The Effect of Myrtacine and Celastrol‐Enriched Extract on Cutibacterium acnes Extracellular Vesicles

Background Commensal bacteria interact with each other and their environment, secreting anti‐microbial peptides, bacteriocins, and extracellular vesicles (EVs). Cutibacterium acnes ( C. acnes ), a commensal bacterium that plays a major role in acne, is classified into different phylotypes ( IA 1 , IA 2 , IB , IC , II , and III ), where overabundance of phylotype IA 1 relative to other phylotypes is found in acne lesions. EVs secreted by C. acnes phylotype IA 1 extracted from an acne lesion were previously found to induce a pro‐inflammatory response in skin models. Here, we investigated the effects of Myrtus communis extract (Myrtacine) and Celastrol‐enriched extract (CEE), anti‐inflammatory ingredients, alone or in combination, on cutaneous innate immunity induced by C. acnes IA 1 EVs. Methods This study was conducted under preventive and modulating conditions: Myrtacine alone, CEE alone, or in combination were added to the culture medium either prior to (preventive) or after (modulating) incubation with C. acnes IA 1 EVs from healthy and acne skin in immortalized keratinocytes (HaCaT) and human skin explants. Then, regulation of β‐defensin 2 (hBD2), interleukin (IL)‐6, IL‐8, IL‐17α, and IL‐36ɣ was assessed. Results Preventive and modulating applications of Myrtacine and CEE significantly reduced expression of the five immune markers induced specifically by EVs from acne‐derived C. acnes IA 1 . Conclusion Our results show that C. acnes EVs may be a target of Myrtacine and CEE. They can down‐modulate the pro‐inflammatory activity induced by EVs derived from C. acnes IA 1 from acne skin, showing the interest of these ingredients at both preventive and modulating levels in the treatment of inflammatory acne.