INTERSTITIAL LUNG DISEASE PROTEIN BIOMARKERS IN POST-COVID PATIENTS

Critical care patients who survive to severe COVID-19 are at higher risk of developing interstitial lung disease (ILD). Identifying protein biomarkers of lung sequelae may help to clarify the underlying pathophysiology and contribute to the development of precision medicine strategies. Here, we aimed to identify a set of proteins that could be used as biomarkers of ILD in post-COVID patients. Protein levels from plasma samples collected at 6 months post-ICU discharge of 40 post-COVID patients that survived severe ARDS was obtained via the Olink® Explore assay (3,072 proteins). ILD was assessed by CT scans, quantitative analysis of lung attenuation and of different pulmonary function parameters with a follow-up at 6 months after ICU discharge. Protein prioritization was based on Student's t-test and principal component analysis to identify those contributing more to the differentiation of patients evidencing ILD. Spearman correlation analysis was used to reduce protein information redundancy. Functional enrichment analysis was performed using EnrichR. A total of 203 proteins showed nominally significant differences between ILD and non-ILD patients at six months. Further analyses prioritized 10 non-redundant proteins of this set. These proteins are involved in key mechanisms of immune regulation, inflammatory signalling, and tissue remodelling. We identified a set of proteins that may serve as biomarkers for post-COVID ILD. Validation in independent patients is needed.