Iron Oxide Particles Alter Bacterial Uptake and the LPS-Induced Inflammatory Response in Macrophages
Exposure to geogenic (earth-derived) particulate matter (PM) is linked to severe bacterial infections in Australian Aboriginal communities. Experimental studies have shown that the concentration of iron in geogenic PM is associated with the magnitude of respiratory health effects, however, the mecha...
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doaj-cc3832a30aa04e16870983c1479120b52020-12-29T00:01:19ZengMDPI AGInternational Journal of Environmental Research and Public Health1661-78271660-46012021-12-011814614610.3390/ijerph18010146Iron Oxide Particles Alter Bacterial Uptake and the LPS-Induced Inflammatory Response in MacrophagesLewis J. Williams0Stephen G. Tristram1Graeme R. Zosky2Tasmanian School of Medicine, University of Tasmania, Hobart 7000, AustraliaSchool of Health Sciences, University of Tasmania, Launceston 7250, AustraliaTasmanian School of Medicine, University of Tasmania, Hobart 7000, AustraliaExposure to geogenic (earth-derived) particulate matter (PM) is linked to severe bacterial infections in Australian Aboriginal communities. Experimental studies have shown that the concentration of iron in geogenic PM is associated with the magnitude of respiratory health effects, however, the mechanism is unclear. We investigated the effect of silica and iron oxide on the inflammatory response and bacterial phagocytosis in macrophages. THP-1 and peripheral blood mononuclear cell-derived macrophages were exposed to iron oxide (haematite or magnetite) or silica PM with or without exposure to lipopolysaccharide. Cytotoxicity and inflammation were assessed by LDH assay and ELISA respectively. The uptake of non-typeable <i>Haemophilus influenzae</i> by macrophages was quantified by flow cytometry. Iron oxide increased IL-8 production while silica also induced significant production of IL-1β. Both iron oxide and silica enhanced LPS-induced production of TNF-α, IL-1β, IL-6 and IL-8 in THP-1 cells with most of these responses replicated in PBMCs. While silica had no effect on NTHi phagocytosis, iron oxide significantly impaired this response. These data suggest that geogenic particles, particularly iron oxide PM, cause inflammatory cytokine production in macrophages and impair bacterial phagocytosis. These responses do not appear to be linked. This provides a possible mechanism for the link between exposure to these particles and severe bacterial infection.https://www.mdpi.com/1660-4601/18/1/146geogenicparticulate mattermacrophagesinflammatory cytokinesNTHi |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Lewis J. Williams Stephen G. Tristram Graeme R. Zosky |
spellingShingle |
Lewis J. Williams Stephen G. Tristram Graeme R. Zosky Iron Oxide Particles Alter Bacterial Uptake and the LPS-Induced Inflammatory Response in Macrophages International Journal of Environmental Research and Public Health geogenic particulate matter macrophages inflammatory cytokines NTHi |
author_facet |
Lewis J. Williams Stephen G. Tristram Graeme R. Zosky |
author_sort |
Lewis J. Williams |
title |
Iron Oxide Particles Alter Bacterial Uptake and the LPS-Induced Inflammatory Response in Macrophages |
title_short |
Iron Oxide Particles Alter Bacterial Uptake and the LPS-Induced Inflammatory Response in Macrophages |
title_full |
Iron Oxide Particles Alter Bacterial Uptake and the LPS-Induced Inflammatory Response in Macrophages |
title_fullStr |
Iron Oxide Particles Alter Bacterial Uptake and the LPS-Induced Inflammatory Response in Macrophages |
title_full_unstemmed |
Iron Oxide Particles Alter Bacterial Uptake and the LPS-Induced Inflammatory Response in Macrophages |
title_sort |
iron oxide particles alter bacterial uptake and the lps-induced inflammatory response in macrophages |
publisher |
MDPI AG |
series |
International Journal of Environmental Research and Public Health |
issn |
1661-7827 1660-4601 |
publishDate |
2021-12-01 |
description |
Exposure to geogenic (earth-derived) particulate matter (PM) is linked to severe bacterial infections in Australian Aboriginal communities. Experimental studies have shown that the concentration of iron in geogenic PM is associated with the magnitude of respiratory health effects, however, the mechanism is unclear. We investigated the effect of silica and iron oxide on the inflammatory response and bacterial phagocytosis in macrophages. THP-1 and peripheral blood mononuclear cell-derived macrophages were exposed to iron oxide (haematite or magnetite) or silica PM with or without exposure to lipopolysaccharide. Cytotoxicity and inflammation were assessed by LDH assay and ELISA respectively. The uptake of non-typeable <i>Haemophilus influenzae</i> by macrophages was quantified by flow cytometry. Iron oxide increased IL-8 production while silica also induced significant production of IL-1β. Both iron oxide and silica enhanced LPS-induced production of TNF-α, IL-1β, IL-6 and IL-8 in THP-1 cells with most of these responses replicated in PBMCs. While silica had no effect on NTHi phagocytosis, iron oxide significantly impaired this response. These data suggest that geogenic particles, particularly iron oxide PM, cause inflammatory cytokine production in macrophages and impair bacterial phagocytosis. These responses do not appear to be linked. This provides a possible mechanism for the link between exposure to these particles and severe bacterial infection. |
topic |
geogenic particulate matter macrophages inflammatory cytokines NTHi |
url |
https://www.mdpi.com/1660-4601/18/1/146 |
work_keys_str_mv |
AT lewisjwilliams ironoxideparticlesalterbacterialuptakeandthelpsinducedinflammatoryresponseinmacrophages AT stephengtristram ironoxideparticlesalterbacterialuptakeandthelpsinducedinflammatoryresponseinmacrophages AT graemerzosky ironoxideparticlesalterbacterialuptakeandthelpsinducedinflammatoryresponseinmacrophages |
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1724368228718739456 |