Interactions between Streptomyces californicus and Stachybotrys chartarum can induce apoptosis and cell cycle arrest in mouse RAW264.7 macrophages
 
 
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Toxicology and Applied Pharmacology
Volume 202, Issue 3 , 1 February 2005, Pages 278-288

doi:10.1016/j.taap.2004.07.002
Copyright 2004 Elsevier Inc. All rights reserved.
Interactions between Streptomyces californicus and Stachybotrys chartarum can induce apoptosis and cell cycle arrest in mouse RAW264.7 macrophages

Piia Penttinena, , , Jukka Pelkonenb, c, Kati Huttunena, Mika Toivolaa and Maija-Riitta Hirvonena

aDepartment of Environmental Health, National Public Health Institute, FIN-70701 Kuopio, Finland
bDepartment of Clinical Microbiology, University of Kuopio, Kuopio, Finland
cDepartment of Clinical Microbiology, Kuopio University Hospital, Kuopio, Finland

Received 27 February 2004; accepted 8 July 2004. Available online 11 September 2004.

Abstract
Exposure to complex mixtures of bacteria and fungi in moisture-damaged buildings is a potential cause of inflammatory related symptoms among occupants. The present study assessed interactions between two characteristic moldy house microbes Streptomyces californicus and Stachybotrys chartarum. Differences in cytotoxic and inflammatory responses in mouse (RAW264.7) macrophages were studied after exposure to the spores of co-cultivated microbes, the mixture of separately cultivated spores, and the spores of either of these microbes cultivated alone. The RAW264.7 cells were exposed to six doses (1 104 to 3 106 spores/ml) for 24 h, and the time course of the induced responses was evaluated after 4, 8, 16, and 24 h of exposure (1 106 spores/ml). The cytotoxic potential of the spores was characterized by the MTT test, DNA content analysis, and enzyme assay for caspase-3 activity. The production of cytokines (IL-1β, IL-6, IL-10, TNFα, and MIP2) was measured immunochemically and nitric oxide by the Griess method. Co-cultivation increased the ability of the spores to cause apoptosis by more than 4-fold and the proportion of RAW264.7 cells at the G2/M stage increased nearly 2-fold when compared to the response induced by the mixture of spores. In contrast, co-cultivation decreased significantly the ability of the spores to trigger the production of NO and IL-6 in RAW264.7 cells. In conclusion, these data suggest that co-culture of S. californicus and S. chartarum can result in microbial interactions that significantly potentiate the ability of the spores to cause apoptosis and cell cycle arrest in mammalian cells.

Keywords: Apoptosis; Cell cycle arrest; Interaction; Co-cultivation; RAW264.7; Streptomyces californicus; Stachybotrys chartarum

Subject-index terms: Streptomyces californicus; Stachybotrys chartarum; Moisture damaged building; Co-cultivation; Interaction; Mouse macrophage; RAW264.7; In vitro; Cytotoxicity; Apoptosis; Caspase-3; Cell cycle arrest; Inflammatory mediator; Nitric oxide; Cytokine; Flow cytometry



Corresponding author. Department of Environmental Health, National Public Health Institute, PO Box 95, FIN-70701 Kuopio, Finland. Fax: +358 17 201265.