Itching in a trichophytin contact dermatitis mouse model and the antipruritic effect of antifungal agents.

BACKGROUND: Tinea is an infectious disease by dermatophytes, of which Trichophyton species accounts for the overwhelming majority of case. Tinea often causes itching with inflammation. In terms of pruritus by fungal infection, however, tinea has not been investigated sufficiently to date. AIM: To evaluate itch caused by Trichophyton infection and the effect of antifungal agents on the infection, by measuring scratch behaviour and profiles of inflammatory cytokines and chemokines. METHODS: We used a previously established mouse model of contact hypersensitivity induced by trichophytin, a crude extract from Trichophyton mentagrophytes. Scratching behaviour was recorded using a counting device that measured an electric current induced in a coil by movement of magnets that had been inserted into the hind paws of each animal. We investigated expression of various genes in lesional skin of mice and in normal human epidermal keratinocytes. We also investigated the antipruritic effects of the corticosteroid dexamethasone (DEX) and three antifungal agents: ketoconazole (KCZ), terbinafine (TBF) and liranaftate (LNF). RESULTS: Biphasic peaks of scratching were observed at 1 h and at 6-7 h during an observation period of 14 h after trichophytin induction. For lesional skin, RNA was extracted 24 h after trichophytin challenge, and increased expression was seen in the genes for interleukin (IL)-17A, interferon-γ, tumour necrosis factor (TNF)-α, macrophage inflammatory protein (MIP)-2 and Dectin-1, whereas there was no obvious change in the genes for IL-31 and prostaglandin (PG)E2. Furthermore, KCZ inhibited histidine decarboxylase (HDC) expression in vitro and in vivo, and inhibited scratching in the very early phase. LNF inhibited expression of thymic stromal lymphopoietin (TSLP) and IL-8 in vitro, and TSLP, TNF-α, IL-1α and MIP2 in vivo, and also scratching in the early phase. TBF did not induce any significant alterations in either gene expression or scratching. DEX suppressed expression of all the chemical mediators except HDC in vitro and in vivo, and inhibited scratching. CONCLUSION: Antifungals can inhibit itching induced by fungal infection through different mechanisms.

Glycyrrhetinic acid inhibits contact hypersensitivity induced by trichophytin via dectin-1.

Trichophyton infection is highly prevalent and tends to be recurrent. Therefore, it is important to develop new therapeutic agents. Previously, we established a mouse model of Trichophyton-induced contact hypersensitivity (CHS) and demonstrated that dectin-1 was involved in inflammation induced by trichophytin, the Trichophyton antigen. Here, we used that model to investigate glycyrrhetinic acid (GA) from plants of the genus Glycyrrhiza as a potential anti-inflammatory agent against superficial mycoses. GA suppressed swelling and the expression of inflammatory cytokines, including macrophage inflammatory protein (MIP)-2, interleukin (IL)-6, tumor necrosis factor (TNF)-α and interferon (IFN)-γ mRNA. Anti-MIP-2 antibody suppressed trichophytin-induced inflammation, and antidectin-1 antibody suppressed zymosan-induced MIP-2 production in keratinocyte cells. These results suggest that MIP-2 is produced by dectin-1 activation and is involved in inflammation associated with CHS to trichophytin. GA also suppressed zymosan-induced MIP-2 and interleukin (IL)-8, production in mouse and human macrophages and keratinocytes. Furthermore, GA suppressed the phosphorylation of spleen tyrosine kinase (Syk) and inhibitor of nuclear factor-kappa B (IκBα) and the degradation of IκBα in zymosan-simulated RAW264.7 cells. The results of this study suggest that GA suppresses inflammation induced by trichophytin, partly by the downregulation of Syk phosphorylation.

[Allergy in Trichophyton infection in the cattle]. / Wystepowanie alergii przy trychofitozie bydla.

The examinations have been performed with glycoproteidic fractions of Trichophyton verrucosum (Tv-GP) and T. mentagrophytes (Tm-GP) purified by a method of gel chromatography. Trichophytins were intradermally injected at a dose of 2.0 ml (1.0 mg of protein) and the results were estimated after 24 and 72 h on the basis of differences in skin fold thickness (RGFS). In animals infected with lice or scabies in a farm free of trichophytosis the median value of RGFS was below 1.0 mm and maximal value was 2.0 mm. In a farm where trichophytosis caused by T. verrucosum was diagnosed positive reactions (RGFS above 4.0 mm) against the two trichophytins appeared in 90% of sick animals, 95% of convalescents and in 20% of animals without skin lesions but kept together with sick animals. In a part of diseased animals and exposed to infection apart from local reactions also appeared so called focal reactions characterized by appearance of fungal lesions followed by opening and crushing the crusts. There is a lack of relationship between intensity of allergic skin reaction and rate of fungal lesions. The animals infected with T. verrucosum cross-reacted with trichophytins Tv-GP and Tm-GP, allergic state persisted in convalescent animals after idiopatic disappearance of clinical symptoms. The performed studies point to a possibility of the use of allergic skin tests with a standardized trichophytins to evaluate immunological state in cattle with trichophytosis.

Allergic delayed skin reactions from lipid fractions of trichophytin.

Crude trichophytin was fractionated to find out if its lipid fraction could cause inflammatory delayed allergic skin reactions in dermatophyte-sensitized guinea pigs. The following fractions were obtained: polysaccharide-peptide, total lipids, total lipids without free fatty acids and free fatty acids. The crude trichophytin and polysaccharide-peptide fraction gave rise to strong and equal allergic delayed skin reactions after 24 h. The total lipids gave statistically significant weaker, but clearly positive reactions, and of the same degree as the free fatty acid fraction. The total lipids without free fatty acids did not produce reactions in the sensitized animals, indicating that free fatty acids are responsible for the allergic skin reactions. In some cases the free fatty acids showed comparatively intense reactions. It can be concluded that free fatty acids are antigenic substances that are, sometimes, involved in the allergic delayed skin reactions in dermatophytosis.