Encephalopathies associated with severe COVID-19 present specific neurovascular unit alterations without evidence of strong neuroinflammation

Coronavirus disease (COVID-19) has been associated with a large variety of neurological disorders. However the mechanisms underlying these neurological complications remain elusive. In this study we aimed at determining whether neurological symptoms were caused by SARS-CoV-2 direct infection or by either systemic or local pro-inflammatory mediators.We checked for SARS-CoV-2 RNA by RT-qPCR, SARS-CoV-2-specific antibodies and for 49 cytokines/chemokines/growth factors (by Luminex) in the cerebrospinal fluids (CSF) +/-sera of a cohort of 22 COVID-19 patients with neurological presentation and 55 neurological control patients (inflammatory [IND], non-inflammatory [NIND], multiple sclerosis [MS]).We detected SARS-CoV-2 RNA and virus-specific antibodies in the CSF of 0/22 and 10/21 COVID-19 patients, respectively. Of the four categories of tested patients, the CSF of IND exhibited the highest level of cytokines, chemokines and growth factors. In contrast, COVID-19 patients did not present overall upregulation of inflammatory mediators in the CSF. However, the CSF of patients with severe COVID-19 (ICU patients) exhibited higher concentrations of CCL2, CXCL8, and VEGF-A in the CSF than patients with a milder form of COVID-19. In addition, we could show that intrathecal CXCL8 synthesis was linked to an elevated barrier index and correlated to the increase of peripheral inflammation (serum HGF and CXCL10).Our results point at an absence of massive SARS-CoV-2 infection or inflammation of the central nervous system, but highlight a specific impairment of the neurovascular unit linked to intrathecal production of CXCL8.