Effects Of Oxidizing Gases On Interface Properties And Oxidative Damage Of Pulmonary Surfactant

Ozone（O₃）and nitrogen dioxide（NO₂）,as typical atmospheric pollutants,are characterized by strong oxidation and easy to cause atmospheric secondary pollution,causing great harm to environmental quality and human health.Relevant studies have shown that exposure to O₃ and NO₂ is closely related to the incidence of respiratory diseases such as asthma,pneumonia and bronchitis.Therefore,it is necessary to study the effects of oxidative gas exposure on human health.Respiration is an important way of O₃ and NO₂ exposure.O₃ and NO₂ inhaled have first contacted the interface film formed by Pulmonary surfactant（PS）on the lining of alveolar lining.PS can reduce surface tension,maintain alveolar stability and other functions,and is essential to ensure normal respiratory function.The special lipid and protein composition system and interface chemistry are the basis of PS normal function.The contact between the two will strengthen the stability of the interface properties.Existing studies mainly focus on the monitoring and control of oxidizing gases,but there are few studies on human health,especially on the effects of oxidizing gases on lung health.Therefore,in this paper,O₃ and NO₂are taken as research objects to study their interaction with PS through in vitro experiments.The effects of O₃ and NO₂exposure on the chemical structure and interfacial chemical properties（surface tension,phase behavior and foaming performance）of PS active components were investigated.The effects of exposure time,body salts,antioxidant system and PS active components on the oxidative damage potential of O₃ and NO₂ were evaluated.Further,through the presence of Fe²⁺and O₃/NO₂ composite system,the effects of exposure time,PBS components,antioxidants and PS active components on its oxidation damage potential,combined with the structure changes of malondialdehyde and protein,the influence mechanism of the system on the oxidation of PS was revealed.The main conclusions are as follows:（1）Exposure to both O₃ and NO₂ can lead to changes in the chemical structure of active components in PS.The infrared spectrum analysis shows that the contents of N-（CH₃）₃,PO₂^-,C=O and other functional groups change significantly,and the disappearance of the-OH group is detected in all of them,indicating that the action of O₃ and NO₂ on PS can break or transform the original chemical bond.This may be the key to the effect of O₃ and NO₂ exposure on the chemical properties of PS interface.（2）The exposure of O₃ and NO₂ can lead to the change of the chemical properties of PS interface.With the increase of exposure time,the surface tension of PS increased gradually,theπ-A isotherm shrank,and the foaming volume decreased gradually.Among them,the effect of O₃ on PS is more obvious,which may be attributed to the stronger oxidation of O₃.（3）The oxidative potential of O₃ and NO₂ exposure was affected by the simulated pulmonary fluid system in each group.As the time of O₃ and NO₂ passing into SLF and H₂O increases,SLF can induce·O₂^-,H₂O₂ and·OH to be higher than pure water.Na2HPO4 in PBS solution can promote the generation of three ROS in SLF by O₃ and·O₂^-by NO₂ in SLF.Among the four antioxidants,only Asc and GSH can promote the ROS generation of O₃ and NO₂ in SLF;With the increase of PS and DOPC concentrations,ROS generation induced by O₃ and NO₂ increased.These conclusions indicate that exposure time,PBS component,antioxidant,PS and its active component in SLF can enhance the potential of O₃ and NO₂ to cause oxidative damage.（4）Exogenous Fe²⁺can enhance the oxidation potential of O₃/NO₂.With the increase of O₃/NO₂ inlet time,Fe²⁺can promote the generation of O₃ and NO₂ to produce·OH.Na₂HPO₄ and Fe²⁺in PBS can increase the amount of O₃ and NO₂ to produce·OH.The four antioxidants in SLF can promote the interaction of Fe²⁺and O₃/NO₂ to produce·OH,in which Asc contributes the most.With the increase of PS concentration,Fe²⁺and O₃/NO₂ have a synergistic effect on the production of OH in SLF,in which DOPC plays a major role.The content of MDA increases gradually with the time of oxygenating gas,and the presence of Fe²⁺promotes the growth of MDA.Both oxidizing gas and Fe²⁺affect the protein structure and reduce its conformational stability.In particular,the co-existence of Fe²⁺and O₃ has the most serious effect on the damage of BSA.All of the above conclusions indicate that the co-existence of Fe²⁺and O₃/NO₂ can produce synergistic effects,which can enhance the ability of oxidizing gases to cause oxidative damage and thus enhance pulmonary toxicity.