Modulation of Glutathione Hemostasis by Inhibition of 12/15-Lipoxygenase Prevents ROS-Mediated Cell Death after Hepatic Ischemia and Reperfusion

Baicalein relieves lung graft ischemia-reperfusion injury by reducing advanced glycation endproducts: From screens to mechanisms

BACKGROUND

The lack of effective drugs for treating ischemia-reperfusion injury (IRI) in lung transplants (LTx) remains an issue. Traditional Chinese medicine (TCM) ingredients are promising but poorly studied in LTx. This study aimed to identify potential ingredients and elucidate their mechanisms.

METHODS

Ten TCM ingredients, including (-)-epigallocatechin-3-gallate, quercetin, wogonin, triptolide, berberine, fisetin, coumestrol, luteolin, nobiletin, and baicalein, were identified as promising candidates using a network pharmacology approach. All the candidates were tested for their ability to improve clamp-induced IRI. Multiple-dose validation was conducted in LTx models, with a focus on baicalein. The pharmacological efficacy of baicalin was verified in an ex-vivo rat lung perfusion model.

RESULTS

All ten TCM ingredients improved clamp-induced IRI. Multiple-dose validation confirmed that baicalein mitigated IRI-induced graft damage and dysfunction. Baicalein reduced the elevated levels of advanced glycation endproducts (AGEs) and their downstream pathogenic effects induced by IRI. Exogenous AGEs counteracted the therapeutic effect of baicalein. Baicalein inhibited AGE formation by modulating glucose oxidation rather than polyol metabolism.

CONCLUSIONS

This study provides a laboratory foundation for the use of TCM ingredients in the treatment of IRI in LTx.

The Efficacy of Ferroptosis Inhibition on Ischemia-Reperfusion Injury of Abdominal Organs: A Systematic Review and Meta-analysis

Solid organ transplantation is hampered by complications that arise after ischemia-reperfusion injury (IRI), a detrimental type of injury for which no adequate treatment options are available. Ferroptosis, an iron-dependent form of regulated cell death, is a major driver of IRI. This systematic review and meta-analysis summarizes the effects of pharmacological ferroptosis inhibition in abdominal organs in the setting of IRI. PubMed, Embase, Web of Science and Cochrane were searched for concepts "ferroptosis" and "IRI" in August 2023. To allow for meta-analyses, inhibitors were divided into different intervention pathways: (I) lipophilic radical scavengers, (II) iron chelators, (III) antioxidants, (IV) lipid metabolism inhibitors, (V) combination treatments, and (VI) others. When available, organ function and injury effect sizes were extracted and used for random-effects meta-analyses. In total 79 articles were included, describing 59 unique inhibitors in kidney, liver, and intestinal IRI. No studies in pancreas were found. Overall bias and study quality was unclear and average to low, respectively. Apart from 1 clinical study, all inhibitors were tested in preclinical settings. The vast majority of the studies showed ferroptosis inhibition to be protective against IRI under various treatment conditions. In liver and kidney IRI, meta-analyses on standardized effect sizes from 43 articles showed a combined protective effect against IRI compared with a nontreated controls for all analyzed intervention pathways. In conclusion, ferroptosis inhibition protects against abdominal IRI in preclinical research. Important questions regarding optimal intervention pathway, bioavailability, optimal dosage, side effects etc. should be addressed before clinical introduction.

Modulation of Neuroinflammation in Poststroke Rehabilitation: The Role of 12/15-Lipoxygenase Inhibition and Baicalein

Neuroinflammation significantly contributes to stroke pathophysiology, leading to tissue damage and neurological deficits. Baicalein, a potent 12/15-LOX (12/15-lipoxygenase) inhibitor, demonstrates neuroprotective effects by reducing inflammatory lipid mediators, modulating key inflammatory pathways, and attenuating oxidative stress. Experimental studies indicate that baicalein can diminish infarct size and neurological deficits while improving safety and tolerability. Combination therapies with baicalein show promise in enhancing stroke outcomes. Overall, targeting 12/15-LOX and employing baicalein represents a promising approach to modulating neuroinflammation and improving recovery in stroke patients. This review highlights the therapeutic potential of inhibiting the 12/15-LOX pathway and utilizing the natural compound baicalein to mitigate poststroke neuroinflammation.

Baicalein attenuates oxidative damage in mice haematopoietic cells through regulation of PDGFRβ

Platelet-derived growth factor receptor β (PDGFRβ) plays a crucial role in murine haematopoiesis. Baicalein (BAI), a naturally occurring flavonoid, can alleviate disease damage through anti-oxidative, anti-apoptotic, and anti-inflammatory mechanisms. However, whether BAI attenuates oxidative damage in murine haematopoietic cells by PDGFRβ remains unexplored. In this study, we utilized a tert-butyl hydroperoxide (TBHP)-induced BaF3 cell injury model and an ionising radiation (IR)-induced mice injury model to investigate the impact of the presence or absence of PDGFRβ on the pharmacological effects of BAI. In addition, the BAI-PDGFRβ interaction was characterized by molecular docking and dynamics simulations. The results show that a specific concentration of BAI led to increased cell viability, reduced reactive oxygen species (ROS) content, upregulated nuclear factor erythroid 2-related factor 2 (NRF2) expression, and its downstream target genes heme oxygenase 1 (HO-1) and NAD(P)H Quinone Dehydrogenase 1 (NQO1), and activated protein kinase B (AKT) pathway in cells expressing PDGFRβ plasmid and experiencing damage. Similarly, BAI elevated lineage-Sca1+cKIT+ (LSK) cell proportion, promoted haematopoietic restoration, enhanced NRF2-mediated antioxidant response in PDGFRβ+/+ mice. However, despite BAI usage, PDGFRβ knockout mice (PDGFRβ-/-) showed lower LSK proportion and less antioxidant capacity than the total body irradiation (TBI) group. Furthermore, we demonstrated an interaction between BAI and PDGFRβ at the molecular level. Collectively, our results indicate that BAI attenuates oxidative stress injury and helps promote haematopoietic cell recovery through regulation of PDGFRβ.

Ferroptosis: a new target for hepatic ischemia-reperfusion injury?

Ischemia-reperfusion injury (IRI) can seriously affect graft survival and prognosis and is an unavoidable event during liver transplantation. Ferroptosis is a novel iron-dependent form of cell death characterized by iron accumulation and overwhelming lipid peroxidation; it differs morphologically, genetically, and biochemically from other well-known cell death types (autophagy, necrosis, and apoptosis). Accumulating evidence has shown that ferroptosis is involved in the pathogenesis of hepatic IRI, and targeting ferroptosis may be a promising therapeutic approach. Here, we review the pathways and phenomena involved in ferroptosis, explore the associations and implications of ferroptosis and hepatic IRI, and discuss possible strategies for modulating ferroptosis to alleviate the hepatic IRI.

Sulforaphane protects microvascular endothelial cells in lower limb ischemia/reperfusion injury mice

Background: Microvascular damage is a key pathological factor in acute lower limb ischemia/reperfusion (I/R) injury. Current evidence suggests that sulforaphane (SFN) protects tissue from I/R injury. However, the role of SFN in acute lower limb I/R injury remains elusive. This study aimed to investigate the role and potential mechanism of SFN in I/R-related microvascular damage in the limb. Methods: Limb viability was evaluated by laser Doppler imaging, tissue edema analysis and histological analysis. Western blotting and immunofluorescence were applied to analyze the levels of apoptosis, oxidative stress, autophagy, transcription factor EB (TFEB) activity and mucolipin 1 (MCOLN1)-calcineurin signaling pathway. Results: SFN administration significantly ameliorated I/R-induced hypoperfusion, tissue edema, skeletal muscle fiber injury and endothelial cell (EC) damage in the limb. Pharmacological inhibition of NFE2L2 (nuclear factor, erythroid 2 like 2) reversed the anti-oxidation and anti-apoptosis effects of SFN on ECs. Additionally, silencing of TFEB by interfering RNA abolished the SFN-induced autophagy restoration, anti-oxidant response and anti-apoptosis effects on ECs. Furthermore, silencing of MCOLN1 by interfering RNA and pharmacological inhibition of calcineurin inhibited the activity of TFEB induced by SFN, demonstrating that SFN regulates the activity of TFEB through the MCOLN1-calcineurin signaling pathway. Conclusion: SFN protects microvascular ECs against I/R injury by TFEB-mediated autophagy restoration and anti-oxidant response.

LoxBlock-1 or Curcumin attenuates liver, pancreas and cardiac ferroptosis, oxidative stress and injury in Ischemia/reperfusion-damaged rats by facilitating ACSL/GPx4 signaling

In this study, the effects of the pretreatment of Curcumin and LoxBlock-1 on liver, pancreas, and cardiac dysfunction following Ischemia-Reperfusion-induced (IR) Acute Kidney Injury (AKI) were investigated through the mechanisms of oxidative stress and ferroptosis. Total antioxidant status (TAS), total oxidant status (TOS) and oxidative stress index (OSI) parameters in the tissue were analyzed to investigate the oxidative stress occurring in the liver, pancreas, and heart, and Acyl-Coa synthetase long-chain family member (ACSL4). Glutathione peroxidase 4 (GPx4) enzyme levels were also analyzed by ELISA to investigate the effect on ferroptosis. In addition, hematoxylin-eosin staining was performed for histopathological examination of the tissues. As a result of biochemical analyzes, it was observed that oxidative stress parameters increased significantly in the IR group. In addition, while the ACSL4 enzyme level increased in the IR group in all tissues, the GPx4 enzyme level decreased. In the histopathological examination, it was observed that IR caused serious damage to the heart, liver, and pancreas tissues. The present study shows that Curcumin and LoxBlock-1 have a protective effect on the liver, pancreas, and cardiac ferroptosis following the effect on AKI. In addition, Curcumin was found to be more effective than LoxBlock-1 in I/R injury with its antioxidant property.

GPX4: The hub of lipid oxidation, ferroptosis, disease and treatment

Glutathione peroxidase 4 (GPx4) moonlights as structural protein and antioxidase that powerfully inhibits lipid oxidation. In the past years, it is considered as a key regulator of ferroptosis, which takes role in the lipid and amine acid metabolism and influences the cell aging, oncogenesis, and cell death. More and more evidences show that targeting GPX4-induced ferroptosis is a promising strategy for disease therapy, especially cancer treatment. In view of these, we generalize the function of GPX4 and regulatory mechanism between GPX4 and ferroptosis, discuss its roles in the disease pathology, and focus on the recent advances of disease therapeutic potential.

Hepatocyte-specific TMEM16A deficiency alleviates hepatic ischemia/reperfusion injury via suppressing GPX4-mediated ferroptosis

Ischemia/reperfusion (I/R)-induced liver injury with severe cell death is a major complication of liver transplantation. Transmembrane member 16A (TMEM16A), a component of hepatocyte Ca²⁺-activated chloride channel, has been implicated in a variety of liver diseases. However, its role in hepatic I/R injury remains unknown. Here, mice with hepatocyte-specific TMEM16A knockout or overexpression were generated to examine the effect of TMEM16A on hepatic I/R injury. TMEM16A expression increased in liver samples from patients and mice with I/R injury, which was correlated with liver damage progression. Hepatocyte-specific TMEM16A knockout alleviated I/R-induced liver damage in mice, ameliorating inflammation and ferroptotic cell death. However, mice with hepatic TMEM16A overexpression showed the opposite phenotype. In addition, TMEM16A ablation decreased inflammatory responses and ferroptosis in hepatocytes upon hypoxia/reoxygenation insult in vitro, whereas TMEM16A overexpression promoted the opposite effects. The ameliorating effects of TMEM16A knockout on hepatocyte inflammation and cell death were abolished by chemically induced ferroptosis, whereas chemical inhibition of ferroptosis reversed the potentiated role of TMEM16A in hepatocyte injury. Mechanistically, TMEM16A interacted with glutathione peroxidase 4 (GPX4) to induce its ubiquitination and degradation, thereby enhancing ferroptosis. Disruption of TMEM16A-GPX4 interaction abrogated the effects of TMEM16A on GPX4 ubiquitination, ferroptosis, and hepatic I/R injury. Our results demonstrate that TMEM16A exacerbates hepatic I/R injury by promoting GPX4-dependent ferroptosis. TMEM16A-GPX4 interaction and GPX4 ubiquitination are therefore indispensable for TMEM16A-regulated hepatic I/R injury, suggesting that blockades of TMEM16A-GPX4 interaction or TMEM16A inhibition in hepatocytes may represent promising therapeutic strategies for acute liver injury.

Baicalein Relieves Ferroptosis-Mediated Phagocytosis Inhibition of Macrophages in Ovarian Endometriosis

Iron overload and oxidative stress have been reported to contribute to ferroptosis in endometriotic lesions. However, the possible roles of iron overload on macrophages in endometriosis (EMs) remain unknown. Based on recent reports by single-cell sequencing data of endometriosis, here we found significant upregulations of ferroptosis-associated genes in the macrophage of the endometriotic lesion. Additionally, there was an elevated expression of HMOX1, FTH1, and FTL in macrophages of peritoneal fluid in EMs, as well as iron accumulation in the endometriotic lesions. Notably, cyst fluid significantly up-regulated levels of intracellular iron and ferroptosis in Phorbol-12-myristate-13-acetate (PMA)-stimulated THP-1 cells. Additionally, high iron-induced ferroptosis obviously reduced PMA-stimulated THP-1 cells' phagocytosis and increased the expression of angiogenic cytokines, such as vascular endothelial growth factor A (VEGFA) and interleukin 8 (IL8). Baicalein, a potential anti-ferroptosis compound, increased GPX4 expression, significantly inhibited ferroptosis, and restored phagocytosis of THP-1 cells in vitro. Collectively, our study reveals that ferroptosis triggered by high iron in cyst fluid promotes the development of EMs by impairing macrophage phagocytosis and producing more angiogenic cytokines (e.g., IL8 and VEGFA). Baicalein displays the potential for the treatment of EMs, especially in patients with high ferroptosis and low phagocytosis of macrophages.

Baicalein Alleviates Testicular Ischemia-Reperfusion Injury in a Rat Model of Testicular Torsion-Detorsion

Testicular torsion/detorsion-induced ischemia/reperfusion injury is partly due to the overgeneration of reactive oxygen species. Baicalein, a main bioactive constituent derived from the dried root of Scutellaria baicalensis Georgi, possesses powerful antioxidative and anti-inflammatory properties. Therefore, we designed the research to explore the possible protective effect of baicalein against testicular ischemia-reperfusion injury. Sprague-Dawley rats were randomized into 4 groups, including control, testicular ischemia-reperfusion, testicular ischemia-reperfusion+vehicle injection, and testicular ischemia-reperfusion+baicalein therapy groups. The control group received surgical exposure of the left testis without torsion-detorsion. In the testicular ischemia-reperfusion group, the left testis underwent 720° counterclockwise torsion for two hours and then was allowed detorsion. Rats in the testicular ischemia-reperfusion+vehicle injection group received intraperitoneal injection of the vehicle at detorsion. In the baicalein-treated group, the intraperitoneal administration of baicalein dissolved in the vehicle was performed at detorsion. At four hours or three months following testicular detorsion, testicular tissues were removed to detect the levels of tumor necrosis factor-alpha (TNF-α) and interleukin-1beta (IL-1β) which can recruit neutrophils into the testis, myeloperoxidase activity (an index of neutrophil infiltration in the testis), protein expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in neutrophils which can catalyze reactive oxygen species production, malondialdehyde concentration (a common marker of reactive oxygen species), and spermatogenesis. Both testicular ischemia-reperfusion and testicular ischemia-reperfusion+vehicle injection significantly increased the TNF-α and IL-1β levels, myeloperoxidase activity, NADPH oxidase protein expression, and malondialdehyde concentration, while decreased spermatogenesis in ipsilateral testes. In contrast, baicalein administration remarkably reduced TNF-α and IL-1β levels, myeloperoxidase activity, NADPH oxidase protein expression, and malondialdehyde concentration and also elevated spermatogenesis in ipsilateral testes. The results of our experiment demonstrate that baicalein alleviates testicular ischemia-reperfusion injury by inhibiting TNF-α and IL-1β secretion, neutrophil infiltration in the testis, and NADPH oxidase protein expression in neutrophils to reduce reactive oxygen species production.

Extraction Optimization, Structural Characterization, and Anti-Hepatoma Activity of Acidic Polysaccharides From Scutellaria barbata D. Don

The Chinese medicinal herb Scutellaria barbata D. Don has antitumour effects and is used to treat liver cancer in the clinic. S. barbata polysaccharide (SBP), one of the main active components extracted from S. barbata D. Don, exhibits antitumour activity. However, there is still a lack of research on the extraction optimization, structural characterization, and anti-hepatoma activity of acidic polysaccharides from S. barbata D. Don. In this study, the optimal extraction conditions for SBP were determined by response surface methodology (RSM): the material-liquid ratio was 1:25, the extraction time was 2 h, and the extraction temperature was 90°C. Under these conditions, the average extraction efficiency was 3.85 ± 0.13%. Two water-soluble polysaccharides were isolated from S. barbata D. Don, namely, SBP-1A and SBP-2A, these homogeneous acidic polysaccharide components with average molecular weights of 1.15 × 10⁵ Da and 1.4 × 10⁵ Da, respectively, were obtained at high purity. The results showed that the monosaccharide constituents of the two components were fucose, galactosamine hydrochloride, rhamnose, arabinose, glucosamine hydrochloride, galactose, glucose, xylose, and mannose; the molar ratio of these constituents in SBP-1A was 0.6:0.3:0.6:30.6:3.3:38.4:16.1:8:1.4, and that in SBP-2A was 0.6:0.5:0.8:36.3:4.4:42.7:9.2:3.6:0.7. In addition, SBP-1A and SBP-2A contained uronic acid and β-glucan, and the residue on the polysaccharide was mainly pyranose. The in vitro results showed that the anti-hepatoma activity of SBP-2A was better than that of SBP-1A and SBP. In addition, SBP-2A significantly enhanced HepG2 cell death, as cell viability was decreased, and SBP-2A induced HepG2 cell apoptosis and blocked the G1 phase. This phenomenon was coupled with the upregulated expression of P53 and Bax/Bcl-2 ratio, as well as the downregulated expression of the cell cycle-regulating protein cyclinD1, CDK4, and Bcl-2 in this study. Further analysis showed that 50 mg/kg SBP-2A inhibited the tumour growth in H22 tumour-bearing mice, with an average inhibition rate of 40.33%. Taken together, SBP-2A, isolated and purified from S. barbata showed good antitumour activity in vivo and in vitro, and SBP-2A may be a candidate drug for further evaluation in cancer prevention. This study provides insight for further research on the molecular mechanism of the anti-hepatoma activity of S. barbata polysaccharide.

Targeted fatty acid metabolomics to discover Parkinson's disease associated metabolic alteration

The pathogenesis of Parkinson's disease (PD) remains to be elucidated, and the metabolomics analysis has the potential to identify metabolic profiles that are involved in PD pathogenesis. Here we applied a target metabolomics approach to measure the plasma levels of 158 fatty acid metabolites in a discovery cohort including 42 PD patients and 54 health volunteers, and found two upregulated (arachidonic acid and 13-hydroxy-octadecatrienoic acid) and eleven down-regulated (docosahexaenoic acid, lyso-platelet-activating factor, 12-hydroxy-eicosatetraenoic acid, dihydroxy-eicosatrienoic acids, dihidroxy-octadecenoic acids, 17,18-dihydroxy-eicosatetraenoic acid, and hydroperoxy-octadecadienoic acids) metabolites as primary candidate marker of PD. A support vector machine algorithm with primary candidate marker was used in an independent validation cohort to identify PD. Arachidonic acid and 13-hydroxy-octadecatrienoic acid were evaluated as an effective tool in that area under the receiver operating characteristic curve reached 0.995 and 0.912 in the validation set for diagnosing PD from healthy volunteers. Besides, the sensitivity and specificity of arachidonic acid as diagnostic factor of PD in validation set were 100% and 94.10%. Similarly, the sensitivity and specificity of 13-hydroxy-octadecatrienoic acid were 100% and 82.40% for identifying PD. This target fatty acid metabolomics demonstrated a series of plasma fatty acid metabolite as PD candidate marker with high efficiency and provided insights into the understanding of PD metabolic regulation.

Mutagenesis, Hydrogen-Deuterium Exchange, and Molecular Docking Investigations Establish the Dimeric Interface of Human Platelet-Type 12-Lipoxygenase

It was previously shown that human platelet 12S-lipoxygenase (h12-LOX) exists as a dimer; however, the specific structure is unknown. In this study, we create a model of the dimer through a combination of computational methods, experimental mutagenesis, and hydrogen-deuterium exchange (HDX) investigations. Initially, Leu183 and Leu187 were replaced by negatively charged glutamate residues and neighboring aromatic residues were replaced with alanine residues (F174A/W176A/L183E/L187E/Y191A). This quintuple mutant disrupted both the hydrophobic and π-π interactions, generating an h12-LOX monomer. To refine the determinants for dimer formation further, the L183E/L187E mutant was generated and the equilibrium shifted mostly toward the monomer. We then submitted the predicted monomeric structure to protein-protein docking to create a model of the dimeric complex. A total of nine of the top 10 most energetically favorable docking conformations predict a TOP-to-TOP dimeric arrangement of h12-LOX, with the α-helices containing a Leu-rich region (L172, L183, L187, and L194), corroborating our experimental results showing the importance of these hydrophobic interactions for dimerization. This model was supported by HDX investigations that demonstrated the stabilization of four, non-overlapping peptides within helix α2 of the TOP subdomain for wt-h12-LOX, consistent with the dimer interface. Most importantly, our data reveal that the dimer and monomer of h12-LOX have distinct biochemical properties, suggesting that the structural changes due to dimerization have allosteric effects on active site catalysis and inhibitor binding.

Sevoflurane preconditioning activates HGF/Met-mediated autophagy to attenuate hepatic ischemia-reperfusion injury in mice

Sevoflurane (SEV) preconditioning plays a protective effect against liver ischemia reperfusion (IR) injury, while the role of autophagy in SEV-mediated hepatoprotection and the precise mechanism is unclear. In the current study, mice were pretreated with SEV or autophagy inhibitor before liver IR injury. In vitro, primary rat hepatocytes were pretreated with SEV and then exposed to hypoxia/reoxygenation (H/R). Liver function was measured by biochemical and histopathological examinations, and markers associated with inflammation, oxidation, apoptosis and autophagy were subsequently measured. We found that SEV preconditioning dramatically reduced hepatic damage, alleviated cell inflammatory response, oxidative stress and apoptosis in mice suffering hepatic IR injury, whereas these protective effects were abolished by the autophagy inhibitor 3-MA. In addition, pretreatment with SEV markedly activated HGF/Met signaling pathway regulation. Besides, pretreatment with an hepatocyte growth factor (HGF) inhibitor or knocking down HGF expression significantly downregulated phosphorylated met (p-met) and autophagy levels, and abolished the protective effects of SEV against hepatic IR or hepatocyte H/R injury. Conversely, HGF overexpression efficiently increased the p-met and autophagy levels and strengthened the protective effects of SEV. These results indicated that sevoflurane preconditioning ameliorates hepatic IR injury by activating HGF/Met-mediated autophagy.

Weaning differentially affects mitochondrial function, oxidative stress, inflammation and apoptosis in normal and low birth weight piglets

Weaning is associated with increased occurrence of infections and diseases in piglets. Recent findings indicate that weaning induces mitochondrial dysfunction and oxidative stress conditions that more severely impact smaller piglets. The objective of this study was to characterize the molecular mechanisms underlying these physiological consequences and the relation with systemic inflammatory status in both normal and low birth weight (NBW and LBW) piglets throughout the peri-weaning period. To conduct the study, 30 sows were inseminated, and specific piglets from their litters were assigned to one of two experimental groups: NBW (n = 60, 1.73 ± 0.01 kg,) and LBW piglets weighing less than 1.2 kg (n = 60, 1.01 ± 0.01 kg). Then, 10 piglets from each group were selected at 14, 21 (weaning), 23, 25, 29 and 35 days of age to collect organ and plasma samples. Specific porcine RT2 Profiler™ PCR Arrays related to mitochondrial function, oxidative stress, inflammation and apoptosis processes were first used to target genes that are modulated after weaning in NBW piglets (d 23 and d 35 vs. d 14). Expression of selected genes was evaluated by quantitative PCR. These analyses revealed that expression of inflammatory genes CXCL10 and CCL19 increased after weaning in intestinal mucosa, while expression of genes encoding subunits of the mitochondrial respiratory chain was downregulated in liver and kidney of both groups. Interestingly, major modulators of mitophagy (BNIP3), cell survival (BCL2A1) and antioxidant defense system (TXNRD2, GPx3, HMOX1) were found to be highly expressed in NBW piglets. The systemic levels of TNF-α and IL1-β significantly increased following weaning and were higher in NBW piglets. These results provide novel information about the molecular origin of mitochondrial dysfunction and oxidative stress observed in weaned piglets and suggest that clearance of dysfunctional mitochondria, antioxidant defenses and inflammatory response are compromised in LBW piglets.

Gigantol ameliorates CCl4-induced liver injury via preventing activation of JNK/cPLA2/12-LOX inflammatory pathway

Arachidonic acid (AA) signaling pathway is an important constituent of inflammatory processes. In our previous study, it was found that dihydro-stilbene gigantol relieved hepatic inflammation in mice with CCl₄-induced acute liver injury. This study aimed to investigate the involvement of arachidonate metabolic cascade in this process. Our results showed CCl₄ activated AA metabolism with the evidence of cPLA2 phosphorylation, which was dependent on the MAPK/JNK activation. Pretreatment with JNK inhibitor SU3327 or gigantol abolished the cPLA2 activation, along with the attenuation of liver damage. Besides, gigantol markedly decreased immune cells activation. Metabolomic analysis revealed that gigantol universally reversed the upregulation of major AA metabolites in injured mouse livers induced by CCl₄, especially 12-hydroxyeicosatetraenoic acid (12-HETE). Gigantol also decreased the mRNA and protein expression of platelet-, and leukocyte-type 12-lipoxxygenase (LOX) in the liver. Furthermore, pan-LOX inhibitor nordihydroguaiaretic acid (NDGA) and specific 12-LOX inhibitors baicalein and ML351 attenuated the liver injury to the same extent as gigantol. Overall, our study elucidated a comprehensive profile of AA metabolites during hepatic inflammation caused by CCl₄, highlighting the role of 12-LOX-12-HETE pathway in this process. And gigantol alleviated liver inflammation partly through inhibiting the JNK/cPLA2/12-LOX pathway.

Inhibition of ACSL4 attenuates ferroptotic damage after pulmonary ischemia-reperfusion

Lung ischemia-reperfusion (IR) injury is a common clinical pathology associated with high mortality. Ferroptosis, a novel mode of cell death elicited by iron-dependent phospholipid peroxidation, has been implicated in ischemic events. Acyl-CoA synthetase long-chain family member 4 (ACSL4) is one of the main enzymes in pro-ferroptotic lipid metabolism. In this study, the involvement of ferroptotic death in different durations of reperfusion was evaluated by assessing the iron content, malondialdehyde, and glutathione levels, ferroptosis-related protein expression, and mitochondria morphology. The roles of ferroptosis-specific inhibitor, liproxastin-1 (Lip-1), and ACSL4 modulation in a preventive regimen were assessed in vivo and in vitro. The hallmarks of pulmonary function, such as histological lung injury score, wet/dry ratio, and oxygenation index, were evaluated as well. Results showed that lung IR increased the tissue iron content and lipid peroxidation accumulation, along with key protein (GPX4 and ACSL4) expression alteration during reperfusion. Pretreatment with Lip-1 inhibited ferroptosis and ameliorated lung IR-induced injury in animal and cell models. In addition, administering ACSL4 inhibitor rosiglitazone before ischemia diminished the ferroptotic damage in IR-injured lung tissue, consistent with the protective effect of ACSL4 knockdown on lung epithelial cells subjected to hypoxia/reoxygenation. Thus, this study delineated that IR-induced ferroptotic cell death in lung tissue and ACSL4 were correlated with this process. Inhibition of ferroptosis and ACSL4 mitigated the ferroptotic damage in IR-induced lung injury by reducing lipid peroxidation and increasing the glutathione and GPX4 levels.

Endoplasmic reticulum stress mediates osteocyte death under oxygen-glucose deprivation in vitro

As a vascularized organ, bone is known to be susceptible to ischemia. Ischemic osteonecrosis or skeletal unloading lead to ischemia in bone microenvironment that causes osteocytes to suffer hypoxia and nutrition deprivation.

OBJECTIVE

To explore the effects of Oxygen-glucose deprivation (OGD) on osteocytes and the potential mechanism.

METHODS

OGD model was established in cultured MLO-Y4 cell. Cell damage, intracellular oxidative stress and cell apoptosis were detected at different OGD times (0, 2, 4, 8, 12, 24 h), and the changes in endoplasmic reticulum (ER) stress-related indicators were observed. Furthermore, cells were treated with 4-phenylbutyrate sodium (4-PBA) to inhibit ER stress, and cell damage and oxidative stress level were detected.

RESULTS

The cell viability under OGD exhibited a significantly reduced in a time-dependent manner, and the level of intracellular reactive oxygen species (ROS) were increased, cell apoptosis and ER stress was induced. Inhibition of ER stress can reduce cell death and intracellular ROS levels.

CONCLUSION

Our study demonstrated that ER stress regulates OGD-induced apoptotic cell death in MLO-Y4 cells via intracellular ROS.

New insights into the role of mitochondria in cardiac microvascular ischemia/reperfusion injury

As reperfusion therapies have become more widely used in acute myocardial infarction patients, ischemia-induced myocardial damage has been markedly reduced, but reperfusion-induced cardiac injury has become increasingly evident. The features of cardiac ischemia-reperfusion (I/R) injury include microvascular perfusion defects, platelet activation and sequential cardiomyocyte death due to additional ischemic events at the reperfusion stage. Microvascular obstruction, defined as a no-reflow phenomenon, determines the infarct zone, myocardial function and peri-operative mortality. Cardiac microvascular endothelial cell injury may occur much earlier and with much greater severity than cardiomyocyte injury. Endothelial cells contain fewer mitochondria than other cardiac cells, and several of the pathological alterations during cardiac microvascular I/R injury involve mitochondria, such as increased mitochondrial reactive oxygen species (mROS) levels and disturbed mitochondrial dynamics. Although mROS are necessary physiological second messengers, high mROS levels induce oxidative stress, endothelial senescence and apoptosis. Mitochondrial dynamics, including fission, fusion and mitophagy, determine the shape, distribution, size and function of mitochondria. These adaptive responses modify extracellular signals and orchestrate intracellular processes such as cell proliferation, migration, metabolism, angiogenesis, permeability transition, adhesive molecule expression, endothelial barrier function and anticoagulation. In this review, we discuss the involvement of mROS and mitochondrial morphofunction in cardiac microvascular I/R injury.

GPX4 at the Crossroads of Lipid Homeostasis and Ferroptosis

Oxygen is necessary for aerobic metabolism but can cause the harmful oxidation of lipids and other macromolecules. Oxidation of cholesterol and phospholipids containing polyunsaturated fatty acyl chains can lead to lipid peroxidation, membrane damage, and cell death. Lipid hydroperoxides are key intermediates in the process of lipid peroxidation. The lipid hydroperoxidase glutathione peroxidase 4 (GPX4) converts lipid hydroperoxides to lipid alcohols, and this process prevents the iron (Fe²⁺ )-dependent formation of toxic lipid reactive oxygen species (ROS). Inhibition of GPX4 function leads to lipid peroxidation and can result in the induction of ferroptosis, an iron-dependent, non-apoptotic form of cell death. This review describes the formation of reactive lipid species, the function of GPX4 in preventing oxidative lipid damage, and the link between GPX4 dysfunction, lipid oxidation, and the induction of ferroptosis.

FGF21 Mediates Mesenchymal Stem Cell Senescence via Regulation of Mitochondrial Dynamics

Mesenchymal stem cell- (MSC-) based therapy is a novel strategy in regenerative medicine. The functional and regenerative capacities of MSCs decline with senescence. Nonetheless, the potential mechanisms that underlie their senescence are not fully understood. This study was aimed at exploring the potential mechanisms of fibroblast growth factor 21 (FGF21) in the regulation of MSC senescence. The senescence of MSCs was determined by senescence-associated β-galactosidase (SA-β-gal) staining. The morphology and the level of mitochondrial reactive oxygen species (ROS) of MSCs were assessed by MitoTracker and Mito-Sox staining, respectively. The expression of FGF21 and mitochondrial dynamics-related proteins was detected by Western blotting. As MSCs were expanded in vitro, the expression of FGF21 decreased. Depletion of FGF21 enhanced production of mitochondrial reactive oxidative species (ROS) and increased the senescence of early-passage MSCs whereas inhibition of ROS abolished these effects. The senescent MSCs exhibited increased mitochondrial fusion and decreased mitochondrial fission. Treatment of early-passage MSCs with FGF21 siRNA enhanced mitochondrial fusion and reduced mitochondrial fission. Moreover, treatment of mitofusin2- (Mfn2-) siRNA inhibited depletion of FGF21-induced MSC senescence. Furthermore, we demonstrated that depletion of FGF21-induced mitochondrial fusion was regulated by the AMPK signaling pathway. Treatment with an AMPK activator, AICAR, abrogated the depletion of FGF21-induced senescence of MSCs by inhibiting mitochondrial fusion. Compared with MSCs isolated from young donors, those derived from aged donors showed a lower level of FGF21 and a higher level of senescent activity. Furthermore, overexpression of FGF21 in aged MSCs inhibited senescence. Our study shows that FGF21, via the AMPK signaling pathway, regulates the senescence of MSCs by mediating mitochondrial dynamics. Targeting FGF21 might represent a novel strategy to improve the quality and quantity of MSCs.

Associations of Oxidative Stress and Postoperative Outcome in Liver Surgery with an Outlook to Future Potential Therapeutic Options

Several types of surgical procedures have shown to elicit an inflammatory stress response, leading to substantial cytokine production and formation of oxygen-based or nitrogen-based free radicals. Chronic liver diseases including cancers are almost always characterized by increased oxidative stress, in which hepatic surgery is likely to potentiate at least in the short term and hereby furthermore impair the hepatic redox state. During liver resection, intermittent inflow occlusion is commonly applied to prevent excessive blood loss but resulting ischemia and reperfusion of the liver have been linked to increased oxidative stress, leading to impairment of cell functions and subsequent cell death. In the field of liver transplantation, ischemia/reperfusion injury has extensively been investigated in the last decades and has recently been in the scientific focus again due to increased use of marginal donor organs and new machine perfusion concepts. Therefore, given the intriguing role of oxidative stress in the pathogenesis of numerous diseases and in the perioperative setting, the interest for a therapeutic antioxidative agent has been present for several years. This review is aimed at giving an introduction to oxidative stress in surgical procedures in general and then examines the role of oxidative stress in liver surgery in particular, discussing both transplantation and resection. Results from studies in the animal and human settings are included. Finally, potential therapeutic agents that might be beneficial in reducing the burden of oxidative stress in hepatic diseases and during surgery are presented. While there is compelling evidence from animal models and a limited number of clinical studies showing that oxidative stress plays a major role in both liver resection and transplantation and several recent studies have suggested a potential for antioxidative treatment in chronic liver disease (e.g., steatosis), the search for effective antioxidants in the field of liver surgery is still ongoing.

Probing the Electrostatic and Steric Requirements for Substrate Binding in Human Platelet-Type 12-Lipoxygenase

Human platelet ALOX12 (hALOX12 or h12-LOX) has been implicated in a variety of human diseases. The present study investigates the active site of hALOX12 to more thoroughly understand how it positions the substrate and achieves nearly perfect regio- and stereospecificities (i.e., 100 ± 5% of the 12(S)-hydroperoxide product), utilizing site-directed mutagenesis. Specifically, we have determined that Arg402 is not as important in substrate binding as previously seen for hALOX15 but that His596 may play a role in anchoring the carboxy terminal of the arachidonic acid during catalysis. In addition, Phe414 creates a π-stacking interaction with a double bond of arachidonic acid (Δ¹¹), and Ala417/Val418 define the bottom of the cavity. However, the influence of Ala417/Val418 on the profile is markedly less for hALOX12 than that seen in hALOX15. Mutating these two residues to larger amino acids (Ala417Ile/Val418Met) only increased the generation of 15-HpETE by 24 ± 2%, but conversely, smaller residues at these positions converted hALOX15 to almost 100% hALOX12 reactivity [Gan et al. (1996) J. Biol. Chem. 271, 25412-25418]. However, we were able to increase 15-HpETE to 46 ± 3% by restricting the width of the active site with the Ala417Ile/Val418Met/Ser594Thr mutation, indicating both depth and width of the active site are important. Finally, residue Leu407 is shown to play a critical role in positioning the substrate correctly, as seen by the increase of 15-HpETE to 21 ± 1% for the single Leu407Gly mutant. These results outline critical differences between the active site requirements of hALOX12 relative to hALOX15 and explain both their product specificity and inhibitory differences.

Vitamin E hydroquinone is an endogenous regulator of ferroptosis via redox control of 15-lipoxygenase

Ferroptosis is a form of programmed cell death associated with inflammation, neurodegeneration, and ischemia. Vitamin E (alpha-tocopherol) has been reported to prevent ferroptosis, but the mechanism by which this occurs is controversial. To elucidate the biochemical mechanism of vitamin E activity, we systematically investigated the effects of its major vitamers and metabolites on lipid oxidation and ferroptosis in a striatal cell model. We found that a specific endogenous metabolite of vitamin E, alpha-tocopherol hydroquinone, was a dramatically more potent inhibitor of ferroptosis than its parent compound, and inhibits 15-lipoxygenase via reduction of the enzyme's non-heme iron from its active Fe3+ state to an inactive Fe2+ state. Furthermore, a non-metabolizable isosteric analog of vitamin E which retains antioxidant activity neither inhibited 15-lipoxygenase nor prevented ferroptosis. These results call into question the prevailing model that vitamin E acts predominantly as a non-specific lipophilic antioxidant. We propose that, similar to the other lipophilic vitamins A, D and K, vitamin E is instead a pro-vitamin, with its quinone/hydroquinone metabolites responsible for its anti-ferroptotic cytoprotective activity.

Connexin32 plays a crucial role in ROS-mediated endoplasmic reticulum stress apoptosis signaling pathway in ischemia reperfusion-induced acute kidney injury

BACKGROUND

Ischemia-reperfusion (I/R)-induced acute kidney injury (AKI) not only prolongs the length of hospital stay, but also seriously affects the patient's survival rate. Although our previous investigation has verified that reactive oxygen species (ROS) transferred through gap junction composed of connexin32 (Cx32) contributed to AKI, its underlying mechanisms were not fully understood and viable preventive or therapeutic regimens were still lacking. Among various mechanisms involved in organs I/R-induced injuries, endoplasmic reticulum stress (ERS)-related apoptosis is currently considered to be an important participant. Thus, in present study, we focused on the underlying mechanisms of I/R-induced AKI, and postulated that Cx32 mediated ROS/ERS/apoptosis signal pathway activation played an important part in I/R-induced AKI.

METHODS

We established renal I/R models with Cx32+/+ and Cx32-/- mice, which underwent double kidneys clamping and recanalization. ROS scavenger (N-acetylcysteine, NAC) and ERS inhibitors (4-phenyl butyric acid, 4-PBA, and tauroursodeoxycholic acid, TUDCA) were used to decrease the content of ROS and attenuate ERS activation, respectively.

RESULTS

Renal damage was progressively exacerbated in a time-dependent manner at the reperfusion stage, that was consistent with the alternation of ERS activation, including glucose regulated protein 78 (BiP/GRP78), X box-binding protein1, and C/EBP homologous protein expression. TUDCA or 4-PBA application attenuated I/R-induced ERS activation and protected against renal tubular epithelial cells apoptosis and renal damage. Cx32 deficiency decreased ROS generation and distribution between the neighboring cells, which attenuated I/R-induced ERS activation, and improved cell apoptosis and renal damage.

CONCLUSION

Cx32 mediated ROS/ERS/apoptosis signal pathway activation played an important part in I/R-induced AKI. Cx32 deficiency, ROS elimination, and ERS inhibition all could protect against I/R-induced AKI.

Puerarin reduces ischemia/reperfusion-induced myocardial injury in diabetic rats via upregulation of vascular endothelial growth factor A/angiotensin-1 and suppression of apoptosis

Puerarin is an active ingredient of pueraria, which has been developed for puerarin injections, used in the treatment of cardiovascular diseases including arrhythmia, myocardial ischemia and hypertension. However, the molecular mechanisms of puerarin on ischemia/reperfusion (I/R)‑induced myocardial apoptosis in diabetic rats are not fully understood. The present study aimed to investigate whether puerarin can attenuate I/R‑induced myocardial apoptosis in diabetic rats, and to investigate the underlying mechanism. A hemodynamic analyzing system was employed to analyze the left ventricular developed pressure (LVDP), the left ventricular end‑systolic interior dimension (LVIDs) and the left ventricular end diastolic interior dimension (LVIDd). ELISA kits were used to analyze malondialdehyde (MDA), superoxide dismutase (SOD), tumor necrosis factor‑α (TNF‑α) and interleukin (IL)‑6 levels, NO production and caspase‑3 activity. Nuclear factor (NF)‑κB, ascular endothelial growth factor A (VEGFA), angiotensin (Ang)‑I, phosphorylated (p)‑endothelial nitric oxide synthase protein expression was analyzed using western blot analysis. Puerarin significantly reduced the myocardial infarct area, and increased left ventricular developed pressure in diabetic rats with myocardial I/R. Oxidative stress, inflammation and nuclear factor‑κB protein expression were significantly reduced by puerarin. Furthermore, puerarin activated the protein expression levels of VEGFA and Ang‑I, and increased nitric oxide production, phosphorylated‑endothelial nitric oxide synthase protein expression and caspase‑3 activity. These results demonstrated that the myocardial protective effect of puerarin serves to reduce myocardial I/R injury, via upregulation of VEGFA/Ang‑1 and suppression of apoptosis, in diabetic rats with myocardial I/R.

Neutrophil affinity for PGP and HAIYPRH (T7) peptide dual-ligand functionalized nanoformulation enhances the brain delivery of tanshinone IIA and exerts neuroprotective effects against ischemic stroke by inhibiting proinflammatory signaling pathways

A great challenge to the therapy of ischemic stroke is the poor physicochemical properties and inability of the drug to cross the blood–brain barrier (BBB).

Hydrogen protects against liver injury during CO2 pneumoperitoneum in rats

The aim of the current study was to identify the protective effect of hydrogen gas against liver injury during CO₂ pneumoperitoneum. Rats were randomly divided into three groups: control group (C group), pneumoperitoneum group (P15 group) and hydrogen group (H₂ group). Rats in the C group were subjected to anesthesia for 90 min. Rats in the P15 group received an abdominal insufflation of CO₂ for 90 min at an intra-abdominal pressure of 15 mmHg. Rats in the H₂ group received a hypodermic injection of hydrogen gas (0.2 mL/kg) and after 10 min they received an abdominal insufflation of CO₂ for 90 min at an intra-abdominal pressure of 15 mmHg. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured to evaluate liver function. Malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione (GSH) content were measured to evaluate oxidative stress. Nuclear factor E2-related factor 2 (Nrf2) and Nrf2 downstream target genes, apoptosis-related genes and inflammatory cytokine mRNA and protein expression were detected. Liver injury was detected under the microscope. Our results revealed that liver function, antioxidants content, inflammation and liver injury were improved after hydrogen preconditioning in H₂ group compared with P15 group. Overall, our results revealed that subcutaneous hydrogen injection could exert a protective effect against liver injury during CO₂ pneumoperitoneum through reducing oxidative stress, cell apoptosis and inflammatory cytokines release.

Ferrosenescence: The iron age of neurodegeneration?

Aging has been associated with iron retention in many cell types, including the neurons, promoting neurodegeneration by ferroptosis. Excess intracellular iron accelerates aging by damaging the DNA and blocking genomic repair systems, a process we define as ferrosenescence. Novel neuroimaging and proteomic techniques have pinpointed indicators of both iron retention and ferrosenescence, allowing for their early correction, potentially bringing prevention of neurodegenerative disorders within reach. In this review, we take a closer look at the early markers of iron dyshomeostasis in neurodegenerative disorders, focusing on preventive strategies based on nutritional and microbiome manipulations.