Molecular identification of bacterial 16S ribosomal RNA gene in liver tissue of primary biliary cirrhosis: Is Propionibacterium acnes involved in granuloma formation?

The etiopathogenesis of primary biliary cirrhosis (PBC) remains speculative . Epithelioid granulomas are often found in the vicinity of damaged interlo bular bile ducts in PBC, raising the possibility of a reaction to microbial materials. In this study, we tried to detect and identify bacterial DNA wi thin granulomatous lesions in PBC. Using liver sections from 9 patients wit h PBC and 13 control livers, granuloma in portal tracts, portal tracts with out granuloma, and adjacent hepatic parenchyma were selectively microdissec ted from sections, and then DNA was extracted from them. First, part of the bacterial 16S ribosomal RNA (rRNA) gene was amplified from DNA samples ext racted from 5 PBC and 6 control livers, and their amplicons were sequenced for the identification of bacterial species, Several indigenous bacteria we re identified. Among them, Propionibacterium ames (P, Limes) was detected a s a major clone in 20% to 50% of sequenced clones from granuloma of PBC, bu t the detection rate of P, acnes was 0% to 20% in those cloned from adjacen t hepatic parenchyma of PBC, Then, a P, acnes-specific PCR was performed us ing all microdissected samples, Distinct PCR products were identified in ep ithelioid granuloma in all 9 PBC cases. The result that P. acnes DNA is pre sent as a major clone in granulomas of PBC, suggest that P, acnes is involv ed in the pathogenesis of granuloma in PBC.