Neuropsychiatric autoimmune encephalitis without VGKC-complex, NMDAR, and GAD autoantibodies: case report and literature review

An Autopsy-proven Case-based Review of Autoimmune Encephalitis

Autoimmune encephalitis (AIE) is a type of immunoreactive encephalitic disorder and is recognized as the most prevalent noninfectious encephalitis. Nevertheless, the rarity of definitive AIE diagnosis through biopsy or autopsy represents a significant hurdle to understanding and managing the disease. In this article, we present the pathological findings of AIE and review the literature based on a distinct case of AIE presenting as CD8+ T-lymphocyte predominant encephalitis. We describe the clinical progression, diagnostic imaging, laboratory data, and autopsy findings of an 80-year-old deceased male patient. The patient was diagnosed with pulmonary tuberculosis 6 months before death and received appropriate medications. A week before admission to the hospital, the patient manifested symptoms such as a tendency to sleep, decreased appetite, and confusion. Although the patient temporally improved with medication including correction of hyponatremia, the patient progressed rapidly and died in 6 weeks. The brain tissue revealed lymphocytic infiltration in the gray and white matter, leptomeninges, and perivascular infiltration with a predominance of CD8+ T lymphocytes, suggesting a case of AIE. There was no detectable evidence of viral infection or underlying neoplasm. The autopsy revealed that this patient also had Alzheimer's disease, atherosclerosis, arteriolosclerosis, and aging-related tau astrogliopathy. This report emphasizes the pivotal role of pathological examination in the diagnosis of AIE, especially when serological autoantibody testing is not available or when a patient is suspected of having multiple diseases.

Canadian Consensus Guidelines for the Diagnosis and Treatment of Autoimmune Encephalitis in Adults

Autoimmune encephalitis is increasingly recognized as a neurologic cause of acute mental status changes with similar prevalence to infectious encephalitis. Despite rising awareness, approaches to diagnosis remain inconsistent and evidence for optimal treatment is limited. The following Canadian guidelines represent a consensus and evidence (where available) based approach to both the diagnosis and treatment of adult patients with autoimmune encephalitis. The guidelines were developed using a modified RAND process and included input from specialists in autoimmune neurology, neuropsychiatry and infectious diseases. These guidelines are targeted at front line clinicians and were created to provide a pragmatic and practical approach to managing such patients in the acute setting.

A complex case of young child with ADHD, developmental delay who developed seronegative autoimmune encephalitis exacerbated by stimulants

Autoimmune encephalitis (AE) is a group of disorders characterized by a wide clinical spectrum ranging from the typical limbic encephalitis to more complex neuropsychiatric symptoms including abnormal movements, psychosis, deficits in memory and cognition, dysautonomia, seizures, or coma. Psychiatric symptoms can occur early in the disease progress or manifest during its course. These symptoms are challenging and often slow down the diagnosis of AE. This is a crucial aspect considering that early diagnosis and management of AE are critical for a good outcome. However, there is a lack in studies outlining the exact symptomatology and specific appropriate care that would allow clinicians to achieve an early diagnosis and management. Additionally, AE in children mostly presents with neuropsychiatric symptoms and diagnosis is especially challenging in kids because of their limited capacity in describing their symptoms, the normal childhood behavioral changes and the possibility of a comorbid psychiatric diagnosis. We present a complex case of seronegative AE with comorbid ADHD (Attention Deficit Hyperactivity Disorder) and anxiety in a young six-year-old girl.

Autoimmune Encephalitis: A Physician’s Guide to the Clinical Spectrum Diagnosis and Management

The rapidly expanding spectrum of autoimmune encephalitis in the last fifteen years is largely due to ongoing discovery of many neuronal autoantibodies. The diagnosis of autoimmune encephalitis can be challenging due to the wide spectrum of clinical presentations, prevalence of psychiatric features that mimic primary psychiatric illnesses, frequent absence of diagnostic abnormalities on conventional brain MR-imaging, non-specific findings on EEG testing, and the lack of identified IgG class neuronal autoantibodies in blood or CSF in a subgroup of patients. Early recognition and treatment are paramount to improve outcomes and achieve complete recovery from these debilitating, occasionally life threatening, disorders. This review is aimed to provide primary care physicians and hospitalists who, together with neurologist and psychiatrists, are often the first port of call for individuals presenting with new-onset neuropsychiatric symptoms, with up-to-date data and evidence-based approach to the diagnosis and management of individuals with neuropsychiatric disorders of suspected autoimmune origin.

Rare antibody-mediated and seronegative autoimmune encephalitis: An update

Paralleling advances with respect to more common antibody-mediated encephalitides, such as anti-N-methyl-D-aspartate receptor (NMDAR) and anti-leucine-rich glioma-inactivated 1 (LGI1) Ab-mediated encephalitis, the discovery and characterisation of novel antibody-mediated encephalitides accelerated over the past decade, adding further depth etiologically to the spectrum of antibody-mediated encephalitis. Herein, we review the major mechanistic, clinical features and management considerations with respect to anti-γ-aminobutyric acid B (GABA_B)-, anti-α-amino-3-hydroxy-5-methyl-4-isoxazolepropinoic receptor- (AMPAR), anti-GABA_A-, anti-dipeptidyl-peptidase-like protein-6 (DPPX) Ab-mediated encephalitides, delineate rarer subtypes and summarise findings to date regarding seronegative autoimmune encephalitis.

A Single-Health System Case Series of New-Onset CNS Inflammatory Disorders Temporally Associated With mRNA-Based SARS-CoV-2 Vaccines

Background

Since 2020, over 250 million doses of mRNA-based SARS-CoV-2 vaccines have been administered in the United States and hundreds of millions worldwide between the Pfizer-BioNTech and Moderna SARS-CoV-2 vaccines. To date, there have been rare reports associating mRNA-based SARS-CoV-2 vaccines with episodes of inflammatory and autoimmune CNS disorders. We report a case series of five patients with new-onset neurological disorders of inflammatory or immunological origin temporally associated with these vaccines.

Methods

A case-series of five patients within a single 23-hospital health system who developed new-onset CNS inflammatory disease within 2 weeks of receiving a dose of an mRNA-based SARS-CoV-2 vaccine.

Results

Five cases of post-vaccination CNS disorders of immune origin (fatal ADEM; n = 1, new-onset NMOSD; n = 2, new-clinical onset MS-like syndrome but with preexisting clinically silent mild demyelination; n = 1, meningoencephalitis; n = 1) observed within 2 weeks of inoculation with either the first or second dose of mRNA-based SARS-CoV-2 vaccines (Moderna = 3, Pfizer = 2).

Discussion

To our knowledge, these are among the emerging cases of CNS adverse events of immunological or inflammatory origin. These findings should be interpreted with great caution as they neither prove a mechanistic link nor imply a potential long-term increased risk in post-vaccination CNS autoimmunity. Larger prospective studies assessing the potential association between mRNA-based vaccination and the development of neurological adverse events of suspected immune origin, particularly among those with underlying CNS or systemic autoimmune disorders, are needed. The use of mRNA-based SARS-CoV-2 vaccines should continue to be strongly encouraged given their high efficacy in overcoming this pandemic.

Psychotic Symptoms as the Initial Presentation of a Long-Lasting Misdiagnosed Anti-GAD65 Autoimmune Encephalitis: An Emblematic Case and Literature Review

OBJECTIVE

To present a long-lasting misdiagnosed case of anti-GAD65 autoimmune encephalitis (AE) and promote the early identification of reversible psychotic symptoms in AE.

METHODS

The case report was generated through detailed assessment of clinical characteristics, cerebral magnetic resonance images, and laboratory results. Meanwhile, a literatures review related to the topic was conducted.

RESULTS

Psychotic symptoms could be presented in the early stage of anti-GAD65 autoimmune encephalitis. Even though there exists a transdisciplinary gap that hinder the timely recognition of early psychiatric symptoms as components of organic disease, a few strategies could be introduced to enable the earlier recognition and appropriate treatment.

CONCLUSIONS

Our report intends to raise awareness to promote the early identification of immune-mediated "symptomatic" forms of psychosis.

Seronegative limbic encephalitis manifesting as subacute amnestic syndrome: a case report and review of the literature

Background

Limbic encephalitis (LE), a variant of autoimmune encephalitis, is inflammation of the limbic system of the brain. The disorder presents with subacute impairment of short-term memory, psychiatric manifestations, confusion and seizures. “Seronegative LE” is a challenging diagnosis in the absence of well-characterized autoantibodies.

Case presentation

A 33-year-old Kuwaiti woman with no relevant past history presented with subacute progressive amnesia of 6-month duration. Magnetic resonance imaging (MRI) showed bilateral hyperintensity of the limbic structures. An extensive workup of the blood and cerebrospinal fluid (CSF) failed to identify paraneoplastic or autoimmune antibodies. The diagnosis of seronegative LE was made, and immunotherapy was initiated, with improvement in cognitive function.

Conclusion

Seronegative LE is a challenging diagnosis. Inability to detect autoantibodies, especially early in the disease course, should not rule out the diagnosis of autoimmune encephalitis. Early diagnosis and treatment with immunotherapy may prevent irreversible brain damage.

Recurrent seizures of autoimmune origin: emerging phenotypes

OBJECTIVE

Recurrent seizures of autoimmune origin (AEp) are one of the most frequent causes of recurrent seizures or suspected epilepsy of unknown cause. The aim of this study was to identify specific phenotypes corresponding to AEp.

METHODS

We retrospectively reviewed features of patients with recurrent seizures of unknown cause and investigated for suspected AEp (January 2015-May 2018). Patients were separated in: (1) AEpAb+: AEp with positive autoantibodies; (2) AEpAb-: suspected AEp (inflammatory central nervous system (CNS) profile) without autoantibodies; (3) NAEp: epilepsy without CNS inflammation.

RESULTS

Eighty-nine epileptic patients underwent a CSF antibody detection. From the remaining 57 epileptic patients (32 excluded for a differential diagnosis), 61.4% were considered as AEp. 21% were AEpAb+ (4 NMDAR, 2 GABAbR, 3 GAD-Ab, 2 LGi1, 1 CASPR2), 40.4% AEpAb-, and 38.6% NAE. AE (AEpAb+ and AEpAb-) was significantly associated with antibody prevalence in epilepsy (APE) score ≥ 4 (80%), encephalitic phase (71.4%), psychiatric involvement (64.7%), cognitive impairment (50%), and status epilepticus (41.2%). Within the group of 29 patients without encephalitic phase and with chronic epilepsy (NEPp), 34.5% were defined as AEp. 10.4% were AEpAb+ (2 GAD, 1 CASPR2) and 24.1% were AEpAb-. NEP AEp was associated with non-cerebral autoimmune disorders, short epileptic disease duration, and cognitive impairment.

CONCLUSIONS

Autoimmune cause (AEp) should be assessed in patient suffering from recurrent seizures of unknown cause. Acute encephalitis is clearly the main AEp phenotype. AEp was also defined in more than one-third of chronic epilepsy patients (NEP) of unknown cause. Then, AEp may be combined with other autoimmune comorbidities, a shorter evolution of recurrent seizures, and cognitive impairment.

Autoimmune psychosis: an international consensus on an approach to the diagnosis and management of psychosis of suspected autoimmune origin

There is increasing recognition in the neurological and psychiatric literature of patients with so-called isolated psychotic presentations (ie, with no, or minimal, neurological features) who have tested positive for neuronal autoantibodies (principally N-methyl-D-aspartate receptor antibodies) and who have responded to immunotherapies. Although these individuals are sometimes described as having atypical, mild, or attenuated forms of autoimmune encephalitis, some authors feel that that these cases are sufficiently different from typical autoimmune encephalitis to establish a new category of so-called autoimmune psychosis. We briefly review the background, discuss the existing evidence for a form of autoimmune psychosis, and propose a novel, conservative approach to the recognition of possible, probable, and definite autoimmune psychoses for use in psychiatric practice. We also outline the investigations required and the appropriate therapeutic approaches, both psychiatric and immunological, for probable and definite cases of autoimmune psychoses, and discuss the ethical issues posed by this challenging diagnostic category.

Autoimmune Encephalitides

Autoimmune encephalitis is a severe inflammatory disorder of the brain with diverse causes and a complex differential diagnosis. Recent advances in the past decade have led to the identification of new syndromes and biological markers of limbic encephalitis, the commonest presentation of autoimmune encephalitis. The successful use of serum and intrathecal antibodies to diagnose affected patients has resulted in few biopsy and postmortem examinations. In those available, there can be variable infiltrating inflammatory T cells with cytotoxic granules in close apposition to neurons, consistent with an inflammatory autoimmune basis, but true vasculitis is rarely seen. The exception is Hashimoto encephalopathy.

Intravenous immunoglobulin for the treatment of autoimmune encephalopathy in children with autism

The identification of brain-targeted autoantibodies in children with autism spectrum disorder (ASD) raises the possibility of autoimmune encephalopathy (AIE). Intravenous immunoglobulin (IVIG) is effective for AIE and for some children with ASD. Here, we present the largest case series of children with ASD treated with IVIG. Through an ASD clinic, we screened 82 children for AIE, 80 of them with ASD. IVIG was recommended for 49 (60%) with 31 (38%) receiving the treatment under our care team. The majority of parents (90%) reported some improvement with 71% reporting improvements in two or more symptoms. In a subset of patients, Aberrant Behavior Checklist (ABC) and/or Social Responsiveness Scale (SRS) were completed before and during IVIG treatment. Statistically significant improvement occurred in the SRS and ABC. The antidopamine D2L receptor antibody, the anti-tubulin antibody and the ratio of the antidopamine D2L to D1 receptor antibodies were related to changes in the ABC. The Cunningham Panel predicted SRS, ABC, parent-based treatment responses with good accuracy. Adverse effects were common (62%) but mostly limited to the infusion period. Only two (6%) patients discontinued IVIG because of adverse effects. Overall, our open-label case series provides support for the possibility that some children with ASD may benefit from IVIG. Given that adverse effects are not uncommon, IVIG treatment needs to be considered cautiously. We identified immune biomarkers in select IVIG responders but larger cohorts are needed to study immune biomarkers in more detail. Our small open-label exploratory trial provides evidence supporting a neuroimmune subgroup in patients with ASD.

Psychiatric syndromes other than dementia

There is wide variability in how psychiatry guidelines and textbooks address the question of cerebrospinal fluid (CSF) diagnostics in the screening of psychiatric disorders. A United States-based textbook confirms that there is no consensus about which laboratory investigation should be routinely performed in psychiatric patients, but with respect to CSF diagnostics, the differences are even more striking. A survey among European experts showed a wide variety of opinions regarding clinical use and criteria in various countries of Europe and worldwide: some psychiatrists, mostly university hospital-based, recommended performing CSF diagnostics in every patient first experiencing severe mental illness (SMI), but especially in patients from the schizophrenia spectrum, whereas others almost never perform CSF examinations themselves and usually refer patients to neurology departments if necessary. Minor neurologic signs are generally frequent in SMI, mainly in affective and schizophrenic disorders. Even with neurologic signs present, there are no clear guidelines regarding CSF evaluation, leaving doctors with experience-based decision making. However, the field is evolving. A recent review provides helpful yellow and red flags for differential diagnosis of SMI from autoimmune encephalitis; interestingly, minor CSF abnormalities are considered a red flag, suggesting that CSF should be routinely performed in acute psychiatric patients. There are reports of single cases identified as an established neurologic disorder: patients within affective and schizophrenic spectrum disorders systematically underwent CSF examination, and were rediagnosed based on CSF results. This was often to the surprise of the psychiatric doctors. Overall, an increasing number of psychiatrists believe that CSF is too rarely examined in psychiatric patients. This chapter provides an overview of differential diagnostic issues in SMI, particularly for new-onset cases. The general recommendations regarding CSF examination procedures can be found in other chapters of this book. Here we focus on specific aspects of differential diagnosis in SMI. Also, there will be an overview of admittedly limited CSF research efforts in psychiatric disorders, focusing on more recent CSF studies. CSF studies in SMI performed with state-of-the-art methods, for example proteomics or assessments of cytokines, were intriguing but difficult to interpret and required critical considerations regarding respective methodology, an undertaking which is outside the scope of this chapter.

Seronegative Paraneoplastic Limbic Encephalitis Associated with Thymoma

Paraneoplastic limbic encephalitis is an autoimmune syndrome characterized by the acute or subacute onset of encephalopathy, memory loss, confusion, temporal lobe seizures, and behavioral and mood changes. Although most patients with paraneoplastic limbic encephalitis have antineuronal antibodies, advances in the field now permit the diagnosis without autoantibody test results. In this case illustrating the new diagnostic criteria, we report a 70-year-old woman who was brought to the emergency room after the acute onset of cognitive impairment, altered mental status, and choreoathetoid movements. Brain magnetic resonance imaging showed hyperintense signals in both temporal lobes, and a chest computed tomogram revealed a thymoma. Because the patient met current diagnostic criteria for autoimmune limbic encephalitis, we were able to start treatment before her antibody tests were processed. The patient received immunotherapy and her tumor was resected. Her choreoathetoid movements disappeared and her other neurologic symptoms improved. Her cerebrospinal fluid proved to be negative for paraneoplastic limbic encephalitis antibodies. Most but not all patients with paraneoplastic limbic encephalitis associated with thymoma have evidence of paraneoplastic antibodies. Prompt management of the underlying malignancy determines whether patients survive and may minimize future cognitive and functional impairment. Practicing neurologists and psychiatrists should be aware of this diagnosis.

A clinical approach to new-onset psychosis associated with immune dysregulation: the concept of autoimmune psychosis

Growing data point to the overlap between psychosis and pathological processes associated with immunological dysregulation as well as inflammation. Notably, the recent discovery of antibodies against synaptic and neuronal cell membrane proteins such as anti-N-methyl-d-aspartate receptor provides more direct evidence of the etiological connection between autoimmunity and subsequent hazard of psychosis. Here, we advocate the use of term “autoimmune psychosis,” as this term suggests that autoimmune disorders can masquerade as drug-resistant primary psychosis, and this subtype of psychosis has anatomical and immunological footprints in the brain, despite the frequent absence of structural abnormalities on conventional brain MRI. Furthermore, this term might serve as a reminder not to overlook appropriate neurological workup such as neuroimaging and EEG testing, as well as CSF analysis, for cases with acute or subacute atypical onset of neuropsychiatric presentations including those dominated by acute psychotic symptoms. We propose etiologically and serologically oriented subclassification as well as multi-modal diagnostic approach to address some of the challenges inherent to early diagnosis of patients presenting with atypical and refractory new-onset psychotic symptoms of autoimmune origin. This is particularly relevant to the diagnosis of seronegative but probable autoimmune psychosis (SPAP) that might masquerade as antipsychotic drug-resistant primary psychotic disorder. This distinction is therapeutically important as autoimmune-related psychotic symptomatology can frequently respond well to timely treatment with proper immune modulatory therapies.

Ethical Implications of the Mild Encephalitis Hypothesis of Schizophrenia

Schizophrenia is a serious mental disease with a high mortality rate and severe social consequences. Due to insufficient knowledge about its etiopathogenesis, curative treatments are not available. One of the most promising new research concepts is the mild encephalitis hypothesis of schizophrenia, developed mainly by Karl Bechter and Norbert Müller. According to this hypothesis, a significant subgroup of schizophrenia patients suffer from a mild, but chronic, form of encephalitis with markedly different etiologies ranging from viral infections, traumas to autoimmune diseases. This inflammatory process is thought to occur in the beginning or during the course of the disease. In this article, we investigate the consequences of the mild encephalitis hypothesis of schizophrenia for the scientific community, and evaluate these consequences ethically. The mild encephalitis hypothesis implies that schizophrenia would no longer be considered an incurable psychiatric disorder. Instead, it would be considered a chronic, but treatable, neurological disease. This paradigm shift would doubtlessly have significant consequences: (1) major reforms would be necessary in the theoretical conceptualization of schizophrenia, which would challenge the psychiatric diagnostic systems, Diagnostic and Statistical Manual of Mental Disorders version 5 and ICD-10. (2) Psychotic patients should be treated in interdisciplinary teams, optimally in neuropsychiatric units; additionally, specialists for endocrinology, diabetology, and cardiology should be consulted for the frequently occuring somatic comorbidities. (3) Current diagnostic procedures and (4) therapies would have to be modified significantly. (5) There might be repercussions for the pharmaceutical industry as well: first, because old drugs with expired patent protection could partly replace expensive drugs and, second, because there would be a demand for the development of new anti-inflammatory drugs. (6) Legal evaluation of compulsory treatment orders might have to be reconsidered in light of causal therapies; leading to increased legal approval and reduced need for compulsory treatment orders due to better patient compliance. (7) The social inclusion of patients might improve, if treatment became more effective regarding cognitive and social functioning. (8) The stigmatization of patients and their relatives might decrease.

Schizophrenia or Atypical Lupus Erythematosus with Predominant Psychiatric Manifestations over 25 Years: Case Analysis and Review

We observed a case over 25 years of relapsing-remitting schizophrenic spectrum disorder, varying regarding the main symptomatology between more depressive or more schizoaffective or rather typical schizophrenic syndrome. Diseased phases were repeatedly accompanied by minor skin lesions, which were initially classified as mixed tissue disorder. Psychotic phases were waxing-waning over years. During one later relapse, skin involvement was severe, classified to likely represent an allergic reaction to psychopharmaca; this generalized exanthema remitted rapidly with cortisone treatment and azathioprine. Under continued azathioprine and low dose neuroleptics, the patient remitted completely, appearing psychiatrically healthy for 16 years. When azathioprine was set off due to pregnancy, an extraordinary severe relapse of schizophrenia like psychosis accompanied by most severe skin lesions developed within a few weeks, then requiring 2 years of psychiatric inpatient treatment. Finally, a diagnosis of systemic lupus erythematodes plus neuropsychiatric lupus was made. A single CSF sample in 2013 showed suspicious biomarkers, matching with CSF cytokine profiling in schizophrenic and affective spectrum disorder patients and indicated mild neuroinflammation. Complex immune suppressive treatment was reinitiated short after relapse, but was only partially successful. However, surprisingly the psychosis and skin lesions remitted (in parallel) when belimumab was given (add-on). The very details of this complicated, long-term disease course are discussed also with regard to general ideas, in particular with respect to the question if this case of seemingly comorbid schizophrenia with minor autoimmunity signs represented a case of one emerging autoimmune disorder with variant manifestations systemically and within the CNS, though atypically with predominant appearance as a schizophrenia spectrum disorder.

Suspected antibody negative autoimmune limbic encephalitis: outcome of immunotherapy

OBJECTIVES

Whether and when to immunologically treat epilepsy patients with suggested autoantibody (AB)-negative limbic encephalitis (LE) is clinically challenging. Therefore, we evaluated the clinical outcome and eventual outcome predictors of immunotherapy in a group of AB-negative patients with recent-onset temporal lobe epilepsy (TLE), magnetic resonance imaging (MRI) indicators of LE, subjective cognitive decline, and/or psychiatric symptoms.

METHODS

This retrospective, observational, uncontrolled study monitored 28 TLE patients with suggested AB-negative LE along with methylprednisolone immunotherapy.

RESULTS

All patients had seizures, amygdala and/or -hippocampal enlargement, subjective cognitive decline and/or behavioral problems. Eighty-six percent (24/28) were impaired in executive or memory functions, 39% (10/25) depressed, 81% were on antiepileptic drugs when pulse therapy started. After a median follow-up of 18 months, 46% (13/28) of the patients were seizure free (>2 months), 48% (13/27) showed MRI improvements (amygdala and/or hippocampal volume reduction), cognition improved in 57% (16/28), worsened in 32% (9/28), mood improved in 14% (4/25), and deteriorated in 11% (3/25). Immunotherapy was discontinued in 75% (21/28). Clinical changes did not correlate to each other. Outcomes could not be predicted.

CONCLUSION

Immunological treatment of suggested AB-negative LE showed reasonable seizure control, MRI and cognitive improvements. Treatment success was not predictable from clinical features, nor definitely attributable to immunological treatment. Lacking biomarkers for the reliable diagnosis of AB-negative LE, we suggest that in presence of mild manifestations, and after initiating antiepileptic drug therapy, negative dynamics in MRI, seizures, cognition, and behavior should be documented before immunosuppressive treatment is initiated.

IL1R2, CCR2, and CXCR4 May Form Heteroreceptor Complexes with NMDAR and D2R: Relevance for Schizophrenia

The mild neuroinflammation hypothesis of schizophrenia was introduced by Bechter in 2001. It has been hypothesized that a hypofunction of glutamatergic signaling via N-methyl-D-aspartate receptors (NMDARs) and hyperactivation of dopamine D2 receptors play a role in schizophrenia. The triplet puzzle theory states that sets of triplet amino acid homologies guide two different receptors toward each other and contributes to the formation of a receptor heteromer. It is, therefore, proposed that putative NMDAR-C-C chemokine receptor type 2 (CCR2), NMDAR-C-X-C chemokine receptor type 4 (CXCR4), and NMDAR- interleukin 1 receptor type II (IL1R2) heteromers can be formed in the neuronal networks in mild neuroinflammation due to demonstration of Gly-Leu-Leu (GLL), Val-Ser-Thr (VST), and/or Ser-Val-Ser (SVS) amino acid homologies between these receptor protomers. This molecular process may underlie the ability to produce symptoms of schizophrenia in mild neuroinflammation. In this state, volume transmission (VT) is increased involving increased extracellular vesicle-mediated VT from microglia and astroglia. These vesicles may contain CCR2, CXCR4, and/or IL1R2 as well as their ligands and upon internalization by endocytic pathways into neurons can form heteroreceptor complexes with NMDAR in the plasma membrane with pathological allosteric receptor-receptor interactions involving increased internalization and reduced NMDAR signaling. The triplet puzzle theory also suggests the formation of putative D2R-CCR2, D2R-CXCR4, and D2R-IL1R2 heteromers in mild neuroinflammation in view of their demonstrated sets of Leu-Tyr-Ser (LYS), Leu-Pro-Phe (LPF), and/or Ser-Leu-Ala (SLA) triplet homologies. These D2R heteroreceptor complexes may also contribute to schizophrenia-like symptoms in mild neuroinflammation by enhancing D2R protomer function.

New-Onset Refractory Status Epilepticus: More Investigations, More Questions

A 27-year-old previously healthy woman was admitted to the hospital with recurrent seizures. Status epilepticus developed that became refractory to third-line therapy with propofol and barbiturates. The patient had a very extensive diagnostic workup including autoimmune, viral and genetic investigations. A tentative immune therapy was proposed with high doses of steroids and plasma exchanges. Our patient had an inherited heterozygous single nucleotide variant in the sequence c.1280A>G [p.Lys427Arg] of the SMC3 gene that was insufficient to explain the seizures. Surprisingly, IgM antibodies against Japanese encephalitis virus were positive on the serum drawn 11 days after symptom onset, as detected by ELISA and the immunofluorescence antibody (IFA) technique. IgG antibodies were also positive using the IFA technique, but not with ELISA. The same investigations as well as the detection of the viral genome by the q-RT-PCR technique were negative on cerebrospinal fluid. Despite the suspicion of a viral infection, we concluded that our patient had a new-onset refractory status epilepticus of cryptogenic origin. Termination of the status epilepticus was obtained after 47 days, with a possible benefit from the introduction of ketamine.

NMDA Receptor Internalization by Autoantibodies: A Reversible Mechanism Underlying Psychosis?

Since the early 1990s it has been postulated that hypofunction of N-methyl-d-aspartate (NMDA) receptors in brain networks supporting perception and cognition underlies schizophrenic psychosis. Recently, NMDA receptor hypofunction was described in patients with psychotic manifestations who exhibited autoantibodies binding the GluN1 subunit of the receptor, and who improved when the level of these antibodies was lowered by immunomodulation. In this disorder, NMDA receptor antibodies decrease the availability of NMDA receptors by internalizing them. In this opinion article, we review this mechanism as well as data supporting or refuting the possibility that this disorder or similar autoimmune disorders affecting synaptic proteins, which are therefore treatable with immunomodulation, could account for some cases of idiopathic psychosis. We also suggest methodological approaches to clarify this issue.

Neuroinflammation and psychiatric illness

Multiple lines of evidence support the pathogenic role of neuroinflammation in psychiatric illness. While systemic autoimmune diseases are well-documented causes of neuropsychiatric disorders, synaptic autoimmune encephalitides with psychotic symptoms often go under-recognized. Parallel to the link between psychiatric symptoms and autoimmunity in autoimmune diseases, neuroimmunological abnormalities occur in classical psychiatric disorders (for example, major depressive, bipolar, schizophrenia, and obsessive-compulsive disorders). Investigations into the pathophysiology of these conditions traditionally stressed dysregulation of the glutamatergic and monoaminergic systems, but the mechanisms causing these neurotransmitter abnormalities remained elusive. We review the link between autoimmunity and neuropsychiatric disorders, and the human and experimental evidence supporting the pathogenic role of neuroinflammation in selected classical psychiatric disorders. Understanding how psychosocial, genetic, immunological and neurotransmitter systems interact can reveal pathogenic clues and help target new preventive and symptomatic therapies.