PM2.5 Exacerbates Oxidative Stress and Inflammatory Response through the Nrf2/NF-κB Signaling Pathway in OVA-Induced Allergic Rhinitis Mouse Model

Air pollution-related particulate matter (PM) exposure reportedly enhances allergic airway inflammation. Some studies have shown an association between PM exposure and a risk for allergic rhinitis (AR). However, the effect of PM for AR is not fully understood. An AR mouse model was developed by intranasal administration of 100 mu g/mouse PM with a less than or equal to 2.5 mu m in aerodynamic diameter (PM2.5) solution, and then by intraperitoneal injection of ovalbumin (OVA) with alum and intranasal challenging with 10 mg/mL OVA. The effects of PM2.5 on oxidative stress and inflammatory response via the Nrf2/NF-kappa B signaling pathway in mice with or without AR indicating by histological, serum, and protein analyses were examined. PM2.5 administration enhanced allergic inflammatory cell expression in the nasal mucosa through increasing the expression of inflammatory cytokine and reducing the release of Treg cytokine in OVA-induced AR mice, although PM2.5 exposure itself induced neither allergic responses nor damage to nasal and lung tissues. Notably, repeated OVA-immunization markedly impaired the nasal mucosa in the septum region. Moreover, AR with PM2.5 exposure reinforced this impairment in OVA-induced AR mice. Long-term PM2.5 exposure strengthened allergic reactions by inducing the oxidative through malondialdehyde production. The present study also provided evidence, for the first time, that activity of the Nrf2 signaling pathway is inhibited in PM2.5 exposed AR mice. Furthermore, PM2.5 exposure increased the histopathological changes of nasal and lung tissues and related the inflammatory cytokine, and clearly enhanced PM2.5 phagocytosis by alveolar macrophages via activating the NF-kappa B signaling pathway. These obtained results suggest that AR patients may experience exacerbation of allergic responses in areas with prolonged PM2.5 exposure.