title: Streptomyces spores from mouldy houses induce nitric oxide, TNFα and IL-6 secretion from RAW264.7 macrophage cell line without causing subsequent cell death.
abstract: The current view is that only bacterial lipopolysaccharide (LPS) and gamma interferon (IFNγ) are able to alone activate macrophages to secrete nitric oxide (NO), probably a causative agent of cell death. Moreover, some cytokines and gram positive pathogens together with IFNγ induce NO-production. Surprisingly, spores of Streptomyces sp., which are mesophilic gram-positive bacteria found in mouldy houses, stimulated RAW264.7 macrophages to produce pro-inflammatory cytokines, tumor necrosis factor alpha (TNFα) and interleukin-6 (IL-6), and induced the expression of inducible NO-synthase (iNOS) with a subsequent NO-production. However, the Streptomyces spores did not kill NO-producing macrophages, as did both LPS and gram negative bacteria Pseudomonas fluorescens, strong inducers of cytokine- and NO-production. These results imply that Streptomyces sp., induced cytokine and NO-secretion, may play a role in the responses evoked by exposure to these microbes. Moreover, factors other than, or in addition to NO, are necessary for cytotoxicity in murine macrophages.
authors.affiliation: Division of Environmental Health, National Public Health Institute, P.O. Box 95, FIN-70701 Kuopio, Finland.
authors.forename: M R
authors.initials: MR
authors.lastname: Hirvonen
authors.forename: A
authors.initials: A
authors.lastname: Nevalainen
authors.forename: N
authors.initials: N
authors.lastname: Makkonen
authors.forename: J
authors.initials: J
authors.lastname: Mönkkönen
authors.forename: K
authors.initials: K
authors.lastname: Savolainen