SARS-CoV-2 disrupts respiratory vascular barriers by suppressing Claudin-5 expression

In the initial process of COVID-19, SARS-CoV-2 infects respiratory epithelial cells and then transfers to other organs via the blood vessels. It is believed that SARS-CoV-2 can pass the vascular wall by altering the endothelial barrier using an unknown mechanism. In this study, we investigated the effect of SARS-CoV-2 on the endothelial barrier using an airway-on-a-chip that mimics respiratory organs and found that SARS-CoV-2 produced from infected epithelial cells disrupts the barrier by decreasing Claudin-5 (CLDN5), a tight junction protein, and disrupting vascular endothelial cadherin (VE-cadherin)-mediated adherens junctions. Consistently, the gene and protein expression levels of CLDN5 in a COVID-19 patient's lungs were decreased. CLDN5 overexpression or Fluvastatin treatment could rescue the SARS-CoV-2-induced respiratory endothelial barrier disruption. We therefore concluded that the downregulation of CLDN5 expression is a pivotal mechanism for SARS-CoV-2-induced endothelial barrier disruption in respiratory organs and that inducing CLDN5 expression is a novel therapeutic strategy against COVID-19. Overall design: The PET membrane to which HMVEC-L was adhered was mechanically recovered from the airway-on-a-chip, and then total RNA was collected and RNA-seq was performed.