What causes bronchiectasis?
There are numerous causes for bronchiectasis. However, in approximately 50% of cases, an underlying cause is not found (King et al 2006). In these cases the disease is often found in the lower lobes. It is likely though that “ideopathic” bronchiectasis is relatively rare but there are not currently robust or readily available tests of many subtle abnormalities of immune function for the many of these cases to be classified.
It is ideal to identify the cause of bronchiectasis where possible, to target appropriate disease management strategies. These strategies may be associated with reducing the progression of bronchiectasis.
Bronchiectasis may present as a primary lung manifestation of the conditions listed below, which can cause chronic inflammation resulting from an abnormality of anatomy, immunity or function.
Secondary bronchiectasis is more common and may occur as a complication of other lung diseases as a consequence of airway distortion, traction and ultimate damage in relation to conditions including COPD, emphysema, bronchitis, bronchiolitis and interstitial lung disease.
Post infection:
Pneumonia
Pertussis (whooping cough)
Viral (measles, adenovirus, influenza virus)
Mycobacterial (tuberculosis and atypical NTM)
Primary or secondary immune deficiency:
Immunoglobulin G subclass deficiency – for more information go to Immune Deficiency Foundation
Hypogammaglobulinaemia
Lung and bone marrow transplantation
Malignancy
HIV/AIDS
Human T-Lymphotropic Virus 1 (HTLV-1)
Asthma and fungal allergy:
Allergic bronchopulmonary aspergillosis (ABPA)
Allergic bronchopulmonary aspergillosis (ABPA) is a disease of the respiratory tract that occurs in response to the presence of a fungus called Aspergillus.
There are many different types of Aspergillus, but Aspergillus fumigatus is the most common to cause disease in humans.
Following the inhalation of Aspergillus spores the following may occur:
Normal lungs no response
Immunocompromised invasive response (eg invasive pulmonary aspergillosis, necrotising aspergillosis). Generally only occurs in people with very significant problems of their immune system.
Structural lung abnormality colonisation of abnormal lung (eg aspergiloma). This disease usually occurs when the lung structure is not normal, such as a cavity in the lung from a previous severe or destructive infection such as tuberculosis.
Allergic allergic disease (eg asthma worsening, ABPA). This form of aspergillus-related disease occurs in individuals who are ‘atopic’ or prone to allergy, particularly those with asthma
Mucociliary dysfunction:
Recurrent small volume aspiration:
Poor dentition/recurrent oral infection
Bronchial obstruction:
Inhalation of foreign objects such as peanuts
Tumour
Airway compression
Lymph node
Systemic inflammatory diseases:
Rheumatoid arthritis
Sjögren’s Syndrome
Sjögren’s syndrome is an autoimmune disease where the body’s immune system mistakenly attacks its own moisture producing glands. Lymphocytes infiltrate and destroy these glands causing decreased production of saliva and tears.
Inflammatory bowel disease
Sarcoidosis
Sarcoidosis is the name given to a condition in which “sarcoid granulomas” appear in the body’s tissues.
Sarcoidosis is a form of inflammation that is not cancerous and it usually gets better by itself over time. Sarcoid granulomas are seen on tissue biopsy under the microscope and consist of groups of immune cells which are normally part of the body’s defence system.
In chronic or progressive disease, treatment with prednisolone or cortisone may be required.
Sarcoidosis can involve any organ in the body, but in 90% of cases, it involves the lungs or lymph nodes next to the lungs.
Structural lung disease:
Chronic obstructive pulmonary disease
Bronchiolitis
Interstitial lung disease
Pulmonary fibrosis and pneumoconiosis:
Miscellaneous
Treatable causes of bronchiectasis:
Immune deficiency
ABPA
Mycobacterial infection
Airway obstruction
Inflammatory bowel disease
Rheumatoid arthritis
Aspiration
