Free Radical Biology and Medicine最新文献

Alcoholic liver disease (ALD) is a common chronic liver disease worldwide, directly caused by excessive and prolonged alcohol consumption. To date, there are no acknowledged therapeutic approaches for treating ALD. The reason is that ALD pathogenesis is multifactorial and only partially understood. Mitochondrial dysfunction-related mitophagy and inflammation are essential factors that play critical roles in the pathogenesis and progression of ALD. The farnesoid X receptor (FXR), a member of the nuclear receptor superfamily, plays a well-established role in liver protection, but whether and how it counteracts ALD by regulating mitophagy remains unknown. This study aimed to demonstrate the protective effect of FXR overexpression against ethanol-induced liver injury by suppressing NLR family pyrin domain containing 3 (NLRP3) inflammasome activation, thereby promoting mitophagy recovery. The mouse ALD models were established using the DeCarli liquid diet with 5% ethanol (v/v). We established FXR-overexpressing mice by intravenous injection of FXR-mediating lentivirus (LV-FXR). The results revealed that FXR expression was significantly downregulated in liver tissues of ALD patients compared to normal subjects using the Gene Expression Omnibus (GEO) database. FXR overexpression reduced the liver-to-body weight ratio and improved biochemical markers in mice. Overexpression of FXR in mice significantly alleviated ethanol-induced hepatitis, improved mitophagy, and inhibited NLRP3 inflammasome activation and the secretion of IL-18 and IL-1β. In vitro, we transfected AML-12 cells with either pcDNA-FXR or FXR siRNA plasmids before ethanol exposure. Overexpression of FXR markedly attenuated ethanol-induced mitochondrial damage and NLRP3 inflammasome activation. Conversely, FXR knockdown exacerbated both outcomes. In conclusion, FXR overexpression protects against ethanol-induced liver injury through a novel mechanism by suppressing mitochondrial damage, oxidative stress, and NLRP3 inflammasome activation.

Background: Heart failure (HF) is characterized by cardiomyocyte loss. While ferroptosis driven by NOX4 contributes to HF, how autophagy regulates NOX4 stability remains unclear.

Methods: Using in vitro (isoproterenol-induced) and in vivo (TAC-induced) HF models, we combined pharmacological and genetic approaches with co-IP and molecular docking to investigate the autophagy-NOX4 axis.

Results: We identified a novel pathway wherein autophagy activation prompts the receptor NDP52 to bind NOX4 and recruit the E3 ligase ASB2, mediating K48-linked ubiquitination and autophagic degradation of NOX4. This process suppressed ferroptosis and ameliorated cardiomyocyte injury. The NOX4 inhibitor GLX351322, alone or combined with the autophagy activator metformin, conferred significant cardioprotection in vivo.

Conclusion: Our findings reveal the 'autophagy-NDP52-ASB2-NOX4' axis as a crucial mechanism coupling autophagy to ferroptosis in HF, highlighting its therapeutic potential.

Air pollution-induced emphysema is accompanied by changes in pulmonary vasculature, leading to pulmonary hypertension (PH) and ultimately heart failure. Pyrroloquinoline Quinone (PQQ), a potent antioxidant with cardio-protective properties, upregulates mitochondrial biogenesis and functions. Previously, we have shown that PQQ protects against PH; however, the effect of PQQ on emphysema and the mitochondrial dysfunction due to air pollution still remains unexplored. In our study, we unraveled the effect of PQQ on Ultrafine carbon particle (UFCP) induced emphysema and PH. In the in vitro studies, human lung adenocarcinoma epithelial cells (A549 cells) were exposed to UFCP (50 μg/ml) and PQQ (100 μM) for 24 hr, and following this, the redox state and mitochondrial health of the cells were examined. For the in vivo study, SD rats were administered UFCP (100 μg/dose, three times a week, intranasally) and PQQ (2 mg/kg, oral/day) for four weeks. Plethysmography, 2-D Echo, and invasive blood pressure measurement were used to study pulmonary, hemodynamic, and cardiac functions, and metabolic changes were studied by untargeted metabolomics of the lungs. PQQ treatment improved mitochondrial structure, dynamics, and biogenesis and reduced oxidative stress in UFCP-exposed A549 cells. PQQ significantly improved pulmonary functions, inflammation, structure, and muscularization of vessels in UFCP-exposed rats (#p<0.01). Metabolomics study showed improved metabolism in the lungs of PQQ-treated rats. Further, PQQ significantly reduced right ventricular pressure (RVP) and hypertrophy (RVH) in UFCP-exposed rats (#p<0.05). Our findings suggest that improving mitochondrial functions by PQQ preserves alveolar integrity and prevents pulmonary hypertension, and it can be a promising prophylactic, especially for pollution-ridden settings.

Psoriasis is a chronic inflammatory skin disease characterized by keratinocyte hyperproliferation and immune dysregulation. Recent studies highlight ferroptosis, an iron-dependent form of regulated cell death driven by lipid peroxidation, as a key contributor to psoriatic pathogenesis. Lipocalin-2 (LCN2), an iron-binding protein elevated in psoriasis, may regulate this process. We investigated whether bezafibrate (BEZ), a pan-peroxisome proliferator-activated receptor (PPAR) agonist with broad metabolic and anti-inflammatory properties, could ameliorate psoriasis by targeting ferroptosis through LCN2-mediated mechanisms. Our results demonstrated significant ferroptosis activation in psoriatic lesions, characterized by reduced glutathione peroxidase (GPX4) expression, increased acyl-CoA synthetase long-chain family member 4 (ACSL4) and arachidonate 12-lipoxygenase (ALOX12) levels, elevated lipid peroxidation products, and glutathione (GSH) depletion. GPX4 knock-in mice exhibited marked improvement in psoriatic features, confirming ferroptosis involvement. BEZ treatment effectively reduced disease severity, epidermal thickening, and keratinocyte proliferation while restoring redox balance. Lipidomic analysis revealed BEZ reversed imiquimod (IMQ)-induced accumulation of pro-ferroptotic lipids including ceramides, PE(36:4;1O), PE(34:2;1O), and PE(16:0_18:1;O). Pathway analysis showed BEZ downregulated arachidonic acid metabolism while enhancing protective ether lipid and sphingolipid pathways. Importantly, BEZ significantly suppressed LCN2 expression, and LCN2 overexpression abolished BEZ's protective effects against ferroptosis and inflammation in keratinocytes. These findings demonstrate that BEZ alleviates psoriasis by inhibiting ferroptosis through LCN2 suppression and lipid metabolic reprogramming, highlighting the therapeutic potential of pan-PPAR activation as a multifaceted strategy for inflammatory skin disorders.

Prolonged exposure to high altitude (HA) results in a range of systemic changes, some of which, specifically for the heart, particularly cardiac changes, remain difficult to reverse after returning to low altitude. Cardiac de-acclimatization after HA exposure and its underlying mechanisms remain unclear. In this study, mice were subjected to a decompression chamber to simulate a 6000-m altitude exposure for 10 days, followed by the other 10-day de-acclimatization period at a lower altitude of 400 m. The cardiac dysfunction induced by HA exposure persisted throughout the de-acclimatization, accompanied with sustained mitochondrial dysfunction and the short peptide mitochondrial open reading frame of the 12S ribosomal RNA type-c (MOTS-c) deficiency. Exogenous supplementation of MOTS-c during de-acclimatization effectively alleviated the cardiac dysfunction post HA exposure. Mechanistically, MOTS-c activated the PTEN-induced putative kinase 1 (Pink1) / Parkin pathway, promoting mitophagy and improving mitochondrial quality. Silencing Pink1 abolished the protective effects of MOTS-c during de-acclimatization. Additionally, reduced circulating MOTS-c levels were observed in patients with high altitude heart disease and acute coronary syndrome. These results suggest that HA exposure leaves a memory of cardiac dysfunction upon return to lower altitude. This is attributed to a sustained deficiency in MOTS-c. MOTS-c maintains mitochondrial quality through promoting mitophagy, highlighting its therapeutic potential for treating HA-induced cardiac dysfunction during de-acclimatization.

Resveratrol (Res), a natural polyphenol, is widely used as a functional food additive and food preservative due to its antioxidant and anti-inflammatory properties. However, its protective role against drug-induced organ damage, particularly colistin-induced nephrotoxicity (CIN), remains underexplored. This study investigated Res's protective effects and mechanisms against CIN in rat and NRK-52E cells. In vivo, Res (5-20 mg/kg) significantly improved renal function, alleviated histopathological damage, and restored antioxidant status. Mechanistically, Res modulated the Keap1/Nrf2 axis, suppressing excessive Nrf2 activation and its downstream enzymes. Concurrently, Res inhibited ferroptosis by reducing iron accumulation and modulating key ferroptosis markers (GPX4, ACSL4). In vitro, Res (20 μM) reversed CS- and RSL3-induced cytotoxicity, lipid peroxidation, and ferrous iron overload; Nrf2 siRNA abrogated these effects, confirming Nrf2's essential role. These findings highlight Res as a promising strategy to enhance colistin's clinical safety through precise Nrf2 modulation and ferroptosis inhibition, underscoring the therapeutic potential of natural food compounds.

Cyclometallated gold(III) compounds were evaluated for their chemoselective capability to promote C-Se coupling reactions under biocompatible conditions. Competitive reactions with selenium and sulfur substrates highlighted the preference for selenium, and this selectivity was further confirmed in selenopeptide models mimicking the GPx active site. Given that thioredoxin reductase (TXNRD1) is a canonical target for gold compounds, we confirmed that our complexes also inhibit this enzyme, with the two six-membered metallacycles exhibiting a higher potency than auranofin. Expanding beyond TXNRD1, the compounds were further investigated as inhibitors of other selenoenzymes, specifically glutathione peroxidase isoenzymes (GPx1, GPx4). The metallacycles were potent inhibitors of GPx1, while in vitro GPx4 inhibition was overall less pronounced, with LC/MS studies identifying selenocysteine (Sec51) as the primary arylation site on GPx1. We demonstrated that this chemoselectivity could be translated to an intracellular setting. The selectivity towards Se was further explored using A375 GPx4 WT and A375 GPx4 U46C mutant cell lines, where proliferation assays showed a greater effect in the GPx4 WT cells. By integrating structural and functional insights across selenoenzyme families, this study reveals glutathione peroxidases as pivotal molecular targets of cyclometallated gold(III) compounds and lays the groundwork for designing selective Sec-targeting metallodrugs, an approach with untapped potential in anticancer therapy.

Sepsis-induced acute lung injury (ALI) remains a devastatingly lethal clinical syndrome driven by aberrant inflammatory dysregulation, wherein monocytes play critical roles in disease pathogenesis. This study elucidates the mechanistic basis by which the HO-1 inducer Hemin alleviates ALI by activating the HO-1/Nrf2 pathway to target pro-inflammatory monocytes. RNA-seq analysis revealed that the most prominently dysregulated genes in LPS-stimulated human THP-1 monocytes (relative to untreated controls) were predominantly enriched in pathways governing inflammatory responses and oxidative stress. In vitro experiments revealed that Hemin suppressed the p38-MAPK/mTOR pathways in human monocytes, inhibiting inflammatory activation, differentiation, and LPS-induced cell death while preserving phagocytosis. The murine ALI model was established in WT, CCR2^-/-, and Nrf2^-/- mice via tail vein injection of LPS, with assessments conducted 12 hours later. In LPS-challenged mice, Hemin pretreatment selectively inhibited the recruitment of CCR2^hi monocytes (but not CCR2^lo monocytes or neutrophils) into the lungs, thereby attenuating histopathological injury, reducing TNF-α and IL-6 levels, and diminishing monocyte-derived macrophages and their M1/M2 polarization. CCR2 deficiency not only abrogated the therapeutic efficacy of Hemin in ALI, evidenced by the failure to prevent the LPS-induced increase in the proportion of monocyte-derived macrophages and the elevation of macrophage polarization, but also paradoxically elevated pulmonary TNF-α concentrations. Furthermore, experiments using Nrf2^-/- mice revealed that the protective benefits of Hemin are strictly Nrf2-dependent. Nrf2 deficiency prevented Hemin from restoring the redox balance (GSH/GSSG ratio) and abolished its systemic and pulmonary anti-inflammatory effects, along with its suppression of CCR2^hi subsets and inhibition of macrophages polarization. Collectively, our findings establish that activation of the HO-1/Nrf2 pathway mitigates ALI by selectively targeting CCR2^hi pro-inflammatory monocytes, positioning Hemin as a promising therapeutic candidate for ALI and identifying the proportion of CCR2^hi monocyte and Nrf2-mediated redox markers as potential biomarkers to guide precision medicine strategies for ALI management.

Intrauterine adhesion (IUA) is characterized by the formation of endometrial fibrosis within the uterine cavity, which can lead to thin endometrium, hypomenorrhea, infertility, and recurrent abortion, exerting a detrimental impact on women's physical and psychological health. Currently, its pathogenesis is not fully elucidated, absence of effective therapies and coupled with a high recurrence rate. In this study, single-cell RNA sequencing was applied for the first time to a mouse IUA model, revealing significant changes in the expression of senescence markers in endometrial epithelial cells (EECs). Specifically, upregulation of Cdkn1a, and Il6, and downregulation of Lamin B1. Further bioinformatic analysis showed significant enrichment of gene sets related to calcium overload, ER stress, and Endoplasmic Reticulum/Plasma Membrane (ER/PM) contacts in the EECs of IUA mice. Mechanistically, ER/PM contacts in IUA activates the STIM1/Orai1 channel complex, leading to ER stress and intracellular calcium overload, which induces cellular senescence in EECs and ultimately drives IUA progression. Intrauterine administration of the STIM1/Orai1 channel inhibitor BTP2 significantly suppressed ER/PM contacts-induced senescence in EECs and effectively alleviated endometrial fibrosis in the mouse IUA model. In conclusion, targeting the STIM1/Orai1 calcium channel dependent on ER/PM contact sites significantly ameliorates endometrial fibrosis, offering a promising therapeutic strategy for IUA.

Background: D-ribose, a highly reducing pentose sugar, can be phosphorylated by ribokinase (RBKS) to form ribose-5-phosphate (R-5-P). Elevated urinary D-ribose levels have been reported in patients with type 2 diabetes mellitus (T2DM) and Alzheimer's disease, implicating its potential role in disease pathogenesis. Previous investigations into D-ribose cytotoxicity have primarily focused on its non-enzymatic glycation activity, while alternative mechanisms remain underexplored. Since hemoglobin is a major in vivo target of glycation, this study utilized K562 cells-which retain inducible hemoglobin expression-to examine additional cytotoxic mechanisms of D-ribose.

Methods and results: CCK-8 assays demonstrated that D-ribose inhibited K562 cell proliferation in a concentration- and time-dependent manner, and this inhibitory effect was significantly enhanced in hemin-induced differentiated K562 cells. Conversely, RBKS overexpression promoted proliferation and alleviated oxidative stress in K562 cells. Transcriptomic analysis revealed that differentially expressed genes in D-ribose-treated cells were enriched in mineral absorption and oxidative phosphorylation pathways (KEGG), as well as in biological processes related to copper ion homeostasis (GO). RT-qPCR confirmed that both D-ribose treatment and RBKS knockout downregulated key copper homeostasis genes (e.g., SLC31A1, MT1F, ATOX1) and mitochondrial respiratory chain genes (e.g., COX17, COX11, MTATP8, MTND6), and were accompanied by a significant reduction in intracellular free copper levels.

Conclusions: These findings reveal a novel cytotoxic mechanism mediated by the RBKS-copper-oxidative phosphorylation axis in D-ribose-treated K562 cells, providing key insights into the intracellular role of D-ribose.