A murine model of cutaneous aspergillosis for evaluation of biomaterials-based local delivery therapies.

Cutaneous fungal infection is a challenging condition to treat that primarily afflicts immunocompromised patients. Local antifungal therapy may permit the delivery of high concentrations of antifungals directly to wounds while minimizing systemic toxicities. However, the field currently lacks suitable in vivo models. Therefore, a large cutaneous wound was created in immunosuppressed mice and inoculated with Aspergillus fumigatus. We fabricated biodegradable polymer microparticles (MPs) that were capable of locally delivering antifungal and characterized in vitro release kinetics. We compared wound bed size, fungal burden, and histological presence of fungi in mice treated with antifungal-loaded MPs. Mice with a cutaneous defect but no infection, mice with infected cutaneous defect but no treatment, and infected mice treated with blank MPs were used as controls. Infection of large wounds inhibited healing and resulted in tissue invasion in an inoculum-dependent manner. MPs were capable of releasing antifungals at concentrations above A. fumigatus Minimum Inhibitory Concentration (MIC) for at least 6 days. Wounds treated with MPs had significantly decreased size compared with no treatment (64.2% vs. 19.4% wound reduction, p = 0.002) and were not significantly different from uninfected controls (64.2% vs. 58.1%, p = 0.497). This murine model may serve to better understand cutaneous fungal infection and evaluate local biomaterials-based therapies. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1867-1874, 2019.

Cryptococcus-like changes in the setting of vasculitis.

Cutaneous vasculitis has many underlying causes, and the clinical and histological findings often overlap. Inflammatory vasculitis can mimic infection; however, distinction is critical for the timely institution of appropriate therapy. We present two patients who had generalized polymorphous eruptions whose cutaneous pathology showed vasculitis with unusual haloed yeast-like cells within the inflammatory infiltrate, mimicking Cryptococcus. The unusual cells stained negatively with Gomori methenamine silver and periodic acid-Schiff fungal stains, but positively for CD68 and had cytoplasmic reactivity with antibody to myeloperoxidase (MPO). Both patients had positive serum anti-MPO antibodies. The first patient experienced a rapidly fatal course, whereas the second patient improved with prompt initiation of systemic corticosteroids. Interestingly, the second case had prior biopsy showing Sweet syndrome with crypotoccoid-appearing cells. Cryptococcoid cells have been described previously in association with neutrophilic dermatoses, but not in the setting of vasculitis as was seen in our patients. Our cases add to the existing literature on crypotoccoid mimickers, and are the first to be reported in association with vasculitis.

Epidermal epidemic: unravelling the pathogenesis of chytridiomycosis.

Chytridiomycosis, a lethal fungal skin disease of amphibians, fatally disrupts ionic and osmotic homeostasis. Infected amphibians increase their skin shedding rate (sloughing) to slow pathogen growth, but the sloughing process also increases skin permeability. Healthy amphibians increase active ion uptake during sloughing by increasing ion transporter abundance to offset the increased skin permeability. How chytridiomycosis affects the skin function during and between sloughing events remains unknown. Here, we show that non-sloughing frogs with chytridiomycosis have impaired cutaneous sodium uptake, in part because they have fewer sodium transporters in their skin. Interestingly, sloughing was associated with a transient increase in sodium transporter activity and abundance, suggesting that the newly exposed skin layer is initially fully functional until the recolonization of the skin by the fungus again impedes cutaneous function. However, the temporary restoration of skin function during sloughing does not restore ionic homeostasis, and the underlying loss of ion uptake capacity is ultimately detrimental for amphibians with chytridiomycosis.

pH and Microbial Infections.

Maintenance of an acidic stratum corneum pH is a major component of the skin's protective system and creates a hostile environment for colonization with pathogenic microorganisms. This barrier can however be overcome on healthy and in particular on compromised skin. Mycosis, diaper/incontinence dermatitis and wound healing are examples of cases where microbial infection is promoted by the altered skin conditions or environment. Fungi have a complex system that senses ambient pH that leads to metabolic responses allowing adhesion, growth and invasion, as microbial metabolites further increase skin pH resulting in a clinically manifest infection (mycosis). Diabetic patients with a higher pH in intertriginous areas are particularly vulnerable to candidiasis. In diaper and incontinence dermatitis, the increase in skin pH and damage to the skin barrier function is triggered by the contact with urine and faeces with or without occlusion and maintained by host and microbial enzymes and metabolites. This leads to the reduction of the protective resident microflora and fungal overgrowth, mostly with Candida albicans. Skin care with slightly acidic products may help to prevent and treat this kind of dermatitis. Wound healing is a complex sequence of biologic events correlated with ambient pH, which influences the different phases of the healing process. The pH determines the appropriate activity of immune cells and key enzymes as well as biofilm formation. Chronic wounds emerging from the disruption of the healing process are characterized by a neutral to slightly alkaline pH and may benefit from wound pH monitoring and therapeutic acidification.

In vitro models of dermatophyte infection to investigate epidermal barrier alterations.

Fungal infections of the skin, known as dermatophytoses, are initiated at the epidermal barrier and lead to dysfunctions of the stratum corneum and cornified skin appendages. Dermatophytosis affects a significant part of the human population and, despite the availability of effective treatments, its prevalence is still increasing. Numerous dermatophyte species are able to induce lesions in both animals and humans, with different clinical pictures and host inflammatory responses. The understanding of the infectious process and of tissue responses has been impeded by discrepancies between observations in vivo or in research models. Indeed, cells cultured as monolayers do not undergo the keratinization process required to study the adherence and invasion of dermatophytes. Animal models lack relevance to study human dermatophytosis because of species-specific differences in the development of lesions and inflammatory responses. This review focuses on the recent development of cultured human skin equivalents, which partly overcomes those limitations and allows improved understanding of the pathogenesis of dermatophytosis in human being, especially the impacts of infection on epidermal barrier integrity.

Chytridiomycosis causes catastrophic organism-wide metabolic dysregulation including profound failure of cellular energy pathways.

Chytridiomycosis is among several recently emerged fungal diseases of wildlife that have caused decline or extinction of naïve populations. Despite recent advances in understanding pathogenesis, host response to infection remains poorly understood. Here we modelled a total of 162 metabolites across skin and liver tissues of 61 frogs from four populations (three long-exposed and one naïve to the fungus) of the Australian alpine tree frog (Litoria verreauxii alpina) throughout a longitudinal exposure experiment involving both infected and negative control individuals. We found that chytridiomycosis dramatically altered the organism-wide metabolism of clinically diseased frogs. Chytridiomycosis caused catastrophic failure of normal homeostatic mechanisms (interruption of biosynthetic and degradation metabolic pathways), and pronounced dysregulation of cellular energy metabolism. Key intermediates of the tricarboxylic acid cycle were markedly depleted, including in particular α-ketoglutarate and glutamate that together constitute a key nutrient pathway for immune processes. This study was the first to apply a non-targeted metabolomics approach to a fungal wildlife disease and specifically to dissect the host-pathogen interface of Bd-infected frogs. The patterns of metabolite accumulation we have identified reveal whole-body metabolic dysfunction induced by a fungal skin infection, and these findings have broad relevance for other fungal diseases.

Transcriptional profile of the human skin pathogenic fungus Mucor irregularis in response to low oxygen.

Mucormycosis is one of the most invasive mycosis and has caused global concern in public health. Cutaneous mucormycosis caused by Mucor irregularis (formerly Rhizomucor variabilis) is an emerging disease in China. To survive in the human body, M. irregularis must overcome the hypoxic (low oxygen) host microenvironment. However, the exact molecular mechanism of its pathogenicity and adaptation to low oxygen stress environment is relatively unexplored. In this study, we used Illumina HiSeq technology (RNA-Seq) to determine and compare the transcriptome profile of M. irregularis CBS103.93 under normal growth condition and hypoxic stress. Our analyses demonstrated a series of genes involved in TCA, glyoxylate cycle, pentose phosphate pathway, and GABA shunt were down-regulated under hypoxic condition, while certain genes in the lipid/fatty acid metabolism and endocytosis were up-regulated, indicating that lipid metabolism was more active under hypoxia. Comparing the data with other important human pathogenic fungi such as Aspergillus spp., we found that the gene expression pattern and metabolism in responses to hypoxia in M. irregularis were unique and different. We proposed that these metabolic changes can represent a species-specific hypoxic adaptation in M. irregularis, and we hypothesized that M. irregularis could use the intra-lipid pool and lipid secreted in the infection region, as an extracellular nutrient source to support its hypoxic growth. Characterizing the significant differential gene expression in this species could be beneficial to uncover their role in hypoxia adaptation and fungalpathogenesis and further facilitate the development of novel targets in disease diagnosis and treatment against mucormycosis.

White-nose syndrome increases torpid metabolic rate and evaporative water loss in hibernating bats.

Fungal diseases of wildlife typically manifest as superficial skin infections but can have devastating consequences for host physiology and survival. White-nose syndrome (WNS) is a fungal skin disease that has killed millions of hibernating bats in North America since 2007. Infection with the fungus Pseudogymnoascus destructans causes bats to rewarm too often during hibernation, but the cause of increased arousal rates remains unknown. On the basis of data from studies of captive and free-living bats, two mechanistic models have been proposed to explain disease processes in WNS. Key predictions of both models are that WNS-affected bats will show 1) higher metabolic rates during torpor (TMR) and 2) higher rates of evaporative water loss (EWL). We collected bats from a WNS-negative hibernaculum, inoculated one group with P. destructans, and sham-inoculated a second group as controls. After 4 mo of hibernation, TMR and EWL were measured using respirometry. Both predictions were supported, and our data suggest that infected bats were more affected by variation in ambient humidity than controls. Furthermore, disease severity, as indicated by the area of the wing with UV fluorescence, was positively correlated with EWL, but not TMR. Our results provide the first direct evidence that heightened energy expenditure during torpor and higher EWL independently contribute to WNS pathophysiology, with implications for the design of potential treatments for the disease.

Cutaneous presentation of disseminated histoplasmosis as a solitary peri-anal ulcer. Case report and discussion.

Disseminated histoplasmosis has a diverse and non-specific range of clinical signs and symptoms. In a significant minority of patients, cutaneous lesions are apparent at the time of initial presentation, affording an opportunity to establish the diagnosis from a skin biopsy. The most frequently reported clinical scenario in immunocompromised patients with cutaneous involvement is that of multiple papulo-nodular lesions on the face, trunk or extremities. The following report features an immunocompetent patient who presented with a solitary ulcerated plaque on the buttocks close to the anal verge. This case presentation underscores the broad spectrum of clinical presentations as well as the potential for diagnostic confusion with protozoa such as Leishmania or Trypanosoma species during histopathologic examination if special stains for fungal organisms are not performed.

Nano-Sized Technologies for Miconazole Skin Delivery.

Various nano-based strategies for increasing the efficiency of topical drugs have offered the potential advantage of miconazole skin delivery. Miconazole nitrate is an antifungal drug with a drawback of poor skin-penetration in the treatment of deep seated fungal skin infections. Drug entrapment in nanoparticles such as ethosome, liposomes, solid lipid nanoparticles (SLNs) and nano structured lipid carriers (NLCs) can facilitate localized drug delivery and remove the skin barriers for an efficient drug delivery. Different nano-formulations have been recently examined for the controlled release, retention and permeation enhancement of miconazole in skin. The present overview focuses on novel nano-based formulation approaches employed to improve miconazole penetration through skin for the treatment of fungal infections.

Advancements in Topical Antifungal Vehicles.

The primary treatment for superficial fungal infections is antifungal topical formulations, and allylamines and azoles represent the two major classes of topical formulations that are used to treat these infections. The stratum corneum (SC) is composed of keratinocytes that are surrounded by a matrix of lipids. The efficacy of topically applied formulations depends on their ability to penetrate this lipid matrix, and the vehicle plays an integral role in the penetration of active molecule into skin. There are several challenges to formulating topical drugs, which include the biotransformation of the active molecules as they pass through the SC and the physical changes that occur to the vehicle itself when it is applied to the skin. This article will review current and emerging topical antifungal vehicles.

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.

INDUCTION BY EPIDERMOPHYTON FLOCCOSUM OF HUMAN FIBROBLAST MATRIX METALLOPROTEINASE-9 SECRETION IN VITRO.

Skin infection from pathogenic dermatophyte, Epidermophytonfloccosum, can cause serious health complications, especially in immuno-compromised patients. Proteolytic enzymes secreted from E. floccosum are required for host tissue degradation, facilitating fungal invasion. However, little is known regarding host matrix metalloproteinase (MMP) expression during E. floccosum infection. In this study human foreskin fibroblast (HFF) cell line was used to determine MMP-9 protease activity by gelatin zymography and amount by ELISA. E. floccosum-induced HFF secretion of MMP-9 in a time dependent manner, but HFF cell viability decreased. Treatment with an MMP inhibitor (SB-3CT) caused reduction in E. floccosum-induced secreted MMP-9 and improvement in HFF cell viability. These findings indicate a possible control measure for protecting skin from E. floccosum infection.

Recent advances in topical formulation carriers of antifungal agents.

Fungal infections are amongst the most commonly encountered diseases affecting the skin. Treatment approaches include both topical and oral antifungal agents. The topical route is generally preferred due to the possible side effects of oral medication. Advances in the field of formulation may soon render outdated conventional products such as creams, ointments and gels. Several carrier systems loaded with antifungal drugs have demonstrated promising results in the treatment of skin fungal infections. Examples of these newer carriers include micelles, lipidic systems such as solid lipid nanoparticles and nanostructured lipid carriers, microemulsions and vesicular systems such as liposomes, niosomes, transfersomes, ethosomes, and penetration enhancer vesicles.

Could nanovesicles containing a penetration enhancer clinically improve the therapeutic outcome in skin fungal diseases?

AIM: To study whether the formulation of an antifungal drug in nanovesicular form containing skin penetration enhancer would clinically modulate its therapeutic effectiveness. MATERIALS & METHODS: Nanovesicles containing different skin penetration enhancers 'PEVs' were prepared and loaded with sertaconazole. Penetration-enhancer vesicles were characterized for entrapment efficiency, particle size, zeta potential, elasticity, viscosity, morphology and ex vivo skin deposition. Selected formulae were preliminary tested for clinical efficacy on patients suffering from tinea corporis and tinea versicolor. RESULTS & CONCLUSION: The nanosize of the vesicles, their content of penetration enhancer and their deformable nature are three cornerstones positively influencing the therapeutic outcome of topical antifungal therapy, and hence, can be considered a promising treatment modality for skin fungal diseases.

Glycerophospholipid Profiles of Bats with White-Nose Syndrome.

Pseudogymnoascus destructans is an ascomycetous fungus responsible for the disease dubbed white-nose syndrome (WNS) and massive mortalities of cave-dwelling bats. The fungus infects bat epidermal tissue, causing damage to integumentary cells and pilosebaceous units. Differences in epidermal lipid composition caused by P. destructans infection could have drastic consequences for a variety of physiological functions, including innate immune efficiency and water retention. While bat surface lipid and stratum corneum lipid composition have been described, the differences in epidermal lipid content between healthy tissue and P. destructans-infected tissue have not been documented. In this study, we analyzed the effect of wing damage from P. destructans infection on the epidermal polar lipid composition (glycerophospholipids [GPs] and sphingomyelin) of little brown bats (Myotis lucifugus). We hypothesized that infection would lead to lower levels of total lipid or higher oxidized lipid product proportions. Polar lipids from three damaged and three healthy wing samples were profiled by electrospray ionization tandem mass spectrometry. We found lower total broad lipid levels in damaged tissue, specifically ether-linked phospholipids, lysophospholipids, phosphatidylcholine, and phosphatidylethanolamine. Thirteen individual GP species from four broad GP classes were present in higher amounts in healthy tissue. Six unsaturated GP species were absent in damaged tissue. Our results confirm that P. destructans infection leads to altered lipid profiles. Clinical signs of WNS may include lower lipid levels and lower proportions of unsaturated lipids due to cellular and glandular damage.

Topical delivery of drugs for the effective treatment of fungal infections of skin.

The prevalence of fungal infections of skin has increased rapidly, affecting approximately 40 million people across the globe. A wide variety of antifungal drugs has been utilized in the effective management of numerous dermatological infections. Topical treatment of fungal infections has proved to be quite advantageous due to various factors like targeting the site of infection, minimizing systemic side effects, enhanced efficacy of treatment, and improved patient compliance. In spite the fact that these agents are therapeutically active on topical application, these have restricted drug delivery across the skin resulting in insufficient therapeutic index and may exert local as well as systemic side effects. The accomplishment of topical drug delivery needs to pacify two anomalous aspects, first the barrier nature of stratum corneum, and second, deposition of drug within the skin should be ideally achieved with limited percutaneous absorption. Thus, to facilitate the delivery of antifungal drugs and improve the treatment aspects, various novel delivery carriers have been developed. This article attempts to provide an in-depth knowledge of nanoparticulate and vesicular carriers. This article focuses on the different aspects of fungal infections and their effective treatment with antifungal drugs. Efficacy of various carrier systems (nanoparticulate and vesicular carriers) in delivering antifungal drugs topically has also been discussed. Besides, compiling various research reports, this article also includes formulation considerations inclusive of regulatory aspects of excipients used, the mechanisms of penetration, and patents reported.