596 JOURNAL OF COSMETIC SCIENCE CONCLUSION Chronic itch is the most frequently observed symptom of inflammatory skin disorders, (e.g., AD, allergic contact dermatitis, and psoriasis) leading to reduced quality of life due to sleep deprivation and mental distress. The skin itch-sensory pathway constitutes a complex interplay of inflammation, neuronal sensation, and epidermal barrier function. Various herbal formulations are used as the main ingredients in functional cosmetics to soothe itchy skin. This study evaluated the effects of three different herbal extracts (A houstonianum, B falcatum, and S chinensis) on the modulation of itch-inducing factors, including the epidermal barrier component FLG, IL31, TSLP, and β-endorphin, in HaCaT cells. FLG is a structural protein found predominantly in the keratin fibers of keratinocytes, which plays a critical role in maintaining epidermal hydration and skin barrier function. The reduction of FLG expression is associated with skin barrier damage and high susceptibility to itching. Keratinocyte-derived IL31, TSLP, and β-endorphin transmit itch-specific sensitization by binding directly to sensory neurons. Our results demonstrated that the combination of A houstonianum, B falcatum, and S chinensis restored IL4 + IL13–induced reduction in FLG expression and suppressed the expression of IL31, TSLP, and β-endorphin induced by IL4 in keratinocytes. The combination of the three extracts showed no cytotoxicity and higher efficacy than when each was used individually. In addition, since no adverse skin reactions were observed during the clinical investigation, it was considered an effective and safe cream that can help improve itching by restoring the skin barrier function. These findings suggest that a mixture of A houstonianum, B falcatum, and S chinensis can be a beneficial ingredient in cosmetic applications for inflammatory itch. Further comprehensive studies are needed to better understand the molecular mechanism underlying the anti-itch efficacy of these extracts against various skin inflammatory disorders. ACKNOWLEDGMENTS This work was supported by the Seoul R&BD Program (TB201060), Republic of Korea, and by the KU Research Professor Program of Konkuk University. REFERENCES (1) A. Ikoma, M. Steinhoff, S. Ständer, G. Yosipovitch, and M. Schmelz, The neurobiology of itch, Nat. Rev. Neurosci., 7(7), 535–547 (2006). (2) G. Yosipovitch, Dry skin and impairment of barrier function associated with itch — new insights, Int. J. Cosmet. Sci., 26(1), 1–7 (2004). (3) G. Yosipovitch, J. D. Rosen, and T. Hashimoto, Itch: from mechanism to (novel) therapeutic approaches, J. Allergy Clin. Immunol., 142(5), 1375–1390 (2018). (4) G. Yosipovitch and J. D. Bernhard, Clinical practice. Chronic pruritus, N. Engl. J. Med., 368(17), 1625– 1634 (2013). (5) C. Zeidler, M. P. Pereira, F. Huet, L. Misery, K. Steinbrink, and S. Ständer, Pruritus in autoimmune and inflammatory dermatoses, Front. Immunol., 10, 1303 (2019). (6) F. Dalgard, A. Svensson, J. Ø. Holm, and J. Sundby, Self-reported skin morbidity among adults: associations with quality of life and general health in a Norwegian survey, J. Investig. Dermatol. Symp. Proc., 9(2), 120–125 (2004). (7) J. D. Lindh and M. Bradley, Clinical effectiveness of moisturizers in atopic dermatitis and related disorders: a systematic review, Am. J. Clin. Dermatol., 16(5), 341–359 (2015). (8) T. Hoppe, M. C. Winge, M. Bradley, M. Nordenskjöld, A. Vahlquist, H. Törmä, and B. Berne, Moisturizing treatment of patients with atopic dermatitis and ichthyosis vulgaris improves dry skin,

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