van Batenburg Aernoud A, Kazemier Karin M, van Oosterhout Matthijs F M, van der Vis Joanne J, Grutters Jan C, Goldschmeding Roel, van Moorsel Coline H M
Dept of Pulmonology, St Antonius ILD Center of Excellence, St Antonius Hospital, Nieuwegein, The Netherlands.
Center of Translational Immunology, University Medical Center Utrecht, Utrecht, The Netherlands.
ERJ Open Res. 2021 May 31;7(2). doi: 10.1183/23120541.00691-2020. eCollection 2021 Apr.
Pulmonary fibrosis is strongly associated with telomere shortening and increased DNA damage. Key cells in the pathogenesis involve alveolar type 2 (AT2) cells, club cells and myofibroblasts; however, to what extent these cells are affected by telomere shortening and DNA damage is not yet known. We sought to determine the degree of, and correlation between, telomere shortening and DNA damage in different cell types involved in the pathogenesis of progressive fibrosing interstitial lung disease. Telomere length and DNA damage were quantified, using combined fluorescence hybridisation and immunofluorescence staining techniques, in AT2 cells, club cells and myofibroblasts of controls and patients with pulmonary fibrosis and a telomerase reverse transcriptase mutation (TERT-PF), idiopathic pulmonary fibrosis (IPF) and fibrotic hypersensitivity pneumonitis (fHP). In IPF and TERT-PF lungs, AT2 cells contained shorter telomeres and expressed higher DNA damage signals than club cells and myofibroblasts. In fHP lungs, club cells contained highly elevated levels of DNA damage, while telomeres were not obviously short. , we found significantly shorter telomeres and higher DNA damage levels only in AT2 surrogate cell lines treated with telomerase inhibitor BIBR1532. Our study demonstrated that in IPF and TERT-PF lungs, telomere shortening and accumulation of DNA damage primarily affects AT2 cells, further supporting the importance of AT2 cells in these diseases, while in fHP the particularly high telomere-independent DNA damage signals in club cells underscores its bronchiolocentric pathogenesis. These findings suggest that cell type-specific telomere shortening and DNA damage may help to discriminate between different drivers of fibrogenesis.
肺纤维化与端粒缩短和DNA损伤增加密切相关。发病机制中的关键细胞包括肺泡II型（AT2）细胞、俱乐部细胞和成肌纤维细胞；然而，这些细胞受端粒缩短和DNA损伤影响的程度尚不清楚。我们试图确定进行性纤维化间质性肺病发病机制中不同细胞类型中端粒缩短与DNA损伤的程度及其相关性。采用荧光杂交和免疫荧光染色技术相结合的方法，对对照组、肺纤维化合并端粒酶逆转录酶突变（TERT-PF）、特发性肺纤维化（IPF）和纤维化性过敏性肺炎（fHP）患者的AT2细胞、俱乐部细胞和成肌纤维细胞中的端粒长度和DNA损伤进行定量分析。在IPF和TERT-PF肺组织中，AT2细胞的端粒比俱乐部细胞和成肌纤维细胞短，且DNA损伤信号表达更高。在fHP肺组织中，俱乐部细胞的DNA损伤水平显著升高，而端粒无明显缩短。此外，我们发现仅在用端粒酶抑制剂BIBR1532处理的AT2替代细胞系中，端粒明显缩短，DNA损伤水平更高。我们的研究表明，在IPF和TERT-PF肺组织中，端粒缩短和DNA损伤积累主要影响AT2细胞，进一步支持了AT2细胞在这些疾病中的重要性，而在fHP中，俱乐部细胞中特别高的不依赖端粒的DNA损伤信号突出了其以细支气管为中心的发病机制。这些发现表明，细胞类型特异性的端粒缩短和DNA损伤可能有助于区分不同的纤维化驱动因素。
