Kati Huttunen, Anne Hyvärinen, Aino Nevalainen, Hannu Komulainen, and Maija-Riitta Hirvonen
Department of Environmental Health, National Public Health Institute, Kuopio, Finland

Abstract

We compared the inflammatory and cytotoxic responses caused by household mold and bacteria in human and mouse cell lines. We studied the fungi Aspergillus versicolor, Penicillium spinulosum, and Stachybotrys chartarum and the bacteria Bacillus cereus, Pseudomonas fluorescens, and Streptomyces californicus for their cytotoxicity and ability to stimulate the production of inflammatory mediators in mouse RAW264.7 and human 28SC macrophage cell lines and in the human A549 lung epithelial cell line in 24-hr exposure to 10⁵, 10⁶, and 10⁷ microbes/mL. We studied time dependency by terminating the exposure to 10⁶ microbes/mL after 3, 6, 12, 24, and 48 hr. We analyzed production of the cytokines tumor necrosis factor- and interleukins 6 and 1ß (TNF- , IL-6, IL-1ß, respectively) and measured nitric oxide production using the Griess method, expression of inducible NO-synthase with Western Blot analysis, and cytotoxicity with the MTT-test. All bacteria strongly induced the production of TNF- , IL-6 and, to a lesser extent, the formation of IL-1ß in mouse macrophages. Only the spores of Str. californicus induced the production of NO and IL-6 in both human and mouse cells. In contrast, exposure to fungal strains did not markedly increase the production of NO or any cytokine in the studied cell lines except for Sta. chartarum, which increased IL-6 production somewhat in human lung epithelial cells. These microbes were less cytotoxic to human cells than to mouse cells. On the basis of equivalent numbers of bacteria and spores of fungi added to cell cultures, the overall potency to stimulate the production of proinflammatory mediators decreased in the order Ps. fluorescens > Str. californicus > B. cereus > Sta. chartarum > A. versicolor > P. spinulosum. These data suggest that bacteria in water-damaged buildings should also be considered as causative agents of adverse inflammatory effects. Key words: bacteria, cytokine production, fungi, inflammation, mold. Environ Health Perspect 111:85-92 (2003). [Online 4 December 2002]

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