NEW YORK, Apr 12 (Reuters Health) -- In a finding that hints at the origins of emphysema, Ohio researchers have discovered that HIV-infected smokers are at substantial risk for the lung disease.

In the study, 114 HIV-positive adults were compared with 44 people the same age who were HIV-free. Seventeen of those with HIV had early sign of emphysema, compared with just one person without HIV, according to researchers at Ohio State University in Columbus. Emphysema is a chronic lung disease characterized by a destruction of lung tissue and a loss of lung elasticity that results in coughing, breathlessness, and fatigue. Smoking is thought to be the cause of 80% to 90% of emphysema cases, according to the American Lung Association. Among the study participants, 38 HIV-infected patients had smoked a pack a day for 12 or more years, and 14 (37%) of those individuals had signs of emphysema. None of the HIV-free individuals who had smoked that long had the lung disease, report Dr. Philip T. Diaz and colleagues in the March issue of the Annals of Internal Medicine. Despite their high rate of emphysema, none of the HIV-positive men and women in the study had a history of AIDS-related respiratory illnesses such as pneumonia. This supports the concept that HIV causes lung destruction even before pneumonia shows up, Diaz told Reuters Health in an interview. HIV may accelerate smoking-related lung damage, he added. These findings underscore how important it is for HIV patients to kick the smoking habit, according to the Ohio researcher. The finding also supports the hypothesis that along with smoking, viral infection may be involved in the development of emphysema. Some research has suggested that viruses from past respiratory infections may linger in the lungs, and the viral proteins may exacerbate airway inflammation caused by cigarette smoke. This may explain why only some smokers develop emphysema, Diaz said in the interview. In addition, the Ohio team found that lung fluid from HIV-positive subjects with emphysema had elevated levels of infection-fighting cells called cytotoxic or ``killer'' T-lymphocytes (CTLs). Recent research, the authors report, has linked CTL levels to emphysema in smokers who are not HIV-positive.

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