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Updated: Jul 24, 2025
Neurobehavioral Assessments in a Mouse Model of Neonatal Hypoxic-ischemic Brain Injury
Published on: November 24, 2017
GSDMD gene knockout alleviates hyperoxia-induced hippocampal brain injury in neonatal mice
Naga Venkata Divya Challa1, Shaoyi Chen1, Huijun Yun1
1Department of Pediatrics/Division of Neonatology, Batchelor Children's Research Institute and Holtz Children's Hospital, University of Miami Miller School of Medicine, Miami, FL, United States.
Insights
Gasdermin D (GSDMD) knockout protected neonatal mice from hyperoxia-induced brain injury. GSDMD deficiency prevented inflammation, cell death, and altered gene expression in the developing brain.
Area of Science:
- Neuroscience
- Neonatal Research
- Inflammation Biology
Background:
- Neonatal hyperoxia is linked to brain injury and neurodevelopmental issues in preterm infants.
- Hyperoxia activates the brain's inflammasome pathway, specifically gasdermin D (GSDMD), a key mediator of pyroptotic cell death.
- Previous studies indicated GSDMD inhibition mitigates hyperoxia-induced brain injury in neonatal mice.
Approach:
- Newborn GSDMD knockout (KO) and wildtype (WT) mice were exposed to room air or hyperoxia (85% O2) from postnatal day 1 to 14.
- Hippocampal injury was assessed via immunohistology for microglial activation (AIF1), cell proliferation (Ki-67), and cell death (TUNEL assay).
- RNA sequencing identified transcriptional changes, with qRT-PCR confirming key gene expressions.
Key Points:
- Hyperoxia increased microglial activation, decreased cell proliferation, and elevated cell death in WT mice's hippocampi.
- GSDMD-KO mice showed resistance to hyperoxia, with no significant increases in AIF1+ or TUNEL+ cells, nor decreased proliferation.
- Hyperoxia altered numerous genes in WT mice related to neuronal/vascular development and glial differentiation; these changes were prevented by GSDMD-KO.
Conclusions:
- GSDMD knockout alleviates hyperoxia-induced inflammatory injury, cell death, and transcriptional alterations in the neonatal mouse hippocampus.
- GSDMD plays a critical pathogenic role in hyperoxia-induced preterm brain injury.
- Targeting GSDMD presents a potential therapeutic strategy for preventing and treating brain injury and neurodevelopmental deficits in preterm infants.
Abstract:
Background: Neonatal hyperoxia exposure is associated with brain injury and poor neurodevelopment outcomes in preterm infants. Our previous studies in neonatal rodent models have shown that hyperoxia stimulates the brain's inflammasome pathway, leading to the activation of gasdermin D (GSDMD), a key executor of pyroptotic inflammatory cell death. Moreover, we found inhibition of GSDMD activation attenuates hyperoxia-induced brain injury in neonatal mice. We hypothesized that GSDMD plays a pathogenic role in hyperoxia-induced neonatal brain injury and that GSDMD gene knockout (KO) will alleviate hyperoxia-induced brain injury. Methods: Newborn GSDMD knockout mice and their wildtype (WT) littermates were randomized within 24 h after birth to be exposed to room air or hyperoxia (85% O2) from postnatal day 1 to 14. Hippocampal brain inflammatory injury was assessed in brain sections by immunohistology for allograft inflammatory factor 1 (AIF1), a marker of microglial activation. Cell proliferation was evaluated by Ki-67 staining, and cell death was determined by TUNEL assay. RNA sequencing of the hippocampus was performed to identify the transcriptional effects of hyperoxia and GSDMD-KO, and qRT-PCR was performed to confirm some of the significantly regulated genes. Results: Hyperoxia-exposed WT mice had increased microglia consistent with activation, which was associated with decreased cell proliferation and increased cell death in the hippocampal area. Conversely, hyperoxia-exposed GSDMD-KO mice exhibited considerable resistance to hyperoxia as O2 exposure failed to increase either AIF1+ or TUNEL+ cell numbers, nor decrease cell proliferation. Hyperoxia exposure differentially regulated 258 genes in WT and only 16 in GSDMD-KO mice compared to room air- exposed WT and GSDMD-KO, respectively. Gene set enrichment analysis showed that in the WT brain, hyperoxia differentially regulated genes associated with neuronal and vascular development and differentiation, axonogenesis, glial cell differentiation, and core development pathways hypoxia-induced factor 1, and neuronal growth factor pathways. These changes were prevented by GSDMD-KO. Conclusion: GSDMD-KO alleviates hyperoxia-induced inflammatory injury, cell survival and death, and alterations of transcriptional gene expression of pathways involved in neuronal growth, development, and differentiation in the hippocampus of neonatal mice. This suggests that GSDMD plays a pathogenic role in preterm brain injury, and targeting GSDMD may be beneficial in preventing and treating brain injury and poor neurodevelopmental outcomes in preterm infants.
