Non-canonical Oncostatin M Signaling Provides Protection during Respiratory Viral and Bacterial infections

Pneumonia remains a major global health burden, highlighting the need for host-directed therapies to complement antimicrobial treatment. Here, we identify Oncostatin M (OSM) as a critical regulator of pulmonary host responses during influenza and bacterial pneumonia. Loss of OSM shifted lung macrophages toward a pro-inflammatory phenotype during influenza infection and exacerbated lung injury during bacterial pneumonia, demonstrating an essential role for OSM in limiting immunopathology. Unexpectedly, OSM induced Signal Transducer and Activator of Transcription 3 (STAT3) activation in the absence of the canonical OSM receptor subunit OSMr{beta}, revealing previously unrecognized non-canonical OSM signaling in the mouse lungs. Consistent with this finding, loss of OSMr{beta} did not phenocopy the severe disease observed with loss of OSM. Together, these findings identify OSM as a key regulator of pulmonary immunity and reveal unexpected complexity in OSM signaling during pneumonia.