A VACCINE that turns part of the immune system off could provide a treatment
for psoriasis, a potentially disfiguring skin disease.
鈥淲ith a single shot you get long-lasting protection,鈥� says Phil Hodgkin, an
immunologist at the Centenary Institute in Sydney.
Some scientists think that psoriasis, which affects 1 in 50 people, is
triggered when the immune system attacks the body鈥檚 own tissues. Most
researchers trying to find cures for such autoimmune disorders focus on finding
the human proteins that trigger the diseases.
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But James Watson of Genesis Research & Development in Auckland, New
Zealand, took a different tack鈥攁ltering the immune system鈥檚 response. 鈥淲e
tend to think that if we can find the antigen, we can find a treatment, but the
missing link is actually some abnormality in the immune response,鈥� he says.
Watson and his colleagues got their idea from a trial of a leprosy vaccine in
India. The vaccine, which contained heat-killed Mycobacterium vaccae
bacteria, failed to cure leprosy鈥攂ut one of the patients鈥� severe psoriasis
cleared up.
So Watson鈥檚 team have created a psoriasis vaccine containing parts of
M. vaccae. In a safety trial in New Zealand, half of 24 patients with
psoriasis improved, and in a quarter the disease completely disappeared. The
effects last for up to 18 months鈥攖he longest that patients have been
followed. Corixa of Seattle is now running larger trials.
No one yet understands exactly how the vaccine works. 鈥淪omehow the vaccine
reprograms the immune system, turning off the cells that attack the skin,鈥� says
Watson. A handful of animal studies from around the world suggest that modified
versions of the vaccine may be effective against a whole range of autoimmune and
inflammatory diseases, including cardiovascular disease and diabetes, he
says.
