THE ROLE OF IL-5 IN BLEOMYCIN-INDUCED PULMONARY FIBROSIS

Eosinophils are known to express cytokines capable of promoting fibros is, Interleukin-5 (IL-5) is important in regulating eosinophilopoiesis , eosinophil recruitment and activation, Lung IL-5 expression is eleva ted in pulmonary fibrosis, wherein the eosinophil is a primary source of fibrogenic cytokines. To determine the role of IL-5 in pulmonary fi brosis, the effects of anti-IL-5 antibody were investigated in a model of bleomycin-induced pulmonary fibrosis, Fibrosis was induced in mice by endotracheal bleomycin treatment. Animals were also treated with e ither anti-IL-5 antibody or control IgG, Lungs were then analyzed for fibrosis, eosinophil influx, chemotactic activity, and cytokine expres sion, The results show that a primary chemotactic activity at the heig ht of eosinophil recruitment is IL-5, Furthermore, anti-IL-5 antibody caused significant reduction in lung eosinophilia, cytokine expression , and fibrosis, These findings taken together suggest an important rol e for IL-5 in pulmonary fibrosis via its ability to regulate eosinophi lic inflammation, and thus eosinophil-dependent fibrogenic cytokine pr oduction.