Free Radical Biology and Medicine最新文献

Acute hyperbaric stress during diving combines increased ambient pressure, hyperoxia, hemodynamic shifts, and often muscular workload. Identifying real-time blood biomarkers sensitive to these individual and combined physiological loads remains a challenge. Neuregulin-4 (NRG4), an adipokine secreted by thermogenic and subcutaneous white fat, responds to adrenergic stimulation and modulates redox homeostasis. We investigated NRG4 dynamics alongside oxidative protein carbonyls in divers in warm (thermoneutral) water (∼33.6 °C ambient water temperature) to avoid cold stress. Two field campaigns were conducted: a first depth response campaign involved divers exposed to 20, 30, or 40 m on separate days, without exercise, with serial blood sampling; a second physical effort study involved 15 m dives with or without slow-pedalling exercise. Serum NRG4 was quantified by ELISA and expressed as log₂ fold change relative to baseline. Protein carbonyls were measured as markers of oxidative damage. Statistical analysis employed single-sample tests and false-discovery rate control. NRG4 exhibited a robust early increase at 30 m, significant after correction, and nominal elevations at 40 m, but remained unchanged at 20 m. Exercise at 15 m triggered a significant early NRG4 rise absent during passive dives at the same depth. Protein carbonyls remained stable in early post-emersion windows but increased significantly at later time points (180- and 240-min post-emersion) following dives to 40 m, indicating delayed oxidative burden. Our findings position NRG4 as a fast, pressure- and workload-responsive biomarker of diving stress, temporally distinct from classical oxidative injury markers that manifest later. This temporal dissociation underscores the potential of NRG4 for real-time monitoring of acute physiological load during hyperbaric exposure, integrating pressure- and workload-related stressors.

Adults of Schistosoma mansoni reside in the mesenteric veins, where they are naturally exposed to high levels of hydrogen sulfide (H₂S). S. mansoni and other intestinal parasites have adapted to this sulfide-rich environment, but the evolved mechanisms to metabolize sulfide remain unelucidated. Here we reveal that the putative sulfide:quinone oxidoreductase (SQOR) encoded by S. mansoni is indeed an SQOR, catalyzing the first step of sulfide metabolism. We demonstrated that S. mansoni SQOR (SmSQOR) is expressed in eggs, cercaria and adult stages and localized in the mitochondria. The reaction catalyzed by SmSQOR was investigated using sulfane sulfur probe 4 (SSP4) and shown to require the co-presence of sulfide, quinone, and a sulfur acceptor, indicating a quaternary complex-mediated mechanism. Unlike human and bacterial SQORs, purified SmSQOR could not reduce quinones in the presence of sulfide alone unless sulfite, cyanide, or L-cysteine (but not coenzyme A or glutathione) was provided as the sulfur acceptor. In the presence of these sulfur acceptors, SmSQOR formed a long-lived charge-transfer (CT) complex, a transient electronically coupled association between electron donor and acceptor, as indicated by a broad band around 637-755 nm in the spectrum, which was associated with a partial loss of enzyme activity. Moreover, residues critical for CT complex formation and SQOR catalysis were identified. Using SSP4, we also demonstrated that SQOR was active in S. mansoni adult, egg, and cercaria stages. Taken together, these features suggest that metabolism of sulfide proceeds differently in S. mansoni than in humans.

Small cell lung cancer (SCLC) is an aggressive malignancy characterized by limited therapeutic options. In this study, we identified GL-V9 as a potent anti-SCLC agent that induces apoptosis through oxidative stress. GL-V9 significantly reduced SCLC cell viability in a dose-dependent manner and triggered apoptosis both in vitro and in xenograft models. Mechanistically, GL-V9 increased reactive oxygen species (ROS) levels and lipid peroxidation while impairing mitochondrial function, suggesting that its cytotoxic effects are mediated by oxidative stress. Drug-target interaction analyses revealed that GL-V9 directly binds to STEAP3, a key regulator of iron metabolism, and promotes its degradation via the ubiquitin-proteasome pathway. The loss of STEAP3 disrupted iron homeostasis and exacerbated oxidative stress. In contrast, STEAP3 overexpression attenuated ROS accumulation, mitochondrial damage, and apoptosis both in vitro and in vivo. Further investigation demonstrated that STEAP3 degradation decreased the stability of CISD2, a [2Fe-2S] cluster-containing mitochondrial protein essential for redox balance. GL-V9 downregulated CISD2 in a STEAP3-dependent manner, and restoring CISD2 expression significantly rescued cells from GL-V9-induced oxidative stress and apoptosis. Clinically, both STEAP3 and CISD2 are upregulated in SCLC tumors, and their elevated expression correlates with poor patient survival. Co-expression analysis associated these proteins with pathways involved in oxidative stress and mitochondrial dysfunction. Overall, these findings suggest that GL-V9 induces apoptosis in SCLC by targeting STEAP3 for proteasomal degradation, thereby disrupting the STEAP3-CISD2 axis and promoting oxidative stress-driven cell death. This study identifies a previously unrecognized redox regulatory pathway in SCLC and proposes a potential therapeutic strategy centered on selective induction of oxidative stress.

The distinctive characteristics of diabetic cardiomyopathy (DCM), a serious outcome of diabetes mellitus, are anomalies in the structure and functionality of the cardiac tissue. With a focus on their impact on inflammatory responses, oxidative injury, and the functioning of metabolic enzymes, this investigation aimed to evaluate the cardioprotective benefits of inulin and cichoriin over diabetes-related cardiomyopathy induced by high fat diet-streptozotocin (HFD-STZ) in mice. Diabetes was introduced in male Swiss albino mice by feeding them a high-fat diet followed by STZ injection and treated with cichoriin (50 and 100 mg/kg) or inulin (200 and 400 mg/kg). Serum biochemical, lipid, and cardiac injury markers were estimated. The metabolic enzyme activity (G6Pase, FBPase, ATPase, ENTPDase, 5'NT), oxidative stress markers (SOD, CAT, GSH, MDA, LDH), Angiotensin-Converting Enzyme (ACE) activity, and histological changes in the heart, pancreas, liver, and kidney, were assessed. NF-κB and Nrf2 immunohistochemistry was used to evaluate inflammatory and oxidative signalling. Treatment with inulin and cichoriin, especially at higher dosages, improved ACE activity, normalized metabolic enzyme activities, and substantially restored antioxidant enzyme levels. They reduced hyperglycemia, body weight loss, hyperlipidemia, and heart dysfunction with histological changes and fibrosis brought on by diabetes. Alongside these effects, cardiac tissues showed increased Nrf2 expression and decreased NF-κB, indicating the return of redox equilibrium and myocardial integrity. Thus, cichoriin and inulin substantially ameliorate the DCM by reducing oxidative injury, controlling glucose metabolism, and altering NF-κB/Nrf2 signaling pathways. These results demonstrate their potential for use as natural cardioprotective agents in the treatment of diabetic cardiomyopathy.

Accumulation of amyloid-beta (Aβ₄₂) senile plaques in the brain is a hallmark of Alzheimer's disease (AD). Although some drug have been approvaled recently, none has demonstrated robust disease-modifying outcome. The 3-deoxyanthocyanidins (3-DXA) and their derivatives represent a more stable class of polyphenols, present at uniquely high concentrations in sorghum grains. Although 3-DXA exhibit strong potential to modulate protein aggregation processes, their effects on AD pathology remain 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 fluorescence assay was employed to assess alterations in Aβ₄₂ aggregation, while nuclear magnetic resonance spectroscopy and circular dichroism were used to evaluate compounds-protein interactions and secondary-structure changes. The neuroprotective effects of the three compounds 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 strong disruption of β-sheet structures. All three compounds significantly rescued MC-65 cells from Aβ₄₂-induced toxicity (62-77%), accompanied by enhanced mitochondrial activity. Molecular dynamics simulations analyses further 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.