Abstract: Objective This study aimed to investigate the effect of ozone on the pathogenesis and inflammatory factors in a rat model of allergic rhinitis. Methods Forty-eight healthy female Sprague Dawley rats were randomly divided into six groups: normal control group(NC group), allergic rhinitis(AR)model group, normal rat ozone inhalation exposure group(NE group, 1 ppm), AR model exposed to low concentration ozone group(AREL group and 0.5 ppm), AR model exposed to moderate concentration ozone group(AREM group, 1 ppm), and AR model exposed to high ozone concentrations(AREH group, 2 ppm). AR rat models were sensitized to ovalbumin(OVA). The rats were exposed to different concentrations of ozone using the prepared ozone inhalation exposure system for 2 h per day for 6 weeks consecutively. Within 15 min of the last OVA nasal challenge, the numbers of sneezes and scratches were recorded, and the amounts of nasal secretions were measured. Nasal lavage fluid and nasal mucosa were collected 24 h after the last exposure. Western blotting was performed to detect the protein expression of nuclear factor-kappa B(NF-κB)p65. Quantitative real-time PCR was used to detect the mRNA expression of the NF-κB target genes for tumor necrosis factor-alpha(TNF-α), interleukin(IL)-6, and IL-8 in the nasal mucosa. OVA-specific IgE levels and protein levels of the pro-inflammatory factors IL-6, IL-8, and TNF-α in nasal lavage fluid were determined by ELISA. Pathological changes in the nasal mucosa were assessed by hematoxylin and eosin staining. Statistical analyses and graphical representations were performed using SPSS 20.0. Results The frequency of sneezing, nasal scratching, and nasal secretion in rats with AR was higher in the ozone exposure group than in the AR and NC groups(P<0.05). The serum OVA slgE levels in the ARE group were higher than those in the AR and NC groups(P<0.05); the increase was most obvious in the AREH group. Nuclear protein expression of NF-κB p65 in the AREM and AREH groups was higher than that in the AR and NC groups(P<0.05). The mRNA expressions of IL-6, IL-8, and TNF-α in nasal mucosa and the protein content of IL-6, IL-8, and TNF-α in nasal lavage fluid were increased in the AR ozone exposure group. The nasal lavage fluid levels of IL-6, IL-8, and TNF-α were higher in the AREL group than in the NC group, and those in the medium- and high-concentration exposure groups were higher than those in the AR and NC groups(P<0.05). Conclusion Ozone inhalation can increase the serum OVA slgE of AR; promote the release of inflammatory factors TNF-α, IL-6, and IL-8; and lead to the aggravation of AR symptoms. This pathological process may be related to the transfer of NF-κB into the nucleus and expression of its target genes in nasal mucosa activated by ozone in AR rats.

Key words: Rhinitis, Allergic, Ozone, Inflammatory factors, NF-κB