Atopic dermatitis: Is innate or adaptive immunity in control? A clinical perspective

Inhibition of macrophage MAPK/NF-κB pathway and Th2 axis by mangiferin ameliorates MC903-induced atopic dermatitis

Available online Atopic dermatitis (AD) is a chronic, persistent inflammatory skin disease characterized by eczema-like lesions and itching. Although topical steroids have been reported for treating AD, they are associated with adverse effects. Thus, safer medications are needed for those who cannot tolerate these agents for long periods. Mangiferin (MAN) is a flavonoid widely found in many herbs, with significant anti-inflammatory and immunomodulatory activities. However, the potential modulatory effects and mechanisms of MAN in treating Th2 inflammation in AD are unknown. In the present study, we reported that MAN could reduce inflammatory cell infiltration and scratching at the lesion site by decreasing MC903-induced levels of Th2-type cytokines, Histamine, thymic stromal lymphopoietin, Leukotriene B4, and immunoglobulin E. The mechanism may be related to reductions in MAPK and NF-κB-associated protein phosphorylation by macrophages. The results suggested that MAN may be a promising therapeutic agent for AD.

Association Between Atopic Dermatitis and Aging: Clinical Observations and Underlying Mechanisms

As one of the most prevalent chronic inflammatory skin diseases, atopic dermatitis (AD) increasingly affects the aging population. Amid the ongoing global aging trend, it's essential to recognize the intricate relationship between AD and aging. This paper reviews existing knowledge, summarizing clinical observations of associations between AD and aging-related diseases in various systems, including endocrine, cardiovascular, and neurological. Additionally, it discusses major theories explaining the correlation, encompassing skin-mucosal barriers, systemic inflammation and stress, genes, signal transduction, and environmental and behavioral factors. The association between AD and aging holds significant importance, both in population and basic perspectives. While further research is warranted, this paper aims to inspire deeper exploration of inflammation/allergy-aging dynamics and the timely management of elderly patients with AD.

Emerging drugs for the treatment of atopic dermatitis: a focus on phase 2 and phase 3 trials

INTRODUCTION

Atopic dermatitis (AD) is an inflammatory skin condition that affects millions of pediatric and adult patients with well-studied impact on morbidity and quality of life. Management occurs in a stepwise fashion beginning with preventative measures before immunomodulators are introduced. However, challenges remain in treatment of moderate-to-severe atopic dermatitis that is refractory to first- and second-line treatments and there are only few topical anti-inflammatory options, especially for pediatric patients.

AREAS COVERED

New medications are required to address these gaps as lesions may persist despite treatment or patients may discontinue treatment due to actual or anticipated adverse effects of mainstay medications. Emerging research into the pathophysiology of AD and the immune system at large has provided opportunities for novel interventions aimed at stopping AD mechanisms at new checkpoints. Clinical trials for 36 agents currently in phase 2 or phase 3 are evaluated with particular focus on the studies for, B244, CBP-201, tapinarof, lebrikizumab, nemolizumab, amlitelimab, and rocatinlimab as they explore novel pathways and have some of the most promising results.

EXPERT OPINION

These clinical trials contribute to the evolution of AD treatment toward greater precision based on salient pathways with a particular focus on moderate-to-severe AD to enhance efficacy and minimize adverse effects.

Atopic dermatitis (eczema) guidelines: 2023 American Academy of Allergy, Asthma and Immunology/American College of Allergy, Asthma and Immunology Joint Task Force on Practice Parameters GRADE- and Institute of Medicine-based recommendations

BACKGROUND

Guidance addressing atopic dermatitis (AD) management, last issued in 2012 by the American Academy of Allergy, Asthma and Immunology/American College of Allergy, Asthma and Immunology Joint Task Force, requires updating as a result of new treatments and improved guideline and evidence synthesis methodology.

OBJECTIVE

To produce evidence-based guidelines that support patients, clinicians, and other decision-makers in the optimal treatment of AD.

METHODS

A multidisciplinary guideline panel consisting of patients and caregivers, AD experts (dermatology and allergy/immunology), primary care practitioners (family medicine, pediatrics, internal medicine), and allied health professionals (psychology, pharmacy, nursing) convened, prioritized equity, diversity, and inclusiveness, and implemented management strategies to minimize influence of conflicts of interest. The Evidence in Allergy Group supported guideline development by performing systematic evidence reviews, facilitating guideline processes, and holding focus groups with patient and family partners. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach informed rating the certainty of evidence and strength of recommendations. Evidence-to-decision frameworks, subjected to public comment, translated evidence to recommendations using trustworthy guideline principles.

RESULTS

The panel agreed on 25 recommendations to gain and maintain control of AD for patients with mild, moderate, and severe AD. The eAppendix provides practical information and implementation considerations in 1-2 page patient-friendly handouts.

CONCLUSION

These evidence-based recommendations address optimal use of (1) topical treatments (barrier moisturization devices, corticosteroids, calcineurin inhibitors, PDE4 inhibitors [crisaborole], topical JAK inhibitors, occlusive [wet wrap] therapy, adjunctive antimicrobials, application frequency, maintenance therapy), (2) dilute bleach baths, (3) dietary avoidance/elimination, (4) allergen immunotherapy, and (5) systemic treatments (biologics/monoclonal antibodies, small molecule immunosuppressants [cyclosporine, methotrexate, azathioprine, mycophenolate, JAK inhibitors], and systemic corticosteroids) and UV phototherapy (light therapy).

Anti-inflammatory effects of neuregulin-1 in HaCaT keratinocytes and atopic dermatitis-like mice stimulated with Der p 38

Neuregulin (NRG)-1 plays fundamental roles in several organ systems after binding to its receptors, ErbB2 and ErbB4. This study examines the role of NRG-1 in atopic dermatitis (AD), a chronic skin disease that causes dryness, pruritus, and inflammation. In mice administered Der p 38, the skin presents AD-like symptoms including filaggrin downregulation and infiltration of neutrophils and eosinophils. Noticeably, there is an increased expression of NRG-1, ErbB2, and ErbB4 in the skin. Upregulation of these proteins is significantly correlated to the clinical skin severity score. In human keratinocyte HaCaT cells, exposure to Der p 38 decreased filaggrin expression, and NRG-1 alone had no effect on the expression. However, co-treatment of Der p 38 with NRG-1 enhanced the filaggrin expression decreased by Der p 38. Pre-treatment with AG879 (an ErbB2 inhibitor) or ErbB4 siRNA blocked the recovery of filaggrin expression in the cells after co-treatment with Der p 38 and NRG-1. Der p 38 treatment enhanced the secretion of interleukin-6 (IL-6), IL-8, and monocyte chemoattractant protein-1 (MCP-1). Co-treatment of Der p 38 with NRG-1 lowered the cytokine secretion increased by Der p 38, although NRG-1 alone was not effective on cytokine alteration. Neutrophil apoptosis was not altered by NRG-1 or supernatants of cells treated with NRG-1, but the cell supernatants co-treated with Der p 38 and NRG-1 blocked the anti-apoptotic effects of Der p 38-treated supernatants on neutrophils, which was involved in the activation of caspase 9 and caspase 3. Taken together, we determined that NRG-1 has anti-inflammatory effects in AD triggered by Der p 38. These results will pave the way to understanding the functions of NRG-1 and in the future development of AD treatment.

An AhR-Ovol1-Id1 regulatory axis in keratinocytes promotes skin homeostasis against atopic dermatitis

Skin is our outer permeability and immune defense barrier against myriad external assaults. Aryl hydrocarbon receptor (AhR) senses environmental factors and regulates barrier robustness and immune homeostasis. AhR agonist is in clinical trial for atopic dermatitis (AD) treatment, but the underlying mechanism of action remains ill-defined. Here we report OVOL1/Ovol1 as a conserved and direct transcriptional target of AhR in epidermal keratinocytes. We show that OVOL1/Ovol1 impacts AhR regulation of keratinocyte gene expression, and Ovol1 deletion in keratinocytes hampers AhR's barrier promotion function and worsens AD-like inflammation. Mechanistically, we identify Ovol1's direct downstream targets genome-wide, and provide in vivo evidence for Id1's critical role in barrier maintenance and disease suppression. Furthermore, our findings reveal an IL-1/dermal γδT cell axis exacerbating both type 2 and type 3 immune responses downstream of barrier perturbation in Ovol1 -deficient AD skin. Finally, we present data suggesting the clinical relevance of OVOL1 and ID1 function in human AD. Our study highlights a keratinocyte-intrinsic AhR-Ovol1-Id1 regulatory axis that promotes both epidermal and immune homeostasis against AD-like inflammation, implicating new therapeutic targets for AD.

Qingre Qushi formula suppresses atopic dermatitis via a multi-target mechanism

ETHNOPHARMACOLOGICAL RELEVANCE

Our previous studies have shown that the Qingre Qushi (QRQS) formula can treat atopic dermatitis (AD), and its possible mechanism is related to the regulation of the IL-33/ST2 signaling pathway. However, the molecular mechanism of AD is complex, and various AD subtypes respond better to therapies aimed at distinct targets.

AIM OF THE STUDY

This study aimed to investigate the multi-target mechanism of QRQS using experimental and network pharmacology studies.

MATERIALS AND METHODS

Flaky tail (FT) mice were treated with different concentrations of QRQS and cetirizine. The dermatitis score, scratching frequency, and histological evaluation were normatively evaluated. The levels of IgE and IgG1 in serum were tested using ELISAs. Using ELISA and RT-PCR, the expression of associated cytokines was determined. IL-17A-stimulated HaCaT cells were treated with QRQS to assess mRNA and protein expression. To elucidate the mechanism, a network pharmacology analysis based on active components derived from UPLC was conducted. Through molecular docking, we evaluated the binding affinity between the active constituents of QRQS and potential targets.

RESULTS

Using UPLC, 177 active ingredients in QRQS were identified. Network pharmacology analysis showed that the anti-AD effect of the active ingredients was related to the IL-17 signaling pathway and its related targets. FT mice are characterized by Th17-dominated immune disorders. QRQS ameliorated AD-like symptoms and decreased dermatitis scores and scratching frequencies. After QRQS treatment, IL-17A expression was inhibited and IL-17 pathway-associated cytokines were downregulated. Along with changes in Th17-differentiation, QRQS suppressed the expression of IL-4, IL-13, and TNF-α. QRQS also decreased the expression of IL-6, IL-8, and COX-2 in HaCaT cells exposed to IL-17A. The anti-AD active doses are 3.86 g/kg/day in vivo and 100 μg/mL in vitro.

CONCLUSION

QRQS has a multi-target immunoregulatory effect on AD and can improve the Th17-dominated inflammatory response by regulating the IL-17A signaling pathway. Quercetin, genistein, luteolin, and kaempferol are potential active ingredients.

Impact of Crisaborole in Treatment-Experienced Patients With Mild-to-Moderate Atopic Dermatitis

Background: Crisaborole ointment, 2%, is a nonsteroidal phosphodiesterase 4 inhibitor for the treatment of patients with mild-to-moderate atopic dermatitis (AD). Objective: To assess the efficacy and safety of crisaborole in patients with AD who had received prior treatment with (a) corticosteroids (systemic or topical) or topical calcineurin inhibitors (TCIs) or (b) topical corticosteroids (TCSs) or TCIs or (c) who were treatment-naive (TN). Methods: This post hoc analysis comprised patients aged ≥2 years with mild-to-moderate AD. Patients were assigned (2:1) to receive crisaborole or vehicle twice daily for 28 days. Patient response was assessed with the Investigator's Static Global Assessment (ISGA), Dermatology Life Quality Index (DLQI), Children's Dermatology Life Quality Index (CDLQI), and Dermatitis Family Impact (DFI) tools. Safety was also assessed. Results: A significantly higher percentage of patients treated with crisaborole versus vehicle achieved ISGA success regardless of treatment history. Patients treated with crisaborole had significant reductions in DLQI, CDLQI, and DFI scores versus those who received vehicle regardless of treatment history, with the exception of DLQI and DFI scores in the TN group. Crisaborole was well tolerated in all subgroups. Conclusion: Crisaborole demonstrated a favorable efficacy and safety profile in both treatment-experienced and TN patients. ClinicalTrials.gov, NCT02118766 and NCT02118792.

Recent advances in immunomodulators for atopic dermatitis

PURPOSE OF REVIEW

Conventional treatments of atopic dermatitis have been inadequate, especially in patients with moderate-to-severe disease.

RECENT FINDINGS

In the past 5 years, four immunomodulators have been approved for the treatment of atopic dermatitis in children. These include dupilumab, ruxolitinib, upadacitinib, and abrocitinib. The review summarizes the pivotal phase 3 trials of these medications.

SUMMARY

The newer immunomodulators have transformed the treatment of atopic dermatitis, particularly in patients with moderate-to-severe disease. Dupilumab targets IL-4 and IL-13, which are the main causes of allergic inflammation, resulting in great efficacy and few side effects. Upadacitinib and abrocitinib are alternative systemic medications for adolescents who have failed or are unable to tolerate dupilumab. Ruxolitinib cream is the latest addition to the current topical therapy. It is indicated for children 12 years and older with mild-to-moderate atopic dermatitis. Further studies are needed to confirm its safety and efficacy for younger children and for patients with more severe disease.

The hidden sentinel of the skin: An overview on the role of interleukin-13 in atopic dermatitis

Recent evidence suggests that interleukin (IL)-13 is a crucial cytokine involved in the pathogenesis of atopic dermatitis (AD). It is a central driver of type-2 T-helper inflammation and is overexpressed in lesional skin of AD patients. Upon release in peripheral skin, IL-13 activates its receptors, recruits inflammatory cells, and modifies the skin microbiome. IL-13 also reduces the expression of epidermal barrier proteins and activates sensory nerve mediating the itch transmission signal. Novel therapeutics that target IL-13 seem to be efficacious and safe for the treatment of patients with moderate-to-severe AD. The aim of our manuscript is to review the role that IL-13 plays in AD immunopathogenesis.

Sphingosine 1-Phosphate as Essential Signaling Molecule in Inflammatory Skin Diseases

Sphingolipids are crucial molecules of the mammalian epidermis. The formation of skin-specific ceramides contributes to the formation of lipid lamellae, which are important for the protection of the epidermis from excessive water loss and protect the skin from the invasion of pathogens and the penetration of xenobiotics. In addition to being structural constituents of the epidermal layer, sphingolipids are also key signaling molecules that participate in the regulation of epidermal cells and the immune cells of the skin. While the importance of ceramides with regard to the proliferation and differentiation of skin cells has been known for a long time, it has emerged in recent years that the sphingolipid sphingosine 1-phosphate (S1P) is also involved in processes such as the proliferation and differentiation of keratinocytes. In addition, the immunomodulatory role of this sphingolipid species is becoming increasingly apparent. This is significant as S1P mediates a variety of its actions via G-protein coupled receptors. It is, therefore, not surprising that dysregulation in the signaling pathways of S1P is involved in the pathophysiological conditions of skin diseases. In the present review, the importance of S1P in skin cells, as well as the immune cells of the skin, is elaborated. In particular, the role of the molecule in inflammatory skin diseases will be discussed. This is important because interfering with S1P signaling pathways may represent an innovative option for the treatment of inflammatory skin diseases.

Therapeutic effects of mesenchymal stem cells and their derivatives in common skin inflammatory diseases: Atopic dermatitis and psoriasis

Chronic skin inflammatory diseases including atopic dermatitis (AD) and psoriasis have been considered uncontrolled inflammatory responses, which have usually troubled patients around the world. Moreover, the recent method to treat AD and psoriasis has been based on the inhibition, not regulation, of the abnormal inflammatory response, which can induce a number of side effects and drug resistance in long-term treatment. Mesenchymal stem/stromal cells (MSCs) and their derivatives have been widely used in immune diseases based on their regeneration, differentiation, and immunomodulation with few adverse effects, which makes MSCs a promising treatment for chronic skin inflammatory diseases. As a result, in this review, we aim to systematically discuss the therapeutic effects of various resources of MSCs, the application of preconditioning MSCs and engineering extracellular vesicles (EVs) in AD and psoriasis, and the clinical evaluation of the administration of MSCs and their derivatives, which can provide a comprehensive vision for the application of MSCs and their derivatives in future research and clinical treatment.