Thymic stromal lymphopoietin, skin barrier dysfunction, and the atopic march

Atopic dermatitis phenotype affects expression of atopic diseases despite similar mononuclear cell cytokine response

BACKGROUND

The atopic march refers to the coexpression and progression of atopic diseases in childhood, often beginning with atopic dermatitis (AD), although children may not progress through each atopic disease.

OBJECTIVE

We hypothesized that future atopic disease expression is modified by AD phenotype and that these differences result from underlying dysregulation of cytokine signaling.

METHODS

Children (n = 285) were enrolled into the Childhood Origins of Asthma (COAST) birth cohort and followed prospectively. Rates of AD, food allergy, allergic rhinitis, and asthma were assessed longitudinally from birth to 18 years of age. Associations between AD phenotype and food allergy, allergic rhinitis, asthma, allergic sensitization, exhaled nitric oxide, and lung function were determined. Peripheral blood mononuclear cell responses (IL-5, IL-10, IL-13, IFN-γ) to dust mite, phytohemagglutinin, Staphylococcus aureus Cowan I, and tetanus toxoid were compared among AD phenotypes.

RESULTS

AD at year 1 was associated with an increased risk of food allergy (P = .004). Both persistent and late-onset AD were associated with an increased risk of asthma (P < .001), rhinitis (P < .001), elevated total IgE (P < .001), percentage of aeroallergens with detectable IgE (P < .001), and elevated exhaled nitric oxide (P = .002). Longitudinal analyses did not reveal consistent differences in peripheral blood mononuclear cell responses among dermatitis phenotypes.

CONCLUSION

AD phenotype is associated with differential expression of other atopic diseases. Our findings suggest that peripheral blood cytokine dysregulation is not a mechanism underlying this process, and immune dysregulation may be mediated at mucosal surfaces or in secondary lymphoid organs.

Modification of Food Allergy on the Associations between Early Life Exposure to Size-Specific Particulate Matter and Childhood Allergic Rhinitis

Previous studies have reported the association between particulate matter (PM) and childhood allergic rhinitis (AR). However, it is unclear whether food allergy (FA) modifies the PM-AR association. We aimed at evaluating the effect of the modification of FA on PM-AR association in preschool children. We adopted a cross-sectional study and conducted a questionnaire survey among preschool children aged 3-6 years in 7 cities in China from June 2019 to June 2020 to collect information on AR and FA. We used a combination of multilevel logistic regression and restricted cubic spline functions to quantitatively assess whether FA modifies the associations between size-specific PM exposure (1 × 1 km) and the risk of AR. The adjusted odds ratios (ORs) for AR among the children with FA as per a 10 μg/m3 increase in early life PM1, PM2.5, and PM10 were significantly higher than the corresponding ORs among the children without FA [e.g., OR: 1.58, 95% CI: (1.32, 1.90) vs 1.29, 95% CI: (1.18, 1.41), per 10 μg/m3 increase in PM1]. The interactions between FA and size-specific PM exposure and their effects on AR were statistically significant (all p-int < 0.001). FA, as an important part of the allergic disease progression, may modify the PM-AR association in preschool children.

Atopic March or Atopic Multimorbidity-Overview of Current Research

The atopic march encompasses a sequence of allergic conditions, including atopic dermatitis, food allergy, allergic rhinitis, and asthma, that frequently develop in a sequential pattern within the same individual. It was introduced as a conceptual framework aimed at elucidating the developmental trajectory of allergic conditions during childhood. Following the introduction of this concept, it was initially believed that the atopic march represented the sole and definitive trajectory of the development of allergic diseases. However, this perspective evolved with the emergence of new longitudinal studies, which revealed that the evolution of allergic diseases is far more intricate. It involves numerous immunological pathological mechanisms and may not align entirely with the traditional concept of the atopic march. The objective of our review is to portray the atopic march alongside other patterns in the development of childhood allergic diseases, with a specific emphasis on the potential for a personalized approach to the prevention, diagnosis, and treatment of atopic conditions.

Might biologics serve to interrupt the atopic march?

The atopic march was described more than 20 years ago on the basis of initial observations, and it is now seen in prospective studies. The concept has evolved and is now considered to be the progression of atopic dermatitis to other atopic conditions, including asthma, allergic rhinitis, food allergy, and eosinophilic esophagitis in a nonlinear fashion. The progression can include some or all of the aforementioned atopic conditions. The pathogenesis is part of the classic type 2 inflammatory process involving IL-4, IL-5, and IL-13 preceded by induction of the alarmins (thymic stromal lymphopoietin, IL-33, and IL-25), leading to production of IgE in a genetically predisposed individual. The development of new biologics that interact with T2 pathway represent possible ways to prevent or modify the atopic march.

Stratum corneum lipid and cytokine biomarkers at age 2 months predict the future onset of atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) commonly occurs in children and can progress into severe phenotypes or atopic march, causing significant impairment in quality of life. It is important to find early biomarkers of future onset of AD before any clinical manifestations.

OBJECTIVE

We sought to find early predictors of future onset of AD in skin stratum corneum (SC).

METHODS

Skin tape strips were collected from the forearm of newborns (n = 111) with and without family history of atopic diseases at the age of 2 months before any signs of clinical AD. Children were clinically monitored until they reached age 2 years to ensure the presence or absence of AD. Skin tape strips were subjected to lipidomic analyses by the liquid chromatography electrospray ionization tandem mass spectrometry and cytokine determination by Meso Scale Discovery U-Plex assay.

RESULTS

Overall, 22 of 74 (29.7%) and 5 of 37 (13.5%) infants developed AD in the risk group and the control group, respectively. In the SC of future AD children, protein-bound ceramides were decreased (P < .001), whereas unsaturated sphingomyelin species (P < .0001) and "short-chain" nonhydroxy fatty acid sphingosine and alpha-hydroxy fatty acid sphingosine ceramides were elevated (P < .01 and .05, respectively) as compared with healthy children. Thymic stromal lymphopoietin and IL-13 levels were increased in the SC of future AD subjects (by 74.5% and 78.3%, P = .0022 and P < .0001, respectively). Multivariable logistic regression analysis revealed strong AD predicting power of the combination of family history, type 2 cytokines, and dysregulated lipids, with an odds ratio reaching 54.0 (95% CI, 9.2-317.5).

CONCLUSIONS

Noninvasive skin tape strip analysis at age 2 months can identify asymptomatic children at risk of future AD development with a high probability.

Cellular mechanisms and effects of IL-4 receptor blockade in experimental conjunctivitis evoked by skin inflammation

Ocular surface diseases, including conjunctivitis, are recognized as common comorbidities in atopic dermatitis (AD) and occur at an increased frequency in patients with AD treated with biologics targeting IL-4 receptor α (IL-4Rα) or IL-13. However, the inflammatory mechanisms underlying this pathology are unknown. Here, we developed a potentially novel mouse model of skin inflammation-evoked conjunctivitis and showed that it is dependent on CD4+ T cells and basophils. Blockade of IL-4Rα partially attenuated conjunctivitis development, downregulated basophil activation, and led to a reduction in expression of genes related to type 2 cytokine responses. Together, these data suggest that an IL-4Rα/basophil axis plays a role in the development of murine allergic conjunctivitis. Interestingly, we found a significant augmentation of a number of genes that encode tear proteins and enzymes in anti-IL-4Rα-treated mice, and it may underlie the partial efficacy in this model and may represent candidate mediators of the increased frequency of conjunctivitis following dupilumab in patients with AD.

Inborn Errors of the Immune System Associated With Atopy

Atopic disorders, including atopic dermatitis, food and environmental allergies, and asthma, are increasingly prevalent diseases. Atopic disorders are often associated with eosinophilia, driven by T helper type 2 (Th2) immune responses, and triggered by disrupted barrier function leading to abnormal immune priming in a susceptible host. Immune deficiencies, in contrast, occur with a significantly lower incidence, but are associated with greater morbidity and mortality. A subset of atopic disorders with eosinophilia and elevated IgE are associated with monogenic inborn errors of immunity (IEI). In this review, we discuss current knowledge of IEI that are associated with atopy and the lessons these immunologic disorders provide regarding the fundamental mechanisms that regulate type 2 immunity in humans. We also discuss further mechanistic insights provided by animal models.

Improvement in eosinophilic esophagitis when using dupilumab for other indications or compassionate use

BACKGROUND

Dupilumab has been approved to treat atopic dermatitis, asthma, and nasal polyps and is in active clinical trials for the treatment of eosinophilic esophagitis (EoE). Given its shared immunopathology, we hypothesized that EoE symptoms and inflammation would improve when dupilumab therapy was used for other allergic indications.

OBJECTIVE

To measure the clinical and histologic response in EoE to dupilumab when treating other atopic diseases.

METHODS

We completed a retrospective chart review of all patients at Children's Hospital of Philadelphia and Rady Children Hospital who were prescribed dupilumab for atopic dermatitis, asthma, or nasal polyps and had a concomitant clinical diagnosis of EoE. Demographic information along with histology, symptom scores, medications, and diet information were collected. Response to dupilumab was evaluated.

RESULTS

A total of 45 patients were identified. Of which, 11 patients were prescribed dupilumab for asthma, 27 for atopic dermatitis, 3 for nasal polyps, and 4 for compassionate use for EoE. There was no follow-up data for 8 patients. Follow-up histology was available for 26 patients: 22 of 26 had less than 6 eosinophils per high power field after the initiation of dupilumab with significant improvement (pre: 52.9 + 35.1 to post: 4.5 + 10.9 eosinophils/high power field, P < .005). A total of 28 patients had improvement of symptoms, with 24 patients reporting complete resolution of symptoms after dupilumab initiation. Reductions in EoE treatment medications (swallowed steroids, proton pump inhibitors) or expansion of diet occurred in 29 patients treated with dupilumab.

CONCLUSION

Dupilumab therapy initiated for atopic disease effectively induces symptomatic and histologic remission of esophageal disease and reduces the need for EoE-directed therapy in patients with concomitant EoE.

Multi-Omics Profiling Approach to Asthma: An Evolving Paradigm

Asthma is a complex multifactorial and heterogeneous respiratory disease. Although genetics is a strong risk factor of asthma, external and internal exposures and their interactions with genetic factors also play important roles in the pathophysiology of asthma. Over the past decades, the application of high-throughput omics approaches has emerged and been applied to the field of asthma research for screening biomarkers such as genes, transcript, proteins, and metabolites in an unbiased fashion. Leveraging large-scale studies representative of diverse population-based omics data and integrating with clinical data has led to better profiling of asthma risk. Yet, to date, no omic-driven endotypes have been translated into clinical practice and management of asthma. In this article, we provide an overview of the current status of omics studies of asthma, namely, genomics, transcriptomics, epigenomics, proteomics, exposomics, and metabolomics. The current development of the multi-omics integrations of asthma is also briefly discussed. Biomarker discovery following multi-omics profiling could be challenging but useful for better disease phenotyping and endotyping that can translate into advances in asthma management and clinical care, ultimately leading to successful precision medicine approaches.

Melatonin prevents allergic airway inflammation in epicutaneously sensitized mice

PURPOSE

The pathological process of atopic dermatitis (AD) progressing into other types of allergic diseases such as asthma and allergic rhinitis during the first several years of life is often referred to as the atopic march. Although the phenomenon of atopic march has been recognized for decades, how asthma stems from AD is still not fully understood, confounding a universal strategy to effectively protect people from the atopic march.

METHODS

We established experimental atopic march mice by first inducing allergic dermatitis with 0.5% fluorescein isothiocyante (FITC) applied to the skin, followed by an ovalbumin (OVA) airway challenge. In addition, by examining serum immunoglobulin (Ig) concentrations, airway cytokines, the levels of oxidative stress markers, histopathological changes in lung tissue and airway hyperresponsiveness (AHR), we were able to validate the successful establishment of the model. Furthermore, by detecting the attenuating effects of melatonin (MT) and the levels of oxidative stress in the atopic march mice, we explored the potential molecular mechanisms involved in the development of atopic march.

RESULTS

By successfully establishing an experimental atopic march mouse model, we were able to demonstrate that overproduction of oxidative stress in the lung significantly up-regulated the activation of nuclear factor-κB (NF-κB) signaling pathways causing thymic stromal lymphopoietin (TSLP) release, which further promotes the development of atopic march.

CONCLUSIONS

To mitigate the development of the atopic march, antioxidants such as MT may be imperative to inhibit NF-κB activation in the lung, especially after the onset of AD.