The Heart As a Target for Xenobiotic Toxicity: The Cardiac Susceptibility to Oxidative Stress

Silybin prevented avermectin-induced cardiotoxicity in carp by modulating oxidative stress, inflammation, endoplasmic reticulum stress, mitochondrial apoptosis, and autophagy

Avermectin is one of the widely used anthelmintics in aquaculture and exhibits substantial toxicity to aquatic organisms. Silybin is extensively used for its anti-inflammatory, antioxidant and anti-apoptotic biological properties. Heart is essential for the survival of fish and plays a vital role in pumping blood oxygen and nutrients. Residual avermectin in water poses harm to carp. However, there is still insufficient research on whether silybin can mitigate the toxicity of avermectin to carp heart tissues. In this research, we established a model involving carp subjected to acute avermectin exposure and administered diets containing silybin to explore the potential protective effects of silybin against avermectin-induced cardiotoxicity. The results revealed that avermectin induced oxidative stress, inflammation, endoplasmic reticulum (ER) stress, mitochondrial pathway apoptosis and autophagy in the cardiac tissues of carp. Compared with the avermectin group, silybin significantly reduced ROS accumulation in cardiac tissues, restored antioxidant enzyme activity, inhibited mRNA transcript levels of pro-inflammatory-related factors, and attenuated ER stress, mitochondrial pathway apoptosis and autophagy. Protein-protein interaction (PPI) analysis demonstrated that silybin mitigated avermectin-induced cardiac oxidative stress, inflammation, ER stress, mitochondrial pathway apoptosis and autophagy. Silybin exerted anti-inflammatory effects through the Nuclear Factor kappa B (NF-κB) pathway, antioxidant effects through the Nuclear factor erythroid 2-related factor 2 (Nrf2) - Kelch-like ECH-associated protein 1 (Keap1) pathway, alleviated cardiac ER stress through the Glucose-regulated protein 78 (GRP78)/Activating Transcription Factor 6 (ATF6)/C/EBP homologous protein (CHOP) axis, suppressed apoptosis through the mitochondrial pathway, and inhibited excessive autophagy initiation through the PTEN-induced putative kinase 1 (PINK1)/Parkin RBR E3 ubiquitin protein ligase (PARKIN) signaling pathway. This study provided evidence supporting the protective effect of silybin against avermectin-induced cardiotoxicity in carp, highlighting its potential as a dietary additive to protect fish from adverse effects caused by avermectin exposure.

Cardioprotective and Hepatoprotective Potential of Silymarin in Paracetamol-Induced Oxidative Stress

Silymarin, derived from Silybum marianum, has been used in traditional medicine for various ailments. In this study, the cardioprotective and hepatoprotective effects of silymarin against paracetamol-induced oxidative stress were examined in 28 male Swiss Webster mice, divided into four groups and treated for 7 days (via the oral route) with (a) saline 1 mL/kg (control group), (b) saline 1 mL/kg + single dose of paracetamol 110 mg/kg on the 7th day; (c) silymarin 50 mg/kg; and (d) silymarin 50 mg/kg + single dose of paracetamol 110 mg/kg on the 7th day. In vitro and in vivo antioxidant activity together with liver enzyme activity were evaluated. Histopathological and immunohistochemical assessment was performed. Silymarin mitigated paracetamol-induced liver injury by reducing oxidative stress markers such as lipid peroxidation and restoring antioxidant enzyme activity. Silymarin treatment resulted in a significant decrease in liver enzyme levels. Reduced necrosis and inflammatory infiltrate in liver tissues of silymarin-treated groups were detected as well. Immunohistochemical analysis demonstrated reduced expression of inflammatory markers (COX2, iNOS) and oxidative stress marker (SOD2) in the liver tissues of the silymarin-treated groups. Similar trends were observed in cardiac tissue. These results suggest that silymarin exerts potent hepatoprotective and cardioprotective effects against paracetamol-induced oxidative stress, making it a promising therapeutic agent for liver and heart diseases associated with oxidative damage.

Antioxidant and Anticancer Activity of Vitis vinifera Extracts in Breast Cell Lines

Vitis vinifera extracts have been shown to possess antioxidant activity because of their polyphenol content. In addition, their therapeutic potential against several diseases, including cancer, has been reported. In this study, we produced twelve extracts from the seeds, fruit, leaves, and wood of the Vitis vinifera Airen variety using different extraction methodologies and measured their total polyphenol content (TPC). We also determined their antioxidant and antiproliferative effects against normal cells and evaluated the most potent extract against a panel of breast cancer cell lines. We found that the extracts produced by the seeds of Vitis vinifera had a higher TPC compared to the other parts of the plant. Most extracts produced from seeds had antioxidant activity and did not show cytotoxicity against normal breast cells. The extract produced from whole organic seeds of white grape showed the best correlation between the dose and the ROS inhibition at all time points compared to the other seed extracts and also had antiproliferative properties in estrogen-receptor-positive MCF-7 breast cancer cells. Its mechanism of action involves inhibition of proteins Bcl-2, Bcl-xL, and survivin, and induction of apoptosis. Further investigation of the constituents and activity of Vitis vinifera extracts may reveal potential pharmacological applications of this plant.

Edaravone and obeticholic acid protect against cisplatin-induced heart toxicity by suppressing oxidative stress and inflammation and modulating Nrf2, TLR4/p38MAPK, and JAK1/STAT3/NF-κB signals

Cardiotoxicity is a significant adverse effect of cisplatin (CIS) that necessitates extensive medical care. The current study examines the cardioprotective effects of edaravone (EDV), obeticholic acid (OCA), and their combinations on CIS-induced cardiac damage. Rats were allocated into five groups: the normal control group, the remaining four groups received CIS (7.5 mg/kg, i.p.) as a single dose on the fifth day and were assigned to CIS, OCA (10 mg/kg/day) + CIS, EDV (20 mg/kg/day) + CIS, and the (EDV + OCA) + CIS group. Compared to the CIS-treated group, co-treating rats with EDV, OCA, or their combinations significantly decreased ALP, AST, LDH, CK-MB, and troponin-I serum levels and alleviated histopathological heart abnormalities. Biochemically, EDV, OCA, and EDV plus OCA administration mitigated cardiac oxidative stress as indicated by a marked decrease in heart MDA content with a rise in cardiac antioxidants SOD and GSH associated with upregulating Nrf2, PPARγ, and SIRT1 expression. Besides, it dampened inflammation by decreasing cardiac levels of TNF-α, IL-1β, and IL-6, mediated by suppressing NF-κB, JAK1/STAT3, and TLR4/p38MAPK signal activation. Notably, rats co-administered with EDV plus OCA showed noticeable protection that exceeded that of EDV and OCA alone. In conclusion, our study provided that EDV, OCA, and their combinations effectively attenuated CIS-induced cardiac intoxication by activating Nrf2, PPARγ, and SIRT1 signals and downregulating NF-κB, JAK1/STAT3, and TLR4/p38MAPK signals.

A Clinically Relevant Dosage of Mitoxantrone Disrupts the Glutathione and Lipid Metabolic Pathways of the CD-1 Mice Brain: A Metabolomics Study

Long-term cognitive dysfunction, or "chemobrain", has been observed in cancer patients treated with chemotherapy. Mitoxantrone (MTX) is a topoisomerase II inhibitor that binds and intercalates with DNA, being used in the treatment of several cancers and multiple sclerosis. Although MTX can induce chemobrain, its neurotoxic mechanisms are poorly studied. This work aimed to identify the adverse outcome pathways (AOPs) activated in the brain upon the use of a clinically relevant cumulative dose of MTX. Three-month-old male CD-1 mice were given a biweekly intraperitoneal administration of MTX over the course of three weeks until reaching a total cumulative dose of 6 mg/kg. Controls were given sterile saline in the same schedule. Two weeks after the last administration, the mice were euthanized and their brains removed. The left brain hemisphere was used for targeted profiling of the metabolism of glutathione and the right hemisphere for an untargeted metabolomics approach. The obtained results revealed that MTX treatment reduced the availability of cysteine (Cys), cysteinylglycine (CysGly), and reduced glutathione (GSH) suggesting that MTX disrupts glutathione metabolism. The untargeted approach revealed metabolic circuits of phosphatidylethanolamine, catecholamines, unsaturated fatty acids biosynthesis, and glycerolipids as relevant players in AOPs of MTX in our in vivo model. As far as we know, our study was the first to perform such a broad profiling study on pathways that could put patients given MTX at risk of cognitive deficits.

Polygenic risk scores point toward potential genetic mechanisms of type 2 myocardial infarction in people with HIV

BACKGROUND

People with human immunodeficiency virus (HIV) infection (PWH) are at higher risk of myocardial infarction (MI) than those without HIV. About half of MIs in PWH are type 2 (T2MI), resulting from mismatch between myocardial oxygen supply and demand, in contrast to type 1 MI (T1MI), which is due to primary plaque rupture or coronary thrombosis. Despite worse survival and rising incidence in the general population, evidence-based treatment recommendations for T2MI are lacking. We used polygenic risk scores (PRS) to explore genetic mechanisms of T2MI compared to T1MI in PWH.

METHODS

We derived 115 PRS for MI-related traits in 9541 PWH enrolled in the Centers for AIDS Research Network of Integrated Clinical Systems cohort with adjudicated T1MI and T2MI. We applied multivariate logistic regression analyses to determine the association with T1MI and T2MI. Based on initial findings, we performed gene set enrichment analysis of the top variants composing PRS associated with T2MI.

RESULTS

We found that T1MI was strongly associated with PRS for cardiovascular disease, lipid profiles, and metabolic traits. In contrast, PRS for alcohol dependence and cholecystitis, significantly enriched in energy metabolism pathways, were predictive of T2MI risk. The association remained after the adjustment for actual alcohol consumption.

CONCLUSIONS

We demonstrate distinct genetic traits associated with T1MI and T2MI among PWH further highlighting their etiological differences and supporting the role of energy regulation in T2MI pathogenesis.

Organic ligands regulate the environmental impacts of metal-organic frameworks on nitrogen-fixing bacterium Azotobacter vinelandii

Metal-organic frameworks (MOFs) are rapidly developed materials with fantastic properties and wide applications. The increasing studies highlighted the potential threats of MOF materials to the environment. Comparing to the limited species of metal elements, the organic ligands have much higher diversity, but the influence of organic ligands on the environmental impacts of MOFs has not been revealed. Herein, we synthesized three Cu-MOFs with different organic ligands, namely Cu-BDC (1,4-terephthalic acid), Cu-IM (imidazole) and Cu-TATB (2,4,6-tris(4-carboxyphenyl)- 1,3,5-triazine), and evaluated their environmental toxicity to the nitrogen-fixing bacterium Azotobacter vinelandii. Cu-BDC inhibited the bacterial growth at lower concentrations than Cu-IM and Cu-TATB. The transcriptomes suggested the changes of membrane components by Cu-MOFs, consistent with the membrane leakage and cell wall damages. Cu-MOFs inhibited the nitrogen fixation activity through energy metabolism disturbance according to Gene Ontology functional annotation of ATP binding, Ca²⁺Mg²⁺-ATPase activity and ATP content. Only Cu-IM lowered the nitrogen fixation related nif genes, and affected the ribosome, purine metabolism and oxidative phosphorylation pathways. Otherwise, Cu-BDC and Cu-TATB mainly affected the flagellar assemblies and bacterial chemotaxis pathways. Our results collectively indicated that organic ligands regulated the environmental toxicity of MOFs through different metabolism pathways.

Abamectin causes cardiac dysfunction in carp via inhibiting redox equilibrium and resulting in immune inflammatory response and programmed cell death

This study aims to investigate the effects of environmentally relevant concentrations of abamectin on the cardiac function of carp and the potential mechanisms. Here, male carp were exposed to abamectin, and cardiac function-related enzymatic markers were examined. Cardiac histopathology, redox equilibrium, inflammation, and cell death were evaluated. Abamectin exposure caused cardiac dysfunction by upregulating lactate dehydrogenase (LDH), aspartate aminotransferase (AST), creatine kinase (CK), creatine Kinase MB isoenzyme (CK-MB) and white blood cells (WBCs), and decreasing red blood cells (RBCs) and hemoglobin (Hb). DHE staining and biochemical assays revealed that abamectin caused ROS release and oxidative stress by inhibiting Nrf2-ARE pathway. Histopathological and real-time fluorescence quantitative PCR (RT-qPCR) assays revealed that abamectin caused myocardial fiber swelling and inflammatory cell infiltration, enhanced pro-inflammatory cytokines tumor necrosis factor-α (Tnf-α), interleukin-1 beta (Il-1β), and Il-6 levels and attenuated anti-inflammatory cytokines Il-10 and transforming growth factor beta 1 (Tgf-β1) through activating NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome and nuclear factor kappa-B (NF-κB) pathway. Tunel staining showed that abamectin triggered cardiac apoptosis via activating p53-mediated mitochondrial apoptosis with elevated bcl2-associated X (Bax), reduced B-cell lymphoma-2 (Bcl-2), and activated Caspase-9 and Caspase-3. Immunoblot analysis revealed that abamectin activated autophagic flow by inhibiting mammalian target of rapamycin (mTOR), resulting in the conversion of LC3B from LC3-I to LC3-II, elevation of autophagy protein 5 (Atg5), and reduction of p62. Overall, abamectin caused cardiac dysfunction in carp via inhibiting redox equilibrium and resulting in immune inflammatory response and programmed cell death.

Investigating the effect of myricetin against arsenic-induced cardiac toxicity in rats

Arsenic intoxication is a serious health hazard worldwide. Its toxicity is associated with several disorders and health problems in humans. Recent studies revealed that myricetin has various biological effects, including anti-oxidation. The aim of this study is to investigate the protective effect of myricetin against arsenic-induced cardiotoxicity in rats. Rats were randomized to one of the following groups: control, myricetin (2 mg/kg), arsenic (5 mg/kg), myricetin (1 mg/kg) + arsenic, and myricetin (2 mg/kg) + arsenic. Myricetin was given intraperitoneally 30 min before arsenic administration (5 mg/kg for 10 days). After treatments, the activity of lactate dehydrogenase (LDH) and the levels of aspartate aminotransferase (AST), creatine kinase myocardial band (CK-MB), lipid peroxidation (LPO), total antioxidant capacity (TAC), and total thiol molecules (TTM) were determined in serum samples and cardiac tissues. Also, histological changes in cardiac tissue were evaluated. Myricetin pretreatment inhibited arsenic-induced increase in LDH, AST, CK-MB, and LPO levels. Pretreatment with myricetin also enhanced the decreased TAC and TTM levels. In addition, myricetin improved histopathological alterations in arsenic-treated rats. In conclusion, the results of the present study demonstrated that treatment with myricetin prevented arsenic-induced cardiac toxicity at least in part by decreasing oxidative stress and restoring the antioxidant system.

Autophagy (but not metabolism) is a key event in mitoxantrone-induced cytotoxicity in differentiated AC16 cardiac cells

Mitoxantrone (MTX) is an antineoplastic agent used to treat advanced breast cancer, prostate cancer, acute leukemia, lymphoma and multiple sclerosis. Although it is known to cause cumulative dose-related cardiotoxicity, the underlying mechanisms are still poorly understood. This study aims to compare the cardiotoxicity of MTX and its' pharmacologically active metabolite naphthoquinoxaline (NAPHT) in an in vitro cardiac model, human-differentiated AC16 cells, and determine the role of metabolism in the cardiotoxic effects. Concentration-dependent cytotoxicity was observed after MTX exposure, affecting mitochondrial function and lysosome uptake. On the other hand, the metabolite NAPHT only caused concentration-dependent cytotoxicity in the MTT reduction assay. When assessing the effect of different inhibitors/inducers of metabolism, it was observed that metyrapone (a cytochrome P450 inhibitor) and phenobarbital (a cytochrome P450 inducer) slightly increased MTX cytotoxicity, while 1-aminobenzotriazole (a suicide cytochrome P450 inhibitor) decreased fairly the MTX-triggered cytotoxicity in differentiated AC16 cells. When focusing in autophagy, the mTOR inhibitor rapamycin and the autophagy inhibitor 3-methyladenine exacerbated the cytotoxicity caused by MTX and NAPHT, while the autophagy blocker, chloroquine, partially reduced the cytotoxicity of MTX. In addition, we observed a decrease in p62, beclin-1, and ATG5 levels and an increase in LC3-II levels in MTX-incubated cells. In conclusion, in our in vitro model, neither metabolism nor exogenously given NAPHT are major contributors to MTX toxicity as seen by the residual influence of metabolism modulators used on the observed cytotoxicity and by NAPHT's low cytotoxicity profile. Conversely, autophagy is involved in MTX-induced cytotoxicity and MTX seems to act as an autophagy inducer, possibly through p62/LC3-II involvement.

Insights on the molecular targets of cardiotoxicity induced by anticancer drugs: A systematic review based on proteomic findings

Several anticancer agents have been associated with cardiac toxic effects. The currently proposed mechanisms to explain cardiotoxicity differ among anticancer agents, but in fact, the specific modulation is not completely elucidated. Thus, this systematic review aims to provide an integrative perspective of the molecular mechanisms underlying the toxicity of anticancer agents on heart muscle while using a high-throughput technology, mass spectrometry (MS)-based proteomics. A literature search using PubMed database led to the selection of 27 studies, of which 13 reported results exclusively on animal models, 13 on cardiomyocyte-derived cell lines and only one included both animal and a cardiomyocyte line. The reported anticancer agents were the proteasome inhibitor carfilzomib, the anthracyclines daunorubicin, doxorubicin, epirubicin and idarubicin, the antimicrotubule agent docetaxel, the alkylating agent melphalan, the anthracenedione mitoxantrone, the tyrosine kinase inhibitors (TKIs) erlotinib, lapatinib, sorafenib and sunitinib, and the monoclonal antibody trastuzumab. Regarding the MS-based proteomic approaches, electrophoretic separation using two-dimensional (2D) gels coupled with tandem MS (MS/MS) and liquid chromatography-MS/MS (LC-MS/MS) were the most common. Overall, the studies highlighted 1826 differentially expressed proteins across 116 biological processes. Most of them were grouped in larger processes and critically analyzed in the present review. The selection of studies using proteomics on heart muscle allowed to obtain information about the anticancer therapy-induced modulation of numerous proteins in this tissue and to establish connections that have been disregarded in other studies. This systematic review provides interesting points for a comprehensive understanding of the cellular cardiotoxicity mechanisms of different anticancer drugs.

The heart as a target for deltamethrin toxicity: Inhibition of Nrf2/HO-1 pathway induces oxidative stress and results in inflammation and apoptosis

As a synthetic pyrethroid pesticide, deltamethrin (DLM) is widely employed in veterinary medicine and farming, and DLM-triggered oxidative stress largely causes serious harm to the organism. It is well-known that nuclear factor erythroid-2-related factor 2/heme oxygenase-1 (Nrf2/HO-1), a pivotal endogenous anti-oxidative pathway, acts on inhibiting oxidative stress-induced cell injury under the activated state. The purpose of this research was to observe the impact and molecular mechanism of DLM on inflammation and apoptosis in quail cardiomyocytes based on the Nrf2/HO-1 signaling route. In this research, quails were established as a cardiac injury model through gastric infusion of various doses of DLM (0, 15, 30, and 45 mg/kg b. w.) for 12 weeks. Our results showed that DLM could induced cardiomyocyte injury in a dose-dependent manner though weakening antioxidant defense via down-regulating Nrf2 and its downstream protein HO-1. Furthermore, DLM stimulation induced apoptosis in quail heart by decreasing the protein expressions of B-cell lymphoma-extra large and B-cell lymphoma gene 2 (Bcl-2), as well as increasing P53, caspase 3, and Bcl-2-associated X protein levels. Meanwhile, relative levels of nuclear factor-kappa B and interleukin-1β in quail hearts were up-regulated under DLM intervention progressively. Collectively, our study demonstrates that chronic exposure to DLM can induce quail cardiomyocyte inflammation and apoptosis by mediating Nrf2/HO-1 signaling pathway-related oxidative stress.

Antioxidant role of selenium against maneb-induced cardiotoxicity in mice

The current study was conducted to assess the beneficial effect of selenium (Se) on maneb-induced cardiotoxicity and fatty acid alterations in adult mice. Swiss albino male mice were assigned into four experimental groups. The first group consisted of negative controls. The second group represented the positive controls where mice received daily, via the diet, sodium selenite at a dose of 0.2 mg/kg. For the third group, mice were subjected to intraperitoneal injections of maneb (30 mg/kg BW). The fourth group (MB+Se) received daily the same dose of maneb as group 3 along with sodium selenite at the same dose as group 2. Mice exposure to maneb caused cardiotoxicity as indicated by an increase in malondialdehyde, hydrogen peroxide, and protein carbonyl levels, and an alteration of the antioxidant defense system (catalase, glutathione peroxidase, superoxide dismutase, glutathione, and vitamin C). Plasma lactate dehydrogenase activity and total cholesterol, triglyceride, and low-density lipoprotein cholesterol levels increased, while high-density lipoprotein cholesterol level decreased. Results showed also a decrease in the amount of n-3 PUFA, docosahexaenoic, docosapentaenoic, and eicosapentaenoic acids. However, an increase in the levels of MUFA, cis-vaccenic, and palmitoleic acids was observed. Co-administration of Se restored the parameters indicated above to near control values. The histopathological findings confirmed the biochemical results. Selenium could be a useful and efficient agent against maneb-induced cardiotoxicity.

A review on the mitochondrial toxicity of “ecstasy” (3,4-methylenedioxymethamphetamine, MDMA)

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in vitro and in vivo studies on MDMA mitochondria toxicity are revised.

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MDMA causes ATP depletion and inhibition of mitochondrial complexes.

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MDMA or its metabolites impair mitochondrial trafficking in vitro.

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MDMA evokes deletion on mitochondrial DNA in vivo.

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A direct translation to humans is hampered by the doses and concentrations of MDMA.

3,4-Methylenedioxymethamphetamine (MDMA or “ecstasy”) is a drug of abuse used by millions worldwide. MDMA human abuse and dependence is well described, but addictive properties are not always consistent among studies. This amphetamine is a substrate type releaser, binding to monoamine transporters, leading to a pronounced release of serotonin and noradrenaline and to a minor extent dopamine. The toxicity of MDMA is well studied at the pre-clinical level, with neurotoxicity and hepatotoxicity being particularly described.

In this review, we describe the most relevant MDMA effects at the mitochondrial level found in in vitro and in vivo models, these later conducted in mice and rats. Most of these reports focus on the mitochondria of brain or liver. In in vitro models, MDMA causes depletion of ATP levels and inhibition of mitochondrial complex I and III, loss in mitochondrial membrane potential (ΔΨm) and induction of mitochondrial permeability transition. The involvement of mitochondria in the apoptotic cell death evoked by MDMA has also been shown, such as the release of cytochrome c. Additionally, MDMA or its metabolites impaired mitochondrial trafficking and increased the fragmentation of axonal mitochondria. In animal studies, MDMA decreased mitochondrial complex I activity and decreased ATP levels. Moreover, MDMA-evoked oxidative stress has been shown to cause deletion on mitochondrial DNA and impairment in mitochondrial protein synthesis.

Although the concentrations and doses used in some studies do not always correlate to the human scenario, the mitochondrial abnormalities evoked by MDMA are well described and are in part responsible for its mechanism of toxicity.

An innovative approach of bioremediation in enzymatic degradation of xenobiotics

Worldwide, environmental pollution due to a complex mixture of xenobiotics has become a serious concern. Several xenobiotic compounds cause environmental contamination due to their severe toxicity, prolonged exposure, and limited biodegradability. From the past few decades, microbial-assisted degradation (bioremediation) of xenobiotic pollutants has evolved as the most effective, eco-friendly, and valuable approach. Microorganisms have unique metabolism, the capability of genetic modification, diversity of enzymes, and various degradation pathways necessary for the bioremediation process. Microbial xenobiotic degradation is effective but a slow process that limits its application in bioremediation. However, the study of microbial enzymes for bioremediation is gaining global importance. Microbial enzymes have a huge ability to transform contaminants into non-toxic forms and thereby reduce environmental pollution. Recently, various advanced techniques, including metagenomics, proteomics, transcriptomics, metabolomics are effectively utilized for the characterization, metabolic machinery, new proteins, metabolic genes of microorganisms involved in the degradation process. These advanced molecular techniques provide a thorough understanding of the structural and functional aspects of complex microorganisms. This review gives a brief note on xenobiotics and their impact on the environment. Particular attention will be devoted to the class of pollutants and the enzymes such as cytochrome P450, dehydrogenase, laccase, hydrolase, protease, lipase, etc. capable of converting these pollutants into innocuous products. This review attempts to deliver knowledge on the role of various enzymes in the biodegradation of xenobiotic pollutants, along with the use of advanced technologies like recombinant DNA technology and Omics approaches to make the process more robust and effective.

Transcriptional Regulation of Structural and Functional Adaptations in a Developing Adulthood Myocardium

The development of the heart follows a synergic action of several signaling pathways during gestational, pre- & postnatal stages. The current study aimed to investigate whether the myocardium experiences transcriptional changes during the transition from post-natal to adult hood stages. Herein, we used C57/B16/J mice at 4 (28- days; post-natal/PN) and 20 weeks (adulthood/AH) of ages and employed the next generation RNAseq (NGS) to profile the transcriptome and echocardiography analysis to monitor the structural/functional changes in the heart. NGS-based RNA-seq revealed that 1215 genes were significantly upregulated and 2549 were down regulated in the AH versus PN hearts, indicating a significant transcriptional change during this transition.

A synchronized cardiac transcriptional regulation through cell cycle, growth hormones, redox homeostasis and metabolic pathways was noticed in both PN and AH hearts. Echocardiography reveals significant structural and functional (i.e. systolic/diastolic) changes during the transition of PN to adult stage. Particularly, a progressive decline in ejection fraction and cardiac output was observed in AH hearts. These structural adaptations are in line with critical signaling pathways that drive the maturation of heart during AH. Overall, we have presented a comprehensive transcriptomic analysis along with structural-functional relationship during the myocardial development in adult mice.

Analysis of toxicity effects of delta-9-tetrahydrocannabinol on isolated rat heart mitochondria

Mitochondria have the main roles in myocardial tissue homeostasis, through providing ATP for the vital enzymes in intermediate metabolism, contractile apparatus and maintaining ion homeostasis. Mitochondria-related cardiotoxicity results from the exposure with illicit drugs have previously reported. These illicit drugs interference with processes of normal mitochondrial homeostasis and lead to mitochondrial dysfunction and mitochondrial-related oxidative stress. Cannabis consumption has been shown to cause ventricular tachycardia, to increase the risk of myocardial infarction (MI) and potentially sudden death. Here, we investigated this hypothesis that delta-9-tetrahydrocannabinol (Delta-9-THC) as a main cannabinoid found in cannabis could directly cause mitochondrial dysfunction. Cardiac mitochondria were isolated with mechanical lysis and differential centrifugation form rat heart. The isolated cardiac mitochondria were treated with different concentrations of THC (1, 5, 10, 50, 100 and 500 µM) for 1 hour at 37 °C. Then, succinate dehydrogenase (SDH) activity, mitochondrial swelling, reactive oxygen species (ROS) formation, mitochondrial membrane potential (MMP) collapse and lipid peroxidation were measured in the treated and nontreated isolated cardiac mitochondria. Our observation showed that THC did not cause a deleterious alteration in mitochondrial functions, ROS production, MMP collapse, mitochondrial swelling, oxidative stress and lipid peroxidation in used concentrations (5-100 µM), even in several tests, toxicity showed a decreasing trend. Altogether, the results of the current study showed that THC is not directly toxic in isolated cardiac mitochondria, and even may be helpful in reducing mitochondrial toxicity.

Inflammation as a Possible Trigger for Mitoxantrone-Induced Cardiotoxicity: An In Vivo Study in Adult and Infant Mice

Mitoxantrone (MTX) is a pharmaceutical drug used in the treatment of several cancers and refractory multiple sclerosis (MS). Despite its therapeutic value, adverse effects may be severe, namely the frequently reported cardiotoxicity, whose mechanisms need further research. This work aimed to assess if inflammation or oxidative stress-related pathways participate in the cardiotoxicity of MTX, using the mouse as an animal model, at two different age periods (infant or adult mice) using two therapeutic relevant cumulative doses. Histopathology findings showed that MTX caused higher cardiac toxicity in adults. In MTX-treated adults, at the highest dose, noradrenaline cardiac levels decreased, whereas at the lowest cumulative dose, protein carbonylation increased and the expression of nuclear factor kappa B (NF-κB) p65 subunit and of M1 macrophage marker increased. Moreover, MTX-treated adult mice had enhanced expression of NF-κB p52 and tumour necrosis factor (TNF-α), while decreasing interleukin-6 (IL-6). Moreover, while catalase expression significantly increased in both adult and infant mice treated with the lowest MTX cumulative dose, the expression of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and glutathione peroxidase only significantly increased in infant animals. Nevertheless, the ratio of GAPDH to ATP synthase subunit beta decreased in adult animals. In conclusion, clinically relevant doses of MTX caused dissimilar responses in adult and infant mice, being that inflammation may be an important trigger to MTX-induced cardiotoxicity.

Effects of anticancer drugs on the cardiac mitochondrial toxicity and their underlying mechanisms for novel cardiac protective strategies

Mitochondria are organelles that play a pivotal role in the production of energy in cells, and vital to the maintenance of cellular homeostasis due to the regulation of many biochemical processes. The heart contains a lot of mitochondria because those muscles require a lot of energy to keep supplying blood through the circulatory system, implying that the energy generated from mitochondria is highly dependent. Thus, cardiomyocytes are sensitive to mitochondrial dysfunction and are likely to be targeted by mitochondrial toxic drugs. It has been reported that some anticancer drugs caused unwanted toxicity to mitochondria. Mitochondrial dysfunction is related to aging and the onset of many diseases, such as obesity, diabetes, cancer, cardiovascular and neurodegenerative diseases. Mitochondrial toxic mechanisms can be mainly explained concerning reactive oxygen species (ROS)/redox status, calcium homeostasis, and endoplasmic reticulum stress (ER) stress signaling. The toxic mechanisms of many anticancer drugs have been revealed, but more studying and understanding of the mechanisms of drug-induced mitochondrial toxicity is required to develop mitochondrial toxicity screening system as well as novel cardioprotective strategies for the prevention of cardiac disorders of drugs. This review focuses on the cardiac mitochondrial toxicity of commonly used anticancer drugs, i.e., doxorubicin, mitoxantrone, cisplatin, arsenic trioxide, and cyclophosphamide, and their possible chemopreventive agents that can prevent or alleviate cardiac mitochondrial toxicity.

Cardioprotective Effects of Natural Products via the Nrf2 Signaling Pathway

Due to its poor regenerative capacity, the heart is specifically vulnerable to xenobiotic- induced cardiotoxicity, myocardial ischaemia/reperfusion injury and other pathologies. Nuclear factor erythroid-2-related factor 2 (Nrf2) is considered as an essential factor in protecting cardiomyocytes against oxidative stress resulting from free radicals and reactive oxygen species. It also serves as a key regulator of antioxidant enzyme expression via the antioxidant response element, a cis-regulatory element, which is found in the promoter region of several genes encoding detoxification enzymes and cytoprotective proteins. It has been reported that a variety of natural products are capable of activating Nrf2 expression, and in this way, increase the antioxidant potential of cardiomyocytes. In the present review, we consider the cardioprotective activities of natural products and their possible therapeutic potential.

Mechanisms underlying the protective effect of tannic acid against arsenic trioxide‑induced cardiotoxicity in rats: Potential involvement of mitochondrial apoptosis

Arsenic trioxide (ATO) is a frontline chemotherapy drug used in the therapy of acute promyelocytic leukemia. However, the clinical use of ATO is hindered by its cardiotoxicity. The present study aimed to observe the potential effects and underlying mechanisms of tannic acid (TA) against ATO-induced cardiotoxicity. Male rats were intraperitoneally injected with ATO (5 mg/kg/day) to induce cardiotoxicity. TA (20 and 40 mg/kg/day) was administered to evaluate its cardioprotective efficacy against ATO-induced heart injury in rats. Administration of ATO resulted in pathological damage in the heart and increased oxidative stress as well as levels of serum cardiac biomarkers creatine kinase and lactate dehydrogenase and the inflammatory marker NF-κB (p65). Conversely, TA markedly reversed this phenomenon. Additionally, TA treatment caused a notable decrease in the expression levels of cleaved caspase-3/caspase-3, Bax, p53 and Bad, while increasing Bcl-2 expression levels. Notably, the application of TA decreased the expression levels of cytochrome c, second mitochondria-derived activator of caspases and high-temperature requirement A2, which are apoptosis mitochondrial-associated proteins. The present findings indicated that TA protected against ATO-induced cardiotoxicity, which may be associated with oxidative stress, inflammation and mitochondrial apoptosis.

Arsenic induces dose-dependent structural and ultrastructural pathological remodeling in the heart of Wistar rats

AIM

Arsenic, an environmental contaminant, represents a public health problem worldwide. Studies have shown its association with molecular mechanisms related to cardiomyocytes redox balance. However, the microstructure and ultrastructure of cardiac tissue, as well as the activity of its antioxidant defenses front of disturbances in the mineral bioavailability induced by arsenic are still scarce. Thus, the aim of this study was to evaluate if arsenic exposure might induce structural and ultrastructural damages in cardiac tissue, including pathological remodeling of the parenchyma and stroma. Moreover, its impact on micromineral distribution and antioxidant enzymes activity in heart tissue was also evaluated.

MAIN METHODS

Adult male Wistar rats were divided into three groups that received 0, 1 and 10 mg/L sodium arsenite in drinking water for eight weeks. The hearts were collected and subjected to structural and ultrastructural analysis, mineral microanalysis and antioxidant enzymes quantification. Functional markers of cardiac damages were evaluated using serum samples.

KEY FINDINGS

Arsenic exposure induced dose-dependent structural and ultrastructural remodeling of cardiac tissue, with parenchyma loss, increase of stroma components, collagen deposition, and pathological damages such as inflammation, sarcomere disorganization, mitochondria degeneration and myofilament dissociation. Moreover, this metalloid was bioaccumulated in the tissue affecting its micromineral content, which resulted in antioxidant imbalance and increased levels of oxidative stress and cardiac markers.

SIGNIFICANCE

Taken together, our findings indicate that the heart is a potential target to arsenic toxicity, and long-term exposure to this metalloid must be avoided, once it might induce several cardiac tissue pathologies.

M3, a 1,4-Dihydropyridine Derivative and Mixed L-/T-Type Calcium Channel Blocker, Attenuates Isoproterenol-Induced Toxicity in Male Wistar Rats

Recent evidence indicates that Ca²⁺ dysregulation is involved in the pathogenesis of isoproterenol (ISP)-induced biochemical toxicity and associated oxidative stress. In this study, we investigated the chemopreventive benefit of M3, a 1,4-dihydropyridine calcium channel blocker, against ISP-induced toxicity in male Wistar rats. Adult rats were divided into eight groups of six rats/group. Groups 1-5 received normal saline (control, 10 mL/kg/day, p.o.), ISP (85 mg/kg/day, s.c.), M3 lower dose (M3LD, 5 mg/kg, p.o.), M3 upper dose (M3UD, 20 mg/kg/day, p.o.), and Nifedipine (NFD, 20 mg/kg/day, p.o.), respectively. Others (groups 6-8) were pretreated with either M3LD, M3UD or NFD one hour before ISP administration. All rats were sacrificed 24 h after the last administration and changes in biochemical, hematological, and antioxidant parameters were assessed. Histologic examination of the heart, liver and kidney was also conducted. ISP elevated (p < 0.05) Ca²⁺, alanine aminotransferase, lactate dehydrogenase, triglycerides, and low-density lipoprotein levels when compared with control. Similarly, ISP increased levels of markers of renal function (p < 0.01), C-reactive protein (148.1%) and myocardial malondialdehyde (MDA, 88.7%) and tumor necrosis factor-alpha (109.2%). Platelet level was reduced (p < 0.05) in the ISP-intoxicated control rats. M3 exhibited antioxidant property, reduced levels of triglycerides, MDA and improved biochemical and hematological alterations associated with ISP toxicity. M3, however, was not effective in restoring histological changes that characterized ISP toxicity at the doses used. M3 offers chemopreventive benefits against ISP toxicity possibly through L-/T-type calcium channels blockade and modulatory actions on biochemical and antioxidant homeostasis.

Molecular Mechanisms of Cardiomyocyte Death in Drug-Induced Cardiotoxicity

Homeostatic regulation of cardiomyocytes plays a crucial role in maintaining the normal physiological activity of cardiac tissue. Severe cardiotoxicity results in cardiac diseases including but not limited to arrhythmia, myocardial infarction and myocardial hypertrophy. Drug-induced cardiotoxicity limits or forbids further use of the implicated drugs. Such drugs that are currently available in the clinic include anti-tumor drugs (doxorubicin, cisplatin, trastuzumab, etc.), antidiabetic drugs (rosiglitazone and pioglitazone), and an antiviral drug (zidovudine). This review focused on cardiomyocyte death forms and related mechanisms underlying clinical drug-induced cardiotoxicity, including apoptosis, autophagy, necrosis, necroptosis, pryoptosis, and ferroptosis. The key proteins involved in cardiomyocyte death signaling were discussed and evaluated, aiming to provide a theoretical basis and target for the prevention and treatment of drug-induced cardiotoxicity in the clinical practice.

A Bibliometric Review of Publications on Oxidative Stress and Chemobrain: 1990-2019

Oxidative stress is considered one of the possible mechanisms behind chemobrain or the cognitive dysfunction persistent after chemotherapy treatment. Breast cancer patients have reported chemobrain symptoms since the 1990s. In this present bibliometric review, we employed the VOSviewer tool to describe the existing landscape on literature concerning oxidative stress, breast cancer chemotherapies, and chemobrain. As of 2019, 8799 papers were listed in the Web of Science database, with more than 900 papers published each year. As expected, terms relating to oxidative stress, mitochondria, breast cancer, and antioxidants have occurred very often in the literature throughout the years. In recent years, there has been an increase in the occurrence of terms related to nanomedicine. Only within the last decade do the keywords 'brain', 'blood-brain barrier', and 'central nervous system' appear, reflecting an increased interest in chemobrain. China has become the most prolific producer of oxidative stress and chemotherapy related papers in the last decade followed by the USA and India. In conclusion, the subject of oxidative stress as a mechanism behind chemotherapies' toxicities is an active area of research.

Adverse outcome pathways induced by 3,4-dimethylmethcathinone and 4-methylmethcathinone in differentiated human SH-SY5Y neuronal cells

Cathinones (β-keto amphetamines), widely abused in recreational settings, have been shown similar or even worse toxicological profile than classical amphetamines. In the present study, the cytotoxicity of two β-keto amphetamines [3,4-dimethylmethcathinone (3,4-DMMC) and 4-methylmethcathinone (4-MMC)], was evaluated in differentiated dopaminergic SH-SY5Y cells in comparison to methamphetamine (METH). MTT reduction and NR uptake assays revealed that both cathinones and METH induced cytotoxicity in a concentration- and time-dependent manner. Pre-treatment with trolox (antioxidant) partially prevented the cytotoxicity induced by all tested drugs, while N-acetyl-L-cysteine (NAC; antioxidant and glutathione precursor) and GBR 12909 (dopamine transporter inhibitor) partially prevented the cytotoxicity induced by cathinones, as evaluated by the MTT reduction assay. Unlike METH, cathinones induced oxidative stress evidenced by the increase on intracellular levels of reactive oxygen species (ROS), and also by the decrease of intracellular glutathione levels. Trolox prevented, partially but significantly, the ROS generation elicited by cathinones, while NAC inhibited it completely. All tested drugs induced mitochondrial dysfunction, since they led to mitochondrial membrane depolarization and to intracellular ATP depletion. Activation of caspase-3, indicative of apoptosis, was seen both for cathinones and METH, and confirmed by annexin V and propidium iodide positive staining. Autophagy was also activated by all drugs tested. Pre-incubation with bafilomycin A1, an inhibitor of the vacuolar H⁺-ATPase, only protected against the cytotoxicity induced by METH, which indicates dissimilar toxicological pathways for the tested drugs. In conclusion, the mitochondrial impairment and oxidative stress observed for the tested cathinones may be key factors for their neurotoxicity, but different outcome pathways seem to be involved in the adverse effects, when compared to METH.

Citrus sinensis and Vitis vinifera Protect Cardiomyocytes from Doxorubicin-Induced Oxidative Stress: Evaluation of Onconutraceutical Potential of Vegetable Smoothies

The interest towards nutraceuticals able to counteract drug side effects is continuously growing in current chemotherapeutic protocols. In the present study, we demonstrated that smoothies containing mixtures of Citrus sinensis and Vitis vinifera L. cv. Aglianico N, two typical fruits of the Mediterranean diet, possess bioactive polyphenols that protect cardiomyocytes against doxorubicin-induced oxidative stress. The polyphenolic extracts isolated from Citrus sinensis- and Vitis vinifera-based functional smoothies were deeply characterized by Liquid Chromatography-Mass Spectrometry methods. Subsequently, the functional smoothies and relative mixtures were tested to verify their ability to affect cellular viability and oxidative stress parameters in embryonic cardiomyocyte cells (H9c2), and human breast adenocarcinoma cell line (MCF-7) exposed to doxorubicin. Interestingly, we found that the mix resulting from Citrus sinensis and Vitis vinifera association in ratio 1:1 was able to reduce cardiomyocytes damage induced by anthracyclines, without significantly interfering with the pro-apoptotic activity of the drug on breast cancer cells. These results point out the potential use of vegetable smoothies as adjuvants functional foods for chemotherapeutic anticancer protocols.

Unlocking Personalized Biomedicine and Drug Discovery with Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes: Fit for Purpose or Forever Elusive?

In recent decades, drug development costs have increased by approximately a hundredfold, and yet about 1 in 7 licensed drugs are withdrawn from the market, often due to cardiotoxicity. This review considers whether technologies using human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) could complement existing assays to improve discovery and safety while reducing socioeconomic costs and assisting with regulatory guidelines on cardiac safety assessments. We draw on lessons from our own work to suggest a panel of 12 drugs that will be useful in testing the suitability of hiPSC-CM platforms to evaluate contractility. We review issues, including maturity versus complexity, consistency, quality, and cost, while considering a potential need to incorporate auxiliary approaches to compensate for limitations in hiPSC-CM technology. We give examples on how coupling hiPSC-CM technologies with Cas9/CRISPR genome engineering is starting to be used to personalize diagnosis, stratify risk, provide mechanistic insights, and identify new pathogenic variants for cardiovascular disease.

An Overview on Arsenic Trioxide-Induced Cardiotoxicity

Arsenic trioxide (ATO) is among the first-line chemotherapeutic drugs used in oncological practice. It has shown substantial efficacy in treating patients with relapsed or refractory acute promyelocytic leukaemia. The clinical use of ATO is hampered due to cardiotoxicity and hence many patients are precluded from receiving this highly effective treatment. An alternative to this would be to use any drug that can ameliorate the cardiotoxic effects and allow exploiting the full therapeutic potential of ATO, with considerable impact on cancer therapy. Generation of reactive oxygen species is involved in a wide range of human diseases, including cancer, cardiovascular, pulmonary and neurological disorders. Hence, agents with the ability to protect against these reactive species may be therapeutically useful. The present review focuses on the beneficial as well as harmful effects of arsenic and ATO, the mechanisms underlying ATO toxicity and the possible ways that can be adopted to circumvent ATO-induced toxicity.

The Main Metabolites of Fluorouracil + Adriamycin + Cyclophosphamide (FAC) Are Not Major Contributors to FAC Toxicity in H9c2 Cardiac Differentiated Cells

In the clinical practice, the combination of 5-fluorouracil (5-FU) + Adriamycin (also known as doxorubicin, DOX) + cyclophosphamide (CYA) (known as FAC) is used to treat breast cancer. The FAC therapy, however, carries some serious risks, namely potential cardiotoxic effects, although the mechanisms are still unclear. In the present study, the role of the main metabolites regarding FAC-induced cardiotoxicity was assessed at clinical relevant concentrations. Seven-day differentiated H9c2 cells were exposed for 48 h to the main metabolites of FAC, namely the metabolite of 5-FU, α-fluoro-β-alanine (FBAL, 50 or 100 μM), of DOX, doxorubicinol (DOXOL, 0.2 or 1 μM), and of CYA, acrolein (ACRO, 1 or 10 μM), as well as to their combination. The parent drugs (5-FU 50 μM, DOX 1 μM, and CYA 50 μM) were also tested isolated or in combination with the metabolites. Putative cytotoxicity was evaluated through phase contrast microscopy, Hoechst staining, membrane mitochondrial potential, and by two cytotoxicity assays: the reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and the neutral red (NR) lysosomal incorporation. The metabolite DOXOL was more toxic than FBAL and ACRO in the MTT and NR assays. When in combination, neither FBAL nor ACRO increased DOXOL-induced cytotoxicity. No nuclear condensation was observed for any of the tested combinations; however, a significant mitochondrial potential depolarization after FBAL 100 μM + DOXOL 1 μM + ACRO 10 μM or FBAL 100 μM + DOXOL 1 μM exposure was seen at 48 h. When tested alone DOX 1 μM was more cytotoxic than all the parent drugs and metabolites in both the cytotoxicity assays performed. These results demonstrated that DOXOL was the most toxic of all the metabolites tested; nonetheless, the metabolites do not seem to be the major contributors to FAC-induced cardiotoxicity in this cardiac model.

Doxorubicin Is Key for the Cardiotoxicity of FAC (5-Fluorouracil + Adriamycin + Cyclophosphamide) Combination in Differentiated H9c2 Cells

Currently, a common therapeutic approach in cancer treatment encompasses a drug combination to attain an overall better efficacy. Unfortunately, it leads to a higher incidence of severe side effects, namely cardiotoxicity. This work aimed to assess the cytotoxicity of doxorubicin (DOX, also known as Adriamycin), 5-fluorouracil (5-FU), cyclophosphamide (CYA), and their combination (5-Fluorouracil + Adriamycin + Cyclophosphamide, FAC) in H9c2 cardiac cells, for a better understanding of the contribution of each drug to FAC-induced cardiotoxicity. Differentiated H9c2 cells were exposed to pharmacological relevant concentrations of DOX (0.13–5 μM), 5-FU (0.13–5 μM), CYA (0.13–5 μM) for 24 or 48 h. Cells were also exposed to FAC mixtures (0.2, 1 or 5 μM of each drug and 50 μM 5-FU + 1 μM DOX + 50 μM CYA). DOX was the most cytotoxic drug, followed by 5-FU and lastly CYA in both cytotoxicity assays (reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and neutral red (NR) uptake). Concerning the equimolar combination with 1 or 5 μM, FAC caused similar cytotoxicity to DOX alone. Even in the presence of higher concentrations of 5-FU and CYA (50 μM 5-FU + 1 μM DOX + 50 μM CYA), 1 μM DOX was still a determinant for the cardiotoxicity observed in the cytotoxicity assays, phase contrast morphological evaluation, and mitochondrial potential depolarization evaluation. To the best of our knowledge, this was the first in vitro work with this combination regimen, DOX being the most toxic drug and key to the toxicity of FAC.

AMP-activated protein kinase sparks the fire of cardioprotection against myocardial ischemia and cardiac ageing

AMP-activated protein kinase (AMPK) is a pivotal regulator of some endogenous defensive molecules in various pathological processes, particularly myocardial ischemia (MI), a high risk of myocardial infarction. Thereby it is of great significance to explore the inherent mechanism between AMPK and myocardial infarction. In this review, we first introduce the structure and role of AMPK in the heart. Next, we introduce the mechanisms of AMPK in the heart; followed by the energy regulation of AMPK in MI. Lastly, the attention will be expanded to some potential directions and further perspectives. The information compiled here will be helpful for further research and drug design in the future before AMPK might be considered as a therapeutic target of MI.

Bromine inhalation mimics ischemia-reperfusion cardiomyocyte injury and calpain activation in rats

Halogens are widely used, highly toxic chemicals that pose a potential threat to humans because of their abundance. Halogens such as bromine (Br₂) cause severe pulmonary and systemic injuries; however, the mechanisms of their toxicity are largely unknown. Here, we demonstrated that Br₂ and reactive brominated species produced in the lung and released in blood reach the heart and cause acute cardiac ultrastructural damage and dysfunction in rats. Br₂-induced cardiac damage was demonstrated by acute (3-24 h) increases in circulating troponin I, heart-type fatty acid-binding protein, and NH₂-terminal pro-brain natriuretic peptide. Transmission electron microscopy demonstrated acute (3-24 h) cardiac contraction band necrosis, disruption of z-disks, and mitochondrial swelling and disorganization. Echocardiography and hemodynamic analysis revealed left ventricular (LV) systolic and diastolic dysfunction at 7 days. Plasma and LV tissue had increased levels of brominated fatty acids. 2-Bromohexadecanal (Br-HDA) injected into the LV cavity of a normal rat caused acute LV enlargement with extensive disruption of the sarcomeric architecture and mitochondrial damage. There was extensive infiltration of neutrophils and increased myeloperoxidase levels in the hearts of Br_2- or Br₂ reactant-exposed rats. Increased bromination of sarco(endo)plasmic reticulum Ca²⁺-ATPase (SERCA) and increased phosphalamban after Br₂ inhalation decreased cardiac SERCA activity by 70%. SERCA inactivation was accompanied by increased Ca²⁺-sensitive LV calpain activity. The calpain-specific inhibitor MDL28170 administered within 1 h after exposure significantly decreased calpain activity and acute mortality. Bromine inhalation and formation of reactive brominated species caused acute cardiac injury and myocardial damage that can lead to heart failure. NEW & NOTEWORTHY The present study defines left ventricular systolic and diastolic dysfunction due to cardiac injury after bromine (Br₂) inhalation. A calpain-dependent mechanism was identified as a potential mediator of cardiac ultrastructure damage. This study not only highlights the importance of monitoring acute cardiac symptoms in victims of Br₂ exposure but also defines calpains as a potential target to treat Br₂-induced toxicity.

Study on the oxidation of fibrinogen using Fe3O4 magnetic nanoparticles and its influence to the formation of fibrin

Oxidative stress accompanies various diseases associated with chronic inflammation. In this work, H₂O₂ and H₂O₂-Fe₃O₄ magnetic nanoparticles were used as two reactive oxygen species to study the oxidative stress for the structure and polymerization behaviour of fibrinogen molecules. The alterations of secondary structure and component of fibrinogen molecule were characterized by circular dichroism spectra, ultraviolet-visible spectra and fluorescence spectra, the viscoelasticity of fibrinogen solution was studied by dynamic light scattering microrheology. Based on the molecular dynamics simulations and fluorescence properties, the possible oxidative stress sites were analyzed and confirmed by Tb³⁺ probe. The hydrophobicity/philicity and electrostatic net charges present on the exterior part of the fibrinogen molecules were measured with zeta potential. The height and image analysis obtained from atomic force microscope indicated that oxidative stress of fibrinogen molecules could influence the equilateral junctions of protofibrils and the different cross-linking patterns between the α- and γ-chains, result in the decrease of the fibre size, form a higher proportion of branching and a denser aggregation state. This study will provide insights into the misfolding and fibril formation of disease-associated fibrinogen, facilitate an increased understanding of how oxidative stress in vivo affects the formation and polymerization of fibrin, and support efforts for the improved treatment of patients suffering from the thrombotic disease.

Evidence for cardiotoxicity associated with sertraline in rats

Sertraline is an antidepressant that is frequently prescribed to treat depression, obsessive-compulsive disorder, panic disorder, and anxiety. This drug had a safe cardiotoxicity profile, until the reporting of cases of sertraline-associated cardiotoxicities in the early 2000s. Since then, there have been conflicting results on the cardiotoxicity of this drug. In the study reported here we aimed to identify the cardiotoxic effects of sertraline by evaluating serum cardiac biomarkers, such as serum aspartate aminotransferase (AST), creatinine phosphokinase-myoglobin band (CK-MB), lactate dehydrogenase (LDH), and cardiac troponin T (cTn-T) levels as well as electrocardiographic parameters, DNA damage in cardiomyocytes, and histological findings of heart tissue in rats that were administered oral doses of 5, 10, or 20 mg kg-1 of sertraline for 28 days. Additionally, to investigate the possible mechanisms underlying cardiotoxicity, glutathione and malondialdehyde levels in cardiac tissue were determined to evaluate oxidative stress. According to our results, AST, LDH, and cTn-T levels were significantly increased in the 10 and 20 mg kg-1 sertraline groups when compared to the control group. Heart rates were increased, PR intervals prolonged, a short QTc value was observed, and T-wave amplitudes were decreased significantly in the 20 mg kg-1 sertraline group when compared to the control group. Significant DNA damage was observed in the high-dose groups. Histopathological investigations also revealed some degenerative changes in the 10 and 20 mg kg-1 sertraline groups. Glutathione levels were significantly decreased in the 10 and 20 mg kg-1 sertraline groups when compared with the control group. In conclusion, our findings support the cardiotoxic potential of sertraline and also suggest that oxidative stress may play a role in the toxicity of sertraline.

Pixantrone, a new anticancer drug with the same old cardiac problems? An in vitro study with differentiated and non-differentiated H9c2 cells

Pixantrone (PIX) is an anticancer drug approved for the treatment of multiple relapsed or refractory aggressive B-cell non-Hodgkin's lymphoma. It is an aza-anthracenedione synthesized to have the same anticancer activity as its predecessors, anthracyclines (e.g. doxorubicin) and anthracenediones (e.g. mitoxantrone), with lower cardiotoxicity. However, published data regarding its possible cardiotoxicity are scarce. Therefore, this work aimed to assess the potential cytotoxicity of PIX, at clinically relevant concentrations (0.1; 1; and 10 μM) in both non-differentiated and 7-day differentiated H9c2 cells. Cells were exposed to PIX for 48 h and cytotoxicity was evaluated through phase contrast microscopy, Hoescht staining and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) reduction and neutral red (NR) uptake assays. Cytotoxicity was observed in differentiated and non-differentiated H9c2 cells, with detached cells and round cells evidenced by phase contrast microscopy, mainly at the highest concentration tested (10 μM). In the Hoechst staining, PIX 10 μM showed a marked decrease in the number of cells when compared to control but with no signs of nuclear condensation. Furthermore, significant concentration-dependent mitochondrial dysfunction was observed through the MTT reduction assay. The NR assay showed similar results to those obtained in the MTT reduction assay in both differentiated and non-differentiated H9c2 cells. The differentiation state of the cells was not crucial to PIX effects, although PIX toxicity was slightly higher in differentiated H9c2 cells. To the best of our knowledge, this was the first in vitro study performed with PIX in H9c2 cells and it discloses worrying cytotoxicity at clinically relevant concentrations.

Comprehensive review of cardiovascular toxicity of drugs and related agents

Cardiovascular diseases are a leading cause of morbidity and mortality in most developed countries of the world. Pharmaceuticals, illicit drugs, and toxins can significantly contribute to the overall cardiovascular burden and thus deserve attention. The present article is a systematic overview of drugs that may induce distinct cardiovascular toxicity. The compounds are classified into agents that have significant effects on the heart, blood vessels, or both. The mechanism(s) of toxic action are discussed and treatment modalities are briefly mentioned in relevant cases. Due to the large number of clinically relevant compounds discussed, this article could be of interest to a broad audience including pharmacologists and toxicologists, pharmacists, physicians, and medicinal chemists. Particular emphasis is given to clinically relevant topics including the cardiovascular toxicity of illicit sympathomimetic drugs (e.g., cocaine, amphetamines, cathinones), drugs that prolong the QT interval, antidysrhythmic drugs, digoxin and other cardioactive steroids, beta-blockers, calcium channel blockers, female hormones, nonsteroidal anti-inflammatory, and anticancer compounds encompassing anthracyclines and novel targeted therapy interfering with the HER2 or the vascular endothelial growth factor pathway.

Mitoxantrone is More Toxic than Doxorubicin in SH-SY5Y Human Cells: A 'Chemobrain' In Vitro Study

The potential neurotoxic effects of anticancer drugs, like doxorubicin (DOX) and mitoxantrone (MTX; also used in multiple sclerosis), are presently important reasons for concern, following epidemiological data indicating that cancer survivors submitted to chemotherapy may suffer cognitive deficits. We evaluated the in vitro neurotoxicity of two commonly used chemotherapeutic drugs, DOX and MTX, and study their underlying mechanisms in the SH-SY5Y human neuronal cell model. Undifferentiated human SH-SY5Y cells were exposed to DOX or MTX (0.13, 0.2 and 0.5 μM) for 48 h and two cytotoxicity assays were performed, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) reduction and the neutral red (NR) incorporation assays. Phase contrast microphotographs, Hoechst, and acridine orange/ethidium bromide stains were performed. Mitochondrial membrane potential was also assessed. Moreover, putative protective drugs, namely the antioxidants N-acetyl-l-cysteine (NAC; 1 mM) and 100 μM tiron, the inhibitor of caspase-3/7, Ac-DEVD-CHO (100 μM), and a protein synthesis inhibitor, cycloheximide (CHX; 10 nM), were tested to prevent DOX- or MTX-induced toxicity. The MTT reduction assay was also done in differentiated SH-SY5Y cells following exposure to 0.2 μM DOX or MTX. MTX was more toxic than DOX in both cytotoxicity assays and according to the morphological analyses. MTX also evoked a higher number of apoptotic nuclei than DOX. Both drugs, at the 0.13 μM concentration, caused mitochondrial membrane potential depolarization after a 48-h exposure. Regarding the putative neuroprotectors, 1 mM NAC was not able to prevent the cytotoxicity caused by either drug. Notwithstanding, 100 μM tiron was capable of partially reverting MTX-induced cytotoxicity in the NR uptake assay. One hundred μM Ac-DEVD-CHO and 10 nM cycloheximide (CHX) also partially prevented the toxicity induced by DOX in the NR uptake assay. MTX was more toxic than DOX in differentiated SH-SY5Y cells, while MTX had similar toxicity in differentiated and undifferentiated SH-SY5Y cells. In fact, MTX was the most neurotoxic drug tested and the mechanisms involved seem dissimilar among drugs. Thus, its toxicity mechanisms need to be further investigated as to determine the putative neurotoxicity for multiple sclerosis and cancer patients.

Methylphenidate clinically oral doses improved brain and heart glutathione redox status and evoked renal and cardiac tissue injury in rats

Methylphenidate (MPH) is a first-line stimulant drug to treat attention deficit hyperactivity disorder (ADHD). Overdiagnosis of ADHD and MPH abuse lead to serious concerns about the possible long-term adverse consequences of MPH in healthy children and adolescents. We aimed to evaluate MPH effects in adolescent male Wistar rats (postnatal day 40) using an oral dose scheme (2 daily MPH doses 5 mg/kg in a 5% sucrose solution, 5 h apart, for 7 days) that mimics the therapeutic doses given to human adolescents. Twenty-four hours after the last MPH administration, rats were sacrificed and brain areas [cerebellum, prefrontal cortex (PFC), hippocampus, and striatum], peripheral organs (liver, heart, and kidneys), and blood were collected for biochemical and histological analysis. MPH treatment did not alter rats' body temperature or weight, neither food or water intake throughout the experiment. The ratio of reduced glutathione/oxidized glutathione (GSH/GSSG) significantly increased in the PFC and hippocampus of MPH-treated rats, meanwhile protein carbonylation remained unchanged in the brain. In the heart, the GSH/GSSG ratio and GSH levels were significantly increased, with decreased GSSG, while histology revealed significant damage, namely interstitial edema, vascular congestion, and presence of a fibrin-like material in the interstitial space. In the kidneys, MPH treatment resulted in extensive necrotic areas with cellular disorganization and cell infiltration, and immunohistochemistry analysis revealed a marked activation of nuclear factor-ĸB. This study showed that clinically relevant oral MPH doses improve the GSH redox status in the brain and heart, but evoke heart and kidney tissue damage to adolescent rats.

Insights on Localized and Systemic Delivery of Redox-Based Therapeutics

Reactive oxygen and nitrogen species are indispensable in cellular physiology and signaling. Overproduction of these reactive species or failure to maintain their levels within the physiological range results in cellular redox dysfunction, often termed cellular oxidative stress. Redox dysfunction in turn is at the molecular basis of disease etiology and progression. Accordingly, antioxidant intervention to restore redox homeostasis has been pursued as a therapeutic strategy for cardiovascular disease, cancer, and neurodegenerative disorders among many others. Despite preliminary success in cellular and animal models, redox-based interventions have virtually been ineffective in clinical trials. We propose the fundamental reason for their failure is a flawed delivery approach. Namely, systemic delivery for a geographically local disease limits the effectiveness of the antioxidant. We take a critical look at the literature and evaluate successful and unsuccessful approaches to translation of redox intervention to the clinical arena, including dose, patient selection, and delivery approach. We argue that when interpreting a failed antioxidant-based clinical trial, it is crucial to take into account these variables and importantly, whether the drug had an effect on the redox status. Finally, we propose that local and targeted delivery hold promise to translate redox-based therapies from the bench to the bedside.

Recurrent exposure to ferric oxide nanoparticles alters myocardial oxidative stress, apoptosis and necrotic markers in male mice

The cardiotoxicity of iron oxide nanoparticles (Fe₂O₃-NPs) in mice was investigated. The mice were intraperitoneally administered with Fe₂O₃-NPs at the dose of 25 and 50 mg/kg bw for 30 days at seven days interval. In vivo MRI analysis reveals the Fe₂O₃-NPs accumulation in the cardiac system. Also, serum iron estimation and Prussian blue staining confirms the iron deposition in circulatory system. Cardiac dysfunction was assessed by ECG analysis and further validated by evaluating the functional markers such as cardiac Troponin-1 (cTnI) expression, AChE activity and levels of LDH and CK-MB in cardiac tissue. Fe₂O₃-NPs exposure disturbs the balance between the oxidants and antioxidants resulting in oxidative myocardial damages. In consequence, damaged mitochondria, diminished ATP level and NOX4 over expression were observed in the intoxicated groups indicating the role of Fe₂O₃-NPs in oxidative stress. A dose dependant increase in oxidative stress mediates apoptosis through upregulation of Bax, cytochrome c and cleaved caspase 3 in the 25 mg/kg treated group. Sustained oxidative stress suggest the occurrence of necrosis in addition to apoptosis in 50 mg/kg treated group evidenced by altered expression pattern of cleaved PARP, cytochrome c, Bax and cleaved caspase 3. In addition, triphenyl tetrazolium chloride (TTC) staining confirms cardiac necrosis in 50 mg/kg Fe₂O₃-NPs treated group.

Role of oxidative stress in cardiovascular disease outcomes following exposure to ambient air pollution

Exposure to ambient air pollution is associated with adverse cardiovascular outcomes. These are manifested through several, likely overlapping, pathways including at the functional level, endothelial dysfunction, atherosclerosis, pro-coagulation and alterations in autonomic nervous system balance and blood pressure. At numerous points within each of these pathways, there is potential for cellular oxidative imbalances to occur. The current review examines epidemiological, occupational and controlled exposure studies and research employing healthy and diseased animal models, isolated organs and cell cultures in assessing the importance of the pro-oxidant potential of air pollution in the development of cardiovascular disease outcomes. The collective body of data provides evidence that oxidative stress (OS) is not only central to eliciting specific cardiac endpoints, but is also implicated in modulating the risk of succumbing to cardiovascular disease, sensitivity to ischemia/reperfusion injury and the onset and progression of metabolic disease following ambient pollution exposure. To add to this large research effort conducted to date, further work is required to provide greater insight into areas such as (a) whether an oxidative imbalance triggers and/or worsens the effect and/or is representative of the consequence of disease progression, (b) OS pathways and cardiac outcomes caused by individual pollutants within air pollution mixtures, or as a consequence of inter-pollutant interactions and (c) potential protection provided by nutritional supplements and/or pharmacological agents with antioxidant properties, in susceptible populations residing in polluted urban cities.

Methylphenidate effects in the young brain: friend or foe?

Attention deficit hyperactivity disorder (ADHD) is one of the most prevalent neuropsychiatry disorders in children and adolescents, and methylphenidate (MPH) is a first-line stimulant drug available worldwide for its treatment. Despite the proven therapeutic efficacy, concerns have been raised regarding the possible consequences of chronic MPH exposure during childhood and adolescence. Disturbances in the neurodevelopment at these crucial stages are major concerns given the unknown future life consequences. This review is focused on the long-term adverse effects of MPH to the brain biochemistry. Reports conducted with young and/or adolescent animals and studies with humans are reviewed in the context of long-term consequences after early life-exposure. MPH pharmacokinetics is also reviewed as there are differences among laboratory animals and humans that may be relevant to extrapolate the findings. Studies reveal that exposure to MPH in laboratory animals during young and/or adolescent ages can impact the brain, but the outcomes are dependent on MPH dose, treatment period, and animal's age. Importantly, the female sex is largely overlooked in both animal and human studies. Unfortunately, human reports that evaluate adults following adolescent or child exposure to MPH are very scarce. In general, human data indicates that MPH is generally safe, although it can promote several brain changes in early ages. Even so, there is a lack of long course patient evaluation to clearly establish whether MPH-induced changes are friendly or foe to the brain and more human studies are needed to assess the adult brain changes that arise from early MPH treatment.

Short-Term Subclinical Zinc Deficiency in Weaned Piglets Affects Cardiac Redox Metabolism and Zinc Concentration

Background: Subclinical zinc deficiency (SZD) represents the common zinc malnutrition phenotype. However, its association with oxidative stress is not well understood. The heart muscle may be a promising target for studying early changes in redox metabolism.Objective: We investigated the effects of short-term SZD on cardiac redox metabolism in weaned piglets.Methods: Forty-eight weaned German Large White × Landrace × Piétrain piglets (50% castrated males and 50% females; body weight of 8.5 kg) were fed diets with different zinc concentrations for 8 d. Measurements included cardiac parameters of antioxidative capacity, stress-associated gene expression, and tissue zinc status. Analyses comprised (linear, broken-line) regression models and Pearson correlation coefficients.Results: Glutathione and α-tocopherol concentrations as well as catalase, glutathione reductase, B-cell lymphoma 2-associated X protein, and caspase 9 gene expression plateaued in response to reduction in dietary zinc from 88.0 to 57.6, 36.0, 36.5, 41.3, 55.3, and 33.8 mg/kg, respectively (P < 0.0001). Further reduction in dietary zinc promoted a linear decrease of glutathione and α-tocopherol (30 and 0.6 nmol/mg dietary Zn, respectively; P < 0.05) and a linear increase of gene expression [0.02, 0.01, 0.003, and 0.02 Log₁₀(2^-ΔΔCt)/mg dietary Zn, respectively; P < 0.05)]. Tissue zinc declined linearly with reduction in dietary zinc (0.21 mg tissue Zn/mg dietary Zn; P = 0.004) from 88.0 to 42.7 mg/kg (P < 0.0001), below which it linearly increased inversely to further reduction in dietary zinc (0.57 mg tissue Zn/mg dietary Zn; P = 0.006). H₂O₂-detoxification activity and metallothionein 1A gene expression decreased linearly with reduction in dietary zinc from 88.0 to 28.1 mg/kg [0.02 mU and 0.008 Log₁₀(2^-ΔΔCt)/mg dietary Zn, respectively; P < 0.05]. Fas cell-surface death receptor, etoposide-induced 2.4 and cyclin-dependent kinase inhibitor 1A gene expression correlated positively to cardiac zinc in piglets fed ≤42.7 mg Zn/kg (r ≥ 0.97; P < 0.05).Conclusions: Short-term SZD decreased cardiac antioxidative capacity of weaned piglets while simultaneously increasing stress-associated gene expression and zinc concentration. This is the first report to our knowledge on the effects of SZD on redox metabolism.

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.

The Increasing Prevalence in Intersex Variation from Toxicological Dysregulation in Fetal Reproductive Tissue Differentiation and Development by Endocrine-Disrupting Chemicals

An increasing number of children are born with intersex variation (IV; ambiguous genitalia/hermaphrodite, pseudohermaphroditism, etc.). Evidence shows that endocrine-disrupting chemicals (EDCs) in the environment can cause reproductive variation through dysregulation of normal reproductive tissue differentiation, growth, and maturation if the fetus is exposed to EDCs during critical developmental times in utero. Animal studies support fish and reptile embryos exhibited IV and sex reversal when exposed to EDCs. Occupational studies verified higher prevalence of offspring with IV in chemically exposed workers (male and female). Chemicals associated with endocrine-disrupting ability in humans include organochlorine pesticides, poly-chlorinated biphenyls, bisphenol A, phthalates, dioxins, and furans. Intersex individuals may have concurrent physical disorders requiring lifelong medical intervention and experience gender dysphoria. An urgent need exists to determine which chemicals possess the greatest risk for IV and the mechanisms by which these chemicals are capable of interfering with normal physiological development in children.

"Ecstasy" toxicity to adolescent rats following an acute low binge dose

BACKGROUND

3,4-Methylenedioxymethamphetamine (MDMA or "ecstasy") is a worldwide drug of abuse commonly used by adolescents. Most reports focus on MDMA's neurotoxicity and use high doses in adult animals, meanwhile studies in adolescents are scarce. We aimed to assess in rats the acute MDMA toxicity to the brain and peripheral organs using a binge dose scheme that tries to simulate human adolescent abuse.

METHODS

Adolescent rats (postnatal day 40) received three 5 mg/kg doses of MDMA (estimated equivalent to two/three pills in a 50 kg adolescent), intraperitoneally, every 2 h, while controls received saline. After 24 h animal sacrifice took place and collection of brain areas (cerebellum, hippocampus, frontal cortex and striatum) and peripheral organs (liver, heart and kidneys) occurred.

RESULTS

Significant hyperthermia was observed after the second and third MDMA doses, with mean increases of 1 °C as it occurs in the human scenario. MDMA promoted ATP levels fall in the frontal cortex. No brain oxidative stress-related changes were observed after MDMA. MDMA-treated rat organs revealed significant histological tissue alterations including vascular congestion, but no signs of apoptosis or necrosis were found, which was corroborated by the lack of changes in plasma biomarkers and tissue caspases. In peripheral organs, MDMA did not affect significantly protein carbonylation, glutathione, or ATP levels, but liver presented a higher vulnerability as MDMA promoted an increase in quinoprotein levels.

CONCLUSIONS

Adolescent rats exposed to a moderate MDMA dose, presented hyperthermia and acute tissue damage to peripheral organs without signs of brain oxidative stress.

Pathways of cardiac toxicity: comparison between chemotherapeutic drugs doxorubicin and mitoxantrone

Anthracyclines, e.g., doxorubicin (DOX), and anthracenediones, e.g., mitoxantrone (MTX), are drugs used in the chemotherapy of several cancer types, including solid and non-solid malignancies such as breast cancer, leukemia, lymphomas, and sarcomas. Although they are effective in tumor therapy, treatment with these two drugs may lead to side effects such as arrhythmia and heart failure. At the same clinically equivalent dose, MTX causes slightly reduced cardiotoxicity compared with DOX. These drugs interact with iron to generate reactive oxygen species (ROS), target topoisomerase 2 (Top2), and impair mitochondria. These are some of the mechanisms through which these drugs induce late cardiomyopathy. In this review, we compare the cardiotoxicities of these two chemotherapeutic drugs, DOX and MTX. As described here, even though they share similarities in their modes of toxicant action, DOX and MTX seem to differ in a key aspect. DOX is a more redox-interfering drug, while MTX induces energy imbalance. In addition, DOX toxicity can be explained by underlying mechanisms that include targeting of Top2 beta, mitochondrial impairment, and increases in ROS generation. These modes of action have not yet been demonstrated for MTX, and this knowledge gap needs to be filled.