Objective To observe the effects of different concentrations of atmospheric PM2.5 on asthmatic rats, and the changes of miR155, STAT6, and IL-13 associated with asthma exacerbation.
Methods A total of 50 SD rats were randomly assigned into five groups, including normal saline control group, asthma group, asthma+PM2.5 low dose group, asthma+PM2.5 medium dose group, and asthma+ PM2.5 high dose group. The control group and asthma group were treated with normal saline (1.5 mg/kg body weight), and the asthma+ PM2.5 exposure groups were treated with mixture of PM2.5 and normal saline (1.5, 6.0, and 24.0 mg/kg). An asthma rat model was reproduced by sensitization with intraperitoneal in jection and inhalation of ovalbumin (OVA). On day 25, 28, 31 and 34, the rats were administrated with PM2.5 by intratracheal in stillation, and sacrificed on day 36. We observed pathological changes of rat lung tissue samples by HE staining. Total and differential cell counts in bronchoalveolar lavage fluid (BALF) were compared across groups. Expression levels of miR155, STAT6, and IL-13 in rat lung tissue samples were analyzed by RT-PCR. Level of IL-13 in BALF was detected by ELISA.
Results The percentage of eosinophilic in the asthma group was higher than that in the control group, and the percentages in the asthma+PM2.5 medium and high dose group were higher than the control, asthma group, the differences were statistically significant (P < 0.05). The expression of miR155 and STAT6 in the asthma+PM2.5 medium and high dose groups were higher than that in the control group (P < 0.05). There was a positive correlation between the expressions of miR155 and STAT6 genes (r=0.843, P < 0.001). The gene expressions of IL-13 in rat lung tissue and the protein expression level of IL-13 in BALF were not different (P > 0.05).
Conclusion miR155 and STAT6 may play a role in the exacerbation of asthma induced by atmospheric PM2.5, and miR155 and STAT6 may be related.
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