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

项目摘要/摘要 儿童肥胖症/2型糖尿病的增加与全球范围内与肥胖相关的增加是同步的 代谢综合征。母亲肥胖是与糖尿病发病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，母体感染的潜在影响机制 肥胖对后代代谢紊乱的影响尚不完全清楚。我们最近的工作导致了这一发现 CRIG+巨噬细胞保护宿主细胞免受肠道微生物DNA胞外小泡的侵袭 (MEV)诱导的细胞异常，而在肥胖的背景下，CRIG+巨噬细胞缺失 人和小鼠，伴随宿主细胞中细菌DNA的丰富和胰岛素的恶化 敏感度或胰岛素分泌。肠道MEV可以很容易地通过肥胖小鼠的肠道屏障，并 进一步将微生物DNA输送到关键的新陈代谢组织。我们进一步证明了CRIG+的关键作用 巨噬细胞在清除肠道血流中的作用，从微生物的强劲积累中得到证明 NCD Crig-/-小鼠静脉注射肠道MEVs后关键代谢组织中的DNA。相反， NCD WT小鼠的CRIG+细胞通过C3介导的机制阻断肠道MEVs的渗透，从而 防止细菌DNA在宿主细胞中的浓缩。有效弱化CRIG+细胞的恢复 肥胖小鼠的组织炎症和代谢紊乱。微生物DNA的枯竭使 肠道病毒的致病作用，而微生物DNA的积累触发了 宿主细胞异常的cGAS/STING通路。相比之下，cGAS的敲除阻止了微生物DNA- 引起的细胞紊乱。这些结果导致了CRIG+巨噬细胞保护宿主细胞的结论 从肠道MEVS的发病机制来看。我们还发现CRIG+巨噬细胞数量显著减少 在肥胖妊娠的母体肝脏和胎盘中，伴随着胚胎中细菌DNA的丰富。 相比之下，瘦弱怀孕的小鼠胎盘中含有大量的CRIG+巨噬细胞，而没有16S 在它们的胚胎中检测到了rRNA。母体肠道胚胎可以接触到微生物DNA并将其输送到 在肥胖怀孕的小鼠或瘦的Crig-/-小鼠中的胚胎，但在瘦的WT小鼠中不是。因此，这项提案旨在 揭示CRIG+巨噬细胞在妊娠中的重要作用及母体肥胖的影响 胚胎微生物DNA浓缩对后代代谢反应的影响。我们将进一步确定：1)危急 母体CRIG+巨噬细胞在阻断肠道胚胎渗透中的作用；2) 母亲肥胖对胚胎CRIG+巨噬细胞发育的影响；3)母亲肥胖的影响- 诱导胚胎微生物DNA积聚对子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.