Deficient macrophage autophagy protects mice from Cerium Oxide nanoparticle-induced lung fibrosis
Background
Cerium (Ce) is a rare earth element, rapidly oxidizing to form CeO2, and currently used in numerous commercial applications, especially as nanoparticles (NP). The potential health effects of Ce remain uncertain, but literature indicates the development of rare earth pneumoconiosis accompanied with granuloma formation, interstitial fibrosis and inflammation. The exact underlying mechanisms are yet not completely understood, and we propose that autophagy could be an interesting target to study, particularly in macrophages. Therefore, the objective of our study was to investigate the role of macrophagic autophagy after pulmonary exposure to CeO2 NP in mice. Mice lacking the early autophagy gene Atg5 in their myeloid lineage and their wildtype counterparts were exposed to CeO2 NP by single oropharyngeal administration and sacrificed up to one month after. At that time, lung remodeling was thoroughly characterized (inflammatory cells infiltration, expression of fibrotic markers such as αSMA, TGFβ1, total and type I and III collagen deposition), as well as macrophage infiltration (quantification and M1/M2 phenotype).
Results:
Such pulmonary exposure to CeO2 NP induces a progressive and dose-dependent lung fibrosis in the bronchiolar and alveolar walls, together with the activation of autophagy. Blockade of macrophagic autophagy protects from alveolar but not bronchiolar fibrosis, via the modulation of macrophage polarization towards M2 phenotype.
Conclusion:
In conclusion, our findings bring novel insight on the role of macrophagic autophagy in lung fibrogenesis, and add to the current awareness of pulmonary macrophages as potential new therapeutic targets for future anti-fibrotic therapies.
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Additional Figure 6: Characterization of macrophage polarization in vitro iNOS (Panel A), CD68 (Panel B), Arginase 1 (Panel C) or CD206 (Panel D) expression in mice peritoneal macrophages in response to Saline or 10 µg/ml CeO2 NP.
Additional Figure 5: Macrophages are responsible of Atg5+/- mice protection against alveolar remodeling Representative lung tissue sections of mice exposed to Saline or CeO2 NP in presence of clodronate, and stained Hematoxylin Eosin. Original magnification x200.
Additional Figure 4: X-Ray microfluoresence and XANES spectra of CeO2-exposed mice Representative images of XRF maps of Saline (Panel A and C) and CeO2 NP-exposed (Panel B and D) lungs from WT (Panel A and B) or Atg5+/- (Panel C and D) mice. Original magnification x100. False colors used in correlation XRF maps represent P (green), S (blue) and Ce (red). Panel E: XANES spectra at the Ce edge for Reference (blue line), and representative Ce spots (red, green and yellow lines).
Additional Figure 3: Expression of Atg5 peritoneal macrophages of CeO2-exposed mice Expression of Atg5 in peritoneal macrophages from CeO2-exposed in WT and Atg5+/- mice.
Additional Figure 2: Expression of Atg5 in lungs Representative lung tissue sections of mice exposed to Saline or 50 µg CeO2 NP and stained, after 28 days, for Atg5. Original magnification x200.
Additional Figure 1: Cell differential in CeO2-exposed mice Quantification of cell differential in BAL fluid 24h (Panel A), 1 week (panel B) or 28 days (Panel C) post-exposure to CeO2 NP. Each individual circle represents the value obtained from one animal (empty circle: saline exposure – plain circle: CeO2 NP-exposure). *p<0.05. Representative images of NP internalized by alveolar macrophages (Panel D).
On 10 Jan, 2021
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On 14 Jul, 2020
Deficient macrophage autophagy protects mice from Cerium Oxide nanoparticle-induced lung fibrosis
On 10 Jan, 2021
On 10 Jan, 2021
On 10 Jan, 2021
On 29 Dec, 2020
Received 28 Dec, 2020
On 21 Dec, 2020
On 21 Dec, 2020
Invitations sent on 21 Dec, 2020
On 21 Dec, 2020
Received 21 Dec, 2020
Received 21 Dec, 2020
On 20 Dec, 2020
On 20 Dec, 2020
On 20 Dec, 2020
On 17 Dec, 2020
Received 15 Dec, 2020
Received 30 Nov, 2020
Received 29 Nov, 2020
On 04 Nov, 2020
On 02 Nov, 2020
On 01 Nov, 2020
Invitations sent on 01 Nov, 2020
On 01 Nov, 2020
On 01 Nov, 2020
On 01 Nov, 2020
Posted 16 Jul, 2020
Received 26 Aug, 2020
On 26 Aug, 2020
Received 17 Aug, 2020
On 11 Aug, 2020
Received 06 Aug, 2020
On 24 Jul, 2020
Invitations sent on 23 Jul, 2020
On 23 Jul, 2020
On 15 Jul, 2020
On 15 Jul, 2020
On 14 Jul, 2020
On 14 Jul, 2020
Background
Cerium (Ce) is a rare earth element, rapidly oxidizing to form CeO2, and currently used in numerous commercial applications, especially as nanoparticles (NP). The potential health effects of Ce remain uncertain, but literature indicates the development of rare earth pneumoconiosis accompanied with granuloma formation, interstitial fibrosis and inflammation. The exact underlying mechanisms are yet not completely understood, and we propose that autophagy could be an interesting target to study, particularly in macrophages. Therefore, the objective of our study was to investigate the role of macrophagic autophagy after pulmonary exposure to CeO2 NP in mice. Mice lacking the early autophagy gene Atg5 in their myeloid lineage and their wildtype counterparts were exposed to CeO2 NP by single oropharyngeal administration and sacrificed up to one month after. At that time, lung remodeling was thoroughly characterized (inflammatory cells infiltration, expression of fibrotic markers such as αSMA, TGFβ1, total and type I and III collagen deposition), as well as macrophage infiltration (quantification and M1/M2 phenotype).
Results:
Such pulmonary exposure to CeO2 NP induces a progressive and dose-dependent lung fibrosis in the bronchiolar and alveolar walls, together with the activation of autophagy. Blockade of macrophagic autophagy protects from alveolar but not bronchiolar fibrosis, via the modulation of macrophage polarization towards M2 phenotype.
Conclusion:
In conclusion, our findings bring novel insight on the role of macrophagic autophagy in lung fibrogenesis, and add to the current awareness of pulmonary macrophages as potential new therapeutic targets for future anti-fibrotic therapies.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9