Obesity is associated with metabolic, immunological, and infectious disease comorbidities, including an increased risk of enteric infection and inflammatory bowel disease such as Crohn's disease (CD). Expansion of intestinal pathobionts such as adherent-invasive Escherichia coli (AIEC) is a common dysbiotic feature of CD, which is amplified by prior use of oral antibiotics. Although high-fat, high-sugar diets are associated with dysbiotic expansion of E. coli, it is unknown if the content of fat or another dietary component in obesogenic diets is sufficient to promote AIEC expansion. Here, we found that administration of an antibiotic combined with feeding mice an obesogenic low fiber, high sucrose, high fat diet (HFD) that is typically used in rodent obesity studies promoted AIEC intestinal expansion. Even a short-term (i.e., 1-day) pulse of HFD feeding before infection was sufficient to promote AIEC expansion, indicating that the magnitude of obesity was not the main driver of AIEC expansion. Controlled diet experiments demonstrated that neither dietary fat nor sugar were the key determinants of AIEC colonization, but that lowering dietary fiber from approximately 13% to 5-6% was sufficient to promote intestinal expansion of AIEC when combined with antibiotics in mice. When combined with antibiotics, lowering fiber promoted AIEC intestinal expansion to a similar extent as widely used HFDs in mice. However, lowering dietary fiber was sufficient to promote AIEC intestinal expansion without affecting body mass. Our results show that low dietary fiber combined with oral antibiotics are environmental factors that promote expansion of Crohn's disease-associated pathobionts in the gut.

中文翻译：

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低膳食纤维促进与肥胖无关的克罗恩病相关病原体的肠道扩张

肥胖与代谢、免疫和传染病合并症有关，包括肠道感染和炎症性肠病（如克罗恩病 (CD)）的风险增加。肠道病原体如粘附侵袭性大肠杆菌 (AIEC) 的扩张是 CD 常见的生态失调特征，通过先前使用口服抗生素而放大。尽管高脂肪、高糖饮食与大肠杆菌的生态失调扩张有关，但尚不清楚致肥胖饮食中脂肪或其他饮食成分的含量是否足以促进 AIEC 扩张。在这里，我们发现将抗生素与给小鼠喂食一种通常用于啮齿动物肥胖研究的致肥胖低纤维、高蔗糖、高脂肪饮食 (HFD) 相结合，促进了 AIEC 肠道扩张。即使是短期（即 1 天）感染前 HFD 喂养的脉冲足以促进 AIEC 扩张，表明肥胖程度不是 AIEC 扩张的主要驱动因素。对照饮食实验表明，膳食脂肪和糖都不是 AIEC 定植的关键决定因素，但将膳食纤维从大约 13% 降低到 5-6% 足以促进 AIEC 肠道扩张，当与小鼠中的抗生素结合时。当与抗生素结合使用时，降低纤维促进 AIEC 肠道扩张的程度与在小鼠中广泛使用的 HFD 相似。然而，降低膳食纤维足以促进 AIEC 肠道扩张而不影响体重。我们的研究结果表明，低膳食纤维结合口服抗生素是促进克罗恩病扩张的环境因素