Recently, novel Th2 cytokine-producing cells, type 2 innate lymphoid cells (ILC2s) were identified and analyzed as an important cells for various inflammatory diseases. In this study, we examined a role of ILC2s in liver inflammation and fibrosis with IL-5 reporter mice that we newly generated. We found that IL-5 production from ILC2s and eosinophil activation are not necessary for the development of liver inflammation and the following fibrosis. We also found that ILC2s were activated by intraperinoteal administration of oil (e.g. mineral oil and olive oil), and this activation was mediated by peritoneal cells, especially macrophages and cytokine IL-33 and/or TSLP.
