Bronchiolitis obliterans following hematopoietic stem cell transplantation: a clinical update

Bronchiolitis obliterans after stem cell transplantation for hematologic malignancies rescued by lung transplantation: A report of two cases

Bronchiolitis obliterans syndrome (BOS) occurring after hematopoietic stem cell transplantation (HSCT) for hematologic malignancies is a progressive and refractory disease, and lung transplantation (LTx) seems to be the only promising treatment. We report two cases of BOS after HSCT, which showed distinct clinical courses and were successfully treated with LTx. The respiratory symptoms and function of the two patients progressively deteriorated to a critical level during the waiting period. In one patient, recurrent and intractable pneumothoraxes consistent with thoracic air-leak syndrome (TALS) occurred, which were associated with pleuroparenchymal fibroelastosis. TALS could accelerate clinical deterioration, thus permitting a shorter waiting period for LTx.

Current Approach to Non-Infectious Pulmonary Complications of Hematopoietic Stem Cell Transplantation

Hematopoietic stem cell transplantation is an established treatment for patients with a wide range of malignant and nonmalignant conditions. Noninfectious pulmonary complications still remain a leading cause of morbidity and mortality in these patients. Treating hematopoietic stem cell transplantation recipients with noninfectious pulmonary complications is still challenging, and the current treatment armamentarium and strategies are not adequate for patients receiving hematopoietic stem cell transplantation. Further trials are needed for a better description of the pathogenesis and the complete diagnostic criteria as well as for the development of effective therapeutic approaches for the management of noninfectious pulmonary complications of the hematopoietic stem cell transplantation. This review outlines the incidence, risk factors, pathogenesis, and clinical spectrum and discusses the current approaches to the management of noninfectious pulmonary complications of Hematopoietic stem cell transplantation.

Major Pulmonary Complications After Hematopoietic Stem Cell Transplant

Both autologous and allogeneic hematopoietic stem cell transplants are important therapeutic options for several benign and malignant disorders. Pulmonary complications, although they have become less frequent, remain a significant cause of morbidity and mortality after hematopoietic stem cell transplant. These complications range from bacterial, fungal, and viral pulmonary infections to noninfectious conditions such as diffuse alveolar hemorrhage and idiopathic pneumonia syndrome. Bronchiolitis obliterans syndrome is the primary chronic pulmonary complication, and treatment of this condition remains challenging. This report highlights the advances in the diagnosis and management of the major pulmonary complications after hematopoietic stem cell transplant. It also underscores the need for prospective and multicenter research to have a better understanding of the mechanisms behind these complications and to obtain more effective diagnostic tool and therapeutic options.

Risk Factor and Clinical Outcome of Bronchiolitis Obliterans Syndrome after Allogeneic Hematopoietic Stem Cell Transplantation

PURPOSE

The development of bronchiolitis obliterans syndrome (BOS) after allogeneic hematopoietic stem cell transplantation (HSCT) deteriorates patients' quality of life. This study aimed to analyze the prevalence, clinical features, risk factors and prognostic factors of BOS.

MATERIALS AND METHODS

This retrospective study included patients who underwent allogeneic HSCT from January 2002 to December 2008 and survived for ≥100 days after transplantation.

RESULTS

Of 860 patients who survived for ≥100 days, 36 (4.2%) met the diagnostic criteria. The duration of BOS development after transplantation was 466.00 (284.00-642.75) [median (interquartile range)] days. The risk factor for the development of BOS was peripheral blood as the stem cell source with a hazard ratio (HR) of 2.550 [95% confidence interval (CI): 1.274-5.104, p=0.008]. In multivariate analysis, pretransplant FEV₁/FVC (HR: 0.956, 95% CI: 0.921-0.993, p=0.020) and time from HSCT to diagnosis of BOS (HR: 0.997, 95% CI: 0.994-0.999, p=0.009) were independent prognostic factors associated with mortality.

CONCLUSION

Peripheral blood as a stem cell source is a risk factor for the development of BOS. A decreased pretransplant FEV₁/FVC and shorter duration of time from transplantation to diagnosis of BOS are poor prognostic factors for BOS.

Lung transplantation following hematopoietic stem cell transplantation: report of two cases and systematic review of literature

BACKGROUND

Non-infectious pulmonary complications following hematopoietic stem cell transplantation (HSCT) are major cause of morbidity and mortality with limited treatment options. Lung transplantation (LT) has been rarely reported as a treatment option for selected HSCT recipients with these problems.

OBJECTIVE

Describe the outcome of HSCT recipients who underwent LT.

METHODS

Two cases of LT following HSCT from our institution are presented. Cases reported in literature were identified using English language PubMed/MEDLINE with keywords hematopoietic stem cell transplantation, bone marrow transplantation, or bronchiolitis obliterans cross-referenced with lung transplantation. We extracted data on baseline characteristics and survival data following LT.

RESULTS

Total of 84 patients are analyzed. Age at time of LT was median of 22 yr (range 1-66). Seventy-nine patients were recipients of allogeneic HSCT. The indications for LT were bronchiolitis obliterans syndrome (BOS; 63 patients), pulmonary fibrosis (13 patients), BOS/pulmonary fibrosis (five patients), and graft-versus-host-disease (GVHD) of lung (three patients). The median time between HSCT and LT was 52.3 months (range 6-240). The median follow-up after LT was 36 months (range 0-168). During this time, BOS was documented in 25 patients. Relapse of hematological malignancy was reported in two patients, and new malignancy developed in four patients. At the end of follow-up, 60 patients were alive and 24 patients died. The probability of survival following LT at 24 and 36 months was 0.88 (95% CI 0.78-0.93) and 0.79 (95% CI 0.67-0.87), respectively.

CONCLUSION

LT is a potential therapeutic option in selected patients with severe chronic pulmonary disease following HSCT. Further studies are needed to determine the appropriate timing and the outcome of this approach.

Can the anti-inflammatory activities of β2-agonists be harnessed in the clinical setting?

Beta2-adrenoreceptor agonists (β2-agonists) are primarily bronchodilators, targeting airway smooth muscle and providing critical symptomatic relief in conditions such as bronchial asthma and chronic obstructive pulmonary disease. These agents also possess broad-spectrum, secondary, anti-inflammatory properties. These are mediated largely, though not exclusively, via interactions with adenylyl cyclase-coupled β2-adrenoreceptors on a range of immune and inflammatory cells involved in the immunopathogenesis of acute and chronic inflammatory disorders of the airways. The clinical relevance of the anti-inflammatory actions of β2-agonists, although often effective in the experimental setting, remains contentious. The primary objectives of the current review are: firstly, to assess the mechanisms, both molecular and cell-associated, that may limit the anti-inflammatory efficacy of β2-agonists; secondly, to evaluate pharmacological strategies, several of which are recent and innovative, that may overcome these limitations. These are preceded by a consideration of the various types of β2-agonists, their clinical applications, and spectrum of anti-inflammatory activities, particularly those involving adenosine 3',5'-cyclic adenosine monophosphate-activated protein kinase-mediated clearance of cytosolic calcium, and altered gene expression in immune and inflammatory cells.

Rattus model utilizing selective pulmonary ischemia induces bronchiolitis obliterans organizing pneumonia

Bronchiolitis obliterans organizing pneumonia (BOOP), a morbid condition when associated with lung transplant and chronic lung disease, is believed to be a complication of ischemia. Our goal was to develop a simple and reliable model of lung ischemia in the Sprague-Dawley rat that would produce BOOP. Unilateral ischemia without airway occlusion was produced by an occlusive slipknot placed around the left main pulmonary artery. Studies were performed 7 days later. Relative pulmonary and systemic flow to each lung was measured by injection of technetium Tc 99m macroaggregated albumin. Histological sections were examined for structure and necrosis and scored for BOOP. Apoptosis was detected by immunohistochemistry with an antibody against cleaved caspase 3. Pulmonary artery blood flow to left lungs was less than 0.1% of the cardiac output, and bronchial artery circulation was ∼2% of aortic artery flow. Histological sections from ischemic left lungs consistently showed Masson bodies, inflammation, and young fibroblasts filling the distal airways and alveoli, consistent with BOOP. In quantitative evaluation of BOOP using epithelial changes, inflammation and fibrosis were higher in ischemic left lungs than right or sham-operated left lungs. Apoptosis was increased in areas exhibiting histological BOOP, but there was no histological evidence of necrosis. Toll-like receptor 4 expression was increased in ischemic left lungs over right. An occlusive slipknot around the main left pulmonary artery in rats produces BOOP, providing direct evidence that ischemia without immunomodulation or coinfection is sufficient to initiate this injury. It also affords an excellent model to study signaling and genetic mechanisms underlying BOOP.

Distribution of aerosols in murine obliterative bronchiolitis lungs by fluorescent imaging

ABSTRACT Background: Obliterative bronchiolitis (OB) is a major obstacle to the success of lung transplantation and is also a serious complication of hematopoietic stem cell transplant. It has few therapeutic options and respiratory delivery of potential therapeutic drugs is hindered by the narrowed and occluded airways.

METHODS

OB was induced in mice using an established protocol and lung function was assessed by plethysmograph. Mice were exposed to four different aerosols of aluminum phthalocyanine tetrasulfonic acid (AlPCS) that ranged in concentration and median particle size distribution (0.2-4.0 μm). The fluorescent intensity and number of pixels were measured for the trachea and lobes at two different compressional thicknesses. With analysis of the fluorescent intensity, the concentration and attenuation coefficient were estimated for each lobe and the trachea as well as individual pixels. The latter allowed generation of images reflective of the concentration.

RESULTS

Lungs/trachea from OB mice had lower deposition, which correlated with lung function measurements, and apparent greater variability in the intensity compared to controls. The estimated lung volumes measured by plethysmograph were not different between the OB group and controls; however, total inflational lung capacity was reduced in OB mice.

CONCLUSIONS

Despite the variability in disease induction, there is a clear link between aerosol deposition and lung function, which was revealed by fluorescent imaging. The modulation of aerosol deposition in lungs with restrictive airway disease underscores the importance of tailoring aerosolization to optimize drug delivery.

Long-term health impacts of hematopoietic stem cell transplantation inform recommendations for follow-up

Advances in transplantation techniques and supportive care strategies have resulted in a significant improvement in survival of those who have undergone treatment. However, hematopoietic stem cell transplantation (HSCT) survivors are at risk of developing long-term complications, such as endocrinopathies, musculoskeletal disorders, cardiopulmonary compromise and subsequent malignancies. These complications have a direct impact on the morbidity and mortality experienced by HSCT survivors. Two-thirds of HSCT survivors develop at least one chronic health condition; while a fifth develop severe or life-threatening conditions. HSCT patients who have survived for at least 5 years post-transplantation are at a fourfold to ninefold increased risk of late mortality for as long as 30 years from HSCT, producing an estimated 30% lower life expectancy compared with the general population. The high burden of morbidity experienced by HSCT survivors makes it critically important that there is standardized follow-up of HSCT survivors at high risk for post-HSCT complications. The Center for International Blood and Marrow Transplant Research/European Group for Blood and Marrow Transplantation/American Society for Blood and Marrow Transplantation and the Children's Oncology Group long-term follow-up guidelines offer such standardized care. Future steps include wider dissemination and refinement of these guidelines.

The spectrum of noninfectious pulmonary complications following hematopoietic stem cell transplantation

Hematopoietic stem cell transplantation (HSCT) is an established treatment for a variety of malignant and nonmalignant conditions. Pulmonary complications, infectious and noninfectious, are a major cause of morbidity and mortality in these patients. The recent advances in prophylaxis and treatment of infectious complications increased the significance of noninfectious pulmonary conditions. Acute lung injury due to diffuse alveolar hemorrhage or idiopathic pneumonia syndrome are the main acute complications, while bronchiolitis obliterans remains the most challenging pulmonary complications facing clinicians who are taking care of HSCT recipients. There are other noninfectious pulmonary complications following HSCT that are less frequent. This report provides a clinical update of the incidence, risk factors, pathogenesis, clinical characteristics and management of the main noninfectious pulmonary complications following HSCT.

Diagnosis and treatment of constrictive bronchiolitis

Constrictive bronchiolitis is a bronchiolar airway disease that surrounds the lumen with fibrotic concentric narrowing and obliteration. The mosaic pattern seen on the expiratory high-resolution chest CT scan is diagnostic in an individual with shortness of breath, early inspiratory crackles, and irreversible airflow obstruction. Swyer-James-MacLeod syndrome is no longer considered a congenital disorder but as constrictive bronchiolitis detected in young adults who had infectious pneumonia during infancy. For lung transplant recipients, tacrolimus continues to be an important immune suppression medication, extracorporeal photopheresis may improve the decline of pulmonary function, and azithromycin may be effective in some lung transplant recipients for treatment of bronchiolitis obliterans syndrome for prevention of constrictive bronchiolitis.