The Airway Microbiota Signatures of Infection and Rejection in Lung Transplant Recipients

BackgroundInfection and rejection are the two most common complications after lung transplantation (LT) and are associated with increased morbidity and mortality. The differential diagnosis of infection and rejection is sometimes difficult due to similar clinical manifestations. However, few studies have investigated the airway microbiota between lung transplant recipients (LTRs) with infection and rejection. ResultsA total of 181 sputum samples (event-free, n=47; infection, n=103; rejection, n=31) were collected from 59 LTRs. A distinct airway microbiota was observed among clinically stable (or event-free) recipients and those with infection or acute rejection after LT. Alpha and beta diversity were significantly different between event-free and rejection recipients and between infection and rejection recipients. Ten differential genera were identified by linear discriminant analysis effect size (LEfSe), with Corynebacterium, unclassified Enterococcaceae and unclassified Lactobacillales enriched in recipients with infection, and Rothia, Granulicatella, Neisseria, Actinomyces, Leptotrichia, Lactobacillus and unclassified Aerococcaceae more abundant in LTRs with acute rejection. Random forest analyses indicated that the combination of the 10 microbiota constituents and procalcitonin (PCT) and T-lymphocyte levels showed AUCs of 0.894, 0.955 and 0.913 to differentiate between event-free and infection, event-free and rejection, and infection and rejection recipients, respectively. ConclusionsOur study is the first to compare the airway microbiota between LTRs with infection and acute rejection. The airway microbiota, especially combined with PCT and T-lymphocyte levels, showed satisfactory predictive efficiency in discriminating among clinically stable recipients and those with infection and acute rejection, suggesting that the airway microbiota was an indicator to differentiate between infection and acute rejection after LT.