Bronchiectasis

name: Bronchiectasis
creation_date: '2025-12-04T16:57:31Z'
updated_date: '2026-02-17T21:53:14Z'
category: Respiratory Disease
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.
  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
- name: Impaired Mucociliary Clearance
  description: Damage and dilation of airways hinder effective clearance of
    mucus, allowing for accumulation and further infection.
  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.
  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.
  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.
  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.
  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.
  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
- 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
- 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
- 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
- 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
- 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
- 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: pharmacotherapy
    term:
      id: MAXO:0000058
      label: pharmacotherapy
- name: Bronchodilators
  description: Medications to open airways and improve breathing.
  treatment_term:
    preferred_term: pharmacotherapy
    term:
      id: MAXO:0000058
      label: pharmacotherapy
- 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 system disorder
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: []