ABSTRACT
We analyzed the ability of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) itself and SARS-CoV-2-IgG immune complexes to trigger human monocyte necroptosis. SARS-CoV-2 was able to induce monocyte necroptosis dependently of MLKL activation. Necroptosis-associated proteins (RIPK1, RIPK3 and MLKL) were involved in SARS-CoV-2N1 gene expression in monocytes. SARS-CoV-2 immune complexes promoted monocyte necroptosis in a RIPK3- and MLKL-dependent manner, and Syk tyrosine kinase was necessary for SARS-CoV-2 immune complex-induced monocyte necroptosis, indicating the involvement of Fcγ receptors on necroptosis. Finally, we provide evidence that elevated LDH levels as a marker of lytic cell death are associated with COVID-19 pathogenesis.
Subject(s)
Antigen-Antibody Complex , COVID-19 , Humans , Antigen-Antibody Complex/metabolism , SARS-CoV-2 , Protein Kinases/metabolism , Monocytes , Necroptosis , Receptor-Interacting Protein Serine-Threonine Kinases/genetics , Receptor-Interacting Protein Serine-Threonine Kinases/metabolismABSTRACT
Clinical and experimental data indicate that severe acute respiratory syndrome coronavirus (SARS-CoV)-2 infection is associated with significant changes in the composition and function of intestinal microbiota. However, the relevance of these effects for SARS-CoV-2 pathophysiology is unknown. In this study, we analyzed the impact of microbiota depletion after antibiotic treatment on the clinical and immunological responses of K18-hACE2 mice to SARS-CoV-2 infection. Mice were treated with a combination of antibiotics (kanamycin, gentamicin, metronidazole, vancomycin, and colistin, Abx) for 3 days, and 24 h later, they were infected with SARS-CoV-2 B lineage. Here, we show that more than 80% of mice succumbed to infection by day 11 post-infection. Treatment with Abx had no impact on mortality. However, Abx-treated mice presented better clinical symptoms, with similar weight loss between infected-treated and non-treated groups. We observed no differences in lung and colon histopathological scores or lung, colon, heart, brain and kidney viral load between groups on day 5 of infection. Despite some minor differences in the expression of antiviral and inflammatory markers in the lungs and colon, no robust change was observed in Abx-treated mice. Together, these findings indicate that microbiota depletion has no impact on SARS-CoV-2 infection in mice.
Subject(s)
COVID-19 Drug Treatment , Microbiota , Angiotensin-Converting Enzyme 2 , Animals , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/therapeutic use , Disease Models, Animal , Melphalan , Mice , Mice, Transgenic , Peptidyl-Dipeptidase A/metabolism , SARS-CoV-2 , gamma-GlobulinsABSTRACT
The use of in vitro methods of infecting cell lines to test new treatments for SARS-CoV-2 does not always recapitulate the real context of the infection, and mouse models for SARS-CoV-2 infection are limited. Here we describe a novel ex vivo approach by collecting, isolating, and culturing nasal epithelial cells obtained from patients with COVID-19. This technique allows us to study immune responses and test new treatments directly on cells from patients naturally infected with SARS-CoV-2.