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STUDY: Surprising finding may explain HIV’s hold on the body
JOURNAL: Institut Cochin
AUTHORS: France Pietri-Rouxel
ABSTRACT: The AIDS virus, long known to infect immune system cells, also takes up residence in fat cells, French researchers report. They found HIV in the fat tissue of patients with irregular fat deposits known as lipodystrophies — a side-effect of long-term drug treatment for the virus.
COMMENTARY: THE FINDING could help explain why HIV has proven impossible to eradicate, and it may open a whole new window in understanding how the fatal and incurable virus works.
France Pietri-Rouxel of the Institut Cochin in Paris and colleagues stumbled upon the finding by accident, when she was treating HIV patients whose body fat began to redistribute itself in odd ways — the condition known as lipodystrophy.
A specialist in fat tissue, she was removing fat from the abdomens of the patients and injecting it into their cheeks to fill out their faces. “The thin, gaunt face is one of the disturbing signs of an HIV patient,” she said in an interview.
Jacques Leibowich of Hopital Foch in Suresnes, France, asked her for samples of the fat tissue for an unrelated study he was doing. To his surprise, HIV DNA turned up in the tissue. T
The human immunodeficiency virus, discovered 20 years ago, is known to infect immune system cells. It favors CD4 T-cells, lymphocytes that respond to a viral infection.
The virus grapples the cells, injects its genetic material and forces the cell to manufacture more copies of itself.
To do this it uses receptors, a kind of molecular doorway into the cell. The two main receptors HIV uses are called CD4 and CCR5 — both found on T-cells.
But fat cells also have CCR5 receptors, and now it appears HIV must use these to infect fat cells.
Robert Gallo, head of the Institute and one of the men who discovered HIV, said the finding could help explain why HIV lurks in the body for years despite treatment with drugs that can suppress its activity. Experts believe it must lie low in a pool of cells known as a reservoir.
“That could be a major contributor to the reservoir,” Gallo said. “It could also be the reason that some people with HIV lose fat.”
Pietri-Rouxel said all seven patients she treated had HIV in their fat. All were taking drug cocktails known as highly active antiretroviral treatment or HAART, which had reduced the virus in their body to levels that cannot be detected in blood tests.
“What we don’t know is the relationship between the treatment and the infected cells,” Pietri-Rouxel said.
“Could the treatment have caused it?” asked Leibowich.
Pietri-Rouxel said there was some evidence the virus was acting as it does in other cells and using them as little factories to make copies of itself, but this was not yet certain.
If all fat cells in an HIV patient are infected, the implications could be serious, Leibowich said. “A person has about a kilogram (2 pounds) of lymphocytes,” he said. “But someone like me has 15 kilograms (30 pounds) of fat. So fat cells could be the more important source.”
The researchers now plan to look for infected fat cells in other HIV patients, especially those who have not developed lipodystrophies.