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Scratching of their skin by NC/Nga mice leads to development of dermatitis
Yuki Hashimoto1, Iwao Arai, Yutaka Nakanishi
1Pharmacology Laboratory, Medicinal Research Laboratories, Taisho Pharmaceutical Co., Ltd., 1-403, Yoshino-cho, Kita-ku, Saitama-city, Saitama 331-9530, Japan. yuki.hashimoto@po.rd.taisho.co.jp
Abstract:
Effects of scratching behavior on dermatitis, transepidermal water loss (TEWL) and serum IgE concentrations were examined in NC/Nga (NC) mice with toenails (WIT) and without toenails (WOT). The first study was a preventive treatment done to cut off hind toenails before dermatitis induction and the second study was a therapeutic treatment by cutting off hind toenails of NC mice with severe dermatitis. In the preventive study, scratching behavior significantly increased in both WIT and WOT after dermatitis induction. Skin severity score, TEWL, number of mast cells and serum IgE concentration statistically increased in WIT but not in WOT after dermatitis induction. Histological changes coincided with the skin severity score in WIT, while no changes were observed in WOT. In the therapeutic study, skin severity score in WOT but not in WIT statistically decreased after cutting off the hind toenails. TEWL and numbers of mast cells in WOT were statistically lower compared with findings in WIT. Thus scratching up the skin with toenails seemed to be the most important factor leading to dermatitis in NC mice.
Insights
Scratching with toenails significantly worsens dermatitis in NC/Nga mice, increasing skin severity, water loss, and allergic markers. Removing toenails prevents and treats dermatitis, highlighting toenails as a key factor.
Area of Science:
- Dermatology
- Immunology
- Animal Models
Background:
- Dermatitis is a common skin condition.
- Scratching behavior exacerbates skin inflammation.
- NC/Nga mice are a model for atopic dermatitis.
Purpose of the Study:
- To investigate the role of toenails in scratching-induced dermatitis.
- To evaluate the impact of toenail removal on dermatitis severity, transepidermal water loss (TEWL), and serum IgE.
- To compare preventive and therapeutic effects of toenail removal.
Main Methods:
- NC/Nga mice were divided into groups with toenails (WIT) and without toenails (WOT).
- Studies included preventive (pre-dermatitis induction) and therapeutic (post-dermatitis induction) toenail removal.
- Dermatitis severity, TEWL, mast cell counts, and serum IgE were measured.
Main Results:
- Scratching behavior increased in both WIT and WOT groups after dermatitis induction.
- In the preventive study, WIT mice showed increased skin severity, TEWL, mast cells, and IgE compared to WOT mice.
- In the therapeutic study, WOT mice showed decreased skin severity, TEWL, and mast cells compared to WIT mice.
Conclusions:
- Toenails are a critical factor in exacerbating dermatitis in NC/Nga mice through scratching.
- Toenail removal is effective in preventing and treating scratching-induced dermatitis.
- Reducing scratching behavior by removing toenails mitigates dermatitis progression.
