Adaptive immunity cells are differentially distributed in the peripheral blood of glycine receptor antibody-positive patients with focal epilepsy of unknown cause

The correlation of GluR3B antibody with T lymphocyte subsets and inflammatory factors and their role in the progression of epilepsy

OBJECTIVE

To investigate changes in proportions of peripheral blood lymphocyte subsets, the correlation between the lymphocyte subsets and cytokine levels in patients with GluR3B antibody-positive epilepsy, analyze the role of GluR3B antibodies and cytokines in the progression of epilepsy. In addition, the immunotherapeutic effect in patients with GluR3B antibody-positive epilepsy will be evaluated.

METHODS

Patients with epilepsy hospitalized in the Department of Neurology of the affiliated Hospital of Xuzhou Medical University from December 2016 to May 2023 were recruited. GluR3B antibody levels were measured by enzyme-linked immunosorbent assay (ELISA). Lymphocyte subset proportions were determined using flow cytometry, and serum concentrations of 12 cytokines were measured using cytometric beads array. Differences in T lymphocyte subsets and inflammatory factors were analysed between GluR3B antibody positive and negative patients. Structural equation modeling (SEM) was used to analyse the role of GluR3B antibodies and inflammatory factors in drug-resistant epilepsy (DRE). Finally, the therapeutic effect of immunotherapy on epilepsy patients with GluR3B antibodies was assessed.

RESULTS

In this study, sixty-four cases of DRE, sixty-six cases of drug-naïve epilepsy (DNE), and forty-one cases of drug-responsive epilepsy were recruited. (1) DRE patients with positive GluR3B antibody were characterized by a significant increase in the proportion of cluster of differentiation (CD)4+ T lymphocytes, a decrease in CD8+ T lymphocytes, and an increase of CD4+/CD8+ ratio. Similar alterations in T lymphocyte subsets were observed in GluR3B antibody-positive patients with DNE. GluR3B antibody levels correlated positively with CD4+ T lymphocytes (r = 0.23) and negatively with CD8+ T lymphocytes (r=-0.18). (2) In patients with DRE, the serum concentrations of interleukin-1β (IL-1β), IL-8, and interferon-gamma (IFN-γ) were significantly higher in those with positive GluR3B antibody compared to those with negative GluR3B antibody. Serum IL-1β levels were also higher in GluR3B antibody-positive DNE patients compared to antibody-negative DNE patients. In drug-responsive epilepsy patients with GluR3B antibody-positive, both serum IL-1β and IFN-γ levels were higher than those with GluR3B antibody-negative. Moreover, the concentrations of serum GluR3B antibody were positively correlated with the levels of IL-1β, IL-8, and IFN-γ. (3) SEM analysis indicated that GluR3B antibody may be a direct risk factor for DRE (direct effect = 4.479, 95%CI 0.409-8.503), or may be involved in DRE progression through affecting IFN-γ and IL-8 levels (total indirect effect = 5.101, 95%CI 1.756-8.818). (4) Immunotherapy significantly decreased seizure frequency and serum GluR3B antibody levels, and the seizure frequency was positively correlated with the levels of GluR3B antibody levels in patients receiving immunotherapy.

CONCLUSIONS

This study demonstrates that GluR3B antibody may influence the progression of epilepsy through altering the proportion of CD4+ and CD8+ lymphocyte subsets and increasing proinflammatory cytokines. The seizure suppression of immunotherapy is associated with the decrease of GluR3B antibody levels. Thus, the present study contributes to a better understanding of the immunoregulatory mechanisms of autoimmune-associated epilepsy and provides a potential target for DRE.

Clinical features in antiglycine receptor antibody-related disease: a case report and update literature review

Background and objectives

Antiglycine receptor (anti-GlyR) antibody mediates multiple immune-related diseases. This study aimed to summarize the clinical features to enhance our understanding of anti-GlyR antibody-related disease.

Methods

By collecting clinical information from admitted patients positive for glycine receptor (GlyR) antibody, the clinical characteristics of a new patient positive for GlyR antibody were reported in this study. To obtain additional information regarding anti-GlyR antibody-linked illness, clinical data and findings on both newly reported instances in this study and previously published cases were merged and analyzed.

Results

A new case of anti-GlyR antibody-related progressive encephalomyelitis with rigidity and myoclonus (PERM) was identified in this study. A 20-year-old man with only positive cerebrospinal fluid anti-GlyR antibody had a good prognosis with first-line immunotherapy. The literature review indicated that the common clinical manifestations of anti-GlyR antibody-related disease included PERM or stiff-person syndrome (SPS) (n = 179, 50.1%), epileptic seizure (n = 94, 26.3%), and other neurological disorders (n = 84, 24.5%). Other neurological issues included demyelination, inflammation, cerebellar ataxia and movement disorders, encephalitis, acute psychosis, cognitive impairment or dementia, celiac disease, Parkinson's disease, neuropathic pain and allodynia, steroid-responsive deafness, hemiballism/tics, laryngeal dystonia, and generalized weakness included respiratory muscles. The group of PERM/SPS exhibited a better response to immunotherapy than others.

Conclusions

The findings suggest the presence of multiple clinical phenotypes in anti-GlyR antibody-related disease. Common clinical phenotypes include PERM, SPS, epileptic seizure, and paraneoplastic disease. Patients with RERM/SPS respond well to immunotherapy.

Glycine Receptor β-Targeting Autoantibodies Contribute to the Pathology of Autoimmune Diseases

BACKGROUND AND OBJECTIVES

Stiff-person syndrome (SPS) and progressive encephalomyelitis with rigidity and myoclonus (PERM) are rare neurologic disorders of the CNS. Until now, exclusive GlyRα subunit-binding autoantibodies with subsequent changes in function and surface numbers were reported. GlyR autoantibodies have also been described in patients with focal epilepsy. Autoimmune reactivity against the GlyRβ subunits has not yet been shown. Autoantibodies against GlyRα1 target the large extracellular N-terminal domain. This domain shares a high degree of sequence homology with GlyRβ making it not unlikely that GlyRβ-specific autoantibody (aAb) exist and contribute to the disease pathology.

METHODS

In this study, we investigated serum samples from 58 patients for aAb specifically detecting GlyRβ. Studies in microarray format, cell-based assays, and primary spinal cord neurons and spinal cord tissue immunohistochemistry were performed to determine specific GlyRβ binding and define aAb binding to distinct protein regions. Preadsorption approaches of aAbs using living cells and the purified extracellular receptor domain were further used. Finally, functional consequences for inhibitory neurotransmission upon GlyRβ aAb binding were resolved by whole-cell patch-clamp recordings.

RESULTS

Among 58 samples investigated, cell-based assays, tissue analysis, and preadsorption approaches revealed 2 patients with high specificity for GlyRβ aAb. Quantitative protein cluster analysis demonstrated aAb binding to synaptic GlyRβ colocalized with the scaffold protein gephyrin independent of the presence of GlyRα1. At the functional level, binding of GlyRβ aAb from both patients to its target impair glycine efficacy.

DISCUSSION

Our study establishes GlyRβ as novel target of aAb in patients with SPS/PERM. In contrast to exclusively GlyRα1-positive sera, which alter glycine potency, aAbs against GlyRβ impair receptor efficacy for the neurotransmitter glycine. Imaging and functional analyses showed that GlyRβ aAbs antagonize inhibitory neurotransmission by affecting receptor function rather than localization.

Peripheral blood regulatory B and T cells are decreased in patients with focal epilepsy

Patients with focal epilepsy of unknown cause (FEoUC) may display T cell infiltration in post-surgery brain specimens and increased serum levels of pro-inflammatory cytokines produced by B and T cells, indicating potential involvement of adaptive immunity. Our study aimed to investigate the peripheral blood distribution of B and T cell subgroups to find clues supporting the distinct organization of adaptive immunity in FEoUC. Twenty-two patients with FEoUC and 25 age and sex matched healthy individuals were included. Peripheral blood mononuclear cells were immunophenotyped by flow cytometry. Expression levels of anti-inflammatory cytokines and FOXP3 were measured by real-time PCR. Carboxyfluorescein succinimidyl ester (CFSE) proliferation assay was conducted using CD4+ T cells. Patients with FEoUC showed significantly decreased regulatory B (Breg), B1a, plasmablast and regulatory T (Treg) cell percentages, and increased switched memory B and Th17 cell ratios. Moreover, CD4+CD25+CD49d- Tregs of FEoUC patients displayed significantly reduced TGFB1 and FOXP3, but increased IL10 gene expression levels. CD4+ helper T cells of patients with FEoUC gave more exaggerated proliferation responses to phytohemagglutinin, anti-CD3 and anti-CD28 stimulation. Patients with FEoUC display increased effector lymphocyte, decreased regulatory lymphocyte ratios, and impaired Treg function and enhanced lymphocyte proliferation capacity. Overall, this pro-inflammatory phenotype lends support to the involvement of adaptive immunity in FEoUC.