Inflammatory bowel disease (IBD) is an immune-mediated inflammatory disease (IMID) of the gastrointestinal tract and includes two subtypes: Crohn’s disease and ulcerative colitis. It is well-recognized that IBD is associated with a complex multifactorial aetiology that includes genetic predisposition and environmental exposures, with downstream dysregulation of systemic immune function and host–microbial interactions in the local environment in the gut. Evidence to support the notion of a multistage development of IBD is growing, as has been observed in other IMIDs such as rheumatoid arthritis and systemic lupus erythematosus. With the rising worldwide incidence of IBD, it is increasingly important to understand the complex interplay of pathological events during the different stages of disease development to enable IBD prediction and prevention strategies. In this article, we review comprehensively the current evidence pertaining to the preclinical phase of IBD, including at-risk, initiation and expansion phases. We also discuss the framework of preclinical IBD, expanding on underlying pathways in IBD development, future research directions and IBD development in the context of other IMIDs.

炎症性肠病（IBD）是一种免疫介导的胃肠道炎症性疾病（IMID），包括两种亚型：克罗恩病和溃疡性结肠炎。众所周知，IBD 与复杂的多因素病因有关，包括遗传易感性和环境暴露，以及肠道局部环境中全身免疫功能和宿主-微生物相互作用的下游失调。支持 IBD 多阶段发展这一观点的证据正在不断增加，正如在类风湿关节炎和系统性红斑狼疮等其他 IMID 中观察到的那样。随着全球 IBD 发病率的上升，了解疾病发展不同阶段病理事件的复杂相互作用以实现 IBD 预测和预防策略变得越来越重要。在本文中，我们全面回顾了有关 IBD 临床前阶段的当前证据，包括风险阶段、启动阶段和扩展阶段。我们还讨论了临床前 IBD 的框架，扩展了 IBD 发展的基本途径、未来的研究方向以及其他 IMID 背景下的 IBD 发展。