The airway smooth muscle cell in asthma:
A genomics approach

Asthma is a worldwide disease with symptoms that are characteristic and well
described. However the pathophysiologic mechanisms leading to the observed
functional changes are still unknown. Recently, interest has been shown in the
ASM layer as an important structure contributing to the pathophysiologic
features of asthma. Several studies have shown that the phenotype of ASM is
changed with asthma and it is postulated that ASM itself can contribute to the
regulation and perpetuation of airways inflammation in asthma. Mast cells and
progenitor cells of the ASM also tend to play an important role in asthma.
Furthermore, the beneficial effects of corticosteroids on the clinical status
and lung function are well described. However it is not clear whether this is
solely based on its anti-inflammatory effect or that steroids also have other
local actions . Therefore, the airway smooth muscle layer could be the common
pathway in determining variable airways obstruction in asthma. We hypothesize
that the phenotypic profiles of the ASM layer at the gene-level is different
between asthmatic and healthy patients, is associated with measures of variable
airways obstruction and with the inflammatory infiltrate within the ASM layer,
and that the ASM gene expression profile changes after treatment with oral
steroids.

To examine the difference in gene expression profiles of ASM in bronchial
biopsy specimens between asthmatic patients, non-asthmatic allergic and
non-asthmatic non-allergic controls.
To associate the gene expression profiles with airway hyperresponsiveness,
dynamics of airway resistance, and inflammatory cell infiltrates in- and
outside the ASM layer in asthma.
To investigate the change in gene expression profiles in relation to clinical
and functional improvement after 14 days of oral steroids treatment.
To associate the presence and type of bronchial pathogens with clinical
severity, and with the degree and profile of airways inflammation, airway
remodelling and airway hyperresponsiveness.
To examine the ASM volume in biopsy specimens in asthmatic and non-asthmatic
patients.
To associate the physiologic and pathologic parameters of asthma with the
circulating venous blood gene profile.
To maximize the quality of the data in asthmatic patients and controls through
confirmation of the feasibility of RNA-analysis by using biopsy material
obtained from chronic cough patients.

The study consists of three different study phases: screening, study phase 1
and study phase 2.
A cross-sectional study will be done during study phase 1, and a randomised
controlled, double-blind, parallel intervention study during study phase 2.

Furthermore, prior to the study, the feasibility of RNA-analysis will be
confirmed by using biopsy material of chronic cough patients.

During study phase 2, the asthmatic patients will be randomly divided in 2
groups of equal sizes. One group will receive an oral steroid (Prednisolone)
and the other group placebo.

All study procedures will be carried out on an international consensus basis
and performed by qualified personnel.
The amount of procedures and duration of the study depends on the patientgroup:
Asthmatic patients in 2 months: once a general physical examination and skin
prick test during screening, 3 times spirometry, 2 times FOT and eNO
measurements, 2 times methacholine bronchoprovocation test, 2 times venous
blood collection and bronchoscopy with biopsies. The bronchoscopy will always
be preceded by blood collection. The time between the 2 bronchoscopies will be
at least 14 days.
Non-asthmatic, healthy patients in 1 month: once a general physical examination
and skin prick test during screening, 2 times spirometry, once a FOT an eNO
measurement, once a methacholine bronchoprovocation test, once a venous blood
collection and bronchoscopy with biopsies.The bronchoscopy will always be
preceded by peripheral blood collection.

After a bronchoscopy, patients could develop a slight amount of recurrent
bleeding, which most of the time will be self-limiting. Regardless, the patient
will stay at the AMC for at least an hour after the bronchoscopy has been done.
Only with permission of the attending physician the patient is allowed to go
home. Patients could develop a short term fever (couple of hours). Most of the
time it will be resolved by the next day. The patient will otherwise be advised
to contact his or her general practitioner or attending physician.
During venous blood collection, the patient may experience light-headedness.
This will be attenuated as much as possible by instructing the patient and
making the procedure as comfortable as possible, for example sitting in a
comfortable chair. However, light-headedness is not expected to occur
frequently as 2,5ml of blood will be collected.
It is known that Prednisolone given orally may be accompanied by systemic side
effects. Patients will be asked to report all side-effects during these 14 days
of dosing as soon as possible. If deemed necessary after review, the patient
will immediately stop taking the medication and the clinical status wil be
followed-up to ensure his or her safety. The dosage and dosing scheme used in
this study has been recommended as exacerbation treatment. In other words,
patients will receive only one extra episode of exacerbation treatment by
participating in this study.

Regarding confirming the feasibility of RNA-analysis, one extra biopsy specimen
will be taken from chronic cough patients, who are scheduled to undergo a
routine, diagnostic bronchoscopy with biopsy collection. The collection of one
extra biopsy specimen wil have no influence on the results of the bronchoscopy.
Furthermore, the execution of the bronchoscopy will not differ from the normal
situation.