Single-cell analysis of severe COVID-19 patients reveals a monocyte-driven inflammatory storm attenuated by Tocilizumab

Abstract

1 inflammatory storm incited by monocyte centric immune interactions 2 revealed by single-cell analysis 3 4 ABSTRACT 40 41Coronavirus disease 2019 has caused more than 40,000 deaths 42 worldwide 1 . Approximately 14% of patients with COVID-19 experienced severe 43 disease and 5% were critically ill 2 . Studies have shown that dysregulation of the 44 COVID-19 patients' immune system may lead to inflammatory storm and cause severe 45 illness and even death 3,4 . Tocilizumab treatment targeting interleukin 6 receptor has 46shown inspiring clinical results of severe COVID-19 patients 5 . However, the immune 47 network with Tocilizumab treatment at single cell resolution has not been uncovered. 48Here, we profiled the single-cell transcriptomes of 13,289 peripheral blood 49 mononuclear cells isolated at three longitudinal stages from two severe COVID-19 50 patients treated with Tocilizumab. We identified a severe stage-specific monocyte 51 subpopulation and these cells centric immune cell interaction network connected by the 52 inflammatory cytokines and their receptors. The over-activated inflammatory immune 53 response was attenuated after Tocilizumab treatment, yet immune cells including 54 plasma B cells and CD8 + T cells still exhibited an intense humoral and cell-mediated 55 anti-virus immune response in recovered COVID-19 patients. These results provided 56 critical insights into the immunopathogenesis of severe COVID-19 and revealed 57 fundamentals of effectiveness in Tocilizumab treatment. 58 59 60 61Keywords ： Coronavirus disease 2019 (COVID-19); Severe acute respiratory 62 syndrome coronavirus 2 (SARS-CoV-2); Tocilizumab; Single-cell RNA sequencing 63(scRNA-seq); Inflammatory storm; Monocyte 64 65 (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission.

Dissecting the common and compartment-specific features of COVID-19 severity in the lung and periphery with single-cell resolution

“…Compositional changes were not as readily apparent in PBMCs, although we observed an expansion of multiple plasma cell types in severe donors compared to healthy control subjects, consistent with previous reports [23,33,34,44].…”

“…Cell type-specific immunopathological responses in severe COVID-19 have been investigated at both local and systemic levels in recent studies comparing severe patients to healthy controls [21,22,23,24,25,26,32,53,54,55]. We sought to build on this knowledge by determining the cell-type specific biological responses that differentiate mild and severe disease courses in the lung and systemic circulation.…”

“…A number of recent studies have compared severe patients to healthy control subjects in an effort to define immunological hallmarks of disease severity in both the lung and peripheral circulation using scRNA-seq. These studies have identified that severe disease in the lung compartment is associated with lymphopenia, T cell hyperactivation, and inflammatory macrophage polarization, while severe disease in the blood is associated with lymphopenia, suppression of type I and type II interferon activity, and decreased monocyte HLA class II expression [23,24,25,26]. Although these studies describe immunological dysregulation in severe COVID-19 patients requiring intensive care, they do not explore immunological features distinguishing these patients from those who experience a mild to moderate symptomatic disease course that does not become life-threatening.…”

Deep immune profiling of COVID-19 patients reveals patient heterogeneity and distinct immunotypes with implications for therapeutic interventions

“…Furthermore, D-dimer was associated with both WBC and PMN counts, although the later relationship was not significant (Figure S1B). IL-6 levels were variable across the 16 patients analyzed for suspected increased inflammation: normal in 1 patient, moderately elevated in 4 subjects (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) pg/ml), and high in 11 patients (21-738 pg/ml) ( Figure S1A). Thus, COVID-19 patients present with varied pre-existing comorbidities, complex clinical phenotypes, evidence of inflammation in many patients, and clinically altered leukocyte counts.…”

“…Most patients seroconvert within 7-14 days of onset of infection and increases in plasmablasts have been reported (15,(20)(21)(22). However, the role of humoral responses in the control of SARS-CoV2 and pathogenesis of COVID-19 disease remains unclear.…”