Tests of airway function in detecting and monitoring treatment of obliterative bronchiolitis after lung transplantation

Lymphocyte Depleting and Modulating Therapies for Chronic Lung Allograft Dysfunction

Chronic lung rejection, also called chronic lung allograft dysfunction (CLAD), remains the major hurdle limiting long-term survival after lung transplantation, and limited therapeutic options are available to slow the progressive decline in lung function. Most interventions are only temporarily effective in stabilizing the loss of or modestly improving lung function, with disease progression resuming over time in the majority of patients. Therefore, identification of effective treatments that prevent the onset or halt progression of CLAD is urgently needed. As a key effector cell in its pathophysiology, lymphocytes have been considered a therapeutic target in CLAD. The aim of this review is to evaluate the use and efficacy of lymphocyte depleting and immunomodulating therapies in progressive CLAD beyond usual maintenance immunosuppressive strategies. Modalities used include anti-thymocyte globulin, alemtuzumab, methotrexate, cyclophosphamide, total lymphoid irradiation, and extracorporeal photopheresis, and to explore possible future strategies. When considering both efficacy and risk of side effects, extracorporeal photopheresis, anti-thymocyte globulin and total lymphoid irradiation appear to offer the best treatment options currently available for progressive CLAD patients. SIGNIFICANCE STATEMENT: Effective treatments to prevent the onset and progression of chronic lung rejection after lung transplantation are still a major shortcoming. Based on existing data to date, considering both efficacy and risk of side effects, extracorporeal photopheresis, anti-thymocyte globulin, and total lymphoid irradiation are currently the most viable second-line treatment options. However, it is important to note that interpretation of most results is hampered by the lack of randomized controlled trials.

Long-Term Follow-up of a Randomized Controlled Trial Evaluating a Mobile Health Intervention for Self-Management in Lung Transplant Recipients

Mobile health interventions may help transplant recipients follow their complex medical regimens. Pocket Personal Assistant for Tracking Health (Pocket PATH) is one such intervention tailored for lung transplant recipients. A randomized controlled trial showed Pocket PATH's superiority to usual care for promoting the self-management behaviors of adherence, self-monitoring and communication with clinicians during posttransplant year 1. Its long-term impact was unknown. In this study, we examined associations between Pocket PATH exposure during year 1 and longer term clinical outcomes-mortality and bronchiolitis obliterans syndrome (BOS)-among 182 recipients who survived the original trial. Cox regression assessed whether (a) original group assignment and (b) performance of self-management behaviors during year 1 predicted time to outcomes. Median follow-up was 5.7 years after transplant (range 4.2-7.2 years). Pocket PATH exposure had no direct effect on outcomes (p-values >0.05). Self-monitoring was associated with reduced mortality risk (hazard ratio [HR] 0.45; 95% confidence interval [CI] 0.22-0.91; p = 0.027), and reporting abnormal health indicators to clinicians was associated with reduced risks of mortality (HR 0.15; 95% CI 0.04-0.65; p = 0.011) and BOS (HR 0.27; 95% CI 0.08-0.86; p = 0.026), regardless of intervention group assignment. Although Pocket PATH did not have a direct impact on long-term outcomes, early improvements in self-management facilitated by Pocket PATH may be associated with long-term clinical benefit.

A randomised controlled trial of azithromycin therapy in bronchiolitis obliterans syndrome (BOS) post lung transplantation

Background

We conducted a placebo-controlled trial of azithromycin therapy in bronchiolitis obliterans syndrome (BOS) post lung transplantation.

Methods

We compared azithromycin (250 mg alternate days, 12 weeks) with placebo. Primary outcome was FEV₁ change at 12 weeks.

Results

48 patients were randomised; (25 azithromycin, 23 placebo). It was established, post randomisation that two did not have BOS. 46 patients were analysed as intention to treat (ITT) with 33 ‘Completers’. ITT analysis included placebo patients treated with open-label azithromycin after study withdrawal.

Outcome

The ITT analysis (n=46, 177 observations) estimated mean difference in FEV₁ between treatments (azithromycin minus placebo) was 0.035 L, with a 95% CI of −0.112 L to 0.182 L (p=0.6). Five withdrawals, who were identified at the end of the study as having been randomised to placebo (four with rapid loss in FEV₁, one withdrawn consent) had received rescue open-label azithromycin, with improvement in subsequent FEV₁ at 12 weeks. Study Completers showed an estimated mean difference in FEV₁ between treatment groups (azithromycin minus placebo) of 0.278 L, with 95% CI for the mean difference: 0.170 L to 0.386 L (p=<0.001). Nine of 23 ITT patients in the azithromycin group had ≥10% gain in FEV₁ from baseline. No patients in the placebo group had ≥10% gain in FEV₁ from baseline while on placebo (p=0.002). Seven serious adverse events, three azithromycin, four in the placebo group, were deemed unrelated to study medication.

Conclusions

Azithromycin therapy improves FEV₁ in patients with BOS and appears superior to placebo. This study strengthens evidence for clinical practice of initiating azithromycin therapy in BOS.

Trial registration number

EU-CTR, 2006-000485-36/GB.

Inhaled Corticosteroids and Long-Acting β2-Agonists in Treatment of Patients with Chronic Bronchiolitis Following Exposure to Sulfur Mustard

We examined the role of two regimens of combination inhaler therapy on amount of reversibility of chronic lung complications in mustard gas exposed patients. In a phase III, prospective, randomized clinical trial, 105 participants received either combination form of fluticasone propionate and salmetrol, 500/100 microg daily (group 1; n = 52) or beclomethasone, 1000 microg daily, and salbutamol inhaler, 800 microg daily (group 2; n = 53) for 12 wk. Pulmonary function test (PFT) indices and respiratory symptoms (including dyspnea, night awakening due to dyspnea and cough) were assessed at baseline and in each visit. Thirty-six patients in group 1 and 30 patients in group 2 completed study course. Both medication regimes increased pretreatment forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), FEV1/FVC%, and peak expiratory force (PEF) by the end of 12 wk. It seems that these improvements are more constant in group 1 than in group 2. Reversibility, that is, 10% increase of FEV1 in the second month was seen for 27% of patients in the group 1 and for 7% in the group 2. VAS scores have decreased in two groups during treatment period (p = .003) and after follow-up period it remained sustained in group 1 alone. Inhaled corticosteroids and long-acting beta 2-agonists are effective in treatment of patients with chronic bronchiolitis following exposure to sulfur mustard. However, a medium dose of fluticasone/salmeterol has the same effect on the airways reversibility, rather than a very high dose of beclomethasone with only the short-acting beta-agonist.

Adherence to the Therapeutic Regimen in Heart, Lung, and Heart-Lung Transplant Recipients

Optimal outcome after heart, lung, and heart-lung transplantation can only be obtained if patients are supported in adhering to a lifelong therapeutic regimen. The transplant patient's therapeutic regimen consists of a lifelong medication regimen, including immunosuppressive drugs; monitoring for signs and symptoms related to complications; avoidance of risk factors for cardiovascular disease and cancer (ie, diet and exercise prescriptions, nonsmoking); avoidance of abuse/dependence of alcohol or illegal drugs, as well as attending regular clinical checkups. Nonadherence to all aspects of this regimen is substantial. Nonadherence has been related to negative clinical outcome in view of acute rejections, graft vasculopathy, higher costs, and mortality. This review focuses on the prevalence, correlates, and consequences of nonadherence to the therapeutic regimen in heart, lung, and heart-lung transplantation. The current state of the-art on adherence-enhancing interventions is reported. Priorities for future research are outlined.

Surrogate markers and risk factors for chronic lung allograft dysfunction

Obliterative bronchiolitis (OB) is the histologic correlate of chronic allograft dysfunction in pulmonary transplantation. The histologic diagnosis of OB is challenging, therefore a physiologic definition, bronchiolitis obliterans syndrome (BOS) based on pulmonary function tests has been used as a surrogate marker for OB for the last decade. BOS has proven to be the best available surrogate marker for OB and is predictive of the ultimate endpoints of graft and patient survival. Multiple other clinical markers have been reported and proposed as alternates for or complements to BOS grade, but all need further evaluation and validation in large, prospective clinical trials. Lastly, given the early occurrence and high incidence of chronic allograft dysfunction, the easily measurable endpoint of BOS grade, and our lack of understanding of ways to prevent or alter the course of BOS, lung transplant recipients represent an ideal population for clinical trials targeting prevention and treatment of chronic allograft dysfunction.

Bronchiolitis obliterans syndrome

BOS remains a difficult problem to control following lung transplantation, largely because of uncertainties regarding the underlying mechanisms that are responsible for it. Continued work on the pathogenesis of BOS is essential. The progressive nature and poor outlook when BOS stage 3 is reached indicates that current strategies should be focused on prevention and early intervention. There is a great need for randomized, controlled trials on intervention if the international transplant community is to make progress in this area.

Bronchiolar airflow impairment after lung transplantation: an early and common manifestation

BACKGROUND

Bronchiolitis obliterans syndrome (BOS) is the major limitation to long-term survival after lung transplantation (LT). In this study we investigate the extent and frequency of airflow limitation after LT and its value for the diagnosis of BOS.

METHODS

Flow-volume measurements were analyzed retrospectively in 36 recipients of a bilateral LT, with a median follow-up of 32.9 months. The prevalence and onset of a decline of FEV(1), FEF(25), FEF(50), FEF(75) and MMEF(75/25) were evaluated and subsequently related to the occurrence of Grade 1 BOS.

RESULTS

Grade 1 BOS was diagnosed in 16 recipients at a median of 218 (range 88 to 1,007) days after LT. A persistent and significant decrease in FEV(1), FEF(25), FEF(50), FEF(75) and MMEF(75/25) was observed in 23, 24, 30, 32 and 29 patients, respectively. In those patients developing BOS during follow-up this decrease was determined at 147 (55 to 657), 130 (78 to 932), 110 (21 to 573), 103 (32 to 657) and 121 (32 to 657) days after LT (p < 0.0005), respectively. The respective predictive values of these parameters for the occurrence of Grade 1 BOS (within 120 days) were 88%, 60%, 50%, 35% and 41%.

CONCLUSION

Bronchiolar dysfunction is a common and early finding after LT. The decrease of FEV(1) in BOS is often preceded by a decrease of bronchial airflow. Airflow markers may be used as an early warning sign for the development of BOS, although their predictive values are moderate.

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

BACKGROUND

Bronchiolitis obliterans syndrome (BOS), defined as an irreversible, staged decline in forced expiratory volume in 1 second (FEV(1)), is an established marker of obliterative bronchiolitis. Potential causes of BOS include sub-clinical chronic rejection and/or exaggerated healing response following acute injury. BOS may thus result from two or more distinct processes, both acute and chronic.

METHODS

A total of 5,916 measurements of FEV(1) from 204 lung transplant recipients surviving at least 6 months after transplantation were analyzed. Follow-up ranged from 6 months to 13 years. By adjusting for the acute effects of rejection, pulmonary infection and measurement variation on FEV(1) trace, patients either had a linear decline characterized by a single acute drop in FEV(1) of >15% at BOS onset, or a chronic linear decline in FEV(1). The fraction having acute onset was estimated. Acute events occurring within the first 6 months were assessed as risk factors for acute onset BOS.

RESULTS

Of the 204 patients, 8% died before BOS onset and 18% were BOS-free at analysis. For 18% of patients, BOS onset followed a chronic linear decline in FEV(1) of 3.7% per year, with a median time of BOS onset >99 months. For 56% of patients, BOS onset followed an acute drop in FEV(1) of median 33.8% (95% CI 19.1% to 39.7%), with median onset time of 52 months. During the first 6 months, acute rejection was significantly and independently associated with acute onset of BOS (relative risk = 1.15 per episode, 95% CI [1.03 to 1.29], p = 0.01), whereas pulmonary infection and cytomegalovirus (CMV) infection were not. Acute BOS onset followed a documented acute event in the previous 6 months in 38 of 114 (33%) of cases.

CONCLUSIONS

BOS likely reflects more than one process. Compared with those who had a slow linear decline in lung function, acute BOS onset was associated with acute rejection in the first 6 months, was often triggered by an acute event and had poor prognosis, with obliterative bronchiolitis (OB) the main cause of death.

Dependence of murine obstructive airway disease on CD40 ligand

BACKGROUND

Human lung transplantation carries a poor prognosis because of chronic rejection in the form of obliterative bronchiolitis syndrome (OBS). Using the mouse model of heterotopic tracheal transplantation, we examined the role of costimulation in the allograft rejection that characterizes obstructive airway disease (OAD).

METHODS

C57BL/6 or BALB/c tracheae were implanted into wild-type control, CD28-/-, muMT (B-cell deficient), or CD40L-/- recipient mice. Grafts were explanted from 7 to 42 days posttransplantation and evaluated.

RESULTS

Thickening of the basement membrane and a decrease in patent luminal area were first noted at 2 weeks in wild-type allogeneic trachea recipients and to a slightly lesser degree in CD28-/- recipients. In contrast, CD40L-/- recipient mice showed no evidence of cellular infiltrates or fibrosis in transplanted tracheae. To determine whether CD40L interacted with host or donor CD40, CD40-deficient tracheae were transplanted into CD40L+/+, CD40+/+ wild-type mice. Wild-type mice rejected CD40-/- tracheae. Tracheae were transplanted into B-cell-deficient mice to determine the role of B-cell CD40 in chronic pulmonary allograft rejection. The OAD reaction was identical in wild-type and B-cell-deficient mice.

CONCLUSIONS

Development of OAD in the mouse trachea transplant model is primarily dependent on CD40L and is relatively CD28 independent. The ability of mice to reject CD40-/- tracheae demonstrated that host, not donor, CD40 is required for rejection. Furthermore, the ability of B-cell-deficient mice to reject allogeneic tracheae demonstrated that B-cell CD40-mediated responses are not required for the development of OAD.

Conservation of small-airway function by tacrolimus/cyclosporine conversion in the management of bronchiolitis obliterans following lung transplantation

We studied serial lung function in 11 patients with bronchiolitis obliterans syndrome who were treated with tacrolimus conversion following lung or heart-lung transplantation. Our results show that tacrolimus conversion slows the decline of lung function in bronchiolitis obliterans syndrome. The attenuation continues for at least 1 year following conversion.