L 03 & 04 Asthma Flashcards
What is asthma?
autoimmunity dysfunction. (autoimmune means body’s immune system attacks and destroys healthy body tissue by mistake)
What type of response does asthma cause?
Inflammatory response to an allergen (nonpathogenic =>means it does not cause disease).
What antibody and cells are involved of causing asthma?
IgE antibody &
T cells, B cells, Mast cells, eosinophils etc
Asthma progresses in 2 phases what are they?
- Sensitisation (first exposure):
2. Inflammation (re-exposure)
Asthma which types of hypersensitivity reactions?
Type 1 and type 4
In type 1=>Ige, Mast cells are important mediator
In type 4=>Th2 cells, Eosinophil,
What is Atopy/ allergy?
A predisposition to mounting IgE mediated immune responses.
IgE responses are like food allergy, rhinitis, dermatitis, asthma etc.
Name other IgE immune responses?
Food allergies, allergic rhinitis, atopic dermatitis.
What are the 3 conditions in the atopic march? (And the 4th sometimes)?
Asthma Atopic dermatitis (usually 1st to develop) Allergic rhinitis (rhinoconjunctivitis)
Also food allergies are common
How to test for atopy/allergy?
Skin prick testing. Don’t use if anaphylaxis has previously occurred for that allergen
3 steps of sensitisation phase?
- 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.
3 steps of inflammation phase?
- 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.
Th2 involvement
Produce the cytokines to drive IgE production by B cells/eosinophils/mast cell recruitment, for eradication of extracellular parasites or allergen
Mast cell involvement
Release cytokines and cause bronchoconstrictors
Eosinophil involvement
Release from white blood cells help to protect the damage cells and contribute to remodeling
What cells are important in initiating and driving the immune response?
Dendritic cells and B cells
What are the Other types of asthma + brief explanation?
- Non-atopic: asthma without atopic predisposition.
- Neutrophilic: less reversible, more inflammatory, later onset. Insensitive to CCs
- 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
Potential asthma triggers (allergic and non-allergic)?
Allergic: dust mites, animal dander, pollen, mould, food allergens
Non-allergic: cold air, humidity, exercise, tobacco smoke exposure
Pathophysiology of edema and remodeling of lung function during asthma?
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.
What are the 2 main factors causes asthma?
Genetics & environment.
Genes = polygenic
It is an immune dysfunction that occurs in susceptible individuals in a permissive environment
Susceptible genes that cause asthma?
Genes involving the:
- Function of immune system
- Mucosal biology and barrier function
- Lung function and disease expression
What are the Potential associations(connection) with developing asthma?
Environment (pollution, poverty, diet, family size, home)
Antibiotics
Paracetamol
Breast milk/delivery method/maternal diet
Animal contact
NZ epidemiology of asthma?
High rate for children and adults
Rate is higher for māori children and adults
Best treatment for asthma?
Avoiding triggers and allergens
3x immunotherapies for asthma?
- Asthma vaccines
- Anti-IgE therapy
- Specific allergen therapy
