Muir, Amanda B.

Background Eosinophilic oesophagitis (EoE) is a food allergen-induced inflammatory disorder characterised by interleukin (IL)-13-mediated oesophageal inflammation and epithelial basal cell hyperplasia (BCH). The role of mitochondria in EoE pathogenesis remains elusive. Design Prompted by single cell transcriptomics data, we interrogated the role of mitochondria in EoE pathobiology using patient biopsies, EoE-mouse models and oesophageal epithelial cells grown in monolayer and three-dimensional (3D) organoid cultures treated with EoE-relevant cytokines. 3D organoids and EoE-bearing mice were treated with omeprazole—a proton-pump inhibitor used as first-line EoE therapy. We performed CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) interference in mouse organoids to identify the key mitochondrial regulatory genes whose depletion may lead to BCH. We analysed mitochondrial membrane potential, mass and superoxide production by flow cytometry, cellular oxygen consumption by respirometry, mitochondrial structures and perturbation of cellular energy homeostasis by immunoblotting. Results Mitochondrial dysfunction appeared to be a hallmark of EoE-related BCH where mitochondrial structural damage was associated with impaired oxidative respiratory capacity, elevation of mitochondrial superoxide and decreased adenosine triphosphate (ATP) production, as corroborated by activation of the adenosine monophosphate (AMP) -activated protein kinase and suppression of mammalian target-of-rapamycin signalling. Depletion of PGC1A, the master regulator of mitochondria biogenesis, recapitulated EoE-related BCH, suggesting that mitochondrial dysfunction drives BCH. Further, omeprazole alleviated mitochondrial damage and dysfunction in EoE-related BCH modelled in mice and patient-derived organoids. Conclusion Mitochondrial dysfunction is tightly linked to perturbation of redox homeostasis in EoE-related BCH, which is promoted by IL-13 and reversible with omeprazole treatment.

In response to the social inequities that exist in health care, the NIH-funded Consortium of Eosinophilic Gastrointestinal Disease Researchers (CEGIR) recently formed a diversity committee to examine systemic racism and implicit bias in the care and research of eosinophilic gastrointestinal diseases (EGIDs). Herein, we describe our process, highlighting milestones and issues addressed since the committee’s inception, which we hope will inspire other researchers to enhance diversity, equity, inclusion, and accessibility (DEIA) in their fields. Our journey began by establishing mission and vision statements to define the purpose of the committee. Regular discussion of diversity-related topics was incorporated into existing meetings and web-based materials were shared. This was followed by educational initiatives, including establishing a library of relevant publications and a speaker series to address DEIA topics. We then established a research agenda focused on the following actionable items: (1) to define what is known about the demographics of EGIDs by systematic review of population-based studies; (2) to develop a practical tool for reporting participant demographics to reduce bias in EGID literature; (3) to examine health disparities in the care of individuals with eosinophilic esophagitis who present to the emergency department with an esophageal food impaction; (4) to examine how access to a gastroenterologist affects the conclusions of published research examining the prevalence of pediatric eosinophilic esophagitis; and (5) to develop a model for examining the dimensions of diversity, and provide a framework for CEGIR’s ongoing projects and data capture. In addition to promoting consciousness of DEIA, this initiative has fostered inclusivity among CEGIR members and will continue to inspire positive changes in EGID care and research.