Preparation of large biological samples for high-resolution, hierarchical, synchrotron phase-contrast tomography with multimodal imaging compatibility.

Imaging across different scales is essential for understanding healthy organ morphology and pathophysiological changes. The macro- and microscale three-dimensional morphology of large samples, including intact human organs, is possible with X-ray microtomography (using laboratory or synchrotron sources). Preparation of large samples for high-resolution imaging, however, is challenging due to limitations such as sample shrinkage, insufficient contrast, movement of the sample and bubble formation during mounting or scanning. Here, we describe the preparation, stabilization, dehydration and mounting of large soft-tissue samples for X-ray microtomography. We detail the protocol applied to whole human organs and hierarchical phase-contrast tomography at the European Synchrotron Radiation Facility, yet it is applicable to a range of biological samples, including complete organisms. The protocol enhances the contrast when using X-ray imaging, while preventing sample motion during the scan, even with different sample orientations. Bubbles trapped during mounting and those formed during scanning (in the case of synchrotron X-ray imaging) are mitigated by multiple degassing steps. The sample preparation is also compatible with magnetic resonance imaging, computed tomography and histological observation. The sample preparation and mounting require 24-36 d for a large organ such as a whole human brain or heart. The preparation time varies depending on the composition, size and fragility of the tissue. Use of the protocol enables scanning of intact organs with a diameter of 150 mm with a local voxel size of 1 µm. The protocol requires users with expertise in handling human or animal organs, laboratory operation and X-ray imaging.

The role of miR-155 in cigarette smoke-induced pulmonary inflammation and COPD.

Chronic obstructive pulmonary disease (COPD) is a highly prevalent respiratory disease characterized by airflow limitation and chronic inflammation. MiR-155 is described as an ancient regulator of the immune system. Our objective was to establish a role for miR-155 in cigarette smoke (CS)-induced inflammation and COPD. We demonstrate increased miR-155 expression by RT-qPCR in lung tissue of smokers without airflow limitation and patients with COPD compared to never smokers and in lung tissue and alveolar macrophages of CS-exposed mice compared to air-exposed mice. In addition, we exposed wild type and miR-155 deficient mice to CS and show an attenuated inflammatory profile in the latter. Alveolar macrophages were sorted by FACS from the different experimental groups and their gene expression profile was analyzed by RNA sequencing. This analysis revealed increased expression of miR-155 targets and an attenuation of the CS-induced increase in inflammation-related genes in miR-155 deficient mice. Moreover, intranasal instillation of a specific miR-155 inhibitor attenuated the CS-induced pulmonary inflammation in mice. Finally, elastase-induced emphysema and lung functional changes were significantly attenuated in miR-155 deficient mice. In conclusion, we highlight a role for miR-155 in CS-induced inflammation and the pathogenesis of COPD, implicating miR-155 as a new therapeutic target in COPD.

Bone morphogenetic protein 6 (BMP-6) modulates lung function, pulmonary iron levels and cigarette smoke-induced inflammation.

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.

An optimized non-destructive protocol for testing mechanical properties in decellularized rabbit trachea.

Successful tissue-engineered tracheal transplantation relies on the use of non-immunogenic constructs, which can vascularize rapidly, support epithelial growth, and retain mechanical properties to that of native trachea. Current strategies to assess mechanical properties fail to evaluate the trachea to its physiological limits, and lead to irreversible destruction of the construct. Our aim was to develop and evaluate a novel non-destructive method for biomechanical testing of tracheae in a rabbit decellularization model. To validate the performance of this method, we simultaneously analyzed quantitative and qualitative graft changes in response to decellularization, as well as in vivo biocompatibility of implanted scaffolds. Rabbit tracheae underwent two, four and eight cycles of detergent-enzymatic decellularization. Biomechanical properties were analyzed by calculating luminal volume of progressively inflated and deflated tracheae with microCT. DNA, glycosaminoglycan and collagen contents were compared to native trachea. Scaffolds were prelaminated in vivo. Native, two- and four-cycle tracheae showed equal mechanical properties. Collapsibility of eight-cycle tracheae was significantly increased from -40cm H2O (-3.9kPa). Implantation of two- and four-cycle decellularized scaffolds resulted in favorable flap-ingrowth; eight-cycle tracheae showed inadequate integration. We showed a more limited detergent-enzymatic decellularization successfully removing non-cartilaginous immunogenic matter without compromising extracellular matrix content or mechanical stability. With progressive cycles of decellularization, important loss of functional integrity was detected upon mechanical testing and in vivo implantation. This instability was not revealed by conventional quantitative nor qualitative architectural analyses. These experiments suggest that non-destructive, functional evaluation, e.g. by microCT, may serve as an important tool for mechanical screening of scaffolds before clinical implementation. STATEMENT OF SIGNIFICANCE: Decellularization is a front-running strategy to generate scaffolds for tracheal tissue-engineering. Preservation of biomechanical properties of the trachea during this process is paramount to successful clinical transplantation. In this paper, we evaluated a novel method for biomechanical testing of decellularized trachea. We detected important loss of functional integrity with progressive cycles of decellularization. This instability was not revealed by our quantitative nor qualitative analyses. These experiments suggest that the technique might serve as a performant, non-destructive tool for mechanical screening of scaffolds before clinical implementation.

Radiological Analysis of Unused Donor Lungs: A Tool to Improve Donor Acceptance for Transplantation?

Despite donor organ shortage, a large proportion of possible donor lungs are declined for transplantation. Criteria for accepting/declining lungs remain controversial because of the lack of adequate tools to aid in decision-making. We collected, air-inflated, and froze a large series of declined/unused donor lungs and subjected these lung specimens to CT examination. Affected target regions were scanned by using micro-CT. Lungs from 28 donors were collected. Two lungs were unused, six were declined for non-allograft-related reasons (collectively denominated nonallograft declines, n = 8), and 20 were declined because of allograft-related reasons. CT scanning demonstrated normal lung parenchyma in only four of eight nonallograft declines, while relatively normal parenchyma was found in 12 of 20 allograft-related declines. CT and micro-CT examinations confirmed the reason for decline in most lungs and revealed unexpected (unknown from clinical files or physical inspection) CT abnormalities in other lungs. CT-based measurements showed a higher mass and density in the lungs with CT alterations compared with lungs without CT abnormalities. CT could aid in the decision-making to accept or decline donor lungs which could lead to an increase in the quantity and quality of lung allografts.

"White-Out" After Lung Transplantation: A Multicenter Cohort Description of Late Acute Graft Failure.

Graft failure represents a leading cause of mortality after organ transplantation. Acute late-onset graft failure has not been widely reported. The authors describe the demographics, CT imaging-pathology findings, and treatment of patients presenting with the latter. A retrospective review was performed of lung transplant recipients at two large-volume centers. Acute late-onset graft failure was defined as sudden onset of bilateral infiltrates with an oxygenation index <200 without identifiable cause or concurrent extrapulmonary organ failure. Laboratory, bronchoalveolar lavage (BAL), radiology, and histology results were assessed. Between 2005 and 2016, 21 patients were identified. Median survival was 19 (IQR 13-36) days post onset. Twelve patients (57%) required intensive care support at onset, 12 (57%) required mechanical ventilation, and 6 (29%) were placed on extracorporeal life support. Blood and BAL analysis revealed elevated neutrophilia, with CT demonstrating diffuse ground-glass opacities. Transbronchial biopsy samples revealed acute fibrinoid organizing pneumonia (AFOP), organizing pneumonia, and diffuse alveolar damage (DAD). Assessment of explanted lungs confirmed AFOP and DAD but also identified obliterative bronchiolitis. Patients surviving to discharge without redo transplantation (n = 2) subsequently developed restrictive allograft syndrome. This study describes acute late-onset graft failure in lung allograft recipients, without known cause, which is associated with a dismal prognosis.

The role of recipient derived interleukin-17A in a murine orthotopic lung transplant model of restrictive chronic lung allograft dysfunction.

The single most important cause of late mortality after lung transplantation is chronic lung allograft dysfunction (CLAD). However, the pathological development of CLAD was not as simple as previously presumed and subclassification phenotypes, bronchiolitis obliterans syndrome (BOS) and restrictive CLAD (rCLAD), have been introduced. We want to re-investigate how CLAD manifests in the murine orthotopic lung transplant model and investigate the role of interleukin 17A (IL-17A) within this model. Orthotopic LTx was performed in CB57BL/6, IL-17 WT and IL-17 KO mice. In a first experiment, CB57BL/6 mice receiving an isograft (CB57BL/6) or allograft (BALB/C) were compared. In a second experiment IL-17 WT and IL-17 KO mice (both CB57BL/6 background) received an allograft (BALB/C). Mice received daily immunosuppression with steroids and cyclosporine and were sacrificed 10weeks after transplantation for histopathological analysis by an experienced lung pathologist. After murine orthotopic lung transplantation, the allograft histopathologically presented features of human rCLAD (i.e. overt inflammation, pleural/parenchymal fibrosis and obliterative bronchiolitis). In the IL-17A KO group, less inflammation in the bronchovascular axis (p=0.03) was observed and a non-significant trend towards less bronchovascular fibrosis, pleural/septal inflammation and fibrosis, and parenchymal inflammation and fibrosis when compared to WT mice. The major mismatch orthotopic lung transplant model resembles features of human rCLAD. IL-17A mediated immunity is involved in the inflammatory component, but had little influence on the degree of fibrosis. Further mechanistic and therapeutic studies in this mouse model are needed to fully understand the mechanisms in rCLAD.

Parametric Response Mapping of Bronchiolitis Obliterans Syndrome Progression After Lung Transplantation.

Bronchiolitis obliterans syndrome (BOS) remains a major complication after lung transplantation. Air trapping and mosaic attenuation are typical radiological features of BOS; however, quantitative evaluation remains troublesome. We evaluated parametric response mapping (PRM, voxel-to-voxel comparison of inspiratory and expiratory computed tomography [CT] scans) in lung transplant recipients diagnosed with BOS (n = 20) and time-matched stable lung transplant recipients (n = 20). Serial PRM measurements were performed prediagnosis, at time of BOS diagnosis, and postdiagnosis (Tpre , T0 , and Tpost , respectively), or at a postoperatively matched time in stable patients. PRM results were correlated with pulmonary function and confirmed by microCT analysis of end-stage explanted lung tissue. Using PRM, we observed an increase in functional small airway disease (fSAD), from Tpre to T0 (p = 0.006) and a concurrent decrease in healthy parenchyma (p = 0.02) in the BOS group. This change in PRM continued to Tpost , which was significantly different compared to the stable patients (p = 0.0002). At BOS diagnosis, the increase in fSAD was strongly associated with a decrease in forced expiratory volume in 1 s (p = 0.011). Micro-CT confirmed the presence of airway obliteration in a sample of a BOS patient identified with 67% fSAD by PRM. We demonstrated the use of PRM as an adequate output to monitor BOS progression in lung transplant recipients.

Prophylactic Azithromycin Therapy After Lung Transplantation: Post hoc Analysis of a Randomized Controlled Trial.

Prophylactic azithromycin treatment has been demonstrated to improve freedom from bronchiolitis obliterans syndrome (BOS) 2 years after lung transplantation (LTx). In the current study, we re-evaluated the long-term effects of this prophylactic approach in view of the updated classification system for chronic lung allograft dysfunction (CLAD). A retrospective, intention-to-treat analysis of a randomized controlled trial comparing prophylactic treatment with placebo (n = 43) versus azithromycin (n = 40) after LTx was performed. Graft dysfunction (CLAD), graft loss (retransplantation, mortality), evolution of pulmonary function and functional exercise capacity were analyzed 7 years after inclusion of the last study subject. Following LTx, 22/43 (51%) patients of the placebo group and 11/40 (28%) patients of the azithromycin group ever developed CLAD (p = 0.043). CLAD-free survival was significantly longer in the azithromycin group (p = 0.024). No difference was present in proportion of obstructive versus restrictive CLAD between both groups. Graft loss was similar in both groups: 23/43 (53%) versus 16/40 (40%) patients (p = 0.27). Long-term pulmonary function and functional exercise capacity were significantly better in the azithromycin group (p < 0.05). Prophylactic azithromycin therapy reduces long-term CLAD prevalence and improves CLAD-free survival, pulmonary function, and functional exercise capacity after LTx.

Impact of CLAD Phenotype on Survival After Lung Retransplantation: A Multicenter Study.

Chronic lung allograft dysfunction (CLAD) remains a major problem after lung transplantation with no definitive treatment except redo lung transplantation (re-LTx) in selected candidates. However, CLAD is not a homogeneous entity and different phenotypes exist. Therefore, we aimed to evaluate the effect of CLAD phenotypes on survival after re-LTx for CLAD. Patients who underwent re-LTx for respiratory failure secondary to CLAD in four LTx centers between 2003 and 2013 were included in this retrospective analysis. Bronchiolitis obliterans syndrome (BOS) and restrictive CLAD (rCLAD) were distinguished using pulmonary function, radiology and explant lung histopathology. Patient variables pre- and post-re-LTx were collected and analyzed. A total of 143 patients underwent re-LTx for CLAD resulting in 94 BOS (66%) and 49 rCLAD (34%) patients. Unadjusted and adjusted survival after re-LTx for rCLAD was worse compared to BOS (HR = 2.60, 1.59-4.24; p < 0.0001 and HR = 2.61, 1.51-4.51; p = 0.0006, respectively). Patients waiting at home prior to re-LTx experienced better survival compared to hospitalized patients (HR 0.40; 0.23-0.72; p = 0.0022). Patients with rCLAD redeveloped CLAD earlier and were more likely to redevelop rCLAD. Survival after re-LTx for rCLAD is worse compared to BOS. Consequently, re-LTx for rCLAD should be critically discussed, particularly when additional peri-operative risk factors are present.

Role of genetics in lung transplant complications.

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.

Azithromycin and the treatment of lymphocytic airway inflammation after lung transplantation.

Lymphocytic airway inflammation is a major risk factor for chronic lung allograft dysfunction, for which there is no established treatment. We investigated whether azithromycin could control lymphocytic airway inflammation and improve allograft function. Fifteen lung transplant recipients demonstrating acute allograft dysfunction due to isolated lymphocytic airway inflammation were prospectively treated with azithromycin for at least 6 months (NCT01109160). Spirometry (FVC, FEV1 , FEF25-75 , Tiffeneau index) and FeNO were assessed before and up to 12 months after initiation of azithromycin. Radiologic features, local inflammation assessed on airway biopsy (rejection score, IL-17(+) cells/mm(2) lamina propria) and broncho-alveolar lavage fluid (total and differential cell counts, chemokine and cytokine levels); as well as systemic C-reactive protein levels were compared between baseline and after 3 months of treatment. Airflow improved and FeNO decreased to baseline levels after 1 month of azithromycin and were sustained thereafter. After 3 months of treatment, radiologic abnormalities, submucosal cellular inflammation, lavage protein levels of IL-1ß, IL-8/CXCL-8, IP-10/CXCL-10, RANTES/CCL5, MIP1-α/CCL3, MIP-1ß/CCL4, Eotaxin, PDGF-BB, total cell count, neutrophils and eosinophils, as well as plasma C-reactive protein levels all significantly decreased compared to baseline (p < 0.05). Administration of azithromycin was associated with suppression of posttransplant lymphocytic airway inflammation and clinical improvement in lung allograft function.

Body mass index in lung transplant candidates: a contra-indication to transplant or not?

BACKGROUND: According to International Society of Heart and Lung Transplantation criteria, high body mass index (BMI; ≥ 30 kg/m(2)) is a relative contraindication for lung transplantation (LT). On the other hand, low BMI may be associated with worse outcome. We investigated the influence of pre-LT BMI on survival after LT in a single-center study. METHODS: Patients were divided according to the World Health Organization criteria into 4 groups: BMI <18.5 kg/m(2) (underweight), BMI 18.5-24.9 kg/m(2) (normal weight), BMI 25-29.9 kg/m(2) (overweight), and BMI ≥ 30 kg/m(2) (obesity). An additional analysis was made per underlying disease. RESULTS: BMI was determined in a cohort of 546 LT recipients, of which 28% had BMI <18.5 kg/m(2). Underweight resulted in similar survival (P = .28) compared with the normal weight group. Significantly higher mortality was found in overweight (P = .016) and obese patients (P = .031) compared with the normal-weight group. Subanalysis of either underweight (P = .19) or obese COPD patients (P = .50) did not reveal worse survival. In patients with interstitial lung disease, obesity was associated with increased mortality (P = .031) compared with the normal-weight group. In cystic fibrosis patients, underweight was not associated with a higher mortality rate (P = .12) compared with the normal-weight group. CONCLUSIONS: Low pre-LT BMI did not influence survival rate in our cohort, independently from underlying disease.

Genetic variation in immunoglobulin G receptor affects survival after lung transplantation.

Chronic rejection remains the most important complication after lung transplantation (LTx). There is mounting evidence that both rheumatoid arthritis and chronic rejection share similar inflammatory mechanisms. As genetic variants in the FCGR2A gene that encodes the immunoglobulin gamma receptor (IgGR) have been identified in rheumatoid arthritis, we investigated the relationship between a genetic variant in the IgGR gene and chronic rejection and mortality after LTx. Recipient DNA from blood or explant lung tissue of 418 LTx recipients was evaluated for the IgGR (rs12746613) polymorphism. Multivariate analysis was carried out, correcting for several co-variants. In total, 216 patients had the CC-genotype (52%), 137 had the CT-genotype (33%) and 65 had the TT-genotype (15%). Univariate analysis demonstrated higher mortality in the TT-genotype compared with both other genotypes (p < 0.0001). Multivariate analysis showed that the TT-genotype had worse survival compared with the CC-genotype (hazard ratio [HR] = 2.26, p = 0.0002) but no significance was observed in the CT-genotype (HR = 1.32, p = 0.18). No difference was seen for chronic rejection. The TT-genotype demonstrated more respiratory infections (total, p = 0.037; per patient, p = 0.0022) compared with the other genotypes. A genetic variant in the IgGR is associated with higher mortality and more respiratory infections, although not with increased prevalence of chronic rejection, after LTx.

Pirfenidone: a potential new therapy for restrictive allograft syndrome?

This case report describes the evolution of pulmonary function findings (FVC, FEV1 and TLC) and CT features with pirfenidone treatment for restrictive allograft syndrome following lung transplantation. Furthermore, we herein report hypermetabolic activity on (18) F-FDG PET imaging in this setting, which could indicate active fibroproliferation and pleuroparenchymal remodeling. These findings may warrant further investigation.

Lymphocytic bronchiolitis after lung transplantation is associated with daily changes in air pollution.

Acute rejection represents a major problem after organ transplantation, being a recognized risk for chronic rejection and mortality. Recently, it became clear that lymphocytic bronchiolitis (LB, B-grade acute rejection) is more important than previously thought, as it predisposes to chronic rejection. We aimed to verify whether daily fluctuations of air pollution, measured as particulate matter (PM) are related to histologically proven A-grade rejection and/or LB and bronchoalveolar lavage (BAL) fluid cellularity after lung transplantation. We fitted a mixed model to examine the association between daily variations in PM(10) and A-grade rejection/LB on 1276 bronchoscopic biopsies (397 patients, 416 transplantations) taken between 2001 and 2011. A difference of 10 µg/m(3) in PM(10) 3 days before diagnosis of LB was associated with an OR of 1.15 (95% CI 1.04-1.27; p = 0.0044) but not with A-grade rejection (OR = 1.05; 95% CI 0.95-1.15; p = 0.32). Variations in PM(10) at lag day 3 correlated with neutrophils (p = 0.013), lymphocytes (p = 0.0031) and total cell count (p = 0.024) in BAL. Importantly, we only found an effect of PM10 on LB in patients not taking azithromycin. LB predisposed to chronic rejection (p < 0.0001). The risk for LB after lung transplantation increased with temporal changes in particulate air pollution, and this was associated with BAL neutrophilia and lymphocytosis. Azithromycin was protective against this PM effect.

Determinants of physical activity in daily life in candidates for lung transplantation.

BACKGROUND: Participation in daily physical activity (PA) has never been objectively assessed in candidates for lung transplantation (LTx). The main research questions were: 1) How active are LTx-candidates in daily life? 2) What are determinants of activity behavior before LTX? METHODS: Ninety-six candidates for LTx (diagnosis of COPD or interstitial lung disease; mean age 55 ± 7 years) underwent measurements of PA, pulmonary function, 6-min walking distance (6MWD), muscle force and health-status (SF-36 scale). RESULTS: Patients were markedly inactive (5% of waking hours walking, 26% standing and 69% sedentary). Backward multiple regression identified 6MWD (expressed as % of predicted value; ß = 73.0 steps, partial r(2) = 0.36, p = 0.00), a higher score on the energy/fatigue scale of the SF-36 (ß = 28.6 steps, partial r(2) = 0.09, p = 0.00) and a higher expiratory muscle force (expressed as % of predicted value; ß = 11.8 steps, partial r(2) = 0.05, p = 0.02) as determinants of daily steps. Minutes of mild to moderate (≥2 METs) activity were determined by 6MWD (expressed as % of predicted value; ß = 2.14 min, partial r(2) = 0.30, p = 0.00), inspiratory muscle force (expressed as % of predicted value; ß = 0.33 min, partial r(2) = 0.04, p = 0.05) and seasonal influences (spring/summer vs. autumn/winter: ß = 18.95 min, partial r(2) = 0.04, p = 0.05). The overall fit of the models was r(2) = 0.50 and r(2) = 0.38, respectively. CONCLUSIONS: The 6MWD was the main determinant of an inactive lifestyle in these patients. Respiratory muscle force, energy and fatigue and seasonal variations explained some additional variability in activity behavior. Patients should be encouraged to participate in interventions aimed at improving physical fitness and participation in daily physical activity before LTx.

A randomised controlled trial of azithromycin to prevent chronic rejection after lung transplantation.

Azithromycin reduces airway inflammation and improves forced expiratory volume in 1 s (FEV1) in chronic rejection or bronchiolitis obliterans syndrome (BOS) after lung transplantation (LTx). Azithromycin prophylaxis might prevent BOS. A double-blind randomised controlled trial of azithromycin (n = 40) or placebo (n = 43), initiated at discharge and administered three times a week for 2 yrs, was performed in 2005-2009 at the Leuven University Hospital (Leuven, Belgium). Primary end-points were BOS-free and overall survival 2 yrs after LTx; secondary end-points were acute rejection, lymphocytic bronchiolitis and pneumonitis rate, prevalence of pseudomonal airway colonisation or gastro-oesophageal reflux, and change in FEV1, airway and systemic inflammation over time. Patients developing BOS were assessed for change in FEV1 with open-label azithromycin. BOS occurred less in patients receiving azithromycin: 12.5 versus 44.2% (p = 0.0017). BOS-free survival was better with azithromycin (hazard ratio 0.27, 95% CI 0.092-0.816; p = 0.020). Overall survival, acute rejection, lymphocytic bronchiolitis, pneumonitis, colonisation and reflux were comparable between groups. Patients receiving azithromycin demonstrated better FEV1 (p = 0.028), and lower airway neutrophilia (p = 0.015) and systemic C-reactive protein levels (p = 0.050) over time. Open-label azithromycin for BOS improved FEV1 in 52.2% patients. No serious adverse events were noted. Azithromycin prophylaxis attenuates local and systemic inflammation, improves FEV1 and reduces BOS 2 yrs after LTx.