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Background: Sensitive skin is a condition of cutaneous hypersensitivity to environmental factors. Lactic acid stinging test (LAST) is commonly used to assess sensitive skin and composed of four distinct sensations (pain, burning sensation, itch, and crawly feeling). A link between sensitive skin and barrier dysfunction has been proposed in atopic dermatitis (AD) patients. However, clinical and laboratory factors that are associated with sensitive skin remain unelucidated., Objective: To investigate relationship between sensitive skin and AD-associated markers., Methods: Forty-two Japanese AD patients and 10 healthy subjects (HS) were enrolled. AD patients were divided into extrinsic (EAD; high IgE levels) and intrinsic (IAD; normal IgE levels) types. We conducted 1% LAST by assessing the four distinct sensations and calculated the frequencies of sensitive skin in EAD, IAD, and HS. We also performed clinical AD-related tests, including transepidermal water loss (TEWL), visual analogue scale (VAS) of pruritus, and quality of life, and measured laboratory markers, including blood levels of IgE, CCL17/TARC, lactate dehydrogenase (LDH) and eosinophil counts, and concentration levels of serum Th1/Th2 cytokines. Filaggrin (FLG) mutations were examined in 21 patients. These values were subjected to correlation analyses with each of the four sensation elements., Results: According to the standard criteria for LAST positivity, the frequencies of LAST-positive subjects were 54.8% and 10.0% in AD and HS, respectively (P=0.014). EAD patients showed a significantly (P=0.026) higher frequency of positive LAST (65.6%) than did IAD patients (20.0%). Among the four LAST sensation elements, the crawly feeling and pain scores positively correlated with VAS of pruritus, total serum IgE, mite-specific IgE, CCL17/TARC, and/or LDH. There was no association of the LAST scores with serum Th1/Th2 cytokine levels. Notably, neither TEWL nor FLG mutations correlated with LAST positivity or any sensation scores., Conclusions: The frequency of sensitive skin is higher in EAD than in IAD. Sensitive skin is associated with AD severity, but not necessarily with barrier condition., (Copyright © 2017 Japanese Society for Investigative Dermatology. Published by Elsevier B.V. All rights reserved.)

Background: Dry skin causes pruritus and discomfort in patients with xerosis and atopic dermatitis. General treatment for skin dryness involves the topical application of an emollient. However, more effective, simpler therapies are desired. Collagen tripeptide (CTP) is a highly purified, non-antigenic, low-allergenic collagen fraction that is known to have various biological effects., Objective: To clarify the therapeutic effects of CTP for dry skin using acetone-induced dry skin model mice., Methods: ICR mice were treated with acetone followed by oral administration of CTP (80 or 500mg/kg/day) for 3 days. Hyaluronic acid production induced by CTP was assessed using human dermal fibroblasts in vitro and in an acetone-induced dry skin model mice in vivo. Transepidermal water loss (TEWL) and scratching behavior were evaluated. Furthermore, the effects of CTP on intraepidermal nerve fibers and expression of semaphorin 3A (Sema3A) and nerve growth factor (NGF) were examined by immunohistochemistry and quantitative RT-PCR., Results: CTP enhanced hyaluronic acid production in human dermal fibroblasts in vitro and in murine skin in vivo. Oral administration of CTP in acetone-induced dry skin model mice significantly decreased TEWL and suppressed scratching behavior. Intraepidermal nerve growth was dramatically inhibited in CTP-treated mice. Quantitative PCR analysis and immunohistochemical study revealed that CTP abolished the increased NGF and decreased Sema3A levels induced by acetone treatment., Conclusion: Oral administration of CTP improves dry skin and normalizes axon-guidance factors in the epidermis in addition to reducing pruritus. CTP may be used in a new therapeutic strategy against dry skin and pruritus., (Copyright © 2012 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.)