92 SKIN CARE
to irritation, further weakening its natural defences. Calcium plays a pivotal role in supporting
the skin’s barrier function by regulating essential processes in epidermal biology. It modulates enzymatic activity, gene expression, and the differentiation of keratinocytes, the skin’s primary cells. These processes are crucial for maintaining a healthy and intact barrier. Calcium also supports the synthesis
of structural proteins such as filaggrin and involucrin, which contribute to the strength and hydration of the skin’s outer layer. Moreover, calcium regulates the production of lipids that form the lipid matrix, a key component of the skin’s protective barrier. A calcium gradient within the
epidermis is essential for coordinating these functions. As we age, this gradient diminishes, weakening the barrier and increasing TEWL. Replenishing calcium levels can help restore this gradient, enhance barrier integrity, and improve hydration, leaving the skin feeling smoother, more resilient, and better protected. 1,2
Gene expression in keratinocytes In vitro studies were conducted in primary epidermal keratinocytes, under low-calcium conditions to mimic the effects of skin aging. Under these conditions, the active ingredient demonstrated a significant modulatory effect on the expression of various genes responsible for producing proteins that form the skin’s three primary defensive barriers, as listed below.
1. Stratum corneum This layer is primarily formed by proteins such as loricrin, involucrin, transglutaminase 1, and cholesterol sulfotransferase. Loricrin and involucrin are critical for the formation of the skin’s protective outermost layer, the stratum corneum. Loricrin, a major protein in the corneocytes,
binds to lipids and other proteins to form a rigid structure that helps maintain skin integrity and water retention. Involucrin contributes to the formation of
the cornified envelope, providing a barrier to environmental damage. Transglutaminase 1 plays a key role in
the cross-linking of proteins in the stratum corneum, strengthening the skin’s physical structure. Cholesterol sulfotransferase is involved in the regulation of the lipid matrix, supporting the barrier’s ability to retain moisture and defend against external irritants.3
which relies on a natural moisturizing factor (NMF) composed of molecules such as amino acids, salts, and sugars. These compounds have water-retaining properties that help bind moisture to the skin, preventing dehydration and preserving the integrity of the skin barrier. In addition to NMF, the skin’s
moisture retention is further supported by a water transport system within the
epidermis, primarily facilitated by aquaporins. These specialized protein channels are crucial for transporting water between skin cells, ensuring consistent hydration. Aquaporins are especially important in the stratum corneum, the outermost layer of the skin, where water retention is vital.7,8 The active ingredient tested has
Figure 2: On the left, Lithothamnion calcareum algae; on the right, rice amylopectin from Oryza sativa
2. Tight junction barrier The tight junctions in the epidermis are primarily formed by proteins like claudin-1, claudin-4, and occludin. These proteins form tight seals between adjacent cells, creating a selective barrier that controls the passage of ions, water, and solutes across the skin. Claudins are particularly important for
maintaining the skin’s permeability, while occludin regulates the overall tightness of the junctions, further enhancing the skin’s ability to separate the internal and external environments, protecting the skin from harmful substances.4,5
3. Antimicrobial barrier The skin’s antimicrobial defences are bolstered by ß-defensin-3, a peptide involved in the innate immune system. ß-defensin-3 acts as a first line of defence against pathogens by disrupting the membrane integrity of bacteria, helping to prevent infection. Additionally, it plays a role in the
inflammatory response and wound healing processes, aiding the skin’s recovery from injury and infection.6
The skin has a sophisticated network of mechanisms and structures that work together to maintain optimal moisture levels. A key component in this process is the epidermis,
demonstrated efficacy at multiple levels within the epidermis, delivering both immediate and long-lasting moisturizing effects. It influences key biological pathways, enhancing the skin’s capacity to retain moisture. For instance, the ingredient modulates the
expression of genes involved in hydration and skin cohesion, including filaggrin, caspase-14, and aquaporin-9. Filaggrin is essential for the formation of the skin barrier and the production of NMF. Caspase-14 plays a critical role in skin cell differentiation, contributing to the integrity of the epidermal layer, while aquaporin-9 directly facilitates water transport, boosting hydration. This upcycling active ingredient also
enhances cellular cohesion by influencing proteins like desmocollin-1 (DSC1) and desmoglein-1 (DSG1), which help skin cells adhere to each other, reinforcing the skin barrier. This action promotes skin resilience, preventing moisture loss and protecting against environmental stressors. By modulating hydration-related genes and supporting cellular cohesion, this ingredient offers a promising solution to improve the structural and functional integrity of the skin’s protective barrier while.
Effects on the barrier function An ex vivo test using a topical application with a 3% of the active ingredient on skin models was conducted during 6 days. The main purpose was to evaluate protein production in the tight junction area, ceramide production, and skin barrier recovery after delipidation. Using an immunohistochemical technique
coupled with advanced image analysis, the surface areas of the granular layer (specifically occluding proteins) and the stratum corneum
PERSONAL CARE March 2025
www.personalcaremagazine.com
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