Immune-enhancing effects of gamma-irradiated sericin.

Gamma radiation changes the molecular structure and activity of proteins, which in turn changes their physiological effects. Sericin, one of the silk peptides, has beneficial effects to humans such as inducing apoptosis, acting as an anti-oxidant. The effects of gamma irradiation on the physiological activity of fibroin have been studied, but its effects on sericin alone have not yet been established. In this study, we assessed the effects of gamma irradiation on sericin (I-sericin) in regard to its inflammatory effects in vitro and in vivo. Our results showed that I-sericin (5 kGy) significantly increased nitric oxide production, proliferation of immune cells, and effectively attenuated lipopolysaccharide (LPS)-induced inflammation. The mice were fed I-sericin for 4 weeks and treated with LPS; they exhibited significantly increased proliferation of lymphocytes, activation of NK cells and decreased secretion of inflammatory cytokines These results suggest gamma-irradiated I-sericin as a valuable functional food supplement by immune-enhancing and anti-inflammation effects.