Because antiretroviral therapy has enabled people to live longer, those with HIV now face a growing epidemic of age-related chronic diseases such as chronic obstructive pulmonary disease (COPD). The reason for this increased risk, however, remains unknown. Compelling evidence suggests that HIV infection triggers an inflammatory process which causes the premature aging of inflammatory and structural cells due to cell exhaustion from repeated divisions and oxidative stress. This concept of “inflamm-aging” (coined by Claudio Franceschi) applies fittingly to the development of COPD as well, where the primary trigger is cigarette smoke.
Given the dual pro-inflammatory states of HIV and COPD, Dr. Leung hypothesizes that the accelerated development of emphysema in HIV is driven in part by inflammation-induced cell aging related to the HIV infection and potentiated in the lungs by cigarette smoke. Dr. Leung's laboratory has found peripheral leukocyte telomere lengths, a marker of cell senescence, are shorter in HIV-infected patients who also have COPD compared to HIV-infected patients without COPD. Those with the most severe airflow obstruction on spirometry and those with the greatest extent of emphysema as visualized on CT scanning also appear to have the shortest telomere lengths. The laboratory group is now exploring whether similar relationships hold in lung cells obtained from HIV-infected patients.