VANCOUVER, CANADA — Millions of HIV patients who suffer
from dementia now have hope of a treatment, thanks to a breakthrough
discovery by Canadian researchers.
Scientists from the University of Calgary in Alberta and
the University of British Columbia in Vancouver have found
that HIV triggers an enzyme in white blood cells that kills
nerve cells in the brain. The enzyme, known as Metalloproteinase-2
or MMP2, changes a molecule required for normal brain growth
and function. The altered molecule becomes highly toxic and
destroys brain nerve cells, giving rise to symptoms of dementia.
It is the first study to unravel the mechanics of how dementia
and memory loss is caused in HIV patients. In addition, the
researchers also found they could block the toxic effects
of MMP2 by using drugs already in clinical trials for cancer
treatment.
“We now understand how this enzyme becomes a killing
machine,” says Christopher Overall, Canada Research
Chair in Metalloproteinase Biology at UBC. “This is
exciting news for patients because we think dementia can be
slowed or stopped by adding another protease blocker to the
drug cocktails now used to treat HIV.”
More than 20 per cent of people with AIDS experience dementia
during the course of their illness. A rapidly progressive
condition, HIV dementia is characterized by impaired concentration
and problem solving, forgetfulness, as well as motor abnormalities
such as slurred speech and difficulties with movement.
The findings of the two-year study, completed with principal
co-investigator Christopher Power of the University of Calgary,
were reported recently in Nature Neuroscience. Members of
Overall’s lab at the UBC Faculty of Dentistry completed
biochemical assays and identified the toxic protein that allowed
Power, a neurologist who treats people with HIV dementia,
to test MMP2 on HIV-infected cells.
“The team and I are revved up about the new avenues
of potential treatment for people with HIV and perhaps for
other types of dementia, such as Alzheimer’s disease,”
says Power, physician-scientist in the Dept. of Clinical Neurosciences
at the University of Calgary Faculty of Medicine.
Overall has been in discussions with pharmaceutical companies
interested in testing the effectiveness of cancer drugs like
Prinomastat to block the killer enzyme. The scientists estimate
it may be five to 10 years before the drug is available to
patients.
According to UNAIDS, more than 800,000 people have AIDS
in the U.S. Some 42 million people worldwide are infected
with HIV or have AIDS, including an estimated 12 million youth.
The University of Calgary’s Faculty of Medicine consistently
ranks among the top three in federal funding per researcher,
including ranking first overall in three of the last four
years.
NB Editors: Electronic images of the researchers are available.
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