Bronchiolitis Obliterans

Hematopoietic stem cell transplant (HSCT) is an effective but toxic therapy and pulmonary morbidity affects as many as 25% of children receiving transplant. Early pulmonary injury includes diffuse alveolar hemorrhage (DAH), thrombotic microangiopathy (TMA) interstitial pneumonitis (IPS) and infection, while later, bronchiolitis obliterans is a complication of chronic GVHD associated with severe morbidity and mortality. Improved diagnosis and treatment of pulmonary complications are urgently needed as survival after HSCT improves, and as HSCT is increasingly used for non-malignant disorders such as sickle cell disease. Currently, there are large and important gaps in the investigator's knowledge regarding incidence, etiology and optimal treatment of pulmonary complications. Moreover, young children unable to perform spirometry are often diagnosed late, and strategies for monitoring therapeutic response are limited. This is a prospective multi-institutional cohort study in pediatric patients undergoing allogeneic hematopoietic stem cell transplantation (alloHSCT). Assembly of a large prospective uniformly screened cohort of children receiving HSCT, together with collection of biological samples, will be an effective strategy to identify mechanisms of lung injury, test novel diagnostic strategies for earlier diagnosis, and novel treatments to reduce morbidity and mortality from lung injury after transplant.

The goal of this research study is to test the efficacy of a novel immunosuppressive agent, belumosudil, in allogeneic hematopoietic stem cell transplant (HSCT) recipients who have been newly diagnosed or have developing (early stage) bronchiolitis obliterans syndrome (BOS). The name of the study drugs involved in this study are: * Belumosudil (an immunotherapy) * Fluticasone (an intranasal corticosteroid) * Azithromycin (an antibiotic) * Montelukast (a leukotriene receptor antagonist) * Prednisone (a corticosteroid)

This study investigates a type of cell, called abnormal clonogenic epithelial cells, in patients with bronchiolitis obliterans syndrome who have had an donor stem cell transplant or a lung transplant. Learning more about clonogenic cells in these patients may help doctors to detect signs of bronchiolitis obliterans syndrome earlier in future patients.

Bronchiolitis obliterans (BO) is an irreversible chronic obstructive pulmonary pathology leading to obstruction and/or obliteration of the small airways. In children, the most common form of BO occurs following a serious lower respiratory tract infection. This is a rare complication; the incidence is unknown. The diagnosis, often late, is made on clinical, spirometric and radiological arguments. The pathophysiology would be linked to damage to the airway epithelium. PIBO is most commonly associated with adenovirus (ADV) infection (serotypes 3, 7, 11 and 21) but also other viruses such as rhinovirus (RV). The treatment of PIBO is not clearly established, it remains empirical. The research hypothesis is that the morphology of the nasal epithelium of children with ADV or RV infection is different for those progressing to PIBO. The main objective of the proposed observational study is to characterize damage to the respiratory epithelium in these children. This is a single-center prospective longitudinal study (AP-HM), in children aged 1 month to 6 years, comparing children hospitalized for lower respiratory infection by ADV or RV progressing or not to PIBO. All children included will have a nasal swab and brushing on D0. Children developing PIBO will have nasal brushing with bronchial endoscopy with bronchial biopsies and bronchoalveolar washing at the time of PIBO diagnosis and again at M6 in case of partial response to treatment. This is therefore a pilot study aimed at defining damage to the respiratory epithelium in children with PIBO following an ADV or RV infection and the role of respiratory epithelial cells in PIBO.