Foxp3(+) regulatory T cells are expanded in severe atopic dermatitis patients

IL-4-induced decrease in both the number and CTLA-4 expression of Treg impairs suppression of Th2 type inflammation in severe atopic dermatitis

BACKGROUND

Treg plays a pivotal role in the suppression of Th2 cell and the maintenance of immune homeostasis. The precise molecular mechanism underlying the disruption of Treg suppression of Th2 cell and the promotion of Th2 type inflammation in allergic diseases remains elusive.

OBJECTIVE

This study aims to investigate the molecular mechanism underlying quantitative and functional changes of Treg in AD.

METHODS

The molecular mechanism was investigated using flow cytometry, mRNA sequencing, co-culture experiments, co-immunoprecipitation, chromatin immunoprecipitation, and bisulfite sequencing in vitro or in AD mice model and patients with AD.

RESULTS

Increased proportion of Treg was detected in mild and moderate AD. Conversely, characteristic decrease in both the number and CTLA-4 expression of Treg was relevant to serum IL-4 level in severe AD patients, which was verified under a high concentration of IL-4 treatment in vitro. The underlying mechanism is that IL-4/pSTAT6 pathway recruits DNMT1 and HDAC2 to inhibit transcriptional regulation of Foxp3 and CTLA-4 loci. High level of IL-4 impaired the suppression of Treg against Th2 cell differentiation mediated by CTLA-4, and blockade of IL-4Rα signaling in Treg restored Treg number and suppression of Th2 cell in AD model mice and patients with AD.

CONCLUSION

The number of Treg is relevant to stratification of severity and serum IL-4 level in patients with AD. Abnormal high level of IL-4 epigenetically triggers a decrease in both the number and CTLA-4 expression of Treg. The reduced expression of CTLA-4 on Treg induced by IL-4 impairs suppression of Th2 cell differentiation.

The Role of Regulatory T Cells in Allergic Diseases: Collegium Internationale Allergologicum (CIA) Update 2024

BACKGROUND

Allergy represents a major health problem of increasing prevalence worldwide with a high socioeconomic impact. Our knowledge on the molecular mechanisms underlying allergic diseases and their treatments has significantly improved over the last years. The generation of allergen-specific regulatory T cells (Tregs) is crucial in the induction of healthy immune responses to allergens, preventing the development and worsening of allergic diseases.

SUMMARY

In the last decades, intensive research has focused on the study of the molecular mechanisms involved in Treg development and Treg-mediated suppression. These mechanisms are essential for the induction of sustained tolerance by allergen-specific immunotherapy (AIT) after treatment discontinuation. Compelling experimental evidence demonstrated altered suppressive capacity of Tregs in patients suffering from allergic rhinitis, allergic asthma, food allergy, or atopic dermatitis, as well as the restoration of their numbers and functionality after successful AIT.

KEY MESSAGE

The better understanding of the molecular mechanisms involved in Treg generation during allergen tolerance induction might well contribute to the development of novel strategies for the prevention and treatment of allergic diseases.

Altered Gene Expression of IL-35 and IL-36α in the Skin of Patients with Atopic Dermatitis

A comprehensive understanding of atopic dermatitis (AD) pathogenesis is desired, especially in the current era of novel biologics and small molecule drugs. In recent years, new cytokines have emerged that may play a significant role in the pathogenesis of AD. Using the tape stripping (TS) method, this study analyzed the gene expression of IL-35 and IL-36α in lesional and nonlesional AD skin compared with healthy skin and their association with the clinical features of AD among the Polish population. Ten AD patients and seven healthy individuals were enrolled. The lesional skin of the AD patients showed significantly higher expression levels of IL-35 compared to healthy skin (p = 0.0001). The expression level of IL-36α was significantly higher in lesional AD skin than in nonlesional AD skin (p = 0.0039) and healthy skin (p = 0.0045). There was a significant negative correlation between AD severity and the expression level of IL-35 in both lesional (R = -0.66, p = 0.048) and nonlesional skin (R = -0.9, p = 0.0016). In summary, both IL-35 and IL-36α appear to play a role in the pathogenesis of AD. Furthermore, it might be speculated that IL-35 and IL-36α may be potential candidates for disease biomarkers. However, further studies are needed to verify these assumptions and comprehensively elucidate their importance in the pathogenesis of AD.

Antigen-specific T cell balance reveals Why patients with atopic dermatitis fail to achieve immune tolerance

The number of regulatory T cells (Tregs) and how they behave in the pathogenesis of atopic dermatitis (AD) are still controversial. We identified and quantified Tregs, mite-specific Tregs, and mite-specific effector T cells (Teffs) in patients with AD and healthy controls (HCs). We collected peripheral blood and analyzed the cells using flow cytometry after stimulation with mite antigens. Mite-specific Tregs and mite-specific Teffs were recognized by the expression of CD137 and CD154, respectively. Patients with AD had more Tregs than HCs; however, when focusing on a single antigen, the ratio of mite-specific Tregs/Teffs was lower in patients with AD than in HCs. Furthermore, the mite-specific Teffs in patients with AD were more likely to produce proinflammatory cytokines interleukin (IL)-4 and IL-13. This Teff-dominant imbalance is thought to be the cause of development of atopic status in patients with AD without immune tolerance.

Long-term effects of ciclosporin and oclacitinib on mediators of tolerance, regulatory T-cells, IL-10 and TGF-β, in dogs with atopic dermatitis

BACKGROUND

Atopic dogs often are managed with allergen-specific immunotherapy (AIT) and concurrent dosages of ciclosporin (CSA) or oclacitinib to alleviate their clinical signs. Both drugs might affect proper tolerance induction by inhibiting regulatory T-cell (Treg) induction.

HYPOTHESIS/OBJECTIVES

We evaluated Treg cell numbers and serum interleukin (IL)-10 and transforming growth factor-beta (TGF-β)1 levels in dogs diagnosed with atopic dermatitis (AD) and successfully treated with either CSA or oclacitinib for nine or more months.

ANIMALS

We included 15 dogs receiving oclacitinib, 14 dogs treated with CSA, 15 healthy dogs, 13 dogs with untreated moderate-to-severe AD and 15 atopic dogs controlled with AIT.

MATERIALS AND METHODS

Peripheral blood CD4+CD25+FOXP3+ T-cell percentages were determined using flow cytometry. Serum concentrations of IL-10 and TGF-β1 were measured by enzyme-linked immunosorbent assay.

RESULTS

The percentage of Treg cells in the CSA group was significantly lower in comparison with the healthy group (p = 0.0003), the nontreated AD group (p = 0.0056) or the AIT group (p = 0.0186). There was no significant difference in Treg cell percentages between the CSA and oclacitinib groups, nor between the oclacitinib and the healthy, nontreated AD or AIT-treated dogs. No significant differences were detected in IL-10 and TGF-β1 serum concentrations between the five groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Lower Treg cell percentages in the CSA-treated dogs suggest an impact of this drug on this cell population; however, it does not necessarily mean that it diminishes tolerance. Functionality and cytokine production may be more important than the number of Treg cells. Further studies evaluating the treatment outcome of dogs receiving AIT and concurrent drugs are needed to show clinical relevance.

Effect of early postnatal supplementation of newborns with probiotic strain E. coli O83:K24:H31 on allergy incidence, dendritic cells, and microbiota

Introduction

Probiotic administration seems to be a rational approach to promote maturation of the neonatal immune system. Mutual interaction of the microbiota with the host immune system is critical for the setting of appropriate immune responses including a tolerogenic one and thevmaintenance of homeostasis. On the other hand, our knowledge on the modes of actions of probiotics is still scarce.

Methods

In our study, probiotic strain Escherichia coli O83:K24:H31 (EcO83) was administered to neonates of allergic mothers (AMs; neonates with increased risk for allergy development) within 48 h after the delivery, and the impact of this early postnatal supplementation on allergy incidence and selected immune markers has been analyzed 10 years after the primary EcO83 administration.

Results

We have observed decreased allergy incidence in 10-year-old children supplemented with EcO83 (13 of 52 children were allergic) in comparison with non-supplemented children of AMs (16 of 42 children were allergic). The early postnatal EcO83 supplementation appeared to limit the allergy in the high-risk group (children of AMs) compared to that in the low-risk group (children of healthy mothers). Dendritic cells (DCs) in the peripheral blood of EcO83-supplemented children do not differ significantly in cell surface presence of CD83. The immunomodulatory capacity of EcO83 on DCs was tested in vitro as well. Both directly isolated myeloid and in vitro monocyte-derived DCs from cord blood increased CD83 expression together with interleukin (IL)-10 secretion after EcO83 stimulation. The effect of early postnatal EcO83 supplementation on the microbiota composition of 10-year-old children was characterized by next-generation sequencing, and we have not observed significant changes in the microbiota composition of EcO83-supplemented and non-supplemented children at the age of 10 years.

Conclusions

Early postnatal EcO83 supplementation appears to lower allergy incidence in children of AMs. It seems that the beneficial effect of EcO83 is mediated via modulation of DC functional capacities without impacting the microbiota composition. Larger-scale studies will be necessary to confirm these preliminary findings.

Immunization with a Pneumococcal pep27 Mutant Strain Alleviates Atopic Dermatitis through the Upregulation of Regulatory T-Cell Activity and Epithelial Barrier Function and Suppressing TSLP Expression

Atopic dermatitis (AD) is an inflammatory disease driven in part by type 2 helper T (Th2) cytokines and skin barrier disruption alleviating the entry of allergens. Thymic stromal lymphopoietin (TSLP), an epithelial cell‒derived cytokine, is known to aggravate AD symptoms by activating Th2. In addition, regulatory T cells (Tregs) inhibit inflammatory cells such as Th2. However, the relationship between TSLP and Tregs in AD is unclear. A murine dermatitis model was induced by applying oxazolone to the ear skin of mice. Prophylactic and therapeutic responses were analyzed by immunizing mice intranasally with a pneumococcal pep27 mutant (Δpep27 mutant), attenuated strain by reducing the virulence of a pathogen. Intranasal immunization with a pneumococcal pep27 mutant could elicit anti-inflammatory Treg-relevant factors and epithelial barrier genes (loricrin, involucrin, filaggrin, and small proline-rich repeat proteins). Thus, pneumococcal pep27-mutant immunization suppressed epidermal collapse, IgE, TSLP, and upregulation of Th2 expression by upregulating Treg activity. In contrast, Treg inhibition aggravated AD symptoms through the upregulation of TSLP and Th2 and the repression of epithelial barrier function compared with that of the noninhibited pneumococcal Δpep27-mutant group. Taken together, immunization with pneumococcal Δpep27 mutant upregulated Treg and epithelial barrier function and inhibited TSLP and Th2 to relieve AD symptoms.

Current Insight into the Role of IL-35 and Its Potential Involvement in the Pathogenesis and Therapy of Atopic Dermatitis

Interleukin 35 (IL-35), a new member of the IL-12 family of heterodimeric cytokines, could induce two different types of regulatory cells including regulatory T and B cells such as IL-35-induced regulatory T cells and IL-10-producing regulatory B cells (IL-10+Bregs), and IL-35-producing regulatory B cells (IL-35+Bregs). These cells appear to play an important role in modulating the immune system in numerous diseases. Several findings suggested that the expression of IL-35 is dysregulated in many autoimmune, inflammatory, and allergic diseases. Due to the functions of IL-35, it seems that this cytokine may act as an efficient therapeutic strategy for numerous conditions including atopic dermatitis (AD). We aimed to provide a comprehensive overview of the role of IL-35 in modulating the immune system. Additionally, we highlight IL-35 as a specific immunological target, discuss its possible involvement in the pathogenesis of AD, and hypothesize that IL-35 may become a novel target for the treatment of AD. However, further studies are required to evaluate this hypothesis.

Therapeutic effect of chinese herbal medicine gu-ben-hua-shi (AESS) formula on atopic dermatitis through regulation of yes-associated protein

Background: Atopic dermatitis (AD) is a chronic and recurrent skin disease. At present, there is a lack of sufficiently effective and safe medicines that can be used for a prolonged time and reduce the recurrence of AD. The Gu-Ben-Hua-Shi (AESS) formula has been used for many years with a good clinical effect on AD but its specific treatment mechanism is unknown.

Methods: The main components of AESS were analyzed using ultra-high performance liquid chromatography (UPLC). The composition of AESS compounds in the serum from rats was analyzed using ultra-high performance liquid chromatography-mass spectrometry. An AD mouse model was constructed using 2,4-dinitrofluorobenzene stimulation in Balb/C mice and the effect on the reduction of skin lesions and Th1/Th2/Th17/Treg balance after AESS administration were measured. The effects of AESS serum on the proliferation and apoptosis of keratinocyte cell line HaCaT and adhesion of HaCaT to human monocyte cell line THP-1 were detected in an IFN-γ/TNF-α stimulated AD-like inflammatory cell model. The effects of Yes-associated protein (YAP) expression on the therapeutic effect and a related signaling pathway were also investigated.

Results: In total, 10 components were confirmed using UPLC, namely five organic acids, three flavonoids, and two chromogenic ketones. Additionally, the similarity of the three batches of samples (S1–3) was above 0.98, indicating that the formula samples have good uniformity. These 10 compounds were also detected in rat serum, suggesting that they are absorbed into rat blood as prototype components. Furthermore, AESS effectively reduced the skin lesions in the AD mouse model, regulated the Th1/Th2/Th17/Treg imbalance, improved the proliferation ability of the AD-like cell model, and inhibited HaCaT apoptosis and adhesion to THP-1 cells. It also reduced the expression of YAP in Th17 and Treg cells of the mouse spleen and increased YAP expression in the skin. The change in YAP expression in keratinocytes weakened the curative effect of AESS, and AESS exerted its effects through the NF-κB signaling pathway.

Conclusion: AESS may play a role in the treatment of AD by affecting the expression of YAP. These findings can be used to promote its use as an alternative medication for prolonged use with fewer side effects.

Post-Translational Modifications in Atopic Dermatitis: Current Research and Clinical Relevance

Atopic dermatitis (AD) is a chronic and relapsing cutaneous disorder characterized by compromised immune system, excessive inflammation, and skin barrier disruption. Post-translational modifications (PTMs) are covalent and enzymatic modifications of proteins after their translation, which have been reported to play roles in inflammatory and allergic diseases. However, less attention has been paid to the effect of PTMs on AD. This review summarized the knowledge of six major classes (including phosphorylation, acetylation, ubiquitination, SUMOylation, glycosylation, o-glycosylation, and glycation) of PTMs in AD pathogenesis and discussed the opportunities for disease management.

Expression of Helper and Regulatory T Cells in Atopic Dermatitis: A Meta-Analysis

BACKGROUND

Atopic dermatitis (AD) is a common inflammatory skin disease, with the incidence peaks in infancy. A meta-analysis was performed to assess the levels of T helper type 22 (Th22) cells, T helper type 17 (Th17) cells, interleukin (IL)-17, and Tregs in peripheral blood of patients with AD.

METHODS

A comprehensive literature search was performed in PubMed, Embase, China National Knowledge Internet, and Wan-fang Data from the day of inception of this study to July 2021. Two authors independently extracted the data, which were pooled and calculated using Stata software version 15.

RESULTS

A total of eight studies met the inclusion criteria. Compared with control group, patients with AD had an increased proportion of Th22 cells [weighted mean difference (WMD) = 2.07, 95% CI (1.33, 2.81), p < 0.001], Th17 cells [WMD = 1.04, 95% CI [0.66, 1.43], p < 0.001], IL-17 [WMD = 17.56, 95% CI (11.1, 24.03), p < 0.001], and a decreased proportion of Tregs [WMD = -2.49, 95% CI (-2.93, -2.05), p < 0.001] in peripheral blood. The subgroup analysis showed that patients with higher disease severity had higher levels of Th22 [mild: WMD = 1.33, 95% CI (1.24, 1.41), p < 0.001; moderate: WMD = 1.41, 95% CI (1.36, 1.54), p < 0.001; severe: WMD = 3.46, 95% CI (3.34, 2.81), p < 0.001] and lower levels of Tregs [mild: WMD = -1.43, 95% CI (-1.75, -1.11), p < 0.001; moderate: WMD = -2.16, 95% CI (-2.46, -1.86), p < 0.001; severe: WMD = -2.96, 95% CI (-3.25, -2.67), p < 0.001] in peripheral blood compared to healthy controls.

CONCLUSION

The random effect model of the meta-analysis showed patients with AD had an increased proportion of Th22 cells, Th17 cells, and IL-17, whereas a decreased proportion of Tregs was found in peripheral blood. The results demonstrated that Th22 cells, Th17 cells, IL-17, and Tregs may be involved in the pathogenic mechanisms of AD.

Possible Role of Leptin in Atopic Dermatitis: A Literature Review

Atopic dermatitis (AD) is the most frequent chronic inflammatory skin disease, and its incidence has been rapidly increasing in developed countries in the last years. AD presents a high degree of heterogeneity due to biases and confounding factors such as age range, sex, or ethnicity. For those reasons, the search for new biomarkers is crucial. At the same time, obesity, which is a global health problem, has also increased over the years. It has been associated with many pathophysiological states, including skin diseases such as AD, mostly in childhood. Obesity promotes a low grade inflammation driven by many different cytokines and adipokines, including leptin, which has a key role in many other diseases due to its pleiotropic effects. Leptin also has a role in both skin and allergic diseases very related to AD. Thus, this adipokine could have an important role in the pathogenesis of AD, especially in its chronicity. Despite the limited literature available, there is some evidence that leads us to consider leptin as an important adipokine in this skin disease. For this reason, here we have reviewed the role of leptin in the pathophysiology of AD.

Targeted DNA methylation profiling reveals epigenetic signatures in peanut allergy

DNA methylation (DNAm) has been shown to play a role in mediating food allergy; however, the mechanism by which it does so is poorly understood. In this study, we used targeted next-generation bisulfite sequencing to evaluate DNAm levels in 125 targeted highly informative genomic regions containing 602 CpG sites on 70 immune-related genes to understand whether DNAm can differentiate peanut allergy (PA) versus nonallergy (NA). We found PA-associated DNAm signatures associated with 12 genes (7 potentially novel to food allergy, 3 associated with Th1/Th2, and 2 associated with innate immunity), as well as DNAm signature combinations with superior diagnostic potential compared with serum peanut–specific IgE for PA versus NA. Furthermore, we found that, following peanut protein stimulation, peripheral blood mononuclear cell (PBMCs) from PA participants showed increased production of cognate cytokines compared with NA participants. The varying responses between PA and NA participants may be associated with the interaction between the modification of DNAm and the interference of environment. Using Euclidean distance analysis, we found that the distances of methylation profile comprising 12 DNAm signatures between PA and NA pairs in monozygotic (MZ) twins were smaller than those in randomly paired genetically unrelated individuals, suggesting that PA-related DNAm signatures may be associated with genetic factors.

Atopic dermatitis in West Highland white terriers - Part III: early life peripheral blood regulatory T cells are reduced in atopic dermatitis

BACKGROUND

Regulatory T (Treg) cells are involved in homeostasis of immune regulation and suppression of inflammation and T-cell polarisation. Current knowledge regarding the role of Treg cells in the initiation of allergic disease is limited for both people and dogs.

OBJECTIVES

To explore the role of circulating Treg cells and their possible influencing factors, on the development of atopic dermatitis (AD).

METHODS AND MATERIALS

This study followed part of a birth cohort of West Highland white terrier dogs and classified them according to eventual clinical signs of AD (i.e. allergic versus healthy). The Treg phenotypes were assessed longitudinally by flow cytometry at 3, 3-12 and 12-36 months of age, and associated with development of AD. Different early life antigenic factors [endotoxins and allergens in house dust, Toxocara canis-specific immunoglobulin (Ig)E/IgG, allergen-specific and total IgE, skin microbiota] were measured at three months of age, and a possible association with Treg cell levels was assessed.

RESULTS

The percentages of CD4⁺ CD25⁺ Foxp3⁺ Treg cells in healthy dogs were significantly higher at in 3-month-old (mean 4.5% healthy versus 3.3% allergic; P = 0.021) and <1-year-old (4.0% healthy versus 2.9% allergic; P = 0.028) dogs when compared to percentages of Treg cells in dogs that developed AD. There was a significantly positive correlation between the relative abundance of Lachnospiraceae on the skin and CD4⁺ CD25⁺ Foxp3⁺ Treg cells in puppies that became allergic (r = 0.568, P = 0.017).

CONCLUSION AND CLINICAL IMPORTANCE

Further large-scale studies are needed to identify the practical value of these findings in AD diagnosis, treatment and prevention.

Increased Frequency of CTLA-4 and PD-1 Expressing Regulatory T Cells and Basophils With an Activating Profile in Infants With Moderate-to-Severe Atopic Dermatitis Hypersensitized to Food Allergens

Background: Infants with severe atopic dermatitis (AD) may be sensitized to foods that have not been introduced into their diet, posing a risk for developing an immediate hypersensitivity reaction on the first exposure to the food to which they are sensitized. The aim of this work was to perform an analysis of the sensitization profile in infants with moderate-to-severe AD and to identify cellular and molecular markers for food allergy (FA). Methods: Blood samples from healthy donors and children with moderate-to-severe AD were studied. Specific IgE to several allergens were determined using ImmunoCAP FEIA system and ISAC technology. Furthermore, using flow cytometry-based studies, basophils and regulatory T (Treg) cells were phenotypically characterized. Results: 90% of children with AD were sensitized to food antigens before introducing them into the diet, and 100% developed FA. Phenotypic analysis showed a significantly higher percentage of CTLA-4 and PD-1 expressing Treg cells in AD patients than in healthy controls. Basophils from patients exhibited a marked reduction in the expression of CD300a, higher expression of FcεRI and CXCR4, and to some extent higher expression of CD63 and CD300c. Conclusions: Infants with moderate-to-severe AD are at high risk of being sensitized to food allergens. Therefore, to avoid allergic reactions, broad-spectrum sensitization studies are necessary before introducing complementary diet. Increased expression of CTLA-4 and PD-1 suggests greater suppressive potential of Treg cells in infants with AD than healthy controls. Furthermore, our results suggest a role for CD300 molecules on circulating basophils as possible biomarkers for FA susceptibility.

Role of YAP-related T cell imbalance and epidermal keratinocyte dysfunction in the pathogenesis of atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is characterized by impaired skin barrier function and immune system dysfunction. The expression and role of Yes-associated protein (YAP) in AD are unclear.

OBJECTIVE

To characterize the role of the YAP in T cell imbalance and epidermal keratinocyte dysfunction in the pathogenesis of AD.

METHODS

We included 35 patients with AD (21 acute and 14 chronic). An AD mouse model was constructed using 2,4-dinitrofluorobenzene, and AD-like inflammatory cell model was constructed using TNF-α/IFN-γ-activated HaCaT cells. The proportion of Th1/Th2/Th17/Treg cells was detected using flow cytometry. After mononuclear cells were obtained from human peripheral blood or mouse spleen and induced to differentiate into different T cell subsets, YAP mRNA and protein expression were analyzed. Up-regulation of YAP was induced by lentivirus and down-regulation of YAP was induced by its specific inhibitor verteporfin (VP). The expression of YAP in skin lesions and infiltrating T cell subsets was detected using immunohistochemistry and double immunofluorescence staining, respectively.

RESULTS

We found differing degrees of Th1/Th2/Th17/Treg imbalance in acute and chronic AD. YAP expression was downregulated in Treg cells and upregulated in Th17 cells; YAP expression was downregulated in the AD epidermis. After YAP overexpression, the proportion of both Th17 and the Treg cells differentiated from mouse spleen mononuclear cells increased. There was an opposite trend after YAP inhibition. The proliferation and migration decreased and apoptosis increased after YAP inhibition in HaCaT cells.

CONCLUSION

Change of YAP expression may cause T cell imbalance and hamper the healing of the epidermis in AD.

3'-Sialyllactose prebiotics prevents skin inflammation via regulatory T cell differentiation in atopic dermatitis mouse models

3'-Sialyllactose (3'-SL), a natural prebiotic, maintains immune homeostasis and exerts anti-inflammatory and anti-arthritic effects. Although regulatory T cells (Tregs) prevent excessive inflammation and maintain immune tolerance, the effect of 3'-SL on Treg regulation is unclear. This study aimed to investigate the effect of 3'-SL on Treg responses in atopic dermatitis (AD) pathogenesis. Oral administration of 3'-SL reduced AD-like symptoms such as ear, epidermal, and dermal thickness in repeated topical application of house dust mites (HDM) and 2,4-dinitrochlorobenzene (DNCB). 3'-SL inhibited IgE, IL-1β, IL-6, and TNF-α secretion and markedly downregulated AD-related cytokines including IL-4, IL-5, IL-6, IL-13, IL-17, IFN-γ, TNF-α, and Tslp through regulation of NF-κB in ear tissue. Additionally, in vitro assessment of Treg differentiation revealed that 3'-SL directly induced TGF-β-mediated Treg differentiation. Furthermore, 3'-SL administration also ameliorated sensitization and elicitation of AD pathogenesis by suppressing mast cell infiltration and production of IgE and pro-inflammatory cytokines in mouse serum by mediating the Treg response. Furthermore, Bifidobacterium population was also increased by 3'-SL administration as prebiotics. Our data collectively show that 3'-SL has therapeutic effects against AD progression by inducing Treg differentiation, downregulating AD-related cytokines, and increasing the Bifidobacterium population.

In vitro Conversion into CD4+CD25+Foxp3+ Induced Regulatory T Cells Is Reduced in Atopic Dermatitis Patients

BACKGROUND

Atopic dermatitis (AD) is one of the most common inflammatory skin diseases, with an increasing incidence in clinical practice. AD models have demonstrated that TGF-β signaling is compromised in regulatory T cells (Tregs).

OBJECTIVES

This study aimed to investigate the TGF-β-dependent in vitro conversion of CD4+CD25- T cells derived from AD-patients into CD4+CD25+Foxp3+ induced Tregs (iTregs) in comparison to healthy controls.

METHODS

To analyze in vitro iTreg conversion, human CD4+CD25- T cells were cultured on anti-CD3-coated plates in the presence of TGF-β and IL-2 for up to 3 days. Consequently, the underlying mechanism of impaired CD4+CD25+Foxp3+ iTreg generation was explored by focusing on TGF-β signaling. Finally, the functionality of iTregs was investigated.

RESULTS

Conversion of CD4+CD25-Foxp3- into CD4+CD25+Foxp3+ iTregs was diminished in AD individuals. Impaired iTreg generation was accompanied by a reduced surface expression of GARP (glycoprotein A repetitions predominant), a marker for activated Tregs. A reduced expression of Smad3 mRNA was revealed in CD4+CD25- T cells. Interestingly, the suppressive quality of iTregs was found to be equal in cells derived from AD and healthy donors.

CONCLUSION

The signaling effect of TGF-β receptors on the suppressor quality of iTreg conversion is conserved. Impaired iTreg generation might be a reason for the lack of immune suppression in AD patients and contributes to the chronicity of the disease.

Correlation of Blood FoxP3+ Regulatory T Cells and Disease Activity of Atopic Dermatitis

Objectives

To investigate CD4+CD25+FoxP3+ T regulatory cells (Tregs) in the peripheral blood of patients with atopic dermatitis (AD) and its correlation with disease severity.

Methods

Blood samples from 79 AD patients before and after four-week conventional treatment were collected. Cell counts of CD4+CD25+FoxP3+Tregs, CD4+CD25+FoxP3-T effector cells (Teffs), and CD4+IL-10+Tregs were analyzed by flow cytometry. Serum levels of IL-4, IL-10, IL-12, IL-13, IFN-γ, and TGF-β were measured by ELISA.

Results

The pretreatment cell count of CD4+CD25+FoxP3+Tregs positively correlated with disease severity in all patients (P < 0.0001). However, when that correlation was rechecked based on the treatment response, a much stronger correlation of that was found in those patients with remission after treatment, while no correlation of that was found in patients without remission. Both the cell count and proportions of peripheral CD4+CD25+FoxP3+Tregs and CD4+CD25+FoxP3-Teffs reduced significantly after treatment in patients with remission, but remained unchanged in patients without remission. The cell count and proportion of CD4+IL-10+Tregs did not change after treatment in both groups. In patients with remission, serum levels of IL-4 and IL-13 significantly reduced (all P < 0.05); IL-12 and IFN-γ levels increased significantly (all P < 0.05); IL-10 and TGF-β levels remained unchanged after treatment. None of those cytokine levels changed in patients without remission.

Conclusions

CD4+CD25+FoxP3+Tregs is associated with AD development and severity in some patients but not in others. AD maybe divided into CD4+CD25+FoxP3+Treg-associated subtype, which CD4+CD25+FoxP3+Treg is parallel to the activity of AD, and nonassociated subtype, which CD4+CD25+FoxP3+Treg is not related. This subgroup difference may contribute partly to the nonidentical markers that have been found in AD and should be studied further.

Autoreactive T-Lymphocytes in Inflammatory Skin Diseases

The presence of one or several autoantigen(s) and a response by the adaptive immune system are the key criteria to classify a pathology as an autoimmune disease. The list of entities fulfilling this criterion is currently growing in the light of recent advancements in the pathogenetic understanding of a number of important dermatoses. The role of autoreactive T-lymphocytes differs amongst these pathologies. While they are directly involved as effector cells attacking and sometimes killing their respective target in some diseases (e.g., vitiligo), they provide help to B-lymphocytes, which in turn produce the pathogenic autoreactive antibodies in others (pemphigus and pemphigoid). Atopic dermatits is a chimera in this regard, as there is evidence for both functions. Psoriasis is an example for an entity where autoantigens were finally identified, suggesting that at least a subgroup of patients should be classified as suffering from a true autoimmune rather than autoinflammatory condition. Identification of resident memory T-lymphocytes (T_RM) helped to understand why certain diseases relapse at the same site after seemingly effective therapy. Therefore, the in-depth characterization of autoreactive T-lyphocytes goes way beyond an academic exercise and opens the door toward improved therapies yielding durable responses. T_RM are particularly suitable targets in this regard, and the clinical efficacy of some established and emerging therapeutic strategies such as the inhibition of Janus Kinase 3 or interleukin 15 may rely on their capacity to prevent T_RM differentiation and maintenance. Research in this field brings us closer to the ultimate goal in the management of autoimmunity at large, namely resetting the immune system in order to restore the state of tolerance.

Immune dysregulation and Th2 polarization are associated with atopic dermatitis in heart-transplant children: A delicate balance between risk of rejection or atopic symptoms

Atopic dermatitis (AD) has a high incidence in heart-transplant children, and the reason why there is more AD after transplantation is still unknown. We conducted a cross-sectional study comparing 11 AD and 11 non-AD age-matched heart-transplant children, to assess which immune alterations are related to AD in these patients. AD patients had been transplanted at a younger age compared to non-AD, indicating that age at transplant may be determinant in the onset of AD. The earlier thymectomy in AD heart-transplant children favored the presence of more differentiated phenotypes in the T cell compartment. We observed a clear reduction in the T-helper 1/T-helper 2 (Th1/Th2) ratio in AD children. This Th2 polarization was related to eosinophilia and high immunoglobulin E levels, but also to an impaired regulatory T cell (Treg) suppression, which could be secondary to an exhaustion of the Treg compartment. Interestingly, AD patients were free of rejection episodes (0/11) in comparison to non-AD children (4/11). We propose that a predominant Th2 phenotype may prevent the emergence of Th1 responses associated with graft rejection. A more differentiated Treg phenotype could also play a role in preventing acute rejection in the first year posttransplant. Our findings provide useful insights and knowledge for the better understanding of atopic disorders in transplanted children.

A Nationwide, Population-based Cohort Study on Potential Autoimmune Association of Ménière Disease to Atopy and Vitiligo

Ménière disease (MD), an idiopathic disorder of sensorineural hearing loss and vertigo, shares many similarities with two common skin conditions, atopic dermatitis (AD) and vitiligo. Recent studies have suggested that MD may be related to or triggered by autoimmune conditions, notably Hashimoto thyroiditis and alopecia areata. These evidences led to the authors contemplating the possibility of immunological bridge between MD and the two skin conditions. The authors have tested this hypothesis with population-based cohort from the National Health Insurance Service Database of Korea. A cohort of 1.1 million patients was extracted from the database. Using χ² tests, prevalence of the two skin disorders in relation to MD status was analysed. In MD patients, the odds ratios for having concurrent AD and vitiligo were 0.717 (95% CI, 0.535–0.962, p = 0.026) and 2.149 (95% CI, 1.396–3.308, p = 0.001), respectively. Females and older patients were more than twice likely to be affected by the two skin conditions. The relationship between vitiligo and MD was significant in younger subgroup only. Socio-economic subgroup analysis revealed the observed patterns are primarily a middle-upper class phenomenon. Uncertainty regarding temporal sequence of onset, and lack of detail on disease severity and subtype kept the study from more refined conclusion. In concluding, AD and vitiligo might be linked to MD through T_reg-driven action of cellular immunity, but further big data-based investigations must follow.

Regulatory cells in the skin: Pathophysiologic role and potential targets for anti-inflammatory therapies

Inflammation is a fundamental defense mechanism to protect the body from danger, which becomes potentially harmful if it turns chronic. Therapeutic strategies aimed at specifically blocking proinflammatory signals, particularly cytokines, such as IL-4, IL-6, IL-13, IL-17A, or TNF-α, have substantially improved our ability to effectively and safely treat chronic inflammatory diseases. Much less effort has been made to better understand the role of potential anti-inflammatory mechanisms. Here we summarize the current understanding of regulatory cell populations in the context of chronic inflammation, namely macrophages, Langerhans cells, myeloid-derived suppressor cells, and regulatory T and B lymphocytes. Emphasis is given to the skin because many different immune-related diseases occur in the skin. Development, phenotype, function, and evidence for their role in animal models of inflammation, as well as in the corresponding human diseases, are described. Finally, the feasibility of using regulatory cells as targets for potentially disease-modifying therapeutic strategies is discussed.

Filaggrin null mutations are associated with altered circulating Tregs in atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease with a complex pathogenesis. Although regulatory T cells (Tregs) have previously been studied in AD, their role remains controversial, likely owing to patient heterogeneity. Thus, we recruited adult AD patients and age‐matched healthy controls, and assessed their filaggrin (FLG) genotype, serum IgE level, and eczema area and severity index (EASI). We found increased proportions of all circulating Treg subpopulations in AD patients. Moreover, we show positive correlations between circulating Tregs and serum IgE FLG null mutations limited the expansion of both memory and effector Tregs and enhanced that of recently thymus‐emigrated Tregs. Furthermore, proportions of circulating Th2‐ or Th17‐Tregs but not Th1‐Tregs were increased in AD patients, and accentuated by FLG null mutations, thereby mimicking the immune deviation observed in Th cell populations. Moreover, ICOS⁺ Tregs showed reduced production of interleukin‐10, suggesting impaired immunosuppression in AD. The level of demethylation of FOXP3i1, which reflects the stability of FOXP3 expression, was similar in the blood and skin of AD patients and healthy controls. Overall, these results show that Tregs may participate into AD pathogenesis and that FLG null mutations exert further modifications on specific subpopulations of circulating Tregs.

Forkhead box protein 3 demethylation is associated with tolerance induction in peanut-induced intestinal allergy

BACKGROUND

Regulatory T (Treg) cells play an essential role in the maintenance of immune homeostasis in allergic diseases.

OBJECTIVES

We sought to define the mechanisms underlying induction of tolerance to peanut protein and prevention of the development of peanut allergy.

METHODS

High or low doses of peanut extract were administered to pups every day for 2 weeks before peanut sensitization and challenge. After challenge, symptoms, Treg cell numbers, and forkhead box protein 3 (Foxp3), TH2 and TH17 cytokine, and Tgfβ expression in mesenteric lymph node (MLN) CD4+ T cells and jejunum were monitored. Treg cell suppressive activity and Foxp3 methylation in MLN CD4+ T cells were assayed.

RESULTS

Feeding high but not low doses of peanut before sensitization induced tolerance, as demonstrated by prevention of diarrhea and peanut-specific IgE responses, increases in the percentage of CD4+CD25+FoxP3+ cells in MLNs, and Foxp3 mRNA and protein expression in CD4+ cells from MLNs or jejunum. Feeding high doses of peanut before sensitization decreased percentages of CD3+CD4+IL-13+ and CD3+CD4+IL-17+ cells in MLNs and decreased Il13 and Il17a and increased Tgfβ mRNA expression in the jejunum; numbers of CD103+ dendritic cells in MLNs were significantly increased. Treg cell suppression was shown to be antigen specific. Foxp3 methylation was increased in peanut extract-sensitized and challenged mice, whereas in tolerized mice levels were significantly reduced.

CONCLUSIONS

Feeding high doses of peanut to pups induced tolerance to peanut protein. Foxp3 demethylation was associated with tolerance induction, indicating that Treg cells play an important role in the regulation of peanut sensitivity and maintenance of immune homeostasis.

Probiotics as a Potential Immunomodulating Pharmabiotics in Allergic Diseases: Current Status and Future Prospects

The prevalence of allergic disorders has dramatically increased over the past decade, particularly in developed countries. Apart from gastrointestinal disorders, neoplasia, genital and dermatological diseases etc., dysregulation of gut microbiota (dysbiosis) has also been found to be associated with increased risk of allergies. Probiotics are increasingly being employed to correct dysbiosis and, in turn, to modulate allergic diseases. However, several factors like strain variations and effector metabolites or component of them in a bacterial species can affect the efficacy of those as probiotics. On the other hand, host variations like geographical locations, food habits etc. could also affect the expected results from probiotic usage. Thus, there is a glaring deficiency in our approach to establish probiotics as an irrefutable treatment avenue for suitable disorders. In this review, we explicate on the reported probiotics and their effects on certain allergic diseases like atopic dermatitis, food allergy and asthma to establish their utility. We propose possible measures like elucidation of effector molecules and functional mechanisms of probiotics towards establishing probiotics for therapeutic use. Certain probiotics studies have led to very alarming outcomes which could have been precluded, had effective guidelines been in place. Thus, we also propose ways to secure the safety of probiotics. Overall, our efforts tend to propose necessary discovery and quality assurance guidelines for developing probiotics as potential immunomodulatory ‘Pharmabiotics.’

The role of regulatory T cells and genes involved in their differentiation in pathogenesis of selected inflammatory and neoplastic skin diseases. Part II: The Treg role in skin diseases pathogenesis

Regulatory FOXP3+ T cells (Tregs) constitute 5% to 10% of T cells in the normal human skin. They play an important role in the induction and maintenance of immunological tolerance. The suppressive effects of these cells are exerted by various mechanisms including the direct cytotoxic effect, anti-inflammatory cytokines, metabolic disruption, and modulation of the dendritic cells function. The deficiency of Treg cells number or function are one of the basic elements of the pathogenesis of many skin diseases, such as psoriasis, atopic dermatitis, bacterial and viral infections. They also play a role in the pathogenesis of T cell lymphomas of the skin (cutaneous T cell lymphomas - CTCL), skin tumors and mastocytosis. Here, in the second part of the cycle, we describe dysfunctions of Tregs in selected skin diseases.

Clinical Signs, Staphylococcus and Atopic Eczema-Related Seromarkers

Childhood eczema or atopic dermatitis (AD) is a distressing disease associated with pruritus, sleep disturbance, impaired quality of life and Staphylococcus aureus isolation. The pathophysiology of AD is complex and various seromarkers of immunity are involved. We investigated if anti-staphylococcal enterotoxin IgE (anti-SE), selected seromarkers of T regulatory (Treg), T helper (Th) and antigen-presenting cells (APC) are associated with clinical signs of disease severity and quality of life. Disease severity was assessed with the Scoring Atopic Dermatitis (SCORAD) index, and quality of life with the Children's Dermatology Life Quality Index (CDLQI) in AD patients ≤18 years old. Concentrations of anti-staphylococcus enterotoxin A and B immunoglobulin E (anti-SEA and anti-SEB), selected Treg/Th/APC chemokines, skin hydration and transepidermal water loss (TEWL) were measured in these patients. Forty patients with AD [median (interquartile range) age of 13.1 (7.9) years) were recruited. Backward stepwise linear regression (controlling for age, personal allergic rhinitis and asthma, and other blood markers) showed the serum anti-SEB level was positively associated with S. aureus and S. epidermidis isolations, objective SCORAD, clinical signs and CDLQI. TNF-α (a Th1 cytokine) was positively associated with objective SCORAD (B = 4.935, p = 0.010), TGF-β (a Treg cytokine) negatively with disease extent (B = -0.015, p = 0.001), IL-18 (an APC cytokine) positively with disease extent (B = 0.438, p = 0.001) and with TEWL (B = 0.040, p = 0.010), and IL-23 (an APC cytokine) negatively with disease extent (B = -2.812, p = 0.006) and positively with pruritus (B = 0.387, p = 0.007).

CONCLUSIONS

Blood levels of anti-SEB, Th1, Treg and APC cytokines are correlated with various clinical signs of AD. AD is a systemic immunologic disease involving Staphylococcus aureus, cellular, humoral, cytokine and chemokine pathophysiology.

The impact of langerin (CD207)+ dendritic cells and FOXP3+ Treg cells in the small bowel mucosa of children with celiac disease and atopic dermatitis in comparison to children with functional gastrointestinal disorders

In the present study we aimed to evaluate the impact of langerin (CD207)+ dendritic cells (DCs) and FOXP3+ Treg cells in the intestinal mucosa of children with celiac disease (CD) and atopic dermatitis (AD) in comparison to children with functional gastrointestinal disorders (FGD). Seventy-five children (37 male, mean age 8.4 ± 4.8 years), who randomly underwent small bowel biopsy, were studied. The CD was diagnosed in 14 children, including five persons with concomitant AD (all positive for anti-tissue transglutaminase IgA antibodies and with small bowel atrophy). Normal small bowel mucosa was found in eight patients with AD and in 53 patients with FGD. The sera of all patients were tested for total and specific IgE antibodies to food allergen panels. Staining for CD11c+, langerin (CD207+) DCs, CD4+, and FOXP3+ Treg cells was performed on paraffin-embedded sections of bioptates using immunohistochemistry. The density of CD11c+ DCs, CD4+, and FOXP3+ Treg cells was higher in the CD patients compared to the AD and FGD patients (p = 0.02; p = 0.001). In AD, significantly higher density of CD11c+ DCs was detected in patients positive for specific IgE to food allergen panels (p = 0.02). The FGD patients with elevated total IgE had increased density of langerin (CD207)+ DCs compared to the patients with normal total IgE levels (p = 0.01). The increased density of FOXP3+ Treg cells, CD4+, cells and CD11c+ DCs was associated with CD but not with AD. The elevated level of total IgE or specific IgE to food allergens was associated with more pronounced expression of DCs, indicating a possible link between the presence of these cells in small bowel mucosa with elevated level of serum IgE.

The adaptive immune system in atopic dermatitis and implications on therapy

In atopic dermatitis (AD), the skin inflammation is believed to occur due to a misdirected immune reaction against harmless antigens on the one hand, and to a disturbed skin barrier on the other. In recent years, vast efforts have been made to investigate the relevance and details of the immune response to allergens. Clinically, it was demonstrated for the first time that aeroallergen exposure leads to worsening of AD symptoms. An overexpression of Th2 cytokines has been observed in acute and subacute lesions of AD. The clinical impact of the key Th2 cytokines IL-4 and IL-13 on atopic dermatitis has recently been shown in clinical studies with dupilumab, a monoclonal antibody which blocks the IL-4/IL-13 receptor. In vitro data indicate, however, that the T cell response is not solely Th2-polarized but may lead to heterogeneous cytokine production involving IFN-γ and IL-17 in an allergen-dependent manner. Classical thymus-derived Foxp3 T cells have interestingly been detected in elevated numbers in the circulation of AD patients. Therapeutic approaches with allergen specific immunotherapy aim to induce regulatory T cells of the Tr1 type. The strikingly altered microbiome of AD skin with diminished diversity of bacteria on lesional skin but increases of S. aureus colonization and the sensitization against microbial allergens and homologue self-proteins deserve special attention. For the treatment of itch symptoms, which still represent a challenge in daily practice, promising data have been published on the relevance of the H(histamine)4-receptor and on mediators such as IL-31, TSLP.