Increased CCL24/eotaxin-2 with postnatal ozone exposure in allergen-sensitized infant monkeys is not associated with recruitment of eosinophils to airway mucosa

Ozone inhalation induces exacerbation of eosinophilic airway inflammation and Th2-skew immune response in a rat model of AR

BACKGROUND

Ozone (O3) exposure elicits allergic rhinitis (AR) exacerbations by mechanisms that remain poorly understood. We used a rat model to investigate the effects of O3 on eosinophilic airway inflammation and Th2-related response.

METHODS

Sprague-Dawley (SD) rats were sensitized and challenged with ovalbumin (OVA) to make AR models. Three groups of AR rats were exposed respectively to 0.5, 1.0, 2.0 ppm of O3 for 2 h daily over 6 weeks consecutively and studied 24 h later. Normal rats exposed to O3 alone were used as controls. Nasal symptoms and OVA-specific immunoglobulin E (OVA-sIg E) in the serum were evaluated. Inflammatory cells in nasal lavage fluid (NLF) were classified and counted. Cytokines protein levels in NLF were assessed by ELISA. The pathological changes in the nasal mucosa were examined by histology.

RESULTS

The combination of allergen and repeated O3 exposure in rats induced a significant increase of the number of sneezes, nasal rubs, amount of nasal secretion and OVA-sIgE in the serum, accompanied by enhancement of eosinophils in NLF and nasal mucosa. The increase of interleukin-5 (IL-5), IL-13, Eotaxin and decrease of INF-γ protein levels in NLF were detected in AR rats after O3 inhalation. Hematoxylin and eosin staining showed disordered arrangement of the nasal mucosa epithelium and eosinophilic infiltration in a concentration-dependent manner.

CONCLUSIONS

O3 inhalation deteriorated symptoms in AR rats, and the possible mechanism is that ozone co-exposure could enhance the expression of Th2 cytokines, eosinophilic airway inflammation dose-dependently. The observation is helpful for us to understand the synergistic effect of O3 in the air pollution and allergen on aggravating allergic rhinitis.

Ozone-induced enhancement of airway hyperreactivity in rhesus macaques: Effects of antioxidant treatment

BACKGROUND

Ozone (O3) inhalation elicits airway inflammation and impairs treatment responsiveness in asthmatic patients. The underlying immune mechanisms have been difficult to study because of the lack of relevant experimental models. Rhesus macaques spontaneously have asthma and have a similar immune system to human subjects.

OBJECTIVES

We sought to investigate mucosal immune changes after O3 inhalation in a clinically relevant nonhuman primate asthma model and to study the effects of an antioxidant synthetic lignan (synthetic secoisolariciresinol diglucoside [LGM2605]).

METHODS

A cohort of macaques (n = 17) previously characterized with airway hyperreactivity (AHR) to methacholine was assessed (day 1). Macaques were treated (orally) with LGM2605 (25 mg/kg) or placebo twice per day for 7 days, exposed to 0.3 ppm O3 or air for 6 hours (on day 7), and studied 12 hours later (day 8). Lung function, blood and bronchoalveolar lavage (BAL) fluid immune cell profile, and bronchial brushing and blood cell mRNA expression were assessed.

RESULTS

O3 induced significant BAL fluid neutrophilia and eosinophilia and increased AHR and expression of IL6 and IL25 mRNA in the airway epithelium together with increased BAL fluid group 2 innate lymphoid cell (ILC2s), CD1c+ myeloid dendritic cell, and CD4+ T-cell counts and diminished surfactant protein D expression. Although LGM2605 attenuated some of the immune and inflammatory changes, it completely abolished O3-induced AHR.

CONCLUSION

ILC2s, CD1c+ myeloid dendritic cells, and CD4+ T cells are selectively involved in O3-induced asthma exacerbation. The inflammatory changes were partially prevented by antioxidant pretreatment with LGM2605, which had an unexpectedly disproportionate protective effect on AHR.

From the Field to the Laboratory: Air Pollutant-Induced Genomic Effects in Lung Cells

Current in vitro studies do not typically assess cellular impacts in relation to real-world atmospheric mixtures of gases. In this study, we set out to examine the feasibility of measuring biological responses at the level of gene expression in human lung cells upon direct exposures to air in the field. This study describes the successful deployment of lung cells in the heavily industrialized Houston Ship Channel. By examining messenger RNA (mRNA) levels from exposed lung cells, we identified changes in genes that play a role as inflammatory responders in the cell. The results show anticipated responses from negative and positive controls, confirming the integrity of the experimental protocol and the successful deployment of the in vitro instrument. Furthermore, exposures to ambient conditions displayed robust changes in gene expression. These results demonstrate a methodology that can produce gas-phase toxicity data in the field.