Increased plasma level of soluble P-selectin in non-hospitalized COVID-19 convalescent donors.

BACKGROUND: The coronavirus disease-2019 (COVID-19) is a systemic disease with severe implications on the vascular and coagulation system. A procoagulant platelet phenotype has been reported at least in the acute disease phase. Soluble P-selectin (sP-sel) in the plasma is a surrogate biomarker of platelet activation. Increased plasma levels of sP-sel have been reported in hospitalized COVID-19 patients associated with disease severity. Here, we evaluated in a longitudinal study the sP-sel plasma concentration in blood donors who previously suffered from moderate COVID-19. METHODS: 154 COVID-19 convalescent and 111 non-infected control donors were recruited for plasma donation and for participation in the CORE research trial. First donation (T1) was performed 43-378 days after COVID-19 diagnosis. From most of the donors the second (T2) plasma donation including blood sampling was obtained after a time period of 21-74 days and the third (T3) donation after additional 22-78 days. Baseline characteristics including COVID-19 symptoms of the donors were recorded based on a questionnaire. Platelet function was measured at T1 by flow cytometry and light transmission aggregometry in a representative subgroup of 25 COVID-19 convalescent and 28 control donors. The sP-sel plasma concentration was determined in a total of 704 samples by using a commercial ELISA. RESULTS: In vitro platelet function was comparable in COVID-19 convalescent and control donors at T1. Plasma samples from COVID-19 convalescent donors revealed a significantly higher sP-sel level compared to controls at T1 (1.05 ± 0.42 ng/mL vs. 0.81 ± 0.30 ng/mL; p < 0.0001) and T2 (0.96 ± 0.39 ng/mL vs. 0.83 ± 0.38 ng/mL; p = 0.0098). At T3 the sP-sel plasma level was comparable in both study groups. Most of the COVID-19 convalescent donors showed a continuous decrease of sP-sel from T1 to T3. CONCLUSION: Increased sP-sel plasma concentration as a marker for platelet or endothelial activation could be demonstrated even weeks after moderate COVID-19, whereas, in vitro platelet function was comparable with non-infected controls. We conclude that COVID-19 and additional individual factors could lead to an increase of the sP-sel plasma level.

Soluble P-selectin as a potential diagnostic and prognostic biomarker for COVID-19 disease: A case-control study.

INTRODUCTION: To our knowledge, the diagnostic value of the sP-Selectin level in the diagnosis of COVID-19 disease has not yet been investigated. In this study, we aimed to assess this by evaluating the relationship between sP-Selectin level and the clinical severity of COVID-19 infections. METHODS: A total of 80 patients (50 with mild to moderate and 30 with severe COVID-19 pneumonia), and 60 non-symptomatic healthy volunteers participated in the study. Following serum isolation, sP-Selectin levels were assessed by Enzyme-Linked Immunosorbent Assay (ELISA) method. RESULTS: The serum sP-Selectin level was 1.7 ng/ml in the control group (1-3.78); 6.24 ng/ml (5.14-7.23) in mild-to-moderate pneumonia group; and 6.72 ng/ml (5.36-8.03) in the severe pneumonia group. Serum sP-Selectin levels in both mild-to-moderate pneumonia and severe pneumonia groups were found to be higher than the control group, with statistical significance (p = 0.0001 and p = 0.0001, respectively). Receiver operating characteristic analysis (ROC) showed greater area under the curve (AUC) for the serum sP-Selectin levels of the COVID-19 patients (AUC = 0.913, 95% CI = 0.857-0.969; p = 0.0001). The serum sP-Selectin level was found to be 97.5% sensitive and 80% specific at 4.125 ng/ml level for diagnosis (p = 0.0001). The serum sP-Selectin level was found to be 76.9% sensitive and 51.9% specific at the level of 6.12 ng/ml (p = 0.005) to predict the need for intensive care treatment. CONCLUSION: This study showed that sP-Selectin can be used as a valuable biomarker in both diagnosing and predicting the need for intensive care treatment of COVID-19 infection.