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Investigation of Macrophage Polarization Using Bone Marrow Derived Macrophages
Published on: June 23, 2013
Fifty-hertz magnetic fields induce free radical formation in mouse bone marrow-derived promonocytes and macrophages
Jana Rollwitz1, Madeleine Lupke, Myrtill Simkó
1Division of Environmental Physiology, Institute for Cell Biology and Biosystems Technology, University of Rostock, Albert-Einstein-Strasse 3, D-18057 Rostock, Germany.
Abstract:
Our findings show a significant increase of free radical production after exposure to 50 Hz electromagnetic fields at a flux density of 1 mT to mouse bone marrow-derived (MBM) promonocytes and macrophages, indicating the cell-activating capacity of extremely low frequency magnetic fields (ELF-MF). We demonstrate that after exposure to ELF-MF mainly superoxide anion radicals were produced, both in MBM macrophages (33%) and also in their precursor cells (24%). To elucidate whether NADPH- or NADH-oxidase functions are target proteins for MF interaction, the flavoprotein inhibitor diphenyleneiodonium chloride (DPI) was used. MF-induced free radical production was not inhibited by DPI, whereas tetradecanoylphorbolacetate (TPA)-induced free radical production was diminished by about 70%. TPA is known to induce a direct activation of NADPH-oxidase through the PKC pathway. Since DPI lacks an inhibitory effect in MF-exposed MBM cells, we suggest that 50 Hz MF stimulates the NADH-oxidase pathway to produce superoxide anion radicals, but not the NADPH pathway. Furthermore, we showed an oscillation (1-10 days) in superoxide anion radical release in mouse macrophages, indicating a cyclic pattern of NADH-oxidase activity.
Insights
Exposure to 50 Hz electromagnetic fields (EMF) significantly increases free radical production in mouse immune cells. This suggests EMF activates cells via the NADH-oxidase pathway, not NADPH-oxidase, with a cyclic release pattern observed.
Area of Science:
- Biophysics
- Cell Biology
- Immunology
Background:
- Extremely low frequency magnetic fields (ELF-MF) are pervasive, and their biological effects require elucidation.
- Cellular responses to ELF-MF, particularly free radical production, are not fully understood.
- Identifying the specific enzymatic pathways involved in ELF-MF-induced cellular responses is crucial.
Purpose of the Study:
- To investigate the effect of 50 Hz electromagnetic fields (EMF) on free radical production in mouse bone marrow-derived (MBM) promonocytes and macrophages.
- To determine whether NADPH-oxidase or NADH-oxidase pathways are involved in EMF-induced free radical generation.
- To characterize the temporal pattern of free radical release following EMF exposure.
Main Methods:
- Exposure of MBM promonocytes and macrophages to 50 Hz EMF at 1 mT flux density.
- Measurement of free radical production, specifically superoxide anion radicals.
- Utilizing diphenyleneiodonium chloride (DPI), a flavoprotein inhibitor, to differentiate between NADPH- and NADH-oxidase activity.
- Comparison with tetradecanoylphorbolacetate (TPA)-induced radical production.
Main Results:
- Significant increase in free radical production observed in MBM cells exposed to 50 Hz EMF.
- Superoxide anion radicals were the primary free radicals produced (33% in macrophages, 24% in promonocytes).
- EMF-induced radical production was not inhibited by DPI, unlike TPA-induced production (70% inhibition).
- An oscillating pattern (1-10 days) in superoxide anion radical release was detected in macrophages.
Conclusions:
- 50 Hz EMF exposure at 1 mT stimulates free radical production in mouse immune cells, indicating cell activation.
- The findings suggest that EMF primarily activates the NADH-oxidase pathway, not the NADPH-oxidase pathway, for superoxide anion radical generation.
- The observed cyclic pattern of radical release points to a potential rhythmic activity of NADH-oxidase in macrophages.
