A team from the Faculty of Medicine at Universit Laval and the research centre at CHUQ (Centre hospitalier universitaire de Qubec) has discovered a natural defence mechanism that the body deploys to combat nerve cell degeneration observed in persons with Alzheimer's disease (AD). Investigators Alain R. Simard, Denis Soulet, Genevieve Gowing, Jean-Pierre Julien and Serge Rivest describe this major discovery in the February 16th issue of the scientific journal Neuron.

Alzheimer's disease is characterized by the accumulation of amyloid proteins in the brain. These proteins form plaques around which microglia, the central nervous system's immune cells, aggregate. These microglia appear to be incapable of eliminating the plaques, and this has led some researchers to postulate that microglial action produces an inflammation causing neuronal death. The fact that Alzheimer's patients are prescribed anti-inflammatory drugs results from this concept of the disease.

For Serge Rivest and his team, whose research is funded by the Canadian Institutes of Health Research (CIHR), microglia are not part of the problem, but of its solution. These investigators have observed that, although the brain's resident microglia do appear to be poorly equipped for combating amyloid plaques, an entirely different case prevails for another type of microglia: those derived from bone marrow stem cells.

Using tests conducted with transgenic mouse models of AD, the investigators have demonstrated that bone marrow-derived microglia infiltrate amyloid plaques and succeed in destroying them most efficiently. These newly-recruited immune cells are specifically attracted by the amyloid proteins that are the most toxic to nerve cells.

"The discovery made by Dr. Rivest and his team is an important step towards a new therapeutic approach to Alzheimer's disease," states Dr. Rmi Quirion, Scientific Director of the Institute of Neurosciences, Mental Health and Addiction (INMHA
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Contact: Jasmine Sharma
613-941-4563
Canadian Institutes of Health Research
16-Feb-2006

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