Angiotensin II Type I Receptor Antagonism Attenuates Nicotine-Induced Cardiac Remodeling, Dysfunction, and Aggravation of Myocardial Ischemia-Reperfusion Injury in Rats

Cardiovascular complications are resolved by tuna protein hydrolysate supplementation in rats fed with a high-fat diet

This study is aimed to investigate whether tuna protein hydrolysate (TPH) supplementation could alleviate cardiovascular complications induced by a high-fat diet (HFD) in rats. Rats were fed a HFD for 16 weeks and given TPH (100 mg/kg, 300 mg/kg, or 500 mg/kg) or metformin (100 mg/kg) (n = 8) for the last four weeks. TPH had the following effects: resolved their impaired glucose tolerance, hyperglycemia, dyslipidemia, obesity, and hypertension (p < 0.05); alleviated left ventricular dysfunction and hypertrophy (p < 0.05), and vascular dysfunction and hypertrophy (p < 0.05); adipocyte hypertrophy; increases in circulating leptin and tumor necrosis factor (TNF-α) were mitigated (p < 0.05); increased renin-angiotensin system (RAS), oxidative stress, and decreased nitric oxide metabolites were modulated (p < 0.05). TPH restored the expression of angiotensin II receptor type 1 (AT1R)/NADPH oxidase 2 (NOX2), endothelial nitric oxide synthase (eNOS), nuclear factor erythroid 2-related factor (Nrf2)/heme oxygenase-1 (HO-1), and peroxisome proliferator-activated receptor γ (PPARγ)/the nuclear factor kappa B (NF-κB) protein in cardiovascular tissue (p < 0.05). In metabolic syndrome (MS) rats, metformin and TPH had comparable effects. In conclusion, TPH alleviated cardiovascular complications related to MS. It suppressed RAS, oxidative stress, and inflammation that were associated with modulation of AT1R/NOX2, eNOS, Nrf2/HO-1, and PPARγ/NF-κB expression.

The controversial effect of smoking and nicotine in SARS-CoV-2 infection

The effects of nicotine and cigarette smoke in many diseases, notably COVID-19 infection, are being debated more frequently. The current basic data for COVID-19 is increasing and indicating the higher risk of COVID-19 infections in smokers due to the overexpression of corresponding host receptors to viral entry. However, current multi-national epidemiological reports indicate a lower incidence of COVID-19 disease in smokers. Current data indicates that smokers are more susceptible to some diseases and more protective of some other. Interestingly, nicotine is also reported to play a dual role, being both inflammatory and anti-inflammatory. In the present study, we tried to investigate the effect of pure nicotine on various cells involved in COVID-19 infection. We followed an organ-based systematic approach to decipher the effect of nicotine in damaged organs corresponding to COVID-19 pathogenesis (12 related diseases). Considering that the effects of nicotine and cigarette smoke are different from each other, it is necessary to be careful in generalizing the effects of nicotine and cigarette to each other in the conducted researches. The generalization and the undifferentiation of nicotine from smoke is a significant bias. Moreover, different doses of nicotine stimulate different effects (dose-dependent response). In addition to further assessing the role of nicotine in COVID-19 infection and any other cases, a clever assessment of underlying diseases should also be considered to achieve a guideline for health providers and a personalized approach to treatment.

Nicotine exposure exacerbates silica-induced pulmonary fibrosis via STAT3-BDNF-TrkB-mediated epithelial-mesenchymal transition in alveolar type II cells

The addictive substance nicotine, found in cigarettes and some e-cigarettes, plays a vital role in pro-inflammatory and fibrotic processes. However, the part played by nicotine in the progression of silica-induced pulmonary fibrosis is poorly understood. We used mice exposed to both silica and nicotine to investigate whether nicotine synergizes with silica particles to worsen lung fibrosis. The results revealed that nicotine accelerated the development of pulmonary fibrosis in silica-injured mice by activating STAT3-BDNF-TrkB signalling. Mice with a history of exposure to nicotine showed an increase in Fgf7 expression and alveolar type II cell proliferation if they were also exposed to silica. However, newborn AT2 cells could not regenerate the alveolar structure and release pro-fibrotic factor IL-33. Moreover, activated TrkB induced the expression of p-AKT, which promotes the expression of epithelial-mesenchymal transcription factor Twist, but no Snail. In vitro assessment confirmed activation of the STAT3-BDNF-TrkB pathway in AT2 cells, exposed to nicotine plus silica. In addition, TrkB inhibitor K252a downregulated p-TrkB and the downstream p-AKT and restricted the epithelial-mesenchymal transition caused by nicotine plus silica. In conclusion, nicotine activates the STAT3-BDNF-TrkB pathway, which promotes epithelial-mesenchymal transition and exacerbates pulmonary fibrosis in mice with combined exposure to silica particles and nicotine.

Acacetin alleviates myocardial ischaemia/reperfusion injury by inhibiting oxidative stress and apoptosis via the Nrf-2/HO-1 pathway

CONTEXT

Acacetin is a natural source of flavonoids with anti-inflammatory and antioxidant effects.

OBJECTIVE

This study determines acacetin's protective effect and mechanism on myocardial ischaemia/reperfusion (I/R) injury.

MATERIALS AND METHODS

Sprague-Dawley rats were divided into sham and I/R injury and treatment with acacetin. Acacetin (10 mg/kg) was subcutaneously injected for 7 days. ECG and echocardiography were conducted to determine arrhythmia and heart function. The pathological characters of the heart were determined with triphenyl tetrazolium chloride staining, Haematoxylin & Eosin staining, and Masson staining. Expression of proteins in infarct tissues was examined with western blots.

RESULTS

Administrated with acacetin in I/R rats significantly reduced the arrhythmia score from 4.90 to 2.50 and the reperfusion arrhythmia score from 3.79 to 1.82 in the vehicle or the acacetin group, respectively. LVEF was improved from 33.5% in the I/R group to 43.7% in the acacetin group, LVFS was increased from 16.4% to 24.5%, LVIDs was decreased from 6.5 to 5.3 mm. The inflammatory cell infiltration, myocardial fibrosis, and collagen 1 and 3 were reduced by acacetin. Acacetin promoted SOD and decreased MDA. In myocardial tissues, the expression level of TLR4 and IL-6 were restrained, and IL-10 was promoted. Apoptotic protein Bax was suppressed, and anti-apoptotic protein Bcl-2 was promoted in the acacetin group. Interestingly, the transcription factor Nrf-2/HO-1 pathway was also reversed by acacetin.

DISCUSSION AND CONCLUSION

Our findings indicated that acacetin has a potential therapeutic effect in clinical application on treating I/R-induced heart injury.

Nicotine and novel tobacco products drive adverse cardiac remodeling and dysfunction in preclinical studies

Background

The heart undergoes structural and functional changes in response to injury and hemodynamic stress known as cardiac remodeling. Cardiac remodeling often decompensates causing dysfunction and heart failure (HF). Cardiac remodeling and dysfunction are significantly associated with cigarette smoking. Although cigarette smoking has declined, the roles of nicotine and novel tobacco products (including electronic cigarettes and heat-not-burn tobacco) in cardiac remodeling are unclear. In this perspective, we present evidence demonstrating maladaptive cardiac remodeling in nicotine-exposed mice undergoing hemodynamic stress with angiotensin (Ang)-II infusion and review preclinical literature linking nicotine and novel tobacco products with cardiac remodeling and dysfunction.

Methods

Adult, male C57BL/6J mice were exposed to room air or chronic, inhaled nicotine for 8 weeks. A subset of mice was infused with Ang-II via subcutaneous osmotic mini-pumps during the final 4 weeks of exposure. Left ventricular structure and function were assessed with echocardiography.

Results

Chronic, inhaled nicotine abrogated Ang-II-induced thickening of the left ventricular posterior wall, leading to reduced relative wall thickness. Ang-II infusion was associated with increased left ventricular mass index in both air- and nicotine-exposed mice.

Conclusions

These changes suggest a phenotypic shift from concentric hypertrophy to eccentric hypertrophy in nicotine-exposed, hemodynamically-stressed mice which could drive HF pathogenesis. These findings join a growing body of animal studies demonstrating cardiac remodeling and dysfunction following nicotine and electronic cigarette exposure. Further exploration is necessary; however, clinicians and researchers should not overlook these emerging products as potential risk factors in the pathogenesis of cardiac remodeling and associated diseases including HF.

Sacubitril/valsartan attenuates myocardial ischemia/reperfusion injury via inhibition of the GSK3β/NF-κB pathway in cardiomyocytes

In ischemia/reperfusion (I/R) injury, both inflammation and apoptosis play a vital role, and the inhibition of excessive inflammation and apoptosis show substantial clinical potential in the treatment of I/R disease. The role of sacubitril/valsartan (SAC/VAL)-a first-in-class angiotensin receptor-neprilysin inhibitor (ARNI)-in inflammation regulation and apoptosis in the context of I/R injury needs to be further explored. In this study, we investigate the short- and long-term effects of SAC/VAL administration in treating adult murine I/R injury both in vivo and in vitro. Our results verified that the application of SAC/VAL could reduce infarct size and suppress apoptosis and the inflammatory response in the acute phase post I/R. Long-term application of SAC/VAL for four weeks significantly improved ventricular function and reversed pathological ventricular remodeling. Mechanistically, SAC/VAL treatment induces the inhibition of the GSK3β-mediated NF-κB pathway through synergistically blocking angiotensin 1 receptor (AT1R) and activating natriuretic peptide receptor (NPR). In summary, we reported the therapeutic role of SAC/VAL in regulating the GSK3β/NF-κB signaling pathway to suppress the inflammatory response and apoptosis, thereby reducing cardiac dysfunction and remodeling post I/R.

Harmful Impact of Tobacco Smoking and Alcohol Consumption on the Atrial Myocardium

Tobacco smoking and alcohol consumption are widespread exposures that are legal and socially accepted in many societies. Both have been widely recognized as important risk factors for diseases in all vital organ systems including cardiovascular diseases, and with clinical manifestations that are associated with atrial dysfunction, so-called atrial cardiomyopathy, especially atrial fibrillation and stroke. The pathogenesis of atrial cardiomyopathy, atrial fibrillation, and stroke in context with smoking and alcohol consumption is complex and multifactorial, involving pathophysiological mechanisms, environmental, and societal aspects. This narrative review summarizes the current literature regarding alterations in the atrial myocardium that is associated with smoking and alcohol.

Cannabidiol-mediated RISK PI3K/AKT and MAPK/ERK pathways decreasing reperfusion myocardial damage

Myocardial ischemia continues to be the first cause of morbimortality in the world; the definitive treatment is reperfusion; however, this action causes additional damage to ischemic myocardial tissue; this forces to seek therapies of cardioprotection to reduce this additional damage. There are many cardioprotective agents; within these, cannabinoids have shown to have beneficial effects, mainly cannabidiol (CBD). CBD is a non psychoactive cannabinoid. To evaluate the effect in experimental models of CBD in myocardial ischemia reperfusion in rats, twelve-week-old male rats have been used. The animals were divides in 3 groups: control(C), ischemia reperfusion (IR) and CBD pretreatment (1/day/5mg/kg /10days). Langendorff organ isolate studies were performed, and the area of infarction was assessed with triphenyl tetrazolium, in addition to molecular analysis of AT1 and AT2 receptors and Akt and Erk proteins and their phosphorylated forms related to RISK pathways. It was observed that there is an improvement with the use of CBD increasing inotropism and cardiac lusitropism, improving considerably the cardiovascular functionality. These could be related to the reduction of the area of infarction and activation of the AT2 receptor and the RISK pathway with absence of activation of the AT2 receptor (these could relate the reduction of the infarct area and the restoration of cardiovascular function with the activation of the AT2 receptor and the RISK pathway with the absence of activation of the AT2 receptor). The use of cannabinoids was shown to have beneficial effects when used as a treatment for myocardial reperfusion damage.

Targeting mitochondrial reactive oxygen species-mediated oxidative stress attenuates nicotine-induced cardiac remodeling and dysfunction

Long-term nicotine intake is associated with an increased risk of myocardial damage and dysfunction. However, it remains unclear whether targeting mitochondrial reactive oxygen species (ROS) prevents nicotine-induced cardiac remodeling and dysfunction. This study investigated the effects of mitoTEMPO (a mitochondria-targeted antioxidant), and resveratrol (a sirtuin activator) , on nicotine-induced cardiac remodeling and dysfunction. Sprague–Dawley rats were administered 0.6 mg/kg nicotine daily with 0.7 mg/kg mitoTEMPO, 8 mg/kg resveratrol, or vehicle alone for 28 days. At the end of the study, rat hearts were collected to analyze the cardiac structure, mitochondrial ROS level, oxidative stress, and inflammation markers. A subset of rat hearts was perfused ex vivo to determine the cardiac function and myocardial susceptibility to ischemia–reperfusion injury. Nicotine administration significantly augmented mitochondrial ROS level, cardiomyocyte hypertrophy, fibrosis, and inflammation in rat hearts. Nicotine administration also induced left ventricular dysfunction, which was worsened by ischemia–reperfusion in isolated rat hearts. MitoTEMPO and resveratrol both significantly attenuated the adverse cardiac remodeling induced by nicotine, as well as the aggravation of postischemic ventricular dysfunction. Findings from this study show that targeting mitochondrial ROS with mitoTEMPO or resveratrol partially attenuates nicotine-induced cardiac remodeling and dysfunction.

Angiotensin II type 1 receptor mediates pulmonary hypertension and right ventricular remodeling induced by inhaled nicotine

Use of electronic cigarettes is rapidly increasing among youth and young adults, but little is known regarding the long-term cardiopulmonary health impacts of these nicotine-containing devices. Our group has previously demonstrated that chronic, inhaled nicotine induces pulmonary hypertension (PH) and right ventricular (RV) remodeling in mice. These changes were associated with upregulated RV angiotensin-converting enzyme (ACE). Angiotensin II receptor blockers (ARBs) have been shown to reverse cigarette smoking-induced PH in rats. ACE inhibitor and ARB use in a large retrospective cohort of patients with PH is associated with improved survival. Here, we utilized losartan (an ARB specific for angiotensin II type 1 receptor) to further explore nicotine-induced PH. Male C57BL/6 mice received nicotine vapor for 12 h/day, and exposure was assessed using serum cotinine to achieve levels comparable to human smokers or electronic cigarette users. Mice were exposed to nicotine for 8 wk and a subset was treated with losartan via an osmotic minipump. Cardiac function was assessed using echocardiography and catheterization. Although nicotine exposure increased angiotensin II in the RV and lung, this finding was nonsignificant. Chronic, inhaled nicotine significantly increased RV systolic pressure and RV free wall thickness versus air control. These parameters were significantly lower in mice receiving both nicotine and losartan. Nicotine significantly increased RV internal diameter, with no differences seen between the nicotine and nicotine-losartan group. Neither nicotine nor losartan affected left ventricular structure or function. These findings provide the first evidence that antagonism of the angiotensin II type 1 receptor can ameliorate chronic, inhaled nicotine-induced PH and RV remodeling.NEW & NOTEWORTHY Chronic, inhaled nicotine causes pulmonary hypertension and right ventricular remodeling in mice. Treatment with losartan, an angiotensin II type 1 receptor antagonist, ameliorates nicotine-induced pulmonary hypertension and right ventricular remodeling. This novel finding provides preclinical evidence for the use of renin-angiotensin system-based therapies in the treatment of pulmonary hypertension, particularly in patients with a history of tobacco-product use.

S-allylcysteine improves ischemia/reperfusion alteration on cardiac function, antioxidant, and mitochondrial permeability

S-Allylcysteine (SAC) is an extensively studied natural product which has been proven to confer cardioprotection. This potentiates SAC into many clinical relevance possibilities, hence, the use of it ought to be optimally elucidated. To further confirm this, an ischemia/reperfusion model has been used to determine SAC at 10 mM and 50 mM on cardiac function, cardiac marker, and mitochondrial permeability. Using Langendorff setup, 24 adult male Wistar rats' hearts were isolated to be perfused with Kreb-Henseleit buffer throughout the ischemia/reperfusion method. After 20 min of stabilization, global ischemia was induced by turning off the perfusion for 35 min followed by 60 min of reperfusion with either Kreb-Henseleit buffer or SAC with the dose of 10 mM or 50 mM. The cardiac function was assessed and coronary effluent was collected at different timepoints throughout the experiment for lactate dehydrogenase (LDH) measurement. The harvested hearts were then used to measure glutathione while isolated mitochondria for mPTP analysis. SAC-reperfused hearts were shown to prevent the aggravation of cardiac function after I/R induction. It also dose-dependently upregulated glutathione reductase and glutathione level and these were also accompanied by significant reduction of LDH leakage and preserved mitochondrial permeability. Altogether, SAC dose-dependently was able to recover the post-ischemic cardiac function deterioration alongside with improvement of glutathione metabolism and mitochondrial preservation. These findings highly suggest that SAC when sufficiently supplied to the heart would be able to prevent the deleterious complications after the ischemic insult.

Acute administration of nicotine induces transient elevation of blood pressure and increases myocardial infarct size in rats

Aims

We investigated the acute effects of nicotine on myocardial infarct size, no reflow, hemodynamics and cardiac function in an acute myocardial ischemia and reperfusion infarction rat model.

Main methods

Female Sprague-Dawley rats (n = 23/group) received an intravenous loading dose of nicotine at 2.0 μg/kg/min or saline control for 30 min before starting coronary artery occlusion, then followed by a maintenance dose 0.35 μg/kg/min of nicotine to the end of 30 min occlusion and 3 h reperfusion.

Key findings

At baseline, there was no difference in systolic blood pressure (BP in mmHg) (nicotine, 69.0 ± 2.7; control, 69.3 ± 4.4; p = NS) or diastolic BP (nicotine, 45.7 ± 3.2; control, 48.2 ± 4.2; p = NS) between groups. Nicotine administration initially increased systolic BP (nicotine, 97.0 ± 8.6; control, 69.2 ± 3.3, p < 0.0001) and diastolic BP (nicotine, 65.6 ± 6.4; control, 47.4 ± 3.1, p = 0.0003) at 10 min after starting injection of the loading dose; BP dropped to control levels in both groups at 30 min. During occlusion and reperfusion, the BP and heart rate were not altered by nicotine. Nicotine significantly increased myocardial infarct size as a percentage of the ischemic risk zone compared to the controls (nicotine, 54.9 ± 1.9; control, 48.6 ± 2.7, p < 0.05), but nicotine did not affect the no-reflow size and heart function.

Significance

While acute nicotine only transiently elevated blood pressure, it did not affect hemodynamic parameters during coronary artery occlusion. Nicotine increased myocardial infarct size, suggesting that the increase in infarct size was not simply due to an increase in oxygen demand due to altered afterload, heart rate, or contractility, but may have been due to a more direct effect on the myocardium.

Etomidate alleviates cardiac dysfunction, fibrosis and oxidative stress in rats with myocardial ischemic reperfusion injury

Background

Etomidate has been shown to reduce ischemia/reperfusion (I/R) injury in several tissues. Here we aimed to investigate the protective effects of etomidate on I/R injury in Sprague-Dawley (SD) rats.

Methods

Thirty rats were randomly divided into 5 groups and pretreated with saline or 0.5/1/2 mg/kg etomidate. I/R injury was induced in all groups except the sham control group. After administration with saline or 0.5/1/2 mg/kg etomidate daily for another 27 days, rats were sacrificed and the effects of etomidate were analyzed.

Results

Treatment with etomidate dose dependently improved echocardiography indexes, ameliorated myocardial histological alterations and reduced serum creatine kinase isoenzyme (CK-MB), myoglobin (Mb) and troponin I (cTnl) levels. Fibrosis markers transforming growth factor beta (TGF-β), alpha-smooth muscle actin (α-SMA) and fibronectin was decreased with etomidate treatment. Etomidate also decreased oxidative stress and inflammation in rats, indicated by increased superoxide dismutase (SOD) and glutathione (GSH), and reduced malondialdehyde (MDA) in myocardial tissues, as well as decreased inducible NO synthase (iNOS) and increased interleukin (IL)-10 in both serum and myocardial tissues.

Conclusions

Altogether, we showed that etomidate alleviated I/R injury in rats through reduced cardiac dysfunction, fibrosis and oxidative stress. These results supported the protective role of etomidate to myocardial I/R injury.

Mitochondrial Dysfunction in Diabetic Cardiomyopathy: The Possible Therapeutic Roles of Phenolic Acids

As the powerhouse of the cells, mitochondria play a very important role in ensuring that cells continue to function. Mitochondrial dysfunction is one of the main factors contributing to the development of cardiomyopathy in diabetes mellitus. In early development of diabetic cardiomyopathy (DCM), patients present with myocardial fibrosis, dysfunctional remodeling and diastolic dysfunction, which later develop into systolic dysfunction and eventually heart failure. Cardiac mitochondrial dysfunction has been implicated in the development and progression of DCM. Thus, it is important to develop novel therapeutics in order to prevent the progression of DCM, especially by targeting mitochondrial dysfunction. To date, a number of studies have reported the potential of phenolic acids in exerting the cardioprotective effect by combating mitochondrial dysfunction, implicating its potential to be adopted in DCM therapies. Therefore, the aim of this review is to provide a concise overview of mitochondrial dysfunction in the development of DCM and the potential role of phenolic acids in combating cardiac mitochondrial dysfunction. Such information can be used for future development of phenolic acids as means of treating DCM by alleviating the cardiac mitochondrial dysfunction.

Nicotine in Senescence and Atherosclerosis

Cigarette smoke is a known exacerbator of age-related pathologies, such as cardiovascular disease (CVD), atherosclerosis, and cellular aging (senescence). However, the role of nicotine and its major metabolite cotinine is yet to be elucidated. Considering the growing amount of nicotine-containing aerosol use in recent years, the role of nicotine is a relevant public health concern. A number of recent studies and health education sites have focused on nicotine aerosol-induced adverse lung function, and neglected cardiovascular (CV) impairments and diseases. A critical review of the present scientific literature leads to the hypothesis that nicotine mediates the effects of cigarette smoke in the CV system by increasing MAPK signaling, inflammation, and oxidative stress through NADPH oxidase 1 (Nox1), to induce vascular smooth muscle cell (VSMC) senescence. The accumulation of senescent VSMCs in the lesion cap is detrimental as it increases the pathogenesis of atherosclerosis by promoting an unstable plaque phenotype. Therefore, nicotine, and most likely its metabolite cotinine, adversely influence atherosclerosis.