A Mouse Model of Trichophyton Inflammation Based on Trichophytin-induced Contact Hypersensitivity.

The prevalence of Trichophyton-induced superficial skin mycosis is very high among human patients. Dermatophytes generally infect the epidermis, especially the stratum corneum, forming scales, hyperkeratosis, and vesicles. The important roles played by the immune system in Trichophyton infection are detection of fungal invasion and elimination of fungi.These immune mechanisms are presumed to involve not only innate immunity but also acquired immunity. Therefore, there is a substantial need for studies on treatment methods based on new basic knowledge, and the elucidation of immunological mechanisms of Trichophyton-induced inflammatory reactions is especially important.However, since Trichophyton cannot colonize on the mouse skin, we tried to develop a model for Trichophyton inflammation induced by trichophytin extracted from Trichophyton mentagrophytes using a method based on contact hypersensitivity.Trichophytin is a crude extract that mainly contains fungal cell wall constituents including ß-glucan and zymosan. In this model, TLR2, TLR4, and dectin-1 were highly expressed, and production of IL-17A and IL23 was observed. This indicates that we succeeded in inducing fungal-specific inflammation in the mice.In this review, we introduce a mouse Trichophyton inflammation model developed to investigate the immunological mechanisms of Trichophyton-induced inflammatory reactions. In addition, we report results of evaluation of anti-inflammatory and anti-itching effects of anti-fungal agents using the inflammation model.

Possible Role of Trichophytin Antigen in Inducing Impaired Immunological Clearance of Fungus in Onychomycosis.

The immunology of onychomycosis is poorly understood. Th1 and Th17 are the principal effector cells responsible for protective immunity against fungi, while it is assumed that Th2 responses are associated with deleterious effects. The study was conducted to appraise the role of interleukin-6 (IL-6), transforming growth factor ß (TGF-ß) and immunoglobulin E (IgE) in onychomycosis patients and to study skin reactivity to trichophytin antigen in them. Serum samples of 60 cases of chronic onychomycosis and 30 healthy controls were assayed for serum IgE, IL-6 and TGF-ß levels using specific immunoassay kits; 0.01 ml of trichophytin antigen, Candida antigen and phosphate-buffered saline using separate syringes were injected intradermal at three independent sites of the forearm in cases and controls. Serum IL-6 levels were significantly lower in cases as compared to controls, while serum TGF-ß levels in both cases and controls were comparable. Serum IgE levels in cases were significantly higher when compared with controls. Thirty-eight patients showed immediate hypersensitivity response to trichophytin antigen, while none showed delayed hypersensitivity reaction to trichophytin antigen. Constant fungal antigenic stimuli induce a state of anergy as indicated by low serum IL-6 levels and the absence of delayed hypersensitivity reaction to trichophytin antigen in cases, leading to chronicity of infection. High total IgE may indicate a high probability of prior fungal sensitization.

Reactivity to trichophytin antigen in patients with onychomycosis: effect of terbinafine.

BACKGROUND: Many patients with chronic dermatophytosis and onychomycosis have depressed cell-mediated immunity (CMI) to trichophytin. OBJECTIVE: The fungicidal properties of oral terbinafine provide a unique opportunity to explore whether elimination of antigen could restore CMI response in these patients. METHODS: A double-blind, placebo-controlled study evaluated the effect of terbinafine (250 mg/d for 12 weeks) on skin immunoreactivity to intradermal trichophytin antigen (TRIPA), mycologic status of the nail, and nail growth in patients with toenail onychomycosis. RESULTS: Skin reactivity, in an optimized, dose response challenge series to TRIPA was inversely related to disease chronicity. Mycologic/clinical response rates were 72%/84% for terbinafine and 0%/7% for placebo. Terbinafine increased the number of TRIPA reactors 2-fold and the mean TRIPA reaction area 4-fold; responses in placebo-treated patients were relatively unchanged. Of the 7 (of 25) patients receiving terbinafine who still had positive mycology 6 months after treatment, all were anergic to TRIPA at baseline and all but one remained so after treatment. CONCLUSION: Terbinafine treatment enhances and restores CMI to TRIPA in patients with Trichophyton rubrum onychomycosis and may thereby reduce susceptibility to reinfection. Terbinafine reversal of immunologic anergy may be an important model of microbial tolerance in chronic dermatophyte infections.

Dermatophytosis: association between ABO blood groups and reactivity to the trichophytin.

The authors investigated the relationship between dermatophytosis and ABO blood groups through blood typing, identification of isolated dermatophytes and specific cellular immune response of 40 individuals carriers of this mycosis. They verified that the fungus Trichophyton rubrum, isolated from 54.5% of the patients, was more frequent in individuals belonging to blood group A. The cellular immune response, evaluated through the trichophytin antigen, was positive in 25% of the studied patients; the presence of immediate reactions (30 minutes) was verified in 35%. The blood group distribution among patients with dermatophytosis and control groups was, respectively: 47.5% X 36% in group A, 40% X 50% in group O, 12. 5% X 11% in group B. Even though the authors have found a higher number of patients belonging to blood group A infected by T. rubrum, these results suggest that there is no statistical evidence that these individuals are more susceptible to dermatophytosis.

Association of hypersensitivity and carriage of dermatophytes in clinically normal sites in patients with Tinea cruris.

Forty nine patients with mycologically confirmed Tinea cruris were investigated for the association of hypersensitivity to trichophytin and the isolation of dermatophytes from clinically normal sites with chronicity and recurrence of infection. At the end of six months following specific therapy, 24 patients returned for follow up and they were similarly studied. Dermatophytes were isolated from clinically asymptomatic sites in 46% patients before treatment and in 21% of the patients on follow up. Immediate weal reaction and increased concentration of IgE antibodies were seen in 73% and 80% of the patients respectively. However, the delayed hypersensitivity reaction was more associated with patients having lesions for more than 6 months (48%) in comparison with patients with a short history (17%). On follow up after 6 months, the different hypersensitivity reactions and IgE antibody concentration maintained more or less the same association. Therefore in persistent or recurrent Tinea cruris infection, besides potential carriage in clinically normal sites, hypersensitivity to antigens of dermatophytes possibly plays an important role in pathogenicity.

Hereditary palmoplantar keratoderma and dermatophytosis in the northernmost county of Sweden (Norrbotten).

Clinical reports of hereditary palmoplantar keratoderma are generally based on a limited number of patients. In 1967 the prevalence in the northernmost county of Sweden (Norrbotten) was shown to be 0.55%. In 1982 it was possible to trace half of the original propositi from that study. Among these families, a severe clinical form with a presumed recessive inheritance could be distinguished. The clinical pictures in relatives of the original propositi were described, and other diseases were listed together with those in patients from previously performed studies. The frequency of dermatophytosis was 36.2%, which was equal to a prevalence of 37.6%. T. mentagrophytes occurred significantly more often and immunological factors, such as increased presence of blood group A, specific dermatophyte IgG antibodies, precipitating antibodies and an immunological in vitro reaction to keratin, supported differences in the distribution of dermatophytes. However, the amount of keratin was considered the most important factor for the affinity of dermatophytes to the palms and soles. A vesicular eruption along the hyperkeratotic border and a mononuclear cell infiltrate were often reported. Such reactions were interpreted as immunological reactions to dermatophytosis. Scaling and fissuring were considered clinical signs of dermatophyte infections and not a part of the originally reported clinical picture. Results of the histopathological study corresponded to previously reported descriptions of the Unna-Thost variety. However, it has recently been reported that the histopathological picture of this variety was based on histopathological features of epidermolytic palmoplantar keratoderma. The existence on the Continent of the Unna-Thost variety was therefore questioned. Histopathological features of epidermolytic palmoplantar keratoderma were not found in the County of Norrbotten and the designation "Diffuse HPPK type Norrbotten" has therefore been proposed. The histopathological picture of the presumed recessive variety did not differ from that of the dominant variety but ultrastructural characteristics differentiated it from Mal de Meleda and the dominant variety. It was therefore concluded that a new variety with a presumed recessive inheritance was found.

[The reaction to trichophytin in dermatophytoses]. / Contribuição ao estudo da reação à tricofitina nas dermatofitoses.

The authors investigated the specific immunological competence of 31 patients with dermatophytosis using tricophytin antigen. Among them, 54.8% showed reaction to the delay phase (48 h) in the following proportions: tinea inguinale, 75%; tinea pedis, 61.5%; tinea unguium, 50% and tinea corporis, 20%. Other 62.5% showed positive result to the early phase (30 m). The association between these reactions revealed that, although the majority of cases with early positive reaction showed negativity to the delayed reaction, 20.8% presented positively to both phases of the reaction. Out of the non-reactive patients to the delayed phase, 8 were submitted to the other cutaneous tests such as PPD, streptokinase, candidin, vaccinia and DNCB and showed preserved cellular immunity in 75%. These results suggest that, while using this reaction for immunological evaluation of patients with dermatophytosis, one should consider the overall immune status of the patient, the presence of early hypersensibility and the localization of the infection.

Contribuição ao estudo da reação à tricofitina nas dermatofitoses / Contribution to the study of the reaction to trichophyline in dermatophytoses

Os autores investigaram a competência imunológica específica de 31 indivíduos portadores de dermatofitose, utilizando o antígeno tricofitina. Destes, 54,8% mostraram-se reatores à fase tardia dessa prova (48 h) nas seguintes proporções: tinea inguinale, 75%; tinea pedis, 61,5%; tinea unguium, 50% e tinea corporis, 20%. 62,5% dos casos apresentaram positividade à fase imediata (30 m) da reação. A associação entre essas reações revelou que, embora a maioria dos pacientes com reação imediata positiva apresentasse negatividade à reação tardia, 20,8% apresentaram positividade para as duas fases da reação. Dos pacientes não reatores à fase tardia, oito foram submetidos a outros testes cutâneos: PPD, estreptoquinase, candidina, vacínia e DNCB, verificando-se imunidade celular conservada em 75% dos casos. Estes resultados sugerem que, quando da utilização dessa prova na avaliação imunológica de pacientes com dermatofitose, deve-se considerar o estado imune geral do paciente, a presença de hipersensibilidade imediata e a localização da infecção

The authors investigated the specific immunological competence of 31 patients with dermatophytosis using tricophytin antigen. Among them, 54.8% showed reaction to the delay phase (48 h) in the following proportions: tinea inguinale, 75%; tinea pedis, 61.5%; tinea unguium, 50% and tinea corporis, 20%. Other 62.5% showed positive result to the early phase (30 m). The association between these reactions revealed that, although the majority of cases with early positive reaction showed negativity to the delayed reaction, 20.8% presented positivity to both phases of the reaction. Out of the non-reactive patients to the delayed phase, 8 were submitted to the other cutaneous tests such as PPD, streptokinase, candidin, vaccinia and DNCB and showed preserved cellular immunity in 75%. These results suggest that, while using this reaction for immunological evaluation of patients with dermatophytosis, one should consider the overall immune status of the patient, the presence of early hypersensibility and the localization of the infection

Inflammation and immunity in dermatophytosis.

Infections by dermatophytes (dermatophytosis) naturally stimulate the immune system as in those by other microorganisms to induce various immunological phenomena. However, differing from other infections, the infecting organisms cannot become a direct target of antibody response or phagocytosis because they reside only in the barrier membrane of the body surface, i.e. in the stratum corneum. Thus, the immunity against dermatophytes is relative as compared with the absolute one noted in other infections such as measles and mumps. In dermatophytosis, a unique behavior of the epidermis as noted in contact dermatitis plays an important role in the defense against infection. Dermatitic changes induced by fungal products, particularly those due to contact sensitivity to a fungal antigen, trichophytin, enhance epidermopoiesis, which leads to increased turnover of the epidermis with their resultant elimination from the skin surface. Furthermore, the dermatophytes in the stratum corneum provoke transepidermal leukocyte chemotaxis by generating chemotactic C5a anaphylatoxin in exudating serum via alternative complement pathway activation in addition to a release of low molecular weight chemotactic factors. Such neutrophilic migration with the formation of subcorneal pustules also enhances epidermal proliferation as in psoriasis.

Hypersensitivity to trichophytin in small animals experimentally infected with Trichophyton equinum.

Typical lesions resulting from experimental Trichophyton equinum infection in laboratory animals persisted for 3-4 weeks. Lesions in rabbits were slightly less severe than those in guinea pigs. In experimentally infected dogs lesions persisted for longer and developed in the form of a deep, crusty dermatophytosis. In skin tests with three trichophytins it was shown that specific hypersensitivity resulting from infection of laboratory animals persists for at least 6 months. Stronger local reactions were produced with homologous trichophytins, especially in the final tests after 6 months.

[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.

Cell-mediated immunity in the immunopathogenesis of dermatophytosis.

CMI to dermatophyte antigens, principally trichophytin, is central to both (1) pathogenesis of the typical "ringworm" lesion and (2) an acquired, relative resistance that affords partial immunity to the host. The exact form of effector "T" cell immunity and the cellular and molecular mechanism(s) which eliminate dermatophytes from the skin, are poorly understood, but may involve lymphokine and accelerated epidermal turnover. Recent studies in the "nude" rat suggest that this thymic deficient animal offers potential for study of chronic, extensive dermatophytosis. The pathogenesis of the indolent inflammation of chronic infection is unclear, but may involve fungal derived chemotactic factors and/or activation of the alternative complement pathway. Chronic, extensive dermatophytosis may be caused by several different organisms, including T. rubrum, T. mentagrophytes, T. tonsurans and T. concentricum. Despite the multiple, microbial etiologies, most patients with this distinctive syndrome share similar immunological characteristics, including deficient, antigen-specific CMI to trichophytin. Approximately half of the patients have either an immediate hypersensitivity to trichophytin or an elevated serum IgE level, and in addition, they exhibit other stigmata of atopy including a positive family history. It is intriguing to consider the possibility that genetic control of the immune response may render a certain IgE hyperresponsive subpopulation unable to mount sufficient host resistance to reject dermatophyte infection.