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Asthma Animal Model

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Model Introduction

Allergic asthma is a common respiratory disease characterized by core pathological features including Airway Hyperresponsiveness (AHR), elevated allergen-specific IgE, eosinophil infiltration, and a Th2-biased immune response. An ideal animal model should replicate the key features of human allergic asthma as closely as possible, including airway inflammation, increased mucus secretion, airway remodeling, and changes in immune cytokines. Currently, stable allergic asthma models can be constructed through specific animal strain selection, allergen exposure, and local airway challenge, which are used for mechanistic studies and drug screening.

Research Applications

Allergic asthma animal models are widely used to:

  • Study Th2-type immune responses and changes in the Th1/Th2 balance.
  • Analyze IgE-mediated allergic mechanisms.
  • Observe eosinophil-mediated airway inflammation.
  • Evaluate anti-inflammatory drugs and targeted therapy strategies.
  • Explore pathological differences induced by various allergens. Models can be evaluated through behavior, pulmonary function testing, inflammatory cell analysis, and molecular assessment to build a multi-dimensional disease evaluation system.

Key Points of Experimental Design

1) Experimental Animal Selection Commonly used animals include mice, rats, and guinea pigs:

  • Mice: The most common species due to clear genetic backgrounds and mature immunological tools, facilitating mechanistic research.
    • BALB/c: Strong Th2 response, prone to induced eosinophilic inflammation and high IgE.
    • C57BL/6: A standard strain.
  • Rats: Suitable for chronic models and pharmacological studies; larger airway structures facilitate physiological testing.
    • Common strains: SD, Wistar.
  • Guinea Pigs: Sensitive airway smooth muscle, ideal for observing immediate-type reactions; however, their use is declining due to limited immunological reagents. 2) Allergens and Adjuvants
  • Allergens: Ovalbumin (OVA) is commonly used to stably induce Th2 responses; environmental allergens like House Dust Mite (HDM) extract can also be used.
  • Adjuvants: Aluminum hydroxide is used to enhance the immune response and promote a Th2-type shift, favoring IgE production. 3) Sensitization and Challenge Protocol Model construction is divided into two phases: (1) Systemic Sensitization Phase
  • Objective: To induce a specific immune response and produce high titers of specific IgE.
  • Method:
    • Day 0: Intraperitoneal injection of a solution containing OVA (e.g., 150 μg) and aluminum hydroxide adjuvant (e.g., 100 mg).
    • Days 7 and 14: Booster immunizations. (2) Airway Challenge Phase
  • Objective: To induce local allergic inflammation and asthma symptoms.
  • Method:
    • Starting after the last sensitization (e.g., Day 16), administer a low-concentration OVA solution (e.g., 1%–1.5%) via nebulized inhalation or intranasal instillation.
    • Typically once every other day for 4–7 times. 4) Model Variants
  • Chronic/Severe Models: Extend the challenge duration or add IL-33 or low-dose LPS.
  • Combined Syndrome and Disease Model: Combine with oral administration of thyroxine to construct a “Yin-deficiency type allergic asthma” model.
  • Different Allergen Models: Use HDM extract instead of OVA to improve clinical relevance. 5) Example Experimental Protocol (BALB/c OVA Model)
  • Animals: 6–8 week old female BALB/c mice.
  • Sensitization: IP injection of a suspension containing 100 μg OVA + 2 mg Al(OH)3 on Days 0, 7, and 14.
  • Challenge: 1% OVA nebulization for 30 minutes daily from Day 21 for 7 consecutive days.
  • Evaluation: 24–48 hours after the last challenge.

Key Detection Indicators

1) Behavioral Observation

  • Shortness of breath
  • Abdominal muscle twitching
  • Nodding respiration
  • Composite symptom score 2) Airway Hyperresponsiveness (AHR)
  • Methacholine gradient nebulization stimulation.
  • Detection of airway resistance.
  • Detection of lung dynamic compliance. 3) Inflammatory Cells and Histology
  • Total and differential cell counts in Bronchoalveolar Lavage Fluid (BALF).
  • Significant increase in eosinophils.
  • H&E Staining: Peribronchial inflammatory cell infiltration.
  • Goblet cell hyperplasia.
  • Increased mucus secretion.
  • Airway wall thickening.
  • PAS Staining. 4) Immunological and Molecular Indicators
  • Serum total IgE or specific IgE levels.
  • Elevated IL-4, IL-5, and IL-13.
  • Potentially decreased IFN-γ.
  • RT-PCR for related gene expression (e.g., IL-4 receptor mRNA).

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