Cerebrospinal Fluid in PASC: A Window into the COVID Mind

Introduction: This NOSI award supported the initiation of The COVID Mind Study at Yale, an ongoing longitudinal study to investigate the pathogenic mechanisms of neurologic manifestations of Long COVID through examination of cerebrospinal fluid (CSF), blood, and magnetic resonance imaging (MRI), alongside detailed clinical data in individuals with persistent cognitive symptoms after COVID-19. Our objective is to use multi-modal data to generate high-impact novel understanding of the pathogenesis of neurologic Long COVID.

Objective: Informed by our studies in acute COVID-19, we are investigating para-infectious processes in neurologic Long COVID, including systemic inflammatory abnormalities, vascular damage, viral persistence in the central nervous system (CNS), and dysregulated CNS host immune responses including autoimmunity.

Methods: In Aim 1, we are defining the clinical and immunological features through deep immunophenotyping of the cerebrospinal fluid (CSF) and blood, including assessment of brain autoimmunity and altered T cell function. In Aim 2, we are assessing for SARS-CoV-2 persistence in the CSF and blood through highly sensitive viral antigen detection assays. In Aim 3, we are measuring objective markers of nervous system dysfunction through multimodal brain MRI, neurocognitive testing, and CSF and blood markers of neuronal injury. Ultimately, we will perform multivariate analyses to assess the relationship between immune perturbations, viral persistence, and objective measures of neurologic injury. A major unique focus of our study is state-of-the-art examination of CSF, employing soluble biomarker assays, high throughput transcriptomics, epigenomics, and advanced proteomics. CSF is produced within the brain in the choroid plexus and is the only CNS tissue readily sampled in living humans. CSF immune cells reflect infiltrating brain parenchymal immune and have provided critical insight into other infectious, inflammatory and degenerative CNS disorders. Our group has advanced the understanding of chronic viral effects in the CNS through CSF-based studies in HIV. Furthermore, we have successfully integrated CSF and blood studies with neuroimaging data to reveal novel understanding of the pathophysiology of neurologic injury in viral infection.

Results: n-LC participants have abnormalities on detailed cognitive assessments, no overt signs of neuroinflammation based on clinical CSF tests nor on a survey of 15 soluble cytokines in CSF, and no detectability of SARS-CoV-2 in CSF by antigen or PCR testing. We have detected anti-neuronal antibodies in CSF in a case of n-LC psychosis but have since found CSF autoantibodies to be non-specific. Our more recent work has demonstrated alterations in cellular function of CSF T cells specifically in women with n-LC, as well as alterations in blood markers of endothelial activation and endothelial/immune cell interaction associating with cognitive and affective symptoms in n-LC. Importantly, our preliminary imaging studies reveal subtle alterations in brain structure and blood flow in individuals compared to controls, specifically in regions with accelerated atrophy in the landmark UK Biobank Study.

Conclusion/Discussion: This funding initiated the comprehensive infrastructure and participant cohorts of the ongoing COVID Mind Study, a longitudinal research program specifically designed to elucidate n-LC pathophysiology through multimodal assessment of poeple with n-LC and matched fully recovered controls. Our published and widely presented findings to date indicate that while overt chronic inflammation or viral persistence are not detected in the CSF, more subtle CNS cellular abnormalities as well as vascular inflammation may associate with n-LC symptoms, warranting additional studies which are now ongoing.

Key Topics:

• Advanced imaging analysis to define the long term impact of COVID on organ structure/function and characterize Long COVID phenotypes
• Assay and in vitro studies to gain mechanistic insights
• Biomarker, in-depth phenotyping assays and in vitro studies using tissue and other biospecimens
• Chronic immune dysfunction
• Clinical assessment and pathogenesis of clinical manifestations
• Remaining gaps in tissue-specific manifestations of Long COVID
• Studies of vascular injury, thrombosis, and other potential mechanisms of Long COVID
• Viral persistence/reactivation