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Biological Responses of Raw 264.7 Macrophage Exposed to Two Strains of Stachybotrys chartarum Spores Grown on Four Different Wallboard Types
Kim, J., L. Harvey, A. Evans, G. Byfield, D. Betancourt, AND T. Dean. Biological Responses of Raw 264.7 Macrophage Exposed to Two Strains of Stachybotrys chartarum Spores Grown on Four Different Wallboard Types. INHALATION TOXICOLOGY. Taylor & Francis, Inc., Philadelphia, PA, 28(7):303-312, (2016).
The many benefits of building “green” have been the motivation for the use of “green” or sustainable products in the design and execution of the built environment. However, the use of these natural or recycled materials, some of which are resistant to microbes, provide an opportunity for the growth of microorganisms with the potential to elicit increased adverse health effects in the presence of an antimicrobial. This study provided a comprehensive understanding of the biological effects elicited by two environmental strains of Stachybotrys chartarum grown on four water damaged wallboard types. The responses induced by the macrophage cell line were variable showing cytotoxicity, apoptosis, and inflammation depending on the fungal strain, the type of wallboard, and the state of the spores used for exposure. Collectively, the data demonstrated that all of the wallboard types elicited harmful biological responses with the potential to negatively impact human health.
The focus of this research was to provide a better understanding of the health impacts caused by Stachybotrys chartarum (Houston and 51-11) spores grown on four gypsum products two of which were resistant to microbes. Raw 264.7 cells were exposed to whole spores and fragmented 51-11 spores, and assessed for specific biological responses. Houston whole spores showed no cytotoxicity with some level of inflammation, while 51-11 whole spores elicited variable responses dependent upon the wallboard type. High concentrations of fragmented 51-11 spores resulted in macrophage cell death primarily through apoptosis with no inflammation. None of the fungal spores resulted in elevated major histocompatibility complex (MHC) class II expression on the surface of the Raw cells. Mycotoxin levels measured from 51-11 spores showed moderately high concentrations for three of the wallboard types and extremely high concentrations for one. Overall, both fungal strains elicited harmful biological responses regardless of the wallboard type.