Skin as a protective shield
Human skin acts as the protective shield for the body against toxic environmental elements and pathological influence. It is exposed to a variety of environmental stress factors that may result in specific skin conditions. These negative influences trigger a multitude of biological processes in the skin, leading to sensitive skin, inflammation and irritation, but also initiating and accelerating aging processes. Over time, this can translate to uneven pigmentation.
The more delicate skin is, the more pronounced these biological processes are. This is especially the case with babies and people with sensitive skin. In order to provide skin with the ability to deal with these influences effectively, it is essential to use an active ingredient which has a significant influence on all biological processes involved in these phenomena.
Sensitive skin – physiological or psychological?
Sensitive skin is described as hyperirritable skin with a low tolerance threshold, mainly showing subjective complaints. People “feel” that their skin is easily irritated, especially when exposed to factors like cosmetics or mechanical stress. The subjective factor of sensitive skin makes this phenomenon very difficult to describe objectively and scientifically. In order to try to objectify sensitivity of skin, during the last few decades a consensus has been found about the signs and complaints typically associated with sensitive skin. The most important factor in sensitive skin is neurogenic inflammation, meaning the onset of burning, prickling, stinging and itching sensations. Often, but not always, neurogenic inflammation is accompanied by erythema. Effectively treating sensitive skin should therefore focus on neurogenic inflammation and erythema.
Neurogenic Inflammation and Erythema
Biological mechanisms leading to neurogenic inflammation and accompanying erythema in sensitive skin are considered to comprise an enormously complex interplay of skin cells, neuropeptides, inflammatory mediators, hormones, proteases, immune cells, etc. To exacerbate the complexity of sensitive skin, it has been recognized that there are many additional factors that come into play. These include: mental and physical state of a person, cultural factors (e.g., skin care routines), age, environmental factors (e.g., temperature, humidity, pollution), diet (e.g., spicy food, alcohol, coffee), seasonal variations and the use of pharmaceuticals. All these factors can negatively influence skin, making it more sensitive.
Often provoked by sunlight in normal skin, erythema is a much more frequent occurrence in sensitive skin. Mechanical stress is a very well-known cause of erythema in sensitive skin. Mechanical stress is something to which skin is virtually constantly exposed. Friction from clothes, shoes and diapers is considered to be one of the many sources of mechanical stress for skin. Fabrics are an important factor, as are working with the hands, waxing and, most well-known of all, shaving: 41% of all people report sensitive skin symptoms after shaving.
Inflammation in skin as a consequence of negative external impacts
Negative external influences lead to an immune response by the skin which can result in inflammation. Well-known manifestations of skin inflammation are redness, itching, pain and edema. An underlying but very important phenomenon in inflamed skin is the loss of epidermal homeostasis, in other words, the integrity of the epidermis. As the epidermis, in particular the stratum corneum, is our body’s main barrier against the outside world, it is vital to maintain a normally functioning, non-inflamed skin.
Cytokines play a central role in skin inflammation. They are low-molecular weight polypeptides (<80 kDa) of which only very low concentrations are needed to trigger inflammatory reactions in the skin. Cytokines bind to specific cell receptors to transmit their messages to target cells. These target cells then react to these triggers, largely by producing more inflammatory cytokines.
An even compexion is a sign of beauty in most parts of the world. Damage caused by UV light can lead to hyperpigmentation. Hyperpigmentation, such as age spots or freckles, results from surplus production of melanin. When skin is exposed to UV rays for a longer period of time, it reacts with increased cell proliferation; the epidermis gets thicker, and production of melanin, the metabolic product of melanocytes, is increased. Furthermore, the decomposition of melanosomes in hyperpigmented areas is disturbed or completely interrupted. This explains why age spots do not disappear of their own accord.
Especially people with a higher skin phototype often show a phenomenon called postinflammatory hyperpigmentation. This can play a prominent role in the appearance of dark circles. Dark circles under the eyes are a common phenomenon. Men and women are equally affected and, although aging plays a causative role, dark circles are seen in people of all ages. The pathophysiology of dark circles is extremely multifactorial, with different physiological processes being intertwined with each other. In reducing the appearance of dark circles it is therefore essential to find the common causes for the different processes which lead to the formation of dark circles.