SARS-CoV-2 infection results in immune responses in the respiratory tract and peripheral blood that suggest mechanisms of disease severity

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Abstract

Respiratory tract infection with SARS-CoV-2 results in varying immunopathology underlying COVID-19. We examine cellular, humoral and cytokine responses covering 382 immune components in longitudinal blood and respiratory samples from hospitalized COVID-19 patients. SARS-CoV-2-specific IgM, IgG, IgA are detected in respiratory tract and blood, however, receptor-binding domain (RBD)-specific IgM and IgG seroconversion is enhanced in respiratory specimens. SARS-CoV-2 neutralization activity in respiratory samples correlates with RBD-specific IgM and IgG levels. Cytokines/chemokines vary between respiratory samples and plasma, indicating that inflammation should be assessed in respiratory specimens to understand immunopathology. IFN-α2 and IL-12p70 in endotracheal aspirate and neutralization in sputum negatively correlate with duration of hospital stay. Diverse immune subsets are detected in respiratory samples, dominated by neutrophils. Importantly, dexamethasone treatment does not affect humoral responses in blood of COVID-19 patients. Our study unveils differential immune responses between respiratory samples and blood, and shows how drug therapy affects immune responses during COVID-19.

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  1. SciScore for 10.1101/2021.09.01.21262715: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    NIH rigor criteria are not applicable to paper type.

    Table 2: Resources

    Antibodies
    SentencesResources
    Phenotypic whole blood immune analyses: Fresh whole blood (200μl per stain) was used to measure CD4+CXCR5+ICOS+PD1+ follicular T cells (Tfh) and CD3-CD19+CD27hiCD38hi antibody-secreting B cell (ASC; plasmablast) populations as described15, 49 as well as activated HLA-DR+CD38+CD8+ and HLA-DR+CD38+CD4+ T cells, intermediate CD14+CD16+ and classical CD14+ monocytes, activated CD3-CD56+ NK cells, MAIT cells, [δ-T cells, as per the specific antibody panels (Supplementary Table 6; gating strategy is presented in Supplementary Fig.
    CD3-CD19+CD27hiCD38hi antibody-secreting B
    suggested: None
    antibody-secreting
    suggested: (Félix A. Rey; Pasteur Institute Cat# C10, RRID:AB_2725800)
    SARS-CoV-2 RBD ELISA: RBD-specific ELISA for detection of IgM, IgG and IgA antibodies was performed as previously described31, 50, 51, using flat bottom Nunc MaxiSorp 96-well plates (Thermo Fisher Scientific) for antigen coating (2µg/ml), blocking with PBS (with w/v 1% BSA) and serial dilutions in PBS (with v/v 0.05% Tween and w/v 0.5% BSA).
    IgM , IgG
    suggested: None
    IgA
    suggested: None
    antigen coating ( 2µg/ml)
    suggested: None
    The sVNT blocking ELISA assay (manufactured by GenScript, NJ, USA) was carried out essentially as described51, which detects circulating neutralizing SARS-CoV-2 antibodies that block the interaction between RBD and ACE2 on the cell surface receptor of the host.
    ACE2
    suggested: None
    Colour intensity was inversely dependent on the titre of anti-SARS-CoV-2 neutralizing antibodies.
    anti-SARS-CoV-2 neutralizing antibodies .
    suggested: None
    Experimental Models: Cell Lines
    SentencesResources
    SARS-CoV-2 isolate CoV/Australia/VIC01/202053 was propagated in Vero cells and stored at -80°C.
    Vero
    suggested: None
    Cytokine analysis: Patients’ plasma and respiratory samples were measured for IL-1β, IFN-α2, IFN-γ, TNF, MCP-1 (CCL2), IL-6, IL-8 (CXCL8), IL-10, IL-12p70, IL-17A, IL-18, IL-23 and IL-33 using the LEGENDplex™ Human Inflammation Panel 1 kit, as per manufacturer’s instructions (BioLegend, San Diego, CA, USA).
    MCP-1
    suggested: None
    Software and Algorithms
    SentencesResources
    Flow cytometry data were analyzed using FlowJo v10 software.
    FlowJo
    suggested: (FlowJo, RRID:SCR_008520)
    Endpoint titres were determined by interpolation from a sigmodial curve fit (all R-squared values >0.95; GraphPad Prism 9) as the reciprocal dilution of plasma that produced >15% (for IgA and IgG) or >30% (for IgM) absorbance of the positive control at a 1:31.6 (IgG and IgM) or 1:10 dilution (IgA).
    GraphPad
    suggested: (GraphPad Prism, RRID:SCR_002798)
    PLSDA: Partial least squares discriminant analysis (PLSDA), performed in Eigenvectors PLS toolbox in Matlab, was used in conjunction with Elastic-Net, described above, to identify and visualize signatures that distinguish categorical outcomes (COVID-19 diagnosis, NIH scores, drug therapies).
    Matlab
    suggested: (MATLAB, RRID:SCR_001622)
    In R, data were subject to arcsinh transformation and clustering using FlowSOM 27.
    FlowSOM
    suggested: (FlowSOM, RRID:SCR_016899)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).


    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    There are limitations to the current study. Firstly, ETA samples were only collected from patients with severe disease requiring invasive oxygen support, therefore, it is unclear whether COVID-19 patients with milder symptoms had less robust immune responses in the respiratory tract. Additionally, most patients in the severe/critical group received dexamethasone, which could be an intercorrelating factor for the differences observed between severity groups. Moreover, while the non-COVID-19 controls provided insights onto the immune status in hospitalized individuals, the comparisons will benefit more if there were larger numbers of non-COVID patients with more homogenous diseases. Overall, innate and adaptive immune responses are generated in respiratory and blood samples of COVID-19 patients. While immunological features detected in the peripheral blood can be associated with robust immune responses and predict clinical outcomes, monitoring immune responses in the respiratory samples can be of a benefit prior to initiation of therapeutic interventions for COVID-19 patients.

    Results from TrialIdentifier: No clinical trial numbers were referenced.


    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.


    Results from JetFighter: We did not find any issues relating to colormaps.


    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    Results from scite Reference Check: We found no unreliable references.


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