Protective Properties Of N-acetylcysteine On Lipopolysaccharide-induced Respiratory Inflammation And Oxidative Stress

Respiratory disease has always been a major problem in medical field and breeding industry.Bovine respiratory disease(BRD)has a multifactorial etiology and develops as a result of complex interactions between environmental factors,host factors,and pathogens.As the most common and costly disease,BRD plays an adverse effect of the development of beef cattle and dairy industry.Due to the multifactorial etiology,it makes difficulty to fully diagnose and prevent the disease.In recent years,the use of environmental-friendly and efficient alternatives to antibiotics for animal health has become the current consensus of feeding industry.N-Acety-L-cysteine(NAC),as a derivative of cysteine,has significant antioxidate,anti-inflammatory and immunological activity.In experiment,we established LPSinduced embryonic bovine tracheal cells(EBTr)inflammation and oxidative-stress models to explore the protective effects of NAC.Based on the results of cell experiment,the effect of N-Acety-L-cysteine on LPS-induced lung injury model in mice was further studied,and the feasibility of NAC as a feed additive to protect lung injury was discussed.1 Regulation of N-Acety-L-cysteine on LPS-induced embryonic bovine tracheal cell(EBTr)inflammation modelsThis experiment aims to study the optimal treatment concentration of N-Acety-L-cysteine(NAC)on embryonic bovine tracheal cells(EBTr)and its effect on LPS-induced inflammation models.In this study,to find appropriate concentration,the CCK8 method was used to assess cell viability after exposure to different concentration of NAC for 24 hours.Cells were divided into 4 groups: control group(PBS group),NAC group(NAC),LPS group(LPS),NAC protection group(LPS+NAC),using RT-q PCR method to explore The effect of NAC pretreatment on the expression of genes related to inflammation and oxidative stress in LPS-induced EBTr models.Cells were treated with LPS at 4 μg/m L for 0,3,6,9,12,and 24 h respectively,and the results showed that the relative m RNA levels and secretion of IL-6 and IL-8 reached a peak at 6 h.So,6 h was selected as optimal treating time.Within 9 h of LPS treatment,the expression level of oxidative stress-related gene HO-1 has been increasing,while Nrf2 and NQO-1 showed different downward trends.After NAC pretreatment,it can significantly reduce the increasing trend of inflammation-related genes and factors asuch as IL-6 and IL-8 caused by inflammation.In addition,NAC can also reverse the change of m RNA levels of antioxidant-related genes such as HO-1,Nrf2,NQO-1,and maintain homeostasis.2 Protective effect of NAC on LPS-induced acute lung injury model in miceBovine respiratory disease(BRD)is one of the most fatal and costly diseases that hinder the development of beef cattle and dairy industry.N-acetylcysteine(NAC),a compound with a variety of biological functions,was developed in the 20 th century and has been widely used in the medical domain.In recent years,the possibility of making it as animal feed additives has been received more attention.The purpose of this study was to investigate the protective effect of N-acetylcysteine on the inflammation and oxidative injury in lipopolysaccharide(LPS)-induced mice acute lung injury model,and to compare with Dexamethasone(DEX).In this experiment,60 ICR mice were randomly divided into control group(PBS group),NAC group(NAC),ALI group(LPS),NAC protection group(LPS+NAC)and DEX protection group(LPS+DEX),with 12 mice in each group.Dexamethasone was intraperitoneally injected into the DEX group 2 h before modeling.The ALI mice model was established by endotracheal injection of LPS.The protective effect of NAC pretreatment on the mice model of acute lung injury was studied by intragastric administration of 600 mg/kg NAC for three consecutive days.2 h after the last intragastric administration,endotracheal infusion of LPS was conducted.After 12 h of modeling,alveolar lavage fluid and lung tissue samples were collected and analysed further.Results showed that endotracheal drip LPS,the number of total cells in mice alveolar lavage fluid,neutrophil percentage,IL-6,IL-1β,TNF-α inflammatory factors,MPO activity and MDA concentration in lung tissue,inflammation related factor m RNA expression and lung injury score were significantly higher than that of control group,said acute lung injury model induced by success.The pretreatment of NAC and DEX can significantly attenuate the pulmonary inflammation,reduce the number of total cells in the alveolar lavage fluid and the m RNA expression of inflammatory genes such as IL-6,IL-1β,TNF-α,inhibit the activity of MPO in the tissue,down-regulate the concentration of lung MDA,and alleviate the oxidative damage of the body.The results showed that intragastric administration of NAC could effectively alleviate the inflammatory response and oxidative damage in ALI model of mice,but the protective effect was slightly weaker than that of dexamethasone.