Microbiome and metabolome patterns after lung transplantation reflect underlying disease and chronic lung allograft dysfunction.

BACKGROUND: Progression of chronic lung disease may lead to the requirement for lung transplant (LTx). Despite improvements in short-term survival after LTx, chronic lung allograft dysfunction (CLAD) remains a critical challenge for long-term survival. This study investigates the molecular and microbial relationships between underlying lung disease and the development of CLAD in bronchoalveolar lavage fluid (BALF) from subjects post-LTx, which is crucial for tailoring treatment strategies specific to allograft dysfunctions. METHODS: Paired 16S rRNA gene amplicon sequencing and untargeted LC-MS/MS metabolomics were performed on 856 BALF samples collected over 10 years from LTx recipients (n = 195) with alpha-1-antitrypsin disease (AATD, n = 23), cystic fibrosis (CF, n = 47), chronic obstructive pulmonary disease (COPD, n = 78), or pulmonary fibrosis (PF, n = 47). Data were analyzed using random forest (RF) machine learning and multivariate statistics for associations with underlying disease and CLAD development. RESULTS: The BALF microbiome and metabolome after LTx differed significantly according to the underlying disease state (PERMANOVA, p = 0.001), with CF and AATD demonstrating distinct microbiome and metabolome profiles, respectively. Uniqueness in CF was mainly driven by Pseudomonas abundance and its metabolites, whereas AATD had elevated levels of phenylalanine and a lack of shared metabolites with the other underlying diseases. BALF microbiome and metabolome composition were also distinct between those who did or did not develop CLAD during the sample collection period (PERMANOVA, p = 0.001). An increase in the average abundance of Veillonella (AATD, COPD) and Streptococcus (CF, PF) was associated with CLAD development, and decreases in the abundance of phenylalanine-derivative alkaloids (CF, COPD) and glycerophosphorylcholines (CF, COPD, PF) were signatures of the CLAD metabolome. Although the relative abundance of Pseudomonas was not associated with CLAD, the abundance of its virulence metabolites, including siderophores, quorum-sensing quinolones, and phenazines, were elevated in those with CF who developed CLAD. There was a positive correlation between the abundance of these molecules and the abundance of Pseudomonas in the microbiome, but there was no correlation between their abundance and the time in which BALF samples were collected post-LTx. CONCLUSIONS: The BALF microbiome and metabolome after LTx are particularly distinct in those with underlying CF and AATD. These data reflect those who developed CLAD, with increased virulence metabolite production from Pseudomonas, an aspect of CF CLAD cases. These findings shed light on disease-specific microbial and metabolic signatures in LTx recipients, offering valuable insights into the underlying causes of allograft rejection. Video Abstract.

Donation after circulatory death in lung transplantation-five-year follow-up from ISHLT Registry.

BACKGROUND: This study aimed to examine intermediate-term outcomes of lung transplantation (LTx) recipients from donors after circulatory death (DCD). METHODS: We examined the International Society for Heart and Lung Transplantation (ISHLT) Thoracic Transplant Registry data for patients transplanted between January 2003 and June 2017 at 22 centers in North America, Europe, and Australia participating in the DCD Registry. The distribution of continuous variables was summarized as median and interquartile range (IQR) values. Wilcoxon rank sum test was used to compare distribution of continuous variables and chi-square or Fisher's exact test for categorical variables. Kaplan-Meier survival rates after LTx from January 2003 to June 2016 were compared between DCD-III (Maastricht category III withdrawal of life-sustaining therapy [WLST]) only and donors after brain death (DBD) using the log-rank test. Risk factors for 5-year mortality were investigated using Cox multivariate proportional-hazards model. RESULTS: The study cohort included 11,516 lung transplants, of which 1,090 (9.5%) were DCD lung transplants with complete data. DCD-III comprised 94.1% of the DCD cohort. Among the participating centers, the proportion of DCD-LTx performed each year increased from 0.6% in 2003 to 13.5% in 2016. DCD donor management included extubation in 91%, intravenous heparin in 53% and pre-transplant normothermic ex vivo donor lung perfusion in 15%. The median time interval from WLST to cardiac arrest was 15 minutes (IQR: 11-22 minutes) and to cold flush 32 minutes (IQR: 26-41minutes). Compared with DBD, donor age was higher in DCD-III donors (46 years [IQR: 34-55] vs 40 years [IQR: 24-52]), bilateral LTx was performed more often (88.3% vs 76.6%), and more recipients had chronic obstructive pulmonary disease and emphysema as their transplant indication. Five-year survival rates were comparable (63% vs 61%, p = 0.72). In multivariable analysis, recipient and donor ages, indication diagnosis, procedure type (single vs bilateral and double LTx), and transplant era (2003-2009 vs 2010-2016) were independently associated with survival (p < 0.001), but donor type was not (DCD-III vs DBD; hazard ratio, 1.04 [0.90-1.19], p = 0.61). CONCLUSION: This ISHLT DCD Registry report with 5-year follow-up demonstrated similar favorable long-term survival in DCD-III and DBD lung donor recipients at 22 experienced centers globally. These data indicate that more extensive use of DCD-LTx would increase donor organ availability and may reduce waiting list mortality.

Portable normothermic ex-vivo lung perfusion, ventilation, and functional assessment with the Organ Care System on donor lung use for transplantation from extended-criteria donors (EXPAND): a single-arm, pivotal trial.

BACKGROUND: Donor lung use for transplantation is the lowest among solid organ tranplants because of several complex and multifactorial reasons; one area that could have a substantial role is the limited capabilities of cold ischaemic storage. The aim of the EXPAND trial was to evaluate the efficacy of normothermic portable Organ Care System (OCS) Lung perfusion and ventilation on donor lung use from extended-criteria donors and donors after circulatory death, which are rarely used. METHODS: In this single-arm, pivotal trial done in eight institutions across the USA, Germany, and Belgium, lungs from extended-criteria donors were included if fulfilling one or more of the following criteria: a ratio of partial pressure of arterial oxygen (PaO2) to fractional concentration of oxygen inspired air (FiO2) in the donor lung of 300 mm Hg or less; expected ischaemic time longer than 6 h; donor age 55 years or older; or lungs from donors after circulatory death that were recruited and assessed using OCS Lung. Lungs were transplanted if they showed stability of OCS Lung variables, PaO2:FiO2 was more than 300 mm Hg, and they were accepted by the transplanting surgeon. Patients were adult bilateral lung transplant recipients. The primary efficacy endpoint was a composite of patient survival at day 30 post-transplant and absence of The International Society for Heart & Lung Tranplantation primary-graft dysfunction grade 3 (PGD3) within 72 h post-transplantation, with a prespecified objective performance goal of 65%. The primary analysis population was all transplanted recipients. This trial is registered with ClinicalTrials.gov, number NCT01963780, and is now complete. FINDINGS: Between Jan 23, 2014, and Oct 23, 2016, 93 lung pairs were perfused, ventilated, and assessed on the OCS Lung. 12 lungs did not meet OCS transplantation criteria so 81 lungs were suitable for transplantation. Two lungs were excluded for logistical reasons, hence 79 (87%) of eligible lungs were transplanted. The primary endpoint was achieved in 43 (54%) of 79 patients and did not meet the objective performance goal. 35 (44%) of 79 patients had PGD3 within the initial 72 h. 78 (99%) of 79 patients had survived at 30 days post-transplant. The mean number of lung graft-related serious adverse events (respiratory failure and major pulmonary-related infection) was 0·3 events per patient (SD 0·5). INTERPRETATION: Despite missing the objective primary endpoint, the portable OCS Lung resulted in 87% donor lung use for transplantation with excellent clinical outcomes. Many lungs declined by other transplant centres were successfully transplanted using this new technology, which implies its use has the potential to increase the number of lung transplants performed worldwide. Whether similar outcomes could be obtained if these lungs were preserved on ice is unknown and remains an area for future research. FUNDING: TransMedics Inc.

Greater survival despite increased complication rates following lung transplant for alpha-1-antitrypsin deficiency compared to chronic obstructive pulmonary disease.

BACKGROUND: Alpha-1-antitrypsin (A1AT) deficiency (A1ATD) is characterized by accelerated degradation of lung function. We examined our experience with lung transplantation for chronic obstructive pulmonary disease (COPD) with and without A1ATD to compare survival and rates of postoperative surgical complications. METHODS: Patients with A1ATD and non-A1ATD COPD undergoing lung transplantation from 1988-2015 at our institution were analyzed. Complications were categorized into non-gastroenteritis gastrointestinal (GI), wound, airway, and reoperation for bleeding. Overall and complication-free survival were evaluated using Kaplan-Meier curves and Cox proportional hazards models. RESULTS: Three hundred and eighty-five patients underwent lung transplant for COPD (98 A1ATD). For A1ATD, 56.1% underwent single lung transplantation (80.6% for COPD). Early overall and complication-free survival was worse for A1ATD, but this trend reversed at longer follow up. Unadjusted estimated survival showed advantage for COPD at 90 days and 1 year, which attenuated by 5 years and reversed at 10 years (P<0.001). On adjusted analysis, A1ATD was associated with a trend toward lower complication-free survival at 90 days and 1 year, due partly to increased rates of post-transplant GI pathology, particularly in the era of the lung allocation score (LAS). CONCLUSIONS: A1ATD lung recipients had worse short-term complication-free survival but improved long-term survival compared to COPD patients. A1ATD was associated with greater risk of new GI pathology after transplant. Close monitoring of A1ATD patients with timely evaluation of GI complaints after transplant is warranted.

Secondary pulmonary arterial hypertension: to treat or not to treat?

PURPOSE OF REVIEW: The purpose of this review is to review recent literature related to mechanisms and treatment options for 'secondary' (i.e., WHO Groups 3 and 5) pulmonary arterial hypertension (PAH). RECENT FINDINGS: Published randomized controlled trials, in general, do not support the use of approved therapies for 'primary' (i.e., WHO Group 1) PAH patients in patients with Group 3 PAH because of the small numbers of patients and inconsistent benefit. Therefore, we currently recommend against the use of these medications for Group 3 PAH. Similarly, there is limited evidence supporting the use of Group 1 PAH medications in Group 5 patients. In most patients with Group 5 PAH, treatment should be directed to the underlying disease. SUMMARY: The utility of PAH-specific therapy in WHO Group 3 PAH is unclear because of the small numbers of patients evaluated and inconsistent beneficial effects observed. There is limited evidence supporting the use of PAH medications in Group 5 patients, and they may be harmful in some cases.

Clinical implications of donor age: A single-institution analysis spanning 3 decades.

BACKGROUND: We sought to clarify the effect of donor age as a continuous variable on morbidity and mortality in a single-institution experience. METHODS: From 1986 to 2016, 882 adult lung transplants were performed, including 396 in the lung allocation score era. Kaplan-Meier curves and Cox proportional hazards models were used to evaluate the association of donor age with overall survival and bronchiolitis obliterans syndrome (BOS) score ≥1-free survival. Logistic regression was used to evaluate the association with primary graft dysfunction grade 3. Natural cubic splines were used to explore donor age in a continuous fashion to allow for nonlinear relationships. RESULTS: In the lung allocation score era, unadjusted 5-year survival was not significantly different between 3 a priori-defined donor age groups: age <40, 40 to 54, and age ≥55 years (64%, 61%, and 69%, P = .8). Unadjusted 5-year freedom from BOS ≥1 was not significantly different (34%, 20%, and 33%, respectively, P = .1). After we adjusted for comorbidities, cubic spline analysis demonstrated no effect between donor age as a continuous variable and hazard for mortality at 5 years. Similarly, no interaction was seen between donor age and risk of BOS or primary graft dysfunction 3. Adjusted analysis of all 882 transplants pre- and postinception of the lung allocation score also showed no effect of age on 10-year survival. CONCLUSIONS: Long-term survival of lung transplant recipients was not affected by the age of the donor. These findings support the notion that donor age could be relaxed.

Pulmonary Transplant Salvage Using Ultrasound-Assisted Thrombolysis of Subacute Occlusive Main Pulmonary Artery Embolus.

A 53-year-old woman who underwent bilateral lung transplantation 14 months before presented with 2 to 3 weeks of severe exertional dyspnea. Workup revealed a complete embolic occlusion of her left main pulmonary artery related to a femoral deep venous thrombosis. The occlusion did not respond to systemic anticoagulation, and a trial of catheter-directed thrombolysis was pursued. Flow to the left lower lobe was restored after 2 days of thromobolytic therapy. The patient is alive and well at more than 1 year of follow-up.

Gender differences in long-term survival post-transplant: A single-institution analysis in the lung allocation score era.

The purpose of this study was to clarify the significance of recipient gender status on lung transplant outcomes in a large single-institution experience spanning three decades, we analyzed data from all lung transplants performed in our institution since 1986. Kaplan-Meier curves and Cox proportional hazard models were used to evaluate the effect of recipient characteristics on survival and BOS score ≥1-free survival. Logistic regression analysis was used to explore the association of gender with short-term graft function. About 876 lung transplants were performed between 1986 and 2016. Kaplan-Meier survival estimates at 5 years post-transplant for females vs males in the LAS era were 71% vs 58%. In the LAS era, females showed greater unadjusted BOS≥1-free survival than males (35% vs 25%, P=.02) over 5 years. Female gender was the only factor in the LAS era significantly associated with improved adjusted 5-year survival [HR 0.56 (95% CI 0.33, 0.95) P=.03]. Conversely, in the pre-LAS era female gender was not associated with improved survival. Female recipients showed significantly improved survival over 5 years compared to males in the LAS era. A prospective analysis of biologic and immunologic differences is warranted.

Lung transplantation for pulmonary sarcoidosis. Twenty-five years of experience in the USA.

OBJECTIVE: Lung transplantation is the ultimate treatment for end-stage pulmonary sarcoidosis. Post-transplant survival outcomes remain unclear. METHODS: Survival models were used to assess survival and graft outcomes in patients with sarcoid among 20,896 lung transplants performed in the USA. RESULTS: 695 lung recipients were transplanted for pulmonary sarcoidosis. Sarcoid lung recipients had similar median survival rate (69.7 months (IQR 60.2-79.3)) compared with the non-sarcoid lung recipients (63.1 months (IQR 61.4-64.8), p=0.88). In multivariate Cox regression, sarcoidosis was not independently associated with worse mortality (HR 0.96 (95% CI 0.85 to 1.08), p=0.51). Among the sarcoid lung recipients, double lung transplantation (HR 0.76 (0.58 to 0.99), p=0.04) and lung allocation score era (HR 0.74 (0.56 to 0.97), p=0.03) were associated with improved survival. CONCLUSIONS: Recipients of lung transplants for pulmonary sarcoidosis had similar outcomes compared with non-sarcoid lung recipients.

MSC therapy attenuates obliterative bronchiolitis after murine bone marrow transplant.

RATIONALE: Obliterative bronchiolitis (OB) is a significant cause of morbidity and mortality after lung transplant and hematopoietic cell transplant. Mesenchymal stromal cells (MSCs) have been shown to possess immunomodulatory properties in chronic inflammatory disease. OBJECTIVE: Administration of MSCs was evaluated for the ability to ameliorate OB in mice using our established allogeneic bone marrow transplant (BMT) model. METHODS: Mice were lethally conditioned and received allogeneic bone marrow without (BM) or with spleen cells (BMS), as a source of OB-causing T-cells. Cell therapy was started at 2 weeks post-transplant, or delayed to 4 weeks when mice developed airway injury, defined as increased airway resistance measured by pulmonary function test (PFT). BM-derived MSC or control cells [mouse pulmonary vein endothelial cells (PVECs) or lung fibroblasts (LFs)] were administered. Route of administration [intratracheally (IT) and IV] and frequency (every 1, 2 or 3 weeks) were compared. Mice were evaluated at 3 months post-BMT. MEASUREMENTS AND MAIN RESULTS: No ectopic tissue formation was identified in any mice. When compared to BMS mice receiving control cells or no cells, those receiving MSCs showed improved resistance, compliance and inspiratory capacity. Interim PFT analysis showed no difference in route of administration. Improvements in PFTs were found regardless of dose frequency; but once per week worked best even when administration began late. Mice given MSC also had decreased peribronchiolar inflammation, lower levels of hydroxyproline (collagen) and higher frequencies of macrophages staining for the alternatively activated macrophage (AAM) marker CD206. CONCLUSIONS: These results warrant study of MSCs as a potential management option for OB in lung transplant and BMT recipients.

Use of the donor lung after asphyxiation or drowning: effect on lung transplant recipients.

BACKGROUND: With the relative paucity of acceptable donors for lung transplantation, criteria for extended donor consideration are being explored. We sought to evaluate the suitability of donors whose cause of death was asphyxiation or drowning (A/D) as a potential option to enlarge the donor pool. METHODS: We queried the United Network for Organ Sharing (UNOS) Standard Transplant Analysis and Research registry for lung transplantation from 1987 to 2010 to assess associations between cause of death and recipient survival using the Kaplan-Meier method. To adjust for potential confounders, we used a Cox proportional hazards model and a logistic regression model to evaluate incidence of rejection within the first year. RESULTS: There were 18,250 adult primary lung transplantations performed, with 309 A/D donors. There was no difference in survival between groups (log-rank, p = 0.52). There were no differences in demographics, length of stay, airway dehiscence, lung allocation score (LAS), or ischemic time in univariate analysis (all p > 0.05). The A/D lung recipients had fewer deaths from pulmonary causes (5.8% versus 9.5%; p = 0.02). Proportional hazards analysis was significant for double lung transplantation (hazard ratio [HR], 0.85; 95% confidence interval [CI], 0.8-0.9), height difference (HR, 1.002; 95% CI, 1.00-1.003), donor age greater than 50 years (HR, 0.89; 95% CI, 0.83-0.96), and recipient age greater than 55 years (HR, 0.8; 95% CI, 0.76-0.84). A/D cause of death did not impact survival in multivariate analysis. CONCLUSIONS: A/D as a donor cause of death was not associated with poor long-term survival or incidence of rejection in the first year after transplantation. Donor cause of death by A/D, when carefully evaluated and selected, should not automatically exclude the organ from transplant consideration. These results provide important justification for potentially broadening the donor pool safely.

Elevated peptides in lung lavage fluid associated with bronchiolitis obliterans syndrome.

OBJECTIVE: The objective of this discovery-level investigation was to use mass spectrometry to identify low mass compounds in bronchoalveolar lavage fluid from lung transplant recipients that associate with bronchiolitis obliterans syndrome. EXPERIMENTAL DESIGN: Bronchoalveolar lavage fluid samples from lung transplant recipients were evaluated for small molecules using ESI-TOF mass spectrometry and correlated to the development of bronchiolitis obliterans syndrome. Peptides associated with samples from persons with bronchiolitis obliterans syndrome and controls were identified separately by MS/MS analysis. RESULTS: The average bronchoalveolar lavage fluid MS spectrum profile of individuals that developed bronchiolitis obliterans syndrome differed greatly compared to controls. Controls demonstrated close inter-sample correlation (R = 0.97+/-0.02, average+/-SD) while bronchiolitis obliterans syndrome showed greater heterogeneity (R = 0.86+/-0.09, average+/-SD). We identified 89 features that were predictive of developing BOS grade 1 and 66 features predictive of developing BOS grade 2 or higher. Fractions from MS analysis were pooled and evaluated for peptide content. Nearly 10-fold more peptides were found in bronchiolitis obliterans syndrome relative to controls. C-terminal residues suggested trypsin-like specificity among controls compared to elastase-type enzymes among those with bronchiolitis obliterans syndrome. CONCLUSIONS: Bronchoalveolar lavage fluid from individuals with bronchiolitis obliterans syndrome has an increase in low mass components detected by mass spectrometry. Many of these features were peptides that likely result from elevated neutrophil elastase activity.

Clostridium difficile infection increases mortality risk in lung transplant recipients.

BACKGROUND: Clostridium difficile infection (CDI) and associated mortality in solid organ transplant recipients is rising, but data are scarce in lung transplant recipients. We aimed to characterize CDI and its effect on mortality in a large cohort of lung transplant recipients. METHODS: Lung transplant recipients were identified from our transplant database from 2000 to 2011. Cox proportional hazard models were used to calculate hazard ratios for CDI and death after adjusting for potential confounders identified from bivariate analysis. RESULTS: We identified 388 patients (196 female, 192 male), with a median age of 56 years (range, 8-75 years), during the study period. CDI developed after transplant in 89 (22.9%), with 27 (7.0%) developing CDI during the initial hospitalization at a mean diagnosis of 12.7 ± 11.4 days. Incidence varied widely each year (median, 24%; range, 5%-32%), with the highest rates in 2007 to 2008. Post-operative length of stay was identified as a significant predictor of CDI (hazard ratio [HR], 1.02; 95% confidence interval [CI], 1.01-1.03). Early CDI was an independent significant predictor of death (HR, 1.96; 95% CI, 1.14-3.36) as well as CDI anytime after transplant (HR, 1.61; 95% CI, 1.02-2.52). CONCLUSIONS: CDI rates varied widely from 2000 through 2011, with the highest rates in 2007 to 2008. Lung transplant recipients who developed CDI had a higher risk of death, especially when CDI occurred in the first 6 months after transplant.

Automatic event detection in lung transplant recipients based on home monitoring of spirometry and symptoms.

OBJECTIVE: The goal of this study was to develop, implement, and test an automated decision system to provide early detection of clinically important bronchopulmonary events in a population of lung transplant recipients following a home monitoring protocol. SUBJECTS AND METHODS: Spirometry and other clinical data were collected daily at home by lung transplant recipients and transmitted weekly to the study data center. Decision rules were developed using wavelet analysis of declines in spirometry and increases in respiratory symptoms from a learning set of patient home data and validated with an independent patient set. RESULTS: Using forced expiratory volume in 1 s or symptoms, the detection captured the majority of events (sensitivity, 80-90%) at an acceptable level of false alarms. On average, detections occurred 6.6-10.8 days earlier than the known event records. CONCLUSIONS: This approach is useful for early discovery of pulmonary events and has the potential to decrease the time required for humans to review large amount of home monitoring data to discover relatively infrequent but clinically important events.

Calcineurin inhibitors and Clostridium difficile infection in adult lung transplant recipients: the effect of cyclosporine versus tacrolimus.

BACKGROUND: Tacrolimus (FK506) has a superior immunosuppressive effect compared with cyclosporine (CSA) without a significant increase in generalized infectious complications. Differences in specific infections such as Clostridium difficile (CDI) have not been reported. We investigated the relationship between calcineurin inhibitors and CDI, hypothesizing that choice of calcineurin inhibitor (CSA or FK506) after lung transplantation would have no effect on the incidence of CDI. METHODS: We performed a retrospective chart review of lung transplant recipients between June 1, 2000, and December 31, 2005, at a single institution. Positive CDI assays through December 11, 2011, were also recorded. We used Student's t- and chi-squared tests (α = 0.05) to compare CSA and FK506 groups. We calculated adjusted hazard ratios for CDI using Cox proportional hazard models. RESULTS: We identified 217 lung transplant recipients: 106 patients in the CSA group and 111 patients in the FK506 group. A total of 31 patients (27.9%) in the FK506 group developed CDI postoperatively compared with 20 patients (18.9%) in the CSA group (P = 0.16). The adjusted hazard ratio for CDI in the FK506 group was not significantly higher (1.53; 95% confidence interval, 0.78-2.98). There was no significant difference in the intensive care unit or total length of stay, in-hospital incidence rate, time to first CDI episode, or recurrence rate between groups. CONCLUSIONS: The CDI rates were not significantly higher in the FK506 group than the CSA group in our study. These data are consistent with previous studies on FK506 that show no increase in infectious complications over CSA, and demonstrate its continued safety in lung transplantation.

ISHLT International Registry for Heart and Lung Transplantation - three decades of scientific contributions.

The International Registry for Heart and Lung Transplantation (Registry) was established by the International Society for Heart and Lung Transplant (ISHLT) in 1983. It has since become the largest repository of heart and lung transplant data in the world. The continued relevance of the Registry and its high impact scientific contributions have been possible through accountability and responsible governance. This manuscript describes the logistics of the Registry's operations, its goals and future directions.

Empirical null distribution based modeling of multi-class differential gene expression detection.

In this paper, we study the multi-class differential gene expression detection for microarray data. We propose a likelihood based approach to estimating an empirical null distribution to incorporate gene interactions and provide more accurate false positive control than the commonly used permutation or theoretical null distribution based approach. We propose to rank important genes by p-values or local false discovery rate based on the estimated empirical null distribution. Through simulations and application to a lung transplant microarray data, we illustrate the competitive performance of the proposed method.