New Basic Mold Research

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 This NEW research explains why MOST people DON'T get sick from mold. Maybe

some researchers can build upon this discovery, to figure out why WE DO get

sick from mold. When you click on the link, you can save and print out the free

summary PDF of this article. You may have to register first, with the science

journal.

 

Joe

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Nature Reviews Immunology 9, 672-673 (October 2009) | doi :10.1038/nri2641

Innate immunity: A protective fungal spore coat

Christiaan van Ooij1

Author affiliations

Chief Editor, Nature Reviews Microbiology

Published online 18 September 2009

 

Although every breath we take contains thousands of fungal spores, these spores

do not trigger an immune response. Latgé and colleagues, writing in a recent

issue of Nature, show that the surface hydrophobin (RodA) that forms the rodlet

layer around fungal spores (the conidia) prevents their recognition by dendritic

cells (DCs) and the subsequent immune response.

To test why conidia are not immunogenic, the authors looked in vitro at the

effect of Aspergillus fumigatus RodA on human DCs. The protein did not elicit a

response, as measured by the production of cytokines and proliferation of CD4+ T

cells. RodA does not act as an inhibitor of DCs, as DCs were activated when

exposed to RodA mixed with A. fumigatus antigens that are known to activate

these cells.

The protective role of RodA in A. fumigatus conidia was confirmed by exposing

DCs to conidia that lacked RodA (owing either to a deletion of the gene that

encodes RodA (rodA) or to chemical removal of the rodlet layer) or to germinated

spores, which have shed RodA. The DCs responded to these morphotypes by

producing inflammatory cytokines, chemokines and reactive oxygen intermediates.

Conidial hydrophobins that were purified from other air-borne filamentous fungi

were also unable to induce an immune response in DCs, and chemical removal of

the rodlet layer made the conidia immunogenic. It therefore seems that the

rodlet layer provides a protective layer around the conidia of filamentous fungi

that covers the immunogenic molecules in the underlying cell wall. Finally, the

protective role of A. fumigatus RodA was demonstrated in vivo. When mice were

inoculated intranasally, rodA conidia and germinated spores elicited immune

responses, as measured by the

infiltration of neutrophils into the lungs and the production of cytokines and

chemokines in the lungs, whereas purified RodA and wild-type conidia were

immunologically inert.

The avoidance of immune activation has benefits for both the fungus and the

host. For the host it prevents chronic activation of the immune system in

response to the constant inhalation of spores, whereas for the fungus it

prevents rapid elimination, allowing the cells to survive in the lungs of the

host until an opportunity to germinate and proliferate arises.

References and links

Aimanianda, V. et al. Surface hydrophobin prevents immune recognition of

airborne fungal spores. Nature 460, 1117–1121 (2009) 

Link to FREE 1 page PDF summary: 

http://www.nature.com/nri/journal/v9/n10/pdf/nri2641.pdf

 

Link to 4 page complete article (price $32):

http://www.nature.com/nature/journal/v460/n7259/full/nature08264.html