[Expression of hepatocyte growth factor by activated eosinophiles in inflammatory lung tissue]

Hepatocyte growth factor (HGF) plays a multifunctional role in the regeneration of alveolar type-II and other epithelial cells. HGF is produced by various kinds of mesenchymal cells, including polymorphonuclear granulocytes. However, it was not evident that eosinophiles produce HGF. In this investigation, we utilized immunohistochemical techniques to show that Eol-1 cells, an eosinophilic leukemia cell line, as well as activated eosinophiles in inflammatory lung tissue, produce HGF. It was also shown that IL-5 induced the production of HGF by peripheral eosinophiles in vitro. These findings suggest that, in inflammatory lung diseases, eosinophiles activated in the presence of IL-5 produce not only tissue-injurious substances (e.g., eosinophilic cationic protein, major basic protein, and peroxidase) but also HGF; and that eosinophiles may play a role in the regeneration of injured lung tissue through the production of HGF.