Pseudomonas and risk factor mitigation for chronic lung allograft dysfunction

Reduced levels of liver kinase B1 in small extracellular vesicles as a predictor for chronic lung allograft dysfunction in cystic fibrosis lung transplant recipients

Small extracellular vesicles (sEVs) isolated from plasma of lung transplant recipients (LTRs) with chronic lung allograft dysfunction (CLAD) contain increased levels of lung associated self-antigens, Kα1 tubulin and collagen V, and decreased expression of the tumor suppressor liver kinase B1 (LKB1). In this study, sEVs were isolated from plasma collected from LTRs with or without cystic fibrosis (CF) from multiple centers at the onset of CLAD and 6 and 12 months before clinical diagnosis of CLAD (n = 32) as well as from time-matched stable controls (n = 25). sEVs were analyzed for Kα1 tubulin, collagen V, and LKB1 by western blot. Exoview R200, a functionalized microarray chip was employed to characterize the LKB1 in sEVs. EVs from non-CF LTRs had higher levels of lung self-antigens (p < 0.05) and lower levels of LKB1 (p = 0.024) 12 months before CLAD diagnosis than those from time-matched stable LTRs; however, in CF LTRs, only LKB1 levels were lower (p = 0.0005) 6 months before diagnosis. Further characterization of sEVs 6 months before CLAD in CF LTRs also demonstrated significantly lower numbers of LKB1 and LKB1/CD9 + sEV particles. Reduced LKB1 in circulating sEVs offers a potential biomarker for the risk of CLAD in LTRs with CF.

Detection of Bacterial Colonization in Lung Transplant Recipients Using an Electronic Nose

Background

Bacterial colonization (BC) of the lower airways is common in lung transplant recipients (LTRs) and increases the risk of chronic lung allograft dysfunction. Diagnosis often requires bronchoscopy. Exhaled breath analysis using electronic nose (eNose) technology may noninvasively detect BC in LTRs. Therefore, we aimed to assess the diagnostic accuracy of an eNose to detect BC in LTRs.

Methods

We performed a cross-sectional analysis within a prospective, single-center cohort study assessing the diagnostic accuracy of detecting BC using eNose technology in LTRs. In the outpatient clinic, consecutive LTR eNose measurements were collected. We assessed and classified the eNose measurements for the presence of BC. Using supervised machine learning, the diagnostic accuracy of eNose for BC was assessed in a random training and validation set. Model performance was evaluated using receiver operating characteristic analysis.

Results

In total, 161 LTRs were included with 80 exclusions because of various reasons. Of the remaining 81 patients, 16 (20%) were classified as BC and 65 (80%) as non-BC. eNose-based classification of patients with and without BC provided an area under the curve of 0.82 in the training set and 0.97 in the validation set.

Conclusions

Exhaled breath analysis using eNose technology has the potential to noninvasively detect BC.

Outcome and prognostic factors after lung transplantation for bronchiectasis other than cystic fibrosis

BACKGROUND

While lung transplant (LTX) can be an effective therapy to provide the survival benefit in selected populations, post-transplant outcome in LTX recipients with bronchiectasis other than cystic fibrosis (CF) has been less studied. Pseudomonas aeruginosa, often associated with exacerbations in bronchiectasis, is the most common micro-organism isolated from LTX recipients. We aimed to see the outcomes of patients with bronchiectasis other than CF after LTX and seek the risk factors associated with pre- and post-transplant Pseudomonas status.

METHODS

Patients who underwent LTX at Tohoku University Hospital between January 2000 and December 2020 were consecutively included into the retrospective cohort study. Pre- and post-transplant prevalence of Pseudomonas colonization between bronchiectasis and other diseases was reviewed. Post-transplant outcomes (mortality and the development of chronic lung allograft dysfunction (CLAD)) were assessed using a Cox proportional hazards and time-to-event outcomes were estimated using the Kaplan-Meier method.

RESULTS

LTX recipients with bronchiectasis experienced a high rate of pre- and post-transplant Pseudomonas colonization compared to other diseases with statistical significance (p < 0.001 and p < 0.001, respectively). Nevertheless, long-term survival in bronchiectasis was as great as non-bronchiectasis (Log-rank p = 0.522), and the bronchiectasis was not a trigger for death (HR 1.62, 95% CI 0.63-4.19). On the other hand, the chance of CLAD onset in bronchiectasis was comparable to non-bronchiectasis (Log-rank p = 0.221), and bronchiectasis was not a predictor of the development of CLAD (HR 1.88, 95% CI 0.65-5.40).

CONCLUSIONS

Despite high prevalence of pre- and post-transplant Pseudomonas colonization, the outcome in LTX recipients with bronchiectasis other than CF was comparable to those without bronchiectasis.