<i>Petasites japonicus</i>‑propolis mixture attenuates airway inflammation in a mouse model of PM₁₀ and ovalbumin‑induced respiratory disease

Airway inflammation driven by particulate matter (PM) exposure underlies diseases such as asthma and allergic rhinitis. Although conventional anti-inflammatory therapies exist, they often cause significant side effects. Natural plant extracts offer non-toxic alternatives with comparable efficacy. The present study evaluated the effects of <i>Petasites japonicus</i>-propolis (PJP) mixture in a mouse model co-exposed to PM (intranasal) and ovalbumin (OVA; intraperitoneal) over 30 days. PJP was administered orally at 50, 100 or 200 mg/kg daily for 9 days. PJP reduced sneezing and nasal rubbing. Serum levels of total IgE and OVA-specific IgG₁ were decreased by PJP. In addition, bronchoalveolar lavage fluid and nasal lavage fluid showed lower histamine and IL-4 concentrations. In lung tissue, PJP reduced the epithelial thickness and inflammatory cell infiltration (goblet cells, eosinophils and mast cells). At the molecular level, PJP downregulated suppression of tumorigenicity 2, IL-33, TNF-α and IL-4 expression, and inhibited NF-κB phosphorylation. PJP attenuated PM/OVA-induced airway inflammation by suppressing NF-κB signaling and associated cytokine responses, highlighting its potential as a therapeutic candidate for inflammatory respiratory diseases.