Muscle Toxicity Research Articles

A Case of Transient Visual Disturbance and Ocular Paresis after Endoscopic Sinus Surgery

Endoscopic sinus surgery (ESS) is widely used as standard surgical treatment for chronic rhinosinusitis. Orbital complications of varying degrees occurred during ESS have been widely reported. If the orbital symptoms occurred immediately after surgery, ocular damage associated with surgery is suspected if the patient’s preoperative ocular function was patent. If immediate action is not taken, permanent visual loss might develop, so it is very important to diagnose orbital complications and take appropriate action. In our case, there was no definite intraorbital hemorrhage when sudden visual loss was noted. The symptoms were fully recovered without further treatment and it is clinically suspected to be caused by transient ocular muscle toxicity of local anesthetics.

Rhabdomyolysis and acute kidney injury induced by the association of rosuvastatin and abiraterone: A case report and review of the literature

Abiraterone acetate is an inhibitor of androgens biosynthesis, approved as first-line treatment in castration-resistant prostate cancer and metastatic castration-sensitive prostate cancer. Abiraterone has been rarely associated with severe rhabdomyolysis, but the mechanism of muscle toxicity is unknown. We hereby present a case of severe rhabdomyolysis resulting in acute on chronic kidney injury following abiraterone initiation in a patient previously under rosuvastatin. Rhabdomyolysis was resolutive after rosuvastatin and abiraterone discontinuation, and kidney function recovered. There was no recurrence of muscle toxicity after re-initiation of abiraterone alone. Abiraterone selectively inhibits CYP17 as well as the hepatic transporter OATP1B1. OATP1B1 is an efflux transporter, whose function is to extract several drugs from the portal blood, allowing them to undergo hepatic metabolism. We hypothesize that abiraterone-induced inhibition of plasmatic uptake of rosuvastatin by OATP1B1 increased plasmatic concentration of rosuvastatin, leading to toxicity on muscle cells. We therefore suggest that the association between rosuvastatin and abiraterone should be avoided.

Alcohol induces mitochondrial fragmentation and stress responses to maintain normal muscle function in Caenorhabditis elegans.

Chronic excessive ethanol consumption has distinct toxic and adverse effects on a variety of tissues. In skeletal muscle, ethanol causes alcoholic myopathy, which is characterized by myofiber atrophy and the loss of muscle strength. Alcoholic myopathy is more prevalent than all inherited muscle diseases combined. Current evidence indicates that ethanol directly impairs muscle organization and function. However, the underlying mechanism by which ethanol causes toxicity in muscle is poorly understood. Here, we show that the nematode Caenorhabditis elegans exhibits the key features of alcoholic myopathy when exposed to ethanol. As in mammals, ethanol exposure impairs muscle strength and induces the expression of protective genes, including oxidative stress response genes. In addition, ethanol exposure causes the fragmentation of mitochondrial networks aligned with myofibril lattices. This ethanol-induced mitochondrial fragmentation is dependent on the mitochondrial fission factor DRP-1 (dynamin-related protein 1) and its receptor proteins on the outer mitochondrial membrane. Our data indicate that this fragmentation contributes to the activation of the mitochondrial unfolded protein response (UPR). We also found that robust, perpetual mitochondrial UPR activation effectively reduces muscle weakness caused by ethanol exposure. Our results strongly suggest that the modulation of mitochondrial stress responses may provide a method to ameliorate alcohol toxicity and damage to muscle.

Doxorubicin‐Induced Muscle Toxicity: A Novel Mechanism Involving Inflammation‐Mediated Pyroptosis in Soleus Muscle

Doxorubicin (Dox) is an effective chemotherapeutic agent which is widely used clinically to treat solid tumors. Unfortunately, the use of Dox has been restricted due to serious side effects including skeletal muscle toxicity. The current dogma is that Dox‐induced muscle toxicity (DIMT) is mediated through enhanced oxidative stress, inflammation, and unwanted cell death due to apoptosis and necrosis. We hypothesized that inflammation‐mediated cell death known as “pyroptosis” plays a critical role in DIMT. To test this notion, we generated a mouse model of DIMT where C57BL/6J mice (10±2 weeks, male and female), were treated with Dox [12mg/kg cumulative dose, administered through 3 intraperitoneal (i.p.) injections on alternative days]. Mice were sacrificed 14 days following the last injection of Dox and soleus muscle (SM) was harvested. The expression of TLR4, inflammasome (NLRP3 and ASC), pyroptotic markers (caspase‐1, IL‐1β, and IL‐18), pro‐inflammatory cytokines (TNF‐α and IL‐6), pro‐inflammatory M1 macrophages (iNOS), and anti‐inflammatory M2 macrophages (CD206 and Arginase‐1) were measured using immunostaining and western blot techniques. Skeletal muscle function was measured prior to sacrifice. The results showed a significant increase (p<0.05) in the expression of inflammasome formation, pyroptotic markers, pro‐inflammatory cytokines, and M1 macrophage while a significant decrease (p<0.05) in the infiltration of M2 macrophages was observed following Dox administration as compared to saline treated controls. Furthermore, muscle strength was significantly decreased (p<0.05) in Dox‐treated mice vs. control. These data indicate that Dox induces NLRP3‐ASC inflammasome‐mediated pyroptosis, increases inflammation and M1 macrophage infiltration, while decreasing M2 macrophages thereby causing muscle weakness. We propose that novel strategies specifically targeted towards limiting pyroptosis may help in attenuating DIMT in cancer patients receiving Dox chemotherapy.

HMGB1 Initiates Inflammasome Mediated Pyroptosis, Atrophy and Adverse Muscle Remodeling

Diabetic cardiomyopathy and associated muscle toxicity is a major concern, therefore it is essential to understand the mechanism and pathophysiology of diabetic skeletal muscle which remains unknown. The current study is undertaken to investigate whether there is an upregulation of High Mobility Group‐B1 (HMGB1) that initiates inflammation induced pyroptosis and involves adverse muscle remodeling. C57BL/6J mice (10±2 weeks) were divided into 2‐groups (n=16/group; 8males and 8females); control (saline) and STZ treated (200mg/kg body weight) via i.p. injection. Diabetes was established by determining the increased levels of glucose in STZ animals. At Day‐42, muscle function was determined using Grip‐strength meter and Rotarod. Mice were euthanized and gastrocnemius (GM) muscle was harvested. Pyroptotic initiator HMGB1, activator TLR4, inflammasome marker (NLRP3), and pyroptotic markers (caspase1, IL1β, IL‐18 and GSDMD) were examined using immunohistochemistry, western blotting and RT‐PCR. Muscle atrophy and fibrosis was examined histologically. IL‐6 inflammatory cytokine levels were analyzed using ELISA. We observed a significant (p<0.05) increase in glucose levels, pyroptotic initiator HMGB1, inflammasome and pyroptotic markers in GM of STZ administered mice as compared to control. A significant (p<0.05) decrease in myofibrillar area was observed in diabetic mice. Atrophy was also confirmed by significant increase (p<0.05) in MuRF1 gene expression. Interstitial and vascular fibrosis was significantly (p<0.05) increased in STZ group versus control. Moreover, a significant decrease (p<0.05) in muscle functions were observed in diabetic animals compared to control. Furthermore, a significant (p<0.05) increase in plasma IL‐6 levels were observed in diabetic mice. In conclusion, our data suggest that diabetes involves a novel form of inflammation induced pyroptosis that leads to muscle dysfunction. Further therapeutic approaches need to be developed to target pyroptosis in diabetes.

Long-term neuromusculoskeletal side effects and quality of life in nasopharyngeal cancer patients receiving radiochemotherapy.

In this study, we aimed to evaluate the neuromusculoskeletal late side effects and their impact on the quality of life of patients with nasopharyngeal carcinoma treated with radiochemotherapy. Twenty-seven patients were included. The mean follow-up was 61months (range, 18-111months). The median external radiotherapy dose applied to the nasopharynx and primary tumor was 70Gy (range, 61-73Gy). The mean dose received by the temporomandibular joint in the dose-volume histograms of these patients was 60.7Gy. The maximal doses of the muscles responsible for cervical motion in different ranges were greater than 60Gy, and the mean doses were greater than 40Gy in the muscle groups, except for the extensor muscles. Two patients had brachial plexus involvement, while 89% of the patients had restriction in flexion and extension movements. Of the patients, 52% had trismus. There was a significant correlation between extension restriction and general heath score and the physical subscale of the quality-of-life questionnaire (p = 0.01). There was also a correlation between trismus and pain killer usage (p = 0.004). This is the first study to analyze long-term muscle and nerve toxicity and their correlation between doses in nasopharyngeal cancer patients following radiochemotherapy. Despite the advances in radiotherapy techniques, it is necessary to pay attention to the doses of the nerves and muscles for late effects.

Freeze-Dried Extracellular Vesicles From Adipose-Derived Stem Cells Prevent Hypoxia-Induced Muscle Cell Injury.

Cellular therapies have tremendous potential for the successful treatment of major extremity wounds in the combat setting, however, the challenges associated with transplanting stem cells in the prolonged field care (PFC) environment are a critical barrier to progress in treating such injuries. These challenges include not only production and storage but also transport and handling issues. Our goal is to develop a new strategy utilizing extracellular vesicles (EVs) secreted by stem cells that can resolve many of these issues and prevent ischemic tissue injury. While EVs can be preserved by freezing or lyophilization, both processes result in decrease in their bioactivity. Here, we describe optimized procedures for EVs production, isolation, and lyophilization from primary human adipose-derived stem cells (hADSCs). We compared two isolation approaches that were ultrafiltration (UF) using a tangential fluid filtration (TFF) system and differential ultracentrifugation (UC). We also optimized EVs lyophilization in conjunction with trehalose and polyvinylpyrrolidone 40 (PVP40) as lyoprotectants. Bioactivity of EVs was assessed based on reversal of hypoxia-induced muscle cell injury. To this end, primary human myoblasts were subjected to hypoxic conditions for 6 h, and then treated with hADSC-derived EVs at a concentration of 50 μg/mL. Subsequently, muscle cell viability and toxicity were evaluated using MTS and LDH assays, respectively. Overall, nanoparticle tracking data indicated that UF/TFF yields threefold more particles than UC. Lyophilization of EVs resulted in a significantly reduced number of particles, which could be attenuated by adding lyoprotections to the freeze-drying solution. Furthermore, EVs isolated by UF/TFF and freeze-dried in the presence of trehalose significantly increased viability (P < 0.0193). Taken together, our findings suggest that the isolation and preservation methods presented in this study may enhance therapeutic applications of EVs.

Time-dependent simvastatin administration enhances doxorubicin toxicity in neuroblastoma

Statins have a primary indication for the reduction and management of hypercholesterolemia; however, evidence shows that statins have the ability to increase the toxicity of chemotherapeutics within cancer cells by inducing anti-proliferative, anti-metastatic, and anti-angiogenic effects. More recently, lipophilic statins have shown complex interaction with energy metabolism, specifically acute mitochondrial dysfunction and delayed inhibition of glycolysis. With the goal to demonstrate that statin-mediated enhancement of chemotherapeutics is time-dependent, we hypothesized that the lipophilic statin simvastatin, in conjunction with variable co-exposure of doxorubicin or cisplatin, will enhance the toxicity of these drugs in neuroblastoma. Utilizing human SK-N-AS neuroblastoma cells, we assessed cell proliferation, necrosis, caspase activation, and overall apoptosis of these cells. After determining the toxicity of simvastatin at 48 h post-treatment, 10μM was chosen as the intervention concentration. We found that significant cell death resulted from 1.0μM dose of doxorubicin with 24 h pre-treatment of simvastatin. On the other hand, simvastatin enhancement of cisplatin toxicity was only observed in the co-exposure model. As doxorubicin has strict dosage limits due to its primary off-target toxicity in cardiac muscle, we further compared the effects of this drug combination on rat H9C2 cardiomyoblasts. We found that simvastatin did not enhance doxorubicin toxicity in this cell line. We conclude that simvastatin provides time-dependent sensitization of neuroblastoma cells to doxorubicin toxicity, and our results provide strong argument for the consideration of simvastatin as an adjuvant in doxorubicin-based chemotherapy programs.

Muscle Toxicity of Drugs: When Drugs Turn Physiology into Pathophysiology.

Drugs are prescribed to manage or prevent symptoms and diseases, but may sometimes cause unexpected toxicity to muscles. The symptomatology and clinical manifestations of the myotoxic reaction can vary significantly between drugs and between patients on the same drug. This poses a challenge on how to recognize and prevent the occurrence of drug-induced muscle toxicity. The key to appropriate management of myotoxicity is prompt recognition that symptoms of patients may be drug related and to be aware that inter-individual differences in susceptibility to drug-induced toxicity exist. The most prevalent and well-documented drug class with unintended myotoxicity are the statins, but even today new classes of drugs with unintended myotoxicity are being discovered. This review will start off by explaining the principles of drug-induced myotoxicity and the different terminologies used to distinguish between grades of toxicity. The main part of the review will focus on the most important pathogenic mechanisms by which drugs can cause muscle toxicity, which will be exemplified by drugs with high risk of muscle toxicity. This will be done by providing information on key clinical and laboratory aspects, muscle electromyography patterns and biopsy results, and pathological mechanism and management for a specific drug from each pathogenic classification. In addition, rather new classes of drugs with unintended myotoxicity will be highlighted. Furthermore, we will explain why it is so difficult to diagnose drug-induced myotoxicity, and which tests can be used as a diagnostic aid. Lastly, a brief description will be given of how to manage and treat drug-induced myotoxicity.

Comparative effects of Mancozeb and Disulfiram-induced striated muscle myopathies in Long-Evans rats

Dithiocarbamates (DTCs) like mancozeb (MZ) and disulfiram (DS) are used throughout agriculture and medicine and have been implicated in neurotoxicity. Little research has been studied on the reported myopathies caused by these compounds. Their pathogenesis and mechanism of muscle toxicity has not been fully studied. The aim of this study is to investigate if DTCs alter striated muscle tissues in vivo. Long-Evans rats were treated with either MZ or DS followed by analysis of muscle biomarkers and metal levels. DS resulted in increases in serum lactate dehydrogenase (LDH), cardiac troponin, and myoglobin levels. Creatine kinase-MB serum levels decreased. Mancozeb only showed an increase in serum LDH. Both MZ and DS-treatment resulted in altered metal levels in the myocardium but not skeletal muscle. Ultrastructural alterations included damaged mitochondria and myofibril splitting. The presence of multivesicular bodies, and alterations of the intercalated disc were also seen.

Safety of two different doses of simvastatin plus rifaximin in decompensated cirrhosis (LIVERHOPE-SAFETY): a randomised, double-blind, placebo-controlled, phase 2 trial

Statins have beneficial effects on intrahepatic circulation and decrease portal hypertension and rifaximin modulates the gut microbiome and might prevent bacterial translocation in patients with cirrhosis. Therefore, this drug combination might be of therapeutic benefit in patients with decompensated cirrhosis. However, there is concern regarding the safety of statins in patients with decompensated cirrhosis. We assessed the safety of two different doses of simvastatin, in combination with rifaximin, in patients with decompensated cirrhosis. We did a double-blind, randomised, placebo-controlled, phase 2 trial in patients with decompensated cirrhosis and moderate-to-severe liver failure from nine university hospitals in six European countries (Italy, France, Holland, Germany, the UK, and Spain). Patients older than 18 years with Child-Pugh class B or C disease were eligible. We randomly assigned patients (1:1:1) to receive either simvastatin 40 mg/day plus rifaximin 1200 mg/day, simvastatin 20 mg/day plus rifaximin 1200 mg/day, or placebo of both medications for 12 weeks. Randomisation was stratified according to Child-Pugh class (B vs C) and restricted using blocks of multiples of three. The primary endpoint was development of liver or muscle toxicity, as defined by changes in liver aminotransferases (aspartate aminotransferase [AST] and alanine aminotransferase [ALT]), alkaline phosphastase, and creatine kinase. The study is registered with the European Union Clinical Trials Register, 2016-004499-23, and with ClinicalTrials.gov, NCT03150459. The study recruitment period was between July 28, 2017, and Jan 2, 2018. Follow-up finished on March 12, 2018. 50 patients were randomly assigned to simvastatin 40 mg/day plus rifaximin 1200 mg/day (n=18), simvastatin 20 mg/day plus rifaximin 1200 mg/day (n=16), or placebo of both medications (n=16). Six patients (two from each group) were excluded. Therefore, the full analysis set included 44 patients (16 in the simvastatin 40 mg/day plus rifaximin 1200 mg/day group, 14 in the simvastatin 20 mg/day plus rifaximin mg/day group, and 14 in the placebo group). After a safety analyses when the first ten patients completed treatment, treatment was stopped prematurely in the simvastatin 40 mg/day plus rifaximin group due to recommendations by the data safety monitoring board. Patients in the simvastatin 40 mg/day plus rifaximin group showed a significant increase in AST and ALT compared with the placebo group (mean differences between the groups at the end of treatment for AST 130 IU/L [95% CI 54 to 205; p=0·0009] and for ALT 61 IU/L [22 to 100; p=0·0025]. We observed no significant differences at 12 weeks in AST and ALT between the simvastatin 20 mg/day plus rifaximin and placebo group (for AST -14 IU/L [-91 to 64; p=0·728] and for ALT -8 IU/L [-49 to 33; p=0·698]). We observed no significant differences in alkaline phosphatase between the the simvastatin 40 mg/day plus rifaximin or the simvastatin 20 mg/day plus rifaximin groups compared with placebo. Patients in the simvastatin 40 mg/day plus rifaximin group showed an increase in creatine kinase at the end of treatment compared with patients in the placebo group (1009 IU/L [208 to 1809]; p=0·014). We observed no significant changes in creatine kinase in the simvastatin 20 mg/day plus rifaximin group (4·2 IU/L [-804 to 813]; p=0·992). Three (19%) patients in the simvastatin 40 mg/day group developed liver and muscle toxicity consistent with rhabdomyolysis. The number of patients who stopped treatment because of adverse events was significantly higher in the simvastatin 40 mg/day plus rifaximin group (nine [56%] of 16 patients) compared with the other two groups (two [14%] of 14 for both groups; p=0·017). There were no serious unexpected adverse reactions reported during the study. Treatment with simvastatin 40 mg/day plus rifaximin in patients with decompensated cirrhosis was associated with a significant increase in adverse events requiring treatment withdrawal, particularly rhabdomyolysis, compared with simvastatin 20 mg/day plus rifaximin. We recommend simvastatin 20 mg/day as the dose to be used in studies investigating the role of statins in patients with decompensated cirrhosis. Horizon 20/20 European programme.

FUS-mediated regulation of acetylcholine receptor transcription at neuromuscular junctions is compromised in amyotrophic lateral sclerosis.

Neuromuscular junction (NMJ) disruption is an early pathogenic event in amyotrophic lateral sclerosis (ALS). Yet, direct links between NMJ pathways and ALS-associated genes such as FUS, whose heterozygous mutations cause aggressive forms of ALS, remain elusive. In a knock-in Fus-ALS mouse model, we identified postsynaptic NMJ defects in newborn homozygous mutants, attributable to mutant FUS toxicity in skeletal muscle. Adult heterozygous knock-in mice displayed smaller neuromuscular endplates that denervated before motor neuron loss, consistent with ‘dying-back’ neuronopathy. FUS was enriched in subsynaptic myonuclei, and this innervation-dependent enrichment was distorted in FUS-ALS. Mechanistically, FUS collaborates with the ETS-transcription factor ERM to stimulate transcription of acetylcholine receptor (AchR) genes. FUS-ALS patient iPSC-derived motor neuron-myotube co-cultures revealed endplate maturation defects due to intrinsic FUS toxicity in both motor neurons and myotubes. Thus, FUS regulates AChR gene expression in subsynaptic myonuclei and muscle-intrinsic toxicity of ALS-mutant FUS may contribute to dying-back motor neuronopathy.

"STATINS KALEIDOSCOPE". MYOPATHY FROM STATINS

Statins are medications that inhibit the 3-hydroxy-3-methylglutaryl-CoA reductase enzyme, thus inhibiting cholesterol biosynthesis. Statins reduce cardiovascular risk and morbidity in patients with coronaropathia, however, without forgetting their side effect in muscle toxicity. Clinically, patients with myopathy caused by statins are divided into four main groups: those with rhabdomyolysis, myalgia / hyper CPK, toxic myopathy limited by statins and myositis (necrotizing myopathy mediated by immune complexes with anti-HMGCR antibodies, IMNM).

Creatine as a Candidate to Prevent Statin Myopathy.

Statins prevent cardiovascular diseases, yet their use is limited by the muscle disturbances they cause. Rarely, statin-induced myopathy is autoimmune, but more commonly it is due to direct muscle toxicity. Available evidence suggests that statin-induced creatine deficiency might be a major cause of this toxicity, and that creatine supplementation prevents it. Statins inhibit guanidinoacetate methyl transferase (GAMT), the last enzyme in the synthesis of creatine; thus, they decrease its intracellular content. Such decreased content could cause mitochondrial impairment, since creatine is the final acceptor of the phosphate group of adenosine triphosphate (ATP) at the end of mitochondrial oxidative phosphorylation. Decreased cellular synthesis of ATP would follow. Accordingly, ATP synthesis is decreased in statin-treated cells. In vitro, creatine supplementation prevents the opening of the mitochondrial permeability transition pore that is caused by statins. Clinically, creatine administration prevents statin myopathy in statin-intolerant patients. Additional research is warranted to hopefully confirm these findings. However, creatine is widely used by athletes with no adverse events, and has demonstrated to be safe even in double-blind, placebo-controlled trials of elderly individuals. Thus, it should be trialed, under medical supervision, in patients who cannot assume statin due to the occurrence of muscular symptoms.

Mitophagy protects against statin-mediated skeletal muscle toxicity.

The deleterious effects of statins on skeletal muscle are well known, but the mechanism associated with these effects remains unresolved. Statins are associated with mitochondrial damage, which may contribute to muscle myopathy. Here we demonstrate that simvastatin induces mitophagy in skeletal muscle cells and hypothesized that attenuating this process by silencing the mitophagy adapter p62/sequestosome-1 (SQSTM1) might mitigate myotoxicity. Surprisingly, silencing p62/SQSTM1 in differentiated C2C12 muscle cells exacerbated rather than attenuated myotoxicity. This inhibition of mitophagy in the face of statin challenge correlated with increased release of cytochrome c to the cytosol, activation of caspase-3, and lactate dehydrogenase (LDH) release. Correspondingly, targeted knockdown of Parkin, a canonical E3 ubiquitin ligase important for mitophagy, mirrored the effects of p62/SQSTM1 silencing. To corroborate these findings in vivo, we treated Parkin knockout mice with simvastatin for 2 wk. In line with our findings in vitro, these mitophagy-compromised mice displayed reduced spontaneous activity, loss of grip strength, and increased circulating levels of muscle damage marker LDH. Our findings demonstrate that mitophagy is an important mechanism to resist statin-induced skeletal muscle damage.-Ramesh, M., Campos, J. C., Lee, P., Song, Y., Hernandez, G., Sin, J., Tucker, K. C., Saadaeijahromi, H., Gurney, M., Ferreira, J. C. B., Andres, A. M. Mitophagy protects against statin-mediated skeletal muscle toxicity.

CYLD dysregulation in pathogenesis of sporadic inclusion body myositis

Sporadic inclusion body myositis (sIBM) is the most commonly acquired myopathy in middle-aged and elderly people. The muscle histology is characterized by both inflammation and degeneration, including sarcoplasmic aggregation of TDP-43. Cylindromatosis (CYLD) is a deubiquitinating enzyme that targets Lys63-linked ubiquitin chains and negatively regulates signal transduction pathways, such as NF-κB signalling pathways. We examined localization of CYLD as well as phosphorylated TDP-43, phosphorylated p62, and Lys63-linked ubiquitin in muscle tissues of sIBM patients and muscle-specific wild-type TDP-43 transgenic (TDP-43 TG) mice. We investigated whether overexpression of CYLD can affect muscle toxicity in the cell models treated by endoplasmic reticulum (ER) stress inducers tunicamycin and thapsigargin. CYLD expressed with phosphorylated TDP-43, phosphorylated p62, and Lys63-linked ubiquitin in the nuclear and perinuclear regions of muscle fibres of wild-type TDP-43 TG mice and the degenerative myofibres of sIBM patients with rimmed vacuoles and endomysial cellular infiltration. Although expression levels of CYLD decreased and cell viability was reduced in cells treated with ER stress inducers, wild-type CYLD, but not the catalytic mutant, substantially improved cell viability based on the deubiquitinase activity. Dysregulation of CYLD may reinforce myodegeneration in the pathophysiology of sIBM by attenuating autophagic clearance of protein aggregates. Regulating CYLD in muscle fibres might serve as a novel therapeutic strategy for sIBM treatment.

Chronic exposure to copper oxide nanoparticles causes muscle toxicity in adult zebrafish.

Repeated deposition of copper oxide nanoparticles (CuO-NPs) into aquatic systems makes them a global threat since the NPs accumulate in various organs of the fish particularly skeletal muscle. In the present study, adult zebrafish were exposed to different concentrations of CuO-NPs (1 and 3 mg/L) for a period of 30 days. The status of functional markers (acetylcholinesterase, creatine kinase-MB, and lactate dehydrogenase) and oxidative stress markers (oxidants and antioxidants) were analyzed. The histological changes in muscle were studied followed by the immunohistochemistry expression for catalase. Further, the expression of myoD, myogenin, pax7, β-actin, and desmin was examined by semi-quantitative reverse transcriptase polymerase chain reaction. The results indicated that chronic exposure to CuO-NPs causes muscular damage as evidenced by elevated levels of functional markers. There was a significant increase in the oxidants with reduction in the antioxidant levels, implying that the antioxidant enzymes were unable to scavenge the free radicals induced by the CuO-NPs. The histopathological analysis showed degeneration and atrophy in the treated groups confirming muscle damage. The immunohistochemical catalase expression in the muscle was reduced in the treated groups further supporting the evidence that the antioxidant has suffered a decline. The altered gene expression indicates skeletal muscle damage due to the CuO-NPs exposure. Overall, the data suggest that chronic exposure to CuO-NPs caused muscular toxicity which may lead to muscle degeneration in adult zebrafish.

Ibudilast attenuates doxorubicin‐induced cytotoxicity by suppressing formation of TRPC3 channel and NADPH oxidase 2 protein complexes

Doxorubicin is a highly effective anticancer agent but eventually induces cardiotoxicity associated with increased production of ROS. We previously reported that a pathological protein interaction between TRPC3 channels and NADPH oxidase 2 (Nox2) contributed to doxorubicin-induced cardiac atrophy in mice. Here we have investigated the effects of ibudilast, a drug already approved for clinical use and known to block doxorubicin-induced cytotoxicity, on the TRPC3-Nox2 complex. We specifically sought evidence that this drug attenuated doxorubicin-induced systemic tissue wasting in mice. We used the RAW264.7 macrophage cell line to screen 1,271 clinically approved chemical compounds, evaluating functional interactions between TRPC3 channels and Nox2, by measuring Nox2 protein stability and ROS production, with and without exposure to doxorubicin. In male C57BL/6 mice, samples of cardiac and gastrocnemius muscle were taken and analysed with morphometric, immunohistochemical, RT-PCR and western blot methods. In the passive smoking model, cells were exposed to DMEM containing cigarette sidestream smoke. Ibudilast, an anti-asthmatic drug, attenuated ROS-mediated muscle toxicity induced by doxorubicin treatment or passive smoking, by inhibiting the functional interactions between TRPC3 channels and Nox2, without reducing TRPC3 channel activity. These results indicate a common mechanism underlying induction of systemic tissue wasting by doxorubicin. They also suggest that ibudilast could be repurposed to prevent muscle toxicity caused by anticancer drugs or passive smoking.

Analysis of secondary care data to evaluate the clinical relevance of the drug-drug interaction between amlodipine and simvastatin

BackgroundPharmacokinetic analyses revealed an increase in the bioavailability of simvastatin when co-administered with amlodipine [Nishio S et al. Hypertensin research 2005; Son H et al. Drug metabolism and pharmacokinetics 2014]. This may induce an increased risk of muscle toxicity for patients who receive this combination. So far, no in vivo data on the clinical relevance of this interaction exist. The objective of the present analysis was to determine the number of patients with concomitant treatment of amlodipine and simvastatin. Subsequently, the data was analyzed for the indication of muscular discomfort. Patients with combined prescription of amlodipine and another hydroxymethylglutaryl-CoA-reductase inhibitor except simvastatin or patients receiving simvastatin without amlodipine served as control groups. MethodsThe present analysis used secondary data from the health insurance company AOK PLUS including information regarding diagnosis and drug prescriptions. ResultsIn total, 67.081 patients corresponding to 4.93% of the analyzed collective received a combined prescription of amlodipine and simvastatin. The absolute frequency increased continuously over time. Muscular discomfort was detected in a) 6.20% of the patients receiving amlodipine and simvastatin, b) 6.60% of the patients receiving amlodipine and another hydroxymethylglutaryl-CoA- reductase inhibitor and c) 8.04% of the patients with simvastatin only. ConclusionsThe present analysis shows an increasing trend of combined prescriptions of amlodipine and simvastatin. Evidence for simvastatin dose adaptation or therapy switch to another hydroxymethylglutaryl-CoA-reductase inhibitor, however, was not found. Muscular discomfort does not occur more often in patients with amlodipine and simvastatin compared to the two control groups. The results of the present analysis reveal no evidence for a clinically relevant interaction between amlodipine and simvastatin.

The effects of crizotinib in a transgenic Drosophila model expressing the human TPM4-ALK fusion gene or TPM4.

ABSTRACTAnaplastic lymphoma kinase (ALK) fusion events lead to constitutive activation of the ALK kinase domain, thereby functioning as oncogenic drivers. These fusion proteins have been identified in numerous cancers. Crizotinib, a small molecule inhibitor of c-Met and ALK, is a Food and Drug Administration-approved drug with reported efficacy in the treatment of cancer. Tropomyosins (TPMs) are a family of actin filament-binding proteins. Altered TPM expression has been found in a variety of human tumors. Inhibitors of cancer-associated TPMs and actin-targeting compounds have been developed, but anti-actin agents have cardiac and respiratory muscle toxicities. In this study, we investigated the sensitivities of human TPM4 (hTPM4), human ALK (hALK), and their fusion gene (hTPM4-hALK) to crizotinib by measuring the lifespan of transgenic Drosophila. Flies overexpressing hTPM4-hALK, hTPM4 and hALK showed decreased lifespans compared with controls. Although crizotinib is an inhibitor of ALK, treatment with crizotinib significantly extended the lifespans of Drosophila expressing hTPM4 and hTPM4-hALK but had no effect on hALK-expressing flies. Autophosphorylation of Tyr1278 is necessary for full activation of the ALK domain. We confirmed that hTPM4-hALK was phosphorylated at Tyr1278 in a ligand-independent manner, and hTPM4-hALK-expressing flies treated with crizotinib showed a decreased level of Tyr1278 phosphorylation compared with untreated hTPM4-hALK-expressing flies, with a greater decrease induced by 1 µM compared with 200 nM crizotinib. Taken together, the results suggest that crizotinib is effective for treating ALK-driven cancer and might be a new therapeutic drug, without cardiac or respiratory muscle toxic effects, for TPM4-expressing cancers.