Preferential Secretion of Thymic Stromal Lymphopoietin (TSLP) by Terminally Differentiated Esophageal Epithelial Cells: Relevance to Eosinophilic Esophagitis (EoE)

Animal models of eosinophilic esophagitis

Eosinophilic esophagitis is a chronic inflammatory disorder of the esophagus. Over the past 25 yr, great strides have been made toward understanding its pathogenesis, in part due to studies in several types of animal models. The vast majority of these models have been characterized in mice. In this review, we summarize the histopathological features of eosinophilic esophagitis recapitulated by these animal models, as well as discuss their strengths and weaknesses.

Development and dysfunction of structural cells in eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a disorder characterized by dysfunction and chronic local inflammation of the esophagus. The incidence and prevalence of EoE are increasing worldwide. The mechanisms responsible are poorly understood, and effective treatment options are limited. From the lumen outward, the esophagus comprises stratified squamous epithelium, lamina propria, and muscle. The tissue-specific nature of EoE strongly suggests that structural cells in the esophagus are involved in the EoE diathesis. Epithelial basal cell hyperplasia and dilated intercellular spaces are cardinal features of EoE. Some patients with EoE develop lamina propria fibrosis, strictures, or esophageal muscle dysmotility. Clinical symptoms of EoE are only weakly correlated with peak eosinophil count, implying that other cell types contribute to EoE pathogenesis. Epithelial, endothelial, muscle, and fibroblast cells can each initiate inflammation and repair, regulate tissue resident immune cells, recruit peripheral leukocytes, and tailor adaptive immune cell responses. A better understanding of how structural cells maintain tissue homeostasis, respond to cell-intrinsic and cell-extrinsic stressors, and exacerbate and/or resolve inflammatory responses in the esophagus is needed. This knowledge will facilitate the development of more efficacious treatment strategies for EoE that can restore homeostasis of both hematopoietic and structural elements in the esophagus.

Associations of Eosinophilic Gastrointestinal Disorders with Other Gastrointestinal and Allergic Diseases

Eosinophilic gastrointestinal disorders (EGIDs) are becoming more common causing significant suffering and reduced quality of life. These conditions can affect different parts of the digestive system, either individually or in combination. Recognition of their link to allergic disorders or other gastrointestinal (GI) diseases has raised questions about their shared underlying mechanisms, which has had implications for diagnosis and management. The authors critically examine the current understanding of the connection between EGIDs and allergic conditions (ie, atopic dermatitis, allergic rhinitis, asthma, and food allergy) and GI diseases (ie, inflammatory bowel disease, celiac disease, gastroesophageal reflux disease, and motility disorders).

Lysyl Oxidase Regulates Epithelial Differentiation and Barrier Integrity in Eosinophilic Esophagitis

BACKGROUND & AIMS

Epithelial disruption in eosinophilic esophagitis (EoE) encompasses both impaired differentiation and diminished barrier integrity. We have shown that lysyl oxidase (LOX), a collagen cross-linking enzyme, is up-regulated in the esophageal epithelium in EoE. However, the functional roles of LOX in the esophageal epithelium remains unknown.

METHODS

We investigated roles for LOX in the human esophageal epithelium using 3-dimensional organoid and air-liquid interface cultures stimulated with interleukin (IL)13 to recapitulate the EoE inflammatory milieu, followed by single-cell RNA sequencing, quantitative reverse-transcription polymerase chain reaction, Western blot, histology, and functional analyses of barrier integrity.

RESULTS

Single-cell RNA sequencing analysis on patient-derived organoids revealed that LOX was induced by IL13 in differentiated cells. LOX-overexpressing organoids showed suppressed basal and up-regulated differentiation markers. In addition, LOX overexpression enhanced junctional protein genes and transepithelial electrical resistance. LOX overexpression restored the impaired differentiation and barrier function, including in the setting of IL13 stimulation. Transcriptome analyses on LOX-overexpressing organoids identified an enriched bone morphogenetic protein (BMP) signaling pathway compared with wild-type organoids. In particular, LOX overexpression increased BMP2 and decreased the BMP antagonist follistatin. Finally, we found that BMP2 treatment restored the balance of basal and differentiated cells.

CONCLUSIONS

Our data support a model whereby LOX exhibits noncanonical roles as a signaling molecule important for epithelial homeostasis in the setting of inflammation via activation of the BMP pathway in the esophagus. The LOX/BMP axis may be integral in esophageal epithelial differentiation and a promising target for future therapies.

Barrier Dysfunction in Eosinophilic Esophagitis

PURPOSE OF REVIEW

Compelling evidence over the past decade supports the central role of epithelial barrier dysfunction in the pathophysiology of eosinophilic esophagitis (EoE). The purpose of this review is to summarize the genetic, environmental, and immunologic factors driving epithelial barrier dysfunction, and how this impaired barrier can further promote the inflammatory response in EoE.

RECENT FINDINGS

Common environmental exposures, such as detergents, may have a direct impact on the esophageal epithelial barrier. In addition, the effects of IL-13 on barrier dysfunction may be reduced by 17β-estradiol, Vitamin D, and the short chain fatty acids butyrate and propionate, suggesting novel therapeutic targets. There are many genetic, environmental, and immunologic factors that contribute to epithelial barrier dysfunction in EoE. This leads to further skewing of the immune response to a "Th2" phenotype, alterations in the esophageal microbiome, and penetration of relevant antigens into the esophageal mucosa, which are central to the pathophysiology of EoE.

A novel sophorolipids extraction method by yeast fermentation process for enhanced skin efficacy

AIMS

Oriental herbs have been used as medicines in the folk remedy for their numerous phytochemicals and bioactivities. In this study, we have selected five Korean traditional medical herbs and applied bio conversion extraction technology, named it as Bioconversion Oji complex, to identify phytochemicals and evaluate skin related efficacies.

MATERIAL AND METHODS

The process of two-step bio conversion was sequentially conducted. The first step of fermentation was to produce biosurfactants using macadamia seed oil with Candida bombicola, and then five natural plants were added to carry out the main fermentation. To evaluate skin improvement efficacy of Bioconversion Oji complex, in vitro and in vivo studies were conducted. We studied HaCaT cells cultured to assess viability, skin anti-inflammatory, moisturizing and barrier improvement-related mRNA expression. For efficacy study, 21 participants were tested evaluating anti-inflammatory, skin moisturizing and skin barrier improving effects of Bioconversion Oji complex compared to Water extraction of Oji (placebo) for the 4 weeks test period.

RESULTS

The application of bioconversion technology highly increased the content of amino acids and lipids within Bioconversion Oji complex, and 23 flavonoids were also identified. Bioconversion Oji complex was found to be non-toxic and showed significant effects in all parameters tested, including anti-inflammation, skin moisture, and skin barrier in both in vitro and in clinical studies.

CONCLUSIONS

Bioconversion Oji complex has demonstrated skin-friendly properties with significant beneficial effects on anti-inflammatory, skin hydration and barrier function properties. This study provides evidence for the use of Bioconversion Oji complex as an active ingredient in cosmetics and skincare products.

Diclofenac exhibits cytotoxic activity associated with metabolic alterations and p53 induction in ESCC cell lines and decreases ESCC tumor burden in vivo

Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive forms of human malignancy, often displaying limited therapeutic response. Here, we examine the non-steroidal anti-inflammatory drug diclofenac (DCF) as a novel therapeutic agent in ESCC using complementary in vitro and in vivo models. DCF selectively reduced viability of human ESCC cell lines TE11, KYSE150, and KYSE410 as compared with normal primary or immortalized esophageal keratinocytes. Apoptosis and altered cell cycle profiles were documented in DCF-treated TE11 and KYSE 150. In DCF-treated TE11, RNA-Sequencing identified differentially expressed genes and Ingenuity Pathway Analysis predicted alterations in pathways associated with cellular metabolism and p53 signaling. Downregulation of proteins associated with glycolysis was documented in DCF-treated TE11 and KYSE150. In response to DCF, TE11 cells further displayed reduced levels of ATP, pyruvate, and lactate. Evidence of mitochondrial depolarization and superoxide production was induced by DCF in TE11 and KYSE150. In DCF-treated TE11, the superoxide scavenger MitoTempo improved viability, supporting a role for mitochondrial reactive oxygen species in DCF-mediated toxicity. DCF treatment resulted in increased expression of p53 in TE11 and KYSE150. p53 was further identified as a mediator of DCF-mediated toxicity in TE11 as genetic depletion of p53 partially limited apoptosis in response to DCF. Consistent with the anticancer activity of DCF in vitro, the drug significantly decreased tumor burdene in syngeneic ESCC xenograft tumors and 4-nitroquinoline 1-oxide-mediated ESCC lesions in vivo. These preclinical findings identify DCF as an experimental therapeutic that should be explored further in ESCC.

Lysyl oxidase regulates epithelial differentiation and barrier integrity in eosinophilic esophagitis

Background & Aims

Epithelial disruption in eosinophilic esophagitis (EoE) encompasses both impaired differentiation and diminished barrier integrity. We have shown that lysyl oxidase (LOX), a collagen cross-linking enzyme, is upregulated in the esophageal epithelium in EoE. However, the functional roles of LOX in the esophageal epithelium remains unknown.

Methods

We investigated roles for LOX in the human esophageal epithelium using 3-dimensional organoid and air-liquid interface cultures stimulated with interleukin (IL)-13 to recapitulate the EoE inflammatory milieu, followed by single-cell RNA sequencing, quantitative reverse transcription-polymerase chain reaction, western blot, histology, and functional analyses of barrier integrity.

Results

Single-cell RNA sequencing analysis on patient-derived organoids revealed that LOX was induced by IL-13 in differentiated cells. LOX-overexpressing organoids demonstrated suppressed basal and upregulated differentiation markers. Additionally, LOX overexpression enhanced junctional protein genes and transepithelial electrical resistance. LOX overexpression restored the impaired differentiation and barrier function, including in the setting of IL-13 stimulation. Transcriptome analyses on LOX-overexpressing organoids identified enriched bone morphogenetic protein (BMP) signaling pathway compared to wild type organoids. Particularly, LOX overexpression increased BMP2 and decreased BMP antagonist follistatin. Finally, we found that BMP2 treatment restored the balance of basal and differentiated cells.

Conclusions

Our data support a model whereby LOX exhibits non-canonical roles as a signaling molecule important for epithelial homeostasis in the setting of inflammation via activation of BMP pathway in esophagus. The LOX/BMP axis may be integral in esophageal epithelial differentiation and a promising target for future therapies.

Eosinophilic Esophagitis—What Do We Know So Far?

Eosinophilic esophagitis is a Th-2 antigen-mediated disease in which there is an influx of eosinophils to all layers of the esophagus, triggering an inflammatory response. Chronic inflammatory process causes esophageal remodeling, leading to difficulties in swallowing. Food impaction, heartburn, and chest pain are other characteristic (but not pathognomonic) symptoms in adults. Although the disease has only been described since in the early 1970s, its incidence and prevalence are rapidly growing, especially in Western countries. According to the diagnostic guidelines, there should be at least 15 eosinophils visible per high-power field in biopsies obtained from different sites in the esophagus upon endoscopy with relevant esophageal symptoms. Other diseases that can cause esophageal eosinophilia should be ruled out. Eosinophilic esophagitis treatment may be challenging; however, new methods of management have recently emerged. The currently used proton pump inhibitors, topical corticosteroids, and elimination diet are combined with biological treatment. New methods for disease diagnostics and clinical course assessment are also available. This review presents current knowledge about the disease, supported by the latest research data.

EoE behaves as a unique Th2 disease: a narrative review

Background and Objective

To highlight and interpret two significant differences between eosinophilic esophagitis (EoE), a type 2 helper cell (Th2) disease, and three other representative Th2 diseases. EoE, asthma, atopic dermatitis (AD), chronic rhinosinusitis (CRS) and other Th2 diseases employ epithelial alarmins to recognize triggers, share a prototypical inflammatory cascade, and respond to glucocorticoids. However, EoE also has several distinguishing characteristics which may be explained by a distinct pathophysiologic mechanism.

Methods

The following report consist of four related narrative reviews which combine comprehensive PubMed and Google searches. Two reviews were performed to identify and contrast all eligible studies describing serologic markers in EoE compared to asthma, AD, and CRS. Two additional reviews then compare the responses to parenteral biological therapies in EoE and in the same representative Th2 diseases.

Key Content and Findings

Comprehensive literature searches definitively differentiate the absence of serologic markers in EoE compared to their identification in the other representative Th2 diseases. Similarly, a summary of therapeutic trials demonstrates that while EoE is unable to clinically respond to a variety of parenteral biological therapies, asthma, AD and CRS are very effectively treated with this same approach. A novel pathophysiology for EoE is proposed, and the emerging literature that support its existence is summarized.

Conclusions

The fundamental properties described in this narrative regarding serologic signaling and response to parenteral therapy in EoE could be explained if EoE employs a unique application of the Th2 pathway. One potential mechanism consistent with these observations is that EoE employs exclusively esophageal mucosal constituents to initiate and generate the prototypical Th2 cascade and the fibrostenotic changes that follow.

Current state of biologics in treating eosinophilic esophagitis

OBJECTIVE

Eosinophilic esophagitis (EoE) is a chronic, allergen-mediated, eosinophil-predominant, type 2 inflammatory disease that progresses to fibrostenosis of the esophagus if left untreated. This review focuses on biologics therapy in EoE.

DATA SOURCES

Manuscripts on EoE treatments are identified on PubMed.

STUDY SELECTIONS

Original research, randomized controlled trials, retrospective studies, meta-analyses, case series, and case reports of high relevance are selected and reviewed.

RESULTS

Biologics have been used as investigational therapies for EoE in clinical studies over the years, based on earlier work that identified key cytokines and mediators of eosinophilic inflammation and, more recently, type 2 inflammation that underlie EoE pathogenesis. Dupilumab, a monoclonal antibody that targets the interleukin (IL)-4Rα chain, thereby interfering with IL-4 and IL-13 binding with the receptor, was recently approved by the Food and Drug Administration for EoE. Dupilumab improved clinical symptoms, endoscopic scores, histologic inflammation, and esophageal distensibility. Several clinical trials that target key cytokines such as IL-5, IL-13, and thymic stromal lymphopoietin in EoE are still ongoing.

CONCLUSION

Topical corticosteroid, proton pump inhibitor therapy, elimination diet, and dilation are widely accepted treatment modalities for EoE. Dupilumab is the first Food and Drug Administration-approved therapy for EoE. Other studies evaluating biologics that target eosinophils, key cytokines, and inflammatory pathways in EoE are ongoing. Treatment algorithms are needed to position EoE therapies as they emerge.

pTINCR microprotein promotes epithelial differentiation and suppresses tumor growth through CDC42 SUMOylation and activation

The human transcriptome contains thousands of small open reading frames (sORFs) that encode microproteins whose functions remain largely unexplored. Here, we show that TINCR lncRNA encodes pTINCR, an evolutionary conserved ubiquitin-like protein (UBL) expressed in many epithelia and upregulated upon differentiation and under cellular stress. By gain- and loss-of-function studies, we demonstrate that pTINCR is a key inducer of epithelial differentiation in vitro and in vivo. Interestingly, low expression of TINCR associates with worse prognosis in several epithelial cancers, and pTINCR overexpression reduces malignancy in patient-derived xenografts. At the molecular level, pTINCR binds to SUMO through its SUMO interacting motif (SIM) and to CDC42, a Rho-GTPase critical for actin cytoskeleton remodeling and epithelial differentiation. Moreover, pTINCR increases CDC42 SUMOylation and promotes its activation, triggering a pro-differentiation cascade. Our findings suggest that the microproteome is a source of new regulators of cell identity relevant for cancer.

Polysaccharides from Platycodonis Radix ameliorated respiratory syncytial virus-induced epithelial cell apoptosis and inflammation through activation of miR-181a-mediated Hippo and SIRT1 pathways

Respiratory syncytial virus (RSV) is the leading cause of bronchiolitis in young children, but there are few safe and effective treatments for this disease. Platycodonis Radix is widely used as an antitussive and expectorant drug for preventing various diseases in lower respiratory tract, in which the polysaccharides are one of the main bioactivity constituents. In this study, the protective effects of the P. Radix polysaccharides (PRP) against RSV-induced bronchiolitis in juvenile mice and RSV-induced apoptosis of epithelial HEp-2 cells were investigated. The results showed that PRP obviously decreased the levels of IL-1β, IL-4, IL-6, TNF-α, IFN-γ and TSLP in lung tissues, and reduced the number of inflammatory cells in bronchoalveolar lavage fluid (BALF) of RSV-infected mice. Furthermore, it reduced the apoptosis of RSV-infected HEp-2 cells and remarkably inhibited the mRNA expressions of RSV L gene, which indicated that PRP affected transcription and replication of RSV in host cells. Compared with that in RSV-infected group, miR-181a-5p in the PRP-treated group presented the highest relative abundance and its expression was violently reduced by approximately 30%. Mechanistically, PRP had the similar effects as miR-181a-5p antagomir on RSV-induced apoptosis and inflammation in HEp-2 cells via upregulating BCL2, MLL3 and SIRT1, which could be reversed by miR-181a-5p mimic. Therefore, it demonstrated that PRP not only protected against RSV-induced lung inflammation in mice but also inhibited apoptosis of RSV-infected HEp-2 cells via suppressing miR-181a-5p and transcriptionally activating Hippo and SIRT1 pathways.

Emerging Therapies for Eosinophilic Gastrointestinal Diseases

Besides eosinophilic esophagitis, other eosinophilic gastrointestinal diseases (EGIDs), such as eosinophilic gastritis, eosinophilic gastroenteritis, and eosinophilic colitis, are increasingly diagnosed over the last decade. Whereas diagnosis and therapy of eosinophilic esophagitis have been standardized, the diagnosis and therapy of other EGIDs are areas of active research. Motivated by the increasing prevalence of these conditions, concerted efforts of different stakeholders have led to the evaluation of targeted biologic therapies for EGID management over the last couple of years, and several promising molecules are currently in the pipeline. This review article provides an overview of targeted biologic therapies for use in EGIDs.

Immune system and microbiome in the esophagus: implications for understanding inflammatory diseases

The gastrointestinal tract is the largest compartment of the body's immune system exposed to microorganisms, structural components and metabolites, antigens derived from the diet, and pathogens. Most studies have focused on immune responses in the stomach, the small intestine, and the colon, but the esophagus has remained an understudied anatomic immune segment. Here, we discuss the esophagus' anatomical and physiological distinctions that may account for inflammatory esophageal diseases.

Functional role of kallikrein 5 and proteinase-activated receptor 2 in eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a chronic, food antigen-driven, inflammatory disease of the esophagus and is associated with impaired barrier function. Evidence is emerging that loss of esophageal expression of the serine peptidase inhibitor, kazal type 7 (SPINK7), is an upstream event in EoE pathogenesis. Here, we provide evidence that loss of SPINK7 mediates its pro-EoE effects via kallikrein 5 (KLK5) and its substrate, protease-activated receptor 2 (PAR2). Overexpression of KLK5 in differentiated esophageal epithelial cells recapitulated the effect of SPINK7 gene silencing, including barrier impairment and loss of desmoglein-1 expression. Conversely, KLK5 deficiency attenuated allergen-induced esophageal protease activity, modified commensal microbiome composition, and attenuated eosinophilia in a murine model of EoE. Inhibition of PAR2 blunted the cytokine production associated with loss of SPINK7 in epithelial cells and attenuated the allergen-induced esophageal eosinophilia in vivo. Clinical samples substantiated dysregulated PAR2 expression in the esophagus of patients with EoE, and delivery of the clinically approved drug α1 antitrypsin (A1AT, a protease inhibitor) inhibited experimental EoE. These findings demonstrate a role for the balance between KLK5 and protease inhibitors in the esophagus and highlight EoE as a protease-mediated disease. We suggest that antagonizing KLK5 and/or PAR2 has potential to be therapeutic for EoE.

The use of biologics in food allergy

BACKGROUND

Food allergy continues to pose problems due to its increased frequency and its increasingly high severity. In this context, alongside the traditional avoidance strategies of allergenic foods and desensitization through the cautious progression of exposure to foods in the context of oral immunotherapy (OIT), alternative strategies have made their way in the last decades. We review the possibilities of intervention in food allergy with the use of biological drugs capable of interfering with the synthesis of IgE, with their mechanisms of action, or with complex biological mechanisms that lead to the establishment of a food allergy.

METHODS

Repeated Entrez PubMed searches using the template algorithm "Food allergy" and "biologics" or "Omalizumab" or "Dupilumab" or "milk desensitization" or "oral tolerance induction" or "oral immunotherapy" or "Etokimab" or "Tezepelumab" or "Quilizumab" or "Ligelizumab" or "Tralokinumab" or "Nemolizumab" or "Mepolizumab" or "Reslizumab" or "Benralizumab". The authors' clinical experience in paediatric allergy units of University hospitals was also drawn upon.

RESULTS

The landscape in this context has changed dramatically over the past 10 years. We have acquired knowledge mainly on the effect of different types of anti-IgE treatments in poliallergic patients with food allergy, and in patients treated with OIT. However, other mediators are being targeted by specific biologic treatments. Among them, the alarmins Il-33 and TSLP, IL-4 and IL-13, eosinophil-related molecules as IL-6, IL-8, IL-10, IL-12, and mostly IL-5, and integrins involved in the pathogenesis of eosinophilic gastrointestinal diseases (EGIDs), as SIGLEC-8.

CONCLUSIONS

The ever-better knowledge of the mechanisms of food allergy allowing these developments will improve not only the perspective of patients with the most serious immediate food allergies such as anaphylaxis, but also those of patients with related diseases such as atopic dermatitis, eosinophilic esophagitis, and EGIDs. Biologics are also intended to complement OIT strategies that have developed over the years.

Pathogenesis of Eosinophilic Esophagitis: A Comprehensive Review of the Genetic and Molecular Aspects

Eosinophilic esophagitis (EoE) is a relatively new condition described as an allergic-mediated disease of the esophagus. Clinically, it is characterized by dysphagia, food impaction, and reflux-like symptoms. Multiple genome-wide association studies (GWAS) have been conducted to identify genetic loci associated with EoE. The integration of numerous studies investigating the genetic polymorphisms in EoE and the Mendelian diseases associated with EoE are discussed to provide insights into the genetic risk of EoE, notably focusing on CCL26 and CAPN14. We focus on the genetic loci investigated thus far, and their classification according to whether the function near the loci is known. The pathophysiology of EoE is described by separately presenting the known function of each cell and molecule, with the major contributors being eosinophils, Th2 cells, thymic stromal lymphopoietin (TSLP), transforming growth factor (TGF)-β1, and interleukin (IL)-13. This review aims to provide detailed descriptions of the genetics and the comprehensive pathophysiology of EoE.

Pediatric Patient With Concurrent Eosinophilic Esophagitis, Erosive Reflux Esophagitis, and Barrett's Esophagus

Eosinophilic esophagitis and Barrett's esophagus are believed to be separate disease processes, with erosive esophagitis leading to Barrett's esophagus. We report a rare case of concurrent diagnoses in a pediatric patient and examine the relevant genetic profiles in the esophagus.

Comparative Analysis of Thymic and Blood Treg in Myasthenia Gravis: Thymic Epithelial Cells Contribute to Thymic Immunoregulatory Defects

The thymus is involved in autoimmune Myasthenia gravis (MG) associated with anti-acetylcholine (AChR) antibodies. In MG, thymic regulatory T cells (Treg) are not efficiently suppressive, and conventional T cells (Tconv) are resistant to suppression. To better understand the specific role of the thymus in MG, we compared the phenotype and function of peripheral and thymic Treg and Tconv from controls and MG patients. Suppression assays with thymic or peripheral CD4 + T cells showed that the functional impairment in MG was more pronounced in the thymus than in the periphery. Phenotypic analysis of Treg showed a significant reduction of resting and effector Treg in the thymus but not in the periphery of MG patients. CD31, a marker lost with excessive immunoreactivity, was significantly reduced in thymic but not blood resting Treg. These results suggest that an altered thymic environment may explain Treg differences between MG patients and controls. Since thymic epithelial cells (TECs) play a major role in the generation of Treg, we co-cultured healthy thymic CD4 + T cells with control or MG TECs and tested their suppressive function. Co-culture with MG TECs consistently hampers regulatory activity, as compared with control TECs, suggesting that MG TECs contribute to the immune regulation defects of MG CD4 + T cells. MG TECs produced significantly higher thymic stromal lymphopoietin (TSLP) than control TECs, and a neutralizing anti-TSLP antibody partially restored the suppressive capacity of Treg derived from co-cultures with MG TECs, suggesting that TSLP contributed to the defect of thymic Treg in MG patients. Finally, a co-culture of MG CD4 + T cells with control TECs restored numbers and function of MG Treg, demonstrating that a favorable environment could correct the immune regulation defects of T cells in MG. Altogether, our data suggest that the severe defect of thymic Treg is at least partially due to MG TECs that overproduce TSLP. The Treg defects could be corrected by replacing dysfunctional TECs by healthy TECs. These findings highlight the role of the tissue environment on the immune regulation.

Toll-like receptor 2 stimulation augments esophageal barrier integrity

BACKGROUND

Germline-encoded innate immune pattern recognition receptors (PRR) are expressed at epithelial surfaces and modulate epithelial defenses. Evidence suggests that stimulation of the Toll-like receptor (TLR) family of PRR may regulate epithelial barrier integrity by upregulating tight junction (TJ) complex protein expression, but it is not known whether this mechanism is utilized in esophageal epithelial cells. TJ complex proteins maintain intact barrier function and are dysregulated in atopic disorders including eosinophilic esophagitis.

METHODS

Pattern recognition receptors expression was assessed in EoE and control primary esophageal epithelial cells, demonstrating robust expression of TLR2 and TLR3. The three-dimensional air-liquid interface culture (ALI) model was used to test whether TLR2 or TLR3 stimulation alters epithelial barrier function using an in vitro model of human epithelium. Transepithelial electrical resistance (TEER) and FITC-Dextran permeability were evaluated to assess membrane permeability. ALI cultures were evaluated by histology, immunohistochemistry, Western blotting, and chromatin immunoprecipitation (ChIP).

RESULTS

TLR3 stimulation did not change TEER in the ALI model. TLR2 stimulation increased TEER (1.28- to 1.31-fold) and decreased paracellular permeability to FITC-Dextran, and this effect was abolished by treatment with anti-TLR2 blocking antibody. TJ complex proteins claudin-1 and zonula occludens-1 were upregulated following TLR2 stimulation, and ChIP assay demonstrated altered histone 4 acetyl binding at the TJP1 enhancer and CLDN1 enhancer and promoter following zymosan treatment, implying the occurrence of durable chromatin changes.

CONCLUSIONS

Our findings implicate the TLR2 pathway as a potential regulator of esophageal epithelial barrier function and suggest that downstream chromatin modifications are associated with this effect.

Fibrostenotic eosinophilic esophagitis might reflect epithelial lysyl oxidase induction by fibroblast-derived TNF-α

BACKGROUND

Fibrosis and stricture are major comorbidities in patients with eosinophilic esophagitis (EoE). Lysyl oxidase (LOX), a collagen cross-linking enzyme, has not been investigated in the context of EoE.

OBJECTIVE

We investigated regulation of epithelial LOX expression as a novel biomarker and functional effector of fibrostenotic disease conditions associated with EoE.

METHODS

LOX expression was analyzed by using RNA-sequencing, PCR assays, and immunostaining in patients with EoE; cytokine-stimulated esophageal 3-dimensional organoids; and fibroblast-epithelial cell coculture, the latter coupled with fluorescence-activated cell sorting.

RESULTS

Gene ontology and pathway analyses linked TNF-α and LOX expression in patients with EoE, which was validated in independent sets of patients with fibrostenotic conditions. TNF-α-mediated epithelial LOX upregulation was recapitulated in 3-dimensional organoids and coculture experiments. We find that fibroblast-derived TNF-α stimulates epithelial LOX expression through activation of nuclear factor κB and TGF-β-mediated signaling. In patients receiver operating characteristic analyses suggested that LOX upregulation indicates disease complications and fibrostenotic conditions in patients with EoE.

CONCLUSIONS

There is a novel positive feedback mechanism in epithelial LOX induction through fibroblast-derived TNF-α secretion. Esophageal epithelial LOX might have a role in the development of fibrosis with substantial translational implications.

KLF4 activates NFκB signaling and esophageal epithelial inflammation via the Rho-related GTP-binding protein RHOF

Understanding the regulatory mechanisms within esophageal epithelia is essential to gain insight into the pathogenesis of esophageal diseases, which are among the leading causes of morbidity and mortality throughout the world. The zinc-finger transcription factor Krüppel-like factor (KLF4) is implicated in a large number of cellular processes, such as proliferation, differentiation, and inflammation in esophageal epithelia. In murine esophageal epithelia, Klf4 overexpression causes chronic inflammation which is mediated by activation of NFκB signaling downstream of KLF4, and this esophageal inflammation produces epithelial hyperplasia and subsequent esophageal squamous cell cancer. Yet, while NFκB activation clearly promotes esophageal inflammation, the mechanisms by which NFκB signaling is activated in esophageal diseases are not well understood. Here, we demonstrate that the Rho-related GTP-binding protein RHOF is activated by KLF4 in esophageal keratinocytes, leading to the induction of NFκB signaling. Moreover, RHOF is required for NFκB activation by KLF4 in esophageal keratinocytes and is also important for esophageal keratinocyte proliferation and migration. Finally, we find that RHOF is upregulated in eosinophilic esophagitis, an important esophageal inflammatory disease in humans. Thus, RHOF activation of NFκB in esophageal keratinocytes provides a potentially important and clinically-relevant mechanism for esophageal inflammation and inflammation-mediated esophageal squamous cell cancer.

Epithelial-stromal crosstalk and fibrosis in eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a food allergen-induced inflammatory disorder. EoE is increasingly recognized as a cause of swallowing dysfunction, food impaction and esophageal stricture. Inflammation of the esophageal mucosa involves immune cell infiltrate, reactive epithelial changes and fibroblast activation, culminating in robust tissue remodeling toward esophageal fibrosis characterized by excess collagen deposition in the subepithelial lamina propria. Fibrosis contributes to a unique mechanical property of the EoE-affected esophagus that is substantially stiffer than the normal esophagus. There is a great need to better understand the processes behind esophageal fibrosis in order to foster improved diagnostic tools and novel therapeutics for EoE-related esophageal fibrosis. In this review, we discuss the role of esophageal inflammatory microenvironment that promotes esophageal fibrosis, with specific emphasis upon cytokines-mediated functional epithelial-stromal interplays, recruitment and activation of a variety of effector cells, and tissue stiffness. We then explore the current state of clinical methodologies to detect and treat the EoE-related esophageal stricture.

Expanding and characterizing esophageal epithelial cells obtained from children with eosinophilic esophagitis

BACKGROUND

The role of epithelial cells in eosinophilic esophagitis (EoE) is not well understood. In this study, our aim was to isolate, culture, and expand esophageal epithelial cells obtained from patients with or without EoE and characterize differences observed over time in culture.

METHODS

Biopsies were obtained at the time of endoscopy from children with EoE or suspected to have EoE. We established patient-derived esophageal epithelial cell (PDEEC) lines utilizing conditional reprogramming methods. We determined integrin profiles, gene expression, MHC class II expression, and reactivity to antigen stimulation.

RESULTS

The PDEECs were found to maintain their phenotype over several passages. There were differences in integrin profiles and gene expression levels in EoE-Active compared to normal controls and EoE-Remission patients. Once stimulated with antigens, PDEECs express MHC class II molecules on their surface, and when co-cultured with autologous T-cells, there is increased IL-6 and TNF-α secretion in EoE-Active patients vs. controls.

CONCLUSION

We are able to isolate, culture, and expand esophageal epithelial cells from pediatric patients with and without EoE. Once stimulated with antigens, these cells express MHC class II molecules and behave as non-professional antigen-presenting cells. This method will help us in developing an ex vivo, individualized, patient-specific model for diagnostic testing for causative antigens.

Food allergen triggers are increased in children with the TSLP risk allele and eosinophilic esophagitis

OBJECTIVES

TSLP has been shown to be associated with eosinophilic esophagitis (EoE). Specifically, children with EoE often have the nucleotides AA or AG instead of GG at the single nucleotide polymorphism position RS3806932. Presently, the phenotypic characteristics in EoE children with the TSLP EoE risk allele are unknown.

METHODS

A retrospective analysis was performed of all children with EoE who had TSLP genotyping at The Children's Hospital of Philadelphia from 2008-2014. EoE food allergen triggers, presence of atopic features, IgE mediated food allergy and skin prick testing results were reviewed. The number and type of EoE food allergen triggers were compared with genotype using chi-square analysis. Primary cell cultures from EoE patients with or without the risk allele were stimulated with ovalbumin and TSLP secretion was measured by ELISA.

RESULTS

Fifty three of 309 patients were found to have no copies of the TSLP risk allele, whereas 256 patients were found to have one or more copies of the risk allele. There was an increase in the number of patients with three or more EoE food allergens among those who were either homozygous or heterozygous for the risk allele compared to those without the risk allele (P < 0.0001). This was independent of their atopic background. Primary cultures from patients homozygous for the risk allele had greater TSLP secretion than those isolated from heterozygous patients.

CONCLUSIONS

The TSLP risk allele is associated with having multiple EoE food allergen triggers. This novel EoE genotypic-phenotypic correlation may guide future treatment for those with the TSLP risk allele.

The Esophageal Organoid System Reveals Functional Interplay Between Notch and Cytokines in Reactive Epithelial Changes

BACKGROUND & AIMS

Aberrations in the esophageal proliferation-differentiation gradient are histologic hallmarks in eosinophilic esophagitis (EoE) and gastroesophageal reflux disease. A reliable protocol to grow 3-dimensional (3D) esophageal organoids is needed to study esophageal epithelial homeostasis under physiological and pathologic conditions.

METHODS

We modified keratinocyte-serum free medium to grow 3D organoids from endoscopic esophageal biopsies, immortalized human esophageal epithelial cells, and murine esophagi. Morphologic and functional characterization of 3D organoids was performed following genetic and pharmacologic modifications or exposure to EoE-relevant cytokines. The Notch pathway was evaluated by transfection assays and by gene expression analyses in vitro and in biopsies.

RESULTS

Both murine and human esophageal 3D organoids displayed an explicit proliferation-differentiation gradient. Notch inhibition accumulated undifferentiated basal keratinocytes with deregulated squamous cell differentiation in organoids. EoE patient-derived 3D organoids displayed normal epithelial structure ex vivo in the absence of the EoE inflammatory milieu. Stimulation of esophageal 3D organoids with EoE-relevant cytokines resulted in a phenocopy of Notch inhibition in organoid 3D structures with recapitulation of reactive epithelial changes in EoE biopsies, where Notch3 expression was significantly decreased in EoE compared with control subjects.

CONCLUSIONS

Esophageal 3D organoids serve as a novel platform to investigate regulatory mechanisms in squamous epithelial homeostasis in the context of EoE and other diseases. Notch-mediated squamous cell differentiation is suppressed by cytokines known to be involved in EoE, suggesting that this may contribute to epithelial phenotypes associated with disease. Genetic and pharmacologic manipulations establish proof of concept for the utility of organoids for future studies and personalized medicine in EoE and other esophageal diseases.

Biologic Therapies for Immunoglobulin E-mediated Food Allergy and Eosinophilic Esophagitis

Immunoglobulin (Ig) E-mediated food allergy and eosinophilic esophagitis (EoE) are chronic, allergen-mediated disorders characterized by an aberrant TH2 immune response. The development and investigation of biologics for the treatment of IgE-mediated food allergy and eosinophilic esophagitis have provided further insight into the pathophysiology and management of these disorders. This article provides an overview of biologic therapies that are being investigated or have potential as treatments for IgE-mediated food allergy and eosinophilic esophagitis. Identification of EoE phenotypes that are responsive to biologics and investigation of biologics combined with other therapies may help elucidate a role for biologics in EoE.

Noncanonical NF-κB signaling and the essential kinase NIK modulate crucial features associated with eosinophilic esophagitis pathogenesis

Eosinophilic esophagitis (EoE) is an allergic disease of the esophagus driven by T cell and eosinophil responses to dietary allergens, resulting in chronic mucosal inflammation. Few spontaneous animal models of esophageal eosinophilia exist, with most studies relying on artificial sensitization procedures. NF-κB-inducing kinase (NIK; MAP3K14) is a key signaling molecule of the noncanonical NF-κB (NFKB1) pathway, an alternative signaling cascade producing chemokines involved in lymphoid stroma development and leukocyte trafficking. Nik-/- mice have been shown to develop a hypereosinophilic syndrome in peripheral blood and major filtering organs; however, the gastrointestinal mucosa of these mice has not been well characterized. We show that Nik-/- mice develop significant, localized eosinophilic esophagitis that mimics human EoE, including features such as severe eosinophil accumulation, degranulation, mucosal thickening, fibrosis and basal cell hyperplasia. The remainder of the GI tract, including the caudal stomach, small intestine and colon, in mice with active EoE are unaffected, also similar to human patients. Gene expression patterns in esophageal tissue of Nik-/- mice mimics human EoE, with thymic stromal lymphopoetin (TSLP) in particular also elevated at the protein level. In gene expression data sets from human biopsy specimens, we further show that many genes associated with noncanonical NF-κB signaling are significantly dysregulated in EoE patients, most notably a paradoxical upregulation of NIK itself with concurrent upregulation of powerful protein-level destabilizers of NIK. These findings suggest that Nik-/- mice could be useful as a spontaneous model of specific features of EoE and highlight a novel role for noncanonical NF-κB signaling in human patients.

Creating a multi-center rare disease consortium - the Consortium of Eosinophilic Gastrointestinal Disease Researchers (CEGIR)

 Eosinophilic gastrointestinal disorders (EGIDs) affect various segments of the gastrointestinal tract. Since these disorders are rare, collaboration is essential to enroll subjects in clinical studies and study the broader population. The Rare Diseases Clinical Research Network (RDCRN), a program of the National Center for Advancing Translational Sciences (NCATS), funded the Consortium of Eosinophilic Gastrointestinal Disease Researchers (CEGIR) in 2014 to advance the field of EGIDs. CEGIR facilitates collaboration among various centers, subspecialties, patients, professional organizations and patient-advocacy groups and includes 14 clinical sites. It has successfully initiated two large multi-center clinical studies looking to refine EGID diagnoses and management. Several pilot studies are underway that focus on various aspects of EGIDs including novel therapeutic interventions, diagnostic and monitoring methods, and the role of the microbiome in pathogenesis. CEGIR currently nurtures five physician-scholars through a career training development program and has published more than 40 manuscripts since its inception. This review focuses on CEGIR's operating model and progress and how it facilitates a framework for exchange of ideas and stimulates research and innovation. This consortium provides a model for progress on other potential clinical areas.

Genetic variations in the TLR3 locus are associated with eosinophilic esophagitis

Background

Eosinophilic esophagitis (EoE) is an antigen-driven disease mediated by an abnormal immune Th2 response.

Objective

The objective of this article is to investigate genes associated with regulating immune responses leading to disease susceptibility.

Methods

Twenty-seven tag single nucleotide polymorphisms (tSNPs) selected in five candidate genes (TLR3, TLR4, FOXP3, FLG and TSLP) were genotyped in 218 EoE patients and 376 controls. Skin prick tests were carried out in EoE patients with a panel of 17 aeroallergens and 22 plant- and animal-derived foods.

Results

Five tSNPs located in the TSLP locus and one tSNP located in the TLR3 locus were significantly associated with EoE. The interactions between TLR3 and TSLP loci were analyzed. TLR3+/TSLP- and TLR3-/TSLP+ individuals showed a significantly reduced susceptibility to EoE compared to TLR3-/TSLP- individuals (OR = 0.66, p = 0.036 and OR = 0.23, p = 0.00014, respectively). Likewise, TLR3+/TSLP+ individuals showed the most decreased susceptibility of developing EoE (OR = 0.16, p = 0.0001). However, the interaction gain attributed to the combination of both genes was negative (IG = -4.52%), which indicated redundancy or independent effect. Additionally, TLR3 locus was found to be associated with aeroallergen and food sensitization in EoE patients (OR = 9.67, p_c = 0.025 and OR = 0.53, p_c = 0.048, respectively).

Conclusion

TLR3 constitutes a novel genetic susceptibility locus for developing EoE, and the effects would be independent of TSLP.

Management of Eosinophilic Esophagitis Based on Pathophysiological Evidence

Over the past decades eosinophilic esophagitis (EoE) has been increasingly diagnosed, and significant progress has been made in our understanding of its pathophysiology. As EoE cannot be cured yet, treatment goals are suppression of disease activity and symptoms as well as the prevention of progression to a more severe disease phenotype. Disease-modifying treatment options can be divided into dietary therapy and immunosuppressive medications, of which topical steroids have been most investigated, yet are still prescribed off-label. In this review, we will summarize recent advances in our understanding of EoE and discuss the mechanisms of action of current treatment options, with emphasis on the role of the esophageal epithelial barrier and the effects of proton-pump inhibitors in the management of patients with EoE.

Tissue Remodeling in Chronic Eosinophilic Esophageal Inflammation: Parallels in Asthma and Therapeutic Perspectives

Chronic eosinophilic inflammation is associated with tissue remodeling and fibrosis in a number of chronic T-helper 2 (Th2)-mediated diseases including eosinophilic esophagitis (EoE) and asthma. Chronic inflammation results in dysregulated tissue healing, leading to fibrosis and end organ dysfunction, manifesting clinically as irreversible airway obstruction in asthma and as esophageal rigidity, strictures, narrowing, dysmotility, dysphagia, and food impactions in EoE. Current therapies for EoE and asthma center on reducing inflammation-driven tissue remodeling and fibrosis with corticosteroids, coupled with symptomatic control and allergen avoidance. Additional control of Th2 inflammation can be achieved in select asthma patients with biologic therapies such as anti-IL-5 and anti-IL-13 antibodies, which have also been trialed in EoE. Recent molecular analysis suggests an emerging role for structural cell dysfunction, either inherited or acquired, in the pathogenesis and progression of EoE and asthma tissue remodeling. In addition, new data suggest that inflammation-independent end organ rigidity can alter structural cell function. Herein, we review emerging data and concepts for the pathogenesis of tissue remodeling and fibrosis primarily in EoE and relevant pathogenetic parallels in asthma, focusing additionally on emerging disease-specific therapies and the ability of these therapies to reduce tissue remodeling in subsets of patients.

Esophageal and Small Intestinal Mucosal Integrity in Eosinophilic Esophagitis and Response to an Elemental Diet

OBJECTIVES

The esophageal mucosal integrity is impaired in eosinophilic esophagitis (EoE) and it has been suggested that the duodenal permeability is increased. The absence of food allergens may restore the integrity. The aims of this study were to assess duodenal permeability in EoE and to evaluate the effect of an elemental diet on the esophageal and duodenal integrity.

METHODS

In this prospective study 17 adult EoE patients and 8 healthy controls (HC) were included. Esophageal biopsy specimens were sampled before and after 4 weeks of elemental diet to measure eosinophil counts and gene expression of tight junction and barrier integrity proteins. Esophageal and duodenal impedance were measured by electrical tissue impedance spectroscopy and Ussing chambers were used to measure transepithelial resistance (TER) and transepithelial molecule flux. Small intestinal permeability was measured using a test, measuring lactulose/mannitol (L/M) ratios.

RESULTS

In EoE patients, the esophageal but not the duodenal integrity was impaired, compared with HC. We observed no significant difference between L/M ratios of HC and EoE patients. After diet, eosinophil counts decreased significantly, which was paralleled by normalization of esophageal impedance and transepithelial molecule flux. The esophageal TER improved significantly, but did not reach values seen in HC. Esophageal expression of genes encoding for barrier integrity proteins filaggrin and desmoglein-1 was impaired at baseline and restored after diet.

CONCLUSIONS

An elemental diet restores esophageal integrity, suggesting that it is at least partly secondary to allergen exposure. Duodenal integrity seems not to be affected in EoE, and possibly plays a minor role in its pathophysiology.

Eosinophilic disorders of the gastro-intestinal tract: an update

Eosinophilic diseases of the gastrointestinal tract, including eosinophilic esophagitis (EoE) and eosinophilic gastroenteritis (EGE), are rare chronic pathologies of the digestive system, with an immuno-mediated pathogenesis. Recent data suggest that, together with the “classic” IgE-response to allergens, also a delayed hypersensitivity mechanism could be involved in the development of eosinophilic disorders. EoE and EGE were studied only in the latest decades and as a consequence accurate data are not yet available, concerning not only pathogenesis, but also epidemiology, treatment and outcomes. The diagnosis of EoE is centered on endoscopic findings but the certainty is obtained by histological examination from biopsy samples, that has a sensitivity of 100% when based on five samples. The currently available treatments include topical corticosteroids, specific diets and endoscopic treatment. Concerning EGE, three subtypes (mucosal, muscular, and serosal) were identified. The diagnosis is based, as for EoE, on endoscopic and histological assessment, and the treatment includes pharmacological and dietetic approaches. Further studies are warranted in order to better define the etiology and pathogenesis of eosinophilic diseases of the gastrointestinal tract, and thus to develop more appropriate and specific therapies.