FOSL2 and idiopathic interstitial pneumonia: The role of collagen expression by alveolar macrophages in IPF is unknown; however, a recent study showed that Collagen VI is upregulated in macrophages overexpressing Fra-2 in mouse models of pulmonary fibrosis and in IPF tissue macrophages while Col-VI knockout bone marrow chimeras were protected from bleomycin-induced lung fibrosis (23).