Researcher(s)
- Sudha Anilkumar, Biomedical Engineering, University of Delaware
Faculty Mentor(s)
- Elizabeth Wright-Jin, Neuroscience, University of Delaware
Abstract
Occurring in 1.5 per 1000 live births, hypoxic ischemic encephalopathy (HIE) is a leading cause of death and long term disability in neonates. HIE is denoted by prolonged lack of oxygen to the brain, triggering an inflammatory response mediated by microglia, the primary immune cells of the central nervous system. Neonatal HIE is heavily linked with maternal immune activation: newborns exposed to maternal infection during gestation are 8 times more likely to be diagnosed with HIE. At present, standard animal models are inconsistent with clinical HIE with respect to patterns of brain injury and adult outcomes. Our novel two-hit mouse model of HIE first exposes the fetus to maternal immune activation via lipopolysaccharide injections in late gestation followed by hypoxia at postnatal (P) day 6 to better mimic the pathophysiology of the condition.
In this study, the inflammatory phenotype of our HIE model was characterized at two time points (P7 and P14) via transcriptional analysis. Bulk RNA sequencing of microglia at P14 was performed on HIE and saline/normoxia controls. Gene set enrichment analysis revealed upregulation of TNF signaling via NF-kB in HIE microglia, indicating activation of pro-inflammatory cytokines within the model. Real time qPCR was conducted on brain hemispheres at P7 and P14 to establish system-wide expression patterns for selected pro and anti inflammatory cytokines. At P7, one day post hypoxic injury, pro and anti inflammatory cytokines were upregulated in comparison to the saline/normoxia control, representing the crosstalk between inflammatory signaling typical in HIE. By P14, both types of cytokines were downregulated, demonstrative of a recovery phase. Identified cytokine trends were comparable to those found in neonatal HIE patients, validating the clinical relevance of our model. Therefore, the study signifies the scope for the model’s utility in elucidating the disease mechanism and assessing possible remediations.