4 - 2010 abstracts, mycotoxins

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Kinetics of Satratoxin G Tissue Distribution and Excretion Following Intranasal

Exposure in the Mouse

Chidozie J. Amuzie*†, Zahidul Islam‡, Jae Kyung Kim‡, Ji-Hyun Seo‡ and J.

Pestka*†‡§,1

+ Author Affiliations

*Comparative Medicine and Integrative Biology Program

†Center for Integrative Toxicology

‡Department of Food Science and Human Nutrition

§Department of Microbiology and Molecular Genetics, Michigan State University,

East Lansing, Michigan 48824

1To whom correspondence should be addressed at Michigan State University, 234

G.M. Trout Building, East Lansing, MI 48824-1224. Fax: (517) 353-8963. E-mail:

pestka@....

Received February 2, 2010.

Accepted May 7, 2010.

Abstract

Intranasal exposure of mice to satratoxin G (SG), a macrocyclic trichothecene

produced by the indoor air mold Stachybotrys chartarum, selectively induces

apoptosis in olfactory sensory neurons (OSNs) of the nose and brain. The purpose

of this study was to measure the kinetics of distribution and clearance of SG in

the mouse. Following intranasal instillation of female C57B16 mice with SG (500

& #956;g/kg bw), the toxin was detectable from 5 to 60 min in blood and plasma,

with the highest concentrations, 30 and 19 ng/ml, respectively, being observed

at 5 min. SG clearance from plasma was rapid and followed single-compartment

kinetics (t1/2 = 20 min) and differed markedly from that of other tissues. SG

concentrations were maximal at 15–30 min in nasal turbinates (480 ng/g), kidney

(280 ng/g), lung (250 ng/g), spleen (200 ng/g), liver (140 ng/g), thymus (90

ng/g), heart (70 ng/g), olfactory bulb (14 ng/g), and brain (3 ng/g). The

half-lives of SG in the nasal turbinate and thymus were 7.6 and 10.1 h,

respectively, whereas in other organs, these ranged from 2.3 to 4.4 h. SG was

detectable in feces and urine, but cumulative excretion over 5 days via these

routes accounted for less than 0.3% of the total dose administered. Taken

together, SG was rapidly taken up from the nose, distributed to tissues involved

in respiratory, immune, and neuronal function, and subsequently cleared.

However, a significant amount of the toxin was retained in the nasal turbinate,

which might contribute to SG's capacity to evoke OSN death.

Key words

trichothecenemycotoxinStachybotrysELISAtoxicokinetics

http://toxsci.oxfordjournals.org/content/116/2/433.abstract

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Neurotoxic, Inflammatory, and Mucosecretory Responses in the Nasal Airways of

Mice Repeatedly Exposed to the Macrocyclic Trichothecene Mycotoxin Roridin A

Dose-Response and Persistence of Injury

Kara N. Corps1,2,

Zahidul Islam2,3,

J. Pestka2,3 and

Jack R. Harkema2,4

+ Author Affiliations

1Comparative Medicine and Integrative Biology, Michigan State University, East

Lansing, MI 48824 USA

2Center for Integrative Toxicology, Michigan State University, East Lansing, MI

48824 USA

3Department of Microbiology and Molecular Genetics, Michigan State University,

East Lansing, MI 48824 USA

4Department of Pathobiology and Diagnostic Investigation, Michigan State

University, East Lansing, MI 48824 USA

Dr. Jack R. Harkema, National Food Safety and Toxicology Center, Room 212, Food

Safety and Toxicology Building, Michigan State University, East Lansing, MI

48824, USA; phone: 517-353-8627; fax: 517-353-9902; e-mail: harkemaj@...

Abstract

Macrocyclic trichothecene mycotoxins encountered in water-damaged buildings have

been suggested to contribute to illnesses of the upper respiratory tract. Here,

the authors characterized the adverse effects of repeated exposures to roridin A

(RA), a representative macrocyclic trichothecene, on the nasal airways of mice

and assessed the persistence of these effects. Young, adult, female C57BL/6 mice

were exposed to single daily, intranasal, instillations of RA (0.4, 2, 10, or

50 & #8202; & #956;g/kg body weight [bw]) in saline (50 & #8202; & #956;l) or saline

alone (controls) over 3 weeks or 250 & #8202; & #956;g/kg RA over 2 weeks.

Histopathologic, immunohistochemical, and morphometric analyses of nasal airways

conducted 24 hr after the last instillation revealed that the lowest-effect

level was 10 & #8202; & #956;g/kg bw. RA exposure induced a dose-dependent,

neutrophilic rhinitis with mucus hypersecretion, atrophy and exfoliation of

nasal transitional and respiratory epithelium, olfactory epithelial atrophy and

loss of olfactory sensory neurons (OSNs). In a second study, the persistence of

lesions in mice instilled with 250 & #8202; & #956;g/kg bw RA was assessed. Nasal

inflammation and excess luminal mucus were resolved after 3 weeks, but OSN loss

was still evident in olfactory epithelium (OE). These results suggest that nasal

inflammation, mucus hypersecretion, and olfactory neurotoxicity could be

important adverse health effects associated with short-term, repeated, airborne

exposures to macrocyclic trichothecenes.

macrocyclic trichothecene mycotoxinroridin Anasal toxicityolfactory

neurodegenerationrhinitis

http://tpx.sagepub.com/content/38/3/429.abstract

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DNA Damage and DNA Damage Responses in THP-1 Monocytes after Exposure to Spores

of either Stachybotrys chartarum or Aspergillus versicolor or to T-2 toxin

Kirsten E. Rakkestad*, Ida Skaar†, Vibeke E. Ansteinsson‡¶, Anita Solhaug†, Jørn

A. Holme*, J. Pestka§, Jan T. sen¶, Hans J. Dahlman*, Jan K.

Hongslo* and Rune Becher*,1

+ Author Affiliations

*Department of Air Pollution and Noise, Division of Environmental Medicine,

Norwegian Institute of Public Health, N-0403 Oslo, Norway

†Department of Feed and Food Safety, National Veterinary Institute, N-0106 Oslo,

Norway

‡Department of Clinical Dentistry-Biomaterials, University of Bergen, N-5009

Bergen, Norway

§Department of Microbiology and Molecular Genetics, Michigan State University,

East Lansing, Michigan 48824

¶NIOM—Nordic Institute of Dental Materials, N-1305 Haslum, Norway

1To whom correspondence should be addressed at Department of Air Pollution and

Noise, Division of Environmental Medicine, Norwegian Institute of Public Health,

PO Box 4404, Nydalen, N-0403 Oslo, Norway. E-mail: rune.becher@....

Received October 16, 2009.

Accepted January 31, 2010.

Abstract

We have characterized cell death in THP-1 cells after exposure to heat-treated

spores from satratoxin G–producing Stachybotrys chartarum isolate IBT 9631,

atranone-producing S. chartarum isolate IBT 9634, and sterigmatocystin-producing

Aspergillus versicolor isolate IBT 3781, as well as the trichothecenes T-2 and

satratoxin G. Spores induced cell death within 3–6 h, with Stachybotrys

appearing most potent. IBT 9631 induced both apoptosis and necrosis, while IBT

9634 and IBT 3781 induced mostly necrosis. T-2 toxin and satratoxin G caused

mainly apoptosis. Comet assay ± formamidopyrimidine DNA glycosylase showed that

only the spore exposures induced early (3h) oxidative DNA damage. Likewise, only

the spores increased the formation of reactive oxygen species (ROS), suggesting

that spores as particles may induce ROS formation and oxidative DNA damage.

Increased Ataxia Telangiectasia Mutated (ATM) phosphorylation, indicating DNA

damage, was observed after all exposures. The DNA damage response induced by IBT

9631 as well as satratoxin G was characterized by rapid (15 min) activation of

p38 and H2AX. The p38 inhibitor SB 202190 reduced IBT 9631–induced H2AX

activation. Both IBT 9631 and T-2 induced activation of Chk2 and H2AX after 3 h.

The ATM inhibitor KU 55933, as well as transfection of cells with ATM siRNA,

reduced this activation, suggesting a partial role for ATM as upstream activator

for Chk2 and H2AX. In conclusion, activation of Chk2 and H2AX correlated with

spore- and toxin-induced apoptosis. For IBT 9631 and satratoxin G, additional

factors may be involved in triggering apoptosis, most notably p38 activation.

Key words

moldmycotoxinsDNA damage responseapoptosis

http://toxsci.oxfordjournals.org/content/115/1/140.abstract

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Pulmonary Responses to Stachybotrys chartarum and Its Toxins: Mouse Strain

Affects Clearance and Macrophage Cytotoxicity

H. Rosenblum Lichtenstein*,1, Ramon M. Molina*, C. Donaghey*,

Chidozie J. Amuzie†, J. Pestka†, Brent A. Coull‡ and ph D. Brain*

+ Author Affiliations

*Department of Environmental Health, Program in Molecular and Integrative

Physiological Sciences, Harvard School of Public Health, Boston, Massachusetts

02115

†Department of Microbiology and Molecular Genetics, Comparative Medicine and

Integrative Biology Program, Michigan State University, East Lansing, Michigan

48824

‡Department of Biostatistics, Harvard School of Public Health, Boston,

Massachusetts 02115

1To whom correspondence should be addressed at Department of Environmental

Health, Program in Molecular and Integrative Physiological Sciences, Harvard

School of Public Health, 665 Huntington Avenue, Building 2, Room 219, Boston, MA

02115. Fax: (617) 432-0014. E-mail: jrosenbl@....

Received December 24, 2009.

Accepted March 31, 2010.

Abstract

We investigated differences in the pulmonary and systemic clearance of

Stachybotrys chartarum spores in two strains of mice, BALB/c and C57BL/6J. To

evaluate clearance, mice were intratracheally instilled with a suspension of

radiolabeled S. chartarum spores or with unlabeled spores. The lungs of C57BL/6J

mice showed more rapid spore clearance than the lungs of BALB/c mice, which

correlated with increased levels of spore-associated radioactivity in the GI

tracts of C57BL/6J as compared with BALB/c mice. To identify mechanisms

responsible for mouse strain differences in spore clearance and previously

described lung inflammatory responses, we exposed alveolar macrophages (AMs)

lavaged from BALB/c and C57BL/6J mice to S. chartarum spores, S. chartarum spore

toxin (SST), and satratoxin G (SG) in vitro. The S. chartarum spores were found

to be highly toxic with most cells from either mouse strain being killed within

24 h when exposed to a spore:cell ratio of 1:75. The spores were more lethal to

AMs from C57BL/6J than those from BALB/c mice. In mice, the SST elicited many of

the same inflammatory responses as the spores in vivo, including AM recruitment,

pulmonary hemorrhage, and cytokine production. Our data suggest that differences

in pulmonary spore clearance may contribute to the differences in pulmonary

responses to S. chartarum between BALB/c and C57BL/6J mice. Enhanced AM survival

and subsequent macrophage-mediated inflammation may also contribute to the

higher susceptibility of BALB/c mice to S. chartarum pulmonary effects.

Analogous genetic differences among humans may contribute to reported variable

sensitivity to S. chartarum.

Key words

Stachybotrys chartarumrodenttoxicityacutesafety

evaluationmacrophageimmunotoxicologylungpulmonary or respiratory

systemrespiratory toxicologydose-responserisk assessment

http://toxsci.oxfordjournals.org/content/116/1/113.abstract

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