Signature of the Host Response to a Respiratory Viral Infection, in the Prediction of Bronchiolitis Obliterans

Bronchiolitis obliterans (BO) is the well-known manifestation of the chronic pulmonary graft-versus-host disease(GVHD) after allogeneic hematopoietic stem cell transplantation (HSCT). The pathophysiology of BO is, however, poorly known. The available data strongly support the role of respiratory viruses, in particular paramyxoviruses (parainfluenzae virus (PIV), respiratory syncytial virus, metapneumovirus). It is likely that the alloimmune response triggered by the respiratory virus is inadequate and leads to the peribronchiolar fibrotic process. The objective is to analyze the kinetics of profiles of the blood and respiratory host responses resulting from a high or low parainfluenza respiratory infection, in order to evaluate if the occurrence of a BO is associated with a specific signature We will evaluate the predictive signature of a BO after a parainfluenza virus infection by characterizing the differences between the patients evolving and those not evolving to a BO at 2 months after the infection.