The mechanisms underlying maternal obesity-induced microbial DNA accumulation in fetus and offspring metabolic abnormalities

项目总结/摘要 儿童肥胖/2型糖尿病的增加与全球肥胖相关疾病的增加相平行。 代谢综合征母亲肥胖是与以下疾病发生率密切相关的关键驱动因素之一： 后代肥胖和代谢紊乱。然而，孕产妇死亡的影响机制 肥胖对后代代谢紊乱的影响尚不完全清楚。我们最近的研究发现 CRIg+巨噬细胞保护宿主细胞免受肠道微生物含DNA的细胞外囊泡的影响， （mEV）诱导的细胞异常，而CRIg+巨噬细胞在肥胖的背景下不存在， 无论是人类还是小鼠，都伴随着宿主细胞中细菌DNA的富集， 敏感性或胰岛素分泌。肠道mEV可以容易地穿过肥胖小鼠的肠道屏障， 进一步将微生物DNA递送到关键代谢组织中。我们进一步证明了CRIg+的关键作用 巨噬细胞在从血流中清除肠道mEV中的作用，如微生物的大量积累所证明的。 静脉注射肠道mEV后NCD CRIg-/-小鼠中关键代谢组织内的DNA。相比之下， NCD WT小鼠中的CRIg+细胞通过C3介导的机制阻断了肠道mEV的浸润，因此 防止细菌DNA在宿主细胞中富集。有效减毒的CRIg+细胞的回收率 组织炎症和代谢紊乱。微生物DNA的消耗削弱了 肠道mEV的致病作用，而微生物DNA的积累触发了 cGAS/STING途径检测宿主细胞异常。相比之下，cGAS的敲除阻止了微生物DNA- 诱发细胞紊乱这些结果导致CRIg+巨噬细胞保护宿主细胞的结论。 从肠道mEV的发病机制。我们还发现CRIg+巨噬细胞群体显著减少， 在肥胖妊娠的母体肝脏和胎盘中，伴随着胚胎中细菌DNA的富集。 相比之下，瘦妊娠小鼠在胎盘中具有高丰度的CRIg+巨噬细胞，并且没有16 s 在它们的胚胎中检测到rRNA。母体肠道mEV可以到达并将微生物DNA递送到 在肥胖妊娠小鼠或瘦CRIg-/-小鼠中，但在瘦WT小鼠中没有。因此，这项建议旨在 揭示CRIg+巨噬细胞在妊娠中的重要作用以及母体肥胖诱导的 胚胎微生物DNA富集对后代代谢反应的影响。我们将进一步确定：1）关键 母体CRIg+巨噬细胞在阻断肠道mEV浸润到胚胎中的作用; 2）母体CRIg+巨噬细胞的作用 母体肥胖对胚胎CRIg+巨噬细胞发育的影响; 3）母体肥胖对胚胎CRIg+巨噬细胞发育的影响。 诱导胚胎微生物DNA积累对后代组织炎症和代谢表型的影响。

Project Summary/Abstract The increase in childhood obesity/Type 2 diabetes is paralleling a worldwide increase in obesity-associated metabolic syndrome. Maternal obesity is one of the key drivers tightly associated with the incidence of offspring obesity and metabolic disorders. However, the mechanisms underlying the impacts of maternal obesity on offspring metabolic disorders are not fully understood. Our recent work has led to the discovery that CRIg+ macrophages protect host cells from the gut microbial DNA-containing extracellular vesicle (mEV)-induced cellular abnormalities, whereas CRIg+ macrophages are absent in the context of obesity in both humans and mice, accompanied with enrichment of bacterial DNAs in host cells and worsen insulin sensitivity or insulin secretion. Intestinal mEVs can readily pass through the gut barrier of obese mice and further deliver microbial DNAs into key metabolic tissues. We further demonstrated the critical role of CRIg+ macrophages in clearing gut mEVs from bloodstream, as evidenced by a robust accumulation of microbial DNAs within key metabolic tissues in NCD CRIg-/- mice after intravenously injected with gut mEVs. By contrast, CRIg+ cells in NCD WT mice blocked the infiltration of gut mEVs through a C3-mediated mechanism, thus preventing the enrichment of bacterial DNAs in host cells. Recovery of CRIg+ cells efficiently attenuated tissue inflammation and metabolic disorders in obese mice. Depletion of microbial DNAs blunted the pathogenic effects of gut mEVs, while accumulation of microbial DNAs triggered the activation of cGAS/STING pathway for host cell abnormalities. By contrast, knockout of cGAS prevented microbial DNA- induced cellular disorders. These results lead to the conclusion that CRIg+ macrophages protect host cells from the pathogenesis of gut mEVs. We also found a significant reduction in CRIg+ macrophage population in maternal liver and placenta in obese pregnancy, concomitant with bacterial DNA enrichment in embryos. By contrast, lean pregnant mice harbored high abundance of CRIg+ macrophages in placenta, and no 16s rRNAs were detected in their embryos. Maternal gut mEVs can reach and deliver microbial DNAs into embryos in obese pregnant mice or lean CRIg-/- mice, but not in lean WT mice. Thus, this proposal seeks to reveal the important roles of CRIg+ macrophages in pregnancy and the impacts of maternal obesity-induced embryonic microbial DNA enrichment on offspring metabolic responses. We will further determine: 1) critical roles of maternal CRIg+ macrophages in blocking the infiltration of gut mEVs into embryos; 2) effects of maternal obesity on the development of embryonic CRIg+ macrophages; 3) effects of maternal obesity- induced embryonic microbial DNA accumulation on offspring tissue inflammation and metabolic phenotypes.