Fig. 1From: Acute exacerbation of idiopathic pulmonary fibrosis: lessons learned from acute respiratory distress syndrome?During AE-IPF, lung inflammation is driven by upregulation of macrophage activation pathways. M1 pathway classically activated by Th1 cytokines (IFN-γ) leads to increased IL-8 and CXCL1 expression and neutrophil recruitment though CXCR2 receptor. M2 pathway activated by type II alveolar epithelial cell injury might perpetuate lung fibrosis boosting collagen deposition, fibroblast proliferation, and epithelial–mesenchymal transition. AE-IPF acute exacerbation of idiopathic pulmonary fibrosis, DAD diffuse alveolar damage, IL interleukin, INF interferonBack to article page