Expansion of activated eosinophils in infants with severe atopic dermatitis

Enhanced Siglec-8 and HLA-DR and reduced CRTH2 surface expression highlight a distinct phenotypic signature of circulating eosinophils in atopic dermatitis

Atopic dermatitis and other type 2 immune response diseases are often linked to elevated eosinophil levels in the blood. Although the role of eosinophils in atopic dermatitis pathophysiology is suspected, it remains unclear. The development of new treatments targeting the type 2 response, particularly cytokines involved in eosinophil activation and chemotaxis, makes it necessary to identify potential eosinophil profiles in atopic dermatitis that may respond to these treatments. A prospective study was conducted comparing blood eosinophil phenotypes in patients with moderate to severe atopic dermatitis (n = 19) without recent systemic treatment to healthy individuals (n = 19). The primary outcome was the membranous phenotypic signature of eosinophils, assessed by flow cytometry. Most patients with atopic dermatitis (84%) had early onset in childhood, a severe disease (mean SCORing Atopic Dermatitis of 57.5), and elevated blood eosinophil counts (310 per µL in atopic dermatitis vs 120 in healthy individuals, P < 0.0001). Patients with atopic dermatitis exhibited lower CRTH2 on eosinophils but higher levels of human leukocyte antigen-DR isotype and Siglec-8 compared to healthy individuals. Other surface proteins showed no significant differences. Clustering analysis confirmed increased Siglec-8 in patients with atopic dermatitis. Additionally, patients with atopic dermatitis had higher serum levels of type 2 immune response markers such as eotaxin-2, IL-5, IL-3, and TARC. Circulating eosinophils in patients with atopic dermatitis show a distinct phenotypic profile, suggesting a role in atopic dermatitis pathophysiology and potential involvement in differential treatment responses.

Relationship between circulating white blood cell count and inflammatory skin disease: a bidirectional mendelian randomization study

Observational studies have shown a strong association between circulating white blood cell counts (WBC) and inflammatory skin diseases such as acne and psoriasis. However, the causal nature of this relationship is unclear. We performed a two-way two-sample Mendelian randomization (MR) analysis to investigate potential causal relationships between leukocytes and inflammatory skin diseases. The circulating white blood cell count, basophil cell count, leukocyte cell count, lymphocyte cell count, eosinophil cell count, and neutrophil cell count data were obtained from the Blood Cell Consortium (BCX). The data for inflammatory skin disorders, including acne, atopic dermatitis (AD), hidradenitis suppurativa (HS), psoriasis, and seborrheic dermatitis (SD), were obtained from the FinnGen Consortium R10. The primary analysis utilized inverse variance weighting (IVW) along with additional methods such as MR-Egger, weighted mode, and weighted median estimator. To assess heterogeneity among instrument variables, Cochran's Q test was employed, while MR-Egger intercept and MR-PRESSO were used to test for horizontal pleiotropy. IVW demonstrated that an elevated monocyte count was significantly associated with a decreased risk of psoriasis (OR = 0.897, 95% CI: 0.841-0.957, P = 0.001, FDR = 0.016). Additionally, an increased eosinophil count was causally associated with a higher risk of AD (OR = 1.188, 95% CI: 1.093-1.293, P = 0.000, FDR = 0.002). No inverse causal relationship between inflammatory skin disease and circulating white blood cell count was found. In conclusion, this study provides evidence that increased monocyte count is associated with a reduced risk of psoriasis and that there is a causal relationship between increased eosinophil counts and an increased risk of AD. These findings help us understand the potential causal role of specific white blood cell counts in the development of inflammatory skin diseases.

Systematic multi-omics reveals the overactivation of T cell receptor signaling in immune system following bisphenol A exposure

Bisphenol A (BPA) is pervasive in the environment, and exposure to BPA may increase the incidence of noncommunicable diseases like autoimmune diseases and cancer. Although BPA causes immunological problems at the cellular level, no system-level research has been conducted on this. Hence, in this study, we aimed to gain a better understanding of the biological response to BPA exposure and its association with immunological disorders. For that, we explored the transcriptome and the proteomic modifications at the systems and cellular levels following BPA exposure. Our integrated multi-omics data showed the alteration of the T cell receptor (TCR) signaling pathway at both levels. The proportion of enlarged T cells increased with upregulation of CD69, a surface marker of early T cell activation, even though the number of T cells reduced after BPA exposure. Additionally, on BPA exposure, the levels of pLCK and pSRC increased in T cells, while that of pLAT decreased. Following BPA exposure, we investigated cytokine profiles and discovered that chitinase 3 Like 1 and matrix metalloproteinase 9 were enriched in T cells. These results indicated that T cells were hyperactivated by CD69 stimulation, and phosphorylation of SRC accelerated on BPA exposure. Hence, alteration in the TCR signaling pathway during development and differentiation due to BPA exposure could lead to insufficient and hasty activation of TCR signaling in T cells, which could modify cytokine profiles, leading to increased environmental susceptibility to chronic inflammation or diseases, increasing the chance of autoimmune diseases and cancer. This study enhances our understanding of the effects of environmental perturbations on immunosuppression at molecular, cellular, and systematic levels following pubertal BPA exposure, and may help develop better predictive, preventative, and therapeutic techniques.

Tumor-Derived Exosomes Regulate Apoptosis of CD45+EpCAM+ Cells in Lung Cancer

Lung cancer has the highest mortality rate among human cancers, and the majority of deaths result from metastatic spread. The tumor microenvironment plays an important role in suppressing the immune surveillance and elimination of tumor cells. A few studies have reported the presence of CD45⁺EpCAM⁺ double-positive cells in cancer, but the underlying mechanism remains unclear with respect to how these cells originate and their function in cancer biology. In this study, we analyzed 25 lung tumor samples. We confirmed the presence of CD45⁺EpCAM⁺ cells in lung cancer, and these cells exhibited higher apoptosis than CD45⁺EpCAM⁻ cells. Using co-culture of lung cancer cell-derived exosomes with healthy donor peripheral blood mononuclear cells, we recapitulated CD45⁺EpCAM⁺ cell formation and increased apoptosis that occurs in patients with primary lung cancer. Further analysis suggested that microRNAs in lung cancer cell-derived exosomes may alter the gene expression profile of CD45⁺EpCAM⁺ cells, resulting in elevated TP53 expression and increased apoptosis. To our knowledge, this is the first report of cancer cell-derived exosomes that can inhibit the immune system by promoting immune cell apoptosis.

DNA Methylation Array Identifies Golli-MBP as a Biomarker for Disease Severity in Childhood Atopic Dermatitis

In this study, we investigated the changes in global methylation status and its functional relevance in childhood atopic dermatitis (AD). Differences in epigenome-scale methylation events in peripheral blood associated with childhood AD were screened using DNA methylation arrays of 24 patients with AD compared with 24 control subjects. Of the 16,840 differentially methylated CpG regions between AD and control subjects, >97% CpG loci revealed hypomethylation in patients with childhood AD. Among the globally hypomethylated loci, we identified two CpG clusters within the golli-mbp locus of the MBP gene, which was functionally enriched by subnetwork enrichment analysis as an orchestrator among associated genes. The differential hypomethylation of the top-ranked cg24700313 cluster in the golli-mbp locus was validated by pyrosequencing in an independent cohort of 224 children with AD and 44 control subjects. DNA methylation was found to be negatively correlated with disease severity but showed no significant correlation with IgE levels after age adjustment. The multivariate correlation analysis represents a higher score in AD intensity with significantly increased IgE levels and decreased methylation levels in cg27400313. We concluded that methylation loss in the golli-mbp locus is an epigenetic factor associated with disease severity of childhood AD.

The pivotal role of CD69 in autoimmunity

Autoimmune disorders are outcomes of impaired activity of the immune system regarding the maintenance of tolerance, which results in tissue damage secondary to an excess in the inflammatory response. Under normal conditions, the cells in the adaptive immune system are highly controlled to remain unresponsive against self-antigens (self-Ags) through various mechanisms and during different stages of maturation. CD69 (cluster of differentiation 69), a C-type lectin disulfide-linked homodimer, is expressed on different leukocytes, including newly-activated lymphocytes, certain subtypes of memory T-cells, infiltrating lymphocytes isolated from patients with chronic inflammatory disorders, and regulatory T-cells (Tregs). Cumulative evidence from in vitro and in vivo studies has revealed an immunoregulatory role for CD69. This marker has been reported to play a controversial role in chronic human inflammatory disorders. Many investigations have linked the absence of CD69 with a predisposition to inflammatory and/or autoimmune conditions, which indicates an immunoregulatory function for CD69 by mechanisms such as controlling the balance between differentiation of Th/Treg cells and enhancing the suppressive activity of Tregs. However, some reports from human studies have indicated that CD69 may exert a stimulatory effect on the inflammatory response. In this review, we first present a brief summary of the concept of 'immune tolerance' and, subsequently, review previous studies to uncover the details that underlie the immunoregulatory effects of CD69.

Nickel challenge up regulates CD69 expression on T lymphocyte sub-sets from patients with nickel induced contact dermatitis

Background

Persistent antigenic stimulation due to repeated exposure to nickel may lead to chronic inflammation resulting in allergic contact dermatitis (ACD).

Objectives

This study was performed to assess nickel induced immune activation among patients sensitized against nickel.

Patients and Methods

A total of 35 patients (29 females and 6 males; mean age 36±9 years) with nickel contact dermatitis and 20 patch test negative healthy individuals (14 females and 6 males; mean age 29±7 years) were included in this study. Peripheral blood of patients and controls was incubated with nickel sulfate for 24 hours. Immune activation was assessed by CD69 up-regulation on T lymphocyte sub-sets by flow cytometry.

Results

Base line expression of CD69 on CD8⁺ lymphocytes was higher among patients compared to controls (4.1±1.3%vs2.8±1.1%;p<0.009). There was no difference in proportions of CD±CD69⁺ cells between patients and controls (3.2±0.9%vs2.3±0.8%). Exposure to nickel induced expression of CD69 on a significantly higher proportion of CD4⁺ lymphocytes (22.1±6.2%) of the ACD patients compared to controls (2.8±2.5%;p<0.0001). Similarly nickel induced CD69 expression on a higher proportion of CD8⁺ lymphocytes (18.2±5.3%) from ACD patients compared to the controls (1.9±1.8%;p<0.0006).

Conclusion

CD69 molecule appears to be an important regulator of immune response in nickel contact dermatitis.

Common features of atopic dermatitis with hypoproteinemia

Purpose

The purpose of this study was to identify the causes, symptoms, and complications of hypoproteinemia to prevent hypoproteinemia and provide appropriate treatment to children with atopic dermatitis.

Methods

Children diagnosed with atopic dermatitis with hypoproteinemia and/or hypoalbuminemia were retrospectively reviewed. The patients’ medical records, including family history, weight, symptoms, treatment, complications, and laboratory test results for allergies and skin cultures, were examined.

Results

Twenty-six patients (24 boys) were enrolled. Seven cases had growth retardation; 7, keratoconjunctivitis; 6, aural discharges; 5, eczema herpeticum; 4, gastrointestinal tract symptoms; and 2, developmental delays. In 21 cases, topical steroids were not used. According to the blood test results, the median values of each parameter were elevated: total IgE, 1,864 U/mL; egg white-specific IgE, 76.5 kU_A/L; milk IgE, 20.5 kU_A/L; peanut IgE, 30 kU_A/L; eosinophil count, 5,810/μL; eosinophil cationic protein, 93.45 μg/L; and platelet count, 666.5×10³/μL. Serum albumin and total protein levels decreased to 2.7 g/dL and 4.25 g/dL, respectively. Regarding electrolyte abnormality, 10 patients had hyponatremia, and 12, hyperkalemia. Systemic antibiotics were used to treat all cases, and an antiviral agent was used in 12 patients. Electrolyte correction was performed in 8 patients.

Conclusion

Hypoproteinemia accompanying atopic dermatitis is common in infants younger than 1 year and may occur because of topical steroid treatment continuously being declined or because of eczema herpeticum. It may be accompanied by growth retardation, keratoconjunctivitis, aural discharge, and eczema herpeticum and can be managed through skin care and topical steroid application without intravenous albumin infusion.

Aluminum Adjuvant-Containing Vaccines in the Context of the Hygiene Hypothesis: A Risk Factor for Eosinophilia and Allergy in a Genetically Susceptible Subpopulation?

There are similarities between the immune response following immunization with aluminum adjuvants and the immune response elicited by some helminthic parasites, including stimulation of immunoglobulin E (IgE) and eosinophilia. Immunization with aluminum adjuvants, as with helminth infection, induces a Th2 type cell mediated immune response, including eosinophilia, but does not induce an environment conducive to the induction of regulatory mechanisms. Helminths play a role in what is known as the hygiene hypothesis, which proposes that decreased exposure to microbes during a critical time in early life has resulted in the increased prevalence and morbidity of asthma and atopic disorders over the past few decades, especially in Western countries. In addition, gut and lung microbiome composition and their interaction with the immune system plays an important role in a properly regulated immune system. Disturbances in microbiome composition are a risk factor for asthma and allergies. We propose that immunization with aluminum adjuvants in general is not favorable for induction of regulatory mechanisms and, in the context of the hygiene hypothesis and microbiome theory, can be viewed as an amplifying factor and significant contributing risk factor for allergic diseases, especially in a genetically susceptible subpopulation.

Crucial role for CD69 in allergic inflammatory responses: CD69-Myl9 system in the pathogenesis of airway inflammation

CD69 has been known as an early activation marker of lymphocytes; whereas, recent studies demonstrate that CD69 also has critical functions in immune responses. Early studies using human samples revealed the involvement of CD69 in various inflammatory diseases including asthma. Moreover, murine disease models using Cd69^-/- mice and/or anti-CD69 antibody (Ab) treatment have revealed crucial roles for CD69 in inflammatory responses. However, it had not been clear how the CD69 molecule contributes to the pathogenesis of inflammatory diseases. We recently elucidated a novel mechanism, in which the interaction between CD69 and its ligands, myosin light chain 9, 12a and 12b (Myl9/12) play a critical role in the recruitment of activated T cells into the inflammatory lung. In this review, we first summarize CD69 function based on its structure and then introduce the evidence for the involvement of CD69 in human diseases and murine disease models. Then, we will describe how we discovered CD69 ligands, Myl9 and Myl12, and how the CD69-Myl9 system regulates airway inflammation. Finally, we will discuss possible therapeutic usages of the blocking Ab to the CD69-Myl9 system.

Eosinophil-derived neurotoxin as a biomarker for disease severity and relapse in recalcitrant atopic dermatitis

BACKGROUND

Eosinophils are encountered in many skin diseases, but the role of eosinophils in atopic dermatitis (AD) remains uncertain.

OBJECTIVE

To examine the role of serum eosinophil-derived neurotoxin (EDN), eosinophil cationic protein (ECP), and total IgE as a biomarker of disease severity and relapse in severe recalcitrant AD.

METHODS

We enrolled 99 patients with AD: 37 with severe recalcitrant AD, 20 with severe AD, and 42 with mild to moderate AD. We examined the difference in serum level of total IgE, ECP, and EDN between the groups and whether any correlation existed between disease severity and ECP or EDN. Lastly, difference in levels of ECP or EDN between those who experienced relapse was examined in the severe recalcitrant group.

RESULTS

Serum levels of total IgE, ECP, and EDN were significantly higher in the severe recalcitrant AD group and severe AD group compared with the mild to moderate AD group. No significant difference was found in serum levels of total IgE, ECP, and EDN between the severe recalcitrant group and severe group. EDN had a significant positive correlation with the SCORing Atopic Dermatitis. No significant correlation was found between EDN and ECP. In the severe recalcitrant group, 29.7% of patients experienced relapse, and EDN was significantly higher in those who experienced relapse. The cutoff value of EDN for predicting relapse was 64.5.

CONCLUSION

EDN correlated with the disease severity of AD. EDN may predict relapse in severe recalcitrant AD. The EDN serum level could be considered a candidate molecule as a clinical biomarker for evaluating AD disease activity and a predictor of relapse.

CD69: from activation marker to metabolic gatekeeper

CD69 is a membrane-bound, type II C-lectin receptor. It is a classical early marker of lymphocyte activation due to its rapid appearance on the surface of the plasma membrane after stimulation. CD69 is expressed by several subsets of tissue resident immune cells, including resident memory T (TRM) cells and gamma delta (γδ) T cells, and is therefore considered a marker of tissue retention. Recent evidence has revealed that CD69 regulates some specific functions of selected T-cell subsets, determining the migration-retention ratio as well as the acquisition of effector or regulatory phenotypes. Specifically, CD69 regulates the differentiation of regulatory T (Treg) cells as well as the secretion of IFN-γ, IL-17, and IL-22. The identification of putative CD69 ligands, such as Galectin-1 (Gal-1), suggests that CD69-induced signaling can be regulated not only during cognate contacts between T cells and antigen-presenting cells in lymphoid organs, but also in the periphery, where cytokines and other metabolites control the final outcome of the immune response. Here, we will discuss new aspects of the molecular signaling mediated by CD69 and its involvement in the metabolic reprogramming regulating TH-effector lineages.

Elevated blood eosinophils in early infancy are predictive of atopic dermatitis in children with risk for atopy

BACKGROUND

Accessible markers to predict the development of atopic diseases are highly desirable but yet matter of debate.

OBJECTIVE

We investigated the role of blood eosinophils at 4 weeks and 7 months of life and their association with developing atopic dermatitis (AD) in a birth cohort of children with atopic heredity.

METHODS

Infant blood samples for eosinophil counts were taken from 559 infants at 4 weeks and from 467 infants at 7 month of life with at least one atopic parent. Elevation of blood eosinophils was defined as ≥ 5% of total leukocytes and the asscociation for the occurrence of AD was assessed by entering 2 × 2 tables and the odds ratios were estimated followed by hypothesis testing against the alternate working hypothesis: odds ratio < > 1. Survival analysis was carried out estimating the Kaplan-Meier product limit estimator from the life-time table of AD score and time to AD manifestation stratified by the eosinophil binary score.

RESULTS

Elevated blood eosinophils observed at 4 weeks were significantly associated with the occurrence of AD in the whole cohort at the age of 7 months (p = 0.007), 1 year (p = 0.004), 2 years (p = 0.007) and 3 years (p = 0.006) of life. AD occurred app. 12 weeks earlier in infants with elevated blood eosinophils at 4 weeks of life. Blood eosinophil counts ≥5% at 7 months of life failed to show significance for AD; for eosinophils at 4.5% a significant association at 7 months (p = 0.005), and 1 year of life (p = 0.039), 2 years (p = 0.033) and 3 years (p = 0.034) was observed.

CONCLUSION

Elevated blood eosinophils at age 4 weeks have a predictive value for the onset of atopic dermatitis in infancy and early childhood in children with high risk for atopy. Early eosinophil counts may therefore be helpful for counseling parents to provide infant skincare but furthermore identify individuals for interventional trials aiming at allergy prevention.

Biomarkers of the involvement of mast cells, basophils and eosinophils in asthma and allergic diseases

Biomarkers of disease activity have come into wide use in the study of mechanisms of human disease and in clinical medicine to both diagnose and predict disease course; as well as to monitor response to therapeutic intervention. Here we review biomarkers of the involvement of mast cells, basophils, and eosinophils in human allergic inflammation. Included are surface markers of cell activation as well as specific products of these inflammatory cells that implicate specific cell types in the inflammatory process and are of possible value in clinical research as well as within decisions made in the practice of allergy-immunology.

Early pediatric atopic dermatitis shows only a cutaneous lymphocyte antigen (CLA)(+) TH2/TH1 cell imbalance, whereas adults acquire CLA(+) TH22/TC22 cell subsets

BACKGROUND

Identifying differences and similarities between cutaneous lymphocyte antigen (CLA)(+) polarized T-cell subsets in children versus adults with atopic dermatitis (AD) is critical for directing new treatments toward children.

OBJECTIVE

We sought to compare activation markers and frequencies of skin-homing (CLA(+)) versus systemic (CLA(-)) "polar" CD4 and CD8 T-cell subsets in patients with early pediatric AD, adults with AD, and control subjects.

METHODS

Flow cytometry was used to measure CD69/inducible costimulator/HLA-DR frequency in memory cell subsets, as well as IFN-γ, IL-13, IL-9, IL-17, and IL-22 cytokines, defining TH1/cytotoxic T (TC) 1, TH2/TC2, TH9/TC9, TH17/TC17, and TH22/TC22 populations in CD4 and CD8 cells, respectively. We compared peripheral blood from 19 children less than 5 years old and 42 adults with well-characterized moderate-to-severe AD, as well as age-matched control subjects (17 children and 25 adults).

RESULTS

Selective inducible costimulator activation (P < .001) was seen in children. CLA(+) TH2 T cells were markedly expanded in both children and adults with AD compared with those in control subjects, but decreases in CLA(+) TH1 T-cell numbers were greater in children with AD (17% vs 7.4%, P = .007). Unlike in adults, no imbalances were detected in CLA(-) T cells from pediatric patients with AD nor were there altered frequencies of TH22 T cells within the CLA(+) or CLA(-) compartments. Adults with AD had increased frequencies of IL-22-producing CD4 and CD8 T cells within the skin-homing population, compared with controls (9.5% vs 4.5% and 8.6% vs 2.4%, respectively; P < .001), as well as increased HLA-DR activation (P < .01).

CONCLUSIONS

These data suggest that TH2 activation within skin-homing T cells might drive AD in children and that reduced counterregulation by TH1 T cells might contribute to excess TH2 activation. TH22 "spreading" of AD is not seen in young children and might be influenced by immune development, disease chronicity, or recurrent skin infections.

Is CD69 an effective brake to control inflammatory diseases?

Early studies described CD69 as a leukocyte activation marker, and suggested its involvement in the activation of different leukocyte subsets as well as in the pathogenesis of chronic inflammation. However, recent investigations have showed that CD69 knockout mice exhibit an enhanced or reduced susceptibility to different experimental models of inflammatory diseases, including those mediated by T helper 17 (Th17) lymphocytes. In this regard, the expression of CD69, both in Th17 lymphocytes and by a subset of regulatory T cells, has an important role in the control of the immune response and the inflammatory phenomenon. Therefore, different evidence indicates that CD69 exerts a complex immunoregulatory role in humans, and that it could be considered as a target molecule for the therapy of immune-mediated diseases.

Nonlesional atopic dermatitis skin is characterized by broad terminal differentiation defects and variable immune abnormalities

BACKGROUND

Atopic dermatitis (AD) is a common inflammatory skin disease with a T(H)2 and "T22" immune polarity. Despite recent data showing a genetic predisposition to epidermal barrier defects in some patients, a fundamental debate still exists regarding the role of barrier abnormalities versus immune responses in initiating the disease. An extensive study of nonlesional AD (ANL) skin is necessary to explore whether there is an intrinsic predisposition to barrier abnormalities, background immune activation, or both in patients with AD.

OBJECTIVE

We sought to characterize ANL skin by determining whether epidermal differentiation and immune abnormalities that characterize lesional AD (AL) skin are also reflected in ANL skin.

METHODS

We performed genomic and histologic profiling of both ANL and AL skin lesions (n = 12 each) compared with normal human skin (n = 10).

RESULTS

We found that ANL skin is clearly distinct from normal skin with respect to terminal differentiation and some immune abnormalities and that it has a cutaneous expansion of T cells. We also showed that ANL skin has a variable immune phenotype, which is largely determined by disease extent and severity. Whereas broad terminal differentiation abnormalities were largely similar between involved and uninvolved AD skin, perhaps accounting for the "background skin phenotype," increased expression of immune-related genes was among the most obvious differences between AL and ANL skin, potentially reflecting the "clinical disease phenotype."

CONCLUSION

Our study implies that systemic immune activation might play a role in alteration of the normal epidermal phenotype, as suggested by the high correlation in expression of immune genes in ANL skin with the disease severity index.