Kao Corp. recently announced a significant breakthrough in understanding the causes of hypersensitivity in sensitive skin. The findings, presented at the 50th Convention of the Japanese Cosmetic Science Society, shed light on the role of epidermal tight junctions in skin discomfort and offer promising solutions for those with sensitive skin.
Key Findings: Tight Junctions and Claudin-3
Under the guidance of Professor Kenji Kabashima from Kyoto University, Kao’s Skin Care Research Laboratory discovered that sensitive skin contains a higher number of nerve fibers closer to the skin surface — i.e., reaching just below the stratum corneum at the granular layer of the epidermis — than healthy skin.
As Kao explained, the granular layer contains structures known as tight junctions that keep cells in close contact to prevent the entry of foreign substances and the evaporation of moisture. Tight junctions also typically hold nerve fibers deeper, to the inner side of the tight junctions.
However, per the company, it has been reported that in atopic dermatitis, weakening of the tight junctions allows nerve fibers to extend to just below the stratum corneum where they can cause discomfort such as itching. This suggested that tight function dysfunction could be involved in sensitivity.
The researchers therefore examined the expression of claudin-3, a structural protein in tight junctions, and found a reduction in its expression in sensitive skin that could be contributing to tight junction dysfunction. This dysfunction could allow nerve fibers to extend closer to the skin’s surface, triggering sensations like tingling and burning.
See the company's press announcement for full study details.
A Promising Amino Acid-derived Solution
In response, Kao’s team explored potential remedies and found that γ-amino-β-hydroxybutyric acid, an amino acid derivative, enhanced the function of tight junctions.
In an eight-week clinical trial involving 40 women with sensitive skin:
a prototype formulation containing this compound significantly reduced discomfort; and
participants reported decreased tingling and burning sensations, marking a breakthrough in sensitive skin care.
The research earned the Convention President’s Award at the Japanese Cosmetic Science Society’s annual event, highlighting its potential for advancing dermatological science.
