DCN and idiopathic pulmonary fibrosis: MMP7, described as a potential diagnostic and prognostic biomarker of IPF [39,40] specifically cleaves DCN [41], a proteoglycan involved in the fibrillization of collagens and acts as an inhibitor of the powerful profibrotic agent transforming growth factor (TGF)-β that induces myofibroblast differentiation [42,43,44].