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Proc Natl Acad Sci U S A ; 119(1)2022 01 04.
Article in English | MEDLINE | ID: covidwho-1595265


Infection by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) provokes a potentially fatal pneumonia with multiorgan failure, and high systemic inflammation. To gain mechanistic insight and ferret out the root of this immune dysregulation, we modeled, by in vitro coculture, the interactions between infected epithelial cells and immunocytes. A strong response was induced in monocytes and B cells, with a SARS-CoV-2-specific inflammatory gene cluster distinct from that seen in influenza A or Ebola virus-infected cocultures, and which reproduced deviations reported in blood or lung myeloid cells from COVID-19 patients. A substantial fraction of the effect could be reproduced after individual transfection of several SARS-CoV-2 proteins (Spike and some nonstructural proteins), mediated by soluble factors, but not via transcriptional induction. This response was greatly muted in monocytes from healthy children, perhaps a clue to the age dependency of COVID-19. These results suggest that the inflammatory malfunction in COVID-19 is rooted in the earliest perturbations that SARS-CoV-2 induces in epithelia.

COVID-19/immunology , Epithelial Cells/immunology , Monocytes/immunology , SARS-CoV-2/pathogenicity , Adult , B-Lymphocytes/immunology , COVID-19/pathology , Child , Coculture Techniques , Ebolavirus/pathogenicity , Epithelial Cells/virology , Gene Expression Profiling , Humans , Inflammation , Influenza A virus/pathogenicity , Lung/immunology , Myeloid Cells/immunology , Species Specificity , Viral Proteins/immunology
Proc Natl Acad Sci U S A ; 118(37)2021 09 14.
Article in English | MEDLINE | ID: covidwho-1373495


The hallmark of severe COVID-19 is an uncontrolled inflammatory response, resulting from poorly understood immunological dysfunction. We hypothesized that perturbations in FoxP3+ T regulatory cells (Treg), key enforcers of immune homeostasis, contribute to COVID-19 pathology. Cytometric and transcriptomic profiling revealed a distinct Treg phenotype in severe COVID-19 patients, with an increase in Treg proportions and intracellular levels of the lineage-defining transcription factor FoxP3, correlating with poor outcomes. These Tregs showed a distinct transcriptional signature, with overexpression of several suppressive effectors, but also proinflammatory molecules like interleukin (IL)-32, and a striking similarity to tumor-infiltrating Tregs that suppress antitumor responses. Most marked during acute severe disease, these traits persisted somewhat in convalescent patients. A screen for candidate agents revealed that IL-6 and IL-18 may individually contribute different facets of these COVID-19-linked perturbations. These results suggest that Tregs may play nefarious roles in COVID-19, by suppressing antiviral T cell responses during the severe phase of the disease, and by a direct proinflammatory role.

COVID-19/etiology , T-Lymphocytes, Regulatory/physiology , Adult , Aged , CD4-Positive T-Lymphocytes/virology , Female , Forkhead Transcription Factors/genetics , Forkhead Transcription Factors/metabolism , Gene Expression Profiling , Gene Expression Regulation , Humans , Inflammation/metabolism , Inflammation/virology , Interleukin-18/genetics , Interleukin-18/metabolism , Interleukin-2 Receptor alpha Subunit/genetics , Interleukin-2 Receptor alpha Subunit/metabolism , Interleukin-6/genetics , Interleukin-6/metabolism , Lymphocytes, Tumor-Infiltrating/physiology , Male , Middle Aged , Severity of Illness Index , T-Lymphocytes, Regulatory/immunology , T-Lymphocytes, Regulatory/virology , Transcription Factors/genetics , Transcription Factors/metabolism