Summary: Researchers uncovered the fundamental mechanism behind IgLON5 encephalitis (Anti-IgLON5 disease). By testing patient-derived antibodies in cell cultures and mice, researchers established a direct causal link between autoimmune attacks on the surface protein IgLON5 and the toxic aggregation of Tau proteins inside neurons.
The breakthrough reveals that the disease is driven by abnormal neuronal hyperactivity, providing a fresh target for future therapeutic interventions.
Key Facts
- The Causal Link Discovered: Rogue antibodies target the cell surface protein IgLON5, forcing these proteins to cluster with other molecules on the cell surface and igniting a fatal intracellular cascade.
- Neuronal Hyperactivity: This surface clustering triggers abnormal neuronal hyperactivity, which researchers identified for the first time as the primary driver of subsequent neurodegeneration.
- Tau Pathology Trigger: The induced hyperactivity causes Tau proteins to detach from the neuronal cytoskeleton, mislocalize, and form toxic aggregates—a hallmark process that mirrors Tau pathology in Alzheimer’s disease.
- Therapeutic Implications: Because Anti-IgLON5 disease features a complex phenotype that often evades early diagnosis, targeting and alleviating this newly discovered hyperactivity dysfunction offers a completely new path for future treatments.
Source: DZNE
In a condition known as “IgLON5 encephalitis”, the immune system mistakenly attacks cells in the brain. This leads to brain inflammation and neuronal damage, which can manifest as sleep disturbances, cognitive impairment, and movement disorders.
Researchers at DZNE and Charité – Universitätsmedizin Berlin have now identified fundamental mechanisms underlying this rare but severe neurodegenerative disease.
Their findings, based on applying antibodies from affected individuals in neuronal cell cultures and mice, have been published in the journal Science Advances.
The disease involves rogue antibodies directed against a cell surface protein called IgLON5. However, until now it was unclear, how this interaction gives rise to a hallmark of the disease. Namely, how the antibodies lead to aggregation of another protein known as “Tau”.
“Now, we found that the aberrant antibodies cause IgLON5 proteins to cluster with other molecules on the cell surface. This triggers abnormal neuronal hyperactivity and a fatal cascade that ultimately results in Tau mislocalization and aggregation.
“In other words, our findings establish a causal link between the IgLON5 antibodies and Tau pathology”, Prof. Susanne Wegmann, a research group leader at DZNE and Charité, explains.
Tau proteins that detach from the cytoskeleton and aggregate can initiate cell toxicity and ultimately neuronal degeneration. Pathological Tau protein aggregation also plays a major role in Alzheimer’s disease: There, too, neuronal hyperactivity – in that case triggered by misfolded amyloid-beta proteins – is suspected to induce pathology Tau changes.
“These similarities will now need to be examined more closely”, says Wegmann.
A potential treatment approach
The specific form of encephalitis currently under investigation, also known as “Anti-IgLON5 disease”, was first documented in 2014 and is quite rare. Due to its complex phenotype, which includes a wide range of possible symptoms, the disease tends to escape early diagnosis.
Current treatments options comprise immunosuppression, dialysis, and other approaches. The disease leads to severe disabilities, if untreated, and may result in premature death.
“Our findings identified neuronal hyperactivity as a driver of the disease. This aspect was previously unknown. Alleviating this dysfunction could be a target for future therapies,” the Berlin biophysicist concludes.
Key Questions Answered:
A: First documented in 2014, it is a rare but severe autoimmune condition where the body attacks its own brain cells. It causes brain inflammation and nerve damage, showing up as sleep issues, cognitive decline, and movement disorders. If left untreated, it leads to severe disability or premature death.
A: It acts like a toxic chain reaction. When the rogue antibodies bind to the IgLON5 proteins on the cell surface, they force them to cluster together. This clustering sends an erratic signal into the neuron, making it hyperactive. That extreme stress causes internal Tau proteins to break away from the cell’s scaffolding and clump together.
A: Yes. In Alzheimer’s, neuronal hyperactivity (triggered by amyloid-beta) is also suspected of driving toxic Tau aggregation. Because both diseases share this exact hyperactivity-to-Tau pipeline, studying how to stop it in IgLON5 encephalitis could yield vital crossover insights for treating Alzheimer’s.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by our staff.
About this neurology research news
Author: Marcus Neitzert
Source: DZNE
Contact: Marcus Neitzert – DZNE
Image: The image is credited to Neuroscience News
Original Research: Open access.
“IgLON5 autoimmune antibodies activate Tau via neuronal hyperactivity” by Bilge Askin, Cagla Kilic, César Cordero Gómez, Sophie Lan-Linh Duong, Alvaro Domingues-Baquero, Alexander Goihl, Karsten Nalbach, Joana Petushi, Pia Grundschöttel, Jessica Wagner, Valentine Thomas, Janne Lamberty, Emily Withers, Hanna Huber, Sabrina Huebschmann, Ekaterina Semenova, Paul Turko, Andrew G. Newman, Lisa Diez, Marc Beyer, Elena De Domenico, Peter Körtvelyessy, Dirk Reinhold, Anja Schneider, Jonas J. Neher, Thomas Ulas, Stefan F. Lichtenthaler, Benjamin R. Rost, Dietmar Schmitz, Harald Prüss, and Susanne Wegmann. Science Advances
DOI:10.1126/sciadv.aec2042
Abstract
IgLON5 autoimmune antibodies activate Tau via neuronal hyperactivity
Anti-IgLON5 disease is an autoimmune disease, in which autoantibodies (AABs) against the neuronal cell surface protein IgLON5 lead to profound brain dysfunction and Tau pathology. How α-IgLON5 AABs cause neuronal Tau protein pathology and neurodegeneration remains unclear.
We find that patient-derived α-IgLON5 AABs cluster IgLON5 proteins with other cell surface proteins, leading to neuronal hyperactivity that triggers pathological Tau missorting and phosphorylation, typically observed early in Tau-related neurodegenerative diseases. In wild-type mice, α-IgLON5 AABs induce hippocampal Tau phosphorylation and neuroinflammatory responses.
Our findings establish a causal link between the α-IgLON5 AABs and Tau pathology in anti-IgLON5 disease patients and highlight the role of neuronal hyperactivity as a disease-overarching driver of Tau pathology and provide a potential target for therapeutic intervention.
