Figure 1.

Cutaneous lipids preserve the epidermal permeability barrier and influence host–microbe interactions. The epidermis consists of multiple layers of phenotypically distinct keratinocytes that contribute to stratification. (A) Keratinocytes in each tier exhibit different adhesion structures responsible for maintaining skin integrity. Epidermal lipids are observed in the differentiating layers of the epidermis, while sebaceous lipids are secreted from sebaceous glands. (B) Molecular arrangement of the main stratum corneum lipids from [51] and effects of those lipids on Staphylococcus aureus colonisation [52,53,54]. (C) Skin microbiota also produce metabolites to utilise cutaneous lipids, generating products that contribute to barrier homeostasis (e.g., sphingomyelinase in Staphylococcus epidermidis [55]). (D) In pathological conditions, these interactions may negatively affect skin physiology (e.g., Cutibacterium acnes enhancing inflammation [56]). SCFA = short-chain fatty acids.