Antigen presentation and MHC class II expression by human esophageal epithelial cells: role in eosinophilic esophagitis

Esophageal epithelial Ikkβ deletion promotes eosinophilic esophagitis in experimental allergy mouse model

BACKGROUND

Eosinophilic esophagitis (EoE) is a chronic TH2-associated inflammatory disorder triggered by food allergens, resulting in esophageal dysfunction through edema, fibrosis, and tissue remodeling. The role of epithelial remodeling in EoE pathogenesis is critical but not fully understood.

OBJECTIVE

We investigated the role of epithelial IKKβ/NF-κB signaling in EoE pathogenesis using a mouse model with conditional Ikkβ knockout in esophageal epithelial cells (IkkβEEC-KO).

METHODS

EoE was induced in IkkβEEC-KO mice through skin sensitization with MC903/ovalbumin followed by intraesophageal ovalbumin challenge. Histologic and transcriptional analyses were performed to assess EoE features. Single-cell RNA sequencing was used to profile esophageal mucosal cell populations and gene expression changes.

RESULTS

IkkβEEC-KO/EoE mice exhibited hallmark EoE features, including eosinophil infiltration, intraepithelial eosinophils, microabscesses, basal cell hyperplasia, and lamina propria remodeling. RNA sequencing revealed significant alterations in IKKβ/NF-κB signaling pathways, with decreased expression of RELA and increased expression of IKKβ-negative regulators. Sequencing analyses identified disrupted epithelial differentiation and barrier integrity alongside increased type 2 immune responses and peptidase activity.

CONCLUSION

Loss of epithelial IKKβ signaling exacerbates EoE pathogenesis, highlighting the critical role of this pathway in maintaining epithelial homeostasis and preventing allergic inflammation. The IkkβEEC-KO/EoE mouse model closely mirrors human EoE, providing a valuable tool for investigating disease mechanisms and therapeutic targets. This model can facilitate the development of strategies to prevent chronic inflammation and tissue remodeling in EoE.

Aged regulatory T cells fail to control autoimmune lacrimal gland pathogenic CD4+ T cells

CD25KO mice are a model of Sjögren disease. CD25KO mice have severe inflammation and infiltrating lymphocytes to the lacrimal glands (LG). Whether the pathogenicity of CD25KO CD4+ T cells can be controlled in vivo by Tregs is unknown. Eight-week-old B6 and CD25KO mice LGs were submitted for RNA bulk sequencing. A total of 3481 genes were differentially expressed in CD25KO LG compared to B6. Tear washing analysis identified CD25KO mice had elevated protein levels of TNF, IFN-γ, and CCL5 and decreased protein levels of IL-12p40 and VEGF-A. Co-adoptive transfer of CD25KO CD4+ T cells with either young or aged B6 Tregs was performed in RAG1KO mice. Recipients of CD25KO CD4+ T cells alone had higher LG inflammation than naive mice. However, in recipients of young B6 Tregs plus CD25KO CD4+ T cells, LGs had significantly reduced inflammation. Recipients of CD25KO CD4+ T cells with aged B6 Tregs had more inflamed LGs than young Tregs, suggesting aged Tregs have less suppressive capacity in vivo. Altogether, CD25KO mice have phenotypic and genetic changes resulting in increased inflammation and severe lymphocytic infiltration in the LGs. However, this autoimmunity can be controlled by the addition of young, but not aged, Tregs, suggesting that aging Tregs have dysfunctional suppression.

Interferon-γ Signaling in Eosinophilic Esophagitis Affects Epithelial Barrier Function and Programmed Cell Death

BACKGROUND & AIMS

Eosinophilic esophagitis (EoE) is a chronic esophageal inflammatory disorder characterized by eosinophil-rich mucosal inflammation and tissue remodeling. Prior research has revealed the upregulation of interferon (IFN) response signature genes (ISGs) in biopsy tissue from patients with EoE, but the specific cell types that contribute to this IFN response and the effect of interferons on the esophageal epithelium remain incompletely understood. Here, we use single-cell RNA sequencing (scRNA-seq) to examine the expression of IFN and ISGs during EoE and explore how IFN-α and IFN-γ treatments affect epithelial function.

METHODS

Epithelial gene expression from patients with EoE was examined using scRNA-seq and a confirmatory bulk RNA-seq experiment of isolated epithelial cells. The functional impact of IFN-α and IFN-γ on epithelial cells was investigated using organoid models.

RESULTS

Using scRNA-seq, the highest number of differentially regulated ISGs was found in the epithelial cells of patients with active EoE, and ISGs in transitional epithelial cells correlated significantly with eosinophil counts and endoscopic reference scores. IFN-γ and IFN-α treatments reduced organoid formation rate and size in a dose-dependent manner, with IFN-γ showing a more pronounced impact on measures of epithelial barrier formation and induction of caspase activity. We identify high IFNG expression in a cluster of majority CD8+ T cells with high expression of CD69 and FOS.

CONCLUSIONS

These findings reveal that interferon, especially IFN-γ, plays a central role in epithelial cell dysfunction, significantly affecting gene expression, cellular differentiation, and barrier integrity. Clarifying the contribution of varied cytokine signals in EoE may help explain the heterogeneity in patient presentation and therapeutic response.

Role of microRNAs in immunoregulatory functions of epithelial cells

Epithelial cells (ECs) provide the first line of defense against microbial threats and environmental challenges. They participate in the host's immune responses via the expression and secretion of various immune-related molecules such as cytokines and chemokines, as well as interaction with immune cells. A growing body of evidence suggests that the dysregulated function of ECs can be involved in the pathophysiology of a broad range of infectious, autoimmune, and inflammatory diseases, including inflammatory bowel disease (IBD), asthma, multiple sclerosis, and rheumatoid arthritis. To maintain a substantial immunoregulatory function of ECs, precise expression of different molecules and their regulatory effects are indispensable. MicroRNAs (miRNAs, miRs) are small non-coding RNAs that regulate gene expression commonly at post-transcriptional level through degradation of target messenger RNAs (mRNAs) or suppression of protein translation. MiRNAs implicate as critical regulators in many cellular processes, including apoptosis, growth, differentiation, and immune response. Due to the crucial roles of miRNAs in such a vast range of biological processes, they have become the spotlight of biological research for more than two decades, but we are still at the beginning stages of the use of miRNA-based therapies in the improvement of human health. Hence, in the present paper, attempts are made to provide a comprehensive overview with regard to the roles of miRNAs in the immunoregulatory functions of ECs. A better understanding of the molecular mechanisms through which immunoregulatory properties of ECs are manifested, could aid the development of efficient strategies to prevent and treat multiple human diseases.

Epithelial-immune interactions govern type 2 immunity at barrier surfaces

Allergic diseases are acute and chronic inflammatory conditions resulting from disproportionate responses to environmental stimuli. Affecting approximately 40% of the global population, these diseases significantly contribute to morbidity and increasing health care costs. Allergic reactions are triggered by pollen, house dust mites, animal dander, mold, food antigens, venoms, toxins, and drugs. This review explores the pivotal role of the epithelium in the skin, lungs, and gastrointestinal tract in regulating the allergic response and delves into the mechanisms of tissue-specific epithelial-immune interactions in this context, with recent advances highlighting their roles in the initiation, elicitation, and resolution phases of allergy. Understanding these intricate interactions at epithelial barriers is essential for developing targeted therapies to manage and treat allergic diseases.

Eosinophilic gastrointestinal disorders and the role for the epithelium in pathogenesis and treatment

PURPOSE OF REVIEW

This review aims to provide an overview of the current understanding of eosinophilic gastrointestinal disorders (EGIDs) and the role of the epithelium in influencing disease pathogenesis to inform and devise future therapeutic strategies.

RECENT FINDINGS

Changes in epithelial cell structure, functions, and integrity are observed in EGIDs. In eosinophilic esophagitis (EoE), the esophageal epithelium has been shown to play key roles in perpetuating the inflammatory response in EoE through the expression of pro-inflammatory cytokines and immunological cell-surface proteins. Similar mechanisms appear to exist in the other EGIDs, including eosinophilic gastritis (EoG), eosinophilic enteritis (EoN), and eosinophilic colitis (EoC). Because of the increasing rarity of each non-EoE EGID, research focusing on how the epithelium is modulating disease in each lower gastrointestinal compartment is still in its rudimentary stages.

SUMMARY

While there has been significant progress in understanding the role of the epithelium in EoE, further research is needed to obtain a better understanding of the mechanisms mediating epithelial-immune crosstalk in non-EoE EGIDs. Using EoE-epithelial cell research to inform future EGID investigations could lead to the development of new therapeutic interventions, such as targeted therapies to restore epithelial barrier function and reduce inflammation, to improve rare disease-patient quality of life.

Advances and ongoing challenges in eosinophilic gastrointestinal disorders presented at the CEGIR/TIGERs Symposium at the 2024 American Academy of Allergy, Asthma & Immunology meeting

The Consortium of Eosinophilic Gastrointestinal disease Researchers (CEGIR) and The International Gastrointestinal Eosinophil Researchers (TIGERs) organized a daylong symposium at the 2024 annual meeting of the American Academy of Allergy, Asthma & Immunology. The symposium featured new discoveries in basic and translational research as well as debates on the mechanisms and management of eosinophilic gastrointestinal diseases. Updates on recent clinical trials and consensus guidelines were also presented. We summarize the updates on eosinophilic gastrointestinal diseases presented at the symposium.

Esophageal epithelial Ikkβ deletion promotes eosinophilic esophagitis in experimental allergy mouse model

Background

Eosinophilic esophagitis (EoE) is a chronic T helper type 2 (Th2)-associated inflammatory disorder triggered by food allergens, resulting in esophageal dysfunction through edema, fibrosis, and tissue remodeling. The role of epithelial remodeling in EoE pathogenesis is critical but not fully understood.

Objective

To investigate the role of epithelial IKKβ/NFκB signaling in EoE pathogenesis using a mouse model with conditional Ikk β knockout in esophageal epithelial cells ( Ikk β EEC-KO ).

Methods

EoE was induced in Ikkβ EEC-KO mice through skin sensitization with MC903/Ovalbumin (OVA) followed by intraesophageal OVA challenge. Histological and transcriptional analyses were performed to assess EoE features. Single-cell RNA sequencing (scRNA-seq) was used to profile esophageal mucosal cell populations and gene expression changes.

Results

Ikkβ EEC-KO /EoE mice exhibited hallmark EoE features, including eosinophil infiltration, intraepithelial eosinophils, microabscesses, basal cell hyperplasia, and lamina propria remodeling. RNA-seq revealed significant alterations in IKKβ/NFκB signaling pathways, with decreased expression of RELA and increased expression of IKKβ negative regulators. scRNA- seq analyses identified disrupted epithelial differentiation and barrier integrity, alongside increased type 2 immune responses and peptidase activity.

Conclusion

Our study demonstrates that loss of epithelial IKKβ signaling exacerbates EoE pathogenesis, highlighting the critical role of this pathway in maintaining epithelial homeostasis and preventing allergic inflammation. The Ikkβ EEC-KO /EoE mouse model closely mirrors human EoE, providing a valuable tool for investigating disease mechanisms and therapeutic targets. This model can facilitate the development of strategies to prevent chronic inflammation and tissue remodeling in EoE.

Key Messages

Critical Role of Epithelial IKKβ/NFκB Signaling: Loss of this signaling exacerbates EoE, causing eosinophil infiltration, basal cell hyperplasia, and tissue remodeling, highlighting its importance in esophageal health.Molecular Insights and Therapeutic Targets: scRNA-seq identified disrupted epithelial differentiation, barrier integrity, and enhanced type 2 immune responses, suggesting potential therapeutic targets for EoE. Relevance of the Ikkβ EEC-KO /EoE Mouse Model: This model replicates human EoE features, making it a valuable tool for studying EoE mechanisms and testing treatments, which can drive the development of effective therapies.

Capsule Summary

This study reveals the crucial role of epithelial IKKβ/NFκB signaling in EoE, providing insights into disease mechanisms and potential therapeutic targets, highly relevant for advancing clinical management of EoE.

Human erythroid progenitors express antigen presentation machinery

Early-life immune exposures can profoundly impact lifelong health. However, functional mechanisms underlying fetal immune development remain incomplete. Erythrocytes are not typically considered active immune mediators, primarily because erythroid precursors discard their organelles as they mature, thus losing the ability to alter gene expression in response to stimuli. Erythroid progenitors and precursors circulate in human fetuses and neonates. Although there is limited evidence that erythroid precursors are immunomodulatory, our understanding of the underlying mechanisms remains inadequate. To define the immunobiological role of fetal and perinatal erythroid progenitors and precursors, we analyzed single cell RNA-sequencing data and found that transcriptomics support erythroid progenitors as putative immune mediators. Unexpectedly, we discovered that human erythroid progenitors constitutively express Major Histocompatibility Complex (MHC) class II antigen processing and presentation machinery, which are hallmarks of specialized antigen presenting immune cells. Furthermore, we demonstrate that erythroid progenitors internalize and cleave foreign proteins into peptide antigens. Unlike conventional antigen presenting cells, erythroid progenitors express atypical costimulatory molecules and immunoregulatory cytokines that direct the development of regulatory T cells, which are critical for establishing maternal-fetal tolerance. Expression of MHC II in definitive erythroid progenitors begins during the second trimester, coinciding with the appearance of mature T cells in the fetus, and is absent in primitive progenitors. Lastly, we demonstrate physical and molecular interaction potential of erythroid progenitors and T cells in the fetal liver. Our findings shed light on a unique orchestrator of fetal immunity and provide insight into the mechanisms by which erythroid cells contribute to host defense.

Bioinformatics analysis identifies a key gene HLA_DPA1 in severe influenza-associated immune infiltration

BACKGROUND

Severe influenza is a serious global health issue that leads to prolonged hospitalization and mortality on a significant scale. The pathogenesis of this infectious disease is poorly understood. Therefore, this study aimed to identify the key genes associated with severe influenza patients necessitating invasive mechanical ventilation.

METHODS

The current study utilized two publicly accessible gene expression profiles (GSE111368 and GSE21802) from the Gene Expression Omnibus database. The research focused on identifying the genes exhibiting differential expression between severe and non-severe influenza patients. We employed three machine learning algorithms, namely the Least Absolute Shrinkage and Selection Operator regression model, Random Forest, and Support Vector Machine-Recursive Feature Elimination, to detect potential key genes. The key gene was further selected based on the diagnostic performance of the target genes substantiated in the dataset GSE101702. A single-sample gene set enrichment analysis algorithm was applied to evaluate the participation of immune cell infiltration and their associations with key genes.

RESULTS

A total of 44 differentially expressed genes were recognized; among them, we focused on 10 common genes, namely PCOLCE2, HLA_DPA1, LOC653061, TDRD9, MPO, HLA_DQA1, MAOA, S100P, RAP1GAP, and CA1. To ensure the robustness of our findings, we employed overlapping LASSO regression, Random Forest, and SVM-RFE algorithms. By utilizing these algorithms, we were able to pinpoint the aforementioned 10 genes as potential biomarkers for distinguishing between both cases of influenza (severe and non-severe). However, the gene HLA_DPA1 has been recognized as a crucial factor in the pathological condition of severe influenza. Notably, the validation dataset revealed that this gene exhibited the highest area under the receiver operating characteristic curve, with a value of 0.891. The use of single-sample gene set enrichment analysis has provided valuable insights into the immune responses of patients afflicted with severe influenza that have further revealed a categorical correlation between the expression of HLA_DPA1 and lymphocytes.

CONCLUSION

The findings indicated that the HLA_DPA1 gene may play a crucial role in the immune-pathological condition of severe influenza and could serve as a promising therapeutic target for patients infected with severe influenza.

Interferon-γ signaling in eosinophilic esophagitis has implications for epithelial barrier function and programmed cell death

Objective

Eosinophilic esophagitis (EoE) is a chronic esophageal inflammatory disorder characterized by eosinophil-rich mucosal inflammation and tissue remodeling. Transcriptional profiling of esophageal biopsies has previously revealed upregulation of type I and II interferon (IFN) response genes. We aim to unravel interactions between immune and epithelial cells and examine functional significance in esophageal epithelial cells.

Design

We investigated epithelial gene expression from EoE patients using single-cell RNA sequencing and a confirmatory bulk RNA-sequencing experiment of isolated epithelial cells. The functional impact of interferon signaling on epithelial cells was investigated using in vitro organoid models.

Results

We observe upregulation of interferon response signature genes (ISGs) in the esophageal epithelium during active EoE compared to other cell types, single-cell data, and pathway analyses, identified upregulation in ISGs in epithelial cells isolated from EoE patients. Using an esophageal organoid and air-liquid interface models, we demonstrate that IFN-γ stimulation triggered disruption of esophageal epithelial differentiation, barrier integrity, and induced apoptosis via caspase upregulation. We show that an increase in cleaved caspase-3 is seen in EoE tissue and identify interferon gamma (IFNG) expression predominantly in a cluster of majority-CD8+ T cells with high expression of CD69 and FOS.

Conclusion

These findings offer insight into the interplay between immune and epithelial cells in EoE. Our data illustrate the relevance of several IFN-γ-mediated mechanisms on epithelial function in the esophagus, which have the potential to impact epithelial function during inflammatory conditions.

Mechanistic Insights into Eosinophilic Esophagitis: Therapies Targeting Pathophysiological Mechanisms

Eosinophilic esophagitis (EoE) is a chronic inflammatory disease characterized by eosinophilic infiltration of the esophagus. It arises from a complex interplay of genetic predisposition (susceptibility loci), environmental triggers (allergens and dietary antigens), and a dysregulated immune response, mainly mediated by type 2 T helper cell (Th2)-released cytokines, such as interleukin (IL)-4, IL-5, and IL-13. These cytokines control eosinophil recruitment and activation as well as tissue remodeling, contributing to the characteristic features of EoE. The pathogenesis of EoE includes epithelial barrier dysfunction, mast cell activation, eosinophil degranulation, and fibrosis. Epithelial barrier dysfunction allows allergen penetration and promotes immune cell infiltration, thereby perpetuating the inflammatory response. Mast cells release proinflammatory mediators and promote eosinophil recruitment and the release of cytotoxic proteins and cytokines, causing tissue damage and remodeling. Prolonged inflammation can lead to fibrosis, resulting in long-term complications such as strictures and dysmotility. Current treatment options for EoE are limited and mainly focus on dietary changes, proton-pump inhibitors, and topical corticosteroids. Novel therapies targeting key inflammatory pathways, such as monoclonal antibodies against IL-4, IL-5, and IL-13, are emerging in clinical trials. A deeper understanding of the complex pathogenetic mechanisms behind EoE will contribute to the development of more effective and personalized therapeutic strategies.

Extracellular vesicles as next generation immunotherapeutics

Extracellular vesicles (EVs) function as a mode of intercellular communication and molecular transfer to elicit diverse biological/functional response. Accumulating evidence has highlighted that EVs from immune, tumour, stromal cells and even bacteria and parasites mediate the communication of various immune cell types to dynamically regulate host immune response. EVs have an innate capacity to evade recognition, transport and transfer functional components to target cells, with subsequent removal by the immune system, where the immunological activities of EVs impact immunoregulation including modulation of antigen presentation and cross-dressing, immune activation, immune suppression, and immune surveillance, impacting the tumour immune microenvironment. In this review, we outline the recent progress of EVs in immunorecognition and therapeutic intervention in cancer, including vaccine and targeted drug delivery and summarise their utility towards clinical translation. We highlight the strategies where EVs (natural and engineered) are being employed as a therapeutic approach for immunogenicity, tumoricidal function, and vaccine development, termed immuno-EVs. With seminal studies providing significant progress in the sequential development of engineered EVs as therapeutic anti-tumour platforms, we now require direct assessment to tune and improve the efficacy of resulting immune responses - essential in their translation into the clinic. We believe such a review could strengthen our understanding of the progress in EV immunobiology and facilitate advances in engineering EVs for the development of novel EV-based immunotherapeutics as a platform for cancer treatment.

Exploring the pathogenesis and immune infiltration in dilated cardiomyopathy complicated with atrial fibrillation by bioinformatics analysis

Background

Atrial fibrillation (AF) is a serious complication of dilated cardiomyopathy (DCM), which increases the risk of thromboembolic events and sudden death in DCM patients. However, the common mechanism of DCM combined with AF remains unclear. This study aims to explore the molecular mechanism and analyze immune infiltration in DCM complicated with AF through comprehensive bioinformatics analysis.

Methods

The gene expression datasets of DCM (GSE141910) and AF (GSE41177 and GSE79768) were obtained from the Gene Expression Omnibus database. Gene enrichment analyses were performed after screening the common differentially expressed genes (DEGs) of DCM and AF. Protein-protein interaction network was constructed in the STRING database and visualized in Cytoscape software, which helped to further screen the central functional modules of DEGs and hub genes. In addition, ImmuCellAI algorithm was performed to estimate immune infiltration patterns, and Spearman correlation was conducted to investigate the correlation between the abundance of multiple immune cells and the expression levels of hub immune-related genes after obtaining hub immune-related genes from the ImmPort database. The hub immune-related genes expression and immune infiltration patterns were additionally verified in the validation datasets (GSE57338, GSE115574, and GSE31821). The diagnostic effectiveness of hub immune-related genes was evaluated through Receiver Operator Characteristic Curve analysis.

Results

A total of 184 common DEGs in DCM and AF were identified for subsequent analyses. The functions of hub genes were significantly associated with immune responses. We identified 7 hub immune-related genes (HLA-DRA, LCK, ITK, CD48, CD247, CD3D, and IL2RG) and a spectrum of immune cell subsets including Monocyte, Neutrophil, and follicular helper T (Tfh) cells were found to be concurrently dysregulated in both DCM and AF. 7 hub immune-related genes were predominantly favorably correlated with Tfh cells and were primarily negatively correlated with Neutrophil infiltrations in DCM and AF. CD48+CD3D were verified to diagnose DCM and AF with excellent sensitivity and specificity, showing favorable diagnostic value.

Conclusions

Our study reveals that immune cells (Tfh cells) disorders caused by hub immune-related genes (CD48 and CD3D) may be the common pathogenesis of DCM combined with AF, which lays a foundation for further immune mechanism research.

Butyrate and propionate restore interleukin 13-compromised esophageal epithelial barrier function

BACKGROUND

Eosinophilic esophagitis (EoE) is a food allergen driven disease that is accompanied by interleukin (IL) 13 overexpression and esophageal barrier dysfunction allowing transepithelial food allergen permeation. Nutraceuticals, such as short-chain fatty acids (SCFAs) that restore barrier function and increase immune fitness may be a promising tool in the management of EoE. Here, we investigated the effects of the SCFAs acetate, propionate, and butyrate on an IL-13-compromised human esophageal epithelial barrier, including the mechanisms involved.

METHODS

An air-liquid interface culture model of differentiated human EPC2-hTERT (EPC2) was used to study whether SCFAs could restore barrier function after IL-13-induced impairment. Esophageal epithelial barrier function was monitored by transepithelial electrical resistance (TEER) and FITC-dextran paracellular flux, and was further examined by qPCR and immunohistochemical analysis. G protein-coupled receptor (GPR) GPR41, GPR43, GPR109a, or histone deacetylase (HDAC) (ant)agonists were used to assess mechanisms of action of SCFAs.

RESULTS

IL-13 stimulation decreased TEER and increased FITC flux, which was counteracted by butyrate and propionate, but not acetate treatment. Barrier proteins FLG and DSG1 mRNA expression was upregulated following butyrate and propionate treatment, whereas expression of eosinophil chemoattractant CCL26 and protease CAPN14 was downregulated. Similarly, butyrate and propionate restored FLG and DSG1 protein expression. Similar effects were observed with an HDAC antagonist but not with GPR agonists.

CONCLUSION

Nutraceuticals butyrate and propionate restore the barrier function of esophageal epithelial cells after an inflammatory insult and may be of therapeutic benefit in the management of EoE.

Human Oral Epithelial Cells Suppress T Cell Function via Prostaglandin E2 Secretion

The oral mucosa is constantly exposed to a plethora of stimuli including food antigens, commensal microbiota and pathogens, requiring distinct immune responses. We previously reported that human oral epithelial cells (OECs) suppress immune responses to bacteria, using H413 and TR146 OEC lines and primary OECs in co-culture with dendritic cells (DCs) and T cells (OEC-conditioned cells). OECs reduced DCs expression of CD80/CD86 and IL-12/TNFα release and impaired T cell activation. Here, we further evaluated the immunosuppression by these OECs and investigated the underlying mechanisms. OEC-conditioned DCs did not induce CD4 T cell polarization towards Treg, judging by the absence of FoxP3 expression. OECs also repressed T-bet/IFNγ expression in CD4 and CD8 T cells activated by DCs or anti-CD3/CD28 antibodies. This inhibition depended on OEC:T cell ratio and IFNγ repression occurred at the transcriptional level. Time-lapse experiments showed that OECs inhibited early steps of T cell activation, consistent with OECs inability to suppress T cells stimulated with PMA/ionomycin. Blocking CD40/CD40L, CD58/CD2 and PD-L1/PD-1 interactions with specific antibodies did not disrupt T cell suppression by OECs. However, preventing prostaglandin E2 (PGE2) synthesis or blocking PGE2 binding to the cognate EP2/EP4 receptors, restored IFNγ and TNFα production in OEC-conditioned T cells. Finally, treating OECs with poly(I:C), which simulates viral infections, limited T cell suppression. Overall, these results point to an inherent ability of OECs to suppress immune responses, which can nonetheless be eluded when OECs are under direct assault.

Type 2 Inflammation in Eosinophilic Esophagitis: From Pathophysiology to Therapeutic Targets

Eosinophilic esophagitis (EoE) is a chronic immune-mediated disease of the esophagus characterized clinically by symptoms related to esophageal dysfunction and histologically by eosinophil-predominant inflammation, whose incidence is rising. It significantly affects patients’ quality of life and, if left untreated, results in fibrotic complications. Although broad consensus has been achieved on first-line therapy, a subset of patients remains non-responder to standard therapy. The pathogenesis of EoE is multifactorial and results from the complex, still mostly undefined, interaction between genetics and intrinsic factors, environment, and antigenic stimuli. A deep understanding of the pathophysiology of this disease is pivotal for the development of new therapies. This review provides a comprehensive description of the pathophysiology of EoE, starting from major pathogenic mechanisms (genetics, type 2 inflammation, epithelial barrier dysfunction, gastroesophageal reflux, allergens, infections and microbiota) and subsequently focusing on the single protagonists of type 2 inflammation (involved cells, cytokines, soluble effectors, surface proteins and transcription factors) that could represent present and future therapeutic targets, while summarizing previous therapeutic approaches in literature.

Immune Tolerance in the Oral Mucosa

The oral mucosa is a site of intense immune activity, where a large variety of immune cells meet to provide a first line of defense against pathogenic organisms. Interestingly, the oral mucosa is exposed to a plethora of antigens from food and commensal bacteria that must be tolerated. The mechanisms that enable this tolerance are not yet fully defined. Many works have focused on active immune mechanisms involving dendritic and regulatory T cells. However, epithelial cells also make a major contribution to tolerance by influencing both innate and adaptive immunity. Therefore, the tolerogenic mechanisms concurring in the oral mucosa are intertwined. Here, we review them systematically, paying special attention to the role of oral epithelial cells.

Immunohistochemical detection of "ex novo" HLA-DR in tumor cells determines clinical outcome in laryngeal cancer patients

There are controversial results about the role of "ex novo" HLA-DR expression by tumor cells and its correlation with the oncological outcomes. Unfortunately, little is known about HLA-DR expression in laryngeal cancer tumor cells. The main purpose of this retrospective study is to strengthen the usefulness of studying "ex novo" HLA-DR expression on tumor cells from primary laryngeal squamous cell carcinoma (LSCC) patients and investigate its correlation with clinical outcome. We analyzed HLA-DR expression by immunohistochemical analysis in 56 patients with LSCC. The "ex novo" HLA-DR expression on laryngeal cancer tumor cells, assessing non-neoplastic LSCC - adjacent tissue, and the association of HLA-DR expression (HLA-DR+) with clinical outcomes were investigated. HLA-DR+ tumor cells were detected in 18/56 LSCC patients (32.1%). All specimens of non-neoplastic laryngeal carcinoma-adjacent tissue resulted HLA-DR negative (HLA-DR-). A statistically significant association was observed between HLA-DR + and well differentiated tumors (G1) (p<0.001). The Kaplan-Meier method showed how HLA-DR+ is significantly associated with both a better disease specific survival (HLA-DR+=100% vs. HLA-DR-=77.4%; p=0.047) and a better relapse free survival (HLA-DR+=100% vs. HLA-DR-=72.3%; p=0.021). Cox regression univariate analysis for death of disease confirmed a higher HR for HLA-DR absence on the surface of epithelial tumor cell [HR:37.489; 95% CI:0.750-18730.776; p=0.253] and for high-grade (G3) tumors [HR:18.601; 95% CI:3.613-95.764; p<0.0001]. Our results confirm that MHC class II HLA-DR expression is activated in a sub-set of LSCC patients. Evaluation of HLA-DR expression in LSCC could be useful for prognosis and future approaches towards personalized therapy.

Impact of food challenge on local oesophageal immunophenotype in eosinophilic oesophagitis

BACKGROUND

Eosinophilic oesophagitis (EoE) is caused by the ingestion of food antigens. Dietary avoidance can result in clinical and histological remission, while food reintroduction can cause recurrence. It is uncertain if food antigen processing and immune activation occurs locally, in the oesophagus. Therefore, we performed a comparative study of the density of cell surface proteins (known to be involved with antigen presentation) on oesophageal tissue prior to, and following food antigen induced disease recurrence. A secondary aim was to consider novel biomarkers.

METHOD

Adult patients with a diagnosis of EoE, who had achieved histological remission with an elimination diet (<15 eosinophils per high power field at oesophageal biopsy), and who underwent food challenge with proven recurrence were included. Immunohistochemistry/immunofluorescence for CD1a, CD3, CD28, CD40, CD69, CD80, CD138, CXCR3 and HLA-DR was performed. Staining intensity of each biomarker (pixels/mm² ) was quantified by semi-automated analysis (Studio-FL software).

RESULTS

Fourteen cases of EoE (pre and post food challenge), 6 GORD and 5 healthy controls were included. HLA-DR, CD3, CD28, CD40 and CD 138 significantly increased with food reintroduction (P = <0.05). CD1a, CD 69, CD 80 and CXCR3 did not measurably change.

CONCLUSION

The presence of cell surface proteins typically associated with antigen presentation (following food antigen induced recurrence) suggests immune activation occurs in the oesophagus, and the relative lack of langerhans cells (CD1a) may indicate this cell type is unimportant. The cell surface protein CD 138 increases with disease recurrence, is not elevated in GORD or healthy controls, and has promise as a biomarker.

Conserved IFN Signature between Adult and Pediatric Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) is an allergic inflammatory disease of the esophagus that occurs in both children and adults. Previous studies of affected tissue from pediatric cohorts have identified prominent signatures of eosinophilia and type 2 inflammation. However, the details of the immune response in adults with EoE are still being elucidated. To determine whether EoE in adults shares inflammatory profiles with those observed in children, we performed RNA sequencing of paired human esophageal biopsies and blood samples from adults with EoE or gastroesophageal reflux disease. Unbiased analysis of differentially expressed genes in tissue revealed a strong IFN signature that was significantly enriched in EoE patients as compared with patients with gastroesophageal reflux disease. Both type I and type II IFN-responsive genes were upregulated in adult biopsies, but not in blood. A similar increase in expression of IFN gene sets was observed in pediatric EoE biopsies as compared with non-EoE samples, and in public pediatric and adult RNA-sequencing data. Finally, we found that human peripheral CD4⁺ T cells from children with EoE produce IFN-γ upon activation with EoE-causal allergens. Together, this work identifies a conserved IFN signature in pediatric and adult EoE, highlighting a role for non-type 2 inflammatory networks in the disease process in humans.

A prognostic immune predictor, HLA-DRA, plays diverse roles in non-muscle invasive and muscle invasive bladder cancer

BACKGROUND

There is an increasing demand for prognostic immune biomarkers of cancer. The prognostic significance of immune markers has been shown for various cancers, but biomarkers of bladder cancer (BCa) have not been fully evaluated. To clarify the role of human leukocyte antigen DR alpha chain (HLA-DRA) in BCa development, we examined expression of HLA-DRA mRNA in tissue samples of non-muscle invasive bladder cancer (NMIBC) and muscle invasive bladder cancer (MIBC).

MATERIALS AND METHODS

Tissues of 96 NMIBC, 43 MIBC and 59 controls comprising noncancerous BCa surrounding tissues were used to examine the expression of HLA-DRA gene by real-time polymerase chain reaction. The expression of up-stream genes regulating HLA-DRA were also measured to explain the role of HLA-DRA in BCa.

RESULTS

Patients with high grade NMIBC showed higher expression of HLA-DRA than those with low grade NMIBC (P < 0.05). In addition, NMIBC patients who progressed to MIBC showed high expression of HLA-DRA mRNA. Kaplan-Meier analysis showed that NMIBC patients with low expression of HLA-DRA had better progression-free survival than those with high expression (P = 0.004). Moreover, the expression of genes regulating HLA-DRA varied in NMIBC and MIBC, indicating a different immunoregulation effect of HLA-DRA in both cancers.

CONCLUSIONS

High expression of HLA-DRA in NMIBC patients has implications for patient stratification strategies, as well as for BCa tumor immunology.

Eosinophils in Eosinophilic Esophagitis: The Road to Fibrostenosis is Paved With Good Intentions

Eosinophilic esophagitis (EoE) is an antigen-driven disease associated with epithelial barrier dysfunction and chronic type 2 inflammation. Eosinophils are the defining feature of EoE histopathology but relatively little is known about their role in disease onset and progression. Classically defined as destructive, end-stage effector cells, eosinophils (a resident leukocyte in most of the GI tract) are increasingly understood to play roles in local immunity, tissue homeostasis, remodeling, and repair. Indeed, asymptomatic esophageal eosinophilia is observed in IgE-mediated food allergy. Interestingly, EoE is a potential complication of oral immunotherapy (OIT) for food allergy. However, we recently found that patients with peanut allergy may have asymptomatic esophageal eosinophilia at baseline and that peanut OIT induces transient esophageal eosinophilia in most subjects. This is seemingly at odds with multiple studies which have shown that EoE disease severity correlates with tissue eosinophilia. Herein, we review the potential role of eosinophils in EoE at different stages of disease pathogenesis. Based on current literature we suggest the following: (1) eosinophils are recruited to the esophagus as a homeostatic response to epithelial barrier disruption; (2) eosinophils mediate barrier-protective activities including local antibody production, mucus production and epithelial turnover; and (3) when type 2 inflammation persists, eosinophils promote fibrosis.

Discordance in the Epithelial Cell-Dendritic Cell Major Histocompatibility Complex Class II Immunoproteome: Implications for Chlamydia Vaccine Development

BACKGROUND

Chlamydia trachomatis and Chlamydia muridarum are intracellular bacterial pathogens of mucosal epithelial cells. CD4 T cells and major histocompatibility complex (MHC) class II molecules are essential for protective immunity against them. Antigens presented by dendritic cells (DCs) expand naive pathogen-specific T cells (inductive phase), whereas antigens presented by epithelial cells identify infected epithelial cells as targets during the effector phase. We previously showed that DCs infected by C trachomatis or C muridarum present epitopes from a limited spectrum of chlamydial proteins recognized by Chlamydia-specific CD4 T cells from immune mice.

METHODS

We hypothesized that Chlamydia-infected DCs and epithelial cells present overlapping sets of Chlamydia-MHC class II epitopes to link inductive and effector phases to generate protective immunity. We tested that hypothesis by infecting an oviductal epithelial cell line with C muridarum, followed by immunoaffinity isolation and sequencing of MHC class I- and II-bound peptides.

RESULTS

We identified 26 class I-bound and 4 class II-bound Chlamydia-derived peptides from infected epithelial cells. We were surprised to find that none of the epithelial cell class I- and class II-bound chlamydial peptides overlapped with peptides presented by DCs.

CONCLUSIONS

We suggest the discordance between the DC and epithelial cell immunoproteomes has implications for delayed clearance of Chlamydia and design of a Chlamydia vaccine.

Therapeutic applications of the selective high affinity ligand drug SH7139 extend beyond non-Hodgkin's lymphoma to many other types of solid cancers

SH7139, the first of a series of selective high affinity ligand (SHAL) oncology drug candidates designed to target and bind to the HLA-DR proteins overexpressed by B-cell lymphomas, has demonstrated exceptional efficacy in the treatment of Burkitt lymphoma xenografts in mice and a safety profile that may prove to be unprecedented for an oncology drug. The aim of this study was to determine how frequently the HLA-DRs targeted by SH7139 are expressed by different subtypes of non-Hodgkin’s lymphoma and by other solid cancers that have been reported to express HLA-DR. Binding studies conducted with SH7129, a biotinylated analog of SH7139, reveal that more than half of the biopsy sections obtained from patients with different types of non-Hodgkin’s lymphoma express the HLA-DRs targeted by SH7139. Similar analyses of tumor biopsy tissue obtained from patients diagnosed with eighteen other solid cancers show the majority of these tumors also express the HLA-DRs targeted by SH7139. Cervical, ovarian, colorectal and prostate cancers expressed the most HLA-DR. Only a few esophageal and head and neck tumors bound the diagnostic. Within an individual’s tumor, cell to cell differences in HLA-DR target expression varied by only 2 to 3-fold while the expression levels in tumors obtained from different patients varied as much as 10 to 100-fold. The high frequency with which SH7129 was observed to bind to these cancers suggests that many patients diagnosed with B-cell lymphomas, myelomas, and other non-hematological cancers should be considered potential candidates for new therapies such as SH7139 that target HLA-DR-expressing tumors.

Characterising the prognostic potential of HLA-DR during colorectal cancer development

HLA-DR, an MHC class II molecule that mediates antigen presentation, is a favourable prognostic indicator in colorectal cancer (CRC). However, the dynamics and location of HLA-DR expression during CRC development are unclear. We aimed to define HLA-DR expression by immunohistochemistry in colorectal epithelium and stromal tissue at different stages of cancer development, assessing non-neoplastic colorectal adenocarcinoma-adjacent tissue, adenomas and carcinoma tissues, and to associate HLA-DR levels with clinical outcomes. Patients with higher than median HLA-DR expression survived at least twice as long as patients with lower expression. This association was significant for HLA-DR staining in the colorectal carcinoma epithelium (n = 152, p = 0.011, HR 1.9, 95% CI 1.15-3.15) and adjacent non-neoplastic epithelium (n = 152, p < 0.001, HR 2.7, 95% CI 1.59-4.66), but not stroma. In stage II cases, however, the prognostic value of HLA-DR expression was significant only in adjacent non-neoplastic tissues, for both epithelium (n = 63, p = 0.015, HR 3.6, 95% CI 1.279-10.25) and stroma (n = 63, p = 0.018, HR 5.07, 95% CI 1.32-19.49). HLA-DR was lower in carcinoma tissue compared to matched adenomas (n = 35), in epithelium (p < 0.01) and stroma (p < 0.001). HLA-DR was further reduced in late-stage carcinoma (n = 101) compared to early stage (n = 105), in epithelium (p < 0.001) and stroma (p < 0.01). HLA-DR expression was lower (p < 0.05) in the adjacent non-neoplastic epithelium of patients with cancer recurrence. We demonstrate a progressive loss of HLA-DR in epithelial and stromal tissue compartments during CRC development and show prognostic ability in carcinoma-adjacent non-neoplastic tissues, highlighting the importance of this molecule in the anti-cancer immune response. These findings may have wider implications for immunotherapeutic interventions.

Immunoexpression of human leukocyte antigen-DR in actinic cheilitis and lower lip squamous cell carcinoma

The aim of this study was to evaluate the immunoexpression of human leukocyte antigen-DR (HLA-DR) in actinic cheilitis (AC) and lower lip squamous cell carcinoma (LLSCC), and to correlate the findings with clinical (tumor size/extent, regional lymph node metastasis, and clinical stage) and histopathological (grade of epithelial dysplasia and inflammatory infiltrate for AC and histopathological grade of malignancy for LLSCC) parameters. Twenty-four AC and 48 LLSCC cases (24 with regional nodal metastasis and 24 without regional nodal metastasis) were selected. The scores of immunopositive cells for HLA-DR in the epithelial component of the lesions were assessed and the results were analyzed statistically using the nonparametric Mann-Whitney test. Epithelial expression of HLA-DR was observed in only five (20.8%) cases of AC (two low-grade and three high-grade lesions), with a very low median score of immunopositivity. By contrast, expression of HLA-DR was found in most LLSCC (97.9%), with a relatively high median score of positive cells. The score of HLA-DR-positive cells tended to be higher in tumors with regional lymph node metastasis, tumors in advanced clinical stages, and low-grade tumors, but the difference was not statistically significant (p > 0.05). In addition, there was a tendency towards higher expression of HLA-DR in highly/moderately keratinized tumors, and tumors with little/moderate nuclear pleomorphism (p > 0.05). The results suggest a potential role of HLA-DR in lip carcinogenesis, particularly in the development and progression of LLSCC. The expression of this protein can be related to the degree of cell differentiation in these tumors.

Human Oral Epithelial Cells Impair Bacteria-Mediated Maturation of Dendritic Cells and Render T Cells Unresponsive to Stimulation

The oral mucosa is a first line of defense against pathogenic organisms and yet tolerates food antigens and resident bacteria. Mucosal epithelial cells are emerging as important regulators of innate and adaptive immune responses. However, the contribution of oral epithelial cells (OECs) determining oral immunity is understudied. Here, we evaluated the ability of H413 and TR146 cells, two OEC lines derived from human oral squamous cell carcinomas, and primary OECs to modulate immune responses to a cocktail of Gram⁺ and Gram⁻ bacteria known as MV130. OECs expressed CD40 constitutively and class II major histocompatibility complex (MHC II) molecules when stimulated with IFNγ, but not CD80 or CD86. Dendritic cells (DCs) treated with bacteria in co-culture with OECs did not fully mature, as judged by the expression of MHC II, CD80 and CD86, and barely released IL-12 and TNFα, compared to control DCs. Furthermore, in the presence of OECs, DCs were unable to stimulate allogenic naive CD4 T cells to produce IFNγ and TNFα. Similarly, OECs in culture with total CD4 T cells or Th1 cells stimulated with anti-CD3 and anti-CD28 antibodies abrogated CD25 and CD69 expression, T cell proliferation and the release of IFNγ and TNFα. The inhibition on T cell activation by OECs was cell-contact dependent, TGFβ independent and largely irreversible. Overall, this behavior of OECs is likely key to avoid immune system over-reaction against resident bacteria.

Molecular basis and cellular mechanisms of eosinophilic esophagitis for the clinical practice

Eosinophilic esophagitis (EoE) is a chronic, allergen-driven inflammatory esophageal disease characterized by predominantly eosinophilic inflammation leading to esophageal dysfunction. Recent efforts to understand EoE have increased our knowledge of the disease. Areas covered: Multiple cells, molecules, and genes interplay with early life environmental factors in the pathophysiology of EoE to converge in the esophageal epithelium at the center of disease pathogenesis. Epithelial cells constitute a mayor cytokine source for TSLP and Calpain-14; an impaired epithelial barrier function allowing penetration of food and microbiota-derived antigens is involved in triggering and maintaining inflammation. Eosinophil and mast cell-derived products, including TGFβ, together with IL-1β and TNFα, promote epithelial mesenchymal transition in EoE, contributing to tissue remodeling by synthetizing and depositing extracellular matrix in subepithelial layers. This article aims to provide a state-of-the-art update on the pathophysiology of EoE applied to clinical practice, and latest research and developments with potential interest to improve the diagnosis and treatment of patients with EoE are revised. Expert commentary: Preliminary approaches have provided promising results toward incorporating minimally invasive methods for patient diagnosis and monitoring in clinical practice. Early diagnosis and optimized therapies will allow for personalized medicine in EoE.

Pathophysiology of Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) is a chronic inflammatory disease of the esophagus associated with an atopic predisposition which appears to be increasing in prevalence over the last few decades. Symptoms stem from fibrosis, swelling, and smooth muscle dysfunction. In the past two decades, the etiology of EoE has been and is continuing to be revealed. This review provides an overview of the effects of genetics, environment, and immune function including discussions that touch on microbiome, the role of diet, food allergy, and aeroallergy. The review further concentrates on the pathophysiology of the disease with particular focus on the important concepts of the molecular etiology of EoE including barrier dysfunction and allergic hypersensitivity.

Corneal Epithelial Cells Exhibit Myeloid Characteristics and Present Antigen via MHC Class II

Purpose

To explore the impact of ocular surface insults on the immunomodulatory capacity and phenotype of corneal epithelial cells (CECs) with a focus on epithelial-mesenchymal transition (EMT).

Methods

Corneas were harvested from mice 6 days following scratch injury, ragweed pollen-induced allergy, or herpes simplex virus type 1 (HSV-1) infection and compared to healthy tissue controls. Corneas were enzymatically digested and CECs phenotypically characterized using flow cytometry. CECs were defined as epithelial cell adhesion molecule (EpCAM)-positive CD45-negative cells. CECs were assessed by PCR to evaluate EMT-associated transcripts. Recombinant HSV-1 and transgenic mice were utilized to investigate the role of vascular endothelial growth factor A (VEGFA) on the phenotype observed. The immunomodulatory potential of CECs was assessed in coculture assays with ovalbumin-specific CD4 T cells.

Results

Ectopic expression of classic "myeloid" antigens Ly6G, CCR2, and CX3CR1 was identified in CEC subsets from all groups with evidence supporting an underlying partial EMT event resulting from loss of cell-cell contacts. Corneal HSV-1 infection induced Ly6C expression and major histocompatibility complex (MHC)-II upregulation in CECs through a VEGFA-linked mechanism. These Ly6C+ MHC-II+ CECs were found to function as amateur antigen-presenting cells and induced CD4 T cell proliferation in vitro.

Conclusions

This study characterizes a novel immunomodulatory CEC phenotype with possible implications for immune privilege, chronic inflammation, and tissue fibrosis. Moreover, the identification of CECs masquerading with multiple "myeloid" antigens warrants careful evaluation of flow cytometry data involving corneal digests.

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.

Importance of maternal diet in the training of the infant's immune system during gestation and lactation

Latest forecasts predict that half of the European population will be allergic within the coming 15 years, with food allergies contributing substantially to the total burden; preventive measures are urgently needed. Unfortunately, all attempted alimentary strategies for primary prevention of allergic diseases through allergen avoidance so far have failed. This also holds true for the prevention of food allergies in breastfed infants by the common practice of excluding certain foods with allergenic potential from the maternal diet. As a preventive measure, therefore, exclusion diets should be discouraged. They can exhaust nursing mothers and negatively impact both their nutritional status as well as their motivation to breastfeed. A prolonged exclusion diet may be indicated solely in cases of doctor-diagnosed food allergy following rigid medical tests (e.g. double-blind placebo-controlled food challenges). Indicated cases usually involve exclusion of only a few food items. Continued breastfeeding is generally important for many aspects of the infant's health, including the training of the infant's immune responses to foreign compounds and avoidance of overshooting inflammatory responses. Recent studies suggest that the presence of maternal dietary proteins in amniotic fluid, cord blood, and human milk might support the induction of tolerance towards solid foods in infants. These are exactly the same species of proteins or remnants thereof that, in comparatively few cases, trigger allergic responses. However, the insight that the proteins of maternal dietary origin in human milk are more likely to be cure (or, more precise, directing prevention) than curse has still largely evaded the attention of health care professionals consulted by worried breastfeeding mothers. In this paper, we summarize recent literature on the importance of exposure to dietary proteins in the establishment of immunological tolerance and hence prevention of allergic disease. Multiple organizations have used the scientific knowledge to build (local) guidelines (e.g. AAAAI, EAACI, BSACI) that can support health care professionals to provide the best strategy to prevent the onset of allergic diseases. We thus hope to clarify existing confusion about the allergenic propensities of dietary proteins during early life, which has contributed to exaggerated fears around the diet of pregnant and breastfeeding mothers.

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.

Disease marker combination enhances patient characterization in the Finnish sarcoidosis patients

Sarcoidosis is an inflammatory disease of unknown etiology and multiple clinical phenotypes. Clinical manifestations range from asymptomatic disease to severe loss-of-function leading to the hypothesis that sarcoidosis might not be just one disease, but consists of several distinct disease entities each with potentially distinct genetic associations. We have previously demonstrated that in our series HLADRB1* 03:01 and haplotype HLA-DRB1*04:01-DPB1*04:01 are associated with good prognosis sarcoidosis. In our recent work, we found a novel SNP (rs9905945) in the 5'upstream region of the ACE gene to be associated with favorable disease prognosis as well. The main objective of this study was to expand the previous results and analyse combined influence of the found ACE SNP rs9905945 with the protective HLA markers HLADRB1* 03:01 and HLA-DRB1*04:01-DPB1*04:01 in 188 Finnish sarcoidosis patients (resolved disease, n = 90; persistent disease, n = 98). When combining the frequencies of the rs9905945 and of the HLA markers, the strongest association was found for a combination of either/or both HLA markers and rs9905945 for good disease prognosis (37.1% in resolved vs. 11.3% in persistent, p < 0.001, OR = 4.61, (95%CI 2.15-9.86)). In conclusion, we discovered that a combination of the ACE SNP rs9905945 and HLA markers enhance the accuracy for predicting disease course in Finnish sarcoidosis patients further characterizing genetic differences between Finnish sarcoidosis patients with different prognosis.

A global perspective on hepatitis B-related single nucleotide polymorphisms and evolution during human migration

Genome-wide association studies have indicated that human leukocyte antigen (HLA)-DP and HLA-DQ play roles in persistent hepatitis B virus (HBV) infection in Asia. To understand the evolution of HBV-related single nucleotide polymorphisms (SNPs) and to correlate these SNPs with chronic HBV infection among different populations, we conducted a global perspective study on hepatitis-related SNPs. We selected 12 HBV-related SNPs on the HLA locus and two HBV and three hepatitis C virus immune-related SNPs for analysis. Five nasopharyngeal carcinoma-related SNPs served as controls. All SNP data worldwide from 26 populations were downloaded from 1,000 genomes. We found a dramatic difference in the allele frequency in most of the HBV- and HLA-related SNPs in East Asia compared to the other continents. A sharp change in allele frequency in 8 of 12 SNPs was found between Bengali populations in Bangladesh and Chinese Dai populations in Xishuangbanna, China (P < 0.001); these areas represent the junction of South and East Asia. For the immune-related SNPs, significant changes were found after leaving Africa. Most of these genes shifted from higher expression genotypes in Africa to lower expression genotypes in either Europe or South Asia (P < 0.001). During this two-stage adaptation, immunity adjusted toward a weak immune response, which could have been a survival strategy during human migration to East Asia. The prevalence of chronic HBV infection in Africa is as high as in Asia; however, the HBV-related SNP genotypes are not present in Africa, and so the genetic mechanism of chronic HBV infection in Africa needs further exploration. Conclusion: Two stages of genetic changes toward a weak immune response occurred when humans migrated out of Africa. These changes could be a survival strategy for avoiding cytokine storms and surviving in new environments. (Hepatology Communications 2017;1:1005-1013).

Interferon-γ treatment in vitro elicits some of the changes in cathepsin S and antigen presentation characteristic of lacrimal glands and corneas from the NOD mouse model of Sjögren's Syndrome

Inflammation and impaired secretion by lacrimal and salivary glands are hallmarks of the autoimmune disease, Sjögren’s Syndrome. These changes in the lacrimal gland promote dryness and inflammation of the ocular surface, causing pain, irritation and corneal damage. The changes that initiate and sustain autoimmune inflammation in the lacrimal gland are not well-established. Here we demonstrate that interferon-γ (IFN-γ) is significantly elevated in lacrimal gland and tears of the male NOD mouse, a model of autoimmune dacryoadenitis which exhibits many ocular characteristics of Sjögren’s Syndrome, by 12 weeks of age early in lacrimal gland inflammation. Working either with primary cultured lacrimal gland acinar cells from BALB/c mice and/or rabbits, in vitro IFN-γ treatment for 48 hr decreased expression of Rab3D concurrent with increased expression of cathepsin S. Although total cellular cathepsin S activity was not commensurately increased, IFN-γ treated lacrimal gland acinar cells showed a significant increase in carbachol-stimulated secretion of cathepsin S similar to the lacrimal gland in disease. In vitro IFN-γ treatment did not increase the expression of most components of major histocompatibility complex (MHC) class II-mediated antigen presentation although antigen presentation was slightly but significantly stimulated in primary cultured lacrimal gland acinar cells. However, exposure of cultured human corneal epithelial cells to IFN-γ more robustly increased expression and activity of cathepsin S in parallel with increased expression and function of MHC class II-mediated antigen presentation. We propose that early elevations in IFN-γ contribute to specific features of ocular disease pathology in Sjögren’s Syndrome.

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.

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.

HLA-DR expression in tumor epithelium is an independent prognostic indicator in esophageal adenocarcinoma patients

Esophageal adenocarcinoma (EAC) is an aggressive cancer with poor prognosis, and incidence is increasing rapidly in the Western world. Measurement of immune markers has been shown to have prognostic significance in a growing number of cancers, but whether this is true for EAC has yet to be evaluated. This study aimed to characterize HLA-DR expression in the esophagus across the inflammation to cancer progression sequence and to assess the prognostic significance of HLA-DR expression in EAC. Tissue microarrays (TMA) were constructed from esophageal tissue taken from patients at different stages in the cancer progression sequence; normal, esophagitis, Barrett’s esophagus (BE), low- and high-grade dysplasia (LGD, HGD) and EAC. HLA-DR expression in tissue epithelium and stroma was assessed by immunohistochemistry. HLA-DR expression increased early in the inflammation to cancer progression sequence; with higher expression detected in esophagitis and BE compared to normal tissue. Patients with low (<50%) HLA-DR expression in the EAC tumor epithelium had significantly worse survival outcomes, compared to those with high expression, in both the tumor core (hazard ratio, HR = 2.178, p = 0.024, n = 70) and leading edge (HR = 2.86, p = 0.013, n = 41). Multivariate analysis demonstrated that low HLA-DR expression in leading edge tumor epithelium was an independent predictor of poor survival, associated with a 2.8-fold increase in disease-associated death (p = 0.023). This study shows that HLA-DR is an independent prognostic marker in EAC tumor epithelium. This may have implications for patient stratification strategies as well as EAC tumor immunology.

Eosinophilic Esophagitis: A Comprehensive Review

Eosinophilic esophagitis (EoE) is an emerging chronic atopic clinical-pathologic disease with an estimated prevalence of 1/1000 similar to the one of Crohn's diseases. Usually, EoE is firstly suspected due to symptoms that are caused by esophageal dysfunction and/or fibrosis. EoE diagnosis is confirmed if the esophageal biopsy shows at least 15 eosinophils per high power field (eos/hpf) as a peak value in one or more of at least four specimens obtained randomly from the esophagus. Most of the patients affected by EoE have other atopic diseases such as allergic rhinitis, asthma, IgE-mediated food allergies, and/or atopic dermatitis. The local inflammation is a T helper type 2 (Th2) flogosis, which most likely is driven by a mixed IgE and non-IgE-mediated reaction to food and/or environmental allergens. Recently published genetic studies showed also that EoE is associated with single nucleotide polymorphism (SNP) on genes which are important in atopic inflammation such as thymic stromal lymphopoietin (TSLP) located close to the Th2 cytokine cluster (IL-4, IL-5, IL-13) on chromosome 5q22. When the EoE diagnosis is made, it is imperative to control the local eosinophilic inflammation not only to give symptomatic relief to the patient but also to prevent complications such as esophageal stricture and food impaction. EoE is treated like many other atopic diseases with a combination of topical steroids and/or food antigen avoidance.

The Inflammatory Milieu of Eosinophilic Esophagitis: A Contemporary Review With Emphasis in Putative Immunohistochemistry and Serologic Markers

Eosinophilic esophagitis is a chronic disease characterized by esophageal dysfunction, frequent clinical history of atopy, and eosinophilic inflammation of the esophagus. Within the esophageal mucosa, there is a wide variety of immune mediators, chemotactic factors, mediators of transcription, and markers of epithelial differentiation and integrity that are overexpressed or underexpressed in eosinophilic esophagitis, offering many candidates for biomarkers with diagnostic or prognostic potential. In this review, we summarize the results from studies performed so far to evaluate the detection of these markers by immunohistochemistry on esophageal biopsies. In addition, we briefly describe some attempts to identify markers that could be detected in serum to be used to diagnose or monitor the disease without the need of a biopsy.

Tissue Microenvironments in the Nasal Epithelium of Rainbow Trout (Oncorhynchus mykiss) Define Two Distinct CD8α+ Cell Populations and Establish Regional Immunity

Mucosal surfaces require balancing different physiological roles and immune functions. To effectively achieve multifunctionality, mucosal epithelia have evolved unique microenvironments that create unique regional immune responses without impairing other normal physiological functions. Whereas examples of regional immunity are known in other mucosal epithelia, to date, no immune microenvironments have been described in the nasal mucosa, a site where the complex functions of olfaction and immunity need to be orchestrated. In this study we identified the presence of CD8α⁺ cells in the rainbow trout (Oncorhynchus mykiss) nasal epithelium. Nasal CD8α⁺ cells display a distinct phenotype suggestive of CD8⁺ T cells with high integrin β₂ expression. Importantly, nasal CD8α⁺ cells are located in clusters at the mucosal tip of each olfactory lamella but scattered in the neuroepithelial region. The grouping of CD8α⁺ cells may be explained by the greater expression of CCL19, ICAM-1, and VCAM-1 in the mucosal tip compared with the neuroepithelium. Whereas viral Ag uptake occurred via both tip and lateral routes, tip-resident MHC class II⁺ cells are located significantly closer to the lumen of the nasal cavity than are their neuroepithelial counterparts, therefore having quicker access to invading pathogens. Our studies reveal compartmentalized mucosal immune responses within the nasal mucosa of a vertebrate species, a strategy that likely optimizes local immune responses while protecting olfactory sensory functions.

The Immunologic Mechanisms of Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) is a chronic allergic inflammatory disease that is triggered by food and/or environmental allergens and is characterized by a clinical and pathologic phenotype of progressive esophageal dysfunction due to tissue inflammation and fibrosis. EoE is suspected in patients with painful swallowing, among other symptoms, and is diagnosed by the presence of 15 or more eosinophils per high-power field in one or more of at least four esophageal biopsy specimens. The prevalence of EoE is increasing and has now reached rates similar to those of other chronic gastrointestinal disorders such as Crohn's disease. In recent years, our understanding of the immunologic mechanisms underlying this condition has grown considerably. Thanks to new genetic, molecular, cellular, animal, and translational studies, we can now postulate a detailed pathway by which exposure to allergens results in a complex and coordinated type 2 inflammatory cascade that, if not intervened upon, can result in pain on swallowing, esophageal strictures, and food impaction. Here, we review the most recent research in this field to synthesize and summarize our current understanding of this complex and important disease.

Mechanisms of Disease of Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) is a recently recognized inflammatory disease of the esophagus with clinical symptoms derived from esophageal dysfunction. The etiology of EoE is now being elucidated, and food hypersensitivity is emerging as the central cornerstone of disease pathogenesis. Herein, we present a thorough picture of the current clinical, pathologic, and molecular understanding of the disease with a focus on disease mechanisms.

Eosinophilic esophagitis: New insights in pathogenesis and therapy

Eosinophilic esophagitis (EoE) is a clinico-pathological entity with esophageal symptoms and dense esophageal eosinophilic infiltration throughout the esophagus that may persist despite treatment with proton pump inhibitors. This eosinophilic infiltration is usually absent in the stomach, small intestine and colon, although there are a number of reports of patients with a multi-organ involvement. EoE is associated with abnormalities involving TH2-dependent immunity, with multiple environmental factors strongly contributing to disease expression. The layer of the esophagus affected by the eosinophilic infiltration causes the specific symptoms. Esophageal involvement results mostly in dysphagia for solids that can be severe enough to cause recurrent esophageal obstruction with typical endoscopic features suggesting esophageal remodeling and pathological changes of eosinophilic infiltration of the mucosa, sub-epithelial fibrosis and muscle hypertrophy. This disease is frequently associated with other allergic conditions such as allergic asthma, allergic dermatitis and eosinophilia. The treatment of patients with EoE depends on the severity of the symptoms and of the inflammatory process as well as to their response to a gradual step-up treatment. The first line of treatment consists of steroid containing local inhalers. If unresponsive they are then treated with oral steroids. Intravenous interleukin blockers seem to have a consistent positive therapeutic effect.