Distinct cytokine profiles associated with COVID-19 severity and mortality

Abstract

Background: Markedly elevated levels of proinflammatory cytokines and defective type-I interferon responses were reported in patients with coronavirus disease 2019 (COVID-19).

Objective: We sought to determine whether particular cytokine profiles are associated with COVID-19 severity and mortality.

Methods: Cytokine concentrations and severe acute respiratory syndrome coronavirus 2 antigen were measured at hospital admission in serum of symptomatic patients with COVID-19 (N = 115), classified at hospitalization into 3 respiratory severity groups: no need for mechanical ventilatory support (No-MVS), intermediate severity requiring mechanical ventilatory support (MVS), and critical severity requiring extracorporeal membrane oxygenation (ECMO). Principal-component analysis was used to characterize cytokine profiles associated with severity and mortality. The results were thereafter confirmed in an independent validation cohort (N = 86).

Results: At time of hospitalization, ECMO patients presented a dominant proinflammatory response with elevated levels of TNF-α, IL-6, IL-8, and IL-10. In contrast, an elevated type-I interferon response involving IFN-α and IFN-β was characteristic of No-MVS patients, whereas MVS patients exhibited both profiles. Mortality at 1 month was associated with higher levels of proinflammatory cytokines in ECMO patients, higher levels of type-I interferons in No-MVS patients, and their combination in MVS patients, resulting in a combined mortality prediction accuracy of 88.5% (risk ratio, 24.3; P < .0001). Severe acute respiratory syndrome coronavirus 2 antigen levels correlated with type-I interferon levels and were associated with mortality, but not with proinflammatory response or severity.

Conclusions: Distinct cytokine profiles are observed in association with COVID-19 severity and are differentially predictive of mortality according to oxygen support modalities. These results warrant personalized treatment of COVID-19 patients based on cytokine profiling.

Keywords: COVID-19; mortality; principal-component analysis; respiratory severity; serum cytokines; type-I interferons.

Graphical abstract

Fig 1

Distinct cytokine profiles associated with COVID-19 respiratory severity. A, PCA of 12 serum cytokines measured in patients with COVID-19 and controls. B, PCA, and PC factors (table), of the 8 cytokines most contributing to interpatient variation in patients with COVID-19, segregates the patients by respiratory severity groups. Ellipses represent the 68% CI of patient distribution in each group. Levels of the ensuing fcc-_INFLAM (C), for inflammatory cytokines derived from PC1, and fcc-_IFNI (D), for type-I interferons derived from PC2, are depicted for each respiratory severity group and the controls. Initial PCA with all 12 cytokines measured in the patients with COVID-19 had shown that IFN-γ, GM-CSF, IL-17A, and IL-18 either contribute less to the variation between patients and/or have a mixed contribution to PC1 and PC2. PC1 and PC2 contributed most of the variation between patients (67.3%), whereas higher PC dimensions had lower contributions (PC3 = 9.7%, PC4 = 6.6%) and did not contribute to separation of patients by severity. ns, Nonsignificant; PC, principal component. ∗P < .05; ∗∗P < .01; ∗∗∗P < .001; ∗∗∗∗P < .0001.

Fig 2

Distinct cytokine combinations associated with COVID-19 mortality. PCAs for each respiratory severity group: No-MVS (A), MVS(∗) (B), and ECMO (C) segregate surviving vs deceased patients in association with different cytokine combinations (corresponding PC factors in the tables). Levels of the ensuing f_CC from the PC factors for each group, f_No-MVS (D), f_MVS (E), and f_ECMO (F), are depicted for surviving vs deceased patients in each respiratory severity group. ns, Nonsignificant; PC, principal component. (∗)MVS with SAPS-II score greater than or equal to 35 (median of the MVS patients). ∗P < .05; ∗∗P < .01; ∗∗∗P < .001; ∗∗∗∗P < .0001.

Fig 3

SARS-CoV-2 serum viral load association with severity and mortality. A, SARS-CoV-2 nucleocapsid (N)-antigen levels depicted by respiratory severity group and deceased vs surviving patient per group (No-MVS: 100% ALQ in deceased vs 34.5% ALQ in surviving patients, P = .002; MVS: 86.4% ALQ in deceased vs 53.2% ALQ in surviving patients, P = .008; ECMO: 16.7% ALQ in deceased vs 47.6% ALQ in surviving patients, P = ns). B, SAPS-II scores depicted as function of N-antigen levels per patient (R = 0.05; P = ns), with deceased vs surviving patients marked. Only patients with a sample taken at most 14 days after symptom onset are included in the analysis, because antigen levels were significantly lower in samples taken after 14 days (50% BLD), as compared with until day 14 (5.4% BLD; P < .0001). For samples until 14 days there was no correlation of N-antigen levels with time from symptom onset and no difference between the cohorts. Ag, Antigen; ALQ, above upper limit of quantification; BLD, below limit of detection; ns, nonsignificant. ∗P < .05; ∗∗P < .01; ∗∗∗P < .001; ∗∗∗∗P < .0001.

Fig 4

Correlation between SARS-CoV-2 serum viral load and cytokine levels. The f_CC values for fcc-_IFNI comprising type-I interferons IFN-α, and IFN-β (A-C) and fcc-_INFLAM comprising the inflammatory cytokines TNF-α, IL-10, IL-6, and IL-8 (D-F) are plotted as function of SARS-CoV-2 nucleocapsid (N)-antigen levels for each of the respiratory severity groups. Only patients with a sample taken at most 14 days after symptom onset are included in the analysis (see Fig 3). Ag, Antigen; ALQ, above upper limit of quantification; BLD, below limit of detection; N.S., nonsignificant.

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