Stacey Clardy

Anti-Yo Antibody Uptake and Interaction with Its Intracellular Target Antigen Causes Purkinje Cell Death in Rat Cerebellar Slice Cultures: A Possible Mechanism for Paraneoplastic Cerebellar Degeneration in Humans with Gynecological or Breast Cancers

Anti-Yo antibodies are immunoglobulin G (IgG) autoantibodies reactive with a 62 kDa Purkinje cell cytoplasmic protein. These antibodies are closely associated with paraneoplastic cerebellar degeneration in the setting of gynecological and breast malignancies. We have previously demonstrated that incubation of rat cerebellar slice cultures with patient sera and cerebrospinal fluid containing anti-Yo antibodies resulted in Purkinje cell death. The present study addressed three fundamental questions regarding the role of anti-Yo antibodies in disease pathogenesis: 1) Whether the Purkinje cell cytotoxicity required binding of anti-Yo antibody to its intraneuronal 62 kDa target antigen; 2) whether Purkinje cell death might be initiated by antibody-dependent cellular cytotoxicity rather than intracellular antibody binding; and 3) whether Purkinje cell death might simply be a more general result of intracellular antibody accumulation, rather than of specific antibody-antigen interaction. In our study, incubation of rat cerebellar slice cultures with anti-Yo IgG resulted in intracellular antibody binding, and cell death. Infiltration of the Purkinje cell layer by cells of macrophage/microglia lineage was not observed until extensive cell death was already present. Adsorption of anti-Yo IgG with its 62 kDa target antigen abolished both antibody accumulation and cytotoxicity. Antibodies to other intracellular Purkinje cell proteins were also taken up by Purkinje cells and accumulated intracellularly; these included calbindin, calmodulin, PCP-2, and patient anti-Purkinje cell antibodies not reactive with the 62 kDa Yo antigen. However, intracellular accumulation of these antibodies did not affect Purkinje cell viability. The present study is the first to demonstrate that anti-Yo antibodies cause Purkinje cell death by binding to the intracellular 62 kDa Yo antigen. Anti-Yo antibody cytotoxicity did not involve other antibodies or factors present in patient serum and was not initiated by brain mononuclear cells. Purkinje cell death was not simply due to intraneuronal antibody accumulation.

Neuronal uptake of anti-Hu antibody, but not anti-Ri antibody, leads to cell death in brain slice cultures

BackgroundAnti-Hu and anti-Ri antibodies are paraneoplastic immunoglobulin (Ig)G autoantibodies which recognize cytoplasmic and nuclear antigens present in all neurons. Although both antibodies produce similar immunohistological labeling, they recognize different neuronal proteins. Both antibodies are associated with syndromes of central nervous system dysfunction. However, the neurological deficits associated with anti-Hu antibody are associated with neuronal death and are usually irreversible, whereas neurological deficits in patients with anti-Ri antibody may diminish following tumor removal or immunosuppression.MethodsTo study the effect of anti-Hu and anti-Ri antibodies on neurons, we incubated rat hippocampal and cerebellar slice cultures with anti-Hu or anti-Ri sera from multiple patients. Cultures were evaluated in real time for neuronal antibody uptake and during prolonged incubation for neuronal death. To test the specificity of anti-Hu antibody cytotoxic effect, anti-Hu serum IgG was incubated with rat brain slice cultures prior to and after adsorption with its target Hu antigen, HuD.ResultsWe demonstrated that: 1) both anti-Hu and anti-Ri antibodies were rapidly taken up by neurons throughout both cerebellum and hippocampus; 2) antibody uptake occurred in living neurons and was not an artifact of antibody diffusion into dead cells; 3) intracellular binding of anti-Hu antibody produced neuronal cell death, whereas uptake of anti-Ri antibody did not affect cell viability during the period of study; and 4) adsorption of anti-Hu antisera against HuD greatly reduced intraneuronal IgG accumulation and abolished cytotoxicity, confirming specificity of antibody-mediated neuronal death.ConclusionsBoth anti-Hu and anti-Ri antibodies were readily taken up by viable neurons in slice cultures, but the two antibodies differed markedly in terms of their effects on neuronal viability. The ability of anti-Hu antibodies to cause neuronal death could account for the irreversible nature of paraneoplastic neurological deficits in patients with this antibody response. Our results raise questions as to whether anti-Ri antibody might initially induce reversible neuronal dysfunction, rather than causing cell death. The ability of IgG antibodies to access and react with intracellular neuronal proteins could have implications for other autoimmune diseases involving the central nervous system.

NMDAR Encephalitis Following Herpes Simplex Virus Encephalitis

Purpose of ReviewHerpes simplex virus encephalitis (HSVE) is often associated with significant morbidity and mortality, and despite appropriate treatment with antivirals, worsening of neurological symptoms or relapse occurs in a subset of patients. Recent data suggests that many relapses are likely caused by a secondary immune response, with the N-methyl-D-aspartate receptor (NMDAR) antibody being the most commonly associated autoantibody. We provide a review of the relevant literature, examining the relationship between HSVE and development of autoimmunity.Recent FindingsAutoantibodies, including pathogenic NMDAR antibody, have been demonstrated in the cerebrospinal fluid (CSF) of patients following HSVE. This occurs usually several weeks following initial HSV infection.SummaryThere is growing evidence of a relationship between HSVE and the subsequent development of NMDAR encephalitis. Possible mechanisms include molecular mimicry or an immune response to direct neuronal damage. Future studies should address if the use of immunotherapy can prevent the development of autoimmunity following HSVE.

Voltage-gated calcium channel autoimmune cerebellar degeneration: Case and study of cytotoxicity.

Objectives: To describe response to treatment in a patient with autoantibodies against voltage-gated calcium channels (VGCCs) who presented with autoimmune cerebellar degeneration and subsequently developed Lambert-Eaton myasthenic syndrome (LEMS), and to study the effect of the patients autoantibodies on Purkinje cells in rat cerebellar slice cultures. Methods: Case report and study of rat cerebellar slice cultures incubated with patient VGCC autoantibodies. Results: A 53-year-old man developed progressive incoordination with ataxic speech. Laboratory evaluation revealed VGCC autoantibodies without other antineuronal autoantibodies. Whole-body PET scans 6 and 12 months after presentation detected no malignancy. The patient improved significantly with IV immunoglobulin G (IgG), prednisone, and mycophenolate mofetil, but worsened after IV IgG was halted secondary to aseptic meningitis. He subsequently developed weakness with electrodiagnostic evidence of LEMS. The patients IgG bound to Purkinje cells in rat cerebellar slice cultures, followed by neuronal death. Reactivity of the patients autoantibodies with VGCCs was confirmed by blocking studies with defined VGCC antibodies. Conclusions: Autoimmune cerebellar degeneration associated with VGCC autoantibodies may precede onset of LEMS and may improve with immunosuppressive treatment. Binding of anti-VGCC antibodies to Purkinje cells in cerebellar slice cultures may be followed by cell death. Patients with anti-VGCC autoantibodies may be at risk of irreversible neurologic injury over time, and treatment should be initiated early.

Lambert–Eaton myasthenic syndrome: Epidemiology and therapeutic response in the national veterans affairs population

One nationwide study (The Netherlands) of Lambert–Eaton myasthenic syndrome (LEMS) has been published. We report LEMS epidemiology and its therapeutic response in the United States Veterans Affairs (VA) population.

Antineuronal Nuclear Autoantibody Type 1/Anti-Hu-Associated Opsoclonus Myoclonus and Epilepsia Partialis Continua: Case Report and Literature Review.

BACKGROUND Opsoclonus-myoclonus syndrome is a rare clinical condition that has been associated with neuroblastoma. There are few reported examples of ANNA-1/anti-Hu antibodies in children with neuroblastoma and opsoclonus-myoclonus, all in children aged less than three years of age. METHODS We describe the new onset of focal seizures without alteration of consciousness and opsoclonus-myoclonus in an 11-year-old girl with ANNA-1/anti-Hu positivity and a paraspinal ganglioneuroblastoma. A systematic review of the literature of children with ANNA-1/anti-Hu positivity and malignancy was also performed. RESULTS Fourteen patients were identified, eight of whom had opsoclonus-myoclonus. Although epilepsia partialis continua has been described in association with several neuronal autoantibodies, association with ANNA-1/anti-Hu has not been reported. CONCLUSIONS We describe epilepsia partialis continua in a child with ANNA-1/anti-Hu antibodies and neuroblastoma. Testing for antineuronal antibodies should be considered in children presenting with either opsoclonus-myoclonus or epilepsia partialis continua.

Improvement of GAD65-associated autoimmune epilepsy with testosterone replacement therapy

Treatment response in autoimmune epilepsy is variable. Achieving seizure reduction is often dependent on the specific neuronal antibody.1,2 Glutamic acid decarboxylase 65 (GAD65)-associated epilepsy is among the most challenging of the autoimmune epilepsies to treat, often requiring multiple antiepileptic drugs (AEDs) and aggressive immunotherapy to attain a reduction in seizure frequency.3

Adult-onset Opsoclonus-Myoclonus Syndrome Associated With Ganglionic Acetylcholine Receptor Autoantibody.

Introduction:Opsoclonus-myoclonus syndrome (OMS) may have a toxin induced, parainfectious, or paraneoplastic etiology. Several autoantibodies have been associated with adult-onset OMS, most commonly antineuronal nuclear antibody 2 (Ri), and it is most frequently associated with breast or small cell lung cancer. The nicotinic ganglionic acetylcholine receptor autoantibody (&agr;3-AChR Ab) has not been described in association. Case Report:A 46-year-old woman was evaluated for symptoms of oscillopsia, tremor, gait imbalance, and mild cognitive deficits that began 6 weeks prior. Neurological examination demonstrated opsoclonus, myoclonus, and mild gait ataxia. Laboratory evaluation revealed an elevated &agr;3-AChR Ab at 0.27 nmol/L (normal ⩽0.02 nmol/L) with no other autoantibodies or infectious etiology detected. Thorough screening revealed no evidence of associated malignancy. Immunotherapy with weekly methylprednisolone led to significant improvement. Conclusions:This first reported case of &agr;3-AChR Ab positivity in the setting of adult-onset OMS expands the spectrum of associated autoantibodies. The mechanism of disease may be linked to cholinergic nuclei within the brainstem. This case suggests including &agr;3-AChR Ab in the evaluation of adult-onset OMS, and highlights the importance of further understanding &agr;3-AChR within the brain.

Infection, Immunodeficiency, and Inflammatory Diseases in Autoimmune Neurology

Abstract When patients present with neurological syndromes, such as encephalopathy/encephalitis, meningitis, and/or myelopathy/myelitis, the differential diagnosis is often broad, including infectious, inflammatory, autoimmune, vascular, and neoplastic etiologies. Just with inflammatory and autoimmune etiologies alone, there are numerous causative diseases. A comprehensive history and physical examination investigating for extraneurologic manifestations of immune‐mediated disease is often necessary. Moreover, evaluating for an underlying infection and/or immunodeficiency becomes a critical aspect to the workup. This article will focus on the association of viral infections and dysregulation of the immune system as triggers of autoimmunity, in addition to various systemic inflammatory diseases that can cause neurological disease either with or without an established rheumatological disorder.

Stiff Person Syndrome with Anti-GAD65 Antibodies Within the National Veterans Affairs Health Administration: Stiff Person in the National VA

Introduction: Stiff person syndrome (SPS) is a neurological disorder characterized by muscle rigidity primarily in the truncal muscles, commonly associated with autoantibodies to the glutamic acid‐decarboxylase 65 kD receptor (GAD65). There is limited epidemiological information on patients with SPS. Methods: We performed a retrospective case review using the National United States Veterans Affairs Health Administration electronic medical record system. We analyzed prevalence, demographics, disease characteristics, and treatment outcomes in SPS patients who were anti‐GAD65 antibody positive. Results: Fifteen patients met our criteria. Point prevalence was 2.06 per million, and period prevalence was 2.71 per million. Men to women ratio was 14:1. All patients benefitted from treatment with symptomatic antispasmodic agents. Ten of 15 patients received intravenous immunoglobulin, with a majority demonstrating stable or improved modified Rankin scores. Discussion: This investigation was a large North American epidemiological study of SPS with predominantly male patients. Symptomatic therapy was beneficial for most patients, with less clear sustained benefit of immunotherapy. Muscle Nerve 58:801–804, 2018