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Pulmonary surfactant, the primary substance lining the epithelium of the human Lower Respiratory Tract (LRT), is rich in lipids, with dipalmitoyl-phosphatidylcholine (DPPC) being the most abundant. Although surfactants are known to have antifungal activity against some yeast species, the significant presence of species like Malassezia restricta in the lung mycobiome suggests that these yeasts may exhibit some level of lipo-tolerance or even lipo-affinity for pulmonary lipids. This study explored the affinity and tolerance of yeasts, identified as significant members of the lung microbiome, to pulmonary lipids through culture-based methods. Eleven species from the genera Malassezia, Candida (including the new genera Nakaseomyces and Meyerozyma), and Cryptococcus were tested for their growth on media containing pulmonary lipids such as DPPC and commercial porcine surfactant and in other culture medium that contain non-pulmonary lipids such as glycerol monostearate and tweens. The yeasts' lipo-affinity or lipo-tolerance was assessed based on their growth on these lipids compared to standard media, specifically Modified Leeming Notman Agar (MLNA) for Malassezia species and Sabouraud Dextrose Agar (SDA) for the other genera. The addition of DPPC or surfactant to the media enhanced the growth of most Malassezia yeasts and some Cryptococcus species. C. parapsilosis, Meyerozyma guilliermondii and Cryptococcus neoformans s.s. showed similar growth to that on the standard media, while the other yeasts primarily demonstrated lipo-tolerance without lipo-affinity for these compounds. To our knowledge, this is the first report on the influence of pulmonary lipids on the in vitro growth of Malassezia spp. and other yeast members of the lung mycobiome. Some yeasts, such as Malassezia restricta, commonly found in the lower respiratory tract (LRT), exhibit specific affinity for lung lipids like DPPC and commercial porcine surfactant. This finding suggests that lung lipids may play a significant role in shaping the LRT mycobiome., Competing Interests: Declarations. Conflict of interest: None., (© 2024. The Author(s).)

During mammalian colonization and infection, microorganisms must be able to rapidly sense and adapt to changing environmental conditions including alterations in extracellular pH. The fungus-specific Rim/Pal signaling pathway is one process that supports microbial adaptation to alkaline pH. This cascading series of interacting proteins terminates in the proteolytic activation of the highly conserved Rim101/PacC protein, a transcription factor that mediates microbial responses that favor survival in neutral/alkaline pH growth conditions, including many mammalian tissues. We identified the putative Rim pathway proteins Rim101 and Rra1 in the human skin colonizing fungus Malassezia sympodialis . Gene deletion by transconjugation and homologous recombination revealed that Rim101 and Rra1 are required for M. sympodialis growth at higher pH. In addition, comparative transcriptional analysis of the mutant strains compared to wild-type suggested mechanisms for fungal adaptation to alkaline conditions. These pH-sensing signaling proteins are required for optimal growth in a murine model of atopic dermatitis, a pathological condition associated with increased skin pH. Together, these data elucidate both conserved and phylum-specific features of microbial adaptation to extracellular stresses.IMPORTANCEThe ability to adapt to host pH has been previously associated with microbial virulence in several pathogenic fungal species. Here we demonstrate that a fungal-specific alkaline response pathway is conserved in the human skin commensal fungus Malassezia sympodialis ( Ms ). This pathway is characterized by the pH-dependent activation of the Rim101/PacC transcription factor that controls cell surface adaptations to changing environmental conditions. By disrupting genes encoding two predicted components of this pathway, we demonstrated that the Rim/Pal pathway is conserved in this fungal species as a facilitator of alkaline pH growth. Moreover, targeted gene mutation and comparative transcriptional analysis support the role of the Ms Rra1 protein as a cell surface pH sensor conserved within the basidiomycete fungi, a group including plant and human pathogens. Using an animal model of atopic dermatitis, we demonstrate the importance of Ms Rim/Pal signaling in this common inflammatory condition characterized by increased skin pH., Competing Interests: The authors declare no conflict of interest.

Malassezia species are commensal and opportunistic fungi found in human skin. All Malassezia species lack fatty acid synthesis genes and survive by utilizing several lipases to degrade and absorb fatty acids from external lipid sources, but little research has been done on their optimal active pH and temperature. Our skin protects itself from external stimuli and maintains homeostasis, involving bacteria and fungi such as Malassezia species that inhabit our skin. Hence, dysbiosis in the skin microbiome can lead to various skin diseases. The skin's pH is slightly acidic compared to neutral, and changes in pH can affect the metabolism of Malassezia species. We used keratinocyte cell lines to determine the effect of lipids bio-converted by Malassezia furfur, Malassezia japonica, and Malassezia yamatoensis under pH conditions similar to those of healthy skin. Lipids bio-converted from Malassezia species were associated with the regulation of transcripts related to inflammation, moisturizing, and promoting elasticity. Therefore, to determine the effect of pH on lipid metabolism in M. furfur, which is associated with seborrheic dermatitis, changes in biomass, lipid content, and fatty acid composition were determined. The results showed that pH 7 resulted in low growth and reduced lipid content, which had a negative impact on skin health. Given that bio-converted Malassezia-derived lipids show positive effects at the slightly acidic pH typical of healthy skin, it is important to study their effects on skin cells under various pH conditions. KEY POINTS: • pH 6, Malassezia spp. bio-converted lipid have a positive effect on skin cells • Malassezia spp. have different lipid, fatty acid, and growth depending on pH • Malassezia spp. can play a beneficial role by secreting lipids to the outside., (© 2024. The Author(s).)

Malassezia globosa is abundant and prevalent on sebaceous areas of the human skin. Genome annotation reveals that M. globosa possesses a repertoire of secreted hydrolytic enzymes relevant for lipid and protein metabolism. However, the functional significance of these enzymes is uncertain and presence of these genes in the genome does not always translate to expression at the cutaneous surface. In this study we utilized targeted RNA sequencing from samples isolated directly from the skin to quantify gene expression of M. globosa secreted proteases, lipases, phospholipases and sphingomyelinases. Our findings indicate that the expression of these enzymes is dynamically regulated by the environment in which the fungus resides, as different growth phases of the planktonic culture of M. globosa show distinct expression levels. Furthermore, we observed significant differences in the expression of these enzymes in culture compared to healthy sebaceous skin sites. By examining the in situ gene expression of M. globosa's secreted hydrolases, we identified a predicted aspartyl protease, MGL_3331, which is highly expressed on both healthy and disease-affected dermatological sites. However, molecular modeling and biochemical studies revealed that this protein has a non-canonical active site motif and lacks measurable proteolytic activity. This pseudoprotease MGL_3331 elicits a heightened IgE-reactivity in blood plasma isolated from patients with atopic dermatitis compared to healthy individuals and invokes a pro-inflammatory response in peripheral blood mononuclear cells. Overall, our study highlights the importance of studying fungal proteins expressed in physiologically relevant environments and underscores the notion that secreted inactive enzymes may have important functions in influencing host immunity., Competing Interests: Declaration of competing interest Conflict of Interest Statement for “A Malassezia pseudoprotease dominates the secreted hydrolase landscape and is a potential allergen on skin”. All authors declare no conflict of interest., (Copyright © 2023 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.)

Introduction: Malassezia is a major component of the skin microbiome, a lipophilic symbiotic organism of the mammalian skin, which can switch to opportunistic pathogens triggering multiple dermatological disorders in humans and animals. This phenomenon is favored by endogenous and exogenous host predisposing factors, which may switch Malassezia from a commensal to a pathogenic phenotype., Area Covered: This review summarizes and discusses the most recent literature on the pathogenesis of Malassezia yeasts, which ultimately results in skin disorders with different clinical presentation. A literature search of Malassezia pathogenesis was performed via PubMed and Google scholar (up to May 2023), using the following keywords: Pathogenesis and Malassezi a;host risk factors and Malassezia , Malassezia and skin disorders; Malassezia and virulence factors: Malassezia and metabolite production; Immunology and Malassezia ., Expert Opinion: Malassezia yeasts can maintain skin homeostasis being part of the cutaneous mycobiota; however, when the environmental or host conditions change, these yeasts are endowed with a remarkable plasticity and adaptation by modifying their metabolism and thus contributing to the appearance or aggravation of human and animal skin disorders.

In spite of the increasing medical interest in Malassezia yeasts, the virulence factors of Malassezia furfur causing bloodstream infections (BSI) were never investigated. Therefore, phospholipase (Pz), lipase (Lz), hemolysin (Hz), biofilm production, and in vitro antifungal susceptibility profiles were evaluated in M. furfur strains, isolated from both pityriasis versicolor (PV) patients (n = 18; Group 1) or from preterm infants BSI (n = 21; Group 2). All the test stains exhibited Pz activity, whereas 92.3% and 97.4% of strains exhibited Lz and Hz activities, respectively. Pz, Lz, and Hz activities were higher (i.e., lower values) within Group 1 strains (i.e., 0.48, 0.40, and 0.77) than those within Group 2 (i.e., 0.54, 0.54, and 0.81). The biofilm production was higher within Malassezia isolates from Group 2 (0.95 ± 0.3) than from Group 1 (0.72 ± 0.4). Itraconazole and posaconazole were the most active drugs against M. furfur, followed by amphotericin B and fluconazole. The minimum inhibitory concentrations (MIC) values varied according to the origin of M. furfur strains being statistically lower in M. furfur from Group 1 than from Group 2. This study suggests that M. furfur strains produce hydrolytic enzymes and biofilm when causing PV and BSI. Data show that the phospholipase activity, biofilm production, and a reduced antifungal susceptibility profile might favor M. furfur BSI, whereas lipase and hemolytic activities might display a synergic role in skin infection., (© The Author(s) 2023. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology.)

Background: Microbiotas affected the prognosis of cancer patients by regulating programmed death ligand-1 (PD-L1) expression. However, the relationship between gastric fungi and PD-L1 expression is still unclear in gastric cancer (GC). We aimed at exploring the association of gastric fungi with PD-L1 expression and overall survival in GC., Methods: A total of 61 GC patients were divided into the two groups based on the PD-L1 combined positive scores (CPS). Fungal profiling was performed by internal transcribed spacer rDNA sequencing, and the survival analyses were performed by Kaplan-Meier curves., Results: We observed a taxonomic difference of fungi between the PD-L1-High ( CPS ≥ 10) and PD-L1-Low group ( CPS < 10) by principal coordinates analysis (PCoA) ( P = 0.014 for Bray-Curtis and P = 0.042 for Jaccard). Malassezia had a higher abundance in the PD-L1-High group compared to the PD-L1-Low group ( P = 0.045). Malassezia globosa elevated significantly in the PD-L1-High group. GC patients with PD-L1 low expression and low abundance of Malassezia globosa had a longer overall survival (OS) than others ( P = 0.047). Malassezia globosa was associated with PD-L1 expression ( Odds   Ratio = 3.509, 95% Confidence Interval: 1.056-11.656, P = 0.040). Malassezia globosa was associated with the tumor size ( P = 0.031) and PD-L1 status ( P = 0.024). GC patients with a high abundance of Malassezia globosa had shorter OS than others ( P = 0.028). Malassezia globosa was an independent factor ( Hazard   Ratio = 3.080, 95% Confidence Interval: 1.140-8.323, P = 0.027) for OS after adjusting for tumor stage. Malassezia globosa was figured out to be associated with- fatty acid and lipid biosynthesis and degradation via LIPASYN pathway. Conclusions. Malassezia globosa was identified as a PD-L1 expression-associated gastric fungus and associated with OS of GC patients, which calls for more studies to further explore its potential in PD-L1/PD-1 targeted immunotherapy., Competing Interests: The authors declare no potential conflicts of interest., (Copyright © 2022 Zhenzhan Zhang et al.)

Superficial fungal infections are common in dermatology and are often caused by opportunistic species in the Candida and Malassezia genera. The aim of this study was to analyze changes in the expression of genes coding for enzymes involved in the biosynthesis of glycosaminoglycans (GAGs) chains following the adherence of Candida and Malassezia yeasts to skin cell lines. Gene expression was analyzed using reverse transcriptase-quantitative polymerase chain reaction assays. Interactions between the yeasts and the skin cells induced the following changes in genes involved in the biosynthesis of heparan sulfate and chondroitin sulfate: downregulation of CHPF in keratinocytes and downregulation of EXT1, EXT2, CHSY3, and CHPF in fibroblasts. Adherence to fibroblasts had an even greater effect on GAG biosynthetic enzymes, inducing the downregulation of 13 genes and the upregulation of two (CHST15 and CHST7). Interactions between yeasts and skin cells might affect the binding affinity of GAG chains, possibly changing their ability to function as receptors for pathogens and interfering with a key stage at the start of infection., (Copyright © 2022 AEDV. Publicado por Elsevier España, S.L.U. All rights reserved.)

Background: Microorganisms synthesize and release a large diversity of small molecules like volatile compounds, which allow them to relate and interact with their environment. Volatile organic compounds (VOCs) are carbon-based compounds with low molecular weight and generally, high vapor pressure; because of their nature, they spread easily in the environment. Little is known about the role of VOCs in the interaction processes, and less is known about VOCs produced by Malassezia, a genus of yeasts that belongs to the human skin mycobiota. These yeasts have been associated with several dermatological diseases and currently, they are considered as emerging opportunistic yeasts. Research about secondary metabolites of these yeasts is limited. The pathogenic role and the molecular mechanisms involved in the infection processes of this genus are yet to be clarified. VOCs produced by Malassezia yeasts could play an important function in their metabolism; in addition, they might be involved in either beneficial or pathogenic host-interaction processes. Since these yeasts present differences in their nutritional requirements, like lipids to grow, it is possible that these variations of growth requirements also define differences in the volatile organic compounds produced in Malassezia species., Aim of Review: We present a mini review about VOCs produced by microorganisms and Malassezia species, and hypothesize about their role in its metabolism, which would reveal clues about host-pathogen interaction., Key Scientific Concepts of Review: Since living organisms inhabit a similar environment, the interaction processes occur naturally; as a result, a signal and a response from participants of these processes become important in understanding several biological behaviors. The efforts to elucidate how living organisms interact has been studied from several perspectives. An important issue is that VOCs released by the microbiota plays a key role in the setup of relationships between living micro and macro organisms. The challenge is to determine what is the role of these VOCs produced by human microbiota in commensal/pathogenic scenarios, and how these allow understanding the species metabolism. Malassezia is part of the human mycobiota, and it is implicated in commensal and pathogenic processes. It is possible that their VOCs are involved in these behavioral changes, but the knowledge about this remains overlocked. For this reason, VOCs produced by microorganisms and Malassezia spp. and their role in several biological processes are the main topic in this review.

Chlorogenic acid (CHA) and gallic acid (GA) are safe natural phenolic compounds that are used as enhancers of some drugs in influencing antioxidant, anticancer, and antibacterial activities. Among fungi, Candida spp. and Malassezia spp. are characterized by an increasing prevalence of multidrug resistance phenomena and by a high morbidity and mortality of their infections. No data are available about the efficacy of CHA and GA combined with azoles on the antifungal susceptibility and on the virulence of both fungi. Therefore, their antifungal and antivirulence effects have been tested in combination with fluconazole (FLZ) or ketoconazole (KTZ) on 23 Candida spp. and 8 M. furfur isolates. Broth microdilution chequerboard, time-kill studies, and extracellular enzymes (phospholipase and hemolytic) activities were evaluated, displaying a synergistic antifungal action between CHA or GA and FLZ or KTZ on C. albicans, C. bovina, and C. parapsilosis, and antagonistic antifungal effects on M. furfur and Pichia kudriavzevii (Candida krusei) isolates. The time-kill studies confirmed the chequerboard findings, showing fungicidal inhibitory effect only when the GA was combined with azoles on Candida strains. However, the combination of phenolics with azoles had no effect on the virulence of the tested isolates. Our study indicates that the combination between natural products and conventional drugs could be an efficient strategy for combating azole resistance and for controlling fungistatic effects of azole drugs., (© The Author(s) 2020. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology.)

The skin of humans and animals is colonized by commensal and pathogenic fungi and bacteria that share this ecological niche and have established microbial interactions. Malassezia are the most abundant fungal skin inhabitant of warm-blooded animals and have been implicated in skin diseases and systemic disorders, including Crohn's disease and pancreatic cancer. Flavohemoglobin is a key enzyme involved in microbial nitrosative stress resistance and nitric oxide degradation. Comparative genomics and phylogenetic analyses within the Malassezia genus revealed that flavohemoglobin-encoding genes were acquired through independent horizontal gene transfer events from different donor bacteria that are part of the mammalian microbiome. Through targeted gene deletion and functional complementation in Malassezia sympodialis , we demonstrated that bacterially derived flavohemoglobins are cytoplasmic proteins required for nitric oxide detoxification and nitrosative stress resistance under aerobic conditions. RNA-sequencing analysis revealed that endogenous accumulation of nitric oxide resulted in up-regulation of genes involved in stress response and down-regulation of the MalaS7 allergen-encoding genes. Solution of the high-resolution X-ray crystal structure of Malassezia flavohemoglobin revealed features conserved with both bacterial and fungal flavohemoglobins. In vivo pathogenesis is independent of Malassezia flavohemoglobin. Lastly, we identified an additional 30 genus- and species-specific horizontal gene transfer candidates that might have contributed to the evolution of this genus as the most common inhabitants of animal skin., Competing Interests: The authors declare no competing interest.

Malassezia is a lipophilic cutaneous commensal yeast and associated with various skin disorders. The yeast also causes bloodstream infection via intravascular catheters and can be detected even in human gut microbiota. Ambient pH is one of the major factors that affect the physiology and metabolism of several pathogenic microorganisms. Although dynamic changes of pH environment in different parts of the body is a great challenge for Malassezia to confront, the role that ambient pH plays in Malassezia is largely unknown. In this study, we investigated the impact of ambient pH on physiology and expression of lipases in M. furfur grown under different pH conditions. The yeast was able to grow in media ranging from pH 4 to 10 without morphological alteration. Elevation in pH value enhanced the extracellular lipase activity but decreased that of intracellular lipase. The qPCR results revealed that a set of functional lipase genes, LIP3-6 , were constitutively expressed regardless of pH conditions or exposure time. Based on the data, we conclude that the external pH plays a promotional role in the secretion of lipases but exerts less effect on transcription of the genes and morphology in M. furfur .

Extracellular vesicles (EVs) released from fungi have been shown to participate in inter-organismal communication and in cross-kingdom modulation of host defense. Malassezia species are the dominant commensal fungal members of the human skin microbiota. We have previously found that Malassezia sympodialis releases EVs. These EVs, designated MalaEx, carry M. sympodialis allergens and induce a different inflammatory cytokine response in peripheral blood mononuclear cells (PBMC) from patients with atopic dermatitis compared to healthy controls. In this study, we explored the host-microbe interaction between MalaEx and human keratinocytes with the hypothesis that MalaEx might be able to activate human keratinocytes to express the intercellular adhesion molecule-1 (ICAM-1, CD54). MalaEx were prepared from M. sympodialis (ATCC 42132) culture supernatants by a combination of centrifugation, filtration and serial ultracentrifugation. The MalaEx showed a size range of 70-580 nm with a mean of 154 nm using nanoparticle tracking analysis. MalaEx were found to induce a significant up-regulation of ICAM-1 expression on primary human keratinocytes isolated from human ex vivo skin ( p = 0.026, n = 3), compared to the unstimulated keratinocytes. ICAM-1 is a counter ligand for the leukocyte integrins lymphocyte function-associated antigen-1 (LFA-1) and macrophage-1 antigen (Mac-1), of which induced expression on epithelial cells leads to the attraction of immune competent cells. Thus, the capacity of MalaEx to activate keratinocytes with an enhanced ICAM-1 expression indicates an important step in the cutaneous defense against M. sympodialis . How this modulation of host cells by a fungus is balanced between the commensal, pathogenic, or beneficial states on the skin in the interplay with the host needs to be further elucidated., (Copyright © 2020 Vallhov, Johansson, Veerman and Scheynius.)

Malassezia furfur isolates from diseased skin preferentially biosynthesize compounds which are among the most active known aryl-hydrocarbon receptor (AhR) inducers, such as indirubin, tryptanthrin, indolo[3,2- b ]carbazole, and 6-formylindolo[3,2- b ]carbazole. In our effort to study their production from Malassezia spp., we investigated the role of indole-3-carbaldehyde (I3A), the most abundant metabolite of Malassezia when grown on tryptophan agar, as a possible starting material for the biosynthesis of the alkaloids. Treatment of I3A with H 2 O 2 and use of catalysts like diphenyldiselenide resulted in the simultaneous one-step transformation of I3A to indirubin and tryptanthrin in good yields. The same reaction was first applied on simple indole and then on substituted indoles and indole-3-carbaldehydes, leading to a series of mono- and bisubstituted indirubins and tryptanthrins bearing halogens, alkyl, or carbomethoxy groups. Afterward, they were evaluated for their AhR agonist activity in recombinant human and mouse hepatoma cell lines containing a stably transfected AhR-response luciferase reporter gene. Among them, 3,9-dibromotryptanthrin was found to be equipotent to 2,3,7,8-tetrachlorodibenzo- p -dioxin (TCDD) as an AhR agonist, and 3-bromotryptanthrin was 10-times more potent than TCDD in the human HG2L7.5c1 cell line. In contrast, 3,9-dibromotryptanthrin and 3-bromotryptanthrin were ∼4000 and >10,000 times less potent than TCDD in the mouse H1L7.5c3 cell line, respectively, demonstrating that they are species-specific AhR agonists. Involvement of the AhR in the action of 3-bromotryptanthrin was confirmed by the ability of the AhR antagonists CH223191 and SR1 to inhibit 3-bromotryptanthrin-dependent reporter gene induction in human HG2L7.5c1 cells. In conclusion, I3A can be the starting material used by Malassezia for the production of both indirubin and tryptanthrin through an oxidation mechanism, and modification of these compounds can produce some highly potent, efficacious and species-selective AhR agonists.

Seborrhoeic Dermatitis (SD) is a very common chronic and/or relapsing inflammatory skin disorder whose pathophysiology remains poorly understood. Yeast of the genus Malassezia has long been regarded as a main predisposing factor, even though causal relationship has not been firmly established. Additional predisposing factors have been described, including sebaceous activity, host immunity (especially HIV infection), epidermal barrier integrity, skin microbiota, endocrine and neurologic factors, and environmental influences. Genetic studies in humans and mouse models-with particularly interesting insights from examining the Mpzl3 knockout mice and their SD-like skin phenotype, and patients carrying a ZNF750 mutation-highlight defects in host immunity, epidermal barrier and sebaceous activity. After synthesizing key evidence from the literature, we propose that intrinsic host factors, such as changes in the amount or composition of sebum and/or defective epidermal barrier, rather than Malassezia, may form the basis of SD pathobiology. We argue that these intrinsic changes provide favourable conditions for the commensal Malassezia to over-colonize and elicit host inflammatory response. Aberrant host immune activity or failure to clear skin microbes may bypass the initial epidermal or sebaceous abnormalities. We delineate specific future clinical investigations, complemented by studies in suitable SD animal models, that dissect the roles of different epidermal compartments and immune components as well as their crosstalk and interactions with the skin microbiota during the process of SD. This research perspective beyond the conventional Malassezia-centric view of SD pathogenesis is expected to enable the development of better therapeutic interventions for the management of recurrent SD., (© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Malassezia pachydermatis causes infections of the skin and mucous membranes, especially in individuals with metabolic, hormonal, and immunological disorders. The search for M. pachydermatis properties that differentiate isolates from healthy and infected animals may result in the identification of typically commensal and potentially pathogenic strains within the entire species. We aimed to determine and compare protein profiles of M. pachydermatis strains isolated from 30 dogs with clinical symptoms of otitis externa and 34 dogs without symptoms of any disease. Two-dimensional gel electrophoresis was applied, and proteins distinguishing the two groups of strains were identified by liquid chromatography coupled with tandem mass spectrometry. Significant differences were found between potentially pathogenic and commensal isolates. The most significant finding was the presence of nicotinamide adenine dinucleotide phosphate (NADP)-dependent mannitol dehydrogenase and ketol-acid reductoisomerase among M. pachydermatis strains obtained from dogs with otitis externa. Nevertheless, it is not clear whether they are associated directly with the pathogenicity or they play the role of fungal allergen. On the basis of these findings, we can conclude that there may be two distinct groups of M. pachydermatis strains-one typically commensal and the other with properties that enhance the infection process. These results may be used for more precise diagnosis and identification of potentially pathogenic strains in the future.

Background: Malassezia yeasts produce bioactive indolic substances when grown on L-tryptophan agar. A panel of these substances was tested against commensal and opportunistic fungi, the Minimum Inhibitory Concentration (MIC) was determined and the potential for in loco antifungal activity on the skin was assessed., Materials and Methods: Eight indoles were included (malassezin, pityriacitrin, indirubin, indolo[3,2-b]carbazole, 6-formylindolo[3,2-b]carbazole, tryptanthrin, 6-hydroxymethylindolo[3,2-b]carbazole and 6-methylindolo[3,2-b]carbazole) and were tested against 40 fungal strains [yeasts: Malassezia spp.(N = 9); Cryptococcus spp.(N = 10); Candida spp.(N = 7); Yarrowia lipolytica(N = 1); Exophialla dermatitidis (N = 2); moulds: Aspergillus spp.(N = 7); Fusarium spp.(N = 2); Rhizopus oryzae(N = 2)]. The concentration of 5/8 of the tested indoles on diseased skin was calculated from published data. Kruskal-Wallis and Mann-Whitney U tests were employed for group susceptibility evaluation in 33 strains., Results: The MIC range was 0.125-32 μg/mL, and the median log 2 MIC was four. Indirubin was the most potent antifungal agent and differed significantly from the others. The highest median MIC was found for FICZ. Malassezia with Candida strains were more susceptible compared to Cryptococcus and Aspergillus, and this inhibitory activity was predicted to be valid also on human skin., Conclusions: Malassezia yeasts produce indolic species that inhibit an array of clinically significant yeasts and moulds., (© 2019 Blackwell Verlag GmbH.)

Mincle is a C-type lectin receptor of the innate immune system with the ability to sense pathogens and commensals through lipidic metabolites. While a growing number of bacterial glycolipids have been discovered that can signal through human Mincle, no fungal metabolites are known that can signal through the human form of this receptor. We report the total synthesis of a complex β-1,2-mannosyloxymannitol glycolipid from Malassezia pachydermatis 44-2, which was reported to signal through the murine Mincle receptor. Assembly of 44-2 was achieved through a highly convergent route that exploits symmetry elements inherent within this molecule and delineation of conditions that maintain the delicate l-mannitol triester-triol array. We show that 44-2 is a potent agonist of human Mincle signaling and constitutes the first fungal metabolite identified that can signal through the human Mincle receptor, providing new insights into antifungal immunity.

Aim: Immunofluorescence microscopy is a powerful technique to detect surface antigens and study their distribution. Analysis of fungi is often hampered by their weak adherence to glass. We therefore established a novel immunofluorescence staining method to overcome this problem., Materials & Methods: Fungal material from colonies is bound to adhesive tape and stained with antibodies., Results: The obtained samples had very good optical quality, showing low unspecific background staining and allowing analysis by confocal laser scanning microscopy. We have exemplified applying the new method to study the distribution of galactomannan on conidiophores of Aspergillus fumigatus and of β-glucans on Malassezia pachydermatis., Conclusion: Tape mount immunostaining facilitates analysis of fungal surface molecules and provides a base for expeditious diagnostic procedures.

Malassezia furfur is part of the human skin microbiota. Its volatile organic compounds (VOCs) possibly contribute to the characteristic odour in humans, as well as to microbiota interaction. The aim of this study was to investigate how the lipid composition of the liquid medium influences the production of VOCs. Growth was performed in four media: (1) mDixon, (2) oleic acid (OA), (3) oleic acid + palmitic acid (OA+PA), and (4) palmitic acid (PA). The profiles of the VOCs were characterized by HS-SPME/GC-MS in the exponential and stationary phases. A total number of 61 VOCs was found in M. furfur , among which alkanes, alcohols, ketones, and furanic compounds were the most abundant. Some compounds previously reported for Malassezia (γ-dodecalactone, 3-methylbutan-1-ol, and hexan-1-ol) were also found. Through our experiments, using univariate and multivariate unsupervised (Hierarchical Cluster Analysis (HCA) and Principal Component Analysis (PCA)) and supervised (Projection to Latent Structures Discriminant Analysis (PLS-DA)) statistical techniques, we have proven that each tested growth medium stimulates the production of a different volatiles profile in M. furfur . Carbon dioxide, hexan-1-ol, pentyl acetate, isomer5 of methyldecane, dimethyl sulphide, undec-5-ene, isomer2 of methylundecane, isomer1 of methyldecane, and 2-methyltetrahydrofuran were established as differentiating compounds among treatments by all the techniques. The significance of our findings deserves future research to investigate if certain volatile profiles could be related to the beneficial or pathogenic role of this yeast.

Malassezia are lipophilic and commensal yeasts capable of inducing skin disease among susceptible hosts. However, severely immunocompromised patients and preterm infants admitted to intensive care units are particularly at risk of developing Malassezia systemic infections. Patients often have central venous catheters which are usually the portal of entry for colonization and infection. In addition to the clinically non-specific findings, a delay in the laboratorial diagnosis may occur as there is often the need to add lipid supplementation to culture in order to support these organisms' growth. Herein, we report three unrelated cases of Malassezia bloodstream infection at a university hospital during a 2-year period, followed by a discussion of the clinical results and comparison with the most recently available published data on epidemiology and risk factors, pathogenesis, diagnosis, susceptibility profile and treatment., (© 2018 Japanese Dermatological Association.)

Background: As prednisone and ciclosporin can have immunosuppressive effects and have been considered potential predisposing factors for skin infections, we investigated the impact of these drugs on the diversity of the cutaneous microbiota, the abundance of Malassezia and infection with Papillomaviruses., Results: Six atopic, asymptomatic Maltese-beagle dogs were treated with ciclosporin for one month and then with prednisone for another month, with a one-month wash-out between treatments. The dogs were sampled on the abdomen and pinna before and after each treatment using a swab. Samples for Papillomavirus detection were obtained with cytobrush sticks. The bacterial microbiota was characterized using 16S amplicon high-throughput sequencing. Malassezia populations were quantified with nested real-time PCR targeting the ribosomal internal transcribed spacer 1. The diversity and composition of cutaneous microbiota was not impacted in a detectable manner by any of the treatments. As observed for the bacterial microbiota, Malassezia populations were not affected by treatment. Three dogs were positive for Papillomavirus at more than one timepoint, but an association with treatment was not apparent., Conclusions: Ciclosporin and prednisone at doses used for the treatment of atopic dermatitis do not impact the canine cutaneous microbiota in a detectable manner.

Dandruff is a scalp disorder characterized by flaking skin and itch of an excessive oily scalp skin. It affects 55% of the global youth and adult population. Seborrheic dermatitis is a similar scalp skin disorder with aggravated itchy rashes and flaking. Different factors are identified in the dandruff development: increased sebum production, uncontrolled fungal growth of Malassezia strains and individual reaction to pro-inflammatory environment, and the susceptibility to trigger an immunological response. Using in vitro and ex vivo models, we show that an Epilobium angustifolium extract dose dependently reduces lipid synthesis in sebocytes to a maximum of -43% (1% extract), and protects the epidermis from Malassezia -induced morphological changes. Epilobium angustifolium extract also acts through innovative mechanisms involving regulations of defensins (human beta-defensins [hBD2] and hBD3) and toll-like receptor 2 involved in the immunological response of the skin. The anti-dandruff and sebum-regulating efficacy of E. angustifolium extract (1.5%) was confirmed in a clinical study that mobilized 24 volunteers with dandruff and greasy scalp for 30 days. At the end of the study, nonadherent and adherent dandruffs were significantly ( p < 0.0001) reduced in average by -54% and -48%, respectively. Using Sebumeter® measurements, scalp sebum production was inhibited by -67% ( p < 0.0001) in average over baseline. In conclusion, E. angustifolium extract offers a new innovative approach to dandruff reduction through immunomodulation of the skin response to Malassezia invasion.

Background: Lithium succinate and gluconate are effective alternative options licensed for the topical treatment of seborrhoeic dermatitis (SD)., Objective: Their mode of action is not fully elucidated. Minimal inhibitory concentrations against Malassezia (M.) yeasts, which play an important role in SD, are very high., Methods: An assay based on the hydrolysis of ethyl octanoate enables us to test the hydrolytic activity of reference strains of the species M. globosa, M. sympodialis and M. furfur solely without interference by fungal growth as the free octanoic acid generated has antifungal activity., Results: In this assay the presence of alkali salts (lithium, sodium and potassium succinate resp.) in concentrations of 2%, 4% and 8% does not influence hydrolytic activity but the availability of the generated free fatty acid in a dose-dependent manner which was analysed by means of high-performance thin layer chromatography and densitometry. This was best effected with the lithium, followed by the sodium and only to a low degree by the potassium salt. As shown by attenuated total reflection Fourier transform infrared spectroscopy the free fatty acid reacted to the respective alkali soap and precipitate from solution. The alkali soaps could not be utilized by the M. spp. as shown in a modified Tween auxanogram and in lack of fungal growth by ethyl oleate in the presence of 8% lithium succinate., Conclusion: The effect of lithium succinate on growth of M. yeasts and presumably in SD can be explained by a precipitation of free fatty acids as alkali soaps limiting their availability for the growth of these lipid-dependent yeasts., (© 2016 European Academy of Dermatology and Venereology.)

Malassezia pachydermatis is a yeast belonging to the microbiota of the skin and mucous membranes of dog and cat, but it can also act as pathogen, causing dermatitis. The aim of this work was to evaluate the genetic variability of M. pachydermatis strains isolated from symptomatic dogs and cats and determine a correlation between genotype and phenotype. For this purpose eleven strains of M. pachydermatis were molecularly classified by nested-polymerase chain reaction (nested-PCR) based on ITS-1 and ITS-2 regions, specific for fungal rRNA genes. Furthermore, random amplification of polymorphic DNA (RAPD) was applied for genetic typing of M. pachydermatis isolates identifying four different genotypes. Strains belonging to genotype 1 produced the highest amount of biofilm and phospholipase activity. The inflammatory response induced by M. pachydermatis strains in immortalized human keratinocytes (HaCat cells) was significantly different when we compared the results obtained from each strain. In particular, HaCat cells infected with the strains belonging to genotypes 1 and 2 triggered the highest levels of increase in TLR-2, IL-1β, IL-6, IL-8, COX-2 and MMP-9 expression. By contrast, cells infected with the strains of genotype 3 and those of genotype 4 did not significantly induce TLR-2 and cytokines. The results obtained might suggest a possible association between genotype and virulence factors expressed by M. pachydermatis strains. This highlights the need for a more accurate identification of the yeast to improve the therapeutic approach and to monitor the onset of human infections caused by this emergent zoonotic pathogen.

Malassezia globosa, which is associated with skin conditions such as dandruff and seborrhoeic dermatitis, possesses 13 secreted lipases, but only MgLip1, MgMDL2 and MgLip2 have been characterized. To understand the substrate preferences of these lipases and by extension their potential role in colonizing human skin, we expressed all 13 predicted secreted lipases in Pichia pastoris and evaluated their ability to utilize mono-, di- and triolein substrates. The M. globosa family class 3 lipases were shown to be specific for mono- and diacylglycerols, but exhibited no regio-selective production of diacylglycerols, which are of special interest for industrial applications. Lipases belonging to the Lip family utilized all substrates. In a further step, five lipases previously demonstrated to be expressed on human skin were tested against the eight most common di- and triacylglycerols in human sebum. All lipases liberated free fatty acids from three to eight of these substrates, proving their ability to hydrolyse key components of human sebum. Again, only Lip family lipases showed activity on triacylglycerides. Based on the demonstrated activity and expression levels of MgLip2 in M. globosa, the Lip lipase family appears to have the highest impact for the pathogenicity of M. globosa.

Background: All the currently recognized Malassezia species have been isolated from mammals. However, only a few of them have been isolated from birds. In fact, birds have been less frequently studied as carriers of Malassezia yeasts than mammals., Aim: In this study we describe two new taxa, Malassezia brasiliensis sp. nov. and Malassezia psittaci sp. nov., Methods: The isolates studied in this publication were isolated from pet parrots from Brazil. They were characterized using the current morphological and physiological identification scheme. DNA sequencing and analysis of the D1/D2 regions of the 26S rRNA gene, the ITS-5.8S rRNA gene sequences and the β-tubulin gene were also performed., Results: The strains proposed as new species did not completely fit the phenotypic profiles of any the described species. The validation of these new species was supported by analysis of the genes studied. The multilocus sequence analysis of the three loci provides robust support to delineate these species., Conclusions: These studies confirm the separation of these two new species from the other species of the genus Malassezia, as well as the presence of lipid-dependent Malassezia yeasts on parrots., (Copyright © 2016 Asociación Española de Micología. Published by Elsevier Espana. All rights reserved.)

Dandruff is a common but complex disorder with three major contributing factors: (1) individual predisposition, (2) scalp sebum and (3) Malassezia yeast colonization. To obtain further insights into the role of sebum in dandruff biogenesis, we analyzed scalp lipid species in a cohort of ten dandruff-free (control) and ten dandruff-afflicted volunteers by gas chromatography coupled to mass spectrometry. Lipid peroxidation levels and biochemical markers of oxidative stress were also assessed. Squalene, a major sebum component, was significantly more peroxidized in dandruff-affected scalps, resulting in significantly higher ratios of squalene monohydroperoxide (SQOOH)/squalene. This was observed when comparing dandruff-affected zones of dandruff subjects to both their non-affected zones and control subjects. In addition, other biomarkers such as malondialdehyde indicated that oxidative stress levels were raised on dandruff scalps. Surprisingly, differences regarding either free or bound fatty acids were fairly rare and minor. Certain novel findings, especially squalene peroxidation levels, were then confirmed in a validation cohort of 24 dandruff-affected subjects, by comparing dandruff-affected and non-dandruff zones from the same individuals. As SQOOH can induce both keratinocyte inflammatory responses and hyperproliferation in vitro, we hypothesized that increased SQOOH could be considered as a new etiological dandruff factor via its ability to impair scalp barrier function. Our results also indicated that Malassezia could be a major source of squalene peroxidation on the scalp.

Aryl hydrocarbon receptor (AHR) is a ligand-dependent transcription factor that binds to structurally diverse chemicals including dioxins, coal tar, flavonoids and tryptophan photoproducts. Upon ligation, cytoplasmic AHR translocates to the nucleus, heterodimerizes with aryl hydrocarbon receptor nuclear translocator and mediates numerous biological effects by inducing the transcription of various AHR-responsive genes such as epidermal barrier proteins. The activation of AHR usually generates oxidative stress. However, AHR also mediates antioxidant signaling by a plethora of ligands via nuclear factor-erythroid 2-related factor-2. Both oxidative and antioxidant ligands upregulate the expression of the filaggrin gene. We review the role of AHR signaling in the gene regulation of epidermal barrier proteins., (Copyright © 2015 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.)

Despite the fact that most lipases are believed to be active against triacylglycerides, there is a small group of lipases that are active only on mono- and diacylglycerides. The reason for this difference in substrate scope is not clear. We tried to identify the reasons for this in the lipase from Malassezia globosa. By protein engineering, and with only one mutation, we managed to convert this enzyme into a typical triacylglycerol lipase (the wild-type lipase does not accept triacylglycerides). The variant Q282L accepts a broad spectrum of triacylglycerides, although the catalytic behavior is altered to some extent. From in silico analysis it seems that specific hydrophobic interactions are key to the altered substrate specificity., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Thermostability and substrate specificity are important characteristics of enzymes for industrial application, which can be improved by protein engineering. SMG1 lipase from Malassezia globosa is a mono- and diacylglycerol lipase (MDL) that shows activity toward mono- and diacylglycerols, but no activity toward triacylglycerols. SMG1 lipase is considered a potential biocatalyst applied in oil/fat modification and its crystal structure revealed that an interesting residue-Asn277 may contribute to stabilize loop 273-278 and the 3104 helix which are important to enzyme characterization. In this study, to explore its role in affecting the stability and catalytic activity, mutagenesis of N277 with Asp (D), Val (V), Leu (L) and Phe (F) was conducted. Circular dichroism (CD) spectral analysis and half-life measurement showed that the N277D mutant has better thermostability. The melting temperature and half-life of the N277D mutant were 56.6 °C and 187 min, respectively, while that was 54.6 °C and 121 min for SMG1 wild type (WT). Biochemical characterization of SMG1 mutants were carried out to test whether catalytic properties were affected by mutagenesis. N277D had similar enzymatic properties as SMG1 WT, but N277F showed a different substrate selectivity profile as compared to other SMG1 mutants. Analysis of the SMG1 3D model suggested that N277D formed a salt bridge via its negative charged carboxyl group with a positively charged guanidino group of R227, which might contribute to confer N277D higher temperature stability. These findings not only provide some clues to understand the molecular basis of the lipase structure/function relationship but also lay the framework for engineering suitable MDL lipases for industrial applications.

Malassezia yeasts are commensal microorganisms, which under insufficiently understood conditions can become pathogenic. We have previously shown that specific strains isolated from diseased human skin can preferentially produce agonists of the aryl hydrocarbon receptor (AhR), whose activation has been linked to certain skin diseases. Investigation of skin scale extracts from patients with Malassezia-associated diseases demonstrated 10- to 1,000-fold higher AhR-activating capacity than control skin extracts. Liquid chromatography-tandem mass spectrometry analysis of the patients' extracts revealed the presence of indirubin, 6-formylindolo[3,2-b]carbazole (FICZ), indolo[3,2-b]carbazole (ICZ), malassezin, and pityriacitrin. The same compounds were also identified in 9 out of 12 Malassezia species culture extracts tested, connecting their presence in skin scales with this yeast. Studying the activity of the Malassezia culture extracts and pure metabolites in HaCaT cells by reverse transcriptase real-time PCR revealed significant alterations in mRNA levels of the endogenous AhR-responsive genes Cyp1A1, Cyp1B1, and AhRR. Indirubin- and FICZ-activated AhR in HaCaT and human HepG2 cells with significantly higher, yet transient, potency as compared with the prototypical AhR ligand, dioxin. In loco synthesis of these highly potent AhR inducers by Malassezia yeasts could have a significant impact on skin homeostatic mechanisms and disease development.

Melanins are synthesized by organisms of all biological kingdoms and comprise a heterogeneous class of natural pigments. Certain of these polymers have been implicated in the pathogenesis of several important human fungal pathogens. This study investigated whether the fungal skin pathogen Malassezia furfur produces melanin or melanin-like compounds. A melanin-binding monoclonal antibody (MAb) labelled in vitro cultivated yeast cells of M. furfur. In addition, melanization of Malassezia yeasts and hyphae was detected by anti-melanin MAb in scrapings from patients with pityriasis versicolor. Treatment of Malassezia yeasts with proteolytic enzymes, denaturant and concentrated hot acid yielded dark particles and electron spin resonance spectroscopy revealed that these particles contained a stable free radical compound, consistent with their identification as melanins. Malassezia yeasts required phenolic compounds, such as L-DOPA, in order to synthesize melanin. L-DOPA also triggered hyphal formation in vitro when combined with kojic acid, a tyrosinase inhibitor, in a dose-dependent manner. In this respect, L-DOPA is thought to be an essential substance that is linked to both melanization and yeast-mycelial transformation in M. furfur. In summary, M. furfur can produce melanin or melanin-like compounds in vitro and in vivo, and the DOPA melanin pathway is involved in cell wall melanization.

Various C-type lectin receptors (CLRs), including Mincle and Dectin-2, function as pattern recognition receptors and play a central role in immunity to fungal pathogens. However, the precise structures of the CLR ligands in various pathogenic fungi have yet to be completely defined. Here we report that Malassezia, an opportunistic skin fungal pathogen, is cooperatively recognized by Mincle and Dectin-2 through distinct ligands. Solvent-based fractionation revealed that Mincle and Dectin-2 recognize lipophilic and hydrophilic components of Malassezia, respectively. Mass spectrometry and nuclear magnetic resonance (NMR) revealed glyceroglycolipid and unique mannosyl fatty acids linked to mannitol as two Mincle ligands. An O-linked mannobiose-rich glycoprotein was identified as a Malassezia ligand for Dectin-2. Cytokine production in response to the Mincle ligands and the Dectin-2 ligand was abrogated in Mincle(-/-) and Dectin-2(-/-) dendritic cells, respectively. These results demonstrate that Mincle and Dectin-2 recognize distinct ligands in Malassezia to induce host immune responses., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Dandruff is a global consumer problem, characterized by flaking and scaling of the scalp, accompanied by itch and irritancy. However, the aetiology of the condition remains poorly understood, although there is a strong consensus that the cutaneous fungi Malassezia globosa and M. restricta are a major contributory factor. Although there is a paucity of understanding on how these commensal microorganisms adopt a pathogenic phenotype, a rich source of potential insights now exists in the shape of the recently published whole-genome sequence of M. globosa, a functional annotation and metabolic reconstruction of which is freely accessible via the integrated microbial genomes (IMG) online community resource (http://www.hmpdacc-resources.org/cgi-bin/imgm&#95;hmp/main.cgi). In these studies, we have taken a combined in-silico and in-vitro approach to investigate aspects of lipid and amino acid metabolism by M. globosa and M. restricta that have the potential to impact on scalp condition and dandruff. The IMG platform was employed to analyse the metabolism of triacylglycerols and fatty acids, as well as the aromatic amino acid tryptophan, by M. globosa, to investigate pro-inflammatory pathways linked in the literature to dandruff and pityriasis versicolour, respectively. Results were equivocal, leaving question marks over the ability of M. globosa to fully degrade unsaturated fatty acids and metabolize tryptophan to indole-3-pyruvic acid. In-vitro assay systems were then developed to study the biotransformation of these metabolites by both M. globosa and M. restricta, as well as their effect on human keratinocytes, and the results here indicated that neither unsaturated fatty acids nor indole derivatives are likely to be major aetiological factors in dandruff., (© 2012 Society of Cosmetic Scientists and the Société Française de Cosmétologie.)

Antimicrobial effects of substances can be determined with different methods that measure distinct parameters. Thus, a comparison of the results obtained can be difficult. In this study, two in vitro methods were employed to determine concentration and time dependent effects of cyclodextrin (CD)-complexes with the antiseptics chlorhexidine diacetate (CHX), iodine (IOD) and polihexanide (PHMB) on Candida albicans and Malassezia pachydermatis. Using both, microplate laser nephelometry and the ATP bioluminescence assay, it could be shown that CD-antiseptics-complexes tested exhibited significant antifungal effects with the exception of γ-CD-CHX in the case of C. albicans. Microplate laser nephelometry (MLN) is an optical method and enables a quantitative determination of particle concentrations in solution. By means of this method, microbial growth under influence of potential antimicrobial substances can be monitored over a prolonged time period. In addition, the antimicrobial activity was analyzed by measurement of the microbial adenosine triphosphate (ATP) content with a bioluminescent assay. The luminescent signal is directly proportional to the amount of ATP, and thus, a linear function of the number of living microbial cells present. Both methods were compared according to the half maximal inhibitory concentration (IC(50)) calculated and the statistical evaluation of Pearson's correlation coefficient (r). In summary, it could be demonstrated that both methods yield similar results although they differ in the parameter., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Background: Malassezia (M.) species are members of the normal part of the skin flora, but they might induce or be involved with various cutaneous diseases. Although the role of Malassezia in the pathogenesis of cutaneous diseases is not fully understood, recent studies have shown that decreased density of Malassezia led to improvement of these diseases., Objective: To identify the antifungal effect of light emitting diode (LED) against Malassezia, its antifungal mechanisms and the impact on the keratinocytes., Methods: LED with various wavelengths (370-630nm) on Malassezia furfur, Malassezia sympodialis and Malassezia globosa was irradiated according to dose and then the antifungal effects were thereafter assessed. After irradiating LED with 392.5±1nm of wavelength according to dose on Malassezia species, reactive oxygen species (ROS) and lipid hydroperoxide production assay were measured. In addition, cell viability and inflammatory cytokines (IL-1α, IL-1β, TNF-α, TGF-β, TLR-2 and COX-2) expressions in normal human epidermal keratinocytes (NHEKs) by LED irradiation were evaluated., Results: The growth of Malassezia species was dose-dependently suppressed by both LED with 380±2 and 392.5±1nm wavelengths. The increases of intracellular and extracellular ROS by LED irradiation with 392.5±1nm wavelengths were significantly observed compared to control group. The cell viability and cytokines in NHEKs were not significantly affected by LED irradiation under 5J/cm(2)in vitro., Conclusion: LED irradiation with 380±2 and 392.5±1nm wavelengths proved to have antifungal effect against Malassezia species and no impact on NHEKs under 5J/cm(2). The findings suggest that LED might be an adjunctive therapeutic light tool against Malassezia yeasts related cutaneous diseases., (Copyright © 2012 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.)

Malassezia pachydermatis and Candida albicans are fungi involved in the skin diseases and systemic infections. The therapy of such infections is difficult due to relapses and problems with pathogen identification. In our study, we compare the fatty acids profile of M. pachydermatis, C. albicans and S. cerevisiae to identify diagnostic markers and to investigate the effect of oxythiamine (OT) on the lipid composition of these species. Total fatty acid content is threefold higher in C. albicans and M. pachydermatis compared with S. cerevisiae. These two species have also increased level of polyunsaturated fatty acids (PUFA) and decreased content of monounsaturated fatty acids (MUFA). We noted differences in the content of longer chain (>18) fatty acids between studied species (for example a lack of 20 : 1 in S. cerevisiae and 22 : 0 in M. pachydermatis and C. albicans). OT reduces total fatty acids content in M. pachydermatis by 50%. In S. cerevisiae, OT increased PUFA whereas it decreased MUFA content. In C. albicans, OT decreased PUFA and increased MUFA and SFA content. The results show that the MUFA to PUFA ratio and the fatty acid profile could be useful diagnostic tests to distinguish C. albicans, M. pachydermatis and S. cerevisiae, and OT affected the lipid metabolism of the investigated species, especially M. pachydermatis., (© 2011 Blackwell Verlag GmbH.)

Human zymogen granule protein 16 (ZG16p) contains a Jacalin-like lectin domain, although its glycan-binding properties are not fully understood. Here, we screened the glycan-binding specificity of ZG16p by recently developed glycoconjugate microarray. ZG16p appeared to exhibit selective binding to α- and β-linked mannose-polyacrylamide-biotin probes. In more quantitative analysis using frontal affinity chromatography, dissociation constants to two types of polyvalent mannose, i.e. high-density mannose and yeast mannan, were determined to be 1.3 and 1.7 µM, respectively. Mutation of the evolutionarily conserved amino acid Asp151, which is involved in sugar binding among the Jacalin-related lectins (JRLs), abolished binding activity to mannose. By immunohistochemical staining, ZG16p was specifically detected in mucus-secreting cells of the digestive system such as serosanguineous acinar cells of the parotid gland, acinar cells of the pancreas and goblet cells of the intestine. Finally, we showed that ZG16p recognizes pathogenic Candida and Malassezia species in a polyvalent mannose-dependent manner. We propose that ZG16p is a novel member of mannose-specific JRLs, which recognizes pathogenic fungi through non-self polyvalent mannose in the digestive system.

Although atopic dermatitis is accepted as a chronic and recurrent dermatitis, it is clear that several acute flares are due to superficial but not clearly infectious colonization of the skin by bacteria or mold. This short article provides a brief overview of (nearly all) the evidence concerning the possible mechanism of action of this phenomenon., (Copyright © 2012 S. Karger AG, Basel.)

Malassezia globosa is a lipid-dependent yeast that is found on the human skin and is associated with various skin disorders, including dandruff and seborrhoeic dermatitis (SD). Despite its important role in skin diseases, the molecular basis for its pathogenicity is poorly understood. The current hypothesis is that dandruff and SD are linked to fatty acid metabolism and secretory lipolytic enzymes, which hydrolyse sebaceous lipids and release irritating free fatty acids. A previous genomic analysis of M. globosa identified a family of 13 homologous genes predicted to encode secreted lipases. We have also reported that M. globosa had significantly higher extracellular lipase activity compared with other species. To identify the major secretory lipases of this yeast during its growth, we successfully purified and characterized an extracellular lipase MgLIP2. Based on MALDI-TOF MS, the peptide mass fingerprint of a tryptically digested protein MgLIP2 corresponded to ORF MGL&#95;4054 of M. globosa. This lipase showed high esterase activity against 4-nitrophenyl palmitate and 1-naphthyl palmitate but not 1-naphthyl acetate. This enzyme had optimal activity at 30 °C and pH 5.0. Furthermore, the activity significantly increased in the presence of Triton X-100 and was partially inhibited by PMSF but was unaffected by univalent and divalent metal ions.

Background: Zinc pyrithione (ZPT) is the active ingredient most commonly used in many antidandruff treatments. Despite decades of successful use to treat human scalps, little is understood about the antifungal mechanism of action of ZPT., Objectives: The objective of this study is to understand the molecular mechanism by which ZPT inhibits fungal growth, the underlying basis for its therapeutic activity., Methods: Modern systems biology approaches, such as deletion library screening and microarray analysis, were used in combination with traditional measures of metal content, microbial growth and enzyme assays., Results: It was shown that ZPT inhibits fungal growth through increased cellular levels of copper, damaging iron-sulphur clusters of proteins essential for fungal metabolism., Conclusions: The molecular basis for the antifungal activity of the commonly used active ZPT has been elucidated, more than 50 years since its introduction, as utilizing a copper toxicity mechanism that targets critical iron-sulphur proteins., (© 2011 The Authors. BJD © 2011 British Association of Dermatologists.)

Members of the genus Malassezia are lypophilic and/or lipid-dependent, unipolar budding yeasts that can become pathogenic under the influence of particular predisposing factors (e.g., changes in the cutaneous microenvironment and/or alterations in host defences). This genus comprises at least 14 species, which have been identified traditionally based on their morphology and biochemical features. However, phenetic characteristics often do not allow the identification or delineation of closely related Malassezia spp., such that molecular tools need to be used to assist in fundamental studies of the epidemiology and ecology of Malassezia as well as aspects of the pathogenesis and disease caused by members of this genus. This article briefly reviews the morphological and biochemical methods commonly used for the identification of Malassezia as well as DNA technological methods that have been established for the specific identification of members of this genus and the diagnosis of their infections. New avenues for the development of improved molecular-diagnostic methods to overcome diagnostic limitations and to underpin fundamental investigations of this interesting group of yeasts are proposed., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

The effects of the addition of different amino nitrogens on growth, morphology and secondary metabolism of Malassezia furfur were investigated. After primary culture on Dixon agar, M. furfur CBS 1878 was transferred into a fluid medium together with the nitrogen sources, glycine (Gly) or tryptophan (Trp), or a combination of both. Growth was measured by means of a direct cell counting method and pigment synthesis was photometrically assessed. Addition of glycine resulted in an exponential increase in biomass, but not in pigment production. Tryptophan as the sole nitrogen source caused distinct brown staining of the medium, without increasing biomass. Simultaneous equimolar addition of both amino acids resulted in an initial increase in biomass as a sign of preferential metabolism of glycine, followed by a growth plateau and pigment production which, caused by higher biomass, occurred more rapidly than after addition of tryptophan alone. The yeast-cell morphology changed from round to oval. Addition of glycine to the tryptophan-containing liquid culture stopped pigment formation with simultaneous growth induction. These in vitro on-off phenomena depending on the nitrogen source might be significant in the pathogenesis of pityriasis versicolor: hyperhidrosis followed by preferential consumption of individual nitrogen sources such as glycine with exponential growth and thereafter transamination of tryptophan and TRP-dependent pigment synthesis., (© 2009 Blackwell Verlag GmbH.)

Background: The disrupted skin barrier of patients with atopic eczema (AE) might facilitate contact between mast cells (MCs) in the skin and environmental triggers of the disease. One such trigger is the skin-colonizing yeast Malassezia sympodialis (M. sympodialis). In this study, we investigated the interaction of MC with M. sympodialis., Methods: Mast cells were generated from peripheral blood CD34(+) progenitor cells of healthy controls (HC) and M. sympodialis-sensitized AE patients. Biopsy specimens were taken from HC and lesional AE skin for immunohistological stainings., Results: The progenitor-derived MCs expressed the macrophage-inducible C-type lectin receptor Mincle, and exposure of these cells to M. sympodialis induced up-regulation of the mRNA expression of Mincle. Furthermore, we demonstrate that, when compared to HC, the progenitor-derived MCs from AE patients (i) contain more intrinsic granule mediators such as histamine, (ii) exhibit enhanced IL-6 release in response to M. sympodialis exposure, and (iii) have an impaired up-regulation of the fungal recognition receptor Dectin-1. In addition, analysis of skin sections from HC and AE patients revealed MCs as the predominant Dectin-1-expressing cell type in the skin., Conclusion: Our data indicate that progenitor-derived MCs from AE patients differ from those from HC. Further investigations with skin-derived MCs are necessary to confirm the observed differences which could provide new insights into the pathogenic mechanisms underlying AE., (© 2010 John Wiley & Sons A/S.)

Recent technological advances have revived the interest in Malassezia yeasts and their clinical role, which has long been a matter of controversy because of their fastidious nature in vitro and relative difficulty in isolation, cultivation and identification. Lipophilic yeasts of the genus Malassezia form a part of normal microbial flora of healthy human (and animal) skin, but they also have been associated with several dermatological diseases, like seborrhoeic dermatitis and atopic dermatitis. Our understanding of the interactions between Malassezia and the host might provide new opportunities to better control these often chronically relapsing diseases.

Langerhans cells (LCs) lining the stratified epithelia and mucosal tissues are the first antigen presenting cells to encounter invading pathogens, such as viruses, bacteria and fungi. Fungal infections form a health threat especially in immuno-compromised individuals. LCs express C-type lectin Langerin that has specificity for mannose, fucose and GlcNAc structures. Little is known about the role of human Langerin in fungal infections. Our data show that Langerin interacts with both mannan and beta-glucan structures, common cell-wall carbohydrate structures of fungi. We have screened a large panel of fungi for recognition by human Langerin and, strikingly, we observed strong binding of Langerin to a variety of Candida and Saccharomyces species and Malassezia furfur, but very weak binding was observed to Cryptococcus gattii and Cryptococcus neoformans. Notably, Langerin is the primary fungal receptor on LCs, since the interaction of LCs with the different fungi was blocked by antibodies against Langerin. Langerin recognizes both mannose and beta-glucans present on fungal cell walls and our data demonstrate that Langerin is the major fungal pathogen receptor on human LCs that recognizes pathogenic and commensal fungi. Together these data may provide more insight in the role of LCs in fungal infections., (Copyright 2009 Elsevier Ltd. All rights reserved.)