Acne vulgaris is an inflammatory disease resulting from multiple processes within the pilosebaceous unit resulting in Cutibacterium acnes overgrowth, hyperactivity of sebaceous gland, hyperkeratinization, production of oxidized free fatty acids triggered by C.acnes and severe inflammation. Exposure to sunlight in presence of severe acne leads to an increase of sebum production further contributing to acne worsening. In this work, we present a preclinical experimental model based on reconstructed human epidermis (RHE, Episkin SA) colonized with C.acnes ATCC11827 (phylotype 2, pathogen) developed to deeper investigate one of the molecular mechanisms behind the complexity of acne pathology. RHE at day 17 were colonized with C.acnes (106-107 CFU/mL) in presence of a “sebum like” mixture of unsaturated and saturated triglycerides. 24h after infection, RHE were exposed to 2MED UVA+UVB (Oriel 1KW solar simulator) and then cultured for 48h in incubator (5% CO2). The different series, negative control and colonized controls with/without UV exposure were compared 48h after the colonization (24h after UV exposure). The following parameters were quantified: CFU/mL in apical part of RHE, transcriptional activity of TLR2, IL-1b, IL-8 and TP53 by qRT-PCR and histo-morphology analysis to address morphological modifications occurred at barrier structure level. A stable viable bacterial load and homogeneous distribution of C.acnes was observed during the experiment. UV exposure has induced sunburn cells (SBC) formation and significant modification of filaggrin localization and expression. The main morphological modifications have concerned keratinocytes differentiation and stratum corneum structure that was affected in the long-term cultivation. A significant over-expression of the 3 inflammatory genes was found in the colonized RHE in presence of UV light compared to the colonized controls. This approach is proposed as useful tool to better understand the stress factors induced by C.acnes specific mechanisms or environmental conditions involving complex pathways that cannot be explored in vivo.

ESDR389 - Reconstructed Human Epidermis Colonized with C.acnes: Pro-inflammatory and Oxidative Stress Response

The scientific meeting of the European Society for Dermatological Research (ESDR) is held yearly, usually in September. With an international attendance of more than 1000 skin scientists from around the globe, the four-day event includes short oral presentations from peer-reviewed abstracts, keynote lectures from international experts, sponsored symposia, satellite programs, educational events as well as an important focus on posters, networking and building collaborations amongst scientists. For more information about this year’s meeting visit our website.