Asthma

Question 1

Features of asthma

Answer 1

Wheeze and dry cough on exertion, worse with colds, with allergen exposure

Question 2

Testing for asthma

Answer 2

Reversible airflow obstruction
Allergen sensitisation
Airway inflammation - eosinophilia or type 2 lymphocytes

Question 3

Pathogenesis

Answer 3

Allergen exposed to bronchial epithelium
inflammation and airway remodelling
Recruitment of inflammatory cells
Increased goblet cells
Increased matrix
Amount and size of smooth muscle cells increase

Question 4

Type 2 immunity in allergic asthma

Answer 4

Antigen presented to MHC II by APC
Turn naive T helper cells into Th2
Produce IL4 - IgE synthesis, IL13 - mucin secretion, IL5 - eosinophilic airway inflammation

Question 5

Test for allergen sensitisation

Answer 5

Blood test for specific IgE antibodies on skin

Question 6

Test for eosinophilia

Answer 6

Blood eosinophil over 300 cells/mcl abnormal
Induced sputum eosinophil more than 2.5% eosinophil abnormal
Exhaled nitric oxide

Question 7

NICE asthma objective tests

Answer 7

Airway obstruction on spirometry ratio <0.7
Bronchodilator reversibility more than 12%
Exhaled nitric oxide more than 35ppb (children) or more than 40ppb (adult)

Question 8

Diagnosis

Answer 8

In children
Symptoms and
Nitric oxide more than 35ppb and positive peak flow variability or
Obstructive spirometry and positive bronchodilator reversibility

Question 9

Management

Answer 9

Reduce airway eosinophilic inflammation - inhaled corticosteroids, leukotriene receptor antagonist

Acute symptom relief - Beta 2 agonist, anticholinergic therapy

Severe asthma - steroid sparing therapy - anti IgE, anti IL5

Question 10

Mechanism of action of corticosteroids

Answer 10

Decrease eosinophils by apoptosis
Decrease cytokines of T lymph
Decrease mast cells
Decrease cytokines of macrophage
Decrease dendritic cells 

Decrease epithelial cytokines and mediators
Decrease endothelial leak
Decrease mucus

Question 11

Pathogenesis of acute lung attack

Answer 11

Reduced anti viral response result in prolonged illness
Reduced peak respiratory flow rate and increased airway obstruction
Increased airway eosinophilic inflammation

Question 12

Anti IgE antibody

Answer 12

Omalizumab
Bind to IgE to prevent interaction with mast cells and basophils
Decrease in number over time
Severe asthma in patients over 6 years who need oral corticosteroid 4 or more times in previous year
Total serum IgE 30-1500

Question 13

Anti IL5 antibody

Answer 13

Mepolizumab

Eosinophilic asthma