Molecular mechanisms of action of topical antiaging compounds:

Clinical and biological impact of the exposome on the skin

The skin exposome is defined as the totality of environmental exposures over the life course that can induce or modify various skin conditions. Here, we review the impact on the skin of solar exposure, air pollution, hormones, nutrition and psychological factors. Photoageing, photocarcinogenesis and pigmentary changes are well-established consequences of chronic exposure of the skin to solar radiation. Exposure to traffic-related air pollution contributes to skin ageing. Particulate matter and nitrogen dioxide cause skin pigmentation/lentigines, while ozone causes wrinkles and has an impact on atopic eczema. Human skin is a major target of hormones, and they exhibit a wide range of biological activities on the skin. Hormones decline with advancing age influencing skin ageing. Nutrition has an impact on numerous biochemical processes, including oxidation, inflammation and glycation, which may result in clinical effects, including modification of the course of skin ageing and photoageing. Stress and lack of sleep are known to contribute to a pro-inflammatory state, which, in turn, affects the integrity of extracellular matrix proteins, in particular collagen. Hormone dysregulation, malnutrition and stress may contribute to inflammatory skin disorders, such as atopic dermatitis, psoriasis, acne and rosacea.

Aesthetic aspects of skin aging, prevention, and local treatment

Skin aging is a complex biologic process influenced by a combination of intrinsic and extrinsic factors. Aging skin shows wrinkles, uneven tone, loss of elasticity, and thinning. Skin health is considered one of the principal factors representing overall well-being and the perception of health in humans; therefore, anti-aging strategies to combat aging signs and dysfunction have been developed over the last decades. Understanding the mechanism behind skin aging is required for elucidation of the mechanism of action and, hence, the potential benefits of the claimed anti-aging products. In this review, preventive measurements, cosmetologic strategies, and photoprotection (systemic antioxidants, ultraviolet and filters), as well as the mechanisms of action and the effectiveness of topical pharmaceutical agents, such as antioxidants (vitamins, polyphenols, and flavonoids) and cell regulators (retinols, peptides, hormones, and botanicals), are presented.

A synopsis on aging-Theories, mechanisms and future prospects

Answering the question as to why we age is tantamount to answering the question of what is life itself. There are countless theories as to why and how we age, but, until recently, the very definition of aging - senescence - was still uncertain. Here, we summarize the main views of the different models of senescence, with a special emphasis on the biochemical processes that accompany aging. Though inherently complex, aging is characterized by numerous changes that take place at different levels of the biological hierarchy. We therefore explore some of the most relevant changes that take place during aging and, finally, we overview the current status of emergent aging therapies and what the future holds for this field of research. From this multi-dimensional approach, it becomes clear that an integrative approach that couples aging research with systems biology, capable of providing novel insights into how and why we age, is necessary.