The Skin Microbiota and Itch: Is There a Link?

The multifaceted role of autophagy in skin autoimmune disorders: a guardian or culprit?

Autophagy is a cellular process that functions to maintain intracellular homeostasis via the degradation and recycling of defective organelles or damaged proteins. This dynamic mechanism participates in various biological processes, such as the regulation of cellular differentiation, proliferation, survival, and the modulation of inflammation and immune responses. Recent evidence has demonstrated the involvement of polymorphisms in autophagy-related genes in various skin autoimmune diseases. In addition, autophagy, along with autophagy-related proteins, also contributes to homeostasis maintenance and immune regulation in the skin, which is associated with skin autoimmune disorders. This review aims to provide an overview of the multifaceted role of autophagy in skin autoimmune diseases and shed light on the potential of autophagy-targeting therapeutic strategies in dermatology.

Interaction between the microbiota and the skin barrier in aging skin: a comprehensive review

The interplay between the microbes and the skin barrier holds pivotal significance in skin health and aging. The skin and gut, both of which are critical immune and neuroendocrine system, harbor microbes that are kept in balance. Microbial shifts are seen with aging and may accelerate age-related skin changes. This comprehensive review investigates the intricate connection between microbe dynamics, skin barrier, and the aging process. The gut microbe plays essential roles in the human body, safeguarding the host, modulating metabolism, and shaping immunity. Aging can perturb the gut microbiome which in turn accentuates inflammaging by further promoting senescent cell accumulation and compromising the host's immune response. Skin microbiota diligently upholds the epidermal barrier, adeptly fending off pathogens. The aging skin encompasses alterations in the stratum corneum structure and lipid content, which negatively impact the skin's barrier function with decreased moisture retention and increased vulnerability to infection. Efficacious restoration of the skin barrier and dysbiosis with strategic integration of acidic cleansers, emollients with optimal lipid composition, antioxidants, and judicious photoprotection may be a proactive approach to aging. Furthermore, modulation of the gut-skin axis through probiotics, prebiotics, and postbiotics emerges as a promising avenue to enhance skin health as studies have substantiated their efficacy in enhancing hydration, reducing wrinkles, and fortifying barrier integrity. In summary, the intricate interplay between microbes and skin barrier function is intrinsically woven into the tapestry of aging. Sound understanding of these interactions, coupled with strategic interventions aimed at recalibrating the microbiota and barrier equilibrium, holds the potential to ameliorate skin aging. Further in-depth studies are necessary to better understand skin-aging and develop targeted strategies for successful aging.

What's New in Cutaneous T-Cell Lymphoma-Associated Pruritus

Cutaneous T-cell lymphomas are a heterogenous group of lymphomas that cause various skin manifestations. Severe pruritus occurs frequently in cutaneous T-cell lymphoma and negatively impacts patients' quality of life. The pathophysiology of cutaneous T-cell lymphoma-associated itch is complex and involves various immune cells, inflammatory cytokines, and neuroimmune interactions. Treating cutaneous T-cell lymphoma pruritus can be challenging, and there have been few randomized controlled studies evaluating the use of antipruritic treatments in these patients. Systemic therapies targeting the disease have also been shown to have some antipruritic effects. Furthermore, although biologic therapy has revolutionized the treatment of other pruritic skin conditions, the use of biologics in cutaneous T-cell lymphoma remains controversial.

An Altered Skin and Gut Microbiota Are Involved in the Modulation of Itch in Atopic Dermatitis

Skin and gut microbiota play an important role in the pathogenesis of atopic dermatitis (AD). An alteration of the microbiota diversity modulates the development and course of AD, e.g., decreased microbiome diversity correlates with disease severity, particularly in lesional skin of AD. Itch is a hallmark of AD with unsatisfying treatment until now. Recent evidence suggests a possible role of microbiota in altering itch in AD through gut-skin-brain interactions. The microbial metabolites, proinflammatory cytokines, and impaired immune response lead to a modulation of histamine-independent itch, disruption of epidermal barrier, and central sensitization of itch mechanisms. The positive impact of probiotics in alleviating itch in AD supports this hypothesis, which may lead to novel strategies for managing itchy skin in AD patients. This review summarizes the emerging findings on the correlation between an altered microbiota and gut-skin-brain axis in AD, especially in modulating itchy skin.

Effects of Dexmedetomidine on Postoperative Pain and Recovery Time in Obese Patients

Objective

The objective of this study is to investigate the effect of dexmedetomidine on postoperative pain and recovery time in obese patients.

Methods

A total of 100 obese patients with body mass index (BMI) ≥ 30 kg/m² who underwent laparoscopic sleeve gastrectomy under general anesthesia in our hospital from January 2019 to December 2021 were included and assigned into DEX group (dexmedetomidine group) and NS group (normal saline group). The bariatric surgery patients who were given normal saline pump were the NS group (n = 50), and the bariatric surgery patients who were given the dexmedetomidine pump were the DEX group (n = 50). The patients in the DEX group were given continuous intravenous infusion of dexmedetomidine before, during, and after induction of anesthesia at a dose of 0.4 μg. kg-1. h-1, 0.4 μg·kg-1. h-1, 0.2 μg·kg-1. h-1, respectively. The NS group was infused with the same volume of normal saline for the same time. The two groups of patients were treated with the same anesthesia induction and maintenance program. By comparing the operation, anesthesia, postoperative extubation, and recovery time of the two groups of patients, the effect of dexmedetomidine on the postoperative recovery time of obese patients was analyzed. Visual analogue scale (VAS) and adverse reactions were compared to analyze the effect of dexmedetomidine on postoperative pain in obese patients.

Results

The operation, anesthesia, postoperative extubation, and recovery time of the DEX group were significantly lower than those of the NS group, whereas the VAS and adverse reactions were significantly lower than those in the NS group (P < 0.05).

Conclusion

An appropriate dose of dexmedetomidine in bariatric surgery for morbidly obese patients can effectively shorten the recovery time and extubation time of patients, reduce postoperative pain and the incidence of adverse reactions, and is worthy of clinical application. Dexmedetomidine 2 μg/kg has promising anesthesia benefits in bariatric surgery of obese patients, can provide favorable analgesia and quality of recovery, help reduce the degree of stress response of patients, and does not increase the risk of adverse events. However, this study has certain limitations, so physicians should tailor the dosage according to the patient's physical condition in clinical practice.

Exploring the Role of Staphylococcus aureus in Inflammatory Diseases

Staphylococcus aureus is a very common Gram-positive bacterium, and S. aureus infections play an extremely important role in a variety of diseases. This paper describes the types of virulence factors involved, the inflammatory cells activated, the process of host cell death, and the associated diseases caused by S. aureus. S. aureus can secrete a variety of enterotoxins and other toxins to trigger inflammatory responses and activate inflammatory cells, such as keratinocytes, helper T cells, innate lymphoid cells, macrophages, dendritic cells, mast cells, neutrophils, eosinophils, and basophils. Activated inflammatory cells can express various cytokines and induce an inflammatory response. S. aureus can also induce host cell death through pyroptosis, apoptosis, necroptosis, autophagy, etc. This article discusses S. aureus and MRSA (methicillin-resistant S. aureus) in atopic dermatitis, psoriasis, pulmonary cystic fibrosis, allergic asthma, food poisoning, sarcoidosis, multiple sclerosis, and osteomyelitis. Summarizing the pathogenic mechanism of Staphylococcus aureus provides a basis for the targeted treatment of Staphylococcus aureus infection.

Neuro-immune communication regulating pruritus in atopic dermatitis

Atopic dermatitis (AD) is a common, chronic-relapsing inflammatory skin disease with significant disease burden. Genetic and environmental trigger factors contribute to AD, activating two of our largest organs, the nervous and immune system. Dysregulation of neuro-immune circuits plays a key role in the pathophysiology of AD causing inflammation, pruritus, pain, and barrier dysfunction. Sensory nerves can be activated by environmental or endogenous trigger factors transmitting itch stimuli to the brain. Upon stimulation, sensory nerve endings also release neuromediators into the skin contributing again to inflammation, barrier dysfunction and itch. Additionally, dysfunctional peripheral and central neuronal structures contribute to neuroinflammation, sensitization, nerve elongation, neuropathic itch, thus chronification and therapy-resistance. Consequently, neuro-immune circuits in skin and central nervous system may be targets to treat pruritus in AD. Cytokines, chemokines, proteases, lipids, opioids, ions excite/sensitize sensory nerve endings not only induce itch but further aggravate/perpetuate inflammation, skin barrier disruption, and pruritus. Thus, targeted therapies for neuro-immune circuits as well as pathway inhibitors (e.g., kinase inhibitors) may be beneficial to control pruritus in AD either in systemic and/or topical form. Understanding neuro-immune circuits and neuronal signaling will optimize our approach to control all pathological mechanisms in AD, inflammation, barrier dysfunction and pruritus.

Topical Treatment of Colquhounia Root Relieves Skin Inflammation and Itch in Imiquimod-Induced Psoriasiform Dermatitis in Mice

Itch is one of the major clinical manifestations of psoriasis, which is closely related with neurogenic inflammation and difficult to control. Colquhounia Root (CR) is a Chinese herb exhibiting broad bioactivities on anti-inflammation. This study was designed to explore the antipsoriatic and anti-itch potential of CR and its underlying mechanisms. Mice in a model of imiquimod-induced psoriasiform dermatitis were treated topically with CR for 7 days, and the severity of skin lesions and itch was significantly ameliorated. CR reduced the inflammatory cell infiltration, as well as mast cells in skins. Particularly, the expression of inflammatory cytokines and chemokine including Il17a, Il22, and Ccl20 and itch-related molecules such as SP, CGRP, and NGF in lesions were decreased in diseased mice upon application with CR. The normal human epidermal keratinocytes were stimulated with the M5 cytokine cocktail, the mixture of IL-17A, IL-22, Oncostatin M, IL-1α, and TNF-α, and cell viability and mRNA expression levels of inflammatory factors and itch-related molecules were measured after being treated with CR. We found that CR inhibited both cell hyperproliferation and overexpression of inflammatory cytokines and itch-related molecules in vitro. Altogether, we conclude that CR relieves psoriatic lesions and itch via controlling immunological and neurogenic inflammation.

Immunopathogenesis and management of polymorphic light eruption

Polymorphic light eruption (PLE) is the most common immunologically mediated photodermatosis, demonstrating many abnormalities caused by critical failure of ultraviolet (UV)-induced immunosuppression. The unique expression of antimicrobial peptides in PLE, which is most likely determined by alteration of microbiome components upon UV exposure, implicates their possible triggering role and pathogenic significance in the eruption. The review aims to clarify current knowledge regarding the immunological disturbances correlated with PLE that serve a base for better understanding of molecular pathogenesis of the disease and the development of new therapeutic strategies. Preventive treatment with broad-spectrum suncreens and sunscreens containing DNA repair enzymes, as well as natural photohardening with graduate exposure to sunlight in early spring could be sufficient in milder cases. Antioxidants and topical calcipotriol are promising approach for adjuvant prevention. Phototherapy, mainly with narrow band UVB rays, is more appropriate method in severe cases of the disease. The established treatment options for PLE include local and systemic glucocorticoids, systemic nonsedative antihistamines for itch relief, and rarely, immunosuppressive drugs in the refractory cases. Like medical photohardening, afamelanotide has the potential of photoprotection by inducing a melanization of the skin. Afamelanotide is believed to be a possible new treatment option for very severe and refractory cases of PLE. Targeting the main pruritogenic cytokine, IL-31, opens a new road for the development of novel therapeutic approaches to combat moderate and severe itching in cases of PLE with intense pruritus.

The Influence of Microbiome Dysbiosis and Bacterial Biofilms on Epidermal Barrier Function in Atopic Dermatitis-An Update

Atopic dermatitis (AD) is a common inflammatory dermatosis affecting up to 30% of children and 10% of adults worldwide. AD is primarily driven by an epidermal barrier defect which triggers immune dysregulation within the skin. According to recent research such phenomena are closely related to the microbial dysbiosis of the skin. There is growing evidence that cutaneous microbiota and bacterial biofilms negatively affect skin barrier function, contributing to the onset and exacerbation of AD. This review summarizes the latest data on the mechanisms leading to microbiome dysbiosis and biofilm formation in AD, and the influence of these phenomena on skin barrier function.

Scabies itch: an update on neuroimmune interactions and novel targets

Frequently described as 'the worst itch' one can ever experience scabies itch is the hallmark of Sarcoptes scabiei mite infestation. Notably, the itchiness often persists for weeks despite scabicides therapy. The mechanism of scabies itch is not yet fully understood, and effective treatment modalities are still missing which can severely affect the quality of life. The aim of this review is to provide an overview of the scope of itch in scabies and highlight candidate mechanisms underlying this itch. We herein discuss scabies itch, with a focus on the nature, candidate underlying mechanisms and treatment options. We also synthesize this information with current understanding of the mechanisms contributing to non-histaminergic itch in other conditions. Itch is a major problem in scabies and can lead to grave consequences. We provide the latest insights on host-mite interaction, secondary microbial infection and neural sensitization with special emphasis on keratinocytes and mast cells to better understand the mechanism of itch in scabies. Also, the most relevant current modalities remaining under investigation that possess promising perspectives for scabies itch (i.e. protease-activated receptor-2 (PAR-2) inhibitor, Mas-related G protein-coupled receptor X2 (MRGPRX2) antagonist) are discussed. Greater understanding of these diverse mechanisms may provide a rational basis for the development of improved and targeted approaches to control itch in individuals with scabies.

Vulvar Pruritus: A Review of Clinical Associations, Pathophysiology and Therapeutic Management

Vulvar pruritus is an unpleasant sensation and frequent symptom associated with many dermatologic conditions, including infectious, inflammatory and neoplastic dermatoses affecting the female genitalia. It can lead to serious impairment of quality of life, impacting sexual function, relationships, sleep and self-esteem. In this review, common conditions associated with vulvar itch are discussed including atopic and contact dermatitis, lichen sclerosus, psoriasis and infectious vulvovaginitis. We review the potential physiologic, environmental and infectious factors that contribute to the development of vulvar itch and emphasize the importance of addressing their complex interplay when managing this disruptive and challenging symptom.

Influence of Skin Subjective Symptoms on Sleep Quality in Patients with Cutaneous Disorders: A Study of 2871 Subjects

Introduction

Previous studies showed more sleep disturbance (SD) in patients with cutaneous disorders (CD). During CD, unpleasant subjective symptoms [USS], such as itch, pain and others (tingling, burning, or tightness) have a negative influence on sleep quality. This study aims to evaluate the prevalence of SD in CD patients and to identify the influence of itch, pain and other unpleasant sensations on SD.

Materials and Methods

An international, anonymized real-life survey was conducted with individuals [18−75 years], with physician-confirmed CD, or without CD. The 25 items covered sociodemographic characteristics, feeling of overall sleep quality and skin unpleasant sensations. Severity of SD and unpleasant sensations were assessed using a 10-cm Visual Analogue Scale (VAS).

Results

From 3834 analyzed questionnaires, 2871 (67.3%) were in the CD group and 863 (32.7%) in the control group. Patients with CD had significantly more SD (71.2% vs 32.7% in the control group, p<0.0001). CD patients without any reported unpleasant sensation were at higher risk for SD than control subjects (OR 1,362 [95% CI 1.975–2.405] p=0.0013). SS were highly associated with SD (OR 1.641 [95% CI 1.393–1.933] p<0.0001). Pruritus, pain and intermediate sensations were significant predictors of SD, with odds ratios of 1.670, 1.625 and 1.326, respectively. VAS sleep scores were strongly associated with pruritus (r: 0.25, p<0.0001) and pain (r: 0.25 p<0.0001) severity ratings.

Discussion

SD is a common problem for patients with CD. Patients with subjective symptoms suffer more from SD, suggesting that they are aggravating factors, but are likely not the only reason for SD in CD patients. We found that during CD, intermediate sensations also contribute to SD. Despite some limitations and the potential bias due to the study design, our results confirm for the first time on an international level the influence of subjective symptoms on sleep quality in patients with CD.

Pruritus in psoriasis and atopic dermatitis: current treatments and new perspectives

Psoriasis and atopic dermatitis (AD) are two common chronic inflammatory skin diseases. Although showing different etiology and clinical manifestations, patients with either disease suffer from low health-related quality of life due to pruritus (dermal itch). Recent studies have revealed that more than 85% of psoriasis patients suffer from pruritus, and it is also the dominating symptom of AD. However, as this is a non-life treating symptom, it was partly neglected for years. In this review, we focus on current findings as well as the impact and potential treatments of pruritus in these two skin diseases. We first distinguish the type of itch based on involved mediators and modulators. This clear delineation between the types of pruritus based on involved receptors and pathways allows for precise treatment. In addition, insights into recent clinical trials aimed to alleviate pruritus by targeting these receptors are presented. We also report about novel advances in combinatorial treatments, dedicated to the type of pruritus linked to a causal disease. Altogether, we suggest that only a focused treatment tailored to the primary disease and the underlying molecular signals will provide fast and sustained relief of pruritus associated with psoriasis or AD.