Visualizing the in-vivo application of zinc in sensitive skin using reflectance confocal microscopy

Hye-Jin Ahn,Ji Hwoon Baek,Young Lee,Mahin Alamgir,Babar Rao,Hyein Ham,Hae Jin Kim,Min Kyung Shin

doi:10.1038/s41598-021-87346-0

Abstract

Findings obtained on objective assessments to evaluate sensitive skin do not correlate well with the symptomatology. We utilized reflectance confocal microscopy (RCM) to compare transepidermal application of zinc in sensitive and non-sensitive skin. Thirty-six subjects participated in this study. They were divided into groups based on lactic acid sting test (LAST):‘stinger’ and ‘non-stinger’; transepidermal water loss (TEWL) measurements; and sensitivity self-assessments: ‘sensitive’ and ‘non-sensitive’. RCM images were taken to visualize transepidermal application of topically-applied zinc. The intensity of zinc reflectance at different depths was measured by ImageJ software. Based on LAST scores, the ‘stinger’ group showed significantly higher reflectance of zinc at 8 µm (stratum corneum) [face (P < 0.001), forearm (P = 0.004)], and at 80–104 µm (dermo-epidermal junction layer) on the face. High-TEWL group showed increased zinc reflectance at 8–24 µm (tight junction layer, P < 0.001). There were no significant differences amongst subjects self-reporting ‘sensitive’ and ‘non-sensitive’ skin. RCM demonstrates that in sensitive skin, there is deeper and higher reflectance of zinc at multiple depths. Structural differences are also visualized. We suggest that RCM is a useful tool for evaluating skin barrier integrity.

Highlights

Findings obtained on objective assessments to evaluate sensitive skin do not correlate well with the symptomatology
Zinc reflectance on reflectance confocal microscopy (RCM) in groups based on lactic acid sting test (LAST) scores
Previous studies have suggested that the mechanisms underlying sensitive skin (SS) are neither immunologic nor a llergic[12,13,14]; there is an increase in the permeability of the stratum corneum (SC), which leads to greater penetration of substances and more water loss[10]

Summary

Introduction

Findings obtained on objective assessments to evaluate sensitive skin do not correlate well with the symptomatology. We utilized reflectance confocal microscopy (RCM) to compare transepidermal application of zinc in sensitive and non-sensitive skin. They were divided into groups based on lactic acid sting test (LAST):‘stinger’ and ‘non-stinger’; transepidermal water loss (TEWL) measurements; and sensitivity self-assessments: ‘sensitive’ and ‘non-sensitive’. Based on LAST scores, the ‘stinger’ group showed significantly higher reflectance of zinc at 8 μm (stratum corneum) [face (P < 0.001), forearm (P = 0.004)], and at 80–104 μm (dermo-epidermal junction layer) on the face. RCM demonstrates that in sensitive skin, there is deeper and higher reflectance of zinc at multiple depths. We suggest that RCM is a useful tool for evaluating skin barrier integrity. We performed in vivo RCM analysis of the skin to evaluate the integrity of the epidermal barrier

Methods

Results

Conclusion