红景天苷对PM_(2.5)暴露小鼠肠道微生物的调节作用

Moderating effect of salidroside on intestinal microbiota in mice exposed to PM_(2.5)

[背景]红景天苷(SAL)对多器官系统具有保护作用。大气细颗粒物(PM_(2.5))暴露可造成肠道微生物紊乱,损害肠道健康。SAL对PM_(2.5)暴露小鼠肠道微生物的调节作用有待深入研究。[目的]探讨PM_(2.5)对小鼠肠道菌群的影响及SAL的作用。[方法]40只6~8周龄C57BL/6雄性小鼠随机分成4组,每组10只,即对照组、SAL组、PM_(2.5)组、SAL+PM_(2.5)组。SAL组、SAL+PM_(2.5)组SAL灌胃(60 mg·kg^(–1)),对照组、PM_(2.5)组无菌生理盐水灌胃(10 mL·kg^(–1));PM_(2.5)组、SAL+PM_(2.5)组PM_(2.5)悬液气管滴注(8 mg·kg^(–1)),对照组、SAL组无菌生理盐水气管滴注(1.5 mL·kg^(–1))。2 d为1个实验周期,共进行10个周期,持续20 d。苏木素-伊红染色观察小鼠回肠组织病理变化。采集结肠内容物用于肠道微生物测序与短链脂肪酸(SCFAs)测定。[结果]PM_(2.5)组回肠组织炎症细胞浸润,SAL+PM_(2.5)组仅有少量炎症细胞浸润。与对照组相比,PM_(2.5)组Shannon降低(P<0.05),Simpson升高(P<0.05),该组肠道菌群多样性下降;SAL+PM_(2.5)组Shannon较PM_(2.5)组升高(P<0.05),Simpson降低(P<0.05),经SAL干预的小鼠肠道菌群多样性上升。主坐标分析结果显示PM_(2.5)暴露组与对照组之间出现明显分离,对照组、SAL组与SAL+PM_(2.5)组之间分离趋势不明显。非加权组平均法(UPGMA)聚类树结果显示对照组与SAL组最先被聚类在一起,两组再与SAL+PM_(2.5)组聚类,最后三组与PM_(2.5)组聚类。PCoA分析与UPGMA聚类结果均表示,PM_(2.5)组均匀度与相似性显著降低。与对照组相比,PM_(2.5)组拟杆菌门、Candidatus_Saccharimonas丰度降低(P<0.05),变形菌门、埃希氏菌属、拟杆菌属、普罗菲登斯菌属、肠球菌属与变形杆菌属丰度升高(P<0.05)。与PM_(2.5)组相比,SAL+PM_(2.5)组变形菌门、放线菌门、普罗菲登斯菌属、变形杆菌属丰度降低(P<0.05),Candidatus_Saccharimonas相对丰度显著升高(P<0.05)。PM_(2.5)组丙酸、戊酸、己酸的含量较对照组降低(P<0.05),SAL+PM_(2.5)组丙酸、异丁酸、丁酸、戊酸、己酸的含量较PM_(2.5)组升高(P<0.05)。[结论]呼吸道PM_(2.5)暴露可引起小鼠肠组织病理改变、肠道微生物紊乱以及SCFAs的变化,而SAL能够在一定程度上起到保护作用。

[Background]Salidroside(SAL)has a protective effect on multiple organ systems.Exposure to fine particulate matter(PM_(2.5))in the atmosphere may lead to disruptions in gut microbiota and impact intestinal health.The regulatory effect of SAL on the gut microbiota of mice exposed to PM_(2.5) requires further investigation.[Objective]To evaluate gut microbiota disruption in mice after being exposed to PM_(2.5) and the potential effect of SAL.[Methods]Forty male C57BL/6 mice,aged 6 to 8 weeks,were randomly divided into four groups:a control group,an SAL group,a PM_(2.5) group,and an SAL+PM_(2.5) group,each containing 10 mice.In the SAL group and the SAL+PM_(2.5) group,the mice were administered SAL(60 mg·kg^(−1))by gavage,while in the control group and the PM_(2.5) group,sterile saline(10 mL·kg^(−1))was administered by gavage.In the PM_(2.5) group and the SAL+PM_(2.5) group,PM_(2.5) suspension(8 mg·kg^(−1))was intratracheally instilled,and in the control group and SAL group,sterile saline(1.5 mL·kg^(−1))was intratracheally administered.Each experiment cycle spanned 2 d,with a total of 10 cycles conducted over 20 d.Histopathological changes in the ileum tissue of the mice were observed after HE staining.Colon contents were collected for gut microbiota sequencing and short-chain fatty acids(SCFAs)measurements.[Results]The PM_(2.5) group showed infiltration of inflammatory cells in the ileum tissue,while the SAL+PM_(2.5) group exhibited only a small amount of inflammatory cell infiltration.Compared to the control group,the PM_(2.5) group showed decreased Shannon index(P<0.05)and increased Simpson index(P<0.05),indicating that the diversity of gut microbiota in this group was decreased;the SAL+PM_(2.5) group showed increased Shannon index compared to the PM_(2.5) group(P<0.05)and decreased Simpson index(P<0.05),indicating that the diversity of gut microbiota in mice intervened with SAL was increased.The principal coordinates analysis(PCoA)revealed a significant separation between the PM_(2.5) group and the control group,while the separation trend was less evident among the control group,the SAL group,and the SAL+PM_(2.5) group.The unweighted pair-group method with arithmetic means(UPGMA)clustering tree results showed that the control group and the SAL group clustered together first,followed by clustering with the SAL+PM_(2.5) group,and finally,the three groups clustered with the PM_(2.5) group.The PCoA and UPGMA clustering results indicated that the uniformity and similarity of the microbiota in the PM_(2.5) group were significantly decreased.Compared to the control group,the PM_(2.5) group showed decreased abundance of phylum Bacteroidetes and Candidatus_Saccharimonas(P<0.05)and increased abundance of phylum Proteobacteria,genus Escherichia,genus Bacteroides,genus Prevotella,genus Enterococcus,and genus Proteus(P<0.05).Compared to the PM_(2.5) group,the SAL+PM_(2.5) group showed decreased abundance of phylum Proteobacteria,phylum Actinobacteria,genus Prevotella,and genus Proteus(P<0.05),and increased abundance of Candidatus_Saccharimonas(P<0.05).The PM_(2.5) group showed reduced levels of propionic acid,valeric acid,and hexanoic acid compared to the control group(P<0.05),while the SAL+PM_(2.5) group showed increased levels of propionic acid,isobutyric acid,butyric acid,valeric acid,and hexanoic acid compared to the PM_(2.5) group(P<0.05).[Conclusion]Exposure to PM_(2.5) can cause pathological alterations,microbial dysbiosis,and disturbing production of SCFAs in intestinal tissue in mice.However,SAL can provide a certain degree of protective effect against these changes.