Search

Purpose of review Chronic lung allograft dysfunction (CLAD) remains a major barrier preventing long-term survival following lung transplantation. As our clinical knowledge regarding its definition and presentation has significantly improved over the last years, adequate biomarkers to predict development of CLAD, phenotype of CLAD or prognosis post-CLAD diagnosis are definitely needed. Recent findings Radiological and physiological markers are gradually entering routine clinical practice. In-depth investigation of biological samples including broncho-alveolar lavage, biopsy and serum has generated potential biomarkers involved in fibrogenesis, airway injury and inflammation but none of these are universally accepted or implemented although progress has been made, specifically regarding donor-derived cell-free DNA and donor-specific antibodies. Although a lot of promising biomarkers have been put forward, a very limited number has made it to routine clinical practice. Nevertheless, a biomarker that leads to earlier detection or more adequate disease phenotyping would advance the field enormously.

BACKGROUND: Sarcoidosis is a systemic granulomatous disease that in most patients affects the lung. Pulmonary fibrotic sarcoidosis is clinically, radiologically, and pathologically a heterogeneous condition. Although substantial indirect evidence suggests small airways involvement, direct evidence currently is lacking. RESEARCH QUESTION: What is the role of the (small) airways in fibrotic sarcoidosis? STUDY DESIGN AND METHODS: Airway morphologic features were investigated in seven explant lungs with end-stage fibrotic sarcoidosis using a combination of CT scanning (large airways), micro-CT scanning (small airways), and histologic examination and compared with seven unused donor lungs as controls with specific attention focused on different radiologically defined sarcoidosis subtypes. RESULTS: Patients with central bronchial distortion (n = 3), diffuse bronchiectasis (n = 3), and usual interstitial pneumonia pattern (n = 1) were identified based on CT scan, showing a decrease and narrowing of large airways, a similar airway number and increased airway diameter of more distal airways, or an increase in airway number and airway diameter, respectively, compared with control participants. The number of terminal bronchioles per milliliter and the total number of terminal bronchioles were decreased in all forms of fibrotic sarcoidosis. Interestingly, the number of terminal bronchioles was inversely correlated with the degree of fibrosis. Furthermore, we identified granulomatous remodeling as a cause of small airways loss using serial micro-CT scanning and histologic examination. INTERPRETATION: The large airways are involved differentially in subtypes of sarcoidosis, but the terminal bronchioles universally are lost. This suggests that small airways loss forms an important aspect in the pathophysiologic features of fibrotic pulmonary sarcoidosis. ispartof: CHEST vol:160 issue:2 pages:562-571 ispartof: location:United States status: published

Video Abstract Download : Download video (50MB) Lung transplantation from a donor previously infected with SARS-CoV-2

Background Physiological lung ageing is associated with a gradual decline in dynamic lung volumes and a progressive increase in residual volume due to diminished elastic recoil of the lung, loss of alveolar tissue, and lower chest wall compliance. However, the effects of ageing on the small airways (ie, airways = 2.5 mm) diameter airways (-0.00781, -0.04409 to 0.02848; R-2=0.0007). In micro-CT analysis of small airways, the total number of terminal bronchioles per lung increased until the age of 30 years, after which an almost linear decline in the number of terminal bronchioles was observed (beta coefficient per decade -2035, 95% CI -2818 to -1252; R-2=0.55), accompanied by a non-significant increase in alveolar airspace size (6.44, -0.57 to 13.45, R-2=0.10). Moreover, this decrease in terminal bronchioles was associated with the age-related decline of pulmonary function predicted by healthy reference values. Interpretation Loss of terminal bronchioles is an important structural component of age-related decline in pulmonary function of healthy, non-smoking individuals.

Idiopathic pulmonary fibrosis (IPF) is a fibrotic disease with the histology of usual interstitial pneumonia (UIP). Although the pathologist's visual inspection is central in histologic assessments, threedimensional microcomputed tomography (microCT) assessment may complement the pathologist's scoring. We examined associations between the histopathologic features of UIP and IPF in explanted lungs and quantitative microCT measurements, including alveolar surface density, total lung volume taken up by tissue (%), and terminal bronchiolar number. Sixty frozen samples from 10 air-inflated explanted lungs with severe IPF and 36 samples from 6 donor control lungs were scanned with microCT and processed for histologic analysis. An experienced pathologist scored three major UIP criteria (patchy fibrosis, honeycomb, and fibroblastic foci), five additional pathologic changes, and immunohistochemical staining for CD68-, CD4-, CD8-, and CD79a-positive cells, graded on a 0 to 3+ scale. The alveolar surface density and terminal bronchiolar number decreased and the tissue percentage increased in lungs with IPF compared with controls. In lungs with IPF, lower alveolar surface density and higher tissue percentage were correlated with greater scores of patchy fibrosis, fibroblastic foci, honeycomb, CD79a-positive cells, and lymphoid follicles. A decreased number of terminal bronchioles was correlated with honeycomb score but not with the other scores. The three-dimensional microCT measurements reflect the pathological UIP and IPF criteria and suggest that the reduction in the terminal bronchioles may be associated with honeycomb cyst formation.

RationalePeripheral airway obstruction is a key feature of chronic obstructive pulmonary disease (COPD), but the mechanisms of airway loss are unknown. This study aims to identify the molecular and cellular mechanisms associated with peripheral airway obstruction in COPD.MethodsTen explanted lung specimens donated by patients with very severe COPD treated by lung transplantation and five unused donor control lungs were sampled using systematic uniform random sampling (SURS), resulting in 240 samples. These samples were further examined by micro-computed tomography (CT), quantitative histology and gene expression profiling.ResultsMicro-CT analysis showed that the loss of terminal bronchioles in COPD occurs in regions of microscopic emphysematous destruction with an average airspace size of ≥500 and InterpretationThe reduction in terminal bronchioles observed in lungs from patients with COPD occurs in a hot spot of microscopic emphysema, where there is upregulation of IFNG signalling, co-stimulatory immune checkpoint genes and genes related to the inflammasome pathway, and increased infiltration of immune cells. These could be potential targets for therapeutic interventions in COPD.

Although chronic lung allograft dysfunction (CLAD) remains the major life-limiting factor following lung transplantation, much of its pathophysiology remains unknown. The discovery that CLAD can manifest both clinically and morphologically in vastly different ways led to the definition of distinct subtypes of CLAD. In this review, recent advances in our understanding of the pathophysiological mechanisms of the different phenotypes of CLAD will be discussed with a particular focus on tissue-based and molecular studies. An overview of the current knowledge on the mechanisms of the airway-centered bronchiolitis obliterans syndrome, as well as the airway and alveolar injuries in the restrictive allograft syndrome and also the vascular compartment in chronic antibody-mediated rejection is provided. Specific attention is also given to morphological and molecular markers for early CLAD diagnosis or histological changes associated with subsequent CLAD development. Evidence for a possible overlap between different forms of CLAD is presented and discussed. In the end, "tissue remains the (main) issue," as we are still limited in our knowledge about the actual triggers and specific mechanisms of all late forms of posttransplant graft failure, a shortcoming that needs to be addressed in order to further improve the outcome of lung transplant recipients. ispartof: AMERICAN JOURNAL OF TRANSPLANTATION vol:20 issue:10 pages:2644-2651 ispartof: location:United States status: published

Rationale: Fibrotic hypersensitivity pneumonitis (fHP) is an interstitial lung disease caused by sensitization to an inhaled allergen. Objectives: To identify the molecular determinants associated with progression of fibrosis. Methods: Nine fHP explant lungs and six unused donor lungs (as controls) were systematically sampled (4 samples/lung). According to microcomputed tomography measures, fHP cores were clustered into mild, moderate, and severe fibrosis groups. Gene expression profiles were assessed using weighted gene co-expression network analysis, xCell, gene ontology, and structure enrichment analysis. Gene expression of the prevailing molecular traits was also compared with idiopathic pulmonary fibrosis (IPF). The explant lung findings were evaluated in separate clinical fHP cohorts using tissue, BAL samples, and computed tomography scans. Measurements and Main Results: We found six molecular traits that associated with differential lung involvement. In fHP, extracellular matrix and antigen presentation/sensitization transcriptomic signatures characterized lung zones with only mild structural and histological changes, whereas signatures involved in honeycombing and B cells dominated the transcriptome in the most severely affected lung zones. With increasing disease severity, endothelial function was progressively lost, and progressive disruption in normal cellular homeostatic processes emerged. All six were also found in IPF, with largely similar associations with disease microenvironments. The molecular traits correlated with in vivo disease behavior in a separate clinical fHP cohort. Conclusions: We identified six molecular traits that characterize the morphological progression of fHP and associate with in vivo clinical behavior. Comparing IPF with fHP, the transcriptome landscape was determined considerably by local disease extent rather than by diagnosis alone. ispartof: AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE vol:205 issue:1 pages:60-+ ispartof: location:United States status: published

American journal of respiratory and critical care medicine : AJRCCM 205(1), 121-125 (2022). doi:10.1164/rccm.202103-0594IM, Published by American Thoracic Society, New York, NY

Introduction: Ex vivo lung perfusion (EVLP) is a normothermic platform used to assess donor lungs. Many have studied biomarkers in lung injury, but it is unclear whether samples taken from one location are representative of the organ. Our objective was to investigate the uniformity of cytokine expression in tissue biopsies and in EVLP perfusates from various locations. Methods: In the tissue study, eight donor lungs were partitioned from apex to base. In each lung, three biopsies were taken from the third, sixth, and ninth slices, while two were taken from the lingula and an injury site. In the perfusate study, four samples were taken from four lobes in eight donors during EVLP. Expressions of IL-6, IL-8, IL-10, and IL-1β were measured using qPCR and ELISA. Results: In the tissue study, the mean intra-biopsy equal-variance F-value was 0.53. The median intra-biopsy coefficient of variation (CV) was 18%. In donors without gross focal injury, the mean comparisons of biopsies in each donor showed that the three consistent slices showed no differences and had a CV of 20%, which was similar to the intra-biopsy CV (p=0.80). Both the lingula and injury biopsies demonstrated larger differences from the rest. The median intra-lung CV of perfusates from different lobes was 4.9%. Conclusion: Intra-biopsy variances were consistent across biopsies. Lungs without gross focal injury demonstrated more consistent gene expression. The lingula is not a representative site due to high signal variability. The consistent measurements in EVLP perfusates provided a uniform picture of the inflammation.

Introduction: COVID-19 raises concerns for lung transplant recipients (LTX) due to the lung as a target organ in immunocompromised patients. Aims and objectives: Evaluating COVID-19 course, treatments received, radiological and functional evolution in LTX. Methods: We conducted a retrospective study of LTX with a PCR confirmed diagnosis of COVID-19. Results: 42 LTX were included from 18/03/2020 until 01/02/2021. Mean age was 54y (19-73), mean time after LTX 68mo (7-194). 30 (71%) LTX were hospitalised with a mean duration of 14d (1-41). Seven (17%) needed ICU, 5 (12%) endotracheal intubation and 1 (2%) VV ECMO. 4 (10%) died. From the 7 patients in ICU, 4 were aged>65y, 2 had diabetes, 2 hypertension, 2 BMI>30. In all hospitalised patients immunosuppression was adapted (mycophenolate mofetil withdrawn for at least 2 weeks, low level of calcineurin inhibitors, 5 day course of azithromycin 500mg). 8 (19%) received hydroxychloroquine, 8 (19%) remdesivir, 9 (21%) COVID-19 convalescent plasma and 9 (21%) higher corticosteroid dose. 4 (10%) LTX experienced recurrent COVID-19. 3 (7%) developed acute rejection shortly after COVID-19. In LTX with follow-up chest CT (n=15) minimal sequellae were described. Mean decrease in FEV1 compared to baseline at 1, 3 and 6 months was, respectively, -133mL (IQR -190 to 35, n=28), -176mL (IQR -330 to 75, n=16) and -48mL (IQR -140 to 90, n=11). No patient met criteria for onset of CLAD. Conclusions: We found a higher mortality and more severe disease course in LTX than in the healthy population. Recurrence of COVID-19 is a frequent event. At mid-term, we did not observe significant new incidence of CLAD onset. Treatment of COVID-19 and risk of CLAD after COVID-19 in LTX require further studies.

BACKGROUND: To investigate the diagnostic yield of 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) in lung transplant recipients. METHODS: A single-center, retrospective cohort study including 234 18F-FDG PET examinations in 199 lung transplant recipients. Indication for PET referral, 18F-FDG PET diagnosis/findings and final clinical diagnosis were classified into 3 groups: malignancy, infection/inflammation not otherwise specified, and chronic lung allograft dysfunction with restrictive allograft syndrome phenotype. Sensitivity/specificity analysis was performed to determine accuracy of 18F-FDG PET in each group. RESULTS: Sensitivity of 18F-FDG PET for malignancy was 91.4% (95% confidence interval, 82.5%-96.0%) and specificity was 82.3% (95% confidence interval, 74.5%-88.1%). Infection/inflammation not otherwise specified and restrictive allograft syndrome as indication for 18F-FDG PET comprised relatively small groups (14 and 31 cases, respectively). In addition, 18F-FDG PET revealed clinically relevant incidental findings in 15% of cases. CONCLUSIONS: Referral for 18F-FDG PET after lung transplantation mainly occurred to confirm or rule out malignancy. In this specific setting, 18F-FDG PET has a high diagnostic yield. Accuracy of 18F-FDG PET for other indications is less clear, given small sample sizes. Clinically relevant diagnoses, unrelated to the primary indication for 18F-FDG PET, are found relatively often in this immunocompromised cohort. ispartof: Transplantation vol:105 issue:7 pages:1603-1609 ispartof: location:United States status: published

Pulmonary fibroelastotic remodelling occurs within a broad spectrum of diseases with vastly divergent outcomes. So far, no comprehensive terminology has been established to adequately address and distinguish histomorphological and clinical entities. We aimed to describe the range of fibroelastotic changes and define stringent histological criteria. Furthermore, we wanted to clarify the corresponding terminology in order to distinguish clinically relevant variants of pulmonary fibroelastotic remodelling. We revisited pulmonary specimens with fibroelastotic remodelling sampled during the last ten years at a large European lung transplant centre. Consensus-based definitions of specific variants of fibroelastotic changes were developed on the basis of well-defined cases and applied. Systematic evaluation was performed in a steps-wise algorithm, first identifying the fulcrum of the respective lesions, and then assessing the morphological changes, their distribution and the features of the adjacent parenchyma. We defined typical alveolar fibro-elastosis as collagenous effacement of the alveolar spaces with accompanying hyper-elastosis of the remodelled and paucicellular alveolar walls, independent of the underlying disease in 45 cases. Clinically, this pattern could be seen in (idiopathic) pleuroparenchymal fibro-elastosis, interstitial lung disease with concomitant alveolar fibro-elastosis, following hematopoietic stem cell and lung transplantation, autoimmune disease, radio-/chemotherapy, and pulmonary apical caps. Novel in-transit and activity stages of fibroelastotic remodelling were identified. For the first time, we present a comprehensive definition of fibroelastotic remodelling, its anatomic distribution, and clinical associations, thereby providing a basis for stringent patient stratification and prediction of outcome.

BACKGROUND: Differential diagnosis of phenotypes of chronic lung allograft dysfunction (CLAD) remains troublesome. We hypothesized that F-fluorodeoxyglucose positron emission tomography with computed tomography (F-FDG PET/CT) may help in differential diagnosis of CLAD phenotypes, as it showed promising results regarding diagnosis and prognosis in interstitial lung diseases. METHODS: A monocentric, retrospective study was performed including all lung transplant recipients suffering from bronchiolitis obliterans syndrome (BOS) or restrictive allograft syndrome (RAS) who underwent F-FDG PET/CT scan, in comparison with stable lung transplant recipients. Maximum standardized uptake value (SUVmax) was associated with pulmonary function and survival. Proof-of-concept microCT and glucose transporter-1 staining served as morphologic validation for regions with different SUVmax. RESULTS: Maximum standardized uptake value was higher in RAS (median, 2.6; n = 29) compared with BOS (median, 1.0; n = 15) and stable patients (median, 0.59; n = 8) (P < 0.0001). In RAS, high SUVmax was associated with worse survival after F-FDG PET/CT (P = 0.0004; hazard ratio, 1.82). Forced vital capacity at F-FDG PET/CT inversely correlated with SUVmax (R = -0.40, P = 0.03). MicroCT analysis revealed extensive fibrosis in regions of high SUVmax, with an increased number of glucose transporter-1-positive cells. CONCLUSIONS: F-fluorodeoxyglucose positron emission tomography with CT may noninvasively differentiate RAS from BOS. RAS patients with areas of increased lung metabolism have worse outcome, demonstrating the potential use of F-FDG PET/CT during follow-up after lung transplantation. ispartof: TRANSPLANTATION vol:103 issue:4 pages:823-831 ispartof: location:United States status: published

Chronic obstructive pulmonary disease (COPD) is associated with abnormal inflammatory responses and airway wall remodeling, leading to reduced lung function. An association between the bone morphogenetic protein (BMP-6) locus and forced vital capacity has been found in a genome-wide association study. However, the role of BMP-6 in the pathogenesis of COPD remains unknown. The pulmonary expression of BMP-6 was analyzed in patients with COPD and in cigarette smoke (CS)-exposed mice. We evaluated lung function and histology in BMP-6 KO mice at baseline. We exposed BMP-6 KO mice to CS for 4 weeks and measured pulmonary inflammation and iron levels. Pulmonary mRNA levels of BMP-6 were decreased in smokers with and without COPD and in CS-exposed mice. Importantly, BMP-6 expression was lowest in severe COPD. Accordingly, protein levels of BMP-6 were decreased in patients with COPD. Lung function measurements demonstrated a decreased compliance and total lung capacity in BMP-6 KO mice, whereas lung histology was normal. Furthermore, BMP-6 KO mice displayed elevated iron levels and an aggravated CS-induced inflammatory response. These results suggest that BMP-6 is important for normal lung function and that downregulation of BMP-6-as observed in patients with COPD-contributes to pulmonary inflammation after CS exposure. ispartof: MUCOSAL IMMUNOLOGY vol:12 issue:2 pages:340-351 ispartof: location:United States status: published

BACKGROUND: Long-term survival after lung transplantation (LTx) is hampered by chronic lung allograft dysfunction (CLAD). Our study evaluated the prevalence and prognostic importance of obstructive and restrictive CLAD phenotypes, with or without an identifiable underlying cause, to validate the recently proposed classification system for CLAD. METHODS: Data for patients who underwent LTx between 2004 and 2015 with a minimal survival of 180 days post-LTx were retrospectively collected. Double LTx patients with CLAD (defined as a persistent forced expiratory volume in 1 second decline of ≥ 20% compared with baseline) were subsequently classified according to obstructive (forced expiratory volume in 1 second /forced vital capacity [FVC] < 70%, total lung capacity > 90%, and FVC > 80%) or restrictive (total lung capacity ≤ 90% or FVC ≤ 80%) pulmonary function and to the presence of an unknown (bronchiolitis obliterans syndrome [BOS]/restrictive allograft syndrome [RAS]) or known (non-BOS/non-RAS) underlying cause. RESULTS: After a median of 3.2 years, CLAD developed in 39% of double LTx patients (n = 219), of which 20% (n = 43) had an identifiable cause. Survival was worse in patients with restrictive CLAD (26%) compared with obstructive CLAD (64%; p < 0.0001). Non-BOS patients suffered from inferior survival compared with BOS patients (p = 0.0016), whereas there was no significant difference in survival between RAS and non-RAS (p = 0.17). Patients who evolved from an obstructive (BOS) to a restrictive (RAS) phenotype (10%) experienced better survival than RAS patients and a worse outcome compared with BOS patients (p < 0.0001). CONCLUSIONS: Given the differences in outcome, accurate diagnosis of CLAD phenotypes is important, because this helps to inform patients about their prognosis, to reveal underlying pathogenesis, to identify homogenous patient populations for clinical trials, and to guide future therapeutic approaches. ispartof: JOURNAL OF HEART AND LUNG TRANSPLANTATION vol:38 issue:2 pages:166-173 ispartof: location:United States status: published

BACKGROUND: Chronic lung allograft dysfunction (CLAD) hampers long-term survival after lung transplantation. Common fibrosis-related mechanisms in idiopathic pulmonary fibrosis and CLAD instigated the consideration of investigating the differential regulation of pleural mesothelium and transforming growth factor-beta(1) (TGF-beta(1)) in restrictive allograft syndrome (RAS). METHODS: TGF-beta(1) was assessed in bronchoalveolar lavage (BAL) fluid using enzyme-linked immunoassay and via immune staining of explant biopsies. To assess the role of the pleura, explanted bronchiolitis obliterans syndrome (BOS) and RAS lungs were compared using computed tomography scans, calretinin stainings, Western blot, and quantititative real-time PCR. Last, a pleural mesothelial cell line was used to assess mesothelial-to-mesenchymal transition and its inhibition. RESULTS: TGF-beta(1) was increased in BAL of RAS patients (p = 0.035), and was present in the (sub) pleural area of biopsies. Explanted RAS lungs demonstrated an increased volume fraction of pleura (p = 0.0004), a higher proportion of calretinin-positive stainings (p = 0.0032), and decreased E-cadherin (p = 0.019) and increased alpha-smooth muscle actin (p = 0.0089) mRNA expression and protein levels in isolated pleural tissue. Moreover, TGF-beta(1) stimulation of pleural mesothelial cells led to a phenotypical switch to mesenchymal cells, accompanied with an increased migratory capacity. Interleukin-1 alpha was able to accentuate TGF-beta(1). induced mesothelial-to-mesenchymal transition. None of the tested drugs could inhibit mesothelial-to-mesenchymal transition at the used concentrations. CONCLUSIONS: Our results support an interplay between TGF-beta(1) and the pleural mesothelium in the pathophysiology of RAS. (C) 2019 International Society for Heart and Lung Transplantation. All rights reserved.

Survival after lung transplantation (LTx) for idiopathic pulmonary fibrosis (IPF) is worse compared to other indications for LTx. We investigated the effect of several pretransplant variables including the use of pretransplant corticosteroids (CS) on post-transplant graft and chronic lung allograft dysfunction (CLAD)-free survival and functional testing (maximum inspiratory and expiratory pressure, six-minute walk test, quadriceps and hand pinch force) in a small cohort of IPF patients. We retrospectively compared two groups of IPF patients (n = 36 on CS vs. n = 18 not on CS) who underwent LTx between 2000 and 2016. Analysis of 54 IPF-LTx patients showed no significant effect on graft survival or functional tests except for maximum inspiratory pressure (P = 0.033) between these two groups (all LTx patients, CS vs. no CS). Regression analysis showed significant impact of procedure with a hazard ratio of 0.423 (CI 95% 0.194, 0.924) favoring sequential single LTx (SSLTx) compared to single lung transplantation (SLTx). When analyzing only the 40 SSLTx patients, corticosteroid-free patients showed significantly better graft survival compared to patients on CS (P = 0.045) and CLAD-free survival (P = 0.019). The possible detrimental effect of corticosteroid therapy before LTx was demonstrated in this cohort of SSLTx patients, which questions the use of corticosteroids in a pretransplantation setting. ispartof: TRANSPLANT INTERNATIONAL vol:32 issue:4 pages:399-409 ispartof: location:Switzerland status: published

BackgroundConnective tissue growth factor (CTGF) is an important mediator in several fibrotic diseases, including lung fibrosis. We investigated CTGF-expression in chronic lung allograft dysfunction (CLAD) and pulmonary graft-versus-host disease (GVHD).Materials and MethodsCTGF expression was assessed by quantitative real-time polymerase chain reaction (qPCR) and immunohistochemistry in end-stage CLAD explant lung tissue (bronchiolitis obliterans syndrome (BOS), n=20; restrictive allograft syndrome (RAS), n=20), pulmonary GHVD (n=9). Unused donor lungs served as control group (n=20). Next, 60 matched lung transplant recipients (BOS, n=20; RAS, n=20; stable lung transplant recipients, n=20) were included for analysis of CTGF protein levels in plasma and broncho-alveolar lavage (BAL) fluid at 3 months post-transplant, 1 year post-transplant, at CLAD diagnosis or 2 years post-transplant in stable patients.ResultsqPCR revealed an overall significant difference in the relative content of CTGF mRNA in BOS, RAS and pulmonary GVHD vs. controls (p=0.014). Immunohistochemistry showed a significant higher percentage and intensity of CTGF-positive respiratory epithelial cells in BOS, RAS and pulmonary GVHD patients vs. controls (pConclusionsLung CTGF-expression is increased in end-stage CLAD and pulmonary GVHD; and higher CTGF-levels are present in BAL of RAS patients at CLAD diagnosis. Our results suggest a potential role for CTGF in CLAD, especially RAS, and pulmonary GVHD.

BackgroundChronic obstructive pulmonary disease (COPD) is a devastating lung disease, representing the third cause of mortality worldwide. In COPD, the bronchial epithelium displays several structural and functional abnormalities affecting barrier integrity, cell polarity, and differentiation, as well as epithelial-to-mesenchymal transition (EMT) and inflammation. Although COPD is currently considered an irreversible disease, the (ir)reversible nature of epithelium changes ex vivo remains poorly known.MethodsThe persistence of COPD epithelial abnormalities was addressed in very long-term (10 weeks) primary cultures of air/liquid interface (ALI)-reconstituted airway epithelium from non-smoker controls, smoker controls, and COPD patients. The role of inflammation was also explored by stimulating ALI cultures with a cytokine mix consisting of TNF-α, IL-6 and IL-1β. Finally, the cellular niche holding epithelial memory was studied by exploiting a single cell RNA-sequencing database.ResultsAlmost all epithelial defects (barrier dysfunction, impaired polarity, lineage abnormalities) observed in smokers and COPD patients persisted in vitro up to week 10, except IL-8/CXCL-8 release and EMT which declined over time. Cytokine treatment induced COPD-like changes and reactivated EMT in COPD cells. Progenitor cells of large and small airways, namely basal and club cells, exhibited EMT-related signatures reminiscent of features observed in situ.ConclusionsThe airway epithelium from smokers and COPD patients displays a memory of its native state and previous injuries by cigarette smoking, which is multidimensional and sustained for years. This memory probably resides in progenitor cells of the airway epithelium.

BACKGROUND: The transition from normal lung anatomy to minimal and established fibrosis is an important feature of the pathology of idiopathic pulmonary fibrosis (IPF). The purpose of this report is to examine the molecular and cellular mechanisms associated with this transition. METHODS: Pre-operative thoracic Multidetector Computed Tomography (MDCT) scans of patients with severe IPF (n = 9) were used to identify regions of minimal(n = 27) and established fibrosis(n = 27). MDCT, Micro-CT, quantitative histology, and next-generation sequencing were used to compare 24 samples from donor controls (n = 4) to minimal and established fibrosis samples. FINDINGS: The present results extended earlier reports about the transition from normal lung anatomy to minimal and established fibrosis by showing that there are activations of TGFBI, T cell co-stimulatory genes, and the down-regulation of inhibitory immune-checkpoint genes compared to controls. The expression patterns of these genes indicated activation of a field immune response, which is further supported by the increased infiltration of inflammatory immune cells dominated by lymphocytes that are capable of forming lymphoid follicles. Moreover, fibrosis pathways, mucin secretion, surfactant, TLRs, and cytokine storm-related genes also participate in the transitions from normal lung anatomy to minimal and established fibrosis. INTERPRETATION: The transition from normal lung anatomy to minimal and established fibrosis is associated with genes that are involved in the tissue repair processes, the activation of immune responses as well as the increased infiltration of CD4, CD8, B cell lymphocytes, and macrophages. These molecular and cellular events correlate with the development of structural abnormality of IPF and probably contribute to its pathogenesis. ispartof: EBIOMEDICINE vol:66 ispartof: location:Netherlands status: published

Randomized placebo-controlled trials demonstrated the efficacy of antifibrotic treatment in non-IPF progressive fibrosing ILD (fILD). Currently, there is no consensus on how progression should be defined and clinical data of non-IPF fILD patients in a real-world setting are scarce. Non-IPF fILD patients presenting at the University Hospitals Leuven between 2012 and 2016 were included. Different definitions of progression according to the selection criteria of the INBUILD, RELIEF and the uILD study were retrospectively evaluated at every hospital visit. Univariate and multivariate analyses were performed to identify predictors of progression and mortality. The study cohort comprised 120 patients; 68.3%, 54.2% and 65.8% had progressive disease based on the INBUILD, RELIEF and uILD study, respectively. A large overlap of progressive fILD patients according to the different clinical trials was observed. Median transplant-free survival time of progressive fILD patients was 3.9, 3.9, 3.8 years and the median time-to-progression after diagnosis was 2.0, 3.1 and 2.3 years according to the INBUILD, RELIEF and uILD study, respectively. We identified several predictors of mortality, but only an underlying diagnosis of HP and uILD was independently associated with progression. Our data show a high prevalence of progressive fibrosis among non-IPF fILD patients and a discrepancy between predictors of mortality and progression. Mortality rate in fILD is high and the identification of progressive disease is only made late during the disease course. Moreover, future treatment decisions will be based upon disease behavior. Therefore, more predictors of progressive disease are needed to guide treatment decisions in the future.

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death worldwide, with limited therapeutic options available, and no treatment able to reverse disease progression. Importantly, immune cells infiltrating the COPD lung are organized into inducible bronchus-associated lymphoid tissue (iBALT), which drives emphysema progression in humans and mice. iBALT formation requires the interaction of lymphotoxin β receptor (LTβR) on stromal organizer cells with TNF superfamily members lymphotoxin α (LTα) and β (LTβ). Here we investigate the therapeutic potential of iBALT-blockade in COPD pathogenesis. Gene set enrichment analysis (GSEA) of transcriptomics data and qPCR of an independent cohort revealed enrichment of the LTβR signaling pathway in the lungs of COPD patients resulting in increased expression of chemokines like CXCL13. Similar to COPD patients, mice chronically exposed to CS demonstrated iBALT generation and emphysema. Interestingly, LTβR-Ig treatment impaired CS-induced iBALT generation concomitant with the down regulation of chemokines like Cxcl13 and Ccl19. Remarkably, this led to full reversal of emphysema and regression of CS-mediated airway remodeling, which was accompanied by improvement in muscle wasting a prominent comorbidity of COPD. Mechanistically, lung restoration by LTβR-signalling-blockade was accompanied by increased Wnt/beta-catenin signal activity, which was crucial for lung epithelial regeneration. Of physiological relevance, this was validated in primary alveolar epithelial cells, human lung organoids and 3D human precision cut lung slices. Our findings pave the way for therapeutically exploiting the LTβR signalling pathway as a novel approach for activating Wnt signalling and tissue regeneration in chronic inflammatory diseases.

A significant proportion of patients with interstitial lung disease (ILD) may develop a progressive fibrosing phenotype characterized by worsening of symptoms and pulmonary function, progressive fibrosis on chest computed tomography and increased mortality. The clinical course in these patients mimics the relentless progressiveness of idiopathic pulmonary fibrosis (IPF). Common pathophysiological mechanisms such as a shared genetic susceptibility and a common downstream pathway-self-sustaining fibroproliferation-support the concept of a progressive fibrosing phenotype, which is applicable to a broad range of non-IPF ILDs. While antifibrotic drugs became the standard of care in IPF, immunosuppressive agents are still the mainstay of treatment in non-IPF fibrosing ILD (F-ILD). However, recently, randomized placebo-controlled trials have demonstrated the efficacy and safety of antifibrotic treatment in systemic sclerosis-associated F-ILD and a broad range of F-ILDs with a progressive phenotype. This review summarizes the current pharmacological management and highlights the unmet needs in patients with non-IPF ILD. ispartof: JOURNAL OF CLINICAL MEDICINE vol:10 issue:6 ispartof: location:Switzerland status: published

Chronic diffuse parenchymal lung disease (DPLD) is an umbrella term for a very heterogeneous group of lung diseases. Over the last decades, clinical, radiological and histopathological criteria have been established to define and separate these entities. More recently the clinical utility of this approach has been challenged as a unifying concept of pathophysiological mechanisms and a shared response to therapy across the disease spectrum have been described. In this review, we discuss molecular motifs for subtyping and the prediction of prognosis focusing on genetics and markers found in the blood, lavage and tissue. As a purely molecular classification so far lacks sufficient sensitivity and specificity for subtyping, it is not routinely used and not implemented in international guidelines. However, a better molecular characterization of lung disease with a more precise identification of patients with, for example, a risk for rapid disease progression would facilitate more accurate treatment decisions and hopefully contribute to better patients' outcomes.

In recent years, the utility of vascular complement factor 4d (C4d) deposition as diagnostic tool for antibody mediated rejection (AMR) after lung transplantation, has become a controversial issue. We aimed to pinpoint the problematic nature of C4d as biomarker with a simple experiment. We quantified C4d in broncho-alveolar lavage (BAL) of lung transplant patients with diverse post-transplant complications in 3 different settings of clinically clear cases of: 1/ chronic lung allograft dysfunction (CLAD); 2/ acute complications acute rejection (AR), lymphocytic bronchiolitis (LB), antibody-mediated rejection (AMR) and respiratory infection (INF); 3/ patients with parallel C4d immunostaining and Anti-HLA. All groups were compared to BAL of stable patients. C4d was measured via standard ELISA. C4d was increased in CLAD, predominantly in RAS (p = 0.0026) but not in BOS (p = 0.89). C4d was increased in all acute events, AR (p = 0.0025), LB (p

Data concerning sleep-disordered breathing (SDB) after lung transplantation (LTX) are scarce. This study aims to analyze prevalence, associated factors, and impact on survival of moderate to severe SDB in a large cohort of consecutive LTX patients (n = 219). Patients underwent a diagnostic polysomnography 1 year after LTX. Moderate to severe SDB was present in 57.5% of patients, with the highest prevalence in chronic obstructive pulmonary disease/emphysema (71.1%) and pulmonary fibrosis (65.1%). SDB patients were older, mostly male, and had higher body mass index and neck circumference. Nocturnal diastolic and 24-hour blood pressures were higher in SDB patients. In 45 patients, polysomnography was also performed pre-LTX. Compared to pre-LTX, mean apnea/hypopnea index (AHI) increased significantly after LTX. A significant correlation was seen between lung function parameters and AHI, suggesting a role of decreased caudal traction on the pharynx. Presence of SDB had no impact on mortality or prevalence of chronic lung allograft dysfunction. However, survival was better in continuous positive airway pressure (CPAP) compliant SDB patients compared to SDB patients without CPAP treatment. These findings may be pertinent for systematic screening of SDB after LTX. ispartof: AMERICAN JOURNAL OF TRANSPLANTATION vol:21 issue:1 pages:281-290 ispartof: location:United States status: published

Trasplantament de pulmó esquerre porcí; Disfunció primària de l’empelt; Resistència vascular pulmonar Trasplante de pulmón izquierdo porcino; Disfunción primaria del injerto; Resistencia vascular pulmonar Porcine left lung transplantation; Primary graft dysfunction; Pulmonary vascular resistance Background Primary graft dysfunction (PGD) remains a major obstacle after lung transplantation. Ischemia–reperfusion injury is a known contributor to the development of PGD following lung transplantation. We developed a novel approach to assess the impact of increased pulmonary blood flow in a large porcine single-left lung transplantation model. Materials Twelve porcine left lung transplants were divided in two groups (n = 6, in low- (LF) and high-flow (HF) group). Donor lungs were stored for 24 h on ice, followed by left lung transplantation. In the HF group, recipient animals were observed for 6 h after reperfusion with partially clamping right pulmonary artery to achieve a higher flow (target flow 40–60% of total cardiac output) to the transplanted lung compared to the LF group, where the right pulmonary artery was not clamped. Results Survival at 6 h was 100% in both groups. Histological, functional and biological assessment did not significantly differ between both groups during the first 6 h of reperfusion. injury was also present in the right native lung and showed signs compatible with the pathophysiological hallmarks of ischemia–reperfusion injury. Conclusions Partial clamping native pulmonary artery in large animal lung transplantation setting to study the impact of low versus high pulmonary flow on the development of ischemia reperfusion is feasible. In our study, differential blood flow had no effect on IRI. However, our findings might impact future studies with extracorporeal devices and represent a specific intra-operative problem during bilateral sequential single-lung transplantation. AN is supported by the KU Leuven (C24/18/073). AV is sponsored by a fundamental research Grant from the FWO (1102020 N). BMV is funded by the KU Leuven University (C24/15/030 and C16/19/005). SEV is sponsored by a grant from the Research Fund-Flanders (FWO 12G8715N). RV is a senior clinical research fellow of the FWO-Flanders. OCS solution was kindly offered by Transmedics (Andover, MA, USA) without any influence on our study. This research did not receive any other specific grants from funding agencies in the public, commercial, or not-for-profit sectors.

Background In cystic fibrosis, the respiratory epithelium is the target tissue of both the genetic abnormality of the disease and of external aggressions, notably by pathogens (Pseudomonas aeruginosa). A detailed characterisation of the cystic fibrosis bronchial epithelium is however lacking, as most previous studies focused on the nasal epithelium or on cell lines. This study aimed to characterise the abnormal phenotype and epithelial-to-mesenchymal transition in cystic fibrosis bronchial epithelium and to evaluate in cell cultures whether abnormalities persist ex vivo. Methods Explant lung tissues (n = 44) were assessed for bronchial epithelial cell phenotyping by immunostaining. Human bronchial epithelial cells were derived from basal cells isolated from cystic fibrosis patients or control donors and cultured in air-liquid interface for 2, 4 or 6 weeks. Results Enhanced mucin 5AC and decreased β-tubulin expression were observed in cystic fibrosis airways reflecting a decreased ciliated/goblet cell ratio, associated with increased number of vimentin-positive cells, indicating epithelial-to-mesenchymal transition process. These features were recapitulated in vitro, in cystic fibrosis-derived reconstituted epithelium. However, they were not induced by CFTR inhibition or Pseudomonas infection, and most abnormalities tended to disappear in long-term culture (6 weeks) except for increased fibronectin release, an epithelial-to-mesenchymal transition marker. Conclusions This study provides new insights into airway epithelial changes in cystic fibrosis, which are imprinted through an acquired mechanism that we could not relate to CFTR function.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a devastating lung disease, mainly due to cigarette smoking, which represents the third cause of mortality worldwide. The mechanisms driving its epithelial salient features remain largely elusive. We aimed to evaluate the activation and the role of the canonical, β-catenin-dependant WNT pathway in the airway epithelium from COPD patients. METHODS: The WNT/β-catenin pathway was first assessed by WNT-targeted RNA sequencing of the air/liquid interface-reconstituted bronchial epithelium from COPD and control patients. Airway expression of total and active β-catenin was assessed in lung sections, as well as WNT components in laser-microdissected airway epithelium. Finally, we evaluated the role of WNT at the bronchial epithelial level by modulating the pathway in the reconstituted COPD epithelium. FINDINGS: We show that the WNT/β-catenin pathway is upregulated in the COPD airway epithelium as compared with that of non-smokers and control smokers, in targeted RNA-sequencing of in vitro reconstituted airway epithelium, and in situ in lung tissue and laser-microdissected epithelium. Extrinsic activation of this pathway in COPD-derived airway epithelium inhibited epithelial differentiation, polarity and barrier function, and induced TGF-β-related epithelial-to-mesenchymal transition (EMT). Conversely, canonical WNT inhibition increased ciliated cell numbers, epithelial polarity and barrier function, whilst inhibiting EMT, thus reversing COPD features. INTERPRETATION: In conclusion, the aberrant reactivation of the canonical WNT pathway in the adult airway epithelium recapitulates the diseased phenotype observed in COPD patients, suggesting that this pathway or its downstream effectors could represent a future therapeutic target. FUNDING: This study was supported by the Fondation Mont-Godinne, the FNRS and the WELBIO. ispartof: EBIOMEDICINE vol:61 ispartof: location:Netherlands status: published

Background: Familial pulmonary fibrosis (FPF) is a rare condition defined by the presence of at least two first line-relatives with interstitial lung disease (ILD) in one family. The aim of this study was to compare transplant-free survival outcomes from familial IPF (f-IPF) and sporadic IPF (s-IPF) patients. Methods: Clinical characteristics of all IPF patients referred for multidisciplinary expert discussion between 2005 and 2018 were retrospectively collected. Patients were stratified according to a family history of a first-line relative with ILD. Survival in patients with f-IPF was contrasted to s-IPF patients. Results: Within the 750 included IPF patients, 104 f-IPF patients (13.9%) were identified. Compared to s-IPF patients, f-IPF patients were significantly younger (68.7y vs 71.1y; p=0.0046), more frequent females (32.7 vs 20.6%; p=0.0086) and had a significantly more preserved diffusion capacity (DLCO 52.5 vs 48.2%; p=0.0024) at time of diagnosis. Both groups showed no difference in forced vital capacity (FVC) and treatment with antifibrotics. A family history of ILD was a significant risk factor for a worse transplant-free survival (p=0.0209; hazard ratio 1.51) in multivariate analysis by cox-proportional hazard model adjusted for GAP parameters (gender, age, FVC and DLCO) and treatment with antifibrotics. Conclusion: f-IPF patients have a worse transplant-free survival compared to s-IPF patients.

Rationale: Cardiovascular comorbidities are prevalent in patients after lung transplantation (LTX). While sleep apnea is known to be associated with cardiovascular problems, data concerning sleep apnea (SA) after LTX are scarce. The aim of this study is to analyze prevalence, associated factors and impact on survival of moderate to severe SA in a large cohort of consecutive LTX patients. Methods: Patients (n=219, 50,2% females) transplanted between February 2013 and March 2017 underwent a diagnostic polysomnography 1 year after LTX. Results: Moderate to severe SA was present in 57.5% of patients. SA patients were older, mostly male (57.9%) and had a higher BMI and neck circumference. The prevalence of moderate to severe SA was highest in COPD/emphysema patients (86/121; 71.1%) and pulmonary fibrosis (28/43; 65.1%). Nighttime diastolic and 24-hour blood pressures were higher in SA patients. Compared to pre-LTX, mean apnoea/hypopnoea index (AHI) increased significantly after LTX. A significant correlation was seen between lung function parameters and AHI. Presence of SA had no significant impact on mortality or prevalence of chronic lung allograft dysfunction. However, survival was significantly better in CPAP compliant SA patients compared to SA patients without CPAP treatment. Conclusion: The prevalence of SA one year after LTX was high, especially in patients with pre-LTX emphysema and pulmonary fibrosis. SA after LTX was associated with anthropometric, lung function parameters and higher blood pressure. CPAP compliant patients had a better survival than SA patients without CPAP treatment. These findings may ask for systemic screening of SA after LTX.

Background Primary graft dysfunction (PGD) remains a major obstacle after lung transplantation. We developed a novel approach to selectively assess reperfusion injury in transplanted lung and investigated the impact of pulmonary flow.Materials Twelve porcine left lung transplants were divided in two groups (n = 6, in low (LF) and high flow (HF) group). Donor lungs were stored for 24 hours on ice, followed by left lung transplantation. Recipient animals were observed for 6h after reperfusion with partially clamping of right PA in HF group. Results Survival at 6 hours was 100% in both groups. PaO2/FiO2 (P/F) ratio of the transplanted lung was lower (229.1 mmHg vs 308.9 mmHg, p=0.01), mPAP was higher (34.62 mmHg vs 29.88 p=0.01) in HF versus LF group. Wet-to-dry (W/D) ratios of right native and left transplanted lung were not different after 6 h of reperfusion. Conclusions Lung transplantation in large animal settings is feasible. P/F ratio in allograft is dependent on PA flow. Our innovative approach to control blood flow to transplanted lung demonstrates that higher flows induce more PGD and allows to further study development and treatment of PGD. Our findings might have an important impact on sequential intra-operative approach during lung transplantation.

BACKGROUND: Lung transplantation (LTx) requires a calcineurin inhibitor-based immunosuppressive regimen. A once daily (QD) tacrolimus regimen was developed to increase medication adherence. However, data concerning its safety and efficacy in LTx are lacking. METHODS: In this prospective study, stable LTx patients were consecutively converted from twice daily (BID) tacrolimus to QD tacrolimus on a 1 mg:1 mg basis. Trough level (Cmin), renal function, cholesterol, fasting glucose, potassium and lung function were monitored six months before and up to one year after conversion. Adherence and its barriers were assessed by self-reported questionnaires (Basel Assessment of Adherence to Immunosuppressive Medications Scale (BAASIS) and Identification of Medication Adherence Barriers questionnaire (IMAB)) and blood-based assays (mean Cmin and coefficient of variation (CV)). RESULTS: We included 372 patients, in whom we observed a decrease in tacrolimus Cmin of 18.5% (p < 0.0001) post-conversion, requiring subsequent daily dose adaptations in both cystic fibrosis (CF) (n = 72) and non-CF patients (n = 300). We observed a small decrease in eGFR one year post-conversion (p = 0.024). No significant changes in blood creatinine, potassium, fasting glucose, cholesterol or rate of lung function decline were observed. In a subgroup of 166 patients, significantly fewer patients missed doses (8.4% vs. 19.3%, p = 0.016) or had irregular intake post-conversion (19.3% vs. 32.5%, p = 0.019). Mean Cmin and CV, as well as the total number of barriers, also decreased significantly post-conversion. CONCLUSIONS: In LTx, conversion from BID to QD tacrolimus (1 mg:1 mg) requires close monitoring of tacrolimus Cmin. QD tacrolimus after transplantation is safe with respect to renal function, metabolic parameters and allograft function and improves LTx recipient adherence. ispartof: JOURNAL OF HEART AND LUNG TRANSPLANTATION vol:40 issue:6 pages:467-477 ispartof: location:United States status: published

Pulmonary veno-occlusive disease (PVOD) occurs in humans either as a heritable form (hPVOD) due to biallelic inactivating mutations of EIF2AK4 (encoding GCN2) or as a sporadic form in older age (sPVOD). The chemotherapeutic agent mitomycin C (MMC) is a potent inducer of PVOD in humans and in rats (MMC-PVOD). Here, we compared human hPVOD and sPVOD, and MMC-PVOD pathophysiology at the histological, cellular, and molecular levels to unravel common altered pathomechanisms. MMC exposure in rats was associated primarily with arterial and microvessel remodeling, and secondarily by venous remodeling, when PVOD became symptomatic. In all forms of PVOD tested, there was convergent GCN2-dependent but eIF2α-independent pulmonary protein overexpression of HO-1 (heme oxygenase 1) and CHOP (CCAAT-enhancer-binding protein [C/EBP] homologous protein), two downstream effectors of GCN2 signaling and endoplasmic reticulum stress. In human PVOD samples, CHOP immunohistochemical staining mainly labeled endothelial cells in remodeled veins and arteries. Strong HO-1 staining was observed only within capillary hemangiomatosis foci, where intense microvascular proliferation occurs. HO-1 and CHOP stainings were not observed in control and pulmonary arterial hypertension lung tissues, supporting the specificity for CHOP and HO-1 involvement in PVOD pathobiology. In vivo loss of GCN2 (EIF2AK4 mutations carriers and Eif2ak4-/- rats) or in vitro GCN2 inhibition in cultured pulmonary artery endothelial cells using pharmacological and siRNA approaches demonstrated that GCN2 loss of function negatively regulates BMP (bone morphogenetic protein)-dependent SMAD1/5/9 signaling. Exogenous BMP9 was still able to reverse GCN2 inhibition-induced proliferation of pulmonary artery endothelial cells. In conclusion, we identified CHOP and HO-1 inhibition, and BMP9, as potential therapeutic options for PVOD. ispartof: AMERICAN JOURNAL OF RESPIRATORY CELL AND MOLECULAR BIOLOGY vol:63 issue:1 pages:118-131 ispartof: location:United States status: published

Lymphangioleiomyomatosis (LAM) is a rare, cystic lung disease with progressive pulmonary function loss caused by progressively proliferating LAM cells. The degree of airway obstruction has not been well investigated within the pathogenesis of LAM. Using a combination of ex vivo computed tomography (CT), microCT and histology, the site and nature of airway obstruction in LAM explant lungs was compared with matched control lungs (n=5 each). The total number of airways per generation, total airway counts, terminal bronchioles number and surface density were compared in LAM versus control. Ex vivo CT analysis demonstrated a reduced number of airways from generation 7 on (p, This study demonstrates a 4-fold reduction in the number of airways and terminal bronchioles in end-stage LAM lungs using a combination of CT, microCT and histopathology, compared to a matched control group http://bit.ly/2tBTiJy

Background Ex vivo lung perfusion (EVLP) is a widespread accepted platform for preservation and evaluation of donor lungs prior to lung transplantation (LTx). Standard lungs are ventilated using volume-controlled ventilation (VCV). We investigated the effects of flow-controlled ventilation (FCV) in a large animal EVLP model. Fourteen porcine lungs were mounted on EVLP after a warm ischemic interval of 2 h and randomized in two groups (n = 7/group). In VCV, 7 grafts were conventionally ventilated and in FCV, 7 grafts were ventilated by flow-controlled ventilation. EVLP physiologic parameters (compliance, pulmonary vascular resistance and oxygenation) were recorded hourly. After 6 h of EVLP, broncho-alveolar lavage (BAL) was performed and biopsies for wet-to-dry weight (W/D) ratio and histology were taken. The left lung was inflated, frozen in liquid nitrogen vapors and scanned with computed tomography (CT) to assess regional distribution of Hounsfield units (HU). Results All lungs endured 6 h of EVLP. Oxygenation was better in FCV compared to VCV (p = 0.01) and the decrease in lung compliance was less in FCV (p = 0.03). W/D ratio, pathology and BAL samples did not differ between both groups (p = 0.16, p = 0.55 and p = 0.62). Overall, CT densities tended to be less pronounced in FCV (p = 0.05). Distribution of CT densities revealed a higher proportion of well-aerated lung parts in FCV compared to VCV (p = 0.01). Conclusions FCV in pulmonary grafts mounted on EVLP is feasible and leads to improved oxygenation and alveolar recruitment. This ventilation strategy might prolong EVLP over time, with less risk for volutrauma and atelectrauma.