Airway colonization and gastric aspiration after lung transplantation: do birds of a feather flock together?

BACKGROUND: Both gastroesophageal reflux and airway colonization with Pseudomonas aeruginosa (P aeruginosa) are common in lung transplantation (LTx) recipients. There is mounting evidence that, due to their interaction with the epithelium, both may be involved in chronic allograft dysfunction/bronchiolitis obliterans syndrome (BOS) after LTx. We investigated whether gastric aspiration and airway colonization with P aeruginosa after LTx are associated.
METHODS: In this retrospective, cross-sectional, case-control study, 24 stable double (SS) LTx recipients were included. Markers of gastroesophageal reflux (pepsin, bile acids) and airway inflammation (neutrophilia and interleukin-8 (IL-8)) were evaluated in bronchoalveolar lavage (BAL) samples of post-operatively colonized (n = 12) and non-colonized matched-control LTx recipients (n = 12).
RESULTS: BAL bile acid levels, but not pepsin levels, as well as neutrophilia and IL-8 protein levels were significantly elevated in colonized compared with non-colonized patients. Furthermore, bile acid levels, but not pepsin levels, correlated positively with BAL neutrophilia and IL-8 protein levels.
CONCLUSIONS: Bile acid aspiration and airway colonization by P aeruginosa after LTx seem to be associated. This relationship between reflux and airway colonization and their role in the development of chronic allograft dysfunction/BOS after LTx should be further elucidated; nevertheless, induction of IL-8-mediated neutrophilic airway inflammation may be a putative mechanism.