148 Fibrillin-rich microfibrils: Key components of dermal-epidermal junction architecture?

Abstract

Understanding skin health and disease across global populations is of great importance yet the majority of studies focus primarily on individuals with lightly-pigmented skin. We obtained skin biopsies from photoprotected buttock of healthy, young (18-40 years; n = 33) individuals of black African, South Asian, Hispanic and white European ancestries. Our study cohort demonstrated diversity of pigmentation levels, with skin types ranging from lightest to darkest according to Individual Typology Angle (ITA) – an objective spectrophotometric skin colour classification consisting of 6 groups: ‘very light’; ‘light’; ‘intermediate’; ‘tan’; ‘brown’; and ‘dark’. In the ‘dark’ and ‘brown’ groups, epidermal thickness and dermal-epidermal junction (DEJ) convolution were significantly increased as compared to those in the ‘light’ and ‘very light’ groups, whereas measurements for the ‘tan’ and ‘intermediate’ groups were midway (P < 0.001). Fibrillin-rich microfibrils (FRM) are located at the DEJ in candelabra-like cascades, with concentration at the base of rete pegs. The distribution of FRM was assessed across all skin types; for individuals in ‘dark’ or ‘brown’ groups FRM were significantly more abundant (44.5% and 40.2%, respectively) than those in ‘light’ and ‘very light’ groups (28.6% and 26.9%, respectively), whereas those in the ‘tan’ or ‘intermediate’ groups were midway (33.7% and 30.8%, respectively; P < 0.001). A positive correlation exists between DEJ convolution and FRM abundance (r = 0.379; P < 0.001) suggesting that FRM may contribute to DEJ structure and integrity. This study demonstrates that fundamental differences exist in skin structure and composition in individuals of diverse geographical ancestry and suggest a role for FRM in DEJ architecture.