Lipid to protein ratio plays an important role in the skin barrier function in patients with atopic eczema

Background The barrier function of the skin is primarily provided by the stratum corneum (SC), the outermost layer of the skin. Skin barrier impairment is thought to be a primary factor in the pathogenesis of atopic eczema (AE). Filaggrin is an epidermal barrier protein and common mutations in the filaggrin gene strongly predispose for AE. However, the role of filaggrin mutations in the decreased skin barrier in AE is not fully understood. It was recently shown that changes in SC lipid composition and organization play a role in the reduced skin barrier in AE. Objectives To determine whether the lipid/protein ratio and the total dry SC mass per surface area are related to the skin barrier function of controls and patients with AE. Methods A case-control study was performed to compare nonlesional and lesional skin of AE with skin of controls. The dry SC mass was determined by tape-stripping and Squamescan™. The ratio between lipid and protein bands in the Raman spectrum was used to determine the lipid/protein ratio. Skin barrier function was assessed by transepidermal water loss. Results The results show that the dry SC mass per skin area is altered only in lesional SC of patients with AE compared with control subjects. The observed reduction in the lipid/protein ratio in SC of patients with AE was more pronounced, both in lesional and nonlesional SC and correlated strongly with the skin barrier function and disease severity. Conclusions The lipid/protein ratio plays a role in the reduced skin barrier function in AE. What's already known about this topic? Filaggrin mutations are a predisposing factor for atopic eczema (AE). In nonlesional and lesional stratum corneum (SC) of patients with AE the intercellular lipid composition and organization are altered. Changes in the SC lipid properties correlate with a reduced skin barrier function, but are not associated with filaggrin mutations. What does this study add? The dry SC mass, being a measure for SC thickness, is only lower in lesional AE SC compared with SC from controls. The lipid/protein ratio in SC is reduced in both nonlesional and lesional SC of patients with AE and strongly correlates with the impaired skin barrier function and disease severity of patients with AE. The lipid/protein ratio plays a more important role in the impaired skin barrier of AE than the SC thickness.

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