Neuro-immune communication regulating pruritus in atopic dermatitis

Ruxolitinib cream monotherapy for facial and/or neck atopic dermatitis: results from a decentralized, randomized phase 2 clinical trial

PURPOSE

Ruxolitinib cream was evaluated in patients with facial/neck atopic dermatitis (AD) in a decentralized, double-blind, randomized clinical trial (NCT05127421).

MATERIALS AND METHODS

Patients aged 12-70 years with AD (Investigator's Global Assessment [IGA] score 2/3, ≤20% affected body surface area [face/neck, ≥0.5%]) were randomized 2:1 to twice-daily 1.5% ruxolitinib cream or vehicle for 4 weeks; thereafter, all patients applied as-needed ruxolitinib cream for 4 additional weeks. The primary endpoint was ≥75% improvement in head/neck Eczema Area and Severity Index (EASI-75) at Week 4 assessed by blinded central reader using photographs.

RESULTS

Among 77 randomized patients (median [range] age, 38.0 [17-66] y), 44.2% were Black. The mean (SD) baseline head/neck EASI was 1.2 (0.7). More patients who applied ruxolitinib cream vs vehicle achieved head/neck EASI-75 at Week 4 (37.0% vs 17.4%; p = 0.091). Improvements with ruxolitinib cream vs vehicle were observed for facial/neck IGA treatment success (IGA 0/1 with ≥2-point improvement from baseline) and Patient-Oriented Eczema Measure (overall and itch). Ruxolitinib cream was well tolerated, including on the face and neck. Application site reactions were infrequent (ruxolitinib cream, 1.9% [n = 1]; vehicle, 8.7% [n = 2]).

CONCLUSIONS

Ruxolitinib cream improved signs and symptoms of facial/neck AD vs vehicle and was well tolerated.

Evaluation of oclacitinib maleate and prednisolone combined therapy for the control of atopic dermatitis in dogs: A controlled clinical trial

BACKGROUND

Canine atopic dermatitis (cAD) is a chronic inflammatory and pruritic dermatopathy requiring a multimodal therapeutic approach.

OBJECTIVE

To assess the effectiveness, safety and cost of oclacitinib and prednisolone treatment in dogs with AD.

ANIMALS

Twenty-three client-owned dogs with cAD.

MATERIALS AND METHODS

Dogs were randomly assigned to one of two groups: Group 1 received prednisolone (0.5 mg/kg every 24 h) for 7 days, then oclacitinib (0.5 mg/kg) and prednisolone (0.5 mg/kg), were administered alternately with a 1 day pause between each drug, for 7 additional weeks. Group 2 received oclacitinib (0.5 mg/kg every 12 h for 14 days, then every 24 h) for 8 weeks. Assessments included the Canine Atopic Dermatitis Extent and Severity Index, 4th iteration (CADESI-04) and pruritus Visual Analog Scale (PVAS) on Day (D)0, D7, D14, D30, D45 and D60.

RESULTS

Both groups showed significant CADESI and PVAS reductions on D7 (p < 0.001). From D14 to D60, mean scores remained stable compared to D7, with no significant differences between groups. Adverse events included two dogs with polyuria and polydipsia, and three with polyphagia in Group 1, all of which resolved by D14. In Group 2, one dog experienced polyphagia, and two had self-limiting vomiting. Three dogs in Group 1 and one dog in Group 2 had mild increases in liver enzyme concentrations.

CONCLUSIONS AND CLINICAL RELEVANCE

The combined protocol was effective and safe for managing itch and inflammation over a 60 day period. It had a 73.3% lower cost compared to oclacitinib alone.

Identification and Validation of the Potential Key Biomarkers for Atopic Dermatitis Mitochondrion by Learning Algorithms

Purpose

Atopic dermatitis (AD) is a common inflammatory skin condition characterized by erythema and pruritus. Its precise pathogenesis remains unclear, though factors such as genetic predisposition, autoantigen response, allergen exposure, infections, and skin barrier dysfunction are involved. Research suggests a correlation between AD and mitochondrial dysfunction, as well as oxidative stress in skin tissues.

Methods

 Skin sample datasets related to AD (GSE36842, GSE120721, GSE16161, and GSE121212) were retrieved from the GEO database. Differential gene analysis identified differentially expressed genes (DEGs) in AD. Three potential biomarkers-COX17, ACOX2, and ADH1B-were identified using LASSO and Support Vector Machine (SVM) algorithms. These biomarkers were validated through ROC curve analysis, nomogram modeling, calibration curves, and real-time PCR. Immune infiltration analysis assessed correlations of the biomarkers. Additionally, single-cell analysis of the GSE153760 dataset identified nine cell clusters and confirmed expression patterns of the three hub genes.

Results

Differential analysis identified 150 upregulated and 367 downregulated genes. Enrichment analysis revealed significant pathways related to mitochondrial function, oxidative stress, and energy metabolism in skin samples from AD patients. Area under the curve (AUC) values for biomarkers COX17, ACOX2, and ADH1B were 1.000, 0.928, and 0.895, respectively, indicating strong predictive capacity. qPCR results showed COX17 was highly expressed in AD lesions, while ACOX2 and ADH1B were higher in normal skin, consistent with previous findings. Correlation analysis indicated ACOX2 and ADH1B were positively correlated with resting mast cells but negatively with activated T cells and NK cells, while COX17 showed a positive correlation with activated T cells and a negative correlation with resting mast cells.

Conclusion

This study suggests that the hub genes COX17, ACOX2, and ADH1B may serve as potential biomarkers in the pathogenesis of AD. These findings could provide insights for the treatment and prognosis of AD and related inflammatory skin conditions.

MRI-based neuroimaging alterations in immune-related skin diseases: a comprehensive review

The skin, as the largest organ in the human body, serves as the primary physical barrier and plays a crucial role in the immune defense process. Immune-related skin diseases encompass a spectrum of complex dermatological conditions characterized by aberrant immune responses, including the production of autoantibodies and dysregulation of inflammatory mediators. Growing evidence suggest a heightened prevalence of comorbid neuropsychiatric disorders among patients with immune-related skin diseases, indicative of potential shared pathogenesis. In recent years, the brain connectome, delineating the intricate network of neural connections, has gained prominence in elucidating various neurological and psychiatric conditions. Researchers have begun to investigate whether alterations in brain connectivity occur in patients with immune-related skin diseases, thereby exploring the connectome perspective in understanding the pathogenesis of these diseases. This review aims to synthesize and analyze recent neuroimaging studies about immune-related skin diseases, including systemic lupus erythematosus, psoriasis, chronic spontaneous urticaria, and atopic dermatitis. We mainly discussed the connectome studies related to these diseases and summarized the underlying mechanisms associated with their clinical manifestations, progression, and treatment. Then from our perspectives, we believe that interdisciplinary collaborations encompassing fields such as neurology, psychiatry, dermatology, and neuroimaging will be instrumental in advancing our understanding of immune-related skin diseases. Furthermore, multi-omics approaches will enable a comprehensive exploration of the molecular mechanisms underlying these neural changes, facilitating the identification of novel diagnostic biomarkers and therapeutic targets.

3D-printed gelatin/dialdehyde starch hydrogels for hydrocortisone topical administration and in vivo treatment of atopic dermatitis

Atopic dermatitis (AD) is a chronic disorder affecting millions worldwide. Recent advancements suggest that combining therapies can significantly improve AD treatment outcomes and mitigate the challenges of long-term drug use, particularly with corticosteroids. In this study, we developed a 3D-printed hydrogel composed of gelatin (Gel) and dialdehyde starch (DAS), capable of encapsulating and delivering hydrocortisone (HC). DAS was synthesized via an oxidation reaction, introducing aldehyde groups that facilitated hydrogel formation with Gel through imine bond formation (Schiff base reaction). By adjusting the Gel/DAS ratio, we formulated inks with suitable rheological properties for extrusion-based 3D printing, an approach not yet fully exploited in this context. The resulting Gel/DAS network successfully encapsulated HC, as demonstrated by characterization analyses. The printed hydrogel exhibited a well-defined microstructure, significant water absorption and retention capabilities, and excellent stability. HC release followed a controlled mechanism consistent with Korsmeyer-Peppas kinetics. In an in vivo model, the 3D-printed hydrogel containing HC showed therapeutic efficacy comparable to conventional HC treatments in alleviating AD symptoms in mice. Additionally, the hydrogel significantly reduced myeloperoxidase (MPO) activity and increased non-protein thiol (NPSH) levels in the dorsal skin of DNCB-exposed mice, underscoring its therapeutic potential.

Effectiveness of Extracellular Vesicle Application in Skin Aging Treatment and Regeneration: Do We Have Enough Evidence from Clinical Trials?

In recent years, there has been a dynamic development in therapies utilizing extracellular vesicles (EVs) including exosomes. Therefore, we have conducted an analysis of the scientific literature to verify the current state of knowledge about these therapies. A total of 12 clinical studies were analyzed, covering the use of EVs in treating skin aging, acne scars, alopecia, and wound healing. The results indicate that EVs and exosomes hold potential in regenerative skin therapies, offering innovative and non-invasive therapeutic approaches. At the same time, significant challenges related to the standardization of their production and the lack of large-scale randomized studies were identified. Thus, we also evaluated the investigated clinical trials in regard to the MISEV (Minimal Information for Studies of Extracellular Vesicles) criteria. This review provides a comprehensive overview of the contemporary applications of EVs in skin therapy and regenerative medicine, highlighting directions for further research.

Altered Sensory and Stress Responses in Atopic Dermatitis: Effects of Acute Stress on Lesional and Non-Lesional Skin

Itch and pain are both mediated by small sensory fibres. Atopic dermatitis (AD) patients usually report stress-induced flares, but the impact of stress on sensory fibres in lesional and non-lesional skin remains inconclusive. This observational study assessed the effect of acute stress on sensory profiles in subjects with AD (n = 18) and healthy controls (HC, n = 21). Participants completed clinical and psychological questionnaires, and quantitative sensory testing was performed on lesional and non-lesional skin in AD and healthy skin in HC. Assessments were done before and after the Montreal Imaging Stress Task, an acute stress protocol. Stress responses were evaluated by anxiety ratings, heart rate (HR) and salivary cortisol (CORT). Cortisol binding globulin (CBG) was quantified as an indirect measure for circulating CORT. AD participants reported higher anxiety, depression and stress perception than HC. HR was similar between groups, but AD participants showed a blunted CORT response post-stress and lower CBG levels, suggesting altered stress regulation. Acute stress reduced cold sensitivity in HC and non-lesional AD skin but had no effect on lesions. These findings indicate that the effects of stress on small fibres depend on the condition of the skin and emphasise the sensory alterations experienced by AD patients.

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.

Filaggrinopathies-FLG/FLG2: Diagnostic Complexities and Immunotherapy

FLG and FLG2 proteins are expressed in the outer layers of the epidermis, where they are vital in epidermal differentiation and skin barrier formation. Filaggrinopathies involving dysfunctions in these proteins are associated with a spectrum of phenotypic presentations, from monogenic to multifactorial conditions. This review examines biosynthesis and function of FLG and FLG2 proteins and evaluates their molecular pathogenesis in filaggrinopathies. Moreover, genotype-phenotype correlations are assessed, emphasizing genetic diagnosis complexities and diverse immune dysregulation patterns. Finally, it examines ongoing immunotherapeutic approaches by targeting different cytokines as promising treatment options for filaggrinopathies management.

Transcriptomic profiling of dorsal root ganglia in atopic and healthy dogs: A comparative RNA sequencing study with implications in cutaneous itch research

BACKGROUND

Itch is a common clinical sign in skin disorders. While the neural pathways of itch transmission from the skin to the brain are well understood in rodents, the same pathways in dogs remain unclear. The knowledge gap hinders the development of effective treatments for canine itch-related disorders.

HYPOTHESIS/OBJECTIVES

This study aimed to investigate the differential gene expression in the dorsal root ganglia (DRGs) between healthy and atopic dogs to identify specific molecules potentially involved in itch signalling and neuroinflammation in canine atopic dermatitis (cAD).

ANIMALS

Two atopic and four healthy dogs.

MATERIALS AND METHODS

DRGs were collected from atopic and healthy dogs to compare their transcriptional profiles using RNA sequencing.

RESULTS

Principal component and heatmap analyses revealed two distinct clusters separating atopic from healthy dogs. Consistent with this observation, we identified 627 (543 upregulated and 84 downregulated) differentially expressed genes (DEGs) in atopic compared with healthy dogs. We further narrowed down our genes of interest to common DEGs in each atopic dog, which revealed 159 (132 upregulated and 27 downregulated) DEGs. Among these genes, when we focused on itch signalling-associated molecules, P2RY12, IL-2RG, TLR1 and POSTN were significantly upregulated, while MRGPRD and LPAR3 were both significantly downregulated in atopic dogs compared with those in healthy dogs. Pathway analysis showed a significant upregulation of CREB signalling in neurons, myelination signalling and neuroinflammation signalling pathways in atopic dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

Our study suggested that dysregulation of neuroinflammatory pathways might play a role in the pathomechanism of cAD as in humans.

Ruxolitinib Cream Monotherapy Improved Symptoms and Quality of Life in Adults and Adolescents with Mild-to-Moderate Atopic Dermatitis: Patient-Reported Outcomes from Two Phase III Studies

BACKGROUND

Atopic dermatitis (AD) is associated with itch, skin pain, sleep disturbances, and diminished quality of life (QoL). Ruxolitinib (Janus kinase [JAK] 1/JAK2 inhibitor) cream demonstrated efficacy and safety in adults and adolescents with mild-to-moderate AD in two phase III studies (TRuE-AD1/TRuE-AD2). In TRuE-AD1/TRuE-AD2, significant improvements in itch were observed as early as 12 h following application of ruxolitinib cream.

OBJECTIVE

The aim of this paper was to assess additional patient-reported outcomes (PROs) in the vehicle-controlled (VC) and long-term safety (LTS) periods of TRuE-AD1/TRuE-AD2.

METHODS

In the TRuE-AD studies, patients aged ≥12 years with AD were randomized 2:2:1 to apply twice-daily 1.5% ruxolitinib cream, 0.75% ruxolitinib cream, or vehicle cream continuously for 8 weeks (VC period). During the LTS period, patients applied the same ruxolitinib cream strength, but on an as-needed basis; patients who initially applied vehicle were re-randomized to apply 0.75% or 1.5% ruxolitinib cream. Pooled data from both study periods were analyzed. PRO assessments included symptoms (itch [Patient-Oriented Eczema Measure, POEM], skin pain [numerical rating scale], and sleep [POEM and Patient-Reported Outcomes Measurement Information System]) and assessments of disease-specific QoL (Dermatology Life Quality Index [DLQI] and the children's version [CDLQI]).

RESULTS

A total of 1208 and 1031 patients from the VC and LTS periods, respectively, were included in the analysis. Significant improvements in skin pain were observed within 12 h among patients who applied ruxolitinib cream versus vehicle; improvements continued throughout the VC period. Improvements in patient-reported symptoms (including sleep) were observed within 2 weeks (first assessment) of ruxolitinib cream application. At Week 2, significant improvements in symptom burden and overall QoL were observed with ruxolitinib cream (0.75%/1.5%) versus vehicle in POEM (-8.9/-9.8 vs -2.2; both p < 0.0001), DLQI (mean changes from baseline, -5.8/-6.1 vs -1.2; both p < 0.0001), and CDLQI (-4.3/-5.3 vs -1.3; both p < 0.0001). Further symptom burden and QoL improvements were reported during the VC period and were maintained through the end of the LTS period (Week 52).

CONCLUSIONS

Consistent with the previously reported itch response data, ruxolitinib cream improved skin pain within 12 h of application. Ruxolitinib cream improved patient-reported AD symptom burden and overall QoL by Week 2. Improvements continued or were maintained for 52 weeks. (Graphical abstract and plain language summary available).

TRIAL REGISTRATION

ClinicalTrials.gov identifiers, NCT03745638 and NCT03745651 (both studies were registered on November 19, 2018).

IL-27 as a novel biomarker for pruritus in nodular prurigo and bullous pemphigoid

Introduction

Bullous pemphigoid (BP) and prurigo nodularis (PN) are chronic pruritic skin diseases that severely impact patients' quality of life. Despite the widespread attention these two diseases have garnered within the dermatological field, the specific pathogenesis, particularly the molecular mechanisms underlying the pruritus, remains largely unclear. Limited clinical sequencing studies focusing on BP and PN have hindered the identification of pathological mechanisms and the exploration of effective treatment strategies.

Methods

To address this gap, we collected a total of 23 peripheral blood mononuclear cell samples from BP and PN patients, as well as healthy controls, and performed RNA sequencing analysis. By integrating bioinformatics and machine learning techniques, we aimed to uncover the shared immune regulatory networks and pruritus-related mechanisms between BP and PN.

Results

Our study identified 161 differentially expressed genes shared between BP and PN, which were primarily enriched in immune activation and neural pathways, providing crucial molecular insights into the pruritus-related mechanisms of both diseases. Furthermore, using the machine learning algorithms of support vector machines and random forest, we pinpoint 7 crucial genes shared between the BP and PN databases. Among these, IL-27 emerged as a potential pivotal gene, as its mRNA expression levels strongly correlated with clinical parameters including pruritus scores, immunoglobulin E levels, and eosinophil counts. Validation experiments conducted on clinical samples from an additional 22 participants confirmed the upregulation of IL-27 expression in both BP and PN lesions.

Discussion

This study is the first to unveil the shared inflammatory and immune pathways common to BP and PN, highlighting the critical role of IL-27 in the pathogenesis of these conditions. Our findings not only enhance the understanding of the intricate relationship between BP and PN, but also provide a foundation for the development of novel therapeutic strategies targeting these two dermatological conditions.

Skin microdialysis detects distinct immunologic patterns in chronic inflammatory skin diseases

BACKGROUND

Insight into the pathophysiology of inflammatory skin diseases, especially at the proteomic level, is severely hampered by the lack of adequate in situ data.

OBJECTIVE

We characterized lesional and nonlesional skin of inflammatory skin diseases using skin microdialysis.

METHODS

Skin microdialysis samples from patients with atopic dermatitis (AD, n = 6), psoriasis vulgaris (PSO, n = 7), or prurigo nodularis (PN, n = 6), as well as healthy controls (n = 7), were subjected to proteomic and multiplex cytokine analysis. Single-cell RNA sequencing of skin biopsy specimens was used to identify the cellular origin of cytokines.

RESULTS

Among the top 20 enriched Gene Ontology (GO; geneontology.org) annotations, nicotinamide adenine dinucleotide metabolic process, regulation of secretion by cell, and pyruvate metabolic process were elevated in microdialysates from lesional AD skin compared with both nonlesional skin and controls. The top 20 enriched Kyoto Encyclopedia of Genes and Genomes (KEGG; genome.jp/kegg) pathways in these 3 groups overlapped almost completely. In contrast, nonlesional skin from patients with PSO or PN and control skin showed no overlap with lesional skin in this KEGG pathway analysis. Lesional skin from patients with PSO, but not AD or PN, showed significantly elevated protein levels of MCP-1 compared with nonlesional skin. IL-8 was elevated in lesional versus nonlesional AD and PSO skin, whereas IL-12p40 and IL-22 were higher only in lesional PSO skin. Integrated single-cell RNA sequencing data revealed identical cellular sources of these cytokines in AD, PSO, and PN.

CONCLUSION

On the basis of microdialysates, the proteomic data of lesional PSO and PN skin, but not lesional AD skin, differed significantly from those of nonlesional skin. IL-8, IL-22, MCP-1, and IL-12p40 might be suitable markers for minimally invasive molecular profiling.

Neuropeptides or their receptors in pathogenesis of lung diseases and therapeutic potentials

There are complex interactions between the immune system and the nervous system in the lung. The nervous system perceives environmental stimuli and transmits these signals to immune cells via neurotransmitters, which is essential for effective immunity and environmental balance. Neuropeptides are important neurotransmitters in the lung, where they regulate immune responses through direct and indirect mechanisms, affecting the occurrence and development of lung diseases. In this review, we emphasize the role of neuropeptides in the pathogeneis of lung diseases and their potential therapeutic value for lung diseases.

Effects of Huang-Lian-Jie-Du decoction on improving skin barrier function and modulating T helper cell differentiation in 1-chloro-2,4-dinitrobenzene-induced atopic dermatitis mice

Background: Atopic dermatitis (AD) is among the most frequently encountered skin diseases, bothering a considerable number of patients. Today, corticosteroids and antihistamines are among the numerous drugs applied for the therapy of AD. However, lengthy use of them contributes to side effects, such as physiological changes in skin. As an alternative and supplementary therapy, traditional Chinese medicine has become a trend for AD treatment. Huang-Lian-Jie-Du decoction (HLJDD), a renowned herbal formula has been employed to treat inflammatory diseases such as AD. However, its role in regulating immunity in AD remains unclear. The object of this study was to elucidate the efficacy of HLJDD and reveal the implicit mechanism from an immunological perspective in AD-like mice. Methods: In brief, 1-chloro-2,4-dinitrobenzene (DNCB) for the sensitization phase (1% DNCB) and stimulation phase (1.5% DNCB) were applied for BALB/c mice. HLJDD and dexamethasone (DXMS) were administered orally to the mice. Mice skin and spleens were collected to evaluate the efficacy of HLJDD. 16S rRNA sequencing was applied to evaluate the commensal microbiota changes in skin and fecal. In vitro, spleen CD4+ T cells and bone marrow-derived mast cells (BMMCs) were co-cultured to explore the modulation of HLJDD in T helper (Th) cells phenotyping. Results: HLJDD showcased a substantial amelioration in skin through the upregulation of FLG, LOR, AQP3, and reducing scratching behaviors in AD-like mice, Also, the quantity of infiltrated mast cells (MCs), pruritus-related mRNA were decreased. In addition, the expression of OX40/OX40L was decreased by HLJDD, which was critical in Th-cell phenotyping. With the treatment of HLJDD, Th1/Th2 and Th17/Treg ratios in AD-like mice became balanced. The structure of commensal microbiota in AD-like mice was affected by HLJDD. HLJDD could also improve the imbalance of Th17/Treg in vitro. Conclusion: HLJDD could improve the symptoms of AD-like mice by alleviating the scratching behaviors via decreased Th2 and pruritus-related mRNA expression. HLJDD also enhanced the relative diversity of skin microbiota and changed the structure of intestinal microbiota. An in-depth study found that HLJDD could balance the ratio of Th1/Th2, Th17/Treg in AD-like mice, and Th17/Treg in vitro by regulating the OX40/OX40L signaling pathway.

Resolution of Chronic Inflammation, Restoration of Epigenetic Disturbances and Correction of Dysbiosis as an Adjunctive Approach to the Treatment of Atopic Dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease with multifactorial and unclear pathogenesis. Its development is characterized by two key elements: epigenetic dysregulation of molecular pathways involved in AD pathogenesis and disrupted skin and gut microbiota (dysbiosis) that jointly trigger and maintain chronic inflammation, a core AD characteristic. Current data suggest that failed inflammation resolution is the main pathogenic mechanism underlying AD development. Inflammation resolution is provided by specialized pro-resolving mediators (SPMs) derived from dietary polyunsaturated fatty acids acting through cognate receptors. SPM levels are reduced in AD patients. Administration of SPMs or their stable, small-molecule mimetics and receptor agonists, as well as supplementation with probiotics/prebiotics, demonstrate beneficial effects in AD animal models. Epidrugs, compounds capable of restoring disrupted epigenetic mechanisms associated with the disease, improve impaired skin barrier function in AD models. Based on these findings, we propose a novel, multilevel AD treatment strategy aimed at resolving chronic inflammation by application of SPM mimetics and receptor agonists, probiotics/prebiotics, and epi-drugs. This approach can be used in conjunction with current AD therapy, resulting in AD alleviation.

Untargeted metabolomics analysis reveals the potential mechanism of imatinib-induced skin rash in patients with gastrointestinal stromal tumor

Imatinib-induced skin rash poses a significant challenge for patients with gastrointestinal stromal tumor, often resulting in treatment interruption or discontinuation and subsequent treatment failure. However, the underlying mechanism of imatinib-induced skin rashes in gastrointestinal stromal tumor patients remains unclear. A total of 51 patients (27 with rash and 24 without rash) were enrolled in our study. Blood samples were collected concomitantly with the onset of clinical manifestations of rashes, and simultaneously collecting clinical relevant information. The imatinib concentration and untargeted metabolomics were performed by ultra-high-performance liquid chromatography-tandem mass spectrometry. There were no significant differences in age, gender, imatinib concentration and white blood cells count between the rash group and the control group. However, the rash group exhibited a higher eosinophil count (P<0.05) and lower lymphocyte count (P<0.05) compared to the control group. Untargeted metabolomics analysis found that 105 metabolites were significantly differentially abundant. The univariate analysis highlighted erucamide, linoleoylcarnitine, and valine betaine as potential predictive markers (AUC≥0.80). Further enriched pathway analysis revealed primary metabolic pathways, including sphingolipid signaling pathway, sphingolipid metabolism, cysteine and methionine metabolism, biosynthesis of unsaturated fatty acids, arginine and proline metabolism, and biosynthesis of amino acids. These findings suggest that the selected differential metabolites could serve as a foundation for the prediction and management of imatinib-induced skin rash in gastrointestinal stromal tumor patients.

The relationship between allergic rhinitis and attention deficit hyperactivity disorder: a systematic review and meta-analysis

Background

Numerous investigations have examined the potential link between allergic rhinitis (AR) and attention deficit hyperactivity disorder (ADHD). However, some studies show no association between the two diseases. The connection between these two conditions remains inconclusive. This study aimed to conduct a meta-analysis exploring the correlation between AR and ADHD.

Methods

We conducted systematic searches of the MEDLINE, EMBASE, Cochrane Library, ERIC, PubMed, Web of Science, and CINAHL databases, up to the year 2023. Subsequently, we conducted a meta-analysis using R 4.2.2, where we computed the pooled odds ratio with a 95% confidence interval to assess the relationship between AR and ADHD within studies exhibiting similar characteristics. Statistical heterogeneity was evaluated by computing the value using the Cochrane Intervention Manual's guidelines. Additionally, subgroup analyses were conducted by stratifying the study population according to gender, age, etc. Sensitivity analysis was performed by systematically removing individual studies.

Results

In this systematic review, we incorporated 12 eligible studies, collectively encompassing a sample size of 530,360 participants. Within the included studies, heterogeneity was observed, and the utilization of a random-effects model demonstrated a noteworthy correlation between children with ADHD and the presence of AR. Similarly, children with AR exhibited a significant correlation with the occurrence of ADHD. We also found some relationships in subgroup analyses.

Conclusion

A substantial correlation is evident between AR and ADHD in children and adolescents. AR may potentially contribute as a risk factor for the onset of ADHD, and conversely, ADHD may heighten the likelihood of developing AR.

Atopic dermatitis and food allergy: More than sensitization

The increased risk of food allergy in infants with atopic dermatitis (AD) has long been recognized; an epidemiologic phenomenon termed "the atopic march." Current literature supports the hypothesis that food antigen exposure through the disrupted skin barrier in AD leads to food antigen-specific immunoglobulin E production and food sensitization. However, there is growing evidence that inflammation in the skin drives intestinal remodeling via circulating inflammatory signals, microbiome alterations, metabolites, and the nervous system. We explore how this skin-gut axis helps to explain the link between AD and food allergy beyond sensitization.

Navigating the evolving landscape of atopic dermatitis: Challenges and future opportunities: The 4th Davos declaration

The 4th Davos Declaration was developed during the Global Allergy Forum in Davos which aimed to elevate the care of patients with atopic dermatitis (AD) by uniting experts and stakeholders. The forum addressed the high prevalence of AD, with a strategic focus on advancing research, treatment, and management to meet the evolving challenges in the field. This multidisciplinary forum brought together top leaders from research, clinical practice, policy, and patient advocacy to discuss the critical aspects of AD, including neuroimmunology, environmental factors, comorbidities, and breakthroughs in prevention, diagnosis, and treatment. The discussions were geared towards fostering a collaborative approach to integrate these advancements into practical, patient-centric care. The forum underlined the mounting burden of AD, attributing it to significant environmental and lifestyle changes. It acknowledged the progress in understanding AD and in developing targeted therapies but recognized a gap in translating these innovations into clinical practice. Emphasis was placed on the need for enhanced awareness, education, and stakeholder engagement to address this gap effectively and to consider environmental and lifestyle factors in a comprehensive disease management strategy. The 4th Davos Declaration marks a significant milestone in the journey to improve care for people with AD. By promoting a holistic approach that combines research, education, and clinical application, the Forum sets a roadmap for stakeholders to collaborate to improve patient outcomes in AD, reflecting a commitment to adapt and respond to the dynamic challenges of AD in a changing world.

Pathogenesis of Inflammation in Skin Disease: From Molecular Mechanisms to Pathology

Many skin diseases begin with inflammatory changes on a molecular level. To develop a more thorough understanding of skin pathology and to identify new targets for therapeutic advancements, molecular mechanisms of inflammation in the context of skin disease should be studied. Current research efforts to better understand skin disease have focused on examining the role of molecular processes at several stages of the inflammatory response such as the dysregulation of innate immunity sensors, disruption of both transcriptional and post-transcriptional regulation, and crosstalk between immune and neuronal processes (neuro-immune crosstalk). This review seeks to summarize recent developments in our understanding of inflammatory processes in skin disease and to highlight opportunities for therapeutic advancements. With a focus on publications within the past 5 years (2019-2024), the databases PubMed and EBSCOhost were used to search for peer-reviewed papers regarding inflammatory molecular mechanisms and skin disease. Several themes of research interest regarding inflammatory processes in skin disease were determined through extensive review and were included based on their relative representation in current research and their focus on therapeutic potential. Several skin diseases such as psoriasis, atopic dermatitis, hidradenitis suppurativa, and scleroderma were described in the paper to demonstrate the widespread influence of inflammation in skin disease.

Integrative Treatment Approaches with Mind-Body Therapies in the Management of Atopic Dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease with a complex pathophysiology characterized by intense pruritus, often associated with psychological stress and atopic and non-atopic comorbidities that significantly reduce quality of life. The psychological aspects of AD and the interaction between the mind and body via the skin-brain axis have led to an interest in mind-body therapies (MBT). The aim of this article is, therefore, to reinforce the importance of psychodermatological care in AD. We performed a focused literature review on holistic practices or integrative MBT in AD, including education, cognitive behavioral therapy, habit reversal, meditation, mindfulness, hypnotherapy, eye movement desensitization and reprocessing, biofeedback, progressive muscle relaxation, autonomous sensory meridian response, music therapy, massage, and touch therapy. A multidisciplinary holistic approach with MBT, in addition to conventional pharmacologic antipruritic therapies, to break the itch-scratch cycle may improve AD outcomes and psychological well-being. Although there is a paucity of rigorously designed trials, evidence shows the potential benefits of an integrative approach on pruritus, pain, psychological stress, anxiety, depressive symptoms, and sleep quality. Relaxation and various behavioral interventions, such as habit reversal therapy for replacing harmful scratching with massaging with emollient 'plus', may reduce the urge to scratch, while education may improve adherence to conventional therapies.

[Mental disorders from climate and environmental changes using the example of dermatology]

BACKGROUND

Global climate and environmental changes impose a significant impact on human health by increasing prevalences of chronic and acute skin diseases. Climate-associated environmental changes can also trigger or intensify mental illnesses independently of a skin disease.

AIM

Discussion of the effects of the climate and environmental changes on dermatological diseases applying the biopsychosocial model.

MATERIALS AND METHODS

A selective literature search in the PubMed database and other sources was conducted.

RESULTS

The biopsychosocial model considers complex interactions between biological, psychological, and social factors. In view of the consequences of climate and environmental changes, an extension of the model is proposed for the first time in order to address new challenges. The modified presentation supports the understanding of the dynamics and underscores that in dermatological care not only direct health effects of climate and environmental changes have to be dealt with, but also with an increasing number of mental illnesses, which in turn are to be regarded as direct and indirect health effects.

CONCLUSION

Coping with the predicted increase in the burden of disease and the decline in the available labor force associated with demographic change poses a major challenge. In order to maintain the functionality of the healthcare system, the prompt implementation of resource-efficient, sustainable measures in all areas of society is essential. The integrative consideration of dermatological and psychological complaints in the context of climate and environmental changes requires the adaptation of content for the education, training, and continuing education of specialists.

Efficacy and feasibility analysis of compound fluocinolone acetonide cream combined with guaiazulene in the treatment of neurodermatitis

OBJECTIVE

To evaluate the effectiveness and feasibility of combined treatment with compound fluocinolone acetonide cream and guaiazulene in patients with neurodermatitis.

METHODS

A prospective study was conducted on 92 outpatient patients diagnosed with neurodermatitis at our dermatology department from January 2022 to December 2023. Using a random number table, these patients were evenly divided into a control group and an experimental group, with 46 individuals in each group. The control group received treatment with compound fluocinolone acetonide alone, while the experimental group additionally received oral guaiazulene tablets. Clinical symptom and sign scores, Visual Analog Scale (VAS) scores, skin lesion itching scores, comprehensive efficacy, treatment onset time, adverse reactions, and quality of life were monitored, recorded, and compared.

RESULTS

In the 2-week treatment period, patients in the experimental group showed significant improvement in skin symptoms and signs, with scores significantly lower than those in the control group (P < 0.05). After treatment, VAS and skin lesion itching scores in the experimental group were significantly reduced (P < 0.05), demonstrating a more pronounced therapeutic advantage compared to the control group (P < 0.05). Although the effective rate in the experimental group was as high as 86.96%, there was no significant advantage compared to the control group, and the difference in treatment efficacy was not significant (P > 0.05). The treatment onset time in the experimental group was significantly shorter than that in the control group (P < 0.05), and the incidence of adverse reactions was lower (P < 0.05). The quality of life in the experimental group improved significantly after treatment, with DLQI scores lower than those in the control group (P < 0.05).

CONCLUSION

Combined treatment with compound fluocinolone acetonide cream and guaiazulene demonstrates excellent efficacy and feasibility in the management of neurodermatitis. Compared to standard treatment alone, it yields superior clinical outcomes.

From traditional medicine to nanomedicine: potential of Ginkgo biloba extracts in treating inflammatory skin diseases

The use of plant extracts as a potential cure for various conditions has moved from traditional medicine to evidence-based medicine. Skin diseases have been addressed since time immemorial using plant extracts through observational and traditional knowledge and passed on through generations. With the advent of modern techniques, the molecular mechanisms of action of plant extracts/isolates are being deciphered with more precision, and more nanomedicine-based therapies are being studied to improve their therapeutic efficacy and stability. The leaves and seeds of Ginkgo biloba (G. biloba), an ancient medicinal tree species, have been used in Chinese herbal medicine for thousands of years. G. biloba extracts have been widely studied as a neuroprotective and anti-ischaemic drug for ischaemia-reperfusion injuries in the heart, lungs, brain, kidneys, and other organs. However, the use of G. biloba can be accompanied with side effects and drug interactions. Although, there is now a growing interest for its use in skincare, the mechanisms of action of the extract are not fully understood and vital aspects of G. biloba, such as its neuroprotective and angiogenic properties contributing to the treatment of inflammatory skin diseases and skin ageing, are yet to be investigated. This review critically discusses the mechanisms of action of different constituents of G. biloba extracts linked to their potential interference in the molecular mechanisms underlying the pathogenesis of inflammatory skin diseases. In addition to its ability to act on oxidative stress, G. biloba can regulate angiogenesis through its compounds such as ginkgetin or ginkgolide K, which either inhibit aberrant angiogenesis in eczema/psoriasis or increase microcirculation during skin ageing. G. biloba may also contribute to the control of pruritus in atopic dermatitis via a neuroprotective and anti-inflammatory mechanism by suppressing JAK2/STAT3 signalling pathways. This review also highlights nanomedicine strategies to decrease the side effects and enhance the efficacy of the extracts. Similar strategies have been successfully used for anticancer molecules in targeted chemotherapy and iron delivery in anaemia treatment.

Characterization of Inflammatory Mediators and Metabolome in Interstitial Fluid Collected with Dermal Open Flow Microperfusion before and at the End of Dupilumab Treatment in Atopic Dermatitis

Dupilumab is a monoclonal antibody approved for the treatment of atopic dermatitis (AD); however, its effects on molecular, cellular, and immunological levels remain to be elucidated. In this study, blood and dermal interstitial fluid (ISF) from nonlesional (NL) and lesional (L) skin were collected from eight patients with moderate to severe AD, before (visit 2-v2) and at the end of a 16-week treatment with dupilumab (visit 10-v10). Clinical treatment effect was demonstrated by significantly decreased AD severity scores at the end of treatment. At v10 versus v2, the percentages of CD4+ interleukin-producing cells showed a decreasing trend in ISF L and NL, unbound IL-4 levels in plasma were increased, IL-5 levels in ISF L reduced, and levels of factors involved in anti-inflammatory pathways and re-epithelization increased. At v2, ISF L showed that AD lesions might have altered amino acid pathways and lipid signaling compared to ISF NL. At v10, ISF L exhibited raised levels of long- and very-long-chain fatty acids and lipids compared to v2. Furthermore, dupilumab administration caused reduced expression of miR-155-5p and miR-378a-3p in ISF L. In conclusion, results from the present study provided novel knowledge by linking local immune and metabolic alterations to AD pathogenesis and treatment response.

Advances in GPCR-targeted drug development in dermatology

Achieving the efficacy and specificity of G-protein-coupled receptor (GPCR) targeting-drugs in the skin remains challenging. Understanding the molecular mechanism underlying GPCR dysfunction is crucial for developing targeted therapies. Recent advances in genetic, signal transduction, and structural studies have significantly improved our understanding of cutaneous GPCR functions in both normal and pathological states. In this review, we summarize recent discoveries of pathogenic GPCRs in dermal injuries, chronic inflammatory dermatoses, cutaneous malignancies, as well as the development of potent potential drugs. We also discuss targeting of cutaneous GPCR complexes via the transient receptor potential (TRP) channel and structure elucidation, which provide new opportunities for therapeutic targeting of GPCRs involved in skin disorders. These insights are expected to lead to more effective and specific treatments for various skin conditions.

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.

Immunoexpression of IL-33 in the different clinical aspects of canine atopic dermatitis

Canine atopic dermatitis (CAD) is a chronic and inflammatory skin condition with a multifaceted origin, involving genetic factors, skin barrier abnormalities, immune responses, and hypersensitivity to various allergens. Interleukin 33 (IL-33), released by keratinocytes upon cellular injury, plays a crucial role in atopic dermatitis pathogenesis by inducing Th2 lymphocyte-mediated immune responses. This study aimed to evaluate IL-33 expression in dogs with atopic dermatitis and compare it to a control group. Forty-nine dogs were included, with 39 having atopic dermatitis, subdivided into groups based on clinical characteristics, and ten in the control group. Lesion and pruritus scores were assessed, and incisional biopsies were analyzed for dermatopathological characteristics. IL-33 expression was evaluated using immunohistochemistry, the analyses were blinded, based on the measurement of immunostaining areas using Image Pro-Plus software, version 4.5, relying on a semi-automatic color segmentation method, where the tissue immunostaining area for each biomarker was artificially delimited and quantified. Statistically significant differences in IL-33 immunostaining were found among groups (P=0.0005). Lichenified dogs (group 4) exhibited higher immunostaining compared to erythema (group 3) (P=0.0006), alesional pruritus (group 2) (P=0.0261), and the control group (group 1) (P=0.0079). IL-33 immunostaining increased with lesion progression, strongly correlating with lesion scores (P<0.0001), particularly in patients with chronic lesions characterized by erythema and lichenification. These findings suggest IL-33's significant role in canine atopic dermatitis pathogenesis and its association with lesion and inflammation scores during the chronic phase. This suggests potential therapeutic interventions targeting IL-33 or its receptors, though further studies are needed to explore these possibilities.

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.

Induction of Semaphorin 3A by Resveratrol and Pinostilbene via Activation of the AHR-NRF2 Axis in Human Keratinocytes

Semaphorin 3A (SEMA3A), a nerve-repellent factor produced by keratinocytes, has an inhibitory effect on nerve extension to the epidermis. Epidermal innervation is involved in pruritus in inflammatory skin diseases such as atopic dermatitis (AD) and dry skin. We previously reported that tapinarof, a stilbene molecule, upregulates SEMA3A in human keratinocytes. We also showed that this mechanism is mediated via the aryl hydrocarbon receptor (AHR), a ligand-activated transcription factor, and the nuclear factor erythroid 2-related factor 2 (NRF2) axis. Since some stilbenes activate AHR and NRF2, we attempted to identify other stilbenes that upregulate SEMA3A. We analyzed normal human epidermal keratinocytes (NHEKs) treated with 11 types of stilbenes and examined SEMA3A expression. We found that resveratrol and pinostilbene, antioxidant polyphenols, upregulated SEMA3A and increased nuclear AHR and NRF2 expression. In addition, AHR knockdown by small interfering RNA (siRNA) transfection abolished the NRF2 nuclear expression. Furthermore, AHR and NRF2 knockdown by siRNA transfection abrogated resveratrol- and pinostilbene-induced SEMA3A upregulation. Finally, we confirmed that resveratrol and pinostilbene increased SEMA3A promoter activity through NRF2 binding using ChIP-qPCR analysis. These results suggest that resveratrol and pinostilbene upregulate SEMA3A via the AHR-NRF2 axis in human keratinocytes.

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.

The relationship and clinical significance of serum cytokine expression level and skin pruritus in patients with Hodgkin lymphoma and angioimmunoblastic T-cell lymphoma

Pruritus of lymphoma is commonly associated with both Hodgkin lymphoma (HL) and angioimmunoblastic T cell lymphoma (AITL) and critically affects the life quality of patient. Recent evidence suggests that the pruritogenic cytokines seem to play a significant role in the genesis of chronic. This study aims to investigate the cytokines associated with itching in lymphoma patients and provide the basis for potential therapeutic targets. Serum samples were collected from 60 lymphoma patients, including 47 with Hodgkin lymphoma (HL) and 13 with angioimmunoblastic T-cell lymphoma (AITL), serving as the observation group (lymphoma group, LP group, n = 60). Additionally, serum samples from 8 healthy donors (HD group, n = 8) were collected for comparison. Within the lymphoma group, patients were stratified into those with pruritus (LWP group, n = 30) and those without pruritus (LWOP group, n = 30) based on the presence of skin pruritus symptoms. Elevated levels of multiple cytokines were significantly observed in the LP group in comparison to the HD group (p < 0.01). Patients in LWP group exhibited higher serum levels of IL-31 (p < 0.001), IL-1β (P = 0.039), and IL-1α (P = 0.037) compared to LWOP group. Notably, serum IL-31 levels were higher in advanced AITL patients (stage IV) than in early AITL patients (stage I-Ⅲ, P < 0.05). In subgroup analysis, patients with pruritus in the AITL group exhibited higher serum levels of MIG and CTACK compared to HL group, whereas PDGF-BB levels were significantly lower (p < 0.05). Elevated serum levels of IL-31, IL-1β, and IL-1α are linked to lymphoma-associated pruritus. Differences in serum cytokine profiles between HL and AITL subgroups are also highlighted. These findings offer valuable insights for clinical intervention in managing lymphoma-related pruritus.

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.

T cells at the interface of neuroimmune communication

The immune system protects the host from infection and works to heal damaged tissue after infection or injury. There is increasing evidence that the immune system and the nervous system work in concert to achieve these goals. The sensory nervous system senses injury, infection, and inflammation, which results in a direct pain signal. Direct activation of peripheral sensory nerves can drive an inflammatory response in the skin. Immune cells express receptors for numerous transmitters released from sensory and autonomic nerves, which allows the nervous system to communicate directly with the immune system. This communication is bidirectional because immune cells can also produce neurotransmitters. Both innate and adaptive immune cells respond to neuronal signaling, but T cells appear to be at the helm of neuroimmune communication.

Nanotechnology strategies to address challenges in topical and cellular delivery of siRNAs in skin disease therapy

Gene therapy is one of the most advanced therapies in current medicine. In particular, interference RNA-based therapy by small interfering RNA (siRNA) has gained attention in recent years as it is a highly versatile, selective and specific therapy. In dermatological conditions, topical delivery of siRNA offers numerous therapeutic advantages, mainly by inhibiting the expression of target transcripts directly in the skin. However, crossing the stratum corneum and overcoming intracellular barriers is an inherent challenge. Substantial efforts by scientists have moved towards the use of multimodal and multifunctional nanoparticles to overcome these barriers and achieve greater bioavailability in their site of action, the cytoplasm. In this review the most innovative strategies based on nanoparticle and physical methods are presented, as well as the design principles and the main factors that contribute to the performance of these systems. This review also highlights the synergistic contributions of medicine, nanotechnology, and molecular biology to advancing translational research into siRNA-based therapeutics for skin diseases.

Cutaneous-immuno-neuro-endocrine (CINE) system: A complex enterprise transforming skin into a super organ

Skin is now emerging as a complex realm of three chief systems viz. immune system, nervous system, and endocrine system. The cells involved in their intricate crosstalk, namely native skin cells, intra-cutaneous immune cells and cutaneous sensory neurons have diverse origin and distinct functions. However, recent studies have explored their role beyond their pre-defined functional boundaries, such that the cells shun their traditional functions and adopt unconventional roles. For example, the native skin cells, apart from providing for basic structural framework of skin, also perform special immune functions and participate in extensive neuro-endocrine circuitry, which were traditionally designated as functions of cutaneous resident immune cells and sensory neurons respectively. At the cellular level, this unique collaboration is brought out by special molecules called neuromediators including neurotransmitters, neuropeptides, neurotrophins, neurohormones and cytokines/chemokines. While this intricate crosstalk is essential for maintaining cutaneous homeostasis, its disruption is seen in various cutaneous diseases. Recent study models have led to a paradigm shift in our understanding of pathophysiology of many such disorders. In this review, we have described in detail the interaction of immune cells with neurons and native skin cells, role of neuromediators, the endocrine aspect in skin and current understanding of cutaneous neuro-immuno-endocrine loop in one of the commonest skin diseases, psoriasis. An accurate knowledge of this unique crosstalk can prove crucial in understanding the pathophysiology of different skin diseases and allow for generation of targeted therapeutic modalities.

Epigenetic control of inflammation in Atopic Dermatitis

Atopic dermatitis (AD), also known as atopic eczema, is a common but also complex chronic, itchy skin condition with underlying inflammation of the skin. This skin ailment is prevalent worldwide and affects people of all ages, particularly children below five years of age. The itching and resulting rashes in AD patients are often the result of inflammatory signals, thus necessitating a closer look at the inflammation-regulating mechanisms for putative relief, care and therapy. Several chemical- as well as genetically-induced animal models have established the importance of targeting pro-inflammatory AD microenvironment. Epigenetic mechanisms are gaining attention towards a better understanding of the onset as well as the progression of inflammation. Several physiological processes with implications in pathophysiology of AD, such as, barrier dysfunction either due to reduced filaggrin / human β-defensins or altered microbiome, reprograming of Fc receptors with resulting overexpression of high affinity IgE receptors, elevated eosinophil numbers or the elevated IL-22 production by CD4 + T cells have underlying epigenetic mechanisms that include differential promoter methylation and/or regulation by non-coding RNAs. Reversing these epigenetic changes has been verified to reduce inflammatory burden through altered secretion of cytokines IL-6, IL-4, IL-13, IL-17, IL-22 etc, with benefit against AD progression in experimental models. A thorough understanding of epigenetic remodeling of inflammation in AD has the potential of opening avenues for novel diagnostic, prognostic and therapeutic options.

Dendritic cells under allergic condition enhance the activation of pruritogen-responsive neurons via inducing itch receptors in a co-culture study

BACKGROUND

Itch sensitization has been reported in patients with chronic allergic skin diseases and observed in a mouse model of allergic contact dermatitis (ACD). There is evidence suggesting that neuroimmune interactions may contribute to itch sensitization, as an increase in dendritic cells (DCs) within ganglia has been observed during allergic conditions. However, how DCs interact with sensory neurons in ganglia during allergic conditions is still not known. This study aims to investigate the role of DCs in dorsal root ganglion (DRG) under ACD conditions, specifically focusing on itch sensitization within the DRG. The tolylene-2,4-diisocyanate (TDI) mouse model for ACD and the co-culture model of DCs and DRG neurons was employed in this study.

RESULTS

We successfully induced ACD by TDI, as evidenced by the development of edema, elevated total serum IgE levels, and an observed itch reaction in TDI-sensitized mice. Calcium imaging and RT-qPCR analysis revealed that TDI-sensitized mice exhibited signs of peripheral sensitization, including a higher percentage of neurons responding to pruritogens and increased activation and expression of itch receptors in excised DRG of TDI-sensitized mice. Immunofluorescence and flow cytometric analysis displayed an increase of MHCII+ cells, which serves as a marker for DCs, within DRG during ACD. The co-culture study revealed that when DRG neurons were cultured with DCs, there was an increase in the number of neurons responsive to pruritogens and activation of itch receptors such as TRPA1, TRPV1, H1R, and TRPV4. In addition, the immunofluorescence and RT-qPCR study confirmed an upregulation of TRPV4.

CONCLUSIONS

Our findings indicate that there is an increase of MHCII+ cells and itch peripheral sensitization in DRG under TDI-induced ACD condition. It has been found that MHCII+ cells in DRG might contribute to the itch peripheral sensitization by activating itch receptors, as shown through co-culture studies between DRG neurons and DCs. Further studies are required to identify the specific mediator(s) responsible for peripheral sensitization induced by activated DCs.

Role of stress in skin diseases: A neuroendocrine-immune interaction view

Psychological stress is a crucial factor in the development of many skin diseases, and the stigma caused by skin disorders may further increase the psychological burden, forming a vicious cycle of psychological stress leading to skin diseases. Therefore, understanding the relationship between stress and skin diseases is necessary. The skin, as the vital interface with the external environment, possesses its own complex immune system, and the neuroendocrine system plays a central role in the stress response of the body. Stress-induced alterations in the immune system can also disrupt the delicate balance of immune cells and inflammatory mediators in the skin, leading to immune dysregulation and increased susceptibility to various skin diseases. Stress can also affect the skin barrier function, impair wound healing, and promote the release of pro-inflammatory cytokines, thereby exacerbating existing skin diseases such as psoriasis, atopic dermatitis, acne, and urticaria. In the present review, we explored the intricate relationship between stress and skin diseases from a neuroendocrine-immune interaction perspective. We explored the occurrence and development of skin diseases in the context of stress, the stress models for skin diseases, the impact of stress on skin function and diseases, and relevant epidemiological studies and clinical trials. Understanding the relationship between stress and skin diseases from a neuroendocrine-immune interaction perspective provides a comprehensive framework for targeted interventions and new insights into the diagnosis and treatment of skin diseases.

Emerging Role of the IL-36/IL-36R Axis in Multiple Inflammatory Skin Diseases

IL-36 is a most recent member of the IL-1 cytokine family, primarily expressed at barrier sites of the body such as the skin, lungs, and intestine. It plays a vital role in inflammation and is implicated in the development of various cutaneous; intestinal; and pulmonary disorders, including psoriasis, inflammatory bowel disease, and chronic obstructive pulmonary disease. IL-36 comprises 4 isoforms: the proinflammatory IL-36α, IL-36β, and IL-36γ and the anti-inflammatory IL-36R antagonist. An imbalance between proinflammatory and anti-inflammatory IL-36 isoforms can contribute to the inflammatory fate of cells and tissues. IL-36 cytokines signal through an IL-36R heterodimer mediating their function through canonical signaling cacade, including the NF-B pathway. Prominent for its role in psoriasis, IL-36 has recently been associated with disease mechanisms in atopic dermatitis, hidradenitis suppurativa, neutrophilic dermatoses, autoimmune blistering disease, and Netherton syndrome. The major cutaneous source of IL-36 cytokines is keratinocytes, pointing to its role in the communication between the epidermis, innate (neutrophils, dendritic cells) immune system, and adaptive (T helper [Th]1 cells, Th17) immune system. Thus, cutaneous IL-36 signaling is crucial for the immunopathological outcome of various skin diseases. Consequently, the IL-36/IL-36R axis has recently been recognized as a promising drug target for the treatment of inflammatory disorders beyond psoriasis. This review summarizes the current update on IL-36 cytokines in inflammatory skin diseases.

Cutaneous Components Leading to Pruritus, Pain, and Neurosensitivity in Atopic Dermatitis: A Narrative Review

Atopic dermatitis (AD) is a chronic, relapsing immunoinflammatory skin condition characterized by sensations such as pruritis, pain, and neuronal hypersensitivity. The mechanisms underlying these sensations are multifactorial and involve complex crosstalk among several cutaneous components. This review explores the role these components play in the pathophysiology of atopic dermatitis. In the skin intercellular spaces, sensory nerves interact with keratinocytes and immune cells via myriad mediators and receptors. These interactions generate action potentials that transmit pruritis and pain signals from the peripheral nervous system to the brain. Keratinocytes, the most abundant cell type in the epidermis, are key effector cells, triggering crosstalk with immune cells and sensory neurons to elicit pruritis, pain, and inflammation. Filaggrin expression by keratinocytes is reduced in atopic dermatitis, causing a weakened skin barrier and elevated skin pH. Fibroblasts are the main cell type in the dermis and, in atopic dermatitis, appear to reduce keratinocyte differentiation, further weakening the skin barrier. Fibroblasts and mast cells promote inflammation while dermal dendritic cells appear to attenuate inflammation. Inflammatory cytokines and chemokines play a major role in AD pathogenesis. Type 2 immune responses typically generate pruritis, and the type 1 and type 3 responses generate pain. Type 2 responses and increased skin pH contribute to barrier dysfunction and promote dysbiosis of the skin microbiome, causing the proliferation of Staphyloccocus aureus. In conclusion, understanding the dynamic interactions between cutaneous components in AD could drive the development of therapies to improve the quality of life for patients with AD.

CLA+ memory T cells in atopic dermatitis

Circulating skin-homing cutaneous lymphocyte-associated antigen (CLA)+ T cells constitute a small subset of human memory T cells involved in several aspects of atopic dermatitis: Staphylococcus aureus related mechanisms, the abnormal Th2 immune response, biomarkers, clinical aspects of the patients, pruritus, and the mechanism of action of targeted therapies. Superantigens, IL-13, IL-31, pruritus, CCL17 and early effects on dupilumab-treated patients have in common that they are associated with the CLA+ T cell mechanisms in atopic dermatitis patients. The function of CLA+ T cells corresponds with the role of T cells belonging to the skin-associated lymphoid tissue and could be a reason why they reflect different mechanisms of atopic dermatitis and many other T cell mediated skin diseases. The goal of this review is to gather all this translational information of atopic dermatitis pathology.

Neuroimmune communication in allergic rhinitis

The prevalence rate of allergic rhinitis (AR) is high worldwide. The inhalation of allergens induces AR, which is an immunoglobulin E-mediated and type 2 inflammation-driven disease. Recently, the role of neuroimmune communication in AR pathogenesis has piqued the interest of the scientific community. Various neuropeptides, such as substance P (SP), vasoactive intestinal peptide (VIP), calcitonin gene-related peptide (CGRP), nerve growth factor (NGF), and neuromedin U (NMU), released via "axon reflexes" or "central sensitization" exert regulatory effects on immune cells to elicit "neurogenic inflammation," which contributes to nasal hyperresponsiveness (NHR) in AR. Additionally, neuropeptides can be produced in immune cells. The frequent colocalization of immune and neuronal cells at certain anatomical regions promotes the establishment of neuroimmune cell units, such as nerve-mast cells, nerve-type 2 innate lymphoid cells (ILC2s), nerve-eosinophils and nerve-basophils units. Receptors expressed both on immune cells and neurons, such as TRPV1, TRPA1, and Mas-related G protein-coupled receptor X2 (MRGPRX2) mediate AR pathogenesis. This review focused on elucidating the mechanisms underlying neuroimmune communication in AR.

Xanthotoxol relieves itch in mice via suppressing spinal GRP/GRPR signaling

Although pruritus, commonly known as itch, is a common and debilitating symptom associated with various skin conditions, there is a lack of effective therapies available. Xanthotoxol (XAN), a biologically active linear furocoumarin, shows potential in the treatment of various neurological disorders. In this study, we discovered that administering XAN either through intraperitoneal or intrathecal injections effectively reduced scratching behavior induced by compound 48/80 or chloroquine. Importantly, XAN also substantially alleviates chronic itch in dry skin and allergic contact dermatitis mice. Substantial progress has highlighted the crucial role of gastrin-releasing peptide (GRP)-gastrin-releasing peptide receptor (GRPR) signaling in the dorsal spinal cord in transmitting various types of itch. Our behavior tests revealed that XAN significantly alleviated scratching behaviors induced by intrathecal administration of GRP or GRPR agonist bombesin. Furthermore, XAN reduced the activation of neurons in the spinal cord caused by intrathecal administration of GRP in mice. Moreover, XAN attenuates the activation of spinal GRPR-positive neurons in itchy mice. These findings suggest that XAN mitigates itch in mice by suppressing spinal GRP/GRPR signaling, thereby establishing XAN as a promising therapeutic option for treating pruritus.