Evidence for the utility of cfDNA plasma concentrations to predict disease severity in COVID-19

COVID-19 is a pandemic caused by the highly infective SARS-CoV-2. There is a need for biomarkers not only for overall prognosis but also for predicting the response to treatments and thus for improvements in the clinical management of patients with COVID-19. Circulating cell-free DNA (cfDNA) has emerged as a promising biomarker in the assessment of various disease conditions. The aim of this retrospective and observational pilot study was to examine the potential value of cfDNA plasma concentrations as a correlative biomarker in hospitalized COVID-19 patients. Lithium-Heparin plasma samples were obtained from twenty-one COVID-19 patients during hospitalization in the University Medical Center of Mainz, Germany, and the cfDNA concentrations were determined by quantitative PCR yielding amplicons of long interspersed nuclear elements (LINE-1). cfDNA plasma concentrations of COVID-19 patients ranged between 247.5 and 6346.25 ng/ml and the mean concentrations were 1831 {+/-} 1388 ng/ml ({+/-} standard deviation). Correlations were found between cfDNA levels and the occurrence of acute respiratory distress symptom (ARDS), acute kidney injury (AKI), myositis, neurological complications, bacterial superinfection and disease severity as defined by sepsis-related organ failure assessment score (SOFA) score. D-Dimer and C-reactive-protein (CRP), determined by clinical laboratory analysis, showed the highest correlations with cfDNA levels. The results of this observational study suggest that cfDNA plasma concentrations may serve as a predictive biomarker of disease severity in COVID-19. Prospective studies enrolling larger patient cohorts are ongoing to test this hypothesis.