Inami Yoshihiro, Andoh Tsugunobu, Sasaki Atsushi, Kuraishi Yasushi
Department of Applied Pharmacology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan.
Yakugaku Zasshi. 2012;132(11):1225-30. doi: 10.1248/yakushi.12-00232-3.
The primary function of surfactants is to remove dirt, exfoliated corneum cells, and microorganisms from the skin. However, the use of toiletries such as soaps and shampoos containing surfactants may cause adverse effects such as cutaneous irritation, dryness, and itching. Recently, skin pathologies, including dry skin, rough skin, and sensitive skin, have increased because of changes in living conditions and lifestyle. Although many people with skin pathologies complain of itching during and/or after skin washing using detergents, the mechanisms of detergent-induced itch are yet to be elucidated. Therefore, in this study, we investigated the mechanisms underlying surfactant-induced itching. We found that topical application of an anionic surfactant sodium laurate at an alkaline pH, but not N-lauroylsarcosine sodium salt at neutral pH, to mouse skin induced scratching, an itch-related response. Additionally, we found that the sodium laurate-induced scratching was inhibited by H(1) histamine receptor antagonist, but not mast cell deficiency. Sodium laurate application increased histamine content and the level of the active form (53 kDa) of L-histidine decarboxylase (HDC) in the mouse epidermis, but not the dermis. Furthermore, addition of sodium laurate to a human epidermal cell culture increased histamine release and HDC levels, without affecting cell viability. These results suggest that surfactants with alkaline properties are pruritogenic and that the pruritus is induced by the histamine released from epidermal keratinocytes. The increase in histamine release may be attributable to the activation of HDC in epidermal keratinocytes.
表面活性剂的主要功能是清除皮肤表面的污垢、角质层脱落细胞和微生物。然而，使用含有表面活性剂的肥皂和洗发水等洗漱用品可能会产生不良影响，如皮肤刺激、干燥和瘙痒。近年来，由于生活条件和生活方式的改变，包括干性皮肤、粗糙皮肤和敏感性皮肤在内的皮肤疾病有所增加。尽管许多患有皮肤疾病的人在使用洗涤剂清洗皮肤期间和/或之后会抱怨瘙痒，但洗涤剂诱发瘙痒的机制尚待阐明。因此，在本研究中，我们调查了表面活性剂诱发瘙痒的机制。我们发现，在碱性pH条件下将阴离子表面活性剂月桂酸钠局部应用于小鼠皮肤会诱发抓挠，这是一种与瘙痒相关的反应，而在中性pH条件下将N-月桂酰肌氨酸钠盐应用于小鼠皮肤则不会诱发抓挠。此外，我们发现月桂酸钠诱发的抓挠可被H(1)组胺受体拮抗剂抑制，但不受肥大细胞缺陷的影响。月桂酸钠的应用增加了小鼠表皮中组胺含量以及L-组氨酸脱羧酶（HDC）活性形式（53 kDa）的水平，但真皮中没有增加。此外，向人表皮细胞培养物中添加月桂酸钠会增加组胺释放和HDC水平，而不影响细胞活力。这些结果表明，具有碱性性质的表面活性剂具有致痒性，且瘙痒是由表皮角质形成细胞释放的组胺诱发的。组胺释放的增加可能归因于表皮角质形成细胞中HDC的激活。
