Circulating markers of angiogenesis and endotheliopathy in COVID-19

Abstract

Increase in thrombotic and microvascular complications is emerging to be a key feature of patients with critical illness associated with COVID-19 infection. While endotheliopathy is thought to be a key factor of COVID-19-associated coagulopathy, markers indicative of this process that are prognostic of disease severity have not been well-established in this patient population. Using plasma profiling of patients with COVID-19, we identified circulating markers that segregated with disease severity: markers of angiogenesis (VEGF-A, PDGF-AA and PDGF-AB/BB) were elevated in hospitalized patients with non-critical COVID-19 infection, while markers of endothelial injury (angiopoietin-2, FLT-3L, PAI-1) were elevated in patients with critical COVID-19 infection. In survival analysis, elevated markers of endothelial injury (angiopoietin-2, follistatin, PAI-1) were strongly predictive of in-hospital mortality. Our findings demonstrate that non-critical and critical phases of COVID-19 disease may be driven by distinct mechanisms involving key aspects of endothelial cell function, and identify drivers of COVID-19 pathogenesis and potential targets for future therapies.

Keywords: COVID-19; angiogenesis; endotheliopathy.

Figure 1.

Analyses of vascular biomarkers across the spectrum of COVID-19 disease severity. (a) Subject demographics for ICU patients with COVID-19 (classified by alive (A) and died (D)), non-ICU patients with COVID-19, and controls. *Obesity is defined as BMI > 30. ^♯One-way ANOVA. ^χGroup-wise Pearson’s Chi test; ^†Kruskal-Wallis test. ^‡Fisher’s exact test. SD, standard deviation; BMI, body-mass index; CHF, congestive heart failure; CAD, coronary artery disease; MI, myocardial infarction; TIA, transient ischemic attack; CKD, chronic kidney disease. (b) Heatmap indicating relative protein levels detected in each subject (columns) for proteins (rows) that had statistically significant differences between groups. (c) Comparisons of absolute plasma protein levels (pg/mL) for select markers between control, non-ICU, and ICU groups, as well as ICU survivors vs. non-survivors; differences were tested in two-sided t-tests (with Welch correction for unequal variances, where applicable) and two-tailed Mann-Whitney U-tests for samples that did and did not conform to the normal distribution, respectively. Significance levels are expressed as q-values (‘adjusted p-values’; *q < 0.05, **q < 0.01, ***q < 0.0001). (d) Raw values of vascular markers, p and q values for tests evaluating differences between subject cohorts; original tests with p < 0.05 were accepted as significant if corresponding q was less than the false discovery rate of 0.05 (highlighted green). (e) Kaplan-Meier curves for angiopoietin-2, follistatin, and PAI-1, indicating that patients with elevated circulating levels of these proteins had a significantly higher likelihood of in-hospital mortality. (f) Receiver operating characteristic (ROC) curves for angiopoietin-2, follistatin, PAI-1, and FLT-3L. (g) Schematic model of vascular processes in the progression of COVID-19 pathogenesis.