Gut microbiota promote liver regeneration through hepatic membrane phospholipid biosynthesis

肠道菌群通过肝膜磷脂生物合成促进肝再生

J Hepatol . 2023 Apr;78(4):820-835.  doi: 10.1016/j.jhep.2022.12.028. Epub 2023 Jan 18.

Yuhan Yin ¹, Anna Sichler ¹, Josef Ecker ², Melanie Laschinger ¹, Gerhard Liebisch ³, Marcus Höring ³, Marijana Basic ⁴, André Bleich ⁴, Xue-Jun Zhang ¹, Ludwig Kübelsbeck ¹, Johannes Plagge ², Emely Scherer ⁵, Dirk Wohlleber ⁵, Jianye Wang ¹, Yang Wang ¹, Marcella Steffani ¹, Pavel Stupakov ¹, Yasmin Gärtner ¹, Fabian Lohöfer ⁶, Carolin Mogler ⁷, Helmut Friess ¹, Daniel Hartmann ¹, Bernhard Holzmann ⁸, Norbert Hüser ⁹, Klaus-Peter Janssen ¹⁰

Abstract

Background & aims: Hepatocyte growth and proliferation depends on membrane phospholipid biosynthesis. Short-chain fatty acids (SCFAs) generated by bacterial fermentation, delivered through the gut-liver axis, significantly contribute to lipid biosynthesis. We therefore hypothesized that dysbiotic insults like antibiotic treatment not only affect gut microbiota, but also impair hepatic lipid synthesis and liver regeneration.

肝细胞的生长和增殖依赖于膜磷脂的生物合成。由细菌发酵产生的短链脂肪酸（SCFA）通过肠-肝轴递送，显著促进脂质生物合成。因此，我们假设抗生素治疗等微生态失调不仅影响肠道微生物群，而且还损害肝脏脂质合成和肝脏再生。

Methods: Stable isotope labeling and 70% partial hepatectomy (PHx) was carried out in C57Bl/6J wild-type mice, in mice treated with broad-spectrum antibiotics, in germ-free mice and mice colonized with minimal microbiota. The microbiome was analyzed by 16S rRNA gene sequencing and microbial culture. Gut content, liver, blood and primary hepatocyte organoids were tested by mass spectrometry-based lipidomics, quantitative reverse-transcription PCR (qRT-PCR), immunoblot and immunohistochemistry for expression of proliferative and lipogenic markers. Matched biopsies from hyperplastic and hypoplastic liver tissue of patients subjected to surgical intervention to induce hyperplasia were analyzed by qRT-PCR for lipogenic enzymes.

在C57 B1/6 J野生型小鼠、用广谱抗生素治疗的小鼠、无菌小鼠和用最小微生物群定殖的小鼠中进行稳定同位素标记和70%部分肝切除术（PHx）。通过16 S rRNA基因测序和微生物培养来分析微生物组。通过基于质谱的脂质组学、定量逆转录PCR（qRT-PCR）、免疫印迹和免疫组织化学测试肠内容物、肝脏、血液和原代肝细胞类器官的增殖和脂肪生成标志物的表达。通过qRT-PCR分析来自经受手术干预以诱导增生的患者的增生性和发育不良性肝组织的匹配活检物的脂肪生成酶。

Results: Three days of antibiotic treatment induced persistent dysbiosis with significantly decreased beta-diversity and richness, but a massive increase of Proteobacteria, accompanied by decreased colonic SCFAs. After PHx, antibiotic-treated mice showed delayed liver regeneration, increased mortality, impaired hepatocyte proliferation and decreased hepatic phospholipid synthesis. Expression of the lipogenic enzyme SCD1 was upregulated after PHx but delayed by antibiotic treatment. Germ-free mice essentially recapitulated the phenotype of antibiotic treatment. Phospholipid biosynthesis, hepatocyte proliferation, liver regeneration and survival were rescued in gnotobiotic mice colonized with a minimal SCFA-producing microbial community. SCFAs induced the growth of murine hepatocyte organoids and hepatic SCD1 expression in mice. Further, SCD1 was required for proliferation of human hepatoma cells and was associated with liver regeneration in human patients.

抗生素治疗3天可导致持续性失调，β-多样性和丰富度显著降低，但变形杆菌门大量增加，同时结肠SCFA减少。PHX治疗后小鼠肝再生延迟，死亡率升高，肝细胞增殖受损，肝磷脂合成减少。生脂酶SCD 1在PHX后表达上调，但因抗生素治疗而延迟表达。无菌小鼠在本质上重新描述了抗生素治疗的表型。磷脂生物合成、肝细胞增殖、肝再生和存活被克隆到极小的SCFA产生微生物群落中。SCFAs诱导小鼠肝细胞生长和肝SCD 1的表达。此外，SCD 1是人肝癌细胞增殖所必需的，并且与患者的肝再生有关

Conclusion: Gut microbiota are pivotal for hepatic membrane phospholipid biosynthesis and liver regeneration.

肠道微生物群对于肝膜磷脂生物合成和肝再生是关键的。

Impact and implications: Gut microbiota affect hepatic lipid metabolism through the gut-liver axis, but the underlying mechanisms are poorly understood. Perturbations of the gut microbiome, e.g. by antibiotics, impair the production of bacterial metabolites, which normally serve as building blocks for membrane lipids in liver cells. As a consequence, liver regeneration and survival after liver surgery is severely impaired. Even though this study is preclinical, its results might allow physicians in the future to improve patient outcomes after liver surgery, by modulation of gut microbiota or their metabolites.

肠道微生物群通过肠-肝轴影响肝脏脂质代谢，但其潜在机制尚不清楚。干扰肠道微生物组，例如通过抗生素，损害细菌代谢物的产生，其通常作为肝细胞中膜脂质的构建块。因此，肝脏手术后的肝脏再生和存活严重受损。尽管这项研究是临床前研究，但其结果可能允许医生在未来通过调节肠道微生物群或其代谢物来改善肝脏手术后的患者预后。

Keywords: Liver regeneration; intestinal microbiome; lipidomics; microbial metabolites; microbiota.