CD19-Directed CAR T-Cells in a Patient With Refractory MOGAD: Clinical and Immunologic Follow-Up for 1 Year.

OBJECTIVES: In MOG antibody-associated disease (MOGAD), relapse prevention and the treatment approach to refractory symptoms are unknown. We report a patient with refractory MOGAD treated with CD19-directed CAR T-cells. METHODS: CD19-directed CAR T-cells (ARI-0001) were produced in-house by lentiviral transduction of autologous fresh leukapheresis and infused after a conventional lymphodepleting regimen. RESULTS: A 18-year-old man developed 2 episodes of myelitis associated with serum MOG-IgG, which were followed by 6 episodes of left optic neuritis (ON) and sustained the presence of MOG-IgG over 6 years despite multiple immunotherapies. After the sixth episode of ON, accompanied by severe residual visual deficits, CAR T-cell treatment was provided without complications. Follow-up of cell counts showed complete depletion of CD19+ B cells at day +7; reconstituted B cells at day +141 showing a naïve B-cell phenotype, and low or absent memory B cells and plasmablasts for 1 year. MOG-IgG titers have remained undetectable since CAR T-cell infusion. The patient had an early episode of left ON at day +29, when MOG-IgG was already negative, and since then he has remained free of relapses without immunotherapy for 1 year. DISCUSSION: This clinical case shows that CD19-directed CAR T-cell therapy is well-tolerated and is a potential treatment for patients with refractory MOGAD. CLASSIFICATION OF EVIDENCE: This provides Class IV evidence. It is a single observational study without controls.

Antibodies Against ZSCAN1 in Pediatric and Adult Patients With Non-Paraneoplastic ROHHAD Syndrome.

OBJECTIVES: To report the association of zinc finger and SCAN domain containing 1 antibodies (ZSCAN1-abs) with rapid-onset obesity, hypothalamic dysfunction, hypoventilation, and autonomic dysregulation (ROHHAD) syndrome in patients without tumor. METHODS: Patients with symptoms compatible with ROHHAD syndrome but without an associated tumor were selected from our database. Serum and CSF samples were examined for the presence of ZSCAN1-abs by an in-house cell-based assay. In addition, samples from 149 patients with several inflammatory and noninflammatory disorders and 50 healthy participants served as controls. RESULTS: Thirteen patients with ROHHAD syndrome were identified. Of these, we had paired serum/CSF samples from 6 patients and only serum from the other 7. Five of 6 patients (83.3%) with paired serum/CSF (4 children, 1 adult) had ZSCAN-abs only in CSF and 1 had antibodies in serum and CSF. ZSCAN1-abs were not detected in the remaining 7 patients with ROHHAD with only serum available or in any of the 199 control samples. DISCUSSION: Patients with ROHHAD syndrome should be investigated for the presence of ZSCAN1-abs in CSF. The antibodies do not necessarily predict the presence of a tumor. The detection of ZSCAN1-abs in an adult patient suggests that this condition also occurs beyond the pediatric age.

Very Long-Term Functional Outcomes and Dependency in Children With Anti-NMDA Receptor Encephalitis.

OBJECTIVES: To assess the daily function of children with anti-N-methyl-d-aspartate receptor encephalitis (NMDARe) after a minimal follow-up of 5 years. METHODS: Patients 18 years and younger by the time of disease onset, whose serum and CSF were studied in our center between 2013 and 2017, were included in the study. Patients' daily life function was assessed by their physicians using a 15-domain question format (Liverpool Outcome Score). RESULTS: Of 76 patients, 8 (11%) died and 68 were followed for a mean of 7.1 years (SD 1.5 years, range: 5.0-10.1). Three outcome patterns were identified: full recovery (50; 73%); behavioral and school/working deficits (12; 18%); and multidomain deficits (6; 9%) involving self-care ability, behavioral-cognitive impairment, and seizures. Younger age of disease onset was significantly associated with multidomain deficits (OR 1.6, 95% CI 1.02-2.4, p = 0.04), particularly in children younger than 6 years, among whom 8 of 23 (35%) remained sociofamiliar dependent. DISCUSSION: After a minimal follow-up of 5 years, most children with NMDARe had substantial or full functional recovery, but approximately one-fifth remained with behavioral and school/working deficits. The younger the patient at disease onset, the more probable it was to remain with multidomain deficits and dependent on sociofamiliar support.

Neurological, psychiatric, and sleep investigations after treatment of anti-leucine-rich glioma-inactivated protein 1 (LGI1) encephalitis in Spain: a prospective cohort study.

BACKGROUND: Anti-leucine-rich glioma-inactivated protein 1 (LGI1) encephalitis is an autoimmune disorder that can be treated with immunotherapy, but the symptoms that remain after treatment have not been well described. We aimed to characterise the clinical features of patients with anti-LGI1 encephalitis for 1 year starting within the first year after initial immunotherapy. METHODS: For this prospective cohort study, we recruited patients with anti-LGI1 encephalitis as soon as possible after they had received conventional immunotherapy for initial symptoms; patients were recruited from 21 hospitals in Spain. Patients were excluded if they had an interval of more than 1 year since initial immunotherapy, had pre-existing neurodegenerative or psychiatric disorders, or were unable to travel to Hospital Clínic de Barcelona (Barcelona, Spain). Patients visited Hospital Clínic de Barcelona on three occasions-the first at study entry (visit 1), the second 6 months later (visit 2), and the third 12 months after the initial visit (visit 3). They underwent neuropsychiatric and videopolysomnography assessments at each visit. Healthy participants who were matched for age and sex and recruited from Hospital Clínic de Barcelona underwent the same investigations at study entry and at 12 months. Cross-sectional comparisons of clinical features between groups were done with conditional logistic regression, and binary logistic regression was used to assess associations between cognitive outcomes at 12 months and clinical features before initial immunotherapy and at study entry. FINDINGS: Between May 1, 2019, and Sept 30, 2022, 42 participants agreed to be included in this study. 24 (57%) participants had anti-LGI1 encephalitis (mean age 63 years [SD 12]; 13 [54%] were female and 11 [46%] were male) and 18 (43%) were healthy individuals (mean age 62 years [10]; 11 [61%] were female and seven [39%] were male). At visit 1 (median 88 days [IQR 67-155] from initiation of immunotherapy), all 24 patients had one or more symptoms; 20 (83%) patients had cognitive deficits, 20 (83%) had psychiatric symptoms, 14 (58%) had insomnia, 12 (50%) had rapid eye movement (REM)-sleep behaviour disorder, nine (38%) had faciobrachial dystonic seizures, and seven (29%) had focal onset seizures. Faciobrachial dystonic seizures were unnoticed in four (17%) of 24 patients and focal onset seizures were unnoticed in five (21%) patients. At visit 1, videopolysomnography showed that 19 (79%) patients, but no healthy participants, had disrupted sleep structure (p=0·013); 15 (63%) patients and four (22%) healthy participants had excessive fragmentary myoclonus (p=0·039), and nine (38%) patients, but no healthy participants, had myokymic discharges (p=0·0051). These clinical and videopolysomnographic features led to additional immunotherapy in 15 (63%) of 24 patients, which resulted in improvement of these features in all 15 individuals. However, at visit 3, 13 (65%) of 20 patients continued to have cognitive deficits. Persistent cognitive deficits at visit 3 were associated with no use of rituximab before visit 1 (odds ratio [OR] 4·0, 95% CI 1·5-10·7; p=0·0015), REM sleep without atonia at visit 1 (2·2, 1·2-4·2; p=0·043), and presence of LGI1 antibodies in serum at visit 1 (11·0, 1·1-106·4; p=0·038). INTERPRETATION: Unsuspected but ongoing clinical and videopolysomnography alterations are common in patients with anti-LGI1 encephalitis during the first year or more after initial immunotherapy. Recognising these alterations is important as they are treatable, can be used as outcome measures in clinical trials, and might influence cognitive outcome. FUNDING: Fundació La Caixa.

Clinical characterisation of patients in the post-acute stage of anti-NMDA receptor encephalitis: a prospective cohort study and comparison with patients with schizophrenia spectrum disorders.

BACKGROUND: Anti-NMDA receptor (NMDAR) encephalitis is associated with a post-acute stage that is not well known. We aimed to describe the clinical features of this stage, similarities with schizophrenia spectrum disorders, and the factors that predict cognitive-psychiatric outcomes and could serve as prognostic biomarkers. METHODS: In this prospective cohort study, participants (aged 12-60 years) with anti-NMDAR encephalitis during the post-acute stage visited Hospital Clínic de Barcelona (Barcelona, Spain) on three occasions (at study entry [V1], at 6 months [V2], and at 12 months [V3]) and underwent comprehensive neuropsychiatric evaluations. Similar evaluations were done in a group of age-matched participants with schizophrenia spectrum disorders and a group of age-matched and sex-matched healthy participants also recruited from Hospital Clínic de Barcelona. We analysed differences between and within groups in the longitudinal follow-up using multilevel linear mixed-effect models, adjusting for group, age, sex, and socioeconomic status to control for possible confounding. FINDINGS: Between Jan 1, 2017, and Sept 30, 2020, 82 participants were recruited, 28 (34%) with anti-NMDAR encephalitis, 27 (33%) with schizophrenia spectrum disorders, and 27 (33%) healthy participants. Although, by V1 (median 4 months [IQR 3-7] from disease onset), many acute-stage symptoms in participants with anti-NMDAR encephalitis had resolved (acute stage median modified Rankin Scale [mRS] score 5 [IQR 4-5] vs V1 mRS score 2 [1-2]; p<0·0001), 25 (89%) participants showed deficits in at least one cognitive domain. In this group, 15 (68%) of 22 cognitive domain variables were impaired at V1, whereas only eight (36%) were altered at V3 (p=0·016). In participants with schizophrenia spectrum disorders, 11 (50%) of 22 variables (all shared with participants with anti-NMDAR encephalitis) were impaired at V1, without changes at V3. Two acute-stage features of anti-NMDAR encephalitis (ie, decreased consciousness and no improvement within the first 4 weeks of treatment) predicted cognitive domain outcomes, and a visuospatial task (ie, serial biases) at V1 showed potential in predicting learning and memory outcomes. At V1, all psychiatric symptom clusters were similarly altered in participants with anti-NMDAR encephalitis and in those with schizophrenia spectrum disorders, but only those in individuals with anti-NMDAR encephalitis subsequently improved (p=0·031). The greatest cognitive-psychiatric improvement in participants with anti-NMDAR encephalitis occurred between V1 and V2. During this interval, four (14%) participants with anti-NMDAR encephalitis would have met the diagnostic criteria of schizophrenia if CSF antibody findings had not been investigated. INTERPRETATION: The cognitive-psychiatric symptoms of anti-NMDAR encephalitis in the post-acute stage resembled those of stabilised schizophrenia, but only those in participants with anti-NMDAR encephalitis progressively improved, predominantly during V1-V2. These findings are important for clinical trials on anti-NMDAR encephalitis and suggest that prompt cognitive-psychosocial rehabilitation might be a valuable intervention. FUNDING: Instituto Salud Carlos III, NEURON Network of European Funding for Neuroscience Research, National Alliance for Research in Schizophrenia and Affective Disorders, and la Caixa Health-Research Foundation.

Rituximab as Second-Line Treatment in Anti-NMDAR Encephalitis after Herpes Simplex Encephalitis in Children.

The long-term response of two infants with anti-N-methyl-D-aspartate receptor (anti-NMDAR) post herpes simplex encephalitis treated with rituximab is reported here. Rituximab may improve the course of the disease and should be considered early as second-line treatment. Data on the long-term effect of rituximab in B cell depletion and immunoglobulins levels in infants are needed.

Neurofilament Light Chain Levels in Anti-NMDAR Encephalitis and Primary Psychiatric Psychosis.

BACKGROUND AND OBJECTIVES: An important challenge in diagnosing anti-NMDA receptor (NMDAR) encephalitis (NMDARe) is differentiating it from a first episode of psychosis (FEP) caused by a psychiatric disease (pFEP). CSF antibody testing distinguishes these diseases, but spinal taps are difficult to obtain in psychiatric facilities. A separate problem is the lack of biomarkers of NMDARe severity and outcome. Here we assessed the performance of neurofilament light chain (NfL) testing in these settings. METHODS: In this observational study, NfL levels were determined with single-molecule array in patients with NMDARe, pFEP, herpes simplex encephalitis (HSE), and healthy participants (HC), with the last 2 groups used as controls. Receiver operating characteristic (ROC) analyses were performed to assess the prediction accuracy of serum NfL (sNfL) levels for NMDARe and pFEP and to obtain clinically useful cutoffs. RESULTS: One hundred eighteen patients with NMDARe (33 with isolated psychosis at presentation), 45 with pFEP, 36 with HSE, and 36 HC were studied. Patients with NMDARe with seizures/status epilepticus, intensive care unit admission, and CSF pleocytosis (>20 white blood cells/µL) and without early immunotherapy were more likely to have higher NfL (mainly in CSF) than individuals with NMDARe without these features. NfL levels at diagnosis of NMDARe did not correlate with outcome at 1-year follow-up assessed with the modified Rankin Scale. Patients with NMDARe had significantly higher sNfL than individuals with pFEP and HC and lower sNfL than patients with HSE. ROC analysis of sNfL between NMDARe with isolated psychosis and pFEP provided an area under the curve of 0.93 (95% CI 0.87-0.99) and an sNfL cutoff ≥15 pg/mL to distinguish these disorders (sensitivity 85%, specificity 96%, positive likelihood ratio 19.3). Forty-three of 45 (96%) patients with pFEP had sNfL<15 pg/mL, whereas only 5 of 33 (15%) with NMDARe with isolated psychosis were below this cutoff (risk estimation NMDARe vs pFEP: odds ratio 120.4 [95% CI 21.8-664], p < 0.001). None of the patients with HSE and 35 of 36 (97%) HC had sNfL<15 pg/mL. DISCUSSION: NfL measured at diagnosis of NMDARe associated with features of disease severity but not with long-term outcome. Young patients with FEP and sNfL ≥15 pg/mL had a 120 times higher chance of having NMDARe than those with pFEP. This cutoff correctly classified 96% of patients with pFEP and 85% of patients with NMDARe with isolated psychosis. Patients with FEP of unclear etiology and sNfL ≥15 pg/mL should undergo CSF NMDAR antibody testing.

Use and Safety of Immunotherapeutic Management of N-Methyl-d-Aspartate Receptor Antibody Encephalitis: A Meta-analysis.

Importance: Overall, immunotherapy has been shown to improve outcomes and reduce relapses in individuals with N-methyl-d-aspartate receptor (NMDAR) antibody encephalitis (NMDARE); however, the superiority of specific treatments and combinations remains unclear. Objective: To map the use and safety of immunotherapies in individuals with NMDARE, identify early predictors of poor functional outcome and relapse, evaluate changes in immunotherapy use and disease outcome over the 14 years since first reports of NMDARE, and assess the Anti-NMDAR Encephalitis One-Year Functional Status (NEOS) score. Data Sources: Systematic search in PubMed from inception to January 1, 2019. Study Selection: Published articles including patients with NMDARE with positive NMDAR antibodies and available individual immunotherapy data. Data Extraction and Synthesis: Individual patient data on immunotherapies, clinical characteristics at presentation, disease course, and final functional outcome (modified Rankin Scale [mRS] score) were entered into multivariable logistic regression models. Main Outcomes and Measures: The planned study outcomes were functional outcome at 12 months from disease onset (good, mRS score of 0 to 2; poor, mRS score greater than 2) and monophasic course (absence of relapse at 24 months or later from onset). Results: Data from 1550 patients from 652 articles were evaluated. Of these, 1105 of 1508 (73.3%) were female and 707 of 1526 (46.3%) were 18 years or younger at disease onset. Factors at first event that were significantly associated with good functional outcome included adolescent age and first-line treatment with therapeutic apheresis, corticosteroids plus intravenous immunoglobulin (IVIG), or corticosteroids plus IVIG plus therapeutic apheresis. Factors significantly associated with poor functional outcome were age younger than 2 years or age of 65 years or older at onset, intensive care unit admission, extreme delta brush pattern on electroencephalography, lack of immunotherapy within the first 30 days of onset, and maintenance IVIG use for 6 months or more. Factors significantly associated with nonrelapsing disease were rituximab use or maintenance IVIG use for 6 months or more. Adolescent age at onset was significantly associated with relapsing disease. Rituximab use increased from 13.5% (52 of 384; 2007 to 2013) to 28.3% (311 of 1100; 2013 to 2019) (P < .001), concurrent with a falling relapse rate over the same period (22% [12 of 55] in 2008 and earlier; 10.9% [35 of 322] in 2017 and later; P = .006). Modified NEOS score (including 4 of 5 original NEOS items) was associated with probability of poor functional status at 1 year (20.1% [40 of 199] for a score of 0 to 1 points; 43.8% [77 of 176] for a score of 3 to 4 points; P = .05). Conclusions and Relevance: Factors influencing functional outcomes and relapse are different and need to be considered independently in development of evidence-based optimal management guidelines of patients with NMDARE.

International Consensus Recommendations for the Treatment of Pediatric NMDAR Antibody Encephalitis.

OBJECTIVE: To create an international consensus treatment recommendation for pediatric NMDA receptor antibody encephalitis (NMDARE). METHODS: After selection of a panel of 27 experts with representation from all continents, a 2-step Delphi method was adopted to develop consensus on relevant treatment regimens and statements, along with key definitions in pediatric NMDARE (disease severity, failure to improve, and relapse). Finally, an online face-to-face meeting was held to reach consensus (defined as ≥75% agreement). RESULTS: Corticosteroids are recommended in all children with NMDARE (pulsed IV preferred), with additional IV immunoglobulin or plasma exchange in severe patients. Prolonged first-line immunotherapy can be offered for up to 3-12 months (oral corticosteroids or monthly IV corticosteroids/immunoglobulin), dependent on disease severity. Second-line treatments are recommended for cases refractory to first-line therapies (rituximab preferred over cyclophosphamide) and should be considered about 2 weeks after first-line initiation. Further immunotherapies for refractory disease 1-3 months after second-line initiation include another second-line treatment (such as cyclophosphamide) and escalation to tocilizumab. Maintenance immune suppression beyond 6 months (such as rituximab redosing or mycophenolate mofetil) is generally not required, except for patients with a more severe course or prolonged impairments and hospitalization. For patients with relapsing disease, second-line and prolonged maintenance therapy should be considered. The treatment of NMDARE following herpes simplex encephalitis should be similar to idiopathic NMDARE. Broad guidance is provided for the total treatment duration (first line, second line, and maintenance), which is dictated by the severity and clinical course (i.e., median 3, 9 and 18 months in the best, average, and worst responders, respectively). Recommendations on the timing of oncologic searches are provided. CONCLUSION: These international consensus recommendations for the management of pediatric NMDARE aim to standardize the treatment and provide practical guidance for clinicians, rather than absolute rules. A similar recommendation could be applicable to adult patients.

Absence of GluD2 Antibodies in Patients With Opsoclonus-Myoclonus Syndrome.

OBJECTIVE: A recent study showed glutamate receptor delta 2 antibodies (GluD2-ab) in sera of patients with opsoclonus-myoclonus syndrome (OMS). Inconsistencies between cerebellar immunoreactivity and expression of GluD2 led us to hypothesize that these antibodies are not biomarkers of OMS. METHODS: Serum of 45 children with OMS (10 [22%] with neuroblastoma), 158 adults with OMS (53 [34%] with tumors), and 172 controls including 134 patients with several types of neurologic disorders, 18 with neuroblastoma without OMS, and 20 healthy participants were investigated. Antibodies were determined with 3 different techniques: (1) rat brain immunohistochemistry, (2) a live cell-based assay using a standard secondary antibody (2-step CBA), and (3) a similar CBA with a secondary and tertiary antibodies (3-step CBA). Two plasmids were used in the CBA studies. Three commercial GluD2-ab and 2 human sera with GluD2-ab served as controls for expression of GluD2. RESULTS: The 3 commercial GluD2-ab showed predominant reactivity with the molecular and Purkinje cell layers (where GluD2 is highly enriched), and were also positive with the indicated CBAs. Substantially milder reactivity with brain tissue and CBA was obtained with the 2 control human sera containing GluD2-ab. None of the 203 patients with OMS and 172 controls showed immunoreactivities consistent with GluD2-abs. Compared with a standard 2-step CBA, the 3-step assay did not improve antibody detection and showed more frequent nonspecific reactivity that was not immunoabsorbed with GluD2. CONCLUSION: We did not find GluD2-ab in a large cohort of patients with OMS. GluD2-ab should not be considered diagnostic biomarkers of OMS.

Sleep disorders in anti-NMDAR encephalitis.

OBJECTIVE: To describe the sleep disorders in anti-NMDA receptor encephalitis (anti-NMDARe). METHODS: Patients recovering from anti-NMDARe were invited to participate in a prospective observational single-center study including comprehensive clinical, video-polysomnography (V-PSG) sleep assessment, and neuropsychological evaluation. Age- and sex-matched healthy participants served as controls. RESULTS: Eighteen patients (89% female, median age 26 years, interquartile range [IQR] 21-29 years) and 21 controls (81% female, median age 23 years, IQR 18-26 years) were included. In the acute stage, 16 (89%) patients reported insomnia and 2 hypersomnia; nightmares occurred in 7. After the acute stage, 14 (78%) had hypersomnia. At study admission (median 183 days after disease onset, IQR 110-242 days), 8 patients still had hypersomnia, 1 had insomnia, and 9 had normal sleep duration. Patients had more daytime sleepiness than controls (higher Barcelona Sleepiness Index, p = 0.02, and Epworth Sleepiness Score, p = 0.04). On V-PSG, sleep efficiency was similar in both groups, but patients more frequently had multiple and longer confusional arousals in non-REM (NREM) sleep (videos provided). In addition, 13 (72%) patients had cognitive deficits; 12 (67%) had psychological, social, or occupational disability; and 33% had depression or mania. Compared with controls, patients had a higher body mass index (median 23.5 [IQR 22.3-30.2] vs 20.5 [19.1-21.1] kg/m2; p = 0.007). Between disease onset and last follow-up, 14 (78%) patients developed hyperphagia, and 6 (33%) developed hypersexuality (2 requiring hospitalization), all associated with sleep dysfunction. CONCLUSIONS: Sleep disturbances are frequent in anti-NMDARe. They show a temporal pattern (predominantly insomnia at onset; hypersomnia during recovery), are associated with behavioral and cognitive changes, and can occur with confusional arousals during NREM sleep.

Single-cycle rituximab-induced immunologic changes in children: Enhanced in neuroimmunologic disease?

OBJECTIVE: To investigate the immunologic impact of a single cycle of rituximab (RTX) in children and adolescents with immune-mediated disorders, we evaluated B cells and immunoglobulin levels of 20 patients with neuroimmunologic, nephrologic, dermatologic, and rheumatologic disorders treated under recommended guidelines. METHODS: Retrospective study of immunologic changes in children (aged ≤18 years) diagnosed with immune-mediated disorders in which RTX was prescribed between June 2014 and February 2019. Patients were excluded if they had prior diagnosis of malignant disease or primary immunodeficiency. Patients were clinically and immunologically followed up every 3 months. Only patients having received a single cycle of RTX and with a follow-up greater than 12 months were included in the analysis of persistent dysgammaglobulinemia. RESULTS: Twenty children were included. Median age at RTX treatment was 12.8 years (interquartile range [IQR] 6.6-15.5 years). Median follow-up was 12.6 months (IQR 10.2-24 months). Of the 14 patients eligible for persistent dysgammaglobulinemia analysis (3 had received RTX retreatment, 2 had <12 months post-RTX follow-up, and in 1 data for this time point was missing), 2/14 (14%) remained with complete B-cell depletion, and 5/14 (36%) had dysgammaglobulinemia. Patients with dysgammaglobulinemia were younger (7.8 vs 15.6 years, p = 0.072), had more underlying neuroimmunologic diseases (5/5 vs 0/9, p < 0.001), and had received more frequently concentrated doses of RTX (3/5 vs 1/9, p = 0.05) than patients without dysgammaglobulinemia. Kinetics of immunoglobulins in the 20 patients revealed a decrease as early as 3 months after RTX in patients with neuroimmunologic disorders. CONCLUSION: In our cohort, single-cycle RTX-induced dysgammaglobulinemia was enhanced in patients with neuroimmunologic diseases. Further studies are needed to confirm this observation.

Clinical significance of anti-NMDAR concurrent with glial or neuronal surface antibodies.

OBJECTIVE: To determine the frequency and significance of concurrent glial (glial-Ab) or neuronal-surface (NS-Ab) antibodies in patients with anti-NMDA receptor (NMDAR) encephalitis. METHODS: Patients were identified during initial routine screening of a cohort (C1) of 646 patients consecutively diagnosed with anti-NMDAR encephalitis and another cohort (C2) of 200 patients systematically rescreened. Antibodies were determined with rat brain immunostaining and cell-based assays. RESULTS: Concurrent antibodies were identified in 42 patients (4% from C1 and 7.5% from C2): 30 (71%) with glial-Ab and 12 (29%) with NS-Ab. Glial-Ab included myelin oligodendrocyte glycoprotein (MOG) (57%), glial fibrillary acidic protein (GFAP) (33%), and aquaporin 4 (AQP4) (10%). NS-Ab included AMPA receptor (AMPAR) (50%), GABAa receptor (GABAaR) (42%), and GABAb receptor (8%). In 39 (95%) of 41 patients, concurrent antibodies were detected in CSF, and in 17 (41%), concurrent antibodies were undetectable in serum. On routine clinical-immunologic studies, the presence of MOG-Ab and AQP4-Ab was suggested by previous episodes of encephalitis or demyelinating disorders (8, 27%), current clinical-radiologic features (e.g., optic neuritis, white matter changes), or standard rat brain immunohistochemistry (e.g., AQP4 reactivity). GFAP-Ab did not associate with distinct clinical-radiologic features. NS-Ab were suggested by MRI findings (e.g., medial temporal lobe changes [AMPAR-Ab], or multifocal cortico-subcortical abnormalities [GABAaR-Ab]), uncommon comorbid conditions (e.g., recent herpesvirus encephalitis), atypical tumors (e.g., breast cancer, neuroblastoma), or rat brain immunostaining. Patients with NS-Ab were less likely to have substantial recovery than those with glial-Ab (5 of 10 [50%] vs 17 of 19 [89%], p = 0.03). CONCLUSIONS: Between 4% and 7.5% of patients with anti-NMDAR encephalitis have concurrent glial-Ab or NS-Ab. Some of these antibodies (MOG-Ab, AQP4-Ab, NS-Ab) confer additional clinical-radiologic features and may influence prognosis.

Clinical significance of Kelch-like protein 11 antibodies.

OBJECTIVE: To report the clinical and oncologic associations of antibodies against Kelch-like protein 11 (KLHL11-ab), recently suggested as biomarkers of a paraneoplastic brainstem cerebellar syndrome associated with testicular seminoma, and to determine the value of immunohistochemistry as a screening technique. METHODS: Studies included 432 sera or CSF from 329 patients with paraneoplastic (157) or autoimmune neurologic syndromes (172); 63 with neurologic symptoms and benign teratomas; 28 with small-cell lung cancer, and 12 healthy subjects. KLHL11-abs were examined using a cell-based assay (CBA) with HEK293 cells transfected with a human KLHL11 clone. The CBA specificity was confirmed by immunoprecipitation. All positive samples were examined by immunohistochemistry on rat brain sections. RESULTS: KLHL11-abs were detected in 32 patients by CBA, and patients' antibodies immunoprecipitated KLHL11. Using rat brain immunohistochemistry, only 7 samples (22%) were positive. Patients' median age was 28 years (range 9-76 years), and 16 (50%) were women. Tumors were identified in 23/32 (72%) patients, including 14 teratomas and 7 seminomas or mixed germ cell tumors. Thirteen (41%) patients had cerebellar ataxia (7) or encephalitis with brainstem cerebellar symptoms (6), 7 (22%) anti-NMDA receptor (NMDAR) encephalitis (5 with ovarian teratoma), 5 (16%) opsoclonus-myoclonus, 3 (9%) limbic encephalitis, and 4 (12%) diverse neurologic symptoms (3 with benign teratomas). Concurrent autoantibodies occurred in 14 (44%) patients (7 anti-NMDAR, 6 Ma2, and 1 Hu). CONCLUSIONS: KLHL11-abs associate with a spectrum of syndromes and tumors wider than those previously reported; 44% of patients have concurrent neuronal antibodies, some of them (anti-NMDAR) pathogenically relevant. Brain immunostaining is not useful for routine screening of KLHL11-abs.

Clinical features of seronegative, but CSF antibody-positive, anti-NMDA receptor encephalitis.

OBJECTIVE: To determine the frequency of anti-NMDA receptor encephalitis without detectable serum NMDAR antibodies and to compare the clinical features of these patients with those with NMDAR antibodies in serum and CSF. METHODS: This is a retrospective assessment of serum antibody status and clinical features of 489 patients with anti-NMDAR encephalitis, defined by the presence of NMDAR antibodies in the CSF, and available paired serum/CSF samples examined at Hospital Clínic-Institut d'Investigacions Biomèdiques August Pi I Sunyer, Barcelona, between January 2007 and December 2017. NMDAR antibodies were determined with rat brain immunostaining, in-house cell-based assay (CBA), and a commercial CBA. Patients were considered seronegative if NMDAR antibodies were undetectable with the 3 indicated techniques. RESULTS: Serum NMDAR antibodies were not detected in 75 of 489 (15%) patients. Compared with the 414 seropositive patients, the seronegative were older (23.5 years [interquartile range (IQR): 17-43] vs 20.5 [IQR: 14-31]; p < 0.0001) and less frequently women (39 [52%] vs 313 [76%]; p < 0.001) and had less tumors (6 [9%] vs 128 [32%]; p < 0.001). In multivariate analysis, older age at diagnosis (odds ratio [OR]: 1.35 [per decade]; 95% confidence interval [CI]: 1.10-1.67), absence of tumor (OR: 0.14; 95% CI: 0.05-0.43), and less need for intensive care unit admission (OR: 0.35; 95% CI: 0.18-0.69) were independent variables associated with the absence of serum NMDAR antibodies. Time to diagnosis, treatment with immunotherapy, relapses, and outcome were similar in seronegative and seropositive patients. CONCLUSIONS: NMDAR antibodies are not detected in the serum of 15% of the patients with anti-NMDAR encephalitis. These patients appear to be older and have milder neurologic symptoms with less frequency of tumors.

Paraneoplastic cerebellar ataxia and antibodies to metabotropic glutamate receptor 2.

OBJECTIVE: To report the presence of a new neuronal surface antibody against the metabotropic glutamate receptor 2 antibody (mGluR2-Ab) in 2 patients with paraneoplastic cerebellar ataxia. METHODS: mGluR2-Abs were initially characterized by immunohistochemistry on the rat brain and confirmed by immunofluorescence on HEK293 cells transfected with mGluR2. Additional studies included analysis of potential cross-reactivity with other mGluRs, expression of mGluR2 in patients' tumors, and the effects of mGluR2-Abs on cultures of rat hippocampal neurons. RESULTS: Patient 1 was a 78-year-old woman with progressive cerebellar ataxia with an initial relapsing-remitting course who developed a small-cell tumor of unknown origin. Patient 2 was a 3-year-old girl who presented a steroid-responsive acute cerebellitis preceding the diagnosis of an alveolar rhabdomyosarcoma. Patients' serum and CSF showed a characteristic immunostaining of the hippocampus and cerebellum in rat brain sections and immunolabeled the cell surface of live rat hippocampal neurons. HEK293 cells transfected with mGluR1, 2, 3, and 5 confirmed that patients' antibodies only recognized mGluR2. mGluR2-Abs were not detected in 160 controls, 120 with paraneoplastic, autoimmune, or degenerative ataxias, and 40 with autoimmune encephalitis and antibodies against mGluR5 or unknown antigens. Expression of mGluR2 in tumors was confirmed by immunohistochemistry using a commercial mGluR2-Ab. Incubation of live rat hippocampal neurons with CSF of patient 2 did not modify the density of surface mGluR2 clusters. CONCLUSIONS: mGluR2-Abs are a novel biomarker of paraneoplastic cerebellar ataxia. The potential pathogenic effect of the antibodies is not mediated by downregulation or internalization of neuronal surface mGluR2.

An update on anti-NMDA receptor encephalitis for neurologists and psychiatrists: mechanisms and models.

The identification of anti-NMDA receptor (NMDAR) encephalitis about 12 years ago made it possible to recognise that some patients with rapidly progressive psychiatric symptoms or cognitive impairment, seizures, abnormal movements, or coma of unknown cause, had an autoimmune disease. In this disease, autoantibodies serve as a diagnostic marker and alter NMDAR-related synaptic transmission. At symptom onset, distinguishing the disease from a primary psychiatric disorder is challenging. The severity of symptoms often requires intensive care. Other than clinical assessment, no specific prognostic biomarkers exist. The disease is more prevalent in women (with a female to male ratio of around 8:2) and about 37% of patients are younger than 18 years at presentation of the disease. Tumours, usually ovarian teratoma, and herpes simplex encephalitis are known triggers of NMDAR autoimmunity. About 80% of patients improve with immunotherapy and, if needed, tumour removal, but the recovery is slow. Animal models have started to reveal the complexity of the underlying pathogenic mechanisms and will lead to novel treatments beyond immunotherapy. Future studies should aim at identifying prognostic biomarkers and treatments that accelerate recovery.

Anti-MOG encephalitis mimicking small vessel CNS vasculitis.

Objective: To report 2 patients with anti-myelin oligodendrocyte glycoprotein (MOG)-associated encephalitis who were initially misdiagnosed with small vessel primary CNS vasculitis. Methods: Review of symptoms, MRI and neuropathologic features, and response to treatment. MOG antibodies were determined in serum and CSF using a cell-based assay. Results: Symptoms included fever, headache, and progressive mental status changes and focal neurologic deficits. CSF studies revealed lymphocytic pleocytosis, and both patients had abnormal brain MRIs. Brain biopsy samples showed prominent lymphocytic infiltration of the wall of small vessels; these findings initially suggested small vessel CNS vasculitis, and both patients were treated accordingly. Although 1 patient had a relapsing-remitting course not responsive to cyclophosphamide, the other one (also treated with cyclophosphamide) did not relapse. Retrospective assessment of serum and CSF demonstrated MOG antibodies in both cases, and review of biopsy specimens showed absence of fibrinoid necrosis (a pathologic requirement for small vessel CNS vasculitis). Conclusions: Anti-MOG-associated encephalitis can be mistaken for small vessel CNS vasculitis. This is important because the diagnosis of anti-MOG-associated encephalitis does not require brain biopsy and can be established with a serologic test.

Mouse model of anti-NMDA receptor post-herpes simplex encephalitis.

Objective: To develop an endogenous rodent model of postinfectious anti-NMDA receptor (NMDAR) encephalitis. Methods: Six mice were inoculated intranasally with herpes simplex virus (HSV) 1 and subsequently treated with acyclovir for 2 weeks. Serum was collected at 3, 6, and 8 weeks postinoculation and tested for NMDAR antibodies through a cell-based assay. Eight weeks postinoculation, mice were killed and their brains were sectioned and immunostained with antibodies to postsynaptic density (PSD)-95 and NMDARs. Colocalization of hippocampal PSD-95 and NMDAR clusters, representing postsynaptic membrane NMDARs, was quantified via confocal imaging. Hippocampi were additionally analyzed for NMDAR and PSD-95 protein using Western blot analysis. Results: Four of 6 mice (67%) developed serum antibodies to NMDARs: 1 at 3 weeks, 1 at 6 weeks, and 2 at 8 weeks postinoculation. As compared to inoculated mice that did not develop NMDAR antibodies, immunofluorescence staining revealed decreased hippocampal postsynaptic membrane NMDARs in mice with serum antibodies at 8 weeks postinoculation. Western blot analysis showed that mice that had NMDAR antibodies at 8 weeks had decreased total NMDAR but not PSD-95 protein in hippocampal extracts (p < 0.05). Conclusions: Mice inoculated intranasally with HSV-1 developed serum NMDAR antibodies. These antibodies were associated with reduced hippocampal NMDARs, as has been shown in previous models where antibodies from patients with anti-NMDAR encephalitis were infused into mice, paving the way for future studies into the pathophysiology of autoimmune encephalitides.

Encephalitis with mGluR5 antibodies: Symptoms and antibody effects.

OBJECTIVE: To report the clinical features of 11 patients with metabotropic glutamate receptor 5 (mGluR5) antibody-associated encephalitis, immunoglobulin G (IgG) subclass, and effects of the antibodies on neuronal mGluR5 clusters. METHODS: Clinical information was retrospectively obtained from referring physicians. Antibodies to mGluR5 and IgG subclasses were determined with brain immunohistochemistry and cell-based assays. The effects of the antibodies were examined on rat hippocampal neurons with reported techniques. RESULTS: From January 2005 to May 2017, 11 patients (median age 29 years, range 6-75 years, 5 female) were identified. The main clinical features were psychiatric (10), cognitive (10), movement disorders (7), sleep dysfunction (7), and seizures (6). Median modified Rankin Scale score at the peak of the disease was 4; 4 patients required intensive care. Five patients had Hodgkin lymphoma, and 1 had small cell lung cancer. CSF showed pleocytosis (median white blood cell count 22 mm3) in all patients; brain MRI was abnormal in 5, involving limbic (1) or extralimbic (4) regions. Treatments included immunotherapy and/or oncologic therapy; at the last follow-up (median 48 months), 6 patients had complete and 5 had partial recovery. Neurologic relapse occurred in 2 patients. Antibodies were IgG1 alone (4 of 9) or in combination with IgG2 (1 of 9), IgG3 (3 of 9), or both (1). Patients' IgG caused a significant and specific decrease of cell-surface synaptic and extrasynaptic mGluR5 without altering the levels of postsynaptic density protein 95. CONCLUSIONS: Anti-mGluR5 encephalitis associates with a complex neuropsychiatric syndrome, not restricted to limbic encephalitis, and can occur without tumor. Patients respond to treatment, but relapses can occur. The antibodies have pathogenic effects altering the levels of cell-surface mGluR5.