Fenofibrate attenuates impaired ischemic preconditioning-mediated cardioprotection in the fructose-fed hypertriglyceridemic rat heart

The Influence of Metabolic Risk Factors on the Inflammatory Response Triggered by Myocardial Infarction: Bridging Pathophysiology to Treatment

Myocardial infarction (MI) sets off a complex inflammatory cascade that is crucial for effective cardiac healing and scar formation. Yet, if this response becomes excessive or uncontrolled, it can lead to cardiovascular complications. This review aims to provide a comprehensive overview of the tightly regulated local inflammatory response triggered in the early post-MI phase involving cardiomyocytes, (myo)fibroblasts, endothelial cells, and infiltrating immune cells. Next, we explore how the bone marrow and extramedullary hematopoiesis (such as in the spleen) contribute to sustaining immune cell supply at a cardiac level. Lastly, we discuss recent findings on how metabolic cardiovascular risk factors, including hypercholesterolemia, hypertriglyceridemia, diabetes, and hypertension, disrupt this immunological response and explore the potential modulatory effects of lifestyle habits and pharmacological interventions. Understanding how different metabolic risk factors influence the inflammatory response triggered by MI and unraveling the underlying molecular and cellular mechanisms may pave the way for developing personalized therapeutic approaches based on the patient's metabolic profile. Similarly, delving deeper into the impact of lifestyle modifications on the inflammatory response post-MI is crucial. These insights may enable the adoption of more effective strategies to manage post-MI inflammation and improve cardiovascular health outcomes in a holistic manner.

Cardioprotective Activity of Cassia fistula L. Bark Extract in Isoproterenol-Induced Myocardial Infarction Rat Model

Cassia fistula Linn, generally recognized as Indian laburnum, is one of the ancient trees in the Indian subcontinent used for its ornamental and diverse medicinal properties. It is known for its ethnic medicinal uses in inflammatory and infectious pathologies such as antihelmintic, purgative, carminative, antipyretic, expectorant, analgesic, laxative, antiseptic, and antidote against snake poison. The Cassia bark is rich in anthraquinones, flavanols glycosides, and sitosterols, which renders it cardioprotective properties. The existing experiments were designed to assess the potential of Cassia fistula bark against isoproterenol (ISP)-induced cardiotoxicity in rats, which has not been validated yet. The bark was successively extracted with five different solvents, and each extract was subjected to in vitro antioxidant studies. Further acute oral toxicity assays were carried out preceding in vivo myocardial studies. Cardiotoxicity-inducing agent, ISP, was administrated to the rats for two consecutive days (8th and 9th). Based on in vitro studies, the Cassia fistula methanolic extract (CFME) was administered in two doses: CFME-LD (lower dose 250 mg/kg) and CFME-HD (high dose 500 mg/kg) separately. It was found that CFME produced a substantial decrease in lipid peroxidation and an increase in antioxidants in myocardial tissues. CFME abrogated the levels of triglyceride and total cholesterol with a decrease in alanine transaminase (ALT) and aspartate transaminase (AST) activity in serum at both doses. 2,3,5-Triphenyltetrazolium chloride (TTC) staining and histopathology also revealed the protective effects of CFME against ISP-induced myocardial infarction. The study showed the significant role of the CFME as a strong antioxidant and cardioprotective action in ISP-induced toxicity.

Rosuvastatin and low-dose carvedilol combination protects against isoprenaline-induced myocardial infarction in rats: Role of PI3K/Akt/Nrf2/HO-1 signalling

Rosuvastatin has been shown to activate PI3K/Akt/Nrf2/HO-1 pathway, which promotes cell survival in the myocardium. This study investigated the therapeutic benefit of adding rosuvastatin to low-dose carvedilol in protection against myocardial infarction (MI). Rosuvastatin (RSV) and carvedilol (CAR) were given for 7 consecutive days with concurrent administration of two doses of isoprenaline (ISP) on 6th and 7th days to induce MI. Isoprenaline injections caused detrimental alterations in the myocardial architecture and electrocardiogram (ECG) pattern and significantly increased the infarct size, heart index and serum levels of cardiotoxicity markers compared to the control group. ISP induced oxidative damage, inflammatory and apoptotic events and downregulated PI3K/Akt/Nrf2/HO-1 signalling pathway compared to the control values. Treatment with low-dose CAR and/or RSV prevented the ECG and histopathological alterations induced by ISP, and also reduced the infarct size, heart index, serum creatine kinase-MB, cardiac troponin-I and C-reactive protein levels compared to ISP group. CAR and/or RSV treatment restored the activity of superoxide dismutase and total antioxidant capacity with a consequent reduction in lipid peroxides level. Further, they decreased the expression of nuclear factor (NF)-κB (p65) and increased the phosphorylated PI3K and Akt, which may activate the anti-apoptotic signalling as evidenced by the decreased active caspase 3 level. The combination therapy has a more significant effect in the most studied parameters than their monotherapy, which may be because of the activation of PI3K/Akt Nrf2/HO-1 pro-survival signalling pathway. This study highlights the potential benefits of combining RSV with low-dose CAR in case of MI.

Dapsone Ameliorates Isoproterenol-Induced Myocardial Infarction via Nrf2/ HO-1; TLR4/ TNF-α Signaling Pathways and the Suppression of Oxidative Stress, Inflammation, and Apoptosis in Rats

Myocardial infarction (MI) is a critical condition that can happen with high doses or rapid termination of beta blockers therapy. The study aimed to evaluate the potential anti-toxic value of DAP against isoproterenol (ISO) - induced MI. Twenty-eight male Wistar rats were used for the study. The rodents were assigned to four groups (n = 7) and the treatments were given for 12 days as follows; Group 1 (control): were administrated normal saline, Group 2 (DAP control): were administrated DAP (10 mg/kg/day IP), Group 3 (ISO group): were administrated ISO (100 mg/kg, IP on the 11th and 12th days of the experiment), and Group 4 (DAP + ISO): co-treated with DAP plus ISO. The measured parameters were cardiac malondialdehyde (MDA), reduced glutathione (GSH), total nitrite/nitrate (NOx), catalase (CAT), serum cardiac biomarkers; CK-MB, ALT, LDH, and ALK-PH. Also, interleukin-1β (IL-1β), tumor necrosis factor-alpha (TNF-α), Nuclear factor (erythroid-derived 2)-like 2 (Nrf2), heme oxygenase-1 (HO-1), toll-like receptor 4 (TLR4), caspase-3 activity, and hepatic BAX and Bcl-2 were also assessed. Also, histological examination and vimentin immuno-expressions were studied. ISO group exhibited MI as evidenced by the elevation in serum cardiac biomarkers, MDA, NOx, IL-1β, TNF-α, and caspase-3 together with the reduction in GSH, Nrf2, HO-1 levels, and a faint vimentin immuno-reaction. Histological alterations revealing distorted cardiomyocytes; vacuolation, edema, pyknosis, and fragmentation were also noticed. DAP significantly ameliorated all the examined toxicity indicators. DAP revealed efficient ameliorative actions against ISO-caused MI by marked reduction in myocardial infarct size and suppressed oxidative stress, inflammation, and apoptosis via the up-regulation of the Nrf2/HO-1; TLR4/TNF-α signaling pathways.

Hyperlipidaemia and cardioprotection: Animal models for translational studies

Hyperlipidaemia is a well-established risk factor for cardiovascular diseases and therefore, many animal model have been developed to mimic the human abnormal elevation of blood lipid levels. In parallel, extensive research for the alleviation of ischaemia/reperfusion injury has revealed that hyperlipidaemia is a major co-morbidity that attenuates the cardioprotective effect of conditioning strategies (preconditioning, postconditioning and remote conditioning) and that of pharmacological interventions by interfering with cardioprotective signalling pathways. In the present review article, we summarize the existing data on animal models of hypercholesterolaemia (total, low density and HDL abnormalities) and hypertriglyceridaemia used in ischaemia/reperfusion injury and protection from it. We also provide recommendations on preclinical animal models to be used for translations of the cardioprotective strategies into clinical practice. LINKED ARTICLES: This article is part of a themed issue on Risk factors, comorbidities, and comedications in cardioprotection. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.23/issuetoc.

A Comorbidity Model of Myocardial Ischemia/Reperfusion Injury and Hypercholesterolemia in Rat Cardiac Myocyte Cultures

Introduction

The use of comorbidity models is crucial in cardioprotective drug development. Hypercholesterolemia causes endothelial and myocardial dysfunction, as well as aggravates ischemia/reperfusion (I/R)-induced myocardial injury. Endogenous cardioprotective mechanisms against I/R are impaired in hyperlipidemic and hyperglycemic in vivo animal models. Therefore, our aim was to develop a medium throughput comorbidity cell-based test system of myocardial I/R injury, hypercholesterolemia and hyperglycemia that mimics comorbidity conditions.

Methods

Cardiac myocytes isolated from neonatal or adult rat hearts were cultured in control or in three different hypercholesterolemic media with increasing cholesterol content (hiChol) or hiChol + hyperglycemic medium, respectively. Each group was then subjected to simulated ischemia/reperfusion (SI/R) or corresponding normoxic condition, respectively. Cholesterol uptake was tested by Filipin staining in neonatal cardiac myocytes. Cell viability, total cell count and oxidative stress, i.e., total reactive oxygen species (ROS) and superoxide level were measured by fluorescent assays.

Results

Neonatal cardiac myocytes took up cholesterol from the different hiChol media at a concentration-dependent manner. In normoxia, viability of hiChol neonatal cardiac myocytes was not significantly changed, however, superoxide levels were increased as compared to vehicle. After SI/R, the viability of hiChol neonatal cardiac myocytes was decreased and total ROS level was increased as compared to vehicle. HiChol combined with hyperglycemia further aggravated cell death and oxidative stress in normoxic as well as in SI/R conditions. Viability of hiChol adult cardiac myocytes was significantly decreased and superoxide level was increased in normoxia and these changes were further aggravated by SI/R. HiChol combined with hyperglycemia further aggravated cell death, however level of oxidative stress increased only in normoxic condition.

Conclusion

HiChol rat cardiac myocytes showed reduction of cell viability and increased oxidative stress, which were further aggravated by SI/R and with additional hyperglycemia. This is the first demonstration that the combination of the current hypercholesterolemic medium and SI/R in cardiac myocytes mimics the cardiac pathology of the comorbid heart with I/R and hypercholesterolemia.

Review of a causal role of fructose-containing sugars in myocardial susceptibility to ischemia/reperfusion injury

In 2012, the World Health Organization Global Status Report on noncommunicable diseases showed that 7.4 million deaths were due to ischemic heart disease. Consequently, cardiovascular disease is a significant health burden, especially when partnered with comorbidities such as obesity, metabolic syndrome, and type 2 diabetes mellitus. Of note, these diseases can all be induced or exacerbated by diet. Carbohydrates, in particular, fructose and glucose, generally form the largest part of the human diet. Accumulating evidence from animal studies suggests that if large amounts of fructose are consumed either in isolation or in combination with glucose (fructose-containing sugars), myocardial susceptibility to ischemia/reperfusion (I/R) injury increases. However, the underlying mechanisms that predisposes the myocardium to I/R injury in the fructose model are not elucidated, and no single mechanistic pathway has been described. Based on all available data on this topic, this review describes previously investigated mechanisms and highlights 3 main mechanistic pathways whereby fructose has shown to increase myocardial susceptibility to I/R injury. These pathways include (1) increased reactive oxygen species, resulting in reduced nitric oxide synthase and coronary flow; (2) elevated plasma fatty acids and insulin, leading to increased cardiac triglyceride content and lipotoxicity; and (3) disrupted myocardial calcium handling/homeostasis. Moreover, we highlight various factors that should be taken into account when the fructose animal model is used, such as rat strain, treatment periods, and doses. We argue that failure to do so would result in erratic inferences drawn from the existing body of evidence on fructose animal models.

Interaction of risk factors, comorbidities, and comedications with ischemia/reperfusion injury and cardioprotection by preconditioning, postconditioning, and remote conditioning

Pre-, post-, and remote conditioning of the myocardium are well described adaptive responses that markedly enhance the ability of the heart to withstand a prolonged ischemia/reperfusion insult and provide therapeutic paradigms for cardioprotection. Nevertheless, more than 25 years after the discovery of ischemic preconditioning, we still do not have established cardioprotective drugs on the market. Most experimental studies on cardioprotection are still undertaken in animal models, in which ischemia/reperfusion is imposed in the absence of cardiovascular risk factors. However, ischemic heart disease in humans is a complex disorder caused by, or associated with, cardiovascular risk factors and comorbidities, including hypertension, hyperlipidemia, diabetes, insulin resistance, heart failure, altered coronary circulation, and aging. These risk factors induce fundamental alterations in cellular signaling cascades that affect the development of ischemia/reperfusion injury per se and responses to cardioprotective interventions. Moreover, some of the medications used to treat these risk factors, including statins, nitrates, and antidiabetic drugs, may impact cardioprotection by modifying cellular signaling. The aim of this article is to review the recent evidence that cardiovascular risk factors and their medication may modify the response to cardioprotective interventions. We emphasize the critical need to take into account the presence of cardiovascular risk factors and concomitant medications when designing preclinical studies for the identification and validation of cardioprotective drug targets and clinical studies. This will hopefully maximize the success rate of developing rational approaches to effective cardioprotective therapies for the majority of patients with multiple risk factors.

Protective effects of aspirin and vitamin C against corn syrup consumption-induced cardiac damage through sirtuin-1 and HIF-1α pathway

Objective:

The aim of this study was to investigate the protective effects of aspirin (AS) and vitamin C (VC) against cardiac damage induced by chronic corn syrup (CS) consumption via a mechanism involving sirtuin-1 (ST-1), hypoxia-inducible factor-1a (HIF-1a), and the caspase-3 pathway in rats.

Methods:

Forty male Sprague–Dawley rats (14–16 weeks) that weighed 250–300 g were randomly distributed into 5 groups, each containing 8 rats: control group, CS+AS group, CS+VC group, CS+AS+VC group, and CS group. AS (10 mg/kg/day) and VC (200 mg/kg/day) were orally given to the rats. F30 (30% fructose syrup solution) was given to the rats in drinking water for 6 weeks. The rats were sacrificed by exsanguination 24 h after the last administration. Blood samples and tissue were collected for biochemical, histopathological, and immunohistochemical examinations. Non-parametric Kruskal–Wallis test and Mann–Whitney U test used for the parameters without normal distribution and ANOVA and post-hoc LSD tests were used for parameters with a normal distribution to compare groups.

Results:

Uric acid, creatine kinase (CKMB), and lactate dehydrogenase (LDH) levels were increased in the CS group compared with the control group (1.45±0.39 and p=0.011; 3225.64±598.25 and p=0.004; 3906.83±1064.22 and p=0.002, respectively) and decreased in all the treatment groups. In addition, increased levels of MDA and decreased activity of CAT in the CS group (0.172±0.03 and p=0.000; 0.070±0.005 and p=0.007, respectively) were reversed with AS and VC therapy. A decrease in ST-1 activity and increases in caspase-3 and HIF-1 activities corrected by VC and AS therapy were observed.

Conclusion:

AS and VC, which display antioxidant and antiapoptotic activities, ameliorated cardiac damage induced by chronic fructose consumption by increasing the levels of ST-1 and decreasing the levels of HIF-1a and caspase-3.