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8
Pathophys.
7
Phenotypes
15
Pathograph
2
Genes
8
Medical Actions
12
References
2
Deep Research
🏷

Classifications

Harrison's Chapter
RESPIRATORY

Pathophysiology

8
Chronic Infection and Inflammation
Persistent microbial infections and inflammation damage airway walls, leading to dilation and thickening.
Show evidence (1 reference)
DOI:10.1183/16000617.0055-2024 SUPPORT Human Clinical
"The presence of airway infection together with chronic inflammation, airway mucociliary dysfunction and lung damage are key components of the vicious vortex model that better describes its pathophysiology."
Vicious vortex model centers on chronic infection plus inflammation as the core pathophysiology of bronchiectasis.
Airway Dilation
Destruction of elastin and cartilage in the bronchial walls causes irreversible dilation of bronchi.
Impaired Mucociliary Clearance
Damage and dilation of airways hinder effective clearance of mucus, allowing for accumulation and further infection.
airway epithelial cell CL:0002368 ciliated epithelial cell CL:0000067
mucociliary clearance GO:0003351 cilium movement GO:0003341
bronchus UBERON:0002185
Neutrophil-Driven Inflammation
Excessive neutrophil recruitment, degranulation, and NET formation release proteases (neutrophil elastase, proteinase 3, cathepsin G) that degrade extracellular matrix, impair ciliary function, and damage epithelial barriers.
neutrophil CL:0000775
neutrophil degranulation GO:0043312 neutrophil extracellular trap formation GO:0140645 inflammatory response GO:0006954
bronchus UBERON:0002185 extracellular space GO:0005576
Show evidence (2 references)
DOI:10.1183/16000617.0179-2024 SUPPORT Human Clinical
"The excessive release of neutrophil serine proteases, such as neutrophil elastase, cathepsin G and proteinase 3, promotes a protease–antiprotease imbalance that correlates with increased inflammation in bronchiectasis and contributes to disease progression."
Direct evidence that neutrophil serine proteases drive inflammation and disease progression in bronchiectasis.
DOI:10.1055/s-0041-1730891 SUPPORT Human Clinical
"Recent data show that neutrophil extracellular trap formation may be the key mechanism leading to protease release and severe bronchiectasis."
Supports NET formation as a key mechanism for protease release and disease severity.
Protease-Antiprotease Imbalance
Excess neutrophil serine proteases (NE, PR3, CatG) overwhelm antiproteases (SLPI, A1AT), degrading structural proteins and perpetuating tissue damage.
proteolysis GO:0006508
extracellular space GO:0005576
Show evidence (1 reference)
DOI:10.1183/16000617.0179-2024 SUPPORT Human Clinical
"The excessive release of neutrophil serine proteases, such as neutrophil elastase, cathepsin G and proteinase 3, promotes a protease–antiprotease imbalance that correlates with increased inflammation in bronchiectasis and contributes to disease progression."
Directly supports protease-antiprotease imbalance as a neutrophil serine protease-driven mechanism linked to inflammation and bronchiectasis progression.
Goblet Cell Hyperplasia and Mucus Hypersecretion
Increased goblet cell numbers and overproduction of gel-forming mucins (MUC5AC, MUC5B) lead to mucus hyperconcentration and impaired clearance.
goblet cell CL:0000160
mucus secretion GO:0070254
bronchus UBERON:0002185
Show evidence (1 reference)
DOI:10.1055/s-0041-1730891 SUPPORT Human Clinical
"Mucus symptoms arise through goblet cell hyperplasia and metaplasia and reduced ciliary function through dyskinesia and loss of ciliated cells."
Direct support for goblet cell hyperplasia as a source of mucus symptoms in bronchiectasis.
Inflammasome Activation and IL-1beta Signaling
NLRP3 inflammasome activation drives IL-1beta production, which directly impairs ciliary function, disrupts tight junctions, promotes mucus hyperconcentration, and is associated with severe disease and Proteobacteria enrichment.
airway epithelial cell CL:0002368
interleukin-1 beta production GO:0032611
NLRP3 inflammasome complex GO:0072559
bronchus UBERON:0002185
Show evidence (2 references)
DOI:10.1183/13993003.01966-2023 SUPPORT Human Clinical
"A subset of stable bronchiectasis patients show increased airway IL-1β, suggesting pulmonary inflammasome activation is linked with more severe disease, airway infection, mucus dehydration and epithelial dysfunction."
Cohort study (n=269) directly links airway IL-1beta to inflammasome activation, severity, and epithelial dysfunction.
"Chronic IL-1β treatment reduced the functionality of cilia and tight junctions of epithelial cells"
In vitro mechanistic evidence that IL-1beta directly impairs ciliary and tight-junction function in airway epithelial cells.
Microbiome Dysbiosis
Reduced microbial diversity with Proteobacteria dominance, particularly Pseudomonas aeruginosa and Haemophilus influenzae, drives chronic infection, exacerbations, and disease progression.
bronchus UBERON:0002185 respiratory tract mucus UBERON:0000912
Show evidence (2 references)
DOI:10.1055/s-0041-1730891 SUPPORT Human Clinical
"Loss of diversity of the normal lung microbiota and dominance of proteobacteria such as Pseudomonas and Haemophilus are features of severe bronchiectasis and link to poor outcomes."
Direct support for Proteobacteria dominance as a feature of severe disease.
DOI:10.1186/s12931-024-02931-x SUPPORT Human Clinical
"Patients with bronchiectasis, with or without FAO, had similar microbiome profiles characterized by reduced alpha diversity and a predominance of Proteobacteria"
Confirms reduced alpha diversity and Proteobacteria predominance via 16S rRNA sequencing of BAL samples.

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Bronchiectasis Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.

Phenotypes

7
Immune 1
Recurrent Respiratory Infections FREQUENT Recurrent respiratory infections HP:0002205
Show evidence (1 reference)
DOI:10.1183/16000617.0179-2024 SUPPORT Human Clinical
"Patients with clinically significant bronchiectasis have chronic cough and sputum production, as well as recurrent respiratory infections, fatigue and impaired health-related quality of life."
Recurrent respiratory infections are a hallmark clinical feature of bronchiectasis.
Respiratory 6
Chronic Cough VERY_FREQUENT Chronic cough HP:0034315
Show evidence (1 reference)
DOI:10.1183/16000617.0179-2024 SUPPORT Human Clinical
"Patients with clinically significant bronchiectasis have chronic cough and sputum production, as well as recurrent respiratory infections, fatigue and impaired health-related quality of life."
Chronic cough is a defining clinical feature of bronchiectasis.
Sputum Production VERY_FREQUENT Increased sputum production HP:0033709
Often purulent and copious
Show evidence (1 reference)
DOI:10.1183/16000617.0179-2024 SUPPORT Human Clinical
"Patients with clinically significant bronchiectasis have chronic cough and sputum production, as well as recurrent respiratory infections, fatigue and impaired health-related quality of life."
Sputum production is a defining clinical feature of bronchiectasis.
Dyspnea FREQUENT Dyspnea HP:0002094
Hemoptysis OCCASIONAL Hemoptysis HP:0002105
Blood in cough due to airway damage
Fixed Airflow Obstruction FREQUENT Chronic pulmonary obstruction HP:0006510
Progressive airflow limitation that may develop in bronchiectasis patients, associated with Proteobacteria-enriched microbiome
Show evidence (1 reference)
DOI:10.1186/s12931-024-02931-x SUPPORT Human Clinical
"compared to COPD and bronchiectasis without FAO, bronchiectasis with FAO showed more severe disease and a higher risk of exacerbations."
Direct evidence that fixed airflow obstruction is a clinically relevant phenotype in bronchiectasis with worse outcomes.
Wheezing OCCASIONAL Wheezing HP:0030828
🧬

Genetic Associations

2
CFTR (Modifier gene)
SCNN1A (Modifier gene)
💊

Medical Actions

8
Airway Clearance Techniques
Action: physical therapy MAXO:0000011
Physical therapies to enhance mucus clearance, such as chest physiotherapy.
Antibiotic Therapy
Action: antibiotic therapy Ontology label: Antibiotic Therapy NCIT:C15620
Used to treat and prevent bacterial infections in the airways.
Long-term Macrolide Therapy
Action: Pharmacotherapy NCIT:C15986
Agent: azithromycin CHEBI:2955 erythromycin CHEBI:48923
Maintenance macrolide antibiotics such as azithromycin or erythromycin reduce pulmonary exacerbations in selected patients, while requiring attention to macrolide resistance risk.
Show evidence (2 references)
PMID:22901887 SUPPORT Human Clinical
"Azithromycin is a new option for prevention of exacerbations in patients with non-cystic fibrosis bronchiectasis with a history of at least one exacerbation in the past year."
EMBRACE was a randomized, double-blind, placebo-controlled trial supporting azithromycin for exacerbation prevention.
PMID:23532242 SUPPORT Human Clinical
"Among patients with non-CF bronchiectasis, the 12-month use of erythromycin compared with placebo resulted in a modest decrease in the rate of pulmonary exacerbations and an increased rate of macrolide resistance."
BLESS supports long-term macrolide therapy reducing exacerbations while also documenting resistance risk.
Brensocatib
Action: Pharmacotherapy NCIT:C15986
Oral reversible dipeptidyl peptidase 1 inhibitor that reduces neutrophil serine protease activity and pulmonary exacerbations.
Mechanism Target:
INHIBITS Protease-Antiprotease Imbalance — Brensocatib inhibits DPP-1, targeting neutrophil serine proteases that drive the protease-antiprotease imbalance.
Show evidence (1 reference)
PMID:40267423 SUPPORT Human Clinical
"Brensocatib, an oral, reversible inhibitor of dipeptidyl peptidase 1 (DPP-1), targets neutrophil serine proteases, key mediators of neutrophilic inflammation."
The ASPEN trial abstract describes brensocatib's DPP-1 inhibition as targeting neutrophil serine proteases.
Show evidence (1 reference)
PMID:40267423 SUPPORT Human Clinical
"Among patients with bronchiectasis, once-daily treatment with brensocatib (10 mg or 25 mg) led to a lower annualized rate of pulmonary exacerbations than placebo, and the decline in FEV1 was less with the 25-mg dose of brensocatib than with placebo."
ASPEN was a phase 3, double-blind trial demonstrating reduced pulmonary exacerbations with once-daily brensocatib.
Bronchodilators
Action: bronchodilator therapy MAXO:0000316
Medications to open airways and improve breathing.
Inhaled Corticosteroids
Action: respiratory tract agent therapy MAXO:0000312
Reduce inflammation in the airways.
Surgery
Action: surgical procedure MAXO:0000004
Rarely performed; may include removal of severely affected lung areas if localized and recurrent infections persist.
Vaccinations
Action: vaccination MAXO:0001017
Prevent respiratory infections and exacerbations.
🌍

Environmental Factors

2
Pollution
Air pollution exposure ECTO:8000036
May worsen symptoms and progression.
Smoking
Tobacco smoking exposure ECTO:6000029
Exacerbates lung damage and symptoms.
🔬

Biochemical Markers

5
C-Reactive Protein (CRP) (Elevated)
Context: Indicates active inflammation and infection
Sputum Culture (Positive)
Context: Identification of pathogenic organisms
Neutrophil Elastase (NE) (Elevated)
Context: High sputum NE activity associates with severe bronchiectasis, exacerbation risk, airway bacterial load, and disease progression; mechanistic biomarker of neutrophil-driven inflammation
Show evidence (1 reference)
DOI:10.1055/s-0041-1730891 SUPPORT Human Clinical
"Neutrophilic inflammation is characteristic of the disease, with elevated levels of harmful proteases such as neutrophil elastase associated with worse outcomes."
Supports elevated neutrophil elastase as a biomarker linked to worse outcomes in bronchiectasis.
Interleukin-1 beta (IL-1beta) (Elevated)
Context: Subset of patients with high airway IL-1beta show severe disease, mucus hyperconcentration, impaired ciliary function, and Proteobacteria-enriched microbiome
Show evidence (1 reference)
DOI:10.1183/13993003.01966-2023 SUPPORT Human Clinical
"Patients with high sputum IL-1β had more severe disease, increased caspase-1 activity and an increased T-helper type 1, T-helper type 2 and neutrophil inflammatory response compared with patients with low IL-1β."
Cohort study links elevated airway IL-1beta to greater severity and amplified inflammatory response.
Neutrophil Extracellular Traps (NETs) (Elevated)
Context: NET complexes in sputum associate with higher disease severity, exacerbations, and mortality; include MPO, NE, resistin, and azurocidin
{ }

Source YAML

click to show
name: Bronchiectasis
creation_date: '2025-12-04T16:57:31Z'
updated_date: '2026-04-26T23:00:50Z'
category: Respiratory Disease
description: >-
  Bronchiectasis is a chronic respiratory disease characterized by permanent, abnormal
  dilation and thickening of the bronchi resulting from a self-perpetuating cycle of airway
  infection, inflammation, impaired mucociliary clearance, and progressive structural lung
  damage (the so-called vicious vortex). It may be idiopathic or arise secondary to prior
  severe respiratory infection, cystic fibrosis, primary ciliary dyskinesia, immunodeficiency,
  allergic bronchopulmonary aspergillosis, or chronic obstructive airway disease. Affected
  individuals experience chronic productive cough, recurrent respiratory infections, and
  progressive airflow obstruction, with acute exacerbations driving stepwise decline in lung
  function.
parents:
- Chronic Lung Disease
- Inflammatory Lung Disease
prevalence:
- population: Adults
  percentage: Unknown
- population: Children
  percentage: Unknown
progression:
- phase: Onset
  age_range: Childhood to Adulthood
pathophysiology:
- name: Chronic Infection and Inflammation
  description: Persistent microbial infections and inflammation damage airway
    walls, leading to dilation and thickening.
  evidence:
  - reference: DOI:10.1183/16000617.0055-2024
    reference_title: 'Pathophysiology and genomics of bronchiectasis'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The presence of airway infection together with chronic inflammation,
      airway mucociliary dysfunction and lung damage are key components of the
      vicious vortex model that better describes its pathophysiology.
    explanation: Vicious vortex model centers on chronic infection plus
      inflammation as the core pathophysiology of bronchiectasis.
  downstream:
  - target: Airway Dilation
- name: Airway Dilation
  description: Destruction of elastin and cartilage in the bronchial walls causes irreversible dilation of bronchi.
  downstream:
  - target: Impaired Mucociliary Clearance
  - target: Fixed Airflow Obstruction
    description: Irreversible structural destruction and dilation of the bronchial
      walls produces the progressive, fixed airflow limitation seen in
      bronchiectasis.
  - target: Dyspnea
    description: Airway structural damage and airflow limitation manifest
      clinically as breathlessness.
  - target: Wheezing
    description: Distorted, dilated airways and luminal narrowing during airflow
      produce wheeze.
  - target: Hemoptysis
    description: Bronchial wall destruction with hypertrophied, fragile bronchial
      arteries predisposes to airway bleeding.
- name: Impaired Mucociliary Clearance
  description: Damage and dilation of airways hinder effective clearance of mucus, allowing for accumulation and further infection.
  downstream:
  - target: Recurrent Respiratory Infections
    description: Failure to clear mucus and trapped microbes permits persistent
      and recurrent airway infection.
  - target: Chronic Cough
    description: Retained, hyperconcentrated airway secretions stimulate the cough
      reflex.
  cell_types:
  - preferred_term: airway epithelial cell
    term:
      id: CL:0002368
      label: respiratory tract epithelial cell
  - preferred_term: ciliated epithelial cell
    term:
      id: CL:0000067
      label: ciliated epithelial cell
  biological_processes:
  - preferred_term: mucociliary clearance
    term:
      id: GO:0003351
      label: epithelial cilium movement involved in extracellular fluid movement
  - preferred_term: cilium movement
    term:
      id: GO:0003341
      label: cilium movement
  locations:
  - preferred_term: bronchus
    term:
      id: UBERON:0002185
      label: bronchus
- name: Neutrophil-Driven Inflammation
  description: Excessive neutrophil recruitment, degranulation, and NET
    formation release proteases (neutrophil elastase, proteinase 3, cathepsin G)
    that degrade extracellular matrix, impair ciliary function, and damage
    epithelial barriers.
  downstream:
  - target: Protease-Antiprotease Imbalance
    description: Excessive neutrophil serine protease release overwhelms airway
      antiproteases, establishing the protease-antiprotease imbalance.
  evidence:
  - reference: DOI:10.1183/16000617.0179-2024
    reference_title: 'Neutrophilic inflammation in bronchiectasis'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The excessive release of neutrophil serine proteases, such as
      neutrophil elastase, cathepsin G and proteinase 3, promotes a
      protease–antiprotease imbalance that correlates with increased inflammation
      in bronchiectasis and contributes to disease progression.
    explanation: Direct evidence that neutrophil serine proteases drive
      inflammation and disease progression in bronchiectasis.
  - reference: DOI:10.1055/s-0041-1730891
    reference_title: 'Pathophysiology of Bronchiectasis'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Recent data show that neutrophil extracellular trap formation may be
      the key mechanism leading to protease release and severe bronchiectasis.
    explanation: Supports NET formation as a key mechanism for protease release
      and disease severity.
  cell_types:
  - preferred_term: neutrophil
    term:
      id: CL:0000775
      label: neutrophil
  biological_processes:
  - preferred_term: neutrophil degranulation
    term:
      id: GO:0043312
      label: neutrophil degranulation
  - preferred_term: neutrophil extracellular trap formation
    term:
      id: GO:0140645
      label: neutrophil extracellular trap formation
  - preferred_term: inflammatory response
    term:
      id: GO:0006954
      label: inflammatory response
  locations:
  - preferred_term: bronchus
    term:
      id: UBERON:0002185
      label: bronchus
  - preferred_term: extracellular space
    term:
      id: GO:0005576
      label: extracellular region
- name: Protease-Antiprotease Imbalance
  description: Excess neutrophil serine proteases (NE, PR3, CatG) overwhelm
    antiproteases (SLPI, A1AT), degrading structural proteins and perpetuating
    tissue damage.
  downstream:
  - target: Airway Dilation
    description: Protease-driven destruction of airway-wall elastin and collagen
      drives the irreversible bronchial dilation.
  evidence:
  - reference: DOI:10.1183/16000617.0179-2024
    reference_title: 'Neutrophilic inflammation in bronchiectasis'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The excessive release of neutrophil serine proteases, such as
      neutrophil elastase, cathepsin G and proteinase 3, promotes a
      protease–antiprotease imbalance that correlates with increased inflammation
      in bronchiectasis and contributes to disease progression.
    explanation: Directly supports protease-antiprotease imbalance as a
      neutrophil serine protease-driven mechanism linked to inflammation and
      bronchiectasis progression.
  biological_processes:
  - preferred_term: proteolysis
    term:
      id: GO:0006508
      label: proteolysis
  locations:
  - preferred_term: extracellular space
    term:
      id: GO:0005576
      label: extracellular region
- name: Goblet Cell Hyperplasia and Mucus Hypersecretion
  description: Increased goblet cell numbers and overproduction of gel-forming
    mucins (MUC5AC, MUC5B) lead to mucus hyperconcentration and impaired
    clearance.
  downstream:
  - target: Sputum Production
    description: Overproduction of gel-forming mucins generates the copious,
      often purulent sputum characteristic of bronchiectasis.
  - target: Chronic Cough
    description: Excess airway mucus stimulates the cough reflex, producing the
      productive chronic cough.
  evidence:
  - reference: DOI:10.1055/s-0041-1730891
    reference_title: 'Pathophysiology of Bronchiectasis'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Mucus symptoms arise through goblet cell hyperplasia and metaplasia
      and reduced ciliary function through dyskinesia and loss of ciliated cells.
    explanation: Direct support for goblet cell hyperplasia as a source of mucus
      symptoms in bronchiectasis.
  cell_types:
  - preferred_term: goblet cell
    term:
      id: CL:0000160
      label: goblet cell
  biological_processes:
  - preferred_term: mucus secretion
    term:
      id: GO:0070254
      label: mucus secretion
  locations:
  - preferred_term: bronchus
    term:
      id: UBERON:0002185
      label: bronchus
- name: Inflammasome Activation and IL-1beta Signaling
  description: NLRP3 inflammasome activation drives IL-1beta production, which
    directly impairs ciliary function, disrupts tight junctions, promotes mucus
    hyperconcentration, and is associated with severe disease and Proteobacteria
    enrichment.
  evidence:
  - reference: DOI:10.1183/13993003.01966-2023
    reference_title: 'Airway IL-1β is related to disease severity and mucociliary function in bronchiectasis'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: A subset of stable bronchiectasis patients show increased airway
      IL-1β, suggesting pulmonary inflammasome activation is linked with more
      severe disease, airway infection, mucus dehydration and epithelial
      dysfunction.
    explanation: Cohort study (n=269) directly links airway IL-1beta to
      inflammasome activation, severity, and epithelial dysfunction.
  - reference: DOI:10.1183/13993003.01966-2023
    reference_title: 'Airway IL-1β is related to disease severity and mucociliary function in bronchiectasis'
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Chronic IL-1β treatment reduced the functionality of cilia and
      tight junctions of epithelial cells
    explanation: In vitro mechanistic evidence that IL-1beta directly impairs
      ciliary and tight-junction function in airway epithelial cells.
  biological_processes:
  - preferred_term: interleukin-1 beta production
    term:
      id: GO:0032611
      label: interleukin-1 beta production
  cellular_components:
  - preferred_term: NLRP3 inflammasome complex
    term:
      id: GO:0072559
      label: NLRP3 inflammasome complex
  cell_types:
  - preferred_term: airway epithelial cell
    term:
      id: CL:0002368
      label: respiratory tract epithelial cell
  locations:
  - preferred_term: bronchus
    term:
      id: UBERON:0002185
      label: bronchus
- name: Microbiome Dysbiosis
  description: Reduced microbial diversity with Proteobacteria dominance,
    particularly Pseudomonas aeruginosa and Haemophilus influenzae, drives
    chronic infection, exacerbations, and disease progression.
  downstream:
  - target: Recurrent Respiratory Infections
    description: Proteobacteria-dominant dysbiosis with persistent pathogen
      colonization drives chronic and recurrent airway infection.
  evidence:
  - reference: DOI:10.1055/s-0041-1730891
    reference_title: 'Pathophysiology of Bronchiectasis'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Loss of diversity of the normal lung microbiota and dominance of
      proteobacteria such as Pseudomonas and Haemophilus are features of severe
      bronchiectasis and link to poor outcomes.
    explanation: Direct support for Proteobacteria dominance as a feature of
      severe disease.
  - reference: DOI:10.1186/s12931-024-02931-x
    reference_title: 'The clinical impacts of lung microbiome in bronchiectasis with fixed airflow obstruction: a prospective cohort study'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Patients with bronchiectasis, with or without FAO, had similar
      microbiome profiles characterized by reduced alpha diversity and a
      predominance of Proteobacteria
    explanation: Confirms reduced alpha diversity and Proteobacteria predominance
      via 16S rRNA sequencing of BAL samples.
  locations:
  - preferred_term: bronchus
    term:
      id: UBERON:0002185
      label: bronchus
  - preferred_term: respiratory tract mucus
    term:
      id: UBERON:0000912
      label: mucus
genetic:
- name: CFTR
  association: Modifier gene
  notes: CFTR ion channel dysfunction contributes to airway surface liquid dehydration and mucus abnormalities in non-CF bronchiectasis, though the role is debated.
- name: SCNN1A
  association: Modifier gene
  notes: ENaC (epithelial sodium channel) alpha subunit; hyperactivity causes airway surface dehydration and increased mucus viscosity, impairing mucociliary clearance.
phenotypes:
- category: Respiratory
  name: Chronic Cough
  frequency: VERY_FREQUENT
  diagnostic: true
  phenotype_term:
    preferred_term: Chronic Cough
    term:
      id: HP:0034315
      label: Chronic cough
  evidence:
  - reference: DOI:10.1183/16000617.0179-2024
    reference_title: 'Neutrophilic inflammation in bronchiectasis'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Patients with clinically significant bronchiectasis have chronic
      cough and sputum production, as well as recurrent respiratory infections,
      fatigue and impaired health-related quality of life.
    explanation: Chronic cough is a defining clinical feature of bronchiectasis.
- category: Respiratory
  name: Sputum Production
  frequency: VERY_FREQUENT
  notes: Often purulent and copious
  phenotype_term:
    preferred_term: Sputum Production
    term:
      id: HP:0033709
      label: Increased sputum production
  evidence:
  - reference: DOI:10.1183/16000617.0179-2024
    reference_title: 'Neutrophilic inflammation in bronchiectasis'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Patients with clinically significant bronchiectasis have chronic
      cough and sputum production, as well as recurrent respiratory infections,
      fatigue and impaired health-related quality of life.
    explanation: Sputum production is a defining clinical feature of
      bronchiectasis.
- category: Respiratory
  name: Dyspnea
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Dyspnea
    term:
      id: HP:0002094
      label: Dyspnea
- category: Respiratory
  name: Hemoptysis
  frequency: OCCASIONAL
  notes: Blood in cough due to airway damage
  phenotype_term:
    preferred_term: Hemoptysis
    term:
      id: HP:0002105
      label: Hemoptysis
- category: Respiratory
  name: Recurrent Respiratory Infections
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Recurrent Respiratory Infections
    term:
      id: HP:0002205
      label: Recurrent respiratory infections
  evidence:
  - reference: DOI:10.1183/16000617.0179-2024
    reference_title: 'Neutrophilic inflammation in bronchiectasis'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Patients with clinically significant bronchiectasis have chronic
      cough and sputum production, as well as recurrent respiratory infections,
      fatigue and impaired health-related quality of life.
    explanation: Recurrent respiratory infections are a hallmark clinical feature
      of bronchiectasis.
- category: Respiratory
  name: Fixed Airflow Obstruction
  frequency: FREQUENT
  notes: Progressive airflow limitation that may develop in bronchiectasis patients, associated with Proteobacteria-enriched microbiome
  phenotype_term:
    preferred_term: Chronic pulmonary obstruction
    term:
      id: HP:0006510
      label: Chronic pulmonary obstruction
  evidence:
  - reference: DOI:10.1186/s12931-024-02931-x
    reference_title: 'The clinical impacts of lung microbiome in bronchiectasis with fixed airflow obstruction: a prospective cohort study'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: compared to COPD and bronchiectasis without FAO, bronchiectasis with
      FAO showed more severe disease and a higher risk of exacerbations.
    explanation: Direct evidence that fixed airflow obstruction is a clinically
      relevant phenotype in bronchiectasis with worse outcomes.
- category: Respiratory
  name: Wheezing
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Wheezing
    term:
      id: HP:0030828
      label: Wheezing
biochemical:
- name: C-Reactive Protein (CRP)
  presence: Elevated
  context: Indicates active inflammation and infection
- name: Sputum Culture
  presence: Positive
  context: Identification of pathogenic organisms
- name: Neutrophil Elastase (NE)
  presence: Elevated
  context: High sputum NE activity associates with severe bronchiectasis,
    exacerbation risk, airway bacterial load, and disease progression;
    mechanistic biomarker of neutrophil-driven inflammation
  evidence:
  - reference: DOI:10.1055/s-0041-1730891
    reference_title: 'Pathophysiology of Bronchiectasis'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Neutrophilic inflammation is characteristic of the disease, with
      elevated levels of harmful proteases such as neutrophil elastase associated
      with worse outcomes.
    explanation: Supports elevated neutrophil elastase as a biomarker linked to
      worse outcomes in bronchiectasis.
- name: Interleukin-1 beta (IL-1beta)
  presence: Elevated
  context: Subset of patients with high airway IL-1beta show severe disease,
    mucus hyperconcentration, impaired ciliary function, and
    Proteobacteria-enriched microbiome
  evidence:
  - reference: DOI:10.1183/13993003.01966-2023
    reference_title: 'Airway IL-1β is related to disease severity and mucociliary function in bronchiectasis'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Patients with high sputum IL-1β had more severe disease, increased
      caspase-1 activity and an increased T-helper type 1, T-helper type 2 and
      neutrophil inflammatory response compared with patients with low IL-1β.
    explanation: Cohort study links elevated airway IL-1beta to greater severity
      and amplified inflammatory response.
- name: Neutrophil Extracellular Traps (NETs)
  presence: Elevated
  context: NET complexes in sputum associate with higher disease severity, exacerbations, and mortality; include MPO, NE, resistin, and azurocidin
diagnosis:
- name: High-Resolution CT Scan
  notes: Reveals dilated bronchi and other structural changes typical of bronchiectasis.
- name: Pulmonary Function Test
  notes: May indicate obstructive pattern due to airway dilation.
treatments:
- name: Airway Clearance Techniques
  description: Physical therapies to enhance mucus clearance, such as chest physiotherapy.
  treatment_term:
    preferred_term: physical therapy
    term:
      id: MAXO:0000011
      label: physical therapy
- name: Antibiotic Therapy
  description: Used to treat and prevent bacterial infections in the airways.
  treatment_term:
    preferred_term: antibiotic therapy
    term:
      id: NCIT:C15620
      label: Antibiotic Therapy
- name: Long-term Macrolide Therapy
  description: Maintenance macrolide antibiotics such as azithromycin or
    erythromycin reduce pulmonary exacerbations in selected patients, while
    requiring attention to macrolide resistance risk.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: azithromycin
      term:
        id: CHEBI:2955
        label: azithromycin
    - preferred_term: erythromycin
      term:
        id: CHEBI:48923
        label: erythromycin
  evidence:
  - reference: PMID:22901887
    reference_title: 'Azithromycin for prevention of exacerbations in non-cystic fibrosis bronchiectasis (EMBRACE): a randomised, double-blind, placebo-controlled trial.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Azithromycin is a new option for prevention of exacerbations in
      patients with non-cystic fibrosis bronchiectasis with a history of at
      least one exacerbation in the past year.
    explanation: EMBRACE was a randomized, double-blind, placebo-controlled
      trial supporting azithromycin for exacerbation prevention.
  - reference: PMID:23532242
    reference_title: 'Effect of long-term, low-dose erythromycin on pulmonary exacerbations among patients with non-cystic fibrosis bronchiectasis: the BLESS randomized controlled trial.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Among patients with non-CF bronchiectasis, the 12-month use of
      erythromycin compared with placebo resulted in a modest decrease in the
      rate of pulmonary exacerbations and an increased rate of macrolide
      resistance.
    explanation: BLESS supports long-term macrolide therapy reducing
      exacerbations while also documenting resistance risk.
- name: Brensocatib
  description: Oral reversible dipeptidyl peptidase 1 inhibitor that reduces
    neutrophil serine protease activity and pulmonary exacerbations.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
  target_mechanisms:
  - target: Protease-Antiprotease Imbalance
    treatment_effect: INHIBITS
    description: Brensocatib inhibits DPP-1, targeting neutrophil serine
      proteases that drive the protease-antiprotease imbalance.
    evidence:
    - reference: PMID:40267423
      reference_title: 'Phase 3 Trial of the DPP-1 Inhibitor Brensocatib in Bronchiectasis.'
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Brensocatib, an oral, reversible inhibitor of dipeptidyl peptidase
        1 (DPP-1), targets neutrophil serine proteases, key mediators of
        neutrophilic inflammation.
      explanation: The ASPEN trial abstract describes brensocatib's DPP-1
        inhibition as targeting neutrophil serine proteases.
  evidence:
  - reference: PMID:40267423
    reference_title: 'Phase 3 Trial of the DPP-1 Inhibitor Brensocatib in Bronchiectasis.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Among patients with bronchiectasis, once-daily treatment with
      brensocatib (10 mg or 25 mg) led to a lower annualized rate of pulmonary
      exacerbations than placebo, and the decline in FEV1 was less with the
      25-mg dose of brensocatib than with placebo.
    explanation: ASPEN was a phase 3, double-blind trial demonstrating reduced
      pulmonary exacerbations with once-daily brensocatib.
- name: Bronchodilators
  description: Medications to open airways and improve breathing.
  treatment_term:
    preferred_term: bronchodilator therapy
    term:
      id: MAXO:0000316
      label: bronchodilator therapy
- name: Inhaled Corticosteroids
  description: Reduce inflammation in the airways.
  treatment_term:
    preferred_term: respiratory tract agent therapy
    term:
      id: MAXO:0000312
      label: respiratory tract agent therapy
- name: Surgery
  description: Rarely performed; may include removal of severely affected lung areas if localized and recurrent infections persist.
  treatment_term:
    preferred_term: surgical procedure
    term:
      id: MAXO:0000004
      label: surgical procedure
- name: Vaccinations
  description: Prevent respiratory infections and exacerbations.
  treatment_term:
    preferred_term: vaccination
    term:
      id: MAXO:0001017
      label: vaccination
environmental:
- name: Pollution
  notes: May worsen symptoms and progression.
  exposure_term:
    preferred_term: Air pollution exposure
    term:
      id: ECTO:8000036
      label: exposure to air pollution
- name: Smoking
  notes: Exacerbates lung damage and symptoms.
  exposure_term:
    preferred_term: Tobacco smoking exposure
    term:
      id: ECTO:6000029
      label: exposure to tobacco smoking
notes: Bronchiectasis is characterized by a self-sustaining "vicious vortex" of mucociliary dysfunction, persistent infection with Proteobacteria-dominant dysbiosis (notably Pseudomonas aeruginosa), and chronic neutrophil-driven inflammation. Neutrophils release proteases (NE, PR3, CatG) and form NETs that degrade extracellular matrix, impair ciliary function, and damage epithelial barriers. Inflammasome activation with airway IL-1beta is associated with severe disease, mucus hyperconcentration, and epithelial dysfunction. The disease leads to irreversible bronchial dilation and progressive airflow limitation.
disease_term:
  preferred_term: bronchiectasis
  term:
    id: MONDO:0004822
    label: bronchiectasis
classifications:
  harrisons_chapter:
  - classification_value: RESPIRATORY
references:
- reference: DOI:10.1055/s-0041-1730891
  title: Pathophysiology of Bronchiectasis
  findings: []
- reference: DOI:10.1164/rccm.202306-1059oc
  title: Airway “Resistotypes” and Clinical Outcomes in Bronchiectasis
  findings: []
- reference: DOI:10.1183/13993003.01689-2023
  title: 'Airway clearance management in people with bronchiectasis: data from the European Bronchiectasis Registry (EMBARC)'
  findings: []
- reference: DOI:10.1183/13993003.01966-2023
  title: Airway IL-1β is related to disease severity and mucociliary function in bronchiectasis
  findings: []
- reference: DOI:10.1183/16000617.0038-2024
  title: Infection and the microbiome in bronchiectasis
  findings: []
- reference: DOI:10.1183/16000617.0055-2024
  title: Pathophysiology and genomics of bronchiectasis
  findings: []
- reference: DOI:10.1183/16000617.0179-2024
  title: Neutrophilic inflammation in bronchiectasis
  findings: []
- reference: DOI:10.1183/16000617.0234-2023
  title: Biomarkers in bronchiectasis
  findings: []
- reference: DOI:10.1186/s12931-024-02931-x
  title: 'The clinical impacts of lung microbiome in bronchiectasis with fixed airflow obstruction: a prospective cohort study'
  findings: []
- reference: PMID:22901887
  title: 'Azithromycin for prevention of exacerbations in non-cystic fibrosis
    bronchiectasis (EMBRACE): a randomised, double-blind, placebo-controlled
    trial.'
  findings: []
- reference: PMID:23532242
  title: 'Effect of long-term, low-dose erythromycin on pulmonary exacerbations
    among patients with non-cystic fibrosis bronchiectasis: the BLESS randomized
    controlled trial.'
  findings: []
- reference: PMID:40267423
  title: Phase 3 Trial of the DPP-1 Inhibitor Brensocatib in Bronchiectasis.
  findings: []
📚

References & Deep Research

References

12
Pathophysiology of Bronchiectasis
No top-level findings curated for this source.
Airway “Resistotypes” and Clinical Outcomes in Bronchiectasis
No top-level findings curated for this source.
Airway clearance management in people with bronchiectasis: data from the European Bronchiectasis Registry (EMBARC)
No top-level findings curated for this source.
Airway IL-1β is related to disease severity and mucociliary function in bronchiectasis
No top-level findings curated for this source.
Infection and the microbiome in bronchiectasis
No top-level findings curated for this source.
Pathophysiology and genomics of bronchiectasis
No top-level findings curated for this source.
Neutrophilic inflammation in bronchiectasis
No top-level findings curated for this source.
Biomarkers in bronchiectasis
No top-level findings curated for this source.
The clinical impacts of lung microbiome in bronchiectasis with fixed airflow obstruction: a prospective cohort study
No top-level findings curated for this source.
Azithromycin for prevention of exacerbations in non-cystic fibrosis bronchiectasis (EMBRACE): a randomised, double-blind, placebo-controlled trial.
No top-level findings curated for this source.
Effect of long-term, low-dose erythromycin on pulmonary exacerbations among patients with non-cystic fibrosis bronchiectasis: the BLESS randomized controlled trial.
No top-level findings curated for this source.
Phase 3 Trial of the DPP-1 Inhibitor Brensocatib in Bronchiectasis.
No top-level findings curated for this source.

Deep Research

2
Disorder

Disorder

  • Name: Bronchiectasis
  • Category: Respiratory Disease
  • Existing deep-research providers: falcon
  • Existing evidence reference count in YAML: 9

Key Pathophysiology Nodes

  • Chronic Infection and Inflammation
  • Airway Dilation
  • Impaired Mucociliary Clearance
  • Neutrophil-Driven Inflammation
  • Protease-Antiprotease Imbalance
  • Goblet Cell Hyperplasia and Mucus Hypersecretion
  • Inflammasome Activation and IL-1beta Signaling
  • Microbiome Dysbiosis
  • Deep research literature mapping

Citation Inventory (for evidence mapping)

  • DOI:10.1055/s-0041-1730891
  • DOI:10.1164/rccm.202306-1059oc
  • DOI:10.1183/13993003.01689-2023
  • DOI:10.1183/13993003.01966-2023
  • DOI:10.1183/16000617.0038-2024
  • DOI:10.1183/16000617.0055-2024
  • DOI:10.1183/16000617.0179-2024
  • DOI:10.1183/16000617.0234-2023
  • DOI:10.1186/s12931-024-02931-x
Falcon
Pathophysiology description (concise knowledge-base narrative)
Edison Scientific Literature 35 citations 2025-12-15T09:10:49.051530

Pathophysiology description (concise knowledge-base narrative) Non‑CF bronchiectasis arises from a self-sustaining “vicious vortex” of mucociliary dysfunction, persistent infection with Proteobacteria-dominant dysbiosis (notably Pseudomonas aeruginosa), and chronic neutrophil-driven inflammation that releases proteases and NETs, injuring the epithelium and altering mucus rheology, thereby worsening clearance and perpetuating infection. Inflammasome activation with airway IL‑1β links to higher severity, mucus hyperconcentration, epithelial barrier dysfunction, and Proteobacteria enrichment. Excess NSP activity (NE, PR3, CatG) over antiproteases is a causative axis, validated by clinical benefit of DPP‑1 inhibition that reduces airway protease activity and exacerbations. Clinically, frequent exacerbators and those with chronic P. aeruginosa have worse outcomes; airway clearance use remains suboptimal despite guideline recommendations (keir2021pathophysiologyofbronchiectasis pages 2-2, perea2024pathophysiologyandgenomics pages 2-3, aogain2024infectionandthe pages 1-2, johnson2024biomarkersinbronchiectasis pages 1-2, johnson2024biomarkersinbronchiectasis pages 3-4, aogain2024infectionandthe pages 6-7, chen2024theclinicalimpacts pages 1-2).

References

  1. (keir2021pathophysiologyofbronchiectasis pages 2-2): Holly R. Keir and James D. Chalmers. Pathophysiology of bronchiectasis. Seminars in Respiratory and Critical Care Medicine, 42:499-512, Jul 2021. URL: https://doi.org/10.1055/s-0041-1730891, doi:10.1055/s-0041-1730891. This article has 81 citations and is from a peer-reviewed journal.

  2. (keir2021pathophysiologyofbronchiectasis pages 1-2): Holly R. Keir and James D. Chalmers. Pathophysiology of bronchiectasis. Seminars in Respiratory and Critical Care Medicine, 42:499-512, Jul 2021. URL: https://doi.org/10.1055/s-0041-1730891, doi:10.1055/s-0041-1730891. This article has 81 citations and is from a peer-reviewed journal.

  3. (chalmers2025neutrophilicinflammationin pages 1-2): James D. Chalmers, Mark Metersky, Stefano Aliberti, Lucy Morgan, Sebastian Fucile, Melanie Lauterio, and Patrick P. McDonald. Neutrophilic inflammation in bronchiectasis. European Respiratory Review, 34:240179, Apr 2025. URL: https://doi.org/10.1183/16000617.0179-2024, doi:10.1183/16000617.0179-2024. This article has 20 citations and is from a peer-reviewed journal.

  4. (perea2024pathophysiologyandgenomics pages 2-3): Lidia Perea, Rosa Faner, James D. Chalmers, and Oriol Sibila. Pathophysiology and genomics of bronchiectasis. European Respiratory Review, 33:240055, Jul 2024. URL: https://doi.org/10.1183/16000617.0055-2024, doi:10.1183/16000617.0055-2024. This article has 29 citations and is from a peer-reviewed journal.

  5. (keir2021pathophysiologyofbronchiectasis pages 3-4): Holly R. Keir and James D. Chalmers. Pathophysiology of bronchiectasis. Seminars in Respiratory and Critical Care Medicine, 42:499-512, Jul 2021. URL: https://doi.org/10.1055/s-0041-1730891, doi:10.1055/s-0041-1730891. This article has 81 citations and is from a peer-reviewed journal.

  6. (keir2021pathophysiologyofbronchiectasis pages 2-3): Holly R. Keir and James D. Chalmers. Pathophysiology of bronchiectasis. Seminars in Respiratory and Critical Care Medicine, 42:499-512, Jul 2021. URL: https://doi.org/10.1055/s-0041-1730891, doi:10.1055/s-0041-1730891. This article has 81 citations and is from a peer-reviewed journal.

  7. (aogain2024infectionandthe pages 1-2): Micheál Mac Aogáin, Alison J. Dicker, Pontus Mertsch, and Sanjay H. Chotirmall. Infection and the microbiome in bronchiectasis. European Respiratory Review, 33:240038, Jul 2024. URL: https://doi.org/10.1183/16000617.0038-2024, doi:10.1183/16000617.0038-2024. This article has 24 citations and is from a peer-reviewed journal.

  8. (aogain2024infectionandthe pages 4-5): Micheál Mac Aogáin, Alison J. Dicker, Pontus Mertsch, and Sanjay H. Chotirmall. Infection and the microbiome in bronchiectasis. European Respiratory Review, 33:240038, Jul 2024. URL: https://doi.org/10.1183/16000617.0038-2024, doi:10.1183/16000617.0038-2024. This article has 24 citations and is from a peer-reviewed journal.

  9. (aogain2024infectionandthe pages 6-7): Micheál Mac Aogáin, Alison J. Dicker, Pontus Mertsch, and Sanjay H. Chotirmall. Infection and the microbiome in bronchiectasis. European Respiratory Review, 33:240038, Jul 2024. URL: https://doi.org/10.1183/16000617.0038-2024, doi:10.1183/16000617.0038-2024. This article has 24 citations and is from a peer-reviewed journal.

  10. (chen2024theclinicalimpacts pages 1-2): Yen-Fu Chen, Hsin-Han Hou, Ning Chien, Kai-Zen Lu, Chieh-Hua Lin, Yu-Chieh Liao, Kuo-Lung Lor, Jung-Yien Chien, Chung-Ming Chen, Chung-Yu Chen, Shih-Lung Cheng, Hao-Chien Wang, Po-Ren Hsueh, and Chong-Jen Yu. The clinical impacts of lung microbiome in bronchiectasis with fixed airflow obstruction: a prospective cohort study. Respiratory Research, Aug 2024. URL: https://doi.org/10.1186/s12931-024-02931-x, doi:10.1186/s12931-024-02931-x. This article has 6 citations and is from a domain leading peer-reviewed journal.

  11. (johnson2024biomarkersinbronchiectasis pages 3-4): Emma D Johnson, Merete B. Long, and James D. Chalmers. Biomarkers in bronchiectasis. European Respiratory Review, 33:230234, Jul 2024. URL: https://doi.org/10.1183/16000617.0234-2023, doi:10.1183/16000617.0234-2023. This article has 17 citations and is from a peer-reviewed journal.

  12. (chalmers2025neutrophilicinflammationin pages 9-10): James D. Chalmers, Mark Metersky, Stefano Aliberti, Lucy Morgan, Sebastian Fucile, Melanie Lauterio, and Patrick P. McDonald. Neutrophilic inflammation in bronchiectasis. European Respiratory Review, 34:240179, Apr 2025. URL: https://doi.org/10.1183/16000617.0179-2024, doi:10.1183/16000617.0179-2024. This article has 20 citations and is from a peer-reviewed journal.

  13. (johnson2024biomarkersinbronchiectasis pages 1-2): Emma D Johnson, Merete B. Long, and James D. Chalmers. Biomarkers in bronchiectasis. European Respiratory Review, 33:230234, Jul 2024. URL: https://doi.org/10.1183/16000617.0234-2023, doi:10.1183/16000617.0234-2023. This article has 17 citations and is from a peer-reviewed journal.