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  2. Impaired autophagy-accelerated senescence of alveolar type II epithelial cells drives pulmonary fibrosis induced by single-walled carbon nanotubes

Impaired autophagy-accelerated senescence of alveolar type II epithelial cells drives pulmonary fibrosis induced by single-walled carbon nanotubes

  • J Nanobiotechnology. 2023 Feb 28;21(1):69. doi: 10.1186/s12951-023-01821-6.
Xiang Zhang # 1 Xinxin Hu # 1 Yuqing Zhang 1 Bin Liu 2 Haihong Pan 1 Zikai Liu 1 Zhuomeng Yao 1 Qixing Zhu 1 Changhao Wu 3 Tong Shen 4
Affiliations

Affiliations

  • 1 Department of Occupational Health and Environment Health, School of Public Health, Anhui Medical University, Hefei, 230032, China.
  • 2 Department of Medical Aspects of Specific Environments, School of Basic Medicine, Anhui Medical University, Hefei, China.
  • 3 Department of Biochemistry and Physiology, Faculty of Heath and Medical Sciences, University of Surrey, Surrey, Guildford, UK.
  • 4 Department of Occupational Health and Environment Health, School of Public Health, Anhui Medical University, Hefei, 230032, China. shentong@ahmu.edu.cn.
  • # Contributed equally.
Abstract

Background: The rapid increase in production and application of carbon nanotubes (CNTs) has led to wide public concerns in their potential risks to human health. Single-walled CNTs (SWCNTs), as an extensively applied type of CNTs, have shown strong capacity to induce pulmonary fibrosis in animal models, however, the intrinsic mechanisms remain uncertain.

Results: In vivo experiments, we showed that accelerated senescence of alveolar type II epithelial cells (AECIIs) was associated with pulmonary fibrosis in SWCNTs-exposed mice, as well as SWCNTs-induced fibrotic lungs exhibited impaired autophagic flux in AECIIs in a time dependent manner. In vitro, SWCNTs exposure resulted in profound dysfunctions of MLE-12 cells, characterized by impaired autophagic flux and accelerated cellular senescence. Furthermore, the conditioned medium from SWCNTs-exposed MLE-12 cells promoted fibroblast-myofibroblast transdifferentiation (FMT). Additionally, restoration of Autophagy flux with rapamycin significantly alleviated SWCNTs-triggered senescence and subsequent FMT whereas inhibiting Autophagy using 3-MA aggravated SWCNTs-triggered senescence in MLE-12 cells and FMT.

Conclusion: SWCNTs trigger senescence of AECIIs by impairing autophagic flux mediated pulmonary fibrosis. The findings raise the possibility of senescence-related cytokines as potential biomarkers for the hazard of CNTs exposure and regulating Autophagy as an appealing target to halt CNTs-induced development of pulmonary fibrosis.

Keywords

Alveolar type II epithelial cells; Autophagy; Carbon nanotube; Pulmonary fibrosis; Senescence.

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