Farrerol Alleviates Hypoxic-Ischemic Encephalopathy by Inhibiting Ferroptosis in Neonatal Rats via the Nrf2 Pathway

The IRE1-XBP1 Axis Regulates NLRP3 Inflammasome-Mediated Microglia Activation in Hypoxic Ischemic Encephalopathy

Hypoxic-ischemic encephalopathy (HIE) is a perinatal injury caused by cerebral hypoxia and reduced blood perfusion. Microglia activation-induced neuroinflammatory injury is a leading cause of neuron loss and brain injury. Efficient treatment strategies are still required further investigation. Our study is aimed to investigate the role of IRE1-XBP1 inhibitor 4μ8С in HIE. Rat pups (7 d) were used to establish HIE model using unilateral carotid artery ligation and hypoxia. A series of experiments including Western blot, Morris water maze test, TTC staining, RT-qPCR, TUNEL staining, and immunofluorescence staining were operated to evaluate the role of 4μ8С in HIE. 4μ8С treatment effectively reduced phosphorylated IRElα and XBP1 protein levels. 4μ8С treatment improves cognition and learning abilities of HIE rats. 4μ8С treatment alleviated brain infarction and cell apoptosis in HIE rats. 4μ8С treatment inhibited NLRP3 inflammasome activation-mediated microglia activation and inflammatory response. In conclusion, 4μ8С suppressed microglia and NLRP3 inflammasome activation by inactivating IRE1/XBP1 axis during HIE development, which revealed IRE1α inhibition as a novel mechanism for neuron protection.

The mechanism of hypoxia-inducible factor-1α enhancing the transcriptional activity of transferrin ferroportin 1 and regulating the Nrf2/HO-1 pathway in ferroptosis after cerebral ischemic injury

Cerebral ischemic/reperfusion (I/R) injury has high disability and morbidity. Hypoxia-inducible factor-1α (HIF-1α) may enhance the transcriptional activity of transferrin ferroportin 1 (FPN1) in regulating ferroptosis after cerebral ischemia injury (CII). In this study, cerebral I/R injury rat models were established and treated with pcDNA3.1-HIF-1α, pcDNA3.1-NC lentiviral plasmid, or ML385 (a specific Nrf2 inhibitor). Additionally, oxygen-glucose deprivation/reoxygenation (OGD/R) exposed PC12 cells were used as an in vitro model of cerebral ischemia and treated with pcDNA3.1-HIF-1α, si-FPN1, or ML385. The results elicited that cerebral I/R injury rats exhibited increased Longa scores, TUNEL and NeuN co-positive cells, Fe2+ concentration, ROS and HIF-1α levels, and MDA content, while reduced cell density and number, GSH content, and GPX4 protein level. Morphologically abnormal and disordered hippocampal neurons were also observed in CII rats. HIF-1α inhibited brain neuron ferroptosis and ameliorated I/R injury. HIF-1α alleviated OGD-induced PC12 cell ferroptosis. OGD/R decreased FPN1 protein level in PC12 cells, and HIF-1α enhanced FPN1 transcriptional activity. FPN1 knockdown reversed HIF-1α-mediated alleviation of OGD/R-induced ferroptosis. HIF-1α activated the Nrf2/HO-1 pathway by enhancing FPN1 expression and alleviating OGD/R-induced ferroptosis. Conjointly, HIF-1α enhanced the transcriptional activity of FPN1, activated the Nrf2/HO-1 pathway, and inhibited ferroptosis of brain neurons, thereby improving I/R injury in CII rats.

Nuclear factor erythroid 2-related factor-mediated signaling alleviates ferroptosis during cerebral ischemia-reperfusion injury

Cardiac arrest (CA) is a significant challenge for emergency physicians worldwide and leads to increased morbidity and mortality rates. The poor prognosis of CA primarily stems from the complexity and irreversibility of cerebral ischemia-reperfusion injury (CIRI). Ferroptosis, a form of programmed cell death characterized by iron overload and lipid peroxidation, plays a crucial role in the progression and treatment of CIRI. In this review, we highlight the mechanisms of ferroptosis within the context of CIRI, focusing on its role as a key contributor to neuronal damage and dysfunction post-CA. We explore the crucial involvement of the nuclear factor erythroid 2-related factor (Nrf2)-mediated signaling pathway in modulating ferroptosis-associated processes during CIRI. Through comprehensive analysis of the regulatory role of Nrf2 in the cellular responses to oxidative stress, we highlight its potential as a therapeutic target for mitigating ferroptotic cell death and improving the neurological prognosis of patients experiencing CA. Furthermore, we discuss interventions targeting the Kelch-like ECH-associated protein 1/Nrf2/antioxidant response element pathway, including the use of traditional Chinese medicine and Western medicine, which demonstrate potential for attenuating ferroptosis and preserving neuronal function in CIRI. Owing to the limitations in the safety, specificity, and effectiveness of Nrf2-targeted drugs, as well as the technical difficulties and ethical constraints in obtaining the results related to the brain pathological examination of patients, most of the studies focusing on Nrf2-related regulation of ferroptosis in CIRI are still in the basic research stage. Overall, this review aims to provide a comprehensive understanding of the mechanisms underlying ferroptosis in CIRI, offering insights into novel therapeutics aimed at enhancing the clinical outcomes of patients with CA.

A ferroptosis-related ceRNA network for investigating the molecular mechanisms and the treatment of neonatal hypoxic-ischemic encephalopathy

Background

Neonatal hypoxic-ischemic brain damage (HIBD) is a clinical syndrome causing brain injury in newborns with obscure etiology. Increasing evidence suggests that ferroptosis plays a role in HIBD. This study aimed to clarify the key ferroptosis-related genes (FRGs) of HIBD, construct a long non-coding RNA-microRNA-messenger RNA (lncRNA-miRNA-mRNA) network, and further investigate the pathogenesis of HIBD.

Methods

Gene expression data were downloaded from the Gene Expression Omnibus and FerrDb databases. The differentially expressed lncRNAs and FRGs were screened, and the related miRNAs and mRNAs were predicted. The obtained mRNA was intersected with the differentially expressed FRGs (DE-FRGs) to identify the key DE-FRGs. Cell-type Identification by Estimating Relative Subsets of RNA Transcripts method was applied to analyze the immune cell infiltration level and the relationship between key genes and immune cells.

Results

Gene differential expression analysis revealed that 1,178 lncRNAs, 207 miRNAs, and 647 mRNAs were differentially expressed in the blood of HIBD patients in comparison to healthy controls. The correlations of the lncRNAs, miRNAs, and mRNAs lead to the establishment of a competing endogenous RNA (ceRNA) network associated with ferroptosis in HIBD. Further validation using an external dataset and quantitative real-time polymerase chain reaction (PCR) analysis of brain tissues from hypoxic-ischemic encephalopathy rats confirmed the expression patterns of three key genes, including HMOX1, MYCN, and QSOX1. Meanwhile, the three key genes were closely correlated with the infiltration of multiple immune cells and might affect the function of HIBD regulatory genes such as CPT2 and GCK. In addition, drug prediction suggested that four drugs, including cephaeline, emetine, mestranol, and sulmazole, might alleviate HIBD.

Conclusions

Our study established a ceRNA network, identified three key genes, and predicted four drugs that are associated with ferroptosis in HIBD, which provides new ideas for the investigation of the disease mechanisms and might facilitate the diagnosis and treatment of the disease.