Comparison of Inflammatory Responses in Mouse Lungs Exposed to Atranones A And C from Stachybotrys Chartarum

Abstract

Stachybotrys chartarum isolates can be separated into two distinct chemotypes based on the toxins they produce. One chemotype produces macrocyclic trichothecenes; the other produces atranones (and sometimes simple trichothecenes, e.g., trichodermol and trichodermin). Studies using in vivo models of lung disease revealed that exposure to spores of the atranone producing S. chartarum isolates led to a variety of immunotoxic, inflammatory, and other pathological changes. However, it is unclear from these studies what role the pure atranone toxins sequestered in spores of these isolates exert on lung disease onset. This study examined dose-response (0.2, 1.0, 2.0, 5.0, or 20 μg atranone/animal) and time-course (3, 6, 24, and 48 h postinstillation [PI]) relationships associated with inflammatory cell and proinflammatory chemokine/cytokine responses in mouse lungs intratracheally instilled with two pure atranones (either A or C) isolated from S. chartarum. High doses (2.0 to 20 μg toxin/animal) of atranone A and C induced significant inflammatory responses manifested as differentially elevated macrophage, neutrophil, macrophage inflammatory protein (MIP)-2, tumor necrosis factor (TNF) and interleukin (IL)-6 concentrations in the bronchioalveolar lavage fluid (BALF) of intratracheally exposed mice. Compared to controls, BALF macrophage and neutrophil numbers were increased to significant levels from 6 to 48 h (PI). Except for macrophage numbers in atranone A treatment animals, cells exhibited significant dose dependent-like responses. The chemokine/cytokine marker responses were significantly and dose-dependently increased from 3 to 24 h PI and declined to nonsignificant levels at 48 h PI. The results suggest not only that atranones are inflammatory but also that they exhibit different inflammatory potency with different toxicokinetics. Data also suggest that exposure to these toxins in spores of S. chartarum in contaminated building environments could contribute to inflammatory lung disease onset in susceptible individuals.

This work was supported by NSERC operating grants to T. G. Rand and an NSERC IRC to J. D. Miller. The authors thank Shauna Giles for excellent technical assistance.

Additional information

Notes on contributors

Thomas G. Rand

Present address for Taiwo O. Womiloju is Division of Nephrology, Children's Hospital of Eastern Ontario, 401 Smyth Road, Ottawa, Ontario, Canada K1H 8L1.