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Journal of the American Academy of... Mar 2024Seborrheic dermatitis (SD) is a common skin disease with signs and symptoms that may vary by skin color, associated medical conditions, environmental factors, and... (Review)
Review
Seborrheic dermatitis (SD) is a common skin disease with signs and symptoms that may vary by skin color, associated medical conditions, environmental factors, and vehicle preference. Diagnosis of SD is based on presence of flaky, "greasy" patches, and/or thin plaques accompanied by erythema of the scalp, face, ears, chest, and groin and is associated with pruritus in many patients. The presentation may vary in different skin types and hyper- or hypopigmentation may occur, with or without erythema and minimal or no scaling. While the pathogenesis is not certain, 3 key factors generally agreed upon include lipid secretion by sebaceous glands, Malassezia spp. colonization, and some form of immunologic dysregulation that predisposes the patient to SD. Treatment involves reducing proliferation of, and inflammatory response to, Malassezia spp. Topical therapies, including antifungal agents and low potency corticosteroids, are the mainstay of treatment but may be limited by efficacy and side effects. Few novel treatments for SD are currently being studied; however, clinical trials assessing the use of topical phosphodiesterase-4 inhibitors have been completed. Improving outcomes in SD requires recognizing patient-specific manifestations/locations of the disease, including increased awareness of how it affects people of all skin types.
Topics: Humans; Dermatitis, Seborrheic; Antifungal Agents; Adrenal Cortex Hormones; Erythema; Malassezia
PubMed: 36538948
DOI: 10.1016/j.jaad.2022.12.017 -
Life (Basel, Switzerland) Oct 2023This narrative review presents a comprehensive overview of the diagnosis and management of pityriasis versicolor (PV), a common superficial fungal infection caused by... (Review)
Review
This narrative review presents a comprehensive overview of the diagnosis and management of pityriasis versicolor (PV), a common superficial fungal infection caused by the yeast Malassezia. PV is characterised by scaly hypopigmented or hyperpigmented patches, primarily affecting the upper trunk, neck, and upper arms. Regarding commensal interactions, Malassezia utilises nutrient sources without affecting the human host. In cases of pathogenicity, Malassezia can directly harm the host via virulence factors or toxins, or indirectly by triggering damaging host responses. The diagnosis typically relies on recognising characteristic clinical features. Due to the wide variability in its clinical presentation, recognising the differential diagnosis is critical. In this paper, we discuss the clinical differentials, with their dermatoscopic presentation, but also describe a range of helpful diagnostic techniques (microscopy, conventional and ultraviolet-induced fluorescence dermatoscopy, and confocal microscopy). Topical therapies are the primary treatment for PV, encompassing non-specific antifungal agents like sulphur with salicylic acid, selenium sulphide 2.5%, and zinc pyrithione. Additionally, specific topical antifungal medications with either fungicidal or fungistatic properties may also be incorporated into the topical treatment regimen, such as imidazoles, allylamines, and ciclopirox olamine. Systemic therapies might occasionally be used. Patient education and the promotion of good personal hygiene are pivotal to reduce the risk of recurrence. In recurrent cases, particularly during warmer and more humid periods, prolonged prophylaxis with topical agents should be considered.
PubMed: 37895478
DOI: 10.3390/life13102097 -
Annals of Allergy, Asthma & Immunology... Feb 2024Atopic dermatitis (AD) is the most common inflammatory skin disease worldwide, affecting 20% of children and 5% of adults. One critical component in the pathophysiology... (Review)
Review
Atopic dermatitis (AD) is the most common inflammatory skin disease worldwide, affecting 20% of children and 5% of adults. One critical component in the pathophysiology of AD is the epidermal skin barrier, with its outermost layer, the stratum corneum (SC), conferring biochemical properties that enable resilience against environmental threats and maintain homeostasis. The skin barrier may be conceptualized as a key facilitator of complex interactions between genetics, host immunity, the cutaneous microbiome, and environmental exposures. The key genetic risk factor for AD development and persistence is a loss-of-function mutation in FLG, with recent advances in genomics focusing on rare variant discovery, establishment of pathogenic mechanisms, and exploration of the role of other epidermal differentiation complex gene variants in AD. Aberrant type 2 inflammatory responses down-regulate the transcription of key epidermal barrier genes, alter the composition of SC lipids, and induce further injury through a neurocutaneous feedback loop and the itch-scratch cycle. The dysbiotic epidermis exhibits reduced bacterial diversity and enhanced colonization with Staphylococcus and Malassezia species, which contribute to both direct barrier injury through the action of bacterial toxins and perpetuation of the inflammatory cascades. Enhanced understanding of each of the pathogenic mechanisms underpinning barrier disruption has led to the development of novel topical and systemic molecules, including interleukin (IL)-4Ra, IL-13, PDE4, and Janus-associated kinase inhibitors, whose clinical effectiveness exceeds conventional treatment modalities. In this narrative review, we aim to summarize the current understanding of the above-mentioned pathophysiological and therapeutic mechanisms, with a focus on the genetic, cellular, and molecular mechanisms underpinning AD development.
Topics: Child; Humans; Dermatitis, Atopic; Filaggrin Proteins; Intermediate Filament Proteins; Skin; Epidermis
PubMed: 37758055
DOI: 10.1016/j.anai.2023.09.009 -
Veterinary Journal (London, England :... Apr 2024Malassezia are members of the mycobiome of dogs and cats. In the presence of an underlying disease, these yeasts can proliferate, attach to the skin or mucosa to induce... (Review)
Review
Malassezia are members of the mycobiome of dogs and cats. In the presence of an underlying disease, these yeasts can proliferate, attach to the skin or mucosa to induce a secondary Malassezia dermatitis, otitis externa or paronychia. Since allergic dermatitis is one of the most common underlying causes, diagnostic investigation for allergy is often indicated. Cats may suffer from various other underlying problems, especially where Malassezia dermatitis is generalised. Malassezia dermatitis in dogs and cats is chronic, relapsing and pruritic. Direct cytology from dermatological lesions and the ear canal, showing "peanut-shaped" budding yeasts, facilitates a rapid and reliable diagnosis. Topical treatment includes antiseptic and antifungal azole-based products. Systemic treatment with oral antifungals is indicated only in severe or refractory disease. Identification and treatment of the underlying cause is essential for an optimal response. In this evidence-based narrative review, we discuss the clinical presentation of Malassezia dermatitis in dogs and cats, underlying comorbidities, and diagnostic considerations. Treatment is discussed in light of emerging evidence of antifungal resistance and the authors' clinical experience.
Topics: Animals; Cats; Dogs; Malassezia; Dermatomycoses; Cat Diseases; Antifungal Agents; Dog Diseases; Neoplasm Recurrence, Local; Dermatitis
PubMed: 38431127
DOI: 10.1016/j.tvjl.2024.106084 -
Journal of Inflammation Research 2024As the body's largest organ, the skin harbors a highly diverse microbiota, playing a crucial role in resisting foreign pathogens, nurturing the immune system, and... (Review)
Review
As the body's largest organ, the skin harbors a highly diverse microbiota, playing a crucial role in resisting foreign pathogens, nurturing the immune system, and metabolizing natural products. The dysregulation of human skin microbiota is implicated in immune dysregulation and inflammatory responses. This review delineates the microbial alterations and immune dysregulation features in common Inflammatory Skin Diseases (ISDs) such as psoriasis, rosacea, atopic dermatitis(AD), seborrheic dermatitis(SD), diaper dermatitis(DD), and (MF).The skin microbiota, a complex and evolving community, undergoes changes in composition and function that can compromise the skin microbial barrier. These alterations induce water loss and abnormal lipid metabolism, contributing to the onset of ISDs. Additionally, microorganisms release toxins, like secreted α toxins and proteases, which may dissolve the stratum corneum, impairing skin barrier function and allowing entry into the bloodstream. Microbes entering the bloodstream activate molecular signals, leading to immune disorders and subsequent skin inflammatory responses. For instance, stimulates dendritic cells(DCs) to release IL-12 and IL-23, differentiating into a Th17 cell population and producing proinflammatory mediators such as IL-17, IL-22, TNF-α, and IFN-α.This review offers new insights into the role of the human skin microbiota in ISDs, paving the way for future skin microbiome-specific targeted therapies.
PubMed: 38375021
DOI: 10.2147/JIR.S441100 -
Microbiology Spectrum Aug 2023The genus comprises lipid-dependent yeasts that have long been associated with common skin diseases, and have recently been linked with Crohn's disease and certain...
The genus comprises lipid-dependent yeasts that have long been associated with common skin diseases, and have recently been linked with Crohn's disease and certain cancers. Understanding susceptibility to diverse antimicrobial agents is crucial for identifying effective antifungal therapies. Here, we tested the efficacy of isavuconazole, itraconazole, terbinafine, and artemisinin against three species: , and . Using broth microdilution, we found antifungal properties for the two previously unstudied antimicrobials: isavuconazole and artemisinin. Overall, all species were particularly susceptible to itraconazole, with a MIC range from 0.007 to 0.110 μg/mL. The genus is known to be involved in a variety of skin conditions and has recently been associated with diseases such as Crohn's disease, pancreatic ductal carcinoma, and breast cancer. This work was completed to assess susceptibility to a variety of antimicrobial drugs on three species, in particular , which is an abundant species both on human skin and internal organs and has been implicated in Crohn's disease. We tested two previously unstudied drugs and developed a new testing method to overcome current limitations for measuring growth inhibition of slow-growing strains.
Topics: Humans; Antifungal Agents; Itraconazole; Malassezia; Crohn Disease; Dermatomycoses; Microbial Sensitivity Tests
PubMed: 37310217
DOI: 10.1128/spectrum.05076-22 -
Nature Aug 2023A growing body of literature suggests that alterations in the human microbiome are causative of disease initiation and progression. Aykut et al. present data supporting...
A growing body of literature suggests that alterations in the human microbiome are causative of disease initiation and progression. Aykut et al. present data supporting the argument that alterations in the gut fungal microbiome (the “mycobiome”), along with the presence of fungal elements within pancreatic tissue (specifically those of the genus , are associated with pancreatic oncogenesis. Upon analyzing the human sequencing data presented in the original manuscript, we found few fungal reads in pancreatic tissue samples and did not identify differences in pancreatic or gut mycobiome composition between healthy and pancreatic ductal adenocarcinoma (PDAC) patients. Our re-analysis of these data does not support an association between an intrinsic pancreatic mycobiome and the development of human PDAC, and illustrates the challenges in analyzing microbiome sequencing data from low biomass samples.
Topics: Humans; Mycobiome; Pancreatic Neoplasms; Pancreas; Carcinogenesis
PubMed: 37532819
DOI: 10.1038/s41586-023-06292-1 -
Frontiers in Aging Neuroscience 2023Controversies surrounding the validity of the toxic proteinopathy theory of Alzheimer's disease have led the scientific community to seek alternative theories in the... (Review)
Review
Controversies surrounding the validity of the toxic proteinopathy theory of Alzheimer's disease have led the scientific community to seek alternative theories in the pathogenesis of neurodegenerative disorders (ND). Recent studies have provided evidence of a microbiome in the central nervous system. Some have hypothesized that brain-inhabiting organisms induce chronic neuroinflammation, leading to the development of a spectrum of NDs. Bacteria such as , , and have been found to inhabit the brains of ND patients. Furthermore, several fungi, including and species, have been identified in the central nervous system of these patients. However, there remains several limitations to the brain microbiome hypothesis. Varying results across the literature, concerns regarding sample contamination, and the presence of exogenous deoxyribonucleic acids have led to doubts about the hypothesis. These results provide valuable insight into the pathogenesis of NDs. Herein, we provide a review of the evidence for and against the brain microbiome theory and describe the difficulties facing the hypothesis. Additionally, we define possible mechanisms of bacterial invasion of the brain and organism-related neurodegeneration in NDs and the potential therapeutic premises of this theory.
PubMed: 37927338
DOI: 10.3389/fnagi.2023.1240945