Pathophysiology, causes and genetics of paediatric and adult bronchiectasis

Abstract

Bronchiectasis has historically been considered to be irreversible dilatation of the airways, but with modern imaging techniques it has been proposed that 'irreversible' be dropped from the definition. The upper limit of normal for the ratio of airway to arterial development increases with age, and a developmental perspective is essential. Bronchiectasis (and persistent bacterial bronchitis, PBB) is a descriptive term and not a diagnosis, and should be the start not the end of the patient's diagnostic journey. PBB, characterized by airway infection and neutrophilic inflammation but without significant airway dilatation may be a precursor of bronchiectasis, and there are many commonalities in the microbiology and the pathology, which are reviewed in this article. A high index of suspicion is essential, and a history of chronic wet or productive cough for more than 4-8 weeks should prompt investigation. There are numerous underlying causes of bronchiectasis, although in many cases no cause is found. Causes include post-infectious, especially after tuberculosis, adenoviral or pertussis infection; aspiration syndromes; defects in host defence, which may solely affect the airways (cystic fibrosis, not considered in this review, and primary ciliary dyskinesia); and primary ciliary dyskinesia or be systemic, such as common variable immunodeficiency; genetic syndromes; and anatomical defects such as intraluminal airway obstruction (e.g. foreign body), intramural obstruction (e.g. complete cartilage rings) and external airway compression (e.g. by tuberculous lymph nodes). Identification of the underlying cause is important, because some of these conditions have specific treatments and others genetic implications for the family.

New Perspectives in the Diagnosis and Management of Allergic Fungal Airway Disease

“… 72 It is well established that persistent airway blockage leads to bronchiectasis, and it is possible that the mucus impaction in AFAD is the major reason for the development of bronchiectasis. 73 , 74 The fleeting shadows that are also characteristic of AFAD are also probably secondary to mucus obstruction leading to a localised area of eosinophilic pneumonia. The precise pathway by which IgE sensitisation to thermotolerant filamentous fungi may cause production of viscid mucus is not clear, but could be related to excess production of MUC5AC by goblet cells as a result of vigorous T2 hyperimmune stimulation.…”

Antimicrobial Resistance in Common Respiratory Pathogens of Chronic Bronchiectasis Patients: A Literature Review

“…The airways of both NCFB and CF bronchiectasis patients are colonized by similar and frequent microbiota. However, in CF bronchiectasis patients, a tendency towards the growth of Achromobacter xylosoxidans, Burkholderia cepacia complex, H. influenza, P. aeruginosa, S. aureus, and S. maltophilia was demonstrated [4]. Instead, in NCFB patients, H. influenza, M. catarrhalis, NTM, P. aeruginosa or enteric gram-negative bacteria (frequently cultured from samples of the lower respiratory tract) can be predominantly found [36,74].…”

“…Recently, Bush and Floto proposed a possible pathophysiological mechanism, which involves: (a) persistent or recurrent infection, (b) impairment of mucociliary clearance, and (c) airway obstruction [4]. Specifically, persistent or recurrent infections cause progressive neutrophilic inflammation [5,6]-favoring bronchial wall damage-Th17-biased adaptive immunity [7]-promoting enlargement of lymphoid follicles [8], neutrophil recruitment, and mucus hypersecretion [7].…”

Plenary Sessions

“…The BTS guidelines propose a single oral agent, amoxicillin or clarithromycin as the first‐line treatment. Commonly a 2‐week course of treatment is used (14).…”