Feasibility Study Of Interleukin-6 In Assessing And Improving The Prognosis Of Chronic Obstructive Pulmonary Disease

Background and purpose:Chronic obstructive pulmonary disease,referred to as COPD,is a systemic inflammatory disease,which is the fourth leading cause of death in the world and the fifth leading cause of death in Chinese.Persistent chronic inflammation can lead to frequent exacerbations of COPD,thereby reducing patients’ quality of life,accelerating disease progression,and increasing mortality.Therefore,reducing the frequent exacerbations of COPD is one of the important goals of COPD treatment,and it is particularly important to predict the frequency of acute exacerbations in one year and intervene in advance.Current studies have shown that interleukin-6(IL-6)plays an important role in maintaining chronic inflammation and leading to poor prognosis.However,there is insufficient evidence to support IL-6 as a good predictor of COPD exacerbation frequency,and therefore,it has not been widely used in clinical practice.In addition,given the important role of IL-6 in COPD,it may become one of the targets for the treatment of COPD.This study aims to evaluate whether IL-6 can predict the frequency of acute exacerbation of COPD within one year through one-year follow-up observation of COPD patients,and to provide more clinical evidence to support IL-6 as a predictor;At the same time,the therapeutic effect of antagonizing IL-6 on COPD was also explained by in vitro and in vivo experiments.Methods:1.First,we retrospectively collected clinical information and serum IL-6 levels of patients with stable COPD who were admitted to the Department of Respiratory and Critical Care Medicine,Huizhou Central Hospital from January 2016 to December 2017 through a retrospective of the outpatient electronic medical record system.We obtained the optimal serum IL-6 threshold for predicting the frequency of COPD exacerbations by reviewing the data and performing statistical analysis.Then,from January 2018 to December 2020,patients with stable COPD who were treated in our department were recruited,and the patients were divided into low IL-6 group and high IL-6 group according to the best predictive threshold of IL-6.All recruited patients will be followed up once a month by telephone,outpatient clinic,etc..The follow-up time will be one year,and the frequency of acute exacerbations within one year will be observed and recorded.2.HBECs were stimulated with CSE to establish a cell model of COPD.CCK8 was used to evaluate the viability of CSE-induced HBECs.The expression of IL-6 was detected by RT-qPCR and ELISA,then,the CSE-induced cells were treated with IL-6 or Tocilizumab,and RT-qPCR,ELISA and Western-blot were used to detect the related indicators of inflammatory response and airway remodeling response,the effects of IL-6 and Tocilizumab on oxidative stress response were verified by superoxide dismutase(SOD)activity and lipid Peroxidation(MDA)assay.3.Twenty-four rats were randomly divided into three groups:blank control group,COPD without Tocrlizumab treatment group and COPD with Tocilizumab treatment group.The COPD groups were treated by smudging and Lipopolysaccharide(LPS),and then the COPD without Tocilizumab treatment group was given saline while the COPD with Tocilizumab treatment group was given saline and Tocilizumab.Finally,the lung tissues of rats were collected and HE,PAS and MASSON staining were performed to detect the pathological changes of lung tissues.Results:1.A total of 95 patients with stable COPD who met the inclusion criteria and had complete data were retrospectively collected.The frequency of acute exacerbation in the enrolled patients was at least once in the past 1 year,and 35 of them had an exacerbation frequency of ≥2 times.The average hs-CRP and IL-6 were 5.5 mg/L and 8.8 pg/mL,respectively.Correlation analysis showed that serum IL-6 was positively correlated with acute attack frequency,CAT score and mMRC score in the past 1 year,but negatively correlated with pulmonary function indicators such as FEV1%pred,FEV1/FVC%.Hs-CRP Analysis also showed similar results,but to a lesser extent than IL-6.Binary regression analysis showed that high levels of serum IL-6 in vivo were significantly associated with the risk of two or more exacerbations within 1 year.The ROC curve analysis showed that IL-6 had a high value in predicting≥2 times within 1 year,the area under the curve(AUC)was 0.970,and the optimal threshold of IL-6 was 14.030 pg/mL.To test the predictive power of this value,we recruited eligible COPD patients and divided them into a low IL-6 group(IL-6≤14.030 pg/mL)and a high IL-6 group(IL-6>14.030 pg/mL).One-year follow-up of patients in both groups showed that the frequency of acute exacerbations within one year in the low IL-6 group was lower than that in the high IL-6 group,and the frequency of acute exacerbations≥ 2 times in one year was higher than that in the IL-6 group.2.CCK8 results showed that the viability of CSE-induced HBECs were decreased.All data were statistically significant(P<0.05).The results of RT-qPCR and ELISA showed that IL-6 was highly expressed in CSE-induced HBECs and promoted the inflammatory response of cells,The SOD activity and MDA assays showed that IL-6 enhanced the oxidative stress response.All data were statistically significant(P<0.05).RT-qPCR,ELISA,Western-blot,SOD activity and MDA assays indicated that the Tocilizumab could alleviate inflammatory response,airway remodeling and oxidative stress response of CSE-induced HBECs.All data were statistically significant(P<0.05).3.HE staining results showed that the alveolar structure was disordered,the alveolar wall was thickened with many emphysema,and numbers of inflammatory cells in the lung tissue of the COPD without Tocilizumab treatment group,while the alveolar structure of the COPD with Tocilizumab treatment group was clearer and with less emphysema and inflammatory cells.PAS staining showed the largely hyperplasia of goblet cells in the airway of the COPD without Tocilizumab treatment group,while the less goblet cell in the COPD with Tocilizumab treatment group.MASSON staining showed the obviously deposition of airway collagen in the COPD without Tocilizumab treatment group,while the less deposition of airway collagen in the COPD with Tocilizumab treatment group.Conclusion:1.Monitoring COPD patient’s serum IL-6 levels may help predict the frequency of exacerbations in the coming year and guide patients or doctors to take timely and appropriate measures to prevent these events occurrence,thereby improving the quality of life of patients and prolonging life.2.IL-6 plays a proinflammatory role in CSE-stimulated COPD model cells(HBECs),and Tocilizumab can alleviate the inflammatory response,airway remodeling and oxidative stress response.3.Tocilizumab can alleviate the lung inflammation and pathology,which has a therapeutic effect on the rat COPD model.