Skin Aging and Modern Age Anti-Aging Strategies

Review Article

Austin J Womens Health. 2019; 6(1): 1034.

Skin Aging and Modern Age Anti-Aging Strategies

Mohiuddin AK*

Department of Pharmacy, World University of Bangladesh, Bangladesh

*Corresponding author: Abdul Kader Mohiuddin, Department of Pharmacy, World University of Bangladesh, 151/8, Green Road, Dhanmondi, Dhaka -1205, Bangladesh

Received: June 03, 2019; Accepted: July 05, 2019; Published: July 12, 2019

Abstract

As the most voluminous organ of the body that is exposed to the outer environment, the skin suffers from both intrinsic and extrinsic aging factors. Skin aging is characterized by features such as wrinkling, loss of elasticity, laxity, and rough-textured appearance. This aging process is accompanied with phenotypic changes in cutaneous cells as well as structural and functional changes in extracellular matrix components such as collagens and elastin. With intrinsic aging, structural changes occur in the skin as a natural consequence of the biological changes over time and produce a certain number of histological, physiological, and biochemical modifications. Intrinsic aging is determined genetically (influence of gender and ethnic group), variable in function of skin site, and also influenced by hormonal changes. Visually it is characterized by fine wrinkles. By comparison, “photoaging” is the term used to describe the changes occurring in the skin, resulting from repetitive exposure to sunlight. The histological, physiological, and biochemical changes in the different layers of the skin are much more drastic. From a mechanical point of view, human skin appears as a layered composite containing the stiff thin cover layer presented by the stratum corneum, below which are the more compliant layers of viable epidermis and dermis and further below the much more compliant adjacent layer of subcutaneous white adipose tissue. Upon exposure to a strain, such a multilayer system demonstrates structural instabilities in its stiffer layers, which in its simplest form is the wrinkling. These instabilities appear hierarchically when the mechanical strain in the skin exceeds some critical values. Their appearance is mainly dependent on the mismatch in mechanical properties between adjacent skin layers or between the skin and subcutaneous white adipose tissue, on the adhesive strength and thickness ratios between the layers, on their bending and tensile stiffness as well as on the value of the stress existing in single layers. Gradual reduction of elastic fibers in aging significantly reduces the skin’s ability to bend, prompting an up to 4-fold reduction of its stability against wrinkling, thereby explaining the role of these fibers in skin aging. Anti-aging medicine is practiced by physicians, scientists, and researchers dedicated to the belief that the process of physical aging in humans can be slowed, stopped, or even reversed through existing medical and scientific interventions. This specialty of medicine is based on the very early detection and prevention of age-related diseases. Physicians practicing anti-aging medicine seek to enhance the quality of life as well as its length, limiting the period of illness and disability toward the end of one’s life. Anti-aging medicine encompasses lifestyle changes (diet and exercise); hormone replacement therapies, as needed, determined by a physician through blood testing (DHEA, melatonin, thyroid, human growth hormone, estrogen, testosterone); antioxidants and vitamin supplements; and testing protocols that can measure not only hormone levels and blood chemistry but every metabolic factor right down to the cellular level.

Keywords: Skin care; Anti-aging; Photoaging; Wrinkles; Antioxidants; Keratinocytes; Retinoids

Background

Skin is the barrier that segregates the body from the outer environment. Besides protecting the body from water loss and microorganism infection, it has an important cosmetic role. Young and beautiful appearance may have a positive influence on people’s social behavior and reproductive status. Cleopatra, the Egyptian queen is said to have indulged in daily donkey-milk baths, a practice which apparently required over 700 donkeys to accomplish. The alpha hydroxy acids in the milk are believed to be anti-aging and skin-softening agents. Tang-dynasty ruler and sole female emperor of China, Wu Zetian, maintained a lifelong interest in skincare formulas. She mixed her “fairy powder” (made of carefully harvested and prepared Chinese motherwort) with cold water in order to wash her face each morning. The empress was a famed beauty well into her old age. The most hair-raising entrant in this list, 16th century Hungarian countess Elizabeth Báthory is infamous for being one of the world’s first documented female serial killers. Most of her life is shrouded in mystery and legend—the most famous story being that she would regularly bathe in the blood of her female victims. Mary, Queen of Scots, the ill-fated and attractive adversary of Elizabeth I, spent her sixteenth-century happier days on her estate in Edinburgh, Scotland, where her beauty regimen was said to include white-wine baths. In addition to wine’s antiseptic alcohol content, it was also was thought to improve complexion in general. Crème Celeste, a favorite product of empress Elisabeth (Sisi) of Austria, was a concoction of spermaceti (a wax found in the head of sperm whales), sweet almond oil, and rosewater. She would apply this daily and at night, she was known to coat her face in raw veal and crushed strawberries, kept in place with a custom-made leather mask. The skin folds are indicative of an aged personality, but not youthfulness. So, everyone wants to look younger for whole of the life, which leads to the discovery of many surgical and non-surgical treatment modalities to improve the youthfulness. Since the introduction of Botox in 2002 after FDA approval more aesthetic procedures using Botox were performed by aestheticisms involving plastic surgeons and dermatologists. However, many scientists are now starting to view physical aging as a disease process. The cellular and molecular mechanisms involved in aging reveal an intricate series of signals, markers, and pathways, all of which are programmed to monitor and control the lifespan of a cell as it ages. By studying these molecular events and pathways, the field of anti-aging will be furthered by the use of more and more cosmetics.

Introduction

Skin aging is a complex biological process influenced by a combination of endogenous or intrinsic and exogenous or extrinsic factors. Because of the fact that skin health and beauty is considered one of the principal factors representing overall “well-being” and the perception of “health” in humans, several anti-aging strategies have been developed during the last years. In contrast to thin and atrophic, finely wrinkled and dry intrinsically aged skin, premature photo aged skin typically shows a thickened epidermis, mottled discoloration, deep wrinkles, laxity, dullness and roughness. Gradual loss of skin elasticity leads to the phenomenon of sagging. Slowing of the epidermal turnover rate and cell cycle lengthening coincides with a slower wound healing and less effective desquamation in older adults. This fact is important when esthetic procedures are scheduled. On the other side, many of these features are targets to product application or procedures to accelerate the cell cycle, in the belief that a faster turnover rate will yield improvement in skin appearance and will speed wound healing. A marked loss of fibril in-positive structures as well as a reduced content of collagen type VII (Col-7), may contribute to wrinkles by weakening the bond between dermis and epidermis of extrinsically age skin. Sun-exposed aged skin is characterized by the solar elastosis. The sparse distribution and decrease in collagen content in photo aged skin can be due to increased collagen degradation by various matrix metalloproteinase’s, serine, and other proteases irrespective of the same collagen production. The overall collagen content per unit area of the skin surface is known to decline approximately 1%/year. Glycosaminoglycans (GAGs) are among the primary dermal skin matrix constituents assisting in binding water. In photo-aged skin, GAGs may be associated with abnormal elastotic material and thus be unable to function effectively. The total Hyaluronic Acid (HA) level in the dermis of skin that age intrinsically remains stable; however, epidermal HA diminishes markedly. Decreased estrogen levels may play a role in skin aging in women and compounds stimulating estrogen receptors could potentially counteract some of the visible signs of aging. As people live longer, women spend a larger portion of their lives in a postmenopausal state, with a deficiency of estrogen as compared to their younger selves. Changes in diet and increasing exercise, together with a regimen of antioxidants, nutritional supplements, and growth factors, can alter how the genes express themselves. Both factors can greatly enhance the healing capability of the skin and can improve the results of cosmetic surgeries.

The aging processes

Aging can be viewed as the accumulation of changes in cells and tissues resulting from a greater disorderliness of regulatory mechanisms that result in reduced robustness of the organism to encountered stress and disease. The notion of greater disorderliness in aging is illustrated by the erosion of the orderly neuro endocrine feedback regulation of the secretion of Luteinizing Hormone (LH), Follicle Stimulating Hormone (FSH), Adreno Cortico Tropic Hormone (ACTH) and Growth Hormone (GH). These changes are manifested as menopause, andropause, adrenopause, and somatopause. Skin aging is part of the slow decline in appearance and function that appears to be attributed in large part to the drastic decline of hormones in the body after adulthood. At the cellular level, several processes are involved in the physiology of aging and the development of some age-related diseases. The process of apoptosis signifies the process of nontraumatic and non inflammatory cell death. Dysregulation of apoptosis has been implicated in the increased incidence of cutaneous malignancies that are more prevalent in older individuals, such as basal cell carcinoma, squamous cell carcinoma, and malignant melanoma. Cell senescence limits cell divisions in normal somatic cells and may play a central role in agerelated diseases. Telomeres are thought to play a role in cellular aging and might contribute to the genetic background of human aging and longevity. It has been speculated that the limited proliferation potential of human cells is a result of the telomere shortening that occurs during DNA synthesis at each cell division. Photoaging may accelerate the shortening of telomeres and push cells into senescence sooner. That could be the reason why various growth factors may affect the speed and quality of wound healing. Biochemical insults also arise within aging cells, in part from the action of reactive oxygen species generated and scavenged incompletely throughout the cell cycle. Aging-associated changes also occur between and among cells via alterations in the intercellular matrix, the intercellular exchange of trophic factors, the release of inflammatory cytokine mediators, and the degree of infiltration by other associated cell types. In addition, the quantity and distribution of various growth factors may affect wound healing. Decline of DNA repair in combination with loss of melanin increases the risk of photo-carcinogenesis and can also cause the decline of enzymatically active melanocytes (10–20% each decade) that contributes to increased sensitivity to UV radiation. However, it is not known why free radical damage does not adversely affect all of the body’s cells (e.g., gonadal germ cells) [1].

Factors involved in skin aging

Skin aging is a complex biological process influenced by combination of endogenous or intrinsic (genetics, cellular metabolism, hormone and metabolic processes) and exogenous or extrinsic (chronic light exposure, pollution, ionizing radiation, chemicals and toxins) factors. These factors lead together to cumulative structural and physiological alterations and progressive changes in each skin layer as well as changes in skin appearance, especially, on the sunexposed skin areas [2]. Facial skin wrinkles can be considered as a marker for intrinsic aging (See wrinkle classification in Exhibit 1. The major perceived risk factors are unhealthy eating habits, stress, less exercise, dehydration, diseased state and sleeping habits. Though the main factor responsible for extrinsic aging is UVR [3]. Beyond sun damage factors such as smoking and atmospheric pollution have also been studied and considered in extrinsic aging. Studies have shown a clear correlation between these factors and the appearance of melanosis and wrinkles. Both of these factors contribute to aging through a common mechanism called oxidative stress that has a negative impact on cellular processes, such as DNA replication. In addition to the UV region of solar radiation that contributes to cellular injury, visible radiation has an oxidative effect similar to that of infrared radiation via heat generation. The effects of comorbidities, such as metabolic illnesses common in the elderly, nutritional deficiencies, and the use of drugs such as corticosteroids, and even cancer treatments, should be assessed by dermatologists attending to skin conditions associated with aging [4]. Good skin condition can be maintained to some extent by changes in modifiable lifestyle factors such as smoking and sunscreen use [5]. Human skin cells respond to instructions from highly specialized proteins or hormones referred to as growth factors. The growth differentiation factor GDF11, a TGF-β family member, has been associated with the maintenance of youth phenotypes in different human tissues and organs, and in the skin has been related to an inhibition of the inflammatory response. The production of elastin and collagen dermal connective fibers slows, and, with age, the regenerative rates of GAGs become delayed [6, 7].