Nicotinate-Curcumin Impedes Foam Cell Formation from THP-1 Cells through Restoring Autophagy Flux

Mechanism of salidroside regulating autophagy based on network pharmacology and molecular docking

Salidroside is a natural product of phenols with a wide range of pharmacological functions, but whether it plays a role in regulating autophagy is unclear. We systematically investigated the regulatory effect and molecular mechanism of salidroside on autophagy through network pharmacology, which provided a theoretical basis for subsequent experimental research. First, the target genes of salidroside were obtained using the Chinese Medicine System Pharmacology Database and Analysis Platform, and the target genes were converted into standardized gene names using the Uniprot website. At the same time, autophagy-related genes were collected from GeneCards, and preliminary handling of data to obtain intersecting genes. Then, the String website was used to construct a protein-protein interaction network, and to perform the Gene Ontology functional annotation and Kyoto Encyclopedia of Genes and Genomes pathway analysis. To observe the specific molecular mechanism by which salidroside regulates autophagy, we constructed a drug component-target genes-autophagy network. Finally, we performed molecular docking to verify the possible binding conformation between salidroside and the candidate target. By searching the database and analyzing the data, we found that 113 target genes in salidroside interact with autophagy. Salidroside regulate autophagy in relation to a number of important oncogenes and signaling pathways. Molecular docking confirmed that salidroside has high affinity with mTOR, SIRT1, and AKT1. Through network pharmacology combined with molecular docking-validated research methods, we revealed the underlying mechanism of salidroside regulation of autophagy. This study not only provides new systematic insights into the underlying mechanism of salidroside in autophagy, but also provides new ideas for network approaches for autophagy-related research.

Exploring global research trends in Chinese medicine for atherosclerosis: a bibliometric study 2012-2023

Background

While Traditional Chinese Medicine (TCM) boasts an extensive historical lineage and abundant clinical expertise in addressing atherosclerosis, this field is yet to be penetrated adequately by bibliometric studies. This study is envisaged to evaluate the contemporary scenario of TCM in conjunction with atherosclerosis over the preceding decade while also identifying forthcoming research trends and emerging topics via the lens of bibliometric analysis.

Methods

Literature pertaining to TCM and atherosclerosis, circulated between January 1, 2012 and November 14, 2023, was garnered for the purpose of this research. The examination embraced annual publications, primary countries/regions, engaged institutions and authors, scholarly journals, references, and keywords, utilizing analytical tools like Bibliometrix, CiteSpace, ScimagoGraphica, and VOSviewer present in the R package.

Result

This field boasts a total of 1,623 scholarly articles, the majority of which have been contributed by China in this field, with significant contributions stemming from the China Academy of Traditional Chinese Medicine and the Beijing University of Traditional Chinese Medicine. Moreover, this field has received financial support from both the National Natural Science Foundation of China and the National Key Basic Research Development Program. Wang Yong tops the list in terms of publication count, while Xu Hao's articles take the lead for the total number of citations, positioning them at the core of the authors' collaborative network. The Journal of Ethnopharmacology leads with the most publications and boasts the greatest total number of citations. Principal research foci within the intersection of Chinese Medicine and Atherosclerosis encompass disease characteristics and pathogenic mechanisms, theoretical underpinnings and syndrome-specific treatments in Chinese medicine, potentialities of herbal interventions, and modulation exerted by Chinese medicines on gut microbiota.

Conclusion

This analysis offers a sweeping survey of the contemporary condition, principal foci, and progressive trends in worldwide research related to Traditional Chinese Medicine (TCM) and atherosclerosis. It further delves into an in-depth dissection of prominent countries, research institutions, and scholars that have made noteworthy strides in this discipline. Additionally, the report analyzes the most cited articles, research developments, and hotspots in the field, providing a reference for future research directions for clinical researchers and practitioners.

Cyclophilin A accelerates SiO2-induced macrophage foaming

Silicosis is a common occupational disease characterized by lung inflammation, fibrosis and pulmonary dysfunction caused by long-term inhalation of free SiO₂. Cell foaming and the change of CyPA have been observed in SiO₂-induced macrophages, but the specific mechanism of CyPA in SiO₂-induced foam cells remains poorly understood. The purpose of this study is to explore the mechanism of CyPA in SiO₂-induced macrophage foaming and its effect on silicosis. We found that overexpression of CyPA promoted the macrophage foaming and the expression of COL I and α-SMA, while silencing CyPA inhibites the macrophage foaming and the expression of COL I and α-SMA. After blocking the expression of CD36 on the basis of overexpression CyPA, we found it inhibites the macrophage foaming. In conclusion, CyPA can affect the foaming of macrophages and may participate in silicosis fibrosis.

Natural compounds from botanical drugs targeting mTOR signaling pathway as promising therapeutics for atherosclerosis: A review

Atherosclerosis (AS) is a chronic inflammatory disease that is a major cause of cardiovascular diseases (CVDs), including coronary artery disease, hypertension, myocardial infarction, and heart failure. Hence, the mechanisms of AS are still being explored. A growing compendium of evidence supports that the activity of the mechanistic/mammalian target of rapamycin (mTOR) is highly correlated with the risk of AS. The mTOR signaling pathway contributes to AS progression by regulating autophagy, cell senescence, immune response, and lipid metabolism. Various botanical drugs and their functional compounds have been found to exert anti- AS effects by modulating the activity of the mTOR signaling pathway. In this review, we summarize the pathogenesis of AS based on the mTOR signaling pathway from the aspects of immune response, autophagy, cell senescence, and lipid metabolism, and comb the recent advances in natural compounds from botanical drugs to inhibit the mTOR signaling pathway and delay AS development. This review will provide a new perspective on the mechanisms and precision treatments of AS.

Curcumin-Nicotinate Attenuates Hippocampal Synaptogenesis Dysfunction in Hyperlipidemia Rats by the BDNF/TrkB/CREB Pathway: Involving Idol/LDLR Signaling to Eliminate Aβ Deposition

Hyperlipidemia has been demonstrated to evoke Alzheimer disease (AD) pathologies such as Amyloid-β (Aβ) deposition and synaptogenesis dysfunction in the hippocampus. Curcumin gives protection against anti-amyloid properties and synaptogenesis dysfunction. Curcumin-Nicotinate (CurTn), a new type of curcumin derivative, ameliorates cognitive impairment by rescuing autophagic flux in the CA1 hippocampus of diabetic rats. However, whether Curtn possesses an antagonistic effect on AD-related pathologies in the hippocampus induced by hyperlipidemia remains ill-defined. The present study aims to investigate whether CurTn alleviates synaptogenesis dysfunction by promoting the activation of brain-derived neurotrophic factor (BDNF)/tyrosine kinase receptor B (TrkB)/cAMP-response element binding protein (CREB) signaling and whether the underlying fundamental mechanism involves the elimination of Aβ deposition due to Idol/low-density lipoprotein receptor (LDLR) signaling in the hippocampus of high-fat diet (HFD)-induced hyperlipidemia rats. The results demonstrated that CurTn not only improved synaptogenesis dysfunction in the hippocampus of HFD rats, as evidenced by the increases in the expressions of synapse-related proteins postsynaptic density protein 95 (PSD-95), synapsin-1, and Glutamate receptor 1 (GluR1), but also activated BDNF/TrkB/CREB signaling, as evidenced by the elevation of the expressions of BDNF, pTrkB, and CREB. Moreover, CurTn modulated the Idol/LDLR pathway in the hippocampus of HFD rats, as evidenced by the decreased expression of Idol and the increased expression of LDLR. Furthermore, CurTn eliminated the deposition of Aβ, as evidenced by the reduction in the content of Aβ40 and Aβ42. These results reveal that CurTn may attenuate synaptogenesis dysfunction by activating BDNF/TrkB/CREB signaling, as the possible result of the modulation of Idol/LDLR signaling to eliminate Aβ deposition in the hippocampus of HFD rats.

Polyphenols: Chemoprevention and therapeutic potentials in hematological malignancies

Polyphenols are one of the largest plant-derived natural product and they play an important role in plants' defense as well as in human health and disease. A number of them are pleiotropic molecules and have been shown to regulate signaling pathways, immune response and cell growth and proliferation which all play a role in cancer development. Hematological malignancies on the other hand, are cancers of the blood. While current therapies are efficacious, they are usually expensive and with unwanted side effects. Thus, the search for newer less toxic agents. Polyphenols have been reported to possess antineoplastic properties which include cell cycle arrest, and apoptosis via multiple mechanisms. They also have immunomodulatory activities where they enhance T cell activation and suppress regulatory T cells. They carry out these actions through such pathways as PI3K/Akt/mTOR and the kynurenine. They can also reverse cancer resistance to chemotherapy agents. In this review, i look at some of the molecular mechanism of action of polyphenols and their potential roles as therapeutic agents in hematological malignancies. Here i discuss their anti-proliferative and anti-neoplastic activities especially their abilities modulate signaling pathways as well as immune response in hematological malignancies. I also looked at clinical studies done mainly in the last 10-15 years on various polyphenol combination and how they enhance synergism. I recommend that further preclinical and clinical studies be carried out to ensure safety and efficacy before polyphenol therapies be officially moved to the clinics.

Targeting autophagy in atherosclerosis: Advances and therapeutic potential of natural bioactive compounds from herbal medicines and natural products

Atherosclerosis (AS) is the most common causes of cardiovascular disease characterized by the formation of atherosclerotic plaques in the arterial wall, and it has become a dominant public health problem that seriously threaten people worldwide. Autophagy is a cellular self-catabolism process, which is critical to protect cellular homeostasis against harmful conditions. Emerging evidence suggest that dysregulated autophagy is involved in the development of AS. Therefore, pharmacological interventions have been developed to inhibit the AS via autophagy induction. Among various AS treating methods, herbal medicines and natural products have been applied as effective complementary and alternative medicines to ameliorate AS and its associated cardiovascular disease. Recently, mounting evidence revealed that natural bioactive compounds from herbs and natural products could induce autophagy to suppress the occurrence and development of AS, by promoting cholesterol efflux, reducing plaque inflammation, and inhibiting apoptosis or senescence. In the present review, we highlight recent findings regarding possible effects and molecular mechanism of natural compounds in autophagy-targeted mitigation of atherosclerosis, aiming to provide new potential therapeutic strategies for the atherosclerosis treatment preclinically and clinically.

The Impact of Oxidative Stress and AKT Pathway on Cancer Cell Functions and Its Application to Natural Products

Oxidative stress and AKT serine-threonine kinase (AKT) are responsible for regulating several cell functions of cancer cells. Several natural products modulate both oxidative stress and AKT for anticancer effects. However, the impact of natural product-modulating oxidative stress and AKT on cell functions lacks systemic understanding. Notably, the contribution of regulating cell functions by AKT downstream effectors is not yet well integrated. This review explores the role of oxidative stress and AKT pathway (AKT/AKT effectors) on ten cell functions, including apoptosis, autophagy, endoplasmic reticulum stress, mitochondrial morphogenesis, ferroptosis, necroptosis, DNA damage response, senescence, migration, and cell-cycle progression. The impact of oxidative stress and AKT are connected to these cell functions through cell function mediators. Moreover, the AKT effectors related to cell functions are integrated. Based on this rationale, natural products with the modulating abilities for oxidative stress and AKT pathway exhibit the potential to regulate these cell functions, but some were rarely reported, particularly for AKT effectors. This review sheds light on understanding the roles of oxidative stress and AKT pathway in regulating cell functions, providing future directions for natural products in cancer treatment.

Ameliorating potential of curcumin and its analogue in central nervous system disorders and related conditions: A review of molecular pathways

Curcumin, isolated from turmeric (Curcuma longa L.) is one of the broadly studied phytomolecule owing to its strong antioxidant and anti-inflammatory potential and has been considered a promising therapeutic candidate in a wide range of disorders. Considering, its low bioavailability, different curcumin analogs have been developed to afford desired pharmacokinetic profile and therapeutic outcome in varied pathological states. Several preclinical and clinical studies have indicated that curcumin ameliorates mitochondrial dysfunction, inflammation, oxidative stress apoptosis-mediated neural cell degeneration and could effectively be utilized in the treatment of different neurodegenerative diseases. Hence, in this review, we have summarized key findings of experimental and clinical studies conducted on curcumin and its analogues with special emphasis on molecular pathways, viz. NF-kB, Nrf2-ARE, glial activation, apoptosis, angiogenesis, SOCS/JAK/STAT, PI3K/Akt, ERK1/2 /MyD88 /p38 MAPK, JNK, iNOS/NO, and MMP pathways involved in imparting ameliorative effects in the therapy of neurodegenerative disorders and associated conditions.

Putative therapeutic impacts of cardiac CTRP9 in ischaemia/reperfusion injury

Recently, cytokines belonging to C1q/tumour necrosis factor‐related proteins (CTRPs) superfamily have attracted increasing attention due to multiple metabolic functions and desirable anti‐inflammatory effects. These various molecular effectors exhibit key roles upon the onset of cardiovascular diseases, making them novel adipo/cardiokines. This review article aimed to highlight recent findings correlated with therapeutic effects and additional mechanisms specific to the CTRP9, particularly in cardiac ischaemia/reperfusion injury (IRI). Besides, the network of the CTPR9 signalling pathway and its possible relationship with IRI were discussed. Together, the discovery of all involved underlying mechanisms could shed light to alleviate the pathological sequelae after the occurrence of IRI.

Autophagy and Diabetic Encephalopathy: Mechanistic Insights and Potential Therapeutic Implications

Diabetic Encephalopathy (DE) is one of the complications of diabetes mellitus (DM) in the central nervous system. Up to now, the mechanisms of DE are not fully discussed by the field. Autophagy is an intracellular degradation pathway crucial to maintain cellular homeostasis by clearing damaged organelles, pathogens, and unwanted protein aggregates. Increasing evidence has demonstrated that autophagy might play an essential role in DE progress. In this review, we summarize the current evidence on autophagy dysfunction under the condition of DE, and provide novel insights of possibly biological mechanisms linking autophagy impairment to DE, as well as discuss autophagy-targeted therapies as potential treatments for DE.

Monitoring Modified Lipoprotein Uptake and Macropinocytosis Associated with Macrophage Foam Cell Formation

Macrophage foam cell formation plays a crucial role in the initiation and progression of atherosclerosis. Macrophages uptake native and modified low density lipoprotein (LDL) through either receptor-dependent or receptor-independent mechanisms to transform into lipid laden foam cells. Foam cells are involved in the formation of fatty streak that is seen during the early stages of atherosclerosis development and therefore represents a promising therapeutic target. Normal or modified lipoproteins labeled with fluorescent dyes such as 1,1'-dioctadecyl-3-3-3',3'-tetramethylindocarbocyanine perchlorate (Dil) are often used to monitor their internalization during foam cell formation. In addition, the fluorescent dye Lucifer Yellow (LY) is widely used as a marker for macropinocytosis activity. In this chapter, we describe established methods for monitoring modified lipoprotein uptake and macropinocytosis during macrophage foam cell formation.

Bioactive components to inhibit foam cell formation in atherosclerosis

BACKGROUND

The production of lipid-laden cells in macrophages after significant ingestion of oxidized low-density lipoprotein is considered the most critical phase in the creation of atherosclerotic lesions, which is known as foam cell formation. Targeting foam cell development to find a potential therapeutic strategy for the management of atherosclerosis has yielded numerous promising outcomes. Multiple variables influence foam cell growth, including scavenger receptor expression, cholesterol transporter expression acyl CoA: cholesterol acyltransferase activity, and neutral cholesteryl ester hydrolase activity. Plants used during herbal therapy have been shown to assist with a variety of ailments.

RESULT

In this study, we found medicinal plants and their bioactive components suppress foam cell formation in a variety of ways; some inhibit cholesterol transporter and lectin-like oxidized low-density lipoprotein receptor-1 upregulation, while others inhibit the function of acyl CoA: cholesterol acyltransferase activity, and neutral cholesteryl ester hydrolase activity.

CONCLUSION

Recent study findings related to the synthesis of the new active component from plant sources by focusing on the typical process involved in the generation of foam cells. We're also looking at using a cellular target-based therapeutic approach to generate novel plant-based medications for the cure of atherosclerosis.

Curcumin-mediated photodynamic therapy inhibits the phenotypic transformation, migration, and foaming of oxidized low-density lipoprotein-treated vascular smooth muscle cells by promoting autophagy

Supplemental Digital Content is Available in the Text.

Vascular smooth muscle cells (VSMCs) are becoming a hot spot and target of atherosclerosis research. This study aimed to observe the specific effects of curcumin (CUR)-mediated photodynamic therapy (CUR-PDT) on oxidized low-density lipoprotein (ox-LDL)-treated VSMCs and confirm whether these effects are mediated by autophagy. In this study, the mouse aortic smooth muscle cell line and A7r5 cell lines were used for parallel experiments. VSMC viability was evaluated by Cell Counting Kit-8 assay. VSMCs were treated with ox-LDL to establish a model of atherosclerosis in vitro. The autophagy level and the expression of proteins related to phenotypic transformation were detected by western blotting. The migration ability of the cells was detected by using transwell assay. The presence of intracellular lipid droplets was detected by Oil Red O staining. The results showed that VSMCs transformed from the contraction phenotype to the synthetic phenotype when stimulated by ox-LDL, during which autophagy was inhibited. However, CUR-PDT treatment significantly promoted the level of autophagy and inhibited the process of phenotypic transformation induced by ox-LDL. In addition, ox-LDL significantly promoted VSMC migration and increased the number of lipid droplets, whereas CUR-PDT treatment significantly reduced the ox-LDL-induced increase in the migration ability of, and lipid droplet numbers in, VSMCs. When the VSMCs were pretreated with the autophagy inhibitor 3-methyladenine for 24 hours, the effects of CUR-PDT were reversed. Therefore, our study indicated that CUR-PDT can inhibit the phenotypic transformation, migration, and foaming of ox-LDL–treated VSMCs by inducing autophagy.

Autophagy-targeted therapy to modulate age-related diseases: Success, pitfalls, and new directions

Autophagy is a critical metabolic process that supports homeostasis at a basal level and is dynamically regulated in response to various physiological and pathological processes. Autophagy has some etiologic implications that support certain pathological processes due to alterations in the lysosomal-degradative pathway. Some of the conditions related to autophagy play key roles in highly relevant human diseases, e.g., cardiovascular diseases (15.5%), malignant and other neoplasms (9.4%), and neurodegenerative conditions (3.7%). Despite advances in the discovery of new strategies to treat these age-related diseases, autophagy has emerged as a therapeutic option after preclinical and clinical studies. Here, we discuss the pitfalls and success in regulating autophagy initiation and its lysosome-dependent pathway to restore its homeostatic role and mediate therapeutic effects for cancer, neurodegenerative, and cardiac diseases. The main challenge for the development of autophagy regulators for clinical application is the lack of specificity of the repurposed drugs, due to the low pharmacological uniqueness of their target, including those that target the PI3K/AKT/mTOR and AMPK pathway. Then, future efforts must be conducted to deal with this scenery, including the disclosure of key components in the autophagy machinery that may intervene in its therapeutic regulation. Among all efforts, those focusing on the development of novel allosteric inhibitors against autophagy inducers, as well as those targeting autolysosomal function, and their integration into therapeutic regimens should remain a priority for the field.

Different Effects of Endothelial Extracellular Vesicles and LPS-Induced Endothelial Extracellular Vesicles on Vascular Smooth Muscle Cells: Role of Curcumin and Its Derivatives

Background: During the progression of atherosclerosis (AS), the vascular endothelial and smooth muscle cells are reciprocally regulated by extracellular vesicles (EVs). EVs have different effects on pathological and physiological processes due to the different cargoes contained in EVs.

Purpose: To study the effects of endothelial cells-derived EVs on normal and inflammatory conditions. To investigate the effects of curcumin and curcumin derivatives (Nicotinic-curcumin) on endothelial EVs.

Methods: EVs were isolated from human umbilical vein endothelial cells (HUVECs) by ultracentrifugation. To examined the effect of normal and LPS-induced endothelial cells-derived EVs on the proliferation of human aortic smooth muscle cells (HASMCs), the CCK-8 assay was performed. Transwell and wound healing assays were conducted to assess cell migration. The effects of EVs on lipid accumulation following treatment with oxidized low-density lipoprotein (Ox-LDL) were evaluated with the oil red O staining assay and HPLC. The number of EVs was calculated using the nanoparticle tracking analysis (NTA) and BCA. The expression levels of Rab27a and Rab27b that regulate the EVs secretion were measured by Western blotting assay. The differential expression of miRNAs in endothelial EVs and LPS-induced endothelial EVs was analyzed using miRNA-Sequencing (miRNA-Seq) and RT-PCR.

Results: Treatment with endothelial EVs reduced the proliferation and migration of HASMCs as well as lipid accumulation in HASMCs. However, treatment with LPS-induced endothelial EVs did not inhibit the migration of HASMCs or lipid accumulation, instead it promoted the proliferation of HASMCs. Treatment with the two types of EVs induced differential expression of several miRNAs, including miR-92a-3p, miR-126-5p, miR-125a-3p, miR-143-3p, etc. Moreover, 1 μg/mL LPS induction greatly increased secretion of endothelial EVs. Treatment with curcumin and nicotinic-curcumin reduced endothelial EVs secretion, possibly by inhibiting inflammation.

Conclusion: Endothelial EVs may confer beneficial effects on atherosclerosis by regulating vascular smooth muscle cell (VSMCs), whereas pro-inflammatory factors may disrupt this effect.

Role of macrophage autophagy in atherosclerosis: modulation by bioactive compounds

Atherosclerosis is a chronic inflammatory disease associated with lipid metabolism disorder. Autophagy is a catabolic process and contributes to maintaining cellular homeostasis. Substantial evidence suggests that defective autophagy is implicated in several diseases, including atherosclerosis, while increased autophagy mitigates atherosclerosis development. Thus, understanding the mechanisms of autophagy regulation and its association with atherosclerosis is vital to develop new therapies against atherosclerosis. Dietary bioactive compounds are non-nutrient natural compounds that include phenolics, flavonoids, and carotenoids. Importantly, these bioactive compounds possess anti-inflammatory, antioxidant, and antibacterial properties that may alleviate various chronic diseases. Recently, examining the effects of bioactive compounds on autophagy activity in atherogenesis has drawn considerable attention. The current review discusses the role of macrophage autophagy in the development and progression of atherosclerosis. We also summarize our current knowledge of the therapeutic potential of bioactive compounds on atherosclerosis and autophagy.

Nicotinate-curcumin inhibits AngII-induced vascular smooth muscle cell phenotype switching by upregulating Daxx expression

Phenotypic switching is the main cause of the abnormal proliferation and migration of vascular smooth muscle cells (VSMCs). We previously showed that Daxx exerted negative regulatory effect on AngII-induced VSMC proliferation and migration. However, the function of Daxx in VSMC phenotype switching remained unknown. Nicotinate-curcumin (NC) is an esterification derivative of niacin and curcumin that can prevent the formation of atherosclerosis. We found that NC significantly decreased AngII-induced VSMC phenotype switching. Furthermore, NC significantly inhibited AngII-induced cell proliferation and migration. Moreover, NC upregulated Daxx expression and regulated the PTEN/Akt signaling pathway. We concluded that NC inhibited AngII-induced VSMC phenotype switching by regulating the PTEN/Akt pathway, and through a mechanism that might be associated with the upregulation of Daxx expression.

Curcumin and cardiovascular diseases: Focus on cellular targets and cascades

Cardiovascular diseases (CVDs) are one of the leading causes of the most considerable mortality globally, and it has been tried to find the molecular mechanisms and design new drugs that triggered the molecular target. Curcumin is the main ingredient of Curcuma longa (turmeric) that has been used in traditional medicine for treating several diseases for years. Numerous investigations have indicated the beneficial effect of Curcumin in modulating multiple signaling pathways involved in oxidative stress, inflammation, apoptosis, and proliferation. The cardiovascular protective effects of Curcumin against CVDs have been indicated in several studies. In the current review study, we provided novel information on Curcumin's protective effects against various CVDs and potential molecular signaling targets of Curcumin. Nonetheless, more studies should be performed to discover the exact molecular target of Curcumin against CVDs.

Effects of phytochemicals on macrophage cholesterol efflux capacity: Impact on atherosclerosis

High-density lipoprotein cholesterol (HDL) is the major promoter of reverse cholesterol transport and efflux of excess cellular cholesterol. The functions of HDL, such as cholesterol efflux, are associated with cardiovascular disease rather than HDL levels. We have reviewed the evidence base on the major classes of phytochemicals, including polyphenols, alkaloids, carotenoids, phytosterols, and fatty acids, and their effects on macrophage cholesterol efflux and its major pathways. Phytochemicals show the potential to improve the efficiency of each of these pathways. The findings are mainly in preclinical studies, and more clinical research is warranted in this area to develop novel clinical applications.

Curcumin promotes functional recovery and inhibits neuronal apoptosis after spinal cord injury through the modulation of autophagy

Objective: The study was aimed to investigate whether the neuroprotective role of curcumin is associated with regulation of autophagy.Methods: Rat spinal cord injury (SCI) models were established according to Allen's weight-drop trauma method. Curcumin was administered 30 min after the contusion and continued weekly. At 3, 7, 14, 21, and 28 days after SCI, functional recovery was evaluated using the Basso, Beattie and Bresnahan (BBB) scoring and the oblique plate test, following which, spinal cord tissues were obtained. Histological changes and apoptosis were then measured with H&E staining and TUNEL assay. Glia activation, inflammatory infiltration, inflammatory factor release, and myelination were observed through immunohistochemical (IHC) staining and ELISA. Autophagy and Akt activation were detected by western blotting. After autophagy was inhibited by injection of chloroquine, TUNEL, inflammatory factor release, myelin basic protein (MBP) IHC staining and functional recovery evaluation were performed again.Results: Curcumin treatment promoted functional recovery after SCI and reduced neuron apoptosis, improved spinal cord integrity, recovery, and re-myelination, and suppressed the inflammatory response. Autophagy was enhanced and Akt/mTOR pathway was inhibited by curcumin. Autophagy inhibition partially eliminated the protective effect of curcumin on SCI.Conclusion: Curcumin may exert its therapeutic effect on SCI through the enhancement of autophagy, in which, inhibition of the Akt/mTOR signaling pathway may be also involved.

Extract of high hydrostatic pressure-treated danshen (Salvia miltiorrhiza) ameliorates atherosclerosis via autophagy induction

Danshen (Salvia miltiorrhiza) is a traditional medicinal plant widely used in Asian countries for its pharmacological activities (e.g., amelioration of cardiovascular diseases). In this study, we investigated the anti-atherosclerotic activity of raw danshen root extract prepared using high hydrostatic pressure (HHP) at 550 MPa for 5 min and hot water extraction. This method was useful for elimination of bacteria from cultured danshen plants and for better extraction yield of active principles. The HHP-treated danshen extract (HDE) inhibited proliferation of human umbilical vein endothelial cells (HUVECs) and induced autophagy that was assessed by LC3 conversion and p62 degradation. HDE suppressed foam cell formation in oxLDL-induced RAW264.7 macrophages; lysosomal activity simultaneously increased, measured by acridine orange staining. HDE also reduced atherosclerotic plaque development in vivo in apolipoprotein E knock-out (ApoE^−/−) mice fed a high cholesterol diet. Taken together, these results indicated that HDE exhibited anti-atherosclerotic activity via autophagy induction.

Gypenoside inhibits ox-LDL uptake and foam cell formation through enhancing Sirt1-FOXO1 mediated autophagy flux restoration

BACKGROUND

Gypenoside (GP) is the major bioactive constituent of G. pentaphyllum, a traditional Chinese medicine. It has been reported that GP can affect autophagy and lipid metabolism in cultured cells. We hypothesize that GP can inhibit foam cell formation in cultured macrophages through autophagy modulation.

METHODS

THP1 cells were cultured and treated with oxidized low-density lipoprotein (ox-LDL), followed by GP treatment at different concentrations. The autophagy flux was evaluated using western blot and confocal microscope analyses. The ox-LDL uptake and foam cell formation abilities were measured.

RESULTS

We found that ox-LDL impaired the autophagy flux in the cultured macrophages, indicated by a significant reduction of LC3-II and autophagosome puncta quantification, as well as an accumulation of p62 proteins. GP treatment, however, dose-dependently restored the autophagy flux impaired by ox-LDL and reduced the ox-LDL uptake and foam cell transformation from THP1 cells, which can be alleviated, or exacerbated, by modulation of autophagy status using autophagy enhancer or inhibitor. Coimmunoprecipitation assays showed that GP up-regulated Srit1 and FOXO1 expression and enhanced their direct interaction, and thus contributed to the regulation of autophagy.

CONCLUSION

GP inhibits ox-LDL uptake and foam cell formation through enhancing Sirt1-FOXO1 mediated autophagy flux restoration, suggesting this compound has therapeutic potential for atherosclerosis.

Therapeutic potential of polyphenols in cardiovascular diseases: Regulation of mTOR signaling pathway

Cardiovascular diseases comprise of non-communicable disorders that involve the heart and/or blood vessels and have become the leading cause of death worldwide with increased prevalence by age. mTOR is a serine/threonine-specific protein kinase which plays a central role in many physiological processes including cardiovascular diseases, and also integrates various proliferative signals, nutrient and energy abundance and stressful situations. mTOR also acts as central regulator during chronic stress, mitochondrial dysfunction and deregulated autophagy which are associated with senescence. Under oxidative stress, mTOR has been reported to exert protective effects regulating apoptosis and autophagy processes and favoring tissue repair. On the other hand, inhibition of mTOR has been suggested to have beneficial effects against atherosclerosis, cardiac hypertrophy and heart failure, and also in extending the lifespan. In this aspect, the use of drugs or natural compounds, which can target mTOR is an interesting approach in order to reduce the number of deaths caused by cardiovascular disease. In the present review, we intend to shed light on the possible effects and molecular mechanism of natural agents like polyphenols via regulating mTOR.

Curcumin: From a controversial "panacea" to effective antineoplastic products

BACKGROUND

Curcumin, a controversial "panacea," has been broadly studied. Its bioactivities including antioxidant, anti-inflammatory, and especially antineoplastic activities have been documented. However, due to its extensive bioactivities, some scientists hold a skeptical point of view toward curcumin and described curcumin as a "deceiver" to chemists. The objective of this study was to explore curcumin's another possibility as a potential supplementary leading compound to cancer treatments.

METHODS

Literature searches were conducted using electronic databases. Search terms such as "curcumin," "curcumin analogues," and so on were used. The literatures were collected and summarized. In this article, reported targets of curcumin are reviewed. The limitations of a curcumin as a therapeutic anticancer product including low bioavailability and poor targeting are mentioned. Furthermore, modified curcumin analogues and antitumor mechanisms are listed and discussed in the aspects of cell death and tumor microenvironment including angiogenesis, tissue hypoxia status, and energy metabolism.

RESULTS

Several possible modification strategies were presented by analyzing the relationships between the antitumor activity of curcumin analogues and their structural characteristics, including the introduction of hydrophilic group, shortening of redundant hydrocarbon chain, the introduction of extra chemical group, and so on.

CONCLUSIONS

From our perspective, after structural modification curcumin could be more effective complementary product for cancer therapies by the enhancement of targeting abilities and the improvement of bioavailability.

Targeting Foam Cell Formation in Atherosclerosis: Therapeutic Potential of Natural Products

Foam cell formation and further accumulation in the subendothelial space of the vascular wall is a hallmark of atherosclerotic lesions. Targeting foam cell formation in the atherosclerotic lesions can be a promising approach to treat and prevent atherosclerosis. The formation of foam cells is determined by the balanced effects of three major interrelated biologic processes, including lipid uptake, cholesterol esterification, and cholesterol efflux. Natural products are a promising source for new lead structures. Multiple natural products and pharmaceutical agents can inhibit foam cell formation and thus exhibit antiatherosclerotic capacity by suppressing lipid uptake, cholesterol esterification, and/or promoting cholesterol ester hydrolysis and cholesterol efflux. This review summarizes recent findings on these three biologic processes and natural products with demonstrated potential to target such processes. Discussed also are potential future directions for studying the mechanisms of foam cell formation and the development of foam cell-targeted therapeutic strategies.

The role of traditional Chinese medicine in the treatment of atherosclerosis through the regulation of macrophage activity

Atherosclerosis (AS) is the main cause of ischemic cardiovascular, cerebrovascular and peripheral vascular diseases. Macrophage activity has been proven to play a critical role during the AS pathological process, which involves the adhesion, aggregation of mononuclear-macrophages, cell differentiation of M1/M2 macrophages as part of complex mechanisms occurring during lipid metabolism, apoptosis, autophagy, inflammation and immune reaction. Therefore, the development of effective AS treatments is likely to target macrophage activity. Certain herbal extracts (such as Salvia miltiorrhiza) have exhibited enormous potential for AS treatment in the past. Here, we aim to provide a summary on the current understanding of the type of action and the underlying target/pathway in macrophage regulation of certain herbal extracts used in Traditional Chinese Medicine for treatment of AS.

Corticosterone induces neurotoxicity in PC12 cells via disrupting autophagy flux mediated by AMPK/mTOR signaling

Aims

Our previous study indicated that chronic stress caused autophagy impairment and subsequent neuron apoptosis in hippocampus. However, the mechanism underlying the stress‐induced damage to neurons is unclear. In present work, we investigated whether stress‐level glucocorticoids (GCs) GCs promoted PC12 cell damage via AMPK/mTOR signaling‐mediated autophagy.

Methods

Chronic stress‐induced PC12 cell injury model was built by treatment with high level corticosterone (CORT). Cell injury was evaluated by flow cytometry assay and transmission electron microscopy observation.

Results

Autophagy flux was measured based on the changes in LC3‐II and P62 protein expressions, and the color alteration of mCherry‐GFP‐LC3‐II transfection. Our results showed that CORT not only increased cell injury and apoptosis, but also dysregulated AMPK/mTOR signaling‐mediated autophagy flux, as indicated by the upregulated expression of LC3‐II and P62 proteins, and the lowered ration of autolysosomes to autophagosomes. Mechanistically, our results demonstrated that autophagy activation by AMPK activator metformin or mTOR inhibitor rapamycin obviously promotes cell survival and autophagy flux, improved mitochondrial ultrastructure, and reduced expression of Cyt‐C and caspase‐3 in CORT‐induced PC12 cells.

Conclusion

These results indicate that high CORT triggers PC12 cell damage through disrupting AMPK/mTOR‐mediated autophagy flux. Targeting this signaling may be a promising approach to protect against high CORT and chronic stress‐induced neuronal impairment.

Indole-3-carbinol inhibits lipid deposition and promotes autophagy in hyperlipidemia zebrafish larvae

Indole-3-carbinol (I3C) is extracted from cruciferous vegetables and is well known for its anti-cancer, antioxidant and anti-inflammatory effects. This study investigated the protective effect of I3C in hyperlipidemia zebrafish larvae and early life stage toxicity of I3C on zebrafish embryos/larvae. Zebrafish larvae were fed with 4% high-cholesterol diet (HCD) and treated with I3C 2.5μmol/L and 5μmol/L for two weeks. Confocal image analysis, oil Red O staining were used to analysis vascular lipid accumulation and western blotting was used to evaluate possible mechanics. In addition, zebrafish embryos were treated with I3C for 96 h to assess the general toxicity and cardiotoxicity. We found that lipid deposition on vasculature was dose-dependently decreased in the I3C treated groups as compared with control group (47%, 23%, p<0.01). Moreover, we demonstrated that I3C inhibited lipid deposition by inducing autophagy, as identified by the enhancement of LC3-II, beclin-1, hVps34 and m-cathepsin D as well as by the reduction of P62, Bcl-2, Akt, p- Akt, mTOR, and p- mTOR in HCD fed zebrafish larvae (p<0.05). In summary, I3C shows protective effects on hyperlipidemia zebrafish larvae and maybe a promising multitarget drug in the prevention and protection against atherosclerotic.

LncRNA DYNLRB2-2 inhibits THP-1 macrophage foam cell formation by enhancing autophagy

The aim of this study was to investigate whether long non-coding RNA (lncRNA) DYNLRB2-2 can inhibit foam cell formation by activating autophagy. The location of DYNLRB2-2 in THP-1-derived macrophages was analyzed by fluorescence in situ hybridization (FISH). Oxidized-low-density lipoprotein (ox-LDL) was used to induce the formation of foam cells, Oil Red O (ORO) staining and high-performance liquid chromatography (HPLC) were performed to detect accumulation of lipid droplets and the level of cholesterol concentration, respectively. The mRNA and protein level of ATP-binding cassette transporter A1 (ABCA1) were examined by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blotting. Relative protein levels of (p-) liver kinase B1 (LKB1), (p-) AMP-activated protein kinase (AMPK), (p-) the mammalian target of rapamycin (mTOR) and autophagy markers (LC3 II, Beclin-1 and p62) in THP-1 macrophage-derived foam cells were analyzed by Western blotting. The levels of inflammatory factors [tumor necrosis factor (TNF)-α, interleukin (IL)-6 and IL-1β] in THP-1 macrophage-derived foam cells were detected by enzyme-linked immunosorbent assay (ELISA). 3-MA and compound C were used to block autophagy. Our data show that DYNLRB2-2 inhibited the formation of THP-1 macrophage-derived foam cells and promotes cholesterol efflux (CE) by activating autophagy. DYNLRB2-2 caused autophagy by activating the signaling pathway of LKB1/AMPK/mTOR in foam cells. DYNLRB2-2 activated the LKB1/AMPK/mTOR signaling pathway via the miR-298/Sirtuin 3 (SIRT3) axis. Our data indicated that DYNLRB2-2 enhanced CE by regulating the LKB1/AMPK/mTOR autophagy signaling pathway through the miR-298/SIRT3 axis, thereby blocking the formation of foam cells from THP-1 macrophages.

C1q/TNF-Related Protein 9 Inhibits THP-1 Macrophage Foam Cell Formation by Enhancing Autophagy

During the pathogenesis of early atherosclerosis, lipid-loaded macrophages are involved in plaque development and progression. As a novel adipokine, C1q/tumor necrosis factor–related protein-9 (CTRP9) has beneficial effects in cardiovascular disease. However, previous reports have not studied whether the formation of macrophage foam cell induced by oxidized low-density lipoprotein (ox-LDL) is affected by CTRP9. According to our study, in ox-LDL–induced THP-1 macrophages, CTRP9 could reduce the quantity of lipid droplets, lower the level of cholesteryl ester (CE), promote cholesterol efflux, as well as increase the expression level of the cholesterol transport receptors ATP-binding membrane cassette transporter A1 (ABCA1) and G1 (ABCG1). In addition, the protein of LC3 II is elevated and that of p62 is decreased in CTRP9-treated foam cells by enhancing autophagy. However, using 3-methyladenine (3-MA) abolished the role of CTRP9 by inhibiting autophagy. Mechanistically, the autophagy-promoting effects of CTRP9 on foam cells was reversed by an AMPK inhibitor, Compound C, which inhibited the signaling pathway of adenosine 5′-monophosphate (AMP)-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR). These results show that CTRP9 protects against atherosclerosis by promoting cholesterol efflux to reduce the formation of foam cell in virtue of inducing autophagy in an AMPK/mTOR signaling pathway–dependent manner.

Sestrin2 regulates monocyte activation through AMPK-mTOR nexus under high-glucose and dyslipidemic conditions

The vicious cycle between hyperinsulinemia and insulin resistance results in the progression of atherosclerosis in the vessel wall. The complex interaction between hyperglycemia and lipoprotein abnormalities promotes the development of atherogenesis. In the early phase of atherosclerosis, macrophage-derived foam cells play an important role in vascular remodeling. Mechanistic target of rapamycin (mTOR) signaling pathway has been identified to play an essential role in the initiation, progression, and complication of atherosclerosis. Recently sestrin2, an antioxidant, was shown to modulate TOR activity and thereby regulating glucose and lipid metabolism. But the role of sestrin2 in monocyte activation is still not clearly understood. Hence, this study is focussed on investigating the role of sestrin2 in monocyte activation under hyperglycemic and dyslipidemic conditions. High-glucose and oxidized low-density lipoprotein (LDL) treatments mediated proinflammatory cytokine production (M1) with a concomitant decrease in the anti-inflammatory cytokine (M2) levels in human monocytic THP1 cells. Both glucose and oxidized LDL (OxLDL) in a dose and time-dependent manner increased the mTOR activation with a marked reduction in the levels of pAMPK and sestrin2 expression. Both high-glucose and OxLDL treatment increased foam cell formation and adhesion of THP1 cells to endothelial cells. Experiments employing activator or inhibitor of adenosine monophosphate kinase (AMPK) as well as overexpression or silencing of sestrin2 indicated that high-glucose mediated monocyte polarization and adhesion of monocytes to the endothelial cells were appeared to be programmed via sestrin2-AMPK-mTOR nexus. Our results evidently suggest that sestrin2 plays a major role in regulating monocyte activation via the AMPK-mTOR-pathway under diabetic and dyslipidemic conditions and also AMPK regulates sestrin2 in a feedback mechanism.

A novel antioxidant Mito-Tempol inhibits ox-LDL-induced foam cell formation through restoration of autophagy flux

A bulk of cholesteryl esters accumulation in macrophage foam cells drives the occurrence and development of atherosclerosis. Evidence now shows that autophagy plays key roles in the degradation of intracellular lipid droplets via autolysosome, and also in the release of intracellular lipids via cholesterol efflux. In this study, we identified that a mitochondria-targeted antioxidant, Mito-Tempol, has protective effects against cholesteryl esters accumulation by activating autophagy. Mito-Tempol was shown to ameliorate the lipid burden for atherosclerosis, both in vitro and in vivo. In the established in vitro foam cell formation system using oxidized low-density lipoprotein (ox-LDL)-loaded THP-1 macrophages, Mito-Tempol prevented intracellular oxidative stress and attenuated lipid accumulation. Mito-Tempol rescued ox-LDL-impaired autophagic flux, thereby facilitating autophagy-mediated lipid degradation in THP-1 macrophages. Meanwhile, Mito-Tempol also increased the efflux of cholesterol via autophagy-dependent ABCA1 and ABCG1 up-regulation. The classical autophagy pathway of mTOR may be one of the effector for the autophagy restoration of Mito-Tempol. Our findings give the first insight that cardiovascular system disease may benefits more from the treatment of Mito-Tempol for its impact of reversing atherosclerosis via autophagy.

Curcumin: A naturally occurring autophagy modulator

Autophagy is a self-degradative process that plays a pivotal role in several medical conditions associated with infection, cancer, neurodegeneration, aging, and metabolic disorders. Its interplay with cancer development and treatment resistance is complicated and paramount for drug design since an autophagic response can lead to tumor suppression by enhancing cellular integrity and tumorigenesis by improving tumor cell survival. In addition, autophagy denotes the cellular ability of adapting to stress though it may end up in apoptosis activation when cells are exposed to a very powerful stress. Induction of autophagy is a therapeutic option in cancer and many anticancer drugs have been developed to this aim. Curcumin as a hydrophobic polyphenol compound extracted from the known spice turmeric has different pharmacological effects in both in vitro and in vivo models. Many reports exist reporting that curcumin is capable of triggering autophagy in several cancer cells. In this review, we will focus on how curcumin can target autophagy in different cellular settings that may extend our understanding of new pharmacological agents to overcome relevant diseases.

Nicotinate-curcumin ameliorates cognitive impairment in diabetic rats by rescuing autophagic flux in CA1 hippocampus

INTRODUCTION

Our previous study has confirmed that a novel curcumin derivate nicotinate-curcumin (NC) can facilitate autophagic flux in THP-1 cells induced by oxidized low-density lipoprotein.

AIMS

Given that autophagy plays critical roles in neurodegenerative diseases, the present study was carried out to investigate whether NC can improve cognitive function of rats with diabetes mellitus (DM) via restoring autophagic flux in CA1 hippocampus.

RESULTS

Our results showed that NC treatment improved cognitive deficit and attenuated neuronal loss as well as cellular ultrastructure impairment in the CA1 region of DM rats induced by streptozotocin. Moreover, NC lowered the expressions of the apoptosis-related proteins Bcl-2, Bax, Cyt-c, and cleaved Caspase-3. Notably, NC treatment reversed autophagic flux impairment as evidenced by the deceases in LC3-II and p62 protein levels, and autophagosome accumulation in the hippocampal CA1 region of DM rats. However, these protective effects of NC were abolished by cotreatment with 3-methyladenine (an autophagy inhibitor) and chloroquine (an autophagic flux inhibitor), respectively. Furthermore, NC treatment decreased the expressions of phosphorylated mammalian target of rapamycin (mTOR) and p70 ribosomal protein S6 kinase (p70S6k) proteins in the CA1 region of DM rats.

CONCLUSIONS

These results indicate that NC ameliorates DM-induced cognitive function impairment via restoring autophagic flux might by inhibiting mTOR/p70S6k activation in the CA1 region, and NC may be a promising agent for diabetic cognitive dysfunction prevention and treatment.

Drug permeation and metabolism in Mycobacterium tuberculosis: Prioritising local exposure as essential criterion in new TB drug development

Anti-tuberculosis (TB) drugs possess diverse abilities to penetrate the different host tissues and cell types in which infecting Mycobacterium tuberculosis bacilli are located during active disease. This is important since there is increasing evidence that the respective "lesion-penetrating" properties of the front-line TB drugs appear to correlate well with their specific activity in standard combination therapy. In turn, these observations suggest that rational efforts to discover novel treatment-shortening drugs and drug combinations should incorporate knowledge about the comparative abilities of both existing and experimental anti-TB agents to access bacilli in defined physiological states at different sites of infection, as well as avoid elimination by efflux or inactivation by host or bacterial metabolism. However, while there is a fundamental requirement to understand the mode of action and pharmacological properties of any current or experimental anti-TB agent within the context of the obligate human host, this is complex and, until recently, has been severely limited by the available methodologies and models. Here, we discuss advances in analytical models and technologies which have enabled investigations of drug metabolism and pharmacokinetics (DMPK) for new TB drug development. In particular, we consider the potential to shift the focus of traditional pharmacokinetic-pharmacodynamic analyses away from plasma to a more specific "site of action" drug exposure as an essential criterion for drug development and the design of dosing strategies. Moreover, in summarising approaches to determine DMPK data for the "unit of infection" comprising host macrophage and intracellular bacillus, we evaluate the potential benefits of including these analyses at an early stage in the preclinical drug development algorithm. © 2018 IUBMB Life, 70(9):926-937, 2018.

Celosins inhibit atherosclerosis in ApoE-/- mice and promote autophagy flow

ETHNOPHARMACOLOGICAL RELEVANCE

Semen celosiae is a traditional Chinese medicine for purging hepatic pathogenic fire and removing nebula to improve eyesight, treating hepatopyretic vertigo and hypertension. It possesses a serial of potential bioactivities such as hepatoprotection, anti-tumor and anti-inflammatory, anti-diabetes. The triterpenoid saponins celosins from it were proved to have hepatoprotection, lipid lowing and anti-inflammatory. However, the anti-atherosclerosis activities were not reported to date.

AIM OF THE STUDY

This study was designed to examine the therapeutic effects of celosins (CES), the active constituents extracted from Semen celosiae.

MATERIALS AND METHODS

Atherosclerosis model by feeding high fat diet for 12 weeks in ApoE^-/- mice and foam cell model by ox-LDL-treated peritoneal macrophages were performed. The lipid plaque was measured by histopathological analysis. The LC3 dots in the aortic root lesion examined through tissue immunofluorescence. The peritoneal macrophage phagocytosis, formation of foam cells, genes associated protein expression and autophagy flux were measured on foam cell model by oxidized low-density lipoprotein (Ox-LDL) stimulating peritoneal macrophages. The mRNA expression of CD36, SR-A1, ABCA1 and ABCG1 were determined by Real-Time PCR method. The expressions of LC3 and beclin 1 were measured using Western blot.

RESULTS

CES (10, 30, 90mg/kg; p.o.) administrated for 4 weeks significantly reduced the prevalence of the relative area of plaque in mouse aorta, and showed the therapeutic effect on atherosclerosis. In the tissue section of immunofluorescence for aortic root, compared with high fat diet model group, the number of autophagy bodies in CES group increased significantly, suggesting that inhibiting atherosclerosis effect of CES may be related to its promoting autophagy. In vitro, CES significantly reduced phagocytosis of macrophages on lipid and formation rate of foam cells. CES down-regulated the mRNA expression of CD36 and SR-A1 while up-regulated mRNA expression of ABCA1 and ABCG1. Further, CES increased the autophagy specific protein LC3 and beclin 1, and it also increased the level of autophagy in the cells, and promoted the process of autophagy.

CONCLUSIONS

The therapeutic effect of CES on atherosclerosis may be related to the promotion of autophagy.

Ginsenoside Rb1 Enhances Atherosclerotic Plaque Stability by Improving Autophagy and Lipid Metabolism in Macrophage Foam Cells

Atherosclerosis (AS) is a lipid-driven disease in which macrophage foam cells play a critical role by increasing vascular lipid accumulation and contributing to plaque instability. Ginsenoside Rb1 (Rb1), the most abundant active component of ginseng, has been found potently to promote lipid metabolism and attenuate lipid accumulation. However, the underlying mechanisms remain unclear. In this study, the effects of Rb1 on lipid accumulation and plaque stability were investigated both in vitro and in vivo by using primary peritoneal macrophages isolated from C57BL/6 mice and an AS model in ApoE^-/- mice. The results showed that Rb1 reduced lipid accumulation both in macrophage foam cells and atherosclerotic plaques. Rb1 treatment promoted plaque stability by modifying plaque composition via the activation of autophagy both in vitro and in vivo. Transmission electron microscopy further showed an increased accumulation of autophagolysosomes in Rb1-treated macrophage foam cells. However, the modulation of lipid accumulation by Rb1 was attenuated by autophagy blockage using autophagy-related gene 5 (Atg5) small interfering RNA (siRNA) in vitro. In addition, Rb1 notably increased AMPK phosphorylation both in vitro and in vivo, and the AMPK inhibitor compound C abolished the Rb1-induced autophagy in macrophage foam cells. In conclusion, ginsenoside Rb1 reduced lipid accumulation in macrophage foam cells and enhanced atherosclerotic plaque stability by the induction of macrophage autophagy. Our study provides new evidence for the possible use of Rb1 in the prevention and treatment of AS.

Roles of Autophagy in Ischemic Heart Diseases and the Modulatory Effects of Chinese Herbal Medicine

Autophagy is an evolutionarily conserved degradation process which eliminates dysfunctional proteins and cytoplasmic components to maintain homeostasis for cell survival. Increasing evidence has demonstrated the modulatory role of autophagy in ischemic heart diseases (IHDs). Traditionally, this process has been recognized as having protective functions, such as inhibiting atherosclerosis progression and reducing cell death during the ischemic phase. However, recent studies have suggested its dual roles in myocardial ischemia/reperfusion (MIR) injury. Excessive autophagy may play a deleterious role in cardiac function, due to overwhelming clearance of cellular constituents and proteins. Hence modulation of autophagy to increase cardiomyocyte survival and improve cardiac function is meaningful for the treatment of IHD. Chinese herbal medicine, including extractive compounds and patented drugs, has shown its potential role in treating IHD by addressing autophagy-related mechanisms. This review summarizes the updated knowledge on the molecular basis and modulatory role of autophagy in IHD and the recent progress of Chinese herbal medicine in its treatment.

SIRT1 inhibition promotes atherosclerosis through impaired autophagy

SIRT1, a highly conserved NAD⁺-dependent protein deacetylase, plays a pivotal role in the pathogenesis and therapy of atherosclerosis (AS). The aim of this study is to investigate the potential effects of SIRT1 on AS in ApoE^-/- mice and the underlying mechanisms of autophagy in an ox-LDL-stimulated human monocyte cell line, THP-1. In vivo, the accelerated atherosclerotic progression of mice was established by carotid collar placement; then, mice were treated for 4 weeks with a SIRT1-specific inhibitor, EX-527. The atherosclerotic lesion size of EX-527-treated mice was greatly increased compared to that of the mice in the control group. Immunostaining protocols confirmed that the inhibition of SIRT1 during plaque initiation and progression enhanced the extent of intraplaque macrophage infiltration and impaired the autophagy process. In vitro cultured THP-1 macrophages exposed to ox-LDL were utilized to study the link between the SIRT1 function, autophagy flux, pro-inflammatory cytokine secretion, and foam cell formation using different methods. Our data showed that ox-LDL markedly suppressed SIRT1 protein expression and the autophagy level, while it elevated the MCP-1 production and lipid uptake. Additionally, the application of the SIRT1 inhibitor EX-527 or SIRT1 siRNA further attenuated ox-LDL-induced autophagy inhibition. In conclusion, our results show that the inhibition of SIRT1 promoted atherosclerotic plaque development in ApoE^-/- mice by increasing the MCP-1 expression and macrophage accumulation. In particular, we demonstrate that blocking SIRT1 can exacerbate the acetylation of key autophagy machinery, the Atg5 protein, which further regulates the THP-1 macrophage-derived foam cell formation that is triggered by ox-LDL.

Curcumin as a potential protective compound against cardiac diseases

Curcumin, which was first used 3000 years ago as an anti-inflammatory agent, is a well-known bioactive compound derived from the active ingredient of turmeric (Curcuma longa). Previous research has demonstrated that curcumin has immense therapeutic potential in a variety of diseases via anti-oxidative, anti-apoptotic, and anti-inflammatory pathways. Cardiac diseases are the leading cause of mortality worldwide and cause considerable harm to human beings. Numerous studies have suggested that curcumin exerts a protective role in the human body whereas its actions in cardiac diseases remain elusive and poorly understood. On the basis of the current evidence, we first give a brief introduction of cardiac diseases and curcumin, especially regarding the effects of curcumin in embryonic heart development. Secondly, we analyze the basic roles of curcumin in pathways that are dysregulated in cardiac diseases, including oxidative stress, apoptosis, and inflammation. Thirdly, actions of curcumin in different cardiac diseases will be discussed, as will relevant clinical trials. Eventually, we would like to discuss the existing controversial opinions and provide a detailed analysis followed by the remaining obstacles, advancement, and further prospects of the clinical application of curcumin. The information compiled here may serve as a comprehensive reference of the protective effects of curcumin in the heart, which is significant to the further research and design of curcumin analogs as therapeutic options for cardiac diseases.

Oxidized low-density lipoprotein induced mouse hippocampal HT-22 cell damage via promoting the shift from autophagy to apoptosis

AIMS

Although oxidized low-density lipoprotein (ox-LDL) in the brain induces neuronal death, the mechanism underlying the damage effects remains largely unknown. Given that the ultimate outcome of a cell is depended on the balance between autophagy and apoptosis, this study was performed to explore whether ox-LDL induced HT-22 neuronal cell damage via autophagy impairment and apoptosis enhancement.

METHODS

Flow cytometry and transmission electron microscopy (TEM) were used to evaluate changes in cell apoptosis and autophagy, respectively. The protein expression of LC3-II, p62, Bcl-2, and Bax in HT-22 cells was measured by Western bolt analysis.

RESULTS

Our study confirmed that 100 μg/mL of ox-LDL not only promoted TH-22 cell apoptosis, characterized by elevated cell apoptosis rate and Bax protein expression, decreased Bcl-2 protein expression, and damaged cellular ultrastructures, but also impaired autophagy as indicated by the decreased LC3-II levels and the increased p62 levels. Importantly, all of these effects of ox-LDL were significantly aggravated by cotreatment with chloroquine (an inhibitor of autophagy flux). In contrast, cotreatment with rapamycin (an inducer of autophagy) remarkably reversed these effects of ox-LDL.

CONCLUSIONS

Taken together, our results indicated that ox-LDL-induced shift from autophagy to apoptosis contributes to HT-22 cell damage.