Another new class of mycotoxins discovered (by I Yike, T Rand, DG Dearborn)

[Guest guest]

This is important work because these new molecules need to be

considered if we go the exposure limit route and set exposure limits.

(instead of an outright ban like Canada has done) As Dr. Straus said

once " new ones are being discovered all of the time " . Stachybotrys has

had MANY millions of years to develop all these toxins, now we are

playing catch up trying to discover all of the many varieties of them

so limits can be set on each one.

But there are so many. This is a good example of that.

Mycopathologia. 2007 Jul 3;

The role of fungal proteinases in pathophysiology of Stachybotrys chartarum.

Yike I, Rand T, Dearborn DG.

Ann Swetland Center for Environmental Health, Case Western

Reserve University, Cleveland, OH, USA.

The adverse health effects of Stachybotrys chartarum have often

been linked to exposure to the trichothecene mycotoxins. Recent

studies have shown that in addition to mycotoxins this fungus is

capable of producing and secreting in vivo proteins such as hemolysins

and proteinases. Spore extracts obtained from a high trichothecene

producing isolate JS 58-17 exhibited a significantly lower proteolytic

activity compared to the low trichothecene producer, JS 58-06. Growing

isolates on rice or potato dextrose agar results in higher proteolytic

activity of the spores compared to those grown on drywall. Proteinases

in the spore extracts can hydrolyze gelatin and collagen I and IV.

Analysis of zymograms shows the presence of several proteins with

proteolytic activity in the spores of S. chartarum. Human tracheal

epithelial cells exposed to spore extracts produced significantly

higher levels of IL-6, IL-8, and TNF-alpha than control cells. This

stimulation of cytokine production was completely abolished by

Pefabloc, a serine protease inhibitor. Neutrophil numbers and

proinflammatory cytokine (IL1-beta and TNF-alpha) concentrations were

highly elevated in the lungs of 7 day old rat pups exposed

intratracheally to 4 x 10(4) spores/gm body weight compared to

control. No significant differences in those inflammatory indices in

vivo were noted between the treatments with the high trichothecene

producer, isolate JS 58-17 and JS 58-06, which does not produce

macrocyclic trichothecenes. Immunohistochemistry revealed reduced

collagen IV labeling in spore-induced lung granulomas in rat pups

exposed to both isolates. These results suggest that proteinases from

S. chartarum spores significantly contribute to lung inflammation and

injury.

PMID: 17610048 [PubMed - as supplied by publisher]