Interferon-γand transforming growth factor-β1-producing T lymphocytes in lung tissue of mice with pulmonary fibrosis

Abstract

Objective To investigate the changes and significance of interferon-γ (IFN-γ) and transforming growth factor-β1 (TGF-β1) expression in lung T lymphocytes from mice with pulmonary fibrosis. Methods Thirty pathogen-free C57BL/6 mice were randomly divided into five groups: control group,bleomycin one-week group, bleomycin two-week group, bleomycin three-week group and bleomycin four-week group. Pulmonary fibrosis was induced by intratracheal injection of bleomycin (5 mg/kg). Lungs were isolated one, two, three and four weeks after bleomycin treatment. Histological changes in the lungs were evaluated by haematoxylin-eosin stain or Masson trichrome stain,and scored. T cellular phenotypes and the intracellular production of interferon IFN-γ,TGF-β1 in CD4+ T cells were determined by flow cytometry. Results Bleomycin treatment led to considerable pulmonary fibrotic changes. Compared with control group,a significant increase in the percentage of CD4+ T cells and a significant decrease in the percentage of CD8+were observed in all bleomycin groups(all P <0.01 ). With the progression of fibrosis, a significant increase in the percentage of TGP-β1-producing CD4+ T cells and a significant decrease in the percentage of IFN-γ-producing CD4+ T cells were also observed(all P<0.01). There was positive correlation between the ratio of CD4+ TGF-β1+/CD4 + IFN-γ+ and the scores of pulmonary fibrosis( r = 0. 683, P <0.01). Conclusions Downregulation of IFN-γ and upregulation of TGF-β1in the lung T lymphocyte may play an important role in pulmonary fibrosis. Key words: Idiopathic pulmonary fibrosis; Interferon-γ; Transforming gorwth faetor-β1