# Polydatin alleviates mitochondrial damage and apoptosis of lung epithelial cells by inhibiting toll‐like receptor 4‐dependent macrophage activation in asthma

## TL;DR

Polydatin may help treat asthma by reducing inflammation and cell damage through a specific immune signaling pathway.

## Contribution

Polydatin's novel mechanism of blocking TLR4/P2X7R synergy in macrophages to reduce asthma-related inflammation is identified.

## Key findings

- Polydatin reduced IL-1β and IL-18 levels in macrophages and epithelial cells.
- Blocking TLR4/P2X7R signaling reduced mitochondrial damage and apoptosis in lung cells.
- Polydatin alleviated airway inflammation and oxidative stress in an asthma mouse model.

## Abstract

This study investigated the role of polydatin in regulating macrophage–epithelial cell (EC) interactions during asthma. An asthma model was induced in BALB/c mice using ovalbumin (20 μg).

The therapeutic effects of polydatin (20 and 40 mg/kg) were evaluated in this asthmatic mouse model. To assess the underlying mechanisms, Bronchial Epithelium Adenovirus 12‐SV40 2B (BEAS‐2B) cells were cocultured with Tohoku Hospital for Pediatrics‐1 (THP‐1) macrophages, in which toll‐like receptor 4 (TLR4) was either overexpressed or knocked down, and subsequently stimulated with lipopolysaccharide (LPS) and ATP. THP‐1 cells underwent a 1‐h pretreatment with polydatin (50 and 100 μmol/L), Class Lipid Inhibitor‐095 (CLI‐095, TLR4 inhibitor, 1 μg/mL), or A438079 (P2X7R antagonist, 10 μmol/L) prior to LPS/ATP challenge.

Findings from Western blotting, enzyme‐linked immunosorbent assay, flow cytometry, real‐time polymerase chain reaction, and immunofluorescence assays demonstrated that modulating TLR4 expression significantly altered interleukin‐1β (IL‐1β) secretion from THP‐1 macrophages and mitochondrial reactive oxygen species (mtROS) production in BEAS‐2B ECs. In the mouse asthma model, polydatin significantly alleviated airway inflammation, oxidative stress, and apoptosis, likely by interfering with TLR4/P2X7R‐mediated signaling and suppressing the activation of the NOD‐like receptor protein inflammasome. Additionally, polydatin significantly reduced IL‐1β and IL‐18 levels and inhibited the infiltration of macrophages and eosinophils. Correspondingly, polydatin significantly attenuated TLR4/P2X7R signaling in THP‐1 cells stimulated with ATP and LPS, thereby reducing IL‐1β and IL‐18 secretion, calcium influx, mtROS production, and apoptosis in BEAS‐2B ECs.

Polydatin is a promising therapeutic candidate for asthma, possibly by targeting macrophage–epithelium cross‐talk via the TLR4/P2X7R axis. Future formulations as capsules or sprays may effectively alleviate airway inflammation and remodeling.

The alleviation of asthma by polydatin is dependent on the blockage of the toll‐like receptor 4 (TLR4)/P2X7R synergy in macrophages. The blockage of the TLR4/P2X7R synergy results in decreased release and secretion of interleukin‐1β (IL‐1β) and IL‐18. In epithelial cells, low IL‐1β and IL‐18 levels inhibit mitochondrial damage and apoptosis.