The effects ofMalasseziaon pro-inflammatory cytokine production by human peripheral blood mononuclear cellsin vitro

A review of skin immune processes in acne

Acne vulgaris is one of the most prevalent skin conditions, affecting almost all teenagers worldwide. Multiple factors, including the excessive production of sebum, dysbiosis of the skin microbiome, disruption of keratinization within hair follicles, and local inflammation, are believed to trigger or aggravate acne. Immune activity plays a crucial role in the pathogenesis of acne. Recent research has improved our understanding of the immunostimulatory functions of microorganisms, lipid mediators, and neuropeptides. Additionally, significant advances have been made in elucidating the intricate mechanisms through which cutaneous innate and adaptive immune cells perceive and transmit stimulatory signals and initiate immune responses. However, our understanding of precise temporal and spatial patterns of immune activity throughout various stages of acne development remains limited. This review provides a comprehensive overview of the current knowledge concerning the immune processes involved in the initiation and progression of acne. Furthermore, we highlight the significance of detailed spatiotemporal analyses, including analyses of temporal dynamics of immune cell populations as well as single-cell and spatial RNA sequencing, for the development of targeted therapeutic and prevention strategies.

Heat-killed Malassezia pachydermatis suspension modulates the activity of macrophages challenged with Encephalitozoon cuniculi

Phagocytic responses are critical for effective host defense against opportunistic fungal pathogens, such as Encephalitozoon cuniculi, an obligate intracellular fungus that causes emerging encephalitozoonosis in humans and other animals. Malassezia has immunomodulatory effects and can modulate the production of pro- and anti-inflammatory cytokines via keratinocytes and human monocytes. In this study, we evaluated the modulatory effects of heat-killed Malassezia pachydermatis suspension on macrophages challenged with Encephalitozoon cuniculi. Macrophages were treated with heat-killed M. pachydermatis suspension before being infected with spores of E. cuniculi. The cultures were stained with calcofluor, and the spores, internalized or not, were counted to determine their phagocytic capacity and index (PC and PI, respectively). Microbicidal and phagocytic activities were evaluated by transmission electron microscopy (TEM). The untreated macrophages had higher PC and PI and number of phagocytosed spores than treated macrophages. However, TEM revealed that treated macrophages had higher microbicidal activity because there were few spores in different degrees of degeneration and amorphous materials in the phagocytic vacuoles. Macrophages treated with heat-killed M. pachydermatis suspension had lower PC and PI and incipient presence of E. cuniculi in phagosomes. Treated macrophages had a mixed pattern of cytokine release with Th1, Th2, and Th17 profiles, with emphasis on interleukin (IL)-10, IL-4, IL-17, IL-6, and interferon (IFN)-γ secretion, and particularly high production of anti-inflammatory cytokines. Our results suggest that treatment with heat-killed M. pachydermatis suspension increases the release of cytokines and decreases the phagocytic activity of macrophages challenged with E. cuniculi.

Effects of Ultra-Weak Fractal Electromagnetic Signals on Malassezia furfur

Malassezia spp. are dimorphic, lipophilic fungi that are part of the normal human cutaneous commensal microbiome. However, under adverse conditions, these fungi can be involved in various cutaneous diseases. In this study, we analysed the effect of ultra-weak fractal electromagnetic (uwf-EMF) field exposure (12.6 nT covering 0.5 to 20 kHz) on the growth dynamics and invasiveness of M. furfur. The ability to modulate inflammation and innate immunity in normal human keratinocytes was also investigated. Using a microbiological assay, it was possible to demonstrate that, under the influence of uwf-EMF, the invasiveness of M. furfur was drastically reduced (d = 2.456, p < 0.001), while at the same time, its growth dynamic after 72 h having been in contact with HaCaT cells both without (d = 0.211, p = 0.390) and with (d = 0.118, p = 0.438) uwf-EM exposure, were hardly affected. Real-time PCR analysis demonstrated that a uwf-EMF exposure is able to modulate human-β-defensin-2 (hBD-2) in treated keratinocytes and at the same time reduce the expression of proinflammatory cytokines in human keratinocytes. The findings suggest that the underlying principle of action is hormetic in nature and that this method might be an adjunctive therapeutic tool to modulate the inflammatory properties of Malassezia in related cutaneous diseases. The underlying principle of action becomes understandable by means of quantum electrodynamics (QED). Given that living systems consist mainly of water and within the framework of QED, this water, as a biphasic system, provides the basis for electromagnetic coupling. The oscillatory properties of water dipoles modulated by weak electromagnetic stimuli not only affect biochemical processes, but also pave the way for a more general understanding of the observed nonthermal effects in biota.

Potential Role of the Microbiome in Acne: A Comprehensive Review

Acne is a highly prevalent inflammatory skin condition involving sebaceous sties. Although it clearly develops from an interplay of multiple factors, the exact cause of acne remains elusive. It is increasingly believed that the interaction between skin microbes and host immunity plays an important role in this disease, with perturbed microbial composition and activity found in acne patients. Cutibacterium acnes (C. acnes; formerly called Propionibacterium acnes) is commonly found in sebum-rich areas and its over-proliferation has long been thought to contribute to the disease. However, information provided by advanced metagenomic sequencing has indicated that the cutaneous microbiota in acne patients and acne-free individuals differ at the virulent-specific lineage level. Acne also has close connections with the gastrointestinal tract, and many argue that the gut microbiota could be involved in the pathogenic process of acne. The emotions of stress (e.g., depression and anxiety), for instance, have been hypothesized to aggravate acne by altering the gut microbiota and increasing intestinal permeability, potentially contributing to skin inflammation. Over the years, an expanding body of research has highlighted the presence of a gut–brain–skin axis that connects gut microbes, oral probiotics, and diet, currently an area of intense scrutiny, to acne severity. This review concentrates on the skin and gut microbes in acne, the role that the gut–brain–skin axis plays in the immunobiology of acne, and newly emerging microbiome-based therapies that can be applied to treat acne.

Acne, the Skin Microbiome, and Antibiotic Treatment

Acne vulgaris is a chronic skin disorder involving hair follicles and sebaceous glands. Multiple factors contribute to the disease, including skin microbes. The skin microbiome in the follicle is composed of a diverse group of microorganisms. Among them, Propionibacterium acnes and Malassezia spp. have been linked to acne development through their influence on sebum secretion, comedone formation, and inflammatory response. Antibiotics targeting P. acnes have been the mainstay in acne treatment for the past four decades. Among them, macrolides, clindamycin, and tetracyclines are the most widely prescribed. As antibiotic resistance becomes an increasing concern in clinical practice, understanding the skin microbiome associated with acne and the effects of antibiotic use on the skin commensals is highly relevant and critical to clinicians. In this review, we summarize recent studies of the composition and dynamics of the skin microbiome in acne and the effects of antibiotic treatment on skin microbes.

Microorganisms inhabiting follicular contents of facial acne are not only Propionibacterium but also Malassezia spp

To clarify the relationship between major cutaneous microorganisms (Propionibacterium, Staphylococcus and Malassezia spp.) and acne vulgaris (acne), we examined the microbiota quantitatively in the follicular contents of inflammatory acne and on the facial skin of patients with acne. Fifteen Japanese untreated acne outpatients were studied. The follicular contents from inflammatory acne lesions of the face were collected using a comedo extractor. The skin surface samples were obtained by the swab method from 10 cm(2) of facial skin. The microbiota was analyzed using polymerase chain reaction. The microbiota in follicular contents was similar to that on the skin surface, namely, there were large populations of Propionibacterium spp., Staphylococcus spp. and Malassezia spp. Moreover, the number of Malassezia spp. on the skin surface was correlated with that of inflammatory acne and that in follicular contents. This study clarified that there are large populations of Propionibacterium spp., Staphylococcus spp. and Malassezia spp. in follicular contents. These results suggest the possibility that not only Propionibacterium acnes but also other cutaneous resident microorganisms are related to acne. Particularly, we considered that Malassezia spp. is closely related.

Malassezia yeasts activate the NLRP3 inflammasome in antigen-presenting cells via Syk-kinase signalling

Although being a normal part of the skin flora, yeasts of the genus Malassezia are associated with several common dermatologic conditions including pityriasis versicolour, seborrhoeic dermatitis (SD), folliculitis, atopic eczema/dermatitis (AE/AD) and dandruff. While Malassezia spp. are aetiological agents of pityriasis versicolour, a causal role of Malassezia spp. in AE/AD and SD remains to be established. Previous reports have shown that fungi such as Candida albicans and Aspergillus fumigatus are able to efficiently activate the NLRP3 inflammasome leading to robust secretion of the pro-inflammatory cytokine IL-1β. To date, innate immune responses to Malassezia spp. are not well characterized. Here, we show that different Malassezia species could induce NLRP3 inflammasome activation and subsequent IL-1β secretion in human antigen-presenting cells. In contrast, keratinocytes were not able to secrete IL-1β when exposed to Malassezia spp. Moreover, we demonstrate that IL-1β secretion in antigen-presenting cells was dependent on Syk-kinase signalling. Our results identify Malassezia spp. as potential strong inducers of pro-inflammatory responses when taken up by antigen-presenting cells and identify C-type lectin receptors and the NLRP3 inflammasome as crucial actors in this process.

The role of L-DOPA on melanization and mycelial production in Malassezia furfur

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.

The itchy scalp--scratching for an explanation

Scalp pruritus is a common complaint that is considered a diagnostically and therapeutically challenging situation. Scalp skin has a unique neural structure that contains densely innervated hair follicles and dermal vasculature. In spite of the recent advances in our understanding of itch pathophysiology, scalp itching has not been studied as yet. In this review, we summarize the current knowledge on the neurobiology of scalp and hair follicles as well as itch mediators and provide a putative mechanism for scalp itch with special emphasis on neuroanatomy and pathophysiology.

Effects of Malassezia yeasts on serum Th1 and Th2 cytokines in patients with guttate psoriasis

BACKGROUND

Systemic and focal infections caused by microorganisms have been known to induce or exacerbate psoriasis. Although the role of yeast species of the genus Malassezia in the pathogenesis of psoriasis is not fully understood, it is thought that these lipophilic yeasts may represent a triggering factor in the exacerbation of psoriatic lesions.

OBJECTIVES

This study investigated the effects of Malassezia yeasts on serum Th1 and Th2 cytokines in patients with guttate psoriasis (GP) in order to define their role in the pathogenesis of psoriasis.

METHODS

Fifty patients with GP and 29 clinically healthy individuals were included in the study. All samples consisted of scales and scrapings taken from the scalps, trunks, and upper limbs of both psoriasis patients and healthy subjects. Psoriasis patients and healthy subjects were grouped according to their positivity or negativity for Malassezia yeasts as ascertained by direct microscopy and/or culture. An enzyme-linked immunosorbent assay (ELISA) was used to measure serum levels of Th1 and Th2 cytokines in these groups.

RESULTS

No significant differences in positivity for Malassezia yeasts were found between psoriatic skin and healthy skin in samples taken from different body sites. Serum interleukin-13 (IL-13) levels were significantly lower in the psoriasis group compared with the control group (P = 0.04). Levels of other cytokines did not differ significantly between the psoriasis and control groups. Mean levels of Th2 cytokines (IL-4, IL-10, IL-13), but not of Th1 cytokines (IL-2 and IFN-γ), were significantly lower in psoriasis patients positive for Malassezia yeasts compared with those negative for Malassezia yeasts and control subjects (P = 0.04, P < 0.001 and P = 0.01, respectively).

CONCLUSIONS

The isolation of Malassezia yeasts from GP lesions does not necessarily mean that these species are pathogenic, but their downregulating effects on anti-inflammatory Th2 cytokines may contribute to the occurrence of GP.

Interesting effect of Malassezia spp. infection on dermatoses of other origins

BACKGROUND

Tinea versicolor (TV) is a superficial fungal infection affecting as many as 40% of the population in the tropics. We noticed an unusual affect of TV on dermatoses of other origins.

METHODS

In this prospective clinical study, we examined patients attending our dermatology outpatient department over a period of one year for coexistence of TV with any unrelated dermatoses. We confirmed the diagnosis of TV by microscopy of skin scrapings. Skin biopsy was performed when necessary to confirm the diagnosis of associated dermatoses.

RESULTS

We describe four cases in which unrelated dermatoses (viral exanthem, acute generalized exanthematous pustulosis, polymorphous light eruption, and irritant contact dermatitis) specifically spared sites affected with TV.

CONCLUSIONS

Recent research has elucidated the immunomodulatory properties of Malassezia spp. in vitro. Our cases serve as possible in vivo models illustrating such properties. Further studies based on these reports could lead to the isolation of molecules from Malassezia, which may have potential use in anti-inflammatory drug formulations.

Nanovesicles from Malassezia sympodialis and host exosomes induce cytokine responses--novel mechanisms for host-microbe interactions in atopic eczema

Background

Intercellular communication can occur via the release of membrane vesicles. Exosomes are nanovesicles released from the endosomal compartment of cells. Depending on their cell of origin and their cargo they can exert different immunoregulatory functions. Recently, fungi were found to produce extracellular vesicles that can influence host-microbe interactions. The yeast Malassezia sympodialis which belongs to our normal cutaneous microbial flora elicits specific IgE- and T-cell reactivity in approximately 50% of adult patients with atopic eczema (AE). Whether exosomes or other vesicles contribute to the inflammation has not yet been investigated.

Objective

To investigate if M. sympodialis can release nanovesicles and whether they or endogenous exosomes can activate PBMC from AE patients sensitized to M. sympodialis.

Methods

Extracellular nanovesicles isolated from M. sympodialis, co-cultures of M. sympodialis and dendritic cells, and from plasma of patients with AE and healthy controls (HC) were characterised using flow cytometry, sucrose gradient centrifugation, Western blot and electron microscopy. Their ability to stimulate IL-4 and TNF-alpha responses in autologous CD14, CD34 depleted PBMC was determined using ELISPOT and ELISA, respectively.

Results

We show for the first time that M. sympodialis releases extracellular vesicles carrying allergen. These vesicles can induce IL-4 and TNF-α responses with a significantly higher IL-4 production in patients compared to HC. Exosomes from dendritic cell and M. sympodialis co-cultures induced IL-4 and TNF-α responses in autologous CD14, CD34 depleted PBMC of AE patients and HC while plasma exosomes induced TNF-α but not IL-4 in undepleted PBMC.

Conclusions

Extracellular vesicles from M. sympodialis, dendritic cells and plasma can contribute to cytokine responses in CD14, CD34 depleted and undepleted PBMC of AE patients and HC. These novel observations have implications for understanding host-microbe interactions in the pathogenesis of AE.

Malassezia virulence determinants

PURPOSE OF REVIEW

Malassezia yeasts are associated with a number of dermatologic and systemic diseases in humans and animals. Pityriasis versicolor is amongst these diseases and represents one of the most common human skin diseases. Beyond that, the role of Malassezia yeasts in the pathogenesis of other skin diseases such as psoriasis, seborrheic dermatitis and confluent and reticulate papillomatosis is discussed but remains less clear. Clear pathogenetic mechanisms of the above-mentioned diseases are not known so far. The review presents new findings on virulence factors of Malassezia yeasts, shedding light on the pathogenesis of Malassezia-associated diseases.

RECENT FINDINGS

Several virulence factors in Malassezia yeasts are known, based on their enzymatic lipolytic activity resulting in the production of distinct metabolites and special cell wall features. Recently, a secondary metabolic pathway possibly implicated in the pathogenesis of pityriasis versicolor was described.

SUMMARY

The article presents virulence factors of Malassezia yeasts ranging from irritant metabolic byproducts to highly bioactive indole derivatives and attempts to clarify their pathogenic implications in the different diseases. Special emphasis is given to the pathogenesis of pityriasis versicolor, as it represents the disease wherein the causative relationship with Malassezia yeasts appears the most obvious.

Malassezia folliculitis is caused by cutaneous resident Malassezia species

Malassezia folliculitis [MF] is caused by the invasion of hair follicles by large numbers of Malassezia cells, but it remains unclear which Malassezia species are involved in the disease. To clarify this situation, Malassezia species isolated from lesions of MF patients were analyzed by both culture and non-culture methods. In addition, Malassezia species recovered from the non-lesion areas of the skin of MF patients and skin samples of healthy subjects were included in this study. The test population consisted of 32 MF patients and 40 healthy individuals. The lesions were obtained using a comedone extractor, while swabs were employed to obtain skin samples from non-lesion areas of the patients and healthy subjects. Malassezia DNA was analyzed using a real-time PCR technique. The detection limit of the culture method was 5 CFU/cm(2) as opposes 50 cells/cm(2) with non-culture procedures. The predominant species recovered from MF lesions were M. globosa and M. sympodialis by culture method analysis, and M. restricta, M. globosa, and M. sympodialis with non-culture methods. These results were in agreement with those found with samples from non-lesion skin areas of MF patients and healthy subjects. This study clarified that MF is caused by Malassezia species that are part of the cutaneous microflora and not by exogenous species.

The Effect of Detergents on the Morphology and Immunomodulatory Activity of Malassezia furfur

BACKGROUND

Several workers have found that Malassezia are capable of suppressing cytokine release and downregulating the phagocytic function of monocytes. But lipid-depleted Malassezia furfur (M. furfur) extracts have also been shown to induce increased production of TNF-alpha, IL-6 and IL-1beta in monocytes. We thought that the detergents in shampoos or soaps could change the composition of the lipid in the M. furfur cell wall.

OBJECTIVE

We studied whether detergents affect the morphology of M. furfur and if the inflammatory cytokine profiles change in the monocytes treated with detergent-treated M. furfur.

METHODS

Commonly used detergents such as sodium lauryl sulfate, ammonium lauryl sulfate and tween-80 were respectively added to the modified Leeming-Notman's media. M. furfur was cultivated in each media (detergent-added or untreated). Thereafter, the surface morphology of the yeast was evaluated by scanning and transmission electron microscopy. The cytokine profiles of monocytes, which were treated by M. furfur with or without detergents, were also evaluated.

RESULTS

The detergent-treated M. furfur were similar to the lipid-extracted form of M. furfur on the electron microscopic study, with a recessed, withered surface and with thinner and rather electron transparent cell walls than the detergent-untreated M. furfur. The levels of TNF-alpha were higher in monocytes treated with detergent-treated Malassezia than that in the monocytes treated with the detergent-untreated Malassezia (p<0.05).

CONCLUSION

According to the findings in this study, it could be inferred that the detergents in shampoos or soaps affect the lipid layers of the Malassezia cell wall and these lipid-extracted Malassezia induce or aggravate some inflammatory conditions. But to correlate the relationship between detergents and Malassezia-associated diseases, in vivo experiments that will focus on short-term contact with detergents in real life conditions should be done.

Distribution of Malassezia species in seborrhoeic dermatitis: correlation with patients' cellular immune status

Malassezia species are implicated in the pathogenesis of seborrhoeic dermatitis (SD), but the relationship between each species and the disorder remains unclear. It is hypothesised that the pathogenesis of SD has an immune component, which is supported by the increased incidence in patients with immunosuppressive disorders. The purpose of our study was to analyse the prevalence of Malassezia species in lesional skin of SD, and to assess the distribution of the species according to severity of the disease and cellular immune status of the patients. Forty SD patients with scalp involvement were included in the study. The samples were obtained by scraping the skin surface of the scalp and then incubated on Sabouraud dextrose agar and modified Dixon agar. The yeasts isolated were identified by their morphological and physiological properties according to the method of Guillot et al. In addition, we performed two-colour flow cytometry analysis to investigate the lymphocyte subpopulations in the peripheral blood. The most commonly isolated species was Malassezia restricta (27.5%), followed by Malassezia globosa (17.5%) and Malassezia slooffiae (15%). We demonstrated low helper/suppressor ratios in 70% patients, because of an increase in the suppressor T-cell population, suggesting an impaired cellular immunity. However, we found no significant difference in the distribution of isolated Malassezia species according to the severity of the scalp involvement and changes in the peripheral blood lymphocyte subpopulations.

The role of Malassezia in atopic dermatitis affecting the head and neck of adults

Atopic dermatitis is a common chronic skin condition. A subset of patients with head and neck dermatitis may have a reaction to Malassezia flora fueling their disease. Although there are no documented differences in Malassezia species colonization, patients with head and neck atopic dermatitis are more likely to have positive skin prick test results and Malassezia-specific IgE compared with healthy control subjects and patients with atopy without head and neck dermatitis. There is no clear relationship with atopy patch testing. The reaction to Malassezia is likely related to both humoral- and cell-mediated immunity. Clinically, Malassezia allergy may be suspected in patients with atopic dermatitis and: (1) head and neck lesions; (2) exacerbations during adolescence or young adulthood; (3) severe lesions recalcitrant to conventional therapy; and (4) other atopic diseases. There is literature to suggest that these patients will benefit from a 1- to 2-month course of daily itraconazole or ketoconazole followed by long-term weekly treatment.

Immune response to fungal infections

The immune mechanisms of defence against fungal infections are numerous, and range from protective mechanisms that were present early in evolution (innate immunity) to sophisticated adaptive mechanisms that are induced specifically during infection and disease (adaptive immunity). The first-line innate mechanism is the presence of physical barriers in the form of skin and mucous membranes, which is complemented by cell membranes, cellular receptors and humoral factors. There has been a debate about the relative contribution of humoral and cellular immunity to host defence against fungal infections. For a long time it was considered that cell-mediated immunity (CMI) was important, but humoral immunity had little or no role. However, it is accepted now that CMI is the main mechanism of defence, but that certain types of antibody response are protective. In general, Th1-type CMI is required for clearance of a fungal infection, while Th2 immunity usually results in susceptibility to infection. Aspergillosis, which is a disease caused by the fungus Aspergillus, has been the subject of many studies, including details of the immune response. Attempts to relate aspergillosis to some form of immunosuppression in animals, as is the case with humans, have not been successful to date. The defence against Aspergillus is based on recognition of the pathogen, a rapidly deployed and highly effective innate effector phase, and a delayed but robust adaptive effector phase. Candida albicans, part of the normal microbial flora associated with mucous surfaces, can be present as congenital candidiasis or as acquired defects of cell-mediated immunity. Resistance to this yeast is associated with Th1 CMI, whereas Th2 immunity is associated with susceptibility to systemic infection. Dermatophytes produce skin alterations in humans and other animals, and the essential role of the CMI response is to destroy the fungi and produce an immunoprotective status against re-infection. The resolution of the disease is associated with a delayed hypersensitive response. There are many effective veterinary vaccines against dermatophytoses. Malassezia pachydermatis is an opportunistic yeast that needs predisposing factors to cause disease, often related to an atopic status in the animal. Two species can be differentiated within the genus Cryptococcus with immunologic consequences: C. neoformans infects predominantly immunocompromised hosts, and C. gattii infects non-immunocompromised hosts. Pneumocystis is a fungus that infects only immunosupressed individuals, inducing a host defence mechanism similar to that induced by other fungal pathogens, such as Aspergillus.

Update on the genusMalassezia

Malassezia yeasts are commensals of normal human skin, but also cause pityriasis versicolor, seborrhoeic dermatitis and evidence is accumulating that they play a significant role in atopic eczema/dermatitis syndrome (AEDS; formerly atopic dermatitis). The taxonomy of the genus has changed considerably and is likely to change more in the future. Our understanding of the interaction between Malassezia and the host demonstrates that it has the paradoxical ability to both stimulate and suppress the immune response directed against it and there is a fine balance in its existence at the interface between commensalism and pathogenicity.

Study of bronchoalveolar lavage fluid in paracoccidioidomycosis: cytopathology and alveolar macrophage function in response to gamma interferon; comparison with blood monocytes

Patients with paracoccidioidomycosis (PCM) present marked involvement of the lungs during the course of the mycosis. The purpose of this work was to obtain bronchoalveolar lavage (BAL) fluid from these patients to study the cytopathology, TNF levels and the oxidative and fungicidal response of alveolar macrophages (AMs) to in vitro incubation with recombinant IFN-gamma. To compare the lung and blood compartments, these determinations were also made in plasma and blood monocytes (BMs) obtained from the same patients. The cytopathology of BAL fluid revealed a predominance of macrophages, but with the presence of neutrophil exudation, and rare lymphocytes and epithelioid and giant cells. Comparison of the oxidative status and fungicidal activity of AMs and circulating BMs demonstrated that both cell types are highly activated for these two functions when compared to control cells. However, TNF levels were higher in BAL fluid than in plasma. The possible mechanisms involved in the hyperresponsiveness of cells from PCM patients are discussed.

Up-regulated expression of MICA and proinflammatory cytokines in skin biopsies from patients with seborrhoeic dermatitis

Seborrhoeic dermatitis is a disease of unknown etiopathogenesis that affects 5% of the population. In this study, we investigated expression of mRNA for IL-1 alpha, IL-6, IL-4, IFN-gamma, and the stress-inducible MICA molecule in skin biopsies from 12 patients with moderate to severe seborrhoeic dermatitis and 2 healthy volunteers by RT-PCR and hybridization with specific probes. Eight patients expressed INF-gamma, 2 expressed IL-6, 8 expressed IL-1 alpha, and 2 expressed IL-4 (1 with moderate disease). Eight patients expressed inflammatory cytokines (IL-1 alpha, IL-6, and/or IFN-gamma) in healthy skin. Higher cytokine mRNA in damaged vs healthy skin was also observed, suggesting the existence of an inflammation that predisposes healthy skin to develop overt disease. Up-regulated expression of MICA mRNA was observed in 8 patients. Although the pathogenesis of seborrhoeic dermatitis remains to be elucidated, expression of cytotoxicity-activating ligands (MICA), recruitment of NK cells, and a local pro-inflammatory microenvironment may facilitate the development of tissue injury.

Immunology of diseases associated with Malassezia species

Malassezia species are members of the human cutaneous commensal flora, in addition to causing a wide range of cutaneous and systemic diseases in suitably predisposed individuals. Studies examining cellular and humoral immune responses specific to Malassezia species in patients with Malassezia-associated diseases and healthy controls have generally been unable to define significant differences in their immune response. The use of varied antigenic preparations and strains from different Malassezia classifications may partly be responsible for this, although these problems can now be overcome by using techniques based on recent work defining some important antigens and also a new taxonomy for the genus. The finding that the genus Malassezia is immunomodulatory is important in understanding its ability to cause disease. Stimulation of the reticuloendothelial system and activation of the complement cascade contrasts with its ability to suppress cytokine release and downregulate phagocytic uptake and killing. The lipid-rich layer around the yeast appears to be pivotal in this alteration of phenotype. Defining the nonspecific immune response to Malassezia species and the way in which the organisms modulate it may well be the key to understanding how Malassezia species can exist as both commensals and pathogens.

The allergenic yeast Malassezia furfur induces maturation of human dendritic cells

BACKGROUND

The yeast Malassezia furfur (M. furfur), present in the normal microflora of human skin, can act as an allergen that incites specific IgE reactivity and T cell proliferation in atopic dermatitis (AD) patients. The role of antigen presenting dendritic cells (DCs) in the onset and maintenance of AD is not well established.

OBJECTIVE

The objective of the present study was to assess whether the interaction of M. furfur with human DCs will result in DC maturation, cytokine production and lymphocyte proliferation.

METHODS

Monocyte-derived dendritic cells (MDDCs) were generated from human peripheral blood. Immature MDDCs were cultured with or without M. furfur or plastic beads, and with or without CD40L stimulation. Interaction of yeast cells by MDDCs was studied by time-lapse photography and cytokines were detected in culture supernatants with ELISA. The ability of MDDCs pre-incubated with M. furfur to induce proliferation in autologous lymphocytes was measured by [(3)H]-thymidine incorporation.

RESULTS

Time-lapse photography showed that the majority of immature MDDCs internalized whole M. furfur yeast cells within 1 h. The presence of M. furfur induced maturation (CD83 expression) of MDDCs, and up-regulation of the costimulatory molecules CD80 and CD86. Production of TNF-alpha, IL-1 beta and IL-18 by MDDCs increased significantly (P < 0.05 for TNF-alpha and IL-1 beta, and P < 0.01 for IL-18) after the addition of M. furfur, while IL-10 and IL-12p70 levels remained unaltered. The CD40L-stimulated IL12p70 production by MDDCs was decreased in the presence of M. furfur (P < 0.05). Finally, immature MDDCs pre-incubated with M. furfur induced a proliferative response in autologous CD14-depleted peripheral blood mononuclear cells, in a dose-dependent manner.

CONCLUSION

The data indicate that immature MDDCs can internalize the opportunistic yeast M. furfur. This process was associated with MDDC maturation, production of pro-inflammatory and immunoregulatory cytokines, which might favour induction of a Th2-type immune response, and a capacity to stimulate lymphocyte proliferation. This chain of events most likely contributes to the inflammatory reaction in AD.

The effects of Malassezia yeasts on cytokine production by human keratinocytes

Yeasts of Malassezia, members of the microbiologic flora of the skin, cause pityriasis versicolor and have also been implicated in the pathogenesis of other superficial dermatoses; the most important ones are seborrheic dermatitis, folliculitis, and atopic dermatitis. The mechanisms by which the yeasts cause these dermatoseş however, are not yet clear, and there have been no studies on the interaction between fungi and keratinocytes, especially the effects of fungi on the production of cytokines by human keratinocytes. Recently, the genus Malassezia has been expanded to seven species based on molecular data. In this study, we estimated the effects of Malassezia yeasts on cytokine (interleukins 1beta, 6, and 8, monocyte chemotactic protein-1, and tumor necrosis factor-alpha) production by human keratinocytes in order to examine whether the pathogenicity of the respective Malassezia yeasts is different from each other and to elucidate the mechanism by which Malassezia yeasts cause the dermatoses with different clinical and pathologic manifestations. Variable levels of interleukin 6 and 8, and tumor necrosis factor-alpha in the supernatants in response to Malassezia yeasts (except M. furfur) increased from 1 to 24 h co-culture, but the monocyte chemotactic protein-1 was undetectable. Furthermore, cytokine levels in the supernatants were undetectable 1-24 h after the keratinocytes were harvested with only supernatants of Malassezia. These results indicate that Malassezia stimulates cytokine production by keratinocytes, the cytokine production needs the presence of Malassezia, and there are differences in ability to induce cytokine production by human keratinocytes among Malassezia yeasts. These differences may reflect the different inflammatory responses in Malassezia-associated dermatoses, resulting in different clinical and pathologic manifestations.

Seborrhoeic dermatitis and Pityrosporum (Malassezia) folliculitis: characterization of inflammatory cells and mediators in the skin by immunohistochemistry

BACKGROUND

The fact that Pityrosporum ovale plays a part in seborrhoeic dermatitis is well established but the mechanism of this relationship has not been established.

OBJECTIVES

To compare the number and type of inflammatory cells and mediators in skin biopsies from normal and lesional skin from the trunk and scalp in patients with seborrhoeic dermatitis, Pityrosporum (Malassezia) folliculitis and in normal skin from healthy controls.

METHODS

The skin biopsies were stained using the labelled Streptavidin-biotin

METHOD

The following markers were studied: CD4, CD8, CD68, HLA-DR, NK1, CD16, C1q, C3c, IgG, CD54 (ICAM-1), interleukin (IL) -1alpha, IL-1beta, IL-2, IL-4, IL-6, IL-10, IL-12, tumour necrosis factor-alpha and interferon-gamma.

RESULTS

HLA-DR+ cells were seen in the highest number, and were higher in lesional skin compared with normal skin from both patients and healthy volunteers. ICAM-1 expression was also increased in lesional skin. C1q and the interleukins showed an increased cellular and intercellular staining in patients compared with healthy controls and the intercellular staining was often more intense in lesions compared with non-lesional skin. Staining was often more intense when Malassezia (Pityrosporum ovale) yeast cells were present.

CONCLUSIONS

An increase in NK1+ and CD16+ cells in combination with complement activation indicates that an irritant non-immunogenic stimulation of the immune system is important. The result with the interleukins showed both an increase in the production of inflammatory interleukins as well as in the regulatory interleukins for both TH1 and TH2 cells. Similarities to the immune response described for Candida albicans infections indicate the role of Malassezia in the skin response in seborrhoeic dermatitis and Pityrosporum folliculitis.

Cell-mediated immunity to the mycelial phase of Malassezia spp. in patients with pityriasis versicolor and controls

BACKGROUND

Malassezia is the aetiological agent of pityriasis versicolor. The mycelial phase of the organism predominates in lesions of pityriasis versicolor.

OBJECTIVES

To evaluate the cell-mediated immune (CMI) response to the mycelial phase of Malassezia in patients with this disease, which has not previously been studied.

METHODS

The CMI status of 12 patients with pityriasis versicolor and 12 age- and sex-matched controls to mycelial antigen(s) of the organism was examined. The responses to the mycelial form of three strains of the organism were assessed using lymphocyte transformation and leucocyte migration inhibition assays.

RESULTS

The transformation responses of the lymphocytes from both patients and controls gave transformation indices < or = 3, although the responses of lymphocytes from patients with pityriasis versicolor to the mycelial form of Malassezia strains were generally higher than those of the controls. In the leucocyte migration inhibition assay, leucocytes from patients with pityriasis versicolor and controls responded to the mycelial antigens of three different Malassezia strains; however, there was no significant difference in leucocyte response between patients with pityriasis versicolor and controls.

CONCLUSIONS

Patients with pityriasis versicolor do not therefore have a CMI deficiency to Malassezia mycelial antigens but fail to generate a protective CMI response to mycelial antigens over and above that of control individuals during active disease.

The effects of lipid extraction on the immunomodulatory activity of Malassezia species in vitro

Malassezia spp. are believed to be the causative agents of pityriasis versicolor and are strongly implicated in seborrhoeic dermatitis. The yeast also forms part of the normal human cutaneous microflora. We have previously shown that when Malassezia yeast cells are incubated with human peripheral blood mononuclear cells (PBMCs), they are capable of reducing the levels of pro-inflammatory cytokines produced. In order to test the hypothesis that this immunoevasive phenomenon may be related to the unusually high level of lipid in the Malassezia yeast cell wall, we have compared the immunomodulatory capacity of normal and lipid-depleted yeast cells. Stationary phase yeast cells of Malassezia sympodialis, M. globosa and M. restricta were treated with chloroform/methanol to extract the surface lipids. The lipid-depleted and non-depleted yeast cells were then co-cultured with human PBMCs from three different human donors at a ratio of 20 yeasts per leukocyte for 24 h. The levels of interleukin (IL)-1beta, IL-6 and tumour necrosis factor (TNF)-alpha were then determined by enzyme-linked immunosorbent assay (ELISA). The results demonstrated that extraction of lipid reversed the yeast cell capacity to reduce the levels of pro-inflammatory cytokines. The levels of IL-1beta, IL-6 and TNF-alpha produced in response to lipid-extracted Malassezia of all three species were either no different from or significantly greater (P < 0.05; ANOVA) than the constitutive control levels. These results suggest that the lipid microfibrillar layer of Malassezia may prevent the yeast cells from inducing inflammation and provide an explanation for the normal commensal status of the organism on human skin. The hypothesis that the lipid layer is absent or altered in seborrhoeic dermatitis may provide an explanation for the inflammatory nature of this dermatosis.

Management of seborrheic dermatitis and pityriasis versicolor

Pityriasis (tinea) versicolor and seborrheic dermatitis are two very common skin diseases. Pityriasis versicolor is a chronic superficial fungal disease usually located on the upper trunk, neck, or upper arms. In pityriasis versicolor, the lipophilic yeast Malassezia (also know as Pityrosporum ovale or P. orbiculare) changes from the blastospore form to the mycelial form under the influence of predisposing factors. The most important exogenous factors are high temperatures and a high relative humidity which probably explain why pityriasis versicolor is more common in the tropics. The most important endogenous factors are greasy skin, hyperhidrosis, hereditary factors, corticosteroid treatment and immunodeficiency. There are many ways of treating pityriasis versicolor topically. Options include propylene glycol, ketoconazole shampoo, zinc pyrithione shampoo, ciclopiroxamine, selenium sulfide, and topical antifungals. In difficult cases, short term treatment with fluconazole or itraconazole is effective and well tolerated. To avoid recurrence a prophylactic treatment regimen is mandatory. Seborrheic dermatitis is characterized by red scaly lesions predominantly located on the scalp, face and upper trunk. There are now many studies indicating that Malassezia plays an important role in this condition. Even a normal number of Malassezia will start an inflammatory reaction. Mild corticosteroids are effective in the treatment of seborrheic dermatitis. However, the disease recurs quickly, often within just a few days. Antifungal therapy is effective in the treatment of seborrheic dermatitis and, because it reduces the number of Malassezia, the time to recurrence is increased compared with treatment with corticosteroids. Antifungal therapy should be the primary treatment of this disease.