A Quantum Dot Biomimetic for SARS-CoV-2 to Interrogate Dysregulation of the Neurovascular Unit Relevant to Brain Inflammation

Despite limited evidence for competent infection and viral replication of SARS-CoV-2 in the central nervous system (CNS), neurologic dysfunction is a common post-acute medical condition reported in "recovered" COVID-19 patients. To identify a potential noninfectious route for SARS-CoV-2-mediated neurological damage, we constructed colloidal nanocrystal quantum dots linked to micelles decorated with spike protein (COVID-QDs) as a biomimetic to interrogate how blood-brain barrier (BBB) dysregulation may subsequently induce neuroinflammation in the absence of infection. In transwell co-culture of endothelial bEnd.3 monolayers and primary neuroglia, we exposed only the bEnd.3 monolayers to COVID-QDs and examined by fluorescence microscopy whether such treatment led to (i) increased inflammation and leakage across the bEnd.3 monolayers, (ii) permeability of the COVID-QDs across the monolayers, and (iii) induction of neuroinflammation in neuroglial cultures. The results of our study provide evidence of neuroinflammatory hallmarks in cultured neurons and astrocytes without direct exposure to SARS-CoV-2-like nanoparticles. Additionally, we found that pre-treatment of our co-cultures with a small-molecule, broad-spectrum inhibitor of mixed lineage and leucine rich repeat kinases led to reversal of the observed dysregulation in endothelial monolayers and resulted in neuroglial protection. The results reported here may serve to guide future studies into the potential mechanisms by which SARS-CoV-2 mediates neurologic dysfunction.