Dataset Information

Human stiff-person syndrome IgG induces anxious behavior in rats.

ABSTRACT:

Background

Anxiety is a heterogeneous behavioral domain playing a role in a variety of neuropsychiatric diseases. While anxiety is the cardinal symptom in disorders such as panic disorder, co-morbid anxious behavior can occur in a variety of diseases. Stiff person syndrome (SPS) is a CNS disorder characterized by increased muscle tone and prominent agoraphobia and anxiety. Most patients have high-titer antibodies against glutamate decarboxylase (GAD) 65. The pathogenic role of these autoantibodies is unclear.

Methodology/principal findings

We re-investigated a 53 year old woman with SPS and profound anxiety for GABA-A receptor binding in the amygdala with (11)C-flumazenil PET scan and studied the potential pathogenic role of purified IgG from her plasma filtrates containing high-titer antibodies against GAD 65. We passively transferred the IgG fraction intrathecally into rats and analyzed the effects using behavioral and in vivo electrophysiological methods. In cell culture, we measured the effect of patient IgG on GABA release from hippocampal neurons. Repetitive intrathecal application of purified patient IgG in rats resulted in an anxious phenotype resembling the core symptoms of the patient. Patient IgG selectively bound to rat amygdala, hippocampus, and frontal cortical areas. In cultured rat hippocampal neurons, patient IgG inhibited GABA release. In line with these experimental results, the GABA-A receptor binding potential was reduced in the patient's amygdala/hippocampus complex. No motor abnormalities were found in recipient rats.

Conclusion/significance

The observations in rats after passive transfer lead us to propose that anxiety-like behavior can be induced in rats by passive transfer of IgG from a SPS patient positive for anti-GAD 65 antibodies. Anxiety, in this case, thus may be an antibody-mediated phenomenon with consecutive disturbance of GABAergic signaling in the amygdala region.

SUBMITTER: Geis C

PROVIDER: S-EPMC3035624 | biostudies-literature | 2011 Feb

REPOSITORIES: biostudies-literature

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Publications

Human stiff-person syndrome IgG induces anxious behavior in rats.

Geis Christian C Weishaupt Andreas A Grünewald Benedikt B Wultsch Thomas T Reif Andreas A Gerlach Manfred M Dirkx Ron R Solimena Michele M Perani Daniela D Heckmann Manfred M Toyka Klaus V KV Folli Franco F Sommer Claudia C

PloS one 20110208 2

<h4>Background</h4>Anxiety is a heterogeneous behavioral domain playing a role in a variety of neuropsychiatric diseases. While anxiety is the cardinal symptom in disorders such as panic disorder, co-morbid anxious behavior can occur in a variety of diseases. Stiff person syndrome (SPS) is a CNS disorder characterized by increased muscle tone and prominent agoraphobia and anxiety. Most patients have high-titer antibodies against glutamate decarboxylase (GAD) 65. The pathogenic role of these auto ...[more]

PMID: 21346811

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Project description:IMPORTANCE:High titers of autoantibodies to glutamic acid decarboxylase (GAD) are well documented in association with stiff person syndrome (SPS). Glutamic acid decarboxylase is the rate-limiting enzyme in the synthesis of ?-aminobutyric acid (GABA), and impaired function of GABAergic neurons has been implicated in the pathogenesis of SPS. Autoantibodies to GAD might be the causative agent or a disease marker. OBJECTIVE:To investigate the characteristics and potential pathogenicity of GAD autoantibodies in patients with SPS and related disorders. DESIGN:Retrospective cohort study and laboratory investigation. SETTING:Weatherall Institute of Molecular Medicine, University of Oxford. PARTICIPANTS:Twenty-five patients with SPS and related conditions identified from the Neuroimmunology Service. EXPOSURES:Neurological examination, serological characterization and experimental studies. MAIN OUTCOMES AND MEASURES:Characterization of serum GAD antibodies from patients with SPS and evidence for potential pathogenicity. RESULTS:We detected GAD autoantibodies at a very high titer (median, 7500 U/mL) in 19 patients (76%), including all 12 patients with classic SPS. The GAD autoantibodies were high affinity (antibody dissociation constant, 0.06-0.78 nmol) and predominantly IgG1 subclass. The patients’ autoantibodies co-localized with GAD on immunohistochemistry and in permeabilized cultured cerebellar GABAergic neurons, as expected, but they also bound to the cell surface of unpermeabilized GABAergic neurons. Adsorption of the highest titer (700 000 U/mL) serum with recombinant GAD indicated that these neuronal surface antibodies were not directed against GAD itself. Although intraperitoneal injection of IgG purified from the 2 available GAD autoantibody–ositive purified IgG preparations did not produce clinical or pathological evidence of disease, SPS and control IgG were detected in specific regions of the mouse central nervous system, particularly around the lateral and fourth ventricles. CONCLUSIONS AND RELEVANCE:Autoantibodies to GAD are associated with antibodies that bind to the surface of GABAergic neurons and that could be pathogenic. Moreover, in mice, human IgG from the periphery gained access to relevant areas in the hippocampus and brainstem. Identification of the target of the non-GAD antibodies and peripheral and intrathecal transfer protocols, combined with adsorption studies, should be used to demonstrate the role of the non-GAD IgG in SPS.

Project description:ObjectiveIn stiff person syndrome (SPS), an antibody-mediated impaired γ-aminobutyric acidergic (GABAergic) neurotransmission is believed to cause muscle stiffness and spasms. Most patients improve with GABA-enhancing drugs and intravenous immunoglobulin, but some respond poorly and remain disabled. The need for more effective therapy prompted a trial with the anti-CD20 monoclonal antibody rituximab.MethodsThis was a placebo-controlled randomized trial of rituximab (2 biweekly infusions of 1g each). The primary outcome was a change in stiffness scores at 6 months. Secondary outcomes were changes in heightened-sensitivity and quality of life scores. Enrolling 24 patients was calculated to detect 50% change in stiffness scores.ResultsRandomization was balanced for age, sex, disease duration, and glutamic acid decarboxylase autoantibody titers. No significant changes were noted at 6 months after treatment in all outcomes. Specifically, no differences were noted in the stiffness index, the primary outcome, or sensitivity scores, the secondary outcome, at 3 or 6 months. Quality of life scores improved significantly (p < 0.01) at 3 months in both groups, but not at 6 months, denoting an early placebo effect. Blinded self-assessment rating of the overall stiffness for individual patients revealed improvement in 4 patients in each group. At 6 months, improvement persisted in 1 patient in the placebo group versus 3 of 4 in the rituximab group, where these meaningful improvements were also captured by video recordings.InterpretationThis is the largest controlled trial conducted in SPS patients and demonstrates no statistically significant difference in the efficacy measures between rituximab and placebo. Rituximab's lack of efficacy could be due to a considerable placebo effect; insensitivity of scales to quantify stiffness, especially in the less severely affected patients; or drug effectiveness in only a small patient subset. Ann Neurol 2017;82:271-277.

Dataset Information

Human stiff-person syndrome IgG induces anxious behavior in rats.

Background

Methodology/principal findings

Conclusion/significance

Publications

Human stiff-person syndrome IgG induces anxious behavior in rats.

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