Asthma is an inflammatory condition which affects the bronchial tubes in the lungs. People with asthma have sensitive or hyperactive airways which narrow in response to certain stimuli. The narrowing is due to inflammation and swelling of the lining, tightening of the airway muscles (spasm) and production of excess mucus. This reduces the airflow in and out of the lungs and leads to the characteristic wheezing and cough.
Asthma is a widespread and chronic health problem in Australia with over two million Australians suffering from it. Asthma affects up to 14% of children and up to 12% of adults and is estimated to cost the community $700m per year in direct costs. As management has improved, fewer people die from asthma, but it is still a common reason for hospital admission and emergency department visits, especially in childhood.
What causes asthma?
The causes of asthma are still not clearly understood, but genetic and environmental factors come into play. There is often a family history of asthma, eczema and/or hay fever or other allergies. Moreover, children with one asthmatic parent are three to six times more likely to develop asthma.
This is due to alterations in a number of genes which together control the level of airways inflammation and type of antibody produced following exposure to environmental stimuli like allergens (see below) The type of antibody is termed IgE and can be measured in the blood and by skin prick testing. Among the environmental factors responsible for triggering attacks are:
- inhaled allergens such as pollen or dust mites and irritants such as perfumes or cleaning fluids
- cigarette smoke (passive as well as active exposure)
- infection with a cold or flu
- changes in temperature or weather
What are the symptoms of asthma?
The symptoms of asthma may vary from person to person, and from time to time. Some people may have all these symptoms while other people may only have a wheeze or cough:
- a dry, irritating, persistent cough, particularly at night, early morning, or during exercise
- shortness of breath
- tightness in the chest
What approaches to treatment are available?
The initial step in management is to confirm that the patient does indeed have asthma and not some other lung disease using standard lung function tests. It is then necessary to identify to what allergen(s) or stimuli the person may be sensitive by testing for the presence of specific IgE antibodies (eg by skin prick testing and serum assays).
Based on the results an asthma action plan can be developed in consultation with GP and specialist . Minimisation of exposure to environmental triggers and tailored inhaler therapy are the mainstay of ongoing treatment in the absence of a definitive long term cure. The place of allergen desensitisation is still controversial and to be optimised requires more research (see below).
What research is Garvan doing in this area?
The Garvan Institute has had a long standing commitment to studying the mechanisms underlying asthma. It was formerly a partner in the Cooperative Research Centre for Asthma and Airways (CRCAA), established in 2005, in which our researchers identified a novel inflammatory mediator in allergic lungs, called aP2. This is now being looked at as a target for new drugs .
More recently, the focus of our research has been on the control of IgE antibodies elevated levels of which are a hallmark of allergic forms of asthma. A unique experimental model has just been developed to investigate the issue which should pave the way for more rational ways of desensitising patients and for devising new strategies for treating IgE mediated allergic diseases in general.
In collaboration with researchers in the St Vincent’s Hospital Centre for Applied Medical Research, the Garvan is also investigating the role of a recently discovered type of cells, known as innate lymphocytes, in the development of allergic inflammation.
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