Thursday 9 July 2009
Researchers uncover potential treatment for inclusion body myositis
Inclusion body myositis (IBM) is the most common neuromuscular condition to affect the elderly. Individuals affected by IBM experience a slow progression of muscle weakness and wasting in the arms and legs. Although there is no definite cause for the onset of IBM, one theory was that it was an auto-immune condition - where the body's immune system mistakenly attacks the muscles. However, current research has focused primarily on the role of clumps of proteins which accumulate in muscles of people affected by IBM and cause the muscles to deteriorate. One protein thought to be important in forming these clumps is amyloid-beta.
A team of researchers lead by Professor Frank LaFerla in California has further examined the role of amyloid-beta in a mouse model of IBM and investigated whether clearing away the clumps of this protein could improve symptoms.
Contents:
- What did this study show?
- What does this mean for patients?
- Background Information
- Further information and links
What did this study show?
Researchers in this study used a mouse model in which amyloid-beta formed clumps in the muscles. These mice developed symptoms similar to individuals affected by IBM. To test whether clearing away the the amyloid-beta clumps could improve the symptoms in these mice, researchers then caused the mice to produce antibodies against the amyloid-beta.
Antibodies are Y-shaped proteins made by certain white blood cells in response to a foreign substance such as bacteria or virus. When we are immunised or vaccinated against a particular illness such as measles, we produce antibodies against that particular virus or bacteria and are therefore protected against it if we encounter it in the future. Antibodies bind to harmful particles in the body, in this case the amyloid-beta, and signal for the immune system to destroy them and clear them away.
The researchers found that the mice which were immunised against amyloid-beta and produced antibodies were able to clear away the clumps of amyloid-beta protein in the muscles and had improved muscle function.
What does this mean for patients?
This study provides extensive new evidence that the clearance of amyloid-beta improves IBM symptoms in mice. These findings may lead to the development of therapies that aim to induce the production of amyloid-beta antibodies in people affected by IBM.
Clumps of amyloid-beta (also known as plaques) are also present in the brains of individuals affected by Alzheimer's disease. There are currently more than ten different clinical trials which are attempting to use antibodies to clear away amyloid-beta plaques in individuals affected by Alzheimer's disease. If any of these clinical trials discover a safe way to immunise people so that they produce amyloid-beta antibodies it would be logical to then test this in a clinical trial for IBM.
Results in studies using mouse models do not necessarily translate into human beings and further research must be conducted to determine if these results are applicable to IBM patients.
Background Information
IBM is the most common neuromuscular condition diagnosed in individuals beyond the age of 50 years. It usually occurs in middle to late life and is more common in men than women. Approximately 5-10% of all individuals affected by IBM inherit the condition, while most develop the condition sporadically without a genetic link. More than 2000 individuals in the UK are affected by IBM.
IBM causes weakness in the muscles of the forearms, fingers, and quadriceps (thigh muscles). Individuals affected by IBM often report difficulty walking up/down stairs, sitting in or getting off of a chair, or gripping a mug. Other muscles such as those controlling the heart, eyes, gut, and bladder are generally spared. Normal intellect and speech is also maintained.
Further information and links
More information about inclusion body myositis (IBM).
