AIDS Virus Lurks in Fat Cells, French Study Finds
HIV, long known to infect immune system cells, also takes up residence in fat cells, according to French researchers with the Institut Cochin in Paris. France Pietri-Rouxel and colleagues 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. They stumbled upon the finding when Pietri-Rouxel, a specialist in fat tissue, was removing fat from the stomachs of HIV patients with lipodystrophy and injecting the fat back into their cheeks to help fill out their gaunt faces. Jacques Leibowich of Hôpital Foch in Suresnes 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.
HIV favors the immune system's CD4 T-cells, lymphocytes that respond to a viral infection. The virus uses two main receptors, CD4 and CCR5 -- both found on T cells -- as a molecular entrance, injecting its RNA and forcing the cell to manufacture copies. But fat cells also have CCR5 receptors, and now it appears HIV must use these to infect fat cells, Leibowich and Pietri-Rouxel told a meeting of the Institute of Human Virology, part of the University of Maryland-Baltimore. Institute head Robert Gallo said the finding could help explain why HIV lurks in the body for years despite treatment with drugs that can suppress its activity. "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 highly active antiretroviral treatment, which reduced the virus to levels undetectable in blood tests. If all fat cells in an HIV patient are infected, the implications could be serious, said Leibowich. "A person has about a kilogram [two 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 plan to look for infected fat cells in other HIV patients, especially those who have not developed lipodystrophies.