UCLA Department of Medicine, Division of Dermatology
2014 Research Grant Recipient
Research Grant Proposal
Variable Pathogenicity of Different Propionibacterium acnes Strains
Propionibacterium acnes is a dominant skin commensal and pathogen implicated in acne vulgaris. Recent studies have found that certain strains of P. acnes, as defined by phylotype and ribotype, are associated with different disease states. In particular, some are associated with skin from acne patients, while others are almost exclusively associated with healthy skin. This may be due to strain-specific protein virulence factors and variable capacity to induce inflammation.
To investigate this, we assessed the capacity of different strains to induce inflammation in PBMCs. Few differences were found in secretion of inflammatory cytokines associated with the innate immune system, including IL-12 and TNF-α. However, acne-associated strains had high IFN-γ secretion, indicating greater induction of Th1 pathways, with comparatively lower IL-17 secretion. In contrast, healthy skin-associated strains induced higher levels of anti-inflammatory IL-10. Furthermore, we are utilizing comparative proteomics as a basis to explain the variable pathogenicity of different strains. Cytosolic, membrane, cell wall, and secreted proteins will be analyzed, and virulence factors identified in acne-associated strains. Such virulence factors may be targeted in novel drug or vaccine treatments against only pathogenic strains of P. acnes. Additionally, less inflammatory, non-pathogenic strains as described in our study may also be highly effective as a topical probiotic treatment for cutaneous P. acnes infections.