Mitochondrial dysfunction in cardiac disease: ischemia--reperfusion, aging, and heart failure

Artemether confers neuroprotection on cerebral ischemic injury through stimulation of the Erk1/2-P90rsk-CREB signaling pathway

Ischemic stroke is one of the leading causes of death and disability among adults. Despite the economic burden of the disease, available treatment options are still very limited. With the exception of anti-thrombolytics and hypothermia, current therapies fail to reduce neuronal injury, neurological deficits and mortality rates, suggesting that the development of novel and more effective therapies against ischemic stroke is urgent. In the present study, we found that artemether, which has been used in the clinic as an anti-malarial drug, was able to improve the neurological deficits, attenuate the infarction volume and the brain water content in a middle cerebral artery occlusion (MCAO) animal model. Furthermore, artemether treatment significantly suppressed cell apoptosis, stimulated cell proliferation and promoted the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2), P90^rsk and cAMP responsive element-binding protein (CREB). Artemether protective effect was attenuated by PD98059, an ERK1/2 inhibitor, administration. Similarly, in oxygen-glucose deprivation/reperfusion (OGD/RP) cell models, artemether pre-treatment induced the suppression of the intracellular ROS, the down-regulation of LDH activity, the reduction of caspase 3 activity and of the apoptosis cell rate and reversed the decrease of mitochondrial membrane potential. As with MCAO animal model, artemether promoted the activation of Erk1/2-P90^rsk-CREB signaling pathway. This effect was blocked by the inhibition or knock-down of ERK1/2. The present study provides evidences of the neuroprotective effect of artemether unravelling its potential as a new therapeutic candidate for the prevention and treatment of stroke.

•

Artemether conferred neuroprotection in a middle cerebral artery occlusion (MCAO) animal model.

•

Artemether conferred neuroprotection on oxygen-glucose deprivation/reperfusion-induced cell injury model.

•

Artemether promoted the activation of Erk1/2-P90^rsk-CREB signaling pathway in vitro and in vivo.

Impact of Aldosterone on the Failing Myocardium: Insights from Mitochondria and Adrenergic Receptors Signaling and Function

The mineralocorticoid aldosterone regulates electrolyte and blood volume homeostasis, but it also adversely modulates the structure and function of the chronically failing heart, through its elevated production in chronic human post-myocardial infarction (MI) heart failure (HF). By activating the mineralocorticoid receptor (MR), a ligand-regulated transcription factor, aldosterone promotes inflammation and fibrosis of the heart, while increasing oxidative stress, ultimately induding mitochondrial dysfunction in the failing myocardium. To reduce morbidity and mortality in advanced stage HF, MR antagonist drugs, such as spironolactone and eplerenone, are used. In addition to the MR, aldosterone can bind and stimulate other receptors, such as the plasma membrane-residing G protein-coupled estrogen receptor (GPER), further complicating it signaling properties in the myocardium. Given the salient role that adrenergic receptor (ARs)-particularly βARs-play in cardiac physiology and pathology, unsurprisingly, that part of the impact of aldosterone on the failing heart is mediated by its effects on the signaling and function of these receptors. Aldosterone can significantly precipitate the well-documented derangement of cardiac AR signaling and impairment of AR function, critically underlying chronic human HF. One of the main consequences of HF in mammalian models at the cellular level is the presence of mitochondrial dysfunction. As such, preventing mitochondrial dysfunction could be a valid pharmacological target in this condition. This review summarizes the current experimental evidence for this aldosterone/AR crosstalk in both the healthy and failing heart, and the impact of mitochondrial dysfunction in HF. Recent findings from signaling studies focusing on MR and AR crosstalk via non-conventional signaling of molecules that normally terminate the signaling of ARs in the heart, i.e., the G protein-coupled receptor-kinases (GRKs), are also highlighted.

Mitochondrial Oxidative Phosphorylation Function and Mitophagy in Ischaemic/Reperfused Hearts from Control and High-Fat Diet Rats: Effects of Long-Term Melatonin Treatment

PURPOSE

Oxidative stress causes mitochondrial dysfunction in myocardial ischaemia/reperfusion (I/R) as well as in obesity. Mitochondrial depolarization triggers mitophagy to degrade damaged mitochondria, a process important for quality control. The aims of this study were to evaluate (i) the effect of I/R on mitochondrial oxidative phosphorylation and its temporal relationship with mitophagy in hearts from obese rats and their age-matched controls, and (ii) the role of oxidative stress in these processes using melatonin, a free radical scavenger.

METHODS

Male Wistar rats were divided into 4 groups: control (normal diet ± melatonin) and high-fat sucrose diet (HFSD ± melatonin). Rats received melatonin orally (10 mg/kg/day). After 16 weeks, hearts were removed and subjected to 40-min stabilization, and 25-min global ischaemia/10-min reperfusion for preparation of mitochondria. Mitochondrial oxidative phosphorylation was measured polarographically. Western blotting was used for evaluation of PINK1, Parkin, p62/SQSTM1 (p62) and TOM 70. Infarct size was measured using tetrazolium staining.

RESULTS

Ischaemia and reperfusion respectively reduced and increased mitochondrial QO2 (state 3) and the ox-phos rate in both control and HFSD mitochondria, showing no major changes between the groups, while melatonin pretreatment had little effect. p62 as indicator of mitophagic flux showed up- and downregulation of mitophagy by ischaemia and reperfusion respectively, with melatonin having no significant effect. Melatonin treatment caused a significant reduction in infarct size in hearts from both control and diet groups.

CONCLUSIONS

The results suggest that I/R (i) affects mitochondria from control and HFSD hearts similarly and (ii) melatonin-induced cardioprotection is not associated with reversal of mitochondrial dysfunction or changes in the PINK1/Parkin pathway.

Quantification of Myocardial Mitochondrial Membrane Potential Using PET

PURPOSE OF REVIEW

To present a method enabling in vivo quantification of tissue membrane potential (ΔΨ_T), a proxy of mitochondrial membrane potential (ΔΨ_m), to review the origin and role of ΔΨ_m, and to highlight potential applications of myocardial ΔΨ_T imaging.

RECENT FINDINGS

Radiolabelled lipophilic cations have been used for decades to measure ΔΨ_m in vitro. Using similar compounds labeled with positron emitters and appropriate compartment modeling, this technique now allows in vivo quantification of ΔΨ_T with positron emission tomography. Studies have confirmed the feasibility of measuring myocardial ΔΨ_T in both animals and humans. In addition, ΔΨ_T showed very low variability among healthy subjects, suggesting that this method could allow detection of relatively small pathological changes. In vivo assessment of myocardial ΔΨ_T provides a new tool to study the pathophysiology of cardiovascular diseases and has the potential to serve as a new biomarker to assess disease stage, prognosis, and response to therapy.

Post-Cardiac Arrest Hydrocortisone Use Ameliorates Cardiac Mitochondrial Injury in a Male Rat Model of Ventricular Fibrillation Cardiac Arrest

Background

Steroid use after cardiac arrest has been reported to improve survival and neurological outcome in cardiac arrest survivors. The study aimed to evaluate the effect of post‐arrest hydrocortisone use on myocardial damage and cardiac mitochondrial injury in a rat model of ventricular fibrillation cardiac arrest.

Methods and Results

Ventricular fibrillation cardiac arrest was induced and left untreated for 5 minutes in adult male Wistar rats. Cardiopulmonary resuscitation and electric shocks were then applied to achieve return of spontaneous circulation (ROSC). Successfully resuscitated animals were randomized into 3 groups: control, low‐dose hydrocortisone (2 mg/kg), and high‐dose hydrocortisone (8 mg/kg). The low‐dose hydrocortisone and high‐dose hydrocortisone (treatment) groups received intravenous hydrocortisone immediately after ROSC and the control group received saline as placebo. Each group consisted of 15 animals. Within 4 hours of ROSC, both treatment groups showed a higher cardiac output than the control group. At the fourth hour following ROSC, histological examination and transmission electron microscopy demonstrated less myocardial damage and mitochondrial injury in the animals treated with hydrocortisone. In the treatment groups, hydrocortisone mitigated the acceleration of Ca²⁺‐induced mitochondrial swelling and suppression of complex activity observed in the control group. At the 72nd hour after ROSC, a significantly higher proportion of animals treated with hydrocortisone survived and had good neurological recovery compared with those given a placebo.

Conclusions

Hydrocortisone use after cardiac arrest may mitigate myocardial injury and cardiac mitochondrial damage and thus improve survival, neurological and histological outcomes in a rat model of ventricular fibrillation cardiac arrest.

Polymer Conjugation of Docosahexaenoic Acid Potentiates Cardioprotective Therapy in Preclinical Models of Myocardial Ischemia/Reperfusion Injury

While coronary angioplasty represents an effective treatment option following acute myocardial infarction, the reperfusion of the occluded coronary artery can prompt ischemia-reperfusion (I/R) injury that significantly impacts patient outcomes. As ω-3 polyunsaturated fatty acids (PUFAs) have proven, yet limited cardioprotective abilities, an optimized polymer-conjugation approach is reported that improves PUFAs bioavailability to enhance cardioprotection and recovery in animal models of I/R-induced injury. Poly-l-glutamic acid (PGA) conjugation improves the solubility and stability of di-docosahexaenoic acid (diDHA) under physiological conditions and protects rat neonatal ventricular myocytes from I/R injury by reducing apoptosis, attenuating autophagy, inhibiting reactive oxygen species generation, and restoring mitochondrial membrane potential. Enhanced protective abilities are associated with optimized diDHA loading and evidence is provided for the inherent cardioprotective potential of PGA itself. Pretreatment with PGA-diDHA before reperfusion in a small animal I/R model provides for cardioprotection and limits area at risk (AAR). Furthermore, the preliminary findings suggest that PGA-diDHA administration in a swine I/R model may provide cardioprotection, limit edema and decrease AAR. Overall, the evaluation of PGA-diDHA in relevant preclinical models provides evidence for the potential of polymer-conjugated PUFAs in the mitigation of I/R injury associated with coronary angioplasty.

DSIP-Like KND Peptide Reduces Brain Infarction in C57Bl/6 and Reduces Myocardial Infarction in SD Rats When Administered during Reperfusion

A structural analogue of the DSIP, peptide KND, previously showed higher detoxification efficacy upon administration of the cytotoxic drug cisplatin, compared to DSIP. DSIP and KND were investigated using the model of acute myocardial infarction in male SD rats and the model of acute focal stroke in C57Bl/6 mice. A significant decrease in the myocardial infarction area was registered in KND-treated animals relative to saline-treated control animals (19.1 ± 7.3% versus 42.1 ± 9.2%). The brain infarction volume was significantly lower in animals intranasally treated with KND compared to the control saline-treated animals (7.4 ± 3.5% versus 12.2 ± 5.6%). Injection of KND in the first minute of reperfusion in the models of myocardial infarction and cerebral stroke reduced infarction of these organs, indicating a pronounced cardioprotective and neuroprotective effect of KND and potentiality for the treatment of ischemia-reperfusion injuries after transient ischemic attacks on the heart and brain, when administered during the reperfusion period. A preliminary pilot study using the model of myocardial infarction with the administration of DSIP during occlusion, and the model of cerebral stroke with the administration of KND during occlusion, resulted in 100% mortality in animals. Thus, in the case of ischemia-reperfusion injuries of the myocardium and the brain, use of these peptides is only possible during reperfusion.

Recent advances in the protective role of hydrogen sulfide in myocardial ischemia/reperfusion injury: a narrative review

Hydrogen sulfide (H₂S) is recognized to be a novel mediator after carbon monoxide and nitric oxide in the organism. It can be produced in various mammalian tissues and exert many physiological effects in many systems including the cardiovascular system. A great amount of recent studies have demonstrated that endogenous H₂S and exogenous H₂S-releasing compounds (such as NaHS, Na₂S, and GYY4137) provide protection in many cardiovascular diseases, such as ischemia/reperfusion injury, heart failure, cardiac hypertrophy, and atherosclerosis. In recent years, many mechanisms have been proposed and verified the protective role exhibited by H₂S against myocardial ischemia/reperfusion injury, and this review is to demonstrate the protective role of exogenous and endogenous H₂S on myocardial ischemia/reperfusion injury.

The pyruvate-lactate axis modulates cardiac hypertrophy and heart failure

The metabolic rewiring of cardiomyocytes is a widely accepted hallmark of heart failure (HF). These metabolic changes include a decrease in mitochondrial pyruvate oxidation and an increased export of lactate. We identify the mitochondrial pyruvate carrier (MPC) and the cellular lactate exporter monocarboxylate transporter 4 (MCT4) as pivotal nodes in this metabolic axis. We observed that cardiac assist device-induced myocardial recovery in chronic HF patients was coincident with increased myocardial expression of the MPC. Moreover, the genetic ablation of the MPC in cultured cardiomyocytes and in adult murine hearts was sufficient to induce hypertrophy and HF. Conversely, MPC overexpression attenuated drug-induced hypertrophy in a cell-autonomous manner. We also introduced a novel, highly potent MCT4 inhibitor that mitigated hypertrophy in cultured cardiomyocytes and in mice. Together, we find that alteration of the pyruvate-lactate axis is a fundamental and early feature of cardiac hypertrophy and failure.

Remote Ischemic Postconditioning Inhibited Mitophagy to Achieve Neuroprotective Effects in the Rat Model of Cardiac Arrest

Remote ischemic postconditioning (RI-postC) is an effective measure to improve nerve function after cardiac arrest. However, the brain protective mechanism of RI-postC has not been fully elucidated, and whether it is related to mitophagy is unclear. In this study, we used the rat model of cardiac arrest to study the effect of RI-postC on mitophagy and explore its possible signaling pathways. Rats were randomly divided into Sham group, CA/CPR group, Mdivi-1 group and RI-postC group. The animal model of cardiac arrest was established by asphyxia. RI-postC was performed by clamping and loosening the left femoral artery. Mdivi-1 was treated with a single intravenous injection. Levels of TOMM20, TIM23, Mfn1, PINK1 and parkin were detected by western blots. Mitochondrial membrane potential was measured by flow cytometry. Real-time PCR was used to detect relative mitochondrial DNA levels. The apoptosis of hippocampal neurons was detected by flow and TUNEL. In addition, Histopathological tests were performed. The results showed that RI-postC was similar to the mitophagy inhibitor Mdivi-1, which could inhibit the decrease of mitophagy-related protein level, improve mitochondrial membrane potential and up-regulate the ratio of mt-Atp6/Rpl13 after cardiopulmonary resuscitation (CPR). Furthermore, RI-postC could also reduce the rate of hippocampal nerve apoptosis and the damage of hippocampal neurons after CPR. Moreover, RI-postC and Mdivi-1 could reduce the protein levels of PINK1 and parkin in mitochondria after CPR, while increasing PINK1 levels in the cytoplasm. These findings suggested that RI-postC could inhibit the overactivation mitophagy through the PINK1/parkin signaling pathway, thus providing neuroprotective effects.

Effect of Gloriosa superba linn (EEGS) on mPT and monosodium glutamate-induced proliferative disorder using rat model

ETHNOPHARMACOLOGICAL RELEVANCE

Hyperplasia, Tumors and cancers are various forms of proliferative disorders affecting humans. Surgery is the main treatment approach while other options are also associated with adverse effects. There is therefore a need for the development of better alternative therapy that is cost effective and readily available with little or no adverse effect. Some bioactive agents in medicinal plants exhibit their anti-proliferative potential by induction of mitochondrial permeability transition pore (mPT) opening. Gloriosa superba, a medicinal plant, is folklorically used in the treatment of tumors and cancers.

AIM OF THE STUDY

This study therefore aimed at investigating the effect of ethanol leaf extract of Gloriosa superba (EEGS) on mPT and monosodium glutamate-induced proliferative disorder in some specific tissues using rat model.

MATERIALS AND METHODS

Isolated rat liver mitochondria were exposed to different concentrations (10, 30, 50, 70 and 90 μg/ml) of EEGS. The mPT pore opening, cytochrome c release, mitochondrial ATPase activity and lipid peroxidation were assessed spectrophotometrically. Caspases 9 and 3 activities were carried out using ELISA technique. Histological assessment of the liver, prostate and uterus of normal and monosodium glutamate (MSG)-treated rats were carried out.

RESULTS

The results showed significant induction of mPT pore opening, release of cytochrome c, enhancement of mitochondrial ATPase activity, inhibition of lipid peroxidation and activation of caspases 9 and 3 activities by EEGS. The histological assessment revealed the presence of MSG-induced hepato-cellular damage, benign prostate hyperplasia and uterine hyperplasia which were ameliorated by EEGS co-administration.

CONCLUSIONS

These findings suggest that EEGS contains putative agents that can induce apoptosis via induction of mPT pore opening and as well protect against MSG-induced hepato-cellular damage and proliferative disorder in prostate and uterus.

Serum Individual Nonesterified Fatty Acids and Risk of Heart Failure in Older Adults

BACKGROUND

Heart failure (HF) is highly prevalent among older adults and is associated with high costs. Although serum total nonesterified fatty acids (NEFAs) have been positively associated with HF risk, the contribution of each individual NEFA to HF risk has not been examined.

OBJECTIVE

The aim of this study was to examine the association of individual fasting NEFAs with HF risk in older adults.

METHODS

In this prospective cohort study of older adults, we measured 35 individual NEFAs in 2,140 participants of the Cardiovascular Health Study using gas chromatography. HF was ascertained using review of medical records by an endpoint committee.

RESULTS

The mean age was 77.7 ± 4.4 years, and 38.8% were male. During a median follow-up of 9.7 (maximum 19.0) years, 655 new cases of HF occurred. In a multivariable Cox regression model controlling for demographic and anthropometric variables, field center, education, serum albumin, glomerular filtration rate, physical activity, alcohol consumption, smoking, hormone replacement therapy, unintentional weight loss, and all other measured NEFAs, we observed inverse associations (HR [95% CI] per standard deviation) of nonesterified pentadecanoic (15:0) (0.73 [0.57-0.94]), γ-linolenic acid (GLA) (0.87 [0.75-1.00]), and docosahexaenoic acid (DHA) (0.73 [0.61-0.88]) acids with HF, and positive associations of nonesterified stearic (18:0) (1.30 [1.04-1.63]) and nervonic (24:1n-9) (1.17 [1.06-1.29]) acids with HF.

CONCLUSION

Our data are consistent with a higher risk of HF with nonesterified stearic and nervonic acids and a lower risk with nonesterified 15:0, GLA, and DHA in older adults. If confirmed in other studies, specific NEFAs may provide new targets for HF prevention.

A novel fluorescent probe for rapid detection of sulfur dioxide in living cells

Sulfur dioxide is one of the reactive sulfur species, which has significant physiological functions in cells. Some physiological processes are closely related to SO₂ in organisms, and the high concentration of SO₂ in living cells can cause many diseases. In order to investigate the unique function of SO₂ at the subcellular level, developing a molecular tool which could detect of SO₂ within organelles is imperative. Hence, we developed a cationic dye named HQ-SO₂ as a new fluorescent probe to specifically monitor SO₂ , which was easy to obtain through one-step reaction. It took Michael addition reaction as the mechanism of reaction for detection of SO₂ . In addition, this probe showed a series of highly favorable properties such as rapid response rate, low cytotoxicity, high selectivity, low detection limit, and good photostability, which enabled the probe to track SO₂ in living cells.

A combination of NLR and sST2 is associated with adverse cardiovascular events in patients with myocardial injury induced by moderate to severe acute carbon monoxide poisoning

Background

Indicators of adverse cardiovascular events in patients with acute carbon monoxide (CO) poisoning‐induced myocardial injury have not yet been elucidated.

Hypothesis

This study aimed at determining the risk factors for adverse cardiovascular events in patients with acute CO poisoning‐induced myocardial injury.

Methods

We enrolled patients with moderate‐to‐severe acute CO poisoning‐induced myocardial injury. Based on the occurrence of adverse cardiovascular events, the patients were assigned into event and non‐event group. Binary logistic regression analysis was performed to analyze the potential risk factors for cardiovascular adverse events.

Results

A total of 413 eligible patients were enrolled. Among them, 61 (14.8%) patients presented adverse cardiovascular events and were assigned to the event group while 352 patients were assigned to the non‐event group. Univariate analysis revealed that cTnI, Lac, and NLR levels at admission and sST2 at day 3 in the event group were significantly higher compared to those in the non‐event group. Subsequent multivariate analysis revealed that sST2 at day 3 and NLR at admission were independent risk factors for adverse cardiovascular events in patients with acute CO poisoning‐induced myocardial injury. Finally, the sensitivity, specificity, and AUC of sST2 at day 3 combined with NLR for event prediction were 79.5%, 82.8%, and 0.858, respectively.

Conclusion

A combination of sST2 at day 3 and NLR is a potential predictor for the occurrence of adverse cardiovascular events in patients with acute CO poisoning‐induced myocardial injury. Therefore, cardiovascular risk stratification should be taken into consideration, especially in patients with acute CO poisoning‐induced myocardial injury.

Association Study Between Genetic Variation in Whole Mitochondrial Genome and Ischemic Stroke

Mitochondrial DNA (mtDNA) affects the mitochondrial function, which is potentially related to susceptibility to ischemic stroke (IS). However, study on IS genetics by whole mitochondrial genome sequencing has not been extensively explored. Therefore, a two-stage study was designed to explore the relationship between the whole mitochondrial genome variants and IS. In the first stage, whole mitochondrial genomes of 52 IS patients and 55 controls were sequenced by next-generation sequencing. Fifty-three mtDNA mutation sites which may be related to the pathogenesis of IS were discovered. Nine unreported mtDNA variation sites were found for the first time. In the second larger Chinese cohort, we confirmed that m.T195C and m.T12338C in the mitochondrial D-loop region were the protective factors of IS, especially m.T195C and m.C311T in the LAA subtype. In conclusion, our study provided population genetic information and a reference for IS-relevant research, with wide applications in diagnosis, therapeutic treatments and prediction of IS.

MSS2 maintains mitochondrial function and is required for chitosan resistance, invasive growth, biofilm formation and virulence in Candida albicans

Candida albicans is the most prevalent fungal pathogen in humans, particularly in immunocompromised patients. In this study, by screening a C. albicans mutant library, we first identified that the MSS2 gene, an ortholog of Saccharomyces cerevisiae MSS2 required for mitochondrial respiration, mediates chitosan resistance. Upon treatment with 0.2% chitosan, the growth of mss2Δ strains was strikingly impaired, and MSS2 expression was significantly repressed by chitosan. Furthermore, mss2Δ strains exhibited slow growth on medium supplemented with glycerol as the sole carbon source. Similar to the chitosan-treated wild-type strain, the mss2Δ strain exhibited a significantly impaired ATP production ability. These data suggest that an antifungal mechanism of chitosan against C. albicans acts by inhibiting MSS2 gene expression, leading to repression of mitochondrial function. Normal respiratory function is suggested to be required for fungal virulence. Interestingly, the mss2Δ mutant strains exhibited significantly impaired invasive ability in vitro and ex vivo but retained normal hyphal development ability in liquid medium. Furthermore, the MSS2 deletion strains could not form robust biofilms and exhibited significantly reduced virulence. Collectively, these results demonstrated that the antifungal effect of chitosan against C. albicans is mediated via inhibition of mitochondrial biogenesis. These data may provide another strategy for antifungal drug development via inhibition of fungal mitochondria.

Borrelia burgdorferi infection induces long-term memory-like responses in macrophages with tissue-wide consequences in the heart

Lyme carditis is an extracutaneous manifestation of Lyme disease characterized by episodes of atrioventricular block of varying degrees and additional, less reported cardiomyopathies. The molecular changes associated with the response to Borrelia burgdorferi over the course of infection are poorly understood. Here, we identify broad transcriptomic and proteomic changes in the heart during infection that reveal a profound down-regulation of mitochondrial components. We also describe the long-term functional modulation of macrophages exposed to live bacteria, characterized by an augmented glycolytic output, increased spirochetal binding and internalization, and reduced inflammatory responses. In vitro, glycolysis inhibition reduces the production of tumor necrosis factor (TNF) by memory macrophages, whereas in vivo, it produces the reversion of the memory phenotype, the recovery of tissue mitochondrial components, and decreased inflammation and spirochetal burdens. These results show that B. burgdorferi induces long-term, memory-like responses in macrophages with tissue-wide consequences that are amenable to be manipulated in vivo.

Lyme carditis is a manifestation of Lyme disease characterized by episodes of atrioventricular block and additional cardiomyopathies. This study describes the proteomic and transcriptomic changes in the heart upon infection with Borrelia burgdorferi, and identifies innate immune memory hallmarks specific to the response to the spirochete that are amenable to therapeutic manipulation.

Loss of Mitochondrial Control Impacts Renal Health

Disruption of mitochondrial biosynthesis or dynamics, or loss of control over mitochondrial regulation leads to a significant alteration in fuel preference and metabolic shifts that potentially affect the health of kidney cells. Mitochondria regulate metabolic networks which affect multiple cellular processes. Indeed, mitochondria have established themselves as therapeutic targets in several diseases. The importance of mitochondria in regulating the pathogenesis of several diseases has been recognized, however, there is limited understanding of mitochondrial biology in the kidney. This review provides an overview of mitochondrial dysfunction in kidney diseases. We describe the importance of mitochondria and mitochondrial sirtuins in the regulation of renal metabolic shifts in diverse cells types, and review this loss of control leads to increased cell-to-cell transdifferentiation processes and myofibroblast-metabolic shifts, which affect the pathophysiology of several kidney diseases. In addition, we examine mitochondrial-targeted therapeutic agents that offer potential leads in combating kidney diseases.

Dissecting Cellular Mechanisms of Long-Chain Acylcarnitines-Driven Cardiotoxicity: Disturbance of Calcium Homeostasis, Activation of Ca2+-Dependent Phospholipases, and Mitochondrial Energetics Collapse

Long-chain acylcarnitines (LCAC) are implicated in ischemia-reperfusion (I/R)-induced myocardial injury and mitochondrial dysfunction. Yet, molecular mechanisms underlying involvement of LCAC in cardiac injury are not sufficiently studied. It is known that in cardiomyocytes, palmitoylcarnitine (PC) can induce cytosolic Ca²⁺ accumulation, implicating L-type calcium channels, Na⁺/Ca²⁺ exchanger, and Ca²⁺-release from sarcoplasmic reticulum (SR). Alternatively, PC can evoke dissipation of mitochondrial potential (ΔΨ_m) and mitochondrial permeability transition pore (mPTP). Here, to dissect the complex nature of PC action on Ca²⁺ homeostasis and oxidative phosphorylation (OXPHOS) in cardiomyocytes and mitochondria, the methods of fluorescent microscopy, perforated path-clamp, and mitochondrial assays were used. We found that LCAC in dose-dependent manner can evoke Ca²⁺-sparks and oscillations, long-living Ca²⁺ enriched microdomains, and, finally, Ca²⁺ overload leading to hypercontracture and cardiomyocyte death. Collectively, PC-driven cardiotoxicity involves: (I) redistribution of Ca²⁺ from SR to mitochondria with minimal contribution of external calcium influx; (II) irreversible inhibition of Krebs cycle and OXPHOS underlying limited mitochondrial Ca²⁺ buffering; (III) induction of mPTP reinforced by PC-calcium interplay; (IV) activation of Ca²⁺-dependent phospholipases cPLA2 and PLC. Based on the inhibitory analysis we may suggest that simultaneous inhibition of both phospholipases could be an effective strategy for protection against PC-mediated toxicity in cardiomyocytes.

Targeting ER stress and calpain activation to reverse age-dependent mitochondrial damage in the heart

Severity of cardiovascular disease increases markedly in elderly patients. In addition, many therapeutic strategies that decrease cardiac injury in adult patients are invalid in elderly patients. Thus, it is a challenge to protect the aged heart in the context of underlying chronic or acute cardiac diseases including ischemia-reperfusion injury. The cause(s) of this age-related increased damage remain unknown. Aging impairs the function of the mitochondrial electron transport chain (ETC), leading to decreased energy production and increased oxidative stress due to generation of reactive oxygen species (ROS). Additionally, ROS-induced oxidative stress can increase cardiac injury during ischemia-reperfusion by potentiating mitochondrial permeability transition pore (MPTP) opening. Aging leads to increased endoplasmic reticulum (ER) stress, which contributes to mitochondrial dysfunction, including reduced function of the ETC. The activation of both cytosolic and mitochondrial calcium-activated proteases termed calpains leads to mitochondrial dysfunction and decreased ETC function. Intriguingly, mitochondrial ROS generation also induces ER stress, highlighting the dynamic interaction between mitochondria and ER. Here, we discuss the role of ER stress in sensitizing and potentiating mitochondrial dysfunction in response to ischemia-reperfusion, and the promising potential therapeutic benefit of inhibition of ER stress and / or calpains to attenuate cardiac injury in elderly patients.

Cardiomyocyte specific deletion of p53 decreases cell injury during ischemia-reperfusion: Role of Mitochondria

p53 is a tumor suppressor protein with a very low content in the basal condition, but the content rapidly rises during stress conditions including ischemia-reperfusion. An increase in p53 content increases cardiac injury during ischemia-reperfusion. Since mitochondrial damage plays a key role in cardiac injury during ischemia-reperfusion, we asked if genetic ablation of p53 decreases cardiac injury by protecting mitochondria. Isolated, perfused hearts from cardiac specific p53 deletion or wild type underwent 25 min global ischemia at 37 °C and 60 min reperfusion. At the end of reperfusion, hearts were harvested for infarct size measurement. In separate groups, cardiac mitochondria were isolated at 30 min reperfusion. Time control hearts were buffer-perfused without ischemia. Compared to wild type, deletion of p53 improved cardiac functional recovery and decreased infarct size following ischemia-reperfusion. Oxidative phosphorylation was improved in p53 deletion mitochondria following ischemia-reperfusion compared to wild type. The net release of ROS generation from wild type but not in p53 deletion mitochondria was increased following ischemia-reperfusion. Peroxiredoxin 3 (PRDX 3) content was higher in p53 deletion than that in wild type, indicating that p53 deletion increases a key antioxidant. Ischemia-reperfusion led to increased spectrin cleavage (a marker of cytosolic calpain1 activation) in wild type but not in p53 deletion mice. Ischemia-reperfusion increased the truncation of mature AIF (apoptosis inducing factor, an indicator of mitochondrial calpain1 activation) in wild type but not in p53 deletion mice. The loss of cytochrome c from mitochondria was also decreased in p53 deletion following ischemia-reperfusion. Bcl-2 content was decreased in wild type but not in p53 deletion following reperfusion, suggesting that depletion of bcl-2 contributes to permeabilization of the mitochondrial outer membrane. Thus, deletion of p53 decreases cardiac injury by protecting mitochondria through attenuation of oxidative stress and calpain activation during ischemia-reperfusion.

Metabolomics applications in coronary artery disease personalized medicine

Coronary artery disease (CAD), the most common cardiovascular disease (CVD), contributes to significant mortality worldwide. CAD is a multifactorial disease wherein various factors contribute to its pathogenesis often complicating management. Biomarker based personalized medicine may provide a more effective way to individualize therapy in multifactorial diseases in general and CAD specifically. Systems' biology "Omics" biomarkers have been investigated for this purpose. These biomarkers provide a more comprehensive understanding on pathophysiology of the disease process and can help in identifying new therapeutic targets and tailoring therapy to achieve optimum outcome. Metabolomics biomarkers usually reflect genetic and non-genetic factors involved in the phenotype. Metabolomics analysis may provide better understanding of the disease pathogenesis and drug response variation. This will help in guiding therapy, particularly for multifactorial diseases such as CAD. In this chapter, advances in metabolomics analysis and its role in personalized medicine will be reviewed with comprehensive focus on CAD. Assessment of risk, diagnosis, complications, drug response and nutritional therapy will be discussed. Together, this chapter will review the current application of metabolomics in CAD management and highlight areas that warrant further investigation.

Inhibition of proteasome reveals basal mitochondrial ubiquitination

Strict quality control for mitochondrial proteins is necessary to ensure cell homeostasis. Two cellular pathways-Ubiquitin Proteasome System (UPS) and autophagy-contribute to mitochondrial homeostasis under stressful conditions. Here, we investigate changes to the mitochondria proteome and to the ubiquitin landscape at mitochondria in response to proteasome inhibition. Treatment of HeLa cells devoid of Parkin, the primary E3 ligase responsible for mitophagy, with proteasome inhibitor MG132 for a few hours caused mitochondrial oxidative stress and fragmentation, reduced energy output, and increased mitochondrial ubiquitination without inducing mitophagy. Overexpression of Parkin did not show any induction of mitophagy in response to MG132 treatment. Analysis of ubiquitin chains on isolated mitochondria revealed predominance of K48, K29 and K63-linked polyubiquitin. Interestingly, of all ubiquitinated mitochondrial proteins detected in response to MG132 treatment, a majority (≥90%) were intramitochondrial irrespective of Parkin expression. However, overall levels of these ubiquitinated mitochondrial proteins did not change significantly upon proteasome inhibition when evaluated by quantitative proteomics (LFQ and SILAC), suggesting that only a small portion are ubiquitinated under basal conditions. Another aspect of proteasome inhibition is significant enrichment of UPS, lysosomal and phagosomal components, and other heat shock proteins associated with isolated mitochondria. Taken together, our study highlights a critical role of UPS for ubiquitinating and removing imported proteins as part of a basal mitochondrial quality control system independent of Parkin. SIGNIFICANCE: As centers of cellular bioenergetics, numerous metabolic pathways and signaling cascades, the health of mitochondria is of utmost importance for ensuring cell survival. Due to their unique physiology, mitochondria are constantly subjected to damaging oxidative radicals (ROS) and protein import-related stress due to buildup of unfolded aggregate-prone proteins. Thus, for quality control purposes, mitochondria are constantly under surveillance by Autophagy and the Ubiquitin Proteasome System (UPS), both of which share ubiquitin as a common signal. The ubiquitin landscape of mitochondria has been studied in detail under stressful conditions, however, little is known about basal mitochondrial ubiquitination. Our study reveals that the extent of ubiquitination at mitochondria greatly increases upon proteasome inhibition, pointing to a large number of potential substrates for proteasomal degradation. Interestingly, most of the ubiquitination occurs on intramitochondrial proteins, components of the electron transport chain (ETC) and matrix-resident metabolic enzymes in particular. Moreover, numerous cytosolic UPS components, chaperones and autophagy-lysosomal proteins were recruited to mitochondria upon proteasome inhibition. Taken together, this suggests that the levels and functions of mitochondrial proteins are constantly regulated through ubiquitin-dependent proteasomal degradation even under basal conditions. Unclogging mitochondrial import channels may provide a mechanism to alleviate stress associated with mitochondrial protein import or to adapt cells according to their metabolic needs. Therefore, targeting the mitochondrial ubiquitination/deubiquitination machinery, such as improving the therapeutic potency of proteasome inhibitors, may provide an additional therapeutic arsenal against tumors.

Mitochondrial Import of Dengue Virus NS3 Protease and Cleavage of GrpEL1, a Cochaperone of Mitochondrial Hsp70

Dengue virus infections, which have been reported in nearly 140 countries, pose a significant threat to human health. The genome of dengue virus encodes three structural and seven nonstructural (NS) proteins along with two untranslated regions, one each on both ends. Among them, dengue protease (NS3) plays a pivotal role in polyprotein processing and virus multiplication. NS3 is also known to regulate several host proteins to induce and maintain pathogenesis. Certain viral proteins are known to interact with mitochondrial membrane proteins and interfere with their functions, but the association of a virus-coded protein with the mitochondrial matrix is not known. In this report, by using in silico analysis, we show that NS3pro alone is capable of mitochondrial import; however, this is dependent on its innate mitochondrial transport signal (MTS). Transient-transfection and protein import studies confirm the import of NS3pro to the mitochondrial matrix. Similarly, NS3pro-helicase (amino acids 1 to 464 of NS3) also targets the mitochondria. Intriguingly, reduced levels of matrix-localized GrpE protein homolog 1 (GrpEL1), a cochaperone of mitochondrial Hsp70 (mtHsp70), were noticed in NS3pro-expressing, NS3pro-helicase-expressing, and virus-infected cells. Upon the use of purified components, GrpEL1 undergoes cleavage, and the cleavage sites have been mapped to KR⁸¹A and QR⁹²S. Importantly, GrpEL1 levels are seriously compromised in severe dengue virus-infected clinical samples. Our studies provide novel insights into the import of NS3 into host mitochondria and identify a hitherto unknown factor, GrpEL1, as a cleavage target, thereby providing new avenues for dengue virus research and the design of potential therapeutics.IMPORTANCE Approximately 40% of the world's population is at risk of dengue virus infection. There is currently no specific drug or potential vaccine for these infections. Lack of complete understanding of the pathogenesis of the virus is one of the hurdles that must be overcome in developing antivirals for this virus infection. In the present study, we observed that the dengue virus-coded protease imports to the mitochondrial matrix, and our report is the first ever of a virus-coded protein, either animal or human, importing to the mitochondrial matrix. Our analysis indicates that the observed mitochondrial import is due to an inherited mitochondrial transport signal. We also show that matrix-localized GrpE protein homolog 1 (GrpEL1), a cochaperone of mitochondrial Hsp70 (mtHsp70), is also the substrate of dengue virus protease, as observed in vitro and ex vivo in virus-infected cells and dengue virus-infected clinical samples. Hence, our studies reveal an essential aspect of the pathogenesis of dengue virus infections, which may aid in developing antidengue therapeutics.

The cardiolipin-binding peptide elamipretide mitigates fragmentation of cristae networks following cardiac ischemia reperfusion in rats

Mitochondrial dysfunction contributes to cardiac pathologies. Barriers to new therapies include an incomplete understanding of underlying molecular culprits and a lack of effective mitochondria-targeted medicines. Here, we test the hypothesis that the cardiolipin-binding peptide elamipretide, a clinical-stage compound under investigation for diseases of mitochondrial dysfunction, mitigates impairments in mitochondrial structure-function observed after rat cardiac ischemia-reperfusion. Respirometry with permeabilized ventricular fibers indicates that ischemia-reperfusion induced decrements in the activity of complexes I, II, and IV are alleviated with elamipretide. Serial block face scanning electron microscopy used to create 3D reconstructions of cristae ultrastructure reveals that disease-induced fragmentation of cristae networks are improved with elamipretide. Mass spectrometry shows elamipretide did not protect against the reduction of cardiolipin concentration after ischemia-reperfusion. Finally, elamipretide improves biophysical properties of biomimetic membranes by aggregating cardiolipin. The data suggest mitochondrial structure-function are interdependent and demonstrate elamipretide targets mitochondrial membranes to sustain cristae networks and improve bioenergetic function.

The Commonalities and Differences in Mitochondrial Dysfunction Between ex vivo and in vivo Myocardial Global Ischemia Rat Heart Models: Implications for Donation After Circulatory Death Research

Heart transplantation is the ultimate treatment option for patients with advanced heart failure. Since hearts from donation after brain death (DBD) donors are limited, donation after circulatory death (DCD) donor hearts could be another source for heart transplantation. DCD process involves ischemia-reperfusion (IR) injury. Mitochondrial dysfunction contributes to IR and is well established in the ex vivo (buffer perfused) ischemia animal model. However, DCD hearts undergo in vivo ischemia with a variable "ischemic period." In addition, the DCD hearts are exposed to an intense catecholamine surge that is not seen with ex vivo perfused hearts. Thus, the severity of mitochondrial damage in in vivo ischemia hearts could differ from the ex vivo ischemia hearts even following the same period of ischemia. The aim of our current study is to identify the mitochondrial dysfunction in DCD hearts and propose strategies to protect mitochondria. Adult Sprague Dawley rat hearts underwent in vivo or ex vivo ischemia for 25 min. Subsarcolemmal mitochondria (SSM) and interfibrillar mitochondria (IFM) were isolated from hearts following ischemia. We found that both ex vivo and in vivo ischemia led to decreased oxidative phosphorylation in SSM and IFM compared to time control or DBD hearts. The proportion of damage to SSM and IFM, including proton leak through the inner membrane, was higher with ex vivo ischemia compare to in vivo ischemia. Time control hearts showed a decrease in SSM and IFM function compared to DBD hearts. The calcium retention capacity (CRC) was also decreased in SSM and IFM with ex vivo and in vivo ischemia, indicating that ischemic damage to mitochondria sensitizes mitochondrial permeability transition pores (MPTP). Our study found differential mitochondrial damage between the in vivo ischemia and the ex vivo ischemia setup. Therefore, consideration should be given to the mode of ischemia while evaluating and testing myocardial protective interventions targeting mitochondria to reduce IR injury in hearts.

Experimental Study of Heart Functionality during Treatment of Chronic Heart Failure in Rats of Different Age Groups with Levosimendan (Experimental Study)

Levosimendan is effective in the therapy of chronic heart failure in both mature and old rats, but the duration of its therapeutic effect differs in these age groups. In 15 days after treatment, the myocardium in old rats maintained augmented functionality, whereas in old animals, functional potencies returned to the levels observed prior to the therapy. Stimulation of tissue respiration with combined administration of L-carnitine and α-lipoic acid against the background of levosimendan treatment prolonged its therapeutic effect in mature, but not in old rats.

The Aging of γδ T Cells

In the coming decades, many developed countries in the world are expecting the "greying" of their populations. This phenomenon poses unprecedented challenges to healthcare systems. Aging is one of the most important risk factors for infections and a myriad of diseases such as cancer, cardiovascular and neurodegenerative diseases. A common denominator that is implicated in these diseases is the immune system. The immune system consists of the innate and adaptive arms that complement each other to provide the host with a holistic defense system. While the diverse interactions between multiple arms of the immune system are necessary for its function, this complexity is amplified in the aging immune system as each immune cell type is affected differently-resulting in a conundrum that is especially difficult to target. Furthermore, certain cell types, such as γδ T cells, do not fit categorically into the arms of innate or adaptive immunity. In this review, we will first introduce the human γδ T cell family and its ligands before discussing parallels in mice. By covering the ontogeny and homeostasis of γδ T cells during their lifespan, we will better capture their evolution and responses to age-related stressors. Finally, we will identify knowledge gaps within these topics that can advance our understanding of the relationship between γδ T cells and aging, as well as age-related diseases such as cancer.

The Functions of Mitochondrial 2',3'-Cyclic Nucleotide-3'-Phosphodiesterase and Prospects for Its Future

2′,3′-cyclic nucleotide-3′-phosphodiesterase (CNPase) is a myelin-associated enzyme that catalyzes the phosphodiester hydrolysis of 2’,3’-cyclic nucleotides to 2’-nucleotides. However, its presence is also found in unmyelinated cells and other cellular structures. Understanding of its specific physiological functions, particularly in unmyelinated cells, is still incomplete. This review concentrates on the role of mitochondrial CNPase (mtCNPase), independent of myelin. mtCNPase is able to regulate the functioning of the mitochondrial permeability transition pore (mPTP), and thus is involved in the mechanisms of cell death, both apoptosis and necrosis. Its participation in the development of various diseases and pathological conditions, such as aging, heart disease and alcohol dependence, is also reviewed. As such, mtCNPase can be considered as a potential target for the development of therapeutic strategies in the treatment of mitochondria-related diseases.

Gerontoxanthone I and Macluraxanthone Induce Mitophagy and Attenuate Ischemia/Reperfusion Injury

Mitophagy is a crucial process in controlling mitochondrial biogenesis. Balancing mitophagy and mitochondrial functions is required for maintaining cellular homeostasis. In this study, we found that Gerontoxanthone I (GeX1) and Macluraxanthone (McX), xanthone derivatives isolated from Garcinia bracteata C. Y. Wu ex Y. H. Li, induced Parkin puncta accumulation and promoted mitophagy. GeX1 and McX treatment induced the degradation of mitophagy-related proteins such as Tom20 and Tim23. GeX1 and McX directly stabilized PTEN-induced putative kinase 1 (PINK1) on the outer membrane of the mitochondria, and then recruited Parkin to mitochondria. This significantly induced phosphorylation and ubiquitination of Parkin, suggesting that GeX1 and McX mediate mitophagy through the PINK1-Parkin pathway. Transfecting ParkinS65A or pretreated MG132 abolished the induction effects of GeX1 and McX on mitophagy. Furthermore, GeX1 and McX treatment decreased cell death and the level of ROS in an ischemia/reperfusion (IR) injury model in H9c2 cells compared to a control group. Taken together, our data suggested that GeX1 and McX induce PINK1-Parkin–mediated mitophagy and attenuate myocardial IR injury in vitro.

The Pheromone and Pheromone Receptor Mating-Type Locus Is Involved in Controlling Uniparental Mitochondrial Inheritance in Cryptococcus

Mitochondria are inherited uniparentally during sexual reproduction in the majority of eukaryotic species studied, including humans, mice, and nematodes, as well as many fungal species. Mitochondrial uniparental inheritance (mito-UPI) could be beneficial in that it avoids possible genetic conflicts between organelles with different genetic backgrounds, as recently shown in mice, and it could prevent the spread of selfish genetic elements in the mitochondrial genome. Despite the prevalence of observed mito-UPI, the underlying mechanisms and the genes involved in controlling this non-Mendelian inheritance are poorly understood in many species. In Cryptococcus neoformans, a human pathogenic basidiomyceteous fungus, mating types (MATα and MATa) are defined by alternate alleles at the single MAT locus that evolved from fusion of the two MAT loci (P/R encoding pheromones and pheromone receptors, and HD encoding homeodomain transcription factors) that are the ancestral state in the basidiomycota. Mitochondria are inherited uniparentally from the MATa parent in C. neoformans, and this requires the SXI1α and SXI2a HD factors encoded by MAT However, there is evidence that additional genes contribute to the control of mito-UPI in Cryptococcus Here, we show that in C. amylolentus, a sibling species of C. neoformans with unlinked P/R and HD MAT loci, mito-UPI is controlled by the P/R locus and is independent of the HD locus. Consistently, by replacing the MATα alleles of the pheromones (MF) and pheromone receptor (STE3) with the MATa alleles, we show that these P/R locus-defining genes indeed affect mito-UPI in C. neoformans during sexual reproduction. Additionally, we show that during early stages of C. neoformans sexual reproduction, conjugation tubes are always produced by the MATα cells, resulting in unidirectional migration of the MATα nucleus into the MATa cell during zygote formation. This process is controlled by the P/R locus and could serve to physically restrict movement of MATα mitochondria in the zygotes, and thereby contribute to mito-UPI. We propose a model in which both physical and genetic mechanisms function in concert to prevent the coexistence of mitochondria from the two parents in the zygote, and subsequently in the meiotic progeny, thus ensuring mito-UPI in pathogenic Cryptococcus, as well as in closely related nonpathogenic species. The implications of these findings are discussed in the context of the evolution of mito-UPI in fungi and other more diverse eukaryotes.

Dexmedetomidine Improves Cardiovascular and Ventilatory Outcomes in Critically Ill Patients: Basic and Clinical Approaches

Dexmedetomidine (DEX) is a highly selective α2-adrenergic agonist with sedative and analgesic properties, with minimal respiratory effects. It is used as a sedative in the intensive care unit and the operating room. The opioid-sparing effect and the absence of respiratory effects make dexmedetomidine an attractive adjuvant drug for anesthesia in obese patients who are at an increased risk for postoperative respiratory complications. The pharmacodynamic effects on the cardiovascular system are known; however the mechanisms that induce cardioprotection are still under study. Regarding the pharmacokinetics properties, this drug is extensively metabolized in the liver by the uridine diphosphate glucuronosyltransferases. It has a relatively high hepatic extraction ratio, and therefore, its metabolism is dependent on liver blood flow. This review shows, from a basic clinical approach, the evidence supporting the use of dexmedetomidine in different settings, from its use in animal models of ischemia-reperfusion, and cardioprotective signaling pathways. In addition, pharmacokinetics and pharmacodynamics studies in obese subjects and the management of patients subjected to mechanical ventilation are described. Moreover, the clinical efficacy of delirium incidence in patients with indication of non-invasive ventilation is shown. Finally, the available evidence from DEX is described by a group of Chilean pharmacologists and clinicians who have worked for more than 10 years on DEX.

Potential therapeutic targets for lung repair during human ex vivo lung perfusion

Introduction

The ex vivo lung perfusion (EVLP) technique has been developed to assess the function of marginal donor lungs and has significantly increased donor lung utilisation. EVLP has also been explored as a platform for donor lung repair through injury-specific treatments such as antibiotics or fibrinolytics. We hypothesised that actively expressed pathways shared between transplantation and EVLP may reveal common mechanisms of injury and potential therapeutic targets for lung repair prior to transplantation.

Materials and methods

Retrospective transcriptomics analyses were performed with peripheral tissue biopsies from “donation after brain death” lungs, with 46 pre-/post-transplant pairs and 49 pre-/post-EVLP pairs. Pathway analysis was used to identify and compare the responses of donor lungs to transplantation and to EVLP.

Results

22 pathways were enriched predominantly in transplantation, including upregulation of lymphocyte activation and cell death and downregulation of metabolism. Eight pathways were enriched predominantly in EVLP, including downregulation of leukocyte functions and upregulation of vascular processes. 27 pathways were commonly enriched, including activation of innate inflammation, cell death, heat stress and downregulation of metabolism and protein synthesis. Of the inflammatory clusters, Toll-like receptor/innate immune signal transduction adaptor signalling had the greatest number of nodes and was central to inflammation. These mechanisms have been previously speculated as major mechanisms of acute lung injury in animal models.

Conclusion

EVLP and transplantation share common molecular features of injury including innate inflammation and cell death. Blocking these pathways during EVLP may allow for lung repair prior to transplantation.

Artesunate targets oral tongue squamous cell carcinoma via mitochondrial dysfunction-dependent oxidative damage and Akt/AMPK/mTOR inhibition

Although mitochondrial metabolism has recently gained attention as a promising therapeutic strategy in cancer, little is known on the impact of mitochondrial respiration inhibition on oral tongue squamous cell carcinoma (OTSCC). Using in vitro and in vivo OTSCC models, our work demonstrates that inducing mitochondrial dysfunction by anti-malarial drug artesunate is effective in targeting OTSCC stem-cell like and bulk cells. Artesunate inhibits anchorage-independent colony formation, proliferation and survival in all tested OTSCC cell lines although with varying efficacy. Artesunate displays preferential anti-OTSCC activity by sparing normal cells. Mechanism analysis indicates that artesunate inhibits mitochondrial respiration via suppressing mitochondrial complex I and II but not IV or V, resulting in oxidative stress and damage. Interestingly, OTSCC cells that are more sensitive to artesunate have higher level of basal mitochondrial respiration and reversed respiratory capacity compared to those with less sensitivity to artesunate, suggesting the varying dependence on mitochondrial respiration among OTSCC cell lines. In addition, artesunate induces oxidative stress and damage in cells with low sensitivity to a less extent than in those with high sensitivity. We confirm that mitochondrial respiration inhibition is required for the action of artesunate in OTSCC. Mitochondrial dysfunction by artesunate further activates AMPK and suppresses Akt/mTOR. Importantly, the in vitro observations are reproducible in vivo OTSCC xenograft mouse model. Our findings provide pre-clinical evidence on the efficacy of artesunate and emphasize the therapeutic value of targeting mitochondrial respiration in OTSCC.

Chronic GPER1 Activation Protects Against Oxidative Stress-Induced Cardiomyoblast Death via Preservation of Mitochondrial Integrity and Deactivation of Mammalian Sterile-20-Like Kinase/Yes-Associated Protein Pathway

Introduction: Estrogen (17β-estradiol, E2) is well-known to induce cardioprotective effects against ischemia/reperfusion (I/R) injury. We recently reported that acute application of E2 at the onset of reperfusion in vivo induces cardioprotective effects against I/R injury via activation of its non-steroidal receptor, G protein-coupled estrogen receptor 1 (GPER1). Here, we investigated the impact and mechanism underlying chronic GPER1 activation in cultured H9c2 rat cardiomyoblasts. Methods: H9c2 rat cardiomyoblasts were cultured and pretreated with the cytotoxic agent H₂O₂ for 24 h and incubated in the presence of vehicle (control), GPER1 agonists E2 and G1, or GPER1 agonists supplemented with G15 (GPER1 antagonist) for 48 or 96 h. After treatment, cells were collected to measure the rate of cell death and viability using flow cytometry and Calcein AM assay or MTT assay, respectively. The resistance to opening of the mitochondrial permeability transition pore (mPTP), the mitochondrial membrane potential, and ATP production was assessed using fluorescence microscopy, and the mitochondrial structural integrity was observed with electron microscopy. The levels of the phosphorylation of mammalian sterile-20-like kinase (MST1) and yes-associated protein (YAP) were assessed by Western blot analysis in whole-cell lysate, while the expression levels of mitochondrial biogenesis genes, YAP target genes, and proapoptotic genes were measured by qRT-PCR. Results: We found that after H₂O₂ treatment, chronic E2/G1 treatment decreased cell death effect was associated with the prevention of the S phase of the cell cycle arrest compared to control. In the mitochondria, chronic E2/G1 activation treatment preserved the cristae morphology, and increased resistance to opening of mPTP, but with little change to mitochondrial fusion/fission. Additionally, chronic E2/G1 treatment predominantly reduced phosphorylation of MST1 and YAP, as well as increased MST1 and YAP protein levels. E2 treatment also upregulated the expression levels of TGF-β and PGC-1α mRNAs and downregulated PUMA and Bim mRNAs. Except for ATP production, all the E2 or G1 effects were prevented by the cotreatment with the GPER1 antagonist, G15. Conclusion: Together, these results indicate that chronic GPER1 activation with its agonists E2 or G1 treatment protects H9c2 cardiomyoblasts against oxidative stress-induced cell death and increases cell viability by preserving mitochondrial structure and function as well as delaying the opening of mPTP. These chronic GPER1 effects are associated with the deactivation of the non-canonical MST1/YAP mechanism that leads to genetic upregulation of cell growth genes (CTGF, CYR61, PGC-1α, and ANKRD1), and downregulation of proapoptotic genes (PUMA and Bim).

Toxicological effects of ciprofloxacin exposure to Drosophila melanogaster

The abuse of ciprofloxacin (CIP) may cause serious side effects and the mechanisms underlying these effects remain unclear. Here, we determinate the 48 h, 72 h and 96 h LC₅₀ values of CIP to Drosophila melanogaster and demonstrate a series of adverse effects after D. melanogaster was exposed to CIP at a sublethal concentration (3.2 mg mL^-1). Treated individuals showed shorter lifespan, delayed development and many of the treated larvae failed to pupate or hatch. Smaller body size was observed at every life stage when exposed to CIP and the size of pupae, the weight of third-instar larvae exhibited a perfectly dose-response relationship that the larger concentration exposed to, the smaller body size or lighter weight is. Moreover, reduction in fat body cell viability, elevated oxidative stress markers (SOD and CAT) and down-regulation of diap1, ex, two target genes of Yorkie (Yki), was observed in response to CIP exposure. Most importantly, we found two types of black spot in Drosophila and the proportion of larvae with a black spot was positively related to the treatment dose, which is new in the field. This study provides a scientific basis for the potential harm caused by abuse of quinolones with the goal of urging cautious use of antibiotics.

Bilobalide protects H9c2 cell from oxygen-glucose-deprivation-caused damage through upregulation of miR-27a

Background: Myocardial ischemia is a troublesome disease. Bilobalide possesses multiple biological functions. We researched the consequents of bilobalide in OGD-irritated H9c2 cells. Methods: OGD-stimulated H9c2 cells were treated by bilobalide, and/or transfected with miR-27a inhibitor or negative control. Use CCK-8 and flow cytometry to test cell activity and apoptosis, respectively. Luciferase activity experiment was to test targeting link between miR-27a and Tmub1. Levels of cell-cycle and apoptosis relative proteins and phosphorylation of PI3K/AKT and Wnt/β-catenin related proteins were detected through western blot. Results: OGD stimulation reduced cell activity and negatively regulated the expression of CDK4, CDK6 and CyclinD1. Cell apoptosis was increased and its related proteins were affected by OGD. Bilobalide administration reversed all the results above caused by OGD. OGD negatively regulated miR-27a while bilobalide upregulated miR-27a. miR-27a's target gene was Tmub1. The protection consequents of bilobalide were suppressed when cells were transfected with a miR-27a inhibitor that cell activity was reduced and apoptosis was raised. Attenuation in the phosphorylation level of PI3K, AKT and β-catenin by OGD was reversed by bilobalide, whereas there were opposite results after transfected with miR-27a inhibitor. Conclusion: Bilobalide relieved OGD-caused H9c2 cell damage, raising cell activity and attenuating apoptosis via upregulating miR-27a and activating of PI3K/AKT and Wnt/β-catenin signal pathway. Highlights Bilobalide alleviates OGD-induced H9c2 cell injury. Bilobalide upregulates miR-27a expression in OGD-stimulated H9c2 cells. Bilobalide alleviates cell injury by upregulation of miR-27a. Bilobalide actuates PI3K/AKT and Wnt/β-catenin pathways.

Empagliflozin, a sodium glucose co-transporter-2 inhibitor, alleviates atrial remodeling and improves mitochondrial function in high-fat diet/streptozotocin-induced diabetic rats

BACKGROUND

Diabetes mellitus is an important risk factor for atrial fibrillation (AF) development. Sodium-glucose co-transporter-2 (SGLT-2) inhibitors are used for the treatment of type 2 diabetes mellitus (T2DM). Their cardioprotective effects have been reported but whether they prevent AF in T2DM patients are less well-explored. We tested the hypothesis that the SGLT-2 inhibitor, empagliflozin, can prevent atrial remodeling in a diabetic rat model.

METHODS

High-fat diet and low-dose streptozotocin (STZ) treatment were used to induce T2DM. A total of 96 rats were randomized into the following four groups: (i) control (ii) T2DM, (iii) low-dose empagliflozin (10 mg/kg/day)/T2DM; and (iv) high-dose empagliflozin (30 mg/kg/day)/T2DM by the intragastric route for 8 weeks.

RESULTS

Compared with the control group, left atrial diameter, interstitial fibrosis and the incidence of AF inducibility were significantly increased in the DM group. Moreover, atrial mitochondrial respiratory function, mitochondrial membrane potential, and mitochondrial biogenesis were impaired. Empagliflozin treatment significantly prevented the development of these abnormalities in DM rats, likely via the peroxisome proliferator-activated receptor-c coactivator 1α (PGC-1α)/nuclear respiratory factor-1 (NRF-1)/mitochondrial transcription factor A (Tfam) signaling pathway.

CONCLUSIONS

Empagliflozin can ameliorate atrial structural and electrical remodeling as well as improve mitochondrial function and mitochondrial biogenesis in T2DM, hence may be potentially used in the prevention of T2DM-related atrial fibrillation.

Mitophagy in the Hippocampus Is Excessive Activated After Cardiac Arrest and Cardiopulmonary Resuscitation

This study examined the activation of mitophagy following cardiac arrest (CA) and cardiopulmonary resuscitation (CPR) and the relationship between the change with time and apoptosis.

MAIN METHODS

The male Sprague-Dawley rats were randomized into four groups: Sham group, CPR24h group, CPR48h group, CPR72h group. The rat model of cardiac arrest was established by asphyxiation. We employed western blot to analyze the levels of mitophagy related proteins of hippocampus, JC-1 to detect mitochondrial membrane potential (MMP) and flow cytometry to measure the rate of apoptosis of hippocampal neurons. Moreover, we also intuitively observed the occurrence of mitophagy through electron microscopy.

KEY FINDINGS

The results showed that the levels of TOMM20 and Tim23 protein were significantly decreased after CPR, which were more remarkable following 72 h of CPR. However, the protein levels of dynamin related protein 1 (Drp1) and cytochrome C (Cyt-c) were strongly up-regulated after CPR. Meanwhile, the hippocampal MMP decreased gradually with time after CPR. Furthermore, we more intuitively verified the activation of mitophagy through electron microscopy. In addition, the rats of apoptosis rate of hippocampus after CPR were significantly increased, which were gradually enhanced over time from 24 h until at least 72 h following CPR.

SIGNIFICANCE

with the enhancement of mitophagy, the apoptosis of hippocampal neurons was gradually enhanced, which suggested mitophagy may be excessive activated and aggravating brain damage after CA and CPR.

Evolutionary genomics analysis of human nucleus-encoded mitochondrial genes: implications for the roles of energy production and metabolic pathways in the pathogenesis and pathophysiology of demyelinating diseases

The myelin sheath is a plasma membrane extension that lines nerve fibers to protect, support and insulate neurons. The myelination of axons in vertebrates enables fast, saltatory impulse propagation, and this process relies on organelles, especially on mitochondria to supply energy. Approximately 99% of mitochondrial proteins are encoded in the nucleus. Since mitochondria play a central role in the energy production and metabolic pathways, which are essential for myelinogenesis, studying these nucleus-encoded genes (nMGs) may provide new insights into the roles of energy metabolism in demyelinating diseases. In this work, a multiomics-based approach was employed to 1) construct a 1,740 human nMG subset with mitochondrial localization evidence obtained from the Integrated Mitochondrial Protein Index (IMPI) and MitoCarta databases, 2) conduct an evolutionary genomics analysis across mouse, rat, monkey, chimp, and human models, 3) examine dysmyelination phenotype-related genes (nMG subset genes with oligodendrocyte- ​and myelin-related ​phenotypes, OMP-nMGs) in MGI mouse lines and human patients, 4) determine the expression discrepancy of OMP-nMGs in brain tissues of cuprizone-treated mice, multiple sclerosis patients, and normal controls, and 5) conduct literature data mining to explore OMP-nMG-associated disease impacts. By contrasting OMP-nMGs with other genes, OMP-nMGs were found to be more ubiquitously expressed (59.1% vs. 16.1%), disease-associated (67.3% vs. 20.2%), and evolutionarily conserved within the human populations. Our multiomics-based analysis identified 110 OMP-nMGs implicated in energy production and lipid and glycan biosynthesis in the pathogenesis and pathophysiology of demyelinating disorders. Future targeted characterization of OMP-nMGs in abnormal myelination conditions may allow the discovery of novel nMG mediated mechanisms underlying myelinogenesis and related diseases.

The Role of Mitochondria in the Mechanisms of Cardiac Ischemia-Reperfusion Injury

Mitochondria play a critical role in maintaining cellular function by ATP production. They are also a source of reactive oxygen species (ROS) and proapoptotic factors. The role of mitochondria has been established in many aspects of cell physiology/pathophysiology, including cell signaling. Mitochondria may deteriorate under various pathological conditions, including ischemia-reperfusion (IR) injury. Mitochondrial injury can be one of the main causes for cardiac and other tissue injuries by energy stress and overproduction of toxic reactive oxygen species, leading to oxidative stress, elevated calcium and apoptotic and necrotic cell death. However, the interplay among these processes in normal and pathological conditions is still poorly understood. Mitochondria play a critical role in cardiac IR injury, where they are directly involved in several pathophysiological mechanisms. We also discuss the role of mitochondria in the context of mitochondrial dynamics, specializations and heterogeneity. Also, we wanted to stress the existence of morphologically and functionally different mitochondrial subpopulations in the heart that may have different sensitivities to diseases and IR injury. Therefore, various cardioprotective interventions that modulate mitochondrial stability, dynamics and turnover, including various pharmacologic agents, specific mitochondrial antioxidants and uncouplers, and ischemic preconditioning can be considered as the main strategies to protect mitochondrial and cardiovascular function and thus enhance longevity.

Diagnosis and Treatment of Genetic HFE-Hemochromatosis: The Danish Aspect

This paper outlines the Danish aspects of HFE-hemochromatosis, which is the most frequent genetic predisposition to iron overload in the five million ethnic Danes; more than 20,000 people are homozygous for the C282Y mutation and more than 500,000 people are compound heterozygous or heterozygous for the HFE-mutations. The disorder has a long preclinical stage with gradually increasing body iron overload and eventually 30% of men will develop clinically overt disease, presenting with symptoms of fatigue, arthralgias, reduced libido, erectile dysfunction, cardiac disease and diabetes. Subsequently the disease may progress into irreversible arthritis, liver cirrhosis, cardiomyopathy, pancreatic fibrosis and osteoporosis. The effective standard treatment is repeated phlebotomies, which in the preclinical and early clinical stages ensures a normal survival rate. Early detection of the genetic predisposition to the disorder is therefore important to reduce the overall burden of clinical disease. Population screening seems to be cost-effective and should be considered.

Mitochondria Lysine Acetylation and Phenotypic Control

Mitochondria have a central role in cellular metabolism and reversible post-translational modifications regulate activity of mitochondrial proteins. Thanks to advances in proteomics, lysine acetylation has arisen as an important post-translational modification in the mitochondrion. During acetylation an acetyl group is covalently attached to the epsilon amino group in the side chain of lysine residues using acetyl-CoA as the substrate donor. Therefore the positive charge is neutralized, and this can affect the function of proteins thereby regulating enzyme activity, protein interactions, and protein stability. The major deacetylase in mitochondria is SIRT3 whose activity regulates many mitochondrial enzymes. The method of choice for the analysis of acetylated proteins foresees the combination of mass spectrometry-based proteomics with affinity enrichment techniques. Beyond the identification of lysine-acetylated proteins, many studies are moving towards the characterization of acetylated patterns in different diseases. Indeed, modifications in lysine acetylation status can directly alter mitochondrial function and, therefore, be linked to human diseases such as metabolic diseases, cancer, myocardial injury and neurodegenerative diseases. Despite the progress in the characterization of different lysine acetylation sites, additional studies are needed to differentiate the specific changes with a significant biological relevance.

Predicting Outcome After Out-of-Hospital Cardiac Arrest: Lactate, Need for Vasopressors, and Cytochrome c

BACKGROUND

Outcome prediction after out-of-hospital cardiac arrest (OHCA) is difficult. We hypothesized that lactate and need for vasopressors would predict outcome, and that addition of a mitochondrial biomarker would enhance performance of the tool.

METHODS

Prospective observational study of OHCA patients presenting to an academic medical center September 2008 to April 2016. We conducted univariate and multivariate logistic regressions.

RESULTS

Patients were divided based on 2 variables: vasopressor status and initial lactate (<5 mmol/L, 5-10, ≥10). Three hundred fifty-two patients were evaluated; 249 had a lactate within 3 hours and were included. Patients on vasopressors had higher mortality (74% vs 40%; P < .001). A stepwise increase in mortality is associated with increasing lactate (45% lactate <5, 66% 5-10, and 83% ≥10; P < 001). Multivariable models with lactate group and vasopressors as predictors demonstrated excellent discrimination (area under the receiver operating curve [AUC]: 0.73 [95% confidence interval, CI: 0.66-0.79]; adjusted for additional covariates: AUC: 0.81 [95% CI: 0.75-0.86]). Thirty-six patients had cytochrome c levels available; among these 36, when comparing models with and without cytochrome c, there was no difference (AUC: 0.88 [95% CI: 0.76-1.00] vs AUC: 0.85 [95% CI: 0.73-0.98], respectively; P = .30).

CONCLUSION

In this prospective validation, the combination of lactate and vasopressors in the immediate postarrest period is predictive of mortality. Cytochrome c offered minimal additional predictive power.

Inhibition of the ubiquitous calpains protects complex I activity and enables improved mitophagy in the heart following ischemia-reperfusion

Activation of calpain 1 (CPN1) and calpain 2 (CPN2) contributes to cardiac injury during ischemia (ISC) and reperfusion (REP). Complex I activity is decreased in heart mitochondria following ISC-REP. CPN1 and CPN2 are ubiquitous calpains that exist in both cytosol (cs)-CPN1 and 2 and mitochondria (mit)-CPN1 and 2. Recent work shows that the complex I subunit (NDUFS7) is a potential substrate of the mit-CPN1. We asked whether ISC-REP led to decreased complex I activity via proteolysis of the NDUFS7 subunit via activation of mit-CPN1 and -2. Activation of cs-CPN1 and -2 decreases mitophagy in hepatocytes following ISC-REP. We asked whether activation of cs-CPN1 and -2 impaired mitophagy in the heart following ISC-REP. Buffer-perfused rat hearts underwent 25 min of global ISC and 30 min of REP. MDL-28170 (MDL; 10 µM) was used to inhibit CPN1 and -2. Cytosol, subsarcolemmal mitochondria (SSM), and interfibrillar mitochondria (IFM) were isolated at the end of heart perfusion. Cardiac ISC-REP led to decreased complex I activity with a decrease in the content of NDUFS7 in both SSM and IFM. ISC-REP also resulted in a decrease in cytosolic beclin-1 content, a key component of the autophagy pathway required to form autophagosomes. MDL treatment protected the contents of cytosolic beclin-1 and mitochondrial NDUFS7 in hearts following ISC-REP. These results support that activation of both cytosolic and mitochondrial calpains impairs mitochondria during cardiac ISC-REP. Mitochondria-localized calpains impair complex I via cleavage of a key subunit. Activation of cytosolic calpains contributes to mitochondrial dysfunction by impairing removal of the impaired mitochondria through depletion of a key component of the mitophagy process.

Mitochondrial Involvement in the Adaptive Response to Chronic Exposure to Environmental Pollutants and High-Fat Feeding in a Rat Liver and Testis

In our modern society, exposure to stressful environmental stimuli, such as pollutants and/or chronic high-fat feeding, continuously induce tissular/organ metabolic adaptation to promote cellular survival. In extreme conditions, cellular death and tissular/organ damage occur. Mitochondria, as a cellular energy source, seem to play an important role in facing cellular stress induced by these environmental stimuli. On the other hand, mitochondrial dysfunction and oxidative stress play a key role in environmental stress-induced metabolic diseases. However, little is known about the combined effect of simultaneous exposure to chronic high-fat feeding and environmental pollutants on metabolic alterations at a tissular and cellular level, including mitochondrial dysfunction and oxidative stress induction. Our research group recently addressed this topic by analysing the effect of chronic exposure to a non-toxic dose of the environmental pollutant dichlorodiphenyldichloroethylene (DDE) associated with high-fat feeding in male Wistar rats. In this review, we mainly summarize our recent findings on mitochondrial adaptive response and oxidative stress induction in the liver, the main tissue involved in fat metabolism and pollutant detoxification, and in male gonads, the main targets of endocrine disruption induced by both high-fat feeding and environmental pollutants.