Despite advances in therapies that have increased the life expectancy of HIV patients, doctors have noticed that these patients also exhibit signs of premature aging. Now, a new study used a biomarker to reveal that HIV ages people by an average of five years at the biological level.
"The medical issues in treating people with HIV have changed," said Howard Fox, a professor at the University of Nebraska Medical Center and co-author of the study. "We're no longer as worried about infections that come from being immunocompromised. Now we worry about diseases related to aging, like cardiovascular disease, neurocognitive impairment, and liver problems."
The team used a tool to examine the epigenetic changes - which affect DNA, but not DNA sequence - in people's cells. These changes are passed down from each cell generation to the next, in turn affecting gene expression. For the current study, the team used methylation, a specific epigenetic change that leads to the attachment of small chemical groups to DNA, as a biomarker.
"What we've seen in previous studies is that as we age, methylation across the entire genome changes," said Trey Ideker, a professor from the University of California San Diego and the study's other co-author. "Some people call it entropy or genetic drift. Although we're not sure of the exact mechanism by which these epigenetic changes lead to symptoms of aging, it's a trend that we can measure inside people's cells."
The team examined 137 patients that were enrolled in the long-term study CHARTER (the CNS Antiretroviral Therapy Effects Research study), which aims to monitor HIV-infected individuals in the process of combination antiretroviral therapy, and compared them to 44 HIV-negative control subjects in the initial analysis. Furthermore, they used a separate group of 48 subjects that were both HIV positive and negative to confirm the findings.
The results showed that HIV infection caused an average increase in biological aging of 4.9 years, and this change is connected to an increased mortality risk of 19 percent.
"We set out to look at the effects of HIV infection on methylation, and I was surprised that we found such a strong aging effect," Ideker said.
"Another thing that was surprising was that there was no difference between the methylation patterns in those people who were recently infected [less than five years] and those with chronic infection [more than 12 years]," Fox added.
It is possible that drugs could be developed to control the epigenetic changes in HIV patients that lead to aging, but the team believes that the most important takeaway from the study is the fact that these patients are more at risk of suffering from age-related diseases, which can be countered by diet, exercise and curbed drug and alcohol use.
The findings were published in the April 21 issue of the journal Molecular Cell.
