Upregulation of H3K27 Demethylase KDM6 During Respiratory Syncytial Virus Infection Enhances Proinflammatory Responses and Immunopathology.

Severe disease following respiratory syncytial virus (RSV) infection has been linked to enhanced proinflammatory cytokine production that promotes a Th2-type immune environment. Epigenetic regulation in immune cells following viral infection plays a role in the inflammatory response and may result from upregulation of key epigenetic modifiers. In this study, we show that RSV-infected bone marrow-derived dendritic cells (BMDC) as well as pulmonary dendritic cells (DC) from RSV-infected mice upregulated the expression of Kdm6b/Jmjd3 and Kdm6a/Utx, H3K27 demethylases. KDM6-specific chemical inhibition (GSK J4) in BMDC led to decreased production of chemokines and cytokines associated with the inflammatory response during RSV infection (i.e., CCL-2, CCL-3, CCL-5, IL-6) as well as decreased MHC class II and costimulatory marker (CD80/86) expression. RSV-infected BMDC treated with GSK J4 altered coactivation of T cell cytokine production to RSV as well as a primary OVA response. Airway sensitization of naive mice with RSV-infected BMDCs exacerbate a live challenge with RSV infection but was inhibited when BMDCs were treated with GSK J4 prior to sensitization. Finally, in vivo treatment with the KDM6 inhibitor, GSK J4, during RSV infection reduced inflammatory DC in the lungs along with IL-13 levels and overall inflammation. These results suggest that KDM6 expression in DC enhances proinflammatory innate cytokine production to promote an altered Th2 immune response following RSV infection that leads to more severe immunopathology.