by Bill Buchanan, Pitt Men’s Study Clinic Coordinator
For decades we’ve wondered why some people don’t progress to AIDS as quickly as others. Now we’ve discovered at least one of the reasons, and you “non-progressors” out there can thank your parents. As for everyone else, this might turn into a new and innovative way to control HIV.
Pitt Men’s Study researchers looked at 30 years of data and samples provided by Study volunteers and studied dendritic cells and B cells, both important components of our immune systems. Those men who progressed slowly had dendritic cells and B cells that contain less cholesterol than the cells of men who progressed more quickly.
That’s right, low levels of cholesterol in the membranes of these cells is protective against HIV. Why? HIV needs cholesterol to transmit from one cell to another. If the transmission of HIV between cells is slowed down because there’s not enough cholesterol in the immune cells, the virus can’t multiply as quickly; and if the virus is not multiplying quickly, it can’t hurt one’s immune system as quickly. This study also indicated that this could be an inherited trait, since it was also observed using cells that were stored in the Pitt Men’s Study freezers before these volunteers become infected with HIV.
Dendritic cells are particularly crucial for HIV multiplying in our bodies because they pass the virus on to our T cells, the cells that are most responsible for viral replication. For most people today, taking highly active antiretroviral therapy interrupts viral replication and halts progression to AIDS. But now we know why some people progressed to AIDS more slowly than others without using HIV meds.
“We’ve known for two decades that some people don’t have the dramatic loss in their T cells and progression to AIDS that you’d expect without drug therapy,” said lead author Giovanna Rappocciolo, Ph.D., an assistant professor at Pitt’s Graduate School of Public Health. “Instead the disease is much slower to progress, and we believe low cholesterol in dendritic cells may be a reason.”
“We couldn’t have made this discovery without the dedication of our volunteers. Results like ours are the real pay-off of the past three decades of meticulous data and specimen collection,” said senior author Charles Rinaldo, Ph.D., chairman of Pitt’s Department of Infectious Diseases and Microbiology, and principal investigator of the Pitt Men’s Study.
This discovery was featured in the April 29, 2014 edition of mBio, the journal of the American Society for Microbiology.
IMPORTANT DISCLAIMER: The cholesterol discussed above is not the same as the cholesterol measured in routine blood tests. In fact, our study’s non-progressors had similar levels of blood cholesterol as the progressors did. Notably, we used statins to treat dendritic cells and B cells from HIV negative men in the study’s lab (in vitro), and this lowered the cholesterol in their membranes and shut down HIV transmission. However, we do not know if ingesting statins will have the same effect in people (in vivo) and do not endorse anyone relying on their blood cholesterol results or their use of statins to determine their HIV treatment.