| Background and objectives:Asthma and bronchiectasis are common chronic airway diseases.Asthma is a chronic airway inflammatory disease involving a variety of cells and cell components.The clinical manifestations are recurrent wheezing and shortness of breath with or without chest tightness or cough,accompanied by airway hyperresponsiveness and variable airflow limitation.With the prolongation of the course of disease,it can lead to airway structural changes,known as airway remodeling[1,2].Bronchiectasis is a chronic airway infectious disease with pathological and incomplete reversible dilatation of bronchial tree caused by various reasons.The typical symptoms include chronic cough,expectoration and hemoptysis[3,4].The co-existence of asthma and bronchiectasis is not uncommon.Compared with asthma alone,patients with Asthma-Bronchiectasis overlap（ABO）have more severe symptoms,worse lung function,higher exacerbation rates,longer hospitalization,higher hospital costs,and higher mortality rates[5-9].Compared with bronchiectasis alone,ABO patients had higher HRCT scores,lower severity of bronchiectasis,lower detection rate of Pseudomonas aeruginosa,and higher acute exacerbation rate[10,11].This has become a common and important problem faced by respiratory physicians.Previous studies have shown that bacterial infection is closely related to the occurrence and development of bronchiectasis.In sputum of bronchiectasis patients,Haemophilus influenza and Pseudomonas aeruginosa are the most commonly isolated pathogenic bacteria.Infection or colonization of Pseudomonas aeruginosa is closely related to the severity,acute exacerbation frequency and prognosis（such as poor pulmonary function,faster decline of pulmonary function and higher mortality）of bronchiectasis[12-14].However,there is no further study to explore the relationship between lower airway bacteria detection and clinical characteristics of ABO patients so far.In recent years,with the development of 16sr RNA sequencing,the association between human microbiome and chronic airway disease has been gradually explored.There is a significant airway microbiome dysbiosis in patients with asthma,and its degree is related to airway hyperresponsiveness,airway inflammatory phenotype,disease severity and asthma control[15,16].In patients with bronchiectasis,the degree of airway microbiome dysbiosis is significantly correlated with disease severity and acute exacerbation[17-20].However,there is no further study to explore the characteristics of lower airway microbiome in ABO patients and its relationship with clinical characteristics.Respiratory viral infection is an important cause of acute exacerbation inasthma and bronchiectasis[21,22].Furthermore,the role of bacterial and viral co-detection in chronic airway diseases is gradually being paid attention to.The previous study of our research group also proved that bacterial and viral co-detection was closely related to the risk of acute exacerbation in bronchiectasis[23].Nevertheless,there is no further study to explore the relationship between lower airway virus spectrum and bacterial microbiome and acute exacerbation in ABO patients so far.Hence,this study mainly focused on three important scientific issues:1)To investigate the association between lower airway bacterial detection in stable ABO patients and disease severity and acute exacerbation;2)To explore the relationship between lower airway microbiome dysbiosis and clinical characteristics in ABO patients,and to further clarify the heterogeneity of ABO from the perspective of inflammatory phenotype and microbiome;3)To explore the characteristics of viral detection in ABO acute exacerbation and its relationship with microbiome and acute exacerbation.The purpose of this study is to provide evidence for the precise treatment for ABO patients in the future.Section 1:The Association Between Lower Airway Bacterial Detection and Clinical Characteristics in Patients with Asthma-Bronchiectasis Overlap DuringStable Period:A Prospective Cohort StudyBackground:Bacterial infection or colonization is closely related to the disease severity and acute exacerbations frequency in patients with bronchiectasis.However,the relevance between lower airway bacterial detection and clinical characteristics of patients with Asthma-Bronchiectasis overlap（ABO）is not yet clear.Objective:To investigate the detection of lower airway bacteria in stable ABO patients and its relevance with disease severity and acute exacerbations.Methods:This is a prospective,observational cohort study which included 81patients with ABO.During the baseline visit at stable phase,comprehensive clinical assessments were conducted,sputum samples were collected for bacterial culture.Patients were followed up closely to record acute exacerbation events and lung function tests were performed during stable visit.Results:During stable period,55.5%of ABO patients had positive sputum cultures,with Pseudomonas aeruginosa（PA）being the most common.Compared with the negative group,ABO patients with any positive bacterial detection or with PA detection had baseline clinical characteristics mainly reflected as longer disease duration（median:20.0years vs 10.0years,P<0.001;22.0years vs 21.3years,P<0.001）,more sputum production（sputum volume≥10ml/day:71.1%vs 44.4%,P=0.015;77.4%vs 48.0%,P=0.009）,higher bronchiectasis severity index（BSI:7.0vs 3.5,P<0.001;8.0 vs 4.0,P<0.001）,higher Reiff scores（9.3 vs 6.8,P<0.001;8.0vs 7.0,P=0.004）,more severe obstructive dysfunction（FEV1%pred:51.9%vs 65.9%,P<0.001;50.6%vs 62.8%,P=0.003）,and more severe neutrophilic airway inflammation（percentage of neutrophil in sputum:96.2%vs 92.3%,P=0.007;96.5%vs 93.4%,P=0.003）.Compared with the positive sputum culture group,the negative group had a higher proportion of patients with a history of wheezing episodes（52.7%vs 31.1%,P=0.049）and allergic rhinitis（66.7%vs 35.5%,P=0.005）,and a higher percentage of eosinophil in blood（3.0%vs 1.7%,P=0.003）.However,the proportion of patients with a family history of allergic diseases（58.0%vs 35.5%,P=0.049）and allergic rhinitis（52.0%vs 29.0%,P=0.043）was significantly higher in the PA-negative group than in the positive group.Patients with ABO who underwent FEV1 pred%re-examination during follow-up showed significant improvement compared with baseline（62.0%vs 56.4%,P<0.001）.Compared with ABO patients with negative sputum culture,patients with positive bacterial cultures at baseline had significantly more bronchiectasis acute exacerbations（0.9 vs 0.2 time per patient-year,P=0.016）.Furthermore,patients with positive bacterial cultures（median time:7months vs 14 months,P=0.005;HR:2.13,95%CI:1.24-3.68）and PA culture（median time:7 months vs 11 months,P=0.046;HR:1.70,95%CI:0.93-3.01）had a significantly shorter time from enrollment to the first bronchiectasis acute exacerbation compared with negative group.The risk of positive sputum cultures in patients with ABO was significantly positively correlated with obstructive dysfunction and significantly negative correlated with more severe blood eosinophil inflammation and existence of allergic rhinitis（P<0.05）,while longer disease duration and higher HRCT Reiff score were significantly positively correlated with the risk of PA detection in patients with ABO（P<0.05）.Conclusions:ABO patients with PA or any bacteria culture positive had more severe bronchiectasis,shorter time to the next bronchiectasis acute exacerbation,while negative group of patients had more prominent asthma-related clinical features.For patients with ABO,we found that there was some reversibility of airflow limitation during follow-up.Clinicians need to focus on sputum culture results（especially those with bacterial detection risk factors）and individualized interventions aimed at ABO heterogeneity.Section 2:The Relationship Between Lower Airway Microbiome and Clinical Characteristics in Asthma-Bronchiectasis Overlap During Stable Period: A Prospective Cohort StudyBackground: Microbiome dysbiosis in the lower airways of patients with asthma and bronchiectasis are closely related to clinical characteristics and airway inflammation phenotypes.However,the microbiome of lower airways in patients with ABO and its relevance with clinical characteristics remained unclear.Objective: To investigate the relevance between lower airway microbiome dysbiosis and clinical characteristics in ABO patients,and to clarify the heterogeneity of ABO from the perspective of inflammation phenotype and lower airway microbiome.Methods: This is a prospective,observational cohort study.Patients with asthma alone（As）,ABO,and bronchiectasis alone（Bx）were first underwent clinical evaluation during stable periods at an inclusion visit,and their sputum samples were analyzed by 16 S r RNA sequencing.Patients were followed up to evaluate the risk of bronchiectasis exacerbation.Results: There were significant differences in clinical characteristics between ABO and As,Bx patients during clinically stable period.The Shannon diversity index of lower airway microbiome in patients with ABO was significantly lower than that in patients with As,but higher than that in Bx patients（Median: 4.36 vs 5.26,P<0.001;4.36 vs 3.69,P<0.001）,while the β diversity was intermediate between asthma and bronchiectasis [the Principal coordinate analysis（PCo A）using weighted Uni Frac distance: R2=0.100,P=0.001].The top five dominant genera were Streptococcus（relative abundance: 18.5%）,other genera in Pseudomonadaceae except Pseudomonas（Other genera in Pseudomonadaceae for short,17.6%）,Neisseria（8.9%）,Haemophilus（6.9%）,and Rothia（6.7%）.Other genera in Pseudomonadaceae and Rothia were the most specific genera in patients with ABO（LDA>4.0,FDR P<0.05）compared to As and Bx.ABO patients,who suffer from more severebronchiectasis（higher BSI,E-FACED or Reiff scores）and airflow limitation but milder asthma in stable period,had the lower airway microbiome diversity,the higher relative abundance of other genera in Pseudomonadaceae,the lower relative abundance of Streptococcus and Rothia（P<0.05）.In stable ABO patients,26% were eosinophilic（Eos-ABO）and 74% were non-eosinophilic（non Eos-ABO）.Compared with non Eos-ABO,Eos-ABO patients had a higher proportion of allergic rhinitis（68.0% vs 39.4%,P=0.014）and severe asthma（64.0% vs 12.7%,P<0.001）,as well as higher total Ig E（167.5 KU/ml vs 41.7 KU/ml,P<0.001）and Fe NO levels（25.0ppb vs 14.5ppb,P=0.025）.Compared with Eos-ABO,non Eos-ABO patients had a higher proportion of baseline sputum production ≥10 ml/day（56.3% vs 24.0%,P=0.005）,higher Reiff score（8.0 vs 4.0,P=0.001）,more severe airflow limitation（FEV1%pred: 60.2% vs 71.3%,P=0.023）,higher blood CRP（0.4mg/d L vs 0.1mg/d L,P<0.001）,higher percentage of eosinophil in sputum（96.0% vs 74.0%,P<0.001）,and higher sputum culture positive rate（53.5% vs 24.0%,P=0.011）.Streptococcus and Rothia were the most specific genera for Eos-ABO patients（LDA>4.0,FDR P< 0.05）compared to non Eos-ABO patients.ABO patients were divided into four groups according to the median of the Shannon diversity index and sputum eosinophil levels: in Eos-ABO patients,low α diversity group had an increased risk of bronchiectasis acute exacerbation（Mean: 1.4 vs 0.0 time per person-year,P<0.001）and a shorter time from enrollment to the first bronchiectasis acute exacerbation（HR:8.74,95% CI:2.51-30.45）compared to the high α diversity group;for low αdiversity ABO patients,the Eos group had a significantly higher annual frequency of bronchiectasis acute exacerbation than the non-Eos group（1.4 vs 0.6 time per person-year,P=0.040）;however,for high α diversity ABO patients,the non-Eos group had a higher risk of bronchiectasis acute exacerbation（0.5 vs 0.0 time per person-year,P < 0.001.）and a shorter time from enrollment to the first acute exacerbation（HR: 4.00,95% CI:1.55-10.34）than the Eos group.Conclusion: The lower airway microbiome features of stable ABO patients were significantly different from As and Bx and were significantly associated with clinical characteristics.The clinical features of asthma are more pronounced in Eos-ABOpatients,while those of bronchiectasis are more prominent in non Eos-ABO patients.There are significant differences in the risk of bronchiectasis acute exacerbation in ABO patients under the combined effect of different levels of airway eosinophilic inflammation and different airway microbiome diversity,and clinical intervention should take into account its heterogeneity.Section 3: Role of Lower Airway Viral Spectrum and Bacterial Microbiome in Acute Exacerbation of Asthma-Bronchiectasis OverlapBackground: Respiratory viral infection is an important cause of acute exacerbation in asthma and bronchiectasis.Bacterial-viral co-detection is significantly associated with the risk of acute exacerbations of bronchiectasis.However,the characteristics of viral detection in lower airway during acute exacerbation and its association with microbiome and acute exacerbation in ABO patients are still unclear.Objectives: To investigate the characteristics of bacterial and viral detection in lower airway during bronchiectasis acute exacerbation in ABO patients and the corresponding risk of bronchiectasis acute exacerbation,and to explore the microbiome characteristics in lower airway during bronchiectasis acute exacerbation with or without viral detection in ABO patients.Methods: A prospective,observational cohort study was conducted to follow up the ABO patients in stable and bronchiectasis acute exacerbation phases,and to perform clinical evaluations.Sputum was collected for sputum bacterial culture,16 Sr RNA sequencing and viral detection.Results: During the follow-up of 81 ABO patients,the median bronchiectasis acute exacerbation rate was 0.6（IQR:1.4）time per patient-year.ABO patients with sputum culture detection of bacteria other than Pseudomonas aeruginosa and Haemophilus influenza had a significantly higher corresponding risk for bronchiectasis acute exacerbations [odds ratio（OR）: 2.18,95% CI:1.10-4.33].Theviral detection rate was significantly higher during acute exacerbation than stable phase（31.6% vs 17.2%,P=0.015）,and OR of bronchiectasis acute exacerbation associated with any virus and nasal virus detection was 2.23（95% CI:1.01-4.94）and3.22（95%CI:1.02-10.21）respectively.Compared with stable phase,the incidence of bacteria-negative but virus-positive（B-V+）was significantly higher in the acute exacerbation phase（15.0% vs 5.6%,P=0.022）,with a corresponding OR for bronchiectasis acute exacerbation of 2.96（95% CI:1.23-7.13）.There was no significant difference in α and β diversity of lower airway microbiome between stable and bronchiectasis acute exacerbation phases,and between patients with and without viral detection on the first day of bronchiectasis acute exacerbation（P>0.05）.During bronchiectasis acute exacerbation in ABO patients,Klebsiella,Moraxella,Streptococcus,Rothia,other genera in Gemellaceae other than Gemella were the most specific genera in patients with viral isolations compared with patients without viral isolations;while compared with patients with viral isolations,Pseudomonas was the most specific genus in patients without viral isolations（LDA score>4.0,FDR P<0.05）.Conclusions: Detection of bacteria other than Pseudomonas aeruginosa and Haemophilus influenza,any virus,nasal virus,and only viral isolations increased the risk of bronchiectasis acute exacerbations in ABO patients.There was a significant difference in the composition characteristics of lower airway genera between ABO patients with and without viral isolations during bronchiectasis acute exacerbation,and the treatment for ABO patients during bronchiectasis acute exacerbation should be highly individualized. |
PDF Full Text Request