New mechanism underlying IL-31-induced atopic dermatitis

Electroacupuncture exerts antipruritic and anti-inflammatory effects on atopic dermatitis by activating CB2 receptor

BACKGROUND

The therapeutic benefits of electroacupuncture (EA) for atopic dermatitis (AD) are recognized, yet the underlying mechanisms remain elusive. Given the side effects associated with clinical CB2 receptor (CB2R) agonists used in AD treatment, our study seeks to elucidate EA's role in modulating CB2R in lesional skin and its impact on antipruritic and anti-inflammatory responses using an AD mouse model.

METHODS

The AD model was induced with MC903, and EA was applied to'Qu chi'(LI11) and'He gu'(LI4) acupoints, corresponding to the neck dermatome. Mice were assessed for scratching behavior and scoring atopic dermatitis score every other day. Immunohistochemistry and immunofluorescence evaluated epidermal thickness, inflammatory cell infiltration, and CB2R expression. Meanwhile, RT-qPCR detected the expression of inflammatory factors, their receptors, and cannabinoid metabolizing enzymes. The study used both wild-type and CB2R knockout (CB2R-/-) mice to clarify CB2R's role in EA's treatment of AD.

RESULTS

EA treatment effectively mitigated chronic itching and AD-like symptoms, especially the proliferation of mast cells and CD4+ T cells. Additionally, EA treatment was found to reduce the expression of IL4, IL13, and IL31 in the skin lesions, as well as the expression of their receptors IL4R and IL31R in the dorsal root ganglia of the neck, contributing to its anti-inflammatory action. Moreover, EA augmented the expression of CB2R and regulated endocannabinoid metabolic enzymes. Furthermore, using CB2R-/- mice, it was found that the antipruritic and anti-inflammatory effects of EA were impaired. EA inhibited ERK phosphorylation in lesional skin, which was also reversed in CB2R-/- mice.

CONCLUSION

EA exerts therapeutic effects on persistent itch and skin inflammation in AD mice by activating CB2R, thereby inhibiting mast cell and CD4+ T cell proliferation and the expression of associated inflammatory factors, as well as downstream ERK phosphorylation.

Atopic Dermatitis: The Relationship Between Immune Mediators and Skin Lipid Barrier

Atopic dermatitis (AD) is a chronic inflammatory skin disease that is prevalent worldwide with complex etiology. Skin barrier defects and abnormal immune activation are crucial in the occurrence and development of AD. In the classic model of the skin barrier, lipids are essential for the formation and maintenance of this barrier as a "mortar" component. However, abnormally activated immune responses promote the lipid barrier deficiency through the secretion of various types of immune mediators directly or indirectly. In this review, we first introduce the skin lipid barrier (SLB) under both normal and abnormal conditions, highlighting the contributions of lipids derived from keratinocytes and sebaceous glands (SGs). Subsequently, the relationships between the immune mediators of Th1, Th2, Th17, Th22, and other types (adipokines, prostaglandins, leukotrienes) and SLB are elaborated in turn. Finally, the therapies for restoring SLB to treat AD are summarized, with a focus on the restoration effect of dupilumab on SLB. We hope that this review will offer a comprehensive perspective for understanding the pathogenesis of lipid metabolism disorders and SLB deficiency caused by immune mediators in AD. It also aims to provide guidance for further research on targeting inflammatory mediators to restore SLB.

Possibility and Potenzial Intervention Targets of Saffron Extract in the Treatment of Atopic Dermatitis: A Review

Atopic dermatitis (AD) is a chronic, recurrent inflammatory skin disorder characterized by dry skin, eczema-like lesions, and severe itching. The multifaceted etiology of AD, which is not yet fully understood, includes genetic predispositions, immune dysfunctions(such as an impaired skin barrier and abnormal immune regulation), imbalances in the skin microbiota, and environmental factors, among others. In the field of AD treatment, the combination of traditional Chinese medicine and modern medicine is becoming an emerging trend. Given the potenzial side effects and reduced efficacy of conventional therapeutic drugs, Chinese herbal medicines offer patients new treatment options because of their unique efficacy and low toxicity. Some saffron extracts derived from saffron and gardenia, such as crocin, crocetin, and safranal, have shown promising potenzial in the treatment of AD. These natural ingredients not only possess anti-inflammatory and immunomodulatory properties similar to those of traditional Chinese medicines but also demonstrate excellent effects in promoting the repair of damaged skin barriers. Therefore, this article reviews the therapeutic potenzial of saffron extract in the treatment of AD, with a special focus on its mechanisms and potenzial interventions, while emphasizing the importance of herbal medicines as alternatives to traditional treatments, providing AD patients with safer and more effective treatment options.

Cutaneous Adverse Events Following Nemolizumab Administration: A Review

Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by epidermal barrier dysfunction and immune dysregulation, with interleukin (IL)-4, IL-13, and IL-31 recognized as key mediators. Prurigo nodularis (PN) is another chronic inflammatory disorder driven by T helper type 2-mediated inflammation and neural dysregulation, leading to severe pruritus. Nemolizumab, a humanized monoclonal antibody targeting IL-31 receptor A, has been approved for use in the treatment of AD and PN. Clinical trials have demonstrated significant reductions in pruritus and cutaneous symptoms associated with its use. In clinical practice, acute eczema and edematous erythema frequently occur, occasionally necessitating the discontinuation of treatment. Despite these observations, no comprehensive review has examined nemolizumab-associated cutaneous adverse events. This review aimed to examine various cutaneous reactions associated with nemolizumab therapy, including psoriasiform eruptions, AD exacerbation, bullous pemphigoid, drug-induced eruptions, and fungal infections. Potential mechanisms underlying these reactions include T-cell activation due to drug sensitization, immune responses triggered by nemolizumab acting as a hapten, and a relative increase in IL-4 and IL-13 levels following IL-31 inhibition. However, the precise pathophysiological mechanism and risk factors remain unclear, and standardized clinical management guidelines are lacking. Further accumulation of clinical data and immunological research are essential for developing evidence-based strategies to manage these adverse events, ensuring treatment continuity and optimizing patient outcomes.

A topical Chinese herbal inhibits pruritus and skin inflammation via neural TRPM8 in atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a chronic, itchy, and inflammatory skin disease. The neuroimmune concept of itch involves aberrant immune responses and neural activities. Chinese herbal medicine has been demonstrated to alleviate AD symptoms, but the underlying mechanisms remain not fully understand.

PURPOSE

Chushizhiyang (CS) ointment is a topical treatment consisting of Chinese herbal ingredients. We aimed to study the underlying mechanism of CS on treating AD.

METHOD

To investigate the therapeutic efficacy of CS, we utilized a well-established atopic dermatitis mouse model, administering CS ointment topically to the ears. To unravel the underlying mechanisms, we employed a multifaceted approach, including behavioral assay, network pharmacology analysis, RNA-sequencing analysis, neural tracing, and calcium imaging. Additionally, transient receptor potential (TRP) M8-deficient mice were employed to validate the specific targets of CS.

RESULTS

By employing a murine model of AD-like disease, we found that CS ointment can reduce skin inflammation and inhibit scratching behavior. Importantly, its capacity to alleviate itch-induced scratching surpasses that of topical steroid, a positive control treatment. The RNA-sequencing analysis of the affected skin revealed that the differentially expressed genes were enriched in neuroactive pathways that include ion channels particularly TRPM8. Calcium imaging demonstrated that CS ointment is capable of activating TRPM8-positive sensory neurons. Using transgenic animals, we found that CS ointment exhibited its anti-inflammatory or anti-pruritic effects only when TRPM8 is functional intact. Additionally, CS treatment reduced neuronal activities in wild-type, rather than TRPM8-compromised animals.

CONCLUSION

Our findings suggest that topical Chinese herbals participate in neuroimmune mechanisms for AD-like disease via TRPM8.

The role of C4d expression in the diagnosis of bullous pemphigoid: a clinical and histopathological study

Inflammatory processes play a crucial role in both autoimmune and non-autoimmune skin diseases. The complement system contributes to these processes, with both well-established and yet-to-be-confirmed effects. The relationship between C4d, an intermediate product of the complement system, and skin diseases remains an area of ongoing investigation. While the presence and role of C4d in autoimmune and non-autoimmune skin diseases have been explored using immunohistochemical methods, the topic remains inconclusive. Bullous pemphigoid is an autoimmune skin disorder characterized by subepidermal blistering, predominantly affecting the elderly population. This study aims to evaluate the potential of C4d as an alternative immunohistochemical marker to the gold-standard diagnostic method, direct immunofluorescence, in diagnosing Bullous pemphigoid. Additionally, C4d staining patterns were analyzed in correlation with clinical data to assess its prognostic significance. In this retrospective study, the histomorphological, clinical, and demographic data of 43 patients diagnosed with Bullous pemphigoid were analyzed. Immunohistochemical assessment of C4d expression and staining patterns was conducted. The findings suggest that C4d may serve as a potential diagnostic and prognostic marker. C4d expression was significantly more frequent in lesions located on the upper extremities and in patients with higher eosinophil scores. Furthermore, patients with high eosinophil scores were more likely to receive systemic treatment. This study demonstrates that C4d could contribute significantly to the diagnostic process, particularly in cases where immunofluorescence studies are limited.

Therapeutic potential of a systemically applied humanized monoclonal antibody targeting Toll‑like receptor 2 in atopic‑dermatitis‑like skin lesions in a mouse model

Atopic dermatitis (AD) is a prevalent, persistent inflammatory skin disorder distinguished by pruritic and irritated skin. Toll-like receptors (TLRs) are specialized receptors that recognize specific patterns associated with pathogens and tissue damage, triggering an innate immune response that protects the host from invading pathogens. Previously, it was demonstrated that intradermal injection of the humanized anti-TLR2 monoclonal antibody (Ab) Tomaralimab effectively relieved AD-like skin inflammation in BALB/c mouse models exposed to house dust mite extracts. However, it remains unclear whether allergenic hapten-induced AD can be effectively treated with systemically administered TLR2-targeting Abs. In the present study, it was observed that administrating Tomaralimab through intravenous injection alleviated AD-like skin lesions in BALB/c mice challenged with topical application of 2,4-dinitrochlorobenzene by reducing the infiltration of inflammatory cells into skin lesions and preventing the creation of various inflammatory cytokines, including thymic stromal lymphopoietin, interleukin (IL)-4, IL-13, IL-17 and IL-31, which are associated with the pathogenesis of AD. These findings support the feasibility of using a humanized anti-TLR2 monoclonal Ab as systemic therapy for AD.

Molecular and cellular mechanisms of itch sensation and the anti-itch drug targets

Itch is an uncomfortable feeling that evokes a desire to scratch. This protective reflex can effectively eliminate parasites that invade the skin. When itchy skin becomes severe or lasts for more than six weeks, it has deleterious effects on both quality of life and productivity. Despite decades of research, the complete molecular and cellular coding of chronic itch remains elusive. This persistent condition often defies treatment, including with antihistamines, and poses a significant societal challenge. Obtaining pathophysiological insights into the generation of chronic itch is essential for understanding its mechanisms and the development of innovative anti-itch medications. In this review we provide a systematic overview of the recent advancement in itch research, alongside the progress made in drug discovery within this field. We have examined the diversity and complexity of the classification and mechanisms underlying the complex sensation of itch. We have also delved into recent advancements in the field of itch mechanism research and how these findings hold potential for the development of new itch treatment medications. But the treatment of clinical itch symptoms still faces significant challenges. Future research needs to continue to delve deeper, not only to discover more itch-related pathways but also to explore how to improve treatment efficacy through multitarget or combination therapy.

In vitro and in vivo efficacy of the Active Oligo Skin complex™, a new active ingredient processed from seawater, on multiple parameters of atopic skin

Background

Different symptoms are associated with atopic skin, including dryness, pruritus and pain, and affect patients' quality of life. The environment, microbiota, epidermis, immune and nerve cells are all implicated in the pathogenesis of atopic skin. Staphylococcus aureus is the focus of particular attention. Epidermis is implicated at multiple levels: inflammatory process, barrier, control of moisture and water loss. Sensory neurons that participate in cutaneous neurogenic inflammation and pruritus are seen as a potential new target. Specific management strategies and new treatments for adults and children are needed to help in more refractory cases. As a baseline of management, guidelines recommend a treatment to moisturize the skin and maintain the skin barrier function, such as an emollient.

Objectives

To evaluate a new product in vitro and in vivo in order to validate the potential of its use in people with atopic skin or dry skin.

Methods

A specific mineral composition, Active Oligo Skin complex™, from seawater was developed and included in a balm. The effects of a solution and balm containing the complex were evaluated in vitro on the growth and biofilm formation of Staphylococcus aureus and Staphylococcus epidermidis in different skin models, and in vivo in adult and young volunteers.

Results

In vitro, the complex modulated bacterial biofilm formation and growth, decreased cytokine [interleukin (IL)-1, IL-6, IL-4] and neuropeptide (substance P) release, and increased the expression of CL1 and CL4. On volunteers with dry skin, the complex had a moisturizing effect after 1 h of application. Dryness and roughness were also reduced in young participants with atopic skin. The balm decreased erythema and pruritus after 21 days of topical application on 60 young participants. On 22 adult participants, stinging score was decreased after -application.

Conclusions

The Active Oligo Skin complex™ appears to display potent antipruritic and anti-inflammatory activities, both in vitro and in vivo.

Pathogenesis and management of TRPV3-related Olmsted syndrome

Olmsted syndrome is characterized by symmetrically distributed, destructive, inflammatory palmoplantar keratoderma with periorificial keratotic plaques, most commonly due to gain-of-function mutations in the transient receptor potential vanilloid 3 (TRPV3) gene, which involves multiple pathological functions of the skin, such as hyperkeratosis, dermatitis, hair loss, itching, and pain. Recent studies suggest that mutations of TRPV3 located in different structural domains lead to cases of varying severity, suggesting a potential genotype-phenotype correlation resulting from TRPV3 gene mutations. This paper reviews the genetics and pathogenesis of Olmsted syndrome, as well as the potential management and treatment. This review will lay a foundation for further developing the individualized treatment for TRPV3-related Olmsted syndrome.

Neuroinflammation evoked mechanisms for neuropathic itch in the spared nerve injury mouse model of neuropathic pain

A large portion of neuropathic pain suffering patients may also concurrently experience neuropathic itch, with a negative impact on the quality of life. The limited understanding of neuropathic itch and the low efficacy of current anti-itch therapies dictate the urgent need of a better comprehension of molecular mechanisms involved and development of relevant animal models. This study was aimed to characterize the itching phenotype in a model of trauma-induced peripheral neuropathy, the spared nerve injury (SNI), and the molecular events underlying the overlap with the nociceptive behavior. SNI mice developed hyperknesis and spontaneous itch 7-14 days after surgery that was prevented by gabapentin treatment. Itch was associated with pain hypersensitivity, loss of intraepidermal nerve fiber (IENF) density and increased epidermal thickness. In coincidence with the peak of scratching behavior, SNI mice showed a spinal overexpression of IBA1 and GFAP, microglia and astrocyte markers respectively. An increase of the itch neuropeptide B-type natriuretic peptide (BNP) in NeuN+ cells, of its downstream effector interleukin 17 (IL17) along with increased pERK1/2 levels occurred in the spinal cord dorsal horn and DRG. A raise in BNP and IL17 was also detected at skin level. Stimulation of HaCat cells with conditioned medium from BV2-stimulated SH-SY5Y cells produced a dramatic reduction of HaCat cell viability. This study showed that SNI mice might represent a model for neuropathic itch and pain. Collectively, our finding suggest that neuropathic itch might initiate at spinal level, then affecting skin epidermis events, through a glia-mediated neuroinflammation-evoked BNP/IL17 mechanism.

Study on the molecular mechanism of atopic dermatitis in mice based on skin and serum metabolomic analysis

INTRODUCTION

Atopic dermatitis (AD) is a common chronic inflammatory dermatosis. However, the exact molecular mechanism underlying the development of AD remain largely unclear.

OBJECTIVE

To investigate comprehensive metabolomic alterations in serum and skin tissue between 2,4-dinitrofluorobenzene (DNFB)-induced AD-like mice and healthy controls, aiming to identify the potential disease biomarkers and explore the molecular mechanisms of AD.

METHODS

In this study, Untargeted metabolomics analysis was used to investigate both skin and serum metabolic abnormalities of 2,4-dinitrofluorobenzene (DNFB)-induced AD-like mice. Then, the metabolic differences among the groups were determined through the application of multivariate analysis. Additionally, the selection of predictive biomarkers was accomplished using the receiver operating characteristic (ROC) module.

RESULTS

Our findings showed that levels of 220 metabolites in the skin and 94 metabolites in the serum were different in AD-like mice that were treated with DNFB compared to control mice. Uracil, N-Acetyl-L-methionine, deoxyadenosine monophoosphate, 2-acetyl-l-alkyl-sn-glycero-3-phosphcholine, and prostaglandin D2 are considered potential biomarkers of AD as obtained by integrating skin and serum differential metabolite results. Metabolomic data analysis showed that the metabolic pathways in which skin and serum are involved together include histidine metabolism, pyrimidine metabolism, alanine, aspartate, and glutamate metabolism.

CONCLUSION

Our research explained the possible molecular mechanism of AD at the metabolite level and provided potential targets for the development of clinical drugs for AD.

Preclinical Models of Atopic Dermatitis Suitable for Mechanistic and Therapeutic Investigations

Atopic dermatitis (AD) is a complex immune-mediated abnormality of the skin characterized by impaired barrier function, eczematous dermatitis, chronic pruritus and itch. The immunological response in AD is mediated by a Th2-dominated immune response in the early acute phase followed by a Th1/ Th2 mixed immune response in the chronic phase. AD is the first step of the "atopic march" that progresses into food allergy, allergic rhinitis, and asthma. Different models are indispensable for studying AD pathogenesis and for designing pre-clinical studies for therapeutic discovery. They reflect the characteristic morphological features of typical human AD with regard to epidermal thickening, hyperkeratosis, acanthosis, and spongiosis and help understand the immunopathogenesis of the disease with respect to IgE levels and cellular infiltration of eosinophils, mast cells, and lymphocytes. Although it is difficult to replicate all human AD clinical features in a model, several AD in vivo models comprising spontaneous, induced, transgenic, and humanized and in vitro models, including 2D, co-culture, and 3D, have been described previously. However, several questions remain regarding whether these models satisfactorily reflect the complexity of human AD. Therefore, this review comprehensively highlights the diversity of currently available models and provides insights into the selection of suitable models based on research questions. It also summarizes the diverse mechanisms associated with each model, which may be valuable for better study design to test new therapeutic options.

Increased Systemic Levels of Centrally Acting B-Type Natriuretic Peptide Are Associated with Chronic Itch of Different Types

B-type natriuretic peptide (BNP) is an itch-selective neuropeptide that was shown to play a role in both histaminergic and nonhistaminergic itch in mice. It was also shown that elevated serum BNP is linked to increased pruritus in nondiabetic hemodialysis patients. This study examined plasma BNP levels of 77 patients and N-terminal pro-BNP levels of 33 patients with differing types of chronic itch to see whether BNP and N-terminal pro-BNP levels can correlate with itch severity. Plasma BNP and N-terminal pro-BNP levels of all patients with itch correlated with itch numerical rating scale and in particular for patients with chronic pruritus of unknown origin. On the basis of this clinical observation, this study further showed that increasing pathophysiological levels of BNP in mice by intravenous or osmotic pump induced significant scratching. In addition, pharmacological and ablation strategies determined that BNP acts centrally by activating the natriuretic peptide receptor A in the dorsal horn of the spinal cord. These data support that BNP and N-terminal pro-BNP levels are associated with chronic itch and may be used in clinical setting.

Protease-Activated Receptor 2 in inflammatory skin disease: current evidence and future perspectives

Protease-activated receptor-2 (PAR2) is a class-A G protein-coupled receptor (GPCR) activated by serine proteases and is expressed by multiple tissues, including the skin. PAR2 is involved in the skin inflammatory response, promoting Th2 inflammation, delaying skin barrier repair, and affecting the differentiation of keratinocytes. It also participates in the transmission of itch and pain sensations in the skin. Increasing evidence indicates that PAR2 plays an important role in the pathogenesis of inflammatory skin diseases such as acne vulgaris, rosacea, psoriasis, and atopic dermatitis. Additional focus will be placed on potential targeted therapies based on PAR2. The Goal of this review is to outline the emerging effects of PAR2 activation in inflammatory skin disease and highlight the promise of PAR2 modulators.

Therapeutic Potential and Mechanisms of Mesenchymal Stem Cell and Mesenchymal Stem Cell-Derived Extracellular Vesicles in Atopic Dermatitis

Atopic dermatitis (AD) is a chronic and inflammatory skin disease with intense itchiness that is highly prevalent worldwide.The pathogenesis of AD is complex and closely related to genetic factors, immunopathogenic factors, environmental factors, and skin infections. Mesenchymal stem cells (MSCs) are non-hematopoietic progenitor cells derived from the mesenchymal stroma. They have anti-inflammatory, anti-apoptotic, and regenerative properties. Numerous studies demonstrate that MSCs can play a therapeutic role in AD by regulating various immune cells, maintaining immune homeostasis, and promoting the repair of damaged tissues. The key mediators for their biological functions are extracellular vesicles (MSC-Evs) and soluble cytokines derived from MSCs. The safety and efficacy of MSCs have been demonstrated in clinical Phase I / IIa trials for AD. This paper provides a comprehensive review of the pathogenesis of AD and the currently published studies on the function of MSCs and MSC-Evs in AD, primarily including the pathogenesis and the immunomodulatory impacts of MSCs and MSC-Evs, along with advancements in clinical studies. It provides insights for comprehending AD pathogenesis and investigating treatments based on MSCs.

Neuronal BST2: A Pruritic Mediator alongside Protease-Activated Receptor 2 in the IL-27-Driven Itch Pathway

Chronic itch is a common and complex symptom often associated with skin diseases such as atopic dermatitis (AD). Although IL-27 is linked to AD, its role and clinical significance in itch remain undefined. We sought to investigate IL-27 function in itch using tissue-specific transgenic mice, various itch models, behavior scoring, RNA sequencing, and cytokine/kinase array. Our findings show that IL-27 receptors were overexpressed in human AD skin. Intradermal IL-27 injection failed to directly induce itch in mice but upregulated skin protease-activated receptor 2 (PAR2) transcripts, a key factor in itch and AD. IL-27 activated human keratinocytes, increasing PAR2 transcription and activity. Coinjection of SLIGRL (PAR2 agonist) and IL-27 in mice heightened PAR2-mediated itch. In addition, IL-27 boosted BST2 transcription in sensory neurons and keratinocytes. BST2 was upregulated in AD skin, and its injection in mice induced itch-like response. BST2 colocalized with sensory nerve branches in AD skin from both human and murine models. Sensory neurons released BST2, and mice with sensory neuron-specific BST2 knockout displayed reduced itch responses. Overall, this study provides evidence that skin IL-27/PAR2 and neuronal IL-27/BST2 axes are implicated in cutaneous inflammation and pruritus. The discovery of neuronal BST2 in pruritus shed light on BST2 in the itch cascade.

The involvement of keratinocytes in pruritus of chronic inflammatory dermatosis

Frequent itching and incessant scratching are commonly observed in various chronic inflammatory skin conditions, including atopic dermatitis and psoriasis. The persistent and prolonged nature of pruritus can worsen one's quality of life. Keratinocytes (KCs), the predominant cells of the epidermis, have been confirmed to interact with sensory neurons and immune cells and be involved in chronic skin inflammatory diseases associated with pruritus. Initially, KCs and sensory neurons form a unique synapse-like connection within the epidermis, serving as the structural foundation for their interaction. Additionally, several receptors, including toll-like receptors and protease-activated receptor 2, expressed on KCs, become activated in an inflammatory milieu. On the one hand, activated KCs are sources of pro-inflammatory cytokines and neurotrophic factors, such as adenosine triphosphate, thymic stromal lymphopoietin, and nerve growth factor, which directly or indirectly participate in stimulating sensory neurons, thereby contributing to the itch sensations. On the other hand, KCs also function as primary transducers alongside intraepidermal nerve endings, directly initiating pruritic responses. This review summarizes the current literature and highlights the critical role of KCs in the development and persistence of chronic itch in inflammatory skin disorders.

Symptom severity reflected by NYHA grade is independently associated with pruritus in chronic heart failure patients

BACKGROUND

Pruritus is a symptom profoundly impairing patients' quality of life (QoL). It is a common symptom in chronic heart failure (CHF) patients of yet unknown nature. The aim of this study was to evaluate the risk factors of pruritus in CHF patients.

METHODS

For this monocentric, prospective cohort study, CHF patients were recruited and CHF symptoms, comorbidities and drug intake were assessed using a structured report. Additionally, a questionnaire evaluated pruritus symptoms. Detailed medical histories including laboratory test results were retrieved from patient files for all participants.

RESULTS

We evaluated data from 550 CHF patients. Of those, 25.3% reported pruritus to occur frequently (3-5 times per week), often (1-2 times per week) or daily. Patients of higher NYHA classes (NYHA III + IV) experienced significantly more pruritus (31.2%) than lower NYHA classes (NYHA I + II) (21.1%, p = 0.024). Patients with pruritus reported disproportionately often concomitant stasis dermatitis (p = 0.026) and chronic lung disease (p = 0.014). Other parameters reflecting cardiac, liver, kidney and thyroid function, as well as medical therapies showed no significant differences between patients with and without pruritus. In the multivariate logistic regression analysis, only NYHA class (p = 0.016, OR 1.55, 95% confidence interval (CI): [1.09; 2.20]) and elevated leukocyte count (p = 0.007, OR 1.11, CI [1.03; 1.21]) remained significantly associated with pruritus in CHF patients.

CONCLUSIONS

NYHA class is an independent predictor for pruritus in CHF patients. Besides NYHA class, leukocyte count was also associated with increased pruritus. Pruritus may impair QoL in CHF patients and should thus be included in the assessment of those patients. We suggest that providing best care for CHF patients can be achieved through an interdisciplinary approach of cardiologists and dermatologists and should include a pruritus assessment.

Unveiling the phyto-restorative potential of ethereal distillates for atopic dermatitis: an advanced therapeutic approach

Atopic dermatitis is acknowledged as a vital inflammatory disorder associated with the integumentary system of the body and is characterized by the formation of thick reddish-grey scars and erythema formation on skin, prevalent amidst the populace. Numerous synthetic drugs are available for treatment like antihistamines, immunosuppressants, glucocorticoids etc., but contrarily, essential oil therapy is exclusively lime lighted to favour the purpose. The utilization of available engineered drugs, possess the marked adverse effects owing to prolonged duration of therapy and therefore, essential oils are explored well and proved to exhibit the anti-eczematic, anti-inflammatory and antipruritic properties. Ethereal distillates own the assorted and selective therapeutic properties attributable to presence of bioactive compounds liable to treat this torturous and integumentary disorder, likely lavender oil, patchouli oil, frankincense oil etc., have been found to exert their pharmacological actions by impeding the liberation and action of inflammatory mediators and immunological hyperactivities that are engaged in exacerbating this idiopathic illness. The current attempt provided the update with the aim to bring forth the naturally originated treatment that is pertinent to provide the invulnerable therapy by circumventing the noxious symptoms i.e. erythema formation and inflamed lesions.

Biomarkers for phenotype-endotype relationship in atopic dermatitis: a critical review

Atopic dermatitis (AD) is the most common form of chronic skin inflammation with diverse clinical variants. Historically, various AD phenotypes have been grouped together without considering their heterogeneity. This approach has resulted in a lack of phenotype- and endotype-adapted therapeutic strategies. Comprehensive insights into AD pathogenesis have enabled precise medicinal approach for AD. These efforts aimed to redefine the endophenotype of AD and develop various biomarkers for diverse purposes. Among these endeavours, efforts are underway to elucidate the mechanisms (and related biomarkers) that lead to the emergence and progression of atopic diseases originating from AD (e.g., atopic march). This review focuses on diverse AD phenotypes and calls for a definition of endophenotypes. While awaiting scientific validation, these biomarkers ensure predicting disease onset and trajectory and tailoring therapeutic strategies for the future.

Atopic Dermatitis Itch: Scratching for an Explanation

Chronic pruritus is a cardinal symptom of atopic dermatitis (AD). The mechanisms underlying atopic itch involve intricate crosstalk among skin, immune components, and neural components. In this review, we explore these mechanisms, focusing on key players and interactions that induce and exacerbate itch. We discuss the similarities and differences between pruritus and pain in patients with AD as well as the relationship between pruritus and factors such as sweat and the skin microbiome. Furthermore, we explore novel targets that could provide significant itch relief in these patients as well as exciting future research directions to better understand atopic pruritus in darker skin types.

Molecular and cellular pruritus mechanisms in the host skin

Pruritus, also known as itching, is a complex sensation that involves the activation of specific physiological and cellular receptors. The skin is innervated with sensory nerves as well as some receptors for various sensations, and its immune system has prominent neurological connections. Sensory neurons have a considerable impact on the sensation of itching. However, immune cells also play a role in this process, as they release pruritogens. Disruption of the dermal barrier activates an immune response, initiating a series of chemical, physical, and cellular reactions. These reactions involve various cell types, including keratinocytes, as well as immune cells involved in innate and adaptive immunity. Collective activation of these immune responses confers protection against potential pathogens. Thus, understanding the molecular and cellular mechanisms that contribute to pruritus in host skin is crucial for the advancement of effective treatment approaches. This review provides a comprehensive analysis of the present knowledge concerning the molecular and cellular mechanisms underlying itching signaling in the skin. Additionally, this review explored the integration of these mechanisms with the broader context of itch mediators and the expression of their receptors in the skin.

Mast cell-sensory neuron crosstalk in allergic diseases

Mast cells (MCs) are tissue-resident immune cells, well-positioned at the host-environment interface for detecting external antigens and playing a critical role in mobilizing innate and adaptive immune responses. Sensory neurons are afferent neurons innervating most areas of the body but especially in the periphery, where they sense external and internal signals and relay information to the brain. The significance of MC-sensory neuron communication is now increasingly becoming recognized, especially because both cell types are in close physical proximity at the host-environment interface and around major organs of the body and produce specific mediators that can activate each other. In this review, we explore the roles of MC-sensory neuron crosstalk in allergic diseases, shedding light on how activated MCs trigger sensory neurons to initiate signaling in pruritus, shock, and potentially abdominal pain in allergy, and how activated sensory neurons regulate MCs in homeostasis and atopic dermatitis associated with contact hypersensitivity and type 2 inflammation. Throughout the review, we also discuss how these 2 sentinel cell types signal each other, potentially resulting in a positive feedback loop that can sustain inflammation. Unraveling the mysteries of MC-sensory neuron crosstalk is likely to unveil their critical roles in various disease conditions and enable the development of new therapeutic approaches to combat these maladies.

Sevoflurane Alters Serum Metabolites in Elders and Aging Mice and Increases Inflammation in Hippocampus

Purpose

Postoperative cognitive dysfunction (POCD) is a central nervous system complication that occurs after anesthesia, particularly among the elderly. However, the neurological pathogenesis of postoperative cognitive dysfunction remains unclear. The aim of this study was to evaluate the effects of sevoflurane exposure on serum metabolites and hippocampal gene expression in elderly patients and aging mice by metabolomics and transcriptomic analysis and to explore the pathogenesis of sevoflurane induced POCD.

Patients and Methods

Human serum samples from five patients over 60 years old were collected before sevoflurane anesthesia and 1 hour after anesthesia. Besides, mice aged at 12 months (n=6 per group) were anesthetized with sevoflurane for 2 hours or with sham procedure. Subsequently, serum and hippocampal tissues were harvested for analysis. Further investigation into the relationship between isatin and neuroinflammation was conducted using BV2 microglial cells.

Results

Sevoflurane anesthesia led to the activation of inflammatory pathways, an increased presence of hippocampal astrocytes and microglia, and elevated expression of neuroinflammatory cytokines. Comparative analysis identified 12 differential metabolites that exhibited changes in both human and mouse serum post-sevoflurane anesthesia. Notably, isatin levels were significantly decreased after anesthesia. Notably, isatin levels significantly decreased after anesthesia, a factor known to stimulate proliferation and proinflammatory gene expression in microglia-the pivotal cell type in inflammatory responses.

Conclusion

Sevoflurane-induced alterations in serum metabolites in both elderly patients and aging mice, subsequently contributing to increased inflammation in the hippocampus.

Serum IL-31 is related to the severity and 3-month prognosis of patients with Intracerebral hemorrhage

Interleukin (IL)-31/IL-33 axis has been proved to play an important role in the regulation of inflammation, and serum IL-33 was found to be a novel serum prognostic marker of intracerebral hemorrhage (ICH), while the value of serum IL-31 levels on prognosis in patients with ICH remains unknown. The present study was designed to study the value of serum IL-31 levels on prognosis in ICH patients. A total of 200 ICH patients and 50 healthy people were included in this study. We collected clinical data such as demographic data, laboratory data, admission disease scores and medical histories of these participants. We measured serum IL-31 levels using enzyme-linked immunosorbent assay, and assessed the prognosis of ICH patients 3 months after onset by mRS scale, and mRS > 2 was defined as a 3-month poor outcome. The level of IL-31 in ICH patients were significantly higher than that in healthy control people (211.91 ± 61.61 vs 167.64 ± 27.45 pg/mL, P < .001), and levels of IL-31 in ICH patients with 3-month good outcome were significantly lower than that in ICH patients with 3-month poor outcome (196.09 ± 50.84 vs 248.05 ± 41.41 pg/mL, P < .001). Results of correlation analysis suggested that the level of serum IL-31 was positively related to admission NIHSS score (r = 0.627, P < .001), hematoma volume (r = 0.352, P < .001), mRS score (r = 0.515, P < .001), high-density lipoprotein-cholesterol (r = 0.177, P = .012), serum C-reactive protein levels (r = 0.483, P < .001), and serum tumor necrosis factor α levels (r = 0.389, P < .001) in ICH patients, while the level of serum IL-31 was negatively related to the admission GCS score (r = -0.518, P < .001) and triglycerides (r = -0.147, P = .038). Results of multivariate regression analysis shows that serum IL-31 levels are an independent risk factor affecting NIHSS scores (OR = 1.023, 95% CI = 1.010-2.036) and 3-month prognosis (OR = 1.023, 95% CI = 0.982-1.747) in ICH patients. The receiver operating characteristic curve analysis showed that the sensitivity and specificity of serum IL-31 level in evaluating the prognosis of ICH were 85.2% and 76.7%, respectively. A cutoff value of serum IL-31 level > 185.30 pg/mL may indicate a poor prognosis for ICH. Serum IL-31 levels on admission in ICH patients are associated with patient prognosis, and higher serum IL-31 levels are associated with a higher risk of poor prognosis in ICH patients.

Adipokines in atopic dermatitis: the link between obesity and atopic dermatitis

Atopic dermatitis (AD) is a chronic skin condition with intense pruritus, eczema, and dry skin. The recurrent intense pruritus and numerous complications in patients with AD can profoundly affect their quality of life. Obesity is one of its comorbidities that has been confirmed to be the hazard factor of AD and also worsen its severity. Nevertheless, the specific mechanisms that explain the connection between obesity and AD remain incompletely recognized. Recent studies have built hopes on various adipokines to explain this connection. Adipokines, which are disturbed by an obese state, may lead to immune system imbalances in people with AD and promote the development of the disease. This review focuses on the abnormal expression patterns of adipokines in patients with AD and their potential regulatory molecular mechanisms associated with AD. The connection between AD and obesity is elucidated through the involvement of adipokines. This conduces to the in-depth exploration of AD pathogenesis and provides a new perspective to develop therapeutic targets.

Full-body blue light irradiation as treatment for atopic dermatitis: a randomized sham-controlled clinical trial (AD-Blue)

BACKGROUND

Visible blue light (wavelength 400-495 nm) is a promising new treatment option for both psoriasis and atopic dermatitis (AD). Whilst previous clinical trials featured various devices and blue light at a variety of wavelengths, none of these interventions were challenged in objective clinical criteria.

PATIENTS AND METHODS

Eighty-seven patients diagnosed with AD were enrolled in AD-Blue, an international, prospective, double-blinded, three-armed (415 nm vs. 450 nm vs. sham control), randomized trial designed to investigate the safety and efficacy of prototype full-body blue light devices.

RESULTS

Full-body irradiation with 450 nm blue light but not 415 nm had a significant impact on itch (Itch-VAS, -1.6 ± 2.3; p  =  0.023 vs. sham irradiation). PO-SCORAD values also decreased significantly in response to irradiation at 415 nm (-11.5 ± 18.4; p = 0.028 vs. sham irradiation). None of the other outcome measures (EASI, SCORAD, IGA, DLQI) changed significantly. No safety signals were observed. Evaluation of skin transcriptomes, cytokine levels in serum, and ELISpots from peripheral blood mononuclear cells isolated from a subset of patients revealed moderate decreases in IL-31 in response to irradiation with blue light.

CONCLUSIONS

Despite its favorable safety profile and moderate reductions in itch and IL-31 levels, full-body blue light irradiation did not lead to an amelioration of any of the objective measures of AD.

Ganzkörper-Blaulichtbestrahlung zur Behandlung der atopischen Dermatitis: eine randomisierte, placebokontrollierte klinische Studie (AD-Blue)

Hintergrund

Sichtbares blaues Licht (Wellenlänge 400–495 nm) ist eine vielversprechende neue Behandlungsoption sowohl für Psoriasis als auch für atopische Dermatitis (AD). In früheren klinischen Studien wurden zwar verschiedene Geräte und blaues Licht mit unterschiedlichen Wellenlängen eingesetzt, aber keine dieser Prozeduren wurde anhand objektiver klinischer Kriterien geprüft.

Patienten und Methodik

87 Patienten mit AD wurden in die AD‐Blue‐Studie aufgenommen, eine internationale, prospektive, doppelblinde, dreiarmige (415 nm vs. 450 nm vs. Placebo), randomisierte Studie zur Untersuchung der Sicherheit und Wirksamkeit von Prototypen von Ganzkörper‐Blaulicht‐Bestrahlungsgeräten.

Ergebnisse

Die Ganzkörper‐Bestrahlung mit 450 nm blauem Licht, aber nicht mit 415 nm, hatte einen signifikant positiven Einfluss auf den Juckreiz (Pruritus‐VAS, –1,6 ± 2,3; p = 0,023 gegenüber der Placebobestrahlung). Die PO‐SCORAD‐Werte sanken ebenfalls signifikant als Reaktion auf die Bestrahlung bei 415 nm (–11,5 ± 18,4; p = 0,028 im Vergleich zur Placebobestrahlung). Keines der anderen Ergebnisse (EASI, SCORAD, IGA, DLQI) veränderte sich signifikant. Es wurden keine Sicherheitsprobleme beobachtet. Die Auswertung von Hauttranskriptomdaten, Zytokinspiegeln im Serum und ELISpots aus mononukleären Zellen des peripheren Blutes, die von einer Untergruppe von Patienten isoliert wurden, ergab eine moderate Abnahme von IL‐31 als Reaktion auf die Bestrahlung mit blauem Licht.

Schlussfolgerungen

Trotz des günstigen Sicherheitsprofils und der mäßigen Verringerung von Pruritus und IL‐31‐Spiegel führte die Ganzkörper‐Blaulichtbestrahlung bei AD zu keiner Verbesserung der objektiven Parameter zu Krankheitsschwere.

Molecular mechanisms of pruritus in prurigo nodularis

Pruritus is the most common symptom of dermatological disorders, and prurigo nodularis (PN) is notorious for intractable and severe itching. Conventional treatments often yield disappointing outcomes, significantly affecting patients' quality of life and psychological well-being. The pathogenesis of PN is associated with a self-sustained "itch-scratch" vicious cycle. Recent investigations of PN-related itch have partially revealed the intricate interactions within the cutaneous neuroimmune network; however, the underlying mechanism remains undetermined. Itch mediators play a key role in pruritus amplification in PN and understanding their action mechanism will undoubtedly lead to the development of novel targeted antipruritic agents. In this review, we describe a series of pruritogens and receptors involved in mediating itching in PN, including cytokines, neuropeptides, extracellular matrix proteins, vasculogenic substances, ion channels, and intracellular signaling pathways. Moreover, we provide a prospective outlook on potential therapies based on existing findings.

The Effects of Lumbricus rubellus Extract on Staphylococcus aureus Colonization and IL-31 Levels in Children with Atopic Dermatitis

Background and Objectives: The ineffective combination of corticosteroids and antibiotics in treating some atopic dermatitis (AD) cases has been concerning. The skin barrier defects in AD ease the colonization of Staphylococcus aureus (S. aureus), which results in a rise in interleukin-31 (IL-31). Lumbricus rubellus (L. rubellus) has shown antimicrobial and antiallergic effects but has not been studied yet to decrease the growth of S. aureus and IL-31 levels in AD patients. This study aimed to analyze the effect of L. rubellus extract in reducing S. aureus colonization, the IL-31 level, and the severity of AD. Materials and Methods: A randomized controlled trial (RCT) (international registration number TCTR20231025004) was conducted on 40 AD patients attending Dermatology and Venereology Polyclinic, Mother and Child Hospital (RSIA), Aceh, Indonesia, from October 2021 to March 2022. AD patients aged 8-16 who had a Scoring Atopic Dermatitis (SCORAD) index > 25, with total IgE serum level > 100 IU/mL, and had healthy weight were randomly assigned into two groups: one received fluocinolone acetonide 0.025% and placebo (control group) and one received fluocinolone acetonide 0.025% combined with L. rubellus extract (Vermint®) (intervention group). The S. aureus colony was identified using a catalase test, coagulase test, and MSA media. The serum IL-31 levels were measured using ELISA assay, while the SCORAD index was used to assess the severity of and improvement in AD. Mean scores for measured variables were compared between the two groups using an unpaired t-test and Mann-Whitney U test. Results: A significant decline in S. aureus colonization (p = 0.001) and IL-31 (p = 0.013) in patients receiving L. rubellus extract was found in this study. Moreover, fourteen AD patients in the intervention group showed an improvement in the SCORAD index of more than 35% (p = 0.057). Conclusions: L. rubellus extract significantly decreases S. aureus colonization and the IL-31 level in AD patients, suggesting its potential as an adjuvant therapy for children with AD.

Association of Periodontitis and Atopic Dermatitis with the Levels of IL-13, IL-31, and TSLP in the Gingival Crevicular Fluid

Emerging epidemiological evidence links atopic dermatitis (AD) and periodontitis, although the mechanisms remain unclear. Th2-derived cytokines are key in the development of both diseases, and different gingival crevicular fluid (GCF) profiles among healthy and diseased subjects have been previously reported. This case-control study examined the GCF levels of interleukins (IL)-13, IL-31, and thymic stromal lymphopoietin (TSLP) in 29 subjects with moderate-to-severe AD and 33 controls. All subjects underwent comprehensive clinical and oral evaluations, followed by GCF collection. GCF levels of IL-13, IL-31, and TSLP were assessed using a multiplex-bead immunoassay. Demographic and periodontal parameters were similar among groups (p > 0.05). The GCF levels of IL-31 and TSLP were higher in AD subjects compared to controls (p < 0.05), whereas no significant differences in the GCF levels of IL-13 were noticed (p = 0.377). Moderate-to-severe AD was positively associated with the GCF levels of IL-31 and TSLP, whereas severe periodontitis was negatively associated with IL-31 (p < 0.05). The GCF levels of IL-13 showed no significant associations with either condition (p = 0.689). There was no significant interaction between AD and periodontitis for IL-31 (p < 0.869). These results suggest that AD and periodontitis independently influence the GCF levels of IL-31 in opposing ways, whereas AD alone influences the levels of TSLP.

Therapeutic potential of infliximab for pruritus in mice model of cholestasis induced by bile duct ligation: Possible involvement of IL-31

BACKGROUND

Cholestatic pruritus is a distressful sensation that can cause a massive desire of scratching skin. Despite maximum medication therapy, some patients still experience pruritus. In this study, we evaluated the effect of infliximab on cholestatic pruritus induced in mice by bile duct ligation.

METHODS

Twenty-four balb/c mice were randomly assigned to three groups; sham, control, and treatment. The bile duct ligation procedure was performed on mice in the control and treatment groups. After six days, mice in the treatment group received subcutaneous administration of infliximab, and the next day all mice were subjected to the scratching behavior test. Skin, dorsal root ganglia (DRG), and blood samples of mice were collected and evaluated by histopathological, molecular, and biochemical tests.

RESULTS

The scratching behavior has significantly decreased in mice with cholestasis after the administration of infliximab. The levels of TNFα, TNFR1, TNFR2, NF-κB, and IL-31were higher in control mice compared to sham. In addition, expression levels of TNFR1, NF-κB, and IL-31 were decreased in the treatment group compared to the controls in skin and DRG, while TNFR2 levels were decreased only in DRG.

CONCLUSION

Infliximab can block TNFα interaction with receptors and inhibit further inflammatory response. Also, our results suggested that infliximab can suppress IL-31 expression indirectly, which is a well-known cytokine in pruritus pathophysiology Infliximab can be a potential therapeutic approach in resistant pruritus in cholestatic disorders.

Inflammatory loops in the epithelial-immune microenvironment of the skin and skin appendages in chronic inflammatory diseases

The epithelial-immune microenvironment (EIME) of epithelial tissues has five common elements: (1) microbial flora, (2) barrier, (3) epithelial cells, (4) immune cells, and (5) peripheral nerve endings. EIME provides both constant defense and situation-specific protective responses through three-layered mechanisms comprising barriers, innate immunity, and acquired immunity. The skin is one of the largest organs in the host defense system. The interactions between the five EIME elements of the skin protect against external dangers from the environment. This dysregulation can result in the generation of inflammatory loops in chronic inflammatory skin diseases. Here, we propose an understanding of EIME in chronic skin diseases, such as atopic dermatitis, psoriasis, systemic lupus erythematosus, alopecia areata, and acne vulgaris. We discuss the current treatment strategies targeting their inflammatory loops and propose possible therapeutic targets in the future.

Clinical trials of antibody drugs in the treatments of atopic dermatitis

Atopic dermatitis (AD) is one of the most common, relapsing, chronic inflammatory skin disease, being regarded as a global health issue. Recent studies have shown that Th2 cell-mediated type 2 immunity plays a central role in AD. The type 2 inflammatory cytokines such as IL-4, IL-13, IL-22, IL-31, IL-17 and IL-5 mediate the pathogenesis of AD. A variety of antibody drugs targeting these cytokines have been developed to treat AD in clinics. Notably, several antibody drugs have exhibited high efficacy in treating atopic dermatitis in previous studies, demonstrating that they could be therapeutic methods for AD patients. Herein, we reviewed the clinical trials of antibody drugs in the treatment of AD, which provides a useful guideline for clinicians to treat patients with AD in clinics.

Basic mechanisms of itch

Pruritus (or itch) is an unpleasant sensation leading to a desire to scratch. In the epidermis, there are selective C or Aδ epidermal nerve endings that are pruriceptors. At their other ends, peripheral neurons form synapses with spinal neurons and interneurons. Many areas in the central nervous system are involved in itch processing. Although itch does not occur solely because of parasitic, allergic, or immunologic diseases, it is usually the consequence of neuroimmune interactions. Histamine is involved in a minority of itchy conditions, and many other mediators play a role: cytokines (eg, IL-4, IL-13, IL-31, IL-33, and thymic stromal lymphopoietin), neurotransmitters (eg, substance P, calcitonin gene-related peptide, vasoactive intestinal peptide, neuropeptide Y, NBNP, endothelin 1, and gastrin-releasing peptide), and neurotrophins (eg, nerve growth factor and brain-derived neurotrophic factor). Moreover, ion channels such as voltage-gated sodium channels, transient receptor potential vanilloid 1, transient receptor ankyrin, and transient receptor potential cation channel subfamily M (melastatin) member 8 play a crucial role. The main markers of nonhistaminergic pruriceptors are PAR-2 and MrgprX2. A notable phenomenon is the sensitization to pruritus, in which regardless of the initial cause of pruritus, there is an increased responsiveness of peripheral and central pruriceptive neurons to their normal or subthreshold afferent input in the context of chronic itch.

Neuroimmune interactions in atopic and allergic contact dermatitis

The skin is a barrier organ populated by many types of skin-resident immune cells and sensory neurons. It has become increasingly appreciated that neuroimmune interactions are an important component of inflammatory diseases such as atopic dermatitis and allergic contact dermatitis. Neuropeptides secreted from nerve terminals play an important role in mediating cutaneous immune cell function, and soluble mediators derived from immune cells interact with neurons to induce itch. In this review article, we will explore emerging research describing neuronal effector functions on skin immune cells in mouse models of atopic and contact dermatitis. We will also discuss the contributions of both specific neuronal subsets and secreted immune factors to itch induction and the associated inflammatory processes. Finally, we will explore how treatment strategies have emerged around these findings and discuss the relationship between scratching and dermatitis.

Novel Insights into the Role of Keratinocytes-Expressed TRPV3 in the Skin

TRPV3 is a non-selective cation channel that is highly expressed in keratinocytes in the skin. Traditionally, keratinocytes-expressed TRPV3 is involved in multiple physiological and pathological functions of the skin, such as itching, heat pain, and hair development. Although the underlying mechanisms by which TRPV3 functions in vivo remain obscure, recent research studies suggest that several cytokines and EGFR signaling pathways may be involved. However, there have also been other studies with opposite results that question the role of TRPV3 in heat pain. In addition, an increasing number of studies have suggested a novel role of TRPV3 in promoting skin regeneration, indicating that TRPV3 may become a new potential target for regulating skin regeneration. This paper not only reviews the role of keratinocytes-expressed TRPV3 in the physiological and pathological processes of itching, heat pain, hair development, and skin regeneration, but also reviews the relationship between TRPV3 gene mutations and skin diseases such as atopic dermatitis (AD) and Olmsted syndrome (OS). This review will lay a foundation for further developing our understanding of the mechanisms by which TRPV3 is involved in itching, heat pain, and hair development, as well as the treatments for TRPV3-related skin diseases.

Pruritogenic Mediators and New Antipruritic Drugs in Atopic Dermatitis

Atopic dermatitis (AD) is a common highly pruritic chronic inflammatory skin disorder affecting 5-20% of children worldwide, while the prevalence in adults varies from 7 to 10%. Patients with AD experience intense pruritus that could lead to sleep disturbance and impaired quality of life. Here, we analyze the pathophysiology of itchiness in AD. We extensively review the histamine-dependent and histamine-independent pruritogens. Several receptors, substance P, secreted molecules, chemokines, and cytokines are involved as mediators in chronic itch. We also, summarize the new emerging antipruritic drugs in atopic dermatitis.

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.

Neural Regulation of Innate Immunity in Inflammatory Skin Diseases

As the largest barrier organ of the body, the skin is highly innervated by peripheral sensory neurons. The major function of these sensory neurons is to transmit sensations of temperature, pain, and itch to elicit protective responses. Inflammatory skin diseases are triggered by the aberrant activation of immune responses. Recently, increasing evidence has shown that the skin peripheral nervous system also acts as a regulator of immune responses, particularly innate immunity, in various skin inflammatory processes. Meanwhile, immune cells in the skin can express receptors that respond to neuropeptides/neurotransmitters, leading to crosstalk between the immune system and nervous system. Herein, we highlight recent advances of such bidirectional neuroimmune interactions in certain inflammatory skin conditions.

Torilis japonica Extract Suppresses the Induction of Atopic Inflammation

As one of the major intractable allergic disorders, atopic inflammation is commonly accompanied by itching, dry skin, and inflammation. Atopic inflammation deteriorates the quality of life and has no fundamental cure, so it is crucial to urgently explore and develop natural resources for long-term treatment without any side effects. This study aimed to verify Torilis japonica extract (TJE)'s relieving effect and mechanism against atopic inflammation using skin cells and skin equivalent models, as well as to investigate torilin's effect (obtained from TJE) and other unknown components as marker compounds. Torilin concentration was verified in TJE using high-performance liquid chromatography and analyzed the unknown components using nuclear magnetic resonance spectroscopy. Furthermore, TJE's cytotoxicity, regenerative effect, and cell cycle regulation effects were confirmed using skin cells with atopic inflammation (human dermal fibroblasts and HaCaT keratinocytes) by using TNF-α and IFN-γ treatments. Consequently, TJE was demonstrated to regulate TARC and CTACK expressions as chemokines and those of interleukin-4, -5, and -13 as cytokines related to atopic inflammation. TJE was further confirmed to affect the matrix metalloproteinase-1, -2, and -9 expressions, which are essential in skin damage. Lastly, this study confirmed TJE's relieving effect against atopic inflammation through a 3D skin model and RhCE model using human dermal fibroblasts and HaCaT keratinocytes. These findings on atopic inflammation verified torilin's relieving effects and TJE's other components.

Lactobacillus for the treatment and prevention of atopic dermatitis: Clinical and experimental evidence

Atopic dermatitis (AD) is a chronic inflammatory skin disease, accompanied by itching and swelling. The main pathological mechanism of AD is related to the imbalance between Type 2 helper cells (Th2 cells) and Type 1 helper cells (Th1 cells). Currently, no safe and effective means to treat and prevent AD are available; moreover, some treatments have side effects. Probiotics, such as some strains of Lactobacillus, can address these concerns via various pathways: i) facilitating high patient compliance; ii) regulating Th1/Th2 balance, increasing IL-10 secretion, and reducing inflammatory cytokines; iii) accelerating the maturation of the immune system, maintaining intestinal homeostasis, and improving gut microbiota; and iv) improving the symptoms of AD. This review describes the treatment and prevention of AD using 13 species of Lactobacillus. AD is commonly observed in children. Therefore, the review includes a higher proportion of studies on AD in children and fewer in adolescents and adults. However, there are also some strains that do not improve the symptoms of AD and even worsen allergies in children. In addition, a subset of the genus Lactobacillus that can prevent and relieve AD has been identified in vitro. Therefore, future studies should include more in vivo studies and randomized controlled clinical trials. Given the advantages and disadvantages mentioned above, further research in this area is urgently required.