key: cord-1015524-edb09w05
authors: Fenyves, Bánk G.; Mehta, Arnav; Kays, Kyle R.; Beakes, Caroline; Margolin, Justin; Goldberg, Marcia B.; Hacohen, Nir; Filbin, Michael R.
title: Plasma P‐selectin is an early marker of thromboembolism in COVID‐19
date: 2021-10-16
journal: Am J Hematol
DOI: 10.1002/ajh.26372
sha: d22560793ab0d2031099f59d65c6d6b4a8e03eb5
doc_id: 1015524
cord_uid: edb09w05

nan

To the Editor:

Coagulopathy and intravascular thrombosis are known complications of SARS-CoV-2 infection. The pathomechanism of COVID-19-associated micro-and macrovascular thrombosis likely involves the interplay of the coronavirus with endothelial cells, platelets, and immune cells. 1 Activation of endothelial cells and platelets results in procoagulant imbalance and macrovascular thrombotic events that are associated with disease severity and adverse outcomes. 1 Coagulopathy is marked by altered plasma levels of several coagulation proteins (e.g., D-dimer, factors V and VIII, von Willebrand factor [vWF] , fibrinogen, and ADAMTS13). [2] [3] [4] However, previous studies investigated only small numbers of coagulation proteins together, and they were limited in their ability to adjust for confounders.

We leveraged a prospectively collected, previously published 5 acute COVID-19 biorepository to study the association of plasma levels of 31 coagulation proteins with the occurrence of venous thromboembolic events (VTE). Plasma protein levels of enrolled patients were assayed upon hospital arrival using two independent proteomic platforms (Olink Explore 1536 and Somalogic SomaScan).

Given that P-selectin was independently associated with VTE, we explored its temporal dynamics and potential utility as an early biomarker of thromboembolic complications.

We enrolled 384 patients that presented with respiratory distress to the Emergency Department of an urban, academic hospital in Boston, MA during the first peak of COVID-19 surge, as described previously. 5 Of the 384 enrolled, 306 patients were confirmed positive for SARS-CoV-2 by reverse transcriptase polymerase chain reaction. Specimen collection and banking was performed as previously described. 5 Samples were obtained on the day of admission (day 0) from all patients, and subsequently on days 3 and 7 from COVID-19-positive patients still hospitalized (Supplementary Information S1). Clinical data and outcomes were obtained from electronic health records. Patients who were intubated and/or died within 28 days were classified as severe. VTE was defined as pulmonary embolism (PE) or deep venous thrombosis (DVT) diagnosed within 28 days by computed tomography with pulmonary-phase angiography (CTPE) or venous duplex ultrasonography (US), respectively. Plasma biomarkers were measured using the Olink Explore 1536 Proximity Extension Assay and the Somalogic SomaScan Platform ® aptamer assay, as described previously. 5 Thirtyone coagulation biomarkers were selected a priori from the two protein libraries based on literature and hypothesized relevance (Table S1 ). All statistical analysis and plotting were done in RStudio (version 4.0.3) using standard packages (Supplementary Information S1).

The clinical characteristics of all enrolled patients are shown in were not significantly different between groups. Day 0 and day 3 D-dimer levels were higher in patients who had VTE (Δ +1738 ng/ml at day 0 and Δ +890 ng/ml at day 3 between VTE and non-VTE patients).

Of the 31 selected coagulation markers, COVID-19-positive patients who developed VTE had higher day 0 plasma levels of factors IX and XI, P-selectin, plasmin, activated protein C, and vWF and lower levels of ADAMTS13, antithrombin III, factor VII, protein C, and prolylcarboxypeptidase, in at least one assay (Table S3) . Notably, P-selectin and vWF levels were significantly higher in both assays, and ADAMTS13 and factor VII were significantly lower.

In multivariable linear regression modeling of each coagulation protein separately-and controlling for possible confounding factors: age, gender, ethnicity, comorbidities, and illness severity-we found that VTE was independently associated with higher day 0 levels of factor XI and P-selectin in the Somalogic panel and factor IX and P-selectin in the Olink panel. Factor IX was not significant in the Somalogic panel, while factor XI was not present in the Olink panel.

Furthermore, we found independent association of VTE with lower levels of protein C (in the Somalogic panel) and alpha-2-antiplasmin (only present in the Somalogic panel) ( Figure 1A ). P-selectin was also independently associated with VTE when adding anticoagulation status as a covariate to the model ( Figure S1 ). We analyzed the subset of COVID-19-positive patients who had high clinical suspicion of PE or DVT, defined as undergoing CTPE or US during their hospitalization (n = 82 total, n = 13 confirmed VTE), and found an independent association of elevated P-selectin with VTE (in both assays), factor IX (Olink only), and factor XI (Somalogic only) on day 0 ( Figure 1B) .

Given the independent significance of P-selectin in both assays, we further analyzed its temporal dynamics. Using the Olink data, we observed a steady increase in the plasma concentration of P-selectin in VTE patients over time. Median plasma level of P-selectin in VTEpositive patients was significantly higher than in VTE-negative patients E468 CORRESPONDENCE at each timepoint ( Figure 1C ). In adjusted linear regression models, including adjustment for severity, P-selectin on day 0 was independently associated with VTE, which progressively diminished on days 3 and 7 ( Figure 1C bottom panel) . This was accompanied by a strong association of illness severity with VTE on days 3 and 7 that was not present on day 0 ( Figure 1D) . Thus, illness severity may increasingly confound the relationship between P-selectin and VTE over time, yet P-selectin had predictive value for VTE early in disease course independent of severity.

To evaluate the predictive performance of P-selectin in COVID-19-positive patients in the context of clinical biomarkers associated with VTE and illness severity, we created logistic regression models using P-selectin, D-dimer, and fibrinogen as independent variables and analyzed their receiver operator characteristic (ROC) curves. We found that although the area under the ROC curve (AUC) of the P-selectin model was lower than that of D-dimer, the combined Pselectin + D-dimer model performed better than D-dimer alone (AUC 0.834 vs. 0.783, Figure 1E ). Both the fibrinogen and fibrinogen + Pselectin models had lower AUCs than the P-selectin model alone.

Our study demonstrates a consistent association of serum P-selectin levels with the development of VTE in a large cohort of patients admitted with COVID-19, across two independent proteomic platforms. P-selectin was associated with VTE upon presentation to the hospital after adjusting for age, comorbidities, and illness severity, implicating endothelial activation in the development of VTE.

Although not superior to D-dimer in its ability to discriminate VTE events when analyzed separately, P-selectin increased the discrimina- 

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