Malassezia, dandruff and seborrhoeic dermatitis: an overview

Artificial intelligence-based prescription of personalized scalp cosmetics improved the scalp condition: efficacy results from 100 participants

Background: Scalp-related symptoms such as dandruff and itching are common with diverse underlying etiologies. We previously proposed a novel classification and scoring system for scalp conditions, called the scalp photographic index (SPI); it grades five scalp features using trichoscopic images with good reliability. However, it requires trained evaluators.Aim: To develop artificial intelligence (AI) algorithms for assessment of scalp conditions and to assess the feasibility of AI-based recommendations on personalized scalp cosmetics.Methods: Using EfficientNet, convolutional neural network (CNN) models (SPI-AI) ofeach scalp feature were established. 101,027 magnified scalp images graded according to the SPI scoring were used for training, validation, and testing the model Adults with scalp discomfort were prescribed shampoos and scalp serums personalized according to their SPI-AI-defined scalp types. Using the SPI, the scalp conditions were evaluated at baseline and at weeks 4, 8, and 12 of treatment.Results: The accuracies of the SPI-AI for dryness, oiliness, erythema, folliculitis, and dandruff were 91.3%, 90.5%, 89.6%, 87.3%, and 95.2%, respectively. Overall, 100 individuals completed the 4-week study; 43 of these participated in an extension study until week 12. The total SPI score decreased from 32.70 ± 7.40 at baseline to 15.97 ± 4.68 at week 4 (p < 0.001). The efficacy was maintained throughout 12 weeks.Conclusions: SPI-AI accurately assessed the scalp condition. AI-based prescription of tailored scalp cosmetics could significantly improve scalp health.

A Comparative Randomized Clinical Study Assessing the Efficacy of a 1% Selenium Disulfide-Based Shampoo versus 2% Ketoconazole Shampoo in Subjects with Moderate to Severe Scalp Seborrheic Dermatitis

Introduction

Scalp seborrheic dermatitis (SSD) is a chronic, relapsing, and inflammatory condition impacting quality of life (QoL). This study evaluated the efficacy and impact on QoL of a 1% selenium disulphide-containing shampoo (SeS2 shampoo) compared to a 2% ketoconazole shampoo.

Methods

This multi-centric, double-blinded, randomized 4-week study was conducted in 64 adult subjects with moderate to severe SSD (SSD severity score (SSSD) > 6). Shampoo was applied on the scalp and hair, according to product indications. Clinical examinations at baseline and on Day (D) 3, 7, 14, and 28 included the assessment of SSSD, total scales score (TSS, sum of adherent, and non-adherent scales), erythema, irritation, seborrhea, and itching. Self-evaluations included QoL and hair quality assessment (scales and greasiness).

Results

The SSSD improved in both groups as early as D3, after one application of shampoo. This significant (p < 0.001) improvement was -71% for SeS2 and -69% for ketoconazole at D28. The decrease of the TSS was significant (p < 0.001) at D28 in both groups (-75% SeS2 and -68% for ketoconazole). The SSSD severity of all subjects decreased to mild at D28. Signs and symptoms had significantly (p < 0.001) improved in both groups after 28 days. QoL improved earlier with SeS2 than with ketoconazole shampoo. The cosmetic acceptability of SeS2 shampoo was higher than that of ketoconazole shampoo. Both shampoos were very well tolerated.

Conclusion

SeS2 shampoo is a reliable and well-tolerated alternative care to ketoconazole shampoo in patients with moderate to severe scalp seborrheic dermatitis.

Prevalence and associated factors for isolated Malassezia species in patients with Dandruff in Mekelle City, Tigrai, Ethiopia

OBJECTIVE

Dandruff, a condition caused by lipophilic Malassezia fungi, is an excessive shed of dead skin cells from the scalp. Effective preventive and curative measures of the condition depend on knowledge and understanding of the prevalence of the condition, the common etiologic species, and the associated factors. This study aimed to investigate the prevalence, common etiologic species, and associated factors of Malassezia infection in Mekelle City, Ethiopia.

METHOD

A facility-based cross-sectional study was conducted from February 2019 to June 2020 involving 217 participants who were visiting dermatology clinics to seek treatment for dandruff conditions. Information on the socio-demographic characteristics and hair care behaviors of the participants was obtained. Isolation and identification of Malassezia species from scalp scrapings using cultural and biochemical tests were carried out.

RESULTS

Out of the 217 participants with dandruff, 111 (51.15%) were positive for Malassezia fungi. One hundred forty (140) Malassezia isolates were collected from the 111 positive participants. Further study of the isolates yielded three etiologic species: Malassezia globosa (67.15%), M. furfur (21.70%), and M. restricta (12.15%). Demographic characteristics, namely gender (AOR = 2.605; 95%CI: 1.427 - 4.757) and age (AOR = 2.667; 95%CI: 1.046 - 6.795), as well as hair care behaviors, namely use of hair oil (AOR = 2.964; 95%CI: 1.288 - 6.820), were associated with the presence of Malassezia species. However, the use of anti-dandruff shampoo (AOR = 2.782; 95%CI: 1.301 - 10.993) was negatively associated with the presence of Malassezia species among the participants with dandruff conditions. These findings open opportunities to devise effective prevention, management, and control measures for Malassezia-based dandruff conditions.

Efficacy and Safety of Precision Cryotherapy to Treat Seborrheic Dermatitis of the Scalp

BACKGROUND

Recently, a new cryotherapy device that precisely controls skin temperature was developed. Precision cryotherapy (PC) can be a safe and alternative treatment modality for immune-related skin diseases that are difficult to treat by conventional cryotherapy because of serious adverse events.

OBJECTIVE

To evaluate the efficacy and safety of PC in scalp seborrheic dermatitis (SD).

METHODS

A single-arm, prospective trial was designed. Twenty-four patients with SD underwent 3 PC interventions 2 weeks apart. At the baseline, Week 6, and Week 8, overall improvements in Physician Global Assessment (PGA) and clinical severity scores were assessed. At each visit, the erythema index (EI) and transepidermal water loss were evaluated. The patients scored 9 subjective symptoms using a visual analog scale (VAS).

RESULTS

The itch VAS score decreased by 50.4% at Week 8. Blinded investigators reported improvement of PGA scores from 2.86 ± 0.62 to 1.66 ± 0.61 and clinical severity scores from 4.55 ± 1.30 to 2.45 ± 1.37. The average EI decreased by 19.6% at Week 8 ( p < .05).

CONCLUSION

This study not only demonstrated the efficacy and safety of PC in scalp SD but it also revealed insights for PC being a promising treatment modality in immune-related skin diseases.

Clinical efficacy of a gentle anti-dandruff itch-relieving shampoo formulation

Dandruff is a common scalp condition affecting almost half of the world's population. Despite its high prevalence, the exact pathophysiology is not well established and is understood to be multifactorial, with factors such as fungal colonization, sebaceous gland activity and individual factors being implicated. There is a need for an effective and safe shampoo that can target the above factors. Hence, we have developed a shampoo formulation with properties of oil control, moisturizing, non-irritative, anti-fungal, anti-microbial and itch-relieving. In this interventional, open-label study, we evaluated the efficacy and safety of this shampoo in reducing the clinical signs of dandruff and pruritus in patients with pre-existing mild-to-moderate dandruff over a course of 21-day treatment duration through self-assessment and objective clinical evaluations. After continued use of the shampoo, there was a significant decrease in the adherent and loose scalp flaking scores. Mean pruritus scores also decreased significantly across the 21-day time points. There were also no adverse events or skin intolerances reported. This study showed that our shampoo formulation has led to a significant reduction in both adherent and loose scalp flaking and pruritus when used in individuals suffering from mild to moderate dandruff. As such, it is an ideal shampoo, which can be used to effectively control dandruff.

Modes-of-action of antifungal compounds: Stressors and (target-site-specific) toxins, toxicants, or Toxin-stressors

Fungi and antifungal compounds are relevant to the United Nation's Sustainable Development Goals. However, the modes-of-action of antifungals-whether they are naturally occurring substances or anthropogenic fungicides-are often unknown or are misallocated in terms of their mechanistic category. Here, we consider the most effective approaches to identifying whether antifungal substances are cellular stressors, toxins/toxicants (that are target-site-specific), or have a hybrid mode-of-action as Toxin-stressors (that induce cellular stress yet are target-site-specific). This newly described 'toxin-stressor' category includes some photosensitisers that target the cell membrane and, once activated by light or ultraviolet radiation, cause oxidative damage. We provide a glossary of terms and a diagrammatic representation of diverse types of stressors, toxic substances, and Toxin-stressors, a classification that is pertinent to inhibitory substances not only for fungi but for all types of cellular life. A decision-tree approach can also be used to help differentiate toxic substances from cellular stressors (Curr Opin Biotechnol 2015 33: 228-259). For compounds that target specific sites in the cell, we evaluate the relative merits of using metabolite analyses, chemical genetics, chemoproteomics, transcriptomics, and the target-based drug-discovery approach (based on that used in pharmaceutical research), focusing on both ascomycete models and the less-studied basidiomycete fungi. Chemical genetic methods to elucidate modes-of-action currently have limited application for fungi where molecular tools are not yet available; we discuss ways to circumvent this bottleneck. We also discuss ecologically commonplace scenarios in which multiple substances act to limit the functionality of the fungal cell and a number of as-yet-unresolved questions about the modes-of-action of antifungal compounds pertaining to the Sustainable Development Goals.

Efficacy and safety of oral isotretinoin in the treatment of moderate to severe seborrheic dermatitis: a retrospective study

BACKGROUND AND OBJECTIVES

Seborrheic dermatitis is a common, chronic, and recurrent inflammatory skin disease. There are few studies on oral isotretinoin in the treatment of seborrheic dermatitis. The aim of this research was to analyze the efficacy and safety of oral isotretinoin in the treatment of patients with moderate to severe seborrheic dermatitis.

METHODS

This was a retrospective study. All included patients were diagnosed as moderate to severe seborrheic dermatitis and treated with oral isotretinoin from January 2019 to December 2020. Symptom Scale of Seborrheic Dermatitis (SSSD) was used to evaluate the overall severity status of disease.

RESULTS

A total of 48 patients with moderate to severe seborrheic dermatitis were enrolled, of which 26 patients were treated with oral isotretinoin at a dose of 20 mg/day, and 22 patients were treated with oral isotretinoin at a dose of 10 mg/day. The duration of treatment was 2.42 ± 0.98 months (range: 2-6 months). The absolute SSSD values were 10.63 ± 1.02 for all 48 patients, 10.95 ± 1.15 and 10.30 ± 1.11 for patients with a dose of 20 and 10 mg/day, respectively. At the endpoint, there were no significant difference in SSSD values between the two groups (2.21 ± 0.24 vs. 2.35 ± 0.46, P = 0.18). The patients were satisfied with the two treatment schemes, and the difference was not statistically significant (P = 0.78). The most common side effect was cheilitis; however, no serious adverse events occurred in either group.

CONCLUSIONS

When considering efficacy and safety, oral isotretinoin can be used to treat patients with moderate to severe seborrheic dermatitis.

Differential microRNA profiles in elderly males with seborrheic dermatitis

Seborrheic dermatitis (SD) is one of the most common skin diseases characterized by inflammatory symptoms and cell proliferation, which has increased incidence in patients older than 50 years. Although the roles of microRNAs (miRNAs) have been investigated in several diseases, miRNA profiles of patients with SD remain unknown. This study aimed to identify differentially expressed miRNAs (DEMs) in lesions of elderly male patients with SD. We used a microarray-based approach to identify DEMs in lesions compared to those in non-lesions of patients with SD. Furthermore, Gene Ontology and pathway enrichment analysis were performed using bioinformatics tools to elucidate the functional significance of the target mRNAs of DEMs in lesions of patients with SD. Expression levels of two miRNAs-hsa-miR-6831-5p and hsa-miR-7107-5p-were downregulated, whereas those of six miRNAs-hsa-miR-20a-5p, hsa-miR-191-5p, hsa-miR-127-3p, hsa-miR-106b-5p, hsa-miR-342-3p, and hsa-miR-6824-5p-were upregulated. Functions of the SD-related miRNAs were predicted to be significantly associated with typical dermatological pathogenesis, such as cell proliferation, cell cycle, apoptosis, and immune regulation. In summary, SD alters the miRNA profile, and target mRNAs of the DEMs are related to immune responses and cell proliferation, which are the two main processes in SD pathogenesis.

Microbiota differences of skin and pharyngeal microbiota between patients with plaque and guttate psoriasis in China

Psoriasis can be provoked or exacerbated by environmental exposures such as certain microbiomes. The distinction between plaque psoriasis (PP) and guttate psoriasis (GP) in the skin or pharyngeal microbiota is not yet clear. High-throughput sequencing using Illumina MiSeq was used in this study to characterize skin and pharyngeal microbial composition in patients with PP [large PP (LPP, n = 62), small PP (SPP, n = 41)] and GP (n = 14). The alpha- and beta-diversity of skin microbiota LPP was similar to that of the SPP group, but different from the GP group. There were no differences in pharyngeal microbiota among the groups. According to linear discriminant analysis effect size (LEfSe) analysis, Staphylococcus, Stenotrophomonas, Enhydrobacter, Brevundimonas, and Allorhizobium–Neorhizobium–Pararhizobium–Rhizobium were the dominant genera of skin microbiota in PP. Diversity of skin microbiota correlated with Psoriasis Area and Severity Index (PASI). Moderate-to-severe psoriasis and mild psoriasis have different microbiota compositions. The skin microbiota may be related to the pharyngeal microbiota. Furthermore, two microbiota-based models could distinguish psoriasis subtypes with area under the receiver-operating characteristic curve (AUC-ROC) of 0.935 and 0.836, respectively. In conclusion, the skin microbiota in patients with LPP is similar to that in patients with SPP, but displays variations compared to that of GP, no differences are noted between subtypes in pharyngeal microbiota. Skin microbiota diversity correlated with PASI.

The Efficacy and Safety of Pimecrolimus in Patients With Facial Seborrheic Dermatitis: A Systematic Review of Randomized Controlled Trials

Facial seborrheic dermatitis (SD) is a chronic inflammatory skin condition that can affect the quality of life with frequent recurrences. There is no medication as yet to cure this disease completely. There are four general categories of agents that are used to treat SD: antifungal agents, keratolytics, corticosteroids, and lastly calcineurin inhibitors. Topical therapies are the mainstream line of treatment to be used for this skin condition.

The objective of this article is to critically review the published data in the literature on the use of topical pimecrolimus 1% topical cream as an option for treating facial SD. The final purpose of this review is to answer two questions: whether pimecrolimus topical cream is effective for the treatment of SD compared to the conventional current treatments and how safe is this treatment. 

The PubMed, Clinicaltrials.gov, MEDLINE + Embase, and Cochrane library databases were searched for original randomized clinical trials (RCTs) evaluating pimecrolimus 1% topical cream and comparing it with other topical treatments for SD. A systematic review and meta-analysis were then conducted on the selected studies by grading the evidence and qualitative comparison of results among and within studies. A total of five studies were included in the review; however, only four were eligible for inclusion in the meta-analysis, in which pimecrolimus was compared with other treatments for the management of facial SD.

Pimecrolimus was found to be an effective topical treatment for facial SD, as it showed considerable desirable control of the symptoms in patients with facial SD clinically, in addition to a lower recurrence or relapsing rates; however, it had more side effects compared to other topical treatments, but the side effects were mild and tolerable.

Amplicon-based sequencing and co-occurence network analysis reveals notable differences of microbial community structure in healthy and dandruff scalps

Background

Dandruff is a chronic, recurring, and common scalp problem that is caused by several etiopathogeneses with complex mechanisms. Management of this condition is typically achieved via antifungal therapies. However, the precise roles played by microbiota in the development of the condition have not been elucidated. Despite their omnipresence on human scalp little is known about the co-occurrence/co-exclusion network of cutaneous microbiota.

Results

We characterized the scalp and hair surface bacterial and fungal communities of 95 dandruff-afflicted and healthy individuals residing in China. The degree distributions of co-occurrence/co-exclusion network in fungi-bacteria and bacteria-bacteria were higher in the healthy group (P < 0.0001), whereas the betweenness values are higher in the dandruff group (P < 0.01). Meanwhile, the co-occurrence/co-exclusion network among fungi-fungi and fungi-bacteria showed that compared to the healthy group, the dandruff group had more positive links (P < 0.0001). In addition, we observed that Malassezia slooffiae, Malassezia japonica and Malassezia furfur, were more abundant in the dandruff group than in the healthy group. These microbiota were co-exclusion by either multiple bacterial genera or Malassezia sp. in healthy group. The lactic acid bacteria on the scalp and hair surface, especially the genera Lactobacillus and Lactococcus, exhibit a negative correlation with multiple bacterial genera on the scalp and hair surface. Lactobacillus plantarum and Pediococcus lactis isolated on the healthy human scalp can inhibit the growth of Staphylococcus epidermidis in vitro.

Conclusions

We showed that microbial networks on scalp and hair surface with dandruff were less integrated than their healthy counterparts, with lower node degree and more positive and stronger links which were deemed to be unstable and may be more susceptible to environmental fluctuations. Lactobacillus bacteria have extensive interactions with other bacteria or fungi in the scalp and hair surface micro-ecological network and can be used as targets for improving scalp health.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08534-4.

The Antibiofilm Nanosystems for Improved Infection Inhibition of Microbes in Skin

Biofilm formation is an important virulence factor for the opportunistic microorganisms that elicit skin infections. The recalcitrant feature of biofilms and their antibiotic tolerance impose a great challenge on the use of conventional therapies. Most antibacterial agents have difficulty penetrating the matrix produced by a biofilm. One novel approach to address these concerns is to prevent or inhibit the formation of biofilms using nanoparticles. The advantages of using nanosystems for antibiofilm applications include high drug loading efficiency, sustained or prolonged drug release, increased drug stability, improved bioavailability, close contact with bacteria, and enhanced accumulation or targeting to biomasses. Topically applied nanoparticles can act as a strategy for enhancing antibiotic delivery into the skin. Various types of nanoparticles, including metal oxide nanoparticles, polymeric nanoparticles, liposomes, and lipid-based nanoparticles, have been employed for topical delivery to treat biofilm infections on the skin. Moreover, nanoparticles can be designed to combine with external stimuli to produce magnetic, photothermal, or photodynamic effects to ablate the biofilm matrix. This study focuses on advanced antibiofilm approaches based on nanomedicine for treating skin infections. We provide in-depth descriptions on how the nanoparticles could effectively eliminate biofilms and any pathogens inside them. We then describe cases of using nanoparticles for antibiofilm treatment of the skin. Most of the studies included in this review were supported by in vivo animal infection models. This article offers an overview of the benefits of nanosystems for treating biofilms grown on the skin.

Host/Malassezia Interaction: A Quantitative, Non-Invasive Method Profiling Oxylipin Production Associates Human Skin Eicosanoids with Malassezia

Malassezia are common components of human skin, and as the dominant human skin eukaryotic microbe, they take part in complex microbe-host interactions. Other phylogenetically related fungi (including within Ustilagomycotina) communicate with their plant host through bioactive oxygenated polyunsaturated fatty acids, generally known as oxylipins, by regulating the plant immune system to increase their virulence. Oxylipins are similar in structure and function to human eicosanoids, which modulate the human immune system. This study reports the development of a highly sensitive mass-spectrometry-based method to capture and quantify bioactive oxygenated polyunsaturated fatty acids from the human skin surface and in vitro Malassezia cultures. It confirms that Malassezia are capable of synthesizing eicosanoid-like lipid mediators in vitro in a species dependent manner, many of which are found on human skin. This method enables sensitive identification and quantification of bioactive lipid mediators from human skin that may be derived from metabolic pathways shared between skin and its microbial residents. This enables better cross-disciplinary and detailed studies to dissect the interaction between Malassezia and human skin, and to identify potential intervention points to promote or abrogate inflammation and to improve human skin health.

A folliculocentric perspective of dandruff pathogenesis: Could a troublesome condition be caused by changes to a natural secretory mechanism?

Dandruff is a common scalp condition, which frequently causes psychological distress in those affected. Dandruff is considered to be caused by an interplay of several factors. However, the pathogenesis of dandruff remains under-investigated, especially with respect to the contribution of the hair follicle. As the hair follicle exhibits unique immune-modulatory properties, including the creation of an immunoinhibitory, immune-privileged milieu, we propose a novel hypothesis taking into account the role of the hair follicle. We hypothesize that the changes and imbalance of yeast and bacterial species, along with increasing proinflammatory sebum by-products, leads to the activation of immune response and inflammation. Hair follicle keratinocytes may then detect these changes in scalp microbiota resulting in the recruitment of leukocytes to the inflammation site. These changes in the scalp skin immune-microenvironment may impact hair follicle immune privilege status, which opens new avenues into exploring the role of the hair follicle in dandruff pathogenesis. Also see the video abstract here: https://youtu.be/mEZEznCYtNs.

Oxidative stress and its impact on skin, scalp and hair

Oxidative stress is an unbalanced condition in which the tissues of the body are not sufficiently able to counteract either exogenous or endogenous sources of reactive oxygen species. Oxidative stress is strongly associated with ageing, both local and systemic, as well as a wide range of local health conditions. This review focuses on the oxidative stress data known for skin, scalp and hair. This oxidative stress may be the 'currency' by which an unhealthy scalp leads to deleterious consequences to the hair. The ramifications of this scalp oxidative stress to normal hair elongation, retention and replacement are discussed.

Continuous clinical improvement of mild-to-moderate seborrheic dermatitis and rebalancing of the scalp microbiome using a selenium disulfide-based shampoo after an initial treatment with ketoconazole

OBJECTIVE

Scalp seborrheic dermatitis (SD) is a chronic, relapsing, and inflammatory scalp disease. Studies indicate a global bacterial and fungal microbiota shift of scalp SD, as compared to healthy scalp. Ketoconazole and selenium disulfide (SeS₂ ) improve clinical signs and symptoms in both scalp dandruff and SD.

AIM

The main objective of this study was to investigate the changes in the scalp microbiota diversity and counts in subjects with scalp SD during a two-phase treatment period.

MATERIAL AND METHODS

The scalp microbiota and clinical efficacy were investigated in 68 subjects with mild-to-moderate scalp SD after an initial one-month treatment with 2% ketoconazole, and after a 2-month maintenance phase, either with a 1% SeS₂ -based shampoo or its vehicle.

RESULTS

Thirty one subjects in the active and 37 subjects in the vehicle group participated. Ketoconazole provided an improvement of clinical symptoms (adherent (-1.75 p < 0.05), non-adherent (-1.5, p < 0.05)) flakes and erythema (scores 1.67-0.93, p < 0.001), in an increased fungal diversity and in a significant (p < 0.005) decrease of Malassezia spp. SeS₂ provided an additional clinical improvement (-0.8; p = 0.0002 and -0.7; p = 0.0081 for adherent and non-adherent flakes, respectively, at Day 84) compared to the vehicle associated with a low Malassezia spp. count and an additional significant (p < 0.001) decrease of the Staphylococcus spp. level.

CONCLUSION

Selenium disulfide provides an additional benefit on the scalp microbiota and in clinical symptoms of SD and dandruff after treatment with ketoconazole. The results confirm the role of Staphylococcus spp. in scalp SD and open possible perspectives for preventing relapses.

Biofilm formation, adherence, and hydrophobicity of M. sympodialis, M. globosa, and M. slooffiae from clinical isolates and normal skinVirulence factors of M. sympodialis, M. globosa and M. slooffiae

The genus Malassezia comprises a heterogeneous group of species that cause similar pathologies. Malassezia yeasts were considered as the most abundant skin eukaryotes of the total skin mycobiome. The ability of this fungus to colonize or infect is determined by complex interactions between the fungal cell and its virulence factors. This study aims to evaluate in vitro the hydrophobicity levels, the adherence capacity on a polystyrene surface and the ability to form biofilm of 19 isolates, including M. sympodialis, M. globosa, and M. slooffiae, from healthy subjects and from dermatological disorders. Cellular surface hydrophobicity levels were determined by two-phase system. The biofilm formation was determined by tetrazolium salt (XTT) reduction assay and by Scanning Electron Microscopy (SEM). Strain dependence was observed in all virulence factors studied. All isolates of M. sympodialis, M. globosa, and M. slooffiae demonstrated their ability to form biofilm at variable capacities. SEM observations confirmed a variable extracellular matrix after 48 hours of biofilm formation. All isolates of M. globosa were highly adherent and/or hydrophobic as well as biofilm producers. In contrast, M. slooffiae was the least biofilm producer. No significant differences between virulence factors were demonstrated for M. sympodialis, either as clinical isolate or as inhabitant of human microbiota. Results of this work together with the previous M. furfur research confirm that the most frequently Malassezia species isolated from normal subject's skin and patients with dermatosis, form biofilm with different capacities. The study of these virulence factors is important to highlight differences between Malassezia species and to determine their involvement in pathological processes.

Treatment of cradle cap in infants with a new cosmetic non-steroidal gel cream: Clinical, laboratory, and instrumental evaluation

Background

Cradle cap is a benign and self‐limiting variant of seborrheic dermatitis (SD) that can be distressing for parents.

Aims

To assess by clinical/laboratory/instrumental evaluation the efficacy/tolerability of a gel cream containing piroctone olamine (antifungal), biosaccharide gum‐2 (antifungal), stearyl glycyrrhetinate (anti‐inflammatory), and zinc l‐pyrrolidone carboxylate (zinc‐PCA) (antiseborrheic) in the treatment of mild/ moderate cradle cap.

Methods

In this prospective, open‐label trial, 10 infants, with mild/moderate cradle cap enrolled at the Dermatology University Clinic of Catania (Italy) used the tested gel cream twice daily for 30 days. Degree of erythema was evaluated clinically by a 5‐point severity scale (from 0=no erythema to 4=severe erythema), at baseline, at 15 and 30 days. Desquamation was rated by dermoscopy evaluation using a 5‐point scale (from 0=no desquamation to 4=severe/many large adherent white flakes), at all time points. An Investigator Global Assessment (IGA) using a 6‐point scale (from −1=worsening to 4=complete response/clear) was also performed at 30 days. Five subjects, randomly selected, underwent double microbiological evaluation for bacteria and yeasts by cultures of cotton swabs at baseline and at 30 days. Tolerability/acceptability was evaluated on a 4‐point scale (from 0=very poor to 3=excellent) at 15 and 30 days. Data were processed using SAS version 9.

Results

At baseline, a significant colony‐forming unit (CFU) count for Malassezia furfur and Staphylococcus aureus was detected in 4 out of 5 selected patients. After 15 and 30 days, a statically significant reduction from baseline in erythema and desquamation severity was observed, along with a reduction in CFU count for Malassezia furfur and Staphylococcus aureus from baseline. No signs of local side effects were documented.

Conclusions

Our results indicate that the tested gel cream may represent a valid option to treat mild‐to‐moderate forms of cradle cap and support its antifungal and antibacterial properties.

A Highlight on the Inhibition of Fungal Carbonic Anhydrases as Drug Targets for the Antifungal Armamentarium

Carbon dioxide (CO2), a vital molecule of the carbon cycle, is a critical component in living organisms' metabolism, performing functions that lead to the building of compounds fundamental for the life cycle. In all living organisms, the CO2/bicarbonate (HCO3-) balancing is governed by a superfamily of enzymes, known as carbonic anhydrases (CAs, EC 4.2.1.1). CAs catalyze the pivotal physiological reaction, consisting of the reversible hydration of the CO2 to HCO3- and protons. Opportunistic and pathogenic fungi can sense the environmental CO2 levels, which influence their virulence or environmental subsistence traits. The fungal CO2-sensing is directly stimulated by HCO3- produced in a CA-dependent manner, which directly activates adenylyl cyclase (AC) involved in the fungal spore formation. The interference with CA activity may impair fungal growth and virulence, making this approach interesting for designing antifungal drugs with a novel mechanism of action: the inhibition of CAs linked to the CO2/HCO3-/pH chemosensing and signaling. This review reports that sulfonamides and their bioisosteres as well as inorganic anions can inhibit in vitro the β- and α-CAs from the fungi, suggesting how CAs may be considered as a novel "pathogen protein" target of many opportunistic, pathogenic fungi.

Keratinocyte IL-36 Receptor/MyD88 Signaling Mediates Malassezia-Induced IL-17-Dependent Skin Inflammation

BACKGROUND

Among skin commensal fungi, lipophilic Malassezia species exist on nearly all human skin surfaces. The pathophysiology of Malassezia-associated skin diseases remains poorly understood due in part to the lack of appropriate animal models. Our objective was to investigate the mechanisms underlying Malassezia-induced skin inflammation using a novel murine model that physiologically recapitulates Malassezia skin infection.

METHODS

Mice were inoculated epicutaneously with Malassezia yeasts without barrier disruption and in the absence of external lipid supplementation. Skin inflammation, lesional fungal loads, and expression of cytokines and antimicrobial peptides were evaluated in wild-type and mutant mouse strains.

RESULTS

Malassezia-induced skin inflammation and epidermal thickening were observed on day 4 after inoculation in wild-type mice. High fungal burdens were detected in the cornified layer on day 2 and decreased thereafter with near complete clearance by day 7 after inoculation. Malassezia-induced skin inflammation and fungal clearance by the host were interleukin-17 (IL-17) dependent with contribution of group 3 innate lymphoid cells. Moreover, IL-17-dependent skin inflammation was mediated through IL-36 receptor and keratinocyte MyD88 signaling.

CONCLUSION

Using a new skin infection model, it is shown that Malassezia-induced IL-17- dependent skin inflammation and control of fungal infection are mediated via keratinocyte IL-36 receptor/MyD88 signaling.

Longitudinal study of the scalp microbiome suggests coconut oil to enrich healthy scalp commensals

Dandruff is a recurrent chronic scalp disorder, affecting majority of the population worldwide. Recently a metagenomic study of the Indian scalp microbiome described an imperative role of bacterial commensals in providing essential vitamins and amino acids to the scalp. Coconut oil and its formulations are commonly applied on the scalp in several parts of the world to maintain scalp health. Thus, in this study we examined the effect of topical application of coconut oil on the scalp microbiome (bacterial and fungal) at the taxonomic and functional levels and their correlation with scalp physiological parameters. A 16-weeks-long time-course study was performed including 12-weeks of treatment and 4-weeks of relapse phase on a cohort of 140 (70 healthy and 70 dandruff) Indian women, resulting in ~ 900 metagenomic samples. After the treatment phase, an increase in the abundance of Cutibacterium acnes and Malassezia globosa in dandruff scalp was observed, which were negatively correlated to dandruff parameters. At the functional level, an enrichment of healthy scalp-related bacterial pathways, such as biotin metabolism and decrease in the fungal pathogenesis pathways was observed. The study provides novel insights on the effect of coconut oil in maintaining a healthy scalp and in modulating the scalp microbiome.

Development and Validation of a Complexometric and Potentiometric Titration Method for the Quantitative Determination of Zinc Pyrithione in Shampoo

Most of the pharmaceutical and cosmetic products used for the treatment of dandruff have zinc pyrithione as an active ingredient; therefore; quantifying this component becomes necessary. The purpose of this study was the validation of two simple and fast methodologies in the quantification of zinc pyrithione for shampoo quality control to guarantee consumer safety. The first method comprised a manual complexometric titration, and the second comprised a potentiometric titration performed with an automatic titrator, obtaining sensitivity values of 0.0534% and 0.0038%, respectively, precision expressed in RSD% values below than 1%, and accuracy in recovery percentage greater than 99%. Additionally, both methods were robust when subjected to significant changes in working conditions (temperature and pH) and were selective even in the presence of interferences and degradation products. Finally, the methodologies were adequate to ensure the quality of shampoo to ensure the safety of consumers.

Experimental Study of Therapeutic Efficacy of the Topical Preparation «Kourochitin» in Skin Allergy

Background:

The researchers of PIBOC RAS developed the dermo-protective topical drug called «Kourochitin», active substance of which is known quinazoline alkaloid tryptanthrin. In the present work, therapeutic efficacy of this drug in the treatment of allergic dermatosis was evaluated.

Methods:

Dermo-protective action of «Kourochitin» was studied in tow murine models: 2, 4- dinitrofluorobenzene- induced allergic contact dermatitis (ACD) and imiquimod-induced psoriasis.

Results and Discussion:

In a model ACD, it was shown that «Kourochitin» exhibits the curative action on pathophysiological, hematological and immunological parameters in ACD. Namely, «Kourochitin» 1) reduces the level of erythema in the allergen damaged skin area and increases the healing index of the epidermis; 2) normalizes the content of eosinophils, basophils and monocytes in the blood of experimental animals; 3) inhibits the production of main pro-inflammatory cytokines: interleukins - 1 and 2, interferon-gamma, and granulocyte-macrophage colony-stimulating factor. In a murine model of imiquimod-induced psoriasis, it was shown that «Kourochitin» application led to reduction in psoriasis severity on the inflamed epidermis of experimental animals. Additionally, in veterinary research, «Kourochitin»-treatment of canine atopic dermatitis almost completely eliminated signs of allergic manifestations on the epidermis.

Conclusion:

The obtained data suggest that «Kourochitin» as anti-inflammatory, anti-allergic, and wound healing remedy is a potential drug for therapy of various dermatological diseases, in particular allergic skin lesions.

An update on the microbiology, immunology and genetics of seborrheic dermatitis

The underlying mechanism of seborrheic dermatitis (SD) is poorly understood but major scientific progress has been made in recent years related to microbiology, immunology and genetics. In light of this, the major goal of this article was to summarize the most recent articles on SD, specifically related to underlying pathophysiology. SD results from Malassezia hydrolysation of free fatty acids with activation of the immune system by the way of pattern recognition receptors, inflammasome, IL-1β and NF-kB. M. restricta and M. globosa are likely the most virulent subspecies, producing large quantities of irritating oleic acids, leading to IL-8 and IL-17 activation. IL-17 and IL-4 might play a big role in pathogenesis, but this needs to be further studied using novel biologics. No clear genetic predisposition has been established; however, recent studies implicated certain increased-risk human leucocyte antigen (HLA) alleles, such as A*32, DQB1*05 and DRB1*01 as well as possible associations with psoriasis and atopic dermatitis (AD) through the LCE3 gene cluster while SD, and SD-like syndromes, shares genetic mutations that appear to impair the ability of the immune system to restrict Malassezia growth, partially due to complement system dysfunction. A paucity of studies exists looking at the relationship between SD and systemic disease. In HIV, SD is thought to be secondary to a combination of immune dysregulation and disruption in skin microbiota with unhindered Malassezia proliferation. In Parkinson's disease, SD is most likely secondary to parasympathetic hyperactivity with increased sebum production as well as facial immobility which leads to sebum accumulation.

Malassezia and Staphylococcus dominate scalp microbiome for seborrheic dermatitis

Seborrheic dermatitis (SD) is a common disease of the human scalp that causes physical damage and psychological problems for patients. Studies have indicated that dysbiosis of the scalp microbiome results in SD. However, the specific fungal and bacterial microbiome changes related to SD remain elusive. To further investigate the fungal and bacterial microbiome changes associated with SD, we recruited 57 SD patients and 53 healthy individuals and explored their scalp microbiomes using next generation sequencing and the QIIME and LEfSe bioinformatics tools. Skin pH, sebum secretion, hydration, and trans-epidermal water loss (TWEL) were also measured at the scalp. We found no statistically significant differences between the normal and lesion sites in SD patients with different subtypes of dandruff and erythema. However, the fungal and bacterial microbiome could differentiate SD patients from healthy controls. The presence of Malassezia and Aspergillus was both found to be potential fungal biomarkers for SD, while Staphylococcus and Pseudomonas were found to be potential bacterial biomarkers. The fungal and bacterial microbiome were divided into three clusters through co-abundance analysis and their correlations with host factors indicated the interactions and potential cooperation and resistance between microbe communities and host. Our research showed the skin microbe dysbiosis of SD and highlighted specific microorganisms that may serve as potential biomarkers of SD. The etiology of SD is multi-pathogenetic-dependent on the linkage of several microbes with host. Scalp microbiome homeostasis could be a promising new target in the risk assessment, prevention, and treatment of SD disease.

Exploring Anti-Fungal, Anti-Microbial and Anti-Inflammatory Properties of a Topical Non-Steroidal Barrier Cream in Face and Chest Seborrheic Dermatitis

INTRODUCTION

The pathogenesis of seborrheic dermatitis (SD) is multifactorial and traditional treatments may not target all aspects of it. The aim of this study was to evaluate short-term anti-fungal, anti-microbial, anti-inflammatory and anti-pruritus properties of a novel non-steroidal cream (NSC) containing piroctone olamine, zinc salt of L-pyrrolidone carboxylate (PCA), hydroxyphenyl propamidobenzoic acid, biosaccharide gum-2 and stearyl glycyrrhetinate in patients with face and chest SD.

METHODS

Twelve male subjects affected by SD, presenting face and chest manifestations, were enrolled. Patients were instructed to apply NSC twice a day, performing regular visits at baseline (W0), after 7 (W1) and 14 (W2) days of treatment. A limitation of the study was that no control group treated with the vehicle without active ingredients was enrolled. To evaluate the efficacy of the NSC, investigator's assessments were represented by scoring index (SI) and investigator's global assessment score (IGA). In order to assess NSC anti-fungal and anti-microbial effects, skin scale scrapings were collected and used for Malassezia furfur (MF) and Staphylococcus epidermidis (SE) cultures. In parallel, in order to assess NSC anti-inflammatory effects, gene expression of IL-1α, IL-1β, IL-6, IL-8, and TNF-α was assessed. In addition, anti-pruritus effects were also evaluated through gene expression of cathepsin S and L-histidine decarboxylase.

RESULTS

SI mean scores significantly decreased at W1 and, to a greater extent, at W2 compared with W0. The IGA score registered an important improvement efficacy both for face and chest, from W1 to W2. MF and SE growth was already inhibited at W1, with a more pronounced decrease at W2. Gene expression of all analyzed mediators was significantly reduced at W1 compared to W0.

CONCLUSION

In conclusion, our assessment is that NSC is an effective and well tolerated treatment option for SD with anti-fungal, anti-microbial and anti-inflammatory properties.

TRIAL REGISTRATION

ISRCTN registry, ISRCTN77871064 (retrospectively registered October 17, 2019). EudraCT number, 2019-003813-32.

FUNDING

ISDIN.

Sulfonamide Inhibition Profile of the β-Carbonic Anhydrase from Malassezia restricta, An Opportunistic Pathogen Triggering Scalp Conditions

The critical CO₂ hydration reaction to bicarbonate and protons is catalyzed by carbonic anhydrases (CAs, EC 4.2.1.1). Their physiological role is to assist the transport of the CO₂ and HCO₃⁻ at the cellular level, which will not be ensured by the low velocity of the uncatalyzed reaction. CA inhibition may impair the growth of microorganisms. In the yeasts, Candida albicans and Malassezia globosa, the activity of the unique β-CA identified in their genomes was demonstrated to be essential for growth of the pathogen. Here, we decided to investigate the sulfonamide inhibition profile of the homologous β-CA (MreCA) identified in the genome of Malassezia restricta, an opportunistic pathogen triggering dandruff and seborrheic dermatitis. Among 40 investigated derivatives, the best MreCA sulfonamide inhibitors were dorzolamide, brinzolamide, indisulam, valdecoxib, sulthiam, and acetazolamide (K_I < 1.0 μM). The MreCA inhibition profile was different from those of the homologous enzyme from Malassezia globosa (MgCA) and the human isoenzymes (hCA I and hCA II). These results might be useful to for designing CA inhibitor scaffolds that may selectively inhibit the dandruff-producing fungi.

Serum zinc levels in seborrheic dermatitis: a case-control study

Background/aim

Malassezia colonization, sebaceous gland activity, hormones, immune system defects, environmental factors, and the interactions between these factors are thought to contribute to the pathogenesis of seborrheic dermatitis (SD). Zinc, an essential element, is involved in many biological processes including the ones that contribute to the development of SD. The aim of this study is to evaluate serum zinc levels in patients with SD.

Materials and methods

Forty-three patients with SD and 41 healthy controls were enrolled in the study. Disease activity was assessed by the Seborrheic Dermatitis Area and Severity Index by a single dermatologist. Serum zinc levels of all subjects were evaluated.

Results

Statistically significantly lower serum zinc levels were noted in SD patients than in the control group (79.16 ± 12.17 vs. 84.88 ± 13.59, respectively; P = 0.045).

Conclusion

The results of the study demonstrated that patients who had SD had lower levels of serum zinc levels than healthy subjects.

Isolation of Malassezia spp. in HIV-positive patients with and without seborrheic dermatitis

Background

Malassezia, a skin saprophyte, is frequently isolated from patients with seborrheic dermatitis, which is one of the most common dermatoses in HIV-infected patients. Its role in pathophysiology has not been defined.

Objective

To determine whether patients living with HIV and seborrheic dermatitis have more Malassezia than those without seborrheic dermatitis.

Method

This is an descriptive, observational, prospective cross-sectional study to which all adult patients living with HIV that attend the infectious disease outpatient clinic at the Dr. Manuel Gea González General Hospital were invited. Patients presenting with scale and erythema were included in Group 1, while patients without erythema were included in Group 2. Samples were taken from all patients for smear and culture.

Results

Thirty patients were included in each group. All patients with seborrheic dermatitis had a positive smear, with varying amounts of yeasts. In the control group, 36.7% of patients had a negative smear. The results are statistically significant, as well as the number of colonies in the cultures.

Study limitations The study used a small sample size and the subspecies were not identified.

Conclusions

Patients with clinical manifestations of seborrheic dermatitis have larger amounts of Malassezia. Further studies need to be performed to analyze if the greater amount is related to imbalances in the microbiota of the skin.

Changes in epidermal morphology associated with dandruff

OBJECTIVE

Dandruff is a very common scalp condition characterized by flaking and pruritus usually with no visible signs of inflammation, such as redness and erythema. Dandruff is considered a multifactorial condition with both microbial colonization and host factors such as sebum production thought to play a role. There is evidence of changes in epidermal morphology in the scalp skin of dandruff sufferers, with reports of an increase in mean thickness and more nucleated cell layers. The underlying mechanisms driving these morphological changes are currently unclear. The objective of this study was to fully characterize epidermal morphology in dandruff compared to healthy scalp skin and to evaluate potential mechanisms underlying any changes observed.

METHODS

Scalp skin biopsies were taken from 22 healthy female subjects and 21 dandruff sufferers, from both lesional and non-lesional sites. Samples were processed, sectioned and stained using haematoxylin and eosin (H&E). To fully characterize epidermal morphology, measurements were taken of epidermal thickness, the convolution of the dermal-epidermal junction and the depth of epidermal rete ridges. To analyse changes in epidermal proliferation immunohistochemical staining was performed using Ki67, a well-established marker of cell proliferation, and quantified using image analysis.

RESULTS

Histochemical analysis of skin sections revealed that in dandruff lesional samples, the epidermis was thicker, had a more convoluted dermal epidermal junction and the rete ridges were elongated, compared to healthy scalp skin. Similar directional changes in epidermal morphology, were observed in non-lesional dandruff samples, albeit to a lesser extent. Image analysis of Ki67 expression in the epidermis revealed dandruff lesional skin contained significantly more Ki67-positive proliferating keratinocytes than healthy controls samples. This suggests dandruff scalp skin epidermal keratinocytes are in a hyper-proliferative state.

CONCLUSION

There were significant changes in epidermal morphology in dandruff lesional skin compared to healthy scalp skin including increased epidermal thickness, a more convoluted dermal-epidermal junction and elongation of rete ridges. Interestingly, we found there was evidence of an increase in the percentage of epidermal Ki67-positive cells, which has not been reported previously, and demonstrates dandruff is a condition displaying epidermal hyper-proliferation.

Comparison of efficacy and safety of atorvastatin 5% lotion and betamethasone 0.1% lotion in the treatment of scalp seborrheic dermatitis

Purpose: Seborrheic dermatitis (SD) is a chronic inflammatory skin disorder that mainly affects areas rich in sebaceous glands, such as the scalp. Although the exact cause of SD is not clearly understood, it seems that skin colonization with Malassezia fungus and the inflammatory responses of the immune system to this fungus play an important role in the pathology of SD. Recently a growing body of evidence has shown anti-inflammatory and anti-fungal effects of statins. Thus, this study aimed to evaluate the efficacy of topical atorvastatin in the treatment of scalp SD.

Patients and methods: In this double-blind, clinical trial, 86 patients with mild-to-moderate scalp SD were divided into either atorvastatin (n=45) or betamethasone groups (n=41) by block randomization method. In addition to the ketoconazole 2% shampoo (3 times per week), the atorvastatin group received atorvastatin 5% lotion and the betamethasone group received betamethasone 0.1% lotion daily for 4 weeks. The SD severity of each patient was determined by Symptom Scale of Seborrheic Dermatitis (SSSD) at baseline and 4 weeks after treatment. Also, the patient’s satisfaction of the treatment and adverse effects were investigated through individual reporting.

Results: After 4 weeks of treatment, the score of SD severity decreased significantly in both groups, while changes of SSSD score from baseline to the fourth week of treatment were comparable in the two groups (P-value=0.476). Regarding patient’s satisfaction of the treatment, results demonstrated the non-inferiority of atorvastatin as compared to betamethasone. Topical atorvastatin was also well-tolerated in almost all patients.

Conclusion: Although preliminary, the results of the present study showed that topical atorvastatin has a comparable effect to topical betamethasone and can be considered as an alternative therapeutic modality in the treatment of scalp SD. However, these results need to be confirmed in future studies while taking into consideration the improvement of topical statin formulations.

Mechanisms of microbial pathogenesis and the role of the skin microbiome in psoriasis: A review

The pathogenesis of psoriasis may involve a breakdown of immune tolerance to cutaneous microorganisms. Psoriasis is associated with a higher incidence of Crohn disease and periodontitis, two diseases involving impaired tolerance and abnormal immune activation in response to intestinal and oral microbiota, respectively. In addition, guttate and chronic plaque psoriasis are associated with Streptococcus pyogenes colonization. The aim of this review is to characterize the microorganisms implicated in psoriasis by examining results of major association studies and possible mechanisms of pathogenesis. Although studies show relative increases in Streptococcus and Staphylococcus and decreases in Malassezia and Cutibacterium, they differ in methods of sampling and methods of microbial analysis. As such, no definitive associations between microbes and psoriasis have been found to date. It also remains unclear if changes in the microbiomal composition have a causal association with psoriasis or are simply a consequence of the inflammatory microenvironment. Techniques enabling strain-level analysis rather than species-level analysis of the skin microbiome are likely necessary to determine microbiomal signatures of psoriasis. Future investigations may lead to new diagnostic tests and novel treatments, such as probiotics or bacterial transplantation.

Topical delivery of climbazole to mammalian skin

Dandruff is a common condition, affecting up to half the global population of immunocompetent adults at some time during their lives and it has been highly correlated with the over-expression of the fungus Malassezia spp. Climbazole (CBZ) is used as an antifungal and preservative agent in many marketed formulations for the treatment of dandruff. While the efficacy of CBZ in vitro and in vivo has previously been reported, limited information has been published about the uptake and deposition of CBZ in the skin. Hence, our aim was to investigate the skin permeation of CBZ as well as the influence of various solvents on CBZ skin delivery. Four solvents were selected for the permeability studies of CBZ, namely propylene glycol (PG), octyl salicylate (OSal), Transcutol® P (TC) and polyethylene glycol 200 (PEG). The criteria for selection were based on their wide use as excipients in commercial formulations, their potential to act as skin penetration enhancers and their favourable safety profiles. 1% (w/v) solutions of CBZ were applied under infinite and finite dose conditions using Franz type diffusion cells to human and porcine skin. In line with the topical use of CBZ as an antidandruff agent, comparatively low amounts of CBZ penetrated across the skin barrier (<1% of the applied dose of CBZ). Finite dose studies resulted in a higher extraction of CBZ from human skin compared with infinite dose studies (p < 0.05). CBZ was also taken up to a higher extent in porcine skin (>7-fold) compared with human skin (p < 0.05). Nevertheless, no statistical differences were observed in the amounts that permeated across the different membranes. These preliminary results confirm the potential of simple formulations of CBZ to target the outer layers of the epidermis. The PG and OSal formulations appear to be promising vehicles for CBZ in terms of overall skin extraction and penetration. Future work will expand the range of vehicles studied and explore the reasons underlying the retention of CBZ in the outer layers of the skin.

Putting It All Together to Understand the Role of Malassezia spp. in Dandruff Etiology

Dandruff is a common scalp condition causing both a discomfort and an undesired social image. Various studies dating from early 1900s have investigated the condition, but understanding of underlying mechanisms and etiology of the condition is still in its infancy. Formation of dandruff is a common but complex event which has been associated with numerous causal factors. Physiological conditions such as pH, water content, or sebum secretion are some of the host-related factors. An imbalance between these factors can disturb the physiological equilibrium of the scalp that can lead to dandruff formation. However, severity of the condition is strongly related to the lipophilic yeast of the skin microbiota, Malassezia spp. On the other hand, there are recent publications highlighting the role of other scalp microbiota members on dandruff formation. This review investigates the processes leading to the formation of dandruff to provide an etiological description of the condition, with a focus on Malassezia spp.

Natural Polyphenols Selectively Inhibit β-Carbonic Anhydrase from the Dandruff-Producing Fungus Malassezia globosa: Activity and Modeling Studies

Around 50 % of the worldwide population is affected by dandruff, which is triggered by a variety of factors. The yeast Malassezia globosa has been labeled as the most probable causative agent for the onset of dandruff. The β-carbonic anhydrase (CA) of MgCA was recently validated as an anti-dandruff target, with its inhibition being responsible for in vivo growth defects in the fungus. As classical CA inhibitors of the sulfonamide type give rise to permeability problems through biological membranes, finding non-sulfonamide alternatives for MgCA inhibition is of considerable interest in the cosmetic field. We recently screened a large library of human (h) CA inhibitors for MgCA inhibition, including different chemotypes, such as monothiocarbamates, dithiocarbamates, phenols, and benzoxaboroles. Herein, we expanded the research toward new MgCA inhibitors by considering a set of natural polyphenols (including flavones, flavonols, flavanones, flavanols, isoflavones, and depsides) that exhibited MgCA inhibitory activity in the micromolar range, as well as selectivity for the fungal isozyme over off-target human isoforms. The binding mode of representative derivatives within the MgCA catalytic cleft was investigated by docking studies using a homology-built model.

Malassezia species in students from universities of Sabzevar, Northeastern Iran

BACKGROUND

Malassezia species, usually part of normal human skin microbiota, may also cause cutaneous infections, mainly pityriasis versicolor (PV) which may rapidly spread in crowded communities, particularly in students' dormitories and sport leisure centers.

OBJECTIVE

Few studies have been conducted on PV in students in the Middle East. The present study was designed to determine prevalence of Malassezia species and related diseases in students from city of Sabzevar, Northeast Iran.

METHODS

Specimens were collected from 189 students and analyzed by direct microscopy and cultures. Following PCR amplification of the large subunit of ribosomal DNA, species were identified by restriction fragment length polymorphism analysis (RFL-PCR).

RESULTS

PV was suspected for 28 students which was confirmed by direct examination and cultures. Cultures also revealed positive for 13 students with healthy skin. Four Malassezia species were identified, with M. restricta as the most prevalent. A higher rate of PV was observed compared to other regions in Iran. However, despite the lipophilic feature of Malassezia species, no significant association was observed between PV or Malassezia species and fatty skin or gender.

CONCLUSION

This study determined the frequencies of Malassezia species in part of Northeast Iran, but further studies are needed to identify risk factors for PV.

The Association of the Skin Microbiota With Health, Immunity, and Disease

The human skin is densely colonized by a highly diverse microbiota comprising all three domains of life. Long believed to represent mainly a source of infection, the human skin microbiota is nowadays well accepted as an important driver of human (skin) health and well-being. This microbiota is influenced by many host and environmental factors and interacts closely with the skin immune system. Although cause and effect are usually difficult to discriminate, changes in the skin microbiota clearly play a role in the pathobiology of many types of skin disease and cosmetic disorders. Consequently, treatment and prevention strategies have to respect this role, rendering pre- and probiotic and even transplantation therapies an additional option to the use of antibiotics.

Inhibition of Malassezia globosa carbonic anhydrase with phenols

A panel of 22 phenols was investigated as inhibitors of the β-class carbonic anhydrase (CAs, EC 4.2.1.1) from the fungal parasite Malassezia globosa (MgCA), a validated anti-dandruff drug target. The displayed inhibitory activities were compared to the ones previously reported against the off-target widely distributed human (h) isoforms hCA I and II. All tested phenols possessed a better efficacy in inhibiting MgCA than the clinically used sulfonamide acetazolamide, with K_Is in the range of 2.5 and 65.0μM. A homology-built model of MgCA was also used for understanding the binding mode of phenols to the fungal enzyme. Indeed, a wide network of hydrogen bonds and hydrophobic interactions between the phenol and active site residues were evidenced. The OH moiety of the inhibitor was observed anchored to the zinc-coordinated water, also making hydrogen bonds with Ser48 and Asp49. The diverse substituents at the phenolic scaffold were observed to interact with different portions of the hydrophobic pocket according to their nature and position. Considering the effective MgCA inhibitory properties of phenols, beside to the rather low inhibition against the off-target hCA I and II, this class of compounds might be of considerable interest in the cosmetics field as potential anti-dandruff drugs.

Dithiocarbamates effectively inhibit the β-carbonic anhydrase from the dandruff-producing fungus Malassezia globosa

A series of dithiocarbamates (DTCs) was investigated for the inhibition of the β-class carbonic anhydrase (CAs, EC 4.2.1.1) from the fungal parasite Malassezia globosa, MgCA, a validated anti-dandruff drug target. These DTCs incorporate various scaffold, among which those of N,N-dimethylaminoethylenediamine, the aminoalcohols with 3-5 carbon atoms in their molecule, 3-amino-quinuclidine, piperidine, morpholine and piperazine derivatives, as well as phenethylamine and its 4-sulfamoylated derivative. Several DTCs resulted more effective in inhibiting MgCA compared to the standard sulfonamide drug acetazolamide (K_I of 74μM), with K_Is ranging between 383 and 6235nM. A computational approach, involving a homology modeling of the enzyme and docking inhibitors within its active site, helped us rationalize the results. This study may contribute to better understand the inhibition profile of MgCA, and offer new ideas for the design of modulators of activity which belong to less investigated chemical classes, thus potentially useful to combat dandruff and other fungal infections.

Dysbiotic Bacterial and Fungal Communities Not Restricted to Clinically Affected Skin Sites in Dandruff

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.

Malassezia species and their associated skin diseases

Malassezia spp. are lipophilic fungi that occur on all skin surfaces of humans and animals as commensal and pathogenic organisms. In the 2000s, several new species were added to the Malassezia genus by Japanese researchers. The genus Malassezia now includes 14 species of basidiomycetous yeast. Culture-independent molecular analysis clearly demonstrated that the DNA of Malassezia spp. was predominantly detected in core body and arm sites, suggesting that they are the dominant fungal flora of the human body. Malassezia spp. have been implicated in skin diseases including pityriasis versicolor (PV), Malassezia folliculitis (MF), seborrheic dermatitis (SD) and atopic dermatitis (AD). While Malassezia spp. are directly responsible for the infectious diseases, PV and MF, they act as an exacerbating factor in AD and SD. The fatty acids generated by Malassezia lipase can induce inflammation of the skin, resulting in development of SD. Patch and serum immunoglobulin E tests revealed that AD patients were hypersensitive to Malassezia. However, these findings only partially elucidated the mechanism by which Malassezia spp. induce inflammation in the skin; understanding of the pathogenetic role of Malassezia spp. in SD or AD remains incomplete. In this article, the latest findings of Malassezia research are reviewed with special attention to skin diseases.

Spatial and compositional variation in the fungal communities of organic and conventionally grown apple fruit at the consumer point-of-purchase

The fungal diversity in harvested apples from organic or conventional management practices was analyzed in different fruit locations (stem end, calyx end, peel, and wounded flesh) shortly after fruit purchase (T1) and after 2 weeks of storage (T5). A total of 5,760,162 high-quality fungal sequences were recovered and assigned to 8,504 Operational Taxonomic Units. Members of the phylum Ascomycota were dominant in all samples and accounted for 91.6% of the total number of detected sequences. This was followed by Basidiomycota (8%), Chytridiomycota (0.1%), and unidentified fungi (0.3%). Alpha and beta diversity analyses revealed the presence of significantly different fungal populations in the investigated fruit parts. Among detected fungi, the genus Penicillium prevailed in the peel and in the wounded flesh while Alternaria spp. prevailed in the calyx and stem end samples that included apple core tissues. Several taxonomic units that appear to be closely related to pathogenic fungi associated with secondary human infections were present in peel and wounds. Moreover, significantly different populations were revealed in organic and conventional apples and this result was consistent in all investigated fruit parts (calyx end, peel, stem end, and wounded flesh). Several unique taxa were exclusively detected in organic apples suggesting that management practices may have been a contributing factor in determining the taxa present. In contrast, little differences were revealed in the two assessment times (T1 and T5). Results of the present study represent an advancement of the current knowledge on the fungal microbiota in collected fruit tissues of apple.