Airway epithelial cells and macrophages trigger IL-6-CD95/CD95L axis and mediate initial immunopathology of COVID-19.

Airway epithelial cells (AEC) infected with SARS-CoV-2 may drive the dysfunction of macrophages during COVID-19. We hypothesized that the direct interaction of AEC with macrophages mediated by CD95/CD95L or indirect interaction mediated by IL-6 signaling are key steps for the COVID-19 severe acute inflammation. The interaction of macrophages with apoptotic and infected AEC increased CD95 and CD163 expression, and induced macrophage death.

Neutrophil Virucidal Activity Against SARS-CoV-2 Is Mediated by Neutrophil Extracellular Traps.

Background: Inflammation in the lungs and other vital organs in COVID-19 is characterized by the presence of neutrophils and a high concentration of neutrophil extracellular traps (NETs), which seems to mediate host tissue damage. However, it is not known whether NETs could have virucidal activity against SARS-CoV-2.

Methods: We investigated whether NETs could prevent SARS-CoV-2 replication in neutrophils and epithelial cells and what the consequence of NETs degradation would be in K18-humanized ACE2 transgenic mice infected with SARS-CoV-2.

The TIGIT T regulatory cells subset associates with nosocomial infection and fatal outcome in COVID-19 patients under mechanical ventilation.

The TIGITFOXP3Treg subset (TIGITTregs) exerts robust suppressive activity on cellular immunity and predisposes septic individuals to opportunistic infection. We hypothesized that TIGITTregs could play an important role in intensifying the COVID-19 severity and hampering the defense against nosocomial infections during hospitalization. Herein we aimed to verify the association between the levels of the TIGITTregs with the mechanical ventilation requirement, fatal outcome, and bacteremia during hospitalization.

Gasdermin-D activation by SARS-CoV-2 triggers NET and mediate COVID-19 immunopathology.

Background: The release of neutrophil extracellular traps (NETs) is associated with inflammation, coagulopathy, and organ damage found in severe cases of COVID-19. However, the molecular mechanisms underlying the release of NETs in COVID-19 remain unclear.

Objectives: We aim to investigate the role of the Gasdermin-D (GSDMD) pathway on NETs release and the development of organ damage during COVID-19.

SARS-CoV-2-triggered neutrophil extracellular traps mediate COVID-19 pathology.

Severe COVID-19 patients develop acute respiratory distress syndrome that may progress to cytokine storm syndrome, organ dysfunction, and death. Considering that neutrophil extracellular traps (NETs) have been described as important mediators of tissue damage in inflammatory diseases, we investigated whether NETs would be involved in COVID-19 pathophysiology. A cohort of 32 hospitalized patients with a confirmed diagnosis of COVID-19 and healthy controls were enrolled.

Molecular characterization of LC3-associated phagocytosis reveals distinct roles for Rubicon, NOX2 and autophagy proteins.

LC3-associated phagocytosis (LAP) is a process wherein elements of autophagy conjugate LC3 to phagosomal membranes. We characterize the molecular requirements for LAP, and identify Rubicon as being required for LAP but not autophagy. Rubicon is recruited to LAPosomes and is required for the activity of a Class III PI(3)K complex containing UVRAG but lacking ATG14 and Ambra1.