Soluble immune receptor serum levels are associated with age, but not with clinical phenotype or disease severity in childhood atopic dermatitis

Soluble IgE-binding factors in the serum of food-allergic patients: Possible pathophysiological role of soluble FcεRI as protective factor

BACKGROUND

IgE-mediated food allergy is the result of an aberrant immune response involving the interaction of a food allergen with its specific IgE bound to FcɛRI, the high affinity IgE receptor, on mast cells. Allergen-specific IgE also binds to soluble binding factors, but, their expression and role in food allergy is not well characterized. Here, we assess the prevalence and relevance of soluble IgE binding factors in food allergy and tolerance.

METHODS

We measured serum levels of four IgE binding factors, that is, galectin-3, galectin-9, soluble FcɛRI (sFcεRI) and soluble CD23 (sCD23) in 67 adults sensitized to peanut or hazelnut and sFcɛRI in 29 children sensitized to hen's egg. Adults without food allergen sensitization (n = 17) served as healthy controls. We compared serum levels of patients and controls and assessed them, in the former, for links to clinical features including allergy and tolerance.

RESULTS

Serum levels of sFcɛRI and sCD23, but not galectin-3 and galectin-9, significantly differ in food-sensitized patients as compared to healthy controls. A subgroup (28%) of peanut and hazelnut allergic patients had elevated sFcεRI levels, that were associated with higher total and specific IgE levels. Furthermore, sFcεRI levels were significantly higher in tolerant subjects compared to allergics. Among hazelnut allergic patients, those with high sFcεRI levels tolerated the highest protein amounts in the oral food challenge.

CONCLUSION

sFcɛRI but not sCD23, galectin-3 and galectin-9 might play a role in the pathophysiology of food allergy. Its functional role or use as biomarker should be assessed in further studies.

Subtypes of atopic dermatitis: From phenotype to endotype

Atopic dermatitis (AD) is a heterogenous disorder and can be classified into different types. Stratification of subtypes may enable personalized medicine approaches. AD can be categorized into the IgE-high, extrinsic subtype and the IgE-normal, intrinsic subtype. While extrinsic AD is the major subtype possessing skin barrier impairment (high incidence of filaggrin mutations), intrinsic AD occupies about 20% of AD with female dominance and preserved barrier. Extrinsic AD exhibits protein allergy and food allergy, but intrinsic AD shows metal allergy possibly in association with suprabasin deficiency. In particular, accumulated knowledge of food allergy has more clearly characterized extrinsic AD. European American (EA) and Asian AD subtypes have been also proposed. Asian patients with AD are characterized by a unique blended immune dysregulation and barrier feature phenotype between EA patients with AD and those with psoriasis. In another ethnic study, filaggrin loss-of-function mutations are not prevalent in African American patients with AD, and Th1/Th17 attenuation and Th2/Th22 skewing were seen in these patients. Recent endotype classification provides new insights for AD and other allergic disorders. Endotype is defined as the molecular mechanisms underlying the visible features/phenotype. Endotype repertoire harbors activation of type 2 cytokines, type 1 cytokines, and IL-17/IL-22, impairment of epidermal barrier, and abnormalities of intercellular lipids. Classification of endotype has been attempted with serum markers. These lines of evidence indicate a need for personalized or precision medicine appropriate for each subtype of AD.

Atopic dermatitis in Taiwanese children: The laboratory values that correlate best to the SCORAD index are total IgE and positive Cheddar cheese IgE

Atopic dermatitis (AD) is a common chronic relapsing inflammatory skin disease associated with a personal or family history of atopic diseases. Determining the objective severity scoring of AD index (SCORAD) and total immunoglobulin E (IgE) to help to stage the severity (lesions extent and intensity of the lesions and then the itch and sleep disturbance they may cause) of AD in children.In this study, we adopted the SCORAD index, which consists of severity, area, and sleep disturbance, to evaluate the AD status of children up to 18 years old. We examined the blood levels of total serum IgE, white blood cell count/differential count (WBC/DC), eosinophil counts (EC), eosinophil cationic protein (ECP) and specific IgE.A total of 208 children with AD were enrolled in this study. Serum IgE values and a number of specific IgE that are positive significantly different SCORAD index through simple linear regression; however, after multiple linear regression, only IgE values (95% CI: 0.001-0.004, P < .001), total WBC count (95% CI: 0.112-1.736, P = .026), EC (95% CI: 0.045-6.706, P = .047), and specific IgE to Cheddar cheese (95% CI: 1.814-16.731, P = .015) remain different. After applying the Phi coefficient, we found that specific IgE to tuna (r = 0.632), codfish (r = 0.613), and clam (r = 0.613) each had a moderate correlation with specific IgE to Cheddar cheese. The 6 most common allergens were found to be mite (D. Farinae: 65.9%), mite (D. Pterony: 64.9%), house dust (47.6%), cockroach mix (37.0%), shrimp (30.8%), and crab (22.6%). Covariates of SCORAD index, severity, area, and sleep disturbance differed.In this study, we found that total IgE values, specific IgE values, WBC, EC, and specific IgE to Cheddar cheese have significant correlations with SCORAD index in AD of Taiwanese children.

Serum biomarkers for allergy in children

A large number of studies investigating various biomarkers for allergy have been published over the past decades. The aim of this review was to evaluate these biomarkers on their diagnostic and/or predictive value. To this date, no single or specific biomarker for allergy has been identified. As allergy is not one disease, but a collection of a number of allergic conditions, it is more plausible a combination of clinical history, clinical readouts, and diagnostic markers will be needed.

Selected immunological parameters in clinical evaluation of patients with atopic dermatitis

Introduction

It has been suggested that soluble immune receptors (SIRs) such as sCD25 and sCD30 may serve as potential biomarkers in evaluation of atopic dermatitis (AD). Previous studies clearly indicated that serum levels of interleukin (IL)-13 and total IgE (tIgE) might be potentially useful in the evaluation of patents with AD.

Aim

To evaluate whether serum levels of sCD25 and sCD30 are suitable biomarkers of AD. Moreover, we have decided to estimate the usefulness of tIgE and IL-13 serum level determination in the evaluated population.

Material and methods

A group of 102 AD patients was investigated. Serum concentrations of sCD30, sCD25, IL-13 and tIgE were measured. The clinical phenotype of AD was classified as extrinsic (ADe) or intrinsic (ADi) based on the presence of IgE. Statistical analysis was performed to estimate correlations between obtained results and clinical features of the population such as AD phenotype, age, disease extent and severity.

Results

Extrinsic AD was diagnosed in 71% of patients, while ADi phenotype was observed in 29% of the investigated population. A negative correlation between serum levels of sCD25 and sCD30 and disease severity as well patients’ age was established. Serum levels of IL-13 did not reach the cut-off point set by the manufacturer. A positive correlation between serum levels of total IgE and disease severity and patients’ age was observed.

Conclusions

This paper shows that serum levels of sCD25 and sCD30 as well as tIgE are age dependent. Determination of serum levels of sCD25, sCD30 and IL-13 is not useful in everyday practice.

TSLP, IL-31, IL-33 and sST2 are new biomarkers in endophenotypic profiling of adult and childhood atopic dermatitis

BACKGROUND

Recent years have seen growing interest in identifying new biomarkers in atopic dermatitis (AD) that could serve as indicators of disease severity and predictors of treatment response.

OBJECTIVES

We compared serum levels of thymic stromal lymphopoietin (TSLP), interleukin(IL)-31, IL-33 and soluble(s)ST2 in AD patients and healthy controls, investigated the possible correlation with disease severity, investigated if other atopic comorbidities could play a role, and assessed their potential as biomarkers in AD.

METHODS

Using standard enzyme-linked immunosorbent assay techniques, we measured target serum levels in 71 adults and 61 children with AD, and 31 adult controls. We characterized our cohort by disease severity, radioallergosorbent test status concerning both dietary and inhalant allergens, and anamnestic reports of food allergy, concomitant allergic asthma and/or allergic rhinitis.

RESULTS

Serum levels of TSLP, IL-31 and IL-33, but not sST2, were significantly elevated in AD patients compared with controls. In AD patients, both IL-31 and IL-33 serum levels were higher in children than in adults, while the opposite was the case for sST2. We observed no correlation between disease severity and any of the investigated targets. While serum TSLP levels were unaffected by concomitant allergies and atopic comorbidities, serum levels of IL-31, IL-33 and sST2 were affected to a small extent. We found a positive correlation between TSLP, IL-31 and IL-33, and an inverse relationship between IL-33 and sST2.

CONCLUSIONS

The studied targets hold little potential as indicators of disease severity. The serum values of our targets show robustness against atopic comorbidities, allergies and changes in disease severity. This robustness strengthens their potential use in biomarker-based stratification and could be instrumental in identifying subgroups and predicting the possible benefit of therapeutic and prevention approaches.

Guidelines of care for the management of atopic dermatitis: section 1. Diagnosis and assessment of atopic dermatitis

Atopic dermatitis (AD) is a chronic, pruritic, inflammatory dermatosis that affects up to 25% of children and 2% to 3% of adults. This guideline addresses important clinical questions that arise in the management and care of AD, providing updated and expanded recommendations based on the available evidence. In this first of 4 sections, methods for the diagnosis and monitoring of disease, outcomes measures for assessment, and common clinical associations that affect patients with AD are discussed. Known risk factors for the development of disease are also reviewed.

High frequencies of positive nickel/cobalt patch tests and high sweat nickel concentration in patients with intrinsic atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is classified into extrinsic AD with high serum IgE levels and impaired barrier, and intrinsic AD with low serum IgE levels and unimpaired barrier. Intrinsic AD has a lower frequency of FLG mutations and a higher frequency of circulating Th1 cells, implying that non-protein antigens, represented by metals, may be an exacerbation factor in intrinsic AD.

OBJECTIVE

To investigate metal allergy in intrinsic AD.

METHODS

Enrolled in this study were 86 Japanese AD patients seen in three university hospitals, consisting of 55 extrinsic and 31 intrinsic AD patients. Patch testing was performed, focusing on nickel, cobalt, and chrome, in parallel with other 14 metals. FLG mutations were analyzed in 49 patients (extrinsic, 29; intrinsic, 20). In 17 patients (extrinsic, 12; intrinsic, 5), sweat was collected from the forearms by exercise, and the concentration of nickel was fluorometrically measured.

RESULTS

Nickel, cobalt, and chrome were the major positive metals. Intrinsic AD showed significantly higher percentages of positive reactions than extrinsic AD to nickel (intrinsic 41.9% vs extrinsic 16.4%, P=0.019) and cobalt (38.7% vs 10.9%, P=0.005). There was no significant difference between FLG mutation-bearing and non-bearing patients. The concentration of nickel was higher in the sweat of intrinsic AD than extrinsic AD patients (333.8 vs 89.4ng/g, P=0.0005) and inversely correlated with serum IgE levels.

CONCLUSIONS

Nickel and cobalt allergy may be involved in intrinsic AD. Given that the metals are excreted through sweat, intrinsic AD might be exaggerated by highly metal-containing sweat.

A group of atopic dermatitis without IgE elevation or barrier impairment shows a high Th1 frequency: possible immunological state of the intrinsic type

BACKGROUND

Atopic dermatitis (AD) can be classified into the major extrinsic type with high serum IgE levels and impaired barrier, and the minor intrinsic type with normal IgE levels and unimpaired barrier.

OBJECTIVE

To characterize the intrinsic type of Japanese AD patients in the T helper cell polarization in relation to the barrier condition.

METHODS

Enrolled in this study were 21 AD patients with IgE<200kU/L (IgE-low group; 82.5±59.6kU/L) having unimpaired barrier, and 48 AD patients with IgE>500kU/L (IgE-high group; 8.050±10.400kU/L). We investigated filaggrin gene (FLG) mutations evaluated in the eight loci common to Japanese patients, circulating Th1, Th2 and Th17 cells by intracellular cytokine staining and flow cytometry, and blood levels of CCL17/TARC, IL-18, and substance P by ELISA.

RESULTS

The incidence of FLG mutations was significantly lower in the IgE-low group (10.5%) than the IgE-high group (44.4%) (normal individuals, 3.7%). The percentage of IFN-γ-producing Th1, but not Th2 or Th17, was significantly higher in the IgE-low than IgE-high group. Accordingly, Th2-attracting chemokine CCL17/TARC, was significantly lower in the IgE-low than the IgE-high group. There were no differences between them in serum IL-18 levels, or the plasma substance P levels or its correlation with pruritus.

CONCLUSION

The IgE-low group differed from the IgE-high group in that it had much less FLG mutations, increased frequency of Th1 cells, and lower levels of CCL17. In the intrinsic type, non-protein antigens capable of penetrating the unimpaired barrier may induce a Th1 eczematous response.

Serum and tissue CD23, IL-15, and FasL in cow's-milk protein-sensitive enteropathy and in coeliac disease

OBJECTIVES

The aim of the study was to explore pathogenesis and find new serum markers for cow's-milk-sensitive enteropathy (CMSE) and coeliac disease (CD). We assessed the intestinal expression and serum concentration of CD23, IL-15, and FasL. We hypothesised that the serum levels of CD23, a protein expressed in the lymphoid follicles, would be associated with lymphonodular hyperplasia (LNH), a feature characteristic of CMSE. We also presumed that interleukin (IL)-15 and FasL, functionally connected with proliferation and apoptosis of the intraepithelial lymphocytes (IELs), would relate with the increased numbers of IELs present in both CMSE and CD.

METHODS

Twenty-three children with CMSE, 20 with untreated CD, and 14 controls were studied for CD3, α/β- and γ/δ-expressing IELs, and for duodenal and ileal expression of CD23, FasL, and IL-15 by immunohistochemistry, and for serum concentration of sCD23, sFasL, and sIL-15 by enzyme-linked immunosorbent assay.

RESULTS

There was a trend for increase in sCD23 serum levels in untreated CMSE and in CD (P = 0.074; P = 0.077). CD23 was expressed in the mucosal germinal centres, but sCD23 was not related to presence of LNH. In CMSE, there was a trend for increase in serum sFasL (P = 0.07) and high levels associated with LNH (P = 0.025) and correlated with the IEL numbers (P < 0.05). Mucosal high endothelial venules adjacent to lymphoid follicles showed an intensive FasL expression.

CONCLUSIONS

Serum sCD23 shows a trend of increment in CMSE and CD, and in the latter, sCD23 level may provide information about the severity of villous atrophy. In CMSE, high serum sFasL indicates both LNH and an increase of IELs, suggesting importance of FasL-mediated mechanisms in the pathogenesis of these features characteristic of CMSE. Further studies are necessary to evaluate whether intensive FasL expression in mucosal high endothelial venules presents a regulatory element in mucosal immunity.

An association of TLR2–16934A >T polymorphism and severity/phenotype of atopic dermatitis

BACKGROUND

Toll-like receptor 2 gene (TLR2) –16934A>T polymorphism has been shown to be associated with severity of atopic dermatitis (AD) as measured using severity scoring of atopic dermatitis (SCORAD) index. Moreover, TLR2–16934A>T polymorphism has been associated with atopy and allergic disorders in farmers’ children.

OBJECTIVE

The aim of this study was to evaluate an association between TLR2–16934A>T polymorphism and AD phenotype, including disease severity and concomitant atopic diseases, or potential serum markers of AD severity and also to find a molecular background of the clinical associations.

METHODS

Genotyping for TLR2–16934A>T polymorphism was performed in 130 consecutive adult ambulatory patients with AD. Total serum (TS) IgE levels, serum tryptase, plasma interleukin-6 and C-reactive protein were measured. In addition, luciferase assay and electrophoretic-mobility shift assay were conducted to assess the effect of –16934A>T polymorphism on transcriptional activity.

RESULTS

There was an inverse association of TLR2–16934TT genotype and/or –16934T allele with SCORAD, but not with TS IgE, tryptase or inflammatory markers. Interestingly, –16934AA genotype and/or –16934A allele were overrepresented in AD patients with concomitant asthma or a family history of atopy. In a subgroup analysis, TLR2–16934A>T polymorphism was associated with SCORAD, asthma, allergic conjunctivitis or family history of atopy in AD patients with TS IgE ≥106 IU/mL but not in those having TS IgE <106 IU/mL. Functional analyses showed that TLR2–16934T allele is associated with higher luciferase activity in human monocytic THP-1 cells and preferential binding of the THP-1-derived nuclear protein.

CONCLUSION

TLR2–16934A>T polymorphism could be a genetic predictor of AD severity, the coexistence of asthma or atopic conjunctivitis as well as a family history of atopic diseases, especially in subjects having higher TS IgE. TLR2–16934A>T polymorphism affects transcriptional activity, which may at least in part account for the clinical associations observed for the –16934A>T polymorphism.

Soluble IgE receptors--elements of the IgE network

Soluble isoforms of three human IgE Fc receptors, namely FcεRI, FcεRII, and galectin-3, can be found in serum. These soluble IgE receptors are a diverse family of proteins unified by the characteristic of interacting with IgE in the extracellular matrix. A truncated form of the alpha-chain of FcεRI, the high affinity IgE receptor, has recently been described as a soluble isoform (sFcεRI). Multiple soluble isoforms of CD23 (sCD23), the low affinity IgE receptor also known as FcεRII, are generated via different mechanisms of extracellular and intracellular proteolysis. The second low affinity IgE receptor, galectin-3, only exists as a secretory protein. We here discuss the physiological roles of these three soluble IgE receptors as elements of the human IgE network. Additionally, we review the potential and current use of sFcεRI, sCD23, and galectin-3 as biomarkers in human disease.