Mitochondrial Reactive Oxidative Species Research Articles

Abstract A020: Neutralizing oxidative damage at telomeres prevents T cell dysfunction and improves adoptive cell therapy

Abstract Background: Failure of adoptive cell therapies (ACTs) is associated with insufficient persistence within the patient, inability to infiltrate tumor sites, and cell-intrinsic loss of functionality. One of the key factors responsible for T cell dysfunction are metabolic barriers such as nutrient competition, low oxygen tension and damaging byproducts in the tumor microenvironment. This leads to a T cell metabolic deregulation affecting their ability to find and kill cancer cell targets properly and effectively. Therefore, elucidating the metabolic pressures experienced in the TME could provide new therapeutic targets to improve ACTs. Reactive Oxidative Species (ROS) accumulation in the TME have detrimental effects on T cell function and anti-tumor response, although the precise targets of ROS are unclear. There are accumulating data showing that mitochondrial ROS can have profound effects on the telomere status of cells. However, there is little evidence describing the role or oxidative stress on telomere health, or the importance of telomere function in immune cells. Our current study demonstrates that tumor infiltrating lymphocytes (TIL) accumulate DNA damage at telomeres, most prominently in terminally exhausted T cells. Furthermore, inducing ROS accumulation at telomeres alone drives T cell dysfunction. Importantly we discovered that alleviating ROS specifically at telomeres improves the response to adoptive cell therapies in a mouse tumor model. Methods: In this study we perform telomeric and centromeric FISH assays to analyze TIL for DNA damage accumulation. We used a chemo-optogenetic FAPS-TAPS to generate singlet oxygen and consequent 8-oxo-guanine lesions specifically at telomeres.1 We tethered the antioxidant protein GPX1 to TRF1, subunit of the Shelterin Complex at telomeres, to generate a telomere-guided ROS scavenger. Results: Telo-FISH analysis demonstrates an accumulation of telomeric DNA damage in TIL from B16 mouse tumors shown by the presence of 53BP1 and ƔH2AX at telomeres. Our data show that mitochondria and telomeric ROS cause the accumulation of DNA damage at telomeres, as well as the development of telomere fragility. These cells ultimately become dysfunctional showing a diminished capability for cytokine production. Importantly, localizing the ROS scavenger GPX1 directly to telomeres reduced telomere fragility and improved the function of therapeutic T cells in the B16 melanoma. Conclusions: Our data suggest that dysfunctional T cells in cancer are not classically senescent, bearing short telomeres, but rather harbor damaged telomeres due to exposure to oxidative stress. Telomeric damage is sufficient to drive a dysfunctional state in newly activated T cells. Protecting telomeres through expression of a telomere-targeted antioxidant protein may preserve T cell function in the tumor microenvironment and drive superior responses to adoptive cell therapies. Citation Format: Dayana Rivadeneira, Sanjana Thosar, Victoria Dean, William Gunn, Konstantinos Lontos, Marcel Bruchez, Patricia Opresko, Greg Delgoffe. Neutralizing oxidative damage at telomeres prevents T cell dysfunction and improves adoptive cell therapy [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr A020.

Activated malate circulation contributes to the manifestation of light-dependent mosaic symptoms

Mosaic symptoms are commonly observed in virus-infected plants. However, the underlying mechanism by which viruses cause mosaic symptoms as well as the key regulator(s) involved in this process remain unclear. Here, we investigate maize dwarf mosaic disease caused by sugarcane mosaic virus (SCMV). We find that the manifestation of mosaic symptoms in SCMV-infected maize plants requires light illumination and is correlated with mitochondrial reactive oxidative species (mROS) accumulation. The transcriptomic and metabolomic analyses results together with the genetic and cytopathological evidence indicate that malate and malate circulation pathways play essential roles in promoting mosaic symptom development. Specifically, at the pre-symptomatic infection stage or infection front, SCMV infection elevates the enzymatic activity of pyruvate orthophosphate dikinase by decreasing the phosphorylation of threonine527 under light, resulting in malate overproduction and subsequent mROS accumulation. Our findings indicate that activated malate circulation contributes to the manifestation of light-dependent mosaic symptoms via mROS.

302 Super Mitochondria, the Next Super Therapy to Reverse Ischemic Damage in Stroke?

INTRODUCTION: Stroke represents a massive healthcare emergency, ranking in the top 5 causes of death and disability and impacting nearly 800,000 Americans annually. Current therapies are limited. A deeper analysis of the mechanisms of cell death after ischemic brain insult may usher novel safe and effective treatments. Mitochondrial damage serves as a key modulator of ischemic cell death, which may be reversible with transfer of healthy mitochondria from mesenchymal stem cells (MSCs) to ischemic neurons. METHODS: MSCs were grown under ambient condition (normal MSCs) (nMSCs) or metabolic switching paradigm involving exchanging galactose for glucose in the cell culture medium (switched MSCs) (sMSCs) then assayed for oxygen consumption rates using the Seahorse technology. Subsequently, primary neurons were subjected to OGD then co-cultured with either nMSCs or sMSCs, and assessed for cell viability, cell metabolism, mitochondrial reactive oxidative species mRNA, and mitochondrial ATP mRNA. RESULTS: Compared to nMSCs, sMSCs displayed robust mitochondrial respiration as evidenced by higher basal energy production, larger spare respiratory capacity, greater ATP production, and decreased proton (H+) leak. Co-culture of OGD-exposed neurons with sMSCs conferred increased cell viability and enhanced cell metabolism, coupled with reduced mitochondrial reactive oxidative species mRNA and elevated mitochondrial ATP mRNA, which were significantly better than those afforded by nMSCs. CONCLUSIONS: These findings suggest sMSCs generated “super” mitochondria. Metabolic switching produces healthy mitochondria that may enhance the mitochondrial transfer between MSCs and ischemic cells warranting consideration as a stroke therapeutic.

Nonerythroid hemoglobin promotes human cumulus cell viability and the developmental capacity of the human oocyte

To determine the relationship between the levels of cumulus cell (CC) hemoglobin messenger ribonucleic acid (mRNA) and the developmental potential of the associated oocyte and whether hemoglobin protects the CCs from oxidative stress-induced apoptosis. Laboratory-based study. University laboratory and university-affiliated invitro fertilization center. Cumulus cells from the oocytes of patients who underwent invitro fertilization with intracytoplasmic sperm injection with and without preimplantation genetic testing between 2018 and2020. Studies on individual and pooled CCs collected at the time of oocyte retrieval or cultured under 20% or 5% O2. Quantitative polymerase chain reaction analysis of individual and pooled patient CC samples were used to monitor the hemoglobin mRNA levels. Reverse transcription-polymerase chain reaction arrays were used to assess genes that regulate oxidative stress in CCs associated with aneuploid and euploid blastocysts. Studies were conducted to assess the effect of oxidative stress on the rate of apoptosis, level of reactive oxygen species, and gene expression in CCs invitro. Compared with CCs associated with arrested and aneuploid blastocysts, the mRNA levels encoding the alpha and beta chains of hemoglobin increased by 2.9- and 2.3-fold in CCs associated with euploid blastocysts, respectively. The mRNA levels encoding the alpha and beta chains of hemoglobin also increased by 3.8- and 4.5-fold in CCs cultured under 5% O2 vs. 20% O2, respectively, and multiple regulators of oxidative stress were overexpressed in cells cultured under 20% O2 compared with those under 5% O2. However, the rate of apoptosis and amount of mitochondrial reactive oxidative species increased by 1.25-fold in CCs cultured under 20% O2 compared with those under 5% O2. Variable amounts of the alpha and beta chains of hemoglobin were also detected within the zona pellucida and oocytes. Higher levels of nonerythroid hemoglobin in CCs are associated with oocytes that result in euploid blastocysts. Hemoglobin may protect CCs from oxidative stress-induced apoptosis, which may enhance cumulus-oocyte interactions. Moreover, CC-derived hemoglobin may be transferred to the oocytes and protect it from the adverse effects of oxidative stress that occurs invivo and invitro.

Structural characterization and anti-osteoporosis effect of an arabinomannan from Anemarrhena asphodeloides Bge

To discover the polysaccharide with anti-diabetic osteoporosis (DOP) activity and clarify its structure, an arabinomannan (PAAP-1B) with a molecular weight of 14.0 kDa was isolated from Anemarrhena asphodeloides Bge. using column chromatography. It consists of arabinose, mannose, and galactose in a molar ratio of 6:3:1. PAAP-1B has a backbone composed of 1,5-α-Araf, 1,4-β-Manp, and 1,6-β-Galp residues that are branched at C3 of α-Araf and β-Galp residues. The side chains are T-α-Araf, T-α-Manp, T-β-Galp, and 1,6-β-Galp. PAAP-1B attenuated DOP and reduced ferroptosis in the femurs and tibias of alloxan-induced mice. It also suppressed ferroptosis in advanced glycation end product-induced osteoblasts by decreasing 4-hydroxynonenal, malondialdehyde, mitochondrial reactive oxidative species levels, and lipid peroxidation, while reversing the downregulation of solute carrier family 7 membrane 11 and glutathione expression.

Peering into the Dry Eye Pipeline for 2023 and Beyond

The global prevalence of dry eye disease (DED) ranges between approximately 5% and 50% and engenders a substantial socioeconomic burden. In the past decade, an unprecedented collaboration between industry and the vision sciences has spawned numerous potential therapeutic agents for DED. Many of these options possess novel mechanisms of action, potentially allowing clinicians to better tailor their treatment of patients suffering from DED. This review covers several specific pipeline drugs, such as lotilaner, perfluorohexyloctane, and cyclosporine A, along with broader drug classes such as reactive aldehyde species inhibitors, keratolytics, and mitochondrial reactive oxidative species scavengers. This review will summarize the promise and efficacy of upcoming dry eye disease treatments through the lens of data from USA-based phase II and phase III clinical trials.

Peroxisome Proliferator-Activated Receptor α Attenuates Hypertensive Vascular Remodeling by Protecting Vascular Smooth Muscle Cells from Angiotensin II-Induced ROS Production.

Vascular remodeling is the fundamental basis for hypertensive disease, in which vascular smooth muscle cell (VSMC) dysfunction plays an essential role. Previous studies suggest that the activation of peroxisome proliferator-activated receptor α (PPARα) by fibrate drugs has cardiovascular benefits independent of the lipid-lowering effects. However, the underlying mechanism remains incompletely understood. This study explored the role of PPARα in angiotensin II (Ang II)-induced vascular remodeling and hypertension using VSMC-specific Ppara-deficient mice. The PPARα expression was markedly downregulated in the VSMCs upon Ang II treatment. A PPARα deficiency in the VSMC significantly aggravated the Ang II-induced hypertension and vascular stiffness, with little influence on the cardiac function. The morphological analyses demonstrated that VSMC-specific Ppara-deficient mice exhibited an aggravated vascular remodeling and oxidative stress. In vitro, a PPARα deficiency dramatically increased the production of mitochondrial reactive oxidative species (ROS) in Ang II-treated primary VSMCs. Finally, the PPARα activation by Wy14643 improved the Ang II-induced ROS production and vascular remodeling in a VSMC PPARα-dependent manner. Taken together, these data suggest that PPARα plays a critical protective role in Ang II-induced hypertension via attenuating ROS production in VSMCs, thus providing a potential therapeutic target for hypertensive diseases.

YAP1 silencing attenuated lung injury/fibrosis but worsened diaphragmatic function by regulating oxidative stress and inflammation response in mice.

Oxidative stress is a crucial mechanism in the pathophysiology of lung injury/fibrosis and diaphragmatic dysfunction. Yes-associated protein 1 (YAP1) is a key oxidative stress response regulator. However, how lung injury/fibrosis and the subsequent YAP1 silencing treatment affect diaphragmatic function remains largely uncharacterized. In this study, mice models of acute lipopolysaccharide (LPS) and paraquat exposure were used to establish acute lung injury and chronic pulmonary fibrosis. AT2 and C2C12cells were co-cultured under LPS and paraquat challenge. YAP1 was interfered with shRNA given in vivo and verteporfin administration in vitro. Pulmonary histology, contractile properties, and cross-sectional areas (CSAs) of the diaphragm and gastrocnemius were evaluated. Histological and biochemical analyses were performed for targeted biomarker determination. We found that LPS and paraquat caused significant lung injury/fibrosis and significantly reduced the diaphragmatic-specific force and CSAs compared with the control. YAP1 silencing alleviated inflammatory cell infiltration or collagen deposition in the lungs yet worsened the already impaired diaphragmatic function by increasing inflammatory cytokines (IL-6 and TNF-α), mitochondrial reactive oxidative species (ROS) emission, protein degradation (Murf-1, atrogin-1, and calpain), and decreasing antioxidant capabilities (superoxide dismutase 2 and glutathione peroxidase). No significant improvements were observed in diaphragmatic function by transient YAP1 knockdown in the gastrocnemius. In vitro, LPS- or paraquat-caused cytotoxicity in AT2 cells was mostly alleviated by verteporfin in a concentration that was 20-fold higher than that in C2C12cells (20 and 1μg/mL, respectively). Finally, 0.5μg/mL of verteporfin significantly ameliorated hydrogen peroxide-induced proteolytic activity and antioxidant enzyme suppression in C2C12cells, whereas 2μg/mL of verteporfin deteriorated the same. Collectively, lung injury/fibrosis adversely affects the diaphragm. YAP1 inhibition alleviates lung injury/fibrosis but worsens diaphragmatic function potentially by enhancing inflammatory cytokines and ROS-mediated protein degradation. This disparity might be attributed to differences in susceptibility to YAP1 inhibition between muscles and the lungs.

Metabolic Switching of Cultured Mesenchymal Stem Cells Creates Super Mitochondria in Rescuing Ischemic Neurons

Transfer of healthy mitochondria from mesenchymal stem cells (MSCs) to ischemic neurons represents a potent stroke therapeutic. MSCs were grown under ambient conditions (nMSCs) or a metabolic switching paradigm by alternating galactose and glucose in medium (sMSCs) and then assayed for oxygen consumption rates using the Seahorse technology. Subsequently, primary neurons were subjected to oxygen glucose deprivation (OGD) and then co-cultured with either nMSCs or sMSCs. Compared to nMSCs, sMSCs displayed higher basal energy production, larger spare respiratory capacity, greater ATP production, and decreased proton leak. Co-culture of OGD-exposed neurons with sMSCs conferred greater cell viability, enhanced cell metabolism, reduced mitochondrial reactive oxidative species mRNA, and elevated mitochondria ATP mRNA than those cultured with nMSCs. Metabolic switching produces “super” mitochondria that may underlie the therapeutic benefit of using sMSCs to treat ischemic cells.

Mitochondrial-Associated Protein LRPPRC is Related With Poor Prognosis Potentially and Exerts as an Oncogene Via Maintaining Mitochondrial Function in Pancreatic Cancer.

Background: The mitochondrial-associated protein leucine-rich pentatricopeptide repeat-containing (LRPPRC) exerts multiple functions involved in physiological processes, including mitochondrial gene translation, cell cycle progression, and tumorigenesis. Previously, LRPPRC was reported to regulate mitophagy by interacting with Bcl-2 and Beclin-1 and thus modifying the activation of PI3KCIII and autophagy. Considering that LRPPRC was found to be negatively associated with survival rate, we hypothesize that LRPPRC may be involved in pancreatic cancer progression via its regulation of autophagy. Methods: Real-time quantitative polymerase chain reaction was performed to detect the expression of LRPPRC in 90 paired pancreatic cancer and adjacent tissues and five pancreatic cancer cell lines. Mitochondrial reactive oxidative species level and function were measured. Mitophagy was measured by performing to detect LC3 levels. Results: By performing a real-time quantitative polymerase chain reaction, the association of LRPPRC with the prognosis of pancreatic cancer was established, and pancreatic cancer tissues had significantly higher LRPPRC expression than adjacent tissues. LRPPRC was negatively associated with the overall survival rate. LRPPRC was also upregulated in pancreatic cancer cell lines. Knockdown of LRPPRC promoted reactive oxidative species accumulation, decreased mitochondrial membrane potential, promoted autophagy/mitophagy, and induced mitochondrial dysfunction. Subsequently, knockdown of LRPPRC inhibited malignant behaviors in PANC-1 cells, including proliferation, migration, invasion, tumor formation, and chemoresistance to gemcitabine. Finally, by inhibiting autophagy/mitophagy using 3-MA, the inhibitory effect of LRPPRC knockdown on proliferation was reversed. Conclusion: Taken together, our results indicate that LRPPRC may act as an oncogene via maintaining mitochondrial homeostasis and could be used as a predictive marker for patient prognosis in pancreatic cancer.

Inhibition of mitochondrial reactive oxygen species improves coronary endothelial function after cardioplegic hypoxia/reoxygenation

ObjectiveCardioplegic ischemia–reperfusion and diabetes mellitus are correlated with coronary endothelial dysfunction and inactivation of small conductance calcium-activated potassium channels. Increased reactive oxidative species, such as mitochondrial reactive oxidative species, may contribute to oxidative injury. Thus, we hypothesized that inhibition of mitochondrial reactive oxidative species may protect coronary small conductance calcium-activated potassium channels and endothelial function against cardioplegic ischemia–reperfusion-induced injury. MethodsSmall coronary arteries and endothelial cells from the hearts of mice with and without diabetes mellitus were isolated and examined by using a cardioplegic hypoxia and reoxygenation model to determine whether the mitochondria-targeted antioxidant Mito-Tempo could protect against coronary endothelial and small conductance calcium-activated potassium channel dysfunction. The microvessels or mouse heart endothelial cells were treated with or without Mito-Tempo (0-10 μM) 5 minutes before and during cardioplegic hypoxia and reoxygenation. Microvascular function was assessed in vitro by vessel myography. K+ currents of mouse heart endothelial cells were measured by whole-cell patch clamp. The levels of intracellular cytosolic free calcium (Ca2+) concentration, mitochondrial reactive oxidative species, and small conductance calcium-activated potassium protein expression of mouse heart endothelial cells were measured by Rhod-2 fluorescence staining, MitoSox, and Western blotting, respectively. ResultsCardioplegic hypoxia and reoxygenation significantly attenuated endothelial small conductance calcium-activated potassium channel activity, caused calcium overload, and increased mitochondrial reactive oxidative species of mouse heart endothelial cells in both the nondiabetic and diabetes mellitus groups. In addition, treating mouse heart endothelial cells with Mito-Tempo (10 μM) reduced cardioplegic hypoxia and reoxygenation-induced Ca2+ and mitochondrial reactive oxidative species overload in both the nondiabetic and diabetes mellitus groups, respectively (P < .05). Treatment with Mito-Tempo (10 μM) significantly enhanced coronary relaxation responses to adenosine 5′-diphosphate and NS309 (P < .05), and endothelial small conductance calcium-activated potassium channel currents in both the nondiabetic and diabetes mellitus groups (P < .05). ConclusionsAdministration of Mito-Tempo improves endothelial function and small conductance calcium-activated potassium channel activity, which may contribute to its enhancement of endothelium-dependent vasorelaxation after cardioplegic hypoxia and reoxygenation.

Anakinra Activates Superoxide Dismutase 2 to Mitigate Inflammasome Activity.

Inflammasomes are powerful cytosolic sensors of environmental stressors and are critical for triggering interleukin-1 (IL-1)-mediated inflammatory responses. However, dysregulation of inflammasome activation may lead to pathological conditions, and the identification of negative regulators for therapeutic purposes is increasingly being recognized. Anakinra, the recombinant form of the IL-1 receptor antagonist, proved effective by preventing the binding of IL-1 to its receptor, IL-1R1, thus restoring autophagy and dampening NLR family pyrin domain containing 3 (NLRP3) activity. As the generation of mitochondrial reactive oxidative species (ROS) is a critical upstream event in the activation of NLRP3, we investigated whether anakinra would regulate mitochondrial ROS production. By profiling the activation of transcription factors induced in murine alveolar macrophages, we found a mitochondrial antioxidative pathway induced by anakinra involving the manganese-dependent superoxide dismutase (MnSOD) or SOD2. Molecularly, anakinra promotes the binding of SOD2 with the deubiquitinase Ubiquitin Specific Peptidase 36 (USP36) and Constitutive photomorphogenesis 9 (COP9) signalosome, thus increasing SOD2 protein longevity. Functionally, anakinra and SOD2 protects mice from pulmonary oxidative inflammation and infection. On a preclinical level, anakinra upregulates SOD2 in murine models of chronic granulomatous disease (CGD) and cystic fibrosis (CF). These data suggest that protection from mitochondrial oxidative stress may represent an additional mechanism underlying the clinical benefit of anakinra and identifies SOD2 as a potential therapeutic target.

Mitochondria Homeostasis and Oxidant/Antioxidant Balance in Skeletal Muscle-Do Myokines Play a Role?

Mitochondria are the cellular powerhouses that generate adenosine triphosphate (ATP) to substantiate various biochemical activities. Instead of being a static intracellular structure, they are dynamic organelles that perform constant structural and functional remodeling in response to different metabolic stresses. In situations that require a high ATP supply, new mitochondria are assembled (mitochondrial biogenesis) or formed by fusing the existing mitochondria (mitochondrial fusion) to maximize the oxidative capacity. On the other hand, nutrient overload may produce detrimental metabolites such as reactive oxidative species (ROS) that wreck the organelle, leading to the split of damaged mitochondria (mitofission) for clearance (mitophagy). These vital processes are tightly regulated by a sophisticated quality control system involving energy sensing, intracellular membrane interaction, autophagy, and proteasomal degradation to optimize the number of healthy mitochondria. The effective mitochondrial surveillance is particularly important to skeletal muscle fitness because of its large tissue mass as well as its high metabolic activities for supporting the intensive myofiber contractility. Indeed, the failure of the mitochondrial quality control system in skeletal muscle is associated with diseases such as insulin resistance, aging, and muscle wasting. While the mitochondrial dynamics in cells are believed to be intrinsically controlled by the energy content and nutrient availability, other upstream regulators such as hormonal signals from distal organs or factors generated by the muscle itself may also play a critical role. It is now clear that skeletal muscle actively participates in systemic energy homeostasis via producing hundreds of myokines. Acting either as autocrine/paracrine or circulating hormones to crosstalk with other organs, these secretory myokines regulate a large number of physiological activities including insulin sensitivity, fuel utilization, cell differentiation, and appetite behavior. In this article, we will review the mechanism of myokines in mitochondrial quality control and ROS balance, and discuss their translational potential.

Abstract 14853: Acute Inhibition of Mitochondrial Reactive Oxidative Species Improves Endothelial SK Channel Function Following Cardioplegic Hypoxia/Reperfusion and Diabetes

Introduction: Cardioplegic-ischemia/reperfusion (CP-I/R) and diabetes mellitus (DM) are correlated with coronary endothelial dysfunction and inactivated small conductance calcium-activated-potassium (SK) channels. Increased reactive oxidative species (ROS), such as mitochondrial ROS (mROS) may contribute to oxidative injury. Thus, we hypothesized that inhibition of mROS may protect coronary SK channels and endothelial function against CP-I/R-induced injury. Objective: A cardioplegic hypoxia and reoxygenation (CP-H/R) model consisting of coronary endothelial cells and small coronary arteries with or without DM were employed for examining whether MT could protect against coronary endothelial and SK channel dysfunction. Methods: Small coronary arteries (&lt;150μm) and endothelial cells (MHECs) were dissected from the mouse heart with non-diabetes (ND) and DM (n=6/group). The microvessels or MHECs were subjected to hypoxia with cardioplegia and re-oxygenated. The microvessels or MHECs were treated with or without MT (10 -5 M) 5-minutes before and during CP-hypoxia. Microvascular vasodilation function was assessed in vitro by administration of vasoconstrictor, then ADP or NS309,respectively. K + currents of MHECs were measured by whole-cell patch clamp. The levels of endothelial mROS was measured by MitoSox TM . Results: CP-H/R significantly attenuated endothelial SK channels activity and the coronary relaxation responses to ADP and NS309 in the ND and DM groups. Treatment with MT enhanced coronary relaxation responses to ADP or NS309 ( p &lt;0.05, Fig 1. A, B), and similar findings were seen in endothelial SK channel currents in both ND and DM MHECs ( p &lt;0.05, Fig 1. C-F). In addition, treating MHECs with MT reduced CP-H/R-induced mROS in ND and DM groups. Conclusions: Administration of MT improves endothelial SK channels activity which may contribute to its enhancement of endothelium-dependent vasorelaxation following CP-H/R.

The Microbiota-Derived Metabolite of Quercetin, 3,4-Dihydroxyphenylacetic Acid Prevents Malignant Transformation and Mitochondrial Dysfunction Induced by Hemin in Colon Cancer and Normal Colon Epithelia Cell Lines.

Meat diet plays a pivotal role in colorectal cancer (CRC). Hemin, a metabolite of myoglobin, produced after meat intake, has been involved in CRC initiation. The compound, 3,4-dihydroxyphenylacetic acid (3,4HPAA) is a scarcely studied microbiota-derived metabolite of the flavonoid quercetin (QUE), which exert antioxidant properties. The aim of this study was to determine the protective effect of 3,4HPAA against malignant transformation (increased cell proliferation, decreased apoptosis, DNA oxidative damage and augmented reactive oxidative species (ROS) levels) and mitochondrial dysfunction induced by hemin in normal colon epithelial cells and colon cancer cells. The effect of 3,4HPAA was assessed in comparison to its precursor, QUE and to a known CRC protective agent, sulforaphane (SFN). The results showed that both, tumor and normal cells, exposed to hemin, presented increased cell proliferation, decreased caspase 3 activity and cytochrome c release, as well as augmented production of intracellular and mitochondrial ROS. In addition, hemin decreased the mitochondrial membrane potential (MMP) and the activity of complexes I and II of the electron transport chain. These effects of hemin were prevented by the action of 3,4HPAA. The metabolite showed to be more active than QUE and slightly less active than SFN. In conclusion, 3,4HPAA administration could represent a promising strategy for preventing malignant transformation and mitochondrial dysfunction in colon epithelia induced by hemin.

Inhibition of p66Shc Oxidative Signaling via CA-Induced Upregulation of miR-203a-3p Alleviates Liver Fibrosis Progression

We previously found that inhibition of p66Shc confers protection against hepatic stellate cell (HSC) activation during liver fibrosis. However, the effect of p66Shc on HSC proliferation, as well as the mechanism by which p66Shc is modulated, remains unknown. Here, we elucidated the effect of p66Shc on HSC proliferation and evaluated microRNA (miRNA)-p66Shc-mediated reactive oxidative species (ROS) generation in liver fibrosis. An in vivo model of carbon tetrachloride (CCl4)-induced liver fibrosis in rats and an LX-2 cell model were developed. p66Shc expression was significantly upregulated in rats with CCl4-induced liver fibrosis and in human fibrotic livers. Additionally, p66Shc knockdown in vitro attenuated mitochondrial ROS generation and HSC proliferation. Interestingly, p66Shc promoted HSC proliferation via β-catenin dephosphorylation in vitro. MicroRNA (miR)-203a-3p, which was identified by microarray and bioinformatics analyses, directly inhibited p66Shc translation and attenuated HSC proliferation in vitro. Importantly, p66Shc was found to play an indispensable role in the protective effect of miR-203a-3p. Furthermore, carnosic acid (CA), the major antioxidant compound extracted from rosemary leaves, protected against CCl4-induced liver fibrosis through the miR-203a-3p/p66Shc axis. Collectively, these results suggest that p66Shc, which is directly suppressed by miR-203a-3p, is a key regulator of liver fibrosis. This finding may lead to the development of therapeutic targets for liver fibrosis.

P6279Mitochondria targeted catalase overexpression protects against beta-adrenergic receptor mediated cardiac remodeling in mice

Abstract Background Beta-adrenergic receptor signaling is widely recognized as a fundamental component in the pathogenesis of chronic heart failure. However, the mechanisms behind beta-adrenergic receptor-mediated remodeling in cardiomyocytes and the myocardium are not fully understood. Oxidative stress has been proposed as a central pathophysiological mediator in cardiovascular disease and heart failure. The triggers and sources of oxidative stress in heart failure remain unclear. In this study we use mice with mitochondria-targeted overexpression of the antioxidant enzyme catalase (mCAT) to link beta-adrenergic receptor-mediated stress to mitochondrial reactive oxidative species (ROS) and the progression of heart failure. Hypothesis Mitochondrial ROS, induced by beta-adrenergic receptor-activation, is a mediator in the progression of the heart failure phenotype. Methods mCAT and wild type mice (n=10) were administered the non-selective beta-adrenergic agonist Isoprotenerol (Iso; 50mg/kg/day) through subcutaneous osmotic pumps for 3 weeks. Hearts were taken for biochemistry (western blotting, qPCR). Cardiomyocytes were isolated and loaded with Fluo-3 AM to study intracellular Ca2+ transients and fractional shortening using confocal line scan microscopy. All experiments were performed in accordance with the Stockholm ethical committee for animal research. Results and conclusions The WT mice displayed an increased heart/body weight ratio following chronic Iso administration. In contrast, mCAT mice displayed resistance to Iso-induced cardiac hypertrophy (p&lt;0.05). Furthermore, chronic Iso exposure in WT mice induced increased ROS-dependent post-translational protein modifications, impaired cardiomyocyte Ca2+ handling and reduced contractility in isolated cardiomyocytes (p&lt;0.05). Cardiomyocytes from mCAT mice did not display the deleterious effects of chronic Iso exposure on cardiomyocyte Ca2+ and contractility. Our study demonstrates that beta-adrenergic receptor stimulation-induced remodeling of the heart, which is similar to what is seen in heart failure, can be prevented by overexpressing catalase in the mitochondria. This indicates an important role of mitochondrial ROS in the link between adrenergic signaling and the development of cardiomyopathy and heart failure. Acknowledgement/Funding Hjärtlungfonden

Mitochondrial ROS and NLRP3 inflammasome in acute ozone-induced murine model of airway inflammation and bronchial hyperresponsiveness

Oxidative stress is a key mechanism underlying ozone-induced lung injury. Mitochondria can release mitochondrial reactive oxidative species (mtROS), which may lead to the activation of NLRP3 inflammasome. The goal of this study was to examine the roles of mtROS and NLRP3 inflammasome in acute ozone-induced airway inflammation and bronchial hyperresponsiveness (BHR). C57/BL6 mice (n = 8/group) were intraperitoneally treated with vehicle (phosphate buffered saline, PBS) or mitoTEMPO (mtROS inhibitor, 20 mg/kg), or orally treated with VX-765 (caspse-1 inhibitor, 100 mg/kg) 1 h before the ozone exposure (2.5 ppm, 3 h). Compared to the PBS-treated ozone-exposed mice, mitoTEMPO reduced the level of total malondialdehyde in bronchoalveolar lavage (BAL) fluid and increased the expression of mitochondrial complexes II and IV in the lung 24 h after single ozone exposure. VX-765 inhibited ozone-induced BHR, BAL total cells including neutrophils and eosinophils, and BAL inflammatory cytokines including IL-1α, IL-1β, KC, and IL-6. Both mitoTEMPO and VX-765 reduced ozone-induced mtROS and inhibited capase-1 activity in lung tissue whilst VX-765 further inhibited DRP1 and MFF expression, increased MFN2 expression, and down-regulated caspase-1 expression in the lung tissue. These results indicate that acute ozone exposure induces mitochondrial dysfunction and NLRP3 inflammasome activation, while the latter has a critical role in the pathogenesis of ozone-induced airway inflammation and BHR.

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.

Vascular progenitor cell senescence in patients with Marfan syndrome.

Vascular progenitor cells (VPCs) present in the adventitia of the vessel wall play a critical role in the regulation of vascular repair following injury. This study aimed to assess the function of VPCs isolated from patients with Marfan syndrome (MFS). VPCs were isolated from control and MFS donors and characterized. Compared with control‐VPCs, MFS‐VPCs exhibited cellular senescence as demonstrated by increased cell size, higher SA‐β‐gal activity and elevated levels of p53 and p21. RNA sequencing showed that several cellular process‐related pathways including cell cycle and cellular senescence were significantly enriched in MFP‐VPCs. Notably, the expression level of TGF‐β1 was much higher in MFS‐VPCs than control‐VPCs. Treatment of control‐VPCs with TGF‐β1 significantly enhanced mitochondrial reactive oxidative species (ROS) and induced cellular senescence whereas inhibition of ROS reversed these effects. MFS‐VPCs displayed increased mitochondrial fusion and decreased mitochondrial fission. Treatment of control‐VPCs with TGF‐β1 increased mitochondrial fusion and reduced mitochondrial fission. Nonetheless, treatment of mitofusin2 (Mfn2)‐siRNA inhibited TGF‐β1‐induced mitochondrial fusion and cellular senescence. Furthermore, TGF‐β1‐induced mitochondrial fusion was mediated by the AMPK signalling pathway. Our study shows that TGF‐β1 induces VPC senescence in patients with MFS by mediating mitochondrial dynamics via the AMPK signalling pathway.