Vitamin C Has Potential Effect Of Protection Against To Lung Inflammation Induced By PM2.5 Suspension

Background:PM2.5 is a kind of particle matters which threaten public health,particularly adverse to respiratory system.Lung inflammation is a typical damage suffer from PM2.5 stimulate,which is result from increase of ROS level.During inflammation process,increase of NLRP3 inflammasome and downstream product(IL-1β and IL-18)are widely focused recent years.As a complex social issue,health risk induced by PM2.5 need various protection to strengthen capability in comprehensive response.But now,still not discovered an effective intervention,which is capable to reduce lung inflammation induced by PM2.5 and have potential popularize value.Objective:The present study is base on in vivo experiment to explore whether vitamin C have potential ability to decrease risk of lung inflammation induce by PM2.5.Methods:32 male SD rats that weight from 180 g to 220 g were divided into 4 groups randomly,marked as:(1)Control group(normally feed,do not received any intervention);(2)Negative group(intake saline through tracheal instillation and gavage);(3)PM2.5 exposure group(intake PM2.5 suspension through tracheal instillation and intake saline through gavage);(4)Vitamin C intervention group(intake PM2.5 suspension through tracheal instillation and intake vitamin C through gavage).Duration of rats feeding and intervention are 21 days in total,gavage is conducted every day meanwhile tracheal instillation is conducted in day 8,10 and 12.After lung and serum sample collection,HE stain was used to proceed pathological examination for inflammation;frozen section combines with immunofluorescence technology to exam level of ROS;Western Blot and ELISA were used to test expression and concentration of proteins.Results:1.HE stain of lung tissue shown that there is significant leakage of fluid and inflammatory infiltration in PM2.5 exposure group,but other 3 groups have normal structure of lung tissue.2.Expression and concentration of TLR4 which is a receptor protein of PM2.5 stimulateExpression and concentration of TLR4 is highest in PM2.5 exposure group contrast to other 3 groups.Results of ELISA shown that concentration of TLR4 in Control,Negative,PM2.5 exposure and Vitamin C intervention group is 5.14,5.18,6.16,5.39 ng/ml,respectively.(compare with PM2.5 exposure group,P<0.05)3.Fluorescent staining shown that expression of ROS is highest in PM2.5 exposure group contrast to other groups.4.Oxidative stress enzyme and substrateMedian of MDA concentration in Control,Negative,PM2.5 exposure and Vitamin C intervention group is 4.34,4.90,8.51 and 6.42 nmol/mgprot.(compare with PM2.5 exposure group,P<0.05)SOD activity is ascending in the order of Control,Negative,PM2.5 exposure and Vitamin C intervention group,median of SOD activity is 152.09,217.44,401.96 and 584.94U/mgprot.(All 4 groups compare with each other,P<0.05).Change trend of GSH-Px activity is the same as SOD,median of GSH-Px activity is 592.86,882.04,1169.15 and 1377.88 U/mgprot in 4 groups.(All 4 groups compare with each other,P<0.05)Concentration of GSH is descending in the order of Control,Negative,PM2.5 exposure and Vitamin C intervention group,median of GSH concentration is 63.61、47.43、33.29、17.73μmol/L.Change trend of GSSG concentration is contrary to GSH,median of GSSG concentration is 23.70、53.22、80.21、106.98μmol/L in 4 groups.(All 4 groups compare with each other,P<0.05)5.Expression and concentration of NLRP3 inflammasomeExpression and concentration of NLRP3,ASC and Caspase-1 is highest in PM2.5 exposure group contrast to other 3 groups.In Control,Negative,PM2.5 exposure and Vitamin C intervention group,mean of NLRP3 concentration is 3.22,3.23,4.10 and 3.16 ng/ml,mean of ASC concentration is 96.19,96.99,112.53 and 97.17pg/ml,median of Caspase-1 concentration is 9.34,10.99,13.29 and 9.62ng/ml.(compare with PM2.5 exposure group,P<0.05)6.Concentration of inflammatory factors: IL-1β and IL-18In serum sample,concentration of IL-1β and IL-18 is highest in PM2.5 exposure group.In Control,Negative,PM2.5 exposure and Vitamin C intervention group,mean of IL-1β concentration is 4.34,4.38,7.15 and 3.26pg/ml,median of IL-18 concentration is 7.50,11.62,15.21 and 10.44pg/ml.(compare with PM2.5 exposure group,P<0.05)In Conclusion:PM2.5 is capable to induce lung inflammation,the mechanism of injury process may relate to activation of oxidative stress system and increase of ROS level.In the context of high ROS levels,expression of NLRP3 inflammasome is increase,meanwhile downstream products including IL-1β and IL-18 are increase,too.Intake vitamin C decrease oxidative stress,reduce ROS level and expression of NLRP3 inflammasome,reduce IL-1β and IL-18 concentration,alleviate pathological damage of lung inflammation,imply that vitamin C has potential effect of protection against to lung inflammation induced by PM2.5.