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Effect of vitamin E on production of macrophage migration inhibitory factor (MIF) by macrophages
W Sakamoto1, J Nishihira, K Fujie
1Department of Biochemistry, School of Dentistry, Hokkaido University, Sapporo, Japan. sakamoto@den.hokudai.ac.jp
Abstract:
Macrophage migration inhibitory factor (MIF), a putative cytokine involved in inflammatory and immune responses, was identified in rat peritoneal macrophages by Western blot analysis and its secretion into culture medium by enzyme-linked immunosorbent assay. To clarify the possibility of vitamin E as an immune modulator, we investigated the effect of vitamin E on MIF production in macrophages in response to calcium ionophore A23187 and lipopolysaccharide (LPS). Intraperitoneal injections of vitamin E (5 mg per rat) for 6 successive days resulted in a significant increase of alpha-tocopherol content in peritoneal macrophages. Alpha-tocopherol content of macrophages in vitamin E-treated rats was 478.3 +/- 90.7 ng/10(6) cells, whereas in control rats it was 1.5 +/- 0.5 ng/10(6) cells. For the control macrophages, total MIF content of the medium (2.5 x 10(6) cells/18 ml) without stimulation was 40.7 +/- 3.6 ng after 14 h culture, whereas stimulation with calcium ionophore A23187 (400 nM) and LPS (5.0 microg/ml) induced the elevation of MIF content to 65.9 +/- 7.5 ng and 74.3 +/- 10.4 ng, respectively (p < 0.05, n = 3). On the other hand, vitamin E-enriched macrophages without stimulation showed less MIF content (14.0 +/- 4.2 ng) than the control (p < 0.05, n = 3). Similarly, the increase of MIF of vitamin E-treated macrophages was significantly suppressed after stimulation with calcium ionophore A23187 or LPS, compared with the control macrophages (p < 0.01, n = 3). From analysis of intracellular MIF content by Western blot, we found no alteration of intracellular MIF content of vitamin E-macrophages, in contrast to the decreased content of control stimulated-macrophages, showing that vitamin E suppressed MIF secretion into the culture medium. Taken together, these results indicate that vitamin E may contribute to the regulation of inflammatory and immune responses through regulation of MIF secretion, possibly by modulating macrophage-membrane architecture.
Insights
Vitamin E significantly increases macrophage alpha-tocopherol content and suppresses the secretion of macrophage migration inhibitory factor (MIF). This suggests vitamin E modulates immune responses by regulating MIF secretion.
Area of Science:
- Immunology
- Cell Biology
- Nutritional Science
Background:
- Macrophage migration inhibitory factor (MIF) is a key cytokine in inflammatory and immune responses.
- Vitamin E is a potent antioxidant with potential immunomodulatory properties.
Purpose of the Study:
- To investigate the effect of vitamin E on MIF production and secretion in rat macrophages.
- To determine if vitamin E can modulate immune responses through MIF regulation.
Main Methods:
- Peritoneal macrophages were isolated from rats and treated with vitamin E.
- Macrophage MIF content and secretion were analyzed using Western blot and ELISA.
- Cells were stimulated with calcium ionophore A23187 and lipopolysaccharide (LPS).
Main Results:
- Vitamin E treatment significantly increased alpha-tocopherol content in macrophages.
- Vitamin E-enriched macrophages showed reduced basal MIF secretion.
- Vitamin E suppressed the A23187- and LPS-induced increase in MIF secretion.
- Intracellular MIF levels remained unchanged, indicating suppressed secretion, not production.
Conclusions:
- Vitamin E acts as an immune modulator by suppressing MIF secretion from macrophages.
- This modulation of MIF secretion may contribute to the regulation of inflammatory and immune responses.
- Vitamin E might influence macrophage-membrane architecture to affect MIF secretion.