Department of Pulmonary Medicine and Oncology, Graduate School of Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo, 113-8603, Japan.
Respir Res. 2018 Apr 24;19(1):71. doi: 10.1186/s12931-018-0783-2.
Idiopathic pulmonary fibrosis (IPF) is a progressive disease with high mortality, and the pathogenesis of the disease is still incompletely understood. Although lymphocytes, especially CD4CD25FoxP3 regulatory T cells (Tregs), have been implicated in the development of IPF, contradictory results have been reported regarding the contribution of Tregs to fibrosis both in animals and humans. The aim of this study was to investigate whether a specific T cell subset has therapeutic potential in inhibiting bleomycin (BLM)-induced murine pulmonary fibrosis.
C57BL/6 mice received BLM (100 mg/kg body weight) with osmotic pumps (day 0), and pulmonary fibrosis was induced. Then, splenocytes or Tregs were adoptively transferred via the tail vein. The lungs were removed and subjected to histological and biochemical examinations to study the effects of these cells on pulmonary fibrosis, and blood samples were collected by cardiac punctures to measure relevant cytokines by enzyme-linked immunosorbent assay. Tregs isolated from an interleukin (IL)-10 knock-out mice were used to assess the effect of this mediator. To determine the roles of the spleen in this model, spleen vessels were carefully cauterized and the spleen was removed either on day 0 or 14 after BLM challenge.
Splenocytes significantly ameliorated BLM-induced pulmonary fibrosis when they were administered on day 14. This effect was abrogated by depleting Tregs with an anti-CD25 monoclonal antibody. Adoptive transfer of Tregs on day 14 after a BLM challenge significantly attenuated pulmonary fibrosis, and this was accompanied by decreased production of fibroblast growth factor (FGF) 9-positive cells bearing the morphology of alveolar epithelial cells. In addition, BLM-induced plasma IL-10 expression reverted to basal levels after adoptive transfer of Tregs. Moreover, BLM-induced fibrocyte chemoattractant chemokine (CC motif) ligand-2 production was significantly ameliorated by Treg adoptive transfer in lung homogenates, accompanied by reduced accumulation of bone-marrow derived fibrocytes. Genetic ablation of IL-10 abrogated the ameliorating effect of Tregs on pulmonary fibrosis. Finally, splenectomy on day 0 after a BLM challenge significantly ameliorated lung fibrosis, whereas splenectomy on day 14 had no effect.
These findings warrant further investigations to develop a cell-based therapy using Tregs for treating IPF.
特发性肺纤维化（IPF）是一种死亡率较高的进行性疾病，其发病机制尚不完全清楚。虽然淋巴细胞，尤其是 CD4CD25FoxP3 调节性 T 细胞（Tregs），已被认为与 IPF 的发展有关，但在动物和人类中，Tregs 对纤维化的贡献仍存在矛盾的结果。本研究旨在探讨特定 T 细胞亚群在抑制博来霉素（BLM）诱导的小鼠肺纤维化中的治疗潜力。
C57BL/6 小鼠接受 BLM（100mg/kg 体重）和渗透泵（第 0 天），诱导肺纤维化。然后，通过尾静脉过继转移脾细胞或 Tregs。取出肺进行组织学和生化检查，以研究这些细胞对肺纤维化的影响，并通过心脏穿刺采集血液样本，通过酶联免疫吸附试验测量相关细胞因子。使用白细胞介素（IL）-10 敲除小鼠的 Tregs 来评估该介质的作用。为了确定脾脏在该模型中的作用，在 BLM 攻击后第 0 天或第 14 天小心烧灼脾血管并切除脾脏。
脾细胞在第 14 天给药时可显著改善 BLM 诱导的肺纤维化。用抗 CD25 单克隆抗体耗竭 Tregs 可消除这种作用。BLM 攻击后第 14 天过继转移 Tregs 可显著减轻肺纤维化，同时伴有成纤维细胞生长因子（FGF）9 阳性细胞的形态呈肺泡上皮细胞的减少。此外，BLM 诱导的血浆 IL-10 表达在过继转移 Tregs 后恢复到基础水平。此外，Treg 过继转移可显著改善 BLM 诱导的肺纤维化中纤维母细胞趋化因子（CC 基序）配体-2 的产生，同时伴有骨髓来源的成纤维细胞的积累减少。IL-10 的基因缺失消除了 Tregs 对肺纤维化的改善作用。最后，BLM 攻击后第 0 天脾切除术可显著改善肺纤维化，而第 14 天脾切除术则无影响。
这些发现值得进一步研究，以开发使用 Tregs 治疗特发性肺纤维化的细胞治疗方法。
