Effet of Combined Nitrogen Dioxide and Carbon Nanoparticle Exposure on Lung Function During Ovalbumin Sensitization in Brown Norway Rat

Abstract

The interaction of particulate and gaseous pollutants in their effects on the severity of allergic inflammation and airway responsiveness are not well understood. We assessed the effect of exposure to NO2 in the presence or absence of repetitive treatment with carbon nanoparticle (CNP) during allergen sensitization and challenges in Borwn-Norway (BN) rat, in order to assess their interactions on lung function and airway responses (AR) to allergen and methacholine (MCH), end-expiratory lung volume (EELV), bronchoalveolar lavage fluid (BALF) cellular content, serum and BALF cytokine levels and histological changes. Animals were divided into the following groups (n = 6): Control; CNP (Degussa-FW2): 13 nm, 0.5 mg/kg instilled intratracheally ×3 at 7-day intervals; OVA: ovalbumin-sensitised; OVA+CNP: both sensitized and exposed to CNP. Rats were divided into equal groups exposed either to air or to NO2, 10 ppm, 6 h/d, 5d/wk for 4 weeks. Exposure to NO2, significantly enhanced lung inflammation and airway reactivity, with a significantly larger effect in animals sensitized to allergen, which was related to a higher expression of TH1 and TH2-type cytokines. Conversely, exposure to NO2 in animals undergoing repeated tracheal instillation of CNP alone, increased BALF neutrophilia and enhanced the expression of TH1 cytokines: TNF-α and IFN-γ, but did not show an additive effect on airway reactivity in comparison to NO2 alone. The exposure to NO2 combined with CNP treatment and allergen sensitization however, unexpectedly resulted in a significant decrease in both airway reactivity to allergen and to methacholine, and a reduction in TH2-type cytokines compared to allergen sensitization alone. EELV was significantly reduced with sensitization, CNP treatment or both. These data suggest an immunomodulatory effect of repeated tracheal instillation of CNP on the proinflammatory effects of NO2 exposure in sensitized BN rat. Furthermore, our findings suggest that NO2, CNP and OVA sensitization may significantly slow overall lung growth in parenchymally mature animals.

Blockade of the cholinergic system during sensitization enhances lung responsiveness to allergen in rats

“…However, despite these cellular changes, there was no evidence of altered lung responsiveness to MCh. Following sensitization with aerosolized OVA, the coexistence of bronchial inflammation and the lack of BHR to non‐specific constrictor challenge are controversial, but our findings are in accordance with results indicating dissociated inflammatory and mechanical responses …”

Nickel oxide nanoparticles can recruit eosinophils in the lungs of rats by the direct release of intracellular eotaxin

“…As a positive control for IgE-mediated allergic inflammation, the OVA-induced allergic airway inflammation model was established according to the previously described method, with slight modification [ 35 ]. Briefly, 6-week old female Wistar rats were sensitized on days 0, 7, and 14 with an intraperitoneal injection of 1 mg OVA (Grade V, Sigma-Aldrich, St Louis, MO, USA) and 100 mg aluminum hydroxide (Sigma-Aldrich) in 1 mL sterile saline.…”

A rapid assessment of the impact of hazard reduction burning around Sydney, May 2016

“…Recent in vitro findings suggested that levels of SO 2 and NO 2 below current EU health based exposure standards can exacerbate pollen allergy on susceptible subjects (Sousa et al, 2012). Moreover, exposure to NO 2 significantly enhanced lung inflammation and airway reactivity in animals that were treated with ovalbumin (Layachi et al, 2012). So, there are mixed results in human clinical studies in which NO 2 exposure preceded allergen exposure.…”