Brain neuronal and glial damage during acute COVID-19 infection in absence of clinical neurological manifestations

No substantial neurocognitive impact of COVID-19 across ages and disease severity: a multicenter biomarker study of SARS-CoV-2 positive and negative adult and pediatric patients with acute respiratory tract infections

BACKGROUND

Compared to intensive care unit patients with SARS-CoV-2 negative acute respiratory tract infections, patients with SARS-CoV-2 are supposed to develop more frequently and more severely neurologic sequelae. Delirium and subsequent neurocognitive deficits (NCD) have implications for patients' morbidity and mortality. However, the extent of brain injury during acute COVID-19 and subsequent NCD still remain largely unexplored. Body-fluid biomarkers may offer valuable insights into the quantification of acute delirium, brain injury and may help to predict subsequent NCD following COVID-19.

METHODS

In a multicenter, observational case-control study, conducted across four German University Hospitals, hospitalized adult and pediatric patients with an acute COVID-19 and SARS-CoV-2 negative controls presenting with acute respiratory tract infections were included. Study procedures comprised the assessment of pre-existing neurocognitive function, daily screening for delirium, neurological examination and blood sampling. Fourteen biomarkers indicative of neuroaxonal, glial, neurovascular injury and inflammation were analyzed. Neurocognitive functions were re-evaluated after three months.

RESULTS

We enrolled 118 participants (90 adults, 28 children). The incidence of delirium [85 out of 90 patients (94.4%) were assessable for delirium) was comparable between patients with COVID-19 [16 out of 61 patients (26.2%)] and SARS-CoV-2 negative controls [8 out of 24 patients (33.3%); p > 0.05] across adults and children. No differences in outcomes as measured by the modified Rankin Scale, the Short-Blessed Test, the Informant Questionnaire on Cognitive Decline in the Elderly, and the pediatrics cerebral performance category scale were observed after three months. Levels of body-fluid biomarkers were generally elevated in both adult and pediatric cohorts, without significant differences between SARS-CoV-2 negative controls and COVID-19. In COVID-19 patients experiencing delirium, levels of GFAP and MMP-9 were significantly higher compared to those without delirium.

CONCLUSIONS

Delirium and subsequent NCD are not more frequent in COVID-19 as compared to SARS-CoV-2 negative patients with acute respiratory tract infections. Consistently, biomarker levels of brain injury indicated no differences between COVID-19 cases and SARS-CoV-2 negative controls. Our data suggest that delirium in COVID-19 does not distinctly trigger substantial and persistent subsequent NCD compared to patients with other acute respiratory tract infections.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT04359914; date of registration 24-APR 2020.

SARS-CoV-2 Infection-Dependent Modulation in Vital Components of the Serum Profile of Severely SARS-CoV-2 Infected Patients

Background

COVID-19 modulates many serological biomarkers during the progress of disease severity. The study aimed to determine COVID-19 severity-associated perturbance in the serum profile.

Methods

A retrospective study including COVID-19-positive individuals (n = 405) was accomplished. The serum profile of COVID-19 participants was mined from laboratory records. Severity-associated alteration in the serum profile was evaluated using Pearson correlation, regression, VCramer, Bayesian posterior VCramer, and bias factor using R-base-RStudio-version-3.3.0 with a significant cut-off of p < 0.05.

Results

Significantly different mean ± standard deviation (SD) (highly versus moderately severe) of C-reactive protein (CRP), ferritin, neutrophil-lymphocyte ratio (NLR), D-dimer, platelets, prothrombin time (PT), partial prothrombin time (PTT), troponin 1, lactate dehydrogenase (LDH), aspartate-aminotransferase (AST), alanine aminotransferase (ALT), and AST/ALT ratio was observed (p < 0.001). Highly severe COVID-19 associated with CRP, ferritin, NLR, in D-dimer, PT, PTT, troponin 1, AST/ALT ratio, AST and ALT (adjusted odds ratio (AOR): 1.346, 1.05, 1.46, 1.33, 1.42, 1.23, 4.07, 3.9, 1.24, 1.45, p < 0.001). CRP with ferritin (r = 0.743), NLR (r = 0.77), white blood cells (WBC) (r = 0.8), troponin1 with LDH (r = 0.757), and D-dimer with platelets (r = -0.81) were highly correlated. X2pearson (p < 0.001), VCramer (0.71), Bayesian-VCramer (0.7), and bias-factor (-125) for troponin 1 indicate the strong association of troponin 1 level and with COVID-19 severity. X2pearson (p < 0.001), VCramer (1), Bayesian-VCramer (0.98), and bias-factor (-266.3) for NLR exhibited a very strong association of pathologic conditions with the high severity of the disease.

Conclusion

These biomarkers of inflammation (CRP, Ferritin, NLR), coagulation disorders (D-dimer, PT, and PTT) cardiac abnormality (troponin 1), and liver injury (AST/ALT) could be crucial in low-medical resource settings as potential prognosticator/predictors of the COVID-19 severity and clinical outcomes. Moreover, the outcome of this study could be leveraged for the early prediction of disease severity during SARS-CoV or Middle East Respiratory Coronavirus (MERS-CoV) infection.

Neurofilament light chain and glial fibrillary acid protein levels are elevated in post-mild COVID-19 or asymptomatic SARS-CoV-2 cases

Given the huge impact of the COVID-19 pandemic, it appears of paramount importance to assess the cognitive effects on the population returning to work after COVID-19 resolution. Serum levels of neurofilament light chain (sNfL) and glial fibrillary acidic protein (sGFAP) represent promising biomarkers of neuro-axonal damage and astrocytic activation. In this cohort study, we explored the association between sNfL and sGFAP concentrations and cognitive performance in a group of 147 adult workers with a previous asymptomatic SARS-CoV-2 infection or mild COVID-19, one week and, in 49 of them, ten months after SARS-Cov2 negativization and compared them to a group of 82 age and BMI-matched healthy controls (HCs). sNfL and sGFAP concentrations were assessed using SimoaTM assay Neurology 2-Plex B Kit. COVID-19 patients were interviewed one-on-one by trained physicians and had to complete a list of questionnaires, including the Cognitive Failure Questionnaire (CFQ). At the first assessment (T0), sNfL and sGFAP levels were significantly higher in COVID-19 patients than in HCs (p < 0.001 for both). The eleven COVID-19 patients with cognitive impairment had significantly higher levels of sNfL and sGFAP than the others (p = 0.005 for both). At the subsequent follow-up (T1), sNfL and sGFAP levels showed a significant decrease (median sNfL 18.3 pg/mL; median sGFAP 77.2 pg/mL), although they were still higher than HCs (median sNfL 7.2 pg/mL, median sGFAP 63.5 pg/mL). Our results suggest an ongoing damage involving neurons and astrocytes after SARS-Cov2 negativization, which reduce after ten months even if still evident compared to HCs.

Systematic review and evidence gap mapping of biomarkers associated with neurological manifestations in patients with COVID-19

OBJECTIVE

This study aimed to synthesize the existing evidence on biomarkers related to coronavirus disease 2019 (COVID-19) patients who presented neurological events.

METHODS

A systematic review of observational studies (any design) following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines and the Cochrane Collaboration recommendations was performed (PROSPERO: CRD42021266995). Searches were conducted in PubMed and Scopus (updated April 2023). The methodological quality of nonrandomized studies was assessed using the Newcastle‒Ottawa Scale (NOS). An evidence gap map was built considering the reported biomarkers and NOS results.

RESULTS

Nine specific markers of glial activation and neuronal injury were mapped from 35 studies published between 2020 and 2023. A total of 2,237 adult patients were evaluated in the included studies, especially during the acute phase of COVID-19. Neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) biomarkers were the most frequently assessed (n = 27 studies, 77%, and n = 14 studies, 40%, respectively). Although these biomarkers were found to be correlated with disease severity and worse outcomes in the acute phase in several studies (p < 0.05), they were not necessarily associated with neurological events. Overall, 12 studies (34%) were judged as having low methodological quality, 9 (26%) had moderate quality, and 9 (26%) had high quality.

CONCLUSIONS

Different neurological biomarkers in neurosymptomatic COVID-19 patients were identified in observational studies. Although the evidence is still scarce and conflicting for some biomarkers, well-designed longitudinal studies should further explore the pathophysiological role of NfL, GFAP, and tau protein and their potential use for COVID-19 diagnosis and management.

Associations between COVID-19 and putative markers of neuroinflammation: A diffusion basis spectrum imaging study

COVID-19 remains a significant international public health concern. Yet, the mechanisms through which symptomatology emerges remain poorly understood. While SARS-CoV-2 infection may induce prolonged inflammation within the central nervous system, the evidence primarily stems from limited small-scale case investigations. To address this gap, our study capitalized on longitudinal UK Biobank neuroimaging data acquired prior to and following COVID-19 testing (N=416 including n=224 COVID-19 cases; Mage=58.6). Putative neuroinflammation was assessed in gray matter structures and white matter tracts using non-invasive Diffusion Basis Spectrum Imaging (DBSI), which estimates inflammation-related cellularity (DBSI-restricted fraction; DBSI-RF) and vasogenic edema (DBSI-hindered fraction; DBSI-HF).We hypothesized that COVID-19 case status would be associated with increases in DBSI markers after accounting for potential confound (age, sex, race, body mass index, smoking frequency, and data acquisition interval) and multiple testing. COVID-19 case status was not significantly associated with DBSI-RF (|β|'s<0.28, pFDR >0.05), but with greater DBSI-HF in left pre- and post-central gyri and right middle frontal gyrus (β's>0.3, all pFDR=0.03). Intriguingly, the brain areas exhibiting increased putative vasogenic edema had previously been linked to COVID-19-related functional and structural alterations, whereas brain regions displaying subtle differences in cellularity between COVID-19 cases and controls included regions within or functionally connected to the olfactory network, which has been implicated in COVID-19 psychopathology. Nevertheless, our study might not have captured acute and transitory neuroinflammatory effects linked to SARS-CoV-2 infection, possibly due to symptom resolution before the imaging scan. Future research is warranted to explore the potential time- and symptom-dependent neuroinflammatory relationship with COVID-19.

Enteric nervous system as a target and source of SARS-CoV-2 and other viral infections

Coronavirus disease 2019 (COVID-19) has been demonstrated to affect several systems of the human body, including the gastrointestinal and nervous systems. The enteric nervous system (ENS) is a division of the autonomic nervous system that extends throughout the gut, regulates gastrointestinal function, and is therefore involved in most gut dysfunctions, including those resulting from many viral infections. Growing evidence highlights enteric neural cells and microbiota as important players in gut inflammation and dysfunction. Furthermore, the ENS and gastrointestinal immune system work together establishing relevant neuroimmune interactions during both health and disease. In recent years, gut-driven processes have also been implicated as players in systemic inflammation and in the initiation and propagation of several central nervous system pathologies, which seem to be hallmarks of COVID-19. In this review, we aim to describe evidence of the gastrointestinal and ENS infection with a focus on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We discuss here viral-induced mechanisms, neuroplasticity, and neuroinflammation to call attention to the enteric neuroglial network as a nervous system with a sensitive and crucial position to be not only a target of the new coronavirus but also a way in and trigger of COVID-19-related symptoms.