Inhibiting the Nrf2/HO-1 signaling cascade weakens the pro-inflammatory response induced by gasoline engine exhaust in lung epithelial cells following air-liquid interface exposure

  • Inhal Toxicol. 2026 May;38(5):237-251. doi: 10.1080/08958378.2026.2659193.
Ying Qu  1 ,  Guoliang Li  1 ,  Tao Yu  1 ,  Xueyan Zhang  1 ,  Wei Zhao  1 ,  Min Zheng  1 ,  Bin Li  1  2 ,  Ping Bin  1  2
Affiliations
  • 1. National Institute for Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing, China.
  • 2. State Key Laboratory of Trauma and Chemical Poisoning, National Institute for Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing, China.
PMID: 42011764 DOI: 10.1080/08958378.2026.2659193
Abstract

Objective: This study aimed to investigate the role of the nuclear factor erythroid 2-related factor 2/heme oxygenase-1 (Nrf2/HO-1) signaling cascade in the inflammatory responses induced by whole gasoline engine exhaust (GEE) in lung epithelial cells via air-liquid interface (ALI) exposure.

Materials and methods: Using an ALI exposure system, human bronchial epithelial cells (BEAS-2B) and type II alveolar epithelial cells (A549) were exposed to whole GEE collected from a two-wheeled motorcycle at various dilution ratios. After a 1 h exposure at 10 mL/min, cell relative viability, intracellular Reactive Oxygen Species (ROS), glutathione (GSH), oxidized glutathione (GSSG) and the GSH/GSSG ratio were measured. Inflammatory cytokines (IL-1β, IL-6, and IL-8) were quantified. The Nrf2 inhibitor brusatol (BR, 300 nM) and the antioxidant N-acetyl-L-cysteine (NAC, 5 mM) were used to modulate the Nrf2/HO-1 pathway and oxidative stress, respectively. Protein and gene expression levels were analyzed by Western Blotting and Real-Time PCR.

Results: Exposure to 10%GEE induced oxidative stress and optimally activated Nrf2/HO-1 expression without cytotoxicity, while higher concentrations suppressed this signaling pathway. Significant correlations were observed between Nrf2/HO-1 levels and inflammatory cytokines. Inhibition of Nrf2/HO-1 with BR reduced inflammatory responses which induced by the 10%GEE in both BEAS-2B and A549 cell lines. Furthermore, attenuating oxidative stress with NAC inhibited both Nrf2/HO-1 expression and the GEE-induced inflammatory response.

Conclusion: Inhibiting the Nrf2/HO-1 signaling cascade attenuates the pro-inflammatory response induced by GEE in lung epithelial cells following ALI exposure. The Nrf2/HO-1 pathway appears to be a critical regulator of GEE-induced pulmonary inflammation, highlighting its potential as a therapeutic target.

Keywords
Gasoline engine exhaust; Nrf2/HO-1 signaling; air-liquid interface; inflammatory response; lung epithelial cells; oxidative stress.
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