Alveolitis in severe SARS-CoV-2 pneumonia is driven by self-sustaining circuits between infected alveolar macrophages and T cells
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Abstract
Some patients infected with Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) develop severe pneumonia and the acute respiratory distress syndrome (ARDS) [1]. Distinct clinical features in these patients have led to speculation that the immune response to virus in the SARS-CoV-2-infected alveolus differs from other types of pneumonia [2]. We collected bronchoalveolar lavage fluid samples from 86 patients with SARS-CoV-2-induced respiratory failure and 252 patients with known or suspected pneumonia from other pathogens and subjected them to flow cytometry and bulk transcriptomic profiling. We performed single cell RNA-Seq in 5 bronchoalveolar lavage fluid samples collected from patients with severe COVID-19 within 48 hours of intubation. In the majority of patients with SARS-CoV-2 infection at the onset of mechanical ventilation, the alveolar space is persistently enriched in alveolar macrophages and T cells without neutrophilia. Bulk and single cell transcriptomic profiling suggest SARS-CoV-2 infects alveolar macrophages that respond by recruiting T cells. These T cells release interferon-gamma to induce inflammatory cytokine release from alveolar macrophages and further promote T cell recruitment. Our results suggest SARS-CoV-2 causes a slowly unfolding, spatially-limited alveolitis in which alveolar macrophages harboring SARS-CoV-2 transcripts and T cells form a positive feedback loop that drives progressive alveolar inflammation.
This manuscript is accompanied by an online resource: https://www.nupulmonary.org/covid-19/
One sentence summary
SARS-CoV-2-infected alveolar macrophages form positive feedback loops with T cells in patients with severe COVID-19.
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SciScore for 10.1101/2020.08.05.238188: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement IRB: Human subjects: All human subjects research was approved by the Northwestern University Institutional Review Board.
Consent: All subjects or their surrogates provided informed consent.Randomization not detected. Blinding not detected. Power Analysis not detected. Sex as a biological variable not detected. Table 2: Resources
Software and Algorithms Sentences Resources FASTQ files were generated using bcl2fastq (Illumina). bcl2fastqsuggested: (bcl2fastq , RRID:SCR_015058)0.6.4 and aligned to the hybrid genome described above using STAR 2.6.1d [47] STARsuggested: (STAR, RRID:SCR_015899)Gene-level assignment was then performed using featureCounts 1.6.4 [48] featureCountssuggest…SciScore for 10.1101/2020.08.05.238188: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement IRB: Human subjects: All human subjects research was approved by the Northwestern University Institutional Review Board.
Consent: All subjects or their surrogates provided informed consent.Randomization not detected. Blinding not detected. Power Analysis not detected. Sex as a biological variable not detected. Table 2: Resources
Software and Algorithms Sentences Resources FASTQ files were generated using bcl2fastq (Illumina). bcl2fastqsuggested: (bcl2fastq , RRID:SCR_015058)0.6.4 and aligned to the hybrid genome described above using STAR 2.6.1d [47] STARsuggested: (STAR, RRID:SCR_015899)Gene-level assignment was then performed using featureCounts 1.6.4 [48] featureCountssuggested: (featureCounts, RRID:SCR_012919)Data was processed using Scanpy v1.5.1 [52], doublets were detected with scrublet v0.2.1 [53] and removed, ribosomal genes were removed and multisample integration was performed with BBKNN v1.3.12 [54] BBKNNsuggested: NoneComputations were automated with snakemake v5.5.4 [56]. snakemakesuggested: (Snakemake, RRID:SCR_003475)Deconvolution of bulk RNA-seq alveolar macrophage signatures was performed using AutoGeneS v1.0.3[57] and signatures derived from integrated single cell RNA-Seq object. AutoGeneSsuggested: NoneVisualization: All plotting was performed using ggplot2 version 3.3.1, with the exception of heatmaps, which were generated using pheatmap version 1.0.12. ggplot2suggested: (ggplot2, RRID:SCR_014601)pheatmapsuggested: (pheatmap, RRID:SCR_016418)Figure layouts were generated using patchwork version 1.01 and edited in Adobe Illustrator 2020. Adobe Illustratorsuggested: (Adobe Illustrator, RRID:SCR_010279)Results from OddPub: Thank you for sharing your data.
Results from LimitationRecognizer: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.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.
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