MicroRNA210 regulated brain pericyte dysfunction exacerbates hypoxic-ischemic brain injury in neonatal mice
Background While the role of pericytes in blood-brain barrier (BBB) disruption and neuroinflammation is well-established in adult neurological disorders, their contribution to neonatal brain injury is largely unexplored. Here, we investigated the role of brain pericytes in hypoxic-ischemic (HI) brain injury in the developing brain, with a particular focus on the regulatory role of pericyte-derived microRNA210 (miR210) in pericyte dysfunction.  Methods HI brain injury was induced on postnatal day 9 transgenic mice, including Atp13a5-tdTomato brain pericyte reporter mice, pericyte-specific diphtheria toxin receptor mice, miR210 knockout mice, and wild-type controls. Post-injury assessments include brain infarct, brain edema, BBB permeability, ELISA, western blotting, immunostaining, and neurological function test. BBB-associated cells, including pericytes and endothelial cells, were isolated from mouse brain using an immunomagnetic approach. RNA sequencing analysis was conducted to examine transcriptomic changes in pericytes after HI. To investigate the regulatory role of miR210 in pericyte dysfunction and its underlying mechanisms, primary pericytes were transfected with miR210 mimic or negative control, followed by oxygen-glucose deprivation. Transfected cells were also treated with either interleukin 1 type 1 receptor neutralizing antibody or recombinant interleukin 1 type 2 receptor chimera protein. Post-assays included RT-qPCR, immunostaining and cell viability assay. Student's t test or one-way ANOVA followed by Bonferroni test was used, as appropriate.  Results HI resulted in a time-dependent loss of pericytes in pericyte reporter mouse pups. Ablation of brain pericytes exacerbated BBB disruption and HI brain injury in neonatal brain. miR210 deletion mitigated brain pericyte loss and BBB leakage post-HI. Transcriptomic analysis revealed that HI-induced pericyte dysfunction was associated with upregulated genes enriched in biological processes such as “cellular response to interleukin 1”. miR210 knockout suppressed the expression of proinflammatory markers such as Il1r1. Mechanistically, miR210 overexpression increased proinflammatory cytokine levels and promoted pericyte cell death under oxygen-glucose deprivation, effects that were reversed by IL1R1 blockade. Importantly, brain pericyte-specific miR210 deletion preserved pericyte viability and BBB integrity, and provided neuroprotection after HI.  Conclusions These findings underscore the critical role of brain pericytes in BBB function in the developing brain and identify miR210 as a central regulator of pericyte dysfunction following neonatal HI brain injury. Overall design: RNA-seq analysis of isolated PDGFRbeta-positive cells from wildtype and microRNA210 knockout mice 24 hours after neonatal hypoxic-ischemic brain injury