Time-resolved Systems Immunology Reveals a Late Juncture Linked to Fatal COVID-19

 

Use the links below to go to the markdown reports for the corresponding figure panels appeared in the Cell 2021 paper. Source code of the markdown files can be found in this github repository: https://github.com/niaid/covid19-time-resolved

Figure 1: Study Design and a Multi-parameter Disease Severity Metric (DSM)

(A) COVID-19 patient cohort overview and sample collection timeline.

(B) Experimental design, analysis questions, and approach.

(C) Heatmap of 18 clinical and serum protein measurements of patients after correction for days since hospital admission.

(D) Parameter importance of the fitted coefficient values from partial-least-square (PLS) ordinal regression models of disease severity.

(E) Distribution of patient disease severity metric (DSM) grouped based on the disease severity-outcome classification for the 30 patients with CITE-seq data (left panel) and an independent set of 64 patients from Brescia (right panel).

 

 

Figure 2: A Multimodal Single Immune Cell Atlas of COVID-19

(A) Average protein expression in each coarse-level cell cluster.

(B) UMAP visualization of single cells based on protein expression profiles for innate and adaptive groupings of cells labelled by the name of the corresponding coarse-level cluster.

(C) Average expression of selected surface protein markers in example finer-resolution CD4+ T cell clusters (CM = central memory, TM = transitional memory, EM.TE = terminal/effector memory).

(D-I) Transcript-based UMAP visualization of classical monocytes defined by surface proteins.

 

 

Figure 3: Cell-type-specific Gene Expression Signatures of COVID-19 Disease Status and Severity

(A) Gene set enrichment analysis (GSEA) result of COVID-19 versus HCs at T0.

(B) Similar to (A) but the enrichment analysis was performed based on association with DSM, and the model controlled for TSO.

(C) Heatmap of type I IFN response in classical monocytes.

(D) Per-sample gene set signature scores of the GO Response to type I IFN gene set vs. TSO (in days) in DSM-low and DSM-high groups.

(E) Scatter plot comparing the effect size (normalized enrichment score) of association between TSO and the GO Response to type I IFN gene set in the DSM-high (y axis) and DSM-low (x axis) patients.

(F) Heatmap of apoptosis/cell death signature in pDCs.

(G) Heatmap showing the sample-level pairwise Pearson correlations among serum IFN-α2a level, pDC frequency, the apoptosis signature score in pDCs, as well as the IFN-I and protein translation signature scores in classical monocyte, CD56dimCD16hi NK, and CD8 memory T cell clusters (* p value < 0.05).

 

 

Figure 4: Conditional Independence Network Analysis Points to IL-15-associated Fatty Acid Metabolism and Attenuated Inflammation in CD56dimCD16hi NK Cells as Primary Correlates of Disease Severity

(A) Disease severity network showing cell type-specific gene set signatures directly connected with DSM.

(B and C, G and I) Scatter plots showing the correlation of circulating IL-15 level versus REACTOME_Fatty acid metabolism signature score (B) and DSM (C); REACTOME_Fatty acid metabolism score versus HALLMARK_TNFa signaling via NF-kB score and GO_Cellular response to IL-1 score (G); REACTOME_Fatty acid metabolism score versus HALLMARK_mTORC1 signaling score and normalized IFNG mRNA expression (I).

(D) Heatmap of REACTOME_Fatty acid metabolism LE genes from the GSEA analysis of DSM association in CD56dimCD16hiNK cells (see Figure 3B).

(E and F) Similar to (D). Heatmaps of inflammation related gene sets in CD56dimCD16hi NK cells: HALLMARK_TNFa signaling via NF-kB (E), GO_Cellular response to IL1 (see (A)), and KEGG_Chemokine signaling pathway (see (A)) (F).

(H) Average IFNG mRNA expression of CD56dimCD16hi NK cells; (B-C, F, I) are aligned column wise.

(J and K) Per-sample gene set signature scores of REACTOME_Fatty acid metabolism (J), HALLMARK_TNFa signaling via NFkB and GO_Cellular response to IL-1 (K) vs. TSO (in days) in DSM-high (red) and DSM-low (blue) groups of CD56dimCD16hi NK cells.

(L) Circulating IL-15 levels in DSM-low and DSM-high groups vs. TSO.

 

 

Figure 5: Single Cell and Clonal Expansion Analysis in CD8+ T cells and Exhaustion Assessment in Clonal CD8+ T cells

(A) Heatmap showing the gene expression profile of CD8+ T cell clusters identified based on single-cell mRNA expression of the leading-edge genes of selected pathways presented in Figure 3; only COVID-19 T0 samples are shown.

(B) Average expression of selected surface proteins in the clusters from (A).

(C) Results of linear model accounting for age, and experimental batch, comparing the frequency of CD8+ T cell clusters from (A) between COVID-19 and HC samples.

(D) Fraction of overlap between RNA based clustering (from A) and surface protein based CD8+ naive and memory T cell cluster annotations (based on high resolution clustering).

(E) CD8+ T cell clonality in HC, DSM-low, DSM-high groups.

(F) Coefficients from linear models of mean surface protein expression of canonical exhaustion markers fitted to COVID-19 patients and HCs.

(G) GSEA results for assessing enrichment for known exhaustion signatures in DE genes for expanded CD8+ T cells in COVID-19 versus HCs and DSM-high versus DSM-low comparisons.

 

 

Figure 6: Analyses of Timing Effects Suggest a Late Immune Response Juncture

(A) Time course of monocyte subset frequencies in DSM-low and DSM-high groups.

(B) Similar to (A) but showing the absolute blood neutrophil and monocyte counts.

(C) Effect size (normalized enrichment score from GSEA) comparison of the period before day 17 (TSO < day 17, green) and during the TSO = days 17-23 period (purple) for inflammatory related gene sets.

(D) Similar to Figure 3A, but here showing GSEA results for assessing differences between the DSM-high versus DSM-low groups using only samples from days 17-23 since symptom onset.

(E) Time course of gene set signature scores of inflammatory related gene sets in DSM-low and DSM-high patient groups in CD56dimCD16hi NK cells and classical monocytes.

(F) Time course of serum protein levels from DSM-high and DSM-low patients respectively.

 

 

Figure 7: Divergence of Deceased and Recovered Patients at the Late Juncture

(A) Approach for assessing and validating the late immune response juncture hypothesis by using serum protein profiles of critical ill patients with either recovery or deceased outcomes.

(B) Effect size plots of circulating serum proteins comparing the difference between critical deceased vs. recovered patients before (days 7-16), during (days 17-23), and after (days 24-30) the juncture period.

(C) Outcome prediction performance (recovered vs. fatal) at (17-23 days; purple) or post (24-30 days; blue) juncture using leave-one-out cross-validation.

(D) Similar to Figure 6F but showing serum protein levels of critical ill patients with recovery or deceased outcomes (see (A)).

(E) Similar to (D) but for antibody measurements against SARS CoV-2 spike and nucleocapsid proteins in critically ill patients with recovered or deceased outcomes.

 

 

Supplemental Figure 1 (related to Figure 1): Timeline of Treatments Relative to Hospital Admission Date and DSM Validation in an Independent Set of Patients

(A) Timeline of treatments relative to hospital admission date.

(B) Distribution of patient disease severity metric (DSM) grouped based on the WHO ordinal disease severity score of the CITE-seq cohort at the earliest time of PBMC sampling.

(C) Distribution of validation cohort disease severity metric (DSM) grouped by whether they were ever admitted to the ICU during the course of hospitalization for all patients (left) and only patients classified as Critical-Alive (right).

 

 

Supplemental Figure 2 (related to Figure 2): Single Immune Cell Atlas of COVID-19 Reveals Cell Populations Associated with COVID-19 Disease Status and Severity

(A) Correlations of cell frequencies gated from CITE-seq and independently obtained 27-color flow cytometry data of the same samples.

(B) Frequencies of immune cell clusters/subsets in HC, DSM-low (less severe disease; DSM at or below median of DSM) and DSM-high (more severe disease; DSM above median) groups at T0 (near hospitalization).

(C) Heatmap showing cell frequencies of major cell clusters/subsets in individual subjects (columns), grouped by HC and DSM.

 

 

Supplemental Figure 3 (related to Figure 3): Cell-type-specific Gene Expression Signatures Association with Time Since Symptom Onset and Disease Severity

(A and B) Similar to Figure 3B, but showing GSEA results (of select gene sets) based on association with time since symptom onset (TSO) in DSM-low (A) and DSM-high (B).

(C) Similar to Figure 3C. Heatmap of translation/ribosomal gene signature in classical monocytes.

(D) Similar to Figure 3D. Time course of gene set signature scores of REACTOME_Translation and KEGG_Ribosome gene sets in DSM-low and DSM-high groups, respectively.

(E and F) Similar to Figure 3F. Heatmap of apoptosis/cell death gene signature in pDCs of validation cohorts - Schulte-Schrepping et al., Cell, 2020 cohort 1 (E) and cohort 2 (F).

(G) GSEA results of Schulte-Schrepping et al. cohorts for pDC apoptosis/cell death signature identified in Brescia cohort.

 

 

Supplemental Figure 4 (related to Figure 4): Supporting Data for Dissecting Primary Gene Expression Signature Correlates Inferred by Conditional Independence Network Analysis

(A) Scatter plot of REACTOME_Oxidative stress-induced senescence signature score and GO_Apoptotic signaling signature score in pDCs.

(B) Similar to (A), but between circulating IL-15 level and fatty acid metabolism signature score in CD56dimCD16hi NK cells after regressing out their associations with DSM.

(C and D) Similar to Figure 4D. Heatmaps of REACTOME_Fatty acid metabolism in NK cells of two validation cohorts - Schulte-Schrepping et al, Cell 2020 cohort 1 (C) and cohort 2 (D).

(E) GSEA results of Schulte-Schrepping et al. cohorts for NK cell REACTOME_Fatty acid metabolism.

(F) Similar to Figure 4G. Scatter plot of REACTOME_Fatty acid metabolism score and HALLMAKR_TNFa signaling via NF-kB score in the validation cohorts - Schulte-Schrepping et al, 2020, Cell.

(G and H) Similar to Figure 4E. Heatmaps of inflammation related gene sets in classical monocytes: HALLMARK_TNFa signaling via NF-kB (G) and HALLMARK_Inflammatory response (H).

 

 

Supplemental Figure 5 (related to Figure 4): Exogeneous Corticosteroid Treatment is Not a Major Driver of Cell-type-specific Gene Expression Signatures Associated with Disease Severity

(A) GSEA results for glucocorticoid response signature in DSM association model.

(B and C) Scatter plot showing the correlations between the indicated signature scores (computed using GSVA) and the glucocorticoid response signature score (B) or the TSC22D3 mRNA expression level (C) in CD56dimCD16hi NK cells.

(D) TSC22D3 mRNA expression levels of CD56dimCD16hi NK cells and classical monocytes in HC, no steroid-use and steroid-use COVID-19 patient groups.

 

 

Supplemental Figure 6 (related to Figure 5): Single Cell and Clonal Expansion Analysis in CD4+ T cells and Exhaustion Assessment in CD8+ T cells

(A-B, C, D) Same as Figures 5A-5D but for CD4+ T cells. 15 CD4+ T cell clusters were tested in linear models.

(E) Similar to Figure 5F but for pseudo-bulk mRNA expression of canonical exhaustion markers.

(F) Association of proportion of CD39+PD1+ cells with COVID-19 versus HCs and DSM in clonal CD8+ memory T cells using different cutoffs for CD39 and PD1 surface protein expression DSB counts (0.5, 1).

(G) Association of proportion of exhausted cells with COVID-19 versus HCs and DSM in clonal CD8+ memory T cells based using different cutoffs for surface protein expression DSB counts (0.5, 1, 1.5) and number of exhaustion markers above DSB count cutoff (2 or 3 markers).

(H) Gene set enrichment of Wherry et al. up and down genes in KEGG, GO BP, REACTOME, and Li BTM's.

(I) GSEA result of Schulte-Schrepping et al. cohorts for exhaustion signatures of COVID-19 versus HCs and severe versus mild comparisons at T0.

(J) Similar to Figure 5G. GSEA results of Schulte-Schrepping et al. cohorts for Wherry et al. exhaustion signatures of COVID-19 versus HCs and severe versus mild comparisons at T0.

 

 

Supplemental Figure 7 (related to Figures 6 and 7): Supporting Data for Critical Juncture Analysis

(A) Similar to Figure 3A, but here showing GSEA results for assessing the differences of delta between disease severity groups (DSM-high versus DSM-low) between the days 17-23 time window and the period before (TSO < day 17).

(B) Time course of blood neutrophil and monocyte counts in recovered and deceased groups.

(C) Effect size comparison of DSM-high versus DSM-low (CITE-seq cohort) and deceased versus recovered (critical patients with distinct outcome subcohorts - see Figure 6G) at the days 17-23 period.

(D) Similar to (C). Effect size comparison of Brescia deceased versus recovered and an independent US cohort (Yale cohort, Lucas et al, 2020, Nature) deceased versus recovered patients (See Methods) for 38 overlapping circulating proteins/cytokines at the juncture period (TSO days 17-23).

 

Additional Supplementary Datasets:

(Table OS1) Correlation between cytokine levels and module scores of selected gene sets.