Quantitative analysis of propionibacterial DNA in bronchoalveolar lavage cells from patients with sarcoidosis

Background and aim of the work: The causes of sarcoidosis are still unknown. Propionibacterial subspieces are thought to be one of the most likely sources of antigens. Here we attempted to measure the amount of propionibacterial DNA in bronchoalveolar lavage (BAL) cell samples from patients with sarcoidosis and other pulmonary diseases. Methods: We examined BAL cells from 42 patients with sarcoidosis and 30 controls. Using quantitative polymerase chain reaction (PCR) for 16S rRNA of Propionibacterium acnes (P. acnes) and Propionibacterium granulosum (P. granulosum), we measured the amount of propionibacterial DNA in 500 ng of total DNA extracted from BAL cells from patients with sarcoidosis or other lung diseases. The correlation between clinical findings and the results of quantitative PCR were analyzed. Results: The mean level of P. acnes DNA from patients with sarcoidosis was 59.9 genomes per 500 ng of total DNA, which was significantly higher than that in controls (20.7 genomes, p<0.0001). The mean level of P. granulosum DNA from patients with sarcoidosis was 1.2 genomes, which was similar to that in controls (1.0±1.6 genomes, p=0.52). The number of genomes of P. acnes in BAL cells was correlated with the serum angiotensin-converting enzyme (ACE) level and the percentage of macrophages in BAL fluid from patients with sarcoidosis. Conclusions: The amount of P. acnes DNA in BAL cells from patients with sarcoidosis was significantly higher than that in BAL cells from patients with other pulmonary diseases. P. acnes may be involved in the pathogenesis of sarcoidosis.