THE ROLE OF EOSINOPHILS IN PULMONARY FIBROSIS (REVIEW)

Pulmonary fibrosis is commonly characterized by inflammation of the al veolar wall, leading to derangement of normal alveolar architecture, a nd interstitial as well as intraalveolar fibrosis. The process involve s cellular interactions via a complex cytokine network and heightened collagen gene expression with abnormal deposition in the lung. Recent studies have identified a myriad of cytokines with potential roles in pulmonary fibrosis. Based on in vivo antibody neutralization studies, important roles for tumor necrosis alpha (TNF alpha), macrophage infla mmatory protein 1 alpha (MIP-1 alpha) and transforming growth factor b eta (TGF beta), have been established. The recent demonstration that t he eosinophil is a major source for several of these key pro-fibrogeni c cytokines during the early stages of fibrosis, strongly suggest a ro le for the eosinophil in pulmonary fibrosis. In vitro, eosinophils can elaborate factors capable of stimulating fibroblast proliferation, an d their presence in lungs undergoing many forms of pulmonary fibrosis has been well documented. Further support for a role for eosinophils i n pulmonary fibrosis are suggested by clinical data showing a correlat ion between lung eosinophil count and a poor prognosis and decreased r esponsiveness to therapy. This review will focus on the recent finding s, which suggest novel potential roles for the eosinophil in the patho genesis of pulmonary fibrosis.