Acute and chronic onset of bronchiolitis obliterans syndrome (BOS): are they different entities?

Inferior outcomes in lung transplant recipients with serum Pseudomonas aeruginosa specific cloaking antibodies

BACKGROUND

Chronic Lung Allograft Dysfunction (CLAD) limits long-term survival following lung transplantation. Colonization of the allograft by Pseudomonas aeruginosa is associated with an increased risk of CLAD and inferior overall survival. Recent experimental data suggests that 'cloaking' antibodies targeting the O-antigen of the P. aeruginosa lipopolysaccharide cell wall (cAbs) attenuate complement-mediated bacteriolysis in suppurative lung disease.

METHODS

In this retrospective cohort analysis of 123 lung transplant recipients, we evaluated the prevalence, risk factors and clinical impact of serum cAbs following transplantation.

RESULTS

cAbs were detected in the sera of 40.7% of lung transplant recipients. Cystic fibrosis and younger age were associated with increased risk of serum cAbs (CF diagnosis, OR 6.62, 95% CI 2.83-15.46, p < .001; age at transplant, OR 0.69, 95% CI 0.59-0.81, p < .001). Serum cAbs and CMV mismatch were both independently associated with increased risk of CLAD (cAb, HR 4.34, 95% CI 1.91-9.83, p < .001; CMV mismatch (D+/R-), HR 5.40, 95% CI 2.36-12.32, p < .001) and all-cause mortality (cAb, HR 2.75, 95% CI 1.27-5.95, p = .010, CMV mismatch, HR 3.53, 95% CI 1.62-7.70, p = .002) in multivariable regression analyses.

CONCLUSIONS

Taken together, these findings suggest a potential role for 'cloaking' antibodies targeting P. aeruginosa LPS O-antigen in the immunopathogenesis of CLAD.

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.

Extracorporeal photopheresis to attenuate decline in lung function due to refractory obstructive allograft dysfunction

BACKGROUND

This study was designed to prospectively evaluate the efficacy of extracorporeal photopheresis (ECP) to attenuate the rate of decline of FEV₁ in lung transplant recipients with refractory bronchiolitis obliterans. Due to an observed higher than expected early mortality, a preliminary analysis was performed.

STUDY DESIGN AND METHODS

Subjects from 10 lung transplant centres were assigned to ECP treatment or to observation based on spirometric criteria, with potential crossover for those under observation. The primary endpoint of this study was to assess response to ECP (i.e., greater than a 50% decrease in the rate of FEV₁ decline) before and 6 months after initiation of ECP. Mortality was also evaluated 6 and 12 months after enrolment as a secondary endpoint.

RESULTS

Of 44 enrolled subjects, 31 were assigned to ECP treatment while 13 were initially assigned to observation on a non-random basis using specific spirometric inclusion criteria (seven of the observation patients subsequently crossed over to receive ECP). Of evaluable patients, 95% of patients initially assigned to treatment responded to ECP with rates of FEV₁ decline that were reduced by 93% in evaluable ECP-treated patients. Mortality rates (percentages) at 6 and 12 months after enrolment was 32% and 41%, respectively. The most common (92%) primary cause of death was respiratory or graft failure. Significantly (p = 0.002) higher rates of FEV₁ decline were observed in the non-survivors (-212 ± 177 ml/month) when compared to the survivors (-95 ± 117 ml/month) 12 months after enrolment. In addition, 18 patients with bronchiolitis obliterans syndrome (BOS) diagnosis within 6 months of enrolment had lost 38% of their baseline lung function at BOS diagnosis and 50% of their lung function at enrolment.

CONCLUSIONS

These analyses suggest that earlier detection and treatment of BOS should be considered to appreciate improved outcomes with ECP.

Chronic Lung Allograft Dysfunction: Review of CT and Pathologic Findings

Chronic lung allograft dysfunction (CLAD) is the most common cause of mortality in lung transplant recipients after the 1st year of transplantation. CLAD has traditionally been classified into two distinct obstructive and restrictive forms: bronchiolitis obliterans syndrome and restrictive allograft syndrome. However, CLAD may manifest with a spectrum of imaging and pathologic findings and a combination of obstructive and restrictive physiologic abnormalities. Although the initial CT manifestations of CLAD may be nonspecific, the progression of findings at follow-up should signal the possibility of CLAD and may be present on imaging studies prior to the development of functional abnormalities of the lung allograft. This review encompasses the evolution of CT findings in CLAD, with emphasis on the underlying pathogenesis and pathologic condition, to enhance understanding of imaging findings. The purpose of this article is to familiarize the radiologist with the initial and follow-up CT findings of the obstructive, restrictive, and mixed forms of CLAD, for which early diagnosis and treatment may result in improved survival. Supplemental material is available for this article. © RSNA, 2021.

Controversies and emerging topics in lung transplantation

Lung transplantation provides a realistic hope of improved survival and enhanced quality of life. However, outcomes can be disappointing, meaning many decisions are highly controversial. Practice is largely based on expert opinion and there is a dearth of high-level evidence. Not surprisingly, this leads to centre-specific practices that may vary considerably in controversial areas. The aim of this review, therefore, is to explore some of those domains and present the available evidence. As the science of lung transplantation approaches its fifth decade, we are only now reaching a critical mass of clinicians and scientific researchers to enable adequately powered studies to assist in informing our approach to some of these controversies.

Lung transplantation provides a realistic hope of improved survival and enhanced quality of life. However, outcomes can be disappointing, meaning many decisions are highly controversial. Better evidence is desperately needed.http://ow.ly/Dl4N30maYV9

Development of a Multivariate Prediction Model for Early-Onset Bronchiolitis Obliterans Syndrome and Restrictive Allograft Syndrome in Lung Transplantation

BACKGROUND

Chronic lung allograft dysfunction and its main phenotypes, bronchiolitis obliterans syndrome (BOS) and restrictive allograft syndrome (RAS), are major causes of mortality after lung transplantation (LT). RAS and early-onset BOS, developing within 3 years after LT, are associated with particularly inferior clinical outcomes. Prediction models for early-onset BOS and RAS have not been previously described.

METHODS

LT recipients of the French and Swiss transplant cohorts were eligible for inclusion in the SysCLAD cohort if they were alive with at least 2 years of follow-up but less than 3 years, or if they died or were retransplanted at any time less than 3 years. These patients were assessed for early-onset BOS, RAS, or stable allograft function by an adjudication committee. Baseline characteristics, data on surgery, immunosuppression, and year-1 follow-up were collected. Prediction models for BOS and RAS were developed using multivariate logistic regression and multivariate multinomial analysis.

RESULTS

Among patients fulfilling the eligibility criteria, we identified 149 stable, 51 BOS, and 30 RAS subjects. The best prediction model for early-onset BOS and RAS included the underlying diagnosis, induction treatment, immunosuppression, and year-1 class II donor-specific antibodies (DSAs). Within this model, class II DSAs were associated with BOS and RAS, whereas pre-LT diagnoses of interstitial lung disease and chronic obstructive pulmonary disease were associated with RAS.

CONCLUSION

Although these findings need further validation, results indicate that specific baseline and year-1 parameters may serve as predictors of BOS or RAS by 3 years post-LT. Their identification may allow intervention or guide risk stratification, aiming for an individualized patient management approach.

Early extracellular matrix changes are associated with later development of bronchiolitis obliterans syndrome after lung transplantation

Background

Chronic lung allograft dysfunction in the form of bronchiolitis obliterans syndrome (BOS) is the main cause of death beyond 1-year post-lung transplantation. The disease-initiating triggers as well as the molecular changes leading to fibrotic alterations in the transplanted lung are largely unknown. The aim of this study was to identify potential early changes in the extracellular matrix (ECM) in different compartments of the transplanted lung prior to the development of BOS.

Methods

Transbronchial biopsies from a cohort of 58 lung transplantation patients at the Copenhagen University hospital between 2005 and 2006, with or without development of BOS in a 5-year follow-up, were obtained 3 and 12 months after transplantation. Biopsies were assessed for total collagen, collagen type IV and biglycan in the alveolar and small airway compartments using Masson's Trichrome staining and immunohistochemistry.

Results

A time-specific and compartment-specific pattern of ECM changes was detected. Alveolar total collagen (p=0.0190) and small airway biglycan (p=0.0199) increased between 3 and 12 months after transplantation in patients developing BOS, while collagen type IV (p=0.0124) increased in patients without BOS. Patients with early-onset BOS mirrored this increase. Patients developing grade 3 BOS showed distinct ECM changes already at 3 months. Patients with BOS with treated acute rejections displayed reduced alveolar total collagen (p=0.0501) and small airway biglycan (p=0.0485) at 3 months.

Conclusions

Patients with future BOS displayed distinct ECM changes compared with patients without BOS. Our data indicate an involvement of alveolar and small airway compartments in post-transplantation changes in the development of BOS.

Quality of Life and Bronchiolitis Obliterans Syndrome in Patients after Lung Transplantation

Background

Lung transplantation has become an established and effective treatment for patients with end-stage pulmonary disease.

Objective

To investigate health-related quality of life in correlation with occurrence and degree of bronchiolitis obliterans syndrome after transplantation.

Methods

In a cross-sectional study design, 119 consecutive lung transplant recipients (63.9% bilateral and 36.1% single lung transplants) responded voluntarily to a set of standardized questionnaires (12-Item Short-Form Health Survey, Center for Epidemiologic Studies-Depression Scale, Coping With Everyday Life, Beck Anxiety Inventory, Zerssen list of complaints) that covered health-related quality of life and psychological well being. Also, we performed pulmonary function studies to clinically grade bronchiolitis obliterans syndrome in all patients.

Results

In this cohort, 41.2% of patients developed bronchiolitis obliterans syndrome at a mean interval of 5.6 years after lung transplantation. Actuarial freedom from bronchiolitis obliterans syndrome was 90.1%±2.3% at 1 year, 79.9%±3.7% at 3 years, and 59.5%±4.8% at 5 years after lung transplantation. Recipients with bronchiolitis obliterans syndrome reported significantly lower well being and quality of life than those without bronchiolitis obliterans syndrome, who scored similar to healthy volunteers. In a subanalysis, body functioning ( P<.001) and related areas of coping ( P<.001) were mostly affected by bronchiolitis obliterans syndrome.

Conclusions

Quality of life was negatively affected by the onset of bronchiolitis obliterans syndrome. However, even patients who develop bronchiolitis obliterans syndrome reported a temporary benefit from lung transplantation. In addition to optimal medical care and efforts in preventing bronchiolitis obliterans syndrome, psychological support of lung recipients seems to be essential, especially when bronchiolitis obliterans syndrome occurs.

Predictors of survival in restrictive chronic lung allograft dysfunction after lung transplantation

BACKGROUND

Chronic lung allograft dysfunction (CLAD) is the main factor limiting long-term survival after lung transplantation. Besides bronchiolitis obliterans syndrome, a restrictive phenotype of CLAD (rCLAD) exists, which is associated with poor prognosis after diagnosis. However, survival determinants for rCLAD remain to be elucidated. Our aim in this study was to establish parameters predicting survival in patients with rCLAD.

METHODS

All patients diagnosed with rCLAD in 2 lung transplant centers were assessed in a retrospective manner. Various clinical parameters [demography, pulmonary function, bronchoalveolar lavage (BAL), histopathology, radiology and blood differentials] at rCLAD diagnosis were correlated with graft survival using unadjusted and adjusted analysis.

RESULTS

A total of 53 patients with rCLAD were included with a median graft survival after diagnosis of 1.1 years. Univariate analysis demonstrated that lower-lobe-dominant or diffuse infiltrates on chest computed tomography, presence of an identifiable trigger before rCLAD onset, lymphocytic bronchiolitis, increased BAL neutrophilia, increased BAL eosinophilia and increased blood eosinophils were associated with inferior graft survival after rCLAD diagnosis. Multivariate analysis confirmed the association of location of infiltrates and blood eosinophilia on graft survival.

CONCLUSION

In this study we have identified parameters associated with graft survival after rCLAD diagnosis that may be useful to predict prognosis.

Current views on chronic rejection after lung transplantation

Chronic lung allograft dysfunction (CLAD) was recently introduced as an overarching term mainly to classify patients with chronic rejection after lung transplantation, although other conditions may also qualify for CLAD. Initially, only the development of a persistent and obstructive pulmonary function defect, clinically identified as bronchiolitis obliterans syndrome (BOS), was considered as chronic rejection, if no other cause could be identified. It became clear in recent years that some patients do not qualify for this definition, although they developed a chronic and persistent decrease in FEV1 , without another identifiable cause. As the pulmonary function decline in these patients was rather restrictive, this was called restrictive allograft syndrome (RAS). In the present review, we will further elaborate on these two CLAD phenotypes, with specific attention to the diagnostic criteria, the role of pathology and imaging, the risk factors, outcome, and the possible treatment options.

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.

Fitting and interpreting continuous-time latent Markov models for panel data

Multistate models characterize disease processes within an individual. Clinical studies often observe the disease status of individuals at discrete time points, making exact times of transitions between disease states unknown. Such panel data pose considerable modeling challenges. Assuming the disease process progresses accordingly, a standard continuous-time Markov chain (CTMC) yields tractable likelihoods, but the assumption of exponential sojourn time distributions is typically unrealistic. More flexible semi-Markov models permit generic sojourn distributions yet yield intractable likelihoods for panel data in the presence of reversible transitions. One attractive alternative is to assume that the disease process is characterized by an underlying latent CTMC, with multiple latent states mapping to each disease state. These models retain analytic tractability due to the CTMC framework but allow for flexible, duration-dependent disease state sojourn distributions. We have developed a robust and efficient expectation-maximization algorithm in this context. Our complete data state space consists of the observed data and the underlying latent trajectory, yielding computationally efficient expectation and maximization steps. Our algorithm outperforms alternative methods measured in terms of time to convergence and robustness. We also examine the frequentist performance of latent CTMC point and interval estimates of disease process functionals based on simulated data. The performance of estimates depends on time, functional, and data-generating scenario. Finally, we illustrate the interpretive power of latent CTMC models for describing disease processes on a dataset of lung transplant patients. We hope our work will encourage wider use of these models in the biomedical setting.

Bronchiolitis obliterans syndrome: the Achilles' heel of lung transplantation

Lung transplantation is a therapeutic option for patients with end-stage pulmonary disorders. Unfortunately, chronic lung allograft dysfunction (CLAD), most commonly manifest as bronchiolitis obliterans syndrome (BOS), continues to be highly prevalent and is the major limitation to long-term survival. The pathogenesis of BOS is complex and involves alloimmune and nonalloimmune pathways. Clinically, BOS manifests as airway obstruction and dyspnea that are classically progressive and ultimately fatal; however, the course is highly variable, and distinguishable phenotypes may exist. There are few controlled studies assessing treatment efficacy, but only a minority of patients respond to current treatment modalities. Ultimately, preventive strategies may prove more effective at prolonging survival after lung transplantation, but their remains considerable debate and little data regarding the best strategies to prevent BOS. A better understanding of the risk factors and their relationship to the pathological mechanisms of chronic lung allograft rejection should lead to better pharmacological targets to prevent or treat this syndrome.

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.

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.

The Role of Infections in BOS

Background: Infectious agents, particularly cytomegalovirus (CMV), have long been considered to be potential triggers for BOS, although the exact magnitude of the role of infections and the mechanisms thereof remain an area of active research. Methods: This chapter will review previous literature and newer results concerning the possible roles of CMV, other herpesviruses, community-acquired respiratory viruses, bacteria (including Pseudomonas, other gram-negative, gram-positive, and atypical organisms), and fungi, including colonization as well as invasive infection. Results: The text reviews and evaluates the body of literature supporting a role for these infectious agents as risk factors for BOS and time to BOS. Changing patterns of infection over time are taken into account, and studies that have shown an association between BOS (or lack thereof) and CMV are reviewed. Strategies for prevention or early treatment of infections are discussed as potential means of preserving allograft function long term. Immunizations, stringent infection-control practices, and antimicrobial treatment including newer therapies will be discussed. Conclusion: In addition to the classic literature that has focused on CMV, an expanding spectrum of infectious organisms has been implicated as possible risk factors for BOS. Increasing knowledge of the impact of long-term antiviral suppression, prophylaxis, and outcomes of early therapy will help guide future recipient management.

Rapid acute onset of bronchiolitis obliterans syndrome in a lung transplant recipient after respiratory syncytial virus infection

Bronchiolitis obliterans syndrome (BOS) can have either an acute or chronic onset with an abrupt or insidious course. The diagnosis is typically achieved by physiological criteria with development of a sustained decline in expiratory flow rates for at least 3 weeks. We review the rapid development of acute BOS and bronchiectasis after respiratory syncytial virus infection in a lung transplant recipient, who had been doing well with normal pulmonary function for 3 years after lung transplantation.

Lung function early after lung transplantation is correlated with the frequency of regulatory T cells

PURPOSES

Outcomes following lung transplantation are limited by bronchiolitis obliterans syndrome (BOS). As the number of circulating regulatory T cells (Treg) is lower in lung recipients with BOS than in stable lung recipients, we hypothesized that Treg is also correlated with lung function in the early post-transplantation period.

METHODS

This prospective study included 18 consecutive patients whose lung function parameters were recorded 3 weeks and 3 months after transplantation, between February and July 2007. Peripheral blood mononuclear cells were stained with anti-CD3, -CD4, -CD8, -CD19, -CD25, -CD28, -CD45RA, -CD45RO, -CD69, -CD127, -CTLA4, and -Foxp3 antibodies and FACS assays were performed. In addition, intracellular cytokines were stained for FACS.

RESULTS

Treg-specific markers (Foxp3, CD127(lo), and CTLA4) in the CD25+ CD4+ population were correlated with both forced expiratory volume in 1 s and forced vital capacity. Th1-cytokine secretion was more dominant in CD4+ CD25+ T cells than in CD4+ CD25- T cells. In contrast, Th2 and Treg cytokine secretion was the dominant response in stable recipients.

CONCLUSIONS

The frequency of Treg cells was positively correlated with good lung function in the early period after lung transplantation.

Survival determinants in lung transplant patients with chronic allograft dysfunction

BACKGROUND

Chronic lung allograft dysfunction (CLAD) remains the leading cause of mortality after lung transplantation.

METHODS

In this retrospective single-center study, we aimed to identify different phenotypes of and risk factors for mortality after CLAD diagnosis using univariate and multivariate Cox proportional hazard survival regression analysis.

RESULTS

CLAD was diagnosed in 71 of 294 patients (24.2%) at 30.9±22.8 months after transplantation. Pulmonary function was obstructive in 51 (71.8%) of the CLAD patients, restrictive in 20 (28.2%) patients, of whom 17 had persistent parenchymal infiltrates on pulmonary computer tomography (CAT) scan. In univariate analysis, previous development of neutrophilic reversible allograft dysfunction (NRAD, P=0.012) and a restrictive pulmonary function (P=0.0024) were associated with a worse survival, whereas there was a strong trend for early development of CLAD and persistent parenchymal infiltrates on CAT scan (P=0.067 and 0.056, respectively). In multivariate analysis, early development of CLAD (P=0.0067), previous development of NRAD (P=0.0016), and a restrictive pulmonary function pattern (P=0.0005) or persistent parenchymal infiltrates on CAT scan (P=0.0043) remained significant.

CONCLUSION

Although most CLAD patients develop an obstructive pulmonary function, 28% develop a restrictive pulmonary function, compatible with the recently defined restrictive allograft syndrome phenotype. Early-onset CLAD, previous development of NRAD, and the development of restrictive allograft syndrome are associated with worse survival after CLAD has been diagnosed.

A review of bronchiolitis obliterans syndrome and therapeutic strategies

Lung transplantation is an important treatment option for patients with advanced lung disease. Survival rates for lung transplant recipients have improved; however, the major obstacle limiting better survival is bronchiolitis obliterans syndrome (BOS). In the last decade, survival after lung retransplantation has improved for transplant recipients with BOS. This manuscript reviews BOS along with the current therapeutic strategies, including recent outcomes for lung retransplantation.

Lung transplantation in autoimmune diseases

In the last 45 years, lung transplantation has evolved from its status as a rare extreme form of surgical therapy for the treatment of advanced lung diseases to an accepted therapeutic option for select patients. Although pulmonary fibrosis and pulmonary vascular diseases are important indications for lung transplantation, only a small percentage of transplants are performed in patients with collagen vascular diseases. The reasons for this low number are multifactorial. This article reviews issues relevant to all lung transplant candidates and recipients as well as those specific to patients with autoimmune diseases.

Restrictive allograft syndrome (RAS): a novel form of chronic lung allograft dysfunction

BACKGROUND

Bronchiolitis obliterans syndrome (BOS) with small-airway pathology and obstructive pulmonary physiology may not be the only form of chronic lung allograft dysfunction (CLAD) after lung transplantation. Characteristics of a form of CLAD consisting of restrictive functional changes involving peripheral lung pathology were investigated.

METHODS

Patients who received bilateral lung transplantation from 1996 to 2009 were retrospectively analyzed. Baseline pulmonary function was taken as the time of peak forced expiratory volume in 1 second (FEV(1)). CLAD was defined as irreversible decline in FEV(1) < 80% baseline. The most accurate threshold to predict irreversible decline in total lung capacity and thus restrictive functional change was at 90% baseline. Restrictive allograft syndrome (RAS) was defined as CLAD meeting this threshold. BOS was defined as CLAD without RAS. To estimate the effect on survival, Cox proportional hazards models and Kaplan-Meier analyses were used.

RESULTS

Among 468 patients, CLAD developed in 156; of those, 47 (30%) showed the RAS phenotype. Compared with the 109 BOS patients, RAS patients showed significant computed tomography findings of interstitial lung disease (p < 0.0001). Prevalence of RAS was approximately 25% to 35% of all CLAD over time. Patient survival of RAS was significantly worse than BOS after CLAD onset (median survival, 541 vs 1,421 days; p = 0.0003). The RAS phenotype was the most significant risk factor of death among other variables after CLAD onset (hazard ratio, 1.60; confidential interval, 1.23-2.07).

CONCLUSIONS

RAS is a novel form of CLAD that exhibits characteristics of peripheral lung fibrosis and significantly affects survival of lung transplant patients.

Pulmonary complications of lung transplantation

Lung transplantation is an effective treatment option for select patients with a variety of end-stage lung diseases. Although transplant can significantly improve the quality of life and prolong survival, a myriad of pulmonary complications may result in significant morbidity and limit long-term survival. The recognition and early treatment of these complications is important for optimizing outcomes. This article provides an overview and update of the pulmonary complications that may be commonly encountered by pulmonologists caring for these patients.

Semi-Markov models with phase-type sojourn distributions

Continuous-time multistate models are widely used for categorical response data, particularly in the modeling of chronic diseases. However, inference is difficult when the process is only observed at discrete time points, with no information about the times or types of events between observation times, unless a Markov assumption is made. This assumption can be limiting as rates of transition between disease states might instead depend on the time since entry into the current state. Such a formulation results in a semi-Markov model. We show that the computational problems associated with fitting semi-Markov models to panel-observed data can be alleviated by considering a class of semi-Markov models with phase-type sojourn distributions. This allows methods for hidden Markov models to be applied. In addition, extensions to models where observed states are subject to classification error are given. The methodology is demonstrated on a dataset relating to development of bronchiolitis obliterans syndrome in post-lung-transplantation patients.

Bronchiolitis obliterans syndrome development in lung transplantation patients

The main cause of death in lung transplantation patients is chronic rejection, known as bronchiolitis obliterans syndrome (BOS). There are many variables associated with its appearance. The aim of this study was to identify factors associated with BOS and its impact on survival among lung transplantation patients.

METHODS

We retrospectively analyzed charts of lung transplant patients from 1999 to 2009, evaluating survival, BOS, and associated factors.

RESULTS

Fifty-six patients have been transplanted with a 5-year survival of 55%. Eighteen (32%) developed BOS, at a mean age at diagnosis of 57 years (range 16-74). According to BOS classification, seven patients (38.8%) were type 2 and six (33.3%) type 3. Half the patients developed BOS at a mean of 8.5 months after transplantation with a mean survival of 18.5 months (range 2-61). Among the factors analyzed, 13 patients (72%) displayed acute cellular rejection and nine (50%) gastroesophageal reflux disease (GERD) diagnosed by pHmetry, both of which were significantly associated with BOS (P = .005). Among seven lung transplantation patients with invasive cytomegalovirus disease, the four who developed BOS (P = .04) showed the worst survival (P = .05). Four of the six patients with severe BOS (66.6%) died at a mean of 10.6 months after the diagnosis. The main cause of death was respiratory insufficiency.

CONCLUSIONS

BOS was associated with worse survival. The presence of acute cellular rejection episodes, CMV disease, and GERD were factors associated with chronic lung rejection.

Survival after bronchiolitis obliterans syndrome among bilateral lung transplant recipients

RATIONALE

Despite the importance of bronchiolitis obliterans syndrome (BOS) in lung transplantation, little is known regarding the factors that influence survival after the onset of this condition, particularly among bilateral transplant recipients.

OBJECTIVES

To identify factors that influence survival after the onset of BOS among bilateral lung transplant recipients.

METHODS

The effect of demographic or clinical factors, occurring before BOS, upon survival after the onset of BOS was studied in 95 bilateral lung transplant recipient using Cox proportional hazards models.

MEASUREMENTS AND MAIN RESULTS

Although many factors, including prior acute rejection or rejection treatments, were not associated with survival after BOS, BOS onset within 2 years of transplantation (early-onset BOS), or BOS onset grade of 2 or 3 (high-grade onset) were predictive of significantly worse survival (early onset P = 0.04; hazard ratio, 1.84; 95% confidence interval, 1.03-3.29; high-grade onset P = 0.003; hazard ratio, 2.40; 95% confidence interval, 1.34-4.32). The effects of both early onset and high-grade onset on survival persisted in multivariable analysis and after adjustment for concurrent treatments. Results suggested an interaction might exist between early onset and high-grade onset. In particular, high-grade onset of BOS, regardless of its timing after transplant, is associated with a very poor prognosis.

CONCLUSIONS

The course of BOS after bilateral lung transplantation is variable. Distinct patterns of survival after BOS are evident and related to timing or severity of onset. Further characterization of these subgroups should provide a more rational basis from which to design, stratify, and assess response in future BOS treatment trials.

Lung

Experiments with animals in the 1940 and 1950s demonstrated that lung transplantation was technically possible [33]. In 1963, Dr. James Hardy performed the first human lung transplantation. The recipient survived 18 days, ultimately succumbing to renal failure and malnutrition [58]. From 1963 through 1978, multiple attempts at lung transplantation failed because of rejection and complications at the bronchial anastomosis. In the 1980s, improvements in immunosuppression, especially the introduction of cyclosporin A, and enhanced surgical techniques led to renewed interest in organ transplantation. In 1981, a 45-year-old-woman received the first successful heart–lung transplantation for idiopathic pulmonary arterial hypertension (IPAH) [106]. She survived 5 years after the procedure. Two years later the first successful single lung transplantation for idiopathic pulmonary fibrosis (IPF) [128] was reported, and in 1986 the first double lung transplantation for emphysema [25] was performed.

Course of Illness after the Onset of Chronic Rejection in Lung Transplant Recipients

Background Despite the overall negative impact of chronic rejection on quality of life and survival after lung transplant, the specific clinical indicators of deterioration have not been identified.

Objectives To describe the course of illness after the onset of chronic rejection, including demographic and transplant variables, morbidity, mortality, health resource utilization, and end-of-life care, and to identify clinical indicators of deterioration in health and limited survival after the onset of chronic rejection.

Methods The medical records of 311 recipients of lung transplants between 1998 and 2004 were reviewed retrospectively to identify 60 recipients who experienced chronic rejection.

Results Median survival after chronic rejection was 31.34 months. Time to rejection (mean, 26.05 months; SD, 16.85) was significantly correlated with overall survival without need of a retransplant (r = 0.64; P &lt; .001). The earlier the onset of chronic rejection or the need for oxygen at home, the shorter was the period of survival after chronic rejection and the more frequent were hospital and intensive care unit admissions and prolonged stays. Of the 26 recipients who died, 65% died at the transplant center, and all but 1 died in the intensive care unit; 3 died after multiple attempts of cardiopulmonary resuscitation; life support was ultimately withdrawn in 69%.

Conclusions Lung transplant recipients who experience chronic graft rejection have high rates of morbidity, mortality, and health resource utilization; however, the course of illness after chronic rejection is highly variable.

Long-term azithromycin for bronchiolitis obliterans syndrome after lung transplantation

BACKGROUND

Bronchiolitis obliterans syndrome (BOS) is a major cause of morbidity and mortality after lung transplantation (LTx). Macrolides are a promising treatment option for BOS. The objective of this study was to determine long-term results of azithromycin treatment in patients with BOS. Variables to predict treatment response were evaluated.

METHODS

An observational study in a single center was performed. Eighty-one adult LTx-recipients (single, double, combined, and re-do) with at least BOS stage 0p (mean forced expired volume in 1 second [FEV1] 55+/-19%) were included. For treatment, 250 mg of oral azithromycin was administered three times per week.

RESULTS

Twenty-four of 81 (30%) patients showed improvement in FEV1 after 6 months, 22/24 already after 3 months of treatment. By univariate analysis, responders at 6 months had higher pretreatment bronchoalveolar lavage (BAL) neutrophils (51+/-29 vs. 21+/-24%). A cutoff value of <20% in pretreatment BAL had a negative predictive value of 0.91 for treatment response. Thirty-three patients (40%) showed disease progression during follow-up (491+/-165 days). Cox regression analysis identified a rapid pretreatment decline in FEV1 and comedication of an mammalian target of rapamycin inhibitor as positive predictors and proton pump inhibitor comedication and a treatment response at 3 months as negative predictors for disease progression (FEV1<90% baseline).

CONCLUSIONS

Azithromycin can improve airflow limitation in a significant proportion of patients with even long-standing BOS. The majority of responders were identified after 3 months of treatment. Results indicate the predictive value of BAL neutrophilia for treatment response and pretreatment course of FEV1 as a variable for disease progression. Beneficial effects on gastroesophageal reflux disease may be a mechanism of action.

Alcohol ingestion by donors amplifies experimental airway disease after heterotopic transplantation

RATIONALE

Obliterative bronchiolitis (OB) after lung transplantation is triggered by alloimmunity, but is ultimately mediated by transforming growth factor (TGF)-beta(1)-dependent airway fibrosis.

OBJECTIVES

Chronic alcohol use increases TGF-beta(1) expression and renders the lung susceptible to injury. Therefore, we hypothesized that donor alcohol abuse could prime the lung allograft for OB, as many organ donors have a history of alcohol abuse.

METHODS

Tracheas from control and alcohol-fed rats (8 wk) were heterotopically transplanted into recipients with varying degrees of alloimmune mismatch and analyzed for obliterative airway disease severity on Postoperative Day 21.

MEASUREMENTS AND MAIN RESULTS

Although donor alcohol ingestion did not increase the number of antigen-presenting cells or infiltrating lymphocytes, it nevertheless increased allograft lumenal collagen content fourfold compared with allografts from control donors. In parallel, alcohol increased TGF-beta(1) and alpha-smooth muscle actin expression in allografts. Alcohol amplified airway disease even in isografts with minor alloimmune mismatches. In contrast, it did not cause any airway disease in isografts in a pure isogenic background, suggesting that a minimal alloimmune response is necessary to trigger alcohol-induced airway fibrosis.

CONCLUSIONS

Although alloimmune inflammation is required to initiate airway disease, alcohol primes the allograft for greater TGF-beta(1) expression, myofibroblast transdifferentiation, and fibrosis than by alloimmune inflammation alone. This has serious clinical implications, as many lung donors have underlying alcohol abuse that may prime the allograft recipient for subsequent OB.

Challenges in pulmonary fibrosis. 2: Bronchiolocentric fibrosis

Bronchiolocentric fibrosis is essentially represented by the pathological pattern of constrictive fibrotic bronchiolitis obliterans. The corresponding clinical condition (obliterative bronchiolitis) is characterised by dyspnoea, airflow obstruction at lung function testing and air trapping with characteristic mosaic features on expiratory high resolution CT scans. Bronchiolitis obliterans may result from many causes including acute diffuse bronchiolar damage after inhalation of toxic gases or fumes, alloimmune chronic processes after lung or haematopoietic stem cell transplantation, or connective tissue disease (especially rheumatoid arthritis). Airway-centred interstitial fibrosis and bronchiolar metaplasia are other features of bronchiolocentric fibrosis.

Course of FEV(1) after onset of bronchiolitis obliterans syndrome in lung transplant recipients

RATIONALE

Bronchiolitis obliterans syndrome (BOS), defined by loss of lung function, develops in the majority of lung transplant recipients. However, there is a paucity of information on the subsequent course of lung function in these patients.

OBJECTIVES

To characterize the course of FEV(1) over time after development of BOS and to determine the predictors that influence the rate of functional decline of FEV(1).

METHODS

FEV(1)% predicted (FEV(1)%pred) trajectories were studied in 111 lung transplant recipients with BOS by multivariate, linear, mixed-effects statistical models.

MEASUREMENTS AND MAIN RESULTS

FEV(1)%pred varied over time after BOS onset, with the steepest decline typically seen in the first 6 months (12% decline; p < 0.0001). Bilateral lung transplant recipients had significantly higher FEV(1)%pred at BOS diagnosis (71 vs. 47%; p < 0.0001) and at 24 months after BOS onset (58 vs. 41%; p = 0.0001). Female gender and pretransplant diagnosis of idiopathic pulmonary fibrosis were associated with a steeper decline in FEV(1)%pred in the first 6 months after BOS diagnosis (p = 0.02 and 0.04, respectively). A fall in FEV(1) greater than 20% in the 6 months preceding BOS (termed "rapid onset") was associated with shorter time to BOS onset (p = 0.01), lower FEV(1)%pred at BOS onset (p < 0.0001), steeper decline in the first 6 months (p = 0.03), and lower FEV(1)%pred at 2 years after onset (p = 0.0002).

CONCLUSIONS

Rapid onset of BOS, female gender, pretransplant diagnosis of idiopathic pulmonary fibrosis, and single-lung transplantation are associated with worse pulmonary function after BOS onset.

Transcript signatures of lymphocytic bronchitis in lung allograft biopsy specimens

BACKGROUND

Rejection and obliterative bronchiolitis are barriers to sustained graft function in recipients of transplanted lungs. Early detection is hindered by inadequate tests and an incomplete understanding of the molecular events preceding or accompanying graft deterioration.

METHODS

Hypothesizing that genes involved in immune responses and tissue remodeling produce biomarkers of rejection, we measured the expression of 192 selected genes in 72 sets of biopsy specimens from human lung allografts. Gene transcripts were quantified using a 2-step, multiplex, real-time polymerase chain reaction approach in endobronchial and transbronchial biopsy specimens from transplant recipients without acute infections undergoing routine surveillance bronchoscopy.

RESULTS

Comparisons of histopathology in parallel biopsy specimens identified 6 genes correlating with rejection as manifested by lymphocytic bronchitis, a suspected harbinger of obliterative bronchiolitis. For example, beta2-defensin and collagenase transcripts in inflamed bronchi increased 37-fold and 163-fold, respectively. By contrast, these transcripts did not correlate with acute rejection in transbronchial specimens. Further, no correspondence was noted between histopathologic bronchitis and parenchymal rejection when endobronchial and transbronchial samples were obtained from the same patient.

CONCLUSIONS

Our highly sensitive method permits quantitation of many gene transcripts simultaneously in small, bronchoscopically acquired biopsy specimens of allografts. Transcript signatures obtained by this approach suggest that airway and alveolar responses to rejection differ and that endobronchial biopsy specimens assess lymphocytic bronchitis and chronic rejection but are not proxies for transbronchial biopsy specimens. Further, they reveal changes in airway expression of the specific genes involved in host defense and remodeling and suggest that the measurement of transcripts correlating with lymphocytic bronchitis may be diagnostic adjuncts to histopathology.

Broncho-alveolar lavage matrix metalloproteases as a sensitive measure of bronchiolitis obliterans

Bronchiolitis obliterans (BO) is a survival-limiting factor in lung transplantation. There are no common BO markers in use. Since BO is associated with extracellular matrix remodeling, we asked whether matrix metalloproteases (MMPs) and their tissue inhibitors (TIMPs) could serve as BO markers. In 72 lung transplant patients (34 BO syndrome (BOS) 0, 15 BOS 0-p, and 23 BOS 1) serum and broncho-alveolar lavage (BAL) MMP and TIMP levels were examined by ELISA. The BAL cell counts were additionally analyzed. The serum MMP-2, MMP-8, MMP-9 and TIMP-2 levels were not different in all groups. In contrast, the BAL MMP-8, -9 and TIMP-1 levels were significantly elevated in BOS 0-p (p = 0.003; p = 0.007; p = 0.0003, respectively) and BOS 1 (p = 0.003; p = 0.001; p = 0.0004, respectively) as compared to BOS 0 patients. The BAL MMP-8, -9 and TIMP-1 levels were significant predictors of BOS 0-p (p = 0.01; p = 0.01; p = 0.01, respectively) and BOS-1 (p = 0.007; p = 0.01; p = 0.006, respectively) in receiver operating characteristic analysis. Except for BAL macrophages that were significantly decreased in BOS 0-p versus BOS 0 patients; other cell counts were not different between the groups. BAL MMP-8, -9 and TIMP-1 might be useful markers to detect BO in lung transplant patients.