ABSTRACT
Background: Coronavirus disease 2019 (COVID-19) leads to peripheral and central disorders, frequently with neurological implications. Blood-brain barrier disruption (BBBd) has been hypothesized as a mechanisms in the acute phase. We tested whether markers of BBBd, brain injury and inflammation could help identify a blood signature for disease severity and neurological complications. Methods: Biomarkers of BBBd (MMP-9, GFAP), neuronal damage (NFL) and inflammation (PPIA, IL-10, TNF) were measured by SIMOA, AlphaLISA and ELISA, in two COVID-19 patient cohorts with high disease severity (ICU Covid; n=79) and neurological complications (NeuroCovid; n=78), and in two control groups with no COVID-19 history: healthy subjects (n=20) and patients with amyotrophic lateral sclerosis (ALS; n=51). Results: Biomarkers of BBBd and neuronal damage were high in COVID-19 patients, with levels similar to or higher than in ALS. NeuroCovid patients had lower levels of PPIA but higher levels of MMP-9 than ICU Covid patients. There was evidence of different temporal dynamics in ICU Covid compared to NeuroCovid patients with PPIA and IL-10 levels highest in ICU Covid patients in the acute phase. In contrast, MMP-9 was higher in the acute phase in NeuroCovid patients, with severity-dependency in the long term. We also found clear severity-dependency of NFL and GFAP. Conclusions: The overall picture points to an increased risk of neurological complications in patients with high levels of biomarkers of BBBd. Our observations may provide hints for therapeutic approaches mitigating BBBd to reduce the neurological damage in the acute phase and potential dysfunction in the long term.