Scutellaria baicalensis Georgi and its active component scutellarin alleviate asthma in rats by modulating the gut microbiota-bile acid axis.

Abstract

ETHNOPHARMACOLOGICAL RELEVANCE: The Complete Works of Jingyue recorded that Scutellaria baicalensis Georgi (SBG, Huangqin) cleared heat and relieved asthma from Ming Dynasty. SBG possesses a long history of medicinal use and has demonstrated efficacy in treating respiratory diseases. Building on these traditional applications, recent studies have reported its anti-asthmatic. Yet, it's unclear whether SBG improves asthma via gut microbiota modulation or which component is key. AIM OF THE STUDY: This study established an asthma model and employed 16S rRNA sequencing and metabolomics approaches to investigate the active components and underlying mechanisms of SBG in the treatment of bronchial asthma through gut-lung axis. MATERIALS AND METHODS: An innovative combined approach was employed, utilizing Ultra-high-performance liquid chromatography/Q/Q/Q Exactive HFX mass spectrometry (UHPLC-QE-MS), 16S rRNA sequencing, metabolomics, and molecular biology to analyze the effective components of SBG, the changes in gut microbiota, and the endogenous metabolic mechanisms involved in the improvement of bronchial asthma. RESULTS: SBG and scutellarin reduced airway (Rrs) and elastic resistance (Ers) (P&#xa0;<&#xa0;0.05) in asthmatic rats, alleviated lung inflammation, and decreased serum IL-2 levels (P&#xa0;<&#xa0;0.05). They also mitigated mucosal damage and inflammatory infiltration, restoring colonic homeostasis and increasing beneficial gut bacteria. Multi-omics analysis suggested SBG acts through the bile acid pathway, modulating bile salt transformation, biosynthesis, and transport. Fecal microbiota transplantation (FMT) from treated rats to germ-free rats partially replicated the anti-asthma effects, indicating SBG and scutellarin inhibit asthma by up-regulating Bifidobacterium animalis. This bacterium produced cholic acid, especially when treated with SBG or scutellarin, showing anti-inflammatory and anti-allergic properties. CONCLUSION: SBG and its core blood-absorbed component scutellarin augment Bifidobacterium animalis, stimulate cholic acid production, modulate the bile acid pathway, and alleviate pulmonary inflammation and allergic reactions, exerting anti-asthma effects.