Presence of<i>Propionibacterium acnes</i>in granulomas associates with a chronic disease course in Dutch sarcoidosis patients

Abstract

Several studies demonstrated that <i>Propionibacterium acnes</i> may be involved in sarcoidosis pathogenesis. Presence of <i>P. acnes</i> was found in granulomas of the majority of Japanese sarcoidosis patients. However, presence of <i>P. acnes</i> in tissue has never been related to sarcoidosis phenotypes and clinical outcome. Therefore, the aims of our study were to demonstrate whether <i>P. acnes</i> can be detected in granulomas of Dutch sarcoidosis patients and to investigate whether its presence is related to a clinical phenotype and/or course of disease. Sections of formalin-fixed paraffin-embedded tissue blocks of 76 sarcoidosis patients were examined by immunostaining with a <i>P. acnes-</i>specific monoclonal antibody (PAB antibody) using a Ventana BenchMark ULTRA. Clinical outcome status (COS) was determined and classified into two phenotype groups: A: resolved, minimal or persistent disease without treatment (COS 1-6) and B: persistent disease with need for treatment (COS 7-9). <i>P. acnes</i> was detected in samples of 31 patients (41%) and located within granulomas in samples of 13 patients (17%). The frequency of <i>P. acnes</i> detected in granulomas at diagnosis was significantly higher in patients with phenotype B compared to patients with phenotype A (29% <i>versus</i> 0%, p=0.021). Presence of <i>P. acnes</i> in granulomas can be confirmed in Dutch sarcoidosis patients. It is intriguing that presence of <i>P. acnes</i> in granulomas is more frequently found in patients with chronic disease requiring treatment. This adds to the rationale that a subgroup of sarcoidosis patients might benefit from antibiotic therapy.