ABSTRACT
COVID-19 can cause severe neurological symptoms, but the underlying pathophysiological mechanisms are unclear. Here, we interrogated the brain stems and olfactory bulbs in postmortem patients who had COVID-19 using imaging mass cytometry to understand the local immune response at a spatially resolved, high-dimensional, single-cell level and compared their immune map to non-COVID respiratory failure, multiple sclerosis, and control patients. We observed substantial immune activation in the central nervous system with pronounced neuropathology (astrocytosis, axonal damage, and blood-brain-barrier leakage) and detected viral antigen in ACE2-receptor-positive cells enriched in the vascular compartment. Microglial nodules and the perivascular compartment represented COVID-19-specific, microanatomic-immune niches with context-specific cellular interactions enriched for activated CD8+ T cells. Altered brain T-cell-microglial interactions were linked to clinical measures of systemic inflammation and disturbed hemostasis. This study identifies profound neuroinflammation with activation of innate and adaptive immune cells as correlates of COVID-19 neuropathology, with implications for potential therapeutic strategies.
Subject(s)
Brain/immunology , CD8-Positive T-Lymphocytes/immunology , COVID-19/immunology , Microglia/immunology , Blood-Brain Barrier/immunology , Blood-Brain Barrier/metabolism , Blood-Brain Barrier/pathology , Brain/metabolism , Brain/pathology , CD8-Positive T-Lymphocytes/metabolism , COVID-19/pathology , Cell Communication , Central Nervous System/immunology , Central Nervous System/metabolism , Central Nervous System/pathology , Humans , Immune Checkpoint Proteins/metabolism , Inflammation , Lymphocyte Activation , Multiple Sclerosis/immunology , Multiple Sclerosis/pathology , Olfactory Bulb/immunology , Olfactory Bulb/metabolism , Olfactory Bulb/pathology , Respiratory Insufficiency/immunology , Respiratory Insufficiency/pathology , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/metabolism , T-Lymphocyte Subsets/immunology , T-Lymphocyte Subsets/metabolismABSTRACT
The complete features of the neurological complications of coronavirus disease 2019 (COVID-19) still need to be elucidated, including associated cranial nerve involvement. In the present study we describe cranial nerve lesions seen in magnetic resonance imaging (MRI) of six cases of confirmed COVID-19, involving the olfactory bulb, optic nerve, abducens nerve, and facial nerve. Cranial nerve involvement was associated with COVID-19, but whether by direct viral invasion or autoimmunity needs to be clarified. The development of neurological symptoms after initial respiratory symptoms and the absence of the virus in the cerebrospinal fluid (CSF) suggest the possibility of autoimmunity.
Subject(s)
Abducens Nerve/diagnostic imaging , COVID-19/diagnostic imaging , Cranial Nerve Diseases/diagnostic imaging , Facial Nerve/diagnostic imaging , Olfactory Bulb/diagnostic imaging , Optic Nerve/diagnostic imaging , Abducens Nerve/immunology , Abducens Nerve/pathology , Abducens Nerve/virology , Adult , Aged , Autoimmunity , COVID-19/immunology , COVID-19/pathology , COVID-19/virology , Cranial Nerve Diseases/immunology , Cranial Nerve Diseases/pathology , Cranial Nerve Diseases/virology , Facial Nerve/immunology , Facial Nerve/pathology , Facial Nerve/virology , Female , Humans , Magnetic Resonance Imaging , Male , Neuroimaging , Olfactory Bulb/immunology , Olfactory Bulb/pathology , Olfactory Bulb/virology , Optic Nerve/immunology , Optic Nerve/pathology , Optic Nerve/virology , SARS-CoV-2/pathogenicityABSTRACT
Neuropilin-1 (NRP-1), a member of a family of signaling proteins, was shown to serve as an entry factor and potentiate SARS Coronavirus 2 (SARS-CoV-2) infectivity in vitro. This cell surface receptor with its disseminated expression is important in angiogenesis, tumor progression, viral entry, axonal guidance, and immune function. NRP-1 is implicated in several aspects of a SARS-CoV-2 infection including possible spread through the olfactory bulb and into the central nervous system and increased NRP-1 RNA expression in lungs of severe Coronavirus Disease 2019 (COVID-19). Up-regulation of NRP-1 protein in diabetic kidney cells hint at its importance in a population at risk of severe COVID-19. Involvement of NRP-1 in immune function is compelling, given the role of an exaggerated immune response in disease severity and deaths due to COVID-19. NRP-1 has been suggested to be an immune checkpoint of T cell memory. It is unknown whether involvement and up-regulation of NRP-1 in COVID-19 may translate into disease outcome and long-term consequences, including possible immune dysfunction. It is prudent to further research NRP-1 and its possibility of serving as a therapeutic target in SARS-CoV-2 infections. We anticipate that widespread expression, abundance in the respiratory and olfactory epithelium, and the functionalities of NRP-1 factor into the multiple systemic effects of COVID-19 and challenges we face in management of disease and potential long-term sequelae.