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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

Polymorphonuclear neutrophils reduce A. niger germination and hyphal length at the surface of A549 cells.A. fumigatus and A. niger percentage of germination (A,C) and hyphal length (B,D) in the presence of A549 cells. Bars represent standard error of the mean. ∗ Indicate significant differences. Data are obtained from three separate experiments; at least 100 conidia per condition were analyzed.
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Figure 6: Polymorphonuclear neutrophils reduce A. niger germination and hyphal length at the surface of A549 cells.A. fumigatus and A. niger percentage of germination (A,C) and hyphal length (B,D) in the presence of A549 cells. Bars represent standard error of the mean. ∗ Indicate significant differences. Data are obtained from three separate experiments; at least 100 conidia per condition were analyzed.

Mentions: Polymorphonuclear neutrophils are crucial in controlling IA by killing conidia and hyphal structures by means of phagocytosis or by degranulation and NETs formation (McCormick et al., 2010a; Braem et al., 2015). Here, the effect of PMNs was investigated on germination and hyphal growth of A. fumigatus and A. niger. To this end, PMNs were added to the A549 monolayer that had been challenged with A. fumigatus and A. niger conidia. PMNs did not inhibit germination of conidia of A. fumigatus and the outgrowth of hyphae (Figures 6C,D). In contrast, germination of conidia of A. niger was reduced by 31% in the presence of PMNs (Figure 6A). In addition, the length of A. niger hyphae was reduced by 24% (Figure 6B). The effect of PMNs on germination and hyphal length was also studied in the absence of epithelial cells. The inhibitory effects of PMNs were stronger in the absence of A549. Germination of A. niger conidia was reduced by 73% in the presence of PMNs, whereas hyphal length was reduced by 50% (Figures 7A,B). Germination of conidia of A. fumigatus was reduced by 31% with no significant effects on hyphal length (Figures 7C,D).


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)

Polymorphonuclear neutrophils reduce A. niger germination and hyphal length at the surface of A549 cells.A. fumigatus and A. niger percentage of germination (A,C) and hyphal length (B,D) in the presence of A549 cells. Bars represent standard error of the mean. ∗ Indicate significant differences. Data are obtained from three separate experiments; 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 6: Polymorphonuclear neutrophils reduce A. niger germination and hyphal length at the surface of A549 cells.A. fumigatus and A. niger percentage of germination (A,C) and hyphal length (B,D) in the presence of A549 cells. Bars represent standard error of the mean. ∗ Indicate significant differences. Data are obtained from three separate experiments; at least 100 conidia per condition were analyzed.
Mentions: Polymorphonuclear neutrophils are crucial in controlling IA by killing conidia and hyphal structures by means of phagocytosis or by degranulation and NETs formation (McCormick et al., 2010a; Braem et al., 2015). Here, the effect of PMNs was investigated on germination and hyphal growth of A. fumigatus and A. niger. To this end, PMNs were added to the A549 monolayer that had been challenged with A. fumigatus and A. niger conidia. PMNs did not inhibit germination of conidia of A. fumigatus and the outgrowth of hyphae (Figures 6C,D). In contrast, germination of conidia of A. niger was reduced by 31% in the presence of PMNs (Figure 6A). In addition, the length of A. niger hyphae was reduced by 24% (Figure 6B). The effect of PMNs on germination and hyphal length was also studied in the absence of epithelial cells. The inhibitory effects of PMNs were stronger in the absence of A549. Germination of A. niger conidia was reduced by 73% in the presence of PMNs, whereas hyphal length was reduced by 50% (Figures 7A,B). Germination of conidia of A. fumigatus was reduced by 31% with no significant effects on hyphal length (Figures 7C,D).

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