Shh from mossy cells contributes to preventing NSC pool depletion after seizure-induced neurogenesis and in aging.

Epileptic seizures induce aberrant neurogenesis from resident neural stem cells (NSCs) in the dentate gyrus of the adult mouse hippocampus, which has been implicated in depletion of the NSC pool and impairment of hippocampal function. However, the mechanisms regulating neurogenesis after seizures remain unknown. Here we demonstrate that Shh from mossy cells is a major source of Shh signaling activity after seizures, by which mossy cells contribute to seizure-induced neurogenesis and maintenance of the NSC pool. Deletion of Shh from mossy cells attenuates seizure-induced neurogenesis. Moreover, in the absence of Shh from mossy cells, NSCs pool are prematurely depleted after seizure-induced proliferation, and NSCs have impaired self-renewal. Likewise, lack of Shh from mossy cells accelerates age-related decline of the NSC pool with accompanying reduction of self-renewal of NSCs outside the context of pathology such as seizures. Together, our findings indicate that Shh from mossy cells is critical to maintain NSCs and to prevent exhaustion from excessive consumption in aging and after seizures.

CaMKII autophosphorylation but not downstream kinase activity is required for synaptic memory.

CaMKII plays a critical role in long-term potentiation (LTP), a well-established model for learning and memory through the enhancement of synaptic transmission. Biochemical studies indicate that CaMKII catalyzes a phosphotransferase (kinase) reaction of both itself (autophosphorylation) and of multiple downstream target proteins. However, whether either type of phosphorylation plays any role in the synaptic enhancing action of CaMKII remains hotly contested. We have designed a series of experiments to define the minimal requirements for the synaptic enhancement by CaMKII. We find that autophosphorylation of T286 and further binding of CaMKII to the GluN2B subunit are required both for initiating LTP and for its maintenance (synaptic memory). Once bound to the NMDA receptor, the synaptic action of CaMKII occurs in the absence of kinase activity. Thus, autophosphorylation, together with binding to the GluN2B subunit, are the only two requirements for CaMKII in synaptic memory.

Detection of High-Risk Paraneoplastic Antibodies against TRIM9 and TRIM67 Proteins.

OBJECTIVE: Co-occurring anti-tripartite motif-containing protein 9 and 67 autoantibodies (TRIM9/67-IgG) have been reported in only a very few cases of paraneoplastic cerebellar syndrome. The value of these biomarkers and the most sensitive methods of TRIM9/67-IgG detection are not known. METHODS: We performed a retrospective, multicenter study to evaluate the cerebrospinal fluid and serum of candidate TRIM9/67-IgG cases by tissue-based immunofluorescence, peptide phage display immunoprecipitation sequencing, overexpression cell-based assay (CBA), and immunoblot. Cases in which TRIM9/67-IgG was detected by at least 2 assays were considered TRIM9/67-IgG positive. RESULTS: Among these cases (n = 13), CBA was the most sensitive (100%) and revealed that all cases had TRIM9 and TRIM67 autoantibodies. Of TRIM9/67-IgG cases with available clinical history, a subacute cerebellar syndrome was the most common presentation (n = 7/10), followed by encephalitis (n = 3/10). Of these 10 patients, 70% had comorbid cancer (7/10), 85% of whom (n = 6/7) had confirmed metastatic disease. All evaluable cancer biopsies expressed TRIM9 protein (n = 5/5), whose expression was elevated in the cancerous regions of the tissue in 4 of 5 cases. INTERPRETATION: TRIM9/67-IgG is a rare but likely high-risk paraneoplastic biomarker for which CBA appears to be the most sensitive diagnostic assay. ANN NEUROL 2023;94:1086-1101.

Synchrony 2022: Epilepsy and Seizures in Autism Spectrum Disorder Roundtable.

The BRAIN Foundation (Pleasanton, CA, USA) hosted Synchrony 2022, a translational medicine conference focused on research into treatments for individuals with neurodevelopmental disorders (NDD), including those with autism spectrum disorders (ASD) [...].

The CRHR1/CREB/REST signaling cascade regulates mammalian embryonic neural stem cell properties.

Growing evidence suggests that the corticotropin-releasing hormone (CRH) signaling pathway, mainly known as a critical initiator of humoral stress responses, has a role in normal neuronal physiology. However, despite the evidence of CRH receptor (CRHR) expression in the embryonic ventricular zone, the exact functions of CRH signaling in embryonic brain development have not yet been fully determined. In this study, we show that CRHR1 is required for the maintenance of neural stem cell properties, as assessed by in vitro neurosphere assays and cell distribution in the embryonic cortical layers following in utero electroporation. Identifying the underlying molecular mechanisms of CRHR1 action, we find that CRHR1 functions are accomplished through the increasing expression of the master transcription factor REST. Furthermore, luciferase reporter and chromatin immunoprecipitation assays reveal that CRHR1-induced CREB activity is responsible for increased REST expression at the transcriptional level. Taken together, these findings indicate that the CRHR1/CREB/REST signaling cascade plays an important role downstream of CRH in the regulation of neural stem cells during embryonic brain development.

ßIV-Spectrin Autoantibodies in 2 Individuals With Neuropathy of Possible Paraneoplastic Origin: A Case Series.

OBJECTIVE: To identify the autoantigen in 2 individuals with possible seronegative paraneoplastic neuropathy. METHODS: Serum and CSF were screened by tissue-based assay and panned for candidate autoantibodies by phage display immunoprecipitation sequencing (PhIP-Seq). The candidate antigen was validated by immunostaining knockout tissue and HEK 293T cell-based assay. RESULTS: Case 1 presented with gait instability, distal lower extremity numbness, and paresthesias after a recent diagnosis of serous uterine and fallopian carcinoma. Case 2 had a remote history of breast adenocarcinoma and presented with gait instability, distal lower extremity numbness, and paresthesias that progressed to generalized weakness. CSF and serum from both patients immunostained the axon initial segment (AIS) and node of Ranvier (NoR) of mice and enriched ßIV-spectrin by PhIP-Seq. Patient CSF and serum failed to immunostain NoRs in dorsal root sensory neurons from ßI/ßIV-deficient mice. ßIV-spectrin autoantibodies were confirmed by overexpression of AIS and nodal ßIV-spectrin isoforms Σ1 and Σ6 by a cell-based assay. ßIV-spectrin was not enriched in a combined 4,815 PhIP-Seq screens of healthy and other neurologic disease patients. DISCUSSION: Therefore, ßIV-spectrin autoantibodies may be a marker of paraneoplastic neuropathy. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that ßIV-spectrin antibodies are specific autoantibody biomarkers for paraneoplastic neuropathy.

ZSCAN1 Autoantibodies Are Associated with Pediatric Paraneoplastic ROHHAD.

OBJECTIVE: Rapid-onset Obesity with Hypothalamic Dysfunction, Hypoventilation and Autonomic Dysregulation (ROHHAD), is a severe pediatric disorder of uncertain etiology resulting in hypothalamic dysfunction and frequent sudden death. Frequent co-occurrence of neuroblastic tumors have fueled suspicion of an autoimmune paraneoplastic neurological syndrome (PNS); however, specific anti-neural autoantibodies, a hallmark of PNS, have not been identified. Our objective is to determine if an autoimmune paraneoplastic etiology underlies ROHHAD. METHODS: Immunoglobulin G (IgG) from pediatric ROHHAD patients (n = 9), non-inflammatory individuals (n = 100) and relevant pediatric controls (n = 25) was screened using a programmable phage display of the human peptidome (PhIP-Seq). Putative ROHHAD-specific autoantibodies were orthogonally validated using radioactive ligand binding and cell-based assays. Expression of autoantibody targets in ROHHAD tumor and healthy brain tissue was assessed with immunohistochemistry and mass spectrometry, respectively. RESULTS: Autoantibodies to ZSCAN1 were detected in ROHHAD patients by PhIP-Seq and orthogonally validated in 7/9 ROHHAD patients and 0/125 controls using radioactive ligand binding and cell-based assays. Expression of ZSCAN1 in ROHHAD tumor and healthy human brain tissue was confirmed. INTERPRETATION: Our results support the notion that tumor-associated ROHHAD syndrome is a pediatric PNS, potentially initiated by an immune response to peripheral neuroblastic tumor. ZSCAN1 autoantibodies may aid in earlier, accurate diagnosis of ROHHAD syndrome, thus providing a means toward early detection and treatment. This work warrants follow-up studies to test sensitivity and specificity of a novel diagnostic test. Last, given the absence of the ZSCAN1 gene in rodents, our study highlights the value of human-based approaches for detecting novel PNS subtypes. ANN NEUROL 2022;92:279-291.

Corrigendum: Case Report: A False Negative Case of Anti-Yo Paraneoplastic Myelopathy.

[This corrects the article DOI: 10.3389/fneur.2021.728700.].

Risk factors and abnormal cerebrospinal fluid associate with cognitive symptoms after mild COVID-19.

Cognitive post-acute sequelae of SARS-CoV-2 (PASC) can occur after mild COVID-19. Detailed clinical characterizations may inform pathogenesis. We evaluated 22 adults reporting cognitive PASC and 10 not reporting cognitive symptoms after mild SARS-CoV-2 infection through structured interviews, neuropsychological testing, and optional cerebrospinal fluid (CSF) evaluations (53%). Delayed onset of cognitive PASC occurred in 43% and associated with younger age. Cognitive PASC participants had a higher number of pre-existing cognitive risk factors (2.5 vs. 0; p = 0.03) and higher proportion with abnormal CSF findings (77% vs. 0%; p = 0.01) versus controls. Cognitive risk factors and immunologic mechanisms may contribute to cognitive PASC pathogenesis.

Dual ankyrinG and subpial autoantibodies in a man with well-controlled HIV infection with steroid-responsive meningoencephalitis: A case report.

Neuroinvasive infection is the most common cause of meningoencephalitis in people living with human immunodeficiency virus (HIV), but autoimmune etiologies have been reported. We present the case of a 51-year-old man living with HIV infection with steroid-responsive meningoencephalitis whose comprehensive pathogen testing was non-diagnostic. Subsequent tissue-based immunofluorescence with acute-phase cerebrospinal fluid revealed anti-neural antibodies localizing to the axon initial segment (AIS), the node of Ranvier (NoR), and the subpial space. Phage display immunoprecipitation sequencing identified ankyrinG (AnkG) as the leading candidate autoantigen. A synthetic blocking peptide encoding the PhIP-Seq-identified AnkG epitope neutralized CSF IgG binding to the AIS and NoR, thereby confirming a monoepitopic AnkG antibody response. However, subpial immunostaining persisted, indicating the presence of additional autoantibodies. Review of archival tissue-based staining identified candidate AnkG autoantibodies in a 60-year-old woman with metastatic ovarian cancer and seizures that were subsequently validated by cell-based assay. AnkG antibodies were not detected by tissue-based assay and/or PhIP-Seq in control CSF (N = 39), HIV CSF (N = 79), or other suspected and confirmed neuroinflammatory CSF cases (N = 1,236). Therefore, AnkG autoantibodies in CSF are rare but extend the catalog of AIS and NoR autoantibodies associated with neurological autoimmunity.

Case Report: A False Negative Case of Anti-Yo Paraneoplastic Myelopathy.

The development of autoimmune antibody panels has improved the diagnosis of paraneoplastic neurological disorders (PNDs) of the brain and spinal cord. Here, we present a case of a woman with a history of breast cancer who presented with a subacute sensory ataxia that progressed over 18 months. Her examination and diagnostic studies were consistent with a myelopathy. Metabolic, infectious, and autoimmune testing were non-diagnostic. However, she responded to empirical immunosuppression, prompting further workup for an autoimmune etiology. An unbiased autoantibody screen utilizing phage display immunoprecipitation sequencing (PhIP-Seq) identified antibodies to the anti-Yo antigens cerebellar degeneration related protein 2 like (CDR2L) and CDR2, which were subsequently validated by immunoblot and cell-based overexpression assays. Furthermore, CDR2L protein expression was restricted to HER2 expressing tumor cells in the patient's breast tissue. Recent evidence suggests that CDR2L is likely the primary antigen in anti-Yo paraneoplastic cerebellar degeneration, but anti-Yo myelopathy is poorly characterized. By immunostaining, we detected neuronal CDR2L protein expression in the murine and human spinal cord. This case demonstrates the diagnostic utility of unbiased assays in patients with suspected PNDs, supports prior observations that anti-Yo PND can be associated with isolated myelopathy, and implicates CDR2L as a potential antigen in the spinal cord.

Anti-SARS-CoV-2 and Autoantibody Profiles in the Cerebrospinal Fluid of 3 Teenaged Patients With COVID-19 and Subacute Neuropsychiatric Symptoms.

Importance: Neuropsychiatric manifestations of COVID-19 have been reported in the pediatric population. Objective: To determine whether anti-SARS-CoV-2 and autoreactive antibodies are present in the cerebrospinal fluid (CSF) of pediatric patients with COVID-19 and subacute neuropsychiatric dysfunction. Design, Setting, and Participants: This case series includes 3 patients with recent SARS-CoV-2 infection as confirmed by reverse transcriptase-polymerase chain reaction or IgG serology with recent exposure history who were hospitalized at the University of California, San Francisco Benioff Children's Hospital and for whom a neurology consultation was requested over a 5-month period in 2020. During this period, 18 total children were hospitalized and tested positive for acute SARS-CoV-2 infection by reverse transcriptase-polymerase chain reaction or rapid antigen test. Main Outcomes and Measures: Detection and characterization of CSF anti-SARS-CoV-2 IgG and antineural antibodies. Results: Of 3 included teenaged patients, 2 patients had intrathecal anti-SARS-CoV-2 antibodies. CSF IgG from these 2 patients also indicated antineural autoantibodies on anatomic immunostaining. Autoantibodies targeting transcription factor 4 (TCF4) in 1 patient who appeared to have a robust response to immunotherapy were also validated. Conclusions and Relevance: Pediatric patients with COVID-19 and prominent subacute neuropsychiatric symptoms, ranging from severe anxiety to delusional psychosis, may have anti-SARS-CoV-2 and antineural antibodies in their CSF and may respond to immunotherapy.

Divergent and self-reactive immune responses in the CNS of COVID-19 patients with neurological symptoms.

Individuals with coronavirus disease 2019 (COVID-19) frequently develop neurological symptoms, but the biological underpinnings of these phenomena are unknown. Through single-cell RNA sequencing (scRNA-seq) and cytokine analyses of cerebrospinal fluid (CSF) and blood from individuals with COVID-19 with neurological symptoms, we find compartmentalized, CNS-specific T cell activation and B cell responses. All affected individuals had CSF anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies whose target epitopes diverged from serum antibodies. In an animal model, we find that intrathecal SARS-CoV-2 antibodies are present only during brain infection and not elicited by pulmonary infection. We produced CSF-derived monoclonal antibodies from an individual with COVID-19 and found that these monoclonal antibodies (mAbs) target antiviral and antineural antigens, including one mAb that reacted to spike protein and neural tissue. CSF immunoglobulin G (IgG) from 5 of 7 patients showed antineural reactivity. This immune survey reveals evidence of a compartmentalized immune response in the CNS of individuals with COVID-19 and suggests a role of autoimmunity in neurologic sequelae of COVID-19.

RETRACTED: Remission of Subacute Psychosis in a COVID-19 Patient With an Antineuronal Autoantibody After Treatment With Intravenous Immunoglobulin.

Retraction notice to: "Remission of Subacute Psychosis in a COVID-19 Patient With an Antineuronal Autoantibody After Treatment With Intravenous Immunoglobulin" by Lindsay S. McAlpine, Brooke Lifland, Joseph R. Check, Gustavo A. Angarita, Thomas T. Ngo, Samuel J. Pleasure, Michael R. Wilson, Serena S. Spudich, Shelli F. Farhadian, and Christopher M. Bartley (Biol Psychiatry 2021; 90:e23-e26); https://doi.org/10.1016/j.biopsych.2021.03.033. This article has been retracted at the request of corresponding author Christopher Bartley, with agreement from all authors and with approval from Biological Psychiatry Editor John H. Krystal, M.D. See Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). After this article was published, the authors determined that two cerebrospinal fluid (CSF) samples were inadvertently confused, resulting in publication of the wrong COVID-19 patient's immunostaining data. The authors determined that the two CSF samples came from COVID-19 patients with sequential case identifiers (i.e., one identifier ended in a "5" and the other in a "6"). To determine whether the published immunostaining results were produced by CSF from another COVID-19 patient, the authors reperformed the mouse brain immunostaining experiments using additional aliquots of stored CSF from the two research participants in question, as well as with the remaining CSF that had been used in the publication. After repeating the immunostaining with these CSF samples, two blinded raters were able to state unequivocally that the CSF samples from the two COVID-19 patients had been confused. Therefore, while the clinical features of the case report are accurate and unaffected, the research data belong to another COVID-19 research participant, not the one described in the published case report. The authors voluntarily informed the Journal of this honest error upon its discovery. All authors agree to retract this paper and sincerely apologize for having allowed the incorrect images to be published with this case report. To avoid misinterpretation of the research findings, both the editors and authors concur that the only proper course of action was to retract this version of the paper. However, this COVID-19 psychosis case remains of clinical interest because of the patient's clear response to immunotherapy. Therefore, the authors are revising the paper, which the Journal will consider further for publication.

NMDA receptors control development of somatosensory callosal axonal projections.

Callosal projections from primary somatosensory cortex (S1) are key for processing somatosensory inputs and integrating sensory-motor information. How the callosal innervation pattern in S1 is formed during early postnatal development is not clear. We found that the normal termination pattern of these callosal projections is disrupted in cortex specific NMDAR mutants. Rather than projecting selectively to the primary/secondary somatosensory cortex (S1/S2) border, axons were uniformly distributed throughout S1. In addition, the density of this projection increased over postnatal life until the mice died by P30. By combining genetic and antibody-mediated loss of function, we demonstrated that it is GluN2B-containing NMDA receptors in target S1 that mediate this guidance phenotype, thus playing a central role in interhemispheric connectivity. Furthermore, we found that this function of NMDA receptors in callosal circuit formation is independent of ion channel function and works with the EPHRIN-B/EPHB system. Thus, NMDAR in target S1 cortex regulates the formation callosal circuits perhaps by modulating EPH-dependent repulsion.

Exploratory neuroimmune profiling identifies CNS-specific alterations in COVID-19 patients with neurological involvement.

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. We therefore examined immune parameters in cerebrospinal fluid (CSF) and blood samples from a cohort of patients with COVID-19 and significant neurological complications. We found divergent immunological responses in the CNS compartment, including increased levels of IL-12 and IL-12-associated innate and adaptive immune cell activation. Moreover, we found increased proportions of B cells in the CSF relative to the periphery and evidence of clonal expansion of CSF B cells, suggesting a divergent intrathecal humoral response to SARS-CoV-2. Indeed, all COVID-19 cases examined had anti-SARS-CoV-2 IgG antibodies in the CSF whose target epitopes diverged from serum antibodies. We directly examined whether CSF resident antibodies target self-antigens and found a significant burden of CNS autoimmunity, with the CSF from most patients recognizing neural self-antigens. Finally, we produced a panel of monoclonal antibodies from patients' CSF and show that these target both anti-viral and anti-neural antigens-including one mAb specific for the spike protein that also recognizes neural tissue. This exploratory immune survey reveals evidence of a compartmentalized and self-reactive immune response in the CNS meriting a more systematic evaluation of neurologically impaired COVID-19 patients.

The Neocortical Progenitor Specification Program Is Established through Combined Modulation of SHH and FGF Signaling.

Neuronal progenitors in the developing forebrain undergo dynamic competence states to ensure timely generation of specific excitatory and inhibitory neuronal subtypes from distinct neurogenic niches of the dorsal and ventral forebrain, respectively. Here we show evidence of progenitor plasticity when Sonic hedgehog (SHH) signaling is left unmodulated in the embryonic neocortex of the mammalian dorsal forebrain. We found that, at early stages of corticogenesis, loss of Suppressor of Fused (Sufu), a potent inhibitor of SHH signaling, in neocortical progenitors, altered the transcriptomic landscape of male mouse embryos. Ectopic activation of SHH signaling occurred, via degradation of Gli3R, resulting in significant upregulation of fibroblast growth factor 15 (FGF15) gene expression in all E12.5 Sufu-cKO neocortex regardless of sex. Consequently, activation of FGF signaling, and its downstream effector the MAPK signaling, facilitated expression of genes characteristic of ventral forebrain progenitors. Our studies identify the importance of modulating extrinsic niche signals such as SHH and FGF15, to maintain the competency and specification program of neocortical progenitors throughout corticogenesis.SIGNIFICANCE STATEMENT Low levels of FGF15 control progenitor proliferation and differentiation during neocortical development, but little is known on how FGF15 expression is maintained. Our studies identified SHH signaling as a critical activator of FGF15 expression during corticogenesis. We found that Sufu, via Gli3R, ensured low levels of FGF15 was expressed to prevent abnormal specification of neocortical progenitors. These studies advance our knowledge on the molecular mechanisms guiding the generation of specific neocortical neuronal lineages, their implications in neurodevelopmental diseases, and may guide future studies on how progenitor cells may be used for brain repair.