Comparison of bronchiolitis obliterans syndrome to other forms of chronic lung allograft dysfunction after lung transplantation

Restrictive allograft dysfunction rather than bronchiolitis obliterans syndrome had a major impact on the overall survival after living-donor lobar lung transplantation

PURPOSE

Chronic lung allograft dysfunction (CLAD) is a known long-term fatal disorder after lung transplantation. In this study, we evaluated the CLAD classification of the International Society for Heart and Lung Transplantation (ISHLT) for living-donor lobar lung transplantation (LDLLT).

METHODS

We conducted a single-center retrospective review of data from 73 patients who underwent bilateral LDLLT between 1998 and 2019. Factors related to opacity on computed tomography (CT) and restriction on pulmonary function tests (PFTs) were also analyzed.

RESULTS

Overall, 26 (36%) patients were diagnosed with CLAD, including restrictive allograft syndrome (RAS), n = 10 (38.5%); bronchiolitis obliterans syndrome (BOS), n = 8 (30.8%); mixed, n = 1 (3.8%); undefined, n = 2 (7.7%); and unclassified, n = 5 (19.2%). The 5-year survival rate after the CLAD onset was 60.7%. The survival of patients with BOS was significantly better than that of patients with RAS (p = 0.012). In particular, patients with restriction on PFT had a significantly worse survival than those without restriction (p = 0.001).

CONCLUSIONS

CLAD after bilateral LDLLT does not have a major impact on the recipient survival, especially in patients with BOS. Restriction on PFT may predict a particularly poor prognosis in patients with CLAD after bilateral LDLLT.

Bronchiolitis obliterans syndrome after lung or haematopoietic stem cell transplantation: current management and future directions

Bronchiolitis obliterans syndrome (BOS) may develop after either lung or haematopoietic stem cell transplantation (HSCT), with similarities in histopathological features and clinical manifestations. However, there are differences in the contributory factors and clinical trajectories between the two conditions. BOS after HSCT occurs due to systemic graft-versus-host-disease (GVHD), whereas BOS after lung transplantation is limited to the lung allograft. BOS diagnosis after HSCT is more challenging, as the lung function decline may occur due to extrapulmonary GVHD, causing sclerosis or inflammation in the fascia or muscles of the respiratory girdle. Treatment is generally empirical with no established effective therapies. This review provides rare insights and commonalities of both conditions, that are not well elaborated elsewhere in contemporary literature, and highlights the importance of cross disciplinary learning from experts in other transplant modalities. Treatment algorithms for each condition are presented, based on the published literature and consensus clinical opinion. Immunosuppression should be optimised, and other conditions or contributory factors treated where possible. When initial treatment fails, the ultimate therapeutic option is lung transplantation (or re-transplantation in the case of BOS after lung transplantation) in carefully selected candidates. Novel therapies under investigation include aerosolised liposomal cyclosporine, Janus kinase inhibitors, antifibrotic therapies, and (in patients with BOS after lung transplantation) B-cell–directed therapies. Effective novel treatments that have a tangible impact on survival and thereby avoid the need for lung transplantation or re-transplantation are urgently required.

Chronic Lung Allograft Dysfunction: Evolving Concepts and Therapies

The primary factor that limits long-term survival after lung transplantation is chronic lung allograft dysfunction (CLAD). CLAD also impairs quality of life and increases the costs of medical care. Our understanding of CLAD continues to evolve. Consensus definitions of CLAD and the major CLAD phenotypes were recently updated and clarified, but it remains to be seen whether the current definitions will lead to advances in management or impact care. Understanding the potential differences in pathogenesis for each CLAD phenotype may lead to novel therapeutic strategies, including precision medicine. Recognition of CLAD risk factors may lead to earlier interventions to mitigate risk, or to avoid risk factors all together, to prevent the development of CLAD. Unfortunately, currently available therapies for CLAD are usually not effective. However, novel therapeutics aimed at both prevention and treatment are currently under investigation. We provide an overview of the updates to CLAD-related terminology, clinical phenotypes and their diagnosis, natural history, pathogenesis, and potential strategies to treat and prevent CLAD.

miRNAs Potentially Involved in Post Lung Transplant-Obliterative Bronchiolitis: The Role of miR-21-5p

Epigenetic changes, including miRNAs deregulation, have been suggested to play a significant role in development of obliterative bronchiolitis (OB) in transplanted lungs. Many studies have tried to identify ideal candidate miRNAs and the downstream pathways implicated in the bronchiolar fibro-obliterative process. Several candidate miRNAs, previously indicated as possibly being associated with OB, were analyzed by combining the quantitative real time-polymerase chain reaction (qRT-PCR) and in situ hybridization (ISH) of lung tissues of OB affected patients. Disease and OB-lesion-specific expression of miR-21-5p was confirmed and by computational analysis we were able to identify the network of genes most probably associated miR-21-5p in the context of OB fibrogenesis. Among all potentially associated genes, STAT3 had a very high probability score. Immunohistochemistry showed that STAT3/miR-21-5p were co-over expressed in OB lesions, thus, suggesting miR-21-5p could regulate STAT3 expression. However, miR-21-5p inhibition in cultures of bronchiolitis obliterans syndrome (BOS) derived myofibroblasts did not significantly affect STAT3 mRNA and protein expression levels. This study demonstrates the specificity of miR-21-5p over-expression in OB lesions and contributes to existing knowledge on the miR-21-5p downstream pathway. Activation of STAT3 is associated with miR-21-5p upregulation, however, STAT-3 network activation is most likely complex and miR-21-5p is not the sole regulator of STAT3.

Longitudinal lung function measurements in single lung transplant recipients with chronic lung allograft dysfunction

BACKGROUND

Phenotyping chronic lung allograft dysfunction (CLAD) in single lung transplant (SLTX) recipients is challenging. The aim of this study was to assess the diagnostic and prognostic value of longitudinal lung function tests in SLTX recipients with CLAD.

METHODS

A total of 295 SLTX recipients were analyzed and stratified according to native lung physiology. In addition to spirometry, measurements of static lung volumes and lung capacities were used to phenotype patients and to assess their prognostic value. Outcome was survival after CLAD onset. Patients with insufficient clinical information were excluded (n = 71).

RESULTS

Of 224 lung transplant recipients, 105 (46.9%) developed CLAD. Time to CLAD onset (hazard ratio [HR]: 0.82, 95% CI: 0.74-0.90; p < 0.001), severity of CLAD at onset (HR: 0.97, 95% CI: 0.94-0.99; p = 0.009), and progression after onset of CLAD (HR: 1.03, 95% CI: 1.00-1.05; p = 0.023) were associated with outcome. Phenotypes at onset were bronchiolitis obliterans syndrome (BOS) (59.1%), restrictive allograft syndrome (RAS) (12.4%), mixed phenotype (6.7%), and undefined phenotype (21.9%). Survival estimates differed significantly between phenotypes (p = 0.004), with RAS and mixed phenotype being associated with the worst survival, followed by BOS and undefined phenotype. Finally, a higher hazard for mortality was noticed for RAS (HR: 2.34, 95% CI: 0.99-5.52; p = 0.054) and mixed phenotype (HR: 3.30, 95% CI: 1.20-9.11; p = 0.021) while controlling for time to CLAD onset and severity of CLAD at onset.

CONCLUSIONS

Phenotyping CLAD in SLTX remains challenging with a high number of patients with an undefined phenotype despite comprehensive lung function testing. However, phenotyping is of prognostic value. Furthermore, early, severe, and progressive CLADs are associated with worse survival.

Significance of Best Spirometry in the First Year After Bilateral Lung Transplantation: Association With 3-Year Outcomes

BACKGROUND

Spirometry is the cornerstone of monitoring allograft function after lung transplantation (LT). We sought to determine the association of variables on best spirometry during the first year after bilateral LT with 3-year posttransplant survival.

METHODS

We reviewed charts of patients who survived at least 3 months after bilateral LT (n = 157; age ± SD: 54 ± 13 y, male:female = 91:66). Best spirometry was calculated as the average of 2 highest measurements at least 3 weeks apart during the first year. Airway obstruction was defined as forced expiratory volume in 1-second (FEV1)/forced vital capacity (FVC) ratio <0.7. Survival was compared based on the ventilatory defect and among groups based on the best FEV1 and FVC measurements (>80%, 60%-80%, and <60% predicted). Primary outcome was 3-year survival.

RESULTS

Overall, 3-year survival was 67% (n = 106). Obstructive defect was uncommon (7%) and did not have an association with 3-year survival (72% versus 67%, P = 0.7). Although one-half patients achieved an FVC>80% predicted (49%), 1 in 5 (19%) remained below 60% predicted. Irrespective of the type of ventilatory defect, survival worsened as the best FVC (% predicted) got lower (>80: 80.8%; 60-80: 63.3%; <60: 40%; P < 0.001). On multivariate logistic regression analysis, after adjusting for age, gender, transplant indication, and annual bronchoscopy findings, best FVC (% predicted) during the first year after LT was independently associated with 3-year survival.

CONCLUSIONS

A significant proportion of bilateral LT patients do not achieve FVC>80% predicted. Although the type of ventilatory defect on best spirometry does not predict survival, failure to achieve FVC>80% predicted during the first year was independently associated with 3-year mortality.

Use of CT-SCAN score and volume measures to early identify restrictive allograft syndrome in single lung transplant recipients

BACKGROUND

Restrictive allograft syndrome (RAS) after lung transplantation (LTx) is associated with the poorer graft survival in patients with chronic lung allograft dysfunction (CLAD). Nevertheless, its diagnostic criteria have not been clearly defined after single-LTx (SLTx). Hence, we studied an SLTx cohort with CLAD to investigate the utility of both computed tomography (CT)-score/volume measures and functional spirometric criteria for the early identification of RAS in this population.

METHODS

We included 51 patients with SLTx (17 RAS, 17 bronchiolitis obliterans syndrome [BOS], and 17 stable condition). The criteria for RAS diagnosis in SLTx included forced vital capacity (FVC) <80% baseline (BL) or forced expiratory volume in 1 second (FEV1) <80% BL with an FEV1/FVC ratio^{unchanged or >0.7} and persistent CT-scan-lung opacities. We defined 4 time points (T): T-baseline, T-onset (first CT-scan-opacities), T-follow-up, and T-last.

RESULTS

In patients with RAS, the spirometric criteria for RAS at T-onset were reached in only 47% (FVC decline <80% BL [(29%] or FEV1 <80% BL/ratio^{unchanged or >0.7} [41%]), whereas at the same T-onset date, the graft CT-score increased to 5 (4-6) vs 1 (0-2) at baseline (p < 0.001) (CT - score ≥2 at T-onset in 100% and ΔCT - score ≥2 in 74% of patients with RAS), and the median CT-scan graft volume decreased to 1,722 ml (vs 1,796 ml at T-baseline, p = 0.003) (decreased CT-graft - volume <90% BL in 50% of patients). In contrast, in patients with BOS, CT-score/volume were unchanged at T-onset vs T-baseline (p = 0.8, p = 0.68, respectively).

CONCLUSION

Our results suggest that the use of a simple CT-score and to a lesser extent, CT-volume measures, might allow for the early identification and/or prediction of RAS in SLTx rather than functional criteria.

A randomised single-centre trial of inhaled liposomal cyclosporine for bronchiolitis obliterans syndrome post-lung transplantation

Introduction

No proven treatments exist for bronchiolitis obliterans syndrome (BOS) following lung transplantation. Inhaled liposomal cyclosporine (L-CsA) may prevent BOS progression.

Methods

A 48-week phase IIb randomised clinical trial was conducted in 21 lung transplant patients with BOS assigned to either L-CsA with standard-of-care (SOC) oral immunosuppression (L-CsA group) or SOC (SOC-alone group). Efficacy end-points were BOS progression-free survival (defined as absence of ≥20% decline in forced expiratory volume in 1 s (FEV₁) from randomisation, re-transplantation or death) and BOS grade change.

Results

BOS progression-free survival was 82% for L-CsA versus 50% for SOC-alone (p=0.1) and BOS grade worsened in 18% for L-CsA versus 60% for SOC-alone (p=0.05). Mean changes in ΔFEV₁ and forced vital capacity, respectively, stabilised with L-CsA: +0.005 (95% CI −0.004– +0.013) and −0.005 (95% CI −0.015– +0.006) L·month⁻¹, but worsened with SOC-alone: −0.023 (95% CI −0.033– −0.013) and −0.026 (95% CI −0.039– −0.014) L·month⁻¹ (p<0.0001 and p=0.009). Median survival (4.1 versus 2.9 years; p=0.03) and infection rate (45% versus 60%; p=0.7) improved with L-CsA versus SOC-alone; creatinine and tacrolimus levels were similar.

Conclusions

L-CsA was well tolerated and stabilised lung function in lung transplant recipients affected by BOS without systemic toxicity, providing a basis for a global phase III trial using L-CsA.

Liposomal aerosol cyclosporine (L-CsA) was well tolerated and stabilised lung function in lung transplant recipients affected by BOS. The data provide evidence for an ongoing global phase III trial using L-CsA for BOS.http://bit.ly/2HB8w5j

The role of the immune system in lung transplantation: towards improved long-term results

Over the past 35 years, lung transplantation has evolved from an experimental treatment to the treatment of choice for patients with end-stage lung disease. Beyond the immediate period after lung transplantation, rejection and infection are the leading causes of death. The risk of rejection after lung transplantation is generally higher than after other solid organ transplants, and this necessitates more intensive immunosuppression. However, this more intensive treatment does not reduce the risk of rejection sufficiently, and rejection is one of the most common complications after transplantation. There are multiple forms of rejection including acute cellular rejection, antibody-mediated rejection, and chronic lung allograft dysfunction. These have posed a vexing problem for clinicians, patients, and the field of lung transplantation. Confounding matters is the inherent effect of more intensive immunosuppression on the risk of infections. Indeed, infections pose a direct problem resulting in morbidity and mortality and increase the risk of chronic lung allograft dysfunction in the ensuing weeks and months. There are complex interactions between microbes and the immune response that are the subject of ongoing studies. This review focuses on the role of the immune system in lung transplantation and highlights different forms of rejection and the impact of infections on outcomes.

Single vs. bilateral lung transplantation: when and why

PURPOSE OF REVIEW

Lung transplantation is a life-saving treatment for several end stage lung diseases. Over the last two decades, the number of lung transplantation performed worldwide has steadily increased but several thousand people still die every year waiting for lung transplantation. However, the optimal procedure for lung transplantation in non-septic lung conditions remains debatable.

RECENT FINDINGS

In pulmonary fibrosis and COPD, many recent studies suggest superiority of bilateral lung transplantation over single lung transplantation when long-term survival is evaluated; consequently, bilateral lung transplantation has been favored by many lung transplantation centers. However, the quality of evidence to support the superiority of bilateral lung transplantation remains low in the absence of prospective studies, and other available studies do not show differences in outcomes between the two types of procedure.

SUMMARY

In the absence of good high quality evidence, it is difficult to make strong general recommendations for the type of lung transplant, and the decision often has to be individualized. However, the number of recipients on the wait list continues to surpass the amount of available organs and due consideration needs to be given to single lung transplantation as an option whenever possible.

MRI-derived regional flow-volume loop parameters detect early-stage chronic lung allograft dysfunction

BACKGROUND

Chronic lung allograft dysfunction (CLAD) is a major cause for the low long-term survival rates after lung transplantation (LTx). Early detection of CLAD may enable providing medical treatment before a nonreversible graft dysfunction has occurred. MRI is advantageous to pulmonary function testing (PFT) in the ability to assess regional function changes, and thus have the potential in detecting very early stages of CLAD before changes in global forced expiratory volume during the first second (FEV1%) occur.

PURPOSE

To examine whether early stages of CLAD (diagnosed based on PFT values) could also be detected using MRI-derived parameters of regional flow-volume dynamics.

STUDY TYPE

Retrospective.

POPULATION

62 lung transplantation recipients were included in the study, 29 of which had been diagnosed with CLAD at various stages.

FIELD STRENGTH/SEQUENCE

MRI datasets were acquired with a 1.5T Siemens scanner using a spoiled gradient echo sequence.

ASSESSMENT

MRI datasets were retrospectively preprocessed and analyzed by a blinded radiologist according to the phase resolved functional lung MRI (PREFUL-MRI) approach, resulting in fractional ventilation (FV) maps and regional flow-volume loops (rFVL). FV- and rFVL-based parameters of regional lung ventilation were estimated.

STATISTICAL TESTS

Differences between groups were compared by Mann-Whitney U-test with a Bonferroni correction for multiple comparisons (n = 2).

RESULTS

rFVL-CC-based parameters discriminated significantly between the presence or absence of CLAD (P < 0.003).

DATA CONCLUSION

Using the contrast media-free PREFUL-MRI technique, parameters of ventilation dynamics and its regional heterogeneity were shown to be sensitive for the detection of early CLAD stages.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY: Stage 3 J. Magn. Reson. Imaging 2019;50:1873-1882.

The impact of non-HLA antibodies on outcomes after lung transplantation and implications for therapeutic approaches

The role of donor-specific antibodies (DSA) to mismatched human leukocyte antigens (HLA) in lung allograft rejection has been recognized over the past 20 years. During this time, there has been growing experience and recognition of an important role for non-HLA antibodies in lung allograft rejection. Multiple self-antigens have been identified that elicit autoimmune responses including collagen V, K-α 1 tubulin, angiotensin type 1 receptor, and endothelin type A receptor, but it is likely that other antigens elicit similar responses. The paradigm for the pathogenesis of these autoimmune responses consists of exposure of sequestered self-antigens followed by loss of peripheral tolerance, which then promotes allograft rejection. Studies have focused mainly on the impact of autoimmune responses on the development of Bronchiolitis Obliterans Syndrome or its mouse model surrogate. However, there are emerging data that illustrate that non-HLA antibodies can induce acute antibody-mediated rejection (AMR) after lung transplantation. Treatment has focused on antibody-depletion protocols, but experience is limited to cohort studies and appropriate controlled trials have not been conducted. It is noteworthy that depletion of non-HLA antibodies has been associated with favorable clinical outcomes. Clearly, additional studies are needed to identify the optimal therapeutic approaches to non-HLA antibodies in clinical practice.

Donor-derived cell-free DNA predicts allograft failure and mortality after lung transplantation

Background

Allograft failure is common in lung-transplant recipients and leads to poor outcomes including early death. No reliable clinical tools exist to identify patients at high risk for allograft failure. This study tested the use of donor-derived cell-free DNA (%ddcfDNA) as a sensitive marker of early graft injury to predict impending allograft failure.

Methods

This multicenter, prospective cohort study enrolled 106 subjects who underwent lung transplantation and monitored them after transplantation for the development of allograft failure (defined as severe chronic lung allograft dysfunction [CLAD], retransplantation, and/or death from respiratory failure). Plasma samples were collected serially in the first three months following transplantation and assayed for %ddcfDNA by shotgun sequencing. We computed the average levels of ddcfDNA over three months for each patient (avddDNA) and determined its relationship to allograft failure using Cox-regression analysis.

Findings

avddDNA was highly variable among subjects: median values were 3·6%, 1·6% and 0·7% for the upper, middle, and low tertiles, respectively (range 0·1%–9·9%). Compared to subjects in the low and middle tertiles, those with avddDNA in the upper tertile had a 6·6-fold higher risk of developing allograft failure (95% confidence interval 1·6–19·9, p = 0·007), lower peak FEV1 values, and more frequent %ddcfDNA elevations that were not clinically detectable.

Interpretation

Lung transplant patients with early unresolving allograft injury measured via %ddcfDNA are at risk of subsequent allograft injury, which is often clinically silent, and progresses to allograft failure.

Fund

National Institutes of Health.

Bronchiolitis obliterans syndrome-free survival after lung transplantation: An International Society for Heart and Lung Transplantation Thoracic Transplant Registry analysis

BACKGROUND

Lung transplant (LTx) recipients have low long-term survival and a high incidence of bronchiolitis obliterans syndrome (BOS). However, few long-term, multicenter, and precise estimates of BOS-free survival (a composite outcome of death or BOS) incidence exist.

METHODS

This retrospective cohort study of primary LTx recipients (1994-2011) reported to the International Society of Heart and Lung Transplantation Thoracic Transplant Registry assessed outcomes through 2012. For the composite primary outcome of BOS-free survival, we used Kaplan-Meier survival and Cox proportional hazards regression, censoring for loss to follow-up, end of study, and re-LTx. Although standard Thoracic Transplant Registry analyses censor at the last consecutive annual complete BOS status report, our analyses allowed for partially missing BOS data.

RESULTS

Due to BOS reporting standards, 99.1% of the cohort received LTx in North America. During 79,896 person-years of follow-up, single LTx (6,599 of 15,268 [43%]) and bilateral LTx (8,699 of 15,268 [57%]) recipients had a median BOS-free survival of 3.16 years (95% confidence interval [CI], 2.99-3.30 years) and 3.58 years (95% CI, 3.53-3.72 years), respectively. Almost 90% of the single and bilateral LTx recipients developed the composite outcome within 10 years of transplantation. Standard Registry analyses "overestimated" median BOS-free survival by 0.42 years and "underestimated" the median survival after BOS by about a half-year for both single and bilateral LTx (p < 0.05).

CONCLUSIONS

Most LTx recipients die or develop BOS within 4 years, and very few remain alive and free from BOS at 10 years post-LTx. Less inclusive Thoracic Transplant Registry analytic methods tend to overestimate BOS-free survival. The Registry would benefit from improved international reporting of BOS and other chronic lung allograft dysfunction (CLAD) events.

Validation and Refinement of Chronic Lung Allograft Dysfunction Phenotypes in Bilateral and Single Lung Recipients

RATIONALE

The clinical course of chronic lung allograft dysfunction (CLAD) is heterogeneous. Forced vital capacity (FVC) loss at onset, which may suggest a restrictive phenotype, was associated with worse survival for bilateral lung transplant recipients in one previously published single-center study.

OBJECTIVES

We sought to replicate the significance of FVC loss in an independent, retrospectively identified cohort of bilateral lung transplant recipients and to investigate extended application of this approach to single lung recipients.

METHODS

FVC loss and other potential predictors of survival after the onset of CLAD were assessed using Kaplan-Meier and Cox proportional hazards models.

MEASUREMENTS AND MAIN RESULTS

FVC loss at the onset of CLAD was associated with higher mortality in an independent cohort of bilateral lung transplant recipients (hazard ratio [HR], 2.75; 95% confidence interval [CI], 2.02-3.73; P < 0.0001) and in a multicenter cohort of single lung recipients (HR, 1.80; 95% CI, 1.09-2.98; P = 0.02). Including all subjects, the deleterious impact of FVC loss on survival persisted after adjustment for other relevant clinical variables (HR, 2.36; 95% CI, 1.77-3.15; P < 0.0001). In patients who develop CLAD without FVC loss, chest computed tomography features suggestive of pleural or parenchymal fibrosis also predicted worse survival in both bilateral (HR, 2.01; 95% CI, 1.16-5.20; P = 0.02) and single recipients (HR, 2.47; 95% CI, 1.24-10.57; P = 0.02).

CONCLUSIONS

We independently validated the prognostic significance of FVC loss for bilateral lung recipients and demonstrated that this approach to CLAD classification also confers prognostic information for single lung transplant recipients. Improved understanding of these discrete phenotypes is critical to the development of effective therapies.

Update in Chronic Lung Allograft Dysfunction

Chronic lung allograft dysfunction (CLAD) is the major limitation to posttransplant survival. This review highlights the evolving definition of CLAD, risk factors, treatment, and expected outcomes after the development of CLAD.

Chronic lung allograft dysfunction phenotypes and treatment

Chronic lung allograft dysfunction (CLAD) remains a major hurdle limiting long-term survival post lung transplantation. Given the clinical heterogeneity of CLAD, recently two phenotypes of CLAD have been defined [bronchiolitis obliterans syndrome (BOS) vs. restrictive allograft syndrome (RAS) or restrictive CLAD (rCLAD)]. BOS is characterized by an obstructive pulmonary function, air trapping on CT and obliterative bronchiolitis (OB) on histopathology, while RAS/rCLAD patients show a restrictive pulmonary function, persistent pleuro-parenchymal infiltrates on CT and pleuroparenchymal fibro-elastosis on biopsies. Importantly, the patients with RAS/rCLAD have a severely limited survival post diagnosis of 6-18 months compared to 3-5 years after BOS diagnosis. In this review, we will review historical evidence for this heterogeneity and we will highlight the clinical, radiological, histopathological characteristics of both phenotypes, as well as their risk factors. Treatment of CLAD remains troublesome, nevertheless, we will give an overview of different treatment strategies that have been tried with some success. Adequate phenotyping remains difficult but is clearly needed for both clinical and scientific purposes.

Parametric Response Mapping as an Imaging Biomarker in Lung Transplant Recipients

RATIONALE

The predominant cause of chronic lung allograft failure is small airway obstruction arising from bronchiolitis obliterans. However, clinical methodologies for evaluating presence and degree of small airway disease are lacking.

OBJECTIVES

To determine if parametric response mapping (PRM), a novel computed tomography voxel-wise methodology, can offer insight into chronic allograft failure phenotypes and provide prognostic information following spirometric decline.

METHODS

PRM-based computed tomography metrics quantifying functional small airways disease (PRM^fSAD) and parenchymal disease (PRM^PD) were compared between bilateral lung transplant recipients with irreversible spirometric decline and control subjects matched by time post-transplant (n = 22). PRM^fSAD at spirometric decline was evaluated as a prognostic marker for mortality in a cohort study via multivariable restricted mean models (n = 52).

MEASUREMENTS AND MAIN RESULTS

Patients presenting with an isolated decline in FEV₁ (FEV₁ First) had significantly higher PRM^fSAD than control subjects (28% vs. 15%; P = 0.005), whereas patients with concurrent decline in FEV₁ and FVC had significantly higher PRM^PD than control subjects (39% vs. 20%; P = 0.02). Over 8.3 years of follow-up, FEV₁ First patients with PRM^fSAD greater than or equal to 30% at spirometric decline lived on average 2.6 years less than those with PRM^fSAD less than 30% (P = 0.004). In this group, PRM^fSAD greater than or equal to 30% was the strongest predictor of survival in a multivariable model including bronchiolitis obliterans syndrome grade and baseline FEV_1% predicted (P = 0.04).

CONCLUSIONS

PRM is a novel imaging tool for lung transplant recipients presenting with spirometric decline. Quantifying underlying small airway obstruction via PRM^fSAD helps further stratify the risk of death in patients with diverse spirometric decline patterns.

Lung volumes predict survival in patients with chronic lung allograft dysfunction

Identification of disease phenotypes might improve the understanding of patients with chronic lung allograft dysfunction (CLAD). The aim of the study was to assess the impact of pulmonary restriction and air trapping by lung volume measurements at the onset of CLAD.

A total of 396 bilateral lung transplant recipients were analysed. At onset, CLAD was further categorised based on plethysmography. A restrictive CLAD (R-CLAD) was defined as a loss of total lung capacity from baseline. CLAD with air trapping (AT-CLAD) was defined as an increased ratio of residual volume to total lung capacity. Outcome was survival after CLAD onset. Patients with insufficient clinical information were excluded (n=95).

Of 301 lung transplant recipients, 94 (31.2%) developed CLAD. Patients with R-CLAD (n=20) and AT-CLAD (n=21), respectively, had a significantly worse survival (p<0.001) than patients with non-R/AT-CLAD. Both R-CLAD and AT-CLAD were associated with increased mortality when controlling for multiple confounding variables (hazard ratio (HR) 3.57, 95% CI 1.39–9.18; p=0.008; and HR 2.65, 95% CI 1.05–6.68; p=0.039). Furthermore, measurement of lung volumes was useful to identify patients with combined phenotypes.

Measurement of lung volumes in the long-term follow-up of lung transplant recipients allows the identification of patients who are at risk for worse outcome and warrant special consideration.

Phenotyping Chronic Lung Allograft Dysfunction Using Body Plethysmography and Computed Tomography

Restrictive subtype of chronic lung allograft dysfunction (CLAD) was recently described after lung transplantation. This study compares different definitions of a restrictive phenotype in CLAD patients and impact on survival. Eighty-nine CLAD patients out of 1191 screened patients (September 1987 to July 2012) were included as complete longitudinal lung volume measurements and chest computed tomography (CT) after CLAD onset was available. CT findings and lung volumes were quantified and survival was calculated for distinctive groups and predictive factors for worse survival were investigated. Graft survival in patients with total lung capacity (TLC) between 90% and 81% of baseline (BL) (n = 13, 15%) in CLAD course was similar to those with TLC >90% BL (n = 64, 56%; log-rank test p = 0.9). Twelve patients (13%) developed a TLC ≤80% BL and 10 (11%) had significant parenchymal changes on CT, of whom 6 (46%) also had TLC ≤80% BL. CT changes correlated with TLC ≤80% BL (Φ-coefficient = 0.48, p = 0.001). Patients with either TLC ≤80% or significant CT changes (n = 16, 18%) had a significantly reduced survival (log-rank p < 0.001). Forced vital capacity loss at CLAD onset was associated with poorer survival but did not correlate with the TLC or CT changes. A restrictive subtype of CLAD may be defined by either TLC ≤80% BL or severe parenchymal changes on chest CT.

Lung transplantation in IIP: A review

The idiopathic interstitial pneumonias (IIP) encompass a large and diverse subtype of interstitial lung disease (ILD) with idiopathic pulmonary fibrosis (IPF) and non-specific interstitial pneumonia (NSIP) being the most common types. Although pharmacologic treatments are available for most types of IIP, many patients progress to advanced lung disease and require lung transplantation. Close monitoring with serial functional and radiographic tests for disease progression coupled with early referral for lung transplantation are of great importance in the management of patients with IIP. Both single and bilateral lung transplantation are acceptable procedures for IIP. Procedure selection is a complex decision influenced by multiple factors related to patient, donor and transplant centre. While single lung transplant may reduce waitlist time and mortality, the long-term outcomes after bilateral lung transplantation may be slightly superior. There are numerous complications following lung transplantation including primary graft dysfunction, chronic lung allograft dysfunction (CLAD), infections, gastroesophageal reflux disease (GERD) and airway disease that limit post-transplant longevity. The median survival after lung transplantation is 4.7 years in patients with ILD, which is less than in patients with other underlying lung diseases. Although long-term survival is limited, this intervention still conveys a survival benefit and improved quality of life in suitable IIP patients with advanced lung disease and chronic hypoxemic respiratory failure.

Longitudinal Forced Vital Capacity Monitoring as a Prognostic Adjunct after Lung Transplantation

RATIONALE

After lung transplantation, spirometric values are routinely followed to assess graft function. FEV1 is used to characterize chronic allograft dysfunction, whereas the course of FVC change has been less acknowledged and rarely used.

OBJECTIVES

To better understand the temporal relationship and prognostic ability of FEV1 and FVC decline after lung transplantation.

METHODS

Serial FEV1 and FVC values were studied among 205 bilateral lung transplant recipients. Different decline patterns were characterized and evaluated for prognostic value via restricted mean modeling of mortality and times to other pertinent events.

MEASUREMENTS AND MAIN RESULTS

Baseline FEV1 was achieved earlier than baseline FVC (median, 296 vs. 378 d; P < 0.0001). Decline in FEV1 or FVC from their respective post-transplant baselines occurred in 85 patients (41%). Fifty-nine of 85 (69%) had an isolated FEV1 decline, with 80% later meeting the FVC decline criterion. This subsequent FVC decline was associated with worsening FEV1 and lower median survival. Twenty-five of 85 patients (29%) demonstrated concurrent FEV1 and FVC decline. Patients with concurrent decline had higher 1- and 5-year mortality rates (1-yr, 53% vs. 18%, P < 0.0001; 5-yr, 61% vs. 48%, P = 0.001). These patients were more likely to have rapid-onset of spirometry decline (P = 0.05) and lower FEV1% predicted (P = 0.04) at presentation.

CONCLUSIONS

FVC decline from its post-transplant baseline provides valuable prognostic information. Concurrent FEV1 and FVC decline identifies patients with fulminant, rapid deterioration and is the strongest clinical predictor of poor survival. Subsequent FVC decline in patients with an initial isolated FEV1 decline identifies disease progression and portends poor prognosis.

Restrictive chronic lung allograft dysfunction: Where are we now?

Chronic lung allograft dysfunction (CLAD) remains a frequent and troublesome complication after lung transplantation. Apart from bronchiolitis obliterans syndrome (BOS), a restrictive phenotype of CLAD (rCLAD) has recently been recognized, which occurs in approximately 30% of CLAD patients. The main characteristics of rCLAD include a restrictive pulmonary function pattern with a persistent decline in lung function (FEV1, FVC and TLC), persistent parenchymal infiltrates and (sub)pleural thickening on chest CT scan, as well as pleuroparenchymal fibroelastosis and obliterative bronchiolitis on histopathologic examination. Once diagnosed, median survival is only 6 to 18 months compared with 3 to 5 years with BOS. In this perspective we review the historic evidence for rCLAD and describe the different diagnostic criteria and prognosis. Furthermore, we elaborate on the typical radiologic and histopathologic presentations of rCLAD and highlight risk factors and mechanisms. Last, we summarize some opportunities for further research including the urgent need for adequate therapy. In this perspective we not only assess the current knowledge, but also clarify the existing gaps in understanding this increasingly recognized complication after lung transplantation.

An international ISHLT/ATS/ERS clinical practice guideline: diagnosis and management of bronchiolitis obliterans syndrome

Bronchiolitis obliterans syndrome (BOS) is a major complication of lung transplantation that is associated with poor survival. The International Society for Heart and Lung Transplantation, American Thoracic Society, and European Respiratory Society convened a committee of international experts to describe and/or provide recommendations for 1) the definition of BOS, 2) the risk factors for developing BOS, 3) the diagnosis of BOS, and 4) the management and prevention of BOS. A pragmatic evidence synthesis was performed to identify all unique citations related to BOS published from 1980 through to March, 2013. The expert committee discussed the available research evidence upon which the updated definition of BOS, identified risk factors and recommendations are based. The committee followed the GRADE (Grading of Recommendation, Assessment, Development and Evaluation) approach to develop specific clinical recommendations. The term BOS should be used to describe a delayed allograft dysfunction with persistent decline in forced expiratory volume in 1 s that is not caused by other known and potentially reversible causes of post-transplant loss of lung function. The committee formulated specific recommendations about the use of systemic corticosteroids, cyclosporine, tacrolimus, azithromycin and about re-transplantation in patients with suspected and confirmed BOS. The diagnosis of BOS requires the careful exclusion of other post-transplant complications that can cause delayed lung allograft dysfunction, and several risk factors have been identified that have a significant association with the onset of BOS. Currently available therapies have not been proven to result in significant benefit in the prevention or treatment of BOS. Adequately designed and executed randomised controlled trials that properly measure and report all patient-important outcomes are needed to identify optimal therapies for established BOS and effective strategies for its prevention.

Lung transplantation in adults and children: putting lung function into perspective

The number of lung transplants performed globally continues to increase year after year. Despite this growing experience, long-term outcomes following lung transplantation continue to fall far short of that described in other solid-organ transplant settings. Chronic lung allograft dysfunction (CLAD) remains common and is the end result of exposure to a multitude of potentially injurious insults that include alloreactivity and infection among others. Central to any description of the clinical performance of the transplanted lung is an assessment of its physiology by pulmonary function testing. Spirometry and the evaluation of forced expiratory volume in 1 s and forced vital capacity, remain core indices that are measured as part of routine clinical follow-up. Spirometry, while reproducible in detecting lung allograft dysfunction, lacks specificity in differentiating the different complications of lung transplantation such as rejection, infection and bronchiolitis obliterans. However, interpretation of spirometry is central to defining the different 'chronic rejection' phenotypes. It is becoming apparent that the maximal lung function achieved following transplantation, as measured by spirometry, is influenced by a number of donor and recipient factors as well as the type of surgery performed (single vs double vs lobar lung transplant). In this review, we discuss the wide range of variables that need to be considered when interpreting lung function testing in lung transplant recipients. Finally, we review a number of novel measurements of pulmonary function that may in the future serve as better biomarkers to detect and diagnose the cause of the failing lung allograft.

Immunosuppression and allograft rejection following lung transplantation: evidence to date

The enduring success of lung transplantation is built on the use of immunosuppressive drugs to stop the immune system from rejecting the newly transplanted lung allograft. Most patients receive a triple-drug maintenance immunosuppressive regimen consisting of a calcineurin inhibitor, an antiproliferative and corticosteroids. Induction therapy with either an antilymphocyte monoclonal or an interleukin-2 receptor antagonist are prescribed by many centres aiming to achieve rapid inhibition of recently activated and potentially alloreactive T lymphocytes. Despite this generic approach acute rejection episodes remain common, mandating further fine-tuning and augmentation of the immunosuppressive regimen. While there has been a trend away from cyclosporine and azathioprine towards a preference for tacrolimus and mycophenolate mofetil, this has not translated into significant protection from the development of chronic lung allograft dysfunction, the main barrier to the long-term success of lung transplantation. This article reviews the problem of lung allograft rejection and the evidence for immunosuppressive regimens used both in the short- and long-term in patients undergoing lung transplantation.

Impact of forced vital capacity loss on survival after the onset of chronic lung allograft dysfunction

RATIONALE

Emerging evidence suggests a restrictive phenotype of chronic lung allograft dysfunction (CLAD) exists; however, the optimal approach to its diagnosis and clinical significance is uncertain.

OBJECTIVES

To evaluate the hypothesis that spirometric indices more suggestive of a restrictive ventilatory defect, such as loss of FVC, identify patients with distinct clinical, radiographic, and pathologic features, including worse survival.

METHODS

Retrospective, single-center analysis of 566 consecutive first bilateral lung recipients transplanted over a 12-year period. A total of 216 patients developed CLAD during follow-up. CLAD was categorized at its onset into discrete physiologic groups based on spirometric criteria. Imaging and histologic studies were reviewed when available. Survival after CLAD diagnosis was assessed using Kaplan-Meier and Cox proportional hazards models.

MEASUREMENTS AND MAIN RESULTS

Among patients with CLAD, 30% demonstrated an FVC decrement at its onset. These patients were more likely to be female, have radiographic alveolar or interstitial changes, and histologic findings of interstitial fibrosis. Patients with FVC decline at CLAD onset had significantly worse survival after CLAD when compared with those with preserved FVC (P < 0.0001; 3-yr survival estimates 9% vs. 48%, respectively). The deleterious impact of CLAD accompanied by FVC loss on post-CLAD survival persisted in a multivariable model including baseline demographic and clinical factors (P < 0.0001; adjusted hazard ratio, 2.73; 95% confidence interval, 1.86-4.04).

CONCLUSIONS

At CLAD onset, a subset of patients demonstrating physiology more suggestive of restriction experience worse clinical outcomes. Further study of the biologic mechanisms underlying CLAD phenotypes is critical to improving long-term survival after lung transplantation.

Pilot study exploring lung allograft surfactant protein A (SP-A) expression in association with lung transplant outcome

Primary graft failure and chronic lung allograft dysfunction (CLAD) limit lung transplant long-term outcomes. Various lung diseases have been correlated with surfactant protein (SP) expression and polymorphisms. We sought to investigate the role of SP expression in lung allografts prior to implantation, in relation to posttransplant outcomes. The expression of SP-(A, B, C, D) mRNA was assayed in 42 allografts. Posttransplant assessments include pulmonary function tests, bronchoscopy, broncho-alveolar lavage fluid (BALF) and biopsies to determine allograft rejection. BALF was assayed for SP-A, SP-D in addition to cytokines IL-8, IL-12 and IL-2. The diagnosis of CLAD was evaluated 6 months after transplantation. Lung allografts with low SP-A mRNA expression prior to implantation reduced survival (Log-rank p < 0.0001). No association was noted for the other SPs. Allografts with low SP-A mRNA had greater IL-2 (p = 0.03) and IL-12 (p < 0.0001) in the BALF and a greater incidence of rejection episodes (p = 0.003). Levels of SP-A mRNA expression were associated with the SP-A2 polymorphisms (p = 0.015). Specifically, genotype 1A1A(0) was associated with lower SP-A mRNA expression (p < 0.05). Lung allografts with low levels of SP-A mRNA expression are associated with reduced survival. Lung allograft SP-A mRNA expression appears to be associated with SP-A gene polymorphisms.

Managing bronchiolitis obliterans syndrome (BOS) and chronic lung allograft dysfunction (CLAD) in children: what does the future hold?

The success of pediatric lung transplantation continues to be limited by long-term graft dysfunction. Historically this has been characterized as an obstructive spirometric defect in the form of the bronchiolitis obliterans syndrome (BOS). It is recognized, however, that this does not reflect many of the other acknowledged etiologies of chronic lung dysfunction-noting it is the sum of the parts that contribute to respiratory morbidity and mortality after transplant. The term chronic lung allograft dysfunction (CLAD) has been coined to reflect these other entities and, in particular, a group of relatively recently described lung disorders called the restrictive allograft syndrome (RAS). RAS is characterized by a restrictive spirometric defect. Although these entities have not yet been studied in a pediatric setting their association with poor compliance, antibody-mediated rejection (AMR), and post-infectious lung damage (particularly viral) warrants attention by pediatric lung transplant teams. Current therapy for the BOS subset of CLAD is otherwise limited to changing immunosuppressants and avoiding excessive infectious risk by avoiding over-immunosuppression. Long-term macrolide therapy in lung transplantation is not of proven efficacy. Reviewing previous BOS studies to explore restrictive spirometric cases and joint projects via groups like the International Pediatric Lung Transplant Collaborative will be the way forward to solve this pressing problem.

Donor surfactant protein D (SP-D) polymorphisms are associated with lung transplant outcome

Chronic lung allograft dysfunction (CLAD) is the major factor limiting long-term success of lung transplantation. Polymorphisms of surfactant protein D (SP-D), an important molecule within lung innate immunity, have been associated with various lung diseases. We investigated the association between donor lung SP-D polymorphisms and posttransplant CLAD and survival in 191 lung transplant recipients consecutively transplanted. Recipients were prospectively followed with routine pulmonary function tests. Donor DNA was assayed by pyrosequencing for SP-D polymorphisms of two single-nucleotide variations altering amino acids in the mature protein N-terminal domain codon 11 (Met(11) Thr), and in codon 160 (Ala(160) Thr) of the C-terminal domain. CLAD was diagnosed in 88/191 patients, and 60/191 patients have died. Recipients of allografts that expressed the homozygous Met(11) Met variant of aa11 had significantly greater freedom from CLAD development and better survival compared to those with the homozygous Thr(11) Th variant of aa11. No significant association was noted for SP-D variants of aa160. Lung allografts with the SP-D polymorphic variant Thr(11) Th of aa11 are associated with development of CLAD and reduced survival. The observed genetic differences of the donor lung, potentially with their effects on innate immunity, may influence the clinical outcomes after lung transplantation.

Lentivirus IL-10 gene therapy down-regulates IL-17 and attenuates mouse orthotopic lung allograft rejection

The purpose of the study was to examine the effect of lentivirus-mediated IL-10 gene therapy to target lung allograft rejection in a mouse orthotopic left lung transplantation model. IL-10 may regulate posttransplant immunity mediated by IL-17. Lentivirus-mediated trans-airway luciferase gene transfer to the donor lung resulted in persistent luciferase activity up to 6 months posttransplant in the isograft (B6 to B6); luciferase activity decreased in minor-mismatched allograft lungs (B10 to B6) in association with moderate rejection. Fully MHC-mismatched allograft transplantation (BALB/c to B6) resulted in severe rejection and complete loss of luciferase activity. In minor-mismatched allografts, IL-10-encoding lentivirus gene therapy reduced the acute rejection score compared with the lentivirus-luciferase control at posttransplant day 28 (3.0 ± 0.6 vs. 2.0 ± 0.6 (mean ± SD); p = 0.025; n = 6/group). IL-10 gene therapy also significantly reduced gene expression of IL-17, IL-23, and retinoic acid-related orphan receptor (ROR)-γt without affecting levels of IL-12 and interferon-γ (IFN-γ). Cells expressing IL-17 were dramatically reduced in the allograft lung. In conclusion, lentivirus-mediated IL-10 gene therapy significantly reduced expression of IL-17 and other associated genes in the transplanted allograft lung and attenuated posttransplant immune responses after orthotopic lung transplantation.

Lung transplantation

Lung transplantation may be the only intervention that can prolong survival and improve quality of life for those individuals with advanced lung disease who are acceptable candidates for the procedure. However, these candidates may be extremely ill and require ventilator and/or circulatory support as a bridge to transplantation, and lung transplantation recipients are at risk of numerous post-transplant complications that include surgical complications, primary graft dysfunction, acute rejection, opportunistic infection, and chronic lung allograft dysfunction (CLAD), which may be caused by chronic rejection. Many advances in pre- and post-transplant management have led to improved outcomes over the past decade. These include the creation of sound guidelines for candidate selection, improved surgical techniques, advances in donor lung preservation, an improving ability to suppress and treat allograft rejection, the development of prophylaxis protocols to decrease the incidence of opportunistic infection, more effective therapies for treating infectious complications, and the development of novel therapies to treat and manage CLAD. A major obstacle to prolonged survival beyond the early post-operative time period is the development of bronchiolitis obliterans syndrome (BOS), which is the most common form of CLAD. This manuscript discusses recent and evolving advances in the field of lung transplantation.

Restrictive allograft syndrome post lung transplantation is characterized by pleuroparenchymal fibroelastosis

We previously described restrictive allograft syndrome as a form of chronic lung allograft dysfunction, demonstrating restrictive pulmonary function decline. However, the histopathological correlates of restrictive allograft syndrome have yet to be satisfactorily described. We hypothesized that pulmonary pleuroparenchymal fibroelastosis, as has recently been described in bone marrow transplant recipients, may also be present in the lungs of patients with restrictive allograft syndrome. Retrospective review of 493 patients who underwent lung transplantation between 1 January 1996 and 30 June 2009, was conducted. Out of 47 patients with clinical features of restrictive allograft syndrome, 16 had wedge biopsy, re-transplant lung explant, or autopsy lung specimens available for review. All lungs showed varying degrees of pleural fibrosis. Fifteen of 16 showed parenchymal fibroelastosis, characterized by hypocellular collagen deposition with preservation and thickening of the underlying alveolar septal elastic network. The fibroelastosis was predominantly subpleural in distribution, with some cases also showing centrilobular and paraseptal distribution. A sharp demarcation was often seen between areas of fibroelastosis and unaffected lung parenchyma, with fibroblastic foci often present at this interface. Concurrent features of obliterative bronchiolitis were present in 14 cases. Another common finding was the presence of diffuse alveolar damage (13 cases), usually in specimens obtained <1 year after clinical onset of restrictive allograft syndrome. The single specimen in which fibroelastosis was not identified was obtained before the clinical onset of chronic lung allograft dysfunction, and showed features of diffuse alveolar damage. In conclusion, pleuroparenchymal fibroelastosis is a major histopathologic correlate of restrictive allograft syndrome, and was often found concurrently with diffuse alveolar damage. Our findings support a temporal sequence of diffuse alveolar damage followed by the development of pleuroparenchymal fibroelastosis in the histopathologic evolution of restrictive allograft syndrome.

Time-dependent changes in the risk of death in pure bronchiolitis obliterans syndrome (BOS)

BACKGROUND

The timing of disease onset may affect the prognosis in chronic lung allograft dysfunction (CLAD). The relationship between the timing of disease onset and the prognosis of CLAD and its sub-types, bronchiolitis obliterans syndrome (BOS) and restrictive allograft syndrome (RAS), was examined.

METHODS

Clinical records and pulmonary function data of 597 patients who underwent bilateral lung transplantation from 1996 to 2010 and survived for >3 months were examined.

RESULTS

Among 155 patients with a final diagnosis of BOS, patient survival after disease onset was significantly different according to disease-onset timing (BOS onset/post-BOS median survival: overall/1,438 days; <1 year/511 days; 1-2 years/1,199 days; 2-3 years/1,403 days; >3 years/did not reach median survival; p < 0.0001). The prognosis of RAS was generally poorer than that of BOS (overall post-RAS median survival, 377 days). Treating non-CLAD, CLAD, BOS, and RAS as time-dependent covariates, recipient sex-adjusted and age-adjusted Cox regression analysis demonstrated an overall mortality risk of BOS (reference: no CLAD) of 6.7 (95% confidence interval, 4.6-9.9). However, when patients survived 3 years without CLAD, the mortality risk of subsequent BOS was only 1.9 (95% confidence interval, 0.8-4.4) compared with no CLAD. The number of RAS patients was too small to obtain sufficient power to estimate time-dependent mortality risk.

CONCLUSION

Late-onset BOS showed a better prognosis than early-onset BOS. Studies that do not distinguish BOS from RAS may overestimate the mortality risk of BOS. Multicenter studies will be required to further elucidate risk factors toward the development of better management strategies for CLAD.

Bronchiolitis Obliterans Syndrome and Chronic Lung Allograft Dysfunction: Evolving Concepts and Nomenclature

Bronchiolitis obliterans syndrome (BOS) eventually occurs in the majority of lung transplant recipients who survive beyond 1 year, can greatly impair quality of life, and is, directly or indirectly, the major cause of delayed allograft dysfunction and recipient death. A number of associated events or conditions are strongly associated with the risk for developing BOS; these include acute rejection, gastroesophageal reflux, infections, and autoimmune reactions that can occur in the setting of alloimmune responses to the lung allograft as recipients are given intense immunosuppression to prevent allograft rejection. The term chronic lung allograft dysfunction (CLAD) is being increasingly used to refer to recipients with late allograft dysfunction that meets the spirometric criteria for the diagnosis of BOS, but clinicians should recognize that such dysfunction can occur for a variety of reasons other than BOS. The recently identified entity of restrictive allograft syndrome, which is now recognized as a relatively distinct phenotype of CLAD, has features that differentiate it from classic obstructive BOS. A number of other entities that can also significantly affect allograft function must also be considered when significant allograft dysfunction is encountered following lung transplantation.

Radiological patterns of primary graft dysfunction after lung transplantation evaluated by 64-multi-slice computed tomography: a descriptive study

We evaluated the diagnostic value of high-resolution computed tomography (HRCT) images generated from 64 detector multi-slice CT scanners (HRCT(64-MSCT) imaging) in relation to primary graft dysfunction (PGD) after lung-transplantation (LUTX) in a pilot study. PGD has mortality rates ranging from 17 to 50% over a 90-day period. Detailed HRCT lung images, reconstructed using 64-MSCT, may aid diagnostic and therapeutic efforts in PGD. Thirty-two patients were scanned four times within a year post-LUTX, in a single-centre prospective study. HRCT lung images were reviewed, evaluated and scored by two observers, for ground-glass (GG) opacities, consolidation, septal thickening (ST) and pulmonary embolism. Image and PGD scores were compared in each patient. GG and consolidation changes were largely present up until 2 weeks post-LUTX, and markedly reduced by the 12th week. ST was predominantly found in patients with PGD. There were no vascular changes found at CT angiographies. The most severe cases of GG opacities and consolidation were found in patients with PGD. ST seems to be an important indicator of PGD. HRCT(64-MSCT) imaging may be a useful tool for the identification of pathological features of PGD not detected by classical evaluation in patients undergoing LUTX.