The diversity and abundance of fungi and bacteria on the healthy and dandruff affected human scalp.
ABSTRACT: Dandruff is a skin condition that affects the scalp of up to half the world's population, it is characterised by an itchy, flaky scalp and is associated with colonisation of the skin by Malassezia spp. Management of this condition is typically via antifungal therapies, however the precise role of microbes in the aggravation of the condition are incompletely characterised. Here, a combination of 454 sequencing and qPCR techniques were used to compare the scalp microbiota of dandruff and non-dandruff affected Chinese subjects. Based on 454 sequencing of the scalp microbiome, the two most abundant bacterial genera found on the scalp surface were Cutibacterium (formerly Propionibacterium) and Staphylococcus, while Malassezia was the main fungal inhabitant. Quantitative PCR (qPCR) analysis of four scalp taxa (M. restricta, M. globosa, C. acnes and Staphylococcus spp.) believed to represent the bulk of the overall population was additionally carried out. Metataxonomic and qPCR analyses were performed on healthy and lesional buffer scrub samples to facilitate assessment of whether the scalp condition is associated with differential microbial communities on the sampled skin. Dandruff was associated with greater frequencies of M. restricta and Staphylococcus spp. compared with the healthy population (p<0.05). Analysis also revealed the presence of an unclassified fungal taxon that could represent a novel Malassezia species.
Project description:The bacterial and fungal communities associated with dandruff were investigated using culture-independent methodologies in the French subjects. The major bacterial and fungal species inhabiting the scalp subject's were identified by cloning and sequencing of the conserved ribosomal unit regions (16S for bacterial and 28S-ITS for fungal) and were further quantified by quantitative PCR. The two main bacterial species found on the scalp surface were Propionibacterium acnes and Staphylococcus epidermidis, while Malassezia restricta was the main fungal inhabitant. Dandruff was correlated with a higher incidence of M. restricta and S. epidermidis and a lower incidence of P. acnes compared to the control population (p<0.05). These results suggested for the first time using molecular methods, that dandruff is linked to the balance between bacteria and fungi of the host scalp surface.
Project description:Several scalp microbiome studies from different populations have revealed the association of dandruff with bacterial and fungal dysbiosis. However, the functional role of scalp microbiota in scalp disorders and health remains scarcely explored. Here, we examined the bacterial and fungal diversity of the scalp microbiome and their potential functional role in the healthy and dandruff scalp of 140 Indian women. Propionibacterium acnes and Staphylococcus epidermidis emerged as the core bacterial species, where the former was associated with a healthy scalp and the latter with dandruff scalp. Along with the commonly occurring Malassezia species (M. restricta and M. globosa) on the scalp, a strikingly high association of dandruff with yet uncharacterized Malassezia species was observed in the core mycobiome. Functional analysis showed that the fungal microbiome was enriched in pathways majorly implicated in cell-host adhesion in the dandruff scalp, while the bacterial microbiome showed a conspicuous enrichment of pathways related to the synthesis and metabolism of amino acids, biotin, and other B-vitamins, which are reported as essential nutrients for hair growth. A systematic measurement of scalp clinical and physiological parameters was also carried out, which showed significant correlations with the microbiome and their associated functional pathways. The results point toward a new potential role of bacterial commensals in maintaining the scalp nutrient homoeostasis and highlights an important and yet unknown role of the scalp microbiome, similar to the gut microbiome. This study, therefore, provides new perspectives on the better understanding of the pathophysiology of dandruff.
Project description:BACKGROUND & OBJECTIVES: Malassezia species implicated with dandruff vary at different geographical locations. The present study was conducted to determine the spectrum and distribution of Malassezia species in dandruff patients and healthy individuals. METHODS: Patients with dandruff from northern (Chandigarh) and southern (Manipal, Karnataka) parts of India (50 each) and healthy individuals (20) were included in the study. Dandruff severity was graded as mild, moderate and severe. Malassezia spp. isolated were quantified and identified by phenotypic characters and molecular methods including PCR-RFLP and DNA sequencing. RESULTS: Number of Malassezia spp. retrieved was significantly higher (P<0.001) in dandruff cases (84%) as compared to healthy individuals (30%). Isolation of Malassezia spp. was significantly higher (P<0.01) in patients from southern India. In moderately severe cases M. restricta was single most predominant (37.8%) isolate from patients of northern part of India and M. furfur (46.4%) from patients of southern part of India. Malassezia density was significantly associated with the severity of dandruff (P<0.001). INTERPRETATION & CONCLUSIONS: Our results on a limited number of individuals show that Malassezia spp. associated with dandruff varies in different regions of the country and the density of yeasts increases with severity of disease.
Project description:Malassezia species are ubiquitous residents of human skin and are associated with several diseases such as seborrheic dermatitis, tinea versicolor, folliculitis, atopic dermatitis, and scalp conditions such as dandruff. Host-Malassezia interactions and mechanisms to evade local immune responses remain largely unknown. Malassezia restricta is one of the most predominant yeasts of the healthy human skin, its cell wall has been investigated in this paper. Polysaccharides in the M. restricta cell wall are almost exclusively alkali-insoluble, showing that they play an essential role in the organization and rigidity of the M. restricta cell wall. Fractionation of cell wall polymers and carbohydrate analyses showed that the polysaccharide core of the cell wall of M. restricta contained an average of 5% chitin, 20% chitosan, 5% ?-(1,3)-glucan, and 70% ?-(1,6)-glucan. In contrast to other yeasts, chitin and chitosan are relatively abundant, and ?-(1,3)-glucans constitute a minor cell wall component. The most abundant polymer is ?-(1,6)-glucans, which are large molecules composed of a linear ?-(1,6)-glucan chains with ?-(1,3)-glucosyl side chain with an average of 1 branch point every 3.8 glucose unit. Both ?-glucans are cross-linked, forming a huge alkali-insoluble complex with chitin and chitosan polymers. Data presented here show that M. restricta has a polysaccharide organization very different of all fungal species analyzed to date.
Project description:Dandruff is a prevalent chronic inflammatory skin condition of the scalp that has been associated with Malassezia yeasts. However, the microbial role has not been elucidated yet, and the etiology of the disorder remains poorly understood. Using high-throughput 16S rDNA and ITS1 sequencing, we characterized cutaneous bacterial and fungal microbiotas from healthy and dandruff subjects, comparing scalp and forehead (lesional and non-lesional skin sites). Bacterial and fungal communities from dandruff analyzed at genus level differed in comparison with healthy ones, presenting higher diversity and greater intragroup variation. The microbial shift was observed also in non-lesional sites from dandruff subjects, suggesting that dandruff is related to a systemic process that is not restricted to the site exhibiting clinical symptoms. In contrast, Malassezia microbiota analyzed at species level did not differ according to health status. A 2-step OTU assignment using combined databases substantially increased fungal assigned sequences, and revealed the presence of highly prevalent uncharacterized Malassezia organisms (>37% of the reads). Although clinical symptoms of dandruff manifest locally, microbial dysbiosis beyond clinically affected skin sites suggests that subjects undergo systemic alterations, which could be considered for redefining therapeutic approaches.
Project description:Most fungal viruses have been identified in plant pathogens, whereas the presence of viral particles in human-pathogenic fungi is less well studied. In the present study, we observed extrachromosomal double-stranded RNA (dsRNA) segments in various clinical isolates of Malassezia species. Malassezia is the most dominant fungal genus on the human skin surface, and species in this group are considered etiological factors of various skin diseases including dandruff, seborrheic dermatitis, and atopic dermatitis. We identified novel dsRNA segments, and our sequencing results revealed that the virus, named MrV40, belongs to the Totiviridae family and contains an additional satellite dsRNA segment encoding a novel protein. The transcriptome of virus-infected Malassezia restricta cells was compared to that of virus-cured cells, and the results showed that transcripts involved in ribosomal biosynthesis were downregulated and those involved in energy production and programmed cell death were upregulated. Moreover, transmission electron microscopy revealed significantly larger vacuoles in virus-infected M. restricta cells, indicating that MrV40 infection dramatically altered M. restricta physiology. Our analysis also revealed that viral nucleic acid from MrV40 induced a TLR3 (Toll-like receptor 3)-mediated inflammatory immune response in bone marrow-derived dendritic cells, suggesting that a viral element contributes to the pathogenicity of Malassezia IMPORTANCE Malassezia is the most dominant fungal genus on the human skin surface and is associated with various skin diseases including dandruff and seborrheic dermatitis. Among Malassezia species, Malassezia restricta is the most widely observed species on the human skin. In the current study, we identified a novel dsRNA virus, named MrV40, in M. restricta and characterized the sequence and structure of the viral genome along with an independent satellite dsRNA viral segment. Moreover, expression of genes involved in ribosomal synthesis and programmed cell death was altered, indicating that virus infection affected the physiology of the fungal host cells. Our data also showed that the viral nucleic acid from MrV40 induces a TLR3-mediated inflammatory immune response in bone marrow-derived dendritic cells, indicating that a viral element likely contributes to the pathogenicity of Malassezia This is the first study to identify and characterize a novel mycovirus in Malassezia.
Project description:Malassezia restricta, one of the predominant basidiomycetous yeasts present on human skin, is involved in scalp disorders. Here, we report the complete genome sequence of the lipophilic Malassezia restricta CBS 7877 strain, which will facilitate the study of the mechanisms underlying its commensal and pathogenic roles within the skin microbiome.
Project description:Malassezia spp in skin microbiome scalp has been implicated in seborrheic dermatitis pathogenesis. Thus, treatment based in antifungal combined to topical keratolitic agents have been indicated as well as oral isotretinoin as it reduces the sebum production, glandular's size and possesses anti-inflammatory properties. This randomized, comparative and therapeutic trial aimed toper form the genotypic identification of Malassezia species before and after low-dose oral isotretinoin or topical antifungal treatments for moderate to severe seborrhea and/or seborrheic dermatitis on scalp. Scales and sebum of the scalp were seeded in the middle of modified Dixon and incubated at 32°C. For genotypic identification polymerase chain reaction primers for the ITS and D1/D2 ribossomal DNA were used and followed by samples sequencing. The procedure was conducted before and after therapeutic and randomized intervention for moderate to severe seborrhea/seborrheic dermatitis on the scalp, including oral isotretinoin, 10 mg, every other day and anti-seborrheic shampoo (piroctone olamine), over six months. The M. globosa and M. restricta were the most frequent species isolated on the scalp before and after both treatments. Other non-Malassezia species were also identified. The Malassezia spp. were maintained in the scalp after both treatments that were equally effective for the control of seborrhea/seborrheic dermatitis clinical signs.
Project description:Dandruff is an unpleasant scalp disorder common to human populations. In this study, we systematically investigated the intra- and inter-associations among dandruff, physiological conditions such as sebum of the scalp, host demographics such as gender, age and the region of the scalp, and the microorganisms on the scalp. We found that the physiological conditions were highly relevant to the host age and varied in different regions of the same scalp. The sebum quantity and water content were negatively correlated with the formation of dandruff and had significant relationships with the two dominant but reciprocally inhibited bacteria on the scalp (Propionibacterium and Staphylococcus). The dominant fungus (Malassezia species) displayed contrary roles in its contribution to the healthy scalp micro-environment. Bacteria and fungi didn't show a close association with each other, but the intramembers were tightly linked. Bacteria had a stronger relationship with the severity of dandruff than fungi. Our results indicated that the severity of dandruff was closely associated with the interactions between the host and microorganisms. This study suggests that adjusting the balance of the bacteria on the scalp, particularly by enhancing Propionibacterium and suppressing Staphylococcus, might be a potential solution to lessen dandruff.
Project description:Dandruff is known to be associated with Malassezia restricta. Zinc pyrithione (ZPT) has been used as an ingredient in anti-dandruff treatments. The mechanism of ZPT has been investigated in several studies; however, a non-pathogenic model yeast, such as Saccharomyces cerevisiae was most often used. The aim of the present study was to understand how ZPT inhibits the growth of M. restricta. We analyzed the cellular metal content and transcriptome profile of ZPT-treated M. restricta cells and found that ZPT treatment dramatically increased cellular zinc levels, along with a small increase in cellular copper levels. Moreover, our transcriptome analysis showed that ZPT inhibits Fe-S cluster synthesis in M. restricta. We also observed that ZPT treatment significantly reduced the expression of lipases, whose activities contribute to the survival and virulence of M. restricta on human skin. Therefore, the results of our study suggest that at least three inhibitory mechanisms are associated with the action of ZPT against M. restricta: (i) an increase in cellular zinc levels, (ii) inhibition of mitochondrial function, and (iii) a decrease in lipase expression.