Neutrophil and monocyte extracellular traps in the diagnosis of post-COVID syndrome

Salmasi JM, Poryadin GV, Panina MI, Larina VN, Ryzhikh AA, Stodelova EA, Kazimirskii AN
About authors

Pirogov Russian National Research Medical University, Moscow, Russia

Correspondence should be addressed: Alexander N. Kazimirskii
Ostrovityanov, 1, Moscow, 117997, Russia; ur.liam@01acinla

About paper

Acknowledgements: the authors express their gratitude to all the patients enrolled for their active cooperation and thank the physicians and nurses at the Diagnostic Clinical Center No. 1 of the Moscow Department of Health.

Author contribution: Poryadin GV, Larina VN — study concept and design; Ryzhikh AA, Stodelova EA — data acquisition and processing; Stodelova EA, Kazimirskii AN — experimental studies, preparation of illustrations; Panina MI — statistical data processing; Kazimirskii AN — manuscript writing; Salmasi JM, Panina MI — editing.

Compliance with ethical standards: the study was approved by the Ethics Committee at the Pirogov Russian National Research Medical University (protocol № 203 of 21 December 2021); all patients submitted the informed consent to study participation.

Received: 2022-10-29 Accepted: 2022-11-25 Published online: 2022-12-09

Post-COVID syndrome (long covid, post COVID-19 condition) is characterized by cognitive and mental disorders, chest and joint pain, impaired sense of smell and taste, as well as by gastrointestinal and cardiac disorders. The diagnosis of post-COVID syndrome is based mainly on the patients' complaints. To date, no optimal diagnostic method has been proposed. The study was aimed to compare the informative value of the indicators obtained during conventional assessment of patients with post-COVID syndrome and the blood levels of neutrophil (NETs) and monocyte (METs) extracellular traps. The study involved neutropils and monocytes collected from 21 patients with post-COVID syndrome aged 18–59. Fluorescence microscopy and the SYBR Green (Evrogen) fluorescent dye for double-stranded DNA were used for enumeration and imaging of extracellular traps. Clinical and laboratory indicators make it impossible to identify the changes specific for post-COVID syndrome. At the same time, post-COVID syndrome is characterized by inflammation in the vascular endothelium. The filamentous forms of NETs found in blood are a laboratory feature of such aseptic inflammation. The filamentous forms of NETs have been detected only in those patients who have a history of mild to severe СOVID-19, while the filamentous forms of METs have been found in patients having a history of severe infection. The findings show that the detection of the filamentous forms of NETs and METs in blood is the most informative diagnostic feature of post-COVID syndrome. 

Keywords: diagnosis, post-COVID syndrome, neutrophil extracellular traps, monocyte extracellular traps, filamentous forms