Effects of particulate matter (PM 2.5) exposure on airway inflammation in asthmatic mice and intervention effect of Honokiol / 中华实用儿科临床杂志

ABSTRACT

Objective To explore the effect of particulate matter (PM 2.5) on airway inflammation in asthmatic mice and the intervention effect of Honokiol.Methods Fifty female BALB/c mice were divided into 5 groups according random number table,group Anormal control group;group Basthma model group;group CPM 2.5 low dose exposure asthma group;group DPM 2.5 high dose exposure asthma groupgroup EHonokiol group.Asthmatic mouse models were established by ovalbumin(OVA) sensitization and challenge.On day 0 and 7,B-E groups were intraperitoneally with injection 100 mg/L OVA and Al (OH)3 for sensitization;on day 14 to 21,10 g/L OVA solution was given 30 min per day to challenge.During challenge phrase,C-D groups were received different doze intratracheal injection of PM 2.5 respectively,every 7 days,total 4 times.On this basis,the mice in group E received Honokiol intragastfic administration.The mice in group A were carried out by using saline instead of OVA.Mice were sacrificed 24 h after the final inhalation challenge,and for the recovered bronchoalveolarlavage fluid(BALF) of the left lung was used for differential inflammatory cell counts,HE staining and pathological examination were performed on the right lung.The expression of Toll-like receptor 4 (TLR4) and nuclear factor (NF)-κB at mRNA level were detected by real-time flurescence quantitative polymerase chain reaction (qPCR).Flow cytometry analysis was performed to measure the levels of Th17 and Treg cells.Results Compared with group A,mice in group B,group C and group D expressed more serious disorsers of bronchial epithelial cells,alveolar wall congestion and edema,increased mucus secretion in the airway and infiltration of inflammatory cells in lung,and those in group D was more obvious than those in group C and group E,significantly reduced respiratory inflammation compared with group E[(8.56 ± 3.28) × 108/L,0.041 5 ± 0.013 5],the total number of inflammatory cell counts in group C and group D were (20.28 ± 11.16) × 108/L and (27.38 ± 14.64) × 108/L,eosinophils proportion were 0.177 8 ±0.064 9 and 0.229 1 ±0.098 7,there were statistically significant differences(all P ＜ 0.05);compared with group E (1.60 ± 0.28,1.54 ± 0.25),the expression of TLR4 mRNA and NF-κB mRNA in group C and group D (2.56 ± 0.49,3.21 ± 0.61;2.42 ± 0.30,2.83 ± 0.32) were significantly higher,and there were statistically significant differences(all P ＜0.05),group D was more higher than those in group C (all P ＜ 0.05);compared with group E(0.018 3 ± 0.002 3),the expression of Th17 in group C and group D (0.043 9 ±0.008 9 and 0.052 2 ±0.011 8) were significantly higher,and there were statistically significant differences(all P ＜0.05);compared with group E(0.064 5 ±0.003 8),the expression of Treg in group C and group D (0.038 2 ± 0.004 2) and (0.022 7 ± 0.003 3) were significantly lower,and there were statistically significant differences(all P ＜ 0.05);and those of group E were improved remarkably.Conclusion PM 2.5 exposure can aggravate airway inflammation in asthmatic mice,and the damage to airway is more obvious when exposed to high dose of PM 2.5,Honokiol can relieve PM 2.5 exposure of asthmatic airway inflammation through down regulation the expression of TLR4 and NF-κB and Th17 and regulating the balance of Th17 and Treg cells.