Ameliorative effects of total glycosides from Aralia elata on airway inflammation and mucus hypersecretion in asthmatic mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Asthma, a chronic inflammatory respiratory disease, is a growing public health concern. Aralia elata (Miq.) Seem, a medicinal plant widely used in East Asia, has traditional applications in Chinese regions (e.g., Heilongjiang, Yunnan) for treating asthma, cough, and phlegm, particularly among the Lisu and Korean ethnic groups. However, the specific bioactive compounds and underlying mechanisms responsible for its anti-asthmatic properties remain unclear. This study investigates the therapeutic potential and mechanism of total glycosides from Aralia elata (GA) in asthma alleviation, addressing this critical knowledge gap.

AIM OF THE STUDY: This study aims to investigate the therapeutic effects and mechanisms of GA on airway inflammation and mucus hypersecretion in asthmatic mice.

MATERIALS AND METHODS: The primary components of GA were characterized by UPLC-Q-TOF/MS, and network pharmacology was employed to predict its potential components and anti-asthma targets. Transcriptomics was used to identify potential pathways involved in GA treatment of asthma in mice. An asthmatic mouse model was induced by sensitization and challenge with ovalbumin (OVA) and Al(OH)3. Mice were randomized into control (NC), model (MOD), dexamethasone (DEX), and GA high- and low-dose (GA-H, GA-L) groups. Additionally, an in vitro mucus hypersecretion model was established by co-stimulating 16HBE with lipopolysaccharide (LPS, 10 μg/mL) and interleukin-13 (IL-13, 50 ng/mL). Cytokine levels in serum and bronchoalveolar lavage fluid (BALF), as well as IL-6, IL-8, and Mucin 5AC (MUC5AC) expression in cells, were measured using ELISA. Group 2 innate lymphoid cells (ILC2s) were quantified by flow cytometry. Proteins and genes expression were analyzed by immunohistochemistry, immunofluorescence, Western blot, and RT-qPCR. Finally, molecular docking simulations were conducted to validate potential targets of GA in asthma treatment.

RESULTS: A total of 59 active ingredients were identified in GA. Among these, GA34, GA59, GA52, GA12, GA13, GA29, GA38, GA43, GA6, and GA41 have been identified as core components in the management of asthma. The core therapeutic targets for the treatment of asthma are STAT3, IL-6, TNF, IRAK1, NF-κB1, TLR4, RELA, IL-13, HSP90AA1, MyD88, TLR2, IL-13Rα1, PTGS2, IL-33 and ST2. In OVA-induced asthmatic mice, GA treatment significantly prolonged asthma latency, improved airway hyperresponsiveness, reduced inflammatory infiltration in lung tissue, and lowered serum IgE and OVA-IgE levels. A total of 1358 differentially expressed genes (DEGs) between NC vs MOD and MOD vs GA were screened by transcriptome sequencing in the lung tissues of each group of mice. KEGG enrichment analysis revealed that significantly altered genes were enriched in the asthma disease and NF-κB signaling pathways. GA reduced BALF levels of T helper 2 cell (Th2)/Th17 cytokines (IL-4, IL-5, IL-6, IL-9, IL-13, IL-17A), ILC2-activating factors (IL-25, IL-33, TSLP), chemokines (IL-8, Eotaxin, MCP-1), leukotrienes (LTB4, LTC4), and sST2, while increasing IL-10 and IFN-γ. It also decreased ILC2 counts and downregulated IL-33, ST2, IRAK1, and MyD88 protein expression in lungs. Furthermore, GA significantly ameliorated goblet cells hyperplasia and mucus hypersecretion in lung tissues of asthmatic mice and reduced the levels of MUC5AC in BALF and lung tissues. GA treatment downregulated the expression of p-STAT6 in lung tissues. GA decreased the secretion of IL-6, IL-8, and MUC5AC, decreased the protein expression of p-STAT6 in LPS + IL-13 induced 16HBE cells. Molecular docking showed strong binding of core component GA52 to ST2 and IL-13Rα1, with binding energies of -10.5 and -10.6 kcal mol-1, respectively.

CONCLUSION: GA ameliorates airway inflammation in asthmatic mice by restoring Th2/Th1, Th17/Treg balance and inhibiting ILC2s-mediated NF-κB pathway. Furthermore, GA mitigates airway mucus hypersecretion by inhibiting the expression of MUC5AC through IL-13-mediated STAT6 pathway in asthmatic mice and IL-13+LPS- stimulated 16HBE cells.