SARS-CoV-2 infects cells of the human exocrine and endocrine pancreas and interferes with beta-cell function (preprint)

Preexisting diabetes increases the risk of a severe course of the pandemic coronavirus disease 2019 (COVID-19). Vice versa, exacerbations of a preexisting diabetes as well as new-onset diabetes have been reported upon SARS-CoV-2 infection. Thus, there is an imperative need to clarify whether human pancreatic endocrine cells organized within an islet of Langerhans are permissive for and affected by SARS-CoV-2 infection, and to elucidate the mechanisms underlying the development of diabetes upon COVID-19. Here, we (i) defined ACE2 and TMPRSS2 expression patterns in human pancreatic endocrine and exocrine cell types, (ii) employed human pancreatic islet cultures to demonstrate susceptibility to SARS-CoV-2 infection and to viral replication in β-cells, (iii) showed that SARS-CoV-2 attenuates glucose-stimulated insulin secretion, and (iv) tested remdesivir as eventually effective to prevent β-cell failure. In addition, we (v) visualized viral particles replicating in endocrine pancreatic cells and define their subcellular localization patterns via transmission electron microscopy, and finally (vi) present examples of cell type specific pancreatic infection patterns of COVID-19 deceased patients. Overall, our data demonstrate that SARS-CoV-2 can infect both the exocrine and endocrine compartments of the pancreas and can perturb β-cell integrity, which might lead to an increased risk for diabetes.

Best Practices for Human Milk Collection for COVID-19 Research (preprint)

In addition to providing life-giving nutrients and other substances to the breastfed infant, human milk can also represent a vehicle of pathogen transfer. As such, when an infectious disease outbreak, epidemic, or pandemic occurs – particularly when it is associated with a novel pathogen – the question will naturally arise as to whether the pathogen can be transmitted via breastfeeding. Until high-quality data are generated to answer this question, abandonment of breastfeeding due to uncertainty can result. The COVID-19 pandemic, which was in full swing at the time this document was written, is an excellent example of this scenario. During these times of uncertainty, it is critical for investigators conducting research to assess the possible transmission of pathogens via milk, whether by transfer through the mammary gland or contamination from respiratory droplets, skin, breast pumps, and milk containers, and/or close contact between mother and infant. To promote the most rigorous science, it is critical to outline optimal methods for milk collection, handling, storage, and analysis in these situations, and investigators should openly share their methods in published materials. Otherwise, the risks of inconsistent test results from pre-analytical and analytical variation, false positives, and false negatives are unacceptably high and the ability to provide public health guidance poor. Here we provide “best practices” for collecting human milk samples for COVID-19 research with the intention that this will also be a useful guide for future pandemics.