L 03 & 04 Asthma

Question 1

What is asthma?

Answer 1

autoimmunity dysfunction. (autoimmune means body’s immune system attacks and destroys healthy body tissue by mistake)

Question 2

What type of response does asthma cause?

Answer 2

Inflammatory response to an allergen (nonpathogenic =>means it does not cause disease).

Question 3

What antibody and cells are involved of causing asthma?

Answer 3

IgE antibody &

T cells, B cells, Mast cells, eosinophils etc

Question 4

Asthma progresses in 2 phases what are they?

Answer 4

1. Sensitisation (first exposure):

2. Inflammation (re-exposure)

Question 5

Asthma which types of hypersensitivity reactions?

Answer 5

Type 1 and type 4

In type 1=>Ige, Mast cells are important mediator
In type 4=>Th2 cells, Eosinophil,

Question 6

What is Atopy/ allergy?

Answer 6

A predisposition to mounting IgE mediated immune responses.

IgE responses are like food allergy, rhinitis, dermatitis, asthma etc.

Question 7

Name other IgE immune responses?

Answer 7

Food allergies, allergic rhinitis, atopic dermatitis.

Question 8

What are the 3 conditions in the atopic march? (And the 4th sometimes)?

Answer 8

Asthma
Atopic dermatitis (usually 1st to develop)
Allergic rhinitis (rhinoconjunctivitis)

Also food allergies are common

Question 9

How to test for atopy/allergy?

Answer 9

Skin prick testing. Don’t use if anaphylaxis has previously occurred for that allergen

Question 10

3 steps of sensitisation phase?

Answer 10

1. Sensitisation (first exposure):
   - Dendritic cells (DCs) encounter an allergen in the lungs to become activated.
   - Activated DCs then travel to the lymph node, activating the T cells causing differentiation into T helper cells and interleukin (IL) production.
   - The IL and Th then cause B cell activation and proliferation which produce IgE to float around in the systemic circulation.

Question 11

3 steps of inflammation phase?

Answer 11

2. Inflammation (re-exposure)
   - IgE antibody bind or sensitize the mast cell/basophil/eosinophil in the lungs will recognize and bind the allergen

• This encounter causes the degranulation of the cells which contain mediators (histamine, proteases, leukotrienes, prostaglandins) and therefore produces an intense inflammatory response.
• Immediate action: airway function impaired. Further action: increased IgE production therefore more damage to airways.

Question 12

Th2 involvement

Answer 12

Produce the cytokines to drive IgE production by B cells/eosinophils/mast cell recruitment, for eradication of extracellular parasites or allergen

Question 13

Mast cell involvement

Answer 13

Release cytokines and cause bronchoconstrictors

Question 14

Eosinophil involvement

Answer 14

Release from white blood cells help to protect the damage cells and contribute to remodeling

Question 15

What cells are important in initiating and driving the immune response?

Answer 15

Dendritic cells and B cells

Question 16

What are the Other types of asthma + brief explanation?

Answer 16

1. Non-atopic: asthma without atopic predisposition.
2. Neutrophilic: less reversible, more inflammatory, later onset. Insensitive to CCs
3. Occupational: due to allergens encountered in the workplace only (don’t confuse it with work-aggravated asthma)

NB: Atopy is the tendency to produce an exaggerated immunoglobulin E (IgE) immune response to otherwise harmless substances in the environment

Question 17

Potential asthma triggers (allergic and non-allergic)?

Answer 17

Allergic: dust mites, animal dander, pollen, mould, food allergens
Non-allergic: cold air, humidity, exercise, tobacco smoke exposure

Question 18

Pathophysiology of edema and remodeling of lung function during asthma?

Answer 18

Oedema: the influx of fluid with inflammation=> mucus hypersecretion =>which blocks airways.

how Remodelling occurs: thickening of the basement membrane=> smooth muscle hypertrophy, and increased mucus cells => progressive and irreversible loss of airway function.

Question 19

What are the 2 main factors causes asthma?

Answer 19

Genetics & environment.

Genes = polygenic
It is an immune dysfunction that occurs in susceptible individuals in a permissive environment

Question 20

Susceptible genes that cause asthma?

Answer 20

Genes involving the:

1. Function of immune system
2. Mucosal biology and barrier function
3. Lung function and disease expression

Question 21

What are the Potential associations(connection) with developing asthma?

Answer 21

Environment (pollution, poverty, diet, family size, home)
Antibiotics
Paracetamol
Breast milk/delivery method/maternal diet
Animal contact

Question 22

NZ epidemiology of asthma?

Answer 22

High rate for children and adults

Rate is higher for māori children and adults

Question 23

Best treatment for asthma?

Answer 23

Avoiding triggers and allergens

Question 24

3x immunotherapies for asthma?

Answer 24

1. Asthma vaccines
2. Anti-IgE therapy
3. Specific allergen therapy