We aimed to study transcriptional and phenotypic changes in circulating immune cells associated with increased risk of mortality in COVID-19, resolution of pulmonary fibrosis in post-COVID-19-Interstitial Lung Disease (ILD) and persistence of Idiopathic Pulmonary Fibrosis. Whole blood and Peripheral Blood Mononuclear cells (PBMC) were obtained from 227 subjects with COVID-19, post-COVID-19 Interstitial Lung Disease (ILD), IPF and controls. We measured a 50-gene signature (nCounter, Nanostring) previously found to be predictive of IPF and COVID-19 mortality along with plasma levels of several biomarkers by Luminex. Additionally, we performed single-cell RNA sequencing in PBMC (10X Genomics) to determine the cellular source of the 50-gene signature. We identified the presence of three genomic risk profiles in COVID-19 based on the 50-gene signature associated with low, intermediate, or high-risk of mortality and with significant differences in pro-inflammatory and pro-fibrotic cytokines. COVID-19 patients in the high-risk group had increased expression of seven genes in CD14+HLA-DRlowCD163+Monocytic-Myeloid-Derived Suppressive cells (7Gene-M-MDSCs) and decreased expression of 43 genes in CD4 and CD8 T cell subsets. The loss of 7Gene-M-MDSC and increased expression of these 43 genes in T cells was seen in survivors with post-COVID-19-ILD. On the contrary, IPF patients had low expression of the 43 genes in CD4 and CD8 T cells. Collectively, we showed that a 50-gene, high-risk profile, predictive of IPF and COVID-19 mortality is characterized by a genomic imbalance in monocyte and T-cell subsets. This imbalance reverses in survivors with post-COVID-19-ILD highlighting genomic differences between post-COVID-19-ILD and IPF.
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