Abstract
Background: Brown rice (BR) has various beneficial effects. Recently, functional ingredient derived from processed BR (Kinmemai rice extract [KR-ex.]) has been developed in Japan, which reportedly decreases subjects’ “susceptibility to catching colds.” However, the effects of KR-ex. on the immune system remain unclear.
Objective: This study aimed to examine the immunostimulant effects of KR-ex., focusing on the expression of activation markers and intracellular energy metabolic activity using human monocyte (U937)-derived macrophage cells.
Methods: Cell activity was assessed using the gene expression of interleukin-1β and cyclooxygenase-2 as activation markers. The energy metabolic activity in mitochondria was evaluated using the expression of uncoupling protein 2 and the oxygen consumption rate, whereas that in glycolysis was evaluated using the expression of glucose transporter 1 and the amount of lactate released.
Results: The results showed that the KR-ex. group had significantly higher expression of activation markers than the control group. Moreover, the KR-ex. group showed decreased mitochondrial metabolic activity and increased glycolytic metabolic activity compared to the control group.
Conclusions: These results suggest that KR-ex. activates human macrophages and promotes the shifting of the intracellular energy metabolism from the mitochondria to glycolysis.
Keywords: Brown rice; Functional ingredient; Immunostimulant effect; Macrophage; Intracellular energy metabolism; Mitochondria; Glycolysis