ABSTRACT
Background: It is unknown whether individuals with neurological post-acute sequelae of COVID-19 (NeuroPASC) display altered levels of neuroimmune activity or neuronal injury. Method(s): Participants with new or worsened neurologic symptoms at least 3 months after laboratory-confirmed COVID-19 were enrolled in The COVID Mind Study at Yale. Never COVID controls (no history of COVID-19;nucleocapsid (N) antibody negative) were pre-pandemic or prospectively enrolled volunteers. CSF and plasma were assessed for neopterin and for IL-1beta, IL-1RA, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12p40, IL-12p70, IL-13, MCP-1, TNFalpha by bead-based multiplex assay;and for anti-SARS-CoV-2 N antibodies by Luminex-based multiplex assay in technical replicate, normalized against bovine serum albumin conjugated beads. Plasma concentrations of D-dimer, C-reactive protein, neurofilament light chain (NFL), and glial fibrillary acid protein (GFAP) were measured using high-sensitivity immunoassays. Group comparisons used non-parametric tests. Result(s): NeuroPASC participants (n=38) were studied 329 (median) days (range 81-742) after first positive test for acute COVID-19. Cognitive impairment (84%) and fatigue (82%) were the most frequent post-COVID symptoms. NeuroPASC and controls (n=22) were median 49 vs 52 yrs old (p=0.9), 74% vs 32% female (p< 0.001), 76% vs 23% white race (p< 0.001), and 6% vs 57% smokers (p< 0.001). CSF white blood cells/mL, CSF protein, and serum:CSF albumin ratio were normal in both groups. CSF TNFalpha (0.66 vs 0.55 pg/ul) and plasma IL12p40 were higher (103.3 vs 42.7);and MCP-1 (503 vs 697 pg/ul) and IL-6 (1.32 vs 1.84 pg/ul;p < 0.05 for IL-6) were lower in NeuroPASC vs controls (p< 0.05);but none of these differences were significant after adjusting for multiple comparisons. Plasma GFAP was elevated in NeuroPASC vs controls (54.4 vs 42.3 pg/ml;adjusted p< 0.03). There were no differences in the other biomarkers tested. 10/31 and 7/31 NeuroPASC had anti-N antibodies in CSF and plasma, respectively. Conclusion(s): When comparing NeuroPASC to never COVID controls, we found no evidence of neuroinflammation (normal CSF cell count, inflammatory cytokines) or blood-brain barrier dysfunction (normal albumin ratio), and no support for ongoing neuronal damage (normal plasma NFL). Future studies should include better gender and race matched controls and should explore the significance of a persistent CNS humoral immune response to SARS-CoV-2 and elevated plasma GFAP after COVID-19. (Figure Presented).
ABSTRACT
Background: The pathogenesis of neuropsychiatric symptoms persisting months after acute SARS-CoV-2 infection is poorly understood. We examined clinical and laboratory parameters in participants with post-acute COVID-19 neuropsychiatric symptom to assess for systemic and nervous system immune perturbations. Methods: Participants with a history of laboratory confirmed COVID-19 and ongoing neurologic symptoms were enrolled in an observational study that collected medical history;detailed post-COVID symptom survey;and paired cerebrospinal fluid (CSF) and blood. In addition to standard clinical labs, neopterin and anti-SARS-CoV-2 antibodies (anti-spike, RBD, and nucleocapsid) were measured by ELISA. Non-parametric tests were used to compare CSF and blood findings between the post-COVID participants and pre-COVID-19 era healthy controls. Results: Post-COVID participants (n=27) and controls (n=21) were similar in age (median 51 and 46 years), but there was a greater proportion of females (67% vs 24%;p=0.004) and white participants in the post-COVID cohort (63% vs 24%;p=0.04). The post-COVID study visit was a median of 264 days (IQR 59-332) after acute COVID-19 symptom onset. 35% were hospitalized during their acute illness;12% required intensive care. 33% had previously been treated with medications for mental health conditions. The most frequent neuropsychiatric symptoms were cognitive impairment (67%), mood symptoms (67%), headache (56%), and neuropathy (41%). Blood c-reactive protein, T cell count, and T cell subset frequency (CD4% and CD8%) were similar between groups, while D-dimer was higher in the post-COVID cohort (median 0.48 vs 0.27 mg/L;p = 0.019) (Figure). CSF WBC, protein, neopterin, and CSF/blood albumin ratio were similar between the groups;the frequency of CSF lymphocytes was lower in the post-COVID cohort (p = 0.05) (Figure 1). Antibodies against at least one SARS-CoV-2 antigen were detected in 7/10 CSF and 8/9 blood samples in the post-COVID CSF (antibody reactivity range 1.5 to 55-fold greater than to control antigens). Conclusion: In this small cohort of post-COVID participants with neurologic symptoms, we found limited differences in CSF and blood markers when compared to pre-pandemic healthy controls. Deeper immunophenotyping in a larger number of participants may provide greater insight into subtle differences. The presence of anti-SARS-CoV-2 antibodies in CSF months after acute infection warrants further investigation.
ABSTRACT
Background: One third of COVID-19 patients develop significant neurological symptoms, yet SARS-CoV-2 is rarely detected in central nervous system (CNS) tissue, suggesting a potential role for parainfectious processes, including neuroimmune responses. Methods: We examined immune parameters in CSF and blood samples from a cohort of hospitalized patients with COVID-19 and significant neurological complications (n=6), compared to SARS-CoV-2 uninfected controls (Fig1A). Immune cells were characterized by single cell RNA and repertoire sequencing. Intrathecal antibodies were assessed for anti-viral and auto-reactivity by ELISA, mouse brain immunostaining, phage display, and IP-MS. Results: Through single cell and parallel cytokine analyses of CSF and paired plasma, we found divergent T cell responses in the CNS compartment, including increased levels of IL-1B and IL-12-associated innate and adaptive immune cell activation (Fig1B). We found evidence of clonal expansion of B cells in the CSF, with B cell receptor sequences that were unique from those observed in peripheral blood B cells (Fig1C), suggesting a divergent intrathecal humoral response to SARS-CoV-2. Indeed, all COVID-19 cases examined had anti-SARS-antibodies. Next, we directly examined whether CSF resident antibodies targeted self-antigens and found a significant burden of CNS autoimmunity, with the CSF from most patients recognizing neural self-antigens. COVID-19 CSF produced immunoreactive staining of specific anatomic regions of the brain including cortical neurons, olfactory bulb, thalamus, and cerebral vasculature. Finally, we produced a panel of monoclonal antibodies from patients' CSF and peripheral blood, and show that these target both anti-viral and anti-neural antigens-including one CSF-derived mAb specific for the spike protein that also recognizes neural tissue (Fig1D). Conclusion: This immune survey reveals evidence of a compartmentalized and self-reactive immune response in the CNS in COVID-19 patients with neurologic symptoms. We identified both innate and adaptive anti-viral immune responses, as well as humoral autoimmunity that appears to be unique to the CNS during SARS-CoV-2 infection. These data suggest a potential role for autoimmunity in contributing to neurological symptoms, and merit further investigation to the potential role of autoantibodies in post-acute COVID-19 neurological symptoms.