Specific Microbiome Changes in a Mouse Model of Parenteral Nutrition Associated Liver Injury and Intestinal Inflammation

BackgroundParenteral nutrition (PN) has been a life-saving treatment in infants intolerant of enteral feedings. However, PN is associated with liver injury (PN Associated Liver Injury: PNALI) in a significant number of PN-dependent infants. We have previously reported a novel PNALI mouse model in which PN infusion combined with intestinal injury results in liver injury. In this model, lipopolysaccharide activation of toll-like receptor 4 signaling, soy oil-derived plant sterols, and pro-inflammatory activation of Kupffer cells (KCs) played key roles. The objective of this study was to explore changes in the intestinal microbiome associated with PNALI.Methodology and Principal FindingsMicrobiome analysis in the PNALI mouse identified specific alterations within colonic microbiota associated with PNALI and further association of these communities with the lipid composition of the PN solution. Intestinal inflammation or soy oil-based PN infusion alone (in the absence of enteral feeds) caused shifts within the gut microbiota. However, the combination resulted in accumulation of a specific taxon, Erysipelotrichaceae (23.8% vs. 1.7% in saline infused controls), in PNALI mice. Moreover, PNALI was markedly attenuated by enteral antibiotic treatment, which also was associated with significant reduction of Erysipelotrichaceae (0.6%) and a Gram-negative constituent, the S24-7 lineage of Bacteroidetes (53.5% in PNALI vs. 0.8%). Importantly, removal of soy oil based-lipid emulsion from the PN solution resulted in significant reduction of Erysipelotrichaceae as well as attenuation of PNALI. Finally, addition of soy-derived plant sterol (stigmasterol) to fish oil-based PN restored Erysipelotrichaceae abundance and PNALI.ConclusionsSoy oil-derived plant sterols and the associated specific bacterial groups in the colonic microbiota are associated with PNALI. Products from these bacteria may directly trigger activation of KCs and promote PNALI. Furthermore, the results indicate that lipid modification of PN solutions may alter specific intestinal bacterial species associated with PNALI, and thus suggest strategies for management of PNALI.

背景：对于肠内营养不耐受的婴儿而言，肠外营养（Parenteral Nutrition, PN）一直是救命性治疗手段。然而，相当比例依赖肠外营养的婴儿会出现肠外营养相关性肝损伤（PN Associated Liver Injury, PNALI）。我们此前曾报道一种新型PNALI小鼠模型：将肠外营养输注与肠损伤相结合可诱导肝损伤。在该模型中，脂多糖激活的Toll样受体4信号通路、大豆油来源的植物固醇以及库普弗细胞（Kupffer cells, KCs）的促炎激活发挥了关键作用。本研究旨在探索与PNALI相关的肠道菌群变化。

研究方法与主要结果：对PNALI小鼠的肠道菌群分析显示，结肠菌群存在与PNALI相关的特异性改变，且这些菌群群落与肠外营养溶液的脂质组成存在显著关联。单纯肠道炎症或单纯输注基于大豆油的肠外营养（无肠内营养供给时）即可引起肠道菌群结构移位；但二者联合可导致PNALI小鼠体内的丹毒丝菌科（Erysipelotrichaceae）丰度显著富集，该菌在PNALI小鼠中占比达23.8%，而生理盐水输注对照组仅为1.7%。此外，肠内抗生素治疗可显著缓解PNALI，同时丹毒丝菌科丰度降至0.6%，另一革兰氏阴性菌组分——拟杆菌门（Bacteroidetes）S24-7谱系的丰度也从PNALI小鼠中的53.5%降至0.8%。值得注意的是，从肠外营养溶液中移除大豆油基脂质乳剂后，丹毒丝菌科丰度显著降低，同时PNALI症状得到缓解。最终，在鱼油基肠外营养溶液中添加大豆来源的植物固醇（豆甾醇，stigmasterol）可恢复丹毒丝菌科的丰度并重现PNALI表型。

结论：大豆油来源的植物固醇与结肠菌群中的特定细菌类群与PNALI密切相关。这些细菌产生的代谢物可能直接激活库普弗细胞，进而促进PNALI的发生。此外，本研究结果表明，对肠外营养溶液的脂质成分进行修饰可改变与PNALI相关的特定肠道菌群，从而为PNALI的临床管理提供潜在策略。