Skin dysbiosis in inflammatory acne lesions and the role of Cutibacterium acnes biofilm. SCARAB

Acne vulgaris is a common inflammatory disorder affecting more than 80% of young adolescents. Cutibacterium acnes plays a role in the pathogenesis of acne lesions, although the mechanisms are poorly understood. The study aimed to explore the microbiome at different skin sites in acne patients and the role of biofilm production in promoting the growth and persistence of C. acnes isolates. Swabs from non-inflammatory (NI) and inflammatory lesions (LA) of 10 acne patients and the skin of 10 healthy subjects (HS) were analyzed using 16S rRNA sequencing. In addition, traditional culture methods were combined with whole-genome sequencing. Microbiota analysis showed a significantly lower alpha diversity in LA than in NI and HS. Differences at the species level were driven primarily by the overabundance of C. acnes on LA than NI and HS. The phylotype IA1 was more represented in the skin of acne patients than HS. Genes involved in lipids transport and metabolism, as well as potential virulence factors associated with host-tissue colonization, were selectively detected in phylotype IA1 strains. Additionally, the IA1 isolates were more efficient in early adhesion and biomass production than other phylotypes showing a significant increase in antibiotic tolerance for ampicillin, benzylpenicillin, clindamycin, and doxycycline. Our data indicate a site-specific dysbiosis in LA compared to HS. Dysbiosis in the LA microbiome and colonization by virulent and highly tolerant C. acnes phylotypes may explain the prevalence of acne in a part of the population, despite the universal carriage of the microorganism.