UV, stress and aging

Anticedants and natural prevention of environmental toxicants induced accelerated aging of skin

Skin is frequently exposed to a variety of environmental and chemical agents that accelerate ageing. External stress such as UV radiations (UVR) and environmental pollutants majorly deteriorate the skin morphology, by activating certain intrinsic factors such as Reactive Oxygen Species (ROS) which trigger the activation of Matrix Metalloproteinases (MMPs) and inflammatory responses hence damaging the extracellular matrix (ECM) components. To counter this, an exogenous supply of anti-oxidants, is required since the endogenous anti-oxidant system cannot alone suffice the need. Bio-prospecting of natural resources for anti-oxidants has hence been intensified. Immense research is being carried out to identify potential plants with potent anti-oxidant activity against skin ageing. This review summarizes the major factors responsible for premature skin ageing and the plants being targeted to lessen the impact of those.

Effects of baicalin against UVA-induced photoaging in skin fibroblasts

Ultraviolet A (UVA) radiation contributes to skin photoaging. Baicalin, a plant-derived flavonoid, effectively absorbs UV rays and has been shown to have anti-oxidant and anti-inflammatory properties that may delay the photoaging process. In the current study, cultured human skin fibroblasts were incubated with 50 μg/ml baicalin 24 hours prior to 10 J/cm(2) UVA irradiation. In order to examine the efficacy of baicalin treatment in delaying UVA-induced photoaging, we investigated aging-related markers, cell cycle changes, anti-oxidant activity, telomere length, and DNA damage markers. UVA radiation caused an increased proportion of β-Gal positive cells and reduced telomere length in human skin fibroblasts. In addition, UVA radiation inhibited TGF-β1 secretion, induced G1 phase arrest, reduced SOD and GSH-Px levels, increased MDA levels, enhanced the expression of MMP-1, TIMP-1, p66, p53, and p16 mRNA, reduced c-myc mRNA expression, elevated p53 and p16 protein expression, and reduced c-myc protein expression. Baicalin treatment effectively protected human fibroblasts from these UVA radiation-induced aging responses, suggesting that the underlying mechanism involves the inhibition of oxidative damage and regulation of the expression of senescence-related genes, including those encoding for p53, p66(Shc) and p16.

Dietary fermented soybean suppresses UVB-induced skin inflammation in hairless mice via regulation of the MAPK signaling pathway

Soybean may be a promising ingredient for regulating UVB-induced inflammatory damage to the skin. We investigated the anti-inflammatory effects of diets supplemented with fermented soybean on UVB-induced skin photodamage and the effectiveness of soybean (S) and fermented soybean (FS) dietary supplementation. To investigate the effects of two major isoflavones-daidzein and genistein-from FS, we used cocultures with keratinocytes and fibroblasts. Genistein treatment strongly inhibited the production of IL-6 and MAPK signaling. Forty hairless male mice divided into four groups were fed with a control diet (group N: normal, group C; +UVB) or diets with 2.5% S+UVB or 2.5% FS+UVB (group S, group FS) for 8 weeks. Macrophage infiltration to the dermis was reduced more in groups S and FS than in group C. The expression levels of iNOS and COX-2 were significantly decreased in group FS (by 7.7% ± 0.4% and 21.2% ± 0.3%, respectively [p < 0.05]).

Environmental factors in the development and progression of late-onset Alzheimer's disease

Late-onset Alzheimer's disease (LOAD) is an age-related neurodegenerative disorder characterized by gradual loss of synapses and neurons, but its pathogenesis remains to be clarified. Neurons live in an environment constituted by neurons themselves and glial cells. In this review, we propose that the neuronal degeneration in the AD brain is partially caused by diverse environmental factors. We first discuss various environmental stresses and the corresponding responses at different levels. Then we propose some mechanisms underlying the specific pathological changes, in particular, hypothalamic-pituitary adrenal axis dysfunction at the systemic level; cerebrovascular dysfunction, metal toxicity, glial activation, and Aβ toxicity at the intercellular level; and kinase-phosphatase imbalance and epigenetic modification at the intracellular level. Finally, we discuss the possibility of developing new strategies for the prevention and treatment of LOAD from the perspective of environmental stress. We conclude that environmental factors play a significant role in the development of LOAD through multiple pathological mechanisms.

Might outdoor heat stress be considered a proxy for the unperceivable effect of the ultraviolet-induced risk of erythema in Florence?

Erythema is the most familiar short-term symptom of human skin associated with overexposure to unperceivable ultraviolet radiation (UV). However, people are able to perceive the warm infrared component of the solar radiation by means of thermal (dis)comfort. This study investigated the potentiality of perceived outdoor heat stress as a valuable proxy for the unperceivable effect of UV-induced risk of erythema in a Mediterranean city. Meteorological data and UVB (280-320nm) measurements were obtained for the 2004-2012 period by a weather station located in the municipality of Florence. Continuous measurements of erythemally effective UV (UVEry) were performed by means of a broadband temperature-corrected radiometer with the spectral response close to the erythemal action spectrum. Hourly UVEry doses were expressed as Standard Erythemal Doses (SEDs). The newly developed Universal Thermal Climate Index (UTCI), that represents the state-of-the-art of outdoor thermal (dis)comfort evaluation, was also assessed. Descriptive analyses of the hourly distribution per month of the frequencies of days with heat stress and UVEry exceeding 2.0, 3.0, 4.5 and 6.0 SEDs were carried out based on the general skin-type characteristics. The association between UVEry and UTCI was analyzed by a two-way contingency table approach. The probability of UVEry exceeding specific SED thresholds when heat stress occurs was often significantly higher than the same probability when no heat stress is perceived. Furthermore, increased magnitudes of the ratios, ranging from the very sensitive to the minimally sensitive skin types, were also found. However, during several months, too many days occur without any signs of heat discomfort, even when people may be exposed to relevant doses of harmful UVEry for the skin of various phototypes. These findings underlie the need for public health authorities to provide differentiated advice per month in relation to potential UV skin damage in the city of Florence.

Problematic lesions in the elderly

As the population continues to age, clinicians and dermatologists are increasingly faced with geriatric patients presenting with a range of dermatologic manifestations, including benign and malignant skin tumors. Knowledge of epidemiologic and morphologic features, including dermoscopy of common and benign melanocytic and nonmelanocytic skin tumors, provides the basis for a better understanding and management of problematic skin tumors in this age group. This article provides an overview of common and problematic skin lesions in elderly patients and addresses epidemiologic, clinical, and dermoscopic clues that aid the differential diagnosis and management of challenging skin lesions.