Levels of Fibrinogen Variants Are Altered in Severe COVID-19

Abstract

Background: Fibrinogen variants as a result of alternative mRNA splicing or protein degradation can affect fibrin(ogen) functions. The levels of these variants might be altered during COVID-19, potentially affecting disease severity or the thrombosis risk. Aim: To investigate the levels of fibrinogen variants in plasma of patients with COVID-19. Methods: In this case-control study, we measured levels of functional fibrinogen using the Clauss assay. ELISAs were used to measure antigen levels of total, intact (non-degraded Aα chain), extended Aα chain (αE) and γ’ fibrinogen in health controls, patients with pneumococcal infection in the intensive care unit (ICU), ward patients with COVID-19, and ICU patients with COVID-19 (with and without thrombosis, two time points). Results: Healthy controls and ward patients with COVID-19 (n=10) showed similar fibrinogen (variant) levels. ICU patients with COVID-19 who later did (n=19) or did not develop thrombosis (n=18) and ICU patients with pneumococcal infection (n=6) had higher absolute levels of functional, total, intact and αE fibrinogen than healthy controls (n=7). The relative αE fibrinogen levels were higher in ICU patients with COVID-19 than in healthy controls, while relative γ’ fibrinogen levels were lower. After diagnosis of thrombosis, only the functional fibrinogen levels were higher in ICU patients with COVID-19 and thrombosis than in those without, while no differences were observed in the other fibrinogen variants. Conclusion: Our results show that severe COVID-19 is associated with increased levels of αE fibrinogen and decreased relative levels of γ’ fibrinogen, which may be cause or consequence of severe disease, but are not associated with the development of thrombosis.

The Relationship between the Laboratory Biomarkers of SARS-CoV-2 Patients with Type 2 Diabetes at Discharge and the Severity of the Viral Pathology

“…Another acute-phase protein is fibrinogen, the precursor of fibrin, which consists of two subunits with three polypeptide chains of Aalpha, Bbeta, and γ. Levels of fibrinogen variants have been associated with severe forms of SARS-CoV-2 infection [ 26 , 27 ]. This finding was also presented in our previous studies, which included data from patients at the time of admission [ 28 , 29 ].…”