The possible involvement of skin dryness on alterations of the dermal matrix

Abstract

Moisturization of the skin plays an important role in maintaining skin homeostasis. Although it is understood that skin dryness initiates the formation of fine wrinkles, there are few objective reports to support that understanding. The purpose of this study was to establish an in vitro dry epidermal model using reconstructed human epidermal equivalents (RHEEs) and to elucidate the relationship between skin dryness and alterations of the dermal matrix which is one of the causes for the formation of wrinkles. An in vitro dry epidermal model was prepared by loading a CaCl2 -filled ampoule on the surface of an RHEE. To evaluate whether the in vitro model reproduced the characteristics of in vivo skin dryness, histological studies and biological assays using a protein array were carried out. Histologically, a distinct fluorescence which originated from carbonylated protein was observed in the stratum corneum. In addition, conditioned medium from RHEEs cultured under dry conditions for 24 h revealed the secretion of several proteins, such as IL-1α, IL-1ra, IL-8, MMP-9, VEGF, M-CSF and IGFBP-2 and IGFBP-3, galectin-1, Cys-C, FGF-6, OPG, Glc and TSP4 compared with normal RHEEs. It has been reported that an increase in IL-1α and the accumulation of carbonylated proteins are observed in the intact stratum corneum in the low humidity winter season. Thus, the in vitro dry epidermal model expresses the features of in vivo skin dryness observed in the winter season. Furthermore, the conditioned medium from RHEEs cultured under dry conditions enhanced MMP-1 secretion by normal human dermal fibroblasts. Taken together, we propose the hypothesis that skin dryness contributes to alterations of the dermal matrix through the elevation of MMP-1 secretion.

3‐O‐Laurylglyceryl ascorbate improves the development of sensitive skin through the reduction of oxidative stress

“…In order to investigate the influence of skin dryness on the development of sensitive skin, we established a dry skin model prepared by exposing the surface of RHEEs to dry air . In the dry skin model, we observed significantly increased secretion of IL‐1α and NGF, and up‐regulated expression levels of NGF and MMP‐9 mRNAs (Figure ).…”

“…It has been demonstrated that IL‐1α is secreted at high levels in dry skin. In fact, it was found that the secretion of IL‐1α is increased in an artificial dry skin model . Also, IL‐1α is a proinflammatory cytokine and stimulates ROS synthesis through the activation of IL‐1 receptor‐associated kinase‐1 .…”

“…Reconstructed human epidermal equivalents were incubated for 24 hours after treatment with or without samples on the surface of the SC. The RHEEs were exposed to dry air prepared with a CaCl 2 ‐filled ampoule for 1 hour and were then incubated with fresh medium for 24 hours, after which mRNA and protein levels were quantified according to the above‐mentioned methods.…”

Correlations between skin hydration parameters and corneocyte‐derived parameters to characterize skin conditions

“…That concept is supported by the results of a dry skin model of a reconstructed human epidermal equivalent exposed to dry conditions. That dry skin model showed a higher level of IL‐1α secretion and resulted in higher CP levels than in the control, because IL‐1α generates ROS through the activation of NADPH oxidase by signaling of interleukin‐1 receptor‐associated kinase‐1 . These facts indicate the possibility of accelerating the turnover rate and accumulating CPs in dry skin, such as Groups III and/or IV, as follows: ROS accelerates the turnover rate by causing a faint inflammation in the skin and accumulates CPs by the oxidation of proteins through lipid peroxidation, which is the initiation reaction of protein carbonylation …”

The expression and function of galectins in skin physiology and pathology

“…Galectin‐1 mRNA expression in normal keratinocytes was gradually suppressed with cell growth to reach confluency, suggesting the possible involvement of galectin‐1 in keratinocyte differentiation. In a study of in vitro dry epidermal model using reconstructed human epidermal equivalents (RHEE), galectin‐1 was detected in conditioned medium from RHEEs cultured under dry conditions . The functional role of galectin‐1 in keratinocyte differentiation and skin moisturization requires further exploration.…”