The need for a new animal model for chronic rejection after lung transplantation

The single most important cause of late mortality after lung transplantation is obliterative bronchiolitis (OB), clinically characterized by a decrease in lung function and morphologically by characteristic changes. Recently, new insights into its pathogenesis have been acquired: risk factors have been identified and the use of azithromycin showed a dichotomy with at least 2 different phenotypes of bronchiolitis obliterans syndrome (BOS). It is clear that a good animal model is indispensable to further dissect and unravel the pathogenesis of BOS. Many animal models have been developed to study BOS but, so far, none of these models truly mimics the human situation. Looking at the definition of BOS, a good animal model implies histological OB lesions, possibility to measure lung function, and airway inflammation. This review sought to discuss, including pros and cons, all potential animal models that have been developed to study OB/BOS. It has become clear that a new animal model is needed; recent developments using an orthotopic mouse lung transplantation model may offer the answer because it mimics the human situation. The genetic variants among this species may open new perspectives for research into the pathogenesis of OB/BOS.