Quantitative PCR of mycobacterial and propionibacterial DNA in lymph nodes of Japanese patients with sarcoidosis

Genome-wide search for sarcoidosis susceptibility genes in African Americans

“…Several environmental risk factors, such as bacterial infection, pine pollen, clay eating, wood dust exposure and occupational exposure to metals, silica, or talc, while previously implicated, remain unconfirmed. [1][2][3][4][5][6][7][8] Age, race and gender are the most clearly defined risk factors for sarcoidosis. 9,10 Genetic variation likely explains why granulomatous inflammation occurs in some individuals in response to the 'sarcoidosis antigen'.…”

Evidence for Mycobacteria in Sarcoidosis

“…A group in Greece reported that 72% of sarcoidosis tissues contained amplifiable MTB DNA, yet they also isolated propionibacteria DNA from 43% of sarcoidosis samples (101). Moreover, studies in Japan have found high levels of propionibacteria DNA but no mycobacterial DNA in sarcoidosis samples (74). However, because propionibacteria are the most common commensal bacteria in the lungs of Japanese patients, the high frequency of propionibacteria nucleic acid in sarcoidosis lung tissue may not reflect causality (102).…”

“…In an interesting case series, three out of four cases of recurrent lung sarcoidosis were positive for identical non-MTB DNA sequences in pre-and posttransplantation lung biopsies despite an absence of clinical mycobacterial infection (72), suggesting a causal relationship between nonpathogenic mycobacteria and sarcoidosis. These and similar studies have been criticized for their small size and high false-positive PCR rate, especially because other investigators failed to find mycobacterial DNA or RNA in sarcoidosis tissues (73)(74)(75). Moreover, finding mycobacterial components in a sarcoidal granuloma raises the question of possible misdiagnosis, especially with the atypical mycobacteria.…”

Sarcoidosis: Unknown Etiology and Genetic Predisposition Provides Therapeutic Challenges

“…Without 100% detection of P. acnes in sarcoidosis patients additional quantitative analysis detected P. granulosum in 60% of sarcoidosis patients, including those with undetectable P. acnes [56].…”

“…To combat possible contamination of cultured isolates with commensal P. acnes and to overcome the slow growth delay typically associated with bacteria culturing, additional immunological and molecular mechanisms were utilized.Using quantitate PCR analysis, detection of Propionibacterium species yielded varying results from 0-80% detection in sarcoidosis patients to 0-30% in control patients [54][55][56]. Without 100% detection of P. acnes in sarcoidosis patients additional quantitative analysis detected P. granulosum in 60% of sarcoidosis patients, including those with undetectable P. acnes [56].…”