Integrin αM activation and upregulation on esophageal eosinophils and periostin-mediated eosinophil survival in eosinophilic esophagitis

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.

Minimally Invasive Approaches to Diagnose and Monitor Eosinophilic GI Diseases

PURPOSE OF REVIEW

This review seeks to understand novel avenues for eosinophilic GI disease management. Biomarkers offer a unique and non-invasive approach to tracking EoE disease progression. While no biomarkers have definitively met the diagnostic criteria for eosinophilic GI diseases, some biomarkers have been shown to be associated with disease activity. Here, we examine the potential of recently studied biomarkers.

RECENT FINDINGS

Current research shows advancements in blood, luminal fluid, and breath testing. Particular areas of interest include mRNA analyses, protein fingerprinting, amplicon sequence variants (ASVs), T cells and IgE receptors, eosinophilic cationic proteins, cytokines, and nitric oxide exhalation. Preliminary results showed that mucosal biomarkers, directly captured from the esophagus, may reflect the best representation of biopsy-based results, in contrast to biomarkers obtained from indirect or peripheral (blood, breath) methods. However, this is based on limited clinical studies without sufficient numbers to evaluate true diagnostic accuracy. Large-scale randomized trials are needed to fully ascertain both the optimal sampling technique and the specific biomarkers that reflect diagnostic status of the disease.

Persistent esophageal changes after histologic remission in eosinophilic esophagitis

BACKGROUND

Eosinophilic esophagitis (EoE) is characterized by persistent or relapsing allergic inflammation, and both clinical and histologic features of esophageal inflammation persist over time in most individuals. Mechanisms contributing to EoE relapse are not understood, and chronic EoE-directed therapy is therefore required to prevent long-term sequelae.

OBJECTIVE

We investigated whether EoE patients in histologic remission have persistent dysregulation of esophageal gene expression.

METHODS

Esophageal biopsy samples from 51 pediatric and 52 adult subjects with EoE in histopathologic remission (<15 eosinophils per high-power field [eos/hpf]) and control (48 pediatric and 167 adult) subjects from multiple institutions were subjected to molecular profiling by the EoE diagnostic panel, which comprises a set of 94 esophageal transcripts differentially expressed in active EoE.

RESULTS

Defining remission as <15 eos/hpf, we identified 51 and 32 differentially expressed genes in pediatric and adult EoE patients compared to control individuals, respectively (false discovery rate < 0.05). Using the stringent definition of remission (0 eos/hpf), the adult and pediatric cohorts continued to have 18 and 25 differentially expressed genes (false discovery rate < 0.05). Among 6 shared genes between adults and children, CDH26 was upregulated in both children and adults; immunohistochemistry demonstrated increased cadherin 26 staining in the epithelium of EoE patients in remission compared to non-EoE controls. In the adult cohort, POSTN expression correlated with the endoscopic reference system score (Spearman r = 0.35, P = .011), specifically correlating with the rings' endoscopic reference system subscore (r = 0.53, P = .004).

CONCLUSION

We have identified persistent EoE-associated esophageal gene expression in patients with disease in deep remission. These data suggest potential inflammation-induced epigenetic mechanisms may influence gene expression during remission in EoE and provide insight into possible mechanisms that underlie relapse in EoE.

Toxin metalloproteinases exert a dominant influence on pro-inflammatory response and anti-inflammatory regulation in jellyfish sting dermatitis

Toxin metalloproteinases are the primary components responsible for various toxicities in jellyfish venom, and there is still no effective specific therapy for jellyfish stings. The comprehension of the pathogenic mechanisms underlying toxin metalloproteinases necessitates further refinement. In this study, we conducted a differential analysis of a dermatitis mouse model induced by jellyfish Nemopilema nomurai venom (NnNV) samples with varying levels of metalloproteinase activity. Through skin tissue proteomics and serum metabolomics, the predominant influence of toxin metalloproteinase activity on inflammatory response was revealed, and the signal pathway involved in its regulation was identified. In skin tissues, many membrane proteins were significantly down-regulated, which might cause tissue damage. The expression of pro-inflammatory factors was mainly regulated by PI3K-Akt signaling pathway. In serum, many fatty acid metabolites were significantly down-regulated, which might be the anti-inflammation feedback regulated by NF-κB p65 signaling pathway. These results reveal the dermatitis mechanism of toxin metalloproteinases and provide new therapeutic targets for further studies. SIGNIFICANCE: Omics is an important method to analyze the pathological mechanism and discover the key markers, which can reveal the pathological characteristics of jellyfish stings. Our research first analyzed the impact of toxin metalloproteinases on jellyfish sting dermatitis by skin proteomics and serum metabolomics. The present results suggest that inhibition of toxin metalloproteinases may be an effective treatment strategy, and provide new references for further jellyfish sting studies.

Effect of VEGF Stimulation on CD11b Receptor on Peripheral Eosinophils in Asthmatics

Asthma is a chronic, complex disease associated with heterogeneity in molecular pathways. Airway inflammation with different cell activation (e.g., eosinophils) and with hypersecretion of many cytokines (e.g., vascular endothelial growth factor-VEGF) might be relevant for asthma pathogenesis and responsible for airway hyperresponsiveness and remodeling. The aim of our study was to reveal the expression of activation marker CD11b on peripheral eosinophils unstimulated and after VEGF in vitro stimulation in asthmatics with different degrees of airway narrowing. The study population included a total of 118 adult subjects: 78 patients with asthma (among them 39 patients with irreversible bronchoconstriction and 39 patients with reversible bronchoconstriction according to the bronchodilation test) and 40 healthy participants as a control group. CD11b expression on peripheral blood eosinophils was detected in vitro using the flow cytometric method without exogenous stimulation (negative control), after N-formyl-methionine-leucyl-phenylalanine stimulation (fMLP; positive control) and after stimulation with VEGF in two concentrations (250 ng/mL and 500 ng/mL). CD11b marker was slightly presented on unstimulated eosinophils in asthmatics and the subgroup with irreversible airway narrowing (p = 0.06 and p = 0.07, respectively). Stimulation with VEGF enhanced the activity of peripheral eosinophils and induced CD11b expression in asthmatics in comparison with a healthy control (p < 0.05), but it was dependent neither on the concentration of VEGF nor on the degree of airways narrowing in patients with asthma. We present our findings to draw attention to the potential role of VEGF in the eosinophil priming and CD11b-mediated signaling in patients with asthma which is currently undervalued.

Dental Follicle Stem Cells Promote Periodontal Regeneration through Periostin-Mediated Macrophage Infiltration and Reprogramming in an Inflammatory Microenvironment

Dental follicle stem cells (DFSCs) have been verified to promote periodontal regeneration in an inflammatory microenvironment. When coping with inflammatory stimulation, DFSCs highly express periostin, a bioactive molecule closely related to periodontal homeostasis. It is worth exploring whether and how periostin plays a role in the promotion of periodontal regeneration by DFSCs. By tracking the fate of DFSCs, it was found that DFSCs significantly contributed to periodontal regeneration in rat periodontal defects while they had a low survival rate. They highly expressed periostin and improved the immune microenvironment in the defect area, especially via the recruitment and reprogramming of macrophages. Silencing periostin attenuated the effects of DFSCs in promoting periodontal regeneration and regulating macrophages. Recombinant human periostin (rhPeriostin) could not only directly promote macrophage reprogramming through the integrin αM/phosphorylated extracellular signal-regulated kinase (p-Erk)/Erk signaling pathway, but it also exhibited the potential to promote periodontal regeneration in rats when loaded in a collagen matrix. These results indicated that periostin is actively involved in the process by which DFSCs promote periodontal regeneration through the regulation of macrophages and is a promising molecular agent to promote periodontal regeneration. This study provides new insight into the mechanism by which DFSCs promote periodontal regeneration and suggests a new approach for periodontal regeneration therapy.

The Multiple Roles of Periostin in Non-Neoplastic Disease

Periostin, identified as a matricellular protein and an ECM protein, plays a central role in non-neoplastic diseases. Periostin and its variants have been considered to be normally involved in the progression of most non-neoplastic diseases, including brain injury, ocular diseases, chronic rhinosinusitis, allergic rhinitis, dental diseases, atopic dermatitis, scleroderma, eosinophilic esophagitis, asthma, cardiovascular diseases, lung diseases, liver diseases, chronic kidney diseases, inflammatory bowel disease, and osteoarthrosis. Periostin interacts with protein receptors and transduces signals primarily through the PI3K/Akt and FAK two channels as well as other pathways to elicit tissue remodeling, fibrosis, inflammation, wound healing, repair, angiogenesis, tissue regeneration, bone formation, barrier, and vascular calcification. This review comprehensively integrates the multiple roles of periostin and its variants in non-neoplastic diseases, proposes the utility of periostin as a biological biomarker, and provides potential drug-developing strategies for targeting periostin.

Management of Adult Patients with Gastrointestinal Symptoms from Food Hypersensitivity-Narrative Review

The incidence of food hypersensitivity has increased dramatically over the years not only among children but also in adults. Adult patients are usually less suspected of food hypersensitivity symptoms since food allergies are more typical for small children, with a tendency to outgrow the condition. The aim of this article is to increase awareness of hypersensitivity to food symptoms and their diagnosis and treatment possibilities among gastroenterologists and other health care professionals dealing with this type of patient. Symptoms of many gastrointestinal disorders, especially functional, may be driven by different types of mechanisms, and food intolerance or allergy should be considered as a potential cause. This article presents the current understanding of the epidemiology, diagnosis and treatment of immune- and non-immune-mediated food-induced diseases. Diagnosis of food hypersensitivity is based mainly on medical history, different types of sensitivity tests, e.g., hydrogen breath test, specific IgE (sIgE) serum concentration, tissue eosinophil count, skin tests and oral food challenges considered as a "gold standard" for food allergy. Elimination diet and pharmacologic treatment for allergy symptoms are first-line therapies. Eosinophilic gastrointestinal diseases are often caused by non-IgE-mediated food allergies, require endoscopic biopsy samples to confirm diagnosis and proper elimination diet often combined with steroids or proton pump inhibitor agents for treatment. Mast cell activation syndrome (MCAS) derives from pathologic reaction of mast cells with increased tryptase serum level as a marker. Symptoms may occur in the digestive, respiratory, skin, neurologic and cardiovascular system. Treatment is based on histamine type 1, type 2 (H1, H2) receptor antagonists and other mast cell stabilizing agents. Carbohydrate intolerances are the most common type of food hypersensitivity in adult patients, and an elimination diet is effective for reducing symptoms. Food additives hypersensitivity remains difficult to diagnose, but use of a diet low in chemical substances alleviates symptoms and helps to diagnose the triggering factors.

Esophageal remodeling in eosinophilic esophagitis: Relationships to luminal captured biomarkers of inflammation and periostin

BACKGROUND

Esophageal remodeling is a factor in disease progression and symptom severity for patients with eosinophilic esophagitis (EoE). Remodeling can begin early in children, resulting in stricture and food impaction. Detection of esophageal remodeling often depends on endoscopy and is appreciated only in its later stages.

OBJECTIVE

We sought to determine whether luminal eosinophil-associated and remodeling proteins captured by the esophageal string test (EST) correlate with measures of esophageal remodeling and biomarkers of the epithelial-mesenchymal transition (EMT).

METHODS

Patients with EoE (7-18 years old) were enrolled from 2 pediatric hospitals. Participants performed the EST and underwent endoscopy. Histology, distensibility measured by endoluminal functional lumen imaging probe, and symptoms were assessed. Protein quantitation by ELISA was performed on mucosal biopsy and EST samples. Tissue sections were evaluated for EMT. Outcome measures were summarized, and Spearman ρ was used to assess bivariate correlations.

RESULTS

Forty patients (68% male) were enrolled (mean age, 12.5 years). Twenty-four (60%) had active disease (≥15 eosinophils per high-power field). EST-captured eotaxin-3, major basic protein 1, EDN, eosinophil peroxidase, and Charcot-Leyden crystal protein/galectin-10 showed significant correlations with peak eosinophils per high-power field (ρ 0.53-0.68, P < .001). Luminal proteins positively correlated with endoscopic features and markers of EMT, and negatively with esophageal distensibility. Periostin was captured by the EST and correlated with eosinophil density, basal zone hyperplasia, endoscopic appearance, and markers of EMT.

CONCLUSION

Luminal markers of esophageal remodeling in addition to biomarkers of eosinophilic inflammation correlate with epithelial and functional remodeling in EoE.

Models and Tools for Investigating Eosinophilic Esophagitis at the Bench

Eosinophilic esophagitis (EoE) is an increasingly common food allergy disease of the esophagus that received its medical designation code in 2008. Despite this recency, great strides have been made in the understanding of EoE pathophysiology and type 2 immunity through basic and translational scientific investigations conducted at the bench. These advances have been critical to our understanding of disease mechanisms and generating new hypotheses, however, there currently is only one very recently approved FDA-approved therapy for EoE, leaving a great deal to be uncovered for patients with this disease. Here we review some of the innovative methods, models and tools that have contributed to the advances in EoE discovery and suggest future directions of investigation to expand upon this foundation.

Expression of DEL-1 in alveolar epithelial cells prevents lipopolysaccharide-induced inflammation, oxidative stress, and eosinophil recruitment in acute lung injury

Bacterial infection is a major cause of acute lung injury (ALI). Developmental endothelial locus-1 (DEL-1) is an immunomodulatory mediator secreted by the endothelial cells. This study aimed to investigate the role of DEL-1 in lipopolysaccharide (LPS)-induced ALI in mouse models and its ability to regulate on eosinophil recruitment. Male C57BL/6 mice were administered an adeno-associated virus (AAV)-mediated DEL-1 overexpression vector via intratracheal injection. Twenty-one days after vector instillation, mice were challenged with LPS (5 mg/kg body weight). Lung injury was evaluated using haematoxylin-eosin staining, flow cytometry, enzyme-linked immunosorbnent assay, quantitative real-time polymerase chain reaction, western blotting, immunohistochemistry and immunofluorescence analyses. DEL-1 was expressed in alveolar epithelial cells of mice. Compared with that in the control group, DEL-1 was expressed at low levels in the lungs of LPS-challenged mice. LPS injured the lungs in mice, as evidenced by an increase in alveolar wall thickness, inflammatory cell infiltration in the stroma, and alveolar collapse. AAV-mediated DEL-1 overexpression attenuated LPS-induced lung injury and inhibited the release of TNF-α, IL-6, and IL-1β. DEL-1 overexpression also attenuated LPS-induced oxidative stress by decreasing lactic dehydrogenase (LDH), myeloperoxidase (MPO), malondialdehyde (MDA), and reactive oxygen species (ROS) activities and increasing superoxide dismutase (SOD) activity. In addition, DEL-1 prevented eosinophil recruitment into lung tissues and inhibited eotaxin production. This study revealed the beneficial role of DEL-1 in preventing LPS-induced ALI in mice. Therefore, DEL-1 can protect lung tissues against LPS-induced inflammation, oxidative stress, and eosinophil recruitment.

Periostin in Allergy and Inflammation

Matricellular proteins are involved in the crosstalk between cells and their environment and thus play an important role in allergic and inflammatory reactions. Periostin, a matricellular protein, has several documented and multi-faceted roles in health and disease. It is differentially expressed, usually upregulated, in allergic conditions, a variety of inflammatory diseases as well as in cancer and contributes to the development and progression of these diseases. Periostin has also been shown to influence tissue remodelling, fibrosis, regeneration and repair. In allergic reactions periostin is involved in type 2 immunity and can be induced by IL-4 and IL-13 in bronchial cells. A variety of different allergic diseases, among them bronchial asthma and atopic dermatitis (AD), have been shown to be connected to periostin expression. Periostin is commonly expressed in fibroblasts and acts on epithelial cells as well as fibroblasts involving integrin and NF-κB signalling. Also direct signalling between periostin and immune cells has been reported. The deposition of periostin in inflamed, often fibrotic, tissues is further fuelling the inflammatory process. There is increasing evidence that periostin is also expressed by epithelial cells in several of the above-mentioned conditions as well as in cancer. Augmented periostin expression has also been associated with chronic inflammation such as in inflammatory bowel disease (IBD). Periostin can be expressed in a variety of different isoforms, whose functions have not been elucidated yet. This review will discuss potential functions of periostin and its different isoforms in allergy and inflammation.

Heterogeneity of Intestinal Tissue Eosinophils: Potential Considerations for Next-Generation Eosinophil-Targeting Strategies

Eosinophils are implicated in the pathophysiology of a spectrum of eosinophil-associated diseases, including gastrointestinal eosinophilic diseases (EGIDs). Biologics that target the IL-5 pathway and are intended to ablate eosinophils have proved beneficial in severe eosinophilic asthma and may offer promise in treating some endotypes of EGIDs. However, destructive effector functions of eosinophils are only one side of the coin; eosinophils also play important roles in immune and tissue homeostasis. A growing body of data suggest tissue eosinophils represent a plastic and heterogeneous population of functional sub-phenotypes, shaped by environmental (systemic and local) pressures, which may differentially impact disease outcomes. This may be particularly relevant to the GI tract, wherein the highest density of eosinophils reside in the steady state, resident immune cells are exposed to an especially broad range of external and internal environmental pressures, and greater eosinophil longevity may uniquely enrich for co-expression of eosinophil sub-phenotypes. Here we review the growing evidence for functional sub-phenotypes of intestinal tissue eosinophils, with emphasis on the multifactorial pressures that shape and diversify eosinophil identity and potential targets to inform next-generation eosinophil-targeting strategies designed to restrain inflammatory eosinophil functions while sustaining homeostatic roles.

Periostin deletion suppresses late-phase response in mouse experimental allergic conjunctivitis

BACKGROUND

To investigate the potential roles of periostin (POSTN), an extracellular matrix preferentially expressed in Th2-skewed conditions in the pathophysiology of allergic conjunctivitis.

METHODS

The roles of POSTN in ragweed-induced experimental allergic conjunctivitis (RW-EAC) were evaluated using both POSTN-knockout (KO) and congenic BALB/c wild-type mice. Histological analysis was carried out to enumerate eosinophils/basophils in the conjunctival tissue. Th2 cytokine expression was evaluated by quantitative polymerase chain reaction (Q-PCR), and microarray analysis was performed to elucidate genes differentially expressed in POSTN-KO and wild-type mice in the RW-EAC model.

RESULTS

Upregulation of POSTN expression and eosinophil infiltration was observed in subconjunctival tissue of RW-EAC in the wild-type mice. The number of infiltrating eosinophils in the conjunctivae of RW-EAC was diminished in POSTN-KO mice compared to wild-type mice. Q-PCR analysis of conjunctival tissue showed induction of Th2 cytokine (Ccl5, Il4, Il5, Il13) expression in the RW-EAC and attenuated Ccl5, Il4, Il13 mRNA expression in the conjunctivae of the RW-EAC using POSTN-KO mice. Microarray analysis and immunohistochemical analysis showed diminished basophil marker (Mcpt8) expression and reduced numbers of infiltrating basophils in the conjunctivae of RW-EAC in POSTN-KO mice.

CONCLUSIONS

POSTN expression in conjunctival tissue plays an indispensable role in the late-phase reaction of the RW-EAC model by facilitating eosinophil/basophil infiltration and augmenting Th2 cytokine expression.

Medical and dietary management of eosinophilic esophagitis

OBJECTIVE

Eosinophilic esophagitis (EoE) is a disease of chronic, allergen-driven, T-helper 2 (Th2) immune-mediated inflammation that progresses to fibrostenosis of the esophagus if left untreated. There are currently no Food and Drug Administration (FDA)-approved drugs for the treatment of EoE. This review focuses on the medical and dietary management of EoE.

DATA SOURCES

Manuscripts on EoE treatments were identified on PubMed.

STUDY SELECTIONS

Original research, randomized control trials, retrospective studies, meta-analyses, case series, and on occasions, case reports of high relevance, were selected and reviewed.

RESULTS

Current treatment strategies available to EoE patients center on monotherapy or combination therapy with dietary modification to exclude antigenic stimulation and topical corticosteroids to control Th2-mediated tissue inflammation and pathologic remodeling. Dilation as a rescue therapy for the narrowed, fibrostenotic, symptomatic esophagus can potentially be avoided with optimal medical and elimination diet therapies. The molecular mechanisms underlying EoE pathogenesis are being unraveled, from which targeted therapies can be developed and evaluated in preclinical and clinical studies. Current clinical research efforts focus on optimization of topical corticosteroid delivery, dosing, frequency, and duration of treatment, either alone or in combination with tailored elimination diet. Preliminary clinical trials with biologics targeting interleukin (IL)-5 and IL-13/IL-4 have been completed.

CONCLUSION

Topical corticosteroid, elimination diet, and dilation are the current treatment modalities for confirmed EoE. The use of proton-pump inhibitors (PPI) is being suggested as a potential regimen to treat EoE, based on evolving understanding of PPI-responsive esophageal eosinophilia (PPI-REE). The complexity of EoE treatment regimens and frequent follow-ups require a multimodal, multi-disciplinary management approach to optimize patient care.