By Kevin Fitzsimons

Philip Diaz studies CT scans of a patient's lungs.

HIV increases smokers' risk of emphysema

Smokers who test positive for the human immunodeficiency virus (HIV), the virus that causes AIDS, may be up to seven times more likely to develop emphysema, new research suggests.

The findings have important implications for the health of people with HIV, and they may also help doctors understand the cause of emphysema in smokers generally.

Emphysema is a chronic, debilitating lung disease that strikes some long-term smokers. Advanced emphysema results in breathlessness following even minor exertion.

The disease usually strikes people who are in their 50s and 60s, but in this study, early emphysema was detected in people with an average age of 35.

"Our results show that HIV-positive smokers, even before they develop other complications like pneumonias, appear to have a much higher risk of smoking-related lung damage,"said Philip Diaz, associate professor of internal medicine and a member of Ohio State's Heart and Lung Institute.

The study, conducted by Diaz and a team of researchers, was published in a recent issue of the Annals of Internal Medicine. It involved 114 otherwise healthy HIV-positive smokers and 44 HIV-negative controls matched for age and smoking history. Evidence of emphysema was based on high-resolution computerized tomography (CT) scans.

The results showed early signs of emphysema in 15 percent (17 of 114) of the HIV-positive smokers and in 2 percent (1 of 44) of the HIV-negative smokers.

The results were more pronounced for HIV-positive smokers with a history of 12-pack years or more of smoking (i.e., a pack a day for 12 years). Here, 37 percent (14 of 38 people) of the HIV-positive group showed signs of emphysema; no cases were found among 14 people in the control group.

However, most of the participants were studied prior to 1998, before the widespread availability of protease inhibitors which are often effective in controlling AIDS symptoms. Thus, only 10 percent of the HIV-positive smokers in the study were using the life-prolonging, highly active antiretroviral therapy (HAART), which is the standard of care today.

Because HAART prolongs life, it may offer some protection from the onset of emphysema in HIV-positive smokers, a possibility borne out by some preliminary data gathered by Diaz and the team of researchers.

"On the other hand, people on HAART are living longer, so emphysema could remain a problem for them,"he speculated.

"I think until proven otherwise, our study supports the concept that people with this chronic viral infection are more predisposed to adverse effects of cigarette smoking. It makes it all the more important for physicians to encourage people who are HIV positive to quit smoking."

The findings also revealed a higher level of cytotoxic lymphocytes (CTLs) in fluids rinsed from the lungs of the HIV-positive smokers. This suggests that CTLs could play an important role in the development of the disease, something that scientists still understand poorly even in the general populations of smokers.

This research supports a relatively new theory that links the destruction of lung tissue occurring during emphysema to the work of CTLs. CTLs destroy cells that are infected by virus. "Some people think what separates the smokers who get emphysema from those who don't might be a viral infection that's been latent in their lungs and that activates CTLs,"said Diaz. "Our observations support that hypothesis."

Recent biopsy studies of people with emphysema from the general population also show that CTLs could be important. Diaz and his team are now studying lungs of people who have died of HIV for evidence of viral infection in the lungs.

Key found to growing, separating human cells

Researchers have taken the first step toward differentiating human cells in an artificial growth medium, which may one day aid the production of human organs for transplant. "We're laying the foundation for artificially growing cells that develop specialized characteristics, just as cells that make up organs naturally do in the body,"said Douglas Kniss, professor of obstetrics and gynecology. In tests, human placental cells initiated the same kind of chemical changes as stem cells do before they differentiate.

www.acs.ohio-state.edu/units/research/archive/diffcell.htm

AIDS illnesses linked to memory problems

People whose diagnoses of AIDS were based on specific illnesses are at greater risk of developing memory problems than those whose diagnoses grew from low immune-cell counts. A study found that AIDS patients with so-called AIDS-defining illnesses are most at risk for memory loss and other cognitive problems. The findings are important because AIDS treatment regimens are complex, and a person with memory or cognitive problems may not be able to follow them, said Robert Bornstein, professor and chair of psychiatry.