Resveratrol protects HUVECs from oxidized-LDL induced oxidative damage by autophagy upregulation via the AMPK/SIRT1 pathway. Cardiovasc Drugs Ther. 2013;27:189-198. [PMID: 23358928 DOI: 10.1007/s10557-013-6442-4]

Curcumin and Resveratrol: Nutraceuticals with so Much Potential for Pseudoachondroplasia and Other ER-Stress Conditions

Natural products with health benefits, nutraceuticals, have shown considerable promise in many studies; however, this potential has yet to translate into widespread clinical use for any condition. Notably, many drugs currently on the market, including the first analgesic aspirin, are derived from plant extracts, emphasizing the historical significance of natural products in drug development. Curcumin and resveratrol, well-studied nutraceuticals, have excellent safety profiles with relatively mild side effects. Their long history of safe use and the natural origins of numerous drugs contrast with the unfavorable reputation associated with nutraceuticals. This review aims to explore the nutraceutical potential for treating pseudoachondroplasia, a rare dwarfing condition, by relating the mechanisms of action of curcumin and resveratrol to molecular pathology. Specifically, we will examine the curcumin and resveratrol mechanisms of action related to endoplasmic reticulum stress, inflammation, oxidative stress, cartilage health, and pain. Additionally, the barriers to the effective use of nutraceuticals will be discussed. These challenges include poor bioavailability, variations in content and purity that lead to inconsistent results in clinical trials, as well as prevailing perceptions among both the public and medical professionals. Addressing these hurdles is crucial to realizing the full therapeutic potential of nutraceuticals in the context of pseudoachondroplasia and other health conditions that might benefit.

Effects of Dichlorvos on cardiac cells: Toxicity and molecular mechanism of action

In this study we aimed to understand the underlying mechanism of Dichlorvos-induced toxicity in cardiac cells. For this end, cells were treated by 170 μM of Dichlorvos (DDVP) (corresponding to the IC50) and molecular events were monitored by flow cytometry and western blotting. We have first demonstrated that cell exposure to DDVP for 24 h induced cell death by necroptosis. In fact, cell treatment with DDVP upregulated RIP1 expression and we have shown that chemical inhibition of RIP1 kinase activity by necrostatin-1 (Nec-1) greatly prevented from the induced cell death. Besides, we have demonstrated that, while there was no observed cell death following short exposure to DDVP (6 h), autophagy was enhanced, as proven by the increase in the level of both Beclin-1 and LC3-II and the accumulation of the CytoID® autophagy detection probe. Besides, when autophagy was inhibited by chloroquine (CQ) the percentage of necroptosis was significantly increased, suggesting that autophagy acts to protect cardiac cells against the toxicity induced by this pesticide. Concurrently, we have shown that the inhibition of the deacetylase sirtuin 1 (SIRT1) by EX527 or its knockdown by siRNA significantly increased DDVP-induced necroptosis, whereas when SIRT1 was activated by resveratrol (RSV) a significant decrease in DDVP-induced cell death was observed. In addition, we revealed that when the autophagy was inhibited by CQ, we can't reveal the protective effect of RSV anymore. Altogether, these results suggest that activation of SIRT1 protects cardiac cells from the toxicity of DDVP through an autophagy-dependent pathway.

Nobiletin and xanthohumol counteract the TNFα-mediated activation of endothelial cells through the inhibition of the NF-κB signaling pathway

Angiogenesis, a process characterized by the formation of new blood vessels from pre-existing ones, is a crucial step in tumor growth and dissemination. Given the ability of tumors to interfere with multiple or different molecular pathways to promote angiogenesis, there is an increasing need to therapeutically block tumor progression by targeting multiple antiangiogenic pathways. Natural polyphenols present health-protective properties, which are likely attributed to their ability to activate multiple pathways involved in inflammation, carcinogenesis, and angiogenesis. Recently, increased attention has been addressed to the ability of flavonoids, the most abundant polyphenols in the diet, to prevent cancer by suppressing angiogenesis. Here we investigate the mechanisms by which xanthohumol (the major prenylated flavonoid of the hop plant Humulus lupulus L.) and nobiletin (flavonoid from red-orange Citrus sinensis) can modulate the effects of Tumor Necrosis Factor-α (TNF-α) on human umbilical vein endothelial cells (HUVEC). The results reported in this paper show that xanthohumol and nobiletin pretreatment of HUVEC inhibits the effects induced by TNF-α on cell migration, invasion capability, and colon cancer cell adhesion on the endothelial monolayer. Moreover, the pretreatment reduces metalloproteinases and adhesion molecules' expression. Finally, our results highlight that xanthohumol and nobiletin can counteract the effects of TNF-α on angiogenesis and invasiveness, mainly through Vascular Endothelial Growth Factor and NF-κB pathways. Since angiogenesis plays an important pathological role in the progression of several diseases, our findings may provide clues for developing xanthohumol and nobiletin as therapeutic agents against angiogenesis-associated diseases.

The sirtuin family in health and disease

Sirtuins (SIRTs) are nicotine adenine dinucleotide(+)-dependent histone deacetylases regulating critical signaling pathways in prokaryotes and eukaryotes, and are involved in numerous biological processes. Currently, seven mammalian homologs of yeast Sir2 named SIRT1 to SIRT7 have been identified. Increasing evidence has suggested the vital roles of seven members of the SIRT family in health and disease conditions. Notably, this protein family plays a variety of important roles in cellular biology such as inflammation, metabolism, oxidative stress, and apoptosis, etc., thus, it is considered a potential therapeutic target for different kinds of pathologies including cancer, cardiovascular disease, respiratory disease, and other conditions. Moreover, identification of SIRT modulators and exploring the functions of these different modulators have prompted increased efforts to discover new small molecules, which can modify SIRT activity. Furthermore, several randomized controlled trials have indicated that different interventions might affect the expression of SIRT protein in human samples, and supplementation of SIRT modulators might have diverse impact on physiological function in different participants. In this review, we introduce the history and structure of the SIRT protein family, discuss the molecular mechanisms and biological functions of seven members of the SIRT protein family, elaborate on the regulatory roles of SIRTs in human disease, summarize SIRT inhibitors and activators, and review related clinical studies.

Resveratrol alleviates enterotoxigenic Escherichia coli K88-induced damage by regulating SIRT-1 signaling in intestinal porcine epithelial cells

This study found that resveratrol pretreatment attenuated porcine intestinal epithelial cell damage caused by enterotoxigenic Escherichia coli (ETEC) K88 in vitro and the protective effects of resveratrol were associated with SIRT-1 signaling. ETEC K88 is a main intestinal pathogen for post-weaning diarrhea (PWD) in piglets. With the strict ban on antibiotics in animal feed, people are seeking effective antibiotic substitutes to protect the intestinal system against harmful pathogenic bacteria. This study was conducted to evaluate the effects of resveratrol, a natural plant polyphenol, on ETEC K88-induced cellular damage in porcine enterocytes and underlying mechanisms. Intestinal porcine epithelial cell line 1 (IPEC-1) cells, pretreated with or without resveratrol (30 μM, 4 h), were challenged with ETEC K88 (MOI = 1 : 10) for 3 h. The results showed that ETEC K88 infection induced severe damage and dysfunction in IPEC-1 cells, as evidenced by a reduced cell viability, decreased tight junctions, mitochondrial dysfunction, and autophagy. It is noteworthy that IPEC-1 cells pre-treated with resveratrol improved their capacity for resistance to most of these abnormal phenotypes caused by ETEC K88 infection. Furthermore, we found that the activation of SIRT-1 signaling was associated with the benefits of resveratrol, as demonstrated by EX-527, an inhibitor of SIRT-1, which reversed most of the protective effects of resveratrol. In conclusion, these results indicated that resveratrol could protect intestinal epithelial cells against ETEC K88 infection by activating SIRT-1 signaling. These findings provide new insights into the role of resveratrol in maintaining intestinal physiological functions.

Role of AMPK mediated pathways in autophagy and aging

AMPK is an important kinase regulating energy homeostasis and also a key protein involved in a variety of signal transduction pathways. It plays a vitally regulatory role in cellular senescence. Activation of AMPK can delay or block the aging process, which is of great significance in the treatment of cardiovascular diseases and other aging related diseases, and provides a potential target for new indications such as Alzheimer's disease. Therefore, AMPK signaling pathway plays an important role in aging research. The in-depth study of AMPK activators will provide more new directions for the treatment of age-related maladies and the development of innovative drugs. Autophagy is a process that engulfs and degrades own cytoplasm or organelles. Thereby, meeting the metabolic demands and updating certain organelles of the cell has become a hotspot in the field of anti-aging in recent years. AMPK plays an important role between autophagy and senescence. In our review, the relationship among AMPK signaling, autophagy and aging will be clarified through the interaction between AMPK and mTOR, ULK1, FOXO, p53, SIRT1, and NF -κB.

Insights Into Parkin-Mediated Mitophagy in Alzheimer's Disease: A Systematic Review

Background: Parkin-mediated mitophagy is the dominant mitophagy pathway of neural cells. Its restoration will result in prevention of cognitive decline, including Alzheimer's disease (AD). The role of this mitophagy pathway in neurodegenerative diseases has drawn attention in recent years. The two main pathological proteins in AD, amyloid β (Aβ) and human Tau (hTau), interfere with mitochondrial dynamics through several pathways. However, taking into consideration the specific interactions between Aβ/hTau and Parkin, special focus is required on this mitophagy pathway and AD. In this review, these interactions are fully discussed, and an overview of the neuroprotective drugs that enhance Parkin-mediated mitophagy is presented. Methods: This systematic review was performed according to PRISMA guidelines, and a comprehensive literature search was done in the electronic databases up to September 2020, using search terms in the titles and abstracts to identify relevant studies. One hundred eighty-six articles were found, and 113 articles were screened by title and abstract. Finally, 25 articles were included in this systematic review according to our inclusion and exclusion criteria. Results: Accumulation of Aβ and hTau affects mitophagy, including Parkin-mediated. Tau seems to prevent Parkin translocation directly. A Parkin level in the cell appears to be of importance in determining the damage caused by Aβ and hTau and in the future therapeutic approaches. Parkin controls the PINK1 level via the presenillins, suggesting that mutations in presenillins affect Parkin mitophagy. Significance: Parkin mitophagy is a process affected by several AD pathological events multidimensionally.

Autophagy attenuates high glucose-induced oxidative injury to lens epithelial cells

Purpose: Autophagic dysfunction and abnormal oxidative stress are associated with cataract. The purpose of the present study was to investigate the changes of cellular autophagy and oxidative stress and their association in lens epithelial cells (LECs) upon exposure to high glucose.

Methods: Autophagy and oxidative stress-related changes were detected in streptozotocin-induced Type 1 diabetic mice and normal mouse LECs incubated in high glucose conditions. Rapamycin at a concentration of 100 nm/l or 50 μM chloroquine was combined for analysis of the relationship between autophagy and oxidative stress. The morphology of LECs during autophagy was observed by transmission electron microscopy. The expressions of autophagy markers (LC3B and p62) were identified, as well as the key factors of oxidative stress (SOD2 and CAT) and mitochondrial reactive oxygen species (ROS) generation.

Results: Transmission electron microscopy indicated an altered autophagy activity in diabetic mouse lens tissues with larger autophagosomes and multiple mitochondria. Regarding the expressions, LC3B was elevated, p62 was decreased first and then increased, and SOD2 and CAT were increased before a decrease during 4 months of follow-up in diabetic mice and 72 h of culture under high glucose for mouse LECs. Furthermore, rapamycin promoted the expressions of autophagy markers but alleviated those of oxidative stress markers, whereas chloroquine antagonized autophagy but enhanced oxidative stress by elevating ROS generation in LECs exposed to high glucose.

Conclusions: The changes in autophagy and oxidative stress were fluctuating in the mouse LECs under constant high glucose conditions. Autophagy might attenuate high glucose-induced oxidative injury to LECs.

Activation of AMPK restored impaired autophagy and inhibited inflammation reaction by up-regulating SIRT1 in acute pancreatitis

AIMS

Acute pancreatitis (AP) is a common inflammatory disorder with high incidence and mortality. AMPK-SIRT1 pathway is involved in a variety of diseases, but its role in AP remains elusive. This study was aimed to explore the role of AMPK-SIRT1 pathway in AP.

MAIN METHODS

AP models in vivo and vitro were constructed by intraperitoneal administration of L-arginine and caerulein-stimulated respectively. Rat serum amylase, IL-6 and TNF-α were determined by ELISA. The expression levels of AMPK, SIRT1, Beclin-1, LC3 and p62 were determined by qRT-PCR and western blot. The number of autophagosome was checked by transmission electron microscope.

KEY FINDINGS

Compared with NC rats, serum amylase, IL-6 and TNF-α were increased in AP rats. The expressions of AMPK and SIRT1 were decreased, while Beclin-1, LC3II/Iratio and p62 were markedly increased in AP rats. After activation of AMPK by metformin, expressions of p-AMPKα, SIRT1 were significantly raised, while expressions of Beclin-1, LC3 II/I, p62, TNF-α, IL-6 were reduced, and the number of autophagosome was decreased significantly in caerulein-stimulated AR42J cells. The inhibition of AMPK by compound C obtained opposite results.

SIGNIFICANCE

During AP occurrence, p-AMPK and SIRT1 were down-regulated, leading to the accumulation of p62, increase of autophagic vacuoles, damage of autophagy, and the occurrence of inflammation. It hinted that activation of AMPK restored impaired autophagy and inhibited inflammation reaction by up-regulating SIRT1. Our findings might provide important theoretical basis for explaining the pathogenesis of AP and investigating therapeutic target to treat and prevent AP.

Resveratrol Reduces COMPopathy in Mice Through Activation of Autophagy

Misfolding mutations in cartilage oligomeric matrix protein (COMP) cause it to be retained within the endoplasmic reticulum (ER) of chondrocytes, stimulating a multitude of damaging cellular responses including ER stress, inflammation, and oxidative stress, which ultimately culminates in the death of growth plate chondrocytes and pseudoachondroplasia (PSACH). Previously, we demonstrated that an antioxidant, resveratrol, substantially reduces the intracellular accumulation of mutant-COMP, dampens cellular stress, and lowers the level of growth plate chondrocyte death. In addition, we showed that resveratrol reduces mammalian target of rapamycin complex 1 (mTORC1) signaling, suggesting a potential mechanism. In this work, we investigate the role of autophagy in treatment of COMPopathies. In cultured chondrocytes expressing wild-type COMP or mutant-COMP, resveratrol significantly increased the number of Microtubule-associated protein 1A/1B-light chain 3 (LC3) vesicles, directly demonstrating that resveratrol-stimulated autophagy is an important component of the resveratrol-driven mechanism responsible for the degradation of mutant-COMP. Moreover, pharmacological inhibitors of autophagy suppressed degradation of mutant-COMP in our established mouse model of PSACH. In contrast, blockage of the proteasome did not substantially alter resveratrol clearance of mutant-COMP from growth plate chondrocytes. Mechanistically, resveratrol increased SIRT1 and PP2A expression and reduced MID1 expression and activation of phosphorylated protein kinase B (pAKT) and mTORC1 signaling in growth plate chondrocytes, allowing clearance of mutant-COMP by autophagy. Importantly, we show that optimal reduction in growth plate pathology, including decreased mutant-COMP retention, decreased mTORC1 signaling, and restoration of chondrocyte proliferation was attained when treatment was initiated between birth to 1 week of age in MT-COMP mice, translating to birth to approximately 2 years of age in children with PSACH. These results clearly demonstrate that resveratrol stimulates clearance of mutant-COMP by an autophagy-centric mechanism. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.

Resveratrol protects against high glucose-induced oxidative damage in human lens epithelial cells by activating autophagy

In the pathogenesis of diabetic cataract, high glucose levels induce oxidative damage in human lens epithelial cells (HLECs). Resveratrol has been demonstrated to be a potent antioxidant in various disease conditions; however, limited information is available on its effects on oxidative damage associated with the pathogenesis of diabetic cataract in HLECs. The present study aimed to determine whether resveratrol prevents high glucose-induced oxidative damage to human lens epithelial cells by activating autophagy. In the present study, HLECs treated with high glucose were used as a cellular model of diabetic cataract and treated with resveratrol for 24 h. Flow cytometry was performed to detect the cellular reactive oxygen species (ROS) content. Autophagy marker protein levels were determined by western blotting. Immunofluorescence assay was performed to analyze in vitro microtubule-associated protein 1 light chain 3 β (LC3B) protein expression. Autophagosome formation in HLECs was observed using transmission electron microscopy. The results demonstrated that high glucose suppressed HLEC viability and proliferation rate compared with normal glucose levels (5 mM), which were significantly reversed by resveratrol treatment. High glucose also increased the ROS content compared with ROS content in normal HLECs, which was reduced following resveratrol treatment. Further experiments demonstrated that resveratrol significantly reversed the high glucose-decreased protein levels of LC3II and beclin-1 proteins and the high glucose-increased protein levels of LC3I and p62 in HLECs. In conclusion, resveratrol inhibited the high glucose-induced oxidative damage in HLECs by promoting autophagy through the activation of the p38 mitogen-activated protein kinase signaling pathway. These results provide a theoretical basis for the application of resveratrol in diabetic cataract prevention and treatment.

Quercetin modulates AMPK/SIRT1/NF-κB signaling to inhibit inflammatory/oxidative stress responses in diabetic high fat diet-induced atherosclerosis in the rat carotid artery

Inflammation and oxidative stress serve interrelated roles in the development of atherosclerosis and other vascular diseases. Quercetin has been previously reported to exhibit numerous beneficial properties towards several metabolic conditions and cardiovascular disease. The present study aimed to evaluate the effects of quercetin on the 5'adenosine monophosphate-activated protein kinase (AMPK)/sirtuin 1 (SIRT1)/NF-κB signaling pathway and inflammatory/oxidative stress response in diabetic-induced atherosclerosis in the carotid artery of rats. Male Wistar rats were used to create a diabetes-induced atherosclerosis model by the administration of high fat diet (HFD) with streptozotocin, which lasted for 8 weeks. Control and diabetic rats received quercetin (30 mg/kg/day; orally) for the last 2 weeks of the diabetic period. Plasma lipid profile and vascular levels of oxidative stress markers, inflammatory cytokines, NF-κB signaling proteins and SIRT1 expression were evaluated using ELISA and western blotting. Quercetin treatment in HFD diabetic rats was reported to improve the lipid profile and reduce the number of atherosclerotic lesions, atherogenic index and malondialdehyde levels, whilst increasing the activity of enzymatic antioxidants in the carotid artery. Additionally, the inflammatory response was suppressed by quercetin administration, as indicated by the reduced NF-κB and IL-1β levels, and increased IL-10 levels. Furthermore, SIRT1 expression was revealed to be significantly increased in response to quercetin treatment compared with non-treated HFD rats. However, these effects of quercetin were abolished or reversed by the administration of compound-C (0.2 mg/kg), a specific AMPK blocker, in HFD rats. Therefore, quercetin may have promising potential in ameliorating atherosclerotic pathophysiology in the rat carotid artery by inhibiting oxidative stress and inflammatory responses mechanistically by modulating the AMPK/SIRT1/NF-κB signaling pathway.

Analysis of SIRT1 Expression in Plasma and in an In Vitro Model of Preeclampsia

Preeclampsia (PE) is a pregnancy-specific disorder that affects 3–8% expecting mothers worldwide being one of the main causes of maternal and fetal morbidity and mortality. The search for altered circulating molecules in PE is an important target to better understand the pathophysiology of this disease. Therefore, we evaluated Sirtuin-1 (SIRT1) concentration in plasma from healthy pregnant (HP) women, gestational hypertensive women (GH), and preeclampsia women (PE) via enzyme-linked immunosorbent assay (ELISA). We also measured intracellular SIRT1 in HUVECs incubated with plasma from PE patients compared to HP and GH via Western Blot Assay. Statistical differences were considered when p < 0.05. SIRT1 was downregulated in PE compared to HP and GH, both in plasma and in in vitro assay. Similarly, SIRT1 was also reduced in pregnant women who subsequently developed PE (case) compared to women who had healthy pregnancies (control). This reduction may be indicative of possible underlying pathophysiology mechanisms in PE.

Sera of Obese Type 2 Diabetic Patients Undergoing Metabolic Surgery Instead of Conventional Treatment Exert Beneficial Effects on Beta Cell Survival and Function: Results of a Randomized Clinical Study

BACKGROUND

Pancreatic beta cells are highly sensitive to oxidative and endoplasmic reticulum (ER) stress, commonly occurring in type 2 diabetes (T2D) and obesity.

OBJECTIVE

We aimed at investigating cellular responses of human beta cells exposed to sera from obese T2D patients treated differently, namely by conventional therapy or laparoscopic sleeve gastrectomy (LSG).

METHODS

Serum samples from obese T2D men randomized to conventional treatment or LSG were taken at baseline and 6 months later. After exposing 1.1B4 cells to study patients' sera, the following were assessed: cellular viability and proliferation (by MTT and xCELLigence assays), reactive oxygen species (ROS) production (with DCFH-DA), and expression of ER stress markers, oxidative- or autophagy-related proteins and insulin (by real-time PCR and Western blot).

RESULTS

At 6-month follow-up, patients undergoing LSG achieved an adequate glycemic control, whereas conventionally treated patients did not. As compared to 1.1B4 cells incubated with baseline sera (control), cells exposed to sera from LSG-treated participants exhibited (i) increased viability and proliferation (p < 0.05); (ii) diminished levels of ROS and p53 (p < 0.05); (iii) enhanced protein expression of autophagy-related SIRT1 and p62/SQSTM1 (p < 0.05); (iv) significantly decreased transcript levels of ER stress markers (p < 0.05); and (v) augmented insulin expression (p < 0.05). Conversely, the 6-month conventional therapy appeared not to impact on circulating redox status. Moreover, 1.1B4 cells exposed to sera from conventionally treated patients experienced mild ER stress.

CONCLUSION

Circulating factors in patients with improved diabetes after metabolic surgery exerted favorable effects on beta cell function and survival.

Autophagy as an emerging therapeutic target for age-related vascular pathologies

Introduction: The incidence of age-related vascular diseases such as arterial stiffness, hypertension and atherosclerosis, is rising dramatically and is substantially impacting healthcare systems. Mounting evidence suggests that there is an important role for autophagy in maintaining (cardio)vascular health. Impaired vascular autophagy has been linked to arterial aging and the initiation of vascular disease.Areas covered: The function and implications of autophagy in vascular smooth muscle cells and endothelial cells are discussed in healthy blood vessels and arterial disease. Furthermore, we discuss current treatment options for vascular disease and their links with autophagy. A literature search was conducted in PubMed up to October 2019.Expert opinion: Although the therapeutic potential of inducing autophagy in age-related vascular pathologies is considerable, several issues should be addressed before autophagy induction can be clinically used to treat vascular disease. These issues include uncertainty regarding the most effective drug target as well as the lack of potency and selectivity of autophagy inducing drugs. Moreover, drug tolerance or autophagy mediated cell death have been reported as possible adverse effects. Special attention is required for determining the cause of autophagy deficiency to optimize the treatment strategy.

Ghrelin induces autophagy and CXCR4 expression via the SIRT1/AMPK axis in lymphoblastic leukemia cell lines

T cell acute lymphoblastic leukemia (T-ALL) is one of the most frequent malignancies in children, and the CXCR4 receptor plays an important role in the metastasis of this malignancy. Ghrelin is a hormone with various functions including stimulation of the release of growth hormone and autophagy in cancer cells. Moreover, SIRT1 and AMPK (AMP-activated protein kinase) stimulate expression of proteins involved in autophagy. On the other hand, autophagic cell death can be an alternative target for cancer therapy, in the absence of apoptosis. The relationship between ghrelin and the SIRT1/AMPK axis and the resulting effects on autophagy, apoptosis, proliferation, and expression of CXCR4 and the ghrelin receptor (GHS-R1a), in Jurkat and Molt-4 human lymphoblastic cell lines was not previously clear. Here we demonstrate that SIRT1 expression is upregulated during the induction of autophagy by ghrelin, an effect that is inhibited by inactivation of SIRT1/AMPK axis. In addition, ghrelin can affect CXCR4 and GHS-R1a expression. In conclusion, this work reveals that ghrelin induces autophagy, invasion, and downregulation of ghrelin receptor expression via the SIRT1/AMPK axis in lymphoblastic cell lines. However, in these cell lines ghrelin-induced autophagy does not lead to cell death due to weak induction of apoptosis.

Polyphenols for diabetes associated neuropathy: Pharmacological targets and clinical perspective

OBJECTIVES

Diabetic neuropathy (DNP) is a widespread and debilitating complication with complex pathophysiology that is caused by neuronal dysfunction in diabetic patients. Conventional therapeutics for DNP are quite challenging due to their serious adverse effects. Hence, there is a need to investigate novel effective and safe options. The novelty of the present study was to provide available therapeutic approaches, emerging molecular mechanisms, signaling pathways and future directions of DNP as well as polyphenols' effect, which accordingly, give new insights for paving the way for novel treatments in DNP.

EVIDENCE ACQUISITION

A comprehensive review was done in electronic databases including Medline, PubMed, Web of Science, Scopus, national database (Irandoc and SID), and related articles regarding metabolic pathways on the pathogenesis of DNP as well as the polyphenols' effect. The keywords "diabetic neuropathy" and "diabetes mellitus" in the title/abstract and "polyphenol" in the whole text were used. Data were collected from inception until May 2019.

RESULTS

DNP complications is mostly related to a poor glycemic control and metabolic imbalances mainly inflammation and oxidative stress. Several signaling and molecular pathways play key roles in the pathogenesis and progression of DNP. Among natural entities, polyphenols are suggested as multi-target alternatives affecting most of these pathogenesis mechanisms in DNP.

CONCLUSION

The findings revealed novel pathogenicity signaling pathways of DNP and affirmed the auspicious role of polyphenols to tackle these destructive pathways in order to prevent, manage, and treat various diseases. Graphical Abstract .

Aflatoxin B1 impairs leydig cells through inhibiting AMPK/mTOR-mediated autophagy flux pathway

Aflatoxin B1 (AFB1), a potential endocrine disrupter, has been shown to induce hepatotoxicity in animal models, but the effects of AFB1 on Leydig cell function are unclear. In this study, in vivo exposure to AFB1 at 15 and 150 μg/kg/day lowered serum testosterone (T), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) levels, reduced Leydig cell number, and down-regulated the expression of testosterone biosynthesis-related genes. In vitro study showed that AFB1 (10 μM) significantly increased ROS levels, and decreased T production in Leydig cells by suppressing certain T-biosynthesis gene expressions. Moreover, AFB1 induced Leydig cell apoptosis through lowering pAMPK/AMPK ratio and increasing pmTOR/mTOR ratio, and then further up-regulating autophagy and apoptosis proteins, LC3, BECLIN 1, and BAX, as well as down-regulating autophagy flux protein P62 and anti-apoptosis protein BCL-2. AFB1-induced toxicity in Leydig cells was characterized by inhibiting T-biosynthesis gene expression, reducing Leydig cell number, promoting ROS production, and inducing cell apoptosis via suppressing AMPK/mTOR-mediated autophagy flux pathway.

The protective effect of lithocholic acid on the intestinal epithelial barrier is mediated by the vitamin D receptor via a SIRT1/Nrf2 and NF-κB dependent mechanism in Caco-2 cells

Lithocholic acid (LCA) is both a secondary bile acid and a vitamin D receptor (VDR) ligand. The VDR is activated by 1,25-dihydroxy vitamin D₃ and plays an important role in maintaining integrity of the intestinal mucosal barrier. LCA can also substitute for vitamin D to carry out the in vivo functions of vitamin D. However, it is unclear whether activation of the VDR by LCA affects mucosal barrier function. In the present study, we researched the protective effect of LCA on tumor necrosis factor-alpha (TNF-α)-induced intestinal epithelial barrier dysfunction in Caco-2 cells of the human epithelial intestinal adenocarcinoma cell line. Caco-2 cell monolayers were pretreated with LCA and then exposed to 100 ng/mL TNF-α. The results showed that LCA alleviated the decrease in transepithelial electrical resistance and the increase in FITC-Dextran flux induced by TNF-α. LCA ameliorated the TNF-α-induced decrease in protein expression and distribution of ZO-1, E-cadherin, Occludin, and Claudin-1, which are tight junction markers. Additionally, the LCA treatment effectively counteracted TNF-α-mediated downregulation of silent information regulator 1 (SIRT1), nuclear factor erythroid2-related factor 2 (Nrf2), and heme oxygenase-1, which are related to oxidative stress. Increases in NF-κB p-p65 and p-IκB-α induced by TNF-α were significantly inhibited by LCA. Considering all these, the present study indicates that LCA has a significant protective effect on TNF-α-induced injury of intestinal barrier function through the VDR and suggests that suppressing NF-κB signaling and activating the SIRT1/Nrf2 pathway might be one of the mechanisms underlying the protective effect of LCA.

Iron oxide nanoparticles promote vascular endothelial cells survival from oxidative stress by enhancement of autophagy

Dextran-coated superparamagnetic iron oxide nanoparticles (Dex-SPIONs) are excellent magnetic resonance imaging contrast agents for disease diagnosis and therapy. They can be delivered to target tissues mainly though vascular endothelium cells, which are major targets of oxidative stress. In cardiovascular cells, autophagy serves primarily on a pro-survival approach that protects the cells from oxidative stress even some autophagy inducers have been developed for adjuvant therapy of cardiovascular disorders. Our study demonstrated that the nanoparticles could be taken up by human umbilical vein endothelial cells (HUVECs) without causing obvious cytotoxicity but triggering autophagy. Furthermore, our results revealed that Dex-SPIONs could enhance HUVECs survival and reverse the reduction of nitric oxide secretion under the condition of H₂O₂ damage. However, these effects could be diminished by the autophagy inhibitor. In particular, we discovered that Dex-SPIONs evoked autophagy in HUVECs by reducing the phosphorylation of PRAS40, an upstream regulator of autophagy initiation. These results suggested that Dex-SPIONs functions as an autophagic-related antioxidant in HUVECs which may be utilized as an adjuvant therapy to cardiovascular disease associated with oxidative stress.

Protective effects of salvianolic acid B against hydrogen peroxide‑induced apoptosis of human umbilical vein endothelial cells and underlying mechanisms

Salvianolic acid B (Sal B) is a water-soluble active component of Danshen and has anti-atherosclerotic effects. The present study aimed to evaluate the cytoprotective effects of Sal B against hydrogen peroxide (H₂O₂)-induced oxidative stress damage in human umbilical vein endothelial cells (HUVECs) and investigate the underlying mechanisms. It was revealed that Sal B protected the cells from H₂O₂-induced damage, as indicated by MTT results showing enhanced cell viability and by flow cytometric analysis showing reduced apoptosis of cells challenged with H₂O₂. Furthermore, as an underlying mechanism, the enhancement of autophagy was indicated to be accountable for the decrease in apoptosis, as Sal B caused the upregulation of light chain 3-II and Beclin-1, and downregulation of p62 under H₂O₂-induced oxidative stress. Finally, Sal B increased the phosphorylation of AMP kinase (AMPK) and decreased the phosphorylation of mammalian target of rapamycin (mTOR), but had no effect on the phosphorylation of AKT. In conclusion, the present study revealed that Sal B protects HUVECs from oxidative stress, at least partially by promoting autophagy via activation of the AMPK pathway and downregulation of the mTOR pathway.

Quercetin alleviates high glucose-induced damage on human umbilical vein endothelial cells by promoting autophagy

BACKGROUND

Quercetin, a flavonoid antioxidant, has been found to exert therapeutic effects in diabetic condition. Autophagy represents a homeostatic cellular mechanism for the turnover of unfolds proteins and damaged organelles through a lysosome-dependent degradation manner. We speculated that quercetin could protect endothelial cells against high glucose-induced damage by promoting autophagic responses.

METHODS

HUVECs viability was evaluated by MTT method. Griess and TBARS assays were used to monitor the levels of NO and MDA, respectively. Intracellular ROS generation was determined in DCFDA-stained cells analyzed by flow cytometry. To investigate the role of quercetin in endothelial cell migratory behavior, we used a scratch test. The level of autophagy proteins LC3, Beclin-1 and P62 were measured by western blotting technique.

RESULTS

Our results showed that quercetin had the potential to increase cell survival after exposure to high glucose (P < 0.05). Total levels of oxidative stress markers were profoundly decreased and the activity of GSH was increased by quercetin (P < 0.05). High glucose suppressed HUVECs migration to the scratched area (P < 0.05). However, a significant stimulation in cell migration was observed after exposure to quercetin (P < 0.05). Based on data, autophagy was blocked at the late stage by high glucose concentration while quercetin enhanced autophagic response by reducing the P62 level coincided with the induction of Beclin-1 and LC3-II to LC3-I ratio (P < 0.05). All these beneficial effects were reversed by 3-methyladenine as an autophagy inhibitor.

CONCLUSION

Together, our data suggest that quercetin could protect HUVECs from high glucose induced-damage possibly by activation of the autophagy response.

The Potential Beneficial Effects of Resveratrol on Cardiovascular Complications in Marfan Syndrome Patients⁻Insights from Rodent-Based Animal Studies

Marfan syndrome (MFS) patients are at risk for cardiovascular disease. In particular, for aortic aneurysm formation, which ultimately can result in a life-threatening aortic dissection or rupture. Over the years, research into a sufficient pharmacological treatment option against aortopathy has expanded, mostly due to the development of rodent disease models for aneurysm formation and dissections. Unfortunately, no optimal treatment strategy has yet been identified for MFS. The biologically-potent polyphenol resveratrol (RES), that occurs in nuts, plants, and the skin of grapes, was shown to have a positive effect on aortic repair in various rodent aneurysm models. RES demonstrated to affect aortic integrity and aortic dilatation. The beneficial processes relevant for MFS included the improvement of endothelial dysfunction, extracellular matrix degradation, and smooth muscle cell death. For the wide range of beneficial effects on these mechanisms, evidence was found for the following involved pathways; alleviating oxidative stress (change in eNOS/iNOS balance and decrease in NOX4), reducing protease activity to preserve the extracellular matrix (decrease in MMP2), and improving smooth muscle cell survival affecting aortic aging (changing the miR21/miR29 balance). Besides aortic features, MFS patients may also suffer from manifestations concerning the heart, such as mitral valve prolapse and left ventricular impairment, where evidence from rodent models shows that RES may aid in promoting cardiomyocyte survival directly (SIRT1 activation) or by reducing oxidative stress (increasing superoxide dismutase) and increasing autophagy (AMPK activation). This overview discusses recent RES studies in animal models of aortic aneurysm formation and heart failure, where different advantageous effects have been reported that may collectively improve the aortic and cardiac pathology in patients with MFS. Therefore, a clinical study with RES in MFS patients seems justified, to validate RES effectiveness, and to judge its suitability as potential new treatment strategy.

Optimal Extraction Study of Gastrodin-Type Components from Gastrodia Elata Tubers by Response Surface Design with Integrated Phytochemical and Bioactivity Evaluation

Gastrodia elata tuber (GET) is a popular traditional Chinese medicines (TCMs). In this study, response surface methodology (RSM) with a Box–Behnken design (BBD) was performed to optimize the extraction parameters of gastrodin-type components (gastrodin, gastrodigenin, parishin A, parishin B, parishin C and parishin E). Different from the conventional studies that merely focused on the contents of phytochemical, we gave consideration to both quantitative analysis of the above six components by HPLC and representative bioactivities of GET, including antioxidation and protection of human umbilical vein endothelial cells (HUVEC). Four independent variables (ethanol concentration, liquid-material ratio, soaking time and extraction time) were investigated with the integrated evaluation index of phytochemical contents. With the validation experiments, the optimal extraction parameters were as follows: ethanol concentration of 41%, liquid–solid ratio of 28.58 mL/g, soaking time of 23.91 h and extraction time of 46.60 min. Under the optimum conditions, the actual standardized comprehensive score was 1.8134 ± 0.0110, which was in accordance with the predicted score of 1.8100. This firstly established method was proved to be feasible and reliable to optimize the extraction parameters of the bioactive components from GET. Furthermore, it provides some reference for the quality control and extraction optimization of TCMs.

LncRNA MALAT1 promotes oxidized low-density lipoprotein-induced autophagy in HUVECs by inhibiting the PI3K/AKT pathway

Emerging evidence suggests that long noncoding RNAs (lncRNAs) are involved in many biological processes, such as cell growth, differentiation, apoptosis, and autophagy. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), highly expressed in endothelial cells, is well conserved and implicated in endothelial cell migration and proliferation. However, whether MALAT1 participates in oxidized low-density lipoprotein (ox-LDL)-induced autophagy regulation in human umbilical vein endothelial cells (HUVECs) remains unknown. In this study, we observed that autophagy was upregulated and MALAT1 expression was markedly increased in HUVECs treated with ox-LDL. The ox-LDL-induced autophagy of HUVECs is significantly associated with the PI3K/AKT pathway. Furthermore, we found that MALAT1 overexpression inhibited PI3K, Akt and p70S6K phosphorylation and downregulated RHEB expression, simultaneously increasing ox-LDL-induced autophagy. MALAT1 silencing caused higher phosphorylated PI3K, Akt and p70S6K levels, upregulated RHEB expression and markedly suppressed autophagy. These results indicated that lncRNA MALAT1 promotes ox-LDL-induced autophagy in HUVECs partly through the PI3K/AKT signaling pathway.

Atheroprone flow enhances the endothelial-to-mesenchymal transition

The endothelial-to-mesenchymal transition (EndoMT) is a cellular process featuring decreased expression of endothelial marker genes but increased expression of mesenchymal marker genes. The EndoMT is involved in endothelial dysfunction and the pathogenesis of atherosclerosis. To investigate the dynamic expression of EndoMT genes in vascular endothelial cells under atheroprotective pulsatile shear stress (PS) and atheroprone oscillatory shear stress (OS), we analyzed RNA sequencing data from multitimepoint shear-stress experiments. This unbiased analysis involving next-generation sequencing confirmed that PS and OS had an opposite effect in regulating EndoMT genes. Further experimental validations with H2O2 and gain- and loss-of-function approaches indicated that reactive oxygen species are involved in OS-induced EndoMT, whereas AMP-activated protein kinase and sirtuin-1 could inhibit OS-induced EndoMT. Furthermore, compared with PS, OS increased the DNA methylation of the promoter regions of von Willebrand factor, CD31, and cadherin 5 genes but decreased that of cadherin 2, fibroblast-specific protein 1, and vimentin. The translational implication of the present study builds on the ability of the antidiabetic drug metformin and cholesterol-lowering drug atorvastatin to suppress the EndoMT in cultured endothelial cells and in mouse aortas. NEW & NOTEWORTHY Our RNA sequencing data provided a genome-wide and unbiased view of the shear stress regulation of the endothelial-to-mesenchymal transition (EndoMT) in the endothelium. Furthermore, epigenetic regulation (e.g., DNA methylation) is a key mechanism involved in shear stress-regulated EndoMT. The translational implication of this study is that cardiovascular medications such as statins and metformin have similar beneficial effects as that of atheroprotective flow by mitigating EndoMT.

The Role of Polyphenols in Human Health and Food Systems: A Mini-Review

This narrative mini- review summarizes current knowledge of the role of polyphenols in health outcomes-and non-communicable diseases specifically-and discusses the implications of this evidence for public health, and for future directions for public health practice, policy, and research. The publications cited originate mainly from animal models and feeding experiments, as well as human cohort and case-control studies. Hypothesized protective effects of polyphenols in acute and chronic diseases, including obesity, neurodegenerative diseases, type 2 diabetes, and cardiovascular diseases, are evaluated. Potential harmful effects of some polyphenols are also considered, counterbalanced with the limited evidence of harm in the research literature. Recent international governmental regulations are discussed, as the safety and health claims of only a few specific polyphenolic compounds have been officially sanctioned. The implications of food processing on the bioavailability of polyphenols are also assessed, in addition to the health claims and marketing of polyphenols as a functional food. Finally, this mini-review asserts the need for increased regulation and guidelines for polyphenol consumption and supplementation in order to ensure consumers remain safe and informed about polyphenols.

Sirtuins and Immuno-Metabolism of Sepsis

Sepsis and septic shock are the leading causes of death in non-coronary intensive care units worldwide. During sepsis-associated immune dysfunction, the early/hyper-inflammatory phase transitions to a late/hypo-inflammatory phase as sepsis progresses. The majority of sepsis-related deaths occur during the hypo-inflammatory phase. There are no phase-specific therapies currently available for clinical use in sepsis. Metabolic rewiring directs the transition from hyper-inflammatory to hypo-inflammatory immune responses to protect homeostasis during sepsis inflammation, but the mechanisms underlying this immuno-metabolic network are unclear. Here, we review the roles of NAD+ sensing Sirtuin (SIRT) family members in controlling immunometabolic rewiring during the acute systemic inflammatory response associated with sepsis. We discuss individual contributions among family members SIRT 1, 2, 3, 4 and 6 in regulating the metabolic switch between carbohydrate-fueled hyper-inflammation to lipid-fueled hypo-inflammation. We further highlight the role of SIRT1 and SIRT2 as potential "druggable" targets for promoting immunometabolic homeostasis and increasing sepsis survival.

Nicotinamide Phosphate Transferase (NAMPT) Increases in Plasma in Patients with Acute Coronary Syndromes, and Promotes Macrophages to M2 Polarization

Atherosclerosis is an inflammatory disease; monocytes and macrophages play an important role in the progression of this disease. However, the mechanisms are not fully understood yet. Nicotinamide phosphate transferase (NAMPT) is the rate limiting enzyme in the synthesis of NAD, but extracellular NAMPT shows the characteristics of cytokines/adipokines, suggesting that it may be a link between metabolism and inflammation. In this study, we compared the expression levels of the NAMPT/NAD+/Sirt1 signaling pathway as well as NAMPT, CRP and IL-6 in the peripheral blood mononuclear cell (PBMC), and plasma in patients with acute coronary syndromes and healthy subjects, and analyzed their association with macrophage polarization. The relationship between eNAMPT and iNAMPT and the polarization of macrophages was analyzed by NAD+, NAMPT blocker, and neutralizing antibody treatment. The results showed that the expression of the NAMPT/NAD+/Sirt1 signaling pathway was up-regulated in the peripheral blood of patients with ACS. Inhibition of iNAMPT expression can reduce M1 polarization; however, there was no significant effect on eNAMPT secretion and M2 polarization. Neutralizing eNAMPT by neutralizing antibodies can reduce M2 polarization and decrease the expression levels of IL-10, IL-13, IL-4 and IL-1ra. The addition of NAD+ in the cell culture supernatant had no significant effect on the polarization of M1 but increased the M2 polarization and the expression levels of IL-10 and IL-1ra. Our findings suggested that NAMPT is involved in the pathogenesis of atherosclerosis; the increased expression of eNAMPT in ACS patients may play a protective role by the up regulation of the NAMPT/NAD+/Sirt1 signaling pathway.

Interplay of Autophagy Inducer Rapamycin and Proteasome Inhibitor MG132 in Reduction of Foam Cell Formation and Inflammatory Cytokine Expression

MG132 is a pivotal inhibitor of the ubiquitin-proteasome system (UPS), and rapamycin (RAPA) is an important inducer of autophagy. MG132 and RAPA have been shown to be effective agents that can cure multiple autoimmune diseases by reducing inflammation. Although individual MG132 and RAPA showed protective effects for atherosclerosis (AS), the combined effect of these two drugs and its molecular mechanism are still unclear. In this article we investigate the regulation of oxidative modification of low-density lipoprotein (ox-LDL) stress and foam cell formation in the presence of both proteasome inhibitor MG132 and the autophagy inducer RAPA to uncover the molecular mechanism underlying this process. We established the foam cells model by ox-LDL and an animal model. Then, we tested six experimental groups of MG132, RAPA, and 3MA drugs. As a result, RAPA-induced autophagy reduces accumulation of polyubiquitinated proteins and apoptosis of foam cells. The combination of MG132 with RAPA not only suppressed expression of the inflammatory cytokines and formation of macrophage foam cells, but also significantly affected the NF-κB signaling pathway and the polarization of RAW 264.7 cells. These data suggest that the combination of proteasome inhibitor and autophagy inducer ameliorates the inflammatory response and reduces the formation of macrophage foam cells during development of AS. Our research provides a new way to suppress vascular inflammation and stabilize plaques of late atherosclerosis.

Silibinin protects human endothelial cells from high glucose-induced injury by enhancing autophagic response

Silibin, a flavonoid from the seeds of Silybum marianum (L.) Gaertn. (Asteraceae) has been reported to produce curative properties in diabetes. Autophagy is generated by a vast array of insults for removal of damaged proteins and organelles from the cell. Inadequate autophagy promotes endothelial cells dysfunction and delays in diabetic ulcers recovery. We hypothesized that silibinin could protect endothelial cells against high glucose-induced damage by engaging autophagic responses. HUVECs viability was evaluated by MTT assay. The Griess method and TBARS assay were used to monitor changes in the levels of nitric oxide and malondialdehyde, respectively. ROS generation was recorded in DCFDA-stained cells analyzed by flow cytometry. To investigate the role of silibinin on migration, we used scratch test. The level of autophagy proteins LC3, Becline-1, and P62 were measured by Western blotting. Our data showed that silibinin had potential to increase cell survival after exposure to high glucose condition. Total levels of oxidative stress markers were profoundly reduced and the activity of GSH was increased by silibinin. High glucose suppressed HUVECs migration to the scratched area. However, a significant increase in cell migration was observed after exposure to silibinin. Autophagy was blocked at the late stage by high glucose concentration and silibinin initiated an autophagic response by reducing P62 and enhancing Beclin-1 and LC3-II-LC3-I ratio. These effects were blocked by autophagy inhibitor of 3-Methyladenine. These observations suggest that silibinin could protect HUVECs from high glucose induced-damage possibly by activation of autophagy pathway.

The Signaling Pathways Involved in the Antiatherosclerotic Effects Produced by Chinese Herbal Medicines

Cardiovascular diseases (CVDs) are considered to be the predominant cause of death in the world. Chinese herb medicines (CHMs) have been widely used for the treatment of CVDs in Asian countries for thousands of years. One reason of high efficacy of CHMs in treating CVDs is attributed to their inhibition in atherosclerosis (AS) development, a critical contributor to CVDs occurrence. Cumulative studies have demonstrated that CHMs alleviate atherogenesis via mediating pathophysiologic events involved in AS. However, there is deficiency in the summaries regarding antiatherogenic signal pathways regulated by CHMs. In this review, we focus on the signal cascades by which herb medicines and relevant extractives, derivatives, and patents improve proatherogenic processes including endothelium dysfunction, lipid accumulation, and inflammation. We mainly elaborate the CHMs-mediated signaling pathways in endothelial cells, macrophages, and vascular smooth muscle cells of each pathogenic event. Moreover, we briefly describe the other AS-related factors such as thrombosis, autophagy, immune response, and noncoding RNAs and effects of CHMs on them in the way of cascade regulation, which is helpful to further illustrate the molecular mechanisms of AS initiation and progression and discover newly effective agents for AS management.

Long-Zhi Decoction Medicated Serum Promotes Angiogenesis in Human Umbilical Vein Endothelial Cells Based on Autophagy

Ischemic stroke (IS) is a fatal subtype of stroke that lacks effective treatments. Angiogenesis following IS is an effective response that mediates brain recovery and repair. Our previous study demonstrated that long-zhi decoction (LZD), a Chinese herbal formula, promoted angiogenesis in rats of IS model. To further investigate the association between the proangiogenic mechanism of an LZD-medicated serum and cellular autophagy, we evaluated its promotional effect on angiogenesis in human umbilical vein endothelial cells (HUVECs) in vitro. We used HUVECs subjected to H₂O₂ to induce injury and observed the effects of the LZD-medicated serum treatment. Cell-based assays included proliferation, migration, and tube formation. To assess the extent of autophagy, transmission electron microscopy was used to measure the number of autophagosomes. Immunofluorescence and Western blotting were performed to evaluate the autophagy-related protein of LC3-II and Beclin-1. The LZD-medicated serum promoted proliferation, migration, and tube formation in HUVECs. The LZD-medicated serum also increased the autophagosomes and the autophagic protein expressions of LC3-II and Beclin-1. The proangiogenic and autophagic activity of LZD provides new cogitations to its clinical application and may lead to potential drug development for treating various vascular diseases, especially in the elderly, in the future.

11β-HSD1 Inhibition by RL-118 Promotes Autophagy and Correlates with Reduced Oxidative Stress and Inflammation, Enhancing Cognitive Performance in SAMP8 Mouse Model

Elevated glucocorticoid (GC) exposure is widely accepted as a key factor in the age-related cognitive decline in rodents and humans. 11β-HSD1 is a key enzyme in the GCs pathway, catalyzing the conversion of 11β-dehydrocorticosterone to corticosterone in mice, with possible implications in neurodegenerative processes and cognitive impairment. Here, we determined the effect of a new 11β-HSD1 inhibitor, RL-118, administered to 12-month-old senescence-accelerated mouse-prone 8 (SAMP8) mice with neuropathological AD-like hallmarks and widely used as a rodent model of cognitive dysfunction. Behavioral tests (open field and object location) and neurodegeneration molecular markers were studied. After RL-118 treatment, increased locomotor activity and cognitive performance were found. Likewise, we found changes in hippocampal autophagy markers such as Beclin1, LC3B, AMPKα, and mTOR, indicating a progression in the autophagy process. In line with autophagy increase, a diminution in phosphorylated tau species (Ser 396 and Ser 404) jointly with an increase in ADAM10 and sAPPα indicated that an improvement in removing the abnormal proteins by autophagy might be implicated in the neuroprotective role of the 11β-HSD1 inhibitor. In addition, gene expression of oxidative stress (OS) and inflammatory markers, such as Hmox1, Aldh2, Il-1β, and Ccl3, were reduced in old treated mice in comparison to that of the control group. Consistent with this, we further demonstrate a significant correlation with autophagy markers and cognitive improvement and significant inverse correlation with autophagy, OS, and neuroinflammation markers. We concluded that inhibition of 11β-HSD1 by RL-118 prevented neurodegenerative processes and cognitive decline, acting on autophagy process, being an additional neuroprotective mechanism not described previously.

SIRT1 and SIRT6 Signaling Pathways in Cardiovascular Disease Protection

SIGNIFICANCE

Oxidative stress represents the common hallmark of pathological conditions associated with cardiovascular disease (CVD), including atherosclerosis, heart failure, hypertension, aging, diabetes, and other vascular system-related diseases. The sirtuin (SIRT) family, comprising seven proteins (SIRT1-SIRT7) sharing a highly conserved nicotinamide adenine dinucleotide (NAD+)-binding catalytic domain, attracted a great attention for the past few years as stress adaptor and epigenetic enzymes involved in the cellular events controlling aging-related disorder, cancer, and CVD. Recent Advances: Among sirtuins, SIRT1 and SIRT6 are the best characterized for their protective roles against inflammation, vascular aging, heart disease, and atherosclerotic plaque development. This latest role has been only recently unveiled for SIRT6. Of interest, in recent years, complex signaling networks controlled by SIRT1 and SIRT6 common to stress resistance, vascular aging, and CVD have emerged.

CRITICAL ISSUES

We provide a comprehensive overview of recent developments on the molecular signaling pathways controlled by SIRT1 and SIRT6, two post-translational modifiers proven to be valuable tools to dampen inflammation and oxidative stress at the cardiovascular level.

FUTURE DIRECTIONS

A deeper understanding of the epigenetic mechanisms through which SIRT1 and SIRT6 act in the signalings responsible for onset and development CVD is a prime scientific endeavor of the upcoming years. Multiple "omic" technologies will have widespread implications in understanding such mechanisms, speeding up the achievement of selective and efficient pharmacological modulation of sirtuins for future applications in the prevention and treatment of CVD. Antioxid. Redox Signal. 28, 711-732.

Rhynchophylla total alkaloid rescues autophagy, decreases oxidative stress and improves endothelial vasodilation in spontaneous hypertensive rats

Autophagy plays an important role in alleviating oxidative stress and stabilizing atherosclerotic plaques. However, the potential role of autophagy in endothelial vasodilation function has rarely been studied. This study aimed to investigate whether rhynchophylla total alkaloid (RTA) has a positive role in enhancing autophagy through decreasing oxidative stress, and improving endothelial vasodilation. In oxidized low-density lipoprotein (ox-LDL)-treated human umbilical vein endothelial cells (HUVECs), RTA (200 mg/L) significantly suppressed ox-LDL-induced oxidative stress through rescuing autophagy, and decreased cell apoptosis. In spontaneous hypertensive rats (SHR), administration of RTA (50 mg·kg^-1·d^-1, ip, for 6 weeks) improved endothelin-dependent vasodilation of thoracic aorta rings. Furthermore, RTA administration significantly increased the antioxidant capacity and alleviated oxidative stress through enhancing autophagy in SHR. In ox-LDL-treated HUVECs, we found that the promotion of autophagy by RTA resulted in activation of the AMP-activated protein kinase (AMPK) signaling pathway. Our results show that RTA treatment rescues the ox-LDL-induced autophagy impairment in HUVECs and improves endothelium-dependent vasodilation function in SHR.

Fish oil alleviates liver injury induced by intestinal ischemia/reperfusion via AMPK/SIRT-1/autophagy pathway

AIM

To evaluate whether fish oil (FO) can protect liver injury induced by intestinal ischemia/reperfusion (I/R) via the AMPK/SIRT-1/autophagy pathway.

METHODS

Ischemia in Wistar rats was induced by superior mesenteric artery occlusion for 60 min and reperfusion for 240 min. One milliliter per day of FO emulsion or normal saline was administered by intraperitoneal injection for 5 consecutive days to each animal. Animals were sacrificed at the end of reperfusion. Blood and tissue samples were collected for analyses. AMPK, SIRT-1, and Beclin-1 expression was determined in lipopolysaccharide (LPS)-stimulated HepG2 cells with or without FO emulsion treatment.

RESULTS

Intestinal I/R induced significant liver morphological changes and increased serum alanine aminotransferase and aspartate aminotransferase levels. Expression of p-AMPK/AMPK, SIRT-1, and autophagy markers was decreased whereas tumor necrosis factor-α (TNF-α) and malonaldehyde (MDA) were increased. FO emulsion blocked the changes of the above indicators effectively. Besides, in LPS-stimulated HepG2 cells, small interfering RNA (siRNA) targeting AMPK impaired the FO induced increase of p-AMPK, SIRT-1, and Beclin-1 and decrease of TNF-α and MDA. SIRT-1 siRNA impaired the increase of SIRT-1 and Beclin-1 and the decrease of TNF-α and MDA.

CONCLUSION

Our study indicates that FO may protect the liver against intestinal I/R induced injury through the AMPK/SIRT-1/autophagy pathway.

Hop derived flavonoid xanthohumol inhibits endothelial cell functions via AMPK activation

Angiogenesis, a process characterized by the formation of new blood vessels from pre-existing ones, is a crucial step in tumor growth and dissemination. Recently, increased attention has been addressed to the ability of flavonoids to prevent cancer by suppressing angiogenesis, strategy that we named "angioprevention". Several natural compounds exert their anti-tumor properties by activating 5' adenosine monophosphate-activated protein kinase (AMPK), a key regulator of metabolism in cancer cells. Drugs with angiopreventive activities, in particular metformin, regulate AMPK in endothelial cells. Here we investigated the involvement of AMPK in the anti-angiogenic effects of xanthohumol (XN), the major prenylated flavonoid of the hop plant, and mechanisms of action. The anti-angiogenic activity of XN was more potent than epigallocatechin-3-gallate (EGCG). Treatment of endothelial cells with XN led to increased AMPK phosphorylation and activity. Functional studies using biochemical approaches confirmed that AMPK mediates XN anti-angiogenic activity. AMPK activation by XN was mediated by CAMMKβ, but not LKB1. Analysis of the downstream mechanisms showed that XN-induced AMPK activation reduced nitric oxide (NO) levels in endothelial cells by decreasing eNOS phosphorylation. Finally, AKT pathway was inactivated by XN as part of its anti-angiogenic activity, but independently from AMPK, suggesting that these two signaling pathways proceed autonomously. Our study dissects the molecular mechanism by which XN exerts its potent anti-angiogenic activity, pointing out AMPK as a crucial signal transducer.

Resveratrol protects Leydig cells from nicotine-induced oxidative damage through enhanced autophagy

Some studies have revealed that nicotine can damage the male reproductive system through various means including oxidative stress, which is a primary factor in the pathogenesis of male infertility. The strong anti-oxidative capacity of resveratrol has been demonstrated previously, but its role in the context of male reproduction remains inconclusive. To explore the biological role of resveratrol in protecting male reproductive function and the potential underlying mechanism, nicotine-induced Leydig cells were used as a cell model of oxidative damage. The data showed that resveratrol treatment increased cell viability, SOD activity and anti-apoptotic activity in nicotine-stressed Leydig cells. This effect was accompanied by the upregulation of autophagy, which was illustrated by MDC-LysoTracker red staining. Moreover, pretreating with 3-methyladenine (3-MA), an autophagy inhibitor, attenuated resveratrol-induced Leydig cells autophagy and promoted apoptosis. Apart from this, resveratrol enhanced AMPK phosphorylation but reduced mTOR phosphorylation. Subsequently, upon inhibiting AMPK phosphorylation by AMPK inhibitors, Leydig cell autophagy induced by resveratrol was obviously abolished. In conclusion, resveratrol may exert its cytoprotective role against oxidative injury by the activation of autophagy via AMPK/mTOR pathway.

Metformin regulates oxLDL-facilitated endothelial dysfunction by modulation of SIRT1 through repressing LOX-1-modulated oxidative signaling

It is suggested that oxLDL is decisive in the initiation and development of atherosclerotic injuries. The up-regulation of oxidative stress and the generation of ROS act as key modulators in developing pro-atherosclerotic and anti-atherosclerotic processes in the human endothelial wall. In this present study, we confirmed that metformin enhanced SIRT1 and AMPK expression in human umbilical vein endothelial cells (HUVECs). Metformin also inhibited oxLDL-increased LOX-1 expression and oxLDL-collapsed AKT/eNOS levels. However, silencing SIRT1 and AMPK diminished the protective function of metformin against oxidative injuries. These results provide a new insight regarding the possible molecular mechanisms of metformin.

Resveratrol attenuates hydrogen peroxide‑induced apoptosis, reactive oxygen species generation, and PSGL‑1 and VWF activation in human umbilical vein endothelial cells, potentially via MAPK signalling pathways

Reactive oxygen species (ROS) are implicated in the pathogenesis of thrombosis. Studies have reported that resveratrol exhibits antioxidative activities, however, the effect and underlying mechanisms of resveratrol on venous thrombosis remain largely unknown. To investigate the effect of resveratrol on venous thrombosis and the underlying mechanisms, the present study investigated the effects of resveratrol on cell viability, apoptosis, ROS generation and the expression of thrombosis‑associated markers in human umbilical vein endothelial cells (HUVECs). HUVECs were pretreated with resveratrol for 2 h and incubated with hydrogen peroxide (H2O2) for 24 h prior to the evaluation of cell viability, ROS generation, apoptosis and thrombosis‑associated marker expression by performing MTT assays, 2',7'‑dichlorofluorescin diacetate reagent, flow cytometry, and reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) and western blot analysis, respectively. Subsequently, to validate whether resve-ratrol functions via mitogen‑activated protein kinase (MAPK) pathways, the expression of thrombosis‑associated markers was detected by western blot analysis and RT‑qPCR following treatment of cells with resveratrol and the MAPK pathway activators anisomycin and curcumin. The results demonstrated that cell viability was markedly reduced by H2O2, and resveratrol treatment reversed the reductions in cell viability in a dose‑dependent manner. In addition, the levels of cell apoptosis and ROS generation were significantly increased by H2O2 alone, and resveratrol also reduced these effects in a dose‑dependent manner. Furthermore, the mRNA and protein expression of caspase‑3, P‑selectin glycoprotein ligand‑1 and von Willebrand factor was upregulated by H2O2 treatment in HUVECs. However, resveratrol decreased the protein expression these proteins in a dose‑dependent manner. Resveratrol also significantly inhibited the induction of phosphorylated (p)‑p38, P‑c‑Jun N‑terminal kinase and P‑extracellular signal‑regulated kinase by H2O2, and these effects were attenuated by the MAPK pathway activators anisomycin and curcumin. In conclusion, these results indicate that resveratrol protected HUVECs against oxidative stress and apoptosis. Furthermore, to the best of our knowledge, the present study is the first to demonstrate that resveratrol attenuates the expression of thrombosis‑associated markers induced by H2O2, which may occur through the suppression of the MAPK signalling pathways, indicating a potential novel therapeutic approach to prevent venous thrombosis.

SIRT1 inhibition causes oxidative stress and inflammation in patients with coronary artery disease

Coronary artery disease (CAD) is the primary critical cardiovascular event. Endothelial cell and monocyte dysfunction with subsequent extravagant inflammation are the main causes of vessel damage in CAD. Thus, strategies that repress cell death and manage unsuitable pro-inflammatory responses in CAD are potential therapeutic strategies for improving the clinical prognosis of patients with CAD. SIRT1 (Sirtuin 1) plays an important role in regulating cellular physiological processes. SIRT1 is also thought to protect the cardiovascular system by means of its antioxidant, anti-inflammation and anti-apoptosis activities. In the present study, we found that the SIRT1 expression levels were repressed and the acetylated p53 expression levels were enhanced in the monocytes of patients with CAD. LOX-1/oxidative stress was also up-regulated in the monocytes of patients with CAD, thereby increasing pro-apoptotic events and pro-inflammatory responses. We also demonstrated that monocytes from CAD patients caused endothelial adhesion molecule activation and the adherence of monocytes and endothelial cells. Our findings may explain why CAD patients remain at an increased risk of long-term recurrent ischemic events and provide new knowledge regarding the management of clinical CAD patients.

Sitagliptin-mediated preservation of endothelial progenitor cell function via augmenting autophagy enhances ischaemic angiogenesis in diabetes

Recently, the dipeptidyl peptidase‐4 (DPP‐4) inhibitor sitagliptin, a major anti‐hyperglycaemic agent, has received substantial attention as a therapeutic target for cardiovascular diseases via enhancing the number of circulating endothelial progenitor cells (EPCs). However, the direct effects of sitagliptin on EPC function remain elusive. In this study, we evaluated the proangiogenic effects of sitagliptin on a diabetic hind limb ischaemia (HLI) model in vivo and on EPC culture in vitro. Treatment of db/db mice with sitagliptin (Januvia) after HLI surgery efficiently enhanced ischaemic angiogenesis and blood perfusion, which was accompanied by significant increases in circulating EPC numbers. EPCs derived from the bone marrow of normal mice were treated with high glucose to mimic diabetic hyperglycaemia. We found that high glucose treatment induced EPC apoptosis and tube formation impairment, which were significantly prevented by sitagliptin pretreatment. A mechanistic study found that high glucose treatment of EPCs induced dramatic increases in oxidative stress and apoptosis; pretreatment of EPCs with sitagliptin significantly attenuated high glucose‐induced apoptosis, tube formation impairment and oxidative stress. Furthermore, we found that sitagliptin restored the basal autophagy of EPCs that was impaired by high glucose via activating the AMP‐activated protein kinase/unc‐51‐like autophagy activating kinase 1 signalling pathway, although an autophagy inhibitor abolished the protective effects of sitagliptin on EPCs. Altogether, the results indicate that sitagliptin‐induced preservation of EPC angiogenic function results in an improvement of diabetic ischaemia angiogenesis and blood perfusion, which are most likely mediated by sitagliptin‐induced prevention of EPC apoptosis via augmenting autophagy.