Characterisation of skin barrier defects in atopic dermatitis patients using Infrared Spectroscopy

Abstract

Abstract Introduction Atopic dermatitis (AD) is characterised by skin barrier defects often measured by biophysical tools that observe stratum corneum (SC) functional properties. Objective To employ in vivo infrared spectroscopy alongside biophysical measurements to analyse changes in chemical composition of the SC in relation to AD severity. Methods We conducted an observational cross-sectional cohort study where attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectroscopy measurements were collected on the forearm alongside surface pH, capacitance, erythema and transepidermal water loss (TEWL) combined with tape stripping (STS) in a cohort of 75 participants; 55 AD patients stratified by phenotypic severity, compared to 20 healthy controls. Common filaggrin (FLG) variant alleles were genotyped. Results Reduced hydration, elevated TEWL and redness all associated with greater AD severity. Spectral analysis showed a reduction in 1465cm-1 (full width half maximum) and 1340 cm-1 peak areas indicative of less orthorhombic lipid ordering and reduced carboxylate functional groups that correlated with clinical severity (lipid structure r=-0.59, carboxylate peak area r=-0.50). Conclusion ATR-FTIR spectroscopy is a suitable tool for the characterisation of structural skin barrier defects in AD and has potential as a clinical tool for directing individual treatments based on chemical structural deficiencies.