Different Propionibacterium acnes Phylotypes Induce Distinct Immune Responses and Express Unique Surface and Secreted Proteomes

Propionibacterium acnes is a skin commensal bacterium that contributes to the development of acne vulgaris and other infections. Recent work revealed that P. acnes clinical isolates can be classified into distinct phylotypes, several of which have associations with healthy skin or acne. We sought to determine if these phylotypes induce different immunological responses and express protein factors that may contribute to their disease associations. We found that acne-associated P. acnes phylotypes induced 2- to 3-fold higher levels of IFN-γ and IL-17 in peripheral blood mononuclear cells compared with healthy phylotypes. On the other hand, P. acnes phylotypes associated with healthy skin induced 2- to 4-fold higher levels of IL-10. Comparative proteomic analysis of P. acnes phylotypes revealed a differential expression of several proteins, including an adhesion protein that was expressed at least 10-fold higher in acne-associated phylotypes and a cell surface hydrolase expressed in all phylotypes except those associated with healthy skin. Taken together, our data provide insight into how specific P. acnes phylotypes influence immune responses and the pathogenesis of acne.