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Wood smoke particle sequesters cell iron to impact a biological effect.
Citation:
Ghio, Andy, J. Soukup, L. Dailey, H. Tong, M. Kesic, G. Buddinger, AND G. Mutlu. Wood smoke particle sequesters cell iron to impact a biological effect. CHEMICAL RESEARCH IN TOXICOLOGY. American Chemical Society, Washington, DC, 28(11):2104-11, (2015).
Impact/Purpose:
Wood fires are a component of both indoor and outdoor air pollution. The particles generated by the burning of wood (WSP) are inhalable and result in biological effects in the human body. This work is designed to look at the components of WSP to determine the effect on human health as it pertains to iron homeostasis.
Description:
The biological effect of an inorganic particle (i.e., silica) can be associated with a disruption in cell iron homeostasis. Organic compounds included in particles originating from combustion processes can also complex sources of host cell iron to disrupt metal homeostasis. We tested the postulate that (1) wood smoke particle (WSP) sequesters host cell iron resulting in a disruption of metal homeostasis, (2) this loss of essential metal results in both an oxidative stress and biological effect in respiratory epithelial cells, and (3) humic-like substances (HULIS), a component of WSP, have a capacity to appropriate cell iron and initiate a biological effect. BEAS- 2B cells exposed to WSP resulted in diminished concentrations of mitochondrial (57)Fe, whereas preincubation with ferric ammonium citrate (FAC) prevented significant mitochondrial iron loss after such exposure.Cellular oxidant generation was increased after WSP exposure, but this signal was diminished by coincubation with FAC. Similarly, exposure of BEAS-2B cells to 100µg/ml WSP activated mitogen-activated protein (MAP) kinases, elevated NF-E2-related factor 2/antioxidant responsive element (Nrf2 ARE) expression, and provoked interleukin (IL)-6 and IL-8 release, but all these changes were diminished by coincubation with FAC. The biological response to WSP was reproduced by exposure to 100 µg/ml humic acid, a polyphenol comparable to HULIS included in the WSP that complexes iron. We conclude that (1) the biological response following exposure to WSP is associated with sequestration of cell iron by the particle, (2) increasing available iron in the cell diminished the biological effects after particle exposure, and (3) HULIS included in WSP can sequester the metal initiating the cell response.
