Studies of host-pathogen interactions and immune-related drug development using the silkworm: interdisciplinary...

Innate immunity acts as a front-line barrier against invading pathogens, and the majority of the components are widely conserved among species. Regulation of innate immunity is important for overcoming infections and preventing self-damaging sepsis. Using the silkworm (Bombyx mori) as an animal model, we elucidated the activation processes of innate immunity with emphasis on a multifunctional insect cytokine called paralytic peptide. Moreover, we established an ex vivo system using silkworm larval specimens to quantitatively evaluate the immunostimulatory activity of natural compounds. We observed that overactivation of innate immunity in silkworms induces tissue damage followed by host death, resembling sepsis-induced multi-organ failure in humans. Here, we summarize our recent findings and propose the usefulness of the silkworm as an animal model for studying immune regulation and for evaluating compounds with the potential to regulate innate immunity.