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

Fungal Head and Neck Dermatitis: Current Understanding and Management

Head and neck dermatitis (HND) is a form of atopic dermatitis (AD) that affects the seborrheic areas of the body and causes greater quality of life detriments than other types of AD. HND can be challenging to treat since first-line topical therapies may be ineffective or intolerable for long-term use on areas affected by HND while dupilumab may cause dupilumab-associated HND (DAHND). Current evidence implicates fungi, particularly Malassezia spp., in the pathogenesis of HND. Penetration of fungal antigens through the defective AD skin barrier activates the innate and adaptive immune systems to cause cutaneous inflammation via the T helper (Th)17 and/or Th2 axes. Malassezia sensitization may distinguish HND from other forms of AD. Multiple double-blind, placebo-controlled trials have shown antifungals to benefit HND, yet the persistence of symptom relief with sustained use remains unclear. Oral antifungals appear more effective than topical antifungals but may be harmful with long-term use. DAHND may also be fungal-mediated given improvement with antifungals and evidence of an overactive immune response against Malassezia in these patients. Janus kinase inhibitors are effective for HND, including DAHND, but may cause significant side effects when administered systemically. OX40/OX40L inhibitors and tralokinumab may be promising options for HND on the horizon. Demographic and environmental factors influence the host mycobiome and should be considered in future precision-medicine approaches as microbiome composition and diversity are linked to severity of HND.

Compositionally aware estimation of cross-correlations for microbiome data

In the field of microbiome studies, it is of interest to infer correlations between abundances of different microbes (here referred to as operational taxonomic units, OTUs). Several methods taking the compositional nature of the sequencing data into account exist. However, these methods cannot infer correlations between OTU abundances and other variables. In this paper we introduce the novel methods SparCEV (Sparse Correlations with External Variables) and SparXCC (Sparse Cross-Correlations between Compositional data) for quantifying correlations between OTU abundances and either continuous phenotypic variables or components of other compositional datasets, such as transcriptomic data. SparCEV and SparXCC both assume that the average correlation in the dataset is zero. Iterative versions of SparCEV and SparXCC are proposed to alleviate bias resulting from deviations from this assumption. We compare these new methods to empirical Pearson cross-correlations after applying naive transformations of the data (log and log-TSS). Additionally, we test the centered log ratio transformation (CLR) and the variance stabilising transformation (VST). We find that CLR and VST outperform naive transformations, except when the correlation matrix is dense. SparCEV and SparXCC outperform CLR and VST when the number of OTUs is small and perform similarly to CLR and VST for large numbers of OTUs. Adding the iterative procedure increases accuracy for SparCEV and SparXCC for all cases, except when the average correlation in the dataset is close to zero or the correlation matrix is dense. These results are consistent with our theoretical considerations.

Malassezia specific IgE in head and neck dermatitis of eczema: A systematic review & meta-analysis

Head and neck atopic dermatitis (HNAD) is a subtype of atopic dermatitis (AD), a common inflammatory skin condition with a distinctive clinical appearance. Malassezia spp., a predominant skin yeast, is considered to exacerbate HNAD. In this study, we investigate the prevalence of Malassezia-specific IgE among HNAD patients. A comprehensive search was performed for observational studies analysing the association between Malassezia-specific IgE and HNAD. This study was performed according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses 2020 checklist and quality was assessed via the Newcastle-Ottawa Quality Assessment Scale (NOS). Fourteen observational studies (840 patients) were included in the analysis. 58% of HNAD patients were male (95% CI: 45.2-69.7). Overall prevalence of Malassezia-specific IgE among HNAD patients was 79.3% (95% CI: 57.5-91.5). Prevalence of Malassezia-specific IgE among HNAD patients varied significantly between geographical regions (p = 0.0441), with 88% in non-Asian regions (95% CI: 61.06-97.17) and 54.73% in Asian regions (95% CI: 34.36-73.63). Malassezia-specific IgE prevalence among HNAD patients varied significantly among studies of higher and lower NOS quality score (p = 0.0386), with 95.42% in studies with NOS ≥7 (95% CI: 63.54-99.60) and 58.05% in studies with NOS <7 (95% CI: 41.44-73.01). Malassezia-specific IgE prevalence among HNAD patients did not vary significantly between more and less predominant Malassezia species (p = 0.1048). Malassezia spp. plays a crucial role in the pathogenesis of HNAD, and IgE anti-Malassezia antibodies appeared to be a common marker for HNAD. Understanding the pathophysiology of Malassezia in HNAD can help develop more targeted therapeutic approaches in managing AD.

Adding Fuel to the Fire? The Skin Microbiome in Atopic Dermatitis

Atopic dermatitis (AD) is a multifactorial, heterogeneous disease characterized by epidermal barrier dysfunction, immune system dysregulation, and skin microbiome alterations. Skin microbiome studies in AD have demonstrated that disease flares are associated with microbial shifts, particularly Staphylococcus aureus predominance. AD-associated S. aureus strains differ from those in healthy individuals across various genomic loci, including virulence factors, adhesion proteins, and proinflammatory molecules-which may contribute to complex microbiome barrier-immune system interactions in AD. Different microbially based treatments for AD have been explored, and their future therapeutic successes will depend on a deeper understanding of the potential microbial contributions to the disease.

Effectiveness of Dose Increase in Upadacitinib from 15 mg to 30 mg for Patients with Moderate-to-Severe Atopic Dermatitis: A Real-World Clinical Practice in Japan

BACKGROUND

Atopic dermatitis is characterized by persistent eczema and pruritus. Janus kinase inhibitors, including upadacitinib, are effective treatments for moderate-to-severe atopic dermatitis. If patients do not respond well to a certain dose of a Janus kinase inhibitor, increasing the dose may improve their treatment responsiveness.

OBJECTIVES

We assessed the outcomes of a dose increase in upadacitinib from 15 mg to 30 mg for Japanese patients with moderate-to-severe atopic dermatitis.

METHODS

In 23 patients who showed insufficient responses to upadacitinib 15-mg treatment, the dose of upadacitinib was increased to 30 mg. We evaluated total Eczema Area and Severity Index (EASI), EASI on the head and neck, trunk, upper, or lower limbs, EASI of erythema, edema/papulation, excoriation, or lichenification, and Peak Pruritus Numerical-Rating Scale at baseline (onset of upadactinib 15 mg), week 0 (time of increase), and weeks 4 and 12 after the increase.

RESULTS

Total EASI, EASI on each anatomical site, EASI of each clinical sign, and Peak Pruritus Numerical-Rating Scale were markedly reduced at weeks 4 or 12 compared with week 0. After the dose increase, the achievement rates of EASI 75 and EASI 90 significantly improved; EASI 75 4.3%, 68.2%, and 66.7%; EASI 90 0%, 18.2%, and 38.1% at weeks 0, 4, and 12, respectively.

CONCLUSIONS

These results suggest that upadacitinib 30 mg can ameliorate rash and pruritus insufficiently improved by upadacitinib 15 mg, and that the dose increase to 30 mg may be considered as a treatment option for patients with atopic dermatitis with a limited response to upadacitinib 15 mg.

Therapeutic effectiveness of upadacitinib on individual types of rash in Japanese patients with moderate-to-severe atopic dermatitis

Atopic dermatitis (AD) is a chronic eczematous disease with various types of rash, erythema, edema/papulation, excoriation, or lichenification. Janus kinase 1 inhibitor upadacitinib is effective for moderate-to-severe AD. We aimed to investigate the therapeutic effects of upadacitinib on each rash type in AD patients in real-world clinical practice. Seventy-two Japanese patients with moderate-to-severe AD were treated with oral upadacitinib 15 mg/day plus topical corticosteroids. The Eczema Area and Severity Index (EASI) scores for erythema, edema/papulation, excoriation, or lichenification on the whole body or on head and neck, upper limbs, lower limbs, or trunk were assessed at weeks 0, 4, and 12 of treatment. The proportions of patients who achieved resolution or at least 75% reduction of EASI from baseline (EASI 75) for individual rash types were calculated at weeks 4 and 12 on the whole body or each anatomical site. The resolution rates for excoriation, erythema, edema/papulation, or lichenification on the whole body were 38.3%, 23.7%, 21.7%, and 8.3% at week 4 and 18.3%, 18.6%, 11.6%, and 13.3% at week 12, respectively. The EASI scores for all rash types significantly decreased at weeks 4 and 12 compared to week 0. The achievement rates of EASI 75 for excoriation, erythema, edema/papulation, or lichenification on the whole body were 67.2%, 66.7%, 49.2%, and 37.7% at week 4 and 57.3%, 65%, 41%, and 41% at week 12, respectively. The achievement rate of EASI 75 for erythema on head and neck at week 4 (45.3%) was lower than that on upper limbs (71%) and on lower limbs (70.8%), and that on head and neck at week 12 (42.2%) was lower than that on lower limbs (69.2%). These results indicate that upadacitinib is effective for all AD rash types, especially for excoriation and erythema, while head-and-neck erythema might be less responsive to upadacitinib.

Effectiveness of switching from baricitinib 4 mg to upadacitinib 30 mg in patients with moderate-to-severe atopic dermatitis: a real-world clinical practice in Japan

BACKGROUND

Atopic dermatitis (AD) is a chronic eczematous disease with severe pruritus. Janus kinase (JAK) inhibitors, upadacitinib, baricitinib, and abrocitinib, are systemic treatments for AD. The outcomes of switching from one JAK inhibitor to another have not been examined.

OBJECTIVES

We assessed the outcomes of switching from baricitinib 4 mg to upadacitinib 30 mg in Japanese patients with moderate-to-severe AD.

METHODS

Twenty patients treated with baricitinib 4 mg, showing insufficient response or adverse events, were switched to treatment with upadacitinib 30 mg. We evaluated total eczema area and severity index (EASI), EASI at head and neck, trunk, upper, or lower limbs, EASI of erythema, edema/papulation, excoriation, or lichenification, and peak pruritus numerical-rating scale (PP-NRS) at baseline (start of baricitinib), weeks 0 (time of switching), and 4 and 12 after switching.

RESULTS

Total EASI, EASI at each anatomical site, EASI of each clinical sign, and PP-NRS were markedly reduced at weeks 4 or 12 compared to week 0. Achievement rates of more than 75% or 90% reduction of EASI from baseline significantly improved after switching.

CONCLUSIONS

Switching from baricitinib 4 mg to upadacitinib 30 mg effectively improved rash and pruritus.

Effectiveness and Safety of Upadacitinib in Combination with Topical Corticosteroids in Adolescent Patients with Moderate-to-Severe Atopic Dermatitis

Purpose

To investigate the therapeutic effectiveness and safety of Janus kinase 1 inhibitor upadacitinib in adolescent patients with atopic dermatitis (AD).

Patients and Methods

This study examined therapeutic effectiveness and safety of upadacitinib for 39 Japanese adolescent patients (aged 12-17 years) diagnosed with moderate-to-severe AD from August 2021 to January 2023. The patients were treated with upadacitinib 15 mg/day plus twice daily topical corticosteroids. Total eczema area and severity index (EASI) or EASI on head and neck, upper limbs, lower limbs, and trunk or for erythema, edema/papulation, excoriation, or lichenification, atopic dermatitis control tool (ADCT), peak pruritus-numerical rating scale (PP-NRS), and laboratory indexes were assessed at weeks 0, 4, and 12 of treatment. Treatment-emergent adverse events were recorded.

Results

Total EASI or EASI on 4 anatomical sites or for 4 rash types, ADCT, and PP-NRS were significantly reduced at week 4 and 12 compared to week 0. The achievement rates at weeks 4 or 12 were 64.1% or 62.5% for EASI 75, 93.5% or 73.1% for ADCT <7-point, and 80.6% or 60% for PP-NRS ≥4-point improvement, respectively, indicating their peak at week 4 and slight decrease at week 12. The percent reduction of EASI for excoriation was higher than that for lichenification or edema/papulation at week 4 or week 12, respectively. The percent reductions of EASI for erythema and edema/papulation on head and neck were lower than those on lower limbs at week 12. Total eosinophil counts (TEC) and IgE reduced at week 4 compared to week 0 while TARC, IgE, TEC, and LDH increased at week 12 compared to week 4.

Conclusion

These results suggest therapeutic effectiveness and tolerability of upadacitinib and support its therapeutic usefulness for adolescent AD patients.

Background factors predicting the occurrence of herpes zoster in atopic dermatitis patients treated with upadacitinib

Upadacitinib, an oral Janus kinase 1 inhibitor approved for treating atopic dermatitis (AD), can cause adverse events such as herpes zoster (HZ) and acne. We aimed to identify background factors predicting the occurrence of HZ and acne during upadacitinib treatment in patients with AD. From August 2021 to December 2022, 112 Japanese patients with moderate-to-severe AD (aged ≥12 years) were treated with upadacitinib 15 mg/day (78 patients) or 30 mg/day (34 patients) plus topical corticosteroids or delgocitinib limited to head and neck for 3-9 months. AD patients with the occurrence of HZ during upadacitinib treatment had higher incidences for history of HZ and of bronchial asthma than those without in the upadacitinib 15 mg, 30 mg, and whole groups. AD patients with occurrence of HZ had higher pretreatment values of lactate dehydrogenase and eczema area and severity index on head and neck compared to those without in the upadacitinib 15 mg and whole groups. Logistic regression analysis revealed that history of HZ was associated with the occurrence of HZ in the upadacitinib 15 mg and whole groups. The proportion of underage patients (<18 years) was higher in patients with occurrence of acne compared to those without in the upadacitinib 30 mg group, but no significant differences were found in the other background factors between the two patient populations. History of HZ may predict the occurrence of HZ during upadacitinib treatment in patients with AD.

Interactions between Malassezia and New Therapeutic Agents in Atopic Dermatitis Affecting Skin Barrier and Inflammation in Recombinant Human Epidermis Model

Several studies have reported the pathogenic role of Malassezia in atopic dermatitis (AD); the significance of Malassezia’s influence on AD needs to be further investigated. Dupilumab, a monoclonal antibody to anti-Interleukin (IL) 4Rα, and ruxolitinib, a Janus kinase (JAK)1/2 inhibitor, are the first approved biologics and inhibitors widely used for AD treatment. In this study, we aimed to investigate how Malassezia Restricta (M. restricta) affects the skin barrier and inflammation in AD and interacts with the AD therapeutic agents ruxolitinib and anti-IL4Rα. To induce an in vitro AD model, a reconstructed human epidermis (RHE) was treated with IL-4 and IL-13. M. restricta was inoculated on the surface of RHE, and anti-IL4Rα or ruxolitinib was supplemented to model treated AD lesions. Histological and molecular analyses were performed. Skin barrier and ceramide-related molecules were downregulated by M. restricta and reverted by anti-IL4Rα and ruxolitinib. Antimicrobial peptides, VEGF, Th2-related, and JAK/STAT pathway molecules were upregulated by M. restricta and suppressed by anti-IL4Rα and ruxolitinib. These findings show that M. restricta aggravated skin barrier function and Th2 inflammation and decreased the efficacy of anti-IL4Rα and ruxolitinib.

EAACI Molecular Allergology User's Guide 2.0

Since the discovery of immunoglobulin E (IgE) as a mediator of allergic diseases in 1967, our knowledge about the immunological mechanisms of IgE-mediated allergies has remarkably increased. In addition to understanding the immune response and clinical symptoms, allergy diagnosis and management depend strongly on the precise identification of the elicitors of the IgE-mediated allergic reaction. In the past four decades, innovations in bioscience and technology have facilitated the identification and production of well-defined, highly pure molecules for component-resolved diagnosis (CRD), allowing a personalized diagnosis and management of the allergic disease for individual patients. The first edition of the "EAACI Molecular Allergology User's Guide" (MAUG) in 2016 rapidly became a key reference for clinicians, scientists, and interested readers with a background in allergology, immunology, biology, and medicine. Nevertheless, the field of molecular allergology is moving fast, and after 6 years, a new EAACI Taskforce was established to provide an updated document. The Molecular Allergology User's Guide 2.0 summarizes state-of-the-art information on allergen molecules, their clinical relevance, and their application in diagnostic algorithms for clinical practice. It is designed for both, clinicians and scientists, guiding health care professionals through the overwhelming list of different allergen molecules available for testing. Further, it provides diagnostic algorithms on the clinical relevance of allergenic molecules and gives an overview of their biology, the basic mechanisms of test formats, and the application of tests to measure allergen exposure.

Head and neck dermatitis is exacerbated by Malassezia furfur colonization, skin barrier disruption, and immune dysregulation

Introduction & objectives

Head and neck dermatitis (HND) is a refractory phenotype of atopic dermatitis (AD) and can be a therapeutic challenge due to lack of responsiveness to conventional treatments. Previous studies have suggested that the microbiome and fungiome may play a role in inducing HND, but the underlying pathogenic mechanisms remain unknown. This study aimed to determine the link between HND and fungiome and to examine the contribution of Malassezia furfur.

Materials and methods

To identify the effect of the sensitization status of M. furfur on HND, 312 patients diagnosed with AD were enrolled. To elucidate the mechanism underlying the effects of M. furfur, human keratinocytes and dermal endothelial cells were cultured with M. furfur and treated with Th2 cytokines. The downstream effects of various cytokines, including inflammation and angiogenesis, were investigated by real-time quantitative PCR. To identify the association between changes in lipid composition and M. furfur sensitization status, D-squame tape stripping was performed. Lipid composition was evaluated by focusing on ceramide species using liquid chromatography coupled with tandem mass spectrometry.

Results

Increased sensitization to M. furfur was observed in patients with HND. Additionally, sensitization to M. furfur was associated with increased disease severity in these patients. IL-4 treated human keratinocytes cultured with M. furfur produced significantly more VEGF, VEGFR, IL-31, and IL-33. IL-4/M. furfur co-cultured dermal endothelial cells exhibited significantly elevated VEGFR, TGF-β, TNF-α, and IL-1β levels. Stratum corneum lipid analysis revealed decreased levels of esterified omega-hydroxyacyl-sphingosine, indicating skin barrier dysfunction in HND. Finally, M. furfur growth was inhibited by the addition of these ceramides to culture media, while the growth of other microbiota, including Cutibacterium acnes, were not inhibited.

Conclusions

Under decreased levels of ceramide in AD patients with HND, M. furfur would proliferate, which may enhance pro-inflammatory cytokine levels, angiogenesis, and tissue remodeling. Thus, it plays a central role in the pathogenesis of HND in AD.

Treatment of atopic dermatitis using topical antifungal drugs: A meta-analysis

Several studies have focused on treating atopic dermatitis (AD) using topical antifungal drugs. However, their findings are inconsistent. This meta-analysis of randomized controlled trials (RCTs) aimed to evaluate the safety and efficacy of topical antifungal drugs for the treatment of AD. We searched prominent databases such as EMBASE, PubMed, Cochrane Library, China Biomedical Literature Database (CBM), China National Knowledge Infrastructure (CNKI), China Science and Technology Journal Database (VIP), and Wanfang Database to retrieve all RCTs on the use of topical antifungal drugs for the treatment of AD. The two authors independently performed screening, extraction, and quality evaluation of data based on inclusion and exclusion criteria. In addition, quantitative synthesis and qualitative description of the results were performed using Review Manager 5.3. Nine studies with a total of 785 subjects were included in the meta-analysis. Based on intervention measures, data were divided into three groups: topical antifungal drugs versus placebo, topical antifungal drugs versus topical glucocorticoids, and topical antifungal drugs plus topical glucocorticoids versus topical glucocorticoids. Risk-of-bias assessments revealed that the random distribution methods and allocation concealment were not ideal; further, some studies had incomplete data and reported selective results. Quantitative analysis revealed that in terms of effective rate, topical antifungal drugs are superior to topical glucocorticoids (p = 0.003), and topical antifungal drugs plus topical glucocorticoids are superior to topical glucocorticoids (p = 0.001). However, no significant differences in adverse reactions were observed between the three groups (p > 0.05). The safety and efficacy of topical antifungal drugs for treating AD cannot be accurately evaluated with existing data. Therefore, additional high-quality and large-sample prospective RCTs are required for further validation to determine the appropriateness of topical antifungal drug use for the treatment of AD in clinical settings.

Fungal exposome, human health, and unmet needs: A 2022 update with special focus on allergy

Humans inhale, ingest, and touch thousands of fungi each day. The ubiquity and diversity of the fungal kingdom, reflected by its complex taxonomy, are in sharp contrast with our scarce knowledge about its distribution, pathogenic effects, and effective interventions at the environmental and individual levels. Here, we present an overview of salient features of fungi as permanent players of the human exposome and key determinants of human health, through the lens of fungal allergy and other fungal hypersensitivity reactions. Improved understanding of the fungal exposome sheds new light on the epidemiology of fungal-related hypersensitivity diseases, their immunological substratum, the currently available methods, and biomarkers for environmental and medical fungi. Unmet needs are described and potential approaches are highlighted as perspectives.

The Role of the Cutaneous Mycobiome in Atopic Dermatitis

Atopic dermatitis is a chronic inflammatory skin disorder characterized by eczematous lesions, itch, and a significant deterioration in the quality of life. Recently, microbiome dysbiosis has been implicated in the pathogenesis of atopic dermatitis. Changes in the fungal microbiome (also termed mycobiome) appear to be an important factor influencing the clinical picture of this entity. This review summarizes the available insights into the role of the cutaneous mycobiome in atopic dermatitis and the new research possibilities in this field. The prevalence and characteristics of key fungal species, the most important pathogenesis pathways, as well as classic and emerging therapies of fungal dysbiosis and infections complicating atopic dermatitis, are presented.

The Acari Hypothesis, III: Atopic Dermatitis

Atopic dermatitis is a chronic relapsing dermatopathology involving IgE against allergenic materials present on mammalian epithelial surfaces. Allergens are as diverse as pet danders, and polypeptides expressed by microbes of the mammalian microbiome, e.g., Malassezia spp. The Acari Hypothesis posits that the mammalian innate immune system utilizes pathogen-bound acarian immune effectors to protect against the vectorial threat posed by mites and ticks. Per The Hypothesis, IgE-mediated allergic disease is a specious consequence of the pairing of acarian gastrointestinal materials, e.g., allergenic foodstuffs, with acarian innate immune effectors that have interspecies operability. In keeping with The Hypothesis, the IgE profile of atopic patients should include both anti-acarian antibodies and specious antibodies responsible for specific allergy. Further, the profile should inform on the diet and/or environment of the acarian vector. In this regard, the prevalence of Demodex and Dermatophagoides on the skin of persons suffering from atopic dermatitis is increased. Importantly, the diets of these mites correspond well with the allergens of affected patients. In this report, roles for these specific acarians in the pathogenesis of atopic dermatitis are proposed and elaborated.

Effectiveness and safety of dupilumab in the treatment of atopic dermatitis in children (6-11 years): data from a French multicenter retrospective cohort in daily practice

BACKGROUND

Dupilumab is the first biotherapy available for the treatment of moderate-to-severe childhood atopic dermatitis (AD).

OBJECTIVE

The aim of this study was to evaluate the effectiveness and safety of dupilumab in daily practice.

METHODS

Patients aged 6 to 11, who had received a first dose of dupilumab were included in this multicenter retrospective cohort study. The primary endpoint was change in SCORAD after 3 months of treatment. Secondary endpoints were change in IGA score at 3 months, proportion of patients with SCORAD50 and SCORAD75, description of adverse events and proportion of children in our cohort who would be excluded from pivotal phase 3 clinical trial.

RESULTS

80 patients were included. After 3 months of treatment, there was a significant decrease in SCORAD (mean: 21.8 ± 13.8 vs 53.9 ± 18.5; p<0.0001) and IGA (1.3 ± 0.8 vs 3.5 ± 0.7; p<0.0001). Conjunctivitis was observed in 11.3%(n=9/80); 3 patients experienced dupilumab facial redness (DFR); 17.5% (n=14/80) reported injection site reactions; 6.3% (n=5/80) discontinued treatment. 61.2 % (n=49/80) children were ineligible in the phase 3 trial.

LIMITATIONS

There is no control group. Because it was a real life study based on information from patient medical records in a French multicenter cohort, we cannot rule out the presence of reporting bias generated by the use of patient reported characteristics and missing information.

CONCLUSION

These real-life data confirm the efficacy and safety of dupilumab in children with moderate to severe AD extended to dyshidrosis and atopic prurigo but it also revealed a lower frequency of DFR and conjunctivitis. However, administration in injectable form may be a barrier in this age group.

Malassezia: Zoonotic Implications, Parallels and Differences in Colonization and Disease in Humans and Animals

Malassezia spp. are commensals of the skin, oral/sinonasal cavity, lower respiratory and gastrointestinal tract. Eighteen species have been recovered from humans, other mammals and birds. They can also be isolated from diverse environments, suggesting an evolutionary trajectory of adaption from an ecological niche in plants and soil to the mucocutaneous ecosystem of warm-blooded vertebrates. In humans, dogs and cats, Malassezia-associated dermatological conditions share some commonalities. Otomycosis is common in companion animals but is rare in humans. Systemic infections, which are increasingly reported in humans, have yet to be recognized in animals. Malassezia species have also been identified as pathogenetic contributors to some chronic human diseases. While Malassezia species are host-adapted, some species are zoophilic and can cause fungemia, with outbreaks in neonatal intensive care wards associated with temporary colonization of healthcare worker’s hands from contact with their pets. Although standardization is lacking, susceptibility testing is usually performed using a modified broth microdilution method. Antifungal susceptibility can vary depending on Malassezia species, body location, infection type, disease duration, presence of co-morbidities and immunosuppression. Antifungal resistance mechanisms include biofilm formation, mutations or overexpression of ERG11, overexpression of efflux pumps and gene rearrangements or overexpression in chromosome 4.

Narrative review on the management of moderate-severe atopic dermatitis in pediatric age of the Italian Society of Pediatric Allergology and Immunology (SIAIP), of the Italian Society of Pediatric Dermatology (SIDerP) and of the Italian Society of Pediatrics (SIP)

Currently, there are a few detailed guidelines on the overall management of children and adolescents with moderate-severe atopic dermatitis. AD ​​is a complex disease presenting with different clinical phenotypes, which require an individualized and multidisciplinary approach. Therefore, appropriate interaction between primary care pediatricians, pediatric allergists, and pediatric dermatologists is crucial to finding the best management strategy. In this manuscript, members of the Italian Society of Pediatric Allergology and Immunology (SIAIP), the Italian Society of Pediatric Dermatology (SIDerP), and the Italian Society of Pediatrics (SIP) with expertise in the management of moderate-severe atopic dermatitis have reviewed the latest scientific evidence in the field. This narrative review aims to define a pathway to appropriately managing children and adolescents with moderate-severe atopic dermatitis.

Characterization of Distinct Microbiota Associated with Scalp Dermatitis in Patients with Atopic Dermatitis

Recent studies have focused on the role of skin microbiota in the pathogenesis of atopic dermatitis (AD). Among the various clinical phenotypes of AD, scalp dermatitis is a commonly observed clinical feature of AD. However, little is known about the pathogenesis of scalp dermatitis in AD. Hence, the aim of this study was to identify the distinct microbiota associated with scalp dermatitis in patients with AD. Using scalp swab samples from 10 patients with AD and 10 healthy controls, this study characterized the scalp microbiota in patients with AD via V3–V4 regions of the 16S rRNA gene sequencing for bacterial identification, and ITS2 gene sequencing for fungal identification. Among bacterial genera, Staphylococcus was the most abundant in AD than in healthy controls, whereas Cutibacterium was the most abundant species in the healthy controls. The most predominant scalp fungal microbiota was Malassezia both in AD and healthy controls, while a higher diversity of non-Malassezia fungi was observed in AD than in healthy controls. The study findings indicate the dysbiosis of scalp microbiota in AD and highlight the potential biomarker role of specific microbiota in AD on the scalp dermatitis.

Characterization of Residual Facial Dermatitis during Dupilumab Therapy: A Retrospective Chart Review to Delineate the Potential Role of Expanded Series Patch Testing

OBJECTIVE

We sought to determine the incidence of RFDD in patients receiving dupilumab and the rate of resolution of RFDD after expanded series patch testing (ESPT) and allergen avoidance.

METHODS

This is a retrospective chart review of 80 patients with atopic dermatitis who were evaluated for RFDD after treatment with dupilumab. Expanded series patch testing findings and response to allergen avoidance were assessed in the subset of patients with RFDD who subsequently underwent ESPT while continuing to receive dupilumab.

RESULTS

Forty-nine patients (61.3%) experienced facial dermatitis before initiating dupilumab. Thirty-five patients (43.8%) experienced RFDD after starting dupilumab. Of the 14 patients with RFDD who received ESPT, 92.9% had 1 or more relevant positive patch test results, with 50% of such patients being mostly to completely clear of facial dermatitis after allergen avoidance. Importantly, 50.6% of the positive reactions to allergens were not included on the North American Contact Dermatitis Group Core 80.

CONCLUSIONS

Many patients with RFDD benefit from patch testing and subsequent allergen avoidance. Expanded series patch testing should be offered to patients who experience RFDD after beginning dupilumab therapy to ensure that such patients have eliminated any exogenous component of their dermatitis, such as concomitant allergic contact dermatitis.

Host-Microbe Interaction on the Skin and Its Role in the Pathogenesis and Treatment of Atopic Dermatitis

Atopic dermatitis (AD) is a condition with a complex and unclear aetiology. Possible causes of AD encompass alterations in the structure and function of the epidermal barrier, disturbances in the skin microbiome, immune factors, allergens, bacterial and fungal infections as well as environmental and genetic factors. In patients with AD, acute skin lesions are colonized by a greater number of bacteria and fungi than chronic lesions, clinically unchanged atopic skin and the skin of healthy people. Mechanisms promoting skin colonization by pathogens include complex interplay among several factors. Apart from disturbances of the skin microbiome, increased adhesion in atopic skin, defects of innate immune response resulting in the lack of or restriction of growth of microorganisms also contribute to susceptibility to the skin colonization of and infections, especially with Staphylococcus aureus. This review of the literature attempts to identify factors that are involved in the pathogenesis of AD-related bacterial and fungal skin colonization. Studies on the microbiome, commensal microorganisms and the role of skin microorganisms in maintaining healthy skin bring additional insight into the treatment and prevention of AD. In the light of presented mechanisms, reduction in colonization may become both causative and symptomatic treatment in AD.

Dysbiosis of skin mycobiome in atopic dermatitis

Atopic dermatitis (AD) is a chronic and relapsing inflammatory skin disease with an increasing prevalence worldwide. The aetiology and pathogenesis of AD have not been fully elucidated. Previous studies have suggested the role of fungi as a triggering factor in the development AD. Here we conducted a systematic review to investigate the skin mycobiome profiles in AD and to address whether there is an association between fungal dysbiosis and AD. We searched Medline/PubMed, Embase and Web of Science for research studies published in English between January 1st, 2010 and April 21st, 2021. A total of 11 human studies and 3 animal studies were included in this analysis. Fungal dysbiosis was observed in AD lesions with a depleted amount of Malassezia and a higher abundance of filamentous fungi. A positive correlation between Candida and Staphylococcus was also demonstrated in AD. We supposed that specific species of Malassezia spp. and Candida spp. may play a role in the pathogenesis of AD by interacting with the pathogenic bacteria. Topical application of emollients could improve the skin barrier function and restore the skin fungal flora by increasing the amount of Malassezia. Further studies focusing on the complex interplay between specific skin fungi and the host can provide better insight into the role of microorganisms in the pathogenesis of AD.

Dupilumab facial redness: Clinical characteristics and proposed treatment in a cohort

In this case series, we report for the first time in the literature in a cohort, the positive response to oral or topical antifungals for atopic dermatitis patients treated with Dupilumab that developed Dupilumab facial redness, supporting the Malassezia hypersensitivity theory.

Dupilumab Demonstrates Rapid and Consistent Improvement in Extent and Signs of Atopic Dermatitis Across All Anatomical Regions in Pediatric Patients 6 Years of Age and Older

INTRODUCTION

In phase III trials in adolescents and children with atopic dermatitis (AD), dupilumab significantly decreased global disease severity. However, the effects of dupilumab on the extent and signs of AD across different anatomical regions were not reported. Here we characterize the efficacy of dupilumab in improving the extent and signs of AD across four different anatomical regions in children and adolescents.

METHODS

A post hoc subset analysis was performed using data from two randomized, double-blind, placebo-controlled, international multicenter, phase III trials of dupilumab therapy in adolescents aged ≥ 12 to < 18 years with moderate-to-severe AD and children aged ≥ 6 to < 12 years with severe AD. Endpoints included mean percentage change in Eczema Area and Severity Index (EASI) signs (erythema, edema/papulation, excoriation, lichenification) and extent of AD (measured by percentage of body surface area [% BSA] involvement) from baseline to week 16 across four anatomical regions (head and neck, trunk, upper extremities, lower extremities).

RESULTS

Dupilumab improved both the extent and severity of AD signs across the four anatomical regions. Improvements were shown to be similar across the four anatomical regions for % BSA involvement and for reduction in EASI signs. Improvements in all signs were seen early, within the first 4 weeks of treatment, and were sustained through week 16, across all regions.

CONCLUSIONS

In pediatric patients 6 years of age and older, treatment with dupilumab resulted in rapid and consistent improvement in the extent and signs of AD across all anatomical regions. CLINICALTRIALS.

GOV IDENTIFIERS

LIBERTY AD ADOL (NCT03054428) and LIBERTY AD PEDS (NCT03345914). Does dupilumab provide improvement in atopic dermatitis across all anatomical regions in children and adolescents? (MP4 48,385 kb).

Topical therapy of atopic dermatitis with a focus on pimecrolimus

Atopic dermatitis (AD) is a chronic and relapsing, inflammatory skin disease characterized by impaired skin barrier function and immune system dysregulation that results in dryness, skin microbiome dysbiosis and intense pruritus. It is highly heterogeneous, and its management is demanding. Patients with AD are at greater risk of comorbidities such as attention-deficit hyperactivity disorder as well as other atopic diseases. Early-onset AD cases typically improve or resolve in late childhood; however, it is proposed that the prevalence of persistent or adult-onset AD is higher than previously thought. Basic therapy consists of emollient application and trigger avoidance, and when insufficient, topical corticosteroids (TCS) are the first-line treatment. However, corticophobia/steroid aversion and TCS side-effects, particularly on sensitive skin areas, lead to low compliance and insufficient disease control. Several long- and short-term randomized controlled and daily practice studies have demonstrated that topical calcineurin inhibitors, such as pimecrolimus, have similar anti-inflammatory effects to low-to-medium strength TCS, reduce pruritus and improve the quality of life of patients. In addition, pimecrolimus does not cause skin atrophy, is steroid-sparing and has a good safety profile, with no evidence for an increased risk of malignancies or skin infections. In general, pimecrolimus cream is well-accepted and well-tolerated, encouraging patient adherence and leading to its use by many physicians as a preferred therapy for children and sensitive skin areas.

Changes in Gut Microbiota Correlates with Response to Treatment with Probiotics in Patients with Atopic Dermatitis. A Post Hoc Analysis of a Clinical Trial

Atopic dermatitis (AD) is a chronic recurrent inflammatory skin disease with a high impact on the comfort of those who are affected and long-term treated with corticosteroids with limited efficacy and a high prevalence of relapses. Because of the limited effectiveness of these treatments, new strategies for recovery from AD lesions are continually being explored. In this article, we describe the gut microbiome changes achieved in a recently published clinical trial with the probiotic formulation Bifidobacterium animalis subsp. lactis CECT 8145, Bifidobacterium longum CECT 7347, and Lacticaseibacillus casei CECT 9104 (formerly Lactobacillus casei CECT 9104), showing a significant improvement in SCORAD (scoring atopic dermatitis) index in children (4-17 years) with AD (Clinicaltrials.gov identifier: NCT02585986). The present gut microbiome post hoc study showed no significant changes in diversity (Shannon and Simpson indexes) after probiotic consumption. In the probiotic group, genera Bacteroides, Ruminococcus, and Bifidobacterium significantly increased their levels while Faecalibacterium decreased, compared to the placebo group. Faecalibacterium showed the highest presence and significant positive correlation with AD severity (SCORAD index), whereas Abyssivirga, Bifidobacterium, and Lactococcus were inversely correlated. The results suggest that the consumption of the probiotic formulation here assayed modulates the gut microbiome with significant changes in genera Bacteroides and Faecalibacterium. In turn, the improvement in SCORAD correlates with a decrease in Faecalibacterium and an increase in Bifidobacterium, among others.

Nomenclature and clinical phenotypes of atopic dermatitis

Atopic dermatitis is a heterogeneous disease and resists classification. In this review, we discuss atopic dermatitis nomenclature and identify morphologic phenotypes, which will facilitate correct diagnoses and development of treatment strategies. We support using the term 'atopic dermatitis' rather than eczema, because it describes the allergic background and inflammation ('itis') as drivers of the disease. Atopic dermatitis has many morphologic manifestations that vary by topographic area affected, age, or race and require consideration in differential diagnosis. Different phenotypes based on morphology and topographic location, ethnicity, and age are discussed. A better-defined phenotype identification for atopic dermatitis will facilitate earlier and correct diagnosis of this complex condition and inform selection of the most appropriate treatment choice in an era in which targeted therapies may generate more individualized patient care.

Atopic Dermatitis and Sensitisation to Molecular Components of Alternaria, Cladosporium, Penicillium, Aspergillus, and Malassezia-Results of Allergy Explorer ALEX 2

Progress in laboratory diagnostics of IgE-mediated allergies is being made through the use of component-resolved diagnosis. The aim of our study is to analyze the sensitization profile to allergen reagents in patients suffering from atopic dermatitis with the use of the ALEX 2–Allergy Explorer and especially to show the sensitization to molecular components of molds and yeast. The complete dermatological and allergological examination including the examination of the sensitization to allergen reagents with Allergy Explorer ALEX 2 testing was performed. The relation between the sensitization to molecular components of molds and yeast and the severity of atopic dermatitis, and the occurrence of bronchial asthma and allergic rhinitis was evaluated. Altogether, 100 atopic dermatitis patients were examined—48 men and 52 women, with an average age of 40.9 years. The sensitization to Mala s 6, Mala s 11, Sac c, Asp f 6, Cla h and Cla h 8 correlates to the severity of atopic dermatitis. The sensitization to Sac c, Alt a 6, Cla h, Cla h 8 was observed significantly more frequently in patients suffering from bronchial asthma to Mala s 6 in patients suffering from allergic rhinitis. In patients with severe form of atopic dermatitis (AD), a very high level of specific IgE was recorded to Mala s 11 (in 36%) and to Asp f 6 (in 12%).

New-onset head and neck dermatitis in adolescent patients after dupilumab therapy for atopic dermatitis

BACKGROUND/OBJECTIVES

Head and neck dermatitis after dupilumab therapy for atopic dermatitis has been frequently reported in adults and only rarely in adolescents. No cases detailing disease course and treatment response have previously been described in adolescents.

METHODS/RESULTS

This case series presents five adolescent patients who developed new-onset or worsening head and neck dermatitis after dupilumab therapy for atopic dermatitis. All five patients improved after oral antifungal therapy.

CONCLUSIONS

The clinical features, treatment response, and potential disease pathogenesis in pediatric patients are described. Adolescents with new-onset head and neck dermatitis after dupilumab therapy may clinically improve with antifungal therapy, suggesting that Malassezia species may be a contributing factor or antifungal therapy may be an effective antiinflammatory agent.

Chronic Systemic Inflammatory Skin Disease as a Risk Factor for Cardiovascular Disease

Chronic systemic skin disease and cardiovascular disease are multisystem disorders which have been associated with each other for centuries. Recent research has strengthened this association, particularly in systemic inflammatory disease. Here we explore the current literature on psoriasis, hidradenitis suppurativa, lupus erythematosus, acanthosis nigricans, atopic dermatitis, and bullous pemphigoid. Psoriasis is a chronic inflammatory disorder that has been labeled as a risk-modifier for hyperlipidemia and coronary artery disease by the American College of Cardiology ACC lipid guidelines. Cardiovascular disease is also found at a significantly higher rate in patients with hidradenitis suppurativa and lupus erythematosus. Some associations have even been noted between cardiovascular disease and acanthosis nigricans, atopic dermatitis, and bullous pemphigoid. While many of these associations have been attributed to a shared underlying disease process such as chronic systemic inflammation and shared underlying risk factors, these dermatologic manifestations can help to identify patients at higher risk for cardiovascular disease.

Facial and neck erythema associated with dupilumab treatment: A systematic review

BACKGROUND

Neither dupilumab-associated facial erythema nor neck erythema was reported in phase 3 clinical trials for the treatment of atopic dermatitis, but there have been a number of reports of patients developing this adverse event in clinical practice.

OBJECTIVE

To outline all cases of reported dupilumab-associated facial or neck erythema to better characterize this adverse event, and identify potential etiologies and management strategies.

METHODS

A search was conducted on EMBASE and PubMed databases. Two independent reviewers identified relevant studies for inclusion and performed data extraction.

RESULTS

A total of 101 patients from 16 studies were reported to have dupilumab-associated facial or neck erythema. A total of 52 of 101 patients (52%) had baseline atopic dermatitis facial or neck involvement and 45 of 101 (45%) reported different cutaneous symptoms from preexisting atopic dermatitis, possibly suggesting a different etiology. Suggested etiologies included rosacea, allergic contact dermatitis, and head and neck dermatitis. Most commonly used treatments included topical corticosteroids, topical calcineurin inhibitors, and antifungal agents. In the 57 patients with data on the course of the adverse events, improvement was observed in 29, clearance in 4, no response in 16, and worsening in 8. A total of 11 of 101 patients (11%) discontinued dupilumab owing to this adverse event.

LIMITATIONS

Limited diagnostic testing, nonstandardized data collection and reporting across studies, and reliance on retrospective case reports and case series.

CONCLUSION

Some patients receiving dupilumab develop facial or neck erythema that differs from their usual atopic dermatitis symptoms. Prompt identification and empiric treatment may minimize distress and potential discontinuation of dupilumab owing to this adverse event.

Head and neck dermatitis, a subtype of atopic dermatitis induced by Malassezia spp: Clinical aspects and treatment outcomes in adolescent and adult patients

BACKGROUND AND OBJECTIVES

Head and neck dermatitis (HND) is a clinical variant of atopic dermatitis (AD), presenting in adolescence or adulthood and characterized by involvement of the head, neck, and superior part of the trunk. The role of Malassezia spp has been advocated in the pathogenesis of HND, and antifungal agents represent the treatment of choice.

METHODS

A retrospective single-center study was performed to define the clinical features and treatment response of HND among adolescent and adult patients.

RESULTS

Thirty-one patients were identified, 17 with "adolescent-onset" and 14 with "adult-onset" HND. Adolescent-onset HND positively correlated with a past history of AD and presented with exclusive head and neck involvement (P < .05). Adult-onset HND was associated with concomitant widespread atopic eczema, involving the flexural areas of the upper and lower limbs, trunk, nipples, or hands (P < .05). A positive response to itraconazole in combination with topical treatments was observed in both groups.

CONCLUSIONS

This study delineates two HND clinical phenotypes: adolescent vs adult onset. Different characteristics were observed in terms of relationship to AD and eczema localization. A history of AD in childhood and presentation with exclusive involvement of head and neck regions was observed predominantly in the adolescent-onset form, while adult-onset HND often occurred in association with diffuse dermatitis and a past history of AD was less frequent than in the adolescent group. The study is limited by the single-center retrospective nature, which may lead to diagnostic and selection biases, and the small cohort of patients.

Inflammasome-mediated Inflammation by Malassezia in human keratinocytes: A comparative analysis with different strains

Malassezia species are associated with several common dermatologic conditions including pityriasis versicolor, seborrhoeic dermatitis, folliculitis, and atopic dermatitis and dandruff. However, its causal role remains to be established. We intended to explore the role of inflammasome activation in human keratinocytes in response to three different Malassezia species. We compared the different activation patterns of inflammasomes and the expression of pro-inflammatory cytokines and antimicrobial peptides by three different Malassezia species-M. restricta, M. globosa and M. sympodialis-in human keratinocytes. We found that different Malassezia species, especially M. restricta and M. globosa could induce nucleotide-binding oligomerisation domain, leucine-rich repeat and pyrin-domain-containing protein (NLRP)3-apoptosis-associated speck-like protein containing CARD (ASC) inflammasome activation and subsequent interleukin (IL)-1β secretion in human keratinocytes. Malassezia species variably induced thymic stromal lymphopoietin, β-defensin 2, and LL-37. IL-8 mRNA and IL-22 protein significantly increased in the M. sympodialis-treated group, and Chemokine C-C motif ligand (CCL)17 and CCL22 mRNA were increased in response to M. globosa- and M. restricta- treated keratinocytes, respectively. Our data show that various species of Malassezia promote variable inflammatory responses in keratinocytes by activating NLRP3 inflammasomes, pro-inflammatory cytokines and chemokines, and antimicrobial peptides.

Applications of Human Skin Microbiota in the Cutaneous Disorders for Ecology-Based Therapy

The skin represents the exterior interface between the human body with the environment while providing a home to trillions of the commensal microorganisms—collectively referred to as the skin microbiota. These microbes that coexist in an established balance play a pivotal role in the protection of cutaneous health and the orchestration of skin homeostasis. However, the well-controlled but delicate balance can be perturbed by alterations in the skin microbial communities, namely, dysbiosis, often due to commensals defeated by pathogens competing for space and nutrients, which leads to the occurrence of multiple cutaneous disorders. In view of this, the analysis of skin microbiota constituents in skin diseases is crucial for defining the role of commensal microbes and treatment of skin diseases. Emerging evidence shows that the ecology-based therapy of microbial transplantation has been proven as a valid therapeutic strategy for cutaneous disorders caused by skin microbial dysbiosis. Although its mechanism is not well-understood, there are already some applications for ecology-based therapy with the aim of correcting the imbalances on the cutaneous ecosystem. In this review, we summarize the interactions between dysbiosis and the cutaneous disorders, including homeostasis and dysbiosis of skin microbiota, microbial composition in skin diseases, and the mechanisms and applications of reversing or ameliorating the dysbiosis by the targeted manipulation of the skin microbiota, which may contribute to aid development of therapeutic modality for ecology-based therapy.

Overview of the Potential Role of Malassezia in Gut Health and Disease

Malassezia is the most prevalent fungus identified in the human skin microbiota; originally described at the end of the nineteenth century, this genus is composed of at least 14 species. The role of Malassezia on the skin remains controversial because this genus has been associated with both healthy skin and pathologies (dermatitis, eczema, etc.). However, with the recent development of next-generation sequencing methods, allowing the description of the fungal diversity of various microbiota, Malassezia has also been identified as a resident fungus of diverse niches such as the gut or breast milk. A potential role for Malassezia in gut inflammation and cancer has also been suggested by recent studies. The aim of this review is to describe the findings on Malassezia in these unusual niches, to investigate what is known of the adaptation of Malassezia to the gut environment and to speculate on the role of this yeast in the host physiology specifically related to the gastrointestinal tract.

Diagnosis and management of moderate to severe atopic dermatitis in adolescents. A Consensus by the Italian Society of Dermatology and Venereology (SIDeMaST), the Italian Association of Hospital Dermatologists and Public Health (ADOI), the Italian Association of Hospital and Territorial Allergists and Immunologists (AAIITO), the Italian Society of Allergy, Asthma and Clinical Immunology (SIAAIC), the Italian Society of Pediatric Allergy and Immunology (SIAIP), the Italian Society of Allergological, Occupational and Environmental Dermatology (SIDAPA), and the Italian Society of Pediatric Dermatology (SIDerP)

Atopic dermatitis (AD) is a chronic inflammatory disease with increasing global incidence, which has a multifactorial pathogenesis and a variable expressivity. Clinical features of AD are different in adults compared to children, but it is well recognized the substantial impact of the disease on patients' quality of life at any age. Indeed, little is known about AD in adolescence, a period of life generally associated with high psychological burden and vulnerability to depression. Guidelines for the management of AD are available for both children and adults but specific guidelines for the diagnosis and treatment of AD in adolescents are lacking. Seven Italian scientific societies of dermatologists, allergists, and pediatric allergists joined in a specific meeting to provide practical guidance for the diagnosis and management of moderate-to-severe adolescent AD suitable for the Italian clinical practice. Through a modified Delphi procedure, consensus was reached by 59 Italian experts in the management of AD on 20 statements covering five areas of interest about adolescent AD, including disease complexity, burden and social impact, diagnosis and definition of severity, current treatments, and new biologic therapies. This paper reports recommendations for the diagnosis and management of AD specifically in adolescents, pointing out some peculiar clinical features and focusing on the choice of medications. Dupilumab, the first biologic approved for the treatment of adolescents with AD, represents a useful treatment option due to its efficacy and reassuring safety profile.

The clinical significance of fungi in atopic dermatitis

Atopic dermatitis (AD) is one of the most common chronic inflammatory skin diseases and is caused by multiple factors including genetic factors, skin barrier defects, host immune responses, allergen sensitivity, environmental effects, and infections. Commonly, bacterial and viral infections are present in the eczematous lesions of AD patients and clearly aggravate the symptoms. However, studies of fungal infections in AD are limited in spite of the fact that there are reports showing that Malassezia, Candida, and some dermatophytes can affect the symptoms of AD. Moreover, certain fungal infections are sometimes overlooked and need to be considered particularly in AD patients with treatment failure as clinical features of those fungal infections could mimic eczematous lesions in AD. Here, we review the epidemiology, pathogenesis, clinical manifestations, and overlooked features of fungal infections associated with the symptoms of AD including the diagnosis and effectiveness of fungal treatments in AD patients.

Malassezia-Associated Skin Diseases, the Use of Diagnostics and Treatment

Yeasts of the genus, Malassezia, formerly known as Pityrosporum, are lipophilic yeasts, which are a part of the normal skin flora (microbiome). Malassezia colonize the human skin after birth and must therefore, as commensals, be normally tolerated by the human immune system. The Malassezia yeasts also have a pathogenic potential where they can, under appropriate conditions, invade the stratum corneum and interact with the host immune system, both directly but also through chemical mediators. The species distribution on the skin and the pathogenetic potential of the yeast varies between different Malassezia related diseases such as head and neck dermatitis, seborrheic dermatitis, pityriasis versicolor, and Malassezia folliculitis. The diagnostic methods used to confirm the presence of Malassezia yeasts include direct microcopy, culture based methods (often a combination of morphological features of the isolate combined with biochemical test), molecular based methods such as Polymerase Chain Reaction techniques, and Matrix Assisted Laser Desorption/Ionization—Time Of Flight mass spectrometry and the chemical imprint method Raman spectroscopy. Skin diseases caused by Malassezia are usually treated with antifungal therapy and if there are associated inflammatory skin mechanisms this is often supplemented by anti-inflammatory therapy. The aim of this paper is to provide an overview of Malassezia related skin disease, diagnostic methods and treatment options.

The role of bacterial skin infections in atopic dermatitis: expert statement and review from the International Eczema Council Skin Infection Group

Patients with atopic dermatitis (AD) have an increased risk of bacterial skin infections, which cause significant morbidity and, if untreated, may become systemic. Staphylococcus aureus colonizes the skin of most patients with AD and is the most common organism to cause infections. Overt bacterial infection is easily recognized by the appearance of weeping lesions, honey‐coloured crusts and pustules. However, the wide variability in clinical presentation of bacterial infection in AD and the inherent features of AD – cutaneous erythema and warmth, oozing associated with oedema, and regional lymphadenopathy – overlap with those of infection, making clinical diagnosis challenging. Furthermore, some features may be masked because of anatomical site‐ and skin‐type‐specific features, and the high frequency of S. aureus colonization in AD makes positive skin swab culture of suspected infection unreliable as a diagnostic tool. The host mechanisms and microbial virulence factors that underlie S. aureus colonization and infection in AD are incompletely understood. The aim of this article is to present the latest evidence from animal and human studies, including recent microbiome research, to define the clinical features of bacterial infections in AD, and to summarize our current understanding of the host and bacterial factors that influence microbial colonization and virulence.

The Skin Commensal Yeast Malassezia Triggers a Type 17 Response that Coordinates Anti-fungal Immunity and Exacerbates Skin Inflammation

Commensal fungi of the mammalian skin, such as those of the genus Malassezia, are associated with atopic dermatitis and other common inflammatory skin disorders. Understanding of the causative relationship between fungal commensalism and disease manifestation remains incomplete. By developing a murine epicutaneous infection model, we found Malassezia spp. selectively induce IL-17 and related cytokines. This response is key in preventing fungal overgrowth on the skin, as disruption of the IL-23-IL-17 axis compromises Malassezia-specific cutaneous immunity. Under conditions of impaired skin integrity, mimicking a hallmark of atopic dermatitis, the presence of Malassezia dramatically aggravates cutaneous inflammation, which again was IL-23 and IL-17 dependent. Consistently, we found a CCR6⁺ Th17 subset of memory T cells to be Malassezia specific in both healthy individuals and atopic dermatitis patients, whereby the latter showed enhanced frequency of these cells. Thus, the Malassezia-induced type 17 response is pivotal in orchestrating antifungal immunity and in actively promoting skin inflammation.