ABSTRACT
Objective: NA Background: There has been increasing recognition of neurologic symptoms in coronavirus disease 19 (COVID-19) patients. Pathophysiology underlying the encephalopathy induced by SARS-CoV-2 is yet to be elucidated, but immune system seems involved. Design/Methods: We analysed well characterised human Neurocovid samples (CSF and serum) for the presence of neurologically relevant auto-antibodies and pro-inflammatory cytokines. In addition, we investigated the molecular mechanisms underlying Covid19-related neurophysiological dysfunctions in disease-relevant neuronal models, such as rodent primary neuronal cultures and human neurons derived from induced pluripotent stem cells. Results: We gathered cerebrospinal fluid (CSF) from 13 COVID-19 patients showing central and peripheral neurological involvement. We collected CSF also from two patients affected by normal pressure hydrocephalus as controls. All CSF samples resulted negative for the presence of SARS-CoV-2 virus. We stained with CSF samples a human immortalized cell line, HEK293, over-expressing cleaved SARS-CoV-2 spike protein in not permeabilizing condition. We detected a strong immunoreactivity in specimens. We monitored the reactivity against spike along the time. To this aim, we collected CSF from one patient two months after the acute phase. We still observed a strong immuno-reactivity towards Spike-expressing HEK293 cells Having observed such an immunoreactivity profile, we aimed to identify the potential target(s) recognized by IgG present in the Neurocovid CSFs. We immobilized 50 ul of 2 CSF on agarose beads. Then we incubated the beads with different protein samples, lysate obtained from murine adult brain tissue, mouse cortical culture, membrane fraction prepared from cortical culture, and HEK293 cells. We eluted bound proteins and we analysed the samples by SDS-PAGE followed by silver staining. We excised and measured by MS/MS the protein bands appearing only in Neurocovid samples. Conclusions: Based on our findings we demonstrated that upon SARS-CoV-2 infection, the immune system generates anti-spike antibodies. These antibodies may recognize and attack neurological autoantigens due to molecular mimicry.