The Adverse Effects PM2.5 In The Coal-burning Indoor Air On Airway Inflammation In Ovalbumin-induced Asthmatic Rats

Objective: We sought to investigate the impacts of exposure to PM2.5 in the coal-burning indoor air on airway inflammation in ovalbumin-induced asthmatic rats and its toxic mechanism.Methods: 1.PM2.5 concentration in the coal-burning indoor air was measured by a precalibrated sampler(TH150-C,Wuhan Tianhong).PM2.5 was collected by filtering membrane and putted in acid(HNO3:HCl=1:3)TFM digestion tank,and was added to 40 ml concentrated nitric acid/concentrated or microwave digestion.Graphite furnace atomic absorption spectrometry was used to detect the composition of metal elements in coal-burning PM2.5.2.The lump coal combustion PM2.5 was collected by filter membrance,after the membrances washed by ultrasonic,12 layer of gauze filtered,PM2.5 was vacuum freezed drying.OVA(15 μg/ml)and(or)PM2.5(2.5 mg/ml)was dissolved in normal saline(NS).Forty male SD rats were randomly divided into 4 groups(n=10 per group).The rats were intratracheally instilled with normal saline alone,PM2.5(2.5 mg/ml),OVA(15 μg/m L),and PM2.5+OVA(2.5 mg/ml PM2.5 and 15 μg/ml OVA),0.2ml per rat,respectively,4times at 2-week intervals.The right upper lung tissue was collected for HE staining and electron microscope section.Bronchoalveolar lavage fluid(Balf)was collected to measure the counts of the inflammatory cells.Interleukin-4(IL-4),interferon-γ(IFN-γ),transforming growth factor-β1(TGF-β1),IL-8 and granulocyte macraoprage colony stimulating factor(GM-CSF)in Balf were detected by enzyme-linked immunosorbent assay(Elisa).Immunoglobulins-E(OVA-Ig E)and OVA-Ig G1 in serum were also measured by Elisa.Real-time Polymerrase chain reaction(Rt-PCR)was used to detect the expressions of Il-4 and Ifn-γ.Results: 1.The average daily concentration of indoor coal-burning PM2.5 was 156.95μg/m3,which has the highest amount of Zinc(Zn)(34.81 μg/m3)and lowest amount of Manganese(Mn)(0.019 μg/m3).2.Behavior observation demonstrated that the symptoms of dysphoria is common,the frequencies that the rats scratched their ears and cheeks were higher,respiratory rates were quickened and deepened in the PM2.5+OVA group compared to the control.Pathological changes:the lung tissue of rat in the PM2.5+OVA group were gloomy with rough surface,those big pieces of rugged pale or semitransparent stove.The other groups have some degrees of improvement,however those of the control group were normal.The counts of the inflammatory cells,which mainly consist of lymphocyte and monocyte,were significantly increased exposed to PM2.5 plus OVA when compared to the control(P<0.05).In the PM2.5+OVA group,the histopathologic changes were severe with inflammatory cell infiltration in contrast to the control.The HE staining results shows that the numbers of lymphocytes and goblet cell exposure to PM2.5+OVA significantly increased compared with the control and PM2.5 groups(P<0.05).PM2.5+OVA caused alveolar structural damage or disappeared,infiltration of inflammatory cells,and unclear blood air barrier structure,however,no pathologic alterations were seen in the lungs of the control group.Compared to the PM2.5+OVA group,the expression of IL-4 in the control,OVA and PM2.5 groups decreased significantly(P<0.05).Compared to the PM2.5+OVA,PM2.5 and OVA groups,the expression of IFN-γ in the control was significantly increased(P<0.05).GM-CSF in the PM2.5+OVA group was higher than the other three groups(p<0.05);GM-CSF in the PM2.5 and OVA groups were higher than the control(P<0.05).Compared to the control and OVA groups,the expression of IL-8 was significantly increased in the PM2.5+OVA group(P<0.05).Compared to the control,TGF-β1 in Balf was reduced in OVA,PM2.5 and PM2.5+OVA groups(P<0.05).In contrast to the PM2.5+OVA group,OVA-Ig E decreased in the control,OVA and PM2.5 groups(P<0.05);OVA group increased compared to the control and PM2.5 groups(P<0.05).There was no significant difference in OVA-Ig G1 among the treatment groups.Conclusion: PM2.5 in the coal-burning indoor air might induce pathological structure change in lung tissue,abnormal expression of pulmonary cytokines,and increase in inflammatory cells infiltration,which further result in airway inflammatory in ovalbumininduced asthmatic rats.