Finally, group IV comprised several mediators of pulmonary fibrosis as IL-8/CXCL8, monocyte chemoattractant protein-1 (MCP-1)/CCL-2, monokine induced by IFN-γ (MIG)/CXCL9 and fibroblast growth factor-(FGF)-9, highly expressed in IPF patients but not in the other two groups (see Additional File 1: Fig. S3). This evidence concerns the gene IFNG and pulmonary fibrosis.