Early detection of airway involvement in obliterative bronchiolitis after lung transplantation. Functional and bronchoalveolar lavage cell findings

Impulse Oscillometry Versus Spirometry to Detect Bronchiolitis Obliterans Syndrome in Bilateral Lung Transplant Recipients: A Prospective Diagnostic Study

BACKGROUND

Chronic lung allograft dysfunction (CLAD), and especially bronchiolitis obliterans syndrome (BOS), remain dominant causes of morbidity and mortality after lung transplantation. Interest is growing in the forced oscillation technique, of which impulse oscillometry (IOS) is a form, as a tool to improve our understanding of these disorders. However, data remain limited and no longitudinal studies have been published, meaning there is no information regarding any capacity IOS may have for the early detection of CLAD.

METHODS

We conducted a prospective longitudinal study enrolling a consecutive sample of adult bilateral lung transplant recipients with healthy lung allografts or CLAD and performed ongoing paired IOS and spirometry tests on a clinically determined basis. We assessed for correlations between IOS and spirometry and examined any predictive value either modality may hold for the early detection of BOS.

RESULTS

We enrolled 91 patients and conducted testing for 43 mo, collecting 558 analyzable paired IOS and spirometry tests, with a median of 9 tests per subject (interquartile range, 5-12) and a median testing interval of 92 d (interquartile range, 62-161). Statistically significant moderate-to-strong correlations were demonstrated between all IOS parameters and spirometry, except resistance at 20 Hz, which is a proximal airway measure. No predictive value for the early detection of BOS was found for IOS or spirometry.

CONCLUSIONS

This study presents the first longitudinal data from IOS after lung transplantation and adds considerably to the growing literature, showing unequivocal correlations with spirometry but failing to demonstrate a predictive value for BOS.

BET-bromodomain and EZH2 inhibitor-treated chronic GVHD mice have blunted germinal centers with distinct transcriptomes

Despite advances in the field, chronic graft-versus-host-disease (cGVHD) remains a leading cause of morbidity and mortality following allogenic hematopoietic stem cell transplant. Because treatment options remain limited, we tested efficacy of anticancer, chromatin-modifying enzyme inhibitors in a clinically relevant murine model of cGVHD with bronchiolitis obliterans (BO). We observed that the novel enhancer of zeste homolog 2 (EZH2) inhibitor JQ5 and the BET-bromodomain inhibitor JQ1 each improved pulmonary function; impaired the germinal center (GC) reaction, a prerequisite in cGVHD/BO pathogenesis; and JQ5 reduced EZH2-mediated H3K27me3 in donor T cells. Using conditional EZH2 knockout donor cells, we demonstrated that EZH2 is obligatory for the initiation of cGVHD/BO. In a sclerodermatous cGVHD model, JQ5 reduced the severity of cutaneous lesions. To determine how the 2 drugs could lead to the same physiological improvements while targeting unique epigenetic processes, we analyzed the transcriptomes of splenic GCB cells (GCBs) from transplanted mice treated with either drug. Multiple inflammatory and signaling pathways enriched in cGVHD/BO GCBs were reduced by each drug. GCBs from JQ5- but not JQ1-treated mice were enriched for proproliferative pathways also seen in GCBs from bone marrow-only transplanted mice, likely reflecting their underlying biology in the unperturbed state. In conjunction with in vivo data, these insights led us to conclude that epigenetic targeting of the GC is a viable clinical approach for the treatment of cGVHD, and that the EZH2 inhibitor JQ5 and the BET-bromodomain inhibitor JQ1 demonstrated clinical potential for EZH2i and BETi in patients with cGVHD/BO.

Mathematical modeling of peripheral blood neutrophil kinetics to predict CLAD after lung transplantation

BACKGROUND

The presence of neutrophils in the lung was identified as a factor associated with CLAD but requires invasive samples. The aim of this study was to assess the kinetics of peripheral blood neutrophils after lung transplantation as early predictor of CLAD.

METHODS

We retrospectively included all recipients transplanted in our center between 2009 and 2014. Kinetics of blood neutrophils were evaluated to predict early CLAD by mathematical modeling using unadjusted and adjusted analyses.

RESULTS

103 patients were included, 80 in the stable group and 23 in the CLAD group. Bacterial infections at 1 year were associated with CLAD occurrence. Neutrophils demonstrated a high increase postoperatively and then a progressive decrease until normal range. Recipients with CLAD had higher neutrophil counts (mixed effect coefficient beta over 3 years = +1.36 G/L, 95% Confidence Interval [0.99-1.92], p < .001). A coefficient of celerity (S for speed) was calculated to model the kinetics of return to the norm before CLAD occurrence. After adjustment, lower values of S (slower decrease of neutrophils) were associated with CLAD (Odds Ratio = 0.26, 95% Confidence Interval [0.08-0.66], p = .01).

CONCLUSION

A slower return to the normal range of blood neutrophils was early associated with CLAD occurrence.

International Society for Heart and Lung Transplantation consensus statement for the standardization of bronchoalveolar lavage in lung transplantation

Bronchoalveolar lavage (BAL) is a key clinical and research tool in lung transplantation (LTx). However, BAL collection and processing are not standardized across LTx centers. This International Society for Heart and Lung Transplantation-supported consensus document on BAL standardization aims to clarify definitions and propose common approaches to improve clinical and research practice standards. The following 9 areas are covered: (1) bronchoscopy procedure and BAL collection, (2) sample handling, (3) sample processing for microbiology, (4) cytology, (5) research, (6) microbiome, (7) sample inventory/tracking, (8) donor bronchoscopy, and (9) pediatric considerations. This consensus document aims to harmonize clinical and research practices for BAL collection and processing in LTx. The overarching goal is to enhance standardization and multicenter collaboration within the international LTx community and enable improvement and development of new BAL-based diagnostics.

Noninvasive methods for detection of chronic lung allograft dysfunction in lung transplantation

Lung transplantation (LTx) is the only therapeutic option for end-stage lung diseases. Chronic lung allograft dysfunction (CLAD), which manifests as airflow restriction and/or obstruction, is the primary factor limiting the long-term survival of patients after surgery. According to histopathological and radiographic findings, CLAD comprises two phenotypes, bronchiolitis obliterans syndrome and restrictive allograft syndrome. Half of all lung recipients will develop CLAD in 5 years, and this rate may increase up to 75% 10 years after surgery owing to the paucity in accurate and effective early detection and treatment methods. Recently, many studies have presented noninvasive methods for detecting CLAD and improving diagnosis and intervention. However, the significance of accurately detecting CLAD remains controversial. We reviewed published studies that have presented noninvasive methods for detecting CLAD to highlight the current knowledge on clinical symptoms, spirometry, imaging examinations, and other methods to detect the disease.

Lung clearance index for early detection of pulmonary complications after allo-HSCT in children

BACKGROUND

Pulmonary chronic graft-vs-host disease (cGvHD) after hematopoietic stem cell transplantation (HSCT) is characterized by impairment of the small airways. Assessment of lung clearance index (LCI) gained from multiple breath washout (MBW) is more sensitive than spirometry in detection of small airways disease. The aim of this study was to describe the development of LCI during the first year after pediatric HSCT and how LCI relates to other pulmonary function parameters and cGvHD.

METHODS

This prospective, longitudinal study included 28 pediatric HSCT-recipients. Spirometry, Sulfur hexafluoride MBW and diffusion capacity of the lungs were performed before and at 3, 6, 9, and 12 months after HSCT. Respiratory symptoms and signs of cGvHD were recorded at each visit.

RESULTS

Before HSCT, 47.8% had abnormal LCI and 12.5% had abnormal forced expiratory volume in 1 second (FEV₁ )_. Patients with persisting respiratory symptoms 12 months post-HSCT had higher median LCI (factor 5.7, P = 0.0018) and lower FEV₁ z-scores (-1.5, P = 0.033) post-HSCT compared to patients free of respiratory symptoms. Overall, post-HSCT LCI values were 3.49 times higher and FEV₁ was 2.31 z-scores lower in eight patients with cGvHD in any organ system compared with patients without cGvHD (P = 0.0089 and P < 0.0001). LCI values during the first 3 months were not predictive of pulmonary cGvHD.

CONCLUSION

LCI is a sensitive marker for cGvHD and high LCI values were associated with persisting respiratory symptoms after 1 year. Further evaluation of MBW in early detection of HSCT-related pulmonary complications require larger patient cohorts and closer follow-up during the first months after HSCT.

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.

Pre-hematopoietic stem cell transplant lung function and pulmonary complications in children

RATIONALE

Pulmonary complications are a significant cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation.

OBJECTIVES

The relationship between pretransplant pulmonary function tests (PFTs) and development of post-transplant pulmonary complications in children was studied.

METHODS

This is a retrospective single institution cohort study of 410 patients who underwent pretransplant PFT and were monitored to 10 years posttransplant.

MEASUREMENTS AND MAIN RESULTS

Pulmonary complications were observed in 174 (42%) patients. Children with pulmonary complications had significantly lower forced expiratory flow at 25-75% of vital capacity (P = 0.02) derived using conventional predicted equations for age, and the Global Lung Initiative-2012 predicted equations (P = 0.01). T-cell depletion (P = 0.001), acute grade 3-4 graft-versus-host disease (P = 0.008), and chronic graft-versus-host disease (P = 0.01) increased risk for pulmonary complications. Patients who had pulmonary complications had a 2.8-fold increased risk of mortality (P < 0.0001). The cumulative incidence of death due to pulmonary complications was significantly higher in children who had low lung volumes, FRC less than 50% (P = 0.005), TLC less than 50% (P = 0.0002), residual volume less than 50% (P = 0.007), and T-cell depletion (P = 0.01). Lower FEV1 (P = 0.0005), FVC (P = 0.0005), TLC (P  <  0.0001), residual volume less than 50% (P = 0.01), and restrictive lung disease (P = 0.01) predicted worse overall survival.

CONCLUSIONS

Abnormal pretransplant PFT significantly increased risk after transplant. These patients may benefit from modified transplant strategies to reduce morbidity and mortality.

Small airways dysfunction in long-term survivors of pediatric stem cell transplantation

BACKGROUND

Chronic graft-versus-host disease (cGvHD) in the lungs is a life-threatening complication of allogeneic hematopoietic stem cell transplantation (HSCT). Pulmonary cGvHD is initiated in the peripheral airways, and diagnosis may be delayed by low sensitivity of standard pulmonary function tests. Multiple breath nitrogen washout (MBWN2 ) is a promising, sensitive method to assess small airways function. This is the first report on MBWN2 in survivors of pediatric HSCT.

METHODS

This cross-sectional study undertaken 3-10 years post-HSCT, included 64 patients and 64 matched controls who all performed spirometry, whole-body plethysmography and MBWN2 . From MBWN2 the lung clearance index (LCI) and indices reflecting ventilation inhomogeneity arising close to the acinar lung zone (Sacin ) and in the conductive airway zone (Scond ) were derived. Subjective respiratory morbidity was assessed using the St. George Respiratory Questionnaire.

RESULTS

LCI, Sacin , and Scond were significantly higher in HSCT-patients compared with controls. Despite few reported symptoms and normal forced expiratory volume in 1 sec (FEV1 ) in 91%, LCI, Scond , and Sacin were abnormal in 34%, 52%, and 25% of HSCT-patients, respectively. LCI and Scond correlated weakly with spirometric findings in HSCT-patients, but not in controls. Scond was abnormal in 82% (9/11) of patients with evidence of cGvHD, and was associated with cGvHD in the multivariate analysis (r(2)  = 0.26, P = 0.001).

CONCLUSIONS

Small airways dysfunction as measured by MBWN2 was a common finding at long term follow-up of children after allogeneic HSCT and was associated with cGvHD. The majority of these subjects had normal spirometric values and did not report any respiratory symptoms. Prospective studies are required to evaluate the long term clinical consequences of these signs of small airway disease and the value of MBWN2 as an early marker of pulmonary cGvHD.

The Respiratory System

This chapter addresses upper airway physiology for the pediatric intensivist, focusing on functions that affect ventilation, with an emphasis on laryngeal physiology and control in breathing. Effective control of breathing ensures that the airway is protected, maintains volume homeostasis, and provides ventilation. Upper airway structures are effectors for all of these functions that affect the entire airway. Nasal functions include air conditioning and protective reflexes that can be exaggerated and involve circulatory changes. Oral cavity and pharyngeal patency enable airflow and feeding, but during sleep pharyngeal closure can result in apnea. Coordination of breathing with sucking and nutritive swallowing alters during development, while nonnutritive swallowing at all ages limits aspiration. Laryngeal functions in breathing include protection of the subglottic airway, active maintenance of its absolute volume, and control of tidal flow patterns. These are vital functions for normal lung growth in fetal life and during rapid adaptations to breathing challenges from birth through adulthood. Active central control of breathing focuses on the coordination of laryngeal and diaphragmatic activities, which adapts according to the integration of central and peripheral inputs. For the intensivist, knowledge of upper airway physiology can be applied to improve respiratory support. In a second part the mechanical properties of the respiratory system as a critical component of the chain of events that result in translation of the output of the respiratory rhythm generator to ventilation are described. A comprehensive understanding of respiratory mechanics is essential to the delivery of optimized and individualized mechanical ventilation. The basic elements of respiratory mechanics will be described and developmental changes in the airways, lungs, and chest wall that impact on measurement of respiratory mechanics with advancing postnatal age are reviewed. This will be follwowed by two sections, the first on respiratory mechanics in various neonatal pathologies and the second in pediatric pathologies. The latter can be classified in three categories. First, restrictive diseases may be of pulmonary origin, such as chronic interstitial lung diseases or acute lung injury/acute respiratory distress syndrome, which are usually associated with reduced lung compliance. Restrictive diseases may also be due to chest wall abnormalities such as obesity or scoliosis (idiopathic or secondary to neuromuscular diseases), which are associated with a reduction in chest wall compliance. Second, obstructive diseases are represented by asthma and wheezing disorders, cystic fibrosis, long term sequelae of neonatal lung disease and bronchiolitis obliterans following hematopoietic stem cell transplantation. Obstructive diseases are defined by a reduced FEV1/VC ratio. Third, neuromuscular diseases, mainly represented by DMD and SMA, are associated with a decrease in vital capacity linked to respiratory muscle weakness that is better detected by PImax, PEmax and SNIP measurements.

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.

NHANES III equations enhance early detection and mortality prediction of bronchiolitis obliterans syndrome after hematopoietic SCT

Bronchiolitis obliterans syndrome (BOS) is a serious complication of chronic GVHD (cGVHD) following HSCT (hematopoietic SCT). The clinical diagnosis of BOS is based on pulmonary function test (PFT) abnormalities including: FEV1<75% predicted and obstructive FEV1/VC ratio, calculated using reference equations. We sought to determine if the frequency of clinical diagnoses and severity of BOS would be altered by using the recommended NHANES III vs older equations (Morris/Goldman/Bates, MGB) in 166 cGVHD patients, median age 48 (range: 12-67). We found that NHANES III equations significantly increased the prevalence of BOS, with an additional 11% (18/166) meeting diagnostic criteria by revealing low FEV1 (<75%) (P<0.0001), and six additional patients by obstructive ratio (vs MBG). Collectively, this led to an increase of BOS incidence from 17 (29/166) to 29% (41/166). For patients with severe BOS, (FEV1<35%), NHANES III equations correctly predicted death 71.4% vs 50% using MGB. In conclusion, the use of NHANES III equations markedly increases the proportion of cases meeting diagnostic criteria for BOS and improves prediction of survival.

A new classification system for chronic lung allograft dysfunction

Although survival after lung transplantation has improved significantly during the last decade, chronic rejection is thought to be the major cause of late mortality. The physiologic hallmark of chronic rejection has been a persistent fall in forced expiratory volume in 1 second associated with an obstructive ventilatory defect, for which the term bronchiolitis obliterans syndrome (BOS) was defined to allow a uniformity of description and grading of severity throughout the world. Although BOS was generally thought to be irreversible, recent evidence suggests that some patients with BOS may respond to azithromycin with > 10% improvement in their forced expiratory volume in 1 second. In addition, a restrictive form of chronic rejection has recently been described that does not fit the strict definition of BOS as an obstructive defect. Hence, the term chronic lung allograft dysfunction (CLAD) has been introduced to cover all forms of graft dysfunction, but CLAD has yet to be defined. We propose a definition of CLAD and a flow chart that may facilitate recognition of the different phenotypes of CLAD that can complicate the clinical course of lung transplant recipients.

Bronchoalveolar lavage as a tool to predict, diagnose and understand bronchiolitis obliterans syndrome

Bronchiolitis obliterans syndrome (BOS), a condition of irreversible small airway fibrosis, is the principal factor limiting long-term survival after lung transplantation. Bronchoscopy and bronchoalveolar lavage (BAL), techniques central to lung transplant clinical practice, provide a unique opportunity to interrogate the lung allograft during BOS development and identify potential disease mechanisms or biomarkers. Over the past 20 years, numerous studies have evaluated the BAL cellular composition, cytokine profiles and protein constituents in lung transplant recipients with BOS. To date, however, no summative evaluation of this literature has been reported. We developed and applied objective criteria to qualitatively rank the strength of associations between BAL parameters and BOS in order to provide a comprehensive and systematic assessment of the literature. Our analysis indicates that several BAL parameters, including neutrophil count, interleukin-8, alpha defensins and MMP-9, demonstrate highly replicable associations with BOS. Additionally, we suggest that considerable opportunity exists to increase the knowledge gained from BAL analyses in BOS through increased sample sizes, covariant adjustment and standardization of the BAL technique. Further efforts to leverage analysis of BAL constituents in BOS may offer great potential to provide additional in-depth and mechanistic insights into the pathogenesis of this complex disease.

Decline in 25% to 75% forced expiratory flow as an early predictor of chronic airway rejection in pediatric lung transplant recipients

BACKGROUND

Bronchiolitis obliterans (BO) is the major obstacle to long-term lung allograft viability. Its clinical correlate, BO syndrome (BOS), is defined as a decline of at least 20% in forced expiratory volume in 1 second (FEV(1)) from baseline. BOS is often diagnosed after significant organ dysfunction has occurred. Because BO is a small-airways disease, we hypothesized that a 20% decline in the 25% to 75% forced expiratory flow (FEF(25-75)) from baseline should occur before a decline in FEV(1) and should predict progression to BOS with high sensitivity and specificity.

METHODS

Pulmonary function tests and records of pediatric lung transplantation patients at Texas Children's Hospital from 2002 to 2007 were reviewed. Declines in FEV(1) and FEF(25-75) from the best post-transplant baseline values were recorded and analyzed. Sensitivity, specificity, and positive and negative predictive values were calculated.

RESULTS

Thirty-one patients were eligible for the study. In 11 BOS patients, the mean±standard deviation number of days from transplant until a 20% decline in FEV(1) was 896.5±400 compared with 728.0±475 (p = 0.022) until a 20% decline in FEF(25-75) was reached. The sensitivity, specificity, and positive predictive and negative predictive values of a 20% reduction in FEF(25-75) in determining BOS were 100%, 90.0%, 84.6%, and 100%, respectively.

CONCLUSIONS

All patients who developed BOS had a decline in FEF(25-75) at or before the decline in FEV(1). The reduction in FEF(25-75) occurred statistically significantly earlier than the decline in FEV(1), by an average of 168.5 days. This decline in FEF(25-75) was also highly sensitive and specific for the diagnosis of BOS.

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.

Prediction of BOS by the single-breath nitrogen test in double lung transplant recipients

BACKGROUND

The present study analyses the ability of the alveolar slope of the single-breath nitrogen washout test (N2-slope) to diagnose and predict the development of the bronchiolitis obliterans syndrome (BOS).

METHODS

We present a retrospective analysis of 61 consecutive bilateral lung or heart-lung transplant recipients who were followed at regular control visits during a three year follow-up. The operating characteristics of the N2-slope to diagnose BOS and potential BOS (BOS 0-p) and to predict BOS were determined based on cut off values of 95% specificity.

RESULTS

The sensitivity of the N2-slope to identify BOS was 96%, and BOS 0-p 100%. The predictive ability to predict BOS with a N2-slope > 478% of the predicted normal was 56%, and if combined with a coincident FEV1 < 90% of the basal value, the predictive ability was 75%.

CONCLUSIONS

The predictive ability of either the N2-slope or of FEV1 to diagnose BOS is limited but the combination of the two appears useful. Follow-up protocols of bilateral lung and heart-lung transplant recipients should consider including tests sensitive to obstruction of the peripheral airways.

Lung transplantation and lung volume reduction surgery

Since the publication of the last edition of the Handbook of Physiology, lung transplantation has become widely available, via specialized centers, for a variety of end-stage lung diseases. Lung volume reduction surgery, a procedure for emphysema first conceptualized in the 1950s, electrified the pulmonary medicine community when it was rediscovered in the 1990s. In parallel with their technical and clinical refinement, extensive investigation has explored the unique physiology of these procedures. In the case of lung transplantation, relevant issues include the discrepant mechanical function of the donor lungs and recipient thorax, the effects of surgical denervation, acute and chronic rejection, respiratory, chest wall, and limb muscle function, and response to exercise. For lung volume reduction surgery, there have been new insights into the counterintuitive observation that lung function in severe emphysema can be improved by resecting the most diseased portions of the lungs. For both procedures, insights from physiology have fed back to clinicians to refine patient selection and to scientists to design clinical trials. This section will first provide an overview of the clinical aspects of these procedures, including patient selection, surgical techniques, complications, and outcomes. It then reviews the extensive data on lung and muscle function following transplantation and its complications. Finally, it reviews the insights from the last 15 years on the mechanisms whereby removal of lung from an emphysema patient can improve the function of the lung left behind.

[Long-term outcome of lung transplantation]

Lung transplantation (LTx) nowadays is an established therapeutic option for various end-stage lung diseases in despite of an optimal medical therapy in selected patients affected with various pathologies such as emphysema/chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF) and various forms of bronchiectasis, pulmonary fibrosis and pulmonary hypertension. Progress and refinement over the last two decades in both surgical techniques and medical management including especially the introduction of cyclosporine A, have been impressive. Patient survival improved significantly over time. According to the most recent data of the International Registry of Lung Transplantation (ISHLT), actuarial survival is 79%, 63%, 52% and 29% at 1, 3, 5 and 10 years respectively, with a current overall survival half-life of 5.3 years, and more than 7 years for those who survived 1 year or more. However, survival depends on different parameters such as the underlying disease, data relative to the donor, the recipient and/or the transplant procedure. Major limitation of long-term survival is still chronic allograft dysfunction, which is histologically represented by an obliterative bronchiolitis and functionally by the bronchiolitis obliterans syndrome (BOS). In uncomplicated cases near-normalization of pulmonary function is the rule, with more than 80% of survivors at 1, 3, 5 and 10 years reporting no activity limitations. Functional results after single LTx remain lower than those of the bilateral LTx, and depend on the potential worsening of the underlying disease and complications arising on the native lung. Exercise performance usually is approximately 50% of predicted, suggesting extrapulmonary causes such as side effects of immunosuppressive drugs. Quality of life improves significantly in all domains including employment status.

Bronchiolitis obliterans after allogeneic hematopoietic stem cell transplantation

With improvements in supportive care, both long-term survival following allogeneic hematopoietic stem cell transplantations (HSCTs) and the indications for this procedure have increased. As a result, the number of patients living with long-term toxic effects due to HSCT has increased. A once rare condition of the donor immune cells attacking healthy host tissues, termed chronic graft-vs-host disease, has become a more common phenomenon. When chronic graft-vs-host disease affects the lung tissue, bronchiolitis obliterans syndrome ensues. Recent data suggest that bronchiolitis obliterans syndrome may affect up to 6% of HSCT recipients and dramatically alters survival, with overall survival of only 13% at 5 years. These statistics have not improved since the first presentation of this disease over 20 years ago. Challenges to the progress of medical management of bronchiolitis obliterans syndrome include difficulties and delays in diagnosis and a paucity of data on pathogenesis to direct new therapies. This article critically evaluates the current diagnostic criteria for bronchiolitis obliterans syndrome and reviews the epidemiology, pathogenesis, and available treatments. Improvements in survival will likely require early disease recognition, allowing for therapeutic modulation of disease prior to the development of irreversible airway obliteration.

Bronchiolitis obliterans syndrome (BOS), bronchiolitis obliterans organizing pneumonia (BOOP), and other late-onset noninfectious pulmonary complications following allogeneic hematopoietic stem cell transplantation

Pulmonary dysfunction is a significant complication following allogeneic hematopoietic stem cell transplantation (HSCT), and is associated with significant morbidity and mortality. Effective antimicrobial prophylaxis and treatment strategies have increased the incidence of noninfectious lung injury, which can occur in the early posttransplant period or in the months and years that follow. Late-onset noninfectious pulmonary complications are frequently encountered, but diagnostic criteria and terminology for these disorders can be confusing and therapeutic approaches are suboptimal. As a consequence, inaccurate diagnosis of these conditions may hamper the appropriate data collection, enrollment into clinical trials, and appropriate patient care. The purpose of this review is to clarify the pathogenesis and diagnostic criteria of representative conditions, such as bronchiolitis obliterans syndrome and bronchiolitis obliterans organizing pneumonia, and to discuss the appropriate diagnostic strategies and treatment options.

Single-breath test in lateral decubitus reflects function of single lungs grafted for interstitial lung disease

After single-lung transplantation (SLT) for emphysema, heterogeneity of ventilation distribution in the graft can be assessed by measuring the slope of the alveolar plateau, computed from a single-breath test, performed in lateral decubitus with this lung in the nondependent position. We tested the validity of this technique in patients with SLT for interstitial lung diseases (ILD). Twelve patients with SLT for ILD, 12 nontransplanted patients with ILD, and 10 healthy control subjects performed single-breath washouts in right and left lateral decubitus; nitrogen slope (S(N(2))) and the difference between SF(6) and He slopes (S(SF(6))-S(He)) were measured between 75 and 100% of expired volume. In 10 transplant recipients, the volume of each lung was measured in both postures by computerized tomography. Slopes were unaffected by posture in normal control subjects and patients with ILD. On the other hand, S(N(2)) and S(SF(6))-S(He) in transplant recipients were smaller with the graft in the nondependent than in the dependent position (0.366 +/- 0.445 vs. 1.035 +/- 0.498 for S(N(2)); 0.094 +/- 0.201 vs. 0.218 +/- 0.277 for S(SF(6))-S(He)). Values of S(N(2)) and S(SF(6))-S(He) obtained in the former position were similar to those obtained in normal controls, while values obtained in the latter position were similar to those obtained in nontransplanted patients with ILD. Computerized tomography studies with the graft in the nondependent position indicated that this lung contributed 82% of the volume expired below functional residual capacity. We conclude that, in patients with SLT for ILD, the slope of the alveolar plateau obtained with the graft in the nondependent position reflects heterogeneity of ventilation distribution in this lung.

A new murine model for bronchiolitis obliterans post-bone marrow transplant

RATIONALE

Bronchiolitis obliterans (BO) is a major problem in lung transplantation and is also part of the spectrum of late-onset pulmonary complications that can occur after hematopoietic stem cell transplant. Better mouse models are needed to study the onset of this disease so that therapeutic interventions can be developed.

OBJECTIVES

Our goal was to develop a BO mouse model.

METHODS

Recipients were lethally conditioned and given a rescue dose of T-cell-depleted, allogeneic bone marrow (BM) supplemented with a sublethal dose of allogeneic T cells.

MEASUREMENTS AND MAIN RESULTS

At 2 months post-BM transplant, the lungs had extensive perivascular and peribronchiolar inflammation consisting of CD4(+) T cells, CD8(+) T cells, B cells, macrophages, neutrophils, and fibroblasts. In contrast to the acute model, histology showed airway obstruction consistent with BO. Epithelial cells of airways in the early stages of occlusion exhibited changes in expression of cytokeratins. Although the lung had severe allogeneic BM transplant-mediated disease, there was only mild to moderate graft-versus-host disease in liver, colon, skin, and spleen. High wet/dry weight ratios and elevated hydroxyproline were seen, consistent with pulmonary edema and fibrosis. Mice with BO exhibited high airway resistance and low compliance. Increases in many inflammatory mediators in the lungs of mice that develop BO were seen early post-transplant and not later at the time of BO.

CONCLUSIONS

This new mouse model will be useful for the study of BO associated with late post-hematopoietic stem cell transplant onset and chronic graft-versus-host disease, which also leads to poor outcome in the lung transplant setting.

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.

Posttransplant monitoring of pediatric lung transplant recipients

PURPOSE OF REVIEW

This article reviews current trends in pediatric lung posttransplant management, reveals pitfalls that exist, and introduces additional parameters that may have an impact on long-term survival.

RECENT FINDINGS

A number of parameters are monitored after transplantation to prevent or identify early complications related to lung transplantation in hope of reducing morbidity and mortality. These include routine laboratory studies, imaging, and monitoring of drug levels and lung function. Drug monitoring allows individualization of a patient's immunosuppressive therapy; however, drug levels alone may not reflect the patient's immune status. ImmuKnow is a general immune-monitoring assay that may help guide therapy. Two major complications are rejection and infection, and bronchoscopy is used to differentiate these two entities. Silent rejection may occur and increase the chance of developing bronchiolitis obliterans; therefore, many centers perform surveillance bronchoscopies. Recently, de-novo anti-histocompatibility locus antigen antibodies and gastroesophageal reflux have been associated with poor outcomes, and many centers are monitoring these entities as part of care following lung transplant.

SUMMARY

There has been little improvement in long-term outcomes of lung transplantation. Current monitoring methods are utilized to maintain or improve outcomes and recently additional monitoring parameters have been identified which hopefully will improve long-term outcomes.

Mucoviscidose : du bon usage des explorations fonctionnelles respiratoires

INTRODUCTION

Neonatal screening for cystic fibrosis (CF) leads to early dedicated specialist care for all patients.

BACKGROUND

Pulmonary function tests (PFT) are mandatory for routine monitoring of CF patients. The aim of this article is to review the current guidelines for PFTs in CF, particularly the type of test, the age and the clinical status of the patient.

VIEWPOINT

The regular use of spirometry is generally accepted. Many other tests are used but their clinical value in the routine follow-up of CF patients remains to be established.

CONCLUSION

Further efforts should be made to evaluate the value of PFTs in CF, particularly in very young children.

Early detection of chronic pulmonary allograft dysfunction by exhaled biomarkers

RATIONALE

Early detection of bronchiolitis obliterans syndrome (BOS) is important because therapies are more likely to be effective if employed early in the disease process.

OBJECTIVES

To compare the performance of exhaled NO and CO (which reflect airway inflammation) and the slope of the alveolar plateau for helium (which reflects heterogeneity of ventilation distribution) for detection of BOS stages 0-p and 1.

METHODS

Recipients of bilateral (n=64) and single (n=1) lung grafts were prospectively monitored for 1,249 days; the helium slope was derived from single-breath washouts and exhaled NO and CO were measured by chemiluminescence on 933 occasions.

MEASUREMENTS AND MAIN RESULTS

At the end of follow-up, 9 patients were in stage 0-p and 16 patients were in BOS stage 1 or higher; 21 patients had at least one measurement made in BOS stage 0-p. All markers increased in BOS stage 0-p, but only the helium slope increased in BOS stage 1. The helium slope had better sensitivity for detection of stages 0-p and 1 than either exhaled NO or CO, but considering exhaled NO and CO together improved their sensitivity; the best sensitivity was found with the three markers in combination. The biomarkers had high negative predictive values, but low specificity and positive predictive values.

CONCLUSIONS

After lung transplantation, (1) the helium slope and exhaled NO, but also exhaled CO, increase in BOS stage 0-p, (2) the helium slope has better sensitivity than exhaled NO and CO for the detection of BOS stages 0-p and 1, and (3) exhaled biomarkers have high negative predictive values, but low specificity and positive predictive values.

Bronchiolitis obliterans following lung transplantation

Bronchiolitis obliterans syndrome (BOS) is the main and late chronic complication after lung transplantation. It remains a major impediment to long-term outcome. Unfortunately, the survival rate of lung transplant recipients lags behind that of other organ transplant recipients, and BOS accounts for more than 30% of all mortality after the third year following lung transplantation. Most recent studies suggest that immune injury is the main pathogenic event in small airway obliteration and the development of BOS. Early detection of BOS is possible as well as essential because prompt initiation of treatment may halt the progress of the disease and the development of chronic graft failure. Current treatment of BOS is disappointing despite advances in surgical techniques and improvements in immunosuppressive therapies. Therefore, a clear understanding of the pathogenesis of BOS plays a major role in the search for new and effective therapeutic strategies for better long-term survival and quality of life after lung transplantation.

Analysis of chronic lung transplant rejection by MALDI-TOF profiles of bronchoalveolar lavage fluid

While lung transplant is an effective therapy for advanced lung disease, chronic allograph rejection remains a primary basis for lower survival rates than those for other solid organ transplants. This study used carefully controlled Zip-Tip extraction of bronchoalveolar lavage fluid (BALF) followed by MALDI-TOF MS to identify biomarkers of chronic lung transplant rejection. Many differences were observed between controls, those who did not develop chronic rejection within 100 months, and patients who had developed chronic rejection, diagnosed as bronchiolitis obliterans syndrome (BOS). Intensity ratios of peaks within the same MALDI-TOF profile were used to quantify the result. One of the best identifiers of BOS was a lowered ratio of clara cell protein (CCP m/z = 15,835) to lysozyme (m/z = 14,700), which gave 94% specificity and 74% sensitivity for diagnosis. Furthermore, low values for CCP/Lysozyme (<0.3) were observed in 66% of samples taken at 1 to 15 months prior to the diagnosis of BOS. Many other components of the profile gave similar or better outcomes for diagnosis but tended to be less valuable for the prediction of future disease. Overall, this study demonstrated the feasibility of this approach for the detection of disease biomarkers.

The dynamics and associations of airway neutrophilia post lung transplantation

Bronchoalveolar lavage (BAL) neutrophilia has been repeatedly observed in lung transplant recipients with established bronchiolitis obliterans syndrome (BOS). Little is known of the fluctuations in BAL and airway neutrophilic inflammation post-transplant. This prospective longitudinal study aimed to evaluate the dynamic changes of lung allograft neutrophils with time, immunosuppression, infection and BOS. A total of 28, initially healthy, BOS 0, lung transplant recipients underwent 134 bronchoscopic assessments, including BAL and endobronchial biopsies (EBB) (with immunohistochemistry) over 3-year follow up. Subsequently, 21 developed BOS 0p and 16 ultimately BOS. Compared to controls, there was early and persistent BAL neutrophilia (p < 0.05), contrasting with an initially normal EBB that shows a progressive increased airway wall neutrophil infiltrate. BAL neutrophilia (but not airway wall neutrophilia) was most striking when there was concomitant bronchopulmonary infection, particularly in the patients with BOS. Univariate and multivariate analyses suggested that BAL neutrophilia was linked to markers of infection while EBB neutrophilia was linked with coexistent inflammation with macrophages and lymphocytes.

IN CONCLUSION

(i) BAL neutrophilia is predominantly associated with infection; (ii) Airway wall neutrophilia (as monitored by EBB) increases with time post-transplant and is not associated with infection; (iii) By itself, BOS is not the major contributor to BAL and EBB neutrophilia.

Single-breath test in lateral decubitus reflects function of single lungs grafted for emphysema

The slope of alveolar plateau for nitrogen derived from the single-breath test is useful to assess the function of bilateral lung grafts, but this technique is not applicable to patients with single-lung grafts due to the confounding influence of the native lung. We tested the hypothesis that the nitrogen slope measured in lateral decubitus with the graft in nondependent position may primarily reflect the distribution of ventilation in this lung. Fifteen patients with single-lung transplantation for emphysema, 10 healthy controls, and 7 patients with advanced emphysema performed single-breath washouts in right and left lateral decubitus; nitrogen slope was measured between 75 and 100% of expired volume. In 10 transplant recipients, the volume of each lung was measured in the two postures by computerized tomography. Nitrogen slope was unaffected by posture in normal controls and emphysema patients. On the other hand, nitrogen slope in transplant recipients was invariably smaller, with the graft in nondependent vs. in dependent position. Values of nitrogen slope with the graft in nondependent position were similar to those obtained in normal controls but significantly smaller than those obtained in emphysema patients. Computerized tomography studies in this position indicated that the volume expired below functional residual capacity was exclusively contributed by the graft. We conclude that, in patients with single-lung transplantation for emphysema, 1) measuring nitrogen slope in lateral decubitus allows to distinguish between the graft and the native lung, and 2) nitrogen slope obtained with the graft in nondependent position reflects ventilation distribution in this lung.

Allograft Rejection After Lung Transplantation

Lung transplantation has become an accepted therapy for selected patients with advanced lung disease. One of the main limitations to successful lung transplantation is rejection of the transplanted organ. This article discusses the clinical presentation, treatment, and prevention of hyperacute, acute, and chronic rejection in the lung transplant recipient.

Acute lung injury after allogeneic stem cell transplantation: from the clinic, to the bench and back again

Allogeneic hematopoietic stem cell transplantation (SCT) is the only curative therapeutic option for a number of malignant and non-malignant conditions, but the success of this treatment strategy is limited by several side effects. Diffuse lung injury is a major complication of SCT that responds poorly to standard treatment and significantly contributes to transplant related morbidity and mortality. Lung injury occurs in both acute and chronic forms and can be either infectious or non-infectious in nature. Acute, non-infectious lung injury following SCT has been defined as idiopathic pneumonia syndrome (IPS). This review will outline the clinical spectrum, risk factors, and pathogeneses of IPS and discuss how current approaches to therapy are being influenced by insights generated using animal models of disease.

Monitoring the lung periphery of transplanted lungs

Lung transplantation is now accepted as a viable therapeutic option for patients with end-stage lung diseases, but long-term survival is threatened by bronchiolitis obliterans (BO), which is regarded as a manifestation of chronic allograft rejection. We have used studies of ventilation distribution for the early detection of this complication. In a prospective study of 57 bilateral-lung transplant recipients, we showed that the slope of phase III of the helium single-breath washout, which targets inhomogeneities of ventilation distribution in the terminal and respiratory bronchioles, was particularly sensitive to the development of BO. In a preliminary study using nitrogen multiple-breath washouts, we showed that S(acin) and S(cond), which reflect structural changes in the acinar and conductive lung zones, were both markedly increased in patients with BO. Taken together, these studies demonstrate that monitoring the function of the allograft by measuring the distribution of ventilation in the lung periphery may be a clinically valuable tool.

Incomplete Event Documentation in Medical Records of Lung Transplant Recipients

Context

The medical record is frequently used in clinical studies as a source of information on illness events experienced by patients; however, it may be incomplete.

Objective

To estimate the extent of incompletely documented acute bronchopulmonary events in a transplant clinic medical record at a single university medical center, using home monitoring data.

Design, Setting, and Subjects

Trends in daily home monitoring data were compared to contemporaneous medical record documentation at 150 different times in 30 lung transplant recipients over 45 subject-years.

Outcome Measure

Proportion of acute bronchopulmonary illness events documented in clinic medical record.

Results

By using home monitoring data in a new way, we found that 40% of events actually suffered by lung recipients could not be ascertained to have occurred from the clinic medical record alone. All missed encounters occurred away from the transplant clinic, and involved hospitalizations and telephone prescriptions.

Conclusions

Using the clinic medical record alone to identify acute bronchopulmonary events in lung transplant recipients may result in missing 40% of events. This has important ramifications for studies relying on the medical record for acute event ascertainment in lung transplantation and possibly other chronic diseases.

Prognostic value of bronchiolitis obliterans syndrome stage 0-p in single-lung transplant recipients

RATIONALE

Early diagnosis of bronchiolitis obliterans syndrome (BOS) is critical in understanding pathogenesis and devising therapeutic trials. Although potential-BOS stage (BOS 0-p), encompassing early changes in FEV(1) and forced expiratory flow, midexpiratory phase (FEF(25-75%)), has been proposed, there is a paucity of data validating its utility in single-lung transplantation.

OBJECTIVE

The aim of this study was to define the predictive ability of BOS 0-p in single-lung transplantation.

METHODS

We retrospectively analyzed spirometric data for 197 single-lung recipients. Sensitivity, specificity, and positive predictive value of BOS 0-p were examined over time using Kaplan-Meier methodology.

RESULTS

BOS 0-p FEV(1) was associated with higher sensitivity, specificity, and positive predictive value than the FEF(25-75%) criterion over different time periods investigated. The probability of testing positive for BOS 0-p FEV(1) in patients with BOS (sensitivity) was 71% at 2 years before the onset of BOS. The probability of being free from development of BOS 0-p FEV(1) in patients free of BOS at follow-up (specificity) was 93% within the last year. Of patients who met the BOS 0-p FEV(1) criterion, 81% developed BOS or died within 3 years. The specificity and positive predictive value curves for the BOS 0-p FEV(1) were significantly different between patients with underlying restrictive versus obstructive physiology (p = 0.05 and 0.01, respectively).

CONCLUSION

The FEV(1) criterion for BOS 0-p provides useful predictive information regarding the risk of development of BOS or death in single-lung recipients. The predictive value of this criterion is higher in patients with underlying restriction and is superior to the FEF(25-75%) criterion.

Detection of chronic rejection by quantitative ventilation scintigrams in lung-transplanted patients: a pilot study

The suspicion of chronic rejection [bronchiolithis obliterans syndrome (BOS)] is usually based on deteriorating forced expired volume in 1 s. It is however, desirable to develop more sensitive methods as increased anti-inflammatory therapy is thought to stop progression of the rejection. The aim of the present study was to develop quantitative tools based on ventilation scintigrams, to diagnose BOS. Sixteen double-lung-transplanted patients participated, six developing BOS and 10 who did not develop BOS. They were investigated with planar posterior-anterior (99m)Tc-Technegas (Tetley Manufacturing Ltd, Sydney, Australia) ventilation scintigraphy at baseline, 6 months to 1 year post-transplantation, and at a follow-up examination 3-4-year post-transplant or in the BOS patients close to the time of the diagnosis. An automatic region of interest (ROI) was drawn on each lung in the scintigraphic image at baseline and also applied to the follow-up investigation. The area inside the ROI was subdivided into stripes 10.8 mm high and squares 10.8 x 10.8 mm wide. Corresponding stripes and squares in baseline and follow-up were analysed regarding differences in relative retention. The results show that the square analysis is superior. Applying chosen cut-off values for square element differences, 6/6 right and 5/6 left BOS lungs were identified and one left and one right lung of patients not developing BOS were misclassified. We conclude that the square element difference appears to be a promising method to diagnose BOS.

Bronchiolitis obliterans in children

Bronchiolitis obliterans (BO) in children is a relatively rare diagnosis. The increase in lung and bone marrow transplantation in children, however, has led to a heightened interest in BO, as this is one of the important complications of those procedures. This article will discuss BO as an entity that can follow any of several illnesses or toxic exposures, in addition to following allogeneic lung or bone marrow transplantation. The complex and incompletely understood pathology, pathogenesis, and molecular pathology involved in BO remain the subject of ongoing investigations. As the prognosis for BO is uncertain and treatment is often unsuccessful, the continued need for the recognition of surrogate markers for BO in patients at risk and the development of better forms of therapy are paramount. This review will describe our current understanding of BO, and will call attention to those research areas that require continuing efforts in order to prevent or treat this entity.

Changes in induced sputum in the presence of bronchiolitis obliterans syndrome and correlation with spirometry in single and bilateral lung transplant recipients

Bronchiolitis obliterans syndrome is a clinical diagnosis based on lung function parameters. Using induced sputum, taken from lung transplant recipients, this paper reports on the correlation between the neutrophil count and the percentage change from postoperative baseline for FEV(1), FEF(50), and FEF(25-75). In double lung transplant recipients the correlations were significant for FEV(1) (r = -0.68, p = 0.002), FEF(50) (r = -0.65, p = 0.016), and FEF(25-75) (r = -0.56, p = 0.016). In single lung transplant recipients, no significant correlations were seen.

Accuracy of exhaled nitric oxide measurements for the diagnosis of bronchiolitis obliterans syndrome after lung transplantation

BACKGROUND

Exhaled nitric oxide (eNO) is increased in patients with bronchiolitis obliterans syndrome (BOS) after lung transplantation. However, the accuracy of eNO measurements in diagnosing BOS is unknown.

METHODS

Thirty-two lung-transplant patients were included. Their immunosuppressive regimen consisted of cyclosporin A (tacrolimus), azathioprine (mycophenolate mofetil), and oral but no inhaled steroids. eNO levels and spirometry were prospectively followed until 2 years after transplantation or until the patient developed BOS.

RESULTS

Thirteen patients (group A) developed BOS (607 +/- 158 days after transplantation). Their mean eNO level at that time was 24.3 +/- 13.2 parts per billion (ppb), whereas the eNO value in the stable patients at 2 years (group B) was 11.4 +/- 4.9 ppb, P=0.0054. All group A patients had an eNO of 15 or greater ppb. Seven patients of group B also had an eNO of 15 or greater ppb, resulting in a test accuracy for the diagnosis of BOS of 0.78. However, considering only those patients who had two consecutive measurements (3-6 weeks apart) of eNO 15 or greater ppb during the months preceding the diagnosis of BOS or in the whole 2-year evaluation period, only 3 of 19 patients in group B (false-positives) but 12 of 13 in group A (1 false-negative) now fulfilled that criteria, which became positive at a mean of 263 +/- 169 days before the diagnosis of BOS was met, based on the forced expiratory volume in 1 second criteria. This increased the accuracy to 0.88.

CONCLUSION

Measurements of eNO appear to be an accurate test for the early diagnosis of BOS.

Bronchiolitis obliterans syndrome: Pathogenesis and management

Over the past 15 years, lung transplantation has become an established treatment for a variety of end-stage lung diseases, but medium- and long-term success has been limited by a high incidence of bronchiolitis obliterans syndrome (BOS). Immune mediated injury has been recognized as the leading cause of BOS, and the term is synonymous with chronic rejection. But recently, nonimmune mechanisms, such as gastroesophageal reflux, have been recognized as potential culprits. The results of various treatment options have generally been disappointing, and BOS has emerged as the leading cause of late morbidity and mortality after lung transplantation.

Bronchiolitis obliterans

Bronchiolitis obliterans (BO) is a disease of small airways that results in progressive dyspnea and airflow limitation. It is a common sequela of bone marrow, lung, and heart-lung transplantation, but can also occur as a complication of certain pulmonary infections, adverse drug reaction, toxic inhalation, and autoimmune disorders. Non-transplant-related BO is rare and can mimic asthma and chronic obstructive pulmonary disease (COPD). In transplant-related BO, the diagnosis can be suggested by obstructive changes in serial pulmonary function testings, while open lung biopsy is usually required in non-transplant cases. High-resolution computerized tomography (HRCT) is also a helpful tool to diagnose and assess the severity of BO. The treatment of BO, regarding of the cause, is usually disappointing. Systemic corticosteroid immunosuppression and retransplantation have been described with variable success.

Bronchoalveolar lavage cytokine profile in a cohort of lung transplant recipients: A predictive role of interleukin-12 with respect to onset of bronchiolitis obliterans syndrome

BACKGROUND

Bronchiolitis obliterans syndrome is the main long-term complication of lung transplantation that limits survival of lung transplant patients. Its pathophysiologic mechanisms are still poorly understood but it seems to result from a chronic immunologic/inflammatory insult leading to excessive fibroproliferation. The aim of this longitudinal study of 44 lung recipients was to determine whether a number of bronchoalveolar lavage and clinical variables are associated with a higher risk of developing bronchiolitis obliterans syndrome.

METHODS

Bronchoalveolar lavage studies involved assessment of several cytokines including: interleukin-8, monocyte chemoattractant protein-1, regulated-upon-activation normal T cell expressed and secreted (RANTES), gamma-interferon, interleukin-12, interleukin-10 and transforming growth factor-beta.

RESULTS

The predictivity of bronchoalveolar lavage (BAL) features with respect to onset of bronchiolitis obliterans syndrome was assessed by the Cox regression model. Among clinical variables, bacterial and viral infections were found to significantly predict occurrence of bronchiolitis obliterans syndrome (hazard ratio [HR] for bacterial infection: 13.044, 95% confidence interval [CI] 1.34 to 126.69, p = 0.027; HR for viral infections: 4.88, 95% CI 1.004 to 22.87, p = 0.05). Among BAL variables, only IL-12 was significantly predictive of bronchiolitis obliterans syndrome (HR 0.956, 95% CI 0.901 to 1.01, p = 0.03). In addition, in a sub-group cross-sectional analysis, bronchiolitis obliterans syndrome patients were compared with clinically stable patients, and significant increases in median levels of interleukin-8 and monocyte chemoattractant protein-1 BAL fluid were detected.

CONCLUSIONS

These findings support the contention that interleukin-12 plays a role in the modulation of the local pro-/anti-fibrotic balance of allograft airways.