Time-related changes in pulmonary function after conversion to tacrolimus in bronchiolitis obliterans syndrome

Management of chronic rejection after lung transplantation

Outcomes after lung transplantation are limited by chronic lung allograft dysfunction (CLAD). The incidence of CLAD is high, and its clinical course tends to be progressive over time, culminating in graft failure and death. Indeed, CLAD is the leading cause of death beyond the first year after lung transplantation. Therapy for CLAD has been limited by a lack of high-quality studies to guide management. In this review, we will discuss the diagnosis of CLAD in light of the recent changes to definitions and will discuss the current clinical evidence available for treatment. Recently, the diagnosis of CLAD has been subdivided into bronchiolitis obliterans syndrome (BOS) and restrictive allograft syndrome (RAS). The current evidence for treatment of CLAD mainly revolves around treatment of BOS with more limited data existing for RAS. The best supported treatment to date for CLAD is the macrolide antibiotic azithromycin which has been associated with a small improvement in lung function in a minority of patients. Other therapies that have more limited data include switching immunosuppression from cyclosporine to tacrolimus, fundoplication for gastroesophageal reflux, montelukast, extracorporeal photopheresis (ECP), aerosolized cyclosporine, cytolytic anti-lymphocyte therapies, total lymphoid irradiation (TLI) and the antifibrotic agent pirfenidone. Most of these treatments are supported by case series and observational studies. Finally, we will discuss the role of retransplantation for 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.

An update on current treatment strategies for managing bronchiolitis obliterans syndrome after lung transplantation

INTRODUCTION

Bronchiolitis obliterans syndrome (BOS), a subtype of chronic lung allograft dysfunction, is quite common, with up to half of all lung recipients developing BOS within 5 years of transplantation. Preventive efforts are aimed at alleviating known risk factors of BOS development, while the primary goal of treatment is to delay the irreversible, fibrotic airway changes, and progressive loss of lung function.

AREAS COVERED

This narrative review will briefly discuss the updated definition, clinical presentation, pathogenesis, risk factors, and survival after BOS while paying particular attention to the salient evidence for optimal preventive strategies and treatments based on investigations in the modern era.

EXPERT OPINION

Future translational research focused on further characterizing the complex interplay between immune and nonimmune mechanisms mediating chronic lung rejection is the first step toward mitigating risk of allograft injury, improving early disease detection with noninvasive biomarkers, and ultimately, developing an effective, targeted therapy that can extend the life of the lung allograft.

Azithromycin prophylaxis after lung transplantation is associated with improved overall survival

BACKGROUND

Azithromycin prophylaxis (AP) in lung transplant recipients has been shown to reduce the composite end-point of death or chronic lung allograft dysfunction (CLAD) onset but without a clear effect on overall survival. Our program began using AP in 2010. We sought to evaluate the association between AP and survival and the risk of CLAD and baseline lung allograft dysfunction (BLAD).

METHODS

We studied double lung recipients transplanted between 2004 and 2016. We defined AP as chronic use of azithromycin initiated before CLAD onset. We analyzed the association between AP and death or retransplant using Cox regression with adjustment for potential confounders. We further used Cox and logistic models to assess the relationship between AP and post-transplant CLAD onset and BLAD, respectively.

RESULTS

A total of 445 patients were included, and 344 (77%) received AP (median time from transplant: 51 days). Patients receiving AP were more likely to receive induction with interleukin-2 receptor antagonists (57% vs 35%; p < 0.001). AP was associated with improved survival (hazard ratio [HR]: 0.59; 95% confidence interval [CI]: 0.42-0.82; p = 0.0020) in our fully adjusted model, with a reduced adjusted risk of BLAD (odds ratio: 0.53; 95% CI: 0.33-0.85; p = 0.0460) but no clear reduction in the adjusted risk of CLAD (HR: 0.69; 95% CI: 0.47-1.03; p = 0.0697).

CONCLUSIONS

AP is associated with improved survival after lung transplantation, potentially through improved baseline function. These findings build on prior trial results and suggest that AP is beneficial for lung transplant recipients.

Lung Transplantation and Precision Medicine

Lung transplantation is an accepted therapeutic option for end-stage lung diseases. Its history starts in the 1940s, initially hampered by early deaths due to perioperative problems and acute rejection. Improvement of surgical techniques and the introduction of immunosuppressive drugs resulted in longer survival. Chronic lung allograft dysfunction (CLAD), a new complication appeared and remains the most serious complication today. CLAD, the main reason why survival after lung transplantation is impaired compared to other solid-organ transplantations is characterized by a gradually increasing shortness of breath, reflected in a deterioration of pulmonary function status, respiratory insufficiency and possibly death.

Extracorporeal Photopheresis for Bronchiolitis Obliterans Syndrome After Lung Transplantation

BACKGROUND

Lung transplantation is a therapeutic option for select patients with end-stage lung disease. However, successful lung transplantation is hampered by chronic lung allograft dysfunction, in particular bronchiolitis obliterans syndrome (BOS). Although there is no approved or standard treatment for BOS, which may have several distinct phenotypes, extracorporeal photopheresis (ECP) has shown promising results in patients who develop BOS refractory to azithromycin treatment.

METHODS

We reviewed all relevant clinical data indexed on PubMed from 1987 to 2017 to evaluate the role of ECP in patients with BOS.

RESULTS

Seven small studies investigated the immunomodulatory effects of ECP in patients after solid organ transplant, and 12 studies reported clinical data specific to ECP therapy for BOS. Studies indicate that ECP triggers an apoptotic cellular cascade that exerts various immunomodulatory effects mediated via increases in anti-inflammatory cytokines, a decrease in proinflammatory cytokines, and an increase in tolerogenic regulatory T cells. Clinical evidence derived from relatively small single-center studies suggests that ECP therapy is associated with improvement or stabilization in lung function and sustainable, statistically significant, decreases in the rate of lung function decline in patients with BOS. Additionally, when adverse event data were reported, ECP was generally well tolerated. None of the comparative studies were randomized.

CONCLUSIONS

Immunomodulation mediated via ECP is a rational therapeutic option that may improve clinical outcomes in patients with BOS, particularly in the context of in-depth patient phenotyping as part of a stratified approach to treatment; good quality randomized controlled trials are needed to confirm observational findings.

Montelukast for bronchiolitis obliterans syndrome after lung transplantation: A randomized controlled trial

Bronchiolitis obliterans syndrome (BOS) remains the major problem which precludes long-term survival after lung transplantation. Previously, an open label pilot study from our group demonstrated a possible beneficial effect of montelukast in progressive BOS patients with low airway neutrophilia (<15%), and already on azithromycin treatment, in whom the further decline in pulmonary function was attenuated. This was, however, a non-randomized and non-placebo controlled trial. The study design is a single center, prospective, interventional, randomized, double blind, placebo-controlled trial, with a two arm parallel group design and an allocation ratio of 1:1. Randomization to additional montelukast (10 mg/day, n = 15) or placebo (n = 15) was performed from 2010 to 2014 at the University Hospitals Leuven (Leuven, Belgium) in all consecutive patients with late-onset (>2years posttransplant) BOS ≥1. Primary end-point was freedom from graft loss 1 year after randomization; secondary end-points were acute rejection, lymphocytic bronchiolitis, respiratory infection rate; and change in FEV₁, airway and systemic inflammation during the study period. Graft loss at 1 y and 2y was similar in both groups (respectively p = 0. 981 and p = 0.230). Montelukast had no effect on lung function decline in the overall cohort. However, in a post-hoc subanalysis of BOS stage 1 patients, montelukast attenuated further decline of FEV₁ during the study period, both in absolute (L) (p = 0.008) and % predicted value (p = 0.0180). A linear mixed model confirmed this association. Acute rejection, lymphocytic bronchiolitis, respiratory infections, systemic and airway inflammation were comparable between groups over the study period. This randomized controlled trial showed no additional survival benefit with montelukast compared to placebo, although the study was underpowered. The administration of montelukast was associated with an attenuation of the rate of FEV₁ decline, however, only in recipients with late-onset BOS stage 1.

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.

Efficacy of concomitant administration of clarithromycin and acetylcysteine in bronchiolitis obliterans in seventeen sulfur mustard-exposed patients: An open-label study

BACKGROUND

Victims of sulfur mustard (SM) gas exposure experience different types of chronic pulmonary disease, manifested as cough, sputum production, and dyspnea. Conventional therapies (eg, immunosuppressive drugs, corticosteroids) have not been effective in these patients.

OBJECTIVE

This study was carried out to determine the efficacy of concomitant administration of the macrolide clarithromycin and the mucolytic agent acetylcysteine in the treatment of bronchiolitis obliterans in SM-exposed patients.

METHODS

This open-label clinical study was conducted at the Research Center of Chemical Injuries, Baqiyatallah Medical Sciences University, Tehran, Iran. Clarithromycin and acetylcysteine were administered concomitantly for 6 months to male SM-exposed patients with chronic bronchitis and bronchiolitis obliterans who were nonresponsive to conventional treatments. Efficacy analysis included symptom assessment and pulmonary function tests (forced expiratory volume in 1 second [FEV1], forced vital capacity [FVC], and FEV1/FVC ratio) using spirometry, performed at baseline and after 2 and 6 months of treatment.

RESULTS

Seventeen male patients (mean [SD] age, 38.3 [5.3] years [range, 31-50 years]; mean [SD] body weight, 77.9 [15.7] kg) were included in the study. Cough and sputum production were each found in 10 of 17 patients (58.8%) at baseline and were improved in all 10 patients after the administration of clarithromycin and acetylcysteine. FEV1 and FVC also were improved, by mean (SD) 10.6% (9.7%) (P < 0.001 vs baseline) and 12.9% (13.6%) (P = 0.001 vs baseline). No significant change in FEV1/FVC ratio was found.

CONCLUSIONS

In this study of concomitant administration of clarithromycin and acetylcysteine for the treatment of bronchiolitis obliterans in SM-exposed patients, symptoms and pulmonary function were improved. These results may have been related to the therapeutic effects of a macrolide antibiotic on chronic bronchitis and bronchiolitis obliterans in these patients. Based on the results of this study, we recommend this treatment for chemical warfare victims with recurrent exacerbation of bronchitis who do not respond to conventional treatment.

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.

The potassium channel KCa3.1 as new therapeutic target for the prevention of obliterative airway disease

BACKGROUND

The calcium-activated potassium channel KCa3.1 is critically involved in T-cell activation as well as in the proliferation of smooth muscle cells and fibroblasts. We sought to investigate whether KCa3.1 contributes to the pathogenesis of obliterative airway disease (OAD) and whether knockout or pharmacologic blockade would prevent the development of OAD.

METHODS

Tracheas from CBA donors were heterotopically transplanted into the omentum of C57Bl/6J wild-type or KCa3.1 mice. C57Bl/6J recipients were either left untreated or received the KCa3.1 blocker TRAM-34 (120 mg/kg/day). Histopathology and immunologic assays were performed on postoperative day 5 or 28.

RESULTS

Subepithelial T-cell and macrophage infiltration on postoperative day 5, as seen in untreated allografts, was significantly reduced in the KCa3.1 and TRAM-34 groups. Also, systemic Th1 activation was significantly and Th2 mildly reduced by KCa3.1 knockout or blockade. After 28 days, luminal obliteration of tracheal allografts was reduced from 89%±21% in untreated recipients to 53%±26% (P=0.010) and 59%±33% (P=0.032) in KCa3.1 and TRAM-34-treated animals, respectively. The airway epithelium was mostly preserved in syngeneic grafts, mostly destroyed in the KCa3.1 and TRAM-34 groups, and absent in untreated allografts. Allografts triggered an antibody response in untreated recipients, which was significantly reduced in KCa3.1 animals. KCa3.1 was detected in T cells, airway epithelial cells, and myofibroblasts. TRAM-34 dose-dependently suppressed proliferation of wild-type C57B/6J splenocytes but did not show any effect on KCa3.1 splenocytes.

CONCLUSIONS

Our findings suggest that KCa3.1 channels are involved in the pathogenesis of OAD and that KCa3.1 blockade holds promise to reduce OAD development.

Bronchiolitis

Bronchiolitis is a disease of the small airways accompanied by progressive and often irreversible airflow obstruction. Bronchiolitis can have several causes such as infection, toxic exposure, collagen vascular disease, post lung and stem cell transplant, and idiopathic etiology. Symptoms of cough and sputum production are often mistaken for chronic obstructive pulmonary disease or asthma, leading to a delay in diagnosis. Unfortunately, many types of bronchiolitis do not improve with therapy. Bronchiolitis following lung and stem cell transplant are the most common types seen in adults, and provide important insights into its pathogenesis.

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.

Conversion From Cyclosporine to Tacrolimus Stabilizes the Course of Lung Function in Lung Transplant Recipients With Bronchiolitis Obliterans Syndrome

Bronchiolitis obliterans syndrome (BOS) continues to be the main factor limiting the long-term survival of lung transplant recipients. The objective of this study was to prospectively assess the impact of conversion from cyclosporine (CsA) to tacrolimus on lung function in patients who developed BOS while receiving CsA-based immunosuppressive therapy. A total of 79 patients with BOS were included in the study. Sixty percent of patients had stage II or III BOS according to the International Society for Heart and Lung Transplantation criteria. Mean time from transplantation was 30.4 +/- 21.9 months and all patients were on CsA therapy at enrollment in the study, with mean trough levels of 232.75 +/- 98.26 ng/mL. After conversion, tacrolimus trough levels were 11.0 +/- 3.6 ng/mL at 3 months and 9.0 +/- 3.4 ng/mL at 12 months. Sixteen deaths occurred during the first year postconversion, 56% of which were due to respiratory failure. Comparison of forced expiratory volume in 1 second (FEV(1)) preconversion versus postconversion showed a change in the slope of the FEV(1)-time curve. The slope of the preconversion curve was -0.44 versus a zero slope, whereas the slope of the postconversion curve was 0.005, with a statistically significant difference between both slopes. This change in slopes, which was also seen in FEV(1%), suggests that lung function loss closed after conversion from CsA to tacrolimus supporting this therapeutic strategy in lung transplant recipients with BOS treated with CsA.

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.

Long-term outcome after pulmonary retransplantation

OBJECTIVE

Bronchiolitis obliterans syndrome has become the most limiting factor for long-term outcome after lung transplantation. Redo lung transplantation was performed for end-stage bronchiolitis obliterans syndrome. Long-term outcome was compared with that after primary lung transplantation as well as with other indications for retransplantation.

METHODS

Of 614 lung transplantation procedures performed at our institution, 54 (8.5%) were redo transplants. These were stratified into different groups according to the indication for redo transplantation, including chronic graft failure/bronchiolitis obliterans syndrome, acute graft failure, and posttransplantation airway complications. Long-term survival was compared with that of the primary lung transplantation cohort, thereby respecting the need for pretransplant mechanical ventilatory support in a subanalysis. In addition, recurrence of bronchiolitis obliterans syndrome after redo lung transplantation was compared with the occurrence of bronchiolitis obliterans after primary transplantation.

RESULTS

A 1-year survival of 50% was achieved after redo lung transplantation for acute graft failure and airway complications as well as after primary lung transplantation in patients with pretransplant ventilatory support. Retransplantation for bronchiolitis obliterans syndrome revealed superior 1- (78%) and 5-year (62%) survivals, which were not different from those of first-time lung transplant recipients. In addition, we found a similar incidence of bronchiolitis syndrome after retransplantation for BOS compared with its occurrence after primary lung transplantation.

CONCLUSION

Redo lung transplantation for end-stage bronchiolitis obliterans syndrome leads to acceptable long-term outcome in selected patients. Future analyses of redo lung transplantation data should generally stratify bronchiolitis obliterans syndrome from other indications with higher mortality.

Tacrolimus pharmacokinetics in lung transplantation: new strategies for monitoring

BACKGROUND

Tacrolimus (TAC) dosing in lung transplantation is traditionally based on blood trough levels (C0). The best sampling strategy for the estimation of total drug exposure (area-under-the-curve [AUC]) has not been determined.

METHODS

Thirty-one 12-hour pharmacokinetic profiles were studied in 15 patients (8 men and 7 women, 42.0 +/- 13 years) post-bilateral lung transplantation (7.3 +/- 3.7 months; range, 3-18 months). Twelve-hour AUC (AUC0-12) was calculated by trapezoidal rule. Relationships between individual concentration points or abbreviated kinetics (2-4 concentration points) and AUC0-12 were determined by linear regression analysis (R2; absolute prediction error [APE]).

RESULTS

Pharmacokinetic profiles showed high variability, particularly in the absorption phase. AUC was 221 +/- 47.2 ng/ml (range, 156-329.3 ng/ml) at C0 10 to 15 ng/ml and was independent of TAC dose (R2 = 0.002). C0 was poorly predictive of AUC0-12 (R2 = 0.64; APE, 16.1% +/- 10.9%; range, 1.4%-37.8%). The predictive performance for AUC0-12 was highest with abbreviated kinetics using 4 (C0/C2/C3/C4: R(2) = 0.99; APE, 2.6% +/- 2.0%; range, 0.1%-7%) or 3 concentration points (C0/C2/C4: R2 = 0.98; APE, 2.6% +/- 2.1%; range, 0.1%-9.1%). Of the 2-point kinetics C2/C6 (R2 = 0.96; APE, 5.3% +/- 3.7%; range, 0.1%-12.7%), C2/C4 (R2 = 0.94, APE 6.7% +/- 4.8%; range 0.1%-14.6%) and C0/C4 (R2 = 0.94; APE 4.1% +/- 2.9%; range, 0.5%-11.4%) performed best. Single point strategies (best was C4: R2 = 0.94; APE 7.1% +/- 5.5%, range, 0.2%-24.1%) all had unacceptably high APE (range > 15%).

CONCLUSION

True TAC exposure shows high variability in stable lung transplant patients and is poorly predicted by C0. Abbreviated kinetics covering at least 2 concentration points between 0 and 4 hours post-drug intake are required for an accurate estimation of AUC.

Pre-transplant Soluble CD30 Is Associated With Bronchiolitis Obliterans Syndrome After Lung Transplantation

BACKGROUND

The purpose of this study was to determine the clinical relevance of soluble CD30 (sCD30) concentrations in sera from lung transplantation (LTx) candidates.

METHODS

Soluble CD30 concentrations were determined by enzyme-linked immunoassay in pre-transplantation sera of 38 LTx candidates and in serial samples taken after LTx from 10 patients.

RESULTS

LTx candidates did not have increased serum sCD30 concentrations when compared with healthy controls (mean +/- SE: 22.3 +/- 2.7 vs 26.2 +/- 3.4 U/ml). No relation could be found between age and serum sCD30 concentrations, neither in the pre-transplant patients nor in the healthy controls. In addition, no differences in sCD30 values could be detected between patients sorted by their original type of lung disease. Measurement of sCD30 in pre-transplant sera of LTx patients showed that the median concentration was 20 U/ml and that LTx patients with low sCD30 (< or = 20 U/ml) had a statistically significant (p = 0.039) longer period of freedom from bronchiolitis obliterans syndrome (BOS) compared to those with a high sCD30 concentration (> 20 U/ml). Furthermore, sCD30 concentrations in sera taken at several timepoints after LTx remained stable, although a peak could be observed before the clinical manifestation of acute rejection (AR).

CONCLUSIONS

Soluble CD30 before lung transplantation is significantly associated with an increased risk of BOS after transplantation.

Conversion to Sirolimus and Mycophenolate Can Attenuate the Progression of Bronchiolitis Obliterans Syndrome and Improves Renal Function after Lung Transplantation

BACKGROUND

Bronchiolitis obliterans syndrome (BOS) is the major problem after lung and heart-lung transplantation (LTx/HLTx). Sirolimus (Sir) and Mycophenolate (MMF) showed a promising efficacy in the treatment of BOS in animal models. The first clinical experience in converting LTx/HLTx-recipients with BOS from calcineurin inhibitor-(CNI)-based immunosuppression to a Sir-MMF based immunosuppression is reported herein.

METHODS

Six LTx- and five HLTx-recipients (eight men; 0.9 to 8 years after transplantation) with CNI-based immunosuppression (plus MMF) in whom BOS was diagnosed were included in the study. Mean patient age was 37+/-13 years (range 17-62 years). Sir was started with 6 mg and continued adjusted to according target trough levels (8-14 ng/ml). Subsequently, the CNIs were tapered down and finally stopped. Follow up included self determined pulmonary function tests, microbiological screening, chest radiographs, and laboratory studies

RESULTS

Two acute rejection episodes occurred during the study period. The incidence of infection was 2.2+/-1.3 infections/patient-year after conversion. Mean FEV1 decreased after a mean follow up of 14.8+/-1.4 months: from 2.1+/-0.7 l prior conversion to 1.3+/-0.6l after conversion (P=0.03). However, graft function remained stable in three patients and progression of BOS slowed down in three patients. Overall, 2 of 10 patients died due to ongoing BOS while awaiting retransplantation

CONCLUSIONS

After BOS was diagnosed, conversion to MMF and Sir stabilized graft function only in some of the converted patients. Therefore, earlier administration of Sir-based immunosuppression might be a more promising approach. Whether conversion to CNI-free immunosuppression can actually ameliorate the extent or progression of BOS has to be investigated in randomized trials.

Bronchiolitis Obliterans Syndrome

Post-transplantation bronchiolitis obliterans syndrome (BOS) is a clinicopathological syndrome characterised histologically by obliterative bronchiolitis (OB) and physiologically by airflow limitation. It affects long-term survival with no consistently effective treatment strategy.An updated review of risk factors for OB/BOS, and approaches to prevention and treatment was performed through a systematic review of relevant studies between January 1990 and February 2005. The initial search identified 853 publications, with 56 articles reviewed after exclusions. Early acute rejection is the most significant risk factor, with late rejection (> or =3 months) also significant. Lymphocytic bronchitis/bronchiolitis is relevant, with later onset associated with greater risk. Viral infections are identified as significant risk factors. Human leukocyte antigen matching and OB/BOS development is a weaker association, but is stronger with acute rejection. Recipient and donor characteristics have a minor role. There is limited evidence that altering immunosuppression is effective in reducing the rate of decline in lung function. BOS reflects an allo-immunological injury, possibly triggered by cytomegalovirus and respiratory viral infections, or noninfectious injury. Immunological susceptibility may be reflected by more frequent acute rejection episodes. Preventative and therapeutic modifications in immunosuppression remain important. Identifying markers of immunological susceptibility and, hence, risk stratification requires further research.

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.

An update on clinical outcomes in heart and lung transplantation

Much progress has been made in heart and lung transplantation over recent decades. The immune mechanisms that result in allograft rejection are now better understood, and the development of immunosuppressant therapies has decreased recipient mortality among transplant recipients. During the 1980s, immunosuppressant therapy primarily involved the use of corticosteroids and cyclosporine. However, while survival rates increased among transplant recipients, many patients experienced primary graft failures, acute and chronic rejection, as well as death. Until the introduction of tacrolimus in the early 1990s, all patients received the same immunosuppressant regimen, regardless of its effectiveness. Tacrolimus therapy has contributed much to the success rates of both heart and lung transplantation, and by 2001, it had become the preeminent immunosuppressant agent used in lung transplantation.

Tacrolimus: a further update of its use in the management of organ transplantation

Extensive clinical use has confirmed that tacrolimus (Prograf) is a key option for immunosuppression after transplantation. In large, prospective, randomised, multicentre trials in adults and children receiving solid organ transplants, tacrolimus was at least as effective or provided better efficacy than cyclosporin microemulsion in terms of patient and graft survival, treatment failure rates and the incidence of biopsy-proven acute and corticosteroid-resistant rejection episodes. Notably, the lower incidence of rejection episodes after renal transplantation in tacrolimus recipients was reflected in improved cost effectiveness. In bone marrow transplant (BMT) recipients, the incidence of tacrolimus grade II-IV graft-versus-host disease was significantly lower with tacrolimus than cyclosporin treatment. Efficacy was maintained in renal and liver transplant recipients after total withdrawal of corticosteroid therapy from tacrolimus-based immunosuppression, with the incidence of acute rejection episodes at up to 2 years' follow-up being similar with or without corticosteroids. Tacrolimus provided effective rescue therapy in transplant recipients with persistent acute or chronic allograft rejection or drug-related toxicity associated with cyclosporin treatment. Typically, conversion to tacrolimus reversed rejection episodes and/or improved the tolerability profile, particularly in terms of reduced hyperlipidaemia. In lung transplant recipients with obliterative bronchiolitis, conversion to tacrolimus reduced the decline in and/or improved lung function in terms of forced expiratory volume in 1 second. Tolerability issues may be a factor when choosing a calcineurin inhibitor. Cyclosporin tends to be associated with a higher incidence of significant hypertension, hyperlipidaemia, hirsutism, gingivitis and gum hyperplasia, whereas the incidence of some types of neurotoxicity, disturbances in glucose metabolism, diarrhoea, pruritus and alopecia may be higher with tacrolimus treatment. Renal function, as assessed by serum creatinine levels and glomerular filtration rates, was better in tacrolimus than cyclosporin recipients at up to 5 years' follow-up.

CONCLUSION

Recent well designed trials have consolidated the place of tacrolimus as an important choice for primary immunosuppression in solid organ transplantation and in BMT. Notably, in adults and children receiving transplants, tacrolimus-based primary immunosuppression was at least as effective or provided better efficacy than cyclosporin microemulsion treatment in terms of patient and graft survival, treatment failure and the incidence of acute and corticosteroid-resistant rejection episodes. The reduced incidence of rejection episodes in renal transplant recipients receiving tacrolimus translated into a better cost effectiveness relative to cyclosporin microemulsion treatment. The optimal immunosuppression regimen is ultimately dependent on balancing such factors as the efficacy of the individual drugs, their tolerability, potential for drug interactions and pharmacoeconomic issues.

Lung transplants with tacrolimus and mycophenolate mofetil: a review

Traditionally, immunosuppressive maintenance therapy in solid organ transplantation has consisted of cyclosporine (CsA), azathioprine, and prednisone. However, lung transplant recipients are far more frequently affected by acute rejection, especially during the first 6 months after the transplantation, than patients with other transplanted organs. Further, they display a greater risk for chronic transplant dysfunction and ultimate graft loss. Bronchiolitis obliterans syndrome (BOS) is the major cause of morbidity and mortality among long-term survivors after lung transplantation. Acute pulmonary allograft rejection has been identified as the major risk factor for the development of BOS. Based on favourable results in kidney, liver, and heart transplantation, tacrolimus and mycophenolate mofetil have been used as primary prophylaxis and as rescue therapy for recurrent or persistent acute rejection and BOS. A secondary indication is CsA toxicity. This review focuses on reported results of the combination of tacrolimus and mycophenolate mofetil in lung transplantation. These new immunosuppressive drugs have markedly improved the efficacy profiles without additional detrimental toxicities, and appear to be a safe alternative to CsA and azathioprine in patients following lung transplantation. However, at present, BOS is not influenced by these new drugs. The optimal long-term immunosuppressive regimen remains to be established.