Wendan Decoction-Derived TMF Alleviates Endolymphatic Hydrops by Modulating the DUSP3/p38 MAPK/AQP2 Axis.
TMF from Wendan Decoction shows potential in reducing endolymphatic hydrops in a guinea pig model, but further research is needed to confirm its relevance in humans.
Where it sits
this study against the rest of the desmopressin corpusSummary and findings
This study measured the effects of 5,6,7,4'-tetramethoxyflavone (TMF) derived from Wendan Decoction on endolymphatic hydrops (EH) in a guinea pig model. TMF was found to reduce cochlear hydrops and inflammatory cytokine levels. The study aimed to elucidate the molecular mechanisms involved, particularly the role of DUSP3 and p38 MAPK.
Abstract
<h4>Ethnopharmacological relevance</h4>Wendan Decoction is a classical traditional Chinese medicine formula historically used for phlegm-related dizziness and vertigo. Recent studies have shown that Wendan Decoction can ameliorate experimental endolymphatic hydrops (EH), a characteristic pathological correlate of Ménière's disease. However, the bioactive constituents responsible for these effects and their molecular targets remain incompletely defined.<h4>Aim of the study</h4>This study aimed to identify and quantify a pharmacologically relevant constituent of Wendan Decoction and to investigate its molecular target and mechanism of action in experimental EH.<h4>Materials and methods</h4>Candidate constituents and regulatory targets were prioritized through ADME-guided screening, target prediction, MD-associated transcriptomic analysis, protein-protein interaction network analysis, pathway enrichment, MAPK pathway mapping, and molecular docking. Targeted UPLC-ESI-MS/MS was used to verify and quantify 5,6,7,4'-tetramethoxyflavone (TMF) in Wendan Decoction granules. The interaction between TMF and DUSP3 was examined using surface plasmon resonance (SPR) and a cell lysate-based cellular thermal shift assay (CETSA). The effects of TMF were evaluated in LPS-stimulated HEI-OC1 cells and a DDAVP-induced guinea pig model of EH. DUSP3 knockdown and pharmacological inhibition of p38 MAPK with SB203580 were used to investigate the functional relationships among DUSP3, p38 MAPK, AQP2, and ZO-1.<h4>Results</h4>TMF was detected in Wendan Decoction granules at 0.0379% (w/w). SPR showed micromolar binding between TMF and recombinant DUSP3, while CETSA showed that TMF increased the thermal stability of DUSP3. In LPS-stimulated HEI-OC1 cells, TMF reduced inflammatory mediator production, increased DUSP3 and ZO-1 expression, inhibited p38 MAPK activation, and decreased AQP2 expression. SB203580 attenuated AQP2 upregulation, ZO-1 reduction, and pro-inflammatory cytokine production, including after DUSP3 silencing, supporting p38 MAPK as a downstream component of DUSP3-associated signaling. In DDAVP-treated guinea pigs, TMF reduced morphometrically quantified cochlear hydrops, alleviated cochlear ultrastructural injury and vestibular-associated behavioral impairment, and decreased cochlear inflammatory cytokine levels. Cochlear DUSP3 knockdown was confirmed at both the mRNA and protein levels and partially weakened TMF-mediated regulation of the p38 MAPK/AQP2 axis.<h4>Conclusions</h4>TMF is a quantified Wendan Decoction-derived constituent with protective activity against experimental EH. The findings support a direct interaction between TMF and DUSP3 and suggest that TMF alleviates EH-associated pathological changes, at least in part, through DUSP3-associated regulation of p38 MAPK activation and downstream AQP2 and ZO-1 expression.
Background
This paper addresses the potential effects of Wendan Decoction, a traditional Chinese medicine, on endolymphatic hydrops (EH), which is associated with Ménière's disease. Prior research indicated that Wendan Decoction could ameliorate EH, but the specific bioactive components and their mechanisms were not fully understood. This study aims to clarify the role of TMF, a constituent of Wendan Decoction, in modulating EH.
Methods
The study employed various methodologies including ADME-guided screening, molecular docking, and targeted UPLC-ESI-MS/MS to quantify TMF. The effects of TMF were evaluated in LPS-stimulated HEI-OC1 cells and in a DDAVP-induced guinea pig model of EH. Key outcomes included the expression levels of DUSP3, AQP2, and ZO-1, as well as morphometric assessments of cochlear hydrops.
Results
TMF was quantified at 0.0379% (w/w) in Wendan Decoction. In LPS-stimulated HEI-OC1 cells, TMF reduced inflammatory mediator production and decreased AQP2 expression. In the guinea pig model, TMF reduced cochlear hydrops and inflammatory cytokine levels. DUSP3 knockdown was confirmed at both the mRNA and protein levels.
Interpretation
The findings suggest that TMF may interact with DUSP3 and modulate the p38 MAPK pathway, impacting AQP2 and ZO-1 expression. While the results are statistically significant, the clinical relevance remains uncertain due to the animal model used and the need for human studies. The study's limitations include the absence of direct human data and reliance on surrogate endpoints.
Key findings
- TMF was detected in Wendan Decoction granules at 0.0379% (w/w).
- In LPS-stimulated HEI-OC1 cells, TMF reduced inflammatory mediator production and decreased AQP2 expression.
- TMF increased DUSP3 and ZO-1 expression and inhibited p38 MAPK activation.
- In DDAVP-treated guinea pigs, TMF reduced cochlear hydrops and decreased cochlear inflammatory cytokine levels.
- Cochlear DUSP3 knockdown was confirmed at both the mRNA and protein levels.
Limitations
- Results based on a guinea pig model, not human data.
- Small sample size in animal studies.
- Short duration of follow-up in animal model.
- In vitro findings may not fully translate to in vivo effects.
- No long-term efficacy data reported.