The role of ferroptosis in endothelial cell dysfunction

Gualou-Xiebai herb pair ameliorate atherosclerosis in HFD-induced ApoE-/- mice and inhibit the ox-LDL-induced injury of HUVECs by regulating the Nrf2-mediated ferroptosis

ETHNOPHARMACOLOGICAL RELEVANCE

Atherosclerosis (AS) is a chronic vascular ailment characterized by inflammatory and lipid deposition in the arterial wall caused by endothelial injury. Ferroptosis is a novel type of cell death, and endothelial ferroptosis is a significant contributor to the progression of AS. Gualou-Xiebai (GLXB) is a renowned Chinese herb pair that serves a crucial function in treating AS. However, whether the underlying mechanism of GLXB plays a role in anti-atherosclerotic effects by inhibiting ferroptosis in endothelial cells has not been determined.

AIM OF THE STUDY

To explore the influence of GLXB on endothelial ferroptosis and determine its underlying mechanism of action in AS.

MATERIALS AND METHODS

In ApoE-/- mice, ultrasound was performed in mice fed a high-fat diet (HFD) for 12 weeks to assess the success of AS establishment. Then, ApoE-/- mice were treated with GLXB and Simvastatin (positive control) for 4 weeks. The effects of GLXB on AS pathology were assessed through aorta imaging and hematoxylin-eosin (HE) staining. To confirm the presence of ferroptosis, mitochondrial damage was observed using transmission electron microscope (TEM), along with analysis of free iron and lipid peroxidation levels. In vitro: ox-LDL-induced human vascular endothelial cells (HUVECs) injury and treated with GLXB, the ferroptosis inducer Erastin and an Nrf2 inhibitor ML385. Cell viability was evaluated using the CCK-8 assay in all groups. Flow cytometry was employed to detect lipid peroxidation and intracellular ferrous iron levels. Immunofluorescence staining microscopy verified Nrf2 nuclear translocation. Protein expression were measured by Western blot analysis.

RESULTS

GLXB improved atherosclerotic aortic lesions and vascular plaques. GLXB inhibited endothelial injury in the aorta by decreasing the levels of inflammatory factors and adhesion factors, and by decreasing the shedding of endothelial cells. GLXB suppressed ferroptosis in ApoE-/- mice by attenuating mitochondrial damage in ECs, increasing the levels of glutathione (GSH) and superoxide dismutase (SOD) in aortic tissues and down-regulating the levels of levels of lipid peroxide (LPO) and malondialdehyde (MDA). Interestingly, Erastin was used to demonstrate in vitro that GLXB inhibition of ferroptosis attenuated ox-LDL-induced injuring effects on HUVECs that were reversed by Erastin. Mechanistically, GLXB activates the Nrf2 signaling pathway to inhibit ferroptosis by increasing downstream anti-ferroptosis target proteins and promoting the interaction between Nrf2 and SLC7A11. More convincingly, ML385 (Nrf2 inhibitor) reversed the anti-ferroptosis effect of GLXB.

CONCLUSION

GLXB inhibits ferroptosis-mediated endothelial cell injury via activating the Nrf2 signaling pathway and further alleviates AS pathological damage.

Research progress on and molecular mechanism of vacuum sealing drainage in the treatment of diabetic foot ulcers

Diabetic foot ulcers (DFUs) are common chronic wounds and a common complication of diabetes. The foot is the main site of diabetic ulcers, which involve small and medium-sized arteries, peripheral nerves, and microcirculation, among others. DFUs are prone to coinfections and affect many diabetic patients. In recent years, interdisciplinary research combining medicine and material science has been increasing and has achieved significant clinical therapeutic effects, and the application of vacuum sealing drainage (VSD) in the treatment of DFUs is a typical representative of this progress, but the mechanism of action remains unclear. In this review, we integrated bioinformatics and literature and found that ferroptosis is an important signaling pathway through which VSD promotes the healing of DFUs and that System Xc-GSH-GPX4 and NAD(P)H-CoQ10-FSP1 are important axes in this signaling pathway, and we speculate that VSD is most likely to inhibit ferroptosis to promote DFU healing through the above axes. In addition, we found that some classical pathways, such as the TNF, NF-κB, and Wnt/β-catenin pathways, are also involved in the VSD-mediated promotion of DFU healing. We also compiled and reviewed the progress from clinical studies on VSD, and this information provides a reference for the study of VSD in the treatment of DFUs.

Targeting Ferroptosis: A Novel Strategy for the Treatment of Atherosclerosis

Since ferroptosis was reported in 2012, its application prospects in various diseases have been widely considered, initially as a treatment direction for tumors. Recent studies have shown that ferroptosis is closely related to the occurrence and development of atherosclerosis. The primary mechanism is to affect the occurrence and development of atherosclerosis through intracellular iron homeostasis, ROS and lipid peroxide production and metabolism, and a variety of intracellular signaling pathways. Inhibition of ferroptosis is effective in inhibiting the development of atherosclerosis, and it can bring a new direction for treating atherosclerosis. In this review, we discuss the mechanism of ferroptosis and focus on the relationship between ferroptosis and atherosclerosis, summarize the different types of ferroptosis inhibitors that have been widely studied, and discuss some issues worthy of attention in the treatment of atherosclerosis by targeting ferroptosis.

Thymosin β4 exerts cytoprotective function and attenuates liver injury in murine hepatic sinusoidal obstruction syndrome after hematopoietic stem cell transplantation

Hepatic sinusoidal obstruction syndrome (HSOS) is one of the life-threatening complications that may occur after hematopoietic stem cell transplantation (HSCT). Hepatic sinusoidal endothelial cells (HSECs) injury and liver fibrosis are key mechanisms of HSOS. Thymosin β4 (Tβ4) is an active polypeptide that functions in a variety of pathological and physiological states such as inflammation regulation, anti-apoptosis and anti-fibrosis. In this study, we found that Tβ4 can stimulate HSECs proliferation, migration and tube formation in vitro via activation of pro-survival signaling AKT (protein kinase B). In addition, Tβ4 resisted γ irradiation-induced HSECs growth arrest and apoptosis in parallel with upregulation of anti-apoptotic protein B-cell lymphoma-extra-large (Bcl-xL) and B-cell lymphoma-2 (Bcl-2), which may be associated with activation of AKT. More importantly, Tβ4 significantly inhibited irradiation-induced proinflammatory cytokines in parallel with negative regulation of TLR4/MyD88/NF-κB and MAPK p38. Meanwhile, Tβ4 reduced intracellular reactive oxygen species production and upregulated antioxidants in HSECs. Additionally, Tβ4 inhibited irradiation-induced activation of hepatic stellate cells via downregulation expression of fibrogenic markers α-SMA, PAI-1 and TGF-β. In a murine HSOS model, levels of circulating alanine aminotransferase, aspartate aminotransferase, total bilirubin, and pro-inflammatory cytokines IL-6, IL-1β and TNF-α were significantly reduced after administration of Tβ4 peptide; further, Tβ4 treatment successfully ameliorated HSECs injury, inflammatory damage and fibrosis of murine liver. Taken together, Tβ4 stimulates proliferation and angiogenesis of HSECs, exerts cytoprotective effect and attenuates liver injury in murine HSOS model, which could be a potential strategy to prevent and treat HSOS after HSCT.

COVID-19 Causes Ferroptosis and Oxidative Stress in Human Endothelial Cells

Oxidative stress and endothelial dysfunction have been shown to play crucial roles in the pathophysiology of COVID-19 (coronavirus disease 2019). On these grounds, we sought to investigate the impact of COVID-19 on lipid peroxidation and ferroptosis in human endothelial cells. We hypothesized that oxidative stress and lipid peroxidation induced by COVID-19 in endothelial cells could be linked to the disease outcome. Thus, we collected serum from COVID-19 patients on hospital admission, and we incubated these sera with human endothelial cells, comparing the effects on the generation of reactive oxygen species (ROS) and lipid peroxidation between patients who survived and patients who did not survive. We found that the serum from non-survivors significantly increased lipid peroxidation. Moreover, serum from non-survivors markedly regulated the expression levels of the main markers of ferroptosis, including GPX4, SLC7A11, FTH1, and SAT1, a response that was rescued by silencing TNFR1 on endothelial cells. Taken together, our data indicate that serum from patients who did not survive COVID-19 triggers lipid peroxidation in human endothelial cells.

Identification of ferroptosis-related genes in syncytiotrophoblast-derived extracellular vesicles of preeclampsia

Preeclampsia (PE), defined as new-onset hypertension and multi-organ systemic complication during pregnancy, is the leading cause of maternal and neonatal mortality and morbidity. With extracellular vesicles research progresses, current data refers to the possibility that ferroptosis may play a role in exosomal effects. Evidence has suggested that ferroptosis may contribute to the pathogenesis of preeclampsia by bioinformatics analyses. The purpose of the current study is to identify the potential ferroptosis-related genes in syncytiotrophoblast-derived extracellular vesicles (STB-EVs) of preeclampsia using bioinformatics analyses. Clinical characteristics and gene expression data of all samples were obtained from the NCBI GEO database. The differentially expressed mRNAs (DE-mRNAs) in STB-EVs of preeclampsia were screened and then were intersected with ferroptosis genes. Functional and pathway enrichment analyses of ferroptosis-related DE-mRNAs in STB-EVs were performed. Ferroptosis-related hub genes in STB-EVs were identified by Cytoscape plugin CytoHubba with a Degree algorithm using a protein-protein interaction network built constructed from the STRING database. The predictive performance of ferroptosis-related hub genes was determined by a univariate analysis of receiver operating characteristic (ROC). The miRNA-hub gene regulatory network was constructed using the miRwalk database. A total of 1976 DE-mRNAs in STB-EVs were identified and the most enriched item identified by gene set enrichment analysis was signaling by G Protein-Coupled Receptors (normalized enrichment score = 1.238). These DE-mRNAs obtained 26 ferroptosis-related DE-mRNAs. Ferroptosis-related DE-mRNAs of gene ontology terms and Encyclopedia of Genes and Genomes pathway enrichment analysis were enriched significantly in response to oxidative stress and ferroptosis. Five hub genes (ALB, NOX4, CDKN2A, TXNRD1, and CAV1) were found in the constructed protein-protein interaction network with ferroptosis-related DE-mRNAs and the areas under the ROC curves for ALB, NOX4, CDKN2A, TXNRD1, and CAV1 were 0.938 (CI: 0.815-1.000), 0.833 (CI: 0.612-1.000), 0.875 (CI: 0.704-1.000), 0.958 (CI: 0.862-1.000), and 0.854 (CI: 0.652-1.000) in univariate analysis of ROC. We constructed a regulatory network of miRNA-hub gene and the findings demonstrate that hsa-miR-26b-5p, hsa-miR-192-5p, hsa-miR-124-3p, hsa-miR-492, hsa-miR-34a-5p and hsa-miR-155-5p could regulate most hub genes. In this study, we identified several central genes closely related to ferroptosis in STB-EVs (ALB, NOX4, CDKN2A, TXNRD1, and CAV1) that are potential biomarkers related to ferroptosis in preeclampsia. Our findings will provide evidence for the involvement of ferroptosis in preeclampsia and improve the understanding of ferroptosis-related molecular pathways in the pathogenesis of preeclampsia.

lncRNA ZFAS1 Positively Facilitates Endothelial Ferroptosis via miR-7-5p/ACSL4 Axis in Diabetic Retinopathy

Accumulating evidence has suggested the significant role of long noncoding RNAs (lncRNA) in regulating ferroptosis, while its regulatory mechanism in diabetic retinopathy (DR) remains unelucidated. In this work, we first demonstrated that lncRNA zinc finger antisense 1 (ZFAS1) is upregulated in high glucose-cultured human retinal endothelial cells (hRECs) and ZFAS1 inhibition attenuated high glucose- (HG-) induced ferroptosis, which was evidenced by cell viability, total iron and ferrous iron levels, reactive oxygen species (ROS) level, and Glutathione Peroxidase 4 (GP_X4) expression detection. Mechanistically, we validated that ZFAS1 may act as a competing endogenous RNA by competitively binding with microRNA-7-5p (miR-7-5p) and modulating the expression of its downstream molecule acyl-CoA synthetase long-chain family member 4 (ACSL4), which is now identified as a classic driver gene of ferroptosis process. In conclusion, our results demonstrate that HG-induced ZFAS1 elevation activates ferroptosis in hRECs and the ZFAS1/miR-7-5p/ACSL4 axis may serve as a therapeutic target for endothelial dysfunction in DR.