Orally administered rutin inhibits the gene expression of Th2 cytokines in the gut and lung in aged mice

Rutin is one of the flavonoids derived from plants such as buckwheat and is well known as a powerful antioxidant. To determine whether dietary rutin could modulate mucosal immunity, we examined the gene expression of Th1/Th2 cytokines and the receptors in the gut and lung. Aged (18 months old, 18 M) C3H/HeN female mice were orally administered rutin for 10 days. The small intestine and lung were taken and analyzed by real-time PCR for gene expression. Interleukin (IL)-13 and IL-13Rα2 gene expression was significantly low (P<0.05 respectively) in the small intestine of aged rutin-fed mice. Meanwhile, there was no change in interferon γ gene expression between control and rutin-fed mice. IL-13 gene expression was also downregulated in the lung. To examine the mechanism of the inhibitory effect of rutin on Th2 cytokines in aged mice, intestinal nitric oxide synthase (NOS) expression was evaluated. Rutin inhibited inducible NOS (NOS2) gene expression, but not neuronal NOS and endothelial NOS. Gene analysis of cells collected from the small intestine by laser capture dissection revealed that NOS2 expression was significantly inhibited in crypt regions. Thus, rutin might be effective against a Th2-dominant profile through NOS2 inhibition in aged mice.