COVID-19 pathophysiology is currently not fully understood, reliable prognostic factors remain elusive, and few specific therapeutic strategies have been proposed. In this scenario, availability of
biomarkers is a priority. MS-based Proteomics techniques were used to profile the
proteome of 81 plasma samples extracted in four consecutive days from 23 hospitalized
COVID-19 associated
pneumonia patients. Samples from 10 subjects that reached a critical condition during their
hospital stay and 10 matched non-severe controls were drawn before the administration of any
COVID-19 specific treatment and used to identify potential
biomarkers of
COVID-19 prognosis. Additionally, we compared the
proteome of five patients before and after
glucocorticoids and
tocilizumab treatment, to assess the changes induced by the
therapy on our selected candidates. Forty-two
proteins were differentially expressed between patients' evolution groups
at 10% FDR. Twelve
proteins showed lower levels in critical patients (fold-changes 1.20-3.58), of which OAS3 and COG5 found their expression increased after
COVID-19 specific
therapy. Most of the 30
proteins over-expressed in critical patients (fold-changes 1.17-4.43) were linked to
inflammation, coagulation,
lipids metabolism,
complement or
immunoglobulins, and a third of them decreased their expression
after treatment. We propose a set of candidate
proteins for
biomarkers of
COVID-19 prognosis at the time of hospital admission. The study design employed is distinctive from previous works and aimed to optimize the chances of the candidates to be validated in confirmatory studies and, eventually, to play a useful role in the clinical practice.