背景:下呼吸道感染(LRTIs)的发病机制已被证明与呼吸道微生物群的菌群失调密切相关。黄芩,中药,广泛用于治疗呼吸道感染。然而,黄芩对LRTI的治疗效果是否取决于呼吸道微生物群的调节,目前尚不清楚。
目的:研究黄芩对LRTI小鼠呼吸道菌群的潜在影响及其机制。
方法:使用肺炎克雷伯菌或肺炎链球菌建立LRTI小鼠模型。进行抗生素治疗,并进行了呼吸道微生物群的移植,以耗尽小鼠的呼吸道微生物群并恢复被破坏的微生物群落,分别。采用高效液相色谱法(HPLC)对黄芩水煎液(SBWD)的化学成分进行定量测定。肺组织病理变化及血清炎症因子的表达,包括白细胞介素-17A(IL-17A),粒细胞-巨噬细胞集落刺激因子(GM-CSF),白细胞介素-6(IL-6),和肿瘤坏死因子-α(TNF-α),通过苏木精和伊红(H&E)染色和酶联免疫吸附测定(ELISA),分别。进行定量实时PCR(qRT-PCR)分析以检测GM-CSF的mRNA表达。进行宏基因组测序以评估SBWD对LRTI小鼠中呼吸道微生物群的组成和功能的影响。
结果:七个主要组成部分,包括Scutellarin,黄芩苷,奥木精A-7-O-β-d-葡糖苷酸,沃戈诺赛德,黄芩素,Wogonin,和oroxylinA,进行了鉴定,并对它们在SBWD中的水平进行了定量。SBWD改善肺炎克雷伯菌和肺炎链球菌诱导的LRTI小鼠的肺病理损伤和炎症反应,正如血清炎性细胞因子水平的剂量依赖性降低所证明的那样,IL-6和TNF-α。SBWD可能对LRTI小鼠的宿主先天性免疫反应具有双向调节作用,并以依赖微生物群的方式调节IL-17A和GM-CSF的表达。肺炎克雷伯菌感染而非肺炎克雷伯菌感染导致呼吸道微生物群的菌群失调,通过以细菌富集为特征的分类学组成的干扰来证明,包括变形杆菌,肠杆菌科,还有克雷伯菌.肺炎克雷伯菌和肺炎链球菌感染改变了呼吸道微生物群的细菌功能谱,如脂多糖生物合成的增加所示,代谢途径,和碳水化合物代谢。SBWD对肺炎克雷伯菌诱导的LRTI小鼠呼吸道菌群组成紊乱的调节有一定的趋势,并调节了部分微生物功能,包括碳水化合物代谢。
结论:SBWD可能通过呼吸道微生物群调节靶向IL-17A和GM-CSF对LRTI发挥抗感染作用。黄芩在LRTI治疗中对呼吸道微生物群的作用机制值得进一步研究。
BACKGROUND: The pathogenesis of lower respiratory tract infections (LRTIs) has been demonstrated to be strongly associated with dysbiosis of respiratory microbiota. Scutellaria baicalensis, a traditional Chinese medicine, is widely used to treat respiratory infections. However, whether the therapeutic effect of S. baicalensis on LRTIs depends upon respiratory microbiota regulation is largely unclear.
OBJECTIVE: To investigate the potential effect and mechanism of S. baicalensis on the respiratory microbiota of LRTI mice.
METHODS: A mouse model of LRTI was established using Klebsiella pneumoniae or Streptococcus pneumoniae. Antibiotic treatment was administered, and transplantation of respiratory microbiota was performed to deplete the respiratory microbiota of mice and recover the destroyed microbial community, respectively. High-performance liquid chromatography (HPLC) was used to determine and quantify the chemical components of S. baicalensis water decoction (SBWD). Pathological changes in lung tissues and the expressions of serum inflammatory cytokines, including interleukin-17A (IL-17A), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α), were determined by hematoxylin and eosin (H&E) staining and enzyme-linked immunosorbent assay (ELISA), respectively. Quantitative real-time PCR (qRT-PCR) analysis was performed to detect the mRNA expression of GM-CSF. Metagenomic sequencing was performed to evaluate the effect of SBWD on the composition and function of the respiratory microbiota in LRTI mice.
RESULTS: Seven main components, including scutellarin, baicalin, oroxylin A-7-O-β-d-glucuronide, wogonoside, baicalein, wogonin, and oroxylin A, were identified and their levels in SBWD were quantified. SBWD ameliorated pulmonary pathological injury and inflammatory responses in K. pneumoniae and S. pneumoniae-induced LRTI mice, as evidenced by the dose-dependent reductions in the levels of serum inflammatory cytokines, IL-6 and TNF-α. SBWD may exert a bidirectional regulatory effect on the host innate immune responses in LRTI mice and regulate the expressions of IL-17A and GM-CSF in a microbiota-dependent manner. K. pneumoniae infection but not S. pneumoniae infection led to dysbiosis in the respiratory microbiota, evident through disturbances in the taxonomic composition characterized by bacterial enrichment, including Proteobacteria, Enterobacteriaceae, and Klebsiella. K. pneumoniae and S. pneumoniae infection altered the bacterial functional profile of the respiratory microbiota, as indicated by increases in lipopolysaccharide biosynthesis, metabolic pathways, and carbohydrate metabolism. SBWD had a certain trend on the regulation of compositional disorders in the respiratory flora and modulated partial microbial functions embracing carbohydrate metabolism in K. pneumoniae-induced LRTI mice.
CONCLUSIONS: SBWD may exert an anti-infection effect on LRTI by targeting IL-17A and GM-CSF through respiratory microbiota regulation. The mechanism of S. baicalensis action on respiratory microbiota in LRTI treatment merits further investigation.