T-2 toxin induces cardiac fibrosis by causing metabolic disorders and up-regulating Sirt3/FoxO3α/MnSOD signaling pathway-mediated oxidative stress.

T-2 toxin, an omnipresent environmental contaminant, poses a serious risk to the health of humans and animals due to its pronounced cardiotoxicity. This study aimed to elucidate the molecular mechanism of cardiac tissue damage by T-2 toxin. Twenty-four male Sprague-Dawley rats were orally administered T-2 toxin through gavage for 12 weeks at the dose of 0, 10, and 100 nanograms per gram body weight per day (ng/(g·day)), respectively. Morphological, pathological, and ultrastructural alterations in cardiac tissue were meticulously examined. Non-targeted metabolomics analysis was employed to analyze alterations in cardiac metabolites. The expression of the Sirt3/FoxO3α/MnSOD signaling pathway and the level of oxidative stress markers were detected. The results showed that exposure to T-2 toxin elicited myocardial tissue disorders, interstitial hemorrhage, capillary dilation, and fibrotic damage. Mitochondria were markedly impaired, including swelling, fusion, matrix degradation, and membrane damage. Metabonomics analysis unveiled that T-2 toxin could cause alterations in cardiac metabolic profiles as well as in the Sirt3/FoxO3α/MnSOD signaling pathway. T-2 toxin could inhibit the expressions of the signaling pathway and elevate the level of oxidative stress. In conclusion, the T-2 toxin probably induces cardiac fibrotic impairment by affecting amino acid and choline metabolism as well as up-regulating oxidative stress mediated by the Sirt3/FoxO3α/MnSOD signaling pathway. This study is expected to provide targets for preventing and treating T-2 toxin-induced cardiac fibrotic injury.

DVL/GSK3/ISL1 pathway signaling: unraveling the mechanism of SIRT3 in neurogenesis and AD therapy.

BACKGROUND: The established association between Alzheimer's disease (AD) and compromised neural regeneration is well-documented. In addition to the mitigation of apoptosis in neural stem cells (NSCs), the induction of neurogenesis has been proposed as a promising therapeutic strategy for AD. Our previous research has demonstrated the effective inhibition of NSC injury induced by microglial activation through the repression of oxidative stress and mitochondrial dysfunction by Sirtuin 3 (SIRT3). Nonetheless, the precise role of SIRT3 in neurogenesis remains incompletely understood. METHODS: In vivo, SIRT3 overexpression adenovirus was firstly injected by brain stereotaxic localization to affect the hippocampal SIRT3 expression in APP/PS1 mice, and then behavioral experiments were performed to investigate the cognitive improvement of SIRT3 in APP/PS1 mice, as well as neurogenic changes in hippocampal region by immunohistochemistry and immunofluorescence. In vitro, under the transwell co-culture condition of microglia and neural stem cells, the mechanism of SIRT3 improving neurogenesis of neural stem cells through DVL/GSK3/ISL1 axis was investigated by immunoblotting, immunofluorescence and other experimental methods. RESULTS: Our findings indicate that the overexpression of SIRT3 in APP/PS1 mice led to enhanced cognitive function and increased neurogenesis. Additionally, SIRT3 was observed to promote the differentiation of NSCs into neurons during retinoic acid (RA)-induced NSC differentiation in vitro, suggesting a potential role in neurogenesis. Furthermore, we observed the activation of the Wnt/ß-catenin signaling pathway during this process, with Glycogen Synthase Kinase-3a (GSK3a) primarily governing NSC proliferation and GSK3ß predominantly regulating NSC differentiation. Moreover, the outcomes of our study demonstrate that SIRT3 exerts a protective effect against microglia-induced apoptosis in neural stem cells through its interaction with DVLs. CONCLUSIONS: Our results show that SIRT3 overexpressing APP/PS1 mice have improved cognition and neurogenesis, as well as improved neurogenesis of NSC in microglia and NSC transwell co-culture conditions through the DVL/GSK3/ISL1 axis.

Elucidating the Role of Sirtuin 3 in Mammalian Oocyte Aging.

The field of reproductive biology has made significant progress in recent years, identifying specific molecular players that influence oocyte development and function. Among them, sirtuin 3 (SIRT3) has attracted particular attention for its central role in mediating mitochondrial function and cellular stress responses in oocytes. So far, studies have demonstrated that the knockdown of SIRT3 leads to a decrease in blastocyst formation and an increase in oxidative stress within an embryo, underscoring the importance of SIRT3 in maintaining the cellular redox balance critical for embryonic survival and growth. Furthermore, the literature reveals specific signaling pathways, such as the SIRT3- Glycogen synthase kinase-3 beta (GSK3ß) deacetylation pathway, crucial for mitigating oxidative stress-related anomalies in oocyte meiosis, particularly under conditions like maternal diabetes. Overall, the emerging role of SIRT3 in regulating oocyte mitochondrial function and development highlights the critical importance of understanding the intricate connections between cellular metabolism, stress response pathways, and overall reproductive health and function. This knowledge could lead to the development of novel strategies to support oocyte quality and fertility, with far-reaching implications for assisted reproductive technologies and women's healthcare. This commentary aims to provide an overview of the importance of SIRT3 in oocytes by synthesizing results from a multitude of studies. The aim is to elucidate the role of SIRT3 in oocyte development, maturation, and aging and to identify areas where further research is needed.

LINC00887 promotes GCN5-dependent H3K27cr level and CRC metastasis via recruitment of YEATS2 and enhancing ETS1 expression.

Recent observations have revealed upregulation of H3K27cr in colorectal cancer (CRC) tissues; however, the underlying cause remains elusive. This study aimed to investigate the mechanism of H3K27cr upregulation and its roles in CRC metastasis. Clinically, our findings showed that H3K27cr served as a highly accurate diagnostic marker to distinguish CRC tissues from healthy controls. Elevated levels of LINC00887 and H3K27cr were associated with a poorer prognosis in CRC patients. Functionally, LINC00887 and H3K27cr facilitated the migration and invasion of CRC cells. Mechanistically, LINC00887 interacted with SIRT3 protein. Overexpressed of LINC00887 obstructed the enrichment of SIRT3 within GCN5 promoter, thereby elevating H3K27ac but not H3K27cr level within this region, subsequently activating GCN5 expression. This activation increased the global level of H3K27cr, promoting the enrichment of GCN5, H3K27cr, and YEATS2 within ETS1 promoter, activating ETS1 transcription and ultimately promoting the metastasis of CRC. The in vivo study demonstrated that inhibition of LINC00887 suppressed CRC metastasis, but this inhibitory effect was nullified when mice were treated with NaCr. In conclusion, our results confirmed the diagnostic biomarker potential of H3K27cr in individuals with CRC, and proposed a functional model to elucidate the involvement of LINC00887 in promoting CRC metastasis by elevating H3K27cr level.

Empagliflozin alleviates obesity-related cardiac dysfunction via the activation of SIRT3-mediated autophagosome formation.

BACKGROUND: Empagliflozin (EMPA) has demonstrated efficacy in providing cardiovascular benefits in metabolic diseases. However, the direct effect of EMPA on autophagy in obesity-related cardiac dysfunction remains unclear. Therefore, this study aimed to determine changes in cardiac autophagy during diet-induced obesity and clarify the exact mechanism by which EMPA regulates autophagic pathways. METHODS: Male C57BL/6J mice were fed a 12-week high-fat diet (HFD) followed by 8 weeks of EMPA treatment. Body composition analysis and echocardiography were performed to evaluate metabolic alterations and cardiac function. Histological and immunofluorescence staining was used to evaluate potential enhancements in myocardial structure and biological function. Additionally, H9c2 cells were transfected with small interfering RNA targeting sirtuin 3 (SIRT3) and further treated with palmitic acid (PA) with or without EMPA. Autophagy-related targets were analyzed by western blotting and RT‒qPCR. RESULTS: EMPA administration effectively ameliorated metabolic disorders and cardiac diastolic dysfunction in HFD-fed mice. EMPA prevented obesity-induced myocardial hypertrophy, fibrosis, and inflammation through the activation of SIRT3-mediated autophagosome formation. The upregulation of SIRT3 triggered by EMPA promoted the initiation of autophagy by activating AMP-activated protein kinase (AMPK) and Beclin1. Furthermore, activated SIRT3 contributed to the elongation of autophagosomes through autophagy-related 4B cysteine peptidase (ATG4B) and autophagy-related 5 (ATG5). CONCLUSIONS: EMPA promotes SIRT3-mediated autophagosome formation to alleviate damage to the cardiac structure and function of obese mice. Activated SIRT3 initiates autophagy through AMPK/Beclin1 and further stimulates elongation of the autophagosome membrane via ATG4B/ATG5. These results provide a new explanation for the cardioprotective benefits of EMPA in obesity.

Cynaroside regulates the AMPK/SIRT3/Nrf2 pathway to inhibit doxorubicin-induced cardiomyocyte pyroptosis. / 木犀草苷通过调节AMPK/SIRT3/Nrf2é€šè·¯æŠ‘åˆ¶é˜¿éœ‰ç´ è¯±å¯¼çš„å¿ƒè‚Œç»†èƒžç„¦äº¡.

Doxorubicin (DOX) is a commonly administered chemotherapy drug for treating hematological malignancies and solid tumors; however, its clinical application is limited by significant cardiotoxicity. Cynaroside (Cyn) is a flavonoid glycoside distributed in honeysuckle, with confirmed potential biological functions in regulating inflammation, pyroptosis, and oxidative stress. Herein, the effects of Cyn were evaluated in a DOX-induced cardiotoxicity (DIC) mouse model, which was established by intraperitoneal injections of DOX (5 mg/kg) once a week for three weeks. The mice in the treatment group received dexrazoxane, MCC950, and Cyn every two days. Blood biochemistry, histopathology, immunohistochemistry, reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and western blotting were conducted to investigate the cardioprotective effects and potential mechanisms of Cyn treatment. The results demonstrated the significant benefits of Cyn treatment in mitigating DIC; it could effectively alleviate oxidative stress to a certain extent, maintain the equilibrium of cell apoptosis, and enhance the cardiac function of mice. These effects were realized via regulating the transcription levels of pyroptosis-related genes, such as nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3), caspase-1, and gasdermin D (GSDMD). Mechanistically, for DOX-induced myocardial injury, Cyn could significantly modulate the expression of pivotal genes, including adenosine monophosphate-activated protein kinase (AMPK), peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), sirtuin 3 (SIRT3), and nuclear factor erythroid 2-related factor 2 (Nrf2). We attribute it to the mediation of AMPK/SIRT3/Nrf2 pathway, which plays a central role in preventing DOX-induced cardiomyocyte injury. In conclusion, the present study confirms the therapeutic potential of Cyn in DIC by regulating the AMPK/SIRT3/Nrf2 pathway.

Sulforaphane triggers Sirtuin 3-mediated ferroptosis in colorectal cancer cells via activating the adenosine 5'-monophosphate (AMP)-activated protein kinase/ mechanistic target of rapamycin signaling pathway.

OBJECTIVE: This study aimed to explore the expression and biological functions of SIRT3 in colorectal cancer cells (HCT-116), the impacts of sulforaphane on the ferroptosis of HCT-116 cells and the involvement of the SIRT3/AMPK/mTOR axis in those effects. METHODS: SIRT3-overexpressing (OE) and SIRT3-knockout (KO) cell lines were treated with different concentrations of sulforaphane, RSL-3, and IKE. Cell viability, intracellular ROS, MDA, iron levels, as well as mRNA and protein expressions of target genes were measured. RESULTS: SIRT3 expression in HCT-116 cells was increased by ferroptosis inducers and decreased by ferroptosis inhibitors. SIRT3 overexpression reduced cell viability and increased intracellular levels of ROS, MDA, and iron, whereas SIRT3 knockdown achieved the opposite effects. SIRT3 overexpression suppressed SLC7A11 expression and promoted the activation of AMPK/mTOR pathway. Restoration of SLC7A11 expression blocked the effects of SIRT3 on ferroptosis induction and cell viability inhibition. SIRT3 effects on cell viability and ferroptosis were antagonized by inhibitors of AMPK or mTOR. Moreover, sulforaphane triggered the ferroptosis of HCT-116 cells by activating the SIRT3/AMPK/mTOR axis. CONCLUSIONS: SIRT3 triggered SLC7A11-mediated ferroptosis in HCT-116 cells, reducing cell viability by activating the AMPK/mTOR pathway, and sulforaphane targets it to inhibit colorectal cancer.

GDF11 promotes osteogenic/odontogenic differentiation of dental pulp stem cells to accelerate dentin restoration via modulating SIRT3/FOXO3-mediated mitophagy.

BACKGROUND: Growth differentiation factor 11 (GDF11) is considered to be a potential molecular target for treating pulpitis. However, whether GDF11 regulates osteogenic/odontogenic differentiation of dental pulp stem cells (DPSCs) to mediate pulpitis process remains unclear. METHODS: Lipopolysaccharide (LPS) was used to induce inflammation conditions in DPSCs. The levels of GDF11, sirtuin 3 (SIRT3), forkhead box O-3 (FOXO3), osteogenic/odontogenic differentiation-related markers were measured by quantitative real-time PCR (qRT-PCR) and western blot (WB). Immunofluorescence staining was used to measure mitophagy. Mitophagy-related proteins were analyzed by WB, and the levels of inflammation factors were examined using qRT-PCR, ELISA and immunohistochemistry. Alkaline phosphatase activity and alizarin red S intensity were evaluated to assess osteogenic differentiation. Acute pulp (AP) injury rat model was constructed to study the role of oe-GDF11 in vivo. RESULTS: GDF11 was downregulated in LPS-induced DPSCs, and LPS suppressed osteogenic/odontogenic differentiation and mitophagy. GDF11 overexpression promoted osteogenic/odontogenic differentiation in DPSCs through the activation of mitophagy. Furthermore, GDF11 upregulated SIRT3 to enhance FOXO3 expression by inhibiting its acetylation. GDF11 ameliorated LPS-induced inflammation and promoted osteogenic/odontogenic differentiation in DPSCs via enhancing SIRT3/FOXO3-mediated mitophagy. Besides, GDF11 overexpression suppressed inflammation and promoted dentin repair in AP rat models. CONCLUSION: GDF11 promoted SIRT3/FOXO3-mediated mitophagy to accelerate osteogenic/odontogenic differentiation in DPSCs, providing a novel target for pulpitis treatment.

ACE2 deficiency inhibits thoracic aortic dissection by enhancing SIRT3 mediated inhibition of inflammation and VSCMs phenotypic switch.

BACKGROUND: Thoracic aortic dissection (TAD) is an irreversible cardiovascular disorder with high mortality and morbidity. However, the molecular mechanisms remain elusive. Thus, identifying an effective therapeutic target to prevent TAD is especially critical. The purpose of this study is to elucidate the potential mechanism of inflammation and vascular smooth muscle cell (VSMCs) phenotypic switch in ß-aminopropionitrile fumarate (BAPN)-induced TAD. METHODS: A mouse model of TAD induced by BAPN and IL-1ß -stimulated HVSMCs in vivo and in vitro models, respectively. ACE2 Knockdown mice treated with BAPN or without, and the TAD mouse model was treated with or without AAV-ACE2. Transthoracic ultrasound was conducted for assessment the maximum internal diameter of the thoracic aorta arch. RNA sequencing analysis was performed to recapitulate transcriptome profile changes. Western blot were used to detect the expression of MMP2, MMP9, ACE2, SIRT3, OPN, SM22α and other inflammatory markers. The circulating levels of ACE2 was measured by ELISA assay. Histological changes of thoracic aorta tissues were assessed by H&E, EVG and IHC analysis. RESULTS: We found that circulating levels of and the protein levels of ACE2 were increased in the TAD mouse model and in patients with TAD. For further evidence, ACE2 deficiency decelerated the formation of TAD. However, overexpression of ACE2 aggravated BAPN-induced aortic injury and VSMCs phenotypic switch via lowered SIRT3 expression and elevated inflammatory cytokine expression. CONCLUSION: ACE2 deficiency prevented the development of TAD by inhibiting inflammation and VSMCs phenotypic switch in a SIRT3-dependent manner, suggesting that the ACE2/SIRT3 signaling pathway played a pivotal role in the pathological process of TAD and might be a potential therapeutical target.

A novel pulmonary fibrosis NOD/SCID murine model with natural aging.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is an age-related disease severely affecting life quality with its prevalence rising as the population ages, yet there is still no effective treatment available. Cell therapy has emerged as a promising option for IPF, however, the absence of mature and stable animal models for IPF immunodeficiency hampers preclinical evaluations of human cell therapies, primarily due to rapid immune clearance of administered cells. This study aims to establish a reliable pulmonary fibrosis (PF) model in immunodeficient mice that supports autologous cell therapy and to investigate underlying mechanism. METHODS: We utilized thirty 5-week-old male NOD/SCID mice, categorizing them into three age groups: 12weeks, 32 weeks and 43 weeks, with 6 mice euthanized randomly from each cohort for lung tissue analysis. We assessed fibrosis using HE staining, Masson's trichrome staining, α-SMA immunohistochemistry and hydroxyproline content measurement. Further, ß-galactosidase staining and gene expression analysis of MMP9, TGF-ß1, TNF-α, IL-1ß, IL-6, IL-8, SOD1, SOD2, NRF2, SIRT1, and SIRT3 were performed. ELISA was employed to quantify protein levels of TNF-α, TGF-ß1, and IL-8. RESULTS: When comparing lung tissues from 32-week-old and 43-week-old mice to those from 12-week-old mice, we noted a marked increase in inflammatory infiltration, fibrosis severity, and hydroxyproline content, alongside elevated expression levels of α-SMA and MMP9. Notably, the degree of fibrosis intensified with age. Additionally, ß-galactosidase staining became more pronounced in older mice. Quantitative PCR analyses revealed age-related, increases in the expression of senescence markers (GLB1, P16, P21), and proinflammatory genes (TGF-ß1, TNF-α, IL-1ß, IL-6, and IL-8). Conversely, the expression of anti-oxidative stress-related genes (SOD1, SOD2, NRF2, SIRT1, and SIRT3) declined, showing statistically significant differences (*P < 0.05, **P < 0.01, ***P < 0.001). ELISA results corroborated these findings, indicating a progressive rise in the protein levels of TGF-ß1, TNF-α, and IL-8 as the mice aged. CONCLUSIONS: The findings suggest that NOD/SCID mice aged 32 weeks and 43 weeks effectively model pulmonary fibrosis in an elderly context, with the disease pathogenesis likely driven by age-associated inflammation and oxidative stress.

The study on the role of O-GlcNAcylation of SIRT3 in regulating mitochondrial oxidative stress during simulate myocardial ischemia-reperfusion.

Myocardial ischemia-reperfusion injury (MIRI) is a significant complication following reperfusion therapy after myocardial infarction. Mitochondrial oxidative stress is a critical factor in MIRI, and Sirtuin 3 (SIRT3), as a major mitochondrial deacetylase, plays a key protective role, with its activity potentially regulated by O-GlcNAcylation. This study used the H9C2 cell line to establish a simulated ischemia/reperfusion (SI/R) model, we utilized co-immunoprecipitated to validate the relationship between O-GlcNAc transferase (OGT) and SIRT3, demonstrated SIRT3 O-GlcNAcylation sites through LC-MS/MS, and performed site mutations using CRISPR/Cas9 technology. The results were validated using immunoblotting. SIRT3 and superoxide dismutase 2 (SOD2) activities were detected using a fluorometric assay, while mitochondrial reactive oxygen species (MROS) levels and cellular apoptosis were assessed using immunofluorescence. We have identified an interaction between SIRT3 and OGT, where SIRT3 undergoes dynamic O-GlcNAcylation at the S190 site, facilitating SIRT3 deacetylase activity. During SI/R, elevated levels of O-GlcNAcylation activate SOD2 by promoting SIRT3 enzyme activity, thereby inhibiting excessive MROS production. This significantly mitigates the occurrence of malignant autophagy in myocardial cells during reperfusion, promoting their survival. Conversely, blocking SIRT3 O-GlcNAcylation at the S190 site exacerbates SI/R injury. We demonstrate that O-GlcNAcylation is a crucial post-translational modification (PTM) of SIRT3 during SI/R, shedding light on a promising mechanism for future therapeutic approaches.

Upregulation of Mitochondrial Sirt3 and Alleviation of the Inflammatory Phenotype in Macrophages by Estrogen.

BACKGROUND: Aging and comorbidities like type 2 diabetes and obesity contribute to the development of chronic systemic inflammation, which impacts the development of heart failure and vascular disease. Increasing evidence suggests a role of pro-inflammatory M1 macrophages in chronic inflammation. A shift of metabolism from mitochondrial oxidation to glycolysis is essential for the activation of the pro-inflammatory M1 phenotype. Thus, reprogramming the macrophage metabolism may alleviate the pro-inflammatory phenotype and protect against cardiovascular diseases. In the present study, we hypothesized that the activation of estrogen receptors leads to the elevation of the mitochondrial deacetylase Sirt3, which supports mitochondrial function and mitigates the pro-inflammatory phenotype in macrophages. MATERIALS AND METHODS: Experiments were performed using the mouse macrophage cell line RAW264.7, as well as primary male or female murine bone marrow macrophages (BMMs). Macrophages were treated for 24 h with estradiol (E2) or vehicle (dextrin). The effect of E2 on Sirt3 expression was investigated in pro-inflammatory M1, anti-inflammatory/immunoregulatory M2, and naïve M0 macrophages. Mitochondrial respiration was measured by Seahorse assay, and protein expression and acetylation were determined by western blotting. RESULTS: E2 treatment upregulated mitochondrial Sirt3, reduced mitochondrial protein acetylation, and increased basal mitochondrial respiration in naïve RAW264.7 macrophages. Similar effects on Sirt3 expression and mitochondrial protein acetylation were observed in primary female but not in male murine BMMs. Although E2 upregulated Sirt3 in naïve M0, pro-inflammatory M1, and anti-inflammatory/immunoregulatory M2 macrophages, it reduced superoxide dismutase 2 acetylation and suppressed mitochondrial reactive oxygen species formation only in pro-inflammatory M1 macrophages. E2 alleviated the pro-inflammatory phenotype in M1 RAW264.7 cells. CONCLUSIONS: The study suggests that E2 treatment upregulates Sirt3 expression in macrophages. In primary BMMs, female-specific Sirt3 upregulation was observed. The Sirt3 upregulation was accompanied by mitochondrial protein deacetylation and the alleviation of the oxidative and pro-inflammatory phenotype in M1 macrophages. Thus, the E2-Sirt3 axis might be used in a therapeutic strategy to fight chronic systemic inflammation and prevent the development of inflammation-linked diseases.

Nicotinamide Riboside-Driven Modulation of SIRT3/mtROS/JNK Signaling Pathways Alleviates Myocardial Ischemia-Reperfusion Injury.

Myocardial ischemia-reperfusion (I/R) injury exacerbates cellular damage upon restoring blood flow to ischemic cardiac tissue, causing oxidative stress, inflammation, and apoptosis. This study investigates Nicotinamide Riboside (NR), a precursor of nicotinamide adenine dinucleotide (NAD+), for its cardioprotective effects. Administering NR to mice before I/R injury and evaluating heart function via echocardiography showed that NR significantly improved heart function, increased left ventricular ejection fraction (LVEF) and fractional shortening (FS), and reduced left ventricular end-diastolic (LVDd) and end-systolic diameters (LVSd). NR also restored E/A and E/e' ratios. It reduced cardiomyocyte apoptosis both in vivo and in vitro, inhibiting elevated caspase-3 activity and returning Bax protein levels to normal. In vitro, NR reduced the apoptotic rate in hydrogen peroxide (H2O2)-treated HL-1 cells from 30% to 10%. Mechanistically, NR modulated the SIRT3/mtROS/JNK pathway, reversing H2O2-induced SIRT3 downregulation, reducing mitochondrial reactive oxygen species (mtROS), and inhibiting JNK activation. Using SIRT3-knockout (SIRT3-KO) mice, we confirmed that NR's cardioprotective effects depend on SIRT3. Echocardiography showed that NR's benefits were abrogated in SIRT3-KO mice. In conclusion, NR provides significant cardioprotection against myocardial I/R injury by enhancing NAD+ levels and modulating the SIRT3/mtROS/JNK pathway, suggesting its potential as a novel therapeutic agent for ischemic heart diseases, meriting further clinical research.

Capsaicin mitigates ventilator-induced lung injury by suppressing ferroptosis and maintaining mitochondrial redox homeostasis through SIRT3-dependent mechanisms.

BACKGROUND: Ventilator-induced lung injury (VILI) is one of the severe complications in the clinic concerning mechanical ventilation (MV). Capsaicin (CAP) has anti-inflammatory and inhibitory effects on oxidative stress, which is a significant element causing cellular ferroptosis. Nevertheless, the specific role and potential mechanistic pathways through which CAP modulates ferroptosis in VILI remain elusive. METHODS: VILI was established in vivo, and the pulmonary epithelial cell injury model induced by circulation stretching (CS) was established in vitro. Both mice and cells were pretreated with CAP. Transmission electron microscopy, ELISA, Western blot, immunofluorescence, RT-PCR, fluorescent probes, and other experimental methods were used to clarify the relationship between iron death and VILI in alveolar epithelial cells, and whether capsaicin alleviates VILI by inhibiting iron death and its specific mechanism. RESULTS: Ferroptosis was involved in VILI by utilizing in vivo models. CAP inhibited ferroptosis and alleviated VILI's lung damage and inflammation, and this protective effect of CAP was dependent on maintaining mitochondrial redox system through SITR3 signaling. In the CS-caused lung epithelial cell injury models, CAP reduced pathological CS-caused ferroptosis and cell injury. Knockdown SIRT3 reversed the role of CAP on the maintaining mitochondria dysfunction under pathological CS and eliminated its subsequent advantageous impacts for ferroptosis against overstretching cells. CONCLUSION: The outcomes showed that CAP alleviated ferroptosis in VILI via improving the activity of SITR3 to suppressing mitochondrial oxidative damage and maintaining mitochondrial redox homeostasis, illustrating its possibility as a novel therapeutic goal for VILI.

Naringin safeguards vertebral endplate chondrocytes from apoptosis and NLRP3 inflammasome activation through SIRT3-mediated mitophagy.

AIM: The degradation of the cartilage endplate (CEP) plays a critical role in the initiation and progression of intervertebral disc degeneration (IVDD), a disease closely associated with inflammation and oxidative stress. Naringin (NGN), a flavonoid compound derived from citrus fruits, has been shown to exhibit significant anti-inflammatory and antioxidant properties. This suggests a promising avenue for NGN's application in IVDD therapy. This study aims to elucidate the therapeutic effects and underlying mechanisms of NGN on CEP degeneration, contributing to the formulation of evidence-based treatment strategies for IVDD. METHODS: In vivo, we developed an intervertebral disc degeneration (IVDD) model in mice by excising the bilateral facet joints and surrounding ligaments, and evaluated the effects of naringin using HE staining and Micro-CT analysis. In vitro, endplate chondrocytes were isolated and subjected to TBHP to replicate the IVDD pathological condition. The protective effects of NGN on these cells were confirmed through immunofluorescence, Western Blot, and flow cytometry. RESULTS: In vivo, NGN effectively mitigated IVDD progression and CEP calcification in mice. In vitro, NGN enhanced mitophagy and suppressed NLRP3 inflammasome activation through the SIRT3/FOXO3a/Parkin pathway. Furthermore, NGN safeguarded chondrocytes against apoptosis and calcification triggered by oxidative stress, in addition to mitigating the degradation of the extracellular matrix. However, silencing SIRT3 negated NGN's protective influence on chondrocytes. CONCLUSION: Our study demonstrated that NGN effectively shields chondrocytes from apoptosis and NLRP3 inflammasome activation by facilitating SIRT3-mediated mitophagy. These insights could pave the way for innovative approaches in the prevention and management of IVDD.

Ligustilide alleviates oxidative stress during renal ischemia-reperfusion injury through maintaining Sirt3-dependent mitochondrial homeostasis.

BACKGROUND: Renal ischemia-reperfusion (I/R) injury is an inevitable complication during renal transplantation and is closely related to patient prognosis. Mitochondrial damage induced oxidative stress is the core link of renal I/R injury. Ligustilide (LIG), a natural compound extracted from ligusticum chuanxiong hort and angelica sinensis, has exhibited the potential to protect mitochondrial function. However, whether LIG can ameliorate renal I/R injury requires further investigation. Delving deeper into the precise targets and mechanisms of LIG's effect on renal I/R injury is crucial. PURPOSE: This study aimed to elucidate the specific mechanism of LIG's protective effect on renal I/R injury. METHODS: In this study, an in vivo model of renal ischemia-reperfusion (I/R) injury was developed in mice, along with an in vitro model of hypoxia-reoxygenation (H/R) using human proximal renal tubular epithelial cells (HK-2). To assess the impact of LIG on renal injury, various methods were employed, including serum creatinine (Cr) and blood urea nitrogen (BUN) testing, hematoxylin and eosin (HE) staining, and immunohistochemistry (IHC) for kidney injury molecule-1 (KIM-1). The effects of LIG on oxidative stress were examined using fluorescent probes dihydroethidium (DHE) and dichlorodihydrofluorescein diacetate (DCFH-DA), TdT-mediated dUTP Nick-End Labeling (TUNEL) staining, and flow cytometry. Additionally, the influence of LIG on mitochondrial morphology and function was evaluated through transmission electron microscopy (TEM), Mito Tracker Red CMXRos staining, adenosine triphosphate (ATP) concentration assays, and JC-1 staining. The potential mechanism involving LIG and Sirt3 was explored by manipulating Sirt3 expression through cell transfection. RESULTS: The results showed that LIG could provide protective function for mitochondria to alleviate oxidative stress induced by renal I/R. Further mechanistic studies indicated that LIG maintained mitochondrial homeostasis by targeting Sirt3. CONCLUSION: Our findings demonstrated that LIG alleviated oxidative stress during renal I/R injury through maintaining Sirt3-dependent mitochondrial homeostasis. Overall, our data raised the possibility of LIG as a novel therapy for renal I/R injury.

SIRT3 sulfhydration using hydrogen sulfide inhibited angiotensin II-induced atrial fibrosis and vulnerability to atrial fibrillation via suppression of the TGF-ß1/smad2/3 signalling pathway.

Atrial fibrosis is associated with the occurrence of atrial fibrillation (AF) and regulated by the transforming growth factor-ß1 (TGF-ß1)/Smad2/3 signalling pathway. Unfortunately, the mechanisms of regulation of TGF-ß1/Smad2/3-induced atrial fibrosis and vulnerability to AF remain still unknown. Previous studies have shown that sirtuin3 (SIRT3) sulfhydration has strong anti-fibrotic effects. We hypothesised that SIRT3 sulfhydration inhibits angiotensin II (Ang-II)-induced atrial fibrosis via blocking the TGF-ß1/Smad2/3 signalling pathway. In this study, we found that SIRT3 expression was decreased in the left atrium of patients with AF compared to that in those with sinus rhythm (SR). In vitro, SIRT3 knockdown by small interfering RNA significantly expanded Ang-II-induced atrial fibrosis and TGF-ß1/Smad2/3 signalling pathway activation, whereas supplementation with Sodium Hydrosulfide (NaHS, exogenous hydrogen sulfide donor and sulfhydration agonist) and SIRT3 overexpression using adenovirus ameliorated Ang-II-induced atrial fibrosis. Moreover, we observed suppression of the TGF-ß1/Smad2/3 pathway when Ang-II was combined with NaHS treatment, and the effect of this co-treatment was consistent with that of Ang-II combined with LY3200882 (Smad pathway inhibitor) on reducing atrial fibroblast proliferation and cell migration in vitro. Supplementation with dithiothreitol (DTT, a sulfhydration inhibitor) and adenovirus SIRT3 shRNA blocked the ameliorating effect of NaHS and AngII co-treatment on atrial fibrosis in vitro. Finally, continued treatment with NaHS in rats ameliorated atrial fibrosis and remodelling, and further improved AF vulnerability induced by Ang-II, which was reversed by DTT and adenovirus SIRT3 shRNA, suggesting that SIRT3 sulfhydration might be a potential therapeutic target in atrial fibrosis and AF.

Role of the circRNA_34414/miR-6960a-5p/SIRT3 axis in postoperative delirium via CA1 Vglut1+ neurons in older mice.

AIMS: Postoperative delirium (POD) is a common neurological complication in elderly patients after anesthesia/surgery. The main purpose of this study is to explore the effect of circRNA-targeted miRNA regulating SIRT3 on mitochondrial function through ceRNA mechanism under the surgical model of tibial fracture and to further explore the potential mechanism of postoperative delirium mediated by circRNA, so as to provide new ideas for clinical diagnosis and prevention of POD. METHODS: The surgical model of tibial fracture under sevoflurane anesthesia caused acute delirium-like behavior in elderly mice. We observed that the decrease of SIRT3 and mitochondrial dysfunction was related to POD, and miRNA and circRNA (circRNA_34414) related to SIRT3 were further studied. Through luciferase and RAP, we observed that circRNA_34414, as a miRNA sponge, was involved in the regulation of SIRT3 expression. RESULTS: Postoperative delirium in elderly mice showed decreased expression of hippocampal circRNA_34414, increased expression of miR-6960-5p, decreased expression of SIRT3, and impaired mitochondrial membrane potential. Overexpression of circRNA_34414, or knockdown of miR-6960-5p, or overexpression of SIRT3 in hippocampal CA1 glutamatergic neurons significantly upregulated hippocampal SIRT3 expression, increased mitochondrial membrane potential levels, and significantly ameliorated postoperative delirium in aged mice; CircRNA_34414 ameliorates postoperative delirium in mice, possibly by targeting miR-6960-5p to upregulate SIRT3. CONCLUSIONS: CircRNA_34414 is involved in the improvement of postoperative delirium induced by anesthesia/surgery by upregulating SIRT3 via sponging miR-6960-5p.

Role of the telomeric factor TRF2 in post-hypoxic brain damages.

The neuronal excitotoxicity that follows reoxygenation after a hypoxic period may contribute to epilepsy, Alzheimer's disease, Parkinson's disease and various disorders that are related to inadequate supplement of oxygen in neurons. Therefore, counteracting the deleterious effects of post-hypoxic stress is an interesting strategy to treat a large spectrum of neurodegenerative diseases. Here, we show that the expression of the key telomere protecting protein Trf2 decreases in the brain of mice submitted to a post-hypoxic stress. Moreover, downregulating the expression of Terf2 in hippocampal neural cells of unchallenged mice triggers an excitotoxicity-like phenotype including glutamate overexpression and behavioral alterations while overexpressing Terf2 in hippocampal neural cells of mice subjected to a post-hypoxic treatment prevents brain damages. Moreover, Terf2 overexpression in culture neurons counteracts the oxidative stress triggered by glutamate. Finally, we provide evidence that the effect of Terf2 downregulation on excitotoxicity involves Sirt3 repression leading to mitochondrial dysfunction. We propose that increasing the level of Terf2 expression is a potential strategy to reduce post-hypoxic stress damages.

Hyperglycemia-induced Sirt3 downregulation increases microglial aerobic glycolysis and inflammation in diabetic neuropathic pain pathogenesis.

BACKGROUND: Hyperglycemia-induced neuroinflammation significantly contributes to diabetic neuropathic pain (DNP), but the underlying mechanisms remain unclear. OBJECTIVE: To investigate the role of Sirt3, a mitochondrial deacetylase, in hyperglycemia-induced neuroinflammation and DNP and to explore potential therapeutic interventions. METHOD AND RESULTS: Here, we found that Sirt3 was downregulated in spinal dorsal horn (SDH) of diabetic mice by RNA-sequencing, which was further confirmed at the mRNA and protein level. Sirt3 deficiency exacerbated hyperglycemia-induced neuroinflammation and DNP by enhancing microglial aerobic glycolysis in vivo and in vitro. Overexpression of Sirt3 in microglia alleviated inflammation by reducing aerobic glycolysis. Mechanistically, high-glucose stimulation activated Akt, which phosphorylates and inactivates FoxO1. The inactivation of FoxO1 diminished the transcription of Sirt3. Besides that, we also found that hyperglycemia induced Sirt3 degradation via the mitophagy-lysosomal pathway. Blocking Akt activation by GSK69093 or metformin rescued the degradation of Sirt3 protein and transcription inhibition of Sirt3 mRNA, which substantially diminished hyperglycemia-induced inflammation. Metformin in vivo treatment alleviated neuroinflammation and diabetic neuropathic pain by rescuing hyperglycemia-induced Sirt3 downregulation. CONCLUSION: Hyperglycemia induces metabolic reprogramming and inflammatory activation in microglia through the regulation of Sirt3 transcription and degradation. This novel mechanism identifies Sirt3 as a potential drug target for treating DNP.