Anti-ageing
Facing an underrated skin problem
SyriCalm CLR( PC) from CLR Chemisches Laboratorium shows immense benefits in formulations intended for sensitive or stressed skin. Technical marketing director,
Harald van der Hoeven discusses how the active ingredient addresses hyperosmotic stress in skin care.
To maintain its barrier properties, skin is constantly in a process of renewal. In this process the keratinocytes, which make up the epidermis, go through a continuous process of differentiation. The result is a well-established stratum corneum( SC), in which corneocytes are embedded in a lipid-rich matrix making the SC the actual physical barrier between the body and the outside world. The turnover time of a healthy functioning epidermis is estimated to be between two and fi ve weeks, depending on factors such as age.
The SC is extremely vulnerable to external attacks. For instance, exposure to UV light
Figure 1: Water gradient in normal skin( green line) compared to that of dry skin( red line) or surfactants, as well as sudden changes in environmental humidity and temperature all have a negative impact on the SC’ s quality. This not only infl uences the physical barrier properties of the skin, but also negatively affects the layers below the SC.
Keratinocytes in the stratum granulosum( SG) can also be affected negatively by external stresses. These are regarded as the‘ real SC factory’ because this is the section of the epidermis where the keratinocytes produce the precursors of the natural moisturising factors and ceramides. This is also where the keratinocytes go through a keratinisation process where they metamorphose into corneocytes. These processes are all fundamentally important in building up a strong SC.
It is crucial to maintain the quality and activity of the keratinocytes in the SG. In this context, one specifi c property of these cells demands special attention – namely cellular volume. This is essential for cellular functioning. Negative external infl uences directly and indirectly induce hyperosmotic stress, and hence the loss of cellular volume in the epidermis.
Figure 2: The assessment of taurine effl ux and the effect of SyriCalm CLR( PC)
What is hyperosmotic stress?
This phenomenon can affect keratinocytes in the SG. While the SG has a steep water gradient, SC disruption leads to an increase in water loss and volume degradation of these cells( see Figure 1). At the border between the stratum spinosum and SG, the cells start to lose water. The intracellular water concentration reaches about 40 percent at the border between SG and SC, while at the surface of the skin the cells contain 15 to 30 percent water. This extreme loss of intracellular water in the SG is part of the regular differentiation process.
Hyperosmotically stressed skin shows a signifi cantly elevated loss of intracellular water depicted by the red line in Figure 1. External stresses lead to an elevated loss of cellular water in the SG. A disruption of its quality – an abundant phenomenon caused by external stress – leads to the drying out of the SC. This is where the corneocytes start absorbing water from the SG. Another cause of hyperosmotic stress is the penetration of electrolytes into the skin, causing keratinocytes to try and
16 | MAY 2017 | P C Review