It has recently become well-established that there is a connection between Alzheimer’s disease pathology and gut microbiome dysbiosis. We have previously demonstrated that antibiotic-mediated gut microbiota perturbations lead to attenuation of Aβ deposition, phosphorylated tau accumulation, and disease-associated glial cell phenotypes in a sex-dependent manner. In this regard, we were intrigued by the finding that a marine-derived oligosaccharide, GV-971, was reported to alter gut microbiota and reduce Aβ amyloidosis in the 5XFAD mouse model that were treated at a point when Aβ burden was near plateau levels. Utilizing comparable methodologies, but with distinct technical and temporal features, we now report on the impact of GV-971 on gut microbiota, Aβ amyloidosis and microglial phenotypes in the APPPS1-21 model, studies performed at the University of Chicago, and independently in the 5X FAD model, studies performed at Washington University, St. Louis. Methods To comprehensively characterize the effects of GV-971 on the microbiota-microglia-amyloid axis, we conducted two separate investigations at independent institutions. There was no coordination of the experimental design or execution between the two laboratories. Indeed, the two laboratories were not aware of each other’s experiments until the studies were completed. Male and female APPPS1-21 mice were treated daily with 40, 80, or 160 mg/kg of GV-971 from 8, when Aβ burden was detectable upto 12 weeks of age when Aβ burden was near maximal levels. In parallel, and to corroborate existing published studies and further investigate sex-related differences, male and female 5XFAD mice were treated daily with 100 mg/kg of GV-971 from 7 to 9 months of age when Aβ burden was near peak levels. Subsequently, the two laboratories independently assessed amyloid-β deposition, metagenomic, and neuroinflammatory profiles. Finally, studies were initiated at the University of Chicago to evaluate the metabolites in cecal tissue from vehicle and GV-971-treated 5XFAD mice. Results These studies showed that independent of the procedural differences (dosage, timing and duration of treatment) between the two laboratories, cerebral amyloidosis was reduced primarily in male mice, independent of strain. We also observed sex-specific microbiota differences following GV-971 treatment. Interestingly, GV-971 significantly altered multiple overlapping bacterial species at both institutions. Moreover, we discovered that GV-971 significantly impacted microbiome metabolism, particularly by elevating amino acid production and influencing the tryptophan pathway. The metagenomics and metabolomics changes correspond with notable reductions in peripheral pro-inflammatory cytokine and chemokine profiles. Furthermore, GV-971 treatment dampened astrocyte and microglia activation, significantly decreasing plaque-associated reactive microglia while concurrently increasing homeostatic microglia only in male mice. Bulk RNAseq analysis unveiled sex-specific changes in cerebral cortex transcriptome profiles, but most importantly, the transcriptome changes in the GV-971-treated male group revealed the involvement of microglia and inflammatory responses. Conclusions In conclusion, these studies demonstrate the connection between the gut microbiome, neuroinflammation, and Alzheimer’s disease pathology while highlighting the potential therapeutic effect of GV-971. GV-971 targets the microbiota-microglia-amyloid axis, leading to the lowering of plaque pathology and neuroinflammatory signatures in a sex-dependent manner when given at the onset of Aβ deposition or when given after Aβ deposition is already at higher levels.

中文翻译：

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寡甘露酸钠以性别特异性方式改变肠道微生物群，减少脑淀粉样变性和反应性小胶质细胞

最近已确定阿尔茨海默氏病病理学与肠道微生物群失调之间存在联系。我们之前已经证明，抗生素介导的肠道微生物群扰动会以性别依赖性方式导致 Aβ 沉积、磷酸化 tau 积累和疾病相关神经胶质细胞表型的减弱。在这方面，我们对以下发现很感兴趣：据报道，在 Aβ 负荷接近平台水平时接受治疗的 5XFAD 小鼠模型中，海洋来源的寡糖 GV-971 可以改变肠道微生物群并减少 Aβ 淀粉样变性。利用类似的方法，但具有不同的技术和时间特征，我们现在报告 GV-971 对 APPPS1-21 模型中肠道微生物群、Aβ 淀粉样变性和小胶质细胞表型的影响，该研究在芝加哥大学进行，并独立于5X FAD 模型，在圣路易斯华盛顿大学进行的研究。方法 为了全面表征 GV-971 对微生物群-小胶质细胞-淀粉样蛋白轴的影响，我们在独立机构进行了两项独立的研究。两个实验室之间的实验设计或执行没有协调。事实上，在研究完成之前，两个实验室并不知道对方的实验。雄性和雌性 APPPS1-21 小鼠从 8 岁开始每天接受 40、80 或 160 mg/kg 的 GV-971 治疗，此时 Aβ 负荷可检测到，直至 12 周龄，此时 Aβ 负荷接近最大水平。与此同时，为了证实现有已发表的研究并进一步调查性别相关差异，雄性和雌性 5XFAD 小鼠在 7 至 9 个月龄期间每天接受 100 mg/kg GV-971 治疗，此时 Aβ 负荷接近峰值水平。随后，两个实验室独立评估了β淀粉样蛋白沉积、宏基因组和神经炎症特征。最后，芝加哥大学启动了研究，评估媒介物和 GV-971 处理的 5XFAD 小鼠盲肠组织中的代谢物。结果这些研究表明，与两个实验室之间的程序差异（剂量、时间和治疗持续时间）无关，脑淀粉样变性主要在雄性小鼠中减少，与品系无关。我们还观察到 GV-971 治疗后性别特异性微生物群的差异。有趣的是，GV-971 显着改变了两个机构中多个重叠的细菌种类。此外，我们发现 GV-971 显着影响微生物代谢，特别是通过提高氨基酸产量和影响色氨酸途径。宏基因组学和代谢组学的变化与外周促炎细胞因子和趋化因子谱的显着减少相对应。此外，GV-971 治疗抑制了星形胶质细胞和小胶质细胞的激活，显着减少了斑块相关的反应性小胶质细胞，同时仅在雄性小鼠中增加了稳态小胶质细胞。批量 RNAseq 分析揭示了大脑皮层转录组谱的性别特异性变化，但最重要的是，GV-971 治疗的男性组中的转录组变化揭示了小胶质细胞和炎症反应的参与。结论 总之，这些研究证明了肠道微生物组、神经炎症和阿尔茨海默病病理学之间的联系，同时强调了 GV-971 的潜在治疗效果。 GV-971 以微生物群-小胶质细胞-淀粉样蛋白轴为目标，在 Aβ 沉积开始时或在 Aβ 沉积已经处于较高水平后给予时，会以性别依赖性方式降低斑块病理学和神经炎症特征。