Cytokine production of peripheral blood mononuclear cells in a dermatophytosis patient in response to stimulation with trichophytin

The interplay among Th17 and T regulatory cells in the immune dysregulation of chronic dermatophytic infection

The delineation of the pathogenic interaction between the host skin immune responses and dermatophytes has remained indigent. The obscure enigma in host-dermatophyte immunopathogenic interactions is the T regulatory (Treg) and T-helper (Th) 17  cell role in maintaining immune homeostasis. We attempted to understand the regulation and recognition of lineage-specific response in chronic dermatophytic skin infection patients. The percentages of Th17 (CD4⁺CD161⁺IL23R⁺) and Treg (CD4⁺CD25⁺FoxP3⁺) cell subpopulations in the peripheral circulation of thirty chronic dermatophytic skin infection patients and twenty healthy individuals was determined. The serum cytokine levels were estimated for disease correlation. The mean duration of the disease was 10.68 ± 8.72 months, with Trichophyton mentagrophytes complex as the major pathogen. Total serum IgE level of patients was significantly higher compared to healthy controls (305 ± 117 vs 98.53 ± 54.55 IU/ml; p < 0.01). Expression of Th17 and Treg cell markers on CD4⁺ T cells was significantly elevated in patients than controls (p < 0.05). Comparatively, serum interleukin (IL)-4 and interferon (IFN)-γ levels were increased, with low IL-10 levels in patients. Our data envisages a complex immune dysfunction in chronic dermatophytosis, arising either as a result of dermatophyte exposure or paradoxical precedence of disease establishment. Designing new treatment strategies and preventing recurrences are challenges for future research.

Anti-inflammatory effect of lanoconazole on 12-O-tetradecanoylphorbol-13-acetate- and 2,4,6-trinitrophenyl chloride-induced skin inflammation in mice

Background

Lanoconazole (LCZ) is a topical antifungal agent clinically used to treat fungal infections such as tinea pedis. LCZ has not only antifungal effects but also anti‐inflammatory effects, which have the potential to provide additional clinical benefits. However, the characteristic features of the inhibitory effects of LCZ on skin inflammation remain unclear.

Objective

We evaluated the inhibitory effects of topical application of LCZ, and compared the effects of LCZ with those of other antifungal agents including liranaftate, terbinafine and amorolfine.

Methods

Each antifungal agent was topically applied on 12‐O‐tetradecanoylphorbol‐13‐acetate‐induced irritant dermatitis and 2,4,6‐trinitrophenyl chloride‐induced contact dermatitis in mice (BALB/c). The ear thickness, myeloperoxidase activity and inflammatory mediator contents were evaluated.

Results

LCZ dose‐dependently suppressed 12‐O‐tetradecanoylphorbol‐13‐acetate‐induced irritant dermatitis, suppressed the production of neutrophil chemotactic factors such as keratinocyte‐derived chemokine and macrophage inflammatory protein‐2, and inhibited neutrophil infiltration to the inflammation site. Moreover, 1% LCZ reduced the ear swelling in mice with 2,4,6‐trinitrophenyl chloride‐induced contact dermatitis in accordance with the inhibition of interferon‐γ production. The inhibitory potency of LCZ on these types of dermatitis in mice was stronger than that of other types of antifungal agents.

Conclusion

The anti‐inflammatory effects of LCZ were exerted through the inhibition of inflammatory mediator production. These effects may contribute to the relief of dermatitis symptoms in patients with tinea pedis.

Are Th17 Cells Playing a Role in Immunity to Dermatophytosis?

Despite their superficial localization in the skin, pathogenic dermatophytes can induce a complex but still misunderstood immune response in their hosts. The cell-mediated immunity (CMI) is correlated with both clinical recovery and protection against reinfection, and CD4+ T lymphocytes have been recognized as a crucial component of the immune defense against dermatophytes. Before the discovery of the Th17 pathway, CMI was considered to be only dependent of Th1 cells, and thus most studies on the immunology of dermatophytosis have focused on the Th1 pathway. Nevertheless, the fine comparative analysis of available scientific data on immunology of dermatophytosis in one hand and on the Th17 pathway mechanisms involved in opportunistic mucosal fungal infections in the other hand reveals that some key elements of the Th17 pathway can be activated by dermatophytes. Stimulation of the Th17 pathway could occur through the activation of some C-type lectin-like receptors and inflammasome in antigen-presenting cells. The Th17 cells could go back to the affected skin and by the production of signature cytokines could induce the effector mechanisms like the recruitment of polymorphonuclear neutrophils and the synthesis of antimicrobial peptides. In conclusion, besides the Th1 pathway, which is important to the immune response against dermatophytes, there are also growing evidences for the involvement of the Th17 pathway.

Anti-inflammatory activity of lanoconazole, a topical antifungal agent

Topical antifungal agents which have anti-inflammatory effects have the potential to provide additional clinical benefits. Therefore, an anti-inflammatory activity of lanoconazole (LCZ), a topical antifungal agent, was investigated against in vitro and in vivo models of inflammation. The release of interleukin-8 (IL-8) from human epidermal keratinocytes stimulated by the addition of 100 μg ml(-1) β-glucan of Saccharomyces cerevisiae was significantly inhibited by LCZ at the concentration of 10(-5) mol l(-1). The release of interferon-γ and IL-2 from human peripheral blood mononuclear cells stimulated by the addition of 30 and 100 μg ml(-1) phytohemagglutinin was significantly inhibited by LCZ at the concentrations of 10(-7) and 10(-6) mol l(-1), respectively. The increase in the ear thickness induced by topical application of 0.01% 12-O-tetradecanoyl phorbol-13-acetate and 1% 2,4,6-trinitrochlorobenzene (TNCB) after sensitisation with 3% TNCB were established as the mouse models of irritant and contact dermatitis, respectively. Application of 1% and 3% LCZ showed a significant anti-inflammatory activity against both the irritant and contact dermatitis models. These findings suggest that LCZ possesses an anti-inflammatory activity, which may be partially helpful in the treatment of dermatomycoses.

Pathogenesis of tinea

Dermatophytes are hyphomycetes that can degrade keratin. This puts them in a position to cause infections of the keratin-containing superficial skin. The resulting clinical picture is called tinea. The pathogenesis and course of tinea is decisively determined by pathogen-related factors and by the defense mechanisms of the host. An infection starts with an adherence of fungal propagules, followed by the formation of hyphae that can spread within the tissue. This process is accompanied by a release of fungal enzymes and other pathogenic factors. Next keratinocytes are activated, the epidermal barrier is destroyed, epidermal proliferation is enhanced and defensins are expressed within the epidermis. In addition, innate and specific immune responses are initiated, involving neutrophilic granulocytes, macrophages, antibodies and T cells. The cellular mechanisms are thought to be crucial for healing. Special conditions apply to nail infections, because within nail plates the fungi are not accessible to effective defense mechanisms, as well as to infections of hair follicles that contain specific concentrations of steroid hormones. Dermatophytes that penetrate into the dermis can cause granulomatous inflammatory reactions and systemic immune reactions are supposed to be a trigger of so-called id reactions.

Anti-inflammatory and anti-itch activity of sertaconazole nitrate

Cutaneous fungal infections are frequently associated with an inflammatory component including irritated skin, itching and stinging/burning. Therapeutic anti-fungal agents that have anti-inflammatory activity have the potential to provide clinical benefit beyond fungus eradication. Recently, certain anti-fungal agents have been shown to have intrinsic anti-inflammatory activity, therefore we sought to determine the extent of the anti-inflammatory activity of these compounds. The anti-inflammatory activities of eight anti-fungal agents (butoconazole, ciclopirox olamine, fluconazole, miconazole nitrate, sertaconazole nitrate, terconazole, tioconazole and ketoconazole) were compared in a number of preclinical models of dermal inflammation and pruritus. While butoconazole, ciclopirox olamine, fluconazole, and miconazole nitrate were all found to have anti-inflammatory activity, only sertaconazole nitrate reduced the release of cytokines from activated lymphocytes and mitigated inflammation in animal models of irritant contact dermatitis and neurogenic inflammation. In addition, sertaconazole nitrate inhibited contact hypersensitivity and scratching responses in a murine model of pruritus. Furthermore, the in vitro and in vivo anti-inflammatory activity of sertaconazole nitrate was found to be greater than other topical anti-fungal agents examined. These studies demonstrate that topical administration of clinically relevant concentrations of sertaconazole nitrate resulted in an efficacious anti-inflammatory activity against a broad spectrum of dermal inflammation models and itch. The anti-inflammatory properties of sertaconazole may contribute to the efficacy of the drug in the treatment of cutaneous fungal conditions and provide greater anti-inflammatory activity compared with other anti-fungal agents.

Effect of lactoferrin feeding on the host antifungal response in guinea-pigs infected or immunised with Trichophyton mentagrophytes

Earlier studies revealed that oral administration of lactoferrin (LF), a multi-functional milk protein, facilitated curing of dermatophytosis in guinea-pigs and man by an unknown mechanism. The present study aimed to assess the effect of feeding bovine LF on the host antifungal defence systems in guinea-pigs infected or immunised with Trichophyton mentagrophytes, a dermatophytosis-causing fungus. The unbound iron-binding capacity (UIBC) of the plasma of individual animals varied, and plasma with higher UIBC inhibited growth of T. mentagrophytes in vitro. However, LF administration did not enhance plasma UIBC or the anti-T. mentagrophytes activity of plasma in infected or uninfected animals. Phagocytic activity and reactive oxygen (RO) production of blood neutrophil polymorphonuclear leucocytes (PMNLs) were estimated by flow cytometry. LF administration caused no significant effects on phagocytic activity or RO production of neutrophil PMNLs in infected or uninfected animals. The functions of mononuclear cells (MNC) from the spleen were investigated in guinea-pigs immunised with heat-killed T. mentagrophytes conidia. The MNC were cultured with concanavalin A or inactivated T. mentagrophytes. In the bromo-deoxyuridine incorporation assay, the stimulation index was higher for MNC derived from LF-treated animals than for those from control animals. The culture supernates of MNC enhanced the ability of macrophages to kill T. mentagrophytes conidia. Furthermore, stronger augmentation was observed with the culture supernate from LF-treated animals than with that from control animals. In conclusion, LF feeding may potentiate the host antifungal defence systems by modulating MNC function rather than plasma antifungal activity or peripheral blood neutrophil PMNL activity.

In vitro release of interferon-gamma by trichophytin-stimulated whole blood cell cultures from ringworm-vaccinated and control calves experimentally inoculated with Trichophyton verrucosum

Of a group of seven calves, four were vaccinated against bovine ringworm with the vaccine Ringvac bovis LTF-130 (Alpharma, Oslo, Norway), while three calves were left unvaccinated. All calves were inoculated epicutaneously with a virulent strain of Trichophyton verrucosum. Clinical signs were recorded. In response to stimulation with trichophytin, in vitro interferon-gamma (IFN-gamma) production in whole blood cell cultures was assessed in samples obtained pre- and post-vaccination and pre- and post-inoculation. A commercial enzyme immunoas say kit was used to measure IFN-gamma levels (Bovigam, CSL, Victoria, Australia). Control calves developed typical ringworm lesions, whereas vaccinated calves did not. Following vaccination, release of IFN-gamma in whole blood cell cultures indicated the presence of circulating trichophytin-specific lymphocytes. After inoculation with T. verrucosum, IFN-gamma production was demonstrated in samples from both vaccinated and control calves. This study showed that vaccination with Ringvac bovis LTF-130 elicits a protective immune response suggesting involvement of the cellular branch of the immune system. Experimental infection of naïve nonvaccinated calves with T. verrucosum, also indicated stimulation of a cell-mediated immune response essential for resolution of lesions.