β-Endorphin enhances the phospholipase activity of the dandruff causing fungi Malassezia globosa and Malassezia restricta

Adult and infantile seborrheic dermatitis: update on current state of evidence and potential research frontiers

Seborrheic dermatitis (SD) is a highly prevalent dermatological condition globally. The condition demonstrates bimodal presentation with what is commonly thought to be two subtypes: adult/adolescent seborrheic dermatitis (ASD) and infantile seborrheic dermatitis (ISD). Despite the common prevalence of ASD and ISD, there remains uncertainty around the underlying pathogenetic mechanisms, risk factors, and appropriate classification of the disease(s). This narrative review summarizes the current understanding of the epidemiology, presentation, and pathogenetic factors like epidermal barrier dysfunction, lipid abnormalities, and cutaneous microbiome for ASD and ISD. Elements such as immune responsiveness, neuroendocrine factors, and genetics in these disease states are also investigated. Throughout our review, we highlight shared features and discrepancies between ASD and ISD that are present in the literature and discuss potential avenues for future research that explore these disease states. We aim to contribute to the medical discourse on ASD and ISD and increase awareness of the need for additional research around these conditions, ultimately informing better targeting of therapeutics moving forward.

Part 2: Understanding the role of Malassezia spp. in skin disorders: pathogenesis of Malassezia associated skin infections

INTRODUCTION

Malassezia is a major component of the skin microbiome, a lipophilic symbiotic organism of the mammalian skin, which can switch to opportunistic pathogens triggering multiple dermatological disorders in humans and animals. This phenomenon is favored by endogenous and exogenous host predisposing factors, which may switch Malassezia from a commensal to a pathogenic phenotype.

AREA COVERED

This review summarizes and discusses the most recent literature on the pathogenesis of Malassezia yeasts, which ultimately results in skin disorders with different clinical presentation. A literature search of Malassezia pathogenesis was performed via PubMed and Google scholar (up to May 2023), using the following keywords: Pathogenesis and Malassezia;host risk factors and Malassezia, Malassezia and skin disorders; Malassezia and virulence factors: Malassezia and metabolite production; Immunology and Malassezia.

EXPERT OPINION

Malassezia yeasts can maintain skin homeostasis being part of the cutaneous mycobiota; however, when the environmental or host conditions change, these yeasts are endowed with a remarkable plasticity and adaptation by modifying their metabolism and thus contributing to the appearance or aggravation of human and animal skin disorders.

Heat-killed Lacticaseibacillus paracasei GMNL-653 ameliorates human scalp health by regulating scalp microbiome

BACKGROUND

The equilibrium of the scalp microbiome is important for maintaining healthy scalp conditions, including sebum secretion, dandruff, and hair growth. Many different strategies to improve scalp health have been reported; however, the effect of postbiotics, such as heat-killed probiotics, on scalp health remains unclear. We examined the beneficial effects of heat-killed probiotics consisting of Lacticaseibacillus paracasei, GMNL-653, on scalp health.

RESULTS

Heat-killed GMNL-653 could co-aggregate with scalp commensal fungi, Malassezia furfur, in vitro, and the GMNL-653-derived lipoteichoic acid inhibited the biofilm formation of M. furfur on Hs68 fibroblast cells. The mRNA of hair follicle growth factors, including insulin-like growth factor-1 receptor (IGF-1R), vascular endothelial growth factor, IGF-1, and keratinocyte growth factor was up-regulated in skin-related human cell lines Hs68 and HaCaT after treatment with heat-killed GMNL-653. For clinical observations, we recruited 22 volunteer participants to use the shampoo containing the heat-killed GMNL-653 for 5 months and subsequently measured their scalp conditions, including sebum secretion, dandruff formation, and hair growth. We applied polymerase chain reaction (PCR) to detect the scalp microbiota of M. restricta, M. globosa, Cutibacterium acnes, and Staphylococcus epidermidis. A decrease in dandruff and oil secretion and an increase in hair growth in the human scalp were observed after the use of heat-killed GMNL-653-containing shampoo. The increased abundance of M. globosa and the decreased abundance of M. restricta and C. acnes were also observed. We further found that accumulated L. paracasei abundance was positively correlated with M. globosa abundance and negatively correlated with C. acnes abundance. S. epidermidis and C. acnes abundance was negatively correlated with M. globosa abundance and positively correlated with M. restricta. Meanwhile, M. globosa and M. restricta abundances were negatively associated with each other. C. acnes and S. epidermidis abundances were statistically positively correlated with sebum secretion and dandruff, respectively, in our shampoo clinical trial.

CONCLUSION

Our study provides a new strategy for human scalp health care using the heat-killed probiotics GMNL-653-containing shampoo. The mechanism may be correlated with the microbiota shift.

Cutaneous Fungal Infections in Patients Experiencing Homelessness and Treatment in Low-Resource Settings: A Scoping Review

Patients experiencing homelessness (PEH) suffer from a high burden of cutaneous fungal infections. Preventative treatment is important as such infections can lead to harmful complications such as cellulitis and even osteomyelitis. There are sparse data regarding cutaneous fungal infections of homeless populations and management in low-resource settings. A MEDLINE search was conducted using the key terms "cutaneous," "fungal," "infections," "dermatophytes," and "homeless." The search included case-control, cohort, and randomized controlled trials published in the English language. This scoping review of studies yielded information with regard to practical treatment advice for providers in low-resource settings, including medical, hygiene, prevention, and treatment options for PEH with cutaneous fungal infections, the most common of which were tinea pedis (3-38%) and onychomycosis (1.6-15.5%). Few studies have been conducted on the differences between sheltered and unsheltered homeless patients, which can have treatment implications. Systemic antifungal therapy should be carefully considered for diffuse, refractory, or nail-based cutaneous fungal infections if there is a history of alcohol use disorder or liver disease. While PEH have a high risk of alcohol use disorder, this can make definitive treatment challenging.

Malassezia spp. Yeasts of Emerging Concern in Fungemia

Malassezia spp. are lipid-dependent yeasts, inhabiting the skin and mucosa of humans and animals. They are involved in a variety of skin disorders in humans and animals and may cause bloodstream infections in severely immunocompromised patients. Despite a tremendous increase in scientific knowledge of these yeasts during the last two decades, the epidemiology of Malassezia spp. related to fungemia remains largely underestimated most likely due to the difficulty in the isolation of these yeasts species due to their lipid-dependence. This review summarizes and discusses the most recent literature on Malassezia spp. infection and fungemia, its occurrence, pathogenicity mechanisms, diagnostic methods, in vitro susceptibility testing and therapeutic approaches.

Endogenous opiates and behavior: 2017

This paper is the fortieth consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2017 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).

Secreted Hydrolytic and Haemolytic Activities of Malassezia Clinical Strains

Malassezia yeasts are opportunistic pathogens associated with a number of skin diseases in animals and humans. The free fatty acids released through these organisms' lipase and phospholipase activities trigger inflammation in the host; thus, these lipase and phospholipase activities are widely recognised as some of the most important factors in Malassezia pathogenesis. In this study, we sought to investigate and examine the relationship between these secreted hydrolytic activities and haemolytic activity in newly isolated Malassezia clinical strains. This characterisation was expected to elucidate pathogenicity of this fungus. We isolated 35 clinical strains of Malassezia spp.; the most frequently isolated species were M. sympodialis and M. furfur. Next, we analysed the hydrolytic activities of all of these clinical isolates; all of these strains (except for one M. dermatis isolate) showed detectable lipase and phospholipase activities against 4-nitrophenyl palmitate and L-α-phosphatidylcholine, dipalmitoyl, respectively. Most of the M. globosa isolates showed higher lipase activities than isolates of other Malassezia species. In terms of phospholipase activity, no significant difference was observed among species of Malassezia, although one isolate of M. globosa showed considerably higher phospholipase activity than the others. All tested strains also exhibited haemolytic activity, both as determined using 5% (v/v) sheep blood agar (halo assay) and by quantitative assay. Although all tested strains showed detectable haemolytic activity, we did not observe an apparent correlation between the secreted lipase and phospholipase activities and haemolytic activity. We infer that the haemolytic activities of Malassezia spp. are mediated by non-enzymatic factor(s) that are present in the secreted samples.

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.

Spondyloarthritis, Acute Anterior Uveitis, and Fungi: Updating the Catterall-King Hypothesis

Spondyloarthritis is a common type of arthritis which affects mostly adults. It consists of idiopathic chronic inflammation of the spine, joints, eyes, skin, gut, and prostate. Inflammation is often asymptomatic, especially in the gut and prostate. The HLA-B*27 allele group, which presents intracellular peptides to CD8+ T cells, is by far the strongest risk factor for spondyloarthritis. The precise mechanisms and antigens remain unknown. In 1959, Catterall and King advanced a novel hypothesis explaining the etiology of spondyloarthritis: an as-yet-unrecognized sexually acquired microbe would be causing all spondyloarthritis types, including acute anterior uveitis. Recent studies suggest an unrecognized sexually acquired fungal infection may be involved in prostate cancer and perhaps multiple sclerosis. This warrants reanalyzing the Catterall-King hypothesis based on the current literature. In the last decade, many links between spondyloarthritis and fungal infections have been found. Antibodies against the fungal cell wall component mannan are elevated in spondyloarthritis. Functional polymorphisms in genes regulating the innate immune response against fungi have been associated with spondyloarthritis (CARD9 and IL23R). Psoriasis and inflammatory bowel disease, two common comorbidities of spondyloarthritis, are both strongly associated with fungi. Evidence reviewed here lends credence to the Catterall-King hypothesis and implicates a common fungal etiology in prostate cancer, benign prostatic hyperplasia, multiple sclerosis, psoriasis, inflammatory bowel disease, and spondyloarthritis. However, the evidence available at this time is insufficient to definitely confirm this hypothesis. Future studies investigating the microbiome in relation to these conditions should screen specimens for fungi in addition to bacteria. Future clinical studies of spondyloarthritis should consider antifungals which are effective in psoriasis and multiple sclerosis, such as dimethyl fumarate and nystatin.