TGF-beta prevents eosinophilic lung disease but impairs pathogen clearance.

Respiratory infections are the third leading cause of death worldwide. Complications arise directly as a consequence of pathogen replication or indirectly due to aberrant or excessive immune responses. In the following report, we evaluate the efficacy, in a murine model, of nasally delivered DNA encoding TGF-beta1 to suppress immunopathology in response to a variety of infectious agents. A single nasal administration suppressed lymphocyte responses to Cryptococcus neoformans, influenza virus and respiratory syncytial virus. The suppression did not depend on the phenotype of the responding T cell, since both Th1 and Th2 responses were affected. During Th2-inducing infection, pulmonary eosinophilic responses were significantly suppressed. In all cases, however, suppressed immunity correlated with increased susceptibility to infection. We conclude that nasal TGF-beta treatment could be used to prevent pulmonary, pathogen-driven eosinophilic disease, although anti-pathogen strategies will need to be administered concordantly.