# Total alkaloids of Leonurus alleviate allergic asthma and inflammation responses by inhibiting hypoxia-induced factor-1⍺-mediated mast cell activation

## TL;DR

This study shows that Leonurus alkaloids reduce allergic asthma symptoms by inhibiting HIF-1α, which reduces mast cell activation and inflammation.

## Contribution

The study identifies HIF-1α as a key target of Leonurus alkaloids in alleviating allergic asthma.

## Key findings

- TAL reduced airway hyperresponsiveness and lung inflammation in an OVA-induced asthma model.
- TAL suppressed HIF-1α expression and mast cell degranulation in both in vivo and in vitro models.
- HIF-1α overexpression weakened TAL's anti-asthmatic effects, confirming its role in the mechanism.

## Abstract

Leonurus japonicus Houtt. has been traditionally used as a gynecological remedy and is now recognized for its anti-inflammatory and immunomodulatory properties. But its potential therapeutic role in allergic asthma is unclear. This study aimed to investigate the anti-asthmatic effects of the total alkaloids of Leonurus (TAL) and their regulation of mast cell activation through the hypoxia-inducible factor-1α (HIF-1α) pathway.

An ovalbumin (OVA)-induced asthma mouse model was used to detect TAL’s effects on airway hyperresponsiveness, lung inflammation, and Th2 cytokines. For in vitro studies, RBL-2H3 cells were employed as a mast cell model. Transcriptomics and cross-species analysis integrated rat signatures with human asthma datasets using KEGG enrichment to identify conserved HIF-1α–related pathways. HIF-1α expression and localization were analyzed by Western blotting and immunofluorescence. Mast cell degranulation was evaluated via β-hexosaminidase (β-hex) assay and Th2 cytokines detection. Constructed a HIF-1α stable overexpression cell or applied pharmacological inhibition (YC-1) to verify the key role of HIF-1⍺ on TAL’s efficacy.

TAL significantly alleviated allergic symptoms, reduced airway hyperresponsiveness, and decreased lung mast cell infiltration. Transcriptomic analysis revealed that hypoxia-related pathways, particularly HIF-1α, were downregulated following TAL intervention. TAL suppressed HIF-1α protein expression, reduced mast cell degranulation, and Th2 cytokines both in vivo and in vitro. Mechanistically, hypoxia induced HIF-1α upregulation, mast cell activation, and cytokine release, whereas TAL inhibited these responses. This effect was weakened by HIF-1α overexpression but potentiated by YC-1.

TAL alleviates allergic asthma by suppressing HIF-1α-mediated mast cell activation and associated inflammation responses, supporting its potential application in inflammatory airway diseases.