Up-Regulation of miR-9-5p Inhibits Hypoxia-Ischemia Brain Damage Through the DDIT4-Mediated Autophagy Pathways in Neonatal Mice

MiR-4472 serves as a potential biomarker for hypoxic-ischemic encephalopathy and promotes neuronal death as well as hypoxic-ischemic brain damage in neonatal rats by targeting MEF2D

BACKGROUND

Hypoxic-ischemic encephalopathy (HIE) is a predominant cause in neonatal mortality and long-term neurological impairment. Accumulating evidence underscores the pivotal involvement of microRNAs (miRNAs) in HIE. Our prior miRNA microarray analysis revealed elevated miR-4472 levels in plasma from HIE newborns. However, the diagnostic potential of miR-4472 for HIE and its mechanistic contributions to disease progression remain to be elucidated.

METHODS

We collected plasma samples from HIE and healthy newborns, qRT-PCR and receiver operating characteristic (ROC) curve analyses were employed to evaluate miR-4472 expression and diagnostic performance, respectively. An in vitro HIE model was established using oxygen-glucose deprivation and reperfusion (OGD/R)-treated SH-SY5Y cells, while an in vivo HIE model was generated by subjecting seven days old male SD rats to carotid artery ligation followed by hypoxia. Neurological function in HIE neonatal rats was assessed using the Zea-Longa scoring system and Morris Water Maze tests, whereas brain tissue pathology and apoptosis were analyzed through HE staining and TUNEL assays, respectively. The targeting relationship between miR-4472 and MEF2D was validated via western blotting and dual-luciferase reporter assays. CCK-8 and Annexin V-FITC/PI staining were utilized to elucidate the effects of miR-4472 on SH-SY5Y cell viability and apoptosis through MEF2D. ELISA and commercial kits were used to quantify inflammatory factors, ROS, and MDA levels.

RESULTS

Our study demonstrated that miR-4472 was significantly elevated in plasma from HIE newborns, OGD/R-treated SH-SY5Y cells, and brain tissue of HIE rats, with higher levels observed in moderate-to-severe cases compared to mild HIE, the area under curve (AUC) of miR-4472 for HIE diagnosis reaching 0.958. Inhibition of miR-4472 restored cell viability and reduced apoptosis in OGD/R-treated SH-SY5Y cells, improved neurological function and ameliorated brain damage in HIE rats. Mechanistically, miR-4472 directly targets and suppresses MEF2D expression, thereby increasing ROS and MDA levels, inducing the expression and release of IL-6, TNF-α, and IL-1β. Intervention with MEF2D effectively antagonized the effects of miR-4472 in HIE.

CONCLUSION

This study demonstrates that plasma miR-4472 serves as a potential diagnostic biomarker for HIE and promotes its pathological progression by targeting MEF2D.

Liposome-loaded miR-34c-5p attenuates apoptosis and oxidative stress following hypoxia-ischemia brain damage in neonatal mice by targeting Arhgap26

Neonatal hypoxia-ischemia (HI) brain injury is considered a major cause of neonatal mortality and chronic disease morbidity worldwide. Despite its clinical importance, therapeutic options for HI injury remain limited. Here we demonstrated that miR-34c-5p expression peaks at postnatal day 10 in mice. Meanwhile, the miR-34c-5p levels in the lesioned cortex decreased following HI insult in neonatal mice. miR-34c-5p overexpression confers neuroprotective effects by attenuating brain injury and ROS production. These protective mechanisms were mediated through the inhibition of caspase 3 activation, suppression of microglial activation, and downregulation of pro-inflammatory cytokines in the injured cortex. In contrast, miR-34c-5p downregulation markedly aggravated the infarct area after HI injury. Additionally, miR-34c-5p overexpression improved short-term motor coordination and long-term neurological outcomes, including locomotor activity, learning, and memory functions, which were associated with upregulated synaptic protein expression. Importantly, we developed a non-invasive intranasal delivery system using liposome-encapsulated miR-34c-5p mimics, which significantly ameliorated brain injury at 3 days post-HI. Mechanistic studies revealed that miR-34c-5p directly targets the 3' untranslated region of GTPase activating protein 26 (Arhgap26). In conclusion, we identified a non-invasive method for successfully delivering miR-34c-5p to improve functional recovery after HI insult by targeting Arhgap26.

Liposomes-Loaded miR-9-5p Alleviated Hypoxia-Ischemia-Induced Mitochondrial Oxidative Stress by Targeting ZBTB20 to Inhibiting Nrf2/Keap1 Interaction in Neonatal Mice

Aims: Hypoxia ischemia (HI) is a leading cause of cerebral palsy and long-term neurological sequelae in infants. Given that mitochondrial dysfunction in neurons contributes to HI brain damage, this study aimed to investigate the regulatory role of miR-9-5p in mitochondrial function following HI injury. Results: Overexpression of miR-9-5p in HI mice or H2O2-exposed PC12 cells suppressed neuronal injury, associated with increased mitochondrial copy number, normalizing mitochondrial membrane potential, improved nuclear factor-erythroid factor 2-related factor 2 (Nrf2) activation, and downregulation of Keap1. This was mediated, in part, through the ability of this miR-9-5p to bind and regulate the transcriptional activity of zinc finger and BTB domain-containing protein 20 (ZBTB20). Further study suggested that the knockdown of ZBTB20 exerts neuroprotection by inhibiting Nrf2/Keap1 interaction to promote the translocation of Nrf2 from the cytoplasm to the nucleus and the consequent expression of antioxidant proteins. Notably, the protective effects of miR-9-5p overexpression against HI-induced mitochondrial damage were reversed by the Nrf2 inhibitor ML385. Finally, the utilization of liposomes for the delivery of miR-9-5p (miR-9-5p@Lip) presents a promising therapeutic strategy for the treatment of HI injury. Innovation: miR-9-5p is a potential therapeutic agent for ischemic stroke through its modulation of the ZBTB20/Nrf2/Keap1 signaling pathway, influencing mitochondrial function and antioxidant response. Furthermore, the use of liposomal delivery for miR-9-5p offers a promising therapeutic strategy for HI injury. Conclusion: Overexpression of miR-9-5p protects against cerebral HI injury by modulating mitochondrial function through the ZBTB20/Nrf2/Keap1 signaling pathway. Antioxid. Redox Signal. 42, 512-528. [Figure: see text].

Engineered Extracellular Vesicles Loaded with MiR-100-5p Antagonist Selectively Target the Lesioned Region to Promote Recovery from Brain Damage

Hypoxic-ischemic (HI) brain damage poses a high risk of death or lifelong disability, yet effective treatments remain elusive. Here, we demonstrated that miR-100-5p levels in the lesioned cortex increased after HI insult in neonatal mice. Knockdown of miR-100-5p expression in the brain attenuated brain injury and promoted functional recovery, through inhibiting the cleaved-caspase-3 level, microglia activation, and the release of proinflammation cytokines following HI injury. Engineered extracellular vesicles (EVs) containing neuron-targeting rabies virus glycoprotein (RVG) and miR-100-5p antagonists (RVG-EVs-Antagomir) selectively targeted brain lesions and reduced miR-100-5p levels after intranasal delivery. Both pre- and post-HI administration showed therapeutic benefits. Mechanistically, we identified protein phosphatase 3 catalytic subunit alpha (Ppp3ca) as a novel candidate target gene of miR-100-5p, inhibiting c-Fos expression and neuronal apoptosis following HI insult. In conclusion, our non-invasive method using engineered EVs to deliver miR-100-5p antagomirs to the brain significantly improves functional recovery after HI injury by targeting Ppp3ca to suppress neuronal apoptosis.

M2 Microglia-Derived Exosomes Protect Against Glutamate-Induced HT22 Cell Injury via Exosomal miR-124-3p

As one of the most serious complications of sepsis, sepsis-associated encephalopathy has not been effectively treated or prevented. Exosomes, as a new therapeutic method, play a protective role in neurodegenerative diseases, stroke and traumatic brain injury in recent years. The purpose of this study was to investigate the role of exosomes in glutamate (Glu)-induced neuronal injury, and to explore its mechanism, providing new ideas for the treatment of sepsis-associated encephalopathy. The neuron damage model induced by Glu was established, and its metabolomics was analyzed and identified. BV2 cells were induced to differentiate into M1 and M2 subtypes. After the exosomes from both M1-BV2 cells and M2-BV2 cells were collected, exosome morphological identification was performed by transmission electron microscopy and exosome-specific markers were also detected. These exosomes were then cocultured with HT22 cells. CCK-8 method and LDH kit were used to detect cell viability and toxicity. Cell apoptosis, mitochondrial membrane potential and ROS content were respectively detected by flow cytometry, JC-1 assay and DCFH-DA assay. MiR-124-3p expression level was detected by qRT-PCR and Western blot. Bioinformatics analysis and luciferase reporter assay predicted and verified the relationship between miR-124-3p and ROCK1 or ROCK2. Through metabolomics, 81 different metabolites were found, including fructose, GABA, 2, 4-diaminobutyric acid, etc. The enrichment analysis of differential metabolites showed that they were mainly enriched in glutathione metabolism, glycine and serine metabolism, and urea cycle. M2 microglia-derived exosomes could reduce the apoptosis, decrease the accumulation of ROS, restore the mitochondrial membrane potential and the anti-oxidative stress ability in HT22 cells induced by Glu. It was also found that the protective effect of miR-124-3p mimic on neurons was comparable to that of M2-EXOs. Additionally, M2-EXOs might carry miR-124-3p to target ROCK1 and ROCK2 in neurons, affecting ROCK/PTEN/AKT/mTOR signaling pathway, and then reducing Glu-induced neuronal apoptosis. M2 microglia-derived exosomes may protect HT22 cells against Glu-induced injury by transferring miR-124-3p into HT22 cells, with ROCK being a target gene for miR-124-3p.