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Objective: To describe our experience with lung transplantation (LTx) from donors ≥70 years and compare short and long-term outcomes to a propensity-matched cohort of donors <70 years., Background: Although extended-criteria donors have been widely used to enlarge the donor pool, the experience with LTx from older donors (≥70 years) remains limited., Methods: All single-center bilateral LTx between 2010 and 2020 were retrospectively analyzed. Matching (1:1) was performed for the donor (type, sex, smoking history, x-ray abnormalities, partial pressure of oxygen/fraction of inspired oxygen ratio, and time on ventilator) and recipient characteristics (age, sex, LTx indication, perioperative extracorporeal life support, and cytomegalovirus mismatch). Primary graft dysfunction grade-3, 5-year patient, and chronic lung allograft dysfunction-free survival were analyzed., Results: Out of 647 bilateral LTx, 69 were performed from donors ≥70 years. The mean age in the older donor cohort was 74 years (range: 70-84 years) versus 49 years (range: 12-69 years) in the matched younger group. No significant differences were observed in the length of ventilatory support, intensive care unit, or hospital stay. Primary graft dysfunction-3 was 26% in the older group versus 29% in younger donor recipients ( P = 0.85). Reintervention rate was comparable (29% vs 16%; P = 0.10). Follow-up bronchoscopy revealed no difference in bronchial anastomotic complications ( P = 1.00). Five-year patient and chronic lung allograft dysfunction-free survivals were 73.6% versus 73.1% ( P = 0.72) and 51.5% versus 59.2% ( P = 0.41), respectively., Conclusions: LTx from selected donors ≥70 years is feasible and safe, yielding comparable short and long-term outcomes in a propensity-matched analysis with younger donors (<70 years)., Competing Interests: R.V. is supported as a senior clinical research fellow by the Research Foundation Flanders (FWO) Belgium. G.M.V. and D.V.R. are supported by the Broere Charitable Foundation. L.J.C. is supported by a KU Leuven University Chair funded by Medtronic, a post-doctoral grant from the University Hospitals Leuven (KOOR—UZ Leuven) and a research project from the Research Foundation Flanders (FWO) Belgium (G090922N). The remaining authors report no conflicts of interest., (Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc.)

Primary graft dysfunction (PGD) is a major obstacle after lung transplantation (LTx), associated with increased early morbidity and mortality. Studies in liver and kidney transplantation revealed prolonged anastomosis time (AT) as an independent risk factor for impaired short- and long-term outcomes. We investigated if AT during LTx is a risk factor for PGD. In this retrospective single-center cohort study, we included all first double lung transplantations between 2008 and 2016. The association of AT with any PGD grade 3 (PGD3) within the first 72 h post-transplant was analyzed by univariable and multivariable logistic regression analysis. Data on AT and PGD was available for 427 patients of which 130 (30.2%) developed PGD3. AT was independently associated with the development of any PGD3 ≤72 h in uni- (odds ratio [OR] per 10 min 1.293, 95% confidence interval [CI 1.136-1.471], p < .0001) and multivariable (OR 1.205, 95% CI [1.022-1.421], p = .03) logistic regression analysis. There was no evidence that the relation between AT and PGD3 differed between lung recipients from donation after brain death versus donation after circulatory death donors. This study identified AT as an independent risk factor for the development of PGD3 post-LTx. We suggest that the implantation time should be kept short and the lung cooled to decrease PGD-related morbidity and mortality post-LTx., (© 2022 The American Society of Transplantation and the American Society of Transplant Surgeons.)

Primary graft dysfunction (PGD) is the clinical syndrome of acute lung injury after lung transplantation (LTx). However, PGD is an umbrella term that encompasses the ongoing pathophysiological and -biological mechanisms occurring in the lung grafts. Therefore, we aim to provide a focused review on the clinical, physiological, radiological, histological and cellular level of PGD. PGD is graded based on hypoxemia and chest X-ray (CXR) infiltrates. High-grade PGD is associated with inferior outcome after LTx. Lung edema is the main characteristic of PGD and alters pulmonary compliance, gas exchange and circulation. A conventional CXR provides a rough estimate of lung edema, while a chest computed tomography (CT) results in a more in-depth analysis. Macroscopically, interstitial and alveolar edema can be distinguished below the visceral lung surface. On the histological level, PGD correlates to a pattern of diffuse alveolar damage (DAD). At the cellular level, ischemia-reperfusion injury (IRI) is the main trigger for the disruption of the endothelial-epithelial alveolar barrier and inflammatory cascade. The multilevel approach integrating all PGD-related aspects results in a better understanding of acute lung failure after LTx, providing novel insights for future therapies.

Background: Chronic Lung Allograft Dysfunction (CLAD) is a major obstacle for long term survival after lung transplantation (LTx). Besides Bronchiolitis Obliterans Syndrome, two other phenotypes of CLAD, restrictive allograft syndrome (RAS) and mixed phenotype, have been described. Trials to test in these conditions are desperately needed and analyzing natural outcome to plan such trials is essential., Methods: We performed a retrospective analysis of functional outcome in bilateral LTx recipients with RAS and mixed phenotype, transplanted between 2009 and 2018 in five large European centers with follow- up spirometry up to 12 months after diagnosis. Based on these data, sample size and power calculations for randomized therapeutic trial was estimated using two imputation methods for missing values., Results: Seventy patients were included (39 RAS and 31 mixed phenotype), median 3.1 years after LTx when CLAD was diagnosed. Eight, 13 and 25 patients died within 6, 9 and 12 months after diagnosis and a two patients underwent re-transplantation within 12 months leading to a graft survival of 89, 79 and 61% six, nine and 12 months after diagnosis, respectively. Observed FEV1 decline was 451 ml at 6 months and stabilized at 9 and 12 months, while FVC showed continuous decline. Using two methods of imputation, a progressive further decline after 6 months for FEV1 was noted., Conclusion: The poor outcome of these two specific CLAD phenotypes suggests the urgent need for future therapeutic randomized trials. The number of missing values in a potential trial seems to be high and most frequently attributed to death. Survival may be used as an endpoint in clinical trials in these distinct phenotypes and imputation techniques are relevant if graft function is used as a surrogate of disease progression in future trials., Competing Interests: The authors have declared that no competing interests exist.

Objectives: Primary graft dysfunction (PGD) remains a major post-transplant complication and is associated with increased morbidity and mortality. Mechanisms evoking PGD are not completely clear, but inflammation plays a central role. We investigated the association between PGD and inflammatory proteins present in immediate postoperative bronchoalveolar lavage., Methods: All double-lung recipients transplanted at our institution from 2002 to 2018 were included in our study. We retrospectively selected 80 consecutive lung transplant recipients with different PGD grades (n = 20 for each PGD grades 0-1 to 2-3). In bronchoalveolar lavage performed within the first 24 h after donor aortic cross-clamping following lung transplantation, concentrations of 30 cytokines, chemokines and growth factors were assessed by enzyme-linked immunosorbent assay (ELISA) and correlated with donor and recipient demographics and outcomes. For analysis, 2 groups were defined: 'mild' PGD (grade 0-1) and 'severe' PGD (grades 2-3)., Results: Significant differences between mild and severe PGD were found in 8 biomarkers [interleukin (IL)-6, IL-10, IL-13, eotaxin, granulocyte colony-stimulating factor, interferon γ, macrophage inflammatory protein 1α, surfactant protein D (SP-D); P < 0.05]. Increased IL-10 and IL-13, but none of the other proteins, were associated with short-term outcome (longer time to extubation; P = 0.005 and P < 0.0001; increased intensive care unit stay; P = 0.012 and P < 0.0001; and hospital stay; P = 0.041 and P = 0.002). There were no significant differences in donor and recipient characteristics between the groups., Conclusions: Expression profiles of key inflammatory mediators in bronchoalveolar lavage fluid differed significantly between lung transplant recipients with severe versus mild PGD and correlated with clinical outcome variables. Further research should focus on the early mechanisms leading to PGD., (© The Author(s) 2020. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.)

Rationale: Patients can change chronic lung allograft dysfunction (CLAD) phenotype, especially from BOS to mixed phenotype. Our aim was to further characterize these patients., Method: Mixed CLAD was defined as a restrictive physiology with persistent CT opacities, after initial bronchiolitis obliterans syndrome (BOS) diagnosis. The incidence, prognosis, pulmonary function, radiology, pathology, and airway inflammation were compared between patients with restrictive allograft syndrome (RAS) and mixed CLAD., Result: A total of 268 (44%) patients developed CLAD of which 47 (18%) were diagnosed with RAS "ab initio," 215 (80%) with BOS, and 6 (2%) an undefined phenotype. Twenty-five patients developed a mixed CLAD phenotype (24 BOS to mixed and 1 RAS to mixed). Survival after mixed phenotype diagnosis was comparable (P = .39) to RAS. More emphysema patients developed a mixed phenotype (P = .020) compared to RAS ab initio, while mixed CLAD patients had a lower FEV 1 (P < .0001) and FEV 1 /FVC (P = .0002) at diagnosis compared to RAS ab initio. CT scans in patients with the mixed phenotype demonstrated apical predominance of the opacities (P = .0034) with pleuroparenchymal fibroelastosis on histopathology., Conclusion: We further characterized patients with a mixed phenotype of CLAD. Although the survival after diagnosis was comparable to RAS ab initio patients, there was a difference in demography, pulmonary function, radiology, and pathology., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Chronic lung allograft dysfunction (CLAD) is the single most important factor limiting long-term survival after lung transplantation (LTx). Azithromycin has been shown to improve CLAD-free and long-term survival, yet the possible impact on early lung allograft function is unclear., Methods: A prospective, randomized, double-blind, placebo-controlled trial of pre-transplant and prompt post-transplant azithromycin treatment was performed at the University Hospitals Leuven. In each arm, 34 patients, transplanted between October 2013 and October 2015, were included for analysis. Study drug was added to standard of care and was administered once before LTx (1,000 mg of azithromycin or placebo) and every other day from Day 1 until Day 31 after LTx (250 mg of azithromycin or placebo). Primary outcome was an anticipated 15% improvement of forced expiratory volume in 1 second (FEV 1 , percent predicted) during the first 3 months post-LTx. Secondary end-points included length of intubation, days on ventilator, duration of intensive care unit and hospital stay, prevalence and severity of primary graft dysfunction, acute rejection, infection, and CLAD-free and overall survival., Results: FEV 1 was not significantly different between the 2 groups (p = 0.41). Patients treated with azithromycin demonstrated less airway inflammation, with lower bronchoalveolar lavage (BAL) neutrophilia and BAL interleukin-8 protein levels at Day 30 (p = 0.09 and p = 0.04, respectively) and Day 90 (p = 0.002 and p = 0.08, respectively) after LTx. Other secondary outcomes were not significantly different between placebo and azithromycin groups., Conclusions: Pre-transplant and prompt post-transplant azithromycin treatment was not able to improve early lung allograft function. However, the known anti-inflammatory properties of azithromycin were confirmed (NCT01915082)., (Copyright © 2018 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.)

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., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Pirfenidone may attenuate the decline of pulmonary function in restrictive allograft syndrome (RAS) after lung transplantation. We retrospectively assessed all lung transplant recipients with RAS who were treated with pirfenidone for at least 3 months (n = 11) in our lung transplant center and report on their long-term outcomes following initiation of pirfenidone. Main outcome parameters included evolution of pulmonary function and overall survival. Pirfenidone appears to attenuate the decline in forced vital capacity and forced expiratory volume in 1 second. Notably, 3 patients were bridged to redo-transplantation with pirfenidone for 11 (5-12) months and are currently alive, while 3 other patients demonstrate long-term stabilization of pulmonary function after 26.6 (range 18.4-46.6) months of treatment. Median overall 3-year survival after RAS diagnosis was 54.5%. Subjective intolerance, mainly anorexia and nausea, necessitating pirfenidone dose de-escalation in 55% of patients, as well as calcineurin dose increase requirements with about 20% are important complications during pirfenidone treatment after lung transplantation. Our findings provide further evidence that pirfenidone appears to be safe and may attenuate the rate of decline in lung function in patients with RAS, but the actual clinical benefit cannot be assessed in the context of this study design and requires further investigation in a larger randomized trial., (© 2018 The American Society of Transplantation and the American Society of Transplant Surgeons.)

Introduction: Previous studies demonstrated that increased cytokine and chemokine levels, either shortly before or after lung transplantation, were associated with post-transplant outcome. However, small patient cohorts were mostly used, focusing on 1 molecule and 1 outcome. In a large single-center cohort, we investigated the predictive value of immediate post-operative broncho-alveolar lavage (BAL) expression of IL-6 and IL-8 on multiple key outcomes, including PGD, CLAD, graft survival, as well as several secondary outcomes., Material and Methods: All patients undergoing a first lung transplant in whom routine bronchoscopy with BAL was performed during the first 48 hours post-transplantation were included. IL-6 and IL-8 protein levels were measured in BAL via ELISA., Results: A total of 336 patients were included. High IL-6 levels measured within 24 hours of transplantation were associated with longer time on ICU and time to hospital discharge; and increased prevalence of PGD grade 3. Increased IL-8 levels, measured within 24 hours, were associated with PGD3, more ECMO use, higher donor paO 2 , younger donor age, but not with other short-or long-term outcome. IL-6 and IL-8 measured between 24 and 48 hours of transplantation were not associated with any outcome parameters., Conclusion: Recipient BAL IL-6 and IL-8 within 24 hours post-transplant were associated with an increased incidence of PGD3., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Vitamin D may have innate immunomodulatory functions with potentially beneficial therapeutic effects in lung transplant recipients., Methods: This was a single-center, double blind, randomized, placebo-controlled, prevention trial of once-monthly oral vitamin D (cholecalciferol; 100,000 IU, n = 44) vs placebo (n = 43) during 2 years in adult lung transplant recipients enrolled from October 2010 to August 2013. Primary outcome was prevalence of chronic lung allograft dysfunction (CLAD) 3 years after transplantation. Secondary outcomes included overall survival, prevalence of acute rejection, lymphocytic bronchiolitis and infection, lung function, pulmonary and systemic inflammation, and bone mineral density., Results: All included patients underwent bilateral lung transplantation and were mostly middle-aged men with prior smoking-related emphysema. Levels of 25-hydroxy vitamin D after 1 year (p < .001) and 2 years (p < .001) were significantly higher in the vitamin D group compared with the placebo group. No difference was observed for CLAD prevalence (p = 0.7) or CLAD-free survival between both groups (p = 0.7). Secondary outcomes were overall comparable between both groups (all p > 0.05)., Conclusions: Once-monthly oral vitamin D supplementation after lung transplantation fails to demonstrate a significant difference in CLAD prevalence, innate immunomodulatory, or a beneficial clinical effect compared with placebo., (Copyright © 2017 International Society for the Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.)

Background: Primary graft dysfunction (PGD) is considered to be the end result of an inflammatory response targeting the new lung allograft after transplant. Previous research has indicated that MAPC cell therapy might attenuate this injury by its paracrine effects on the pro-/anti-inflammatory balance. This study aims to investigate the immunoregulatory capacities of MAPC cells in PGD when administered in the airways., Methods: Lungs of domestic pigs (n = 6/group) were subjected to 90 minutes of warm ischemia. Lungs were cold flushed, cannulated on ice and placed on EVLP for 6 hours. At the start of EVLP, 40 ml of an albumin-plasmalyte mixture was distributed in the airways (CONTR group). In the MAPC cell group, 150 million MAPC cells (ReGenesys/Athersys, Cleveland, OH, USA) were added to this mixture. At the end of EVLP, a physiological evaluation (pulmonary vascular resistance, lung compliance, PaO 2 /FiO 2 ), wet-to-dry weight ratio (W/D) sampling and a multiplex analysis of bronchoalveolar lavage (BAL) (2 × 30 ml) was performed., Results: Pulmonary vascular resistance, lung compliance, PaO 2 /FiO 2 and W/D were not statistically different at the end of EVLP between both groups. BAL neutrophilia was significantly reduced in the MAPC cell group. Moreover, there was a significant decrease in TNF-α, IL-1β and IFN-γ in the BAL, but not in IFN-α; whereas IL-4, IL-10 and IL-8 were below the detection limit., Conclusions: Although no physiologic effect of MAPC cell distribution in the airways was detected during EVLP, we observed a reduction in pro-inflammatory cytokines and neutrophils in BAL in the MAPC cell group. This effect on the innate immune system might play an important role in critically modifying the process of PGD after transplantation. Further experiments will have to elucidate the immunoregulatory effect of MAPC cell administration on graft function after transplantation.

Air pollution from road traffic is a serious health risk, especially for susceptible individuals. Single-centre studies showed an association with chronic lung allograft dysfunction (CLAD) and survival after lung transplantation, but there are no large studies.13 lung transplant centres in 10 European countries created a cohort of 5707 patients. For each patient, we quantified residential particulate matter with aerodynamic diameter ≤10 µm (PM 10 ) by land use regression models, and the traffic exposure by quantifying total road length within buffer zones around the home addresses of patients and distance to a major road or freeway.After correction for macrolide use, we found associations between air pollution variables and CLAD/mortality. Given the important interaction with macrolides, we stratified according to macrolide use. No associations were observed in 2151 patients taking macrolides. However, in 3556 patients not taking macrolides, mortality was associated with PM 10 (hazard ratio 1.081, 95% CI 1.000-1.167); similarly, CLAD and mortality were associated with road lengths in buffers of 200-1000 and 100-500 m, respectively (hazard ratio 1.085- 1.130). Sensitivity analyses for various possible confounders confirmed the robustness of these associations.Long-term residential air pollution and traffic exposure were associated with CLAD and survival after lung transplantation, but only in patients not taking macrolides., (Copyright ©ERS 2017.)

Chronic lung allograft dysfunction (CLAD) remains the major barrier to long-term success after lung transplantation. This report compares gross and microscopic features of lungs removed from patients receiving a redo-transplant as treatment for CLAD. Lungs donated by patients with either the bronchiolitis obliterans syndrome (BOS) or restrictive allograft syndrome (RAS) phenotype of CLAD and appropriate control lungs (eight per group) were air-inflated, frozen solid and kept frozen while a multi-detector computed tomography (MDCT) was obtained. The lung was then cut into 2-cm thick transverse slices and sampled for micro-CT and histopathology. The MDCT showed reduced lung volume with increased lung weight and density in RAS versus BOS and control (p<0.05). Although pre-terminal bronchioles were obstructed in both phenotypes, RAS lungs showed a reduction of pre-terminal bronchioles (p<0.01). Micro-CT and matched histopathology showed that RAS was associated with reduced numbers of terminal bronchioles/lung compared to BOS and controls (p<0.01), with expansion of the interstitial compartment and obliteration of the alveolar airspaces by fibrous connective tissue. RAS is associated with greater destruction of both pre-terminal and terminal bronchioles. Additionally, the interstitial compartments are expanded and alveolar airspaces are obliterated by accumulation of fibrous connective tissue., (Copyright ©ERS 2015.)

Background: Primary graft dysfunction (PGD), with an incidence of 11% to 57%, is a major cause of morbidity and mortality within the first 30 days after lung transplantation (LTx). In this study, we postulate that recipient genetic variants in interleukin-17 and -23 receptor genes (IL-17R and IL-23R, respectively) may predispose LTx recipients to an increased risk for developing PGD., Methods: Seven genetic variants of IL-17R and IL-23R were successfully genotyped in 431 lung transplant recipients. Our primary end-point was PGD and secondary end-points were time to extubation, intensive care unit (ICU) stay, bronchoalveolar lavage neutrophilia and serum C-reactive protein., Results: The AA genotype of the rs882643 genetic variant of IL-17R was associated with higher PGD grades at 0 hour (adjusted p = 0.042), 12 hours (adjusted p = 0.013) and 48 hours (adjusted p = 0.0092) after LTx. The GG genotype of the rs2241049 genetic variant of IL-17R was associated with higher PGD grades at 48 hours (adjusted p = 0.0067) after LTx. For both genetic variants, no association was found with extubation time, ICU stay, post-operative BAL neutrophilia, serum CRP, chronic lung allograft dysfunction (CLAD) or graft loss., Conclusion: Both genetic variants of IL-17R (rs882643 and rs2241049) were associated with PGD. This confirms a genetic predisposition toward PGD and suggests a role of IL-17 in driving neutrophilia in PGD., (Copyright © 2015 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.)

There is increasing knowledge that patients can be predisposed to a certain disease by genetic variations in their DNA. Extensive genetic variation has been described in molecules involved in short- and long-term complications after lung transplantation (LTx), such as primary graft dysfunction (PGD), acute rejection, respiratory infection, chronic lung allograft dysfunction (CLAD), and mortality. Several of these studies could not be confirmed or were not reproduced in other cohorts. However, large multicenter prospective studies need to be performed to define the real clinical consequence and significance of genotyping the donor and receptor of a LTx. The current review presents an overview of genetic polymorphisms (SNP) investigating an association with different complications after LTx. Finally, the major drawbacks, clinical relevance, and future perspectives will be discussed.

Lung transplantation is currently considered as an ultimate live-saving treatment for selected patients suffering from end-stage pulmonary disease. Long-term survival, however, is hampered by chronic rejection, or chronic lung allograft dysfunction (CLAD). Recently, various phenotypes within CLAD have been identified, challenging the established clinical definition of bronchiolitis obliterans syndrome (BOS). Some patients with presumed BOS, for instance, demonstrate an important improvement in forced expiratory volume in the first second of expiration (FEV1) after treatment with azithromycin. These patients are characterized by the presence of excess (≥ 15%) bronchoalveolar lavage (BAL) neutrophils, in absence of concurrent infection. This phenotype of CLAD has been redefined as neutrophilic reversible allograft dysfunction (NRAD), and these patients generally have a very good prognosis after diagnosis. Another group of patients with CLAD develop a restrictive rather than an obstructive pulmonary function defect (defined as a decline in total lung capacity of at least 10%) and demonstrate persistent interstitial and ground-glass opacities on chest computed tomographic (CT) scan. This phenotype is called restrictive allograft syndrome (RAS), and patients with RAS have a much worse prognosis after diagnosis. This review further discusses both of these CLAD phenotypes that do not fit the classical definition of BOS. Potential pathophysiological mechanisms, etiology, diagnosis, prognosis, and treatments are discussed., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Background: Chronic lung allograft dysfunction (CLAD) remains a major risk factor for death after lung transplantation. Previous data suggested that within CLAD at least 2 phenotypes are present: a neutrophilic type (nCLAD or neutrophilic reversible allograft dysfunction [NRAD]), reversible with azithromycin therapy, vs a low neutrophilic type, non-responsive to azithromycin (fibrotic bronchiolitis obliterans syndrome [fBOS]). We aimed to further characterize this dichotomy by measuring multiple proteins in the bronchoalveolar lavage (BAL) fluid of 28 lung recipients., Methods: Patients were retrospectively subdivided by the absence or presence of CLAD and subsequently by their response to azithromycin, resulting in 3 groups: 10 stable, 9 responsive (nCLAD/NRAD), and 9 non-responsive (fBOS). Enzyme-linked immunosorbent assay was used to measure 32 different proteins., Results: Protein variations were predominantly present in the nCLAD/NRAD group, whereas no differences were observed in the fBOS group compared with control. MCP-1 (p < 0.01), RANTES (p < 0.05), IL-1β (p < 0.01), IL-8 (p < 0.01), TIMP-1 (p < 0.01), MMP-8 (p < 0.01), MMP-9 (p < 0.01), HGF (p < 0.001), MPO (p < 0.01), and bile acid (p < 0.05) concentrations were upregulated in nCLAD/NRAD compared with fBOS, whereas PDGF-AA (p < 0.05) was downregulated., Conclusions: These data provide further evidence that within CLAD there is a heterogeneity of phenotypes with different mechanisms involved. Further investigation is warranted to unravel the pathophysiology of both phenotypes., (Copyright © 2011 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.)