Model Introduction
Multiple sclerosis (MS) is a neurological disease with an etiology that remains not fully understood, affecting millions of patients worldwide. To investigate such complex diseases, animal models are frequently employed in scientific research for mechanistic exploration and methodological validation. Among all models used to replicate MS, Experimental Autoimmune Encephalomyelitis (EAE) most accurately reflects the autoimmune pathogenesis of MS. The EAE model “replicates” the disease process by inducing an immune response against central nervous system (CNS) myelin-associated antigens under laboratory conditions, providing an experimental platform for understanding MS and conducting related research. During the construction of the EAE model, factors such as species, strain, age, sex, and the choice of key reagents influence the success rate and reproducibility of the model. Therefore, systematic configuration and control are required during the design phase.
Research Applications
As an animal model for MS, EAE effectively simulates the autoimmune pathological features of MS, serving as a critical platform for studying MS pathogenesis and drug screening. Since different animal strains exhibit significant variations in EAE susceptibility, researchers can select appropriate animals and antigen systems based on their research objectives to achieve stable immune induction and reproducible clinical phenotypes. Furthermore, the EAE model can be integrated with clinical scoring, histopathology, and immunological assays—ranging from behavioral phenotypes to histological changes and immune cell/cytokine levels—forming a comprehensive evaluation chain for the systemic observation of disease progression and intervention efficacy.
Key Points of Experimental Design
1) Species / Strain / Age & Sex / Reagent Selection
- Species Selection The most commonly used laboratory animals for EAE models are rodents, particularly rats and mice, due to their low cost, rapid reproduction, ease of handling, and immunological similarities to humans.
- Strain Selection (Susceptibility Differences)
- C57BL/6 mice: Frequently used EAE model animals, highly sensitive to EAE induced by Myelin Oligodendrocyte Glycoprotein peptide (MOG35-55).
- Lewis rats: Common model animals, especially suitable for studying the effects of nutrients such as vitamins on EAE.
- Wistar rats: Exhibit stable immune responses and are easy to handle, often used in T-cell vaccine research.
- Age and Sex
- Age: Younger animals (typically 6–8 weeks old) have more active immune systems and are more susceptible to EAE induction.
- Sex: Sexual dimorphism affects incidence and symptom severity; in some studies, female animals show higher incidence and more severe symptoms, potentially related to differences in hormone levels and immune responses.
- Reagent Selection
- Antigens: Common antigens include MOG35-55, PLP, and MBP; MOG35-55 is the standard antigen for C57BL/6J mice.
- Adjuvant: Complete Freund’s Adjuvant (CFA) is used to enhance the immune response.
- Pertussis Toxin (PTx): Used to augment EAE induction; however, the dose and batch potency must be strictly controlled to ensure consistency.
2) Immunization Procedure
- Antigen Emulsification Mix the antigen (e.g., MOG35-55) with CFA in a specific ratio to prepare an emulsion. Typically, the antigen concentration is 1–2 mg/mL, and the volume ratio of CFA to antigen is 1:1.
- Immunization Injection Inject the emulsified antigen subcutaneously into the animal’s back or tail base, usually at multiple points; 50–100 µL per point, with a total dose of 100–200 µg per animal.
- PTx Injection Administer PTx intraperitoneally (200–500 ng per animal) on the day of immunization and 48 hours post-immunization. The PTx dose should be adjusted based on batch potency to ensure model consistency.
3) Model Evaluation Timepoints Daily clinical observation and scoring begin from day 7 post-immunization. The peak of the disease typically occurs between days 16–20 post-immunization, which is the timepoint for harvesting tissues for pathological and immunological analysis.
Key Detection Indicators
1) Clinical Scoring Daily observation and scoring according to a standard scoring system starting from day 7 post-immunization. Indicators typically include body weight changes, tail tone, hind limb weakness, forelimb weakness, and paralysis. 2) Pathological Detection Animals are sacrificed at the disease peak (typically days 16–20 post-immunization), and brain and spinal cord tissues are collected for pathological analysis:
- H&E Staining: To observe inflammatory cell infiltration.
- Luxol Fast Blue (LFB) Staining: To observe demyelination. 3) Immunological Detection Detection of immune cells (e.g., Th17, Treg) and related cytokines (e.g., IL-17, IL-10) in peripheral blood or the CNS via flow cytometry or ELISA.
