiation Medicine, Beijing, China.
authors.forename: Qianjun
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Beijing Institute of Radiation Medicine, Beijing, China.
authors.forename: Fengjun
authors.initials: F
authors.lastname: Xiao
authors.affiliation: Beijing Institute of Radiation Medicine, Beijing, China.
authors.forename: Li
authors.initials: L
authors.lastname: Du
authors.affiliation: Beijing Institute of Radiation Medicine, Beijing, China.
authors.forename: Pingkun
authors.initials: P
authors.lastname: Zhou
authors.affiliation: Beijing Institute of Radiation Medicine, Beijing, China. Electronic address: zhumx@nic.bmi.ac.cn.
authors.forename: Maoxiang
authors.initials: M
authors.lastname: Zhu
mesh_terms: D000818:Animals; D003037:Cobalt Radioisotopes / Q000494:pharmacology; D058750:Epithelial-Mesenchymal Transition / Q000502:physiology*; D005260:Female; D005434:Flow Cytometry / Q000379:methods; D055785:Gene Knockdown Techniques; D053645:Interleukin-2 Receptor alpha Subunit / Q000276:immunology; D008212:Lymphocyte Depletion / Q000379:methods; D051379:Mice; D008810:Mice, Inbred C57BL; D011650:Pulmonary Alveoli / Q000473:pathology / Q000528:radiation effects; D017564:Radiation Pneumonitis / Q000209:etiology*; D011897:Random Allocation; D050378:T-Lymphocytes, Regulatory / Q000166:cytology / Q000276:immunology / Q000502:physiology*; D051176:beta Catenin / Q000235:genetics / Q000502:physiology*
chemical_list: D003037:Cobalt Radioisotopes; D053645:Interleukin-2 Receptor alpha Subunit; D051176:beta Catenin