Investigation of water bonding status of normal and psoriatic skin in vivo using diffuse reflectance spectroscopy

Abstract

Psoriasis affects more than 125 million people worldwide, and the diagnosis and treatment efficacy evaluation of the disease mainly rely on clinical assessments that could be subjective. Our previous study showed that the skin erythema level could be quantified using diffuse reflectance spectroscopy (DRS), and the hemoglobin concentration of most psoriatic lesion was higher than that of its adjacent uninvolved skin. While the compromised epidermal barrier function has been taken as the major cause of clinical manifestation of skin dryness and inflammation of psoriasis, very few methods can be used to effectively evaluate this function. In this study, we investigate the near infrared spectroscopic features of psoriatic (n = 21) and normal (n = 21) skin that could link to the epidermal barrier function. From the DRS measurements, it was found that the water bonding status and light scattering properties of psoriasis are significantly different from those of uninvolved or normal skin. The connection between these parameters to the epidermal barrier function and morphology will be discussed. Our results suggest that objective evaluation of epidermal barrier function of psoriasis could be achieved using a simple DRS system.

Investigating the clinical implication of corneometer and mexameter readings towards objective, efficient evaluation of psoriasis vulgaris severity

“…Therefore, it is reasonable to interpret that the Corneometer readings had decent correlation to the PASI “thickness” and “desquamation” scores. On the other hand, the PWFR values gathered from the DRS system is an effective indicator of water-protein binding status in epidermis which directly reflects the skin barrier function 10 . Abnormal desquamation is a visible clinical manifestation of the disrupted skin barrier function.…”

“…In short, an ANN model was trained with diffuse reflectance computed from Monte Carlo simulations to determine the spectral information of tissue absorption and reduced scattering from the measured diffuse reflectance spectra. Specifically, the model was used to recover the skin absorption and reduced scattering spectra in the wavelength range from 500 to 1380 nm, from which we used a wavelength span of 500 nm to 600 nm to quantify the hemoglobin level of skin and another wavelength range from 1230 to 1380 nm to investigate the state of dermal water-protein binding state 7 , 10 .…”

“…In its basic configuration, a DRS system consists of a light source and light detectors to capture dermal reflectance, from which the spectroscopic features of skin are analyzed via computation models to deduce the skin properties 6 – 8 . Previously, we reported the use of spatially resolved DRS in quantifying microvasculature and morphology of psoriasis vulgaris 9 , 10 . Specifically, the increases of hemoglobin concentration in the dermis as well as the mean size of tissue scatterers induced by epidermal hyperplasia were observed in psoriasis vulgaris patients.…”

Altered structure indicating reduced barrier function of lesional compared to non‐lesional psoriatic skin—A non‐invasive in vivo study of the human stratum corneum with confocal Raman micro‐spectroscopy

“…Water is located intra-as well as extracellularly in the SC and forms bonds of different strength (ranging from tightly bound to unbound water) 25 with ICL, keratin and NMF, depending on the SC depth 22 as well as age and other factors. [26][27][28] Several methods have been used to examine the psoriatic SC, like TEWL, corneometry, 'attenuated total reflectance-Fouriertransform infrared spectroscopy', 29,30 tape-stripping, 31 multiphoton CARS tomography, 32 optical coherence tomography, 33 diffuse reflectance spectroscopy, 34 scanning electron microscopy 35 and laser scanning microscopy. 36,37 Previous studies have revealed a less ordered SC structure regarding lipid organisation in psoriatic lesions, 10,36,38 which is thought to be partly due to differences in the composition of ceramides.…”

“…Several methods have been used to examine the psoriatic SC, like TEWL, corneometry, ‘attenuated total reflectance—Fourier‐transform infrared spectroscopy’, 29,30 tape‐stripping, 31 multiphoton CARS tomography, 32 optical coherence tomography, 33 diffuse reflectance spectroscopy, 34 scanning electron microscopy 35 and laser scanning microscopy 36,37 . Previous studies have revealed a less ordered SC structure regarding lipid organisation in psoriatic lesions, 10,36,38 which is thought to be partly due to differences in the composition of ceramides 38,39 .…”