The microbiota-gut-brain axis has emerged as a focal point of biomedical research. Alterations of gut microbiota are involved in not only various immune/inflammatory disorders but also neurological disorders including Alzheimer's disease (AD). The initial stage of the involvement of gut microbiota in the pathogenesis of AD may be the dysfunction of the blood-brain barrier (BBB). Gut microbiota-derived products in the circulation can worsen the BBB integrity, easily cross the disrupted BBB and enter the brain to promote pathological changes in AD. In this review, we first summarize the current evidence of the associations among gut microbiota, AD, and BBB integrity. We then discuss the mechanism of gut microbiota on BBB dysfunction with a focus on bacteria-derived lipopolysaccharide and exosomal high-mobility group box 1. Novel insights into the modification of the BBB as an intervention approach for AD are highlighted as well.

微生物-肠-脑轴已成为生物医学研究的焦点。肠道菌群的改变不仅涉及各种免疫/炎症性疾病，还涉及包括阿尔茨海默病 (AD) 在内的神经系统疾病。肠道菌群参与 AD 发病机制的初始阶段可能是血脑屏障 (BBB) 的功能障碍。循环中的肠道菌群衍生产物会使血脑屏障完整性恶化，容易穿过破坏的血脑屏障进入大脑，促进AD的病理变化。在这篇综述中，我们首先总结了目前肠道微生物群、AD 和 BBB 完整性之间关联的证据。然后，我们讨论了肠道微生物群对 BBB 功能障碍的机制，重点是细菌衍生的脂多糖和外泌体高迁移率组框 1。