Hyperoxia-activated circulating extracellular vesicles induce lung and brain injury in neonatal rats

Abstract

Hyperoxia-induced lung injury plays a key role in the development of bronchopulmonary dysplasia (BPD), characterized by inflammatory injury and impaired lung development in preterm infants. Although BPD is a predictor of poor neurodevelopmental outcomes, currently it is uncertain how lung injury contributes to brain injury in preterm infants. Extracellular vesicles (EVs) are a heterogeneous group of cell-derived membranous structures that regulate intercellular and inter-organ communications. Gasdermin D (GSDMD) has emerged as a key executor of inflammasome-mediated cell death and inflammation. In this study, we utilized a neonatal rat model of BPD to assess if hyperoxia stimulates lung release of circulating EVs and if these EVs induce lung and brain injury. We found that hyperoxia-exposed rats had elevated numbers of plasma-derived EVs compared to rats maintained in room air. These EVs also had increased cargos of surfactant protein C, a marker of type II alveolar epithelial cells (AEC), and the active (p30) form of GSDMD. When these EVs were adoptively transferred into normal newborn rats via intravenous injection, they were taken up both by lung and brain tissues. Moreover, EVs from hyperoxic animals induced not only the pathological hallmarks of BPD, but also brain inflammatory injury in recipient rats, as well as inducing cell death in cultured pulmonary vascular endothelial cells and neural stem cells (NSC). Similarly, hyperoxia-exposed cultured AEC-like cells released EVs that also contained increased GSDMD-p30 and these EVs induced pyroptotic cell death in NSC. Overall, these data indicate that hyperoxia-activated circulating EVs mediate a lung to brain crosstalk resulting in brain injury and suggest a mechanism that links lung injury and neurodevelopmental impairment in BPD infants.

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

“…EVs have been implicated in physiological and pathological communication between cells inside the same organ and between distant organs [ 9 , 13 ]. EVs can be classified according to their size, production mechanisms, and contents [ 34 ].…”

“…In traumatic brain injury, EVs have been shown to contain inflammasome proteins, whose activation can lead to acute lung injury [ 12 ]. More recently, we have shown that circulating EVs from newborn rats exposed to hyperoxia contain inflammasome proteins that can induce lung and brain inflammation when transfected into normal animals [ 13 ]. These exosomes also contained gasdermin D (GSDMD)—a molecule downstream from caspase-1—that is the effector of pyroptosis.…”

Extracellular vesicles in the pathogenesis and treatment of acute lung injury

“…For example, plasma exosomes of patients with burn injury are enriched with the S100 calcium binding protein A9 (S100A9), which inhibits the expression of zonula occludens-1 (ZO-1) and occludin, and activates the p38 MAPK signaling pathway in human pulmonary microvascular endothelial cells (HPMECs), ultimately leading to the disruption of the tight junctions and endothelial barrier [ 81 ]. Similarly, plasma EVs of hyperoxia-exposed rats revealed increased levels of surfactant protein C and GSDMD-p30, and their injection into new-born rats induced inflammatory injury and cell death in pulmonary vascular endothelial cells [ 85 ].…”

Perinatal Hyperoxia and Developmental Consequences on the Lung-Brain Axis

“…Furthermore, increased proinflammatory cytokines and decreased VEGF expression in lung tissues correlated with reduced brain weight, supporting the hypothesis that lung injury may aggravate adverse neurodevelopmental outcome [ 45 ]. A recent study revealed that extracellular vesicles/exosomes released from AECII cells in hyperoxia-injured lungs induced lung and brain injury when adoptively transferred into naïve neonatal rats [ 46 ]. The authors suggested that these extracellular vesicles/exosomes may enter the circulation, subsequently cross the BBB, and induce inflammatory brain injury [ 46 ].…”

“…A recent study revealed that extracellular vesicles/exosomes released from AECII cells in hyperoxia-injured lungs induced lung and brain injury when adoptively transferred into naïve neonatal rats [ 46 ]. The authors suggested that these extracellular vesicles/exosomes may enter the circulation, subsequently cross the BBB, and induce inflammatory brain injury [ 46 ]. These studies support the hypothesis of a detrimental interaction between lung and brain injury caused by hyperoxia.…”