SARS-CoV-2 PLASMA VIREMIA and DYSREGULATED IMMUNITY in SEVERE COVID-19

ABSTRACT

Background: Critical COVID-19 occurs ca. 7d from symptoms onset, and is associated to immune dysregulation as well as SARS-CoV-2 detection in plasma (i.e. viremia). We hereby sought to detail the association between SARS-CoV-2 viremia measured at the end of the first week of disease and immune phenotypes/function in COVID-19 patients. Methods: We consecutively enrolled patients hospitalized in the acute phase of ascertained SARS-CoV-2 pneumonia. In this disease stage, we studied SARS-CoV-2 viremia (RT-PCR) and cytokines (MACSPlex), HLA-DR+CD38+ activated, GRZB+PRF+ pro-cytolitic T-cells, intracellular cytokine production (IL-2, IFNγ, TNFα, IL-4, IL-17A) after SARS-CoV-2 challenge (S-N-M-peptide pool). Simultaneous Th1-cytokines production (polyfunctionality) and amount (iMFI) was assessed. Humoral response anti-S1/S2 IgG, anti-RBD total-Ig, IgM, IgA, IgG1 and IgG3 (ELISA), pseudoviruses neutralization (ID50) and Fc-mediated functions (%ADCC). Results: Out of 54 patients, 27 had detectable viremia (V+). Albeit comparable age and co-morbidities, V+ patients more frequently required non-invasive/invasive ventilatory support (p=0.035), with a trend to higher death (p=0.099) vs patients with undetectable viremia (V-)(Fig.1A). V+ displayed higher circulating IFN-α (p=0.002) and IL-6 (0.003), lower activated HLA-DR+CD38+CD4 (p=0.01) and CD8 (p=0.02), with no differences in GRZB+PRF+ T-cells. V+ featured reduced SARS-CoV-2-specific cytokine-producing T-cells, reaching significance for IFNγ+CD4 (p=0.02), TNFα+CD8, IL-4+CD8 (p=0.04) (Fig.1B-C), with lower bi-and tri-functional SARS-CoV-2-specific CD4 Th1, reaching significance for IL-2+TNFα+CD4 (p=0.03) (Fig.1D). A trend towards lower cytokines iMFI in bi-and tri-functional SARS-CoV-2-specific CD4 Th1 was observed in V+, reaching significance for IL-2+TNFα+CD4, p=0.004. V+ displayed lower anti-S IgG, anti-RBD total-Ig, IgM, IgG1 and IgG3 (Fig.1E), with lower ID50 and %ADCC vs V-(Fig.1F-G). Conclusion: Hospitalized COVID-19 patients with detectable plasma SARS-CoV-2 RNA in the acute phase of disease present worse outcome, higher inflammatory cytokines, fewer activated and SARS-CoV-2-specific polyfunctional T-cells, suggesting a link between SARS-CoV-2 viremia at the end of the first stage of disease and immune dysregulation. Whether high ab initium viral burden and/or intrinsic host factors contribute to a delayed and/or exhausted immune response in severe COVID-19 remains to be elucidated, to further inform strategies of targeted therapeutic interventions.