Characterization of the cytokine storm reflects hyperinflammatory endothelial dysfunction in COVID-19

Abstract

Background: Physicians treating patients with coronavirus disease 2019 (COVID-19) increasingly believe that the hyperinflammatory acute stage of COVID-19 results in a cytokine storm. The circulating biomarkers seen across the spectrum of COVID-19 have not been characterized compared with healthy controls, but such analyses are likely to yield insights into the pursuit of interventions that adequately reduce the burden of these cytokine storms.

Objective: To identify and characterize the host inflammatory response to severe acute respiratory syndrome coronavirus 2 infection, we assessed levels of proteins related to immune responses and cardiovascular disease in patients stratified as mild, moderate, and severe versus matched healthy controls.

Methods: Blood samples from adult patients hospitalized with COVID-19 were analyzed using high-throughput and ultrasensitive proteomic platforms and compared with age- and sex-matched healthy controls to provide insights into differential regulation of 185 markers.

Results: Results indicate a dominant hyperinflammatory milieu in the circulation and vascular endothelial damage markers within patients with COVID-19, and strong biomarker association with patient response as measured by Ordinal Scale. As patients progress, we observe statistically significant dysregulation of IFN-γ, IL-1RA, IL-6, IL-10, IL-19, monocyte chemoattractant protein (MCP)-1, MCP-2, MCP-3, CXCL9, CXCL10, CXCL5, ENRAGE, and poly (ADP-ribose) polymerase 1. Furthermore, in a limited series of patients who were sampled frequently, confirming reliability and reproducibility of our assays, we demonstrate that intervention with baricitinib attenuates these circulating biomarkers associated with the cytokine storm.

Conclusions: These wide-ranging circulating biomarkers show an association with increased disease severity and may help stratify patients and selection of therapeutic options. They also provide insights into mechanisms of severe acute respiratory syndrome coronavirus 2 pathogenesis and the host response.

Keywords: COVID-19; Ordinal Scale; baricitinib; biomarkers; cardiovascular; inflammation.

Fig 1

A-C, Inflammatory panel (Fig 1, A) or the cardiovascular panel II (Fig 1, B) FC in baseline protein levels, patients with COVID-19 vs HC (n = 20) (bottom). Baseline samples of patients with COVID-19 were classified on the basis of patients receiving treatment for 2 days or less (n = 25). Heatmaps of FC relative to baseline (day 0) are shown for moderate/severe patients treated with baricitinib (n = 4) (middle). Red or blue represents significantly upregulated or downregulated markers, respectively, with 1.5×-4× in light color, 4×-8× in medium color, and more than 8× in dark color. Analytes are ordered along the x-axis by P-value significance (P < .05) on the basis of their positive and negative FC (>1.5×) relative to HCs. A “+” sign designates that baricitinib-treated patients were within 1.5× of HCs. Correlations of biomarkers and clinical assessments such as Ordinal Scale, nasopharyngeal viral load (the most sensitive viral target gene, N gene, is shown), and inflammation status (CRP, ferritin, LDH) are shown for each biomarker across all longitudinal time points for patients with COVID-19 treated with baricitinib (top). Orange or green represents significantly positive or negative correlated markers, respectively, with 0.3 < Cor < 0.5 in light color, 0.5 < Cor < 0.7 in medium color, and Cor > 0.7 in dark color. Dashed line represents the last day a patient received baricitinib treatment. Fig 1, C, Volcano plots showing the inflammatory panel and IL-19 (top) or cardiovascular panel II (bottom) biomarkers at baseline for mild (left), moderate/severe (middle), and critical (right) patients compared with HCs. The y-axis is the −log10 of the P value, with higher numbers reflecting greater significance, and the x-axis represents the log2 FC, wherein color designation of blue or red represents decreased or increased presence of these markers relative to HC, respectively. CRP, C-reactive protein; FC, fold change; LDH, lactate dehydrogenase.

Fig 2

(A) IL-6, (B) MCP-3, (C) PTX3, and (D) GDF-2 levels in HCs vs mild, moderate/severe, or critical patients (left), correlation of analyte levels to Ordinal Scale for 4 patients (Fig 2, A-D) over the course of treatment with baricitinib (middle), and time-dependent changes in 4 patients treated with baricitinib (right). Dotted line identifies the levels seen in matched HCs (n = 20). Dashed bar represents the longest course of baricitinib treatment administered to a patient in this study (11 days). ∗P < .05.