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Complement activation and lung injury in Japanese patients with COVID-19: a prospective observational study

Kentaro Seki1, Koichiro Sueyoshi2, Yukari Miyoshi1

  • 1Department of Emergency and Critical Care Medicine, Juntendo University Urayasu Hospital, Urayasu, Chiba, Japan.

Scientific Reports
|October 22, 2024
PubMed

Insights

Complement activation exacerbates lung injury in COVID-19 patients. While complement factors don't predict mechanical ventilation needs, elevated syndecan-1 may indicate disease severity.

Area of Science:

  • Immunology
  • Pathophysiology
  • Critical Care Medicine

Background:

  • Increased inflammatory cytokines in COVID-19 patients drive neutrophil and monocyte migration to lungs.
  • This migration damages the air-blood barrier, affecting bronchial epithelial and vascular endothelial cells.
  • Complement activation, implicated in sepsis-induced organ dysfunction, may contribute to COVID-19 lung injury.

Purpose of the Study:

  • To investigate the association between complement activation and the pathophysiology of COVID-19.
  • To explore the role of complement factors and regulators in COVID-19 progression.

Main Methods:

  • Enrolled 27 COVID-19 patients, divided into invasive mechanical ventilation (IMV) and non-IMV groups.
  • Measured plasma levels of complement factors (C3a, C5a, Ba, sC5b-9), complement regulators (sCD59, factor H), interleukin-6 (IL-6), and syndecan-1 using ELISA.

Main Results:

  • Significantly elevated levels of complement factors, regulators, IL-6, and syndecan-1 in COVID-19 patients versus healthy controls.
  • Decreased C5a and sC5b-9 levels in the IMV group compared to the non-IMV group.
  • Significantly increased syndecan-1 levels in the IMV group compared to the non-IMV group.

Conclusions:

  • Complement activation is an exacerbating factor in COVID-19-related lung injury.
  • Complement factors are not essential predictors for mechanical ventilation in COVID-19 patients.
  • Syndecan-1 shows potential as a biomarker for COVID-19 severity.

Keywords:
COVID-19Complement systemInvasive mechanical ventilationSyndecan-1

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