Streptomyces anulatus from indoor air of moldy houses induce NO and IL-6 production in a human alveolar epithelial cell-line.

Moisture associated microbial growth in buildings may cause respiratory symptoms such as pulmonary inflammation. We studied the effects of spores of Streptomyces anulatus, commonly found in moldy buildings, on the production of nitric oxide (NO), interleukin-6 (IL-6), interleukin-5 (IL-5), interleukin-4 (IL-4), and tumour necrosis factor alpha (TNFα), as well as cell viability in human alveolar II type epithelial cell line (A549). Cells were exposed in vitro to S. anulatus spores with and without interferon-γ (IFNγ) in vitro. Lipopolysaccharide (LPS) was used as a reference substance. S. anulatus alone, and in combination with IFNγ induced NO and IL-6 production and decreased cell viability whereas IL-4, IL-5 or TNFα production were not affected. IFNγ alone had a weaker but otherwise similar effect as S. anulatus on NO and IL-6 production and it potentiated the effects of S. anulatus. LPS did not induce NO or cytokine production, or affect cell viability in A549 cells. These data indicate that spores of S. anulatus induce the excretion of inflammatory mediators in respiratory epithelial cells, which may partly explain the adverse respiratory health effects experienced by individuals exposed to the indoor air of moldy houses.