Cytotoxic and proinflammatory response of RAW 264.7 cells to differentially fractionated fungal fragments

Abstract

Although significant research has been carried out for studying the impacts of pure mycotoxins on human cell, little information is known about the direct effects of fungal submicron particles. In this report, murine macrophage RAW 264.7 cells were exposed to fungal extracts from Stachybotrys chartarum RTI 5802 and Aspergillus versicolor RTI 3843 as well as mixtures from both fungi with fragment sizes ranging from 0.25 to 1 µm. Cell viability was found to be unaffected by all extracts except fragments in the 0.5–1 µm size range from A. versicolor RTI 3843, which decreased cell viability by approximately 60%. IL-1β expression was generally upregulated following exposure to fungal extracts from either S. chartarum RTI 5802 or A. versicolor RTI 3843. However, when extracts from the mixture of both fungi were introduced, IL-1β expression was downregulated. IL-6 and IL-10 expression were also generally upregulated. In comparison to the findings in the literature about the effects of pure mycotoxins on RAW 264.7 cells, the results presented herein show different patterns on mRNA expression which may be a result of the complex composition of the extract in terms of both mycotoxins and other fungal materials in addition to the potential interplay of the different components.

Keywords:

• mycotoxin
• cytokine
• RAW 264.7
• Stachybotrys chartarum
• Aspergillus versicolor

Acknowledgements

The project described was supported by grant number P30-ES011961 from the National Institute of Environmental Health Sciences. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIEHS, NIH. S. chartarum and A. versicolor strains were a generous gift from Doris Betancourt and Timothy Dean at the EPA in the Research Triangle Park, NC.