CXCL12 and COVID-19: Although similarities between the histologic presentation and genetic background of PACS-associated pulmonary fibrosis and UIP have been reported [95], own data [96] show that gene expression, plasma protein expression, and disease course in COVID-19 are distinct from the common forms of interstitial lung diseases, including, e.g. key genes related to matricellular markers (GDF15, CD163), angiogenesis (CXCR4, CXCL12), and fibrosis (MMP1, COL3A1) which may underline the unique vascular etiology of COVID-19 [97].