Circulating extracellular vesicles activate the pyroptosis pathway in the brain following ventilation-induced lung injury

Abstract

Background Mechanical ventilation of preterm newborns causes lung injury and is associated with poor neurodevelopmental outcomes. However, the mechanistic links between ventilation-induced lung injury (VILI) and brain injury is not well defined. Since circulating extracellular vesicles (EVs) are known to link distant organs by transferring their cargos, we hypothesized that EVs mediate inflammatory brain injury associated with VILI. Methods Neonatal rats were mechanically ventilated with low (10 mL/kg) or high (25 mL/kg) tidal volume for 1 h on post-natal day 7 followed by recovery for 2 weeks. Exosomes were isolated from the plasma of these rats and adoptively transferred into normal newborn rats. We assessed the effect of mechanical ventilation or exosome transfer on brain inflammation and activation of the pyroptosis pathway by western blot and histology. Results Injurious mechanical ventilation induced similar markers of inflammation and pyroptosis, such as increased IL-1β and activated caspase-1/gasdermin D (GSDMD) in both lung and brain, in addition to inducing microglial activation and cell death in the brain. Isolated EVs were enriched for the exosomal markers CD9 and CD81, suggesting enrichment for exosomes. EVs isolated from neonatal rats with VILI had increased caspase-1 but not GSDMD. Adoptive transfer of these EVs led to neuroinflammation with microglial activation and activation of caspase-1 and GSDMD in the brain similar to that observed in neonatal rats that were mechanically ventilated. Conclusions These findings suggest that circulating EVs can contribute to the brain injury and poor neurodevelopmental outcomes in preterm infants with VILI through activation of GSDMD.

GSDMD deficiency ameliorates hyperoxia-induced BPD and ROP in neonatal mice

“…Many studies have demonstrated a critical role for GSDMD in regulating pyroptosis and inflammation in various adult diseases. However, there are no reports on the role of GSDMD in neonatal lung and retinal injury in preterm infants, but recent studies from our laboratory have highlighted a critical role for GSDMD in hyperoxia-indued and mechanical ventilation-associated neonatal lung and brain injury in rodent models 15 , 16 . We showed that GSDMD is activated by hyperoxia in the lungs and brains of neonatal mice and that treatment with a pharmacological inhibitor of GSDMD attenuated hyperoxia-induced BPD-like pathology and brain injury 15 .…”

Neuroinflammation of traumatic brain injury: Roles of extracellular vesicles

“…Injection of these EVs aggravates neuroinflammation by activating glial cells and the NF-κB signaling pathway and releasing pro-inflammatory cytokines ( 186 ). Circulating EVs from ALI lead to the activation of microglia and the pyroptosis pathway, which worsen neuroinflammation ( 156 ). Collectively, these studies show that circulating EVs play a crucial role in neuroinflammation.…”

Extracellular vesicles, from the pathogenesis to the therapy of neurodegenerative diseases

“…Intestinal epithelial cells have been reported to release EVs to induce IL-1β-mediated neuronal injury in sepsis-associated encephalopathy, which launches long-term cognitive deficits and neurodegeneration [ 163 ]. Moreover, ventilation-induced lung injury causes lung inflammation, leading to selective loading of caspase-1 into lung-derived EVs [ 164 ]. Caspase-1-enriched peripheral EVs induce microglial activation and cell pyroptosis in the brain, revealing circulating EVs as a pathogenic factor of NDs [ 164 ].…”

“…Moreover, ventilation-induced lung injury causes lung inflammation, leading to selective loading of caspase-1 into lung-derived EVs [ 164 ]. Caspase-1-enriched peripheral EVs induce microglial activation and cell pyroptosis in the brain, revealing circulating EVs as a pathogenic factor of NDs [ 164 ].…”