Chronic SIRT1 supplementation in diabetic mice improves endothelial function by suppressing oxidative stress

Histone deacetylases and inhibitors in diabetes mellitus and its complications

Diabetes mellitus (DM) is a metabolic disorder characterized by hyperglycemia, with its prevalence linked to both genetic predisposition and environmental factors. Epigenetic modifications, particularly through histone deacetylases (HDACs), have been recognized for their significant influence on DM pathogenesis. This review focuses on the classification of HDACs, their role in DM and its complications, and the potential therapeutic applications of HDAC inhibitors. HDACs, which modulate gene expression without altering DNA sequences, are categorized into four classes with distinct functions and tissue specificity. HDAC inhibitors (HDACi) have shown efficacy in various diseases, including DM, by targeting these enzymes. The review highlights how HDACs regulate β-cell function, insulin sensitivity, and hepatic gluconeogenesis in DM, as well as their impact on diabetic cardiomyopathy, nephropathy, and retinopathy. Finally, we suggest that targeted histone modification is expected to become a key method for the treatment of diabetes and its complications. The study of HDACi offers insights into new treatment strategies for DM and its associated complications.

Oral Nanoformulations in Cardiovascular Medicine: Advances in Atherosclerosis Treatment

Atherosclerosis (AS) is the formation of atherosclerotic plaques on the walls of the arteries, causing them to narrow. If this occurs in the coronary arteries, the blood vessels may be completely blocked, resulting in myocardial infarction; if it occurs in the blood vessels of the brain, the blood vessels may be blocked, resulting in cerebral infarction, i.e., stroke. Studies have shown that the pathogenesis of atherosclerosis involves the processes of inflammation, lipid infiltration, oxidative stress, and endothelial damage, etc. SIRT, as a key factor regulating the molecular mechanisms of oxidative stress, inflammation, and aging, has an important impact on the pathogenesis of plaque formation, progression, and vulnerability. Statistics show that AS accounts for about 50 per cent of deaths in Western countries. Currently, oral medication is the mainstay of AS treatment, but its development is limited by side effects, low bioavailability and other unfavourable factors. In recent years, with the rapid development of nano-preparations, researchers have combined statins and natural product drugs within nanopreparations to improve their bioavailability. Based on this, this paper summarises the main pathogenesis of AS and also proposes new oral nanoformulations such as liposomes, nanoparticles, nanoemulsions, and nanocapsules to improve their application in the treatment of AS.

SIRT1: Harnessing multiple pathways to hinder NAFLD

Non-alcoholic fatty liver disease (NAFLD) encompasses hepatic steatosis, non-alcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma. It is the primary cause of chronic liver disorders, with a high prevalence but no approved treatment. Therefore, it is indispensable to find a trustworthy therapy for NAFLD. Recently, mounting evidence illustrates that Sirtuin 1 (SIRT1) is strongly associated with NAFLD. SIRT1 activation or overexpression attenuate NAFLD, while SIRT1 deficiency aggravates NAFLD. Besides, an array of therapeutic agents, including natural compounds, synthetic compounds, traditional Chinese medicine formula, and stem cell transplantation, alleviates NALFD via SIRT1 activation or upregulation. Mechanically, SIRT1 alleviates NAFLD by reestablishing autophagy, enhancing mitochondrial function, suppressing oxidative stress, and coordinating lipid metabolism, as well as reducing hepatocyte apoptosis and inflammation. In this review, we introduced the structure and function of SIRT1 briefly, and summarized the effect of SIRT1 on NAFLD and its mechanism, along with the application of SIRT1 agonists in treating NAFLD.

Prenatal High-Sucrose Diet Induced Vascular Dysfunction of Renal Interlobar Arteries in the Offspring via PPARγ-RXRg-ROS/Akt Signaling

SCOPE

Prenatal nutrition imbalance correlates with developmental origin of cardiovascular diseases; however whether maternal high-sucrose diet (HS) during pregnancy causes vascular damage in renal interlobar arteries (RIA) from offspring still keeps unclear.

METHODS AND RESULTS

Pregnant rats are fed with normal drinking water or 20% high-sucrose solution during the whole gestational period. Swollen mitochondria and distributed myofilaments are observed in vascular smooth muscle cells of RIA exposed to prenatal HS. Maternal HS increases phenylephrine (PE)-induced vasoconstriction in the RIA from adult offspring. NG-Nitro-l-arginine (L-Name) causes obvious vascular tension in response to PE in offspring from control group, not in HS. RNA-Seq of RIA is performed to reveal that the gene retinoid X receptor g (RXRg) is significantly decreased in the HS group, which could affect vascular function via interacting with PPARγ pathway. By preincubation of RIA with apocynin (NADPH inhibitor) or capivasertib (Akt inhibitor), the results indicate that ROS and Akt are the vital important factors to affect the vascular function of RIA exposure to prenatal HS.

CONCLUSION

Maternal HS during the pregnancy increases PE-mediated vasoconstriction of RIA from adult offspring, which is mainly related to the enhanced Akt and ROS regulated by the weakened PPARγ-RXRg.

Endothelial dysfunction in vascular complications of diabetes: a comprehensive review of mechanisms and implications

Diabetic vascular complications are prevalent and severe among diabetic patients, profoundly affecting both their quality of life and long-term prospects. These complications can be classified into macrovascular and microvascular complications. Under the impact of risk factors such as elevated blood glucose, blood pressure, and cholesterol lipids, the vascular endothelium undergoes endothelial dysfunction, characterized by increased inflammation and oxidative stress, decreased NO biosynthesis, endothelial-mesenchymal transition, senescence, and even cell death. These processes will ultimately lead to macrovascular and microvascular diseases, with macrovascular diseases mainly characterized by atherosclerosis (AS) and microvascular diseases mainly characterized by thickening of the basement membrane. It further indicates a primary contributor to the elevated morbidity and mortality observed in individuals with diabetes. In this review, we will delve into the intricate mechanisms that drive endothelial dysfunction during diabetes progression and its associated vascular complications. Furthermore, we will outline various pharmacotherapies targeting diabetic endothelial dysfunction in the hope of accelerating effective therapeutic drug discovery for early control of diabetes and its vascular complications.

Ningxin-Tongyu-Zishen formula alleviates the senescence of granulosa cells on D-galactose-induced premature ovarian insufficiency mice

Ningxin-Tongyu-Zishen formula (NTZF) is a clinical experience formula for the treatment of premature ovarian insufficiency (POI) in traditional Chinese medicine (TCM), and the potential mechanism is unknown. For in vivo experiments, POI mouse models (C57BL/6 mice), were constructed by subcutaneous injection of D-galactose (D-gal, 200 mg/kg). After treatment of NTZF (10.14, 20.27, 40.54 g/kg;) or estradiol valerate (0.15 mg/kg), ovarian function, oxidative stress (OS) and protein expression of Sirt1/p53 were evaluated. For in vitro experiments, H2O2 (200 μM) was used to treat KGN to construct ovarian granulosa cells (OGCs) cell senescence model. Pretreatment with NTZF (1.06 mg/mL) or p53 inhibitor (Pifithrin-α, 1 μM) was performed before induction of senescence, and further evaluated the cell senescence, OS, mRNA and protein expression of Sirt1/p53. In vivo, NTZF improved ovarian function, alleviated OS and Sirt1/p53 signaling abnormalities in POI mice. In vitro experiments showed that NTZF reduced the level of OS and alleviated the senescence of H2O2-induced KGN. In addition, NTZF activated the protein expression of Sirt1, inhibited the mRNA transcription and protein expression of p53 and p21. Alleviating OGCs senescence and protecting ovarian function through Sirt1/p53 is one of the potential mechanisms of NTZF in the treatment of POI.

Hyperuricemia and Gout Reduction by SGLT2 Inhibitors in Diabetes and Heart Failure: JACC Review Topic of the Week

Gout is characterized by increased production of purines (through the pentose phosphate pathway), which is coupled with reduced renal or intestinal excretion of urate. Concurrent upregulation of nutrient surplus signaling (mammalian target of rapamycin and hypoxia-inducible factor-1a) and downregulation of nutrient deprivation signaling (sirtuin-1 and adenosine monophosphate-activated protein kinase) redirects glucose toward anabolic pathways (rather than adenosine triphosphate production), thus promoting heightened oxidative stress and cardiomyocyte and proximal tubular dysfunction, leading to cardiomyopathy and kidney disease. Hyperuricemia is a marker (rather than a driver) of these cellular stresses. By inducing a state of starvation mimicry in a state of nutrient surplus, sodium-glucose cotransporter-2 inhibitors decrease flux through the pentose phosphate pathway (thereby attenuating purine and urate synthesis) while promoting renal urate excretion. These convergent actions exert a meaningful effect to lower serum uric acid by ≈0.6 to 1.5 mg/dL and to reduce the risk of gout by 30% to 50% in large-scale clinical trials.

Sophocarpine alleviates doxorubicin-induced heart injury by suppressing oxidative stress and apoptosis

Doxorubicin (DOX) is an effective anti-tumor drug accompanied with many side effects, especially heart injury. To explore what effects of sophocarpine (SOP) on DOX-induced heart injury, this study conducted in vivo experiment and in vitro experiment, and the C57BL/6J mice and the H9C2 cells were used. The experimental methods used included echocardiography, enzyme-linked immunosorbent assay (ELISA), dihydroethidium (DHE) staining, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining, western blotting and so on. Echocardiography showed that SOP alleviated DOX-induced cardiac dysfunction, as evidenced by the improvements of left ventricle ejection fraction and left ventricle fractional shortening. DOX caused upregulations of creatine kinase (CK), creatine kinase-MB (CK-MB) and lactate dehydrogenase (LDH), while SOP reduced these indices. The relevant stainings showed that SOP reversed the increases of total superoxide level induced by DOX. DOX also contribute to a higher level of MDA and lower levels of SOD and GSH, but these changes were suppressed by SOP. DOX increased the pro-oxidative protein level of NOX-4 while decreased the anti-oxidative protein level of SOD-2, but SOP reversed these effects. In addition, this study further discovered that SOP inhibited the decreases of Nrf2 and HO-1 levels induced by DOX. The TUNEL staining revealed that SOP reduced the high degree of apoptosis induced by DOX. Besides, pro-apoptosis proteins like Bax, cleaved-caspase-3 and cytochrome-c upregulated while anti-apoptosis protein like Bcl-2 downregulated when challenged by DOX, but them were suppressed by SOP. These findings suggested that SOP could alleviate DOX-induced heart injury by suppressing oxidative stress and apoptosis, with molecular mechanism activating of the Nrf2/HO-1 signaling pathway.

Treatment with recombinant Sirt1 rewires the cardiac lipidome and rescues diabetes-related metabolic cardiomyopathy

BACKGROUND

Metabolic cardiomyopathy (MCM), characterized by intramyocardial lipid accumulation, drives the progression to heart failure with preserved ejection fraction (HFpEF). Although evidence suggests that the mammalian silent information regulator 1 (Sirt1) orchestrates myocardial lipid metabolism, it is unknown whether its exogenous administration could avoid MCM onset. We investigated whether chronic treatment with recombinant Sirt1 (rSirt1) could halt MCM progression.

METHODS

db/db mice, an established model of MCM, were supplemented with intraperitoneal rSirt1 or vehicle for 4 weeks and compared with their db/ + heterozygous littermates. At the end of treatment, cardiac function was assessed by cardiac ultrasound and left ventricular samples were collected and processed for molecular analysis. Transcriptional changes were evaluated using a custom PCR array. Lipidomic analysis was performed by mass spectrometry. H9c2 cardiomyocytes exposed to hyperglycaemia and treated with rSirt1 were used as in vitro model of MCM to investigate the ability of rSirt1 to directly target cardiomyocytes and modulate malondialdehyde levels and caspase 3 activity. Myocardial samples from diabetic and nondiabetic patients were analysed to explore Sirt1 expression levels and signaling pathways.

RESULTS

rSirt1 treatment restored cardiac Sirt1 levels and preserved cardiac performance by improving left ventricular ejection fraction, fractional shortening and diastolic function (E/A ratio). In left ventricular samples from rSirt1-treated db/db mice, rSirt1 modulated the cardiac lipidome: medium and long-chain triacylglycerols, long-chain triacylglycerols, and triacylglycerols containing only saturated fatty acids were reduced, while those containing docosahexaenoic acid were increased. Mechanistically, several genes involved in lipid trafficking, metabolism and inflammation, such as Cd36, Acox3, Pparg, Ncoa3, and Ppara were downregulated by rSirt1 both in vitro and in vivo. In humans, reduced cardiac expression levels of Sirt1 were associated with higher intramyocardial triacylglycerols and PPARG-related genes.

CONCLUSIONS

In the db/db mouse model of MCM, chronic exogenous rSirt1 supplementation rescued cardiac function. This was associated with a modulation of the myocardial lipidome and a downregulation of genes involved in lipid metabolism, trafficking, inflammation, and PPARG signaling. These findings were confirmed in the human diabetic myocardium. Treatments that increase Sirt1 levels may represent a promising strategy to prevent myocardial lipid abnormalities and MCM development.