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Hide, Keep Quiet, and Keep Low: Properties That Make Aspergillus fumigatus a Successful Lung Pathogen.

Escobar N, Ordonez SR, Wösten HA, Haas PJ, de Cock H, Haagsman HP - Front Microbiol (2016)

Bottom Line: Germination of A. fumigatus and A. niger conidia in the presence of epithelial cells was delayed when compared to conidia in the medium.Neutrophils reduced germination and hyphal growth of A. niger, but not of A fumigatus, in presence of epithelial cells.Taken together, efficient internalization, delayed germination, and hyphal growth parallel to the epithelium gives a new insight into what could be the causes for the success of A. fumigatus compared to A. niger as an opportunistic pathogen in the lung.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Institute of Biomembranes, Utrecht University Utrecht, Netherlands.

ABSTRACT
Representatives of the genus Aspergillus are opportunistic fungal pathogens. Their conidia can reach the alveoli by inhalation and can give rise to infections in immunocompromised individuals. Aspergillus fumigatus is the causal agent of invasive aspergillosis in nearly 90% of the cases. It is not yet well-established what makes this fungus more pathogenic than other aspergilli such as A. niger. Here, we show that A. fumigatus and A. niger conidia adhere with similar efficiency to lung epithelial A549 cells but A. fumigatus conidia internalized 17% more efficiently. Conidia of both aspergilli were taken up in phagolysosomes 8 h after the challenge. These organelles only acidified in the case of A. niger, which is probably due to the type of melanin coating of the conidia. Viability of both types of conidia was not affected after uptake in the phagolysosomes. Germination of A. fumigatus and A. niger conidia in the presence of epithelial cells was delayed when compared to conidia in the medium. However, germination of A. niger conidia was still higher than that of A. fumigatus 10 h after exposure to A549 cells. Remarkably, A. fumigatus hyphae grew mainly parallel to the epithelium, while growth direction of A. niger hyphae was predominantly perpendicular to the plane of the cells. Neutrophils reduced germination and hyphal growth of A. niger, but not of A fumigatus, in presence of epithelial cells. Taken together, efficient internalization, delayed germination, and hyphal growth parallel to the epithelium gives a new insight into what could be the causes for the success of A. fumigatus compared to A. niger as an opportunistic pathogen in the lung.

No MeSH data available.


Related in: MedlinePlus

Aspergillus fumigatus melanin inhibits acidification of cellular compartments. Tracking of acidification inside cellular compartments containing Cy-pHer5e-labeled conidia (CC). Wild-type A. niger and A. fumigatus and of white strains (AN_white and AF_white). pH calibration curve of AF-CC (A), AF_white-CC (C), AN-CC (E), and AN_white-CC (G) and total fluorescence in time of AF-CC (B), AF_white-CC (D), AN-CC (F), and AN_white-CC (H). Values are expressed as the mean of the corrected total fluorescence (CTCF). Bars represent standard error of the mean. ∗Indicates significant difference. Data obtained from three separate experiments analyzing at least 100 conidia per condition were analyzed.
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Figure 3: Aspergillus fumigatus melanin inhibits acidification of cellular compartments. Tracking of acidification inside cellular compartments containing Cy-pHer5e-labeled conidia (CC). Wild-type A. niger and A. fumigatus and of white strains (AN_white and AF_white). pH calibration curve of AF-CC (A), AF_white-CC (C), AN-CC (E), and AN_white-CC (G) and total fluorescence in time of AF-CC (B), AF_white-CC (D), AN-CC (F), and AN_white-CC (H). Values are expressed as the mean of the corrected total fluorescence (CTCF). Bars represent standard error of the mean. ∗Indicates significant difference. Data obtained from three separate experiments analyzing at least 100 conidia per condition were analyzed.

Mentions: Labeling of acidic compartments by LysoSensorTM and labeling of conidia by a pH sensitive dye (CypHer5E) were used to address whether acidification of the phagolysosomes occurred. LysoSensor strongly stained compartments in A549 cells. However, internalized conidia of both A. fumigatus and A. niger were not surrounded by the label, even 8 h after the challenge (Supplementary Figure S2). To confirm the LysoSensor results, conidia were labeled with the pH sensitive dye CypHer5E. Fluorescence of CypHer5E bound to A. fumigatus conidia indicated a pH of 6 between 2 and 6 h after the challenge and a pH of 5 after 8 h (Figures 3A,B). In contrast, fluorescence of CypHer5E bound to A. niger conidia showed a gradual drop to pH 4 after 4 h, remaining stable until 8 h after the challenge (Figures 3E,F).


Hide, Keep Quiet, and Keep Low: Properties That Make Aspergillus fumigatus a Successful Lung Pathogen.

Escobar N, Ordonez SR, Wösten HA, Haas PJ, de Cock H, Haagsman HP - Front Microbiol (2016)

Aspergillus fumigatus melanin inhibits acidification of cellular compartments. Tracking of acidification inside cellular compartments containing Cy-pHer5e-labeled conidia (CC). Wild-type A. niger and A. fumigatus and of white strains (AN_white and AF_white). pH calibration curve of AF-CC (A), AF_white-CC (C), AN-CC (E), and AN_white-CC (G) and total fluorescence in time of AF-CC (B), AF_white-CC (D), AN-CC (F), and AN_white-CC (H). Values are expressed as the mean of the corrected total fluorescence (CTCF). Bars represent standard error of the mean. ∗Indicates significant difference. Data obtained from three separate experiments analyzing at least 100 conidia per condition were analyzed.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4821987&req=5

Figure 3: Aspergillus fumigatus melanin inhibits acidification of cellular compartments. Tracking of acidification inside cellular compartments containing Cy-pHer5e-labeled conidia (CC). Wild-type A. niger and A. fumigatus and of white strains (AN_white and AF_white). pH calibration curve of AF-CC (A), AF_white-CC (C), AN-CC (E), and AN_white-CC (G) and total fluorescence in time of AF-CC (B), AF_white-CC (D), AN-CC (F), and AN_white-CC (H). Values are expressed as the mean of the corrected total fluorescence (CTCF). Bars represent standard error of the mean. ∗Indicates significant difference. Data obtained from three separate experiments analyzing at least 100 conidia per condition were analyzed.
Mentions: Labeling of acidic compartments by LysoSensorTM and labeling of conidia by a pH sensitive dye (CypHer5E) were used to address whether acidification of the phagolysosomes occurred. LysoSensor strongly stained compartments in A549 cells. However, internalized conidia of both A. fumigatus and A. niger were not surrounded by the label, even 8 h after the challenge (Supplementary Figure S2). To confirm the LysoSensor results, conidia were labeled with the pH sensitive dye CypHer5E. Fluorescence of CypHer5E bound to A. fumigatus conidia indicated a pH of 6 between 2 and 6 h after the challenge and a pH of 5 after 8 h (Figures 3A,B). In contrast, fluorescence of CypHer5E bound to A. niger conidia showed a gradual drop to pH 4 after 4 h, remaining stable until 8 h after the challenge (Figures 3E,F).

Bottom Line: Germination of A. fumigatus and A. niger conidia in the presence of epithelial cells was delayed when compared to conidia in the medium.Neutrophils reduced germination and hyphal growth of A. niger, but not of A fumigatus, in presence of epithelial cells.Taken together, efficient internalization, delayed germination, and hyphal growth parallel to the epithelium gives a new insight into what could be the causes for the success of A. fumigatus compared to A. niger as an opportunistic pathogen in the lung.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Institute of Biomembranes, Utrecht University Utrecht, Netherlands.

ABSTRACT
Representatives of the genus Aspergillus are opportunistic fungal pathogens. Their conidia can reach the alveoli by inhalation and can give rise to infections in immunocompromised individuals. Aspergillus fumigatus is the causal agent of invasive aspergillosis in nearly 90% of the cases. It is not yet well-established what makes this fungus more pathogenic than other aspergilli such as A. niger. Here, we show that A. fumigatus and A. niger conidia adhere with similar efficiency to lung epithelial A549 cells but A. fumigatus conidia internalized 17% more efficiently. Conidia of both aspergilli were taken up in phagolysosomes 8 h after the challenge. These organelles only acidified in the case of A. niger, which is probably due to the type of melanin coating of the conidia. Viability of both types of conidia was not affected after uptake in the phagolysosomes. Germination of A. fumigatus and A. niger conidia in the presence of epithelial cells was delayed when compared to conidia in the medium. However, germination of A. niger conidia was still higher than that of A. fumigatus 10 h after exposure to A549 cells. Remarkably, A. fumigatus hyphae grew mainly parallel to the epithelium, while growth direction of A. niger hyphae was predominantly perpendicular to the plane of the cells. Neutrophils reduced germination and hyphal growth of A. niger, but not of A fumigatus, in presence of epithelial cells. Taken together, efficient internalization, delayed germination, and hyphal growth parallel to the epithelium gives a new insight into what could be the causes for the success of A. fumigatus compared to A. niger as an opportunistic pathogen in the lung.

No MeSH data available.


Related in: MedlinePlus