GDF15 and interstitial lung disease: ,15 Although similarities between the histological presentation and the genetic background of severe COVID-19 and UIP have been described,46,47 our data show that gene expression, plasma protein expression, and disease trajectory in COVID-19 are distinct from the common forms of ILD, including, e.g., key genes related to inflammation (gdf15, cd163), angiogenesis (cxcr4, cxcl12), and fibrosis (mmp1, col3a1), potentially reflecting the unique vascular etiology of COVID-19.