Protein structure is changed in psoriatic skin on the unaffected region — Imaging possibility with ATR-FTIR spectroscopy

Abstract

Psoriasis is a T lymphocyte-mediated inflammatory disorder that affects the skin. A number of studies have demonstrated the occurrence of lipid alterations in psoriatic skin, resulting in a highly perturbed stratum corneum (SC). Relatively little attention has been paid to the protein conformation of the SC. In this study, the attenuated total reflection Fourier transform infrared (ATR-FTIR) spectrum of the untreated psoriatic patients' unharmed SC was obtained after tape stripping. We focused on the amide-I band components in order to establish whether there are any protein alterations in the intact areas of psoriatic skin. Fourier self-deconvolution (FSD) of the amide-I band was followed by curve-fitting to generate the underlying components. Integration of band areas provided an estimate of the secondary structure. The results indicated decreases in all amide-I band components, the peak at 1660cm−1 revealing the most dramatic change. This peak is characteristic of the turn structure in the protein chain. The decrease is marked in the case of the β-sheet structure at 1630cm−1 too. This ATR-FTIR imaging is a rapid and simple noninvasive method, promotes a better understanding of the disease, and would be helpful in following the treatment.