Cardiac autonomic modulation induced by doxorubicin in a rodent model of colorectal cancer and the influence of fullerenol pretreatment

Versatile applications of fullerenol nanoparticles

Nanomaterials have become increasingly important over time as research technology has enabled the progressively precise study of materials at the nanoscale. Developing an understanding of how nanomaterials are produced and tuned allows scientists to utilise their unique properties for a variety of applications, many of which are already incorporated into commercial products. Fullerenol nanoparticles C60(OH)n, 2 ≤ n ≤ 44 are fullerene derivatives and are produced synthetically. They have good biocompatibility, low toxicity and no immunological reactivity. In addition, their nanometre size, large surface area to volume ratio, ability to penetrate cell membranes, adaptable surface that can be easily modified with different functional groups, drug release, high physical stability in biological media, ability to remove free radicals, magnetic and optical properties make them desirable candidates for various applications. This review comprehensively summarises the various applications of fullerenol nanoparticles in different scientific fields such as nanobiomedicine, including antibacterial and antiviral agents, and provides an overview of their use in agriculture and biosensor technology. Recommendations are also made for future research that would further elucidate the mechanisms of fullerenols actions.

A potent multifunctional ZIF-8 nanoplatform developed for colorectal cancer therapy by triple-delivery of chemo/radio/targeted therapy agents

BACKGROUND

Multimodal cancer therapy has garnered significant interest due to its ability to target tumor cells from various perspectives. The advancement of novel nano-delivery platforms represents a promising approach for improving treatment effectiveness while minimizing detrimental effects on healthy tissues.

METHODS

This study aimed to develop a multifunctional nano-delivery system capable of simultaneously delivering an anti-cancer drug, a radiosensitizer agent, and a targeting moiety (three-in-one) for the triple combination therapy of colorectal cancer (CRC). This unique nano-platform, called Apt-PEG-DOX/ZIF-8@GQD, encapsulated both doxorubicin (DOX) and graphene quantum dots (GQDs) within the zeolitic imidazolate framework-8 (ZIF-8). To enhance the safety and anti-cancer potential of the platform, heterobifunctional polyethylene glycol (PEG) and an epithelial cell adhesion molecule (EpCAM) aptamer were conjugated with the system, resulting in the formation of targeted Apt-PEG-DOX/ZIF-8@GQD NPs. The physical and chemical characteristics of Apt-PEG-DOX/ZIF-8@GQD were thoroughly examined, and its therapeutic efficacy was evaluated in combination with radiotherapy (RT) against both EpCAM-positive HT-29 and EpCAM-negative CHO cells. Furthermore, the potential of Apt-PEG-DOX/ZIF-8@GQD as a tumor-specific, radio-enhancing, non-toxic, and controllable delivery system for in vivo cancer treatment was explored using immunocompromised C57BL/6 mice bearing human HT-29 tumors.

RESULTS

The large surface area of ZIF-8 (1013 m2 g-1) enabled successful loading of DOX with an encapsulation efficiency of approximately ∼90%. The synthesis of Apt-PEG-DOX/ZIF-8@GQD resulted in uniform particles with an average diameter of 100 nm. This targeted platform exhibited rapid decomposition under acidic conditions, facilitating an on-demand release of DOX after endosomal escape. In vitro experiments revealed that the biocompatible nano-platform induced selective toxicity in HT-29 cells by enhancing X-ray absorption. Moreover, in vivo experiments demonstrated that the therapeutic efficacy of Apt-PEG-ZIF-8/DOX@GQD against HT-29 tumors was enhanced through the synergistic effects of chemotherapy, radiotherapy, and targeted therapy, with minimal side effects.

CONCLUSION

The combination of Apt-PEG-DOX/ZIF-8@GQD with RT as a multimodal therapy approach demonstrated promising potential for the targeted treatment of CRC and enhancing therapeutic effectiveness. The co-delivery of DOX and GQD using this nano-platform holds great promise for improving the outcome of CRC treatment.

Anthracycline's Effects on Heart Rate Variability in Children with Acute Lymphoblastic Leukemia: Early Toxicity Signs-Pilot Study

Anthracycline treatments are known to cause cardiotoxic long-term side effects in cancer survivors. Recently, a decrease in heart rate variability (HRV) has been identified in these patients, signaling autonomic dysfunction and altered cardiac fitness. This study aimed at evaluating changes in HRV in children treated with anthracyclines. A total of 35 pediatric patients with acute lymphoblastic leukemia were evaluated by means of a 24 h Holter ECG, at baseline and after reaching half the total cumulative dose of doxorubicin equivalent (120 mg/m2). Parameters of HRV were assessed, as well as any arrhythmic episodes, bradycardia and tachycardia percentages. The results showed a significant decrease in both time-domain and frequency-domain HRV parameters, following anthracycline treatment. The low-frequency (LF) to high-frequency (HF) parameters' ratio also displayed a significant difference (p = 0.035), suggestive of early cardiac autonomic dysfunction. Of note, none of the patients presented symptoms of heart disease or elevated troponins, and only two patients presented echocardiographic signs of diastolic dysfunction. The present study showed that cardiac autonomic nervous system regulation is compromised in children treated with anthracyclines even before reaching the total cumulative dose. Therefore, HRV parameters could be the first indicators of subclinical cardiac toxicity, making Holter ECG monitoring of the oncological patient a necessity.

Mechanisms, prevalence and management of cardiac arrhythmias in cancer patients: a comprehensive review

Recently, prognosis and survival of cancer patients has improved due to progression and refinement of cancer therapies; however, cardiovascular sequelae in this population augmented and now represent the second cause of death in oncological patients. Initially, the main issue was represented by heart failure and coronary artery disease, but a growing body of evidence has now shed light on the increased arrhythmic risk of this population, atrial fibrillation being the most frequently encountered. Awareness of arrhythmic complications of cancer and its treatments may help oncologists and cardiologists to develop targeted approaches for the management of arrhythmias in this population. In this review, we provide an updated overview of the mechanisms triggering cardiac arrhythmias in cancer patients, their prevalence and management.

Doxorubicin Dose-Dependent Impact on Physiological Balance-A Holistic Approach in a Rat Model

Doxorubicin (DOX) is commonly used in several chemotherapies to treat various cancers, but it is known to cause cardiotoxicity and cardiac symptoms. Autonomic dysfunction is thought to contribute to the cardiotoxic effects of DOX, but the specific dose required to disrupt homeostatic processes is still unclear and is influenced by numerous factors. This study aimed to investigate how the DOX dosage affects autonomic function and physiological parameters, to elucidate the neurocardiac mechanisms underlying the observed cardiovascular side effects. Wistar rats were treated with DOX for four weeks and divided into three dosing groups: DOX8 (2 mg/kg/week), DOX16 (4 mg/kg/week), and DOX20 (5 mg/kg/week). A control group received NaCl 0.9% saline (1 mL/kg/week). In an acute experiment, we recorded blood pressure (BP), electrocardiogram, heart rate (HR), and respiratory rate (RF). Baroreflex gain and chemoreflex sensitivity were calculated, and cardiac tissue was analyzed with picrosirius histochemistry to measure collagen content. Our results showed that the LF/HF ratio, indicative of autonomic activity, was altered along with hypotension and bradycardia at a cumulative DOX dose threshold of 16 mg/kg. We observed a positive correlation between DOX dose and BP, HR, urinary norepinephrine, LF/HF ratio, and fibrotic heart area. Lower LF/HF ratios were associated with high DOX doses, reflecting drug-induced impairment of autonomic control of HR. This study provides valuable insights into the dose-dependent effects of DOX on physiological parameters and the development of cardiovascular dysfunction. These findings are critical, which is important for optimizing the management and therapeutic strategies for patients undergoing DOX-based chemotherapy.

Ganoderenic acid D-loaded functionalized graphene oxide-based carrier for active targeting therapy of cervical carcinoma

Ganoderenic acid D (GAD), extracted from the Chinese herb Ganoderma lucidum, was loaded onto a graphene oxide-polyethylene glycol-anti-epidermal growth factor receptor (GO-PEG-EGFR) carrier to develop a targeting antitumor nanocomposite (GO-PEG@GAD). The carrier was fabricated from PEG and anti-EGFR aptamer modified GO. Targeting was mediated by the grafted anti-EGFR aptamer, which targets the membrane of HeLa cells. Physicochemical properties were characterized by transmission electron microscopy, dynamic light scattering, X-ray powder diffraction, and Fourier transform infrared spectroscopy. High loading content (77.3 % ± 1.08 %) and encapsulation efficiency (89.1 % ± 2.11 %) were achieved. Drug release continued for approximately 100 h. The targeting effect both in vitro and in vivo was confirmed by confocal laser scanning microscopy (CLSM) and imaging analysis system. The mass of the subcutaneous implanted tumor was significantly decreased by 27.27 ± 1.23 % after treatment with GO-PEG@GAD compared with the negative control group. Moreover, the in vivo anti-cervical carcinoma activity of this medicine was due to activation of the intrinsic mitochondrial pathway.

Potential Medical Use of Fullerenols After Two Decades of Oncology Research

Fullerenes are carbon molecules that are found in nature in various forms. They are composed of hexagonal and pentagonal rings that create closed structures. Almost 4 decades ago, fullerenes were identified in the form of C60 and C70, and following the award of the Nobel Prize in Chemistry for this discovery in 1996, many laboratories started working on their water-soluble derivatives that could be used in different industries, including pharmaceutical industries. One of the first fullerene forms that was the focus of different research groups was fullerenol, C60(OH)n (n  =  2-44). Both in-vitro and in-vivo studies have shown that polyhydroxylate fullerene derivatives can potentially be used as either antioxidative agents or cytostatics (depending on their co-administration, forms, and concentration/dose) in biological systems. The current review aimed to present a critical view of the potential applications and limitations of fullerenols in oncology, as understood from the past 2 decades of research.

Vagus nerve stimulation exerts cardioprotection against doxorubicin-induced cardiotoxicity through inhibition of programmed cell death pathways

The aberration of programmed cell death including cell death associated with autophagy/mitophagy, apoptosis, necroptosis, pyroptosis, and ferroptosis can be observed in the development and progression of doxorubicin-induced cardiotoxicity (DIC). Vagus nerve stimulation (VNS) has been shown to exert cardioprotection against cardiomyocyte death through the release of the neurotransmitter acetylcholine (ACh) under a variety of pathological conditions. However, the roles of VNS and its underlying mechanisms against DIC have never been investigated. Forty adults male Wistar rats were divided into 5 experimental groups: (i) control without VNS (CSham) group, (ii) doxorubicin (3 mg/kg/day, i.p.) without VNS (DSham) group, (iii) doxorubicin + VNS (DVNS) group, (iv) doxorubicin + VNS + mAChR antagonist (atropine; 1 mg/kg/day, ip, DVNS + Atro) group, and (v) doxorubicin + VNS + nAChR antagonist (mecamylamine; 7.5 mg/kg/day, ip, DVNS + Mec) group. Our results showed that doxorubicin insult led to left ventricular (LV) dysfunction through impaired cardiac autonomic balance, decreased mitochondrial function, imbalanced mitochondrial dynamics, and exacerbated cardiomyocyte death including autophagy/mitophagy, apoptosis, necroptosis, pyroptosis, and ferroptosis. However, VNS treatment improved cardiac mitochondrial and autonomic functions, and suppressed excessive autophagy, apoptosis, necroptosis, pyroptosis, and ferroptosis, leading to improved LV function. Consistent with this, ACh effectively improved cell viability and suppressed cell cytotoxicity in doxorubicin-treated H9c2 cells. In contrast, either inhibitors of muscarinic (mAChR) or nicotinic acetylcholine receptor (nAChR) completely abrogated the favorable effects mediated by VNS and acetylcholine. These findings suggest that VNS exerts cardioprotective effects against doxorubicin-induced cardiomyocyte death via activation of both mAChR and nAChR.

Metoprolol Mitigates Ischemic Heart Remodeling and Fibrosis by Increasing the Expression of AKAP5 in Ischemic Heart

The harm of heart failure mainly causes patients to develop dyspnea, fatigue, fluid retention, and other symptoms, which impair patients' activity tolerance and lead to a dramatic decrease in patients' quality of life. The purpose of this study was to verify whether metoprolol regulates AKAP5 expression and test the role of AKAP5 postinjury in mitigating cardiac infarction-associated tissue remodeling and fibrosis. Sprague-Dawley (SD) rats underwent coronary artery ligation (CAL), which was followed immediately with metoprolol daily. And western blot and coimmunoprecipitation experiments were performed to detect the expression of related proteins in the sham-operated group, model group, and drug-treated group. HW/BW ratio and cardiac expression of COL1 and COL3 were increased in rats following CAL compared with shams. Treatment with metoprolol postinjury was associated with a decrease in HW/BW ratio and COL1/COL3 expression compared to uncontrolled rats. CAL resulted in decreased cardiac AKAP5 expression compared to the control group, while metoprolol treatment restored levels compared to baseline shams. Cardiac expression levels of NFATc3/p-NFATc3 and GATA4 were modest at baseline and increased with injury, whereas metoprolol suppressed gene expression to below injury-associated changes. Immunoprecipitation indicated that AKAP5 could bind and regulate PP2B. In summary, we know that metoprolol alleviates ischemic cardiac remodeling and fibrosis, and the mechanism of alleviating remodeling may improve cardiac AKAP5 expression and AKAP5-PP2B interaction.

Acetylcholine receptor agonists provide cardioprotection in doxorubicin-induced cardiotoxicity via modulating muscarinic M2 and α7 nicotinic receptor expression

The balance between cardiac sympathetic and parasympathetic activities has been intricately linked to mitochondrial function, cellular oxidative status, and immunomodulation in healthy and diseased myocardium. Cardiac autonomic neuropathy, along with the associated mitochondrial and cellular dysfunction, is an important pathophysiological feature of doxorubicin-induced cardiotoxicity (DIC). We tested the hypothesis that autonomic modulation by activation of acetylcholine receptors (AChR) effectively attenuates DIC. Rats were divided into control (0.9% sodium chloride solution) and doxorubicin groups (DOX, 3 mg/kg/d, 6 doses). Rats in the DOX group were equally subdivided into 4 interventional groups and treated for 30 days: vehicle, α7 nicotinic receptor agonist (PNU: PNU-282987, 3 mg/kg/d), muscarinic receptor agonist (BET: bethanechol, 12 mg/kg/d), and combined α7nAChR and mAChR agonists group (COM). Cardiac biochemical and functional analyses were done. The results show that AChR agonists protected the heart against DIC via improving mitochondrial and cardiac function, which was accompanied by reducing mitochondrial oxidative damage, apoptosis, and inflammation. Strikingly, PNU and BET exerted cardioprotection through different molecular pathways. PNU-mediated α7nAChR activation promoted mitochondrial fusion via upregulation of Mfn1-2 and attenuated DOX-induced autophagy. Contrarily, activation of mAChR by BET attenuated mitochondrial fission and mitophagy. The in vitro experiments confirmed the cytoprotective effects of AChR activation in DOX-treated H9c2 cells without compromising the anticancer effect of DOX in cancer cells. In conclusion, α7nAChR and mAChR agonists exerted cardioprotection against DIC via rebalancing autonomic function, improving mitochondrial function, reducing oxidative stress, and decreased cardiomyocyte apoptosis and inflammation, leading to improved cardiac function.

Preventive aerobic training preserves sympathovagal function and improves DNA repair capacity of peripheral blood mononuclear cells in rats with cardiomyopathy

To evaluate the effect of preventive aerobic exercise training on sympathovagal function, cardiac function, and DNA repair capacity in a preclinical model of doxorubicin (DOX)-induced cardiomyopathy. Forty male Wistar-Kyoto rats were allocated into four groups (n = 10/group): D (DOX-treated) and C (controls) remained sedentary, and DT (DOX-trained) and CT (control-trained) performed aerobic training 4 days/week, during 4 weeks before exposure to DOX (4 mg/kg/week during 4 weeks) or saline solution. We evaluated cardiac function (echocardiography), hemodynamic and sympathovagal modulation (artery-femoral cannulation), cardiac troponin T levels, and DNA repair capacity (comet assay). Exercise training preserved ejection fraction (D: − 14.44% vs. DT: − 1.05%, p < 0.001), fractional shortening (D: − 8.96% vs. DT: − 0.27%, p = 0.025) and troponin T levels (D: 6.4 ± 3.6 vs. DT: 2.8 ± 1.7 ng/mL, p = 0.010). DOX increased heart rate variability (C: 27.7 ± 7.9 vs. D: 7.5 ± 2.2 ms², p < 0.001) and induced sympathovagal dysfunction (LF/HF, C: 0.37 ± 0.15 vs. D: 0.15 ± 0.15, p = 0.036) through exacerbation of sympathetic function (LF, C: 0.22 ± 0.01 vs. D: 0.48 ± 0.24 Hz, p = 0.019). Peripheral mononuclear blood cells of DT animals presented lower residual DNA damage (D: 43.4 ± 8.4% vs. DT: 26 ± 3.4%, p = 0.003 after 1 h). Cardioprotective effects of preventive aerobic exercise training are mediated by preservation of sympathovagal function and improvement of DNA repair capacity of peripheral blood mononuclear cells.

Choline Protects the Heart from Doxorubicin-Induced Cardiotoxicity through Vagal Activation and Nrf2/HO-1 Pathway

Choline is a precursor of the major neurotransmitter acetylcholine and has been demonstrated beneficial in diverse models of cardiovascular disease. Here, we sought to verify that choline protects the heart from DOX-induced cardiotoxicity and the underlying mechanisms. The results showed that DOX treatment decreased left ventricular ejection fraction and fractional shortening and increased serum cardiac markers and myocardial fibrosis, which were alleviated by cotreatment with choline. DOX-induced cardiotoxicity was accompanied by increases in oxidative stress, inflammation, and apoptosis, which were rectified by choline cotreatment. Levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme-oxygenase-1 (HO-1), which are antioxidant markers, were lowered by DOX and upregulated by choline. Moreover, DOX significantly decreased serum acetylcholine levels and the high-frequency component of heart rate variability and increased serum norepinephrine levels and the low-frequency component; these effects were rescued by choline administration. Interestingly, the protective effects of choline could be partially reversed by administration of the muscarinic receptor antagonist atropine. This suggests that choline might be a promising adjunct therapeutic agent to alleviate DOX-induced cardiotoxicity.

Acetylcholinesterase inhibitor ameliorates doxorubicin-induced cardiotoxicity through reducing RIP1-mediated necroptosis

Doxorubicin is an effective chemotherapeutic drug, but causes cardiotoxicity which limits its use. Oxidative stress, mitochondrial dysfunction, and inflammation are closely implicated in doxorubicin-induced cardiotoxicity (DIC). Necroptosis, a new form of programmed cell death, was also upregulated by doxorubicin, leading to cardiomyocyte death and cardiac dysfunction. Donepezil, an acetylcholinesterase inhibitor, exerted cardioprotection against various heart diseases. However, its cardioprotective effects in DIC are still unknown. We hypothesized that donepezil reduces reactive oxygen species (ROS) production, mitochondrial dysfunction, mitochondrial dynamics imbalance, necroptosis, and apoptosis in DIC rats. Male Wistar rats were assigned to receive either normal saline solution (n = 8) or doxorubicin (3 mg/kg, 6 doses, n = 16) via intraperitoneal injection. The doxorubicin-treated rats were further subdivided to receive either sterile drinking water (n = 8) or donepezil (5 mg/kg/day, p.o., n = 8) for 30 days. At the end of the experiment, the left ventricular (LV) function was determined. Serum and heart tissue were collected to evaluate histological and biochemical parameters. Doxorubicin-treated rats exhibited higher levels of inflammatory cytokines and ROS production. Doxorubicin also impaired mitochondrial function, mitochondrial dynamics balance, mitophagy, and autophagy, which culminated in apoptosis. Furthermore, doxorubicin increased necroptosis as evidenced by increased phosphorylation of receptor-interacting protein kinase 1, receptor-interacting protein kinase 3, and mixed-lineage kinase domain-like. All of these mechanisms led to LV dysfunction. Interestingly, donepezil alleviated mitochondrial injury, mitophagy, autophagy, and cardiomyocyte death, leading to improved LV function in DIC. In conclusion, donepezil attenuated DIC-induced LV dysfunction by reducing mitochondrial damage, mitophagy, autophagy, apoptosis, and necroptosis.

Cardioprotective effects of melatonin and metformin against doxorubicin-induced cardiotoxicity in rats are through preserving mitochondrial function and dynamics

Doxorubicin (Dox) is widely used in chemotherapy regimens for several malignant conditions. Unfortunately, cumulative and irreversible cardiotoxicity of Dox is the most prominent adverse effect which limits its use. Several pharmacological interventions which exert antioxidant properties, including melatonin and metformin, have demonstrated beneficial effects against various cardiac pathological conditions. However, the exact molecular mechanisms underlying their cardioprotective effects are not completely understood. We hypothesized that treatment with either melatonin or metformin provides cardioprotection against Dox-induced cardiotoxicity through mitochondrial protection. Thirty-two male Wistar rats received 6 doses of either 0.9% normal saline solution (0.9% NSS, n = 8) or Dox (3 mg/kg, i.p., n = 24). The Dox-treated rats (n = 8/group) were co-treated with: 1) Vehicle (0.9% NSS), 2) Melatonin (10 mg/kg/day), and 3) Metformin (250 mg/kg/day) for 30 consecutive days via oral gavage. Following the treatment, left ventricular (LV) function, oxidative stress, inflammation, mitochondrial function, dynamics, biogenesis and bioenergetics, mitophagy, autophagy, and apoptosis were determined. Dox induced excessive oxidative stress, inflammation, autophagy, apoptosis, reduced mitochondrial function, dynamics balance, biogenesis, and bioenergetics leading to LV dysfunction. Treatment with either melatonin or metformin exerted equal measures of cardioprotection via reducing oxidative stress, inflammation, autophagy, apoptosis, and improved mitochondrial function, dynamics balance, biogenesis, and bioenergetics in the Dox-treated rats. Melatonin and metformin exerted both anti-cancer and cardioprotective properties, suggesting they have potential roles in concomitant therapy in cancer patients receiving Dox treatment.

Recognition, Prevention, and Management of Arrhythmias and Autonomic Disorders in Cardio-Oncology: A Scientific Statement From the American Heart Association

With the advent of novel cancer therapeutics and improved screening, more patients are surviving a cancer diagnosis or living longer with advanced disease. Many of these treatments have associated cardiovascular toxicities that can manifest in both an acute and a delayed fashion. Arrhythmias are an increasingly identified complication with unique management challenges in the cancer population. The purpose of this scientific statement is to summarize the current state of knowledge regarding arrhythmia identification and treatment in patients with cancer. Atrial tachyarrhythmias, particularly atrial fibrillation, are most common, but ventricular arrhythmias, including those related to treatment-induced QT prolongation, and bradyarrhythmias can also occur. Despite increased recognition, dedicated prospective studies evaluating true incidence are lacking. Moreover, few studies have addressed appropriate prevention and treatment strategies. As such, this scientific statement serves to mobilize the cardio-oncology, electrophysiology, and oncology communities to develop clinical and scientific collaborations that will improve the care of patients with cancer who have arrhythmias.

Resistance training improves cardiac function and cardiovascular autonomic control in doxorubicin-induced cardiotoxicity

Doxorubicin (DOX) is an anticancer chemotherapy drug that is widely used in clinical practice. It is well documented that DOX impairs baroreflex responsiveness and left ventricular function and enhances sympathetic activity, cardiac sympathetic afferent reflexes and oxidative stress, which contribute to hemodynamic deterioration. Because resistance training (RT)-induced cardioprotection has been observed in other animal models, the objective of this study was to assess the effects of RT during DOX treatment on hemodynamics, arterial baroreflex, cardiac autonomic tone, left ventricular function and oxidative stress in rats with DOX-induced cardiotoxicity. Male Wistar rats were submitted to a RT protocol (3 sets of 10 repetitions, 40% of one-repetition maximum (1RM) of intensity, 3 times per week, for 8 weeks). The rats were separated into 3 groups: sedentary control, DOX sedentary (2.5 mg/kg of DOX intraperitoneal injection, once a week, for 6 weeks) and DOX + RT. After training or time control, the animals were anesthetized and 2 catheters were implanted for hemodynamic, arterial baroreflex and cardiac autonomic tone. Another group of animals was used to evaluate left ventricular function. We found that RT in DOX-treated rats decreased diastolic arterial pressure, heart rate, sympathetic tone and oxidative stress. In addition, RT increased arterial baroreflex sensitivity, vagal tone and left ventricular developed pressure in rats with DOX-induced cardiotoxicity. In summary, RT is a useful non-pharmacological strategy to attenuate DOX-induced cardiotoxicity.

Carvedilol improves heart rate variability indices, biomarkers but not cardiac nerve density in streptozotocin-induced T2DM model of diabetic cardiac autonomic neuropathy

OBJECTIVES

There has been increasing recognition of the significant relationship between the autonomic nervous system and cardiovascular sequel in diabetes mellitus (DM) patients. Diabetic cardiac autonomic neuropathy (DCAN) still poses a treatment challenge in the clinical settings despite several research interventions. This study was designed to investigate the effect of carvedilol on experimentally induced DCAN in type 2 DM rat model.

METHODS

DCAN was induced in 42 Wistar rats using high fat diet (HFD) for eight weeks, thereafter streptozotocin (STZ) at 25 mg/kg daily for five days. DCAN features were then assessed using non-invasive time and frequency varying holter electrocardiogram (ECG), invasive biomarkers, cardiac histology and cardiac nerve density.

RESULTS

Carvedilol significantly ameliorated the effects of DCAN on noradrenaline (p=0.010) and advanced glycated end products (AGEs) (p<0.0001). Similarly, carvedilol reversed the reduction in levels of antioxidants, sorbitol dehydrogenase (SD) activity (p=0.009) nerve growth factors (p<0.0001) and choline acetyl-transferase (p=0.031) following DCAN induction. Furthermore, heart rate variability (HRV) indices which were also reduced with DCAN induction were also ameliorated by carvedilol. However, carvedilol had no significant effect on cardiac neuronal dystrophy and reduced cardiac nerve densities.

CONCLUSIONS

Carvedilol improves physiological HRV indices and biomarkers but not structural lesions. Early detection of DCAN and intervention with carvedilol may prevent progression of autonomic neurologic sequel.

Caspofungin Effects on Electrocardiogram of Mice: An Evaluation of Cardiac Safety

Caspofungin is an echinocandin, exhibiting efficacy against most Candida species invasive infection. Its cardiotoxicity was reported in isolated rat heart and ventricular myocytes, but in vivo and clinical studies are insufficient. Our objective was to evaluate caspofungin in vivo cardiac effects using an efficacious dose against Candida albicans. Female Swiss mice were infected with C. albicans, and treated with caspofungin, 5 or 10 mg/kg, intraperitoneal along 5 days. Survival rate and colony-forming units (CFU) into vital organs were determined. For cardiac effects study, mice were treated with caspofungin 10 mg/kg, and electrocardiogram (ECG) signal was obtained on C. albicans-infected mice, single dose-treated, and uninfected mice treated along 5 days, both groups to measure ECG intervals. Besides, ECG was also obtained by telemetry on uninfected mice to evaluate heart rate variability (HRV) parameters. The MIC for caspofungin on the wild-type C. albicans SC5314 strain was 0.3 μg/ml, indicating the susceptible. Survival rate increased significantly in infected mice treated with caspofungin compared to mice treated with vehicle. None of the survived infected mice presented positive CFU after treatment with 10 mg/kg. C. albicans infection induced prolongation of QRS, QT, and QTc intervals; caspofungin did not alter this effect. Caspofungin induced increase of PR and an additional increase of QRS after 24 h of a single dose in infected mice. No significant alterations occurred in ECG intervals and HRV parameters of uninfected mice, after caspofungin treatment. Caspofungin showed in vivo cardiac relative safety maintaining its antifungal efficacy against C. albicans.

Current Evidence on miRNAs as Potential Theranostic Markers for Detecting Chemoresistance in Colorectal Cancer: A Systematic Review and Meta-Analysis of Preclinical and Clinical Studies

BACKGROUND

Findings from observational clinical studies examining the relationship between biomarker expression and theranosis in colorectal cancer (CRC) have been conflicting.

OBJECTIVE

We conducted this systematic review and meta-analysis to summarise the existing evidence to demonstrate the involvement of microRNAs (miRNAs) in chemoresistance and sensitivity in CRC through drug genetic pathways.

METHODS

Using PRISMA guidelines, we systematically searched PubMed and Science Direct for relevant studies that took place between 2012 and 2017. A random-effects model of meta-analysis was applied to evaluate the pooled effect size of hazard ratios (HRs) across the included studies. Cochran's Q test and the I² statistic were used to detect heterogeneity. A funnel plot was used to assess potential publication bias.

RESULTS

Of the 4700 studies found, 39 studies comprising 2822 patients with CRC met the inclusion criteria. The included studies used one or a combination of 14 chemotherapy drugs, including 5-fluorouracil and oxaliplatin. Of the 60 miRNAs, 28 were associated with chemosensitivity, 20 with chemoresistance, and one with differential expression and radiosensitivity; ten miRNAs were not associated with any impact on chemotherapy. The results outline the importance of 34 drug-regulatory pathways of chemoresistance and sensitivity in CRC. The mean effect size was 0.689 (95% confidence interval 0.428-1.110), indicating that the expression of miRNAs decreased the likelihood of death by about 32%.

CONCLUSION

Studies have consistently shown that multiple miRNAs could act as clinical predictors of chemoresistance and sensitivity. An inclusion of supplementary miRNA estimation in CRC routine practice needs to be considered to evaluate the efficacy of chemotherapy after confirming our findings with large-scale prospective cohort studies.

PROSPERO REGISTRATION NUMBER

CRD42017082196.

Loading of doxorubicin and thymoquinone with F2 gel nanofibers improves the antitumor activity and ameliorates doxorubicin-associated nephrotoxicity

AIMS

This study aimed to elucidate the benefits of nanoformulation of doxorubicin (DOX) and thymoquinone (TQ) loaded with nanofibers of poly-N-acetyl glucosamine (pGlcNAc), which is known as F2 gel, over their conventional free forms. Moreover, evaluate the role of TQ in improving chemotherapeutic effect and ameliorating nephrotoxicity of DOX.

MAIN METHODS

The drugs were loaded into F2 gel followed by measurement of physicochemical characterization. Next, MCF-7 and HEPG2 cells were treated with the prepared formulations and assessed for apoptosis alongside with cellular proliferation. Furthermore, we experimentally induced Heps liver carcinoma in mice and at the end of the treatment, mice were sacrificed and serum samples were used to assess nephrotoxicity markers; blood urea nitrogen (BUN) and creatinine. Additionally, renal tissue was used for determination of oxidative markers and antioxidant enzymes; whereas, tumor tissue was utilized to measure nuclear factor kappa B (NF-κB) and caspase 3.

KEY FINDINGS

Nanoformulation showed dramatic increase in apoptosis, caspase 3, and antioxidant enzymes; in contrast to, dramatic fall in cell viability, tumor volume, oxidative and nephrotoxicity markers, and NF-κB compared to corresponding free therapies. Combined therapy was superior in conserving the measured parameters compared to other treated groups.

SIGNIFICANCE

F2 gel loaded with DOX and TQ revealed enhanced antitumor activity with minimal toxicity. Moreover, using TQ as an adjuvant with DOX could augment its cytotoxicity and ameliorate nephrotoxicity.