Pathology: asthma

Question 1

Asthma is defined by which 3 characteristics?

Answer 1

• Chronic inflammation of the airways
• Bronchial hyperresponsiveness
• Variable, reversible airflow limitation

Question 2

Aetiology
- Is the cause known?
- Can both genetic and environmental factors contribute?

Answer 2

No, yes

Question 3

Aetiology
- What are the 4 main causes of asthma?

Answer 3

Atopic asthma
Non atopic asthma
Occupational asthma
Drug induced asthma

Question 4

Aetiology
- Examples of asthma triggers?

Answer 4

Allergens: dust, mold,pet fur
Irritants:
- Cigarette smoke, pollutants, occupational irritants
- Cold air, exercise,
- Infections, rhinitis, GORD,
Drugs: NSAIDs/aspirin, beta blockers

Question 5

Pathophysiology
- What are the 3 stages of allergic asthma?

Answer 5

Sensitisation, immediate phase, late phase

Question 6

Pathophysiology
- Describe sensitisation

Answer 6

• Initial exposure(s) to the allergen/trigger
• Dendritic cells phagocytose the allergen and express its antigens on its surface; then present them to Th2 cells
• Th2 cells secrete IL-4, which drives B cells to switch isotype and secrete IgE
• IgE will bind to Fc receptors on the surface of mast cells.
• This process repeats following repeated exposure to the allergen … –> IgE binding to mast cell Fc receptors. IgE levels will eventually reach a threshold, which will trigger mast cell degranulation.

Question 7

Pathophysiology
- Describe immediate phase

Answer 7

Question 8

Pathophysiology
- Describe late phase

Answer 8

• Secretion of cytokines (eg. IL-5) in the immediate phase will lead to leukocyte (mainly eosinophil) recruitment
• Leads to further inflammatory damage

Question 9

Pathophysiology:
- Airway remodelling can occur with chronic asthma.
- Changes with airway remodelling?

Answer 9

• Accumulation of mucus in bronchial lumen - increased number of goblet cells (green), hypertrophy of submucosal glands
• Thickened basement membrane
• Chronic inflammation - leukocyte recruitment (yellow is eosinophils), oedema
• Angiogenesis
• SMC hypertrophy and hyperplasia (blue)
• Scarring and fibrosis - from recurrent damage and repair

Question 10

Histology
- 2 features in sputum?

Answer 10

Curshmann spirals
Charcot Leyden crystals

Question 11

Histology
- What are Curshmann spirals?
- What are Charcot Leyden crystals?

Answer 11

• Curshmann spirals: spiral shaped mucus plugs, which are basically elongated mucus casts from small bronchi of people with bronchial asthma
• Charcot Leyden crystals shaped like needles, formed by the breakdown of eosinophils
  made of galectin-10, a protein made by eosinophils

Question 12

Prognosis
- Can patients be virtually asymptomatic between attacks?
- Can an unremitting attack cause acute severe asthma (status asthmatics), can it be fatal?

Answer 12

Yes
Yes

Question 13

How would you describe asthma to a patient?
- What is it?
- Causes
- Pathophysiology
- Symptoms

Answer 13