RESUMEN
Background: Aging-related degeneration of elastic fibres causes skin wrinkles and loss of elasticity. A correlation has been reported between dermal elastic fibre degradation and wrinkles. However, the mechanism of wrinkle formation is complex and unclear. To establish methods for treating wrinkles, it is necessary to understand the aging-related morphological alterations underlying elastin fibre degradation or disappearance. Objectives: To image and analyse aging-related three-dimensional (3D) morphological alterations of elastic fibres in the eyelid and abdominal skin. Methods: Excised human eyelid and abdominal skin tissues were examined. The structure of elastic fibres in the skin tissues was examined via nuclear, tropoelastin and fibrillin-1 immunostaining. Then, 3D imaging was performed using a confocal laser microscope and tissue decolourization technology. Images were analysed using a computational method. Results: The decolourization technology made it possible to image elastin fibres in 3D, and we devised a method for analyzing the elastin fibre structure using computational methods. It was quantitatively shown that the eyelid skin has a more complex fibrous structure than the abdomen, and the fibres became curved, shortened and thickened with age. Conclusions: We provide a novel 3D analysis method for elastin fibres and report age-related alterations in elastin fibre structure in the human eyelid and abdominal skin. This method contributes to the understanding of elastin fibre degeneration in more detail than conventional methods. Applying this 3D analysis method to skin tissues will contribute to a better understanding of age-related changes in fibres and to the development of novel wrinkle treatments.
RESUMEN
OBJECTIVE: Previous studies have shown that enolase-1 (ENO1) in the stratum corneum (SC) is more highly expressed in patients with atopic dermatitis (AD) than in healthy individuals, suggesting that it is a novel biomarker for evaluating skin condition in patients with AD. However, the mechanism underlying high ENO1 expression in the SC and its pathological relevance in AD are unclear. In this study, the relationship between ENO1 expression and keratinization of epidermis was investigated, and the role of high ENO1 expression in keratinocytes was characterized. METHODS: ENO1 expression and morphological characteristics were examined in SC from the cheeks of 24 patients with AD. Additionally, the localization of ENO1 in the excised human epidermis was observed. Moreover, to analyse the role of ENO1 in cellular barrier function, tight junction proteins (TJs) and transepithelial electrical resistance (TEER) in keratinocytes with ENO1 overexpression were evaluated. Furthermore, the localization of ENO1 and plasminogen in keratinocytes was evaluated by immunostaining, and the cellular barrier function in keratinocytes was examined after treatment with tranexamic acid (TXA). RESULTS: ENO1 expression was substantially correlated with the rate of nucleated corneocytes in AD. In addition, ENO1 localized in the basal to spinous layers, but was its expression dramatically decreased in healthy human SC. ENO1 overexpression in human epidermal keratinocytes reduced the expression of TJs (claudin-4, E-cadherin, tricellulin, and occludin) and TEER, and treatment with anti-ENO1 IgG reversed these effects. ENO1 colocalized with plasminogen in keratinocytes. Treatment with TXA rescued the ENO1-induced reductions in TJ and TEER expression. CONCLUSION: We found a substantial correlation between ENO1 expression and the rate of nucleated corneocytes in AD and decreased ENO1 expression with nuclear disappearance. These results suggest that high ENO1 expression in the SC of AD is caused by deficient keratinization, which is an AD characteristic. Moreover, ENO1 overexpression in keratinocytes promoted dysfunction of TJ dynamics, leading to reduced integrity of the cellular barrier, and these effects might be mediated by plasmin activity. We propose that ENO1 is a useful indicator of parakeratosis and might have a potential role in cellular TJ barrier function in the epidermis.
