Comparison of epidermal morphologic response to commercial antiwrinkle agents in the hairless mouse

The accelerated aging skin in rhino-like SHJHhr mice

SHJH^hr mice line is rhino-like mice with a nonsense Hairless (Hr) mutant, which shows the characteristic of shedding hair and wrinkled skin with increasing age. Though histological analysis and aging indexes detection, SHJH^hr mice show an increased thickness skin with degraded hair follicle and dermal cysts, and disorganized collagen fibers as well as decreased level of Hyp. Meanwhile, the aging markers p16 and p21 are significantly higher in SHJH^hr mouse skin than ICR mouse skin at same age. Moreover, the data of MDA and SOD show a higher oxidative stress in SHJH^hr mouse skin, and the levels of Nrf2 and its targets are significantly down-regulated, which suggests SHJH^hr mice have a faster aging skin and its reason maybe poor antioxidative protection. Overall, this study shows SHJH^hr mice with an accelerated aging skin, which suggests the role of Hr gene in skin aging.

Recent advances in the anti-aging effects of phytoestrogens on collagen, water content, and oxidative stress

Skin undergoes degenerative changes as it ages, which include the loss of elasticity, reductions in the epidermal thickness and collagen content, elastic fiber degeneration, and increased wrinkling and dryness. Skin aging can be significantly delayed by the administration of estrogen. Estrogen deficiency following menopause results in atrophic skin changes and the acceleration of skin aging. Estrogen administration has positive effects on human skin by delaying or preventing skin aging manifestations, but the use of estrogen replacement is a risk factor for breast and uterine cancer. Phytoestrogens are a large family of plant‐derived molecules possessing various degrees of estrogen‐like activity; they exhibit agonist or antagonist estrogenic properties depending on the tissue. These molecules could be ideal candidates to combat skin aging and other detrimental effects of hypoestrogenism. In this paper, we review the effects of phytoestrogens on human skin and the mechanisms by which phytoestrogens can alleviate the changes due to aging.

Association of Diet With Skin Histological Features in UV-B-Exposed Mice

Importance

Long-term exposure to solar radiation produces deleterious photoaging of the skin. It is not known if diet can influence skin photoaging.

Objectives

To study the influence of a calorie-restricted diet and an obesity diet in mice exposed to long-term UV-B irradiation to assess if there is an association between diet and histopathological response to UV-B irradiation.

Design, Setting, and Participants

In this animal model study in an academic setting, the dorsal skin of SKH1 hairless mice receiving normal, calorie-restricted, and obesity diets was exposed to UV-B irradiation 3 times a week for 10 weeks and were compared with corresponding controls. The mice were placed in the following groups, with 8 animals in each group: (1) intact control (C) with regular diet and no UV-B exposure, (2) intact control with UV-B exposure (CR), (3) calorie-restricted diet (CrC), (4) calorie-restricted diet with UV-B exposure (CrR), (5) obesity diet (OC), and (6) obesity diet with UV-B exposure (OR). The experiment was conducted during October through December 2013. Tissue processing and histological analysis were completed in 2016.

Main Outcomes and Measures

Histomorphometric analysis was performed on paraffin-embedded skin sections stained by histological and immunohistochemical methods for estimation of epidermal thickness, epidermal proliferating cell nuclear antigen index, collagen I, elastic fibers, fibroblasts, mast cells, dermal cellularity, and adipose layer ratio. Changes in wrinkles were noted.

Results

Hairless female mice (age range, 6-8 weeks) were obtained. With a normal diet, changes from UV-B irradiation occurred in epidermal thickness, epidermal proliferating cell nuclear antigen index, collagen I, elastic fibers, fibroblasts, and mast cells, which were modestly influenced by an obesity diet. Calorie restriction influenced the skin in nonirradiated control animals, with higher values for most variables. After UV-B exposure in animals with calorie restriction, epidermal thickness was increased, but other variables were unaffected. Animals receiving the calorie-restricted diet lost weight when exposed to long-term UV-B irradiation. Wrinkles were reduced in the calorie-restricted control group and in UV-B-exposed animals who received the obesity diet.

Conclusions and Relevance

Dietary alterations seem to modify histopathological responses to UV-B exposure in the skin of hairless mice.

Level of Evidence

NA.

Anti-wrinkle effects of fermented and non-fermented Cyclopia intermedia in hairless mice

Background

The fermented leaves and stems of Cyclopia intermedia are used to brew honeybush tea, an herbal tea indigenous to South Africa with reported anti-wrinkle effects. Wrinkle formation caused by photoaging clearly involves changes in extracellular matrix components and mechanical properties of the skin.

Methods

The inhibitory effects of honeybush extract and fermented honeybush on wrinkle formation were determined by analyzing skin replicas, histologically examining epidermal thickness, and identifying damage to collagen fibers.

Results

Honeybush extract and fermented honeybush reduced the length and depth of skin winkles caused by UV irradiation and inhibited thickening of the epidermal layer, in addition to suppressing collagen tissue breakdown reactions, indicating its potential use as a skin wrinkle prevention agent.

Conclusions

This in vivo study demonstrates that honeybush produces significant anti-wrinkle effects and is therefore of interest in anti-aging skin care products.

Active ingredients against human epidermal aging

The decisive role of the epidermis in maintaining body homeostasis prompted studies to evaluate the changes in epidermal structure and functionality over the lifetime. This development, along with the identification of molecular mechanisms of epidermal signaling, maintenance, and differentiation, points to a need for new therapeutic alternatives to treat and prevent skin aging. In addition to recovering age- and sun-compromised functions, proper treatment of the epidermis has important esthetic implications. This study reviews active ingredients capable of counteracting symptoms of epidermal aging, organized according to the regulation of specific age-affected epidermal functions: (1) several compounds, other than retinoids and derivatives, act on the proliferation and differentiation of keratinocytes, supporting the protective barrier against mechanical and chemical insults; (2) natural lipidic compounds, as well as glycerol and urea, are described as agents for maintaining water-ion balance; (3) regulation of immunological pathogen defense can be reinforced by natural extracts and compounds, such as resveratrol; and (4) antioxidant exogenous sources enriched with flavonoids and vitamin C, for example, improve solar radiation protection and epidermal antioxidant activity. The main objective is to provide a functional classification of active ingredients as regulatory elements of epidermal homeostasis, with potential cosmetic and/or dermatological applications.

Effects of topicals on the aging skin process

This article summarizes the antiaging properties of retinoids, glycolic acid, ascorbic acid, and peptide topicals. The supporting evidence is taken from the literature and the primary author's research, consisting of previously published data and new results from ongoing projects.