SIRT1 is Required for Exercise-Induced Beneficial Effects on Myocardial Ischemia/Reperfusion Injury

NAMPT inhibition relieves intestinal inflammation by regulating macrophage activation in experimental necrotizing enterocolitis

Nicotinamide phosphoribosyl transferase (NAMPT) is associated with various NAD+ -consuming enzymatic reactions. The precise role in intestinal mucosal immunity in necrotizing enterocolitis (NEC) is not well defined. Here, we examined whether NAMPT inhibition by the highly specific inhibitor FK866 could alleviate intestinal inflammation during the pathogenesis of NEC. In the present study, we showed that NAMPT expression was upregulated in the human terminal ileum of human infants with NEC. FK866 administration attenuated M1 macrophage polarization and relieved the symptoms of experimental NEC pups. FK866 inhibited intercellular NAD+ levels, macrophage M1 polarization, and the expression of NAD+ -dependent enzymes, such as poly (ADP ribose) polymerase 1 (PARP1) and Sirt6. Consistently, the capacity of macrophages to phagocytose zymosan particles, as well as antibacterial activity, were impaired by FK866, whereas NMN supplementation to restore NAD+ levels reversed the changes in phagocytosis and antibacterial activity. In conclusion, FK866 reduced intestinal macrophage infiltration and skewed macrophage polarization, which is implicated in intestinal mucosal immunity, thereby promoting the survival of NEC pups.

Exercise training and experimental myocardial ischemia and reperfusion: A systematic review and meta-analysis

Background

Despite the success of interventional coronary reperfusion strategies, morbidity and mortality from acute myocardial infarction are still substantial. Physical exercise is a well-recognized effective non-pharmacological therapy for cardiovascular diseases. Therefore, the objective of this systematic review was to analyze studies in animal models of ischemia-reperfusion in association with physical exercise protocols.

Search strategy

Articles published on the topic over a 13-year period (2010-2022) were searched in two databases (PubMed and Google Scholar) using the keywords exercise training, ischemia/reperfusion or ischemia reperfusion injury. Meta-analysis and quality assessment of the studies were performed using the Review Manager 5.3 program.

Results

From the 238 articles retrieved from PubMed and 200 from Google Scholar, after screening and eligibility assessment, 26 articles were included in the systematic review and meta-analysis. For meta-analysis comparing the group of previously exercised animals with the non-exercised animals and then submitted to ischemia-reperfusion, the infarct size was significantly decreased by exercise (p < 0.00001). In addition, the group exercised had increased heart-to-body weight ratio (p < 0.00001) and improved ejection fraction as measured by echocardiography (p < 0.0004) in comparison to non-exercised animals.

Conclusion

We concluded that the animal models of ischemia-reperfusion indicates that exercise reduce infarct size and preserve ejection fraction, associated with beneficial myocardial remodeling.

Exercise activates Sirt1-mediated Drp1 acetylation and inhibits hepatocyte apoptosis to improve nonalcoholic fatty liver disease

PURPOSE

Aerobic exercise has shown beneficial effects in the prevention and treatment of non-alcoholic fatty liver disease (NAFLD). Nevertheless, the regulatory mechanism is not turely clear. Therefore, we aim to clarify the possible mechanism by investigating the effects of aerobic exercise on NAFLD and its mitochondrial dysfunction.

METHODS

NAFLD rat model was established by feeding high fat diet. and used oleic acid (OA) to treat HepG2 cells. Changes in histopathology, lipid accumulation, apoptosis, body weight, and biochemical parameters were assessed. In addition, antioxidants, mitochondrial biogenesis and mitochondrial fusion and division were assessed.

RESULTS

The obtained in vivo results showed that aerobic exercise significantly improved lipid accumulation and mitochondrial dysfunction induced by HFD, activated the level of Sirtuins1 (Srit1), and weakened the acetylation and activity of dynamic-related protein 1 (Drp1). In vitro results showed that activation of Srit1 inhibited OA-induced apoptosis in HepG2 cells and alleviated OA-induced mitochondrial dysfunction by inhibiting Drp1 acetylation and reducing Drp1 expression.

CONCLUSION

Aerobic exercise alleviates NAFLD and its mitochondrial dysfunction by activating Srit1 to regulate Drp1 acetylation. Our study clarifies the mechanism of aerobic exercise in alleviating NAFLD and its mitochondrial dysfunction and provides a new method for adjuvant treatment of NAFLD.

Bergenin alleviates myocardial ischemia-reperfusion injury via SIRT1 signaling

Myocardial ischemia-reperfusion (MI/R) is a major risk factor for cardiovascular disease. At present, reducing oxidative stress and apoptosis is a crucial therapeutic strategy for ameliorating MI/R injury. However, there is a lack of drugs targeting oxidative stress and apoptosis for the clinical therapy of MI/R. Bergenin is a reportedly effective agent with antioxidative and antiapoptotic activity against acute injury. Nevertheless, the roles and potential mechanisms of bergenin against MI/R injury remain unknown. Here, we hypothesized that bergenin attenuated MI/R-induced apoptosis and reactive oxygen species (ROS) production via SIRT1. Mice were subjected to MI/R and treated with bergenin, after which the cardiac function, cardiomyocyte apoptosis, LDH release, and MDA content were evaluated. In vitro, myocardial injury model of H9c2 cells was induced by simulated ischemia/reperfusion (SI/R), apoptosis and oxidative stress was decreased after treated with bergenin. Bergenin significantly reduced myocardial apoptosis and ROS generation in vitro and improved cardiac function in vivo. Intriguingly, bergenin remarkably decreased apoptosis in cardiac tissue accompanied by SIRT1 upregulation following MI/R injury. Further studies showed that inhibiting SIRT1 blocked bergenin's beneficial impact against apoptosis following SI/R injury through excessive oxidative stress and depression of the Bcl2 to Bax ratio. Collectively, these findings indicate that bergenin alleviates MI/R injury by ameliorating myocardial apoptosis and oxidative damage via the SIRT1 signaling pathway.

Resistance exercise promotes the resolution and recanalization of deep venous thrombosis in a mouse model via SIRT1 upregulation

BACKGROUND

Early exercise for acute deep venous thrombosis (DVT) improves the patient's symptoms and does not increase the risk of pulmonary embolism. However, information about its effect on thrombus resolution is limited. The aim of this study was to investigate the role of resistance exercise (RE) in thrombus resolution and recanalization and determine its underlying mechanisms.  METHODS: Ninety-six C57BL/6 J mice were randomly divided into four groups: Control group (C, n = 24); DVT group (D, n = 24); RE + DVT group (ED, n = 24); and inhibitor + RE + DVT group (IED, n = 24). A DVT model was induced by stenosis of the inferior vena cava (IVC). After undergoing IVC ultrasound within 24 h post-operation to confirm DVT formation, mice without thrombosis were excluded. Other mice were sacrificed and specimens were obtained 14 or 28 days after operation. Thrombus-containing IVC was weighed, and the thrombus area and recanalization rate were calculated using HE staining. Masson's trichrome staining was used to analyze the collagen content. RT-PCR and ELISA were performed to examine IL-6, TNF-α, IL-10, and VEGF expression levels. SIRT1 expression was assessed using immunohistochemistry staining and RT-PCR. VEGF-A protein expression and CD-31-positive microvascular density (MVD) in the thrombus were observed using immunohistochemistry.  RESULTS: RE did not increase the incidence of pulmonary embolism. It reduced the weight and size of the thrombus and the collagen content. Conversely, it increased the recanalization rate. It also decreased the levels of the pro-inflammatory factors IL-6 and TNF-α and increased the expression levels of the anti-inflammatory factor IL-10. RE enhanced VEGF and SIRT1 expression levels and increased the MVD in the thrombosis area. After EX527 (SIRT1 inhibitor) was applied, the positive effects of exercise were suppressed.

CONCLUSIONS

RE can inhibit inflammatory responses, reduce collagen deposition, and increase angiogenesis in DVT mice, thereby promoting thrombus resolution and recanalization. Its underlying mechanism may be associated with the upregulation of SIRT1 expression.

Sirtuin 1-Activating Compounds: Discovery of a Class of Thiazole-Based Derivatives

Sirtuin 1 (SIRT1) is a NAD⁺-dependent deacetylase implicated in various biological and pathological processes, including cancer, diabetes, and cardiovascular diseases. In recent years, SIRT1-activating compounds have been demonstrated to exert cardioprotective effects. Therefore, this enzyme has become a feasible target to treat cardiovascular diseases, and many SIRT1 activators, of a natural or synthetic origin, have been identified. In the present work, we developed thiazole-based SIRT1 activators, which showed remarkably higher SIRT1 activation potencies compared with those of the reference compound resveratrol when tested in enzymatic assays. Thiazole 8, a representative compound of this series, was also subjected to further pharmacological investigations, where it was proven to reduce myocardial damage induced by an in vivo occlusion/reperfusion event, thus confirming its cardioprotective properties. In addition, the cardioprotective effect of compound 8 was significantly higher than that of resveratrol. Molecular modeling studies suggest the binding mode of these derivatives within SIRT1 in the presence of the p53-AMC peptide. These promising results could pave the way to further expand and optimize this chemical class of new and potent SIRT1 activators as potential cardioprotective agents.

Role of resveratrol in inhibiting pathological cardiac remodeling

Cardiovascular disease is a group of diseases with high mortality in clinic, including hypertension, coronary heart disease, cardiomyopathy, heart valve disease, heart failure, to name a few. In the development of cardiovascular diseases, pathological cardiac remodeling is the most common cardiac pathological change, which often becomes a domino to accelerate the deterioration of the disease. Therefore, inhibiting pathological cardiac remodeling may delay the occurrence and development of cardiovascular diseases and provide patients with greater long-term benefits. Resveratrol is a non-flavonoid polyphenol compound. It mainly exists in grapes, berries, peanuts and red wine, and has cardiovascular protective effects, such as anti-oxidation, inhibiting inflammatory reaction, antithrombotic, dilating blood vessels, inhibiting apoptosis and delaying atherosclerosis. At present, the research of resveratrol has made rich progress. This review aims to summarize the possible mechanism of resveratrol against pathological cardiac remodeling, in order to provide some help for the in-depth exploration of the mechanism of inhibiting pathological cardiac remodeling and the development and research of drug targets.

Cognitive decline in heart failure: Biomolecular mechanisms and benefits of exercise

By definition, heart failure (HF) is a human pathological condition affecting the structure and function of all organs in the body, and the brain is not an exception to that. Failure of the heart to pump enough blood centrally and peripherally is at the foundation of HF patients' inability to attend even the most ordinary daily activities and progressive deterioration of their cognitive capacity. What is more, between heart and brain exists a bidirectional relationship that goes well beyond hemodynamics and concerns bioelectric and endocrine signaling. This increasingly consolidated evidence makes the scenario even more complex. Studies have mainly chased how HF impairs cognition without focusing much on preventive measures, notably cardio-cerebral health proxies. Here, we aim to provide a brief account of known and hypothetical factors that may explain how exercise can help obviate cognitive dysfunction associated with HF in its different forms. As we shall see, there is a stringent need for a deeper grasp of such mechanisms. Indeed, gaining this new knowledge will automatically shed new light on the inner workings of HF itself, thus resulting in more effective prevention and treatment of this escalating syndrome.

Resveratrol, novel application by preconditioning to attenuate myocardial ischemia/reperfusion injury in mice through regulate AMPK pathway and autophagy level

Myocardial ischemia/reperfusion injury (MI/RI) is the main cause of deaths in the worldwide, leading to severe cardiac dysfunction. Resveratrol (RSV) is a polyphenol plant-derived compound. Our study aimed to elucidate the underlying molecular mechanism of preconditioning RSV in protecting against MI/RI. Mice were ligated and re-perfused by the left anterior descending branch with or without RSV (30 mg/kg·ip) for 7 days. Firstly, we found that RSV pretreatment significantly alleviated myocardial infarct size, improved cardiac function and decreased oxidative stress. Furthermore, RSV activated p-AMPK and SIRT1, ameliorated inflammation including the level of TNF-α and IL-1β, and promoting autophagy level. Moreover, neonatal rat ventricular myocytes (NRVMs) and H9c2 cells with knockdown the expression of AMPK, SIRT1 or FOXO1 were used to uncover the underlying molecular mechanism for the cardio-protection of RSV. In NRVMs, RSV increased cellular viability, decreased LDH release and reduced oxidative stress. Importantly, Compound C(CpC) and EX527 reversed the effect of RSV against MI/RI in vivo and in vitro and counteracted the autophagy level induced by RSV. Together, our study indicated that RSV could alleviate oxidative stress in cardiomyocytes through activating AMPK/SIRT1-FOXO1 signallingpathway and enhanced autophagy level, thus presenting high potential protection on MI/RI.

Nicotinamide riboside relieves the severity of experimental necrotizing enterocolitis by regulating endothelial function via eNOS deacetylation

BACKGROUND

Nicotinamide adenine dinucleotide (NAD+) is involved in regulating oxidative stress. Although NAD+ is associated with various health issues, its role in the intestinal microcirculation in necrotizing enterocolitis (NEC) remains to be confirmed. In the current study, we explored whether nicotinamide riboside (NR), a natural NAD + precursor, ameliorates the severity of NEC through endothelial nitric oxide synthase(eNOS) signaling.

METHODS

A mouse experimental NEC model was induced by formula gavage and hypoxia in full-term mouse pups. Intestinal endothelial cells (MIMECs) were isolated and subjected to stress using tumor necrosis factor (TNF)-α. NR was administered to assess the intestinal microcirculation and lipid peroxidation levels and to explore the involved signaling pathways.

RESULTS

NAD + levels were reduced after induction of NEC stress, which was associated with intestinal injury. NR administration promoted NAD + levels, attenuated oxidative stress and relieved the symptoms of experimental NEC, which were relevant to increased intestinal microcirculatory perfusion through the sirtuin (SIRT) 1 pathway in experimental NEC mice. However, this improvement was not found in eNOS-knockout mice. Consistently, MIMECs exposed to TNFα showed decreased SIRT1 activity associated with increased eNOS acetylation, which could bring about endothelial dysfunction due to limited nitric oxide production. NR administration increased the NAD + content and repressed the production of reactive oxygen species (ROS) in MIMECs under TNFα stress. NR also promoted SIRT1 activity and accordingly suppressed the eNOS acetylation levels under TNFα stress.

CONCLUSION

The current data indicate that NR administration improves the survival of experimental NEC mice via SIRT1-associated eNOS acetylation/deacetylation modulation, which is implicated in endothelial dysfunction. Although NR is commonly found in the human diet, it may also be a promising strategy for NEC treatment because of its pathogenic association with NEC.

Molecular-Signaling Pathways of Ginsenosides Rb in Myocardial Ischemia-Reperfusion Injury: A Mini Review

Reperfusion injury following myocardial ischemia remained a challenge for optimal treatment of myocardial infarction. Ginsenosides Rb (G-Rb), the primary components of ginsenoside, have been reported to exert cardioprotective effects via numerous mechanisms. G-Rb1 mediate cardioprotective effects via various signaling pathways, including mitochondrial apoptotic pathway, PI3K/Akt/mTOR, HIF-1α and GRF91, RhoA, p38α MAPK, and eNOS. G-Rb2 activates the SIRT-1 pathway, while G-Rb3 promotes both JNK-mediated NF-κB and PERK/Nrf2/HMOX1. Generally, ginsenosides Rb1, 2, and 3 modulates oxidative stress, inflammation, and apoptosis, contributing to the improvement of structural, functional and biochemical parameters. In conclusion, G-Rb, particularly G-Rb1, have vast potential as a supplement in attenuating reperfusion injury. Translation into a clinical trial is warranted to confirm the beneficial effects of G-Rb.

Possibilities of pharmacological correction of reperfusion injury of ischemic myocardium (review)

Timely and effective reperfusion in ischemia and reoxygenation in hypoxia of the heart muscle prevent myocardial infarction. Delayed reperfusion and reoxygenation in myocardial ischemia and hypoxia can cause reversible damage in it, which, with a favorable outcome, disappear without a trace. Excessively late reperfusion and reoxygenation inevitably ends with irreversible damage to the myocardium, which is widely known as a myocardial infarction, and which, together with other complications of cardiac ischemia, can cause disability and death of the patient. In recent years, reperfusion injury of the ischemic heart muscle has been recognized as an independent link in the pathogenesis of myocardial infarction. The mechanisms of this link of pathogenesis have been partially studied in experimental conditions. The phenomena of preconditioning and post-conditioning have been discovered, the effects of which are currently determined fairly reliably. After determining the mechanisms of reperfusion injury of the ischemic myocardium, the search and development of pharmacological agents capable of inducing such a phenomenon as cardioprotection began. In parallel, studies of specific microRNAs that claim to be diagnostic markers are being conducted, as well as the search for drugs that affect the level of their expression is being conducted. The information about the achieved successes in this direction is given.