Cardiovascular symptoms of PASC are associated with trace-level cytokines that affect the function of human pluripotent stem cell derived cardiomyocytes (preprint)

Globally, over 65 million individuals are estimated to suffer from post-acute sequelae of COVID-19 (PASC). A large number of individuals living with PASC experience cardiovascular symptoms (i.e. chest pain and heart palpitations) (PASC-CVS). The role of chronic inflammation in these symptoms, in particular in individuals with symptoms persisting for >1 year after SARS-CoV-2 infection, remains to be clearly defined. In this cross-sectional study, blood samples were obtained from three different sites in Australia from individuals with i) a resolved SARS-CoV-2 infection (and no persistent symptoms i.e. Recovered), ii) individuals with prolonged PASC-CVS and iii) SARS-CoV-2 negative individuals. Individuals with PASC-CVS, relative to Recovered individuals, had a blood transcriptomic signature associated with inflammation. This was accompanied by elevated levels of pro-inflammatory cytokines (IL-12, IL-1beta;, MCP-1 and IL-6) at approximately 18 months post-infection. These cytokines were present in trace amounts, such that they could only be detected with the use of novel nanotechnology. Importantly, these trace-level cytokines had a direct effect on the functionality of pluripotent stem cell derived cardiomyocytes in vitro. This effect was not observed in the presence of dexamethasone. Plasma proteomics demonstrated further differences between PASC-CVS and Recovered patients at approximately 18 months post-infection including enrichment of complement and coagulation associated proteins in those with prolonged cardiovascular symptoms. Together, these data provide a new insight into the role of chronic inflammation in PASC-CVS and present nanotechnology as a possible novel diagnostic approach for the condition.

Endothelial cells elicit a pro-inflammatory response to SARS-COV-2 without productive viral infection (preprint)

Thrombotic and microvascular complications are frequently seen in deceased COVID-19 patients, suggesting that vascular pathology is a major driver of severe disease. However, whether this is caused by direct viral infection of the endothelium or inflammation-induced endothelial activation remains highly contentious. What role the endothelium plays in viral amplification and inflammation thus remains a key unresolved question in the pathogenesis of SARS-CoV-2. Here, we use patient autopsy samples, primary human endothelial cells and an in vitro model of the pulmonary epithelial-endothelial cell barrier to show that primary human endothelial cells express the SARS-CoV-2 receptor ACE2 and the protease TMPRSS2, albeit at low levels. Accordingly, when present in a sufficiently high concentration, SARS-CoV-2 can enter primary human endothelial cells from either the apical or basolateral surface. Whilst inducing an inflammatory response, this is not a productive infection. We further demonstrate that in a co-culture model of the pulmonary epithelial-endothelial barrier, endothelial cells are not infected with SARS-CoV-2. They do however, sense and respond to an infection in the adjacent epithelial cells, resulting in the induction of a pro-inflammatory response. Taken together, these data suggest that in vivo, endothelial cells are unlikely to be infected with SARSCoV-2 and that infection is only likely to occur if the adjacent pulmonary epithelium is denuded (basolateral infection) or a high viral load is present in the blood (apical infection). In such a scenario, whilst SARS-CoV-2 infection of the endothelium can occur, it does not contribute to viral amplification. However, endothelial cells are still likely to play a key role in SARS-CoV-2 pathogenesis by sensing and mounting a pro-inflammatory response to SARS-CoV-2.