Neurologic sequalae of COVID-19 are determined by immunologic imprinting from previous Coronaviruses. (preprint)

Coronavirus disease 2019 (COVID-19), which is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), remains a global public health emergency. Although SARS-CoV-2 is primarily a respiratory pathogen, extra-respiratory organs, including the central nervous system (CNS), can also be affected. Neurologic symptoms have been observed not only during acute SARS-CoV-2 infection, but also at distance from respiratory disease, also known as long-COVID or neurological post-acute sequelae of COVID-19 (neuroPASC). The pathogenesis of neuroPASC is not well understood, but hypotheses include SARS-CoV-2-induced immune dysfunctions, hormonal dysregulations, and persistence of SARS-CoV-2 reservoirs. In this study, we used a high throughput systems serology approach to dissect the humoral response to SARS-CoV-2 (and other common Coronaviruses - 229E, HKU1, NL63, OC43) in the serum and cerebrospinal fluid (CSF) from 112 infected individuals who developed or did not develop neuroPASC. Unique SARS-CoV-2 humoral profiles were observed in the CSF of neuroPASC. All antibody isotypes (IgA, IgM, IgA) and subclasses (IgA1-2; IgG1-4) were detected in serum, whereas CSF was characterized by focused IgG1 (and absence of IgM). These data argue in favor of compartmentalized brain-specific responses against SARS-CoV-2 through selective transfer of antibodies from the serum to the CSF across the blood-brain-barrier, rather than intrathecal synthesis, where more diversity in antibody classes/subclasses would be expected. Moreover, compared to individuals who did not develop post-acute neurological complications following infection (n=94), those with neuroPASC (n=18) exhibited attenuated systemic antibody responses against SARS-CoV-2, characterized by decreased capacity to activate antibody-dependent complement deposition (ADCD), NK cell activation (ADNKA) and to bind Fc{gamma} receptors. However, surprisingly, neuroPASC showed significantly expanded antibody responses to other common Coronaviruses, including 229E, HKU1, NL63, and OC43. This biased humoral activation across coronaviruses was particularly enriched in neuroPASC individuals with poor outcome, suggesting an original antigenic sin (or immunologic imprinting), where pre-existing immune responses against related viruses shape the response to current infection, as a key prognostic biomarker of neuroPASC disease. Overall, these findings point to a pathogenic role for compromised anti-SARS-CoV-2 responses in the CSF, likely resulting in incomplete virus clearance from the brain and persistent neuroinflammation, in the development of post-acute neurologic complications of SARS-CoV-2 infection.

Antibody response to BTN162b2 mRNA vaccination in naïve versus SARS-CoV-2 infected subjects with and without waning immunity (preprint)

We profiled antibody responses in a cohort of recipients of the BTN162b2 mRNA vaccine who were either immunologically naïve (n=50) or had been previously infected with SARS-CoV-2 (n=51). Of the previously infected, 25 and 26 were infected during the first and second pandemic waves in Italy, respectively; the majority of those from the first wave had corresponding waning immunity with low to undetectable levels of anti-S antibodies and low anti-N antibodies. We observed in recipients who had been previously infected that spike-specific IgG and pseudovirus neutralization titers were rapidly recalled by a single vaccine dose to higher levels than those in naïve recipients after the second vaccine dose, irrespective of waning immunity. In all recipients, a single vaccine dose was sufficient to induce a potent IgA response that was not associated with serum neutralization titers.

The clinical spectrum of encephalitis in COVID-19 disease: the ENCOVID multicentre study (preprint)

Background: Several preclinical and clinical investigations have argued for nervous system involvement in SARS-CoV-2 infection. Some sparse case reports have described various forms of encephalitis in COVID-19 disease, but very few data have focused on clinical presentations, clinical course, response to treatment and outcomes yet. Objective: to describe the clinical phenotype, laboratory and neuroimaging findings of encephalitis associated with SARS-CoV-2 infection, their relationship with respiratory function and inflammatory parameters and their clinical course and response to treatment. Design: The ENCOVID multicentre study was carried out in 13 centres in northern Italy between February 20th and May 31st, 2020. Only patients with altered mental status and at least two supportive criteria for encephalitis with full infectious screening, CSF, EEG, MRI data and a confirmed diagnosis of SARS-CoV-2 infection were included. Clinical presentation and laboratory markers, severity of COVID-19 disease, response to treatment and outcomes were recorded. Results: Out of 45 cases screened, twenty-five cases of encephalitis positive for SARS-CoV-2 infection with full available data were included. The most common symptoms at onset were delirium (68%), aphasia/dysarthria (24%) and seizures (24%). CSF showed hyperproteinorrachia and/or pleocytosis in 68% of cases whereas SARS-CoV-2 RNA by RT-PCR resulted negative. Based on MRI, cases were classified as ADEM (n=3), limbic encephalitis (LE, n=2), encephalitis with normal imaging (n=13) and encephalitis with MRI alterations (n=7). ADEM and LE cases showed a delayed onset compared to the other encephalitis (p=0.001) and were associated with previous more severe COVID-19 respiratory involvement. Patients with MRI alterations exhibited worse response to treatment and final outcomes compared to other encephalitis. Conclusions and relevance: We found a wide clinical spectrum of encephalitis associated with COVID19 infection, underlying different pathophysiological mechanisms. Response to treatment and final outcome strongly depended on specific CNS-manifestations.

COVID-19 impact on consecutive neurological patients admitted to the emergency department (preprint)

ObjectiveAim of this study was to analyse the impact of COVID-19 on clinical and laboratory findings and outcome of neurological patients consecutively admitted to the emergency department (ED) of a tertiary hub center. MethodsAll adult patients consecutively admitted to the ED for neurological manifestations from February 20th through April 30th 2020 at Spedali Civili of Brescia entered the study. Demographic, clinical, and laboratory data were extracted from medical records and compared between patients with and without COVID-19. ResultsOut of 505 consecutively patients evaluated at ED with neurological symptoms, 147 (29.1%) tested positive for SARS-CoV-2. These patients displayed at triage higher values of CRP, AST, ALT, and fibrinogen but not lymphopenia (p<0.05). They were older (73.1 {+/-} 12.4 vs 65.1 {+/-} 18.9 years, p=0.001) had higher frequency of stroke (34.7% vs 29.3%), encephalitis/meningitis (9.5% vs 1.9%) and delirium (16.3% vs 5.0%). Compared to patients without COVID, they were more frequently hospitalized (91.2% vs 69.3%, p<0.0001) and showed higher mortality rates (29.7% vs 1.8%, p<0.0.001) and discharge disability, independently from age. ConclusionsCOVID-19 impacts on clinical presentation of neurological disorders, with higher frequency of stroke, encephalitis and delirium, and was strongly associated with increased hospitalisation, mortality and disability.