Autoimmune Encephalitis (AE) is a rare neuro‑immune disorder characterised by central‑nervous‑system inflammation driven by dysregulated autoimmune responses. The immune system fails to distinguish self‑antigens from foreign threats and generates autoantibodies (alongside T‑cell responses) targeting neuronal surface or intracellular antigens. These immune effectors attack brain parenchyma, triggering an encephalitis syndrome manifested as psychiatric‑behavioural disturbances, cognitive decline, seizures and movement disorders.
AE was included in China’s First List of Rare Diseases in May 2018. Its annual incidence among European and North‑American populations stands at 0.8‑1.2 per 100 000 persons, with a prevalence of approximately 13.7 per 100 000, accounting for 10%‑20% of all non‑infectious encephalitis cases. Anti‑NMDAR encephalitis represents the most prevalent subtype, responsible for 40%‑80% of all AE cases. It occurs in both children and adults, with a high comorbidity rate of ovarian teratoma among young‑female patients.
Most patients with anti‑surface‑antigen AE (e.g. anti‑NMDAR, anti‑LGI1) achieve favourable outcomes if immunotherapy is initiated in the sub‑acute phase (within 3 months of symptom onset). Delayed diagnosis frequently leads to persistent cognitive impairment, drug‑resistant epilepsy or disease relapse. AE is therefore regarded as a treatable yet frequently misdiagnosed neurological rare disease.
Pathogenesis
AE arises from a cascade of pathological events: breakdown of immune tolerance → production of autoantibodies and sensitised T‑cells → blood‑brain‑barrier (BBB) penetration → targeting of neuronal antigens → collapse of synaptic and neuronal‑network function.
AE is divided into two major subgroups according to the subcellular localisation of target antigens:
- Anti‑neuronal surface / synaptic‑antigen subtypes (NMDAR, LGI1, GABABR, CASPR2, AMPAR): Antibodies themselves drive pathology. Upon antigen binding, they trigger receptor internalisation, reduced receptor density and impaired synaptic plasticity, with relatively limited neuronal necrosis. These subtypes generally respond well to immunotherapy.
- Anti‑intracellular neuronal‑antigen subtypes (Hu, Ma2, high‑titre GAD, etc.): Tissue damage is predominantly mediated by cytotoxic T‑cell responses, frequently associated with paraneoplastic conditions. Neuronal injury is severe, and responses to immunotherapy are limited.
Down‑stream pathological consequences include:
- Predominant injury to limbic structures (hippocampus, amygdala): recent‑memory loss, seizure episodes and psychiatric‑behavioural abnormalities.
- NMDAR internalisation: reduced excitatory neurotransmission, microglial activation, enhanced synaptic phagocytosis, manifesting as depressive‑like behaviours, cognitive retardation and involuntary movements.
- Hypothalamic or brain‑stem involvement: autonomic dysregulation including tachycardia, sialorrhoea, central hypoventilation and thermoregulatory disturbance.
- Preceding infections (e.g. HSV encephalitis) or tumours (teratoma, small‑cell lung carcinoma, thymoma) break immune tolerance via molecular mimicry or ectopic antigen release and initiate autoimmunity.
- Relapse risk persists in a subset of patients; the relapse rate of anti‑NMDAR encephalitis ranges from 12%‑31%, requiring long‑term immunological management.
Commonly Used Mouse Models for AE Research
AE mouse models fall into three major categories based on construction strategy: passive‑antibody‑transfer models, active‑immunisation models, and infection‑associated / humanised PBMC chimaeric models.
Passive‑transfer model IgG purified from cerebrospinal fluid or serum of anti‑NMDAR‑encephalitis patients is delivered to wild‑type mice via intracerebroventricular infusion or tail‑vein injection. This model rapidly recapitulates reduced surface NMDAR density, impaired hippocampal synaptic function, memory deficits and epileptiform discharges, directly demonstrating antibody‑mediated pathogenicity. However, it cannot faithfully reproduce T‑cell infiltration, sustained microglial activation or progressive BBB disruption. Symptoms are transient, making this system suitable for endpoint mechanistic validation.
Active‑immunisation model C57BL/6 mice are immunised with recombinant GluN1 peptides, conformation‑stabilised NMDAR tetramers (GluN1/GluN2B liposomes), or AAV‑GluN1 via oral or subcutaneous routes to induce endogenous anti‑NMDAR antibodies. This model recapitulates the full disease trajectory: autoantibody generation, BBB leakage, hippocampal inflammation and behavioural abnormalities. Deep cervical lymph nodes are identified as key niches for pathogenic B‑cells. It is well‑suited for evaluating therapeutic efficacy of glucocorticoids, IVIg, rituximab and JAK‑inhibitor candidates.
Post‑infection / humanised PBMC model
- Repeated intranasal inoculation with Group A Streptococcus recapitulates post‑infectious AE phenotypes, featuring Th17 cell brain infiltration, BBB disruption and olfactory‑circuit damage.
- Patient‑derived PBMCs are engrafted into immunodeficient strains such as Rag2⁻/⁻Il2rg⁻/⁻ mice to re‑constitute human B‑ and T‑cell compartments. These animals spontaneously generate anti‑GluN1 autoantibodies accompanied by IL‑1β‑driven BBB opening. This platform supports translational research and pre‑clinical testing of therapeutics such as IL‑1 receptor antagonists.
VeloGene Biotechnology Supports Neuro‑Immunological Disease Modelling
Gene therapy brings new hope for rare‑disease treatment; nevertheless, pre‑clinical validation using precise animal models remains indispensable.
Powered by our proprietary TurboMice™ technology, VeloGene Biotechnology has generated a broad portfolio of rare‑disease mouse models. TurboMice™ overcomes historical bottlenecks including lengthy model‑generation timelines and low success rates for complex alleles, enabling precise editing at defined genomic loci. Bypassing conventional breeding‑based screening, homozygous gene‑edited mouse models can be directly derived from embryonic stem cells in as little as two months.
Leveraging TurboMice™, VeloGene Biotechnology provides custom‑built AE‑relevant pre‑clinical models, including human GluN1 knock‑in and NMDAR‑subunit point‑mutation mice. Translational research teams working on neuro‑immunology and rare diseases are welcome to enquire for custom‑model services.