Characterization of the cellular immunity in patients presenting extensive dermatophytoses due to Trichophyton rubrum

The Role of Thickening Agent Proportions in Optimizing Nanoemulsion Gel for Dermatophytosis Treatment

Background

Adjusting thickening agent proportions in nanoemulsion gel (NG) balances its transdermal and topical delivery properties, making it more effective for dermatophytosis treatment.

Methods

Carbomer 940 and α-pinene were used as model thickening agent and antifungal, respectively. A series of α-pinene NGs (αNG1, αNG2, αNG3) containing 0.5%, 0.75% and 1% (w/w) Carbomer 940 were developed and evaluated for stability, rheological properties, and skin irritation; assessed for ex vivo skin permeation, deposition, and fluorescent imaging of drug distribution within skin layers; and tested in vivo for efficacy against Trichophyton rubrum infection in guinea pigs, with PAS (Periodic Acid-Schiff) staining confirming fungal clearance.

Results

The steady-state skin flux rates of α-pinene over 24 hours were αNG1 (46.93±2.52 μg/cm²/h) > αNG2 (26.01±2.65 μg/cm²/h) > αNG3 (11.36±1.69 μg/cm²/h). The α-pinene deposition in the epidermis/dermis for αNG1 decreased substantially from 2 h (62.74 ± 3.36 μg/cm²) to 12 h (11.7 ± 2.24 μg/cm²). In contrast, αNG2 showed relatively sustained deposition with 2 h (25.54 ± 2.67 μg/cm²), 6 h (57.32 ± 4.62 μg/cm²) and 12 h (23.69 ± 3.29 μg/cm²). αNG3 exhibited a slow increase from 2 h (18.32 ± 2.11 μg/cm²) to 12 h (36.78 ± 3.22 μg/cm²). The αNG2 exhibited the highest efficacy and fungal clearance rates (71.42%, 79.17%), followed by αNG1 (55.34% and 60.42%), and αNG3(43.21%, 52.08%). Fluorescent imaging confirmed αNG2's higher drug deposition within the epidermis/dermis, while PAS staining showed a potent fungal clearance with αNG2.

Conclusion

This study demonstrates that Carbomer 940 proportions significantly impact the transdermal performance of αNG. αNG2, with a moderate proportion, optimally enhances skin drug delivery and deposition, achieving superior therapeutic outcomes. These findings highlight the importance of optimizing thickening agent proportions to improve the efficacy of topical nanoemulsion gels.

A Clinico-Mycological and Histopathological Study of Recurrent Dermatophytosis

Background

A few recent studies have shown fungal elements within the hair follicle epithelium, which may act as a reservoir and responsible for recurrent dermatophytosis.

Objectives

To assess the clinical patterns, mycological profile, and histopathology of recurrent dermatophytosis and to determine the prevalence of fungal hyphae in the hair follicle epithelium and other appendages.

Materials and Methods

One hundred and fifty clinically diagnosed cases of recurrent dermatophytic infection were included. Skin samples were taken for direct microscopy, fungal culture, and histopathological analysis. Haematoxylin and eosin and special staining with periodic acid Schiff (PAS) and Gomori's methenamine silver (GMS) were performed to detect the fungal hyphae in the skin and hair follicle epithelium.

Results

The most common clinical pattern observed was tinea corporis et cruris in 64 patients (42.66%). On direct microscopy and fungal culture, positive results were obtained in 116 cases (77.33%) and 78 (52%) cases, respectively. Presence of fungal hyphae in the stratum corneum, hair follicle, and acrosyringium was seen in 107 patients (71.33%), 47 patients (31.33%), and five patients (3.33%), respectively. Out of the 52 cases with hair follicle and eccrine gland involvement, history of fixed drug combinations (FDC) cream use was present in 42 cases (80.76%) and absent in ten cases (19.24%) (P = 0.000062).

Limitations

Skin samples were taken only from a single skin lesion. Higher incidence of follicular invasion may have been detected if multiple biopsy samples were taken.

Conclusion

Hair follicle/eccrine sweat gland involvement was observed in nearly one-third of the patients, which may act as a reservoir and may be responsible for recurrence and chronicity. Histopathology should be considered as an important adjuvant tool in recurrent dermatophytosis to establish the extent of the infection, which guides the further management.

Pathogenesis, Immunology and Management of Dermatophytosis

Dermatophytic infections of the skin and appendages are a common occurrence. The pathogenesis involves complex interplay of agent (dermatophytes), host (inherent host defense and host immune response) and the environment. Infection management has become an important public health issue, due to increased incidence of recurrent, recalcitrant or extensive infections. Recent years have seen a significant rise in incidence of chronic infections which have been difficult to treat. In this review, we review the literature on management of dermatophytoses and bridge the gap in therapeutic recommendations.

Immunopathogenesis of Dermatophytoses and Factors Leading to Recalcitrant Infections

The pathogenesis of dermatophytic infections involves the interplay of three major factors: the dermatophyte, the inherent host defense, and the adaptive host immune response. The fungal virulence factors determine the adhesion and invasion of the skin while the immune response depends on an interaction of the pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMP) with pattern recognition receptors (PRRs) of the host, which lead to a differential Th (T helper) 1, Th2, Th17, and Treg response. While anthropophilic dermatophytes Trichophyton rubrum and now increasingly by T. interdigitale subvert the immune response via mannans, zoophilic species are eliminated due to a brisk immune response. Notably, delayed-type hypersensitivity (Th1) response of T lymphocytes causes the elimination of fungal infection, while chronic disease caused by anthropophilic species corresponds to toll-like receptor 2 mediated IL (interleukin)-10 release and generation of T-regulatory cells with immunosuppressive potential. Major steps that determine the ultimate clinical course and chronicity include genetic susceptibility factors, impaired epidermal and immunological barriers, variations in the composition of sebum and sweat, carbon dioxide tension, skin pH, and topical steroid abuse. It is important to understand these multifarious aspects to surmount the problem of recalcitrant dermatophytosis when the disorder fails conventional therapeutic agents.

The effect of cytoplasmic crude extracts of Trichophyton verrucosum on cell mediated immunity

OBJECTIVE

Trichophyton verrucosum is a slow growing dermatophyte responsible for a number of skin diseases such as ringworm, and is characterized by patches of hair loss and thick crusts on the host skin in domestic animals. In this study, we examined the immunomodulatory effects of crude extract of Trichophyton verrucosum (TV)cytoplasm in a mouse model.

METHODS

The TV variate was cultured on Sabouraud dextrose agar and the mycelium was grinded by mechanical force. The purified protein was obtained from crude extract of the fungus, and protein concentration was measured by BradFord assay. Six to eight week-female BALB/c mice were divided into three groups: test group, receiving cytoplasmic crude extract plus defibrinated sheep blood; control group, receiving defibrinated sheep blood; and normal group, receiving normal saline. Injections were performed on days 0, 3, 5, 7 and 9 and the mice were sacrificed four days after the last injection. T lymphocyte metabolic activity was examined by methyl thiazol tetrazolium (MTT) assay, and also interleukin-4 (IL-4) and interferon-γ (IFNγ) levels were evaluated by enzyme-linked immunosorbent assay (ELISA).

RESULTS

MTT assay showed that the TV extract stimulated lymphocyte metabolic activity. ELISA results showed that despite increase in the level of IFNγ, no changes were observed in IL-4 level.

CONCLUSIONS

Results indicated that crude extract of TV cytoplasm may probably act as an immune modulator, which affects Th₁ responses. The TV crude extract may be an appropriate agent to induce cellular immunity for combating dermatophytosis infection in animals; and therefore, TV extract may have some potential applications in vaccine/adjuvant technology.

Cellular immunodeficiency related to chronic dermatophytosis in a patient with Schistosoma mansoni infection: can schistosomiasis induce immunodeficiency?

Here, we describe a case of hepatosplenic schistosomiasis that progressed to widespread persistent dermatophytosis. Significant T and B lymphocytopenia was confirmed. T-cell deficit is associated with increased susceptibility to fungal infections of skin and mucous membranes. The accumulation of a large amount of blood cells in the spleen could have played a crucial role in the development of lymphocytopenia in the present case. Alternatively, the schistosomiasis-induced increase in prostaglandin E2 levels could have inhibited the production of interferon-γ, a cytokine fundamental to fungal resistance. This case shows the potential of hepatosplenic schistosomiasis to impair the immune response.

Immunoresponses in dermatomycoses

Contact with fungal pathogens initiates a series of host responses beginning with innate immunity, which leads to fungal recognition and microbial killing. The innate immune system also modulates the adaptive immune responses, leading to the establishment of immunological memory and protection against pathogens. In the case of dimorphic fungi such as Candida albicans and Malassezia, the immune system plays an important role in tolerance and resistance when managing the organisms either as commensal microbiota or invading pathogens, and disruption of this balance can result in pathological consequences for the host. In addition, Malassezia and dermatophytes have immunomodulatory capabilities that allow them to adapt to their environments and they may exert different effects in healthy and diseased skin. Here, we discuss the host immune responses to dermatomycoses caused by dimorphic fungi such as C. albicans and Malassezia as well as dermatophytes such as Trichophyton spp. and Arthroderma benhamiae to gain a better understanding of the mechanisms of the host-dermatomycosis interaction.

Dectin-1 and Dectin-2 promote control of the fungal pathogen Trichophyton rubrum independently of IL-17 and adaptive immunity in experimental deep dermatophytosis

Dermatophytoses are chronic fungal infections, the main causative agent of which is Trichophyton rubrum (T. rubrum). Despite their high occurrence worldwide, the immunological mechanisms underlying these diseases remain largely unknown. Here, we uncovered the C-type lectin receptors, Dectin-1 and Dectin-2, as key elements in the immune response to T. rubrum infection in a model of deep dermatophytosis . In vitro, we observed that deficiency in Dectin-1 and Dectin-2 severely compromised cytokine production by dendritic cells. In vivo, mice lacking Dectin-1 and/or Dectin-2 showed an inadequate pro-inflammatory cytokine production in response to T. rubrum infection, impairing its resolution. Strikingly, neither adaptive immunity nor IL-17 response were required for fungal clearance, highlighting innate immunity as the main checkpoint in the pathogenesis of T. rubrum infection.

The Immunologic Response to Trichophyton Rubrum in Lower Extremity Fungal Infections

Manifestations of Trichophyton rubrum infestations, such as tinea pedis, tinea cruris, and tinea corporis, are among the most common human skin diseases seen throughout the world. About 80% of patients presenting with acute dermatophytosis respond well to topical antifungal treatment. However, the remaining 20% of patients progress into a chronic state of dermatophytosis, which is resistant to antifungal treatment. Therefore, it is necessary to have a better understanding and appreciation for the diverse immune responses to Trichophyton as this is critical for the development of therapeutic strategies for those individuals who suffer from a chronic manifestation of Trichophyton rubrum (T. rubrum) infection. As a result, a comprehensive literature review was conducted to review and discuss previous studies that evaluated the human body’s defense to T. rubrum infections and to understand why and how these fungal infections invade the host defense system. Our research revealed that a cell-mediated immune response is critical in defending the body against T. rubrum. However, this organism has mechanisms that enable it to evade the immune system. Therefore, a more successful treatment for chronic T. rubrum infection would involve targeting the mechanisms of T. rubrum that diminish the immune response, while restoring the cell-mediated immune response.

Mycology - an update. Part 1: Dermatomycoses: causative agents, epidemiology and pathogenesis

Dermatomycoses are caused most commonly by dermatophytes. The anthropophilic dermatophyte Trichophyton rubrum is still the most frequent causative agent worldwide. Keratinolytic enzymes, e.g. hydrolases and keratinases, are important virulence factors of T. rubrum. Recently, the cysteine dioxygenase was found as new virulence factor. Predisposing host factors play a similarly important role for the development of dermatophytosis of the skin and nails. Chronic venous insufficiency, diabetes mellitus, disorders of cellular immunity, and genetic predisposition should be considered as risk factors for onychomycosis. A new alarming trend is the increasing number of cases of onychomycosis - mostly due to T. rubrum - in infancy. In Germany, tinea capitis is mostly caused by zoophilic dermatophytes, in particular Microsporum canis. New zoophilic fungi, primarily Trichophyton species of Arthroderma benhamiae, should be taken into differential diagnostic considerations of tinea capitis, tinea faciei, and tinea corporis. Source of infection are small household pets, particularly rodents, like guinea pigs. Anthropophilic dermatophytes may be introduced by families which immigrate from Africa or Asia to Europe. The anthropophilic dermatophytes T. violaceum, T. tonsurans (infections occurring in fighting sports clubs as "tinea gladiatorum capitis et corporis") and M. audouinii are causing outbreaks of small epidemics of tinea corporis and tinea capitis in kindergartens and schools. Superficial infections of the skin and mucous membranes due to yeasts are caused by Candida species. Also common are infections due to the lipophilic yeast fungus Malassezia. Today, within the genus Malassezia more than 10 different species are known. Malassezia globosa seems to play the crucial role in pityriasis versicolor. Molds (also designated non-dermatophyte molds, NDM) are increasingly found as causative agents in onychomycosis. Besides Scopulariopsis brevicaulis, several species of Fusarium and Aspergillus are found.