Data Sheet 1_Modified Dachengqi Decoction ameliorates sepsis-induced lung injury via the gut microbiota-bile acid axis.xlsx

BackgroundSepsis-induced acute lung injury (SI-ALI) is associated with high mortality. The gut microbiota-bile acid axis plays a critical role in regulating host inflammatory responses; however, the mechanism of action of traditional Chinese medicine (TCM) compounds targeting this axis remains unclear.
AimThis study aimed to systematically evaluate the protective effects of Modified DaChengqi Decoction (MDD) against lipopolysaccharide (LPS)-induced SI-ALI and to elucidate its underlying mechanism in modulating inflammation and neutrophil extracellular traps (NETs) through the regulation of gut microbiota and bile acid metabolism.
MethodsAn LPS-induced mouse model of SI-ALI was established. Mice were orally administered MDD, and 72−h survival rate, lung function, histopathology, and inflammatory cytokine levels were assessed. Fecal 16S rRNA sequencing and targeted bile acid metabolomics were combined to analyze changes in the microbiota and metabolites. Network pharmacology was employed to screen key targets, followed by experimental validation using Western blotting, immunohistochemistry, and ELISA to confirm candidate pathways.
ResultsCompared with the model group, MDD significantly improved survival and lung function, alleviated pulmonary inflammation and vascular permeability. Microbiomic analysis revealed that MDD downregulated the abundance of Parabacteroides and Bacteroides. Targeted metabolomics showed that MDD markedly altered the levels of several primary and secondary bile acids, mainly including glycoursodeoxycholic acid (GUDCA), taurochenodesoxycholic acid (TCDCA), chenodeoxycholic acid (CDCA), and taurocholic acid (TCA). Molecular validation demonstrated that the nuclear receptor FXR was significantly upregulated, while the TLR4 and downstream MYD88-NF−κB/JNK signaling pathways were inhibited. Additionally, the expression of PAD4 and CitH3 as well as NETs formation were reduced.
ConclusionMDD can alleviate LPS-induced SI-ALI by modulating the gut microbiota-bile acid metabolism, activating FXR, and thereby suppressing the TLR4/MYD88−mediated inflammatory cascade and NETs generation.

研究背景：脓毒症诱导的急性肺损伤（Sepsis-induced Acute Lung Injury, SI-ALI）病死率居高不下。肠道菌群-胆汁酸轴在调控宿主炎症反应中发挥关键作用，但中药复方（Traditional Chinese Medicine, TCM）靶向该轴的作用机制仍未明确。
研究目的：本研究旨在系统评价改性大承气汤（Modified DaChengqi Decoction, MDD）对脂多糖（lipopolysaccharide, LPS）诱导的SI-ALI的保护作用，并阐明其通过调控肠道菌群与胆汁酸代谢，进而调节炎症反应与中性粒细胞胞外陷阱（neutrophil extracellular traps, NETs）形成的潜在分子机制。
研究方法：构建脂多糖诱导的SI-ALI小鼠模型，对小鼠灌胃给予MDD，检测其72小时生存率、肺功能、组织病理学特征及炎症因子水平。联合粪便16S rRNA基因测序与靶向胆汁酸代谢组学分析菌群与代谢物的变化；采用网络药理学（network pharmacology）筛选关键靶点，并通过蛋白质印迹法（Western blotting）、免疫组织化学法（immunohistochemistry）与酶联免疫吸附测定法（Enzyme-Linked ImmunoSorbent Assay, ELISA）进行实验验证，以确认候选通路。
研究结果：与模型组相比，MDD可显著提升小鼠生存率与肺功能，减轻肺部炎症与血管通透性。微生物组分析显示，MDD可下调副杆菌属（Parabacteroides）与拟杆菌属（Bacteroides）的丰度。靶向代谢组学结果表明，MDD可显著改变多种初级与次级胆汁酸的水平，主要包括糖熊去氧胆酸（glycoursodeoxycholic acid, GUDCA）、牛磺鹅去氧胆酸（taurochenodesoxycholic acid, TCDCA）、鹅去氧胆酸（chenodeoxycholic acid, CDCA）及牛磺胆酸（taurocholic acid, TCA）。分子验证实验证实，核受体FXR（nuclear receptor FXR）显著上调，而Toll样受体4（Toll-like receptor 4, TLR4）及下游MYD88介导的NF-κB/JNK信号通路被抑制。此外，PAD4、CitH3的表达及NETs形成均显著降低。
研究结论：MDD可通过调控肠道菌群-胆汁酸代谢、激活核受体FXR，进而抑制TLR4/MYD88介导的炎症级联反应与NETs生成，从而缓解脂多糖诱导的SI-ALI。