A lung-on-chip model of early M. tuberculosis infection reveals an essential role for alveolar epithelial cells in controlling bacterial growth
- Swiss Federal Institute of Technology in Lausanne (EPFL), Switzerland
- University of Cincinnati, United States
- Emulate Inc, United States
Abstract
We establish a murine lung-on-chip infection model and use time-lapse imaging to reveal the dynamics of host-Mycobacterium tuberculosis interactions at an air-liquid interface with a spatiotemporal resolution unattainable in animal models and to probe the direct role of pulmonary surfactant in early infection. Surfactant deficiency results in rapid and uncontrolled bacterial growth in both macrophages and alveolar epithelial cells. In contrast, under normal surfactant levels, a significant fraction of intracellular bacteria are non-growing. The surfactant-deficient phenotype is rescued by exogenous addition of surfactant replacement formulations, which have no effect on bacterial viability in the absence of host cells. Surfactant partially removes virulence-associated lipids and proteins from the bacterial cell surface. Consistent with this mechanism, the attenuation of bacteria lacking the ESX-1 secretion system is independent of surfactant levels. These findings may partly explain why smokers and elderly persons with compromised surfactant function are at increased risk of developing active tuberculosis.
Data availability
Figures in the main text include all the data for bacterial growth rates within the scatter plots, and all the data for qRT-PCR measurements and quantification of lamellar body size, number, and volume. A summary of the code used to calculate growth rates is included in the Materials and Methods. Annotated code used for data analysis written in Matlab, raw data for bacterial fluorescence intensity over time that was used to calculate growth rates, and image stacks related to Fig. 1, Fig. 1 - figure supplement 3 and Fig. 2 - figure supplement 1is available on Zenodo under DOI 10.5281/zenodo.4266198.
Article and author information
Author details
Funding
Human Frontier Science Program (Long-Term Fellowship,LT000231/2016-L)
- Vivek V Thacker
European Molecular Biology Organization (Long-Term Fellowship,921-2015)
- Vivek V Thacker
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung (Project Funding,310030B_176397)
- John D McKinney
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: Animal protocols were reviewed and approved by EPFL's Chief Veterinarian, by the Service de la Consommation et des Affaires Vétérinaires of the Canton of Vaud, and by the Swiss Office Vétérinaire Fédéral (License Number VD 3434 for experiments involving organ collection and License Number VD 3472 for experiments involving infection with Mycobacterium tuberculosis)
Copyright
© 2020, Thacker et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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A lung-on-chip model of early M. tuberculosis infection reveals an essential role for alveolar epithelial cells in controlling bacterial growth
eLife 9:e59961.
https://doi.org/10.7554/eLife.59961
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