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Immunological mechanisms and therapy approaches in psychotic syndromes were recently supported by the discovery of autoantibody-associated limbic and non-limbic encephalitis. However, how clinical diagnostic procedures in psychiatry should be adapted to these new insights is still unclear. In this study, we analyzed the cerebrospinal fluid (CSF) and neuroimmunological alterations and their association with cerebral MRI (cMRI) and electroencephalographic (EEG) findings. From 2006 to 2013, we acquired 180 CSF samples from psychotic patients. Between 2006 and 2009, CSF examinations were only performed in cases in which organic brain disease was suspected. Since then, this procedure has been integrated into our routine diagnostic workup. CSF basic diagnostics were supplemented by measuring antineuronal antibodies against intracellular synaptic antigens, antibodies against intracellular onconeural antigens, antibodies against neuronal cell surface antigens and thyroid antibodies. In addition, cMRIs and EEGs were conducted. We found white cell counts elevated in 3.4% of the cases, albumin quotient elevated in 21.8%, and protein concentration elevated in 42.2%. Evidence of intrathecal immunoglobulin synthesis was found in 7.2% of the cases. Antibodies measured against neuronal cell surface antigens were positive in 3.2%. Reactivity on antibodies against intracellular onconeural antigens were detected in 3.5%. Serum thyroid antibodies were elevated in 24.7%. Abnormalities were found in 39.5% of cMRIs and in 34.3% of EEGs. The main finding of our study was the high prevalence of CSF and autoantibody abnormalities in 54.4% of psychotic patients. In combination with cMRIs and EEGs, 75.6% showed abnormal findings. Our results are discussed with regard to the concept of immunological encephalopathy. Future studies should analyze the efficacy of immunomodulatory therapies.

Background Comprehensive data on the cerebrospinal fluid (CSF) profile in patients with COVID-19 and neurological involvement from large-scale multicenter studies are missing so far. Objective To analyze systematically the CSF profile in COVID-19. Methods Retrospective analysis of 150 lumbar punctures in 127 patients with PCR-proven COVID-19 and neurological symptoms seen at 17 European university centers Results The most frequent pathological finding was blood-CSF barrier (BCB) dysfunction (median QAlb 11.4 [6.72–50.8]), which was present in 58/116 (50%) samples from patients without pre-/coexisting CNS diseases (group I). QAlb remained elevated > 14d (47.6%) and even > 30d (55.6%) after neurological onset. CSF total protein was elevated in 54/118 (45.8%) samples (median 65.35 mg/dl [45.3–240.4]) and strongly correlated with QAlb. The CSF white cell count (WCC) was increased in 14/128 (11%) samples (mostly lympho-monocytic; median 10 cells/µl, > 100 in only 4). An albuminocytological dissociation (ACD) was found in 43/115 (37.4%) samples. CSF l-lactate was increased in 26/109 (24%; median 3.04 mmol/l [2.2–4]). CSF-IgG was elevated in 50/100 (50%), but was of peripheral origin, since QIgG was normal in almost all cases, as were QIgA and QIgM. In 58/103 samples (56%) pattern 4 oligoclonal bands (OCB) compatible with systemic inflammation were present, while CSF-restricted OCB were found in only 2/103 (1.9%). SARS-CoV-2-CSF-PCR was negative in 76/76 samples. Routine CSF findings were normal in 35%. Cytokine levels were frequently elevated in the CSF (often associated with BCB dysfunction) and serum, partly remaining positive at high levels for weeks/months (939 tests). Of note, a positive SARS-CoV-2-IgG-antibody index (AI) was found in 2/19 (10.5%) patients which was associated with unusually high WCC in both of them and a strongly increased interleukin-6 (IL-6) index in one (not tested in the other). Anti-neuronal/anti-glial autoantibodies were mostly absent in the CSF and serum (1509 tests). In samples from patients with pre-/coexisting CNS disorders (group II [N = 19]; including multiple sclerosis, JC-virus-associated immune reconstitution inflammatory syndrome, HSV/VZV encephalitis/meningitis, CNS lymphoma, anti-Yo syndrome, subarachnoid hemorrhage), CSF findings were mostly representative of the respective disease. Conclusions The CSF profile in COVID-19 with neurological symptoms is mainly characterized by BCB disruption in the absence of intrathecal inflammation, compatible with cerebrospinal endotheliopathy. Persistent BCB dysfunction and elevated cytokine levels may contribute to both acute symptoms and ‘long COVID’. Direct infection of the CNS with SARS-CoV-2, if occurring at all, seems to be rare. Broad differential diagnostic considerations are recommended to avoid misinterpretation of treatable coexisting neurological disorders as complications of COVID-19.

Vascular endothelial growth factor (VEGF) A is generated as two isoform families by alternative RNA splicing, represented by VEGF-A165a and VEGF-A165b. These isoforms have opposing actions on vascular permeability, angiogenesis, and vasodilatation. The proangiogenic VEGF-A165a isoform is neuroprotective in hippocampal, dorsal root ganglia, and retinal neurons, but its propermeability, vasodilatatory, and angiogenic properties limit its therapeutic usefulness. In contrast, a neuroprotective effect of endogenous VEGF-A165b on neurons would be advantageous for neurodegenerative pathologies. Endogenous expression of human and rat VEGF-A165b was detected in hippocampal and cortical neurons. VEGF-A165b formed a significant proportion of total VEGF-A in rat brain. Recombinant human VEGF-A165b exerted neuroprotective effects in response to multiple insults, including glutamatergic excitotoxicity in hippocampal neurons, chemotherapy-induced cytotoxicity of dorsal root ganglion neurons, and retinal ganglion cells (RGCs) in rat retinal ischemia-reperfusion injury in vivo. Neuroprotection was dependent on VEGFR2 and MEK1/2 activation but not on p38 or phosphatidylinositol 3-kinase activation. Recombinant human VEGF-A165b is a neuroprotective agent that effectively protects both peripheral and central neurons in vivo and in vitro through VEGFR2, MEK1/2, and inhibition of caspase-3 induction. VEGF-A165b may be therapeutically useful for pathologies that involve neuronal damage, including hippocampal neurodegeneration, glaucoma diabetic retinopathy, and peripheral neuropathy. The endogenous nature of VEGF-A165b expression suggests that non-isoform-specific inhibition of VEGF-A (for antiangiogenic reasons) may be damaging to retinal and sensory neurons.