London, July 14 : An international team of researchers have shed light on why HIV progresses faster in women than in men with same viral load.

Researchers from Ragon Institute of Massachusetts General Hospital (MGH), MIT and Harvard claim to have identified a receptor molecule that responds to the HIV-1 virus differently in women.

"This study may help to account for reported gender differences in HIV-1 disease progression by demonstrating that women and men differ in the way their immune systems respond to the virus," Nature magazine quoted Dr. Marcus Altfeld, of the Ragon Institute and the MGH Division of Infectious Disease, as saying.

"Focusing on immune activation separately from viral replication might give us new therapeutic approaches to limiting HIV-1-induced pathology," he added.

During the study, the researchers focused on plasmacytoid dendritic cells (pDCs), among the first cells of the immune system to respond to HIV-1 and other viral pathogens.

Previous studies have shown that pDCs recognize HIV-1 with the help of a receptor called Toll-like receptor 7 (TLR7) that triggers the production of interferon-alpha and other important immune system molecules.

It has also been shown that progesterone may modulate pDC activity.

Supporting the previous study results, the researchers found that pDCs from postmenopausal women produced levels of interferon-alpha in response to HIV-1 that were closer to levels observed in men.

They also found that in premenopausal women, higher progesterone levels correlated with increased activation of pDCs in response to HIV-1.

Since activation of T cells predicts the progression of HIV-1 infection to AIDS, the researchers found that stimulation of pDCs in response to HIV-1 led to the subsequent activation of CD8+ T cells by means of interferon-alpha secretion.

For further study, the researchers tested blood samples taken from a group of chronically HIV-1-infected women and men prior to treatment initiation and confirmed that women had higher levels of CD8+ T cell activation than did men with the same blood levels of HIV-1.

"While stronger activation of the immune system might be beneficial in the early stages of infection, resulting in lower levels of HIV-1 replication, persistent viral replication and stronger chronic immune activation can lead to the faster progression to AIDS that has been seen in women," Altfeld added.

The study has been published in the journal Nature Medicine. (ANI)