Anti-inflammatory roles of type I interferon signaling in the lung

Excessive or persistent inflammation may have detrimental effects on lung structure and function. Currently, our understanding of conserved host mechanisms that control the inflammatory response remains incompletely understood. In this study, we investigated the role of type I interferon signaling in the inflammatory response against diverse clinically relevant stimuli. Using mice deficient in type I interferon signaling (IFNAR1^-/-), we demonstrate that the absence of interferon signaling resulted in a robust and persistent inflammatory response against Pseudomonas aeruginosa, lipopolysaccharide, and chemotherapeutic agent bleomycin. The elevated inflammatory response in IFNAR1^-/- mice was manifested as elevated myeloid cells, such as macrophages and neutrophils, in the bronchoalveolar lavage. The inflammatory cell response in the IFNAR1^-/- mice persisted to 14 days and there is impaired recovery and fibrotic remodeling of the lung in IFNAR1^-/- mice after bleomycin injury. In the Pseudomonas infection model, the elevated inflammatory cell response led to improved bacterial clearance in IFNAR1^-/- mice, although there was similar lung injury and survival. We performed RNA sequencing of lung tissue in wild-type and IFNAR1^-/- mice after LPS and bleomycin injury. Our unbiased analysis identified differentially expressed genes between IFNAR1^-/- and wild-type mice, including previously unknown regulation of nucleotide-binding oligomerization domain (NOD)-like receptor signaling, retinoic acid-inducible gene-I (RIG-I) signaling, and necroptosis pathway by type I interferon signaling in both models. These data provide novel insights into the conserved anti-inflammatory mechanisms of the type I interferon signaling.NEW & NOTEWORTHY Type I interferons are known for their antiviral activities. In this study, we demonstrate a conserved anti-inflammatory role of type I interferon signaling against diverse stimuli in the lung. We show that exacerbated inflammatory response in the absence of type I interferon signaling has both acute and chronic consequences in the lung including structural changes.