Effect of vitamin E on production of macrophage migration inhibitory factor (MIF) by macrophages

Article type: Research Article

Authors: Sakamoto, Wataru^; | Nishihira, Jun | Fujie, Katsutoshi | Iizuka, Tadashi | Handa, Hiroshi | Ozaki, Mitsuru | Yukawa, Susumu

Affiliations: Department of Biochemistry, School of Dentistry, Hokkaido University, Sapporo 060, Japan | Central Research Institute, School of Medicine, Hokkaido University, Sapporo 060, Japan | Department of Oral Pathology, School of Dentistry, Hokkaido University, Sapporo 060, Japan | Internal Medicine, Tonan Hospital, Sapporo 060, Japan | 3rd Internal Medicine, Wakayama Medical College, Wakayama 640, Japan

Note: [] Correspondence: Dr Wataru Sakamoto, Department of Biochemistry, School of Dentistry, Hokkaido University, Sapporo 060, Japan. Tel./Fax: +81 11 706 4232; E‐mail: 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 \pm 90.7 ng/10^{6} cells, whereas in control rats it was 1.5 \pm 0.5 ng/10^{6} cells. For the control macrophages, total MIF content of the medium (2.5 \times 10^{6} cells/18 ml) without stimulation was 40.7 \pm 3.6 ng after 14 h culture, whereas stimulation with calcium ionophore A23187 (400 nM) and LPS (5.0 \mug/ml) induced the elevation of MIF content to 65.9 \pm 7.5 ng and 74.3 \pm 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 \pm 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.

Keywords: Vitamin E, macrophages, macrophage migration inhibitory factor (MIF), lipopolysaccharide (LPS), calcium ionophore A23187

Journal: Biofactors, vol. 10, no. 2-3, pp. 139-143, 1999