Swiss Bee-Keepers Hold Key to MS Vaccine:
Investigators: David Wraith and Hartmut Wekerle by John Bonner
Swiss bee-keepers are the unlikely source of evidence to suggest that a proposed new treatment for multiple sclerosis will work, said immunologist David Wraith from the University of Bristol.
Wraith's team has been investigating ways of blocking the specific T cells that react to proteins of the protective myelin sheath surrounding nerve cells.
The T cells produce inflammatory cytokines that mediate destruction of the protective sheath. He has been using synthetic peptides based on fragments of myelin protein to induce tolerance and stop the disastrous autoimmune response.
The approach has been successful in a laboratory model for human MS, experimental allergic encephalomyelitis. Repeated exposure to the peptides switches off the Th1 pathway, which generates T cells that produce tumor necrosis factor and other cytokines implicated in the inflammatory response in MS patients.
Treated mice express a different T-cell population, known as Th0, which produces the protective cytokine IL-10. This blocks any further autoimmune degeneration by preventing antigen-presenting cells from activating new Th1 cells.
The peptides are squirted up the nostrils rather than given as an intravenous vaccine. This makes use of the mucosal immune response designed to prevent damaging inflammatory reactions to harmless antigens in the air and (in the gut mucosa) in food.
"Most autoimmune diseases are inflammatory responses, and so we are tapping into the machinery which has been specially designed to dampen down the inflammatory process,"
Wraith told BioMedNet News. Even antigens that are otherwise harmful can be tolerated when presented to the immune system via the mucosal surface. Scientists in the mid-19th century described how Native Americans had devised a way of preventing skin reactions to poison ivy by regularly eating the plant's leaves, Wraith says.
But, Wraith needed evidence that the beneficial changes induced by the vaccine in mice could also be generated in humans. "It is all very well having an animal model.
But before we could think of trying this approach on patients, we needed evidence that people could produce the same type of T cells that generate the protective IL-10 response seen in mice."
That evidence came from a study of beekeepers in Switzerland, which showed that regular exposure to bee stings switches off allergic reactions - the bee-keeper's blood samples were rich in IL 10.
Wraith has an agreement in principle from the UK medicines licensing authority to begin trials in MS patients. These are likely to begin within the next year, after completing the necessary preclinical safety tests.
Patients will probably receive a primary course of repeated weekly doses followed by monthly booster doses.
He expects those patients in the early stages of the disease to benefit most. Current treatments for MS do little more than treat the symptoms of the disease.
Even the controversial beta interferon therapy works only in some patients and then only slows the progress of the disease. "We hope that we can shut the gate - this is the only treatment that gets to the heart of the process that causes the disease," he said.
Bio Med Net News July 27th, 2001