Modulation of lipopolysaccharide-induced proinflammatory cytokine production by satratoxins and other macrocyclic trichothecenes in the murine macrophage

Abstract

The satratoxins and other macrocyclic trichothecene mycotoxins are produced by Stachybotrys, a mold that is often found in water-damaged dwellings and office buildings. To test the potential immunomodulatory effects of these mycotoxins, RAW 264.7 murine macrophage cells were treated with various concentrations of satratoxin G (SG), isosatratoxin F (iSF), satratoxin H (SH), roridin A (RA), and verrucarin A (VA) for 48 h in the presence or absence of suboptimal concentra-tion of lipopolysaccharide (LPS, 50 ng/ml), and tumor necrosis factor-alpha (TNF-alpha ) and interleukin-6 (IL-6) production were assayed by enzyme-linked immunosorbent assay (ELISA). In LPS-stimulated cultures, TNF-alpha supernatant concentrations were significantly increased in the presence of 2.5, 2.5, and 1 ng/ml of SG, SH, and RA, respectively, whereas IL-6 concentrations were not affected by the same concentrations these macrocyclic trichothecenes. When cells that were treated with LPS and SG (2.5 ng/ml) were evaluated by real-time polymerase chain reaction (PCR),TNF-alpha mRNA was found to increase at 24, 36, and 48 h compared to control cells. At higher concentrations, cytokine production and cell viability were markedly impaired in LPS-stimulated cells. Without LPS stimulation, neither TNF-alpha, nor IL-6 was induced. These results indicate that low concentrations of macrocyclic trichothecenes superinduce expression of TNF-alpha, whereas higher concentrations of these toxins are cytotoxic and concurrently reduce cytokine production. The capacity of satratoxins and other macrocyclic trichothecenes to alter cytokine production may play an etiologic role in outbreaks of Stachybotrys-associated human illnesses.

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