Asthma and Respiratory Immunology Flashcards
(30 cards)
What is the epidemiology of asthma
- 5.4m people currently recieving treatment for it in uk
- 1.1 m children affected ( 3/10 )
~ 3 people die from asthma attack per day in uk - NHS spends ~ 1b pounds treating asthma every year
what are the cardinal features of asthma?
- wheeze +/ - dry cough
- atopy / allergen sensitisation
- reversible airflow obstruction
- airway inflammation (eosinophilia and type 2 lymphocytes)
what is the key symptom of asthma and what is it caused by?
wheezing / whistling sound that comes from airways as a result of airways narrowing / broncho constriction
what can wheezing be associated with?
dry cough
breathlessness
difficulty in breathing
what can make wheezing worse?
exertion ( e.g. exercise )
worse with respiratory infections such as colds
worse with allergen exposure
what are the 3 things you test for to diagnose asthma?
- atopy / allergen sensitisation
- reversible airflow obstruction
- airway inflammation = eosinophilia, type 2 lymphocytes
describe the pathophysiology of asthma
asthmatic airway has a thickened and inflamed wall due to naturally increased baseline smooth muscle
and due to eosinophilia
so lumen = narrower than normal (( if untreated )) and this leads to turbulent flow hence the wheeze sound
what happens to the airway in an asthma attack
it is very highly thickened and closed up even more than at baseline
what is the type of airflow in a normal airway?
laminar
what is the type of airflow in an untreated asthmatic airway?
turbulent
what does the airway look like if asthma is managed and treated correctly?
looks normal
how do you test for reversible airway obstruction?
using spirometry and a flow volume loop
what does a flow volume loop show in a px with asthma? (with and without treatment)
with bronchodilator - should look normal
without - expiratory loop (top half) is scooped and reduced
what test do you do to see eosinophilia?
Biopsy
special red stain will show them
why cant a spirometry be used for a young child?
it is a forced exposure manoeuvre so a lot of effort is required
when someone who is susceptible to asthma gets exposed to allergens and is sensitised, what happens to their airways?
develop inflammation and airway remodelling
what inflammatory changes occur in an asthmatic airway?
recruitment of inflammatory cells mostly eosinophils (bilobar)
what is airway remodelling?
changes in the structural cells in the airway
what are the structural changes that occur in the epithelium in an asthmatic airway?
develop increased goblet cells (mucus secreting)
amount of matrix increases
amount and size of smooth muscle cells increases
why do only some people who are sensitised develop the disease (asthma)?
bc there is an underlying genetic susceptibility - only the people who have this will go on to develop the disease
what shows us that there is an underlying genetic susceptibility for asthma?
genome wide association studies on people with and without the disease, can see there is an increased expression in certain genes
what is a benefit of genome-wide association studies for asthma?
show a consistent, reproducible result in px with it
Examples of what gwa studies for asthma show?
gene expression for IL33 and GSDMB is increased in people with asthma
what is the data for gwa plotted in?
manhattan plot where x axis is the chromosomes that gene is on and y is the p value of how likely it is to be increased normally (log)
