ToxSci Advance Access originally published online on November 7, 2006
Toxicological Sciences 2007 95(2):412-426; doi:10.1093/toxsci/kfl153
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Deoxynivalenol Exacerbates Viral Bronchopneumonia Induced by Respiratory Reovirus Infection
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* Department of Microbiology and Molecular Genetics
Food Science and Human Nutrition
Center for Integrative Toxicology
Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, Michigan 48824
¶ Department of Microbiology, Immunology, and Cell Biology, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia 26506
1 To whom correspondence should be addressed at 234 G. M. Trout Building, Michigan State University, East Lansing, MI 48824-1224. Fax: (517) 353-8963. E-mail: pestka{at}msu.edu.
Received August 28, 2006; accepted November 1, 2006
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Abstract |
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The trichothecene mycotoxin deoxynivalenol (DON), a frequent contaminant of cereal grains, is known to dysregulate mucosal and systemic immunity. In this study, we tested the hypothesis that DON interferes with the murine immune response to viral respiratory infection. Female Balb/c mice (5 weeks old) were orally gavaged with DON (10 mg/kg body weight [bw]) or saline vehicle and then intranasally instilled with 107 plaque-forming units of reovirus serotype 1, strain Lang (T1/L). At 10-day postinstillation (PI), both viral titers and reovirus L2 gene expression were 10-fold higher in lungs of DON-treated mice than in saline controls. The lowest observed effective DON dose that impaired viral clearance was 2 mg/kg bw. Although DON amplified reovirus-induced interferon (IFN)-ß and IFN-
mRNA responses in lung, the toxin suppressed mRNA expression for IFN-
, IFN-ß receptor (IFNAR), and IFN- receptor (IFNGR). DON also impaired induction of two type 1 IFN-dependent antiviral genes, double-stranded RNA activated protein kinase R (PKR) and oligoadenylate synthase 2 (OAS2). Respiratory reovirus infection caused a mild bronchopneumonia in mice which was markedly exacerbated by DON as evidenced by severe inflammatory cell infiltration, marked alveolar damage, and a higher volume density of intraepithelial mucosubstances in pulmonary airways. At 3- and 7-day PI, elevations in total protein, MCP-1, TNF-, total cells, macrophages, neutrophils, and lymphocytes were observed in bronchoalveolar lavage fluid (BALF) of control mice infected with reovirus. DON markedly enhanced viral-induced elevations of protein, MCP-1, TNF-, and inflammatory cells in the BALF at 3-day PI. DON exposure also upregulated induction of reovirus-specific immunoglobulin A (IgA) in BALF, fecal pellets, and serum. DON's effect on BALF IgA was preceded by elevated IL-6 expression and secretion in the lung. Taken together, the results suggest that DON compromised resistance to respiratory viral infection. Reduced expression of IFNAR and type 1 IFN-mediated genes in the lung might contribute to DON impairment of pulmonary reovirus clearance, whereas exacerbation of bronchopneumonia and IgA responses corresponded to increased MCP-1, TNF-, and IL-6 expression.
Key Words: deoxynivalenol; reovirus; respiratory infection; histopathology; cytokines; flow cytometry bead array; host resistance.