Current Clinical Options for the Management of Itch in Atopic Dermatitis

Type 2 Inflammation and Its Role in Dermatologic Diseases

Atopic dermatitis, prurigo nodularis, and chronic spontaneous urticaria are immune-mediated, inflammatory skin conditions characterized by intense itch and disease-specific skin lesions. Despite their different clinical presentations, the three diseases are unified by an aberrant type 2 immune response involving type 2 cytokines, immune cells, and sensory nerves that may underlie their shared clinical manifestations of inflammation and pruritus. The chronic nature of these conditions is associated with significant impairment in patients' quality of life and psychological disorders, such as anxiety and depression. This article reviews type 2 inflammation and its role in atopic dermatitis, prurigo nodularis, and chronic spontaneous urticaria, focusing on the pathophysiologic drivers of type 2 inflammation in each dermatologic condition. Understanding the shared immune mechanisms that underlie these seemingly distinct skin diseases and other concomitant inflammatory conditions is critical for applying therapeutic interventions targeting the type 2 immune pathway.

Novel drug delivery systems in topical treatment of atopic dermatitis

Atopic dermatitis (AD), also known as eczema, is a chronic skin condition, affecting all ages, characterized by inflammation, itching, dryness, and redness, which can severely impact quality of life. Based on clinical features and symptoms, AD is of several types like contact dermatitis, dyshidrotic eczema, neurodermatitis, seborrheic dermatitis, stasis dermatitis, and nummular eczema. Its pathophysiology involves genetic, environmental, and immunological factors, leading to skin barrier dysfunction. Current treatments for AD involve a combination of pharmacological and non-pharmacological strategies tailored to individual needs. Management includes topical therapies of corticosteroids, calcineurin inhibitors, phosphodiesterase inhibitors, and janus kinase inhibitors in the form of gels, creams, ointments, and lotions. Systemic treatments like immunosuppressants and biologics are employed for severe cases. Long term and regular use of current treatments can lead to numerous adverse effects like skin thinning, atrophy, burning sensation, emergence of skin lymphomas, tolerance, and systemic side effects. Emerging topical nanoformulations, such as lipid-based nanoparticles, polymeric carriers, liposomes, cubosomes, ethosomes, nanoemulsions enhance drug delivery, improve therapeutic outcomes, and reduce toxicity, making them promising options for AD treatment. Clinical trials of nanoformulations for AD show significant improvements in treatment efficacy and skin absorption compared to conventional therapies. However, nanomedicine faces challenges in terms of inadequate evaluation studies and formulation instability, requiring stringent regulatory compliance and a thorough preclinical and clinical data investigation. This review aims to describe types of AD, its pathophysiology and current treatments and their challenges. The review further focuses on emerging trends of various nanoformulations for treatment of AD.

Practical guide for the diagnosis and treatment of localized and generalized cutaneous pruritus (chronic itch with no underlying pruritic dermatosis)

Itch, also known as pruritus, is one of the most prevalent symptoms observed in dermatological practices. Itch frequently arises from primary pruritic dermatoses, although it may also manifest in the absence of a primary pruritic skin rash. The latter itchy condition is referred to as "cutaneous pruritus" in the Japanese guidelines published in 2020. Cutaneous pruritus can be classified into two categories based on its distribution: localized cutaneous pruritus and generalized cutaneous pruritus. Localized cutaneous pruritus is indicative of a neuropathic cause, whereas generalized cutaneous pruritus suggests underlying systemic disease(s), drug-induced itch, psychogenic itch (also known as functional itch disorder), or chronic pruritus of unknown origin (CPUO). Systemic diseases associated with cutaneous pruritus include disorders of iron metabolism, chronic kidney disease, chronic liver disease (especially cholestasis), endocrine/metabolic diseases, hematological disorders, and malignant solid tumors. CPUO is a term used to describe chronic itch that is often generalized and for which no underlying cause can be identified despite a comprehensive and careful diagnostic workup. A variety of treatment approaches are available for cutaneous pruritus, including device-based physical therapies (such as phototherapy) and medications that act on the itch-perception processing pathway from the skin, peripheral sensory nerves, the spinal cord, to the brain. This review presents an overview of the current knowledge regarding cutaneous pruritus, from its underlying pathophysiologic mechanisms to the diagnostic procedures and treatment approaches that are currently available.

The role of Interleukin-21 (IL-21) in allergic disorders: Biological insights and regulatory mechanisms

In recent decades, allergic diseases subsequent from an IgE-mediated response to specific allergens have become a progressively public chronic disease worldwide. They have shaped an important medical and socio-economic burden. A significant proportion of allergic disorders are branded via a form 2 immune response relating Th2 cells, type 2 natural lymphoid cells, mast cells and eosinophils. Interleukin-21 (IL-21) is a participant of the type-I cytokine family manufactured through numerous subsets of stimulated CD4+ T cells and uses controlling properties on a diversity of immune cells. Increasingly, experimental sign suggests a character for IL-21 in the pathogenesis of numerous allergic disorders. The purpose of this review is to discuss the biological properties of IL-21 and to summaries current developments in its role in the regulation of allergic disorders.

Current and emerging drugs for the treatment of pruritus: an update of the literature

INTRODUCTION

Pruritus, particularly in its chronic form, often imposes significant suffering and reductions in patients' quality of life. The pathophysiology of itch is varied depending on disease context, creating opportunities for unique drug development and multimodal therapy.

AREAS COVERED

The purpose of this article is to provide an update of the literature regarding current and emerging therapeutics in itch. We review the multitudes of drug targets available and corresponding drugs that have shown efficacy in clinical trials, with a particular emphasis on phase 2 and 3 trials and beyond. Broadly, these targets include therapies directed against type 2 inflammation (i.e. Th2 cytokines, JAK/STAT, lipid mediators, T-cell mediators, and other enzymes and receptors) and neural receptors and targets (i.e. PARs, TRP channels, opioid receptors, MRGPRs, GABA receptors, and cannabinoid receptors).

EXPERT OPINION

Therapeutics for itch are emerging at a remarkable pace, and we are entering an era with more and more specialized therapies. Increasingly, these treatments are able to relieve itch beyond their effect on inflammation by directly targeting the neurosensory system.

Kappa opioid agonists in the treatment of itch: just scratching the surface?

Chronic pruritus is a debilitating condition affecting 23-44 million Americans. Recently, kappa opioid agonists (KOAs) have emerged as a novel class of potent antipruritic agents. In 2021, the Food and Drug Administration approved difelikefalin (Korsuva) for the treatment of moderate-to-severe pruritus associated with chronic kidney disease in adults undergoing hemodialysis. Difelikefalin is a potent, peripherally restricted KOA that is intravenously available. Although promising, difelikefalin is currently available as an intravenous composition only, limiting the scope of use. Oral formulations of difelikefalin did not meet the primary endpoint criteria in recent phase 2 clinical trials; however, additional clinical studies are ongoing. The future for KOAs in the treatment of pruritus is encouraging. Orally active pathway-biased KOAs, such as triazole 1.1, may serve as viable alternatives with broader applications. Extended-release compositions, such as the TP-2021 ProNeura subdermal implant, may circumvent the pharmacokinetic issues associated with peptide-based KOAs. Lastly, dual-acting kappa opioid receptor agonist/mu opioid receptor antagonists are orally bioavailable and may be useful in the treatment of various forms of chronic itch. In this review, we summarize the results of KOAs in clinical and preclinical trials and discuss future directions of drug development.

A phase IV, randomised, double-blind, controlled, parallel group trial to evaluate the effectiveness and safety of Balneum Plus versus emollient in the treatment of chronic kidney disease-associated pruritus in haemodialysis patients

Background

Chronic kidney disease-associated pruritus (CKD-aP) is a common, distressing complaint in patients with advanced renal disease that is frequently overlooked. Treatment is often unsatisfactory. Balneum Plus (Almirall, Barcelona, Spain) is a cream containing 3% lauromacrogols and 5% urea, commonly used to treat atopic dermatitis. It has not been studied in CKD-aP to date.

Methods

Adult haemodialysis patients were randomised 1:1 to apply Balneum Plus or E45 (Reckitt Beckiser, Slough, UK) to compare the active ingredients of lauromacrogol and urea with a control cream. Itch was defined as three episodes of itching during the last 2 weeks, appearing a few times a day, lasting a few minutes and troubling the patient [1]. Patients with other causes of itch, e.g. eczema and liver disease, were excluded. The primary outcome was a reduction in itch as measured by the visual analogue scale (VAS) score at 4 weeks and analysed using an analysis of covariance approach.

Results

A total of 314 patients were screened and 58 patients were randomised, 29 in each group. Three patients dropped out in each group. The median baseline VAS scores were 6.5 [interquartile range (IQR) 4.4-8.0] in the Balneum Plus group and 6.3 (IQR 5.1-7.3) in the E45 group. After 4 weeks, VAS scores decreased to 2.6 (IQR 0.9-4.5) and 2.0 (IQR 0.5-4.8) in the Balneum Plus and E45 groups respectively (P = 0.64 for the difference). Using a validated questionnaire to assess secondary outcomes, we found that the Balneum Plus group had longer itching episodes, more difficulty staying asleep and itching was more annoying than in the E45 group. There was no significant difference in adverse events between the two groups. One patient reported inflamed spots on the abdominal skin in the Balneum Plus group.

Conclusion

This is the first randomised controlled study of two different emollients for the treatment of CKD-aP and is a negative study. We found no significant difference in itch scores between Balneum Plus and E45.

Fc Epsilon RI-Neuroimmune Interplay in Pruritus Triggered by Particulate Matter in Atopic Dermatitis Patients

Atopic dermatitis (AD) is the most common chronic relapsing neuroinflammatory skin disease that is characterized by a complex and multifactorial pathophysiology. It reflects a profound interplay between genetic and environmental factors, and a recently disclosed neuroimmune dysregulation that drives skin barrier disruption, pruritus, and microbial imbalance. In terms of the key external environmental players that impact AD, air quality and itch severity linkage have been thoroughly researched. The impact of ambient air pollutants including particulate matter (PM) and AD pruritic exacerbation has been recorded despite reductions in air pollution levels in in developed countries. The developing countries have, on the contrary, experienced significant urbanization and industrialization with limited environmental protection standards in the past decades. This unprecedented construction, petrochemical industry utilization, and increment in population counts has been paired with consistent exposure to outdoor PM. This may present a key cause of AD pruritic exacerbation supported by the fact that AD prevalence has intensified globally in the past 50 years, indicating that environmental exposure may act as a trigger that could flare up itch in vulnerable persons. At the molecular level, the impact of PM on severe pruritus in AD could be interpreted by the toxic effects on the complex neuroimmune pathways that govern this disease. AD has been recently viewed as a manifestation of the disruption of both the immune and neurological systems. In light of these facts, this current review aims to introduce the basic concepts of itch sensory circuits in the neuroimmune system. In addition, it describes the impact of PM on the potential neuroimmune pathways in AD pathogenesis with a special focus on the Fc Epsilon RI pathway. Finally, the review proposes potential treatment lines that could be targeted to alleviate pruritus based on immune mediators involved in the Fc Epsilon signaling map.

IL-31-generating network in atopic dermatitis comprising macrophages, basophils, thymic stromal lymphopoietin, and periostin

BACKGROUND

IL-31 is a type 2 cytokine involved in the itch sensation in atopic dermatitis (AD). The cellular origins of IL-31 are generally considered to be T_H2 cells. Macrophages have also been implicated as cellular sources of IL-31.

OBJECTIVE

We sought to determine the expression of IL-31 by macrophages and to elucidate the productive mechanisms and contributions to itch in AD skin lesions.

METHODS

Expression of IL-31 by macrophages, expressions of thymic stromal lymphopoietin (TSLP) and periostin, and presence of infiltrating basophils in human AD lesions were examined through immunofluorescent staining, and correlations were assessed. Furthermore, mechanisms of inducing IL-31-expressing macrophages were analyzed in an MC903-induced murine model for AD in vivo and in mouse peritoneal macrophages ex vivo.

RESULTS

A significant population of IL-31⁺ cells in human AD lesions was that of CD68⁺ cells expressing CD163, an M2 macrophage marker. The number of IL-31⁺/CD68⁺ cells correlated with epidermal TSLP, dermal periostin, and the number of dermal-infiltrating basophils. In the MC903-induced murine AD model, significant scratching behaviors with enhanced expressions of TSLP and periostin were observed, accompanied by massive infiltration of basophils and IL-31⁺/MOMA-2⁺/Arg-1⁺ cells. Blockade of IL-31 signaling with anti-IL-31RA antibody or direct depletion of macrophages by clodronate resulted in attenuation of scratching behaviors. To effectively reduce lesional IL-31⁺ macrophages and itch, basophil depletion was essential in combination with TSLP- and periostin-signal blocking. Murine peritoneal macrophages produced IL-31 when stimulated with TSLP, periostin, and basophils.

CONCLUSIONS

A network comprising IL-31-expressing macrophages, TSLP, periostin, and basophils plays a significant role in AD itch.

An evaluation of abrocitinib for moderate-to-severe atopic dermatitis

INTRODUCTION

Atopic dermatitis (AD) is a common itchy inflammatory skin condition that affects many individuals. For many years, the landscape of AD treatment remained unchanged; however, there has been developing therapies that directly target the underlying immunological mechanism of AD. Janus kinase (JAK) inhibitors are small molecules that have shown anti-inflammatory and anti-itch effects in AD. Recently, abrocitinib, an oral JAK 1 inhibitor, was approved by the Food and Drug Administration for atopic dermatitis.

AREAS COVERED

By downregulating the immune cascade, abrocitinib has demonstrated the ability to curb symptoms of AD, including rapidly reducing pruritus in 2-3 days, and is safe and well-tolerated overall despite a low increased risk in infection. The data discussed was obtained from a comprehensive literature review utilizing PubMed.

EXPERT OPINION

Abrocitinib has strong efficacy, likely due to its broader mechanism of action provided by the inhibition of key regulatory molecule, JAK. Results have demonstrated that it is more efficacious at curbing symptoms of AD than dupilumab, the current treatment of choice for refractory, moderate-to-severe AD. While abrocitinib provides a great alternative treatment, particularly for non-responders and AD subtypes, it also demonstrates a stronger side effect profile that must be considered.

Release of Cervical Muscle Tension Improves Psychological Stress and Symptoms of Moderate-to-Severe Atopic Dermatitis: a Case Series with 20 Patients

Introduction

Atopic dermatitis (AD) is a chronic relapsing inflammatory skin disease that is triggered by intense pruritus, impaired skin barrier function, and immune responses to allergenic substances. Break-through therapies for AD include molecular-targeted drugs and the effective management of severe symptoms of AD. However, patients with clinical improvements may continue scratching owing to the influence of psychological stress, which might lead to quick relapses of stressors and subsequent intensive scratching. New drugs may be ineffective because of such scratching behavior caused by stressors. Therefore, it may be useful to consider adjunctive treatment options that focus on external stressors as triggers of deterioration of AD. We hypothesized that improvement of psychological stress by relieving cervical muscle tension would reduce pruritus and atopic symptoms.

Methods

Overall, 21 patients with moderate-to-severe AD were treated to relieve cervical muscular tension using Spineliner SA201, which assists in osteopathic manipulative treatment. We assessed the subjective and objective symptoms of AD, cervical muscle tension, which was evaluated using cervical range of motion (ROM), and psychological burden. Only moisturizers were applied topically during the study period, and no topical corticosteroid therapy was used.

Results

Twenty patients who completed the treatment demonstrated improvement in the symptoms of AD: changes on the visual analog scale (VAS) for pruritus were −44.2%, Eczema Area and Severity Index (EASI) was −67.9%, thymus and activation-regulated chemokine (TARC) was −56.2%, Hospital Anxiety and Depression Scale (HADS) was −27.2%, sleep disturbance was −49.7%, and Dermatology Life Quality Index (DLQI) was −46.7%. Additionally, the cervical muscle tension improved significantly: changes in cervical ROM were 14.7%.

Conclusions

Release of cervical muscle tension may improve psychological stress and have an effect on moderate-to-severe AD.

Atopic dermatitis is a chronic relapsing inflammatory skin disease triggered by intense pruritus, impaired skin barrier function, and immune responses. Standard dermatological therapies for patients with atopic dermatitis include topical glucocorticoid treatments. In some cases, scratching and inflammation could not be adequately controlled, a relapse could not be prevented after remission, and their efficacy is limited. Break-through therapies for atopic dermatitis include new molecular biological drugs, which have demonstrated significantly improved and effective management of severe atopic symptoms. However, patients with clinical improvements may continue scratching owing to psychological stress, which might lead to quick relapses of stressors and subsequent intensive scratching. New drugs may be ineffective owing to such scratching behavior caused by stressors. Therefore, it may be useful to consider adjunctive treatment options focusing on external stressors as triggers for worsening atopic dermatitis. We hypothesized that improvement of psychological stress by relieving cervical muscle tension would reduce pruritus and atopic symptoms. Overall, 21 patients with moderate-to-severe atopic dermatitis were treated to relieve cervical muscular tension using Spineliner SA201, which assists in osteopathic manipulative treatment. We assessed the subjective and objective atopic symptoms, cervical muscle tension, and psychological burden. Only moisturizers were applied topically during the study period, and no topical corticosteroid therapy was used. Twenty patients completed the treatment, atopic symptoms improved significantly, cervical muscular tension improved, and the psychological burden decreased with the treatment. Release of cervical muscle tension may improve psychological stress and affect moderate-to-severe atopic dermatitis.

D-galactose Intake Alleviates Atopic Dermatitis in Mice by Modulating Intestinal Microbiota

Atopic dermatitis (AD) is one of the most prevalent, chronic and persistent inflammatory skin diseases closely associated with intestinal microbiota. To evaluate the effect of D-galactose intake on AD, we orally administered D-galactose to BALB/c mice whose ears and skin were treated with 2,4-dinitrochlorobenzene (DNCB). D-galactose alleviated DNCB-induced AD-like phenotypes such as redness, scaling/dryness and excoriation. Ear thickness was also decreased by D-galactose administration. Histopathological analysis revealed decreased epidermal thickening, infiltration of immune cells, especially mast cells, in the dermis. Total levels of serum IgE representing the immunological response of AD were decreased by D-galactose administration. Microbiota analysis showed that D-galactose administration restored gut microbiota profiles, which were altered in AD mice, characterized by increased abundance of Bacteroidetes and decreased abundance of Firmicutes. The increased abundance of Bacteroides and the decreased abundance of Prevotella and Ruminococcus were reversed by D-galactose treatment, following improvement of AD. Our results suggest the possible use of D-galactose as a prebiotic to alleviate AD by altering gut microbiota.

Managing Atopic Dermatitis with Lebrikizumab - The Evidence to Date

Atopic dermatitis is a prevalent, inflammatory skin disease that presents with an eczematous, itchy rash. As of late, there have been many emerging monoclonal antibody inhibitor and small molecule therapies that have changed the course of eczema treatment. One of the treatments in the pipeline for atopic dermatitis is interleukin 13 monoclonal antibody inhibitor, lebrikizumab. As interleukin 13 has been identified as a pro-inflammatory cytokine in the immunological cascade of eczema, it is thought that lebrikizumab can be a great treatment choice for patients with atopic dermatitis. Lebrikizumab is currently being investigated in several studies. Thus far, lebrikizumab for the treatment of eczema has been found to be efficacious; in particular, a rapid response of pruritus improvement has been demonstrated in as early as 2 days. Additionally, it is well tolerated and has an acceptable safety profile, with reports suggesting that are decreased risks of infection when compared to dupilumab. In this review, we aim to summarize the current understanding of lebrikizumab in terms of the mechanism of action, preclinical pharmacology, pharmacokinetics and metabolism, efficacy and safety, and drug indications.

Bruton's tyrosine kinase inhibition-An emerging therapeutic strategy in immune-mediated dermatological conditions

Bruton's tyrosine kinase (BTK), a member of the Tec kinase family, is critically involved in a range of immunological pathways. The clinical application of BTK inhibitors for B‐cell malignancies has proven successful, and there is strong rationale for the potential benefits of BTK inhibitors in some autoimmune and allergic conditions, including immune‐mediated dermatological diseases. However, the established risk‐to‐benefit profile of “first‐generation” BTK inhibitors cannot be extrapolated to these emerging, non‐oncological, indications. “Next‐generation” BTK inhibitors such as remibrutinib and fenebrutinib entered clinical development for chronic spontaneous urticaria (CSU); rilzabrutinib and tirabrutinib are being studied as potential treatments for pemphigus. Promising data from early‐phase clinical trials in CSU suggest potential for these agents to achieve strong pathway inhibition, which may translate into measurable clinical benefits, as well as other effects such as the disruption of autoantibody production. BTK inhibitors may help to overcome some of the shortcomings of monoclonal antibody treatments for immune‐mediated dermatological conditions such as CSU, pemphigus, and systemic lupus erythematosus. In addition, the use of BTK inhibitors may improve understanding of the pathophysiological roles of mast cells, basophils, and B cells in such conditions.