Glucocorticoid administration accelerates mortality of pneumovirus-infected mice

The use of glucocorticoids for the treatment of symptoms associated with re spiratory syncytial virus (RSV) infection has been questioned. To evaluate the sequelae of glucocorticoid administration in the setting of pneumovirus infection in vivo, hydrocortisone was administered to mice infected with p neumonia virus of mice (PVM), a pneumovirus and natural rodent pathogen tha t is closely related to RSV and replicates the signs and symptoms of severe human RSV infection. Results showed that hydrocortisone spared the pulmona ry neutrophilia but resulted in ablation of the pulmonary eosinophilia, des pite continued production of the relevant chemoattractant, macrophage infla mmatory protein-1 alpha. Hydrocortisone also led to diminished production o f inducible nitric oxide synthase and accumulation of reactive nitrogen spe cies in lung tissue and bronchoalveolar lavage fluid and diminished lymphoc yte recruitment. PVM-infected mice responded to hydrocortisone with enhance d viral replication and accelerated mortality. These results suggest severa l mechanisms to explain why glucocorticoid therapy may be of limited benefi t in the overall picture of pneumovirus infection.