Molecular dynamics in the stratum corneum of plantar heels in atopic dermatitis patients

The skin acts as an effective barrier against the uptake of hazardous chemicals and microorganisms as well as prevention of extensive water loss. These barrier functions are mainly assured by the outermost layer of the skin, the stratum corneum (SC). In conditions such as atopic dermatitis (AD)-a chronic inflammatory skin disease-these barrier functions can become impaired. Although AD is driven by environmental triggers and inflammation in the deeper skin layers, its effects are also evident in the SC, which is a lipid-corneocyte composite membrane. This study characterizes molecular dynamics of lipids and protein components in SC samples from the plantar heel region of AD patients aged 60-80 years, as well as healthy volunteers in the same age range and in the 20-30 age group. Using solid-state NMR, we show that, compared with age-matched healthy controls, lipids in the AD SC exhibit reduced mobility under dry conditions. With increasing hydration, mobility of both lipids and the protein keratin increases, with a stronger response observed in the AD SC. These molecular-level insights could provide further insight in the development of therapeutic strategies aimed at restoring properties of healthy skin.