Abstract
BACKGROUND: Eosinophilic gastrointestinal diseases (EGIDs) are chronic, immune-mediated disorders characterised clinically by gastrointestinal symptoms and histologically by a pathologic increase in eosinophil-predominant inflammation in the gastrointestinal tract, in the absence of secondary causes of eosinophilia. AIMS: To highlight emerging insights and research efforts into the epidemiology, pathophysiology, diagnostic and therapeutic aspects of eosinophilic oesophagitis (EoE) and non-EoE EGIDs, and discuss key remaining knowledge gaps. METHODS: We selected and reviewed original research, retrospective studies, case series, randomised controlled trials, and meta-analyses. RESULTS: Standardised nomenclature classifies EGIDs as EoE, eosinophilic gastritis (EoG), eosinophilic enteritis (EoN), and eosinophilic colitis (EoC). Incidence and prevalence of EoE are rising, emphasising the need to better understand how environmental risk factors and genetic features interact. Advances in understanding EoE pathophysiology have led to clinical trials of targeted therapy and the approval (in the United States) of dupilumab for EoE. Several therapies that are under investigation hope to satisfy both histologic and clinical targets. For non-EoE EGIDs, efforts are focused on better defining clinical and histopathologic disease determinants and natural history, as well as establishing new therapies. CONCLUSIONS: Unmet needs for research are dramatically different for EoE and non-EoE EGIDs. In EoE, non-invasive diagnostic tests, clinicopathologic models that determine the risk of disease progression and therapeutic failure, and novel biologic therapies are emerging. In contrast, in non-EoE EGIDs, epidemiologic trends, diagnostic histopathologic thresholds, and natural history models are still developing for these more rare disorders.