Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal tract that results from dysfunction in innate and/or adaptive immune responses. Impaired innate immunity, which leads to lack of control of an altered intestinal microbiota and to activation of the adaptive immune system, promotes a secondary inflammatory response that is responsible for tissue damage. Neutrophils are key players in innate immunity in IBD, but their roles have been neglected compared with those of other immune cells. The latest studies on neutrophils in IBD have revealed unexpected complexities, with heterogeneous populations and dual functions, both deleterious and protective, for the host. In parallel, interconnections between disease development, intestinal microbiota and neutrophils have been highlighted. Numerous IBD susceptibility genes (such as NOD2, NCF4, LRRK2, CARD9) are involved in neutrophil functions related to defence against microorganisms. Moreover, severe monogenic diseases involving dysfunctional neutrophils, including chronic granulomatous disease, are characterized by intestinal inflammation that mimics IBD and by alterations in the intestinal microbiota. This observation demonstrates the dialogue between neutrophils, gut inflammation and the microbiota. Neutrophils affect microbiota composition and function in several ways. In return, microbial factors, including metabolites, regulate neutrophil production and function directly and indirectly. It is crucial to further investigate the diverse roles played by neutrophils in host–microbiota interactions, both at steady state and in inflammatory conditions, to develop new IBD therapies. In this Review, we discuss the roles of neutrophils in IBD, in light of emerging evidence proving strong interconnections between neutrophils and the gut microbiota, especially in an inflammatory context.

炎症性肠病 (IBD) 是一种胃肠道慢性炎症性疾病，由先天性和/或适应性免疫反应功能障碍引起。先天免疫受损会导致肠道微生物群的改变失去控制并导致适应性免疫系统激活，从而促进继发性炎症反应，从而导致组织损伤。中性粒细胞是 IBD 先天免疫的关键参与者，但与其他免疫细胞相比，它们的作用被忽视了。对 IBD 中性粒细胞的最新研究揭示了意想不到的复杂性，其具有异质性群体和双重功能，对宿主既有害又具有保护作用。与此同时，疾病发展、肠道微生物群和中性粒细胞之间的相互关系也得到了强调。众多IBD易感基因（例如NOD2、NCF4、) 参与中性粒细胞与微生物防御相关的功能。此外，涉及功能失调的中性粒细胞的严重单基因疾病，包括慢性肉芽肿性疾病，其特征是模仿IBD的肠道炎症和肠道微生物群的改变。这一观察结果证明了中性粒细胞、肠道炎症和微生物群之间的对话。中性粒细胞以多种方式影响微生物群的组成和功能。作为回报，微生物因素，包括代谢物，直接和间接调节中性粒细胞的产生和功能。进一步研究中性粒细胞在稳态和炎症条件下宿主-微生物群相互作用中发挥的不同作用对于开发新的 IBD 疗法至关重要。在这篇综述中，我们讨论了中性粒细胞在 IBD 中的作用，因为新出现的证据证明中性粒细胞和肠道微生物群之间存在密切的相互联系，尤其是在炎症环境中。CARD9、LRRK2