About 30 percent of people worldwide—more than 10 million individuals—are not only infected with AIDS-causing HIV but also with the hepatitis C virus (HCV). That dual whammy takes its toll on the immune system and may accelerate the aging process in those patients, according to Vanessa Pirrone, a research instructor in the Department of Microbiology and Immunology.

In a new study supported with University developmen- tal funding, she looks at the impact of co-infection on an aging population. The two viruses “can exacerbate one another,” Pirrone says. Co-infected patients have more rapid progression of liver disease, as well as higher risks for cardiovascular problems, diabetes and carcinomas.

“In general, you have further waning of the immune sys- tem and more immunosenescence,” she says. Normally, the immune system in healthy people slows as they reach their 70s, 80s and 90s. But in the HIV-infected population, problems start to arise when they are only in their 50s. Older HIV-infected patients also suffer two to three times the fre- quency of dementia than younger people with the disease.

Preliminary results from analysis of immune cell and plasma samples from two groups—age 35 and younger and age 50 and older—suggest that co-infection with HCV significantly further accelerates the effects of the aging process in patients with HIV, Pirrone says. She suspects that the two viruses act synergistically by speeding up immune system activation, the excessive and aberrant response of the immune system to HIV that plays a major role in AIDS’ progression.

“The co-infected are not quite as healthy as the mono-infected patients,” she says. “We’re looking to see why that is.” Pirrone’s project will investigate the effect of aging on immune-regulating molecules (cytokines and chemo- kines) as well as on genes, proteins and pathways in those who are co-infected compared to those who are only infected with HIV or HCV.

She will also study different cell populations and determine the mechanisms involved in chronic immune activation and viral immunity in the two age groups.

“It is really untested waters,” Pirrone says.

The study is tapping HIV and co-infected patients who are part of the large group that researchers are monitoring through Drexel’s HIV/AIDS clinic.

Samples of immune cells and plasma from these patients show that those with only HIV infection show increased viral loads as they age, even when they diligently pursue highly active antiretroviral therapy, or HAART. “You would expect the viral load to go down,” Pirrone says, noting that HAARTs have improved lifespans so that more AIDS pa- tients are living into their 50s and beyond. “But the viral load is increasing regardless of the therapy.”