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Vimentin regulates activation of the NLRP3 inflammasome.

dos Santos G, Rogel MR, Baker MA, Troken JR, Urich D, Morales-Nebreda L, Sennello JA, Kutuzov MA, Sitikov A, Davis JM, Lam AP, Cheresh P, Kamp D, Shumaker DK, Budinger GR, Ridge KM - Nat Commun (2015)

Bottom Line: Activation of the NLRP3 inflammasome and subsequent maturation of IL-1β have been implicated in acute lung injury (ALI), resulting in inflammation and fibrosis.Furthermore, decreased active caspase-1 and IL-1β levels are observed in vitro in Vim(-/-) and vimentin-knockdown macrophages.This study provides insights into lung inflammation and fibrosis and suggests that vimentin may be a key regulator of the NLRP3 inflammasome.

View Article: PubMed Central - PubMed

Affiliation: Division of Pulmonary and Critical Care Medicine, Northwestern University, Chicago, Illinois 60611, USA.

ABSTRACT
Activation of the NLRP3 inflammasome and subsequent maturation of IL-1β have been implicated in acute lung injury (ALI), resulting in inflammation and fibrosis. We investigated the role of vimentin, a type III intermediate filament, in this process using three well-characterized murine models of ALI known to require NLRP3 inflammasome activation. We demonstrate that central pathophysiologic events in ALI (inflammation, IL-1β levels, endothelial and alveolar epithelial barrier permeability, remodelling and fibrosis) are attenuated in the lungs of Vim(-/-) mice challenged with LPS, bleomycin and asbestos. Bone marrow chimeric mice lacking vimentin have reduced IL-1β levels and attenuated lung injury and fibrosis following bleomycin exposure. Furthermore, decreased active caspase-1 and IL-1β levels are observed in vitro in Vim(-/-) and vimentin-knockdown macrophages. Importantly, we show direct protein-protein interaction between NLRP3 and vimentin. This study provides insights into lung inflammation and fibrosis and suggests that vimentin may be a key regulator of the NLRP3 inflammasome.

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Bleomycin-induced lung injury and fibrosis are prevented in the absence of vimentinShown is histology of mice lungs 21 d following intratracheal instillation of bleomycin or PBS. Masson trichrome (A) and Picrosirius Red (B) stains for collagen. Original magnification for overview mosaics, ×5. Enlargements were taken with a 40× objective (scale bars, 200 μm). (C) Representative elastographs from AFM micro-indentation of lung tissue from WT and Vim-/- animals. The color bar indicates elastic modulus, E. The darkest red corresponds to elastic modulus values of 50 kPa and above. The data represent 256 indentations per region, with at least two regions per tissue section from at least three mice per group. (D) Collagen content in lungs from WT and Vim-/- mice assessed by Sircol assay. (E) Mice were ventilated at 21 d after intratracheal instillation of bleomycin or PBS. Shown are quasi-static compliance measurements of WT and Vim-/- lungs. (F) Elastic modulus frequency plot obtained from live, unfixed lung tissue of saline and bleomycin-treated WT and Vim-/- animals. Microindentation data were fit using the Hertz model to acquire the elastic modulus of regions of lung tissue. Images in A-B represent data obtained from at least three animals per group; data shown in D-E are mean ± SD of at least five animals. **P < 0.001, ***P<0.0001 relative to WT versus Vim-/-, by one way ANOVA with a correction provided by the Bonferroni multiple comparisons test.
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Figure 4: Bleomycin-induced lung injury and fibrosis are prevented in the absence of vimentinShown is histology of mice lungs 21 d following intratracheal instillation of bleomycin or PBS. Masson trichrome (A) and Picrosirius Red (B) stains for collagen. Original magnification for overview mosaics, ×5. Enlargements were taken with a 40× objective (scale bars, 200 μm). (C) Representative elastographs from AFM micro-indentation of lung tissue from WT and Vim-/- animals. The color bar indicates elastic modulus, E. The darkest red corresponds to elastic modulus values of 50 kPa and above. The data represent 256 indentations per region, with at least two regions per tissue section from at least three mice per group. (D) Collagen content in lungs from WT and Vim-/- mice assessed by Sircol assay. (E) Mice were ventilated at 21 d after intratracheal instillation of bleomycin or PBS. Shown are quasi-static compliance measurements of WT and Vim-/- lungs. (F) Elastic modulus frequency plot obtained from live, unfixed lung tissue of saline and bleomycin-treated WT and Vim-/- animals. Microindentation data were fit using the Hertz model to acquire the elastic modulus of regions of lung tissue. Images in A-B represent data obtained from at least three animals per group; data shown in D-E are mean ± SD of at least five animals. **P < 0.001, ***P<0.0001 relative to WT versus Vim-/-, by one way ANOVA with a correction provided by the Bonferroni multiple comparisons test.

Mentions: Bleomycin exposure to results in chronic inflammation and progressive pulmonary fibrosis19,35. The role of vimentin in pulmonary fibrosis was examined 21 d following administration of bleomycin. The lung architecture was similar for saline-treated WT and Vim-/- mice, but in WT mice bleomycin induced extensive fibrotic areas with abundant collagen production, as assessed by Masson trichrome stain (Figure 4A and Supplemental Figure 4A). Cellular infiltrates, alveolar wall destruction, and collagen deposition were significantly reduced in Vim-/- mice. Similarly, we observed increases in collagen deposition in bleomycin-treated WT mice by staining with Picrosirius red (Figure 4B). In contrast, there was virtually no collagen deposition in the lungs of Vim-/- mice (Figure 4B). Lung collagen concentrations, as assessed by Sircol assay, were 0.57 ± 0.09 and 0.31 ± 0.03 mg per lung in bleomycin-treated WT and Vim-/- mice, respectively (Figure 4D).


Vimentin regulates activation of the NLRP3 inflammasome.

dos Santos G, Rogel MR, Baker MA, Troken JR, Urich D, Morales-Nebreda L, Sennello JA, Kutuzov MA, Sitikov A, Davis JM, Lam AP, Cheresh P, Kamp D, Shumaker DK, Budinger GR, Ridge KM - Nat Commun (2015)

Bleomycin-induced lung injury and fibrosis are prevented in the absence of vimentinShown is histology of mice lungs 21 d following intratracheal instillation of bleomycin or PBS. Masson trichrome (A) and Picrosirius Red (B) stains for collagen. Original magnification for overview mosaics, ×5. Enlargements were taken with a 40× objective (scale bars, 200 μm). (C) Representative elastographs from AFM micro-indentation of lung tissue from WT and Vim-/- animals. The color bar indicates elastic modulus, E. The darkest red corresponds to elastic modulus values of 50 kPa and above. The data represent 256 indentations per region, with at least two regions per tissue section from at least three mice per group. (D) Collagen content in lungs from WT and Vim-/- mice assessed by Sircol assay. (E) Mice were ventilated at 21 d after intratracheal instillation of bleomycin or PBS. Shown are quasi-static compliance measurements of WT and Vim-/- lungs. (F) Elastic modulus frequency plot obtained from live, unfixed lung tissue of saline and bleomycin-treated WT and Vim-/- animals. Microindentation data were fit using the Hertz model to acquire the elastic modulus of regions of lung tissue. Images in A-B represent data obtained from at least three animals per group; data shown in D-E are mean ± SD of at least five animals. **P < 0.001, ***P<0.0001 relative to WT versus Vim-/-, by one way ANOVA with a correction provided by the Bonferroni multiple comparisons test.
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Figure 4: Bleomycin-induced lung injury and fibrosis are prevented in the absence of vimentinShown is histology of mice lungs 21 d following intratracheal instillation of bleomycin or PBS. Masson trichrome (A) and Picrosirius Red (B) stains for collagen. Original magnification for overview mosaics, ×5. Enlargements were taken with a 40× objective (scale bars, 200 μm). (C) Representative elastographs from AFM micro-indentation of lung tissue from WT and Vim-/- animals. The color bar indicates elastic modulus, E. The darkest red corresponds to elastic modulus values of 50 kPa and above. The data represent 256 indentations per region, with at least two regions per tissue section from at least three mice per group. (D) Collagen content in lungs from WT and Vim-/- mice assessed by Sircol assay. (E) Mice were ventilated at 21 d after intratracheal instillation of bleomycin or PBS. Shown are quasi-static compliance measurements of WT and Vim-/- lungs. (F) Elastic modulus frequency plot obtained from live, unfixed lung tissue of saline and bleomycin-treated WT and Vim-/- animals. Microindentation data were fit using the Hertz model to acquire the elastic modulus of regions of lung tissue. Images in A-B represent data obtained from at least three animals per group; data shown in D-E are mean ± SD of at least five animals. **P < 0.001, ***P<0.0001 relative to WT versus Vim-/-, by one way ANOVA with a correction provided by the Bonferroni multiple comparisons test.
Mentions: Bleomycin exposure to results in chronic inflammation and progressive pulmonary fibrosis19,35. The role of vimentin in pulmonary fibrosis was examined 21 d following administration of bleomycin. The lung architecture was similar for saline-treated WT and Vim-/- mice, but in WT mice bleomycin induced extensive fibrotic areas with abundant collagen production, as assessed by Masson trichrome stain (Figure 4A and Supplemental Figure 4A). Cellular infiltrates, alveolar wall destruction, and collagen deposition were significantly reduced in Vim-/- mice. Similarly, we observed increases in collagen deposition in bleomycin-treated WT mice by staining with Picrosirius red (Figure 4B). In contrast, there was virtually no collagen deposition in the lungs of Vim-/- mice (Figure 4B). Lung collagen concentrations, as assessed by Sircol assay, were 0.57 ± 0.09 and 0.31 ± 0.03 mg per lung in bleomycin-treated WT and Vim-/- mice, respectively (Figure 4D).

Bottom Line: Activation of the NLRP3 inflammasome and subsequent maturation of IL-1β have been implicated in acute lung injury (ALI), resulting in inflammation and fibrosis.Furthermore, decreased active caspase-1 and IL-1β levels are observed in vitro in Vim(-/-) and vimentin-knockdown macrophages.This study provides insights into lung inflammation and fibrosis and suggests that vimentin may be a key regulator of the NLRP3 inflammasome.

View Article: PubMed Central - PubMed

Affiliation: Division of Pulmonary and Critical Care Medicine, Northwestern University, Chicago, Illinois 60611, USA.

ABSTRACT
Activation of the NLRP3 inflammasome and subsequent maturation of IL-1β have been implicated in acute lung injury (ALI), resulting in inflammation and fibrosis. We investigated the role of vimentin, a type III intermediate filament, in this process using three well-characterized murine models of ALI known to require NLRP3 inflammasome activation. We demonstrate that central pathophysiologic events in ALI (inflammation, IL-1β levels, endothelial and alveolar epithelial barrier permeability, remodelling and fibrosis) are attenuated in the lungs of Vim(-/-) mice challenged with LPS, bleomycin and asbestos. Bone marrow chimeric mice lacking vimentin have reduced IL-1β levels and attenuated lung injury and fibrosis following bleomycin exposure. Furthermore, decreased active caspase-1 and IL-1β levels are observed in vitro in Vim(-/-) and vimentin-knockdown macrophages. Importantly, we show direct protein-protein interaction between NLRP3 and vimentin. This study provides insights into lung inflammation and fibrosis and suggests that vimentin may be a key regulator of the NLRP3 inflammasome.

Show MeSH
Related in: MedlinePlus