The Role of Propionibacterium acnes in the Pathogenesis of Sarcoidosis and Ulcerative Colitis: How This Connection May Inspire Novel Management of These Conditions

A lesser-acknowledged role of Propionibacterium acnes is its effect on the development of sarcoidosis. This literature review not only further explores this association but also that of Propionibacterium acnes and other inflammatory conditions, such as ulcerative colitis and pyoderma gangrenosum, acne, ulcerative colitis syndrome (PAC syndrome). This article reviews the effect that isotretinoin, a commonly used treatment of acne, has on the pathogenesis of ulcerative colitis, and the immune dysregulation and genetic susceptibility of individuals prone to developing acne, sarcoidosis, and ulcerative colitis. Literature for this article review was obtained from PubMed by utilizing both regular keywords and medical subject heading (MeSH) subheadings for data gathering. Regular keywords were: Propionibacterium acnes, sarcoidosis, ulcerative colitis, and isotretinoin. MeSH subheadings used were: Propionibacterium acnes/immunology, Propionibacterium acnes/pathogenicity, Propionibacterium acnes/genetics, sarcoidosis/immunology, and sarcoidosis/genetics. Following the application of inclusion and exclusion criteria, a total of 5172 publications were obtained. A total of 5086 publications were removed due to a lack of relevancy to outcomes of interest. The remaining 86 publications from all the regular and MeSH keywords were selected due to relevancy to outcomes of interest. Following this, a refined manual search was done, with the removal of duplicates, and 33 publications from PubMed were selected for review. Following a review of these records, Propionibacterium acnes was repeatedly concluded to be a causative agent of sarcoidosis. Variable results for the association between Propionibacterium acnes and ulcerative colitis were found. Most studies showed no significant association between the use of isotretinoin and the development of ulcerative colitis. A strong overlapping role of genetic susceptibility and immune dysregulation in the pathogeneses of sarcoidosis, ulcerative colitis, and Propionibacterium acnes was found.