IFN-λ Diminishes the Severity of Viral Bronchiolitis in Neonatal Mice by Limiting NADPH Oxidase–Induced PAD4-Independent NETosis

Abstract

Infants with attenuated type III IFN (IFN-λ) responses are at increased risk of severe lower respiratory tract infection (sLRI). The IL-28Rα–chain and IL-10Rβ–chain form a heterodimeric receptor complex, necessary for IFN-λ signaling. Therefore, to better understand the immunopathogenic mechanisms through which an IFN-λlo microenvironment predisposes to a sLRI, we inoculated neonatal wild-type and IL-28R–deficient (IL-28R−/−) mice with pneumonia virus of mice, a rodent-specific pneumovirus. Infected IL-28R−/− neonates displayed an early, pronounced, and persistent neutrophilia that was associated with enhanced reactive oxygen species (ROS) production, NETosis, and mucus hypersecretion. Targeted deletion of the IL-28R in neutrophils was sufficient to increase neutrophil activation, ROS production, NET formation, and mucus production in the airways. Inhibition of protein-arginine deiminase type 4 (PAD4), a regulator of NETosis, had no effect on myeloperoxidase expression, citrullinated histones, and the magnitude of the inflammatory response in the lungs of infected IL-28R−/− mice. In contrast, inhibition of ROS production decreased NET formation, cellular inflammation, and mucus hypersecretion. These data suggest that IFN-λ signaling in neutrophils dampens ROS-induced NETosis, limiting the magnitude of the inflammatory response and mucus production. Therapeutics that promote IFN-λ signaling may confer protection against sLRI.

Type I IFN signaling mediates NET release to promoteMycobacterium tuberculosisreplication and granuloma caseation

“…Histone citrullination by PAD enzymes is critical for the initial chromatin decondensation that allows for NETosis following most stimuli 58–60 , including during Mtb infection where pretreatment with the pan-PAD inhibitor Cl-amidine inhibited Mtb induced NETosis by human neutrophils 61 . PAD4 is the primary PAD enzyme expressed in neutrophils and has been shown to be essential for NETosis in response to a number of different stimuli 44, 52, 59, 60, 62, 63 including lipopolysaccharide, lipoteichoic acid, fungal zymosan, and TNFα However, NET formation in response to other stimuli, such as Klebsiella pneumoniae, Aspergillus fumigatus, rodent-specific pneumovirus, and influenza virus A/WSN/33/H1N1, occurs independent of PAD4 64–68 . To determine if Padi4 , the gene that encodes PAD4, is required for NETosis during Mtb infection, we infected WT and Padi4 -/- neutrophils with Mtb for 18 hours and monitored NETosis by fluorescent microscopy.…”

A maternal high-fat diet predisposes to infant lung disease via increased neutrophil-mediated IL-6 trans-signaling

“…All animal procedures were approved by the QIMR Berghofer MRI Animal Ethics Committee (approval number A1706-609M). Pneumonia virus of mice (PVM, strain J3666) was propagated as previously described (Sebina, Rashid et al 2022). A single dose of 10 plaque forming unit (PFU) of PVM in 10 µl or the same volume of vehicle (10%, v/v, FCS in DMEM; Gibco) was administered via the intra-nasal (i.n.)…”

IL-33-induced neutrophilic inflammation and NETosis underlie rhinovirus-triggered exacerbations of asthma

“…injection at −24, 12, 24 and 36 hours post exposure, as described previously. 41, 43 All experiments were approved by the QIMR Berghofer Animal Ethics Committee.…”