Wyder, M. | bioRxiv Science

bioRxiv2023

Prenatal SARS-CoV-2 infection alters postpartum human milk-derived extracellular vesicles

Human milk-derived extracellular vesicles (HMEVs) are crucial functional components in breast milk, contributing to infant health and development. Maternal conditions could affect HMEV cargos; however, the impact of SARS-CoV-2 infection on HMEVs remains unknown. This study evaluated the influence of SARS-CoV-2 infection during pregnancy on postpartum HMEV molecules. Milk samples (9 prenatal SARS-CoV-2 vs. 9 controls) were retrieved from the IMPRINT birth cohort. After defatting and casein micelle disaggregation, 1 mL milk was subjected to a sequential process of centrifugation, ultrafiltration, and qEV-size exclusion chromatography. Particle and protein characterizations were performed following the MISEV2018 guidelines. EV lysates were analyzed through proteomics and miRNA sequencing, while the intact EVs were biotinylated for surfaceomic analysis. Multi-Omics was employed to predict HMEV functions associated with prenatal SARS-CoV-2 infection. Demographic data between the prenatal SARS-CoV-2 and control groups were similar. The median duration from maternal SARS-CoV-2 test positivity to milk collection was 3 months (range: 1-6 months). Transmission electron microscopy showed the cup-shaped nanoparticles. Nanoparticle tracking analysis demonstrated particle diameters of <200 nm and yields of >1e11 particles from 1 mL milk. Western immunoblots detected ALIX, CD9 and HSP70, supporting the presence of HMEVs in the isolates. Thousands of HMEV cargos and hundreds of surface proteins were identified and compared. Multi-Omics predicted that mothers with prenatal SARS-CoV-2 infection produced HMEVs with enhanced functionalities involving metabolic reprogramming and mucosal tissue development, while mitigating inflammation and lower EV transmigration potential. Our findings suggest that SARS-CoV-2 infection during pregnancy boosts mucosal site-specific functions of HMEVs, potentially protecting infants against viral infections. Further prospective studies should be pursued to reevaluate the short- and long-term benefits of breastfeeding in the post-COVID era.

systems biology↗

bioRxiv2019

Cell-specific targeting by Clostridium perfringens β-toxin unraveled: the role of CD31 as the toxin receptor.

Clostridium perfringens {beta}-toxin (CPB) is a highly active hemolysin {beta}-pore forming toxin and the essential virulence factor for a severe, necro-hemorrhagic enteritis in animals and humans. In vivo and in vitro it exerts a remarkable cell type specificity towards endothelial cells, platelets and some leucocytic cell lines. The target cell specificity of CPB is, however, poorly understood and a receptor explaining this selective toxicity has not been identified. This has hampered further research into the pathogenesis of C. perfringens type C induced enteritis. Here we identify Platelet Endothelial Cell Adhesion Molecule-1 (CD31 or PECAM-1) as the specific membrane receptor for CPB on endothelial cells. CD31 expression is essential for CPB toxicity in endothelial cells and lethality in mice and sufficient to render previously resistant cells highly susceptible to the toxin. We further demonstrate, that the extracellular membrane proximal Ig6 domain of CD31 is required for the interaction with CPB and that expression of CD31 corresponds with the specificity of the toxin towards cultured cell lines. Our results thus provide an explanation for the cell type specificity of CPB and can be linked to the characteristic lesions observed a devastating enteric disease in animals and humans.

molecular biology↗