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Effects of Eyjafjallajökull volcanic ash on innate immune system responses and bacterial growth in vitro.

Monick MM, Baltrusaitis J, Powers LS, Borcherding JA, Caraballo JC, Mudunkotuwa I, Peate DW, Walters K, Thompson JM, Grassian VH, Gudmundsson G, Comellas AP - Environ. Health Perspect. (2013)

Bottom Line: In alveolar macrophages, volcanic ash disrupted pathogen-killing and inflammatory responses.In in vitro bacterial growth models, volcanic ash increased bacterial replication and decreased bacterial killing by antimicrobial peptides.These data suggest that volcanic ash exposure, while not seriously compromising lung cell function, may be able to impair innate immunity responses in exposed individuals.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.

ABSTRACT

Background: On 20 March 2010, the Icelandic volcano Eyjafjallajökull erupted for the first time in 190 years. Despite many epidemiological reports showing effects of volcanic ash on the respiratory system, there are limited data evaluating cellular mechanisms involved in the response to ash. Epidemiological studies have observed an increase in respiratory infections in subjects and populations exposed to volcanic eruptions.

Methods: We physicochemically characterized volcanic ash, finding various sizes of particles, as well as the presence of several transition metals, including iron. We examined the effect of Eyjafjallajökull ash on primary rat alveolar epithelial cells and human airway epithelial cells (20-100 µg/cm(2)), primary rat and human alveolar macrophages (5-20 µg/cm(2)), and Pseudomonas aeruginosa (PAO1) growth (3 µg/104 bacteria).

Results: Volcanic ash had minimal effect on alveolar and airway epithelial cell integrity. In alveolar macrophages, volcanic ash disrupted pathogen-killing and inflammatory responses. In in vitro bacterial growth models, volcanic ash increased bacterial replication and decreased bacterial killing by antimicrobial peptides.

Conclusions: These results provide potential biological plausibility for epidemiological data that show an association between air pollution exposure and the development of respiratory infections. These data suggest that volcanic ash exposure, while not seriously compromising lung cell function, may be able to impair innate immunity responses in exposed individuals.

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Effect of volcanic ash on bacterial growth and on bacterial killing by antimicrobial peptides (AMPs). (A) Growth of PAO1 after 9 hr incubation with media alone (control), FeCl3 (10 µg/mL; positive control), ash (10 µg/mL), or Al2O3 (control for particle effects; 10 µg/mL) as measured at OD600. PAO1 growth was increased after ash exposure compared with the control. (B) Schematic of the AMP activity assay. (C) Results of the AMP activity assay showing the bacterial killing capacity as determined by OD600 measurement. For (A) and (C), n = 3 in triplicate.*p < 0.0001 compared with the control by Student’s t-test. **p < 0.0001 compared with FeCl3 by Student’s t-test.
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f4: Effect of volcanic ash on bacterial growth and on bacterial killing by antimicrobial peptides (AMPs). (A) Growth of PAO1 after 9 hr incubation with media alone (control), FeCl3 (10 µg/mL; positive control), ash (10 µg/mL), or Al2O3 (control for particle effects; 10 µg/mL) as measured at OD600. PAO1 growth was increased after ash exposure compared with the control. (B) Schematic of the AMP activity assay. (C) Results of the AMP activity assay showing the bacterial killing capacity as determined by OD600 measurement. For (A) and (C), n = 3 in triplicate.*p < 0.0001 compared with the control by Student’s t-test. **p < 0.0001 compared with FeCl3 by Student’s t-test.

Mentions: The effect of volcanic ash on bacterial growth and killing capacity of antimicrobial peptides. We examined whether volcanic ash increased bacteria growth by adding 3 µg of sieved volcanic ash particles to 3-hr subcultured PAO1 (104). Volcanic ash can release readily soluble Fe into the environment (Olgun et al. 2011), and the volcanic ash from Eyjafjallajökull is rich in Fe (~ 75,000 mg/kg ash) [see Supplemental Material, Table S2 (http://dx.doi.org/10.1289/ehp.1206004)].Therefore, we used FeCl3 (25 µm), a soluble Fe source, as a positive control. As shown in Figure 4A, bacterial growth was significantly increased after ash exposure compared with the control and the Fe-deficient Al2O3 (p < 0.0001). This result suggests that volcanic ash can be a bioavailable source of Fe for PAO1 growth.


Effects of Eyjafjallajökull volcanic ash on innate immune system responses and bacterial growth in vitro.

Monick MM, Baltrusaitis J, Powers LS, Borcherding JA, Caraballo JC, Mudunkotuwa I, Peate DW, Walters K, Thompson JM, Grassian VH, Gudmundsson G, Comellas AP - Environ. Health Perspect. (2013)

Effect of volcanic ash on bacterial growth and on bacterial killing by antimicrobial peptides (AMPs). (A) Growth of PAO1 after 9 hr incubation with media alone (control), FeCl3 (10 µg/mL; positive control), ash (10 µg/mL), or Al2O3 (control for particle effects; 10 µg/mL) as measured at OD600. PAO1 growth was increased after ash exposure compared with the control. (B) Schematic of the AMP activity assay. (C) Results of the AMP activity assay showing the bacterial killing capacity as determined by OD600 measurement. For (A) and (C), n = 3 in triplicate.*p < 0.0001 compared with the control by Student’s t-test. **p < 0.0001 compared with FeCl3 by Student’s t-test.
© Copyright Policy - public-domain
Related In: Results  -  Collection

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f4: Effect of volcanic ash on bacterial growth and on bacterial killing by antimicrobial peptides (AMPs). (A) Growth of PAO1 after 9 hr incubation with media alone (control), FeCl3 (10 µg/mL; positive control), ash (10 µg/mL), or Al2O3 (control for particle effects; 10 µg/mL) as measured at OD600. PAO1 growth was increased after ash exposure compared with the control. (B) Schematic of the AMP activity assay. (C) Results of the AMP activity assay showing the bacterial killing capacity as determined by OD600 measurement. For (A) and (C), n = 3 in triplicate.*p < 0.0001 compared with the control by Student’s t-test. **p < 0.0001 compared with FeCl3 by Student’s t-test.
Mentions: The effect of volcanic ash on bacterial growth and killing capacity of antimicrobial peptides. We examined whether volcanic ash increased bacteria growth by adding 3 µg of sieved volcanic ash particles to 3-hr subcultured PAO1 (104). Volcanic ash can release readily soluble Fe into the environment (Olgun et al. 2011), and the volcanic ash from Eyjafjallajökull is rich in Fe (~ 75,000 mg/kg ash) [see Supplemental Material, Table S2 (http://dx.doi.org/10.1289/ehp.1206004)].Therefore, we used FeCl3 (25 µm), a soluble Fe source, as a positive control. As shown in Figure 4A, bacterial growth was significantly increased after ash exposure compared with the control and the Fe-deficient Al2O3 (p < 0.0001). This result suggests that volcanic ash can be a bioavailable source of Fe for PAO1 growth.

Bottom Line: In alveolar macrophages, volcanic ash disrupted pathogen-killing and inflammatory responses.In in vitro bacterial growth models, volcanic ash increased bacterial replication and decreased bacterial killing by antimicrobial peptides.These data suggest that volcanic ash exposure, while not seriously compromising lung cell function, may be able to impair innate immunity responses in exposed individuals.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.

ABSTRACT

Background: On 20 March 2010, the Icelandic volcano Eyjafjallajökull erupted for the first time in 190 years. Despite many epidemiological reports showing effects of volcanic ash on the respiratory system, there are limited data evaluating cellular mechanisms involved in the response to ash. Epidemiological studies have observed an increase in respiratory infections in subjects and populations exposed to volcanic eruptions.

Methods: We physicochemically characterized volcanic ash, finding various sizes of particles, as well as the presence of several transition metals, including iron. We examined the effect of Eyjafjallajökull ash on primary rat alveolar epithelial cells and human airway epithelial cells (20-100 µg/cm(2)), primary rat and human alveolar macrophages (5-20 µg/cm(2)), and Pseudomonas aeruginosa (PAO1) growth (3 µg/104 bacteria).

Results: Volcanic ash had minimal effect on alveolar and airway epithelial cell integrity. In alveolar macrophages, volcanic ash disrupted pathogen-killing and inflammatory responses. In in vitro bacterial growth models, volcanic ash increased bacterial replication and decreased bacterial killing by antimicrobial peptides.

Conclusions: These results provide potential biological plausibility for epidemiological data that show an association between air pollution exposure and the development of respiratory infections. These data suggest that volcanic ash exposure, while not seriously compromising lung cell function, may be able to impair innate immunity responses in exposed individuals.

Show MeSH
Related in: MedlinePlus