Possible involvement of Syndecan-1 in the state of COVID-19 related to endothelial injury

BACKGROUND: The coronavirus infection 2019 (COVID-19) is associated with microvascular endothelial injury. Here, we report that syndecan-1, a component of endothelial glycocalyx, may reflect the disease state of COVID-19 related to endothelial injury. CASE PRESENTATION: A patient with COVID-19 was transferred to the intensive care unit of our hospital. Computed tomography of the chest showed bilateral ground glass opacities, which was diagnosed as acute respiratory syndrome. The PaO(2)/F(I)O(2) ratio gradually increased from 158 on hospitalization to 300 on Day 11, on which day the ventilator was withdrawn. However, serum syndecan-1 (SDC-1) level gradually decreased from 400.5 ng/ml at hospitalization to 165.1 ng/ml on Day 5. On Day 6, serum SDC-1 level increased to 612.9 ng/ml owing to a systemic thrombosis with an increase in D-dimer. Serum SDC-1 level then decreased until 206.0 ng/ml on Day 11 after a decrease in D-dimer. The patient was transferred to another hospital on Day 21 after hospitalization. CONCLUSIONS: In this case report, changes in serum SDC-1 level closely reflected the change in disease condition in a patient with COVID-19. Serum SDC-1 may be a useful biomarker for monitoring the disease state of critically ill patients with COVID-19.