The Significance Of Neutrophilic Inflammation And Its Tissue Differences In COPD Rats

Objective: In recent years,the air quality of indoor environment has received wide attention.Cigarette smoke,as the main pollutant in indoor environment,is a serious threat to human health.Currently,the international methods of toxicology evaluation for cigarette smoke are generally in vitro which was recommended by CORESTA,but these methods can only preliminarily evaluate the relative toxicity of smoke.The methods which are in vivo due to can simulate the various effects of smoke in the body,have been considered to be the more effective methods of toxicology evaluation.Based on this condition,foreign researchers have specially propose that we can use "the specific disease test",that is,Chronic obstructive pulmonary disease(COPD)animal model for toxicology evaluation of cigarette smoke in vivo.COPD is a chronic respiratory disease.Airway inflammation is a typical pathological characteristic of COPD.And the neutrophil,as one of the main inflammatory cell types,its chemotaxis and activation processes is closely related to the COPD's progression.The occurrence and development processes of the neutrophilic inflammation can reflect the COPD's progression to a certain extent.Smoking is the leading risk factor for COPD.Our early studies have successfully established the rat COPD model whichinduced by cigarette smoke,and the oxidative/antioxidant imbalance,protease/resistant protease imbalances,inflammatory lesions were preliminarily researched.But the mechanism which COPD's neutrophilic inflammation induced by cigarette smoke has not been fully elucidated.In order to establish the integrate cigarette smoke toxicology evaluation method in vivo,this study uses the neutrophilic inflammation as the breakthrough point,detected the neutrophilic chemotactic factors,effect proteins and regulatory protein in health and COPD rats induced by 3types cigarette smoke,and analyzed the tissue lesion which damaged by different components of cigarette smoke.The study is significant for clarifying the toxicological effects and health hazards of the complex environmental air pollution,and looking for the biomarkers of toxicological evaluation.Methods: 48 male SD rats of clean grade were randomly divided into control group(CK)and experimental group(Y-1,Y-2 and Y-3).The rats of three experimental groups were exposed to three types of tobacco smoke respectively,to establish the COPD model.After 30 d and 60 d,BALF was obtained from every four groups,and the inflammation cells were differential counted.The lungs were obtained for H.E.staining to score for inflammation.The levels of LTB4 in serum and MIP-2 in lung were determined by ELISA method.The activities of MPO in lung were determined by biochemistry.And the expression of NE,p38 and thephosphorylation of p38 in lung,liver,spleen,kidney and heart was determined by immunohistochemistry.Results: 1.After 60 days of exposure to cigarette smoke,there were plenty of inflammatory cells aggregated in the airway and pulmonary vessels in the Y-1,Y-2 and Y-3 groups.The numbers of leukocytes in BALF of experimental groups increased significantly,compared with CK group(P<0.01),and the numbers of the Y-3 group was higher than others(P < 0.05).The ratios of neutrophils to total leukocytes increased significantly(P <0.01).The results of H.E.staining showed that the score of pulmonary inflammation in the experimental group was significantly higher than that in CK group(P<0.01).The results showed that after the exposure of cigarette smoke,the lung of rats had an inflammatory response,and the neutrophils and other inflammatory cells were aggregating and infiltrating.2.With the time of exposure goes on,the levels of MIP-2 in lungs and LTB4 in serum of rats in each experimental group were significantly increased(P<0.05),and the growth rate of Y-3 group was significantly higher than others.After 60 d of smoking,the levels of MPO activity and NE expression in the lung of the experimental groups were significantly increased compared with CK group(P<0.05),and Y-2 group has the largest increase.The levels of expression and phosphorylation of p38 in lungs of rats in the experimental groups were significantly higher than that of CK group(P<0.01),and the growth rate of Y-2 group was the largest one.Results show that different genotypes of tobacco smoke can induce different degrees of neutrophilic chemokines and expression and activation of p38 MAPK in COPD rats,and regulating the neutrophilic inflammatory effect.3.After the exposure of smoke,the expression levels of NE,p38 and p-p38 in the liver and spleen of the experimental groups were significantly higher than that of CK group(p<0.01),in which the growth of Y-2 group was obviously higher than others.When exposed after 30 d,the expression levels of p38 in the kidneys and hearts of experimental groups was not obvious,and the expression levels of NE,p38 and p-p38 was significantly increased after 60 d of smoking(p<0.05).Results show that different genotypes of tobacco smoke can induce expression levels of neutrophilic inflammation related proteins in main extrapulmonary organs increase with different degrees,especially for liver and spleen.Conclusion: After the exposure of different genotypes of tobacco smoke,the lungs of rats occur different degrees of neutrophilic inflammation,at the same time,the expression levels of neutrophilic inflammation related proteins in extrapulmonary main tissues have different degrees of increase.The tobacco smoke of Y-2 induced the stronger effects on the expression and activation of p38 and effect proteins of neutrophilic inflammation by cigarette smoke effect,compared with Y-1 and Y-3,and Y-3 induced higher levels of neutrophilic chemokines than others.This condition may be due to different genotype tobacco burn and releasedifferent chemicals,lead to a different degrees of biological effects,at the same time,there may be more regulatory factors involved in this process that needs to be further research.According to detect the chemokines,effect proteins,as well as the regulative proteins which relative with neutrophil,we can find the different effects of different chemical composition of the air pollutants,it's significative for revealing the biological effects and the potential toxicological mechanism of air pollutants exposure.