Influence of mitochondrion-toxic agents on the cardiovascular system

Arsenic induced cardiotoxicity: An approach for molecular markers, epigenetic predictors and targets

Arsenic, a ubiquitous environmental toxicant, has been acknowledged as a significant issue for public health due to its widespread pollution of drinking water and food supplies. The present review aimed to study the toxicity associated with the cardiac system. Prolonged exposure to arsenic has been associated with several harmful health outcomes, especially cardiotoxicity. Arsenic-induced cardiotoxicity encompasses a range of cardiovascular abnormalities, including cardiac arrhythmias, ischemic heart disease, and cardiomyopathy. To tackle this toxicity, understanding the molecular markers, epigenetic predictors, and targets involved in arsenic-induced cardiotoxicity is essential for creating preventative and therapeutic approaches. For preventive measures against this heavy metal poisoning of groundwater, it is crucial to regularly monitor water quality, re-evaluate scientific findings, and educate the public about the possible risks. This review thoroughly summarised what is currently known in this field, highlighting the key molecular markers, epigenetic modifications, and potential therapeutic targets associated with arsenic-induced cardiotoxicity.

Mitochondrial Dysfunction in Cardiotoxicity Induced by BCR-ABL1 Tyrosine Kinase Inhibitors -Underlying Mechanisms, Detection, Potential Therapies

The advent of BCR-ABL tyrosine kinase inhibitors (TKIs) targeted therapy revolutionized the treatment of chronic myeloid leukemia (CML) patients. Mitochondria are the key organelles for the maintenance of myocardial tissue homeostasis. However, cardiotoxicity associated with BCR-ABL1 TKIs can directly or indirectly cause mitochondrial damage and dysfunction, playing a pivotal role in cardiomyocytes homeostatic system and putting the cancer survivors at higher risk. In this review, we summarize the cardiotoxicity caused by BCR-ABL1 TKIs and the underlying mechanisms, which contribute dominantly to the damage of mitochondrial structure and dysfunction: endoplasmic reticulum (ER) stress, mitochondrial stress, damage of myocardial cell mitochondrial respiratory chain, increased production of mitochondrial reactive oxygen species (ROS), and other kinases and other potential mechanisms of cardiotoxicity induced by BCR-ABL1 TKIs. Furthermore, detection and management of BCR-ABL1 TKIs will promote our rational use, and cardioprotection strategies based on mitochondria will improve our understanding of the cardiotoxicity from a mitochondrial perspective. Ultimately, we hope shed light on clinical decision-making. By integrate and learn from both research and practice, we will endeavor to minimize the mitochondria-mediated cardiotoxicity and reduce the adverse sequelae associated with BCR-ABL1 TKIs.

Potential of natural products in combination with arsenic trioxide: Investigating cardioprotective effects and mechanisms

Over the past few decades, clinical trials conducted worldwide have demonstrated the efficacy of arsenic trioxide (ATO) in the treatment of relapsed acute promyelocytic leukemia (APL). Currently, ATO has become the frontline treatments for patients with APL. However, its therapeutic applicability is severely constrained by ATO-induced cardiac side effects. Any cardioprotective agents that can ameliorate the cardiac side effects and allow exploiting the full therapeutic potential of ATO, undoubtedly gain significant attention. The knowledge and use of natural products for evidence-based therapy have grown rapidly in recent years. Here we discussed the potential mechanism of ATO-induced cardiac side effects and reviewed the studies on cardiac side effects as well as the research history of ATO in the treatment of APL. Then, We summarized the protective effects and underlying mechanisms of natural products in the treatment of ATO-induced cardiac side effects. Based on the efficacy and safety of the natural product, it has a promising future in the development of cardioprotective agents against ATO-induced cardiac side effects.

Enhancing an Oxidative "Trojan Horse" Action of Vitamin C with Arsenic Trioxide for Effective Suppression of KRAS-Mutant Cancers: A Promising Path at the Bedside

The turn-on mutations of the KRAS gene, coding a small GTPase coupling growth factor signaling, are contributing to nearly 25% of all human cancers, leading to highly malignant tumors with poor outcomes. Targeting of oncogenic KRAS remains a most challenging task in oncology. Recently, the specific G12C mutant KRAS inhibitors have been developed but with a limited clinical outcome because they acquire drug resistance. Alternatively, exploiting a metabolic breach of KRAS-mutant cancer cells related to a glucose-dependent sensitivity to oxidative stress is becoming a promising indirect cancer targeting approach. Here, we discuss the use of a vitamin C (VC) acting in high dose as an oxidative "Trojan horse" agent for KRAS-mutant cancer cells that can be potentiated with another oxidizing drug arsenic trioxide (ATO) to obtain a potent and selective cytotoxic impact. Moreover, we outline the advantages of VC's non-natural enantiomer, D-VC, because of its distinctive pharmacokinetics and lower toxicity. Thus, the D-VC and ATO combination shows a promising path to treat KRAS-mutant cancers in clinical settings.

Emerging mitochondrial signaling mechanisms in cardio-oncology: beyond oxidative stress

Many anticancer therapies (CTx) have cardiotoxic side effects that limit their therapeutic potential and cause long-term cardiovascular complications in cancer survivors. This has given rise to the field of cardio-oncology, which recognizes the need for basic, translational, and clinical research focused on understanding the complex signaling events that drive CTx-induced cardiovascular toxicity. Several CTx agents cause mitochondrial damage in the form of mitochondrial DNA deletions, mutations, and suppression of respiratory function and ATP production. In this review, we provide a brief overview of the cardiovascular complications of clinically used CTx agents and discuss current knowledge of local and systemic secondary signaling events that arise in response to mitochondrial stress/damage. Mitochondrial oxidative stress has long been recognized as a contributor to CTx-induced cardiotoxicity; thus, we focus on emerging roles for mitochondria in epigenetic regulation, innate immunity, and signaling via noncoding RNAs and mitochondrial hormones. Because data exploring mitochondrial secondary signaling in the context of cardio-oncology are limited, we also draw upon clinical and preclinical studies, which have examined these pathways in other relevant pathologies.

Acute Cholecystitis in a Gastric Bypass Patient Complicated by Takotsubo Cardiomyopathy

Background. Gallbladder disease is a common condition after gastric bypass surgery. Even after weight loss, many bariatric patients continue to suffer from comorbid conditions. Takotsubo cardiomyopathy is a rare condition that mimics acute cardiac ischemia but seems to be caused by a catecholamine storm triggered by intense stress. Case Report. A 62-year-old female presented with acute right upper quadrant (RUQ) pain to the ER. She had a history of laparoscopic gastric bypass 5 years ago and had been noncompliant for 2 years. This noncompliance included missing follow-up appointments, gaining weight which caused poorly controlled DM, and not taking her vitamin supplements. Upon presentation, her WBC was elevated, her LFTs were normal, and imaging showed acute calculous cholecystitis. She was admitted and started on antibiotics with plans for laparoscopic cholecystectomy. The next day, she developed acute chest pain, and troponins were elevated with ST changes on EKG. Echocardiography showed a ballooned left ventricle indicative for Takotsubo cardiomyopathy. Symptomatic treatment including antibiotics, betablocker, and thiamine infusion was initiated. At three-month follow-up, ejection fraction had improved from <20% to >50%. The patient underwent interval laparoscopic cholecystectomy, which was technically very challenging due to severe ongoing acute and chronic cholecystitis. There were no cardiac issues, but the patient developed an abscess in the gallbladder fossa, which was successfully treated with oral antibiotics. Conclusions. Takotsubo cardiomyopathy complicating acute cholecystitis has thus far not been reported. Our patient had a history of gastric bypass and was noncompliant with vitamin supplementation. Thiamine deficiency may have contributed to the cardiac condition (wet beriberi).

Assessing Drug-Induced Mitochondrial Toxicity in Cardiomyocytes: Implications for Preclinical Cardiac Safety Evaluation

Drug-induced cardiotoxicity not only leads to the attrition of drugs during development, but also contributes to the high morbidity and mortality rates of cardiovascular diseases. Comprehensive testing for proarrhythmic risks of drugs has been applied in preclinical cardiac safety assessment for over 15 years. However, other mechanisms of cardiac toxicity have not received such attention. Of them, mitochondrial impairment is a common form of cardiotoxicity and is known to account for over half of cardiovascular adverse-event-related black box warnings imposed by the U.S. Food and Drug Administration. Although it has been studied in great depth, mitochondrial toxicity assessment has not yet been incorporated into routine safety tests for cardiotoxicity at the preclinical stage. This review discusses the main characteristics of mitochondria in cardiomyocytes, drug-induced mitochondrial toxicities, and high-throughput screening strategies for cardiomyocytes, as well as their proposed integration into preclinical safety pharmacology. We emphasize the advantages of using adult human primary cardiomyocytes for the evaluation of mitochondrial morphology and function, and the need for a novel cardiac safety testing platform integrating mitochondrial toxicity and proarrhythmic risk assessments in cardiac safety evaluation.

Honokiol attenuate the arsenic trioxide-induced cardiotoxicity by reducing the myocardial apoptosis

Despite advantages of arsenic trioxide (ATO) in oncological practice, its clinical applications have been hampered by severe cardiotoxicity. The general mechanism of ATO-induced cardiotoxicity has been attributed to its damage to mitochondria, resulting in cardiac remodeling. Honokiol (HKL) is a naturally occurring compound derived from Magnolia bark. Previous studies have demonstrated that HKL exerts cardio-protective effects on ischemia/reperfusion (I/R) or chemical-induced cardiotoxicity by counteracting the toxic effects on mitochondria. The present study was conducted to investigate whether HKL pretreatment protects against ATO-induced cardiac oxidative damage and cell death. For the in vitro study, we evaluated the effects of ATO and/or Honokiol on reactive oxygen species (ROS) production and apoptosis induction in primary cultured cardiomyocytes; for the in vivo study, BALB/c mice were administrated with ATO and/or HKL for a period of 4 weeks, myocardial apoptosis, cardiac function, and cardiac remodeling (cardiac hypertrophy and cardiac fibrosis) were assessed at the end of administration. Our results demonstrated Honokiol pretreatment alleviated the ATO-induced boost in ROS concentration and the following apoptosis induction in primary cultured cardiomyocytes. In the mouse model, Honokiol pretreatment ameliorated ATO-induced myocardial apoptosis, cardiac dysfunction, and cardiac remodeling. Collectively, these results indicated that Honokiol provide a protection against ATO-induced cardiotoxicity by reducing mitochondrial damage. In addition, given that Honokiol has shown considerable suppressive effects on leukemia cells, our data also imply that ATO and Honokiol combination may possibly be a superior avenue in leukemia therapy.

Relevance of mitochondrial oxidative stress to arrhythmias: Innovative concepts to target treatments

Cardiac arrhythmia occurs frequently worldwide, and in severe cases can be fatal. Mitochondria are the power plants of cardiomyocytes. In recent studies, mitochondria under certain stimuli produced excessive reactive oxygen species (ROS), which affect the normal function of cardiomyocytes through ion channels and related proteins. Mitochondrial oxidative stress (MOS) plays a key role in diseases with multifactorial etiopathogenesis, such as arrhythmia; MOS can lead to arrhythmias such as atrial fibrillation and ventricular tachycardia. This review discusses the mechanisms of arrhythmias caused by MOS, particularly of ROS produced by mitochondria. MOS can cause arrhythmias by affecting the activities of Ca²⁺-related proteins, the mitochondrial permeability transition pore protein, connexin 43, hyperpolarization-activated cyclic nucleotide-gated potassium channel 4, and ion channels. Based on these mechanisms, we discuss possible new treatments for arrhythmia. Targeted treatments focusing on mitochondria may reduce the progression of arrhythmias, as well as the occurrence of severe arrhythmias, and may be effective for personalized disease prevention.

Oxidative Stress in Takotsubo Syndrome-Is It Essential for an Acute Attack? Indirect Evidences Support Multisite Impact Including the Calcium Overload-Energy Failure Hypothesis

Indirect evidences in reviews and case reports on Takotsubo syndrome (TTS) support the fact that the existence of oxidative stress (OS) might be its common feature in the pre-acute stage. The sources of OS are exogenous (environmental factors including pharmacological and toxic influences) and endogenous, the combination of both may be present, and they are being discussed in detail. OS is associated with several pathological conditions representing TTS comorbidities and triggers. The dominant source of OS electrones are mitochondria. Our analysis of drug therapy related to acute TTS shows many interactions, e.g., cytostatics and glucocorticoids with mitochondrial cytochrome P450 and other enzymes important for OS. One of the most frequently discussed mechanisms in TTS is the effect of catecholamines on myocardium. Yet, their metabolic influence is neglected. OS is associated with the oxidation of catecholamines leading to the synthesis of their oxidized forms - aminochromes. Under pathological conditions, this pathway may dominate. There are evidences of interference between OS, catecholamine/aminochrome effects, their metabolism and antioxidant protection. The OS offensive may cause fast depletion of antioxidant protection including the homocystein-methionine system, whose activity decreases with age. The alteration of effector subcellular structures (mitochondria, sarco/endoplasmic reticulum) and subsequent changes in cellular energetics and calcium turnover may also occur and lead to the disruption of cellular function, including neurons and cardiomyocytes. On the organ level (nervous system and heart), neurocardiogenic stunning may occur. The effects of OS correspond to the effect of high doses of catecholamines in the experiment. Intensive OS might represent "conditio sine qua non" for this acute clinical condition. TTS might be significantly more complex pathology than currently perceived so far.

Liquiritigenin protects against arsenic trioxide-induced liver injury by inhibiting oxidative stress and enhancing mTOR-mediated autophagy

Liquiritigenin (LQ) has protective effects against various hepatotoxicities. However, its specific role on arsenic trioxide (ATO)-induced hepatotoxicity and the related biomolecular mechanisms remain unclear. The purpose of this study is to explore the protective actions of LQ on ATO-induced hepatotoxicity and its biomolecular mechanisms in mice. LQ was administered orally at 20 and 40 mg/kg per day for seven consecutive days with an intraperitoneal injection of ATO (5 mg/kg). Liver injury was induced by ATO and was alleviated by treatment with LQ as reflected by reduced histopathological damage of liver and decreased serum ALT, AST, and ALP levels. The generation of intracellular ROS induced by ATO was attenuated after LQ treatment. The levels of SOD, CAT, and GSH were elevated with LQ administration while MDA levels decreased. LQ mitigated elevated TNF-α and IL-6 levels as well as the hepatic mitochondrial damage caused by ATO. Moreover, LQ upregulated the expression of LC3-II and enhanced autophagy in the liver of ATO-induced mice. Further studies indicated that LQ significantly suppressed the expression of p-PI3K, p-AKT, and p-mTOR in ATO-induced mice. In conclusion, our findings show that LQ protects against ATO-induced hepatotoxicity due to its antioxidant and anti-inflammatory activities and enhancement of autophagy mediated by the PI3K/AKT/mTOR signaling pathway in mice.

Canagliflozin is a potential cardioprotective drug but exerts no significant effects on pirarubicin‑induced cardiotoxicity in rats

Pirarubicin (THP), one of the anthracycline anticancer drugs, is widely used in the treatment of various types of cancer, but its cardiotoxicity cannot be ignored. Canagliflozin, the first sodium‑glucose co‑transporter‑2 inhibitor approved by the USA FDA, has been shown to have a significant effect on cardiovascular damage caused by diabetes. However, it has not been reported whether it can resist THP‑induced cardiotoxicity. The aim of the present study was to investigate the effect of canagliflozin on THP‑induced cardiotoxicity and its mechanism. A rat model of cardiotoxicity induced by THP was established and canagliflozin treatment was performed at the same time. The changes of electrocardiography, cardiac coefficient and echocardiogram were observed. The levels of lactate dehydrogenase, brain natriuretic peptide, creatine kinase MB, cardiac troponin T, superoxide dismutase (SOD) and malondialdehyde were detected. The expression of SOD2, NADPH oxidase 2, pro/cleaved‑caspase‑ and Bcl‑2/Bax were evaluated by western blotting. The primary culture of cardiomyocytes was prepared to explore the effect in vitro. After eight weeks, a series of cardiotoxicity manifestations were observed in THP rats. However, canagliflozin treatment had no significant effect on the above adverse reactions. Similarly, further studies showed that canagliflozin had no significant effect on THP‑induced cardiomyocyte injury in vitro. The present study showed that there was no significant protective effect of canagliflozin on THP‑induced cardiotoxicity and cardiomyocyte injury.

Antioxidant effect of acetyl-l-carnitine against cisplatin-induced cardiotoxicity

Objective

Cisplatin (CDDP) toxicity is a dose-limiting clinical problem in clinical practice, mainly because of nephrotoxicity or ototoxicity. However, the mechanism of CDDP-induced cardiotoxicity is poorly understood. Acetyl-l-carnitine (ALCAR) is an antioxidant agent with protective effects against the side effects of various chemotherapeutics. CDDP-induced cardiotoxicity and the protective role of ALCAR were evaluated in this study.

Methods

Morphological changes were evaluated in hematoxylin and eosin-stained sections, and immunohistochemistry for caspase-3, superoxide dismutase-2 (SOD-2), inducible nitrite oxide synthase (iNOS), cyclooxygenase-2, and Bcl-2 was performed using the hearts of athymic nude mice carrying xenograft neuroblastoma tumors. Mice were randomized (six/group) to the control, CDDP (16 mg/kg), and ALCAR (200 mg/kg)+CDDP (16 mg/kg) groups. Results were analyzed using nonparametric tests.

Results

No difference was observed in the rates of cardiac necrosis, dilated/congested blood vessels, hemorrhage, polymorphonuclear leukocyte infiltration, edema, and pyknotic nuclei among the groups. SOD-2 expression was increased in the CDDP group but not in the ALCAR+CDDP group. iNOS, Bcl-2, and caspase-3 levels were not significantly different among the groups.

Conclusions

ALCAR might be a candidate protective agent for CDDP-induced cardiotoxicity. SOD-2, as a member of the oxidant system, should be evaluated in further studies as a biomarker of cardiotoxicity.

Arsenal of Phytochemicals to Combat Against Arsenic-Induced Mitochondrial Stress and Cancer

Significance: Phytochemicals are important dietary constituents with antioxidant properties. They affect various signaling pathways involved in the overall maintenance of interior milieu of the cell. Arsenic, an environmental toxicant, is well known for its deleterious consequences, such as various diseases, including cancers in humans. Mitochondria are the cell's powerhouse that fuel all metabolic energy requirements. Dysfunctional mitochondria due to stressors may lead to abnormal functioning of the organelle, hampering the crucial cellular cross talks and ultimately leading to cancer. Application of phytochemicals against arsenic-induced mitochondrial disorders may be a preventive measure to counteract the ruinous impacts of the metalloid. Recent Advances: In recent years, extensive research on the role of mitochondria in cancer gives a better understanding of the areas the organelle covers in maintaining a healthy cell or in inducing carcinogenicity. Detailed knowledge of the mitochondrial governances would enable researchers to administer numerous phytochemicals to ameliorate altered oxidative phosphorylation, mitochondrial membrane potential (MMP), mitochondrial oxidative stress, unfolded protein response, glycolysis, or even apoptosis. Critical Issues: In this review, we have addressed how various phytochemicals belonging to diverse classes combat against arsenic-induced mitochondrial oxidative stress, depletion of MMP, cell cycle abrogation, apoptosis, glycolytic damages, oncogenic regulations, chaperones, mitochondrial complexes, and mitochondrial membrane pore formation in both in vitro and in vivo models. Future Directions: Insightful application of mitoprotective phytochemicals against arsenic-induced mitochondrial oxidative stress and carcinogenesis may guide researchers to develop preclinical chemopreventive agents to fight arsenic toxicity in humans.

Arbutin prevents alterations in mitochondrial and lysosomal enzymes in isoproterenol-induced myocardial infarction: An in vivo study

The present study demonstrated the protective effects of arbutin (ARB) on hyperlipidemia, mitochondrial, and lysosomal membrane damage and on the DNA damage in rats with isoproterenol (ISO)-induced myocardial infarction (MI). Rats were pretreated with ARB (25 and 50 mg/kg body weight (bw)) for 21 days. After pretreatment with ARB, MI was induced by subcutaneous injection of ISO (60 mg/kg bw) for two consecutive days at an interval of 24 h. The levels of TC, TG, and FFA were increased and decreased the level of PL in the heart tissue of ISO-induced MI rats. Very-low-density lipoprotein cholesterol and low-density lipoprotein cholesterol were increased while high-density lipoprotein cholesterol was decreased in the plasma of ISO-administered rats. A heart mitochondrial fraction of the ISO rats showed a significant decrease in the activities of mitochondrial enzymes isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, succinate dehydrogenase, and malate dehydrogenase. The activities of lysosomal enzymes (β-glucosidase, β-glucuronidase, α-galactosidase, β-galactosidase, cathepsin-B, and cathepsin-D) were increased significantly in the heart tissue homogenate of disease control rats. In ISO-induced MI, rat’s significant increase in the percentage of tail DNA and tail length, and a decrease in the level of head DNA were also observed. ARB administration to MI rats brought all these parameters to near normality, showing the protective effect of ARB against MI in rats. The results of this study demonstrated that the 50 mg/kg bw of ARB shows higher protection than 25 mg/kg bw against ISO-induced damage.

Zinc protects against cadmium-induced toxicity in neonatal murine engineered cardiac tissues via metallothionein-dependent and independent mechanisms

Cadmium (Cd) is a nonessential heavy metal and a prevalent environmental toxin that has been shown to induce significant cardiomyocyte apoptosis in neonatal murine engineered cardiac tissues (ECTs). In contrast, zinc (Zn) is a potent metallothionein (MT) inducer, which plays an important role in protection against Cd toxicity. In this study, we investigated the protective effects of Zn against Cd toxicity in ECTs and explore the underlying mechanisms. ECTs were constructed from neonatal ventricular cells of wild-type (WT) mice and mice with global MT gene deletion (MT-KO). In WT-ECTs, Cd (5-20 μM) caused a dose-dependent toxicity that was detected within 8 h evidenced by suppressed beating, apoptosis, and LDH release; Zn (50-200 μM) dose-dependently induced MT expression in ECTs without causing ECT toxicity; co-treatment of ECT with Zn (50 µM) prevented Cd-induced toxicity. In MT-KO ECTs, Cd toxicity was enhanced; but unexpectedly, cotreatment with Zn provided partial protection against Cd toxicity. Furthermore, Cd, but not Zn, significantly activated Nrf2 and its downstream targets, including HO-1; inhibition of HO-1 by a specific HO-1 inhibitor, ZnPP (10 µM), significantly increased Cd-induced toxicity, but did not inhibit Zn protection against Cd injury, suggesting that Nrf2-mediated HO-1 activation was not required for Zn protective effect. Finally, the ability of Zn to reduce Cd uptake provided an additional MT-independent mechanism for reducing Cd toxicity. Thus, Zn exerts protective effects against Cd toxicity for murine ECTs that are partially MT-mediated. Further studies are required to translate these findings towards clinical trials.

Improvement of mitochondrial function by Tapinanthus globifer (A.Rich.) Tiegh. Against hepatotoxic agent in isolated rat's liver mitochondria

ETHNOPHARMACOLOGICAL RELEVANCE

Disturbed mitochondrial function and energy crisis serve as key mechanisms for the development of liver injury. Hence, targeting cellular mitochondria in liver diseases might serve as a therapeutic option. Tapinanthus globifer (A.Rich.) Tiegh. has been used in traditional medicine in the management of liver disease. However, there is no scientific evidence supporting such use.

AIM OF THE STUDY

The current investigation was designed to evaluate the protective role of Tapinanthus globifer treatment on the liver mitochondrial function after the induction of hepatotoxicity by the hepatotoxic agent Fe²⁺in vitro.

MATERIALS AND METHODS

In this study, isolated mitochondria from rats' liver was incubated with Fe²⁺ (10 μM) for 1 h in the absence or presence of T. globifer (50, 100 and 200 μg/mL) metanolic extract (MVA). Mitochondrial viability, mitochondrial membrane potential (ΔΨm), mitochondrial swelling (MPTP)., total thiol content, lipid peroxidation (TBARS) and reactive oxygen species (ROS) production were measured. HPLC-DAD was used to identify potential phytochemicals in MVA.

RESULTS

(MVA) was able to improve mitochondrial dysfunction induced by Fe²⁺, by attenuating MTT reduction, increased ΔΨm and mitochondrial swelling. Reduced total thiol and non-protein thiol contents which were associated with increased lipid peroxidation and ROS generation in Fe²⁺-treated mitochondria were significantly improved by MVA co-treatment. HPLC-DAD analysis revealed the presence of gallic acid, catechin, epigallocatechin, caffeic acid, rutin, glycoside flavonoid and quercetin in MVA that can be responsible for its beneficial effect.

CONCLUSION

MVA phyto-compounds enhance mitochondrial redox signaling and possess mitochondrial function improving potential, thereby, providing scientific basis for its use in traditional medicine.

Gallic acid ameliorates sodium arsenite-induced renal and hepatic toxicity in rats

Chronic exposure to toxic inorganic arsenic results in the adverse health effects including skin lesions, cardiovascular diseases, diabetes, neurological disorders, and liver and kidney diseases. Gallic acid (GA) is an important phenolic compound, which could protect different tissues from oxidative stress induced damage. The present study investigated effects of GA against sodium arsenite (SA)-induced renal and hepatic toxicity. Thirty-five rats were randomly divided in to five groups; group 1 was treated with normal saline (2 ml/kg/day, p.o.; for 21 days); group 2 was exposed to SA (10 mg/kg/day, p.o.; for 14 days); groups 3 and 4 were treated with GA (10 and 30 mg/kg/day, respectively; for 7 days) prior to exposure to SA, and treatment was continued up to 21 days in parallel with SA administration; group 5 was treated with GA (30 mg/kg/day, p.o.; for 21 days). The level of MDA, IL-1β, NO and glutathione (GSH) and the activity of glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase (CAT) were evaluated in kidney and liver tissues. Histopathological parameters and serum levels of ALT, AST, ALP, Cr and BUN were also assessed. Treatment with GA remarkably improved SA-induced alteration of hematological and histopathological parameters; these protective effects were associated with the reduction of SA-induced elevation of MDA, IL-1β and NO levels as well as reduction of GSH level and GPx, SOD and CAT activity. Our results suggest that GA may inhibit SA-induced kidney and liver toxicity through scavenging reactive free radicals and increasing intracellular antioxidant capacity.

Re-examining the relationship between alcohol consumption and coronary heart disease with a new lens

Moderate alcohol consumption has been related to lower risk of coronary heart disease (CHD) in the literature. To examine whether alcohol drinking during the past 12 months and heaviest drinking period were differentially associated with the risk of CHD, we designed a case-control study using a population-based health survey of U.S. adults conducted from 2012 to 2013. Respondents who reported to have doctor-ascertained CHD served as cases (n = 1671), and those free of CHD and other alcohol-related health conditions served as controls (n = 17,629) in logistic regressions. Sex-specific quartiles of average daily ethanol intake were ascertained and calculated for the past 12 months and during the period of heaviest lifetime drinking. We further split current drinkers into reducers and non-reducers (past 12 months relative to the heaviest drinking period) to examine CHD risk profiles in association with the 12-month drinking level. Current-drinker reducers (AOR, 95% CI = 1.57 [1.10-2.27] for men; AOR, 95% CI = 1.33 [1.02-1.72] for women) and former drinkers (AOR, 95% CI = 2.06 [1.43-2.97] for men; AOR, 95% CI = 1.51 [1.19-1.92] for women) more often had CHD than lifetime abstainers. Male heavy drinkers during the heaviest drinking period (AOR, 95% CI = 2.25 [1.52-3.32]) were more likely to manifest CHD than lifetime abstainers. In addition, individuals with diagnosed CHD were significantly more likely to have reduced drinking in the past. A change in alcohol consumption over the life course among former and current drinkers may distort the true alcohol-CHD relationship.

Ameliorative effect of gallic acid on sodium arsenite-induced spleno-, cardio- and hemato-toxicity in rats

AIM

Arsenic is an important toxic chemical affecting millions of people around the world. Exposure to inorganic arsenic results in various health problems including skin lesions, hypertension, hematological disturbance, cardiovascular disease, spleen enlargement and cancer. Gallic acid (GA) is an important phenolic compound possessing various pharmacological properties including anti-inflammatory, antioxidant and free radical scavenging activities. The present study investigated effects of GA against sodium arsenite (SA)-induced spleno-, cardio- and hemato-toxicity.

MAIN METHODS

Thirty-five adult male Wistar rats were randomly divided into five groups; group I received normal saline (2 ml/kg/day, p.o.) for 21 days, group II received SA (10 mg/kg/day, p.o.) for 14 days, group III and IV were treated with GA (10 and 30 mg/kg/day, respectively) for 7 days prior to receive SA and treatment was continued up to 21 days in parallel with SA administration, group V received GA (30 mg/kg/day, p.o.) for 21 days. The level of MDA, NO and glutathione (GSH) and the activity of glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase were measured in heart and spleen tissues. Creatine kinase-MB (CK-MB) activity and hematological and histopathological parameters were also assessed.

KEY FINDINGS

GA significantly decreased SA-induced elevation of MDA and NO levels and reduction of GSH level and GPx and SOD activity in heart and spleen tissues. Furthermore, GA improved SA-induced alteration in hematological and histopathological parameters and reduced SA-induced elevation of serum CK-MB activity.

SIGNIFICANCE

Our results suggest that GA inhibits SA-induced spleno-, cardio- and hemato-toxicity through reducing oxidative stress.

In vitro screening of cell bioenergetics to assess mitochondrial dysfunction in drug development

Drug-induced mitochondrial toxicity is considered as a common cellular mechanism that can induce a variety of organ toxicities. In the present manuscript, 17 in vitro mitochondrial toxic drugs, reported to induce Drug-Induced Liver Injury (DILI) and 6 non-mitochondrial toxic drugs (3 with DILI and 3 without DILI concern), were tested in HepG2 cells using a bioenergetics system. The 17 mitochondrial toxic drugs represent a wide variety of mitochondrial dysfunctions as well as DILI and include 4 pairs of drugs which are structurally related but associated with different DILI concerns in human. Cell bioenergetics were measured using the XF96e analyzer which simultaneous monitor oxygen consumption rate (OCR) and extracellular acidification rate (ECAR), indirect measurements of oxidative phosphorylation and glycolysis, respectively. OCR associated with ATP production, maximal respiration, proton leak and spare respiratory capacity, were also assessed. Duplicate experiments resulted in a sensitivity of 82% (14/17) and specificity of 83% (5/6). The addition of stressors improved specificity considerably. Cut-offs, statistics and rules are clearly discussed to facilitate the use of this assay for screening purposes. Overall, the authors consider that this assay should be part of the battery of safety screening assays at early stages of drug development.

Cocaine Exposure Increases Blood Pressure and Aortic Stiffness via the miR-30c-5p-Malic Enzyme 1-Reactive Oxygen Species Pathway

Cocaine abuse increases the risk of cardiovascular mortality and morbidity; however, the underlying molecular mechanisms remain elusive. By using a mouse model for cocaine abuse/use, we found that repeated cocaine injection led to increased blood pressure and aortic stiffness in mice associated with elevated levels of reactive oxygen species (ROS) in the aortas, a phenomenon similar to that observed in hypertensive humans. This ROS elevation was correlated with downregulation of Me1 (malic enzyme 1), an important redox molecule that counteracts ROS generation, and upregulation of microRNA (miR)-30c-5p that targets Me1 expression by directly binding to its 3'UTR (untranslated region). Remarkably, lentivirus-mediated overexpression of miR-30c-5p in aortic smooth muscle cells recapitulated the effect of cocaine on Me1 suppression, which in turn led to ROS elevation. Moreover, in vivo silencing of miR-30c-5p in smooth muscle cells resulted in Me1 upregulation, ROS reduction, and significantly suppressed cocaine-induced increases in blood pressure and aortic stiffness-a similar effect to that produced by treatment with the antioxidant N-acetyl cysteine. Discovery of this novel cocaine-↑miR-30c-5p-↓Me1-↑ROS pathway provides a potential new therapeutic avenue for treatment of cocaine abuse-related cardiovascular disease.

Riboflavin attenuates myocardial injury via LSD1-mediated crosstalk between phospholipid metabolism and histone methylation in mice with experimental myocardial infarction

The underlying mechanisms responsible for the cardioprotective effects of riboflavin remain elusive. Current study tested the hypothesis that riboflavin protects injured myocardium via epigenetic modification of LSD1. Here we showed that myocardial injury was attenuated and cardiac function was improved in riboflavin-treated mice with experimental myocardial infarction (MI), while these protective effects of riboflavin could be partly blocked by cotreatment with LSD1 inhibitor. Riboflavin also reduced apoptosis in hypoxic (1% oxygen) H9C2 cell lines. Results of ChIP-seq for H9C2 cells showed that riboflavin activated LSD1, as verified by decreased H3K4me2 levels of target genes. Subsequent LEGO bioinformatics analysis indicated that phospholipid metabolism genes Lpcat2 and Pld1 served as the potential target genes responsible for the LSD1 mediated protective effects. Overexpressions of Lpcat2 and Pld1 aggravated hypoxic injury in H9C2 cells, while these detrimental effects could be attenuated by overexpression of LSD1. We thus propose that riboflavin alleviates myocardial hypoxic/ischemic injury by activating LSD1 cellular activity and modulating the expression of phospholipid metabolism genes. LSD1-mediated crosstalk between phospholipid metabolism and histone methylation might thus be an important mechanism for the cardioprotective effects of riboflavin.

Mitochondria and Sex-Specific Cardiac Function

The focus of this chapter is the gender differences in mitochondria in cardiovascular disease. There is broad evidence suggesting that some of the gender differences in cardiovascular outcome may be partially related to differences in mitochondrial biology (Ventura-Clapier R, Moulin M, Piquereau J, Lemaire C, Mericskay M, Veksler V, Garnier A, Clin Sci (Lond) 131(9):803-822, 2017)). Mitochondrial disorders are causally affected by mutations in either nuclear or mitochondrial genes involved in the synthesis of respiratory chain subunits or in their posttranslational control. This can be due to mutations of the mtDNA which are transmitted by the mother or mutations in the nuclear DNA. Because natural selection on mitochondria operates only in females, mutations may have had more deleterious effects in males than in females (Ventura-Clapier R, Moulin M, Piquereau J, Lemaire C, Mericskay M, Veksler V, Garnier A, Clin Sci (Lond) 131(9):803-822, 2017; Camara AK, Lesnefsky EJ, Stowe DF. Antioxid Redox Signal 13(3):279-347, 2010). As mitochondrial mutations can affect all tissues, they are responsible for a large panel of pathologies including neuromuscular disorders, encephalopathies, metabolic disorders, cardiomyopathies, neuropathies, renal dysfunction, etc. Many of these pathologies present sex/gender specificity. Thus, alleviating or preventing mitochondrial dysfunction will contribute to mitigating the severity or progression of the development of diseases. Here, we present evidence for the involvement of mitochondria in the sex specificity of cardiovascular disorders.

Antioxidants Protect against Arsenic Induced Mitochondrial Cardio-Toxicity

Arsenic is a potent cardiovascular toxicant associated with numerous biomarkers of cardiovascular diseases in exposed human populations. Arsenic is also a carcinogen, yet arsenic trioxide is used as a therapeutic agent in the treatment of acute promyelotic leukemia (APL). The therapeutic use of arsenic is limited due to its severe cardiovascular side effects. Many of the toxic effects of arsenic are mediated by mitochondrial dysfunction and related to arsenic's effect on oxidative stress. Therefore, we investigated the effectiveness of antioxidants against arsenic induced cardiovascular dysfunction. A growing body of evidence suggests that antioxidant phytonutrients may ameliorate the toxic effects of arsenic on mitochondria by scavenging free radicals. This review identifies 21 antioxidants that can effectively reverse mitochondrial dysfunction and oxidative stress in cardiovascular cells and tissues. In addition, we propose that antioxidants have the potential to improve the cardiovascular health of millions of people chronically exposed to elevated arsenic concentrations through contaminated water supplies or used to treat certain types of leukemias. Importantly, we identify conceptual gaps in research and development of new mito-protective antioxidants and suggest avenues for future research to improve bioavailability of antioxidants and distribution to target tissues in order reduce arsenic-induced cardiovascular toxicity in a real-world context.

Biochemical and histopathological changes of subacute cadmium intoxication in male rats

Biochemical and histopathological effects of subacute intoxication of rats with cadmium (Cd) were studied in rats. Twenty adult healthy male albino rats were randomly divided into two duplicate groups (five rats in each cage); (1) control group where rats were provided with standard diet and water ad-libitum, (2) Cd group where rats were subjected to freshly prepared Cd chloride solution (CdCl2) 200 mg/l in drinking water daily for 8 weeks, the whole duration of experiment. Blood samples were obtained after 4 weeks, via retro-orbital bleeding for separation of serum. Five rats were killed, each sacrifice by decapitation for collection of kidneys and heart. Disturbed renal and cardiac functions were achieved after 4 weeks as indicated by the increase of most biochemical parameters measured in the serum, renal, and cardiac tissues. Histopathological examination of kidneys and hearts showed pathological alterations in Cd-intoxicated rats after 4 and 8 weeks with hematoxylin and eosin (H&E) and Masson trichrome stains. It was concluded that subacute exposure of rats to Cd (200 mg/l) in drinking water daily induced glomerular shrinkage, focal renal, and cardiac fibrosis at 4 and 8 weeks.

Myocardial oxidative damage is induced by cardiac Fas-dependent and mitochondria-dependent apoptotic pathways in human cocaine-related overdose

The aim of this study is to analyse cardiac specimens from human cocaine-related overdose, to verify the hypothesis that cardiac toxicity by acute exposure to high dosage of cocaine could be mediated by unbalanced myocardial oxidative stress, and to evaluate the apoptotic response. To address these issues, biochemical and immunohistological markers of oxidative/nitrosative stress were evaluated. We found that i-NOS, NOX2 and nitrotyrosine expression were significantly higher in the hearts of subjects who had died from high doses of cocaine, compared to the control group. Increase of these markers was associated with a dramatic increase in 8-OHdG, another marker of oxidative stress. A high number of TUNEL-positive apoptotic myocells was observed in the study group compared to the control group. The immunoexpression of TNF-α was significantly higher in the cocaine group compared to the control group. Furthermore, we detected a significantly stronger immunoresponse to anti-SMAC/DIABLO in our study group compared to control cases. Both cardiac Fas-dependent and mitochondria-dependent apoptotic pathways appeared to be activated to a greater extent in the cocaine group than in the control group. Our results highlight the central role of oxidative stress in cocaine toxicity. High levels of NOS can promote the oxidation process and lead to apoptosis.

Pinocembrin Attenuates Mitochondrial Dysfunction in Human Neuroblastoma SH-SY5Y Cells Exposed to Methylglyoxal: Role for the Erk1/2-Nrf2 Signaling Pathway

Pinocembrin (PB; 5,7-dihydroxyflavanone) is found in propolis and exhibits antioxidant activity in several experimental models. The antioxidant capacity of PB is associated with the activation of the nuclear factor erythroid 2-related factor 2/antioxidant response element (Nrf2/ARE) signaling pathway. The Nrf2/ARE axis mediates the expression of antioxidant and detoxifying enzymes, such as glutathione peroxidase (GPx), glutathione reductase (GR), heme oxygenase-1 (HO-1), and the catalytic (GCLC) and regulatory (GCLM) subunits of the rate-limiting enzyme in the synthesis of glutathione (GSH), γ-glutamate-cysteine ligase (γ-GCL). Nonetheless, it is not clear how PB exerts mitochondrial protection in mammalian cells. Human neuroblastoma SH-SY5Y cells were pretreated (4 h) with PB (0-25 µM) and then exposed to methylglyoxal (MG; 500 µM) for further 24 h. Mitochondria were isolated by differential centrifugation. PB (25 µM) provided mitochondrial protection (decreased lipid peroxidation, protein carbonylation, and protein nitration in mitochondrial membranes; decreased mitochondrial free radical production; enhanced the content of GSH in mitochondria; rescued mitochondrial membrane potential-MMP) and blocked MG-triggered cell death by a mechanism dependent on the activation of the extracellular-related kinase (Erk1/2) and consequent upregulation of Nrf2. PB increased the levels of GPx, GR, HO-1, and mitochondrial GSH. The PB-induced effects were suppressed by silencing of Nrf2 with siRNA. Therefore, PB activated the Erk1/2-Nrf2 signaling pathway resulting in mitochondrial protection in SH-SY5Y cells exposed to MG. Our work shows that PB is a strong candidate to figure among mitochondria-focusing agents with pharmacological potential.

Chlorogenic acid ameliorates isoproterenol-induced myocardial injury in rats by stabilizing mitochondrial and lysosomal enzymes

This study was deliberated to aspire the effects of chlorogenic acid (CGA) against myocardial infarction (MI) induced by Isoproterenol (ISO), in a rat model. In the pathology of MI, enzymes released due to the mitochondrial and lysosomal lipid peroxidation play an integral role. Induction of rats with ISO (85mg/kg BW) for 2 consecutive days resulted in a significant decrease in the activities of heart mitochondrial enzymes isocitrate dehydrogenase (ICDH), α-ketoglutarate dehydrogenase (α-KGDH), succinate dehydrogenase (SDH) and malate dehydrogenase (MDH). The activities of lysosomal enzymes (β- glucosidase, β-glucuronidase, α-galactosidase, β-galactosidase, cathepsin-B and cathepsin-D) were increased significantly in the heart tissue. A prominent expression of LDH 1 and LDH 2 isoenzymes in the serum were observed and changes in the Electrocardiographic (ECG) patterns were also recorded in the ISO-induced rats. The prior administrations of CGA (40mg/kg BW) for 19days markedly ameliorated ISO induced alterations in ECG and significantly restored the activities of all the above enzymes in the heart of ISO-induced rats, which substantiates the stress stabilizing action of CGA. Oral administration of CGA (40mg/kg BW) to normal rats did not show any significant changes. These biochemical functional alterations were supported by the histology of heart (Massion's trichrome and Picrosirius red staining for collagen formation). Thereupon, this study shows that 40mg/kg BW of CGA gives protection against ISO-induced MI and demonstrates that CGA has a significant effect in the protection of heart.

Ellagic acid protects against arsenic toxicity in isolated rat mitochondria possibly through the maintaining of complex II

Chronic arsenic exposure has been linked to many health problems including diabetes and cancer. In the present study, we assessed the protective effect of ellagic acid (EA) against toxicity induced by arsenic in isolated rat liver mitochondria. Reactive oxygen species (ROS) and mitochondrial membrane potential decline were assayed using dichlorofluorescein diacetate and rhodamine 123, respectively, and dehydrogenase activity obtained by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide conversion assay. Arsenic increased ROS levels and mitochondrial dysfunction, which led to a reduction in mitochondrial total dehydrogenase activity. Mitochondria pretreated with EA exposed to arsenic at various concentrations led to a reversal of ROS production and mitochondrial damage. Our results showed that mitochondria were significantly affected when exposed to arsenic, which resulted in excessive ROS production and mitochondrial membrane disruption. Pretreatment with EA, reduced ROS amounts, mitochondrial damage, and restored total dehydrogenase activity specifically associated with mitochondrial complex II. EA protective characteristics may be accomplished particularly throughout the mitochondrial maintenance either directly by its antioxidant property or indirectly through its maintaining of complex II. These findings also suggest a potential role for EA in treating or preventing mitochondria associated disorders.

Cardioprotective and Antioxidant Influence of Aqueous Extracts from Sesamum indicum Seeds on Oxidative Stress Induced by Cadmium in Wistar Rats

Background:

Oxidative stress has been implicated in the pathogenesis of several acute and chronic diseases of the heart as a result of indiscriminate exposure to cardiotoxic heavy metals. The study reported here was designed to evaluate the possible ameliorative effect of aqueous extracts from Sesamum indicum (SI) seeds on oxidative stress induced by cadmium (Cd) in Wistar rats.

Materials and Methods:

Daily administration of Cd (200 mg/L Cd as CdCl₂) in the animals’ main drinking water for 21 days led to oxidative stress. Thereafter, the ameliorative effects were assessed by measuring biochemical parameters such as extent of lipid peroxidation (LPO), lipid profile, and enzymatic and nonenzymatic antioxidants, as well as serum aminotransferase activities.

Results:

Treatment with SI extract elicited notable reduction in serum total cholesterol, triglyceride, and low-density lipoprotein cholesterol levels as well as concomitant increase in high-density lipoprotein cholesterol. SI extract also reversed the elevations witnessed in serum aminotransferase activities, LPO level, and ameliorated enzymatic and nonenzymatic antioxidant status in the heart of Cd-exposed rats.

Conclusion:

Thus, SI appears to be an attractive candidate with potential for the novel treatment of cardiotoxicity and management of oxidative stress arising from Cd exposure.

SUMMARY

Cadmium (200 mg/L) exposure in drinking water caused pronounced oxidative stress and cardiac tissue damage in animal model

Aqueous extract of Sesamum indicum (SI) seeds at a dose of 200 or 400 mg/kg body weight exhibited a significant reversal effect in all biochemical parameters measured such as extent of lipid peroxidation, lipid profile, and enzymatic and nonenzymatic antioxidants, as well as serum aminotransferase activities

Aqueous extract of SI seeds possess antioxidant and cardioprotective potential in a dose-dependent manner, thus conferring protection against oxidative stress induced by cadmium.

Abbreviation used: SI: Sesamum indicum, Cd: Cadmium, CdCl2: Cadmium chloride, LPO: Lipid peroxidation, TBA: Thiobarbituric acid, ALT: Alanine aminotransferase, AST: Aspartate aminotransferase, ALP: Alkaline phosphatise, TC: Total cholesterol, TG: Triglyceride, HDL-C: Highdensity lipoprotein cholesterol, LDL-C: Low-density lipoprotein cholesterol, SD: Standard deviation, GSH: Glutathione, SOD: Superoxide dismutase, CAT: Catalase, GST: Glutathione-S-transferase, GPx: Glutathione peroxidise.

Mechanisms Influencing Circadian Blood Pressure Patterns Among Individuals with HIV

HIV+ individuals have an increased risk for cardiovascular disease (CVD), but the mechanisms behind this association are poorly understood. While hypertension is a well-established CVD risk factor, clinic-based blood pressure (BP) assessment by itself cannot identify several important BP patterns, including white coat hypertension, masked hypertension, nighttime hypertension, and nighttime BP dipping. These BP patterns can be identified over a 24-h period by ambulatory BP monitoring (ABPM). In this review, we provide an overview of the potential value of conducting ABPM in HIV+ individuals. ABPM phenotypes associated with increased CVD risk include masked hypertension (i.e., elevated out-of-clinic BP despite non-elevated clinic BP), nighttime hypertension, and a non-dipping BP pattern (i.e., a drop in BP of <10 % from daytime to nighttime). These adverse ABPM phenotypes may be highly relevant in the setting of HIV infection, given that increased levels of inflammatory biomarkers, high psychosocial burden, high prevalence of sleep disturbance, and autonomic dysfunction have been commonly reported in HIV+ persons. Additionally, although antiretroviral therapy (ART) is associated with lower AIDS-related morbidity and CVD risk, the mitochondrial toxicity, oxidative stress, lipodystrophy, and insulin resistance associated with long-term ART use potentially lead to adverse ABPM phenotypes. Existing data on ABPM phenotypes in the setting of HIV are limited, but suggest an increased prevalence of a non-dipping BP pattern. In conclusion, identifying ABPM phenotypes may provide crucial information regarding the mechanisms underlying the excess CVD risk in HIV+ individuals.

Mitochondrial Quality Control as a Therapeutic Target

In addition to oxidative phosphorylation (OXPHOS), mitochondria perform other functions such as heme biosynthesis and oxygen sensing and mediate calcium homeostasis, cell growth, and cell death. They participate in cell communication and regulation of inflammation and are important considerations in aging, drug toxicity, and pathogenesis. The cell's capacity to maintain its mitochondria involves intramitochondrial processes, such as heme and protein turnover, and those involving entire organelles, such as fusion, fission, selective mitochondrial macroautophagy (mitophagy), and mitochondrial biogenesis. The integration of these processes exemplifies mitochondrial quality control (QC), which is also important in cellular disorders ranging from primary mitochondrial genetic diseases to those that involve mitochondria secondarily, such as neurodegenerative, cardiovascular, inflammatory, and metabolic syndromes. Consequently, mitochondrial biology represents a potentially useful, but relatively unexploited area of therapeutic innovation. In patients with genetic OXPHOS disorders, the largest group of inborn errors of metabolism, effective therapies, apart from symptomatic and nutritional measures, are largely lacking. Moreover, the genetic and biochemical heterogeneity of these states is remarkably similar to those of certain acquired diseases characterized by metabolic and oxidative stress and displaying wide variability. This biologic variability reflects cell-specific and repair processes that complicate rational pharmacological approaches to both primary and secondary mitochondrial disorders. However, emerging concepts of mitochondrial turnover and dynamics along with new mitochondrial disease models are providing opportunities to develop and evaluate mitochondrial QC-based therapies. The goals of such therapies extend beyond amelioration of energy insufficiency and tissue loss and entail cell repair, cell replacement, and the prevention of fibrosis. This review summarizes current concepts of mitochondria as disease elements and outlines novel strategies to address mitochondrial dysfunction through the stimulation of mitochondrial biogenesis and quality control.

Arsenic-Induced Antioxidant Depletion, Oxidative DNA Breakage, and Tissue Damages are Prevented by the Combined Action of Folate and Vitamin B12

Arsenic is a grade I human carcinogen. It acts by disrupting one-carbon (1C) metabolism and cellular methyl (-CH3) pool. The -CH3 group helps in arsenic disposition and detoxification of the biological systems. Vitamin B12 and folate, the key promoters of 1C metabolism were tested recently (daily 0.07 and 4.0 μg, respectively/100 g b.w. of rat for 28 days) to evaluate their combined efficacy in the protection from mutagenic DNA-breakage and tissue damages. The selected tissues like intestine (first-pass site), liver (major xenobiotic metabolizer) and lung (major arsenic accumulator) were collected from arsenic-ingested (0.6 ppm/same schedule) female rats. The hemo-toxicity and liver and kidney functions were monitored. Our earlier studies on arsenic-exposed humans can correlate carcinogenesis with DNA damage. Here, we demonstrate that the supplementation of physiological/therapeutic dose of vitamin B12 and folate protected the rodents significantly from arsenic-induced DNA damage (DNA fragmentation and comet assay) and hepatic and renal tissue degeneration (histo-architecture, HE staining). The level of arsenic-induced free-radical products (TBARS and conjugated diene) was significantly declined by the restored actions of several antioxidants viz. urate, thiol, catalase, xanthine oxidase, lactoperoxidase, and superoxide dismutase in the tissues of vitamin-supplemented group. The alkaline phosphatase, transaminases, urea and creatinine (hepatic and kidney toxicity marker), and lactate dehydrogenase (tissue degeneration marker) were significantly impaired in the arsenic-fed group. But a significant protection was evident in the vitamin-supplemented group. In conclusion, the combined action of folate and B12 results in the restitution in the 1C metabolic pathway and cellular methyl pool. The cumulative outcome from the enhanced arsenic methylation and antioxidative capacity was protective against arsenic induced mutagenic DNA breakages and tissue damages.

Mitochondrial plasticity in cancer-related muscle wasting: potential approaches for its management

PURPOSE OF REVIEW

Cancer cachexia represents a critical problem in clinical oncology due to its negative impact on patients' quality of life, therapeutic tolerance and survival. This paraneoplasic condition is characterized by significant weight loss mainly from skeletal muscle wasting. Understanding the molecular mechanisms underlying cancer cachexia is urgent in order to develop and apply efficient therapeutic strategies.

RECENT FINDINGS

Mitochondrial dysfunction is an early event in cancer-induced muscle wasting. Decreased ability for ATP synthesis, impaired mitochondrial biogenesis, increased oxidative stress, impairment of protein quality control systems, increased susceptibility to mitophagy and to apoptosis were all shown to mediate contractile dysfunction and wasting in cancer cachexia. Anti-inflammatory therapies as well as exercise training seem to counteract muscle mass loss in part by improving mitochondrial functionality.

SUMMARY

Given its central role in muscle wasting, mitochondrial plasticity should be viewed as a key therapeutic target for the preservation of muscle mass in cancer cachexia. Few studies have addressed the mitochondrial events modulated by cancer cachexia and contradictory data were reported. Scarcer studies have focused on the mitochondrial adaptation to anticancer cachexia strategies.

Cryptotanshinone protects against adriamycin-induced mitochondrial dysfunction in cardiomyocytes

CONTEXT

The serious side effect of Adriamycin (ADR) is cardiomyopathy. Cryptotanshinone (CRY) is widely and safely used as antioxidant with MTD more than 5 mg/g in rats (p.o).

OBJECTIVE

The objective of this study is to study the protection effects of CRY against ADR-induced mitochondrial dysfunction in cardiomyocytes.

MATERIALS AND METHODS

The chemical administration lasted for 20 days with an effective dose of CRY (p.o.) at 50 mg/kg in rats. Mitochondrial respiratory chain complex activities, ATP generation, mitochondrial membrane potential (MMP), superoxide anion free radical, oxidative stress-relative enzymes, and mitochondrial biogenesis-relative factors in normal control, ADR (i.p., 1.25 mg/kg), and ADR (i.p., 1.25 mg/kg) + CYP (p.o., 50 mg/kg) groups were detected.

RESULTS

50 mg/kg CRY significantly promoted the energy production of ATP (16.99 ± 2.38 nmol/g Pro) (Pro: Protein) by increasing the complexes activities except II (p > 0.05). After the treatment of CRY, the suppressed MMP was increased while superoxide anion free radical (0.57 ± 0.07/mg Pro) was inhibited markedly. Mitochondrial biogenesis-relative factors PGC-1α, NRF-1, and TFAM were also promoted. Remarkable augmentations of NO, inducible nitric oxide synthase (iNOS), and increased activity of GSH-PX (p < 0.05) were also detected after the treatment of CRY, while no obvious changes on the activity of nitric oxide synthase (cNOS; p > 0.05) were observed.

DISCUSSION AND CONCLUSION

These results suggest that CRY protects against ADR-induced mitochondrial dysfunction in cardiomyocytes. It could be an ideal potential drug of cardioprotection.

Gated mesoporous silica nanoparticles for the controlled delivery of drugs in cancer cells

In recent years, mesoporous silica nanoparticles (MSNs) have been used as effective supports for the development of controlled-release nanodevices that are able to act as multifunctional delivery platforms for the encapsulation of therapeutic agents, enhancing their bioavailability and overcoming common issues such as poor water solubility and poor stability of some drugs. In particular, redox-responsive delivery systems have attracted the attention of scientists because of the intracellular reductive environment related to a high concentration of glutathione (GSH). In this context, we describe herein the development of a GSH-responsive delivery system based on poly(ethylene glycol)- (PEG-) capped MSNs that are able to deliver safranin O and doxorubicin in a controlled manner. The results showed that the PEG-capped systems designed in this work can be maintained closed at low GSH concentrations, yet the cargo can be delivered when the concentration of GSH is increased. Moreover, the efficacy of the PEG-capped system in delivering the cytotoxic agent doxorubicin in cells was also demonstrated.

Therapeutic strategies for mitochondrial disorders

OBJECTIVES

There is currently no curative therapy for mitochondrial disorders, although symptomatic measures can be highly effective and greatly improve the quality of life and outcome of these patients. This review highlights potential strategies for the therapeutic management of mitochondrial disorders.

METHODS

Data for this review were identified by searches of MEDLINE, Current Contents, using various relevant search terms.

RESULTS

Strategies to establish a therapeutic regimen aim to enhance respiratory chain function, eliminate noxious compounds, shift the heteroplasmy rate, alter mitochondrial dynamics, transfer cytoplasm, and promote gene therapy. Symptomatic measures rely on drugs (e.g., antiepileptics), avoidance of mitochondrion-toxic agents, substitution of blood cells, hemodialysis, invasive measures (such as a pacemaker), surgery (e.g., ptosis correction), physiotherapy, speech therapy, occupational therapy, dietary measures (e.g., ketogenic diet, anaplerotic diet), and the avoidance of mitochondrion-toxic agents (e.g., ozone). With the increasing awareness of mitochondrial disorders, the number of treatment studies is growing and its quality is improving. If high quality studies (high Jadad score) yield statistical significance for end points, a treatment is more reliable than with lower quality studies.

CONCLUSIONS

Despite the lack of a proven treatment for mitochondrial disorders, a nihilistic attitude toward treatment is not justified. A number of studies are seeking targeted therapies, and highly effective symptomatic measures are available.

A tocotrienol-enriched formulation protects against radiation-induced changes in cardiac mitochondria without modifying late cardiac function or structure

Radiation-induced heart disease (RIHD) is a common and sometimes severe late side effect of radiation therapy for intrathoracic and chest wall tumors. We have previously shown that local heart irradiation in a rat model caused prolonged changes in mitochondrial respiration and increased susceptibility to mitochondrial permeability transition pore (mPTP) opening. Because tocotrienols are known to protect against oxidative stress-induced mitochondrial dysfunction, in this study, we examined the effects of tocotrienols on radiation-induced alterations in mitochondria, and structural and functional manifestations of RIHD. Male Sprague-Dawley rats received image-guided localized X irradiation to the heart to a total dose of 21 Gy. Twenty-four hours before irradiation, rats received a tocotrienol-enriched formulation or vehicle by oral gavage. Mitochondrial function and mitochondrial membrane parameters were studied at 2 weeks and 28 weeks after irradiation. In addition, cardiac function and histology were examined at 28 weeks. A single oral dose of the tocotrienol-enriched formulation preserved Bax/Bcl2 ratios and prevented mPTP opening and radiation-induced alterations in succinate-driven mitochondrial respiration. Nevertheless, the late effects of local heart irradiation pertaining to myocardial function and structure were not modified. Our studies suggest that a single dose of tocotrienols protects against radiation-induced mitochondrial changes, but these effects are not sufficient against long-term alterations in cardiac function or remodeling.

Role of recombinant human erythropoietin against mitomycin C-induced cardiac, hepatic and renal dysfunction in Wistar rats

Mitomycin C (MMC) is one of the most effective chemotherapeutic drugs. However, the dose of MMC is greatly limited by its toxicity in normal tissues. Recombinant human erythropoietin (rhEPO), an erythropoietic hormone, has also been shown to exert tissue protective effects. The purpose of this study was to explore the protective effect of rhEPO against MMC-induced heart, liver, and renal dysfunction. Adult male Wistar rats were divided into six groups (with six animals each), namely control, rhEPO alone group, MMC alone group, and rhEPO + MMC group (pre-, co-, and posttreatment conditions). The results showed that MMC induced a marked cardiac, renal, and liver failure characterized by a significant decrease in body weight, organs weight, and organs ratio and a significant increase in creatinine, blood urea nitrogen, alanine aminotransferase, aspartate aminotransferase, γ-glutamyl transferase, and conjugated and total bilirubin levels in serum. Histological examination showed that MMC caused liver alterations. rhEPO treatment restored body weight, organs weight, and organs ratio as well as serum biochemical parameters and histological damage caused by MMC exposure.