Advancements in understanding bacterial enteritis pathogenesis through organoids.

Bacterial enteritis has a substantial role in contributing to a large portion of the global disease burden and serves as a major cause of newborn mortality. Despite advancements gained from current animal and cell models in improving our understanding of pathogens, their widespread application is hindered by apparent drawbacks. Therefore, more precise models are imperatively required to develop more accurate studies on host-pathogen interactions and drug discovery. Since the emergence of intestinal organoids, massive studies utilizing organoids have been conducted to study the pathogenesis of bacterial enteritis, revealing new mechanisms and validating established ones. In this review, we focus on the advancements of several bacterial pathogenesis mechanisms observed in intestinal organoid/enteroid models, exploring the host response and bacterial effectors during the infection process. Finally, we address the features that warrant additional investigation or could be enhanced in existing organoid models in order to guide future research endeavors.

Pathophysiology and Clinical Impact of Esophageal Remodeling and Fibrosis in Eosinophilic Esophagitis.

Most of the major clinical signs and consequences of eosinophilic esophagitis seem to be related to tissue remodeling. Important data on remodeling activity in patients with eosinophilic esophagitis are provided by a range of current and new biologic markers and diagnostics. To completely clarify the possible advantages and restrictions of therapeutic approaches, clinical studies should take into consideration the existence and reversibility of esophageal remodeling. The degree of mucosal or submucosal disease activity may not be reflected by epithelial eosinophilic inflammation, which is used to define one criterion of disease activity".

Clinical Evaluation of the Child with Eosinophilic Esophagitis.

The diagnosis of eosinophilic esophagitis (EoE) is based on clinical symptoms of esophageal dysfunction and eosinophil predominant esophageal inflammation. Clinical symptoms in children with EoE vary based on age and may be nonspecific. EoE has a male predominance with the majority having comorbid atopic disorders. At present, treatment options include medications (proton pump inhibition, swallowed topical steroids), dietary therapy or biologic therapy (dupilumab, approved for those ≥12 years of age). Outside of EoE in the context of oral immunotherapy, EoE is typically chronic requiring lifelong therapy. Long-term complications including feeding difficulties, malnutrition, and fibrostenotic disease.

Clinical Evaluation of the Adult with Eosinophilic Esophagitis.

Adult patients with eosinophilic esophagitis (EoE) typically present with a history of dysphagia for solids, sometimes with additional reflux-like pain and a history of prior food impactions. In contrast to these alarming symptoms, the general appearance and physical examination of adult patients with EoE is in line with apparently healthy individuals. Therefore, the diagnosis is based on a history of solid-food dysphagia and eosinophilic tissue infiltration. Importantly, the increasing prevalence of EoE variants, that is, typical EoE symptoms in the absence of a relevant eosinophilia, and several studies with eosinophil-targeting drugs, call the pathogenic role of eosinophils into question.

Histopathology of Eosinophilic Esophagitis.

Microscopic examination of esophageal biopsies is essential to diagnose eosinophilic esophagitis (EoE). Eosinophil inflammation is the basis for the diagnosis, but additional abnormalities may contribute to persistent symptoms and epithelial barrier dysfunction. Both peak eosinophil count and assessments of additional features should be included in pre-therapy and post-therapy pathology reports. Pathologic abnormalities identified in esophageal biopsies of EoE are reversible in contrast to esophageal strictures.

Recognition and Management of Feeding Dysfunction in the Pediatric Patient with Eosinophilic Esophagitis.

Feeding is a complex skill requiring coordination of multiple body systems. Multiple factors are considered in feeding dysfunction in pediatric patients with eosinophilic gastrointestinal disorders, including overall development, nutritional status, mealtime behaviors, and medical comorbidities. Symptoms of feeding dysfunction vary by age, with maladaptive learned feeding behaviors spanning all age ranges. Knowledge of the normal acquisition of feeding skills is critical to interpret the impact of the disease and plan appropriate intervention. Assessment and treatment from a feeding and swallowing disorders specialist can dramatically impact successful outcomes in nutrition, growth, mealtime dynamics and ultimatly quality of life for children and their caregivers in home and social settings.

Pathophysiology of Non-Esophageal Eosinophilic Gastrointestinal Disorders.

Eosinophilic gastrointestinal disorder (EGID) is an umbrella term encompassing a group of chronic, immune-mediated disorders characterized by eosinophil-rich inflammation affecting one or more segments of the gastrointestinal tract. A recent consensus in nomenclature and emerging data made possible through multi-center consortia are beginning to unravel the molecular and cellular underpinnings of EGIDs below the esophagus. These emerging findings are revealing both overarching commonalities related to a food allergen-driven, chronic, Th2-mediated immune response as well as location-specific nuances in the pathophysiology of the collective EGIDs. Altogether, these advances offer promise for improved diagnoses and more efficacious interventional strategies.

Role of Mast Cells in Eosinophilic Gastrointestinal Diseases.

Mast cells play a central role in the pathogenesis of eosinophilic gastrointestinal disorders (EGIDs), including eosinophilic esophagitis. Their interactions with immune and structural cells, involvement in tissue remodeling, and contribution to symptoms make them attractive targets for therapeutic intervention. More is being discovered regarding the intricate interplay of mast cells and eosinophils. Recent studies demonstrating that depletion of eosinophils is insufficient to improve symptoms of EGIDs have raised the question of whether other cells may play a role in symptomatology and pathogenesis of EGIDs.

Pharmacologic Management of Eosinophilic Esophagitis.

Proton pump inhibitors (PPIs), swallowed topical corticosteroids (STSs), and dupilumab are highly effective therapies for the treatment of eosinophilic esophagitis. Shared decision-making informs the choice of therapy and factors such as ease of use, safety, cost, and efficacy should be addressed. PPIs are the most common medication utilized early in the disease course; however, for nonresponders, STSs are an excellent alternative. Dupilumab is unlikely to replace PPIs or STSs as first-line therapy, except in highly specific circumstances. Identification of novel biologic pathways and the development of small molecules may lead to a wider range of treatment options in the future.

Associations of Eosinophilic Gastrointestinal Disorders with Other Gastrointestinal and Allergic Diseases.

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

Health-Related Quality of Life in Patients with Eosinophilic Esophagitis.

Measuring health-related quality of life (HRQOL) gained relevance in research and clinical practice in patients with eosinophilic esophagitis. The physical discomfort and social and psychological consequences of this food-related disease substantially affect HRQOL. Determinant of an impaired HRQOL include symptom severity, disease duration, biological disease activity, and psychological factors. Patients prioritize symptom relief and improved HRQOL as treatment objectives. Available treatment options can address these goals; however, there is a suboptimal adherence to treatment. There is a need for enhanced patient guidance and education. The assessment of HRQOL will help to prioritize patient's needs in management.

Embracing Diversity, Equity, Inclusion, and Accessibility in Eosinophilic Gastrointestinal Diseases.

Eosinophilic gastrointestinal diseases (EGIDs) including eosinophilic esophagitis (EoE) are rare diseases in which eosinophils abnormally infiltrate the gastrointestinal tract. Because these are rare diseases, there is limited information regarding race and ethnicity in EGIDs and even less is known about the impact of socioeconomic factors. There is some evidence that access to care in rural settings may be affecting epidemiologic understanding of EGIDs in the pediatric populations. Future work should try to evaluate bias in research and strive for representation in clinical trials and medicine.

Endoscopic Features of Eosinophilic Gastrointestinal Diseases.

Endoscopic evaluation with biopsies is a mainstay of the diagnosis of eosinophilic esophagitis (EoE) and non-EoE eosinophilic gastrointestinal diseases (EGIDs). Increasing knowledge has resulted in the development of 2 standardized scoring systems: the Endoscopic REFerence Score (EREFS) for EoE and the EG-REFS for eosinophilic gastritis, although the latter has not been validated. In EGIDs, diagnosis and follow-up focus on eosinophil infiltration in biopsies. In this article, we will discuss the most commonly used endoscopic scores in EoE and non-EoE EGIDs, their validity for the diagnosis and follow-up of disease activity, as well as endoscopic interventions and areas of uncertainty.

Histopathology of Eosinophilic Gastrointestinal Diseases Beyond Eosinophilic Esophagitis.

Eosinophilic gastrointestinal diseases (EGID), such as eosinophilic gastritis (EoG), eosinophilic enteritis, and eosinophilic colitis (EoC), are chronic inflammatory conditions characterized by persistent gastrointestinal symptoms and elevated levels of activated eosinophils in the gastrointestinal tract. EoG and eosinophilic duodenitis (EoD) are strongly associated with food allergen triggers and TH2 inflammation, whereas EoC shows minimal transcriptomic overlap with other EGIDs. The level of expression of certain genes associated with TH2 immune response is associated with certain histopathologic findings of EoG, EoD, and EoC. Current immune therapy for EoG depletes tissue eosinophilia with persistence of other histopathologic features of disease.

Dietary Management of Non-EoE Eosinophilic Gastrointestinal Diseases.

Patients with non-eosinophilic esophagitis eosinophilic gastrointestinal diseases (non-EoE EGIDs) are prone to nutritional deficiencies due to food-avoidant behaviors, malabsorption, and high nutrition impact symptoms. Nutrient deficiencies correspond to the segment, depth, and extent of the gastrointestinal tract involved and can impact organs distant from the gut. Patients with non-EoE EGIDs are often atopic, and some appear to respond to dietary avoidance of specific food allergens. Tests to identify food triggers other than response to elimination diets are lacking. Dietary restriction therapy should be considered in such patients and is best implemented through a multidisciplinary approach to avoid nutritional complications.

Pharmacologic Management of Non-Eosinophilic Esophagitis Eosinophilic Gastrointestinal Diseases.

Data for pharmacologic treatments for non-eosinophilic esophagitis (EoE) eosinophilic gastrointestinal diseases (EGIDs) are limited. Nevertheless, because of the increasing understanding of EGID pathogenesis, a number of medications are used to treat EGIDs, though all are currently off-label. Initial therapy generally starts with corticosteroids, and "topical" delivery is preferred over systemic due to long-term side effects. A number of other small molecules could potentially be used, ranging from allergy medications to immunosuppressants. Biologics are also being used and investigated for EGIDs and represent promising targeted therapies. Multiple therapeutic targets have also been identified, many of which overlap with EoE targets.

Clinical Presentation of Patients with Eosinophilic Gastrointestinal Diseases beyond Eosinophilic Esophagitis.

The clinical presentation of eosinophilic gastrointestinal diseases beyond eosinophilic esophagitis (non-EoE EGIDs) varies depending on the gastrointestinal segments affected by the eosinophilic inflammation, the extent of eosinophilic inflammation within the gastrointestinal tract and its depth through the bowel wall. Non-EoE EGIDs with mucosal involvement tend to present with diarrhea, malabsorption, and sometimes bleeding, those with muscular involvement may present with symptoms of obstruction or pseudo-obstruction, intussusception, and even perforation, whereas those with serosal involvement may present with eosinophilic ascites. Here we describe the differences in symptoms experienced by children with non-EoE EGIDs with varying degrees of eosinophilic inflammation through the bowel wall.

A highly divergent enteric calicivirus in a bovine calf in India.

A highly divergent bovine calicivirus was identified in an Indian calf with enteritis. The whole genome of this virus was sequenced, revealing distinct amino acid motifs in the polyprotein encoded by open reading frame 1 (ORF1) that are unique to caliciviruses. Phylogenetic analysis showed that it was related to members of the genus Nebovirus of the family Caliciviridae. Although it showed only 33.7-34.2% sequence identity in the VP1 protein to the nebovirus prototype strains, it showed 90.6% identity in VP1 to Kirklareli virus, a nebovirus detected in calves with enteritis in Turkey in 2012. An in-house-designed and optimized reverse transcription polymerase chain reaction (RT-PCR) assay was used to screen 120 archived bovine diarrhoeic fecal samples, 40 each from the Indian states of Uttar Pradesh, Haryana, and Himachal Pradesh, revealing frequent circulation of these divergent caliciviruses in the bovine population, with an overall positivity rate of 64.17% (77/120). This underscores the importance of conducting a comprehensive investigation of the prevalence of these divergent caliciviruses and assessing their associations with other pathogens responsible for enteritis in India.