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Vitamin supplement could help treatment-resistant
asthmaDecember 09, 2005 Asthma patients who don't respond
to steroid treatment suffer repeated asthma attacks, and are
at greater risk of dying from the condition. Researchers from
King's College London have found that vitamin D3 could
substantially improve the responsiveness of these patients
to steroid treatment, offering them hope of an improvement
in their condition. Their results are published today in the
Journal of Clinical Investigation. Asthma is usually treated
very effectively with inhaled steroids but for some patients,
taking steroid tablets is the only way of controlling their
condition, and this can cause considerable side effects. Unfortunately
a sub-group of people with severe asthma fail to show clinical
improvement, even with high doses of oral steroids, limiting
their treatment options. Professor Tak Lee, Director of the
MRC-Asthma UK Centre in Allergic Mechanisms of Asthma at King's
College London and Imperial College, who was involved in the
latest study, explained its importance: 'This research
is really exciting and points the direction towards potential
new strategies for reversing steroid resistance. This has
major implications for how to treat patients with severe asthma
and could also substantially reduce the use of NHS resources.'
The team's results imply that steroid treatment works,
at least in part, by inducing the T-cells of the immune system
to synthesise a secreted signalling molecule, called IL-10.
This molecule can inhibit the immune responses that cause
the symptoms of allergic and asthmatic disease. Unlike T-cells
from healthy individuals, or patients that respond to steroids,
T-cells taken from patients who are steroid resistant do not
produce IL-10 when cultured in vitro with the steroid, dexamethasone.
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However, the researchers found that
when vitamin D3 was added to the culture medium along with
dexamethasone, this defect was reversed and the previously
steroid-resistant cells were able to respond to the treatment
by producing IL-10 to the same extent as T-cells taken from
steroid-responsive patients. Adding vitamin D3 to cultures
of T-cells from healthy individuals or from steroid-responsive
patients made these cells even more responsive to steroids
than before. Dr Catherine Hawrylowicz, who led the King's
research team said: 'The hope is that this work will lead
to new ways to treat people who don't respond to steroid
treatment as it currently stands, and it could also help those
people who are on heavy doses of steroids to reduce the amount
of medication they are taking.' To test whether this therapy
could work in practice the team at King's went on to perform
a pilot experiment where people with asthma who were unresponsive
to steroids took daily vitamin D3 supplements for seven days.
The researchers took blood samples to assess whether the patients'
T-cells were more responsive to dexamethasone after they had
taken the supplement. The test results were positive.
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Dr Hawrylowicz said: 'This is a
great example of how productive basic science collaborations
can translate into studies in patients. Our research began
more than five years ago with Dr Anne O'Garra from the
MRC National Institute for Medical Research at Mill Hill.'
She added: 'At the moment we only have a preliminary experimental
observation, that ingestion of vitamin D3 can increase the
responsiveness of T-cells from patients with steroid-resistant
asthma to steroids. We now need to test the benefits of this
treatment in the clinic, and we are currently putting a proposal
together to carry out this work. 'Interestingly, vitamin
D3 is at present occasionally administered to patients with
severe asthma to help prevent steroid-induced osteoporosis.
Our studies suggest that there is an additional potential
benefit to this treatment.' Dr. Lyn Smurthwaite, Research
Development Manager at Asthma UK said: '2.6 million people
in the UK have severe asthma symptoms, many of whom have restricted
treatment options available to them as they do not respond
to conventional steroid therapy. Asthma UK is very pleased
to have funded this research which opens up a potentially
important new avenue for developing treatments for people
with difficult to control asthma.' King's College
London
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