The forkhead box O3 (FOXO3): a key player in the regulation of ischemia and reperfusion injury

SIRT2 Promotes NLRP3-Mediated Microglia Pyroptosis and Neuroinflammation via FOXO3a Pathway After Subarachnoid Hemorrhage

Purpose

This study primarily elucidating the specific mechanism of SIRT2 on neuroinflammation and microglial pyroptosis in a mouse model of SAH.

Patients and Methods

CSF were collected from 57 SAH patients and 11 healthy individuals. C57BL/6 mouse SAH model was established using prechiasmatic cistern blood injection and the in vitro hemoglobin (Hb) stimulation microglia model. Lentivirus was used as a vector for RNA interference technology to knock down the SIRT2 gene expression. Small interfering RNA was used to knockdown the expression of FOXO3a. The tools included measurements of brain water content, neurological scores, Western blot, PCR, ELISA, TEM, immunofluorescence, LDH assay, modified Garcia score, and balance beam tests to evaluate changes in pyroptosis and neuroinflammatory responses.

Results

In CSF samples from SAH patients, elevated levels of SIRT2 and GSDMD were observed, with SIRT2 demonstrating particular diagnostic value for predicting prognosis at the 3-month follow-up. SIRT2 upregulation exacerbated neurological deficits, brain edema, and blood-brain barrier disruption in mice following SAH. SIRT2 increased GSDMD, caspase-1, and IL-1β/IL-18 expression, and amplified GSDMD-positive microglia. FOXO3a was also upregulated post-SAH. siRNA-mediated SIRT2 knockdown ameliorated microglial pyroptosis after SAH. FOXO3a siRNA reduced NLRP3 inflammasome activation and microglial pyroptosis severity, along with neuroinflammation post-SAH.

Conclusion

In summary, SIRT2 promoted microglial pyroptosis, primarily by increasing the expression and activity of Foxo3a, thereby exacerbating neuroinflammatory damage following subarachnoid hemorrhage.

Chaperones vs. oxidative stress in the pathobiology of ischemic stroke

As many proteins prioritize functionality over constancy of structure, a proteome is the shortest stave in the Liebig's barrel of cell sustainability. In this regard, both prokaryotes and eukaryotes possess abundant machinery supporting the quality of the proteome in healthy and stressful conditions. This machinery, namely chaperones, assists in folding, refolding, and the utilization of client proteins. The functions of chaperones are especially important for brain cells, which are highly sophisticated in terms of structural and functional organization. Molecular chaperones are known to exert beneficial effects in many brain diseases including one of the most threatening and widespread brain pathologies, ischemic stroke. However, whether and how they exert the antioxidant defense in stroke remains unclear. Herein, we discuss the chaperones shown to fight oxidative stress and the mechanisms of their antioxidant action. In ischemic stroke, during intense production of free radicals, molecular chaperones preserve the proteome by interacting with oxidized proteins, regulating imbalanced mitochondrial function, and directly fighting oxidative stress. For instance, cells recruit Hsp60 and Hsp70 to provide proper folding of newly synthesized proteins-these factors are required for early ischemic response and to refold damaged polypeptides. Additionally, Hsp70 upregulates some dedicated antioxidant pathways such as FOXO3 signaling. Small HSPs decrease oxidative stress via attenuation of mitochondrial function through their involvement in the regulation of Nrf- (Hsp22), Akt and Hippo (Hsp27) signaling pathways as well as mitophagy (Hsp27, Hsp22). A similar function has also been proposed for the Sigma-1 receptor, contributing to the regulation of mitochondrial function. Some chaperones can prevent excessive formation of reactive oxygen species whereas Hsp90 is suggested to be responsible for pro-oxidant effects in ischemic stroke. Finally, heat-resistant obscure proteins (Hero) are able to shield client proteins, thus preventing their possible over oxidation.

Polysaccharides targeting autophagy to alleviate metabolic syndrome

Metabolic syndrome is a prevalent non-communicable disease characterized by central obesity, insulin resistance, hypertension, hyperglycemia, and hyperlipidemia. Epidemiological statistics indicate that one-third of the world's population is affected by metabolic syndrome. Unfortunately, owing to complicated pathogenesis and limited pharmacological options, the growing prevalence of metabolic syndrome threatens human health worldwide. Autophagy is an intracellular degradation mechanism that involves the degradation of unfolded or aggregated proteins and damaged cellular organelles, thereby maintaining metabolic homeostasis. Increasing evidence indicates that dysfunctional autophagy is closely associated with the development of metabolic syndrome, making it an attractive therapeutic target. Furthermore, a growing number of plant-derived polysaccharides have been shown to regulate autophagy, thereby alleviating metabolic syndrome, such as Astragalus polysaccharides, Laminaria japonica polysaccharides, Ganoderma lucidum polysaccharides and Lycium barbarum polysaccharides. In this review, we summarize recent advances in the discovery of autophagy modulators of plant polysaccharides for the treatment of metabolic syndrome, with the aim of providing precursor compounds for the development of new therapeutic agents. Additionally, we look forward to seeing more diseases being treated with plant polysaccharides by regulating autophagy, as well as the discovery of more intricate mechanisms that govern autophagy.

Mitophagy Regulates Kidney Diseases

Background

Mitophagy is a crucial process involved in maintaining cellular homeostasis by selectively eliminating damaged or surplus mitochondria. As the kidney is an organ with a high dynamic metabolic rate and abundant mitochondria, it is particularly crucial to control mitochondrial quality through mitophagy. Dysregulation of mitophagy has been associated with various renal diseases, including acute and chronic kidney diseases, and therefore a better understanding of the links between mitophagy and these diseases may present new opportunities for therapeutic interventions.

Summary

Mitophagy plays a pivotal role in the development of kidney diseases. Upregulation and downregulation of mitophagy have been observed in various kidney diseases, such as renal ischemia-reperfusion injury, contrast-induced acute kidney injury, diabetic nephropathy, kidney fibrosis, and several inherited renal diseases. A growing body of research has suggested that PINK1 and Parkin, the main mitophagy regulatory proteins, represent promising potential therapeutic targets for kidney diseases. In this review, we summarize the latest insights into how the progression of renal diseases can be mitigated through the regulation of mitophagy, while highlighting their performance in clinical trials.

Key Message

This review comprehensively outlines the mechanisms of mitophagy and its role in numerous kidney diseases. While early research holds promise, most mitophagy-centered therapeutic approaches have yet to reach the clinical application stage.

Analysis of Differentially Expressed Murine miRNAs in Acute Myocardial Infarction and Target Genes Related to Heart Rate

OBJECTIVE

This study aims to investigate the expression profile of miRNAs significantly dysregulated after acute myocardial infarction (AMI) and their potential targets.

METHODS

After the establishment of a mouse model of AMI, RNA was extracted from mouse infarcted myocardium. Paired-end sequencing was then performed using the Illumina NovaSeq 6000 system to explore the expression profile of miRNAs. Target genes of downregulated differentially expressed miRNAs (DEmiRNAs) were predicted with miRanda (version 3.3a) and TargetScan (version 6.0). Cytoscape was used to construct a DEmiRNA-mRNA regulatory network to show the regulatory relationship. RT-qPCR was performed to measure miR-142a-3p expression in H2O2-treated rat cardiomyocyte H9c2 cells and heart tissues of MI rats. Cell counting kit-8 and TUNEL assays were conducted to detect H9c2 cell viability and apoptosis.

RESULTS

There were 33 differentially expressed miRNAs, of which 3 were significantly upregulated and the rest 30 were significantly downregulated. Target genes of these miRNAs were identified, and their functional enrichment was analyzed using gene ontology (GO) analysis. Importantly, target genes that can regulate heart rate and their paired upstream miRNAs attracted attention. Significant expression correlation between heart rate-related targets (Epas1, Bves, Hcn4, Cacna1e, Ank2, Slc8a1, Pde4d) and paired miRNAs (miR-142a-5p, miR-7b-5p, miR-144-3p, miR-34c-5p, miR-223-3p, miR-18a-5p) in mouse myocardial tissues was identified. MiR-142a-3p was downregulated in H9c2 cells and rat infarct tissues, and overexpressing miR-142a-3p restrains H2O2-induced H9c2 cell apoptosis.

CONCLUSION

Cardioprotective miRNAs, such as miR-142a-3p, were identified in mouse myocardial tissues, and some specific miRNA-target pairs are associated with heart rate regulation.

Mechanisms of mitophagy and oxidative stress in cerebral ischemia-reperfusion, vascular dementia, and Alzheimer's disease

Neurological diseases have consistently represented a significant challenge in both clinical treatment and scientific research. As research has progressed, the significance of mitochondria in the pathogenesis and progression of neurological diseases has become increasingly prominent. Mitochondria serve not only as a source of energy, but also as regulators of cellular growth and death. Both oxidative stress and mitophagy are intimately associated with mitochondria, and there is mounting evidence that mitophagy and oxidative stress exert a pivotal regulatory influence on the pathogenesis of neurological diseases. In recent years, there has been a notable rise in the prevalence of cerebral ischemia/reperfusion injury (CI/RI), vascular dementia (VaD), and Alzheimer's disease (AD), which collectively represent a significant public health concern. Reduced levels of mitophagy have been observed in CI/RI, VaD and AD. The improvement of associated pathology has been demonstrated through the increase of mitophagy levels. CI/RI results in cerebral tissue ischemia and hypoxia, which causes oxidative stress, disruption of the blood-brain barrier (BBB) and damage to the cerebral vasculature. The BBB disruption and cerebral vascular injury may induce or exacerbate VaD to some extent. In addition, inadequate cerebral perfusion due to vascular injury or altered function may exacerbate the accumulation of amyloid β (Aβ) thereby contributing to or exacerbating AD pathology. Intravenous tissue plasminogen activator (tPA; alteplase) and endovascular thrombectomy are effective treatments for stroke. However, there is a narrow window of opportunity for the administration of tPA and thrombectomy, which results in a markedly elevated incidence of disability among patients with CI/RI. It is regrettable that there are currently no there are still no specific drugs for VaD and AD. Despite the availability of the U.S. Food and Drug Administration (FDA)-approved clinical first-line drugs for AD, including memantine, donepezil hydrochloride, and galantamine, these agents do not fundamentally block the pathological process of AD. In this paper, we undertake a review of the mechanisms of mitophagy and oxidative stress in neurological disorders, a summary of the clinical trials conducted in recent years, and a proposal for a new strategy for targeted treatment of neurological disorders based on both mitophagy and oxidative stress.

Production of Fucoxanthin from Microalgae Isochrysis galbana of Djibouti: Optimization, Correlation with Antioxidant Potential, and Bioinformatics Approaches

Fucoxanthin, a carotenoid with remarkable antioxidant properties, has considerable potential for high-value biotechnological applications in the pharmaceutical, nutraceutical, and cosmeceutical fields. However, conventional extraction methods of this molecule from microalgae are limited in terms of cost-effectiveness. This study focused on optimizing biomass and fucoxanthin production from Isochrysis galbana, isolated from the coast of Tadjoura (Djibouti), by testing various culture media. The antioxidant potential of the cultures was evaluated based on the concentrations of fucoxanthin, carotenoids, and total phenols. Different nutrient formulations were tested to determine the optimal combination for a maximum biomass yield. Using the statistical methodology of principal component analysis, Walne and Guillard F/2 media were identified as the most promising, reaching a maximum fucoxanthin yield of 7.8 mg/g. Multiple regression models showed a strong correlation between antioxidant activity and the concentration of fucoxanthin produced. A thorough study of the optimization of I. galbana growth conditions, using a design of experiments, revealed that air flow rate and CO2 flow rate were the most influential factors on fucoxanthin production, reaching a value of 13.4 mg/g. Finally, to validate the antioxidant potential of fucoxanthin, an in silico analysis based on molecular docking was performed, showing that fucoxanthin interacts with antioxidant proteins (3FS1, 3L2C, and 8BBK). This research not only confirmed the positive results of I. galbana cultivation in terms of antioxidant activity, but also provided essential information for the optimization of fucoxanthin production, opening up promising prospects for industrial applications and future research.

Erythropoietin alleviates lung ischemia-reperfusion injury by activating the FGF23/FGFR4/ERK signaling pathway

Background

The purpose of the present study was to investigate the effect of erythropoietin (EPO) on lung ischemia-reperfusion injury (LIRI).

Methods

Sprague Dawley rats and BEAS-2B cells were employed to construct an ischemia-reperfusion (I/R)-induced model in vivo and in vitro, respectively. Afterward, I/R rats and tert-butyl hydroperoxide (TBHP)-induced cells were treated with different concentrations of EPO. Furthermore, 40 patients with LIRI and healthy controls were enrolled in the study.

Results

It was observed that lung tissue damage, cell apoptosis and the expression of BAX and caspase-3 were higher in the LIRI model in vivo and in vitro than in the control group, nevertheless, the Bcl-2, FGF23 and FGFR4 expression level was lower than in the control group. EPO administration significantly reduced lung tissue damage and cell apoptosis while also up-regulating the expression of FGF23 and FGFR4. Rescue experiments indicated that EPO exerted a protective role associated with the FGF23/FGFR4/p-ERK1/2 signal pathway. Notably, the expression of serum EPO, FGF23, FGFR4 and Bcl-2 was decreased in patients with LIRI, while the expression of caspase-3 and BAX was higher.

Conclusion

EPO could effectively improve LIRI, which might be related to the activation of the FGF23/FGFR4/p-ERK1/2 signaling pathway.

Direct degradation and stabilization of proteins: New horizons in treatment of nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is featured with excessive hepatic lipid accumulation and its global prevalence is soaring. Nonalcoholic steatohepatitis (NASH), the severe systemic inflammatory subtype of NAFLD, is tightly associated with metabolic comorbidities, and the hepatocytes manifest severe inflammation and ballooning. Currently the therapeutic options for treating NASH are limited. Potent small molecules specifically intervene with the signaling pathways that promote pathogenesis of NASH. Nevertheless they have obvious adverse effects and show long-term ineffectiveness in clinical trials. It poses the fundamental question to efficiently and safely inhibit the pathogenic processes. Targeted protein degradation (TPD) belongs to the direct degradation strategies and is a burgeoning strategy. It utilizes the small molecules to bind to the target proteins and recruit the endogenous proteasome, lysosome and autophagosome-mediated degradation machineries. They effectively and specifically degrade the target proteins. It has exhibited promising therapeutic effects in treatment of cancer, neurodegenerative diseases and other diseases in a catalytic manner at low doses. We critically discuss the principles of multiple direct degradation strategies, especially PROTAC and ATTEC. We extensively analyze their emerging application in degradation of excessive pathogenic proteins and lipid droplets, which promote the progression of NASH. Moreover, we discuss the opposite strategy that utilizes the small molecules to recruit deubiquinases to stabilize the NASH/MASH-suppressing proteins. Their advantages, limitations, as well as the solutions to address the limitations have been analyzed. In summary, the innovative direct degradation strategies provide new insights into design of next-generation therapeutics to combat NASH with optimal safety paradigm and efficiency.