Cytotoxicity, production of reactive oxygen species and cytokines induced by different strains of Stachybotrys sp. from moldy buildings in RAW264.7 macrophages

The ability of different strains of the fungus Stachybotrys, isolated from mold problem buildings, to induce cytotoxicity and production of important inflammatory mediators, i.e. nitric oxide (NO), reactive oxygen species (ROS), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in RAW264.7 macrophages were studied. Several strains of Stachybotrys sp. stimulated immediate increase in the ROS production and in 24-h exposure caused TNF-α and IL-6 release from these cells. However, none of the strains of Stachybotrys sp. was able to induce the expression of inducible nitric oxide synthase (iNOS) and subsequent production of NO in RAW264.7 cells. Moreover, there were significant differences in their ability to induce cytotoxicity in the macrophages. These results suggest that, in addition to direct cytotoxic effects of most Stachybotrys sp., some strains of Stachybotrys sp. stimulate production of inflammatory mediators, TNF-α and IL-6 which were associated with low cytotoxicity in RAW264.7 macrophages.