Commensal microbes and humans have coevolved toward a symbiotic relationship. In healthy individuals, the human microbiome has a vital role in the development of the innate and adaptive immune system, inducing protective and regulatory immunity, and the immune system maintains an optimal balance of microbes. Several acute and chronic skin conditions are a result of imbalances in the host-microbiome relationship and are accompanied by epidermal barrier disruption. This research aims to develop three-dimensional (3D) in vitro skin models integrating microbiology and immune cells to simulate this complex relationship and the effects on epidermal health. 3D models, created using the immortalised keratinocyte cell line NTERTs seeded on collagen matrices embedded with dermal fibroblasts, were colonised for 72 hrs in singular or combination inoculums of 5 prominent microbiome species: Staphylococcus epidermidis, Staphylococcus capitis, Cutibacterium acnes, Malassezia restricta and Malassezia globosa. Colonisation of 3D models showed differences in K14, K16, K10, Ki67 and involucrin expression. Epidermal thinning was observed in models colonised with singular inoculations of S. epidermidis, C. acnes and M. restricta however, restoration of epidermal thickness was observed in models colonised with the combination inoculums compared to control models. The effects of model colonisation on T cell activity and function were investigated by measuring the expression of CD69, cutaneous lymphocyte antigen (CLA) and HLA-DR in response to incubating peripheral blood mononuclear cells (PBMCs) with conditioned medium from inoculated models. PBMCs incubated with conditioned media showed increased numbers of CLA+/CD3+ T cells and HLA-DR+/CD3+ T cells, compared to those inoculated with media from sterile controls. Increased CD69+/CD3+ T cells were seen in PBMCs incubated with media from S. epidermidis, S. capitis and M. restrict. Here we demonstrate how different microbiome profiles directly alter epidermal homeostasis, skin barrier properties and immune responses.

ESDR200 - Optimised 3D skin models incorporating microbiome and host immune responses

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.