Free Radical Biology and Medicine最新文献

The accumulation of amyloid-beta (Aβ₄₂) plaques is a hallmark of Alzheimer's disease (AD), which currently have no cure. The 3-deoxyanthocyanidins (3-DXA) and their derivatives represent a more stable class of polyphenols, identified in sorghum grains at uniquely high concentrations. Although 3-DXA exhibit strong potential to modulate protein aggregation processes, their effects on AD pathology remain largely unexplored. In this study, we investigated the inhibitory effects of three 3-DXA derivatives apigeninidin chloride (AC), luteolinidin chloride (LC), and 7-methoxy apigeninidin (7-MAC) on Aβ₄₂ aggregation and associated neurotoxicity. Thioflavin T (ThT) fluorescence assay was employed to assess alterations in Aβ₄₂ aggregation, while circular dichroism and nuclear magnetic resonance spectroscopy were used to evaluate changes in secondary structure. The neuroprotective effects of the 3-DXA derivatives were further examined in MC-65 cells under Aβ-induced toxicity. Additionally, generalized replica exchange with solute tempering based molecular dynamics simulations was conducted to explore the effects of AC and LC on Aβ₄₂ dimer stability and β-sheet disruption. Our findings demonstrate that AC, LC, and 7-MAC significantly reduced Aβ₄₂ aggregation by up to 88%, with AC and LC showing particularly strong disruption of β-sheet structures. All three compounds significantly rescued MC-65 cells from Aβ₄₂-induced toxicity (62-77%) and enhanced mitochondrial activity. Molecular dynamics simulations analyses revealed that AC and LC disrupted hydrophobic interactions within Aβ₄₂ dimers, contributing to destabilisation of neurotoxic aggregates. Overall, AC and LC exhibited strong multitarget activity against AD pathology by inhibiting Aβ42 aggregation, restoring intracellular energy balance, and disrupting key neurotoxic structural motifs.

Introduction: Doxorubicin (DOX) is a widely used chemotherapeutic agent, but its clinical application is limited by dose-dependent cardiotoxicity. Currently, there are no effective strategies to prevent or reverse DOX-mediated myocardial injury, highlighting the urgent need for novel therapeutic approaches.

Objectives: In this study, the cardioprotective effects of crocin, a natural compound derived from Crocus sativus, were investigated in the context of DOX-mediated cardiotoxicity.

Methods: Cardiac function, mitochondrial morphology, ROS production, and ATP content were evaluated in both in vitro and in vivo models of DOX-mediated cardiotoxicity. RNA sequencing was performed to identify key regulatory pathways affected by crocin. Mitophagy-related mechanisms were investigated through molecular and cellular assays, including immunofluorescence and Western blot analysis of PTEN-induced kinase 1 (PINK1)-associated signaling. PINK1 knockdown and mitophagy inhibition were performed to assess the impact on the cardioprotective effects of crocin.

Results: Crocin treatment preserved cardiac function and mitigated DOX-mediated myocardial injury in both in vitro and in vivo models, as evidenced by restored left ventricular ejection fraction, reduced mitochondrial ROS accumulation, restoration of ATP production, and improved mitochondrial morphology. Transcriptomic analysis revealed that crocin upregulated PINK1 expression, a key initiator of mitophagy. Functional assays further confirmed that crocin restored mitophagy activity suppressed by DOX exposure. The cardioprotective effects of crocin were abolished upon PINK1 knockdown or mitophagy inhibitor, highlighting the essential role of PINK1-dependent mitophagy in mediating crocin's effects.

Conclusions: Crocin protects against doxorubicin-induced cardiotoxicity by activating PINK1-mediated mitophagy and maintaining mitochondrial homeostasis. These findings highlight crocin as a potential therapeutic agent for mitigating DOX-mediated cardiotoxicity.

Background: Diabetic cognitive impairment (DCI) is an increasingly recognized complication of type 2 diabetes mellitus (T2DM) with limited effective therapies. Short-chain fatty acids (SCFAs) have been implicated in metabolic regulation and neuronal health, yet comparisons of acetate, propionate, butyrate, and their mixture are limited, and the mechanisms underlying neuroprotection in DCI remain insufficiently clarified.

Methods: Ninety participants (healthy controls, T2DM, and DCI groups) were assessed for serum SCFA levels and cognitive performance using the Montreal Cognitive Assessment (MoCA). In parallel, a DCI mouse model established by a 24-week high-fat diet received 8-week supplementation with acetate, propionate, butyrate, or a mixture of the three. Glucolipid metabolism, spatial learning and memory, hippocampal neuronal damage, neuroinflammation, and mitophagy were evaluated. Based on consistency across the clinical and animal datasets, acetate was selected for mitophagy-focused mechanistic experiments, and pathway dependence was examined by co-administration of the autophagy inhibitor 3-methyladenine (3-MA).

Results: Clinically, serum acetate, propionate, and butyrate were lower in T2DM and DCI than in healthy controls; only acetate showed a further significant reduction in DCI compared with T2DM. All three SCFAs were positively associated with MoCA score and inversely associated with fasting blood glucose, whereas acetate additionally showed inverse associations with lipid parameters. In mice, SCFA supplementation alleviated metabolic dysfunction, spatial learning and memory, neuronal loss, and neuroinflammation, with acetate generally producing more consistent and numerically greater improvements across these endpoints. Mechanistically, acetate enhanced hippocampal mitophagy by restoring LC3-TOMM20 colocalization and activating the PINK1/Parkin pathway. Importantly, 3-MA partially attenuated these benefits, indicating a mitophagy-dependent mechanism.

Conclusions: These integrated clinical and experimental data support a "SCFAs-mitophagy-neuroinflammation" axis linking systemic metabolism to neuronal vulnerability in DCI, and identify acetate as a promising SCFA that may enhance neuronal resilience through mitophagy activation.

Mycobacterium tuberculosis (Mtb) Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is indispensable for glycolysis, it also performs several critical non-metabolic functions. In the present study, we demonstrate that CRISPRi silencing of GAPDH inhibited enzyme activity and iron acquisition via human transferrin (Tf)/lactoferrin (Lf). GAPDH silencing also enhanced reactive oxygen species (ROS) and ROS induced damage suggesting its role as a redox sensor. We then examined the impact of GAPDH inhibition in Mtb using small molecule inhibitors. Vitamin C (VC) was selected considering its potent bactericidal effects against Mtb and its inhibition of human GAPDH resulting in its efficacy against cancer cells. The GAPDH inhibitors Ethyl bromopyruvate (EBP) and Koningic acid (KA) are anti-cancer agents that target the glycolytic activity of GAPDH. In contrast, TCH346 was identified as a neuroprotective agent, wherein it targets the non-metabolic function of GAPDH induced apoptotic signalling. The effects of inhibitors, alone or in combination with VC mirrored the cellular effects of GAPDH silencing, resulting in significant anti-bacterial activity. VC induced iron mobilization which coupled with GAPDH inhibitors induced a veritable "double whammy" resulting in massive increase in ROS and downstream effects. The efficacy of these treatments was assessed in a murine model, confirming that VC augmented the potent anti-tubercular activity induced by EBP and TCH346. Overall, this study identifies the crucial function of Mtb GAPDH as a redox sensor and highlights the potential of targeting its pleiotropic cellular functions towards drug discovery. In addition, the efficacy of TCH346 provides an opportunity of drug-repurposing as a strategy for therapy.

Introduction: Epidemiological studies have demonstrated higher incidence and mortality rate of nonalcoholic steatohepatitis (NASH) in the elderly population than in younger groups. However, the mechanisms underlying this age-related exacerbation remain poorly understood.

Objective: This study aimed to elucidate the specific pathways through which aging exacerbates NASH progression, using an integrated in vivo and in vitro model.

Methods: Aged (18-month-old) and young (6-week-old) mice were fed a high-fat diet (HFD) for 16 weeks to induce NASH. A senescence-associated cellular model of NASH was established by co-treating murine hepatocyte AML-12 with H₂O₂ and free fatty acid (FFA). Gene expression profiling of liver tissue was performed using RNA sequencing to identify molecular signatures. Interventions were as follows: (1) In vitro, BMAL1 overexpression plasmids were transfected into AML-12 cells, followed by treatment with 2-deoxy-D-glucose (2-DG, a glycolysis inhibitor) and 2-methoxyestradiol (2-ME2, a HIF-1α inhibitor); (2) in vivo, hepatocyte-specific BMAL1 overexpression was achieved in aged HFD-fed mice through adeno-associated virus serotype 8 (AAV8) delivery. Mechanism validation was performed using biochemical assays, Western blot, cell staining, molecular docking, and Co-IP.

Results: Aged HFD-fed mice exhibited more severe NASH phenotypes than young mice. Transcriptomic analysis identified NLRP3-related signaling and circadian rhythm pathways as central contributors to age-specific NASH pathogenesis. These mice also exhibited elevated NLRP3 inflammasome activity, enhanced glycolysis, and reduced BMAL1 expression. In senescent NASH cells, BMAL1 overexpression along with 2-DG or 2-ME2 treatment significantly downregulated NLRP3 expression and attenuated lipid accumulation, inflammation, oxidative stress, and fibrosis. Mechanistically, BMAL1 directly bound to HIF-1α, thereby suppressing glycolysis. Hepatocyte-specific BMAL1 overexpression in aged HFD-fed mice markedly inhibited glycolysis and NLRP3 activation, resulting in an improvement in NASH-related pathologies.

Conclusion: This study revealed a novel mechanism in which BMAL1 downregulation under aging and HFD conditions promotes NASH progression by binding to HIF-1α and modulating the glycolysis-NLRP3 inflammasome axis.

Extrusion of damaged mitochondria is emerging as a trigger of innate immune activation. Parkinson's disease (PD), characterized by profound mitochondrial dysfunction, may involve similar mechanisms. Here, we report that dopaminergic neurons release damaged mitochondria into the extracellular space in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. These neuron-derived mitochondria were subsequently engulfed by glial cells, eliciting robust inflammatory responses. Autophagy inhibition did not affect mitochondrial release, indicating a non-canonical extrusion pathway. Upon mitochondrial damage, Rab27a and Rab27b translocated to the outer mitochondrial membrane, mediating mitochondrial export from dopaminergic neurons. Conditional Rab27 knockdown in dopaminergic neurons reduced extracellular mitochondrial accumulation, microglial activation, antiviral signaling, and dopaminergic neurodegeneration. Together, these findings identify Rab27-dependent mitochondrial extrusion as a critical mechanism coupling dopaminergic neuronal injury to neuroinflammation and neurodegeneration in PD.

Myocardial infarction (MI) stands as a leading contributor to global cardiovascular morbidity and mortality, defined by ischemic myocardial cell death and subsequent impairment of cardiac function. The tripartite motif (TRIM) protein family has been shown to regulate myocardial ischemia-reperfusion injury. As a key member of the TRIM protein family, tripartite motif-containing protein 28 (TRIM28) exhibits dysregulated expression in the heart during MI yet its pathophysiological role remains to be fully elucidated. This study aimed to investigate the functional roles and underlying mechanisms of TRIM28 in MI. We observed a significant upregulation of TRIM28 in ischemic myocardium and hypoxic cardiomyocytes. Genetic knockout of TRIM28 ameliorated cardiac function and attenuated apoptosis in MI mice, whereas its overexpression exacerbated contractile dysfunction, and promoted cardiomyocyte apoptosis and mitochondrial injury. Mechanistically, TRIM28 directly interacts with activating transcription factor 5 (ATF5) and suppresses its SUMOylation, thereby enhancing the ubiquitin-mediated degradation of ATF5, inhibiting the mitochondrial unfolded protein response (UPRmt), and ultimately culminating in increased apoptosis. Via molecular docking, we identified a TRIM28-targeting compound, Oolonghomobisflavan B (OFB), which attenuated post-MI apoptosis and facilitated cardiac function recovery. Collectively, these findings demonstrate that TRIM28 acts as a critical regulator of MI progression, and OFB holds therapeutic potential as a candidate drug.

Metformin (Met), a first-line therapeutic agent for type 2 diabetes, has been widely recognized for its antifibrotic properties in various pathological conditions. However, its effects on hypertrophic scars (HS) and the underlying mechanisms remain insufficiently explored. The present study aimed to elucidate the role of metformin in HS and to investigate its associated molecular mechanisms. Both in vitro and in vivo experiments demonstrated that metformin markedly inhibited the proliferation, migration, and collagen deposition of hypertrophic scar fibroblasts (HSFs), and alleviated HS formation in a rabbit ear model. Mechanistic investigations further revealed that these effects were closely associated with the downregulation of ribonucleotide reductase regulatory subunit M2 (RRM2). Notably, reduced RRM2 expression suppressed the production of glutathione synthetase (GSS), thereby impairing glutathione (GSH) synthesis. This, in turn, indirectly downregulated glutathione peroxidase 4 (GPX4), leading to the intracellular accumulation of peroxides and triggering ferroptosis in vivo and in vitro. Collectively, these findings suggest that metformin may attenuate HS fibrosis by inducing HSFs ferroptosis through the RRM2/GSS/GPX4 signaling axis. This study not only expands the potential clinical application of metformin in the treatment of skin fibrosis but also provides a theoretical foundation for the development of novel anti-scar therapeutics.

The cutaneous tissue is persistently exposed to environmental stressors, including a wide range of airborne pollutants. This chronic exposure often leads to a condition of oxidative stress, with the outermost layer of epidermis, the stratum corneum (SC), being especially vulnerable due to its high lipid content. Notably, approximately 40 % of SC lipids consist of cholesterol, present in both esterified and unesterified forms. The oxidative imbalance induced by environmental stressors and constantly associated with inflammatory skin diseases promotes the formation and accumulation of cholesterol oxidation products, belonging to the oxysterols' family, which are known for their potent pro-oxidant and pro-inflammatory properties. In addition, harmful oxysterols of dietary origin could reach the epidermis via the vascularized dermis, thus adding another route of exposure. 7β-Hydroxycholesterol (7βOHC) and 7-ketocholesterol (7 KC), two highly toxic oxysterols of non-enzymatic origin, have been shown to significantly downregulate proteins involved in adherens and tight junctions in the intestinal epithelium. Given the structural similarity of extracellular junction proteins across tissues, it is reasonable to expect that oxysterols may similarly disrupt the integrity of the epidermal barrier. To investigate this, supraphysiologic concentrations of 7 KC and 7βOHC were added to the medium of human keratinocytes. Immunofluorescence analysis revealed a consistent and significant reduction in the levels of Claudin-1, Zonulin-1 (ZO1), and E-cadherin, key proteins of tight and adherens junctions, respectively, in oxysterol-treated cells compared to controls. Notably, oxysterol exposure also led to a reduction of mitochondrial membrane potential and an increased mitochondrial reactive oxygen species (ROS) production. Both mitochondrial damage and the disruption of skin junctions were efficiently prevented by mitoTEMPO, a selective mitochondrial superoxide scavenger, suggesting the pro-oxidant activity of oxysterols mediates these effects in keratinocytes. Finally, experiments conducted using a 3D skin model corroborated findings observed in keratinocyte cultures, reinforcing the role of oxysterols in compromising the skin barrier integrity.