Spectrum of chronic lung allograft pathology in a mouse minor‐mismatched orthotopic lung transplant model

Chronic lung allograft dysfunction (CLAD) is a fatal condition that limits survival after lung transplantation (LTx). The pathological hallmark of CLAD is obliterative bronchiolitis (OB). A subset of patients present with a more aggressive CLAD phenotype, called restrictive allograft syndrome (RAS), characterized by lung parenchymal fibrosis (PF). The mouse orthotopic single LTx model has proven relevant to the mechanistic study of allograft injury. The minor‐alloantigen‐mismatched strain combination using C57BL/10(B10) donors and C57BL/6(B6) recipients reportedly leads to OB. Recognizing that OB severity is a spectrum that may coexist with other pathologies, including PF, we aimed to characterize and quantify pathologic features of CLAD in this model. Left LTx was performed in the following combinations: B10→B6, B6→B10, B6→B6. Four weeks posttransplant, blinded pathologic semi‐quantitative assessment showed that OB was present in 66% of B10→B6 and 30% of B6→B10 grafts. Most mice with OB also had PF with a pattern of pleuroparenchymal fibroelastosis, reminiscent of human RAS‐related pathology. Grading of pathologic changes demonstrated variable severity of airway fibrosis, PF, acute rejection, vascular fibrosis, and epithelial changes, similar to those seen in human CLAD. These assessments can make the murine LTx model a more useful tool for further mechanistic studies of CLAD pathogenesis.     

The role of biomechanical anatomical modeling via computed tomography for identification of restrictive allograft syndrome

Chronic lung allograft dysfunction (CLAD) reduces long‐term graft survival. It is important to distinguish CLAD subtypes: bronchiolitis obliterans syndrome (BOS) and restrictive allograft syndrome (RAS) as RAS has a worse prognosis and accurate subtyping could facilitate targeted treatments. However, the current diagnosis of CLAD subtypes is based on pulmonary function test (PFT) results that reflect global estimates of lung function; anatomical modeling based on computed tomography (CT) has the potential to provide detailed analysis of global and regional lung function. The purpose of this study is to evaluate the utility of CT‐based anatomical modeling for the identification of RAS. This retrospective study included 51 patients (CLAD: 17 BOS and 17 RAS, control: 17 No‐CLAD). CT data were assessed using a biomechanical model‐based platform (MORFEUS) to characterize changes in lung deformation between baseline and disease onset. Lung deformation demonstrated high sensitivity and specificity (>80%) in differentiating RAS from BOS (P<.0001) and No‐CLAD (P<.0001). There were matching radiological reading and inward deformation abnormalities in 79% of lung sections in patients with RAS. Anatomical modeling is complementary to conventional assessment in the diagnosis of RAS and potentially provides quantitative data that can help in the characterization and detailed assessment of heterogeneous lung parenchymal disease.     

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.     

T Cells Promote Bronchial Epithelial Cell Secretion of Matrix Metalloproteinase‐9 via a C‐C Chemokine Receptor Type 2 Pathway: Implications for Chronic Lung Allograft Dysfunction

Chronic lung allograft dysfunction (CLAD) is the major limitation of long‐term survival after lung transplantation. CLAD manifests as bronchiolitis obliterans syndrome (BOS) or restrictive allograft syndrome (RAS). Alloimmune reactions and epithelial‐to‐mesenchymal transition have been suggested in BOS. However, little is known regarding the role of allogenicity in epithelial cell differentiation. Primary human bronchial epithelial cells (BECs) were treated with activated T cells in the presence or absence of transforming growth factor (TGF)‐β. The expression of epithelial and mesenchymal markers was investigated. The secretion of inflammatory cytokines and matrix metalloproteinase (MMP)‐9 was measured in culture supernatants and in plasma from lung transplant recipients (LTRs): 49 stable, 29 with BOS, and 16 with RAS. We demonstrated that C‐C motif chemokine 2 secreted by T cells supports TGF‐β–induced MMP‐9 production by BECs after binding to C‐C chemokine receptor type 2. Longitudinal investigation in LTRs revealed a rise in plasma MMP‐9 before CLAD onset. Multivariate analysis showed that plasma MMP‐9 was independently associated with BOS (odds ratio [OR] = 6.19, p = 0.002) or RAS (OR = 3.9, p = 0.024) and predicted the occurrence of CLAD 12 months before the functional diagnosis. Thus, immune cells support airway remodeling through the production of MMP‐9. Plasma MMP‐9 is a potential predictive biomarker of CLAD.     

Phenotyping Established Chronic Lung Allograft Dysfunction Predicts Extracorporeal Photopheresis Response in Lung Transplant Patients

Chronic lung allograft dysfunction (CLAD) remains the leading cause of mortality in lung transplant recipients after the first year. Treatment remains limited and unpredictable. Existing data suggests extracorporeal photopheresis (ECP) may be beneficial. This study aimed to identify factors predicting treatment response and the prognostic implications. A single center retrospective analysis of all patients commencing ECP for CLAD between November 1, 2007 and September 1, 2011 was performed. In total 65 patients were included, 64 of whom had deteriorated under azithromycin. Median follow‐up after commencing ECP was 503 days. Upon commencing ECP, all patients were classified using proposed criteria for emerging clinical phenotypes, including “restrictive allograft syndrome (RAS)”, “neutrophilic CLAD (nCLAD)” and “rapid decliners”. At follow‐up, 8 patients demonstrated ≥10% improvement in FEV₁, 27 patients had stabilized and 30 patients exhibited ≥10% decline in FEV₁. Patients fulfilling criteria for “rapid decliners” (n = 21, p = 0.005), RAS (n = 22, p = 0.002) and those not exhibiting neutrophilia in bronchoalveolar lavage (n = 44, p = 0.01) exhibited poorer outcomes. ECP appears an effective second line treatment in CLAD patients progressing under azithromycin. ECP responders demonstrated improved progression‐free survival (median 401 vs. 133 days). Proposed CLAD phenotypes require refinement, but appear to predict the likelihood of ECP response.     

Changes in serum KL-6 levels are associated with the development of chronic lung allograft dysfunction in lung transplant recipients

Chronic lung allograft dysfunction (CLAD) remains a leading cause of death after lung transplantation. KL-6 is a reliable biomarker for various interstitial lung diseases and levels are increased in lung transplant recipients with versus without bronchiolitis obliterans syndrome. This study investigated whether changes in serum KL-6 levels over time were associated with CLAD.Twenty-one lung transplant recipients had serum KL-6 measured (NANOPIA®) at baseline and after 7 years. Changes in serum KL-6 levels from baseline were determined. Receiver operating characteristic curves and Kaplan-Meier analysis were used to test the predictive value of changes in serum KL-6 over time. The average increase in KL-6 in patients with CLAD was 15% versus a 28% decrease in non-CLAD patients (p = .042). An 11% decrease in serum KL-6 level was determined as the best cut-off value to be associated with the development of CLAD (86% sensitivity, 78% specificity). Kaplan-Meier analysis confirmed the association between this cut-off and the development of CLAD (log rank p = .013).In this small cohort, changes in serum KL-6 over time were associated with the development of CLAD after lung transplantation.     

A B cell–dependent pathway drives chronic lung allograft rejection after ischemia–reperfusion injury in mice

Chronic lung allograft dysfunction (CLAD) limits long‐term survival after lung transplant (LT). Ischemia–reperfusion injury (IRI) promotes chronic rejection (CR) and CLAD, but the underlying mechanisms are not well understood. To examine mechanisms linking IRI to CR, a mouse orthotopic LT model using a minor alloantigen strain mismatch (C57BL/10 [B10, H‐2^b] → C57BL/6 [B6, H‐2^b]) and isograft controls (B6→B6) was used with antecedent minimal or prolonged graft storage. The latter resulted in IRI with subsequent airway and parenchymal fibrosis in prolonged storage allografts but not isografts. This pattern of CR after IRI was associated with the formation of B cell–rich tertiary lymphoid organs within the grafts and circulating autoantibodies. These processes were attenuated by B cell depletion, despite preservation of allograft T cell content. Our observations suggest that IRI may promote B cell recruitment that drives CR after LT. These observations have implications for the mechanisms leading to CLAD after LT.     

Quantitative chest CT for subtyping chronic lung allograft dysfunction and its association with survival

Chronic lung allograft dysfunction (CLAD) is a major cause of mortality in lung transplant recipients. CLAD can be sub‐divided into at least 2 subtypes with distinct mortality risk characteristics: restrictive allograft syndrome (RAS), which demonstrates increased overall computed tomography (CT) lung density in contrast with bronchiolitis obliterans syndrome (BOS), which demonstrates reduced overall CT lung density. This study aimed to evaluate a reader‐independent quantitative density metric (QDM) derived from CT histograms to associate with CLAD survival. A retrospective study evaluated CT scans corresponding to CLAD onset using pulmonary function tests in 74 patients (23 RAS, 51 BOS). Two different QDM values (QDM1 and QDM2) were calculated using CT lung density histograms. Calculation of QDM1 includes the extreme edges of the histogram. Calculation of QDM2 includes the central region of the histogram. Kaplan‐Meier analysis and Cox regression analysis were used for CLAD prognosis. Higher QDM values were significantly associated with decreased survival. The hazard ratio for death was 3.2 times higher at the 75th percentile compared to the 25th percentile using QDM1 in a univariate model. QDM may associate with CLAD patient prognosis.     

HLA‐G*01:04∼UTR3 Recipient Correlates With Lower Survival and Higher Frequency of Chronic Rejection After Lung Transplantation

Lung transplantation (LTx) is a valid therapeutic option for selected patients with end‐stage lung disease. Soluble HLA‐G (sHLA‐G) has been associated with increased graft survival and decreased rejection episodes in solid organ transplantation. HLA‐G haplotypes named UTRs, defined by SNPs from both the 5′URR and 3′UTR, have been reported to reliably predict sHLA‐G level. The aim of this retrospective study was to determine the impact of HLA‐G alleles and UTR polymorphism from LTx recipients on anti‐HLA allo‐immunization risk, overall survival and chronic rejection (CLAD). HLA‐G SNPs were genotyped in 124 recipients who underwent LTx from 1996 to 2010 in Marseille, 123 healthy individuals and 26 cystic fibrosis patients not requiring LTx. sHLA‐G levels were measured for 38 LTx patients at D0, M3 and M12 and for 123 healthy donors. HLA‐G*01:06～UTR2 was associated with a worse evolution of cystic fibrosis (p = 0.005) but not of long‐term survival post‐LTx. HLA‐G*01:04～UTR3 haplotype was associated with lower levels of sHLA‐G at D0 and M3 (p = 0.03), impaired long‐term survival (p = 0.001), increased CLAD occurrence (p = 0.03) and the production of de novo donor‐specific antibodies (DSA) at M3 (p = 0.01). This study is the first to show the deleterious association of different HLA‐G alleles and UTRs in LTx.     

Detection of chronic lung allograft dysfunction using ventilation‐weighted Fourier decomposition MRI

Chronic lung allograft dysfunction (CLAD) remains the leading cause of morbidity and mortality after lung transplantation. Diagnosis requires spirometric change, which becomes increasingly difficult with advancing CLAD. Fourier decomposition magnetic resonance imaging (FD‐MRI) permits acquisition of ventilated‐weighted images during free‐breathing. This study evaluates FD‐MRI in detecting CLAD in selected patients after bilateral lung transplantation (DLTx). DLTx recipients demonstrating CLAD at various stages participated. Radiologists remained blinded to clinical status until completion of image analysis. Image acquisition used a 1.5‐T MR scanner using a spoiled gradient echo sequence. After FD processing and regional fractional ventilation (RFV) quantification, the volume defect percentage at 2 thresholds (VDP_1,2), median lung RFV and quartile coefficient of dispersion (QCD) were calculated. Sixty‐two patients participated. CLAD was present in 29/62 (47%) patients, of whom 17/62 (27%) had forced expiratory volume in 1 second ≤65% at image acquisition. VDP₁ was higher among these participants compared to other groups (P < .001). Increased VDP₁ was associated with subsequent graft loss, with values >2% showing reduced survival, independent of degree of graft dysfunction (P = .005). VDP₂ discriminated between presence or absence of CLAD (area under the curve = 0.71; P = .03). QCD increased significantly with advancing disease (P < .001). In conclusion, FD‐MRI‐derived parameters demonstrate potential in quantitative CLAD diagnosis and assessment after DLTx.     

A Multicenter Study on Long‐Term Outcomes After Lung Transplantation Comparing Donation After Circulatory Death and Donation After Brain Death

The implementation of donation after circulatory death category 3 (DCD3) was one of the attempts to reduce the gap between supply and demand of donor lungs. In the Netherlands, the total number of potential lung donors was greatly increased by the availability of DCD3 lungs in addition to the initial standard use of donation after brain death (DBD) lungs. From the three lung transplant centers in the Netherlands, 130 DCD3 recipients were one‐to‐one nearest neighbor propensity score matched with 130 DBD recipients. The primary end points were primary graft dysfunction (PGD), posttransplant lung function, freedom from chronic lung allograft dysfunction (CLAD), and overall survival. PGD did not differ between the groups. Posttransplant lung function was comparable after bilateral lung transplantation, but seemed worse after DCD3 single lung transplantation. The incidence of CLAD (p = 0.17) nor the freedom from CLAD (p = 0.36) nor the overall survival (p = 0.40) were significantly different between both groups. The presented multicenter results are derived from a national context where one third of the lung transplantations are performed with DCD3 lungs. We conclude that the long‐term outcome after lung transplantation with DCD3 donors is similar to that of DBD donors and that DCD3 donation can substantially enlarge the donor pool.     

HLA Matching at the Eplet Level Protects Against Chronic Lung Allograft Dysfunction

Donor selection in lung transplantation (LTx) is historically based upon clinical urgency, ABO compatibility, and donor size. HLA matching is not routinely considered; however, the presence or later development of anti‐HLA antibodies is associated with poorer outcomes, particularly chronic lung allograft dysfunction (CLAD). Using eplet mismatches, we aimed to determine whether donor/recipient HLA incompatibility was a significant predictor of CLAD. One hundred seventy‐five LTx undertaken at the Alfred Hospital between 2008 and 2012 met criteria. Post‐LTx monitoring was continued for at least 12 months, or until patient death. HLA typing was performed by sequence‐based typing and Luminex sequence‐specific oligonucleotide. Using HLAMatchmaker, eplet mismatches between each donor/recipient pairing were analyzed and correlated against incidences of CLAD. HLA‐DRB1/3/4/5+DQA/B eplet mismatch was a significant predictor of CLAD (hazard ratio [HR] 3.77, 95% confidence interval [CI]: 1.71–8.29 p < 0.001). When bronchiolitis obliterans syndrome (BOS) and restrictive allograft syndrome (RAS) were analyzed independently, HLA‐DRB1/3/4/5 + DQA/B eplet mismatch was shown to significantly predict RAS (HR 8.3, 95% CI: 2.46–27.97 p < 0.001) but not BOS (HR 1.92, 95% CI: 0.64–5.72, p = 0.237). HLA‐A/B eplet mismatch was shown not to be a significant predictor when analyzed independently but did provide additional stratification of results. This study illustrates the importance of epitope immunogenicity in defining donor–recipient immune compatibility in LTx.     

When tissue is the issue: A histological review of chronic lung allograft dysfunction

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.     

Effect of HMG CoA reductase inhibitors on the development of chronic lung allograft dysfunction

Lung transplant recipients (LRs) have a reduced median 5‐year survival of approximately 55% primarily due to chronic lung allograft dysfunction (CLAD). Statins have anti‐inflammatory and immunomodulatory effects that may facilitate CLAD prevention. This study sought to evaluate statin effect on CLAD development. Adult bilateral LRs from January 2004 to October 2013 were included. Statin group included recipients with early statin use and continued for minimum 6 months. Propensity score matching was performed for age, gender, and native lung disease to select matched nonstatin group. Competing risk approach was used to evaluate statin effect on CLAD development at 3 years while controlling for acute rejection and CMV pneumonitis. A total of 130 patients were included in each group. CLAD cumulative incidence at 3 years for statin and nonstatin groups was 20.6% (CI: 11.8%‐33.5%) and 22.4% (CI: 12.2%‐27.3%). Statin use was not associated with a decreased risk of CLAD (subdistribution hazard ratio [SHR]: 0.93, 95% CI: 0.55‐1.59, P = .80) but was associated with a decreased risk of death (SHR: 0.45, CI: 0.22‐0.90, P = .024). At 3 years, patient survival was 81.7% in statin group and 68.3% in nonstatin group (P = .012). Statins did not significantly delay the time to development of CLAD in LR but did demonstrate a benefit in patient survival.     

Posttransplant lymphoproliferative disorder in pediatric patients: Survival rates according to primary sites of occurrence and a proposed clinical categorization

Posttransplant lymphoproliferative disorder (PTLD) is a devastating complication of organ transplant. In a hospital‐based registry, we identified biopsy‐proven cases of PTLD among children during a 15‐year period and reviewed trends in PTLD rates, the sites of involvement, and the associated survival rates. Cases that were included had at least 1 year of follow‐up after the diagnosis of PTLD. We studied 82 patients with first‐episode PTLD. Median age at diagnosis was 6.4 years (IQR 3.2‐12.3 years). The most frequent PTLD sites were tonsillar/adenoidal (T/A [34%]) and gastrointestinal (32%), followed by miscellaneous (defined as less common sites including central nervous system, kidney, lung, and soft tissue [12%]), lymph node (11%), and multisite (11%). Kaplan‐Meier survival curves showed that T/A PTLD was associated with decreased all‐cause mortality compared with PTLD at other sites (log‐rank 0.004), even after adjustment for histological subtype (P = .047). PTLD‐related mortality was also decreased among T/A PTLD (log‐rank 0.012) but showed a trend toward significance only after adjustment for histological subtype (P = .09). Among first episodes of PTLD, T/A PTLD was associated with a survival advantage compared with PTLD at other sites, even after adjustment for potential confounders. Based on our observations, we propose a clinical categorization of PTLD according to anatomical site of occurrence.     

Impact of Cytokine Expression in the Pre‐Implanted Donor Lung on the Development of Chronic Lung Allograft Dysfunction Subtypes

The long‐term success of lung transplantation continues to be challenged by the development of chronic lung allograft dysfunction (CLAD). The purpose of this study was to investigate the relationship between cytokine expression levels in pre‐implanted donor lungs and the posttransplant development of CLAD and its subtypes, bronchiolitis obliterans syndrome (BOS) and restrictive allograft syndrome (RAS). Of 109 patients who underwent bilateral lung or heart–lung transplantation and survived for more than 3 months, 50 BOS, 21 RAS and 38 patients with No CLAD were identified by pulmonary function test results. Using donor lung tissue biopsies sampled from each patient, expression levels of IL‐6, IL‐1β, IL‐8, IL‐10, interferon‐γ and tumor necrosis factor‐α mRNA were measured. IL‐6 expression levels were significantly higher in pre‐implanted lungs of patients that ultimately developed BOS compared to RAS and No CLAD (p = 0.025 and 0.011, respectively). Cox regression analysis demonstrated an association between high IL‐6 expression levels and BOS development (hazard ratio = 4.98; 95% confidence interval = 2.42–10.2, p < 0.001). In conclusion, high IL‐6 mRNA expression levels in pre‐implanted donor lungs were associated with the development of BOS, not RAS. This association further supports the contention that early graft injury impacts on both late graft function and early graft function.     

Lung Transplant Center Volume Ameliorates Adverse Influence of Prolonged Ischemic Time on Mortality

The influence of prolonged ischemic time on outcomes after lung transplant is controversial, but no research has investigated ischemic time in the context of center volume. We used data from the United Network for Organ Sharing to estimate the influence of ischemic time on patient survival conditional on center volume in the post–lung allocation score era (2005–2015). The analytic sample included 14 877 adult lung transplant recipients, of whom 12 447 were included in multivariable survival analysis. Patient survival was improved in high‐volume centers compared with low‐volume centers (log‐rank test p = 0.001), although mean ischemic times were longer at high‐volume centers (5.16 ± 1.70 h vs. 4.83 ± 1.63 h, p < 0.001). Multivariable Cox proportional hazards regression stratified by transplant center found an adverse influence of longer ischemic time at low‐volume centers but not at high‐volume centers. At centers performing 50 transplants in the period 2005–2015, for example, 8 versus 6 h of ischemia were associated with an 18.9% (95% confidence interval 6.5–32.7%; p < 0.001) greater mortality hazard, whereas at centers performing 350 transplants in this period, no differences in survival by ischemic time were predicted. Despite longer mean ischemic time at high‐volume transplant centers, these centers had favorable patient outcomes and no adverse survival implications of prolonged ischemia.     

Epithelial cell death markers in bronchoalveolar lavage correlate with chronic lung allograft dysfunction subtypes and survival in lung transplant recipients—a single‐center retrospective cohort study

Chronic lung allograft dysfunction (CLAD) remains the leading cause of late death after lung transplantation. Epithelial injury is thought to be a key event in the pathogenesis of CLAD. M30 and M65 are fragments of cytokeratin‐18 released specifically during epithelial cell apoptosis and total cell death, respectively. We investigated whether M30 and M65 levels in bronchoalveolar lavage (BAL) correlate with CLAD subtypes: restrictive allograft syndrome (RAS) versus bronchiolitis obliterans syndrome (BOS). BALs were obtained from 26 patients with established CLAD (10 RAS, 16 BOS) and 19 long‐term CLAD‐free controls. Samples with concurrent infection or acute rejection were excluded. Protein levels were measured by ELISA. Variables were compared using Kruskal–Wallis, Mann–Whitney U test and Chi‐squared tests. Association of M30 and M65 levels with post‐CLAD survival was assessed using a Cox PH models. M65 levels were significantly higher in RAS compared to BOS and long‐term CLAD‐free controls and correlated with worse post‐CLAD survival. Lung epithelial cell death is enhanced in patients with RAS. Detection of BAL M65 may be used to differentiate CLAD subtypes and as a prognostic marker in patients with established CLAD. Understanding the role of epithelial cell death in CLAD pathogenesis may help identify new therapeutic targets to improve outcome.