脱脂米糠抽出物のヒト由来食細胞に対する免疫賦活性の検討

Abstract

The present report describes the effect of the three kinds of degreasing rice bran extracts (rice bran (Rb), rice bran extract E (RbE), and rice bran heat water extract (RbhS) on the immune response of human cells. Samples of Rb and RbE were processed by fermentation with Enterococcus sp. and Pichia sp. at 37°C for 3 to 5 days, subsequently, RbE samples were treated with hemicellulose enzyme. While RbhS samples were heattreated and used as the control. We studied the effect of inactive Staphylococcus aureus cells coated with the three kinds of rice bran extracts on phagocytosis and phagosome-lysosome fusion by human leukocytes in vitro. Rice bran extracts increased phagocytic activity and phagosome-lysosome fusion in neutrophils and monocytes in a doseresponse manner. The rate of phagocytosis of RbE-coated S. aureus by neutrophils was significantly higher, by approximately 3.6 times, than that of uncoated S. aureus. The rate of phagocytosis of RbE-coated S. aureus by monocytes was about 1.6 times higher than that of the control. The phagosome-lysosome fusion index (FI) for RbE-coated bacteria by neutrophils was higher, by approximately 6 times, than that of the control. The ratio of the FI to the phagocytic index (PI) in human neutrophils showed that 83% of phagocytosed cells were digested the fused phagolysosomes when the S. aureus coated with RbE at a concentration of 25 μg/ml. These results show that RbE has immune-enhancing activity. Although degreasing rice bran is traditionally discarded, if processed with Enterococcus sp., Pichia sp. and hemicellulose enzyme, it becomes consumable and can be used as a health food material to enhance immune activity in humans

3種類の方法で調製した脱脂米糠抽出物について免疫賦活性(貧食活性と食胞融合性)の視点から,未利用資源としての活用可能性を検討した。 (1)ライフペップ(Rb)は乳酸菌・酵母処理(37℃ ・3～5日)。 (2)ライフペップE(RbE)は乳酸菌・酵母処理後 酵素(ヘミセルラーゼ)処理。 (3)熱水抽出物(RbhS)はオートクレープ処理。 何れの処理サンプルも,凍結乾燥後試験に供した。その結果,ヒト好中球に対する貧食活性は,3試料とも,濃度に依存して貧食作用が上昇した。RbEでは5μg/mlプラトーに達し,コントロールに比べ3.6倍(p<0.001)の活性を示した。また,単球に対する貧食活性では,RbEが1.6倍(p<0.001)活性を示した。RbEは,脱脂米糠の熱水抽出物(RbhS)とRbより高い活性を示した。 最も貧食活性の強かったRbEの食胞融合能は,コントロールに対して6倍の食胞融合性を示し,25μg/mlの濃度で貧食された菌のうち約8割が殺菌されることが確認できた。この結果,脱脂米糠を乳酸菌・酵母処理後酵素(ヘミセルラーゼ)処理すると,貧食活性を促進できることがわかり,免疫賦活作用を示す利用資源として役に立つことが明確となった。