Lanosterol 14α-demethylase (CYP51)/histone deacetylase (HDAC) dual inhibitors for treatment of Candida tropicalis and Cryptococcus neoformans infections.

Invasive fungal infections remain a challenge due to lack of effective antifungal agents and serious drug resistance. Discovery of antifungal agents with novel antifungal mechanism is important and urgent. Previously, we designed the first CYP51/HDAC dual inhibitors with potent activity against resistant Candida albicans infections. To better understand the antifungal spectrum and synergistic mechanism, herein new CYP51/HDAC dual inhibitors were designed which showed potent in vitro and in vivo antifungal activity against C. neoformans and C. tropicalis infections. Antifungal mechanism studies revealed that the CYP51/HDAC dual inhibitors acted by inhibiting various virulence factors of C. tropicalis and C. neoformans and down-regulating resistance-associated genes. This study highlights the potential of CYP51/HDAC dual inhibitors as a promising strategy for the discovery of novel broad-spectrum antifungal agents.

Dissolving microneedle-mediated dermal delivery of itraconazole nanocrystals for improved treatment of cutaneous candidiasis.

The administration of conventional dosage forms of itraconazole (ITZ) for cutaneous candidiasis treatment is limited by its poor aqueous solubility and the deep location ofCandida albicans(CA) in this disease. In the present work, we developed a nanocrystal (NC) form of ITZ, which was incorporated into dissolving microneedles (MNs) to facilitate skin delivery of ITZ into the infection site. The NCs were prepared by media milling with an ultra-small-scale device using Pluronic®F127 as a stabiliser. The antifungal activity of ITZ was enhanced by NC formulations (MIC value of 2.5 µg/ml), compared to a coarse dispersion of ITZ (MIC value of >2560 µg/ml). The formulation of ITZ into NCs increased dissolution rate by 3-fold. Furthermore, the dissolving MNs containing ITZ-NCs exhibited better dermatokinetic profiles, compared to needle-free patches and conventional creams containing ITZ-NCs. Importantly, the antifungal activity in anex vivocandidiasis infection model exhibited that the CA viability declined by up to 100% after 48 h of administration. These studies have verified the concept that the incorporation of ITZ-NCs into dissolving MNs can offer an effective approach for cutaneous candidiasis treatment.

Mycological Considerations in the Topical Treatment of Superficial Fungal Infections.

Trichophyton rubrum remains the most common pathogenic dermatophyte in the United States, Europe, and industrialized Asia, although other species are predminant elsewhere. Candida albicans is the most common pathogenic yeast, with other species occasionally encountered. Just a few of the 14 described species of Malassezia cause pityriasis versicolor worldwide. FDA approval does not always accurately reflect the potential utility of any given topical antifungal agent. Azole, hydroxypyridone, and allylamine agents are beneficial in the management of dermatophytosis; however, the allylamines may lead to faster symptom resolution and a higher degree of sustained response. Although in actual clinical use the allylamines have all shown some activity against superficial cutaneous candidiasis and pityriasis versicolor, the azole agents remain drugs of choice. Ciclopirox is an excellent broad-spectrum antifungal agent. Optimal topical therapy for superficial fungal infections cannot yet be reliably based upon in-vitro laboratory determination of sensitivity. Inherent antibacterial and anti-inflammatory properties possessed by some antifungal agents may be exploited for clinical purposes. Candida species may be azole-insensitive due to efflux pumps or an altered target enzyme. So-called "antifungal resistance" of dermatophyets is actually due to poor patient adherence (either in dosing or treatment duration), or to reinfection.

Signaling through IL-17C/IL-17RE is dispensable for immunity to systemic, oral and cutaneous candidiasis.

Candida albicans is a commensal fungal microbe of the human orogastrointestinal tract and skin. C. albicans causes multiple forms of disease in immunocompromised patients, including oral, vaginal, dermal and disseminated candidiasis. The cytokine IL-17 (IL-17A) and its receptor subunits, IL-17RA and IL-17RC, are required for protection to most forms of candidiasis. The importance of the IL-17R pathway has been observed not only in knockout mouse models, but also in humans with rare genetic mutations that impact generation of Th17 cells or the IL-17 signaling pathway, including Hyper-IgE Syndrome (STAT3 or TYK2 mutations) or IL17RA or ACT1 gene deficiency. The IL-17 family of cytokines is a distinct subclass of cytokines with unique structural and signaling properties. IL-17A is the best-characterized member of the IL-17 family to date, but far less is known about other IL-17-related cytokines. In this study, we sought to determine the role of a related IL-17 cytokine, IL-17C, in protection against oral, dermal and disseminated forms of C. albicans infection. IL-17C signals through a heterodimeric receptor composed of the IL-17RA and IL-17RE subunits. We observed that IL-17C mRNA was induced following oral C. albicans infection. However, mice lacking IL-17C or IL-17RE cleared C. albicans infections in the oral mucosa, skin and bloodstream at rates similar to WT littermate controls. Moreover, these mice demonstrated similar gene transcription profiles and recovery kinetics as WT animals. These findings indicate that IL-17C and IL-17RE are dispensable for immunity to the forms of candidiasis evaluated, and illustrate a surprisingly limited specificity of the IL-17 family of cytokines with respect to systemic, oral and cutaneous Candida infections.

Influence of various lipid core on characteristics of SLNs designed for topical delivery of fluconazole against cutaneous candidiasis.

Dermal delivery of fluconazole (FLZ) is still a major limitation due to problems relating to control drug release and achieving therapeutic efficacy. Recently, solid lipid nanoparticles (SLNs) were explored for their potential of topical delivery, possible skin compartments targeting and controlled release in the skin strata. The retention and accumulation of drug in skin is affected by composition of SLNs. Hence, the aim of this study was to develop FLZ nanoparticles consisted of various lipid cores in order to optimize the drug retention in skin. SLNs were prepared by solvent diffusion method and characterized for various in vitro and in vivo parameters. The results indicate that the SLNs composed of compritol 888 ATO (CA) have highest drug encapsulation efficiency (75.7 ± 4.94%) with lower particle size (178.9 ± 3.8 nm). The in vitro release and skin permeation data suggest that drug release followed sustained fashion over 24 h. The antifungal activity shows that SLNs made up of CA lipid could noticeably improve the dermal localization. In conclusion, CA lipid based SLNs are represents a promising carrier means for the topical treatment of skin fungal infection as an alternative to the systemic delivery of FLZ.

IL-23 and IL-17A, but not IL-12 and IL-22, are required for optimal skin host defense against Candida albicans.

IL-23 and Th17 cells play important roles in host defense against systemic infections with extracellular bacteria and fungi, although their roles in immunity against localized skin infections are less well defined. Here, the contributions of IL-23 and Th17 cytokines in host defense against cutaneous Candida albicans infection were evaluated. Mice deficient in IL-23 or IL-17A demonstrated delayed healing and decreased IL-17A production after skin infection with C. albicans compared with wild-type mice or mice deficient in IL-12 or IL-22. Histologic examination revealed epidermal hyperplasia overlying infected dermis four days postinoculation in wild-type mice. In IL-23-deficient mice, fungal burden was greater in skin, neither IL-17A nor IL-22 mRNAs were expressed postinfection, and these mice demonstrated only minimal epidermal hyperplasia. Exogenous recombinant IL-17A injected at the site of skin infection promoted more rapid healing of candidiasis in both wild-type mice and mice deficient in IL-23 and IL-12. Taken together, these results demonstrate that IL-23 and IL-17A, but not IL-12 and IL-22, are required for optimal host defense against cutaneous candidiasis. In addition, recombinant IL-17A may serve as a potential therapy to enhance healing in individuals with chronic cutaneous candidiasis.

Candida albicans phospholipomannan triggers inflammatory responses of human keratinocytes through Toll-like receptor 2.

The Toll-like receptors (TLRs) play an important role in the recognition of Candida albicans components and activation of innate immunity. Phospholipomannan (PLM), a glycolipid, is expressed at the surface of C. albicans cell wall, which acts as a member of the pathogen-associated molecular patterns family. In this study, we sought to clarify whether C. albicans-native PLM could induce an inflammation response in human keratinocytes and to determine the underlying mechanisms. Exposure of cultured human primary keratinocytes to PLM led to the increased gene expression and secretion of proinflammatory cytokines (IL-6) and chemokines (IL-8). PLM hydrolysed with beta-d-mannoside mannohydrolase failed to induce gene expression and secretion of IL-6 and IL-8. PLM up-regulated the mRNA and protein levels of TLR2, whereas the mRNA level of TLR4 was not altered. Keratinocytes challenged with PLM resulted in the activation of NF-kappaB and mitogen-activated protein kinase (MAPKs) including p38. Anti-TLR2 neutralizing antibody, NFkappaB and p38MAPK inhibitors blocked the PLM-induced secretion of IL-6, IL-8 in keratinocytes, but no such effect was observed in pretreatment with anti-TLR4-neutralizing antibody and lipopolysaccharide inhibitor (polymyxin B). These data suggest C. albicans-native PLM may contribute to the inflammatory responses of cutaneous candidiasis in the TLR2-NF-kappaB and p38MAPK signalling pathway dependent manner.

Biochemical and physiological parameters on the healthy skin surface of persons with candidal intertrigo and of persons with tinea cruris.

Biochemical and physiological tests were carried out on the skin surface of 20 patients with candidal intertrigo and 27 patients with tinea cruris. In all patients the test areas were free of efflorescences. The same tests were performed in 39 and 27 resectively healthy test persons of the same age and sex. The following striking findings came to light: 1. There was a significant decrease in the percentage amount of squalene in the skin surface lipids of the moniliasis group as compared with the control group. 2. There was a significant decrease in the reducing substances in the so called water solubles obtained with the phenol sulfuric acid method in the moniliasis group. The same results were obtained when only those moniliasis patients who were definitely not suffering from diabetes mellitus were taken into account. This is presumably a question of a reduction in the bound carbohydrates. 3. There were significantly more amino acids extractable from the skin surface of the tinea cruris patients than of the control persons. These results point to important predisposing factors for the susceptibility to candidal intertrigo and tinea cruris respectively.