Clinical Study Of The Relationship Between Protein S100A8 And Airway Hyperresponsiveness In Bronchial Asthma

Background:Eosinophilic bronchitis(EB)shares many similarities with asthma(AS),except for the lack of airway hyperresponsiveness(AHR).In the previous study,we established a mouse model of EB characterized by an increase in cough frequency,airway eosinophilic inflammation,lack of AHR,and effective glucocorticoid therapy.The establishment of the EB mouse model provided a good reference for studying the mechanism of airway hyperresponsiveness in asthma.Through proteomic and bioinformatic analysis of lung tissues of mice in EB,AS,and normal saline(NS)groups,we found that S100A8 was the differential protein of AHR.The animal experiment showed that S100A8 was mainly found around blood vessels and tracheas of the lung tissue as a secretory protein.Compared with the EB group,the expression levels of S100A8 gene and S100A8 protein in the lung tissue of AS group increased significantly.Therefore,we hypothesized that S100A8 might be the AHR regulatory protein in asthma.Objective:This study aims to dynamically observe the expression levels of S100A8 and S100A8/A9 in induced sputum supernatant and serum of patients with bronchial asthma and analyze their relationship with AHR and other clinical characteristics to verify the previous experimental research results and further clarify that S100A8 participates in the occurrence and development of asthma,which is a regulatory protein of AHR in asthma.Research contents:PartⅠ A cross-sectional exploration of the potential of S100A8 and S100A8/A9 as biomarkers in asthmaMethods:From November 2021 to November 2022,patients who were diagnosed with bronchial asthma in the respiratory department of the First Affiliated Hospital of Guangzhou Medical University served as the AS group,and healthy subjects in the same period served as the healthy control(HC)group.The asthma diagnostic criteria referred to Chinese guidelines for bronchial asthma prevent and management(2020edition).Based on the percentage of neutrophils(Neu)in induced sputum,asthmatic patients were divided into neutrophilic asthma group(≥65%)and non-neutrophilic asthma group(<65%).Similarly,asthmatic patients were divided into eosinophilic asthma group(≥2.5%)and non-eosinophilic asthma group(<2.5%)according to the percentage of eosinophils(Eos)in induced sputum.Clinical data were recorded,including(1)medical history;(2)completion of asthma-related scales including Asthma Control Test(ACT)and Asthma Quality of Life Questionnaire(AQLQ);(3)performance of pulmonary function test and bronchial provocation test or bronchial dilation test;and(4)chest radiograph or chest CT,fractional exhaled nitric oxide(Fe NO),induced sputum test,and hematological profiles.S100A8 and S100A8/A9 concentrations in induced sputum supernatant and serum were measured by ELISA.Results:1.A total of 164 asthmatic patients and 48 healthy subjects were finally recruited.Compared to the HC group,the percentage of eosinophils in peripheral blood and induced sputum and the levels of Fe NO were significantly increased,FEV1%pred,FEV1/FVC,MMEF%pred,MEF25%pred,MEF50%pred,MEF75%pred were significantly decreased,and the expression levels of S100A8 in induced sputum supernatant,S100A8/A9 in induced sputum supernatant and serum were significantly increased in AS group,S100A8 in serum was failed to detect.2.Compared to non-neutrophilic asthma group,patients in neutrophilic asthma(NA)group were older,had significantly higher percentages of neutrophils in peripheral blood and induced sputum,significantly lower FVC%pred and FEV1%pred,and significantly higher expression levels of S100A8 and S100A8/A9 in induced sputum supernatant.There was a significant positive correlation between the expression levels of S100A8 and S100A8/A9 in induced sputum supernatant and the absolute number and percentage of neutrophils in sputum.3.Compared to the mild asthma group,patients in moderate and severe asthma groups had significantly higher expression levels of S100A8 in induced sputum supernatant.There was a significant positive correlation between the expression levels of S100A8 in induced sputum supernatant and the number of acute attacks.4.Compared to the very mild AHR group,patients in the severe AHR group had significantly higher expression levels of S100A8 in induced sputum supernatant.There was a significant negative correlation between the expression levels of S100A8 in induced sputum supernatant and the provocative dose to cause a 20 percent decline in the FEV1(PD20-FEV1).Conclusion:The expression levels of S100A8 in induced sputum supernatant,S100A8/A9 in induced sputum supernatant and serum are upregulated significantly in asthmatic patients.The expression levels of S100A8 in induced sputum supernatant correlate to the severity of asthma,airway neutrophilic inflammation,and airway hyperresponsiveness and may be involved in asthma pathogenesis.Part Ⅱ A longitudinal exploration of the relationship between S100A8,S100A8/A9 and airway hyperresponsiveness in asthmaMethods:Participants were randomly selected from the asthma group in the cross-sectional study.Baseline data were recorded,including(1)medical history;(2)completion of asthma-related scales including ACT and AQLQ;(3)performance of pulmonary function test and bronchial provocation test or bronchial dilation test;and(4)chest radiograph or chest CT,Fe NO,induced sputum test,and hematological profiles.S100A8 and S100A8/A9 concentrations in induced sputum supernatant and serum were measured by ELISA.At 3 months after baseline,participants were followed up,symptom relief,ACT and AQLQ were recorded,pulmonary function test and bronchial provocation test or bronchial dilation test,induced sputum and Fe NO were completed,and the concentrations of S100A8 and S100A8/A9 in induction sputum supernatant and serum were measured again.Results:1.A total of 82 asthmatic patients were enrolled,and 54 patients completed follow-up.After anti-asthma treatment,patients were in remission with reduced levels of eosinophilic inflammation and improved symptoms and pulmonary function indicators.2.After anti-asthma treatment,patients had a significant decrease in the expression levels of S100A8 in induced sputum supernatant and no statistically significant change in S100A8/A9 in induced sputum supernatant and serum.3.In the AS,NA,and EA groups,there was a significant positive correlation between the change value of S100A8 in induced sputum supernatant and the change value of the percentage of neutrophils in sputum.4.In the NA group,the change value of S100A8 in induced sputum supernatant negatively correlated with the change value of MEF50%pred,which was the AHR-related indicator.The expression levels of S100A8 in induced sputum supernatant had certain value in diagnosing airway hyperresponsiveness in asthma.Conclusion:S100A8 in induced sputum supernatant is associated with airway hyperresponsiveness in neutrophilic asthma and may be a regulatory protein of airway hyperresponsiveness in neutrophilic asthma.