1. Academic Validation
  2. Prevalence and Mechanisms of Mucus Accumulation in COVID-19 Lung Disease

Prevalence and Mechanisms of Mucus Accumulation in COVID-19 Lung Disease

  • Am J Respir Crit Care Med. 2022 Jul 11. doi: 10.1164/rccm.202111-2606OC.
Takafumi Kato 1 Takanori Asakura 1 Caitlin E Edwards 2 Hong Dang 1 Yu Mikami 1 Kenichi Okuda 1 Gang Chen 1 Ling Sun 1 Rodney C Gilmore 1 Padraig Hawkins 1 Gabriela De la Cruz 3 Michelle R Cooley 2 Alexis B Bailey 2 Stephen M Hewitt 4 Daniel S Chertow 5 Alain C Borczuk 6 Steven Salvatore 7 Fernando J Martinez 8 Leigh B Thorne 9 Frederic B Askin 9 Camille Ehre 1 Scott H Randell 1 Wanda K O'Neal 10 Ralph S Baric 2 Richard C Boucher 11 NIH COVID-19 Autopsy Consortium
Affiliations

Affiliations

  • 1 University of North Carolina at Chapel Hill School of Medicine, 6797, Marsico Lung Institute, Chapel Hill, North Carolina, United States.
  • 2 University of North Carolina at Chapel Hill School of Medicine, 6797, Department of Epidemiology, Chapel Hill, North Carolina, United States.
  • 3 University of North Carolina at Chapel Hill School of Medicine, 6797, Pathology Services Core, Chapel Hill, North Carolina, United States.
  • 4 National Cancer Institute, 3421, Center for Cancer Research, Bethesda, Maryland, United States.
  • 5 NIH Clinical Center, 24481, Critical Care Medicine Department, Bethesda, Maryland, United States.
  • 6 Weill Cornell Medicine, 12295, Anatomic Pathology, New York, New York, United States.
  • 7 Weill Cornell Medicine, 12295, Pathology and Laboratory Medicine , New York, New York, United States.
  • 8 Weill Cornell Medicine, 12295, Pulmonary Critical Care Medicine, New York, New York, United States.
  • 9 University of North Carolina at Chapel Hill School of Medicine, 6797, Department of Pathology and Laboratory Medicine, Chapel Hill, North Carolina, United States.
  • 10 University of North Carolina at Chapel Hill, 2331, Marsico Lung Institute/Cystic Fibrosis Research Center, Chapel Hill, North Carolina, United States.
  • 11 University of North Carolina at Chapel Hill School of Medicine, 6797, Marsico Lung Institute, Chapel Hill, North Carolina, United States; richard_boucher@med.unc.edu.
Abstract

Rationale: The incidence and sites of mucus accumulation, and molecular regulation of Mucin gene expression, in COVID-19 lung disease have not been reported.

Objectives: Characterize incidence of mucus accumulation and the mechanisms mediating Mucin hypersecretion in COVID-19 lung disease.

Methods: Airway mucus and mucins were evaluated in COVID-19 autopsy lungs by AB-PAS and immunohistochemical staining, RNA in situ hybridization, and spatial transcriptional profiling. SARS-CoV-2-infected human bronchial epithelial (HBE) cultures were utilized to investigate mechanisms of SARS-CoV-2-induced Mucin expression and synthesis and test candidate countermeasures.

Measurements and main results: MUC5B and variably MUC5AC RNA levels were increased throughout all airway regions of COVID-19 autopsy lungs, notably in the sub-acute/chronic disease phase following SARS-CoV-2 clearance. In the distal lung, MUC5B-dominated mucus plugging was observed in 90% of COVID-19 subjects in both morphologically identified bronchioles and microcysts, and MUC5B accumulated in damaged alveolar spaces. SARS-CoV-2-infected HBE cultures exhibited peak titers 3 days post inoculation, whereas induction of MUC5B/MUC5AC peaked 7-14 days post inoculation. SARS-CoV-2 Infection of HBE cultures induced expression of EGFR ligands and inflammatory cytokines (e.g., IL-1α/β) associated with Mucin gene regulation. Inhibiting EGFR/IL-1R pathways, or dexamethasone administration, reduced SARS-CoV-2-induced Mucin expression.

Conclusions: SARS-CoV-2 Infection is associated with a high prevalence of distal airspace mucus accumulation and increased MUC5B expression in COVID-19 autopsy lungs. HBE culture studies identified roles for EGFR and IL-1R signaling in Mucin gene regulation post SARS-CoV-2 Infection. These data suggest that time-sensitive mucolytic agents, specific pathway inhibitors, or corticosteroid administration may be therapeutic for COVID-19 lung disease. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Keywords

Airway mucins; COVID-19; Epidermal growth factor receptor; Interleukin-1 receptor; SARS-CoV-2.

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