Targeting mTORC1 and AMPK Signaling: Potential Therapeutic Approaches for Idiopathic Pulmonary Fibrosis
DOI:
https://doi.org/10.71204/99f36029Keywords:
Idiopathic Pulmonary Fibrosis, AMPK, mTORC1, Metabolic ReprogrammingAbstract
Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive disease characterized by increasing incidence and mortality. The underlying mechanisms of IPF remain poorly understood, contributing to the limited availability of effective treatments. Current therapies mainly slow disease progression but fail to provide a cure. Consequently, increasing attention has been directed toward modulating signaling pathways such as mammalian target of rapamycin complex 1(mTORC1) and Adenosine monophosphate–activated protein kinase (AMPK), both of which are key regulators of metabolic reprogramming in IPF. This review summarizes recent advances in therapeutic strategies that target cellular metabolism by modulating mTORC1 and AMPK.
References
Akhter, M. S., & Uppal, P. (2020). Toxicity of Metformin and Hypoglycemic Therapies. Advances in Chronic Kidney Disease, 27(1), 18–30.
Andrianifahanana, M., Hernandez, D. M., Yin, X., Kang, J.-H., Jung, M.-Y., Wang, Y., Yi, E. S., Roden, A. C., Limper, A. H., & Leof, E. B. (2016). Profibrotic up-regulation of glucose transporter 1 by TGF-β involves activation of MEK and mammalian target of rapamycin complex 2 pathways. The FASEB Journal, 30(11), 3733–3744.
Aroda, V. R., Edelstein, S. L., Goldberg, R. B., Knowler, W. C., Marcovina, S. M., Orchard, T. J., Bray, G. A., Schade, D. S., Temprosa, M. G., White, N. H., & Crandall, J. P. (2016). Long-term Metformin Use and Vitamin B12 Deficiency in the Diabetes Prevention Program Outcomes Study. The Journal of Clinical Endocrinology and Metabolism, 101(4), 1754–1761.
Bondue, B., Castiaux, A., Van Simaeys, G., Mathey, C., Sherer, F., Egrise, D., Lacroix, S., Huaux, F., Doumont, G., & Goldman, S. (2019). Absence of early metabolic response assessed by 18F-FDG PET/CT after initiation of antifibrotic drugs in IPF patients. Respiratory Research, 20, 10.
Brackett, C. C. (2010). Clarifying metformin’s role and risks in liver dysfunction. Journal of the American Pharmacists Association, 50(3), 407–410.
Castellano, B. M., Thelen, A. M., Moldavski, O., Feltes, M., van der Welle, R. E. N., et al. (2017). Lysosomal cholesterol activates mTORC1 via an SLC38A9-Niemann-Pick C1 signaling complex. Science (New York, N.Y.), 355(6331), 1306–1311.
Chen, Q., Wang, Y., Sheng, L., & Huang, Y. (2022). Metformin suppresses proliferation and differentiation induced by BMP9 via AMPK signaling in human fetal lung fibroblast-1. Frontiers in Pharmacology, 13, 984730.
Cheng, Y., Mei, X., Shao, W., Zheng, J., Yin, X., Zhang, Q., Li, J., & Zhao, P. (2024). Nobiletin alleviates macrophage M2 polarization by activating AMPK-mTOR-mediated autophagy in pulmonary fibrosis mice. International Immunopharmacology, 139, 112792.
Ding, Y., Wang, L., Liu, B., Ren, G., Okubo, R., Yu, J., & Zhang, C. (2022). Bryodulcosigenin attenuates bleomycin‐induced pulmonary fibrosis via inhibiting AMPK ‐mediated mesenchymal epithelial transition and oxidative stress. Phytotherapy Research, 36(10), 3911–3923.
DUAN, Q., LIU, Y., & ROCKWELL, S. (2013). Fenbendazole as a Potential Anticancer Drug. Anticancer Research, 33(2), 355–362.
Dusabimana, T., Kim, S. R., Kim, H. J., Park, S. W., & Kim, H. (2019). Nobiletin ameliorates hepatic ischemia and reperfusion injury through the activation of SIRT-1/FOXO3a-mediated autophagy and mitochondrial biogenesis. Experimental & Molecular Medicine, 51(4), 51.
Eid, W., Dauner, K., Courtney, K. C., Gagnon, A., Parks, R. J., Sorisky, A., & Zha, X. (2017). mTORC1 activates SREBP-2 by suppressing cholesterol trafficking to lysosomes in mammalian cells. Proceedings of the National Academy of Sciences, 114(30), 7999–8004.
Feng, J., Wang, X., Ye, X., Ares, I., Lopez-Torres, B., Martínez, M., Martínez-Larrañaga, M.-R., Wang, X., Anadón, A., & Martínez, M.-A. (2022). Mitochondria as an important target of metformin: The mechanism of action, toxic and side effects, and new therapeutic applications. Pharmacological Research, 177, 106114.
Ferlay, J., Soerjomataram, I., Dikshit, R., Eser, S., Mathers, C., Rebelo, M., Parkin, D. M., Forman, D., & Bray, F. (2015). Cancer incidence and mortality worldwide: Sources, methods and major patterns in GLOBOCAN 2012. International Journal of Cancer, 136(5), 359-386.
Gamad, N., Malik, S., Suchal, K., Vasisht, S., Tomar, A., Arava, S., Arya, D. S., & Bhatia, J. (2018). Metformin alleviates bleomycin-induced pulmonary fibrosis in rats: Pharmacological effects and molecular mechanisms. Biomedicine & Pharmacotherapy, 97, 1544–1553.
Garcia-Calvo, M., Lisnock, J., Bull, H. G., Hawes, B. E., Burnett, D. A., et al. (2005). The target of ezetimibe is Niemann-Pick C1-Like 1 (NPC1L1). Proceedings of the National Academy of Sciences of the United States of America, 102(23), 8132–8137.
Gonnelli, F., Bonifazi, M., & Hubbard, R. (2024). Mortality trends in idiopathic pulmonary fibrosis in Europe between 2013 and 2018. The European Respiratory Journal, 64(2), 2302080.
Groves, A. M., Win, T., Screaton, N. J., Berovic, M., Endozo, R., Booth, H., Kayani, I., Menezes, L. J., Dickson, J. C., & Ell, P. J. (2009). Idiopathic Pulmonary Fibrosis and Diffuse Parenchymal Lung Disease: Implications from Initial Experience with18 F-FDG PET/CT. Journal of Nuclear Medicine, 50(4), 538–545.
Gu, X., Han, Y.-Y., Yang, C.-Y., Ji, H.-M., Lan, Y.-J., Bi, Y.-Q., Zheng, C., Qu, J., Cheng, M.-H., & Gao, J. (2021). Activated AMPK by metformin protects against fibroblast proliferation during pulmonary fibrosis by suppressing FOXM1. Pharmacological Research, 173, 105844.
Gwinn, D. M., Shackelford, D. B., Egan, D. F., Mihaylova, M. M., Mery, A., Vasquez, D. S., Turk, B. E., & Shaw, R. J. (2008). AMPK phosphorylation of raptor mediates a metabolic checkpoint. Molecular Cell, 30(2), 214–226.
Hardie, D. G. (2011). AMPK and autophagy get connected. The EMBO Journal, 30(4), 634–635.
Humphries, S. M., Yagihashi, K., Huckleberry, J., Rho, B.-H., Schroeder, J. D., Strand, M., Schwarz, M. I., Flaherty, K. R., Kazerooni, E. A., Beek, E. J. R. van, & Lynch, D. A. (2017). Idiopathic Pulmonary Fibrosis: Data-driven Textural Analysis of Extent of Fibrosis at Baseline and 15-Month Follow-up. Radiology, 285, 270–278.
Hutchinson, J., Fogarty, A., Hubbard, R., & McKeever, T. (2015). Global incidence and mortality of idiopathic pulmonary fibrosis: A systematic review. European Respiratory Journal, 46(3), 795–806.
Ji, H., Dong, H., Lan, Y., Bi, Y., Gu, X., Han, Y., Yang, C., Cheng, M., & Gao, J. (2023). Metformin attenuates fibroblast activation during pulmonary fibrosis by targeting S100A4 via AMPK-STAT3 axis. Frontiers in Pharmacology, 14, 1089812.
Kalafatis, D., Gao, J., Pesonen, I., Carlson, L., Sköld, C. M., & Ferrara, G. (2019). Gender differences at presentation of idiopathic pulmonary fibrosis in Sweden. BMC Pulmonary Medicine, 19, 222.
Kang, H. J., Lee, K. J., Woo, J., Kim, J., Kim, Y. K., Lee, C.-H., Yoo, C.-G., & Lee, K.-H. (2021). Cereblon contributes to the development of pulmonary fibrosis via inactivation of adenosine monophosphate-activated protein kinase α1. Experimental & Molecular Medicine, 53(5), 885–893.
Kang, S. A., Pacold, M. E., Cervantes, C. L., Lim, D., Lou, H. J., Ottina, K., Gray, N. S., Turk, B. E., Yaffe, M. B., & Sabatini, D. M. (2013a). mTORC1 Phosphorylation Sites Encode Their Sensitivity to Starvation and Rapamycin. Science, 341(6144), 1236566.
Kang, S. A., Pacold, M. E., Cervantes, C. L., Lim, D., Lou, H. J., Ottina, K., Gray, N. S., Turk, B. E., Yaffe, M. B., & Sabatini, D. M. (2013b). mTORC1 phosphorylation sites encode their sensitivity to starvation and rapamycin. Science (New York, N.Y.), 341(6144), 1236566.
Kheirollahi, V., Wasnick, R. M., Biasin, V., Vazquez-Armendariz, A. I., Chu, X., Moiseenko, A., Weiss, A., Wilhelm, J., Zhang, J.-S., Kwapiszewska, G., Herold, S., Schermuly, R. T., Mari, B., Li, X., Seeger, W., Günther, A., Bellusci, S., & El Agha, E. (2019). Metformin induces lipogenic differentiation in myofibroblasts to reverse lung fibrosis. Nature Communications, 10, 2987.
Kim, J. S., Murray, S., Yow, E., Anstrom, K. J., Kim, H. J., Flaherty, K. R., Martinez, F. J., & Noth, I. (2024). Comparison of Pirfenidone and Nintedanib. Chest, 165(5), 1163–1173.
Kim, Y. C., & Guan, K.-L. (2015). mTOR: A pharmacologic target for autophagy regulation. Journal of Clinical Investigation, 125(1), 25–32.
Lederer, D. J., & Martinez, F. J. (2018). Idiopathic Pulmonary Fibrosis. New England Journal of Medicine, 378(19), 1811–1823.
Lee, C., Kwak, S. H., Han, J., Shin, J. H., Yoo, B., Lee, Y. S., Park, J. S., Lim, B. J., Lee, J. G., Kim, Y. S., Kim, S. Y., & Bae, S. H. (2024). Repositioning of ezetimibe for the treatment of idiopathic pulmonary fibrosis. The European Respiratory Journal, 63(5), 2300580.
Lee, J.-U., Chang, H. S., Shim, E.-Y., Park, J.-S., Koh, E.-S., Shin, H.-K., Park, J.-S., & Park, C.-S. (2020). The S100 calcium-binding protein A4 level is elevated in the lungs of patients with idiopathic pulmonary fibrosis. Respiratory Medicine, 171, 105945. https://doi.org/10.1016/j.rmed.2020.105945
Lee, Y. S., Park, J. S., Lee, D. H., Han, J., & Bae, S. H. (2020). Ezetimibe ameliorates lipid accumulation during adipogenesis by regulating the AMPK–mTORC1 pathway. The FASEB Journal, 34(1), 898–911.
Li, L., Huang, W., Li, K., Zhang, K., Lin, C., Han, R., Lu, C., Wang, Y., Chen, H., Sun, F., & He, Y. (2015). Metformin attenuates gefitinib-induced exacerbation of pulmonary fibrosis by inhibition of TGF-β signaling pathway. Oncotarget, 6(41), 43605–43619.
Li, R., Xu, G., Cao, J., Liu, B., Xie, H., Ishii, Y., & Zhang, C. (2019). Alpha-Mangostin Ameliorates Bleomycin-Induced Pulmonary Fibrosis in Mice Partly Through Activating Adenosine 5′-Monophosphate-Activated Protein Kinase. Frontiers in Pharmacology, 10, 1305.
Liu, B., Yang, J., Hao, J., Xie, H., Shimizu, K., Li, R., & Zhang, C. (2021). Natural product mogrol attenuates bleomycin-induced pulmonary fibrosis development through promoting AMPK activation. Journal of Functional Foods, 77, 104280.
Liu, N., Song, Y., Liu, T., Wang, H., Yu, N., & Ma, H. (2024). Metformin enhanced the effect of pirfenidone on pulmonary fibrosis in mice. The Clinical Respiratory Journal, 18(1), e13731.
Lukey, P. T., Harrison, S. A., Yang, S., Man, Y., Holman, B. F., Rashidnasab, A., et al. (2019). A randomised, placebo-controlled study of omipalisib (PI3K/mTOR) in idiopathic pulmonary fibrosis. European Respiratory Journal, 53(3), 1801992.
Maldonado, F., Moua, T., Rajagopalan, S., Karwoski, R. A., Raghunath, S., Decker, P. A., Hartman, T. E., Bartholmai, B. J., Robb, R. A., & Ryu, J. H. (2014). Automated quantification of radiological patterns predicts survival in idiopathic pulmonary fibrosis. The European Respiratory Journal, 43(1), 204–212.
Mei, Q., Liu, Z., Zuo, H., Yang, Z., & Qu, J. (2022). Idiopathic Pulmonary Fibrosis: An Update on Pathogenesis. Frontiers in Pharmacology, 12, 797292.
Mercer, P. F., Woodcock, H. V., Eley, J. D., Platé, M., Sulikowski, M. G., Durrenberger, P. F., Franklin, L., Nanthakumar, C. B., Man, Y., Genovese, F., McAnulty, R. J., Yang, S., Maher, T. M., Nicholson, A. G., Blanchard, A. D., Marshall, R. P., Lukey, P. T., & Chambers, R. C. (2016). Exploration of a potent PI3 kinase/mTOR inhibitor as a novel anti-fibrotic agent in IPF. Thorax, 71(8), 701–711.
Nigdelioglu, R., Hamanaka, R. B., Meliton, A. Y., O’Leary, E., Witt, L. J., Cho, T., et al. (2016). Transforming Growth Factor (TGF)-β Promotes de Novo Serine Synthesis for Collagen Production. The Journal of Biological Chemistry, 291(53), 27239–27251.
Noble, P. W., Albera, C., Bradford, W. Z., Costabel, U., du Bois, R. M., Fagan, E. A., et al. (2016). Pirfenidone for idiopathic pulmonary fibrosis: Analysis of pooled data from three multinational phase 3 trials. The European Respiratory Journal, 47(1), 243–253.
Oh, C. K., Murray, L. A., & Molfino, N. A. (2012). Smoking and Idiopathic Pulmonary Fibrosis. Pulmonary Medicine, 2012, 808260.
O’Leary, E. M., Tian, Y., Nigdelioglu, R., Witt, L. J., Cetin-Atalay, R., Meliton, A. Y., et al. (2020). TGF-β Promotes Metabolic Reprogramming in Lung Fibroblasts via mTORC1-dependent ATF4 Activation. American Journal of Respiratory Cell and Molecular Biology, 63(5), 601–612.
Olmastroni, E., Scotti, S., Galimberti, F., Xie, S., & Casula, M. (2024). Ezetimibe: Integrating Established Use with New Evidence - A Comprehensive Review. Current Atherosclerosis Reports, 27(1), 10.
Park, Y., Ahn, C., & Kim, T.-H. (2021). Occupational and environmental risk factors of idiopathic pulmonary fibrosis: A systematic review and meta-analyses. Scientific Reports, 11(1), 4318.
Penke, L. R., Speth, J. M., Dommeti, V. L., White, E. S., Bergin, I. L., & Peters-Golden, M. (n.d.). (2018). FOXM1 is a critical driver of lung fibroblast activation and fibrogenesis. The Journal of Clinical Investigation, 128(6), 2389–2405.
Qiao, X., Wang, Z., Chen, Y., Peng, N., Zhang, H., Niu, C., & Cheng, C. (2024). Combined metformin and simvastatin therapy inhibits SREBP2 maturation and alters energy metabolism in glioma. Cell Death & Disease, 15(11), 809.
Raghu, G., Remy-Jardin, M., Myers, J. L., Richeldi, L., Ryerson, C. J., Lederer, D. J., et al. (2018). Diagnosis of Idiopathic Pulmonary Fibrosis. An Official ATS/ERS/JRS/ALAT Clinical Practice Guideline. American Journal of Respiratory and Critical Care Medicine, 198(5), 44–68.
Raghu, G., Remy-Jardin, M., Richeldi, L., Thomson, C. C., Inoue, Y., Johkoh, T., et al. (2022). Idiopathic Pulmonary Fibrosis (an Update) and Progressive Pulmonary Fibrosis in Adults: An Official ATS/ERS/JRS/ALAT Clinical Practice Guideline. American Journal of Respiratory and Critical Care Medicine, 205(9), e18–e47.
Rangarajan, S., Bone, N. B., Zmijewska, A. A., Jiang, S., Park, D. W., Bernard, K., et al. (2018). Metformin reverses established lung fibrosis in a bleomycin model. Nature Medicine, 24(8), 1121–1131.
Richeldi, L., Du Bois, R. M., Raghu, G., Azuma, A., Brown, K. K., Costabel, U., et al. (2014). Efficacy and Safety of Nintedanib in Idiopathic Pulmonary Fibrosis. New England Journal of Medicine, 370(22), 2071–2082.
Rindlisbacher, B., Schmid, C., Geiser, T., Bovet, C., & Funke-Chambour, M. (2018). Serum metabolic profiling identified a distinct metabolic signature in patients with idiopathic pulmonary fibrosis – a potential biomarker role for LysoPC. Respiratory Research, 19(1), 7.
Sack, C., & Raghu, G. (2019). Idiopathic pulmonary fibrosis: Unmasking cryptogenic environmental factors. European Respiratory Journal, 53(2).
Sato, N., Takasaka, N., Yoshida, M., Tsubouchi, K., Minagawa, S., Araya, J., Saito, N., et al. (2016). Metformin attenuates lung fibrosis development via NOX4 suppression. Respiratory Research, 17(1), 107.
Saxton, R. A., & Sabatini, D. M. (2017). mTOR Signaling in Growth, Metabolism, and Disease. Cell, 168(6), 960–976.
Selvarajah, B., Azuelos, I., Platé, M., Guillotin, D., Forty, E. J., Contento, G., et al. (2019). mTORC1 amplifies the ATF4-dependent de novo serine-glycine pathway to supply glycine during TGF-β1––induced collagen biosynthesis. Science Signaling, 12(582), eaav3048.
Shin, H. R., Citron, Y. R., Wang, L., Tribouillard, L., Goul, C. S., Stipp, R., Sugasawa, Y., et al. (2022). Lysosomal GPCR-like protein LYCHOS signals cholesterol sufficiency to mTORC1. Science, 377(6612), 1290–1298.
Spagnolo, P., Kreuter, M., Maher, T. M., Wuyts, W., Bonella, F., Corte, T. J., Kopf, S., Weycker, D., Kirchgaessler, K.-U., & Ryerson, C. J. (2018). Metformin Does Not Affect Clinically Relevant Outcomes in Patients with Idiopathic Pulmonary Fibrosis. Respiration, 96(4), 314–322.
Steinberg, G. R., & Hardie, D. G. (2023). New insights into activation and function of the AMPK. Nature Reviews Molecular Cell Biology, 24(4), 255–272.
Takehara, K., Koga, Y., Hachisu, Y., Utsugi, M., Sawada, Y., Saito, Y., Yoshimi, S., Yatomi, M., Shin, Y., Wakamatsu, I., Umetsu, K., Kouno, S., Nakagawa, J., Sunaga, N., Maeno, T., & Hisada, T. (2022). Differential Discontinuation Profiles between Pirfenidone and Nintedanib in Patients with Idiopathic Pulmonary Fibrosis. Cells, 11(1), 143.
Tang, C.-J., Xu, J., Ye, H.-Y., & Wang, X.-B. (2021). Metformin prevents PFKFB3-related aerobic glycolysis from enhancing collagen synthesis in lung fibroblasts by regulating AMPK/mTOR pathway. Experimental and Therapeutic Medicine, 21(6), 581.
Teague, T. T., Payne, S. R., Kelly, B. T., Dempsey, T. M., McCoy, R. G., Sangaralingham, L. R., & Limper, A. H. (2022). Evaluation for clinical benefit of metformin in patients with idiopathic pulmonary fibrosis and type 2 diabetes mellitus: A national claims-based cohort analysis. Respiratory Research, 23, 91.
Vásquez-Pacheco, E., Marega, M., Lingampally, A., Fassy, J., Truchi, M., Goth, K., et al. (2024). Highlighting fibroblast plasticity in lung fibrosis: The WI-38 cell line as a model for investigating the myofibroblast and lipofibroblast switch. Theranostics, 14(9), 3603–3622. https://doi.org/10.7150/thno.93519
Verrecchia, F., Chu, M.-L., & Mauviel, A. (2001). Identification of Novel TGF-β/Smad Gene Targets in Dermal Fibroblasts using a Combined cDNA Microarray/Promoter Transactivation Approach. Journal of Biological Chemistry, 276(20), 17058–17062.
Wang, L., Xu, K., Wang, N., Ding, L., Zhao, W., Wan, R., Zhao, W., Guo, X., Pan, X., et al. (2022). Fenbendazole Attenuates Bleomycin-Induced Pulmonary Fibrosis in Mice via Suppression of Fibroblast-to-Myofibroblast Differentiation. International Journal of Molecular Sciences, 23(22), 14088.
Wang, Y., Sima, X., Ying, Y., & Huang, Y. (2021). Exogenous BMP9 promotes lung fibroblast HFL-1 cell activation via ALK1/Smad1/5 signaling in vitro. Experimental and Therapeutic Medicine, 22(1), 728.
Weinglass, A. B., Kohler, M., Schulte, U., Liu, J., Nketiah, E. O., Thomas, A., et al. (2008). Extracellular loop C of NPC1L1 is important for binding to ezetimibe. Proceedings of the National Academy of Sciences of the United States of America, 105(32), 11140–11145.
Wollin, L., Maillet, I., Quesniaux, V., Holweg, A., & Ryffel, B. (2014). Antifibrotic and Anti-inflammatory Activity of the Tyrosine Kinase Inhibitor Nintedanib in Experimental Models of Lung Fibrosis. The Journal of Pharmacology and Experimental Therapeutics, 349(2), 209–220.
Woodcock, H. V., Eley, J. D., Guillotin, D., Platé, M., Nanthakumar, C. B., Martufi, M., et al. (2019). The mTORC1/4E-BP1 axis represents a critical signaling node during fibrogenesis. Nature Communications, 10, 6.
Wu, X., Xiao, X., Chen, X., Yang, M., Hu, Z., Shuai, S., Fu, Q., Yang, H., & Du, Q. (2022). Effectiveness and mechanism of metformin in animal models of pulmonary fibrosis: A preclinical systematic review and meta-analysis. Frontiers in Pharmacology, 13, 948101.
Xie, T., Xu, Q., Wan, H., Xing, S., Shang, C., Gao, Y., & He, Z. (2019). Lipopolysaccharide promotes lung fibroblast proliferation through autophagy inhibition via activation of the PI3K-Akt-mTOR pathway. Laboratory Investigation, 99(5), 625–633.
Yang, C., Rubin, L., Yu, X., Lazarovici, P., & Zheng, W. (2024). Preclinical evidence using synthetic compounds and natural products indicates that AMPK represents a potential pharmacological target for the therapy of pulmonary diseases. Medicinal Research Reviews, 44(3), 1326–1369.
Zaman, T., & Lee, J. S. (2018). Risk factors for the development of idiopathic pulmonary fibrosis: A review. Current Pulmonology Reports, 7(4), 118–125.
Zeng, M., Hu, Y., Zhao, L., Duan, C., Wu, H., Xu, Y., Liu, X., Wang, Y., Jiang, D., & Zeng, S. (2025). Design, synthesis, and pharmacological evaluation of triazine-based PI3K/mTOR inhibitors for the potential treatment of non-small cell lung cancer. European Journal of Medicinal Chemistry, 284, 117200.
Zhao, M., & Klionsky, D. J. (2011). AMPK-dependent phosphorylation of ULK1 induces autophagy. Cell Metabolism, 13(2), 119–120.
Zheng, Q., Cox, I. A., Campbell, J. A., Xia, Q., Otahal, P., Graaff, B. de, Corte, T. J., Teoh, A. K. Walters, E. H., & Palmer, A. J. (2022). Mortality and survival in idiopathic pulmonary fibrosis: A systematic review and meta-analysis. ERJ Open Research, 8(1), 00591–2021.
Downloads
Published
Issue
Section
License
Copyright (c) 2026 Doudou Chen, Yu Liu, Zhihao Xu (Author)

This work is licensed under a Creative Commons Attribution 4.0 International License.
All articles published in this journal are licensed under the Creative Commons Attribution 4.0 International License (CC BY 4.0). This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author(s) and source are properly credited. Authors retain copyright of their work, and readers are free to copy, share, adapt, and build upon the material for any purpose, including commercial use, as long as appropriate attribution is given.