Department of Medicine

Division of Pulmonary, Allergy, and Critical Care Medicine
3459 Fifth Avenue,
628 NW
Pittsburgh, PA 15213
Phone: (412) 692-2210

Pneumocystis colonization in the pathogenesis of COPD

TRAINEE

Matthew Gingo, M.D

MENTORS

Alison Morris, M.D.		Frank Sciurba, M.D.

STUDY DESCRIPTION

Chronic obstructive pulmonary disease (COPD) causes irreversible lung damage and can lead to significant functional limitation. COPD is the 4th leading cause of mortality in the world. Smoking is the leading risk factor for COPD, but not all smokers develop the disease. Mechanisms for susceptibility to COPD in smokers have not been completely determined. One theory, known as the “vicious cycle” hypothesis, postulates that structural changes in the lungs due to cigarette smoking allow organisms to colonize the lungs resulting in subclinical infection. This low level infection leads to inflammatory cell recruitment and inflammatory cascades that further damage the lungs and ultimately result in or worsen COPD.

(Sethi, S Chest 2000)

Pneumoncystis jirovecii (Pc) is a fungal organism that may be important in COPD pathogenesis. Using sensitive techniques such as nested polymerase chain reaction (PCR), P. jirovecii can be detected in the respiratory tract of individuals without signs of pneumonia, who are presumed to be colonized. HIV-infected smokers have a high likelihood of colonization and anatomic emphysema is more common in HIV-infected subjects who are also Pc-colonized. In non-HIV-infected subjects, Pc colonization correlates with severity of COPD. However, there are no data relating Pc colonization to progression of airflow obstruction or examining its relationship to anatomic emphysema as documented by computed tomography (CT) scan.

We hypothesize that Pneumocystis colonization is more common in subjects with severe COPD than in those with milder or no disease and is associated with a more rapid progression of disease.

Accordingly, the specific aims are:

• To test the hypothesis that Pneumocystis colonization is associated with severity of airflow obstruction and radiographic emphysema in smokers.
• To test the hypothesis that Pneumocystis-colonized subjects have more rapid decline in lung function and greater increases in radiographic emphysema than similar subjects who are not Pneumocystis-colonized.

(radiology.rsnajnls.org)