Chemokine CXCL12/CXCR4 system and synthetic cathinones

Human death in persons infected with SARS-CoV-2 (the virus responsible for the covid-19pandemic) is caused by barriers dysfunction (i.e. in the pulmonary system). Angiotensin-converting enzyme 2 (ACE2) has been identified as a functional receptor of SARS-CoV-2,similarly to other coronaviruses. Surface expression of ACE2 protein was found on lungalveolar epithelial cells and enterocytes of the small intestine. In brain, ACE2 is expressed onendothelial cells, a major component of blood-brain barrier (BBB). We propose to perform aseries of studies to assess the impact of SARS-CoV-2 spike protein on BBB function in thepresence of cocaine as an extension of our funded research on psychostimulants and theCXCL12/CXCR4 chemokine system. First, a comprehensive series of experiments on theimpact of SARS-CoV-2 spike protein in the presence and absence of cocaine on brainmicrovascular endothelial cells will be performed in vitro to inform on the cellular and molecularmechanism involved in altered BBB function. Included in the analysis will be measurements ofcytosolic Ca2+ levels, mitochondrial reactive oxygen species, tight junctions and cytoskeletalproteins. Second, integrated fluorescence microscopy will be used to visualize and quantifychanges in BBB permeability in real time in awake rats after exposure to SARS-CoV-2 spikeprotein. The impact of acute and chronic administration of cocaine on BBB function in thesetting of SARS-CoV-2 spike protein will be determined. Finally, brain regions from ratsexposed to cocaine and the spike protein will be examined for levels of pro-inflammatorycytokines and chemokines. Taken together, this series of experiments will provide novelinformation about the effect of the spike protein on BBB function and neuroinflammation, and itspotential interactions with cocaine. We hypothesize that chronic cocaine exposure willexacerbate the negative impact of SARS-CoV-2 spike protein on BBB integrity and increasepro-inflammatory mediators in the CNS. These studies will provide the necessary groundwork toembark on a larger study of the impact of SARS-CoV-2 on cocaine behaviors and toxicities.