Effect Of Arbutin On Murine Airway Inflammation By Co-Exposure To Ovalbumin And Fine Particulate Matter

Objective:With the development of urban industrialization,the pollution of fine particulate matter(PM_2.5)in the air increases,which leads to an increase in the incidence rate of asthma.Asthma is a common chronic respiratory disease characterized by allergic airway inflammation.Therefore,controlling and preventing airway inflammation is the focus of asthma prevention and treatment.At present,the drug prevention and treatment of asthma is mainly the use of corticosteroids.However,long-term use of corticosteroids will not only bring heavy economic burden to patients,but also produce many adverse reactions.Therefore,people need to find an anti-inflammatory active substance with low price and small side effects to prevent asthma.β-Arbutin（AR）,a phytochemical derived from hydroquinone,which has become the focus of disease prevention and control research in recent years due to its cheap,accessible and natural harmless properties.Previous studies have shown that AR plays an anti-inflammatory role in acute lung injury and lung inflammation induced by cigarette smoke,which mechanism is related to regulating the secretion of inflammatory cytokines,signal transduction and activator of transcription 6（STAT6）protein expression.However,whether AR can play an anti-inflammatory role in asthma aggravated by PM_2.5and its specific mechanism have not been reported.This study observed the effect of AR on airway inflammation in mice induced by combined exposure to Ovalbumin（OVA）and PM_2.5,and explored the effect of AR on the expression of Janus Kinase 1（JAK1）and STAT6 protein,exploring its possible mechanisms.This provides theoretical basis for the prevention and treatment of chronic airway inflammation by AR,and provides scientific data for the development of AR related plant resources.Methods:1.Animal grouping:Seventy 5-week-old male BALB/c mice were randomly divided into five groups:Control group（control,given normal saline）,OVA+PM_2.5group(2.0μg OVA/mouse,0.1 mg PM_2.5/mouse),OVA+PM_2.5+AR₁₀group(2.0μg OVA/mouse,0.1 mg PM_2.5/mouse,10 mg AR/kg),OVA+PM_2.5+AR₅₀group(2.0μg OVA/mouse,0.1 mg PM_2.5/mouse,50 mg AR/kg)and OVA+PM_2.5+AR₁₀₀group(2.0μg OVA/mouse,0.1 mg PM_2.5/mouse,100 mg AR/kg),14 in each group.All AR intervention groups were given AR dissolved in normal saline by gavage,and the rest groups were given the same amount of normal saline.After 30 minutes of gavage,the control group was perfused with normal saline in the trachea,and the remaining group was imbued with OVA and PM_2.5to establish an airway inflammation model.The intervention was given once every 2 weeks and the same intervention was performed 4times.2.Cell count of bronchoalveolar lavage fluid（BALF）:The white blood cells,neutrophils,lymphocytes,macrophages and eosinophils in BALF of mice were counted with the automatic five-classification blood cell analyzer.3.Detection of cytokines in BALF:Enzyme-linked immunosorbent assay（ELISA）to detect Interleukin-4（IL-4）,IL-5,IL-13,Eotaxin,IL-1β、IL-6,Tumor necrosis factor-α（TNF-α）And IL-17A level in BALF.4.Detection of serum OVA specific antibody:The levels of OVA specific immunoglobulin E（OVA-Ig E）and OVA-Ig G1 in mice serum were detected by ELISA.5.Pathological staining score:Hematoxylin-eosin staining（HE）staining was used to evaluate the infiltration of eosinophils and lymphocytes in the respiratory tract of mice after lung tissue section,and the proliferation of goblet cells in the bronchial epithelium was observed by Periodic Acid-Schiff stain（PAS）.6.Determination of JAK1 and STAT6 protein expression in lung tissue:Western blot（WB）was used to detect the expression level of phosphorylated and non-phosphorylated JAK1 and STAT6 proteins in mouse lung tissue.Results:1.Compared with the control group,the total number of white blood cells,neutrophils,lymphocytes,macrophages and eosinophils in BALF of OVA+PM_2.5group mice increased.Compared with OVA+PM_2.5group,the number of white blood cells in BALF of AR group mice decreased.2.Compared with the control group,IL-4,IL-5,IL-13,Eotaxin,IL-1β,IL-6,TNF-αand IL-17A levels increased in BALF of OVA+PM_2.5mice.Compared with OVA+PM_2.5group,the number of cytokines in BALF of AR group mice decreased.3.Compared with the control group,the levels of OVA-Ig E and OVA-Ig G1 in the serum of the OVA+PM_2.5group mice increased.Compared with the OVA+PM_2.5group,the level of OVA specific antibody in the serum of mice in the AR group decreased.4.Compared with the control group,the pathological score of lung tissue in the OVA+PM_2.5group increased,and the infiltration of inflammatory cells in the tissue increased.Compared with the OVA+PM_2.5group,the score of each AR group decreased and the degree of inflammatory cell infiltration decreased.5.Compared with the control group,the expression of phosphorylated protein of JAK1and STAT6 in the lung tissue of OVA+PM_2.5group increased.Compared with OVA+PM_2.5group,the phosphorylated protein expression of JAK1 and STAT6 in lung tissue of AR group mice decreased.Conclusion:Prophylactic administration of AR can alleviate airway inflammation in mice caused by combined exposure to OVA and PM_2.5.This effect may be achieved by AR by inhibiting the secretion of related inflammatory cytokines and the expression of phosphorylated JAK1 and phosphorylated STAT6 proteins in the JAK1/STAT6 pathway,thus reducing the infiltration of airway submucosal inflammatory cells and the proliferation of bronchial epithelial goblet cells.