After acute or chronic damage to the epidermal barrier, the spontaneous repair mechanism of the skin will accelerate the production of keratinocytes, shorten the replacement time of epidermal cells, and mediate the production and release of cytokines, resulting in hyperkeratosis and mild inflammation of the skin. This is also typical of dry skin symptoms.
Local inflammation can also exacerbate skin dryness, in fact, the breakdown of the epidermal barrier promotes the synthesis and release of a series of pro-inflammatory cytokines, such as IL-1he TNF, so that phagocytic immune cells, especially neutrophils, are destroyed. After being attracted to the dry site, after reaching the destination, neutrophils secrete leukocyte elastase, cathepsin G, protease 3, and collagenase into the surrounding tissues, and form and enrich protease in keratinocytes. Potential consequences of excessive protease activity: 1. Cell damage; 2. Release of pro-inflammatory cytokines; 3. Premature degeneration of cell-to-cell contacts that promote cell mitosis. Proteolytic enzyme activity in dry skin, which may also affect sensory nerves in the epidermis, is associated with pruritus and pain. Topical application of tranexamic acid and α1-antitrypsin (a protease inhibitor) to xerosis is effective, suggesting that xeroderma is associated with proteolytic enzyme activity.
Dry epidermis means that the skin barrier is disturbed, lipids are lost, proteins are reduced, and local inflammatory factors are released. Skin dryness caused by barrier damage is different from dryness caused by reduced sebum secretion, and the effect of simple lipid supplementation often fails to meet expectations. Moisturizing cosmetics developed for barrier damage should not only supplement stratum corneum moisturizing factors, such as ceramides, natural moisturizing factors, etc., but also take into account the effects of antioxidant, anti-inflammatory, and anti-cell division, thereby reducing incomplete differentiation of keratinocytes. Barrier skin dryness is often accompanied by pruritus, and the addition of antipruritic actives should be considered.
Post time: Jun-10-2022
