Geniposide ameliorates atherosclerosis by restoring lipophagy via suppressing PARP1/PI3K/AKT signaling pathway

BACKGROUND

Atherosclerosis (AS) is the leading cause of global death, which manifests as arterial lipid stack and plaque formation. Geniposide is an iridoid glycoside extract from Gardenia jasminoides J.Ellis that ameliorates AS by mediating autophagy. However, how Geniposide regulates autophagy and treats AS remains unclear.

PURPOSE

To evaluate the efficacy and mechanism of Geniposide in treating AS.

STUDY DESIGN AND METHODS

Geniposide was administered to high-fat diet-fed ApoE-/- mice and oxidized low-density lipoprotein-incubated primary vascular smooth muscle cells (VSMCs). AS was evaluated with arterial lipid stack, plaque progression, and collagen loss in the artery. Foam cell formation was detected by lipid accumulation, inflammation, apoptosis, and the expression of foam cell markers. The mechanism of Geniposide in treating AS was assessed using network pharmacology. Lipophagy was measured by lysosomal activity, expression of lipophagy markers, and the co-localization of lipids and lipophagy markers. The effects of lipophagy were blocked using Chloroquine. The role of PARP1 was assessed by Olaparib (a PARP1 inhibitor) intervention and PARP1 overexpression.

RESULTS

In vivo, Geniposide reversed high-fat diet-induced hyperlipidemia, plaque progression, and inflammation. In vitro, Geniposide inhibited VSMC-derived foam cell formation by suppressing lipid stack, apoptosis, and the expressions of foam cell markers. Network pharmacological analysis and in vitro validation suggested that Geniposide treated AS by enhancing lipophagy via suppressing the PI3K/AKT signaling pathway. The benefits of Geniposide in alleviating AS were offset by Chloroquine in vivo and in vitro. Inhibiting PARP1 using Olaparib promoted lipophagy and alleviated AS progression, while PARP1 overexpression exacerbated foam cell formation and lipophagy blockage. The above effects of PARP1 were weakened by PI3K inhibitor LY294002. PARP1 also inhibited the combination of the ABCG1 and PLIN1.

CONCLUSION

Geniposide alleviated AS by restoring PARP1/PI3K/AKT signaling pathway-suppressed lipophagy. This study is the first to present the lipophagy-inducing effect of Geniposide and the binding of ABCG1 and PLIN1 inhibited by PARP1.

Cell death in atherosclerosis

A complex and evolutionary process that involves the buildup of lipids in the arterial wall and the invasion of inflammatory cells results in atherosclerosis. Cell death is a fundamental biological process that is essential to the growth and dynamic equilibrium of all living things. Serious cell damage can cause a number of metabolic processes to stop, cell structure to be destroyed, or other irreversible changes that result in cell death. It is important to note that studies have shown that the two types of programmed cell death, apoptosis and autophagy, influence the onset and progression of atherosclerosis by controlling these cells. This could serve as a foundation for the creation of fresh atherosclerosis prevention and treatment strategies. Therefore, in this review, we summarized the molecular mechanisms of cell death, including apoptosis, pyroptosis, autophagy, necroptosis, ferroptosis and necrosis, and discussed their effects on endothelial cells, vascular smooth muscle cells and macrophages in the process of atherosclerosis, so as to provide reference for the next step to reveal the mechanism of atherosclerosis.

Effects and mechanisms of Zhizi Chuanxiong herb pair against atherosclerosis: an integration of network pharmacology, molecular docking, and experimental validation

BACKGROUND

The Zhizi Chuanxiong herb pair (ZCHP) can delay pathological progression of atherosclerosis (AS); however, its pharmacological mechanism remains unclear because of its complex components. The purpose of current study is to systematically investigate the anti-AS mechanism of ZCHP.

METHODS

The databases of TCMSP, STITCH, SwissTargetPrediction, BATMAN-TCM, and ETCM were searched to predict the potential targets of ZCHP components. Disease targets associated with AS was retrieved from the GEO database. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway analyses were executed using DAVID 6.8. Molecular docking method was employed to evaluate the core target binding to blood components, and animal experiments were performed to test action mechanism.

RESULTS

A ZCHP-components-targets-AS network was constructed by using Cytoscape, included 11 main components and 52 candidate targets. Crucial genes were shown in the protein-protein interaction network, including TNF, IL-1β, IGF1, MMP9, COL1A1, CCR5, HMOX1, PTGS1, SELE, and SYK. KEGG enrichment illustrated that the NF-κB, Fc epsilon RI, and TNF signaling pathways were important for AS treatment. These results were validated by molecular docking. In ApoE-/- mice, ZCHP significantly reduced intima-media thickness, pulse wave velocity, plaque area, and serum lipid levels while increasing the difference between the end-diastolic and end-systolic diameters. Furthermore, ZCHP significantly decreased the mRNA and protein levels of TNF-α and IL-1β, suppressed NF-κB activation, and inhibited the M1 macrophage polarization marker CD86 in ApoE-/- mice.

CONCLUSION

This study combining network pharmacology, molecular biology, and animal experiments showed that ZCHP can alleviate AS by suppressing the TNF/NF-κB axis and M1 macrophage polarization.

Role of trigger receptor 2 expressed on myeloid cells in neuroinflammation－neglected multidimensional regulation of microglia

Neuroinflammation is an inflammatory cascade involved in various neurological disorders, including Alzheimer's disease, multiple sclerosis, and other relevant diseases. The triggering receptor expressed on myeloid cells 2 (TREM2) is a transmembrane immune receptor that is primarily expressed by microglia in the central nervous system (CNS). While TREM2 is initially believed to be an anti-inflammatory factor in the CNS, increasing evidence suggests that TREM2 plays a more complex role in balancing neuroinflammation. However, the exact mechanism remains unclear. Notably, TREM2 directly regulates microglia inflammation through various signaling pathways. Additionally, studies have suggested that TREM2 mediates microglial phagocytosis, autophagy, metabolism, and microglia phenotypes, which may be involved in the modulation of neuroinflammation. In this review, we aim to discuss the critical role of TREM2 in several microglia functions and the underlying molecular mechanism the modulatory which further mediate neuroinflammation, and elaborate. Finally, we discuss the potential of TREM2 as a therapeutic target in neuroinflammatory disorders.

Exploring biomarkers for autophagy-mediated macrophage pyroptosis in atherosclerosis

This study tried to investigate the macrophage autophagy-related pyroptosis in atherosclerosis. The gene expression omnibus (GEO) dataset of GSE100927 was used for differentially expressed genes (DEG) screening, gene ontology (GO) and kyoto encyclopedia of genes and genomes (KEGG), CIBERSORT, weighted correlation network analysis (WGCNA), receiver operating characteristic (ROC), gene set enrichment analysis (GSEA), and correlation analysis, and GSE159677 was used for single-cell analysis, all conducted in R software. Protein-protein interaction (PPI) was constructed in STRING and analyzed in Cytoscape. Transcription factors, drugs, and tissue co-expression network were explored in NetworkAnalyst. A total of 110 autophagy-related DEG (DEATG) were identified, and GO/KEGG revealed the top items enriched in autophagy, phagosome and lysosome. CIBERSORT showed 11 cell types were markedly differentially expressed (p < .05). WGCNA found the turquoise and yellow module were positively correlated with macrophage M0 (corr = 0.5, P = 6e-6) and M2 (corr = 0.54, P = 1e-6), respectively. Then 35 immune-related DEATG were identified, and functional analysis showed immune effector process, interleukin-6 and myeloid cell activation were enriched besides autophagy. PPI and MCC algorithm identified 6 hub genes in regulating macrophage-related autophagy, and ROC indicated high prediction value (area under curve = 0.961). GSEA enriched 6 common pathways associated with autophagy and atherosclerosis pathogenesis, and immune correlation suggested these hub genes were correlated with macrophages M0/M1, monocytes and T cells. Then venn plot found 3 central genes in mediating macrophage autophagy-associated pyroptosis in atherosclerosis, and single-cell analysis demonstrated cell distribution, then validated in THPA human samples. Our data discovered hub genes responsible for macrophage autophagy-mediated pyroptosis in atherosclerosis, and functional analysis with immune cell distribution evidenced their high phenotype-trait prediction value.

Geniposide suppressed OX-LDL-induced osteoblast apoptosis by regulating the NRF2/NF-κB signaling pathway

BACKGROUND

Osteoporosis (OP), due to microarchitectural alterations, is associated with decreased bone mass, declined strength, and increased fracture risk. Increased osteoblast apoptosis contributes to the progression of OP. Natural compounds from herbs provide a rich resource for drug screening. Our previous investigation showed that geniposide (GEN), an effective compound from Eucommia ulmoides, could protect against the pathological development of OP induced by cholesterol accumulation.

METHODS

The rat OP models were duplicated. Dual-energy X-ray absorptiometry, hematoxylin and eosin staining, and immunohistochemistry were used to evaluate bone changes. TUNEL/DAPI staining assays were used for cell apoptosis detection. Protein expression was determined by western blotting assays.

RESULTS

A high-fat diet promoted OP development in vivo, and OX-LDL stimulated osteoblast apoptosis in vitro. GEN exhibited protective activities against OX-LDL-induced osteoblast apoptosis by increasing the NRF2 pathway and decreasing the NF-κB pathway. PDTC, an NF-κB inhibitor, could further promote the biological functions of GEN. In contrast, ML385, an NRF2 inhibitor, might eliminate GEN's protection.

CONCLUSION

GEN suppressed OX-LDL-induced osteoblast apoptosis by regulating the NRF2/NF-κB signaling pathway.

Geniposide ameliorates atherosclerosis by regulating macrophage polarization via perivascular adipocyte-derived CXCL14

ETHNOPHARMACOLOGICAL RELEVANCE

Gardenia jasminoides Ellis is a traditional Chinese medicine that has been used for treatment of various diseases, including atherosclerosis by clearing heat and detoxication. Geniposide is considered as the effective compounds responsible for the therapeutic efficacy of Gardenia jasminoides Ellis against atherosclerosis.

AIM OF THE STUDY

To investigate the effect of geniposide on atherosclerosis burden and plaque macrophage polarization, with focus on its potential impact on CXCL14 expression by perivascular adipose tissue (PVAT).

MATERIALS AND METHODS

ApoE^-/- mice fed a western diet (WD) were used to model atherosclerosis. In vitro cultures of mouse 3T3-L1 preadipocytes and RAW264.7 macrophages were used for molecular assays.

RESULTS

The results revealed that geniposide treatment reduced atherosclerotic lesions in ApoE^-/- mice, and this effect was correlated with increased M2 and decreased M1 polarization of plaque macrophages. Of note, geniposide increased the expression of CXCL14 in PVAT, and both the anti-atherosclerotic effect of geniposide, as well as its regulatory influence on macrophage polarization, were abrogated upon in vivo CXCL14 knockdown. In line with these findings, exposure to conditioned medium from geniposide-treated 3T3-L1 adipocytes (or to recombinant CXCL14 protein) enhanced M2 polarization in interleukin-4 (IL-4) treated RAW264.7 macrophages, and this effect was negated after CXCL14 silencing in 3T3-L1 cells.

CONCLUSION

In summary, our findings suggest that geniposide protects ApoE^-/- mice against WD-induced atherosclerosis by inducing M2 polarization of plaque macrophages via enhanced expression of CXCL14 in PVAT. These data provide novel insights into PVAT paracrine function in atherosclerosis and reaffirm geniposide as a therapeutic drug candidate for atherosclerosis treatment.

TREM2 promotes cholesterol uptake and foam cell formation in atherosclerosis

Disordered lipid accumulation in the arterial wall is a hallmark of atherosclerosis. Previous studies found that the expression of triggering receptor expressed on myeloid cells 2 (TREM2), a transmembrane receptor of the immunoglobulin family, is increased in mouse atherosclerotic aortic plaques. However, it remains unknown whether TREM2 plays a role in atherosclerosis. Here we investigated the role of TREM2 in atherosclerosis using ApoE knockout (ApoE-/-) mouse models, primary vascular smooth muscle cells (SMCs), and bone marrow-derived macrophages (BMDMs). In ApoE-/- mice, the density of TREM2-positive foam cells in aortic plaques increased in a time-dependent manner after the mice were fed a high-fat diet (HFD). Compared with ApoE-/- mice, the Trem2-/-/ApoE-/- double-knockout mice showed significantly reduced atherosclerotic lesion size, foam cell number, and lipid burden degree in plaques after HFD feeding. Overexpression of TREM2 in cultured vascular SMCs and macrophages exacerbates lipid influx and foam cell formation by upregulating the expression of the scavenger receptor CD36. Mechanistically, TREM2 inhibits the phosphorylation of p38 mitogen-activated protein kinase and peroxisome proliferator activated-receptor gamma (PPARγ), thereby increasing PPARγ nuclear transcriptional activity and subsequently promoting the transcription of CD36. Our results indicate that TREM2 exacerbates atherosclerosis development by promoting SMC- and macrophage-derived foam cell formation by regulating scavenger receptor CD36 expression. Thus, TREM2 may act as a novel therapeutic target for the treatment of atherosclerosis.

Phytochemicals targeting lncRNAs: A novel direction for neuroprotection in neurological disorders

Neurological disorders with various etiologies impacting the nervous system are prevalent in clinical practice. Long non-coding RNA (lncRNA) molecules are functional RNA molecules exceeding 200 nucleotides in length that do not encode proteins, but participate in essential activities. Research indicates that lncRNAs may contribute to the pathogenesis of neurological disorders, and may be potential targets for their treatment. Phytochemicals in traditional Chinese herbal medicine (CHM) have been found to exert neuroprotective effects by targeting lncRNAs and regulating gene expression and various signaling pathways. We aim to establish the development status and neuroprotective mechanism of phytochemicals that target lncRNAs through a thorough literature review. A total of 369 articles were retrieved through manual and electronic searches of PubMed, Web of Science, Scopus and CNKI databases from inception to September 2022. The search utilized combinations of natural products, lncRNAs, neurological disorders, and neuroprotective effects as keywords. The included studies, a total of 31 preclinical trials, were critically reviewed to present the current situation and the progress in phytochemical-targeted lncRNAs in neuroprotection. Phytochemicals have demonstrated neuroprotective effects in preclinical studies of various neurological disorders by regulating lncRNAs. These disorders include arteriosclerotic ischemia-reperfusion injury, ischemic/hemorrhagic stroke, Alzheimer's disease, Parkinson's disease, glioma, peripheral nerve injury, post-stroke depression, and depression. Several phytochemicals exert neuroprotective roles through mechanisms such as anti-inflammatory, antioxidant, anti-apoptosis, autophagy regulation, and antagonism of Aβ-induced neurotoxicity. Some phytochemicals targeted lncRNAs and served a neuroprotective role by regulating microRNA and mRNA expression. The emergence of lncRNAs as pathological regulators provides a novel direction for the study of phytochemicals in CHM. Elucidating the mechanism of phytochemicals regulating lncRNAs will help to identify new therapeutic targets and promote their application in precision medicine.

Research progress on the active ingredients of traditional Chinese medicine in the intervention of atherosclerosis: A promising natural immunotherapeutic adjuvant

Atherosclerosis (AS) is a chronic inflammatory disease caused by disorders of lipid metabolism. Abnormal deposition of low-density lipoproteins in the arterial wall stimulates the activation of immune cells, including the adhesion and infiltration of monocytes, the proliferation and differentiation of macrophages and lymphocytes, and the activation of their functions. The complex interplay between immune cells coordinates the balance between pro- and anti-inflammation and plays a key role in the progression of AS. Therefore, targeting immune cell activity may lead to the development of more selective drugs with fewer side effects to treat AS without compromising host defense mechanisms. At present, an increasing number of studies have found that the active ingredients of traditional Chinese medicine (TCM) can regulate the function of immune cells in multiple ways to against AS, showing great potential for the treatment of AS and promising clinical applications. In this paper, we review the mechanisms of immune cell action in AS lesions and the potential targets and/or pathways for immune cell regulation by the active ingredients of TCM to promote the understanding of the immune system interactions of AS and provide a relevant basis for the use of active ingredients of TCM as natural adjuvants for AS immunotherapy.

Natural Monoterpenes as Potential Therapeutic Agents against Atherosclerosis

Traditional herbal medicines based on natural products play a pivotal role in preventing and managing atherosclerotic diseases, which are among the leading causes of death globally. Monoterpenes are a large class of naturally occurring compounds commonly found in many aromatic and medicinal plants. Emerging evidence has shown that monoterpenes have many biological properties, including cardioprotective effects. Remarkably, an increasing number of studies have demonstrated the therapeutic potential of natural monoterpenes to protect against the pathogenesis of atherosclerosis. These findings shed light on developing novel effective antiatherogenic drugs from these compounds. Herein, we provide an overview of natural monoterpenes' effects on atherogenesis and the underlying mechanisms. Monoterpenes have pleiotropic and multitargeted pharmacological properties by interacting with various cell types and intracellular molecular pathways involved in atherogenesis. These properties confer remarkable advantages in managing atherosclerosis, which has been recognized as a multifaceted vascular disease. We also discuss limitations in the potential clinical application of monoterpenes as therapeutic agents against atherosclerosis. We propose perspectives to give new insights into future preclinical research and clinical practice regarding natural monoterpenes.

Molecular Regulation Mechanism of Microglial Autophagy in the Pathology of Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the progressive accumulation of abnormal protein aggregates, neuronal loss, synaptic dysfunction, and neuroinflammation. Microglia are resident macrophages of the central nervous system (CNS). Evidence has shown that impaired microglial autophagy exerts considerable detrimental impact on the CNS, thus contributing to AD pathogenesis. This review highlights the association between microglial autophagy and AD pathology, with a focus on the inflammatory response, defective clearance, and propagation of Aβ and Tau, and synaptic dysfunction. Mechanistically, several lines of research support the roles of microglial receptors in autophagy regulation during AD. In light of accumulating evidence, a strategy for inducing microglial autophagy has great potential in AD drug development.

The Beneficial Effects of Geniposide on Glucose and Lipid Metabolism: A Review

Geniposide is a naturally sourced active ingredient that has diverse pharmacological effects and great potential in improving or treating different kinds of diseases. In recent years, more and more studies have confirmed that geniposide can improve glucose and lipid metabolism disorder, which is an increasingly prevalent health problem causing various metabolic diseases globally. Our review aims to summarize basic information on the pharmacological effects of geniposide on glucolipid metabolism. Geniposide increases glucose utilization and insulin production, protects pancreatic islet β cells, inhibits insulin resistance and hepatic glucose production, and suppresses gluconeogenesis. While in the aspect of lipid metabolism, geniposide can promote lipolysis, inhibit lipogenesis, and regulate lipid transport. Geniposide ameliorates lipid and glucose metabolic disorders, improving the entire glycolipid metabolism network in a three-dimensional manner at the level of molecular mechanism. Growing evidence revealed that geniposide may serve as an effective drug to combat metabolic diseases for the time to come.

Yinchenhao Decoction ameliorates the high-carbohydrate diet induced suppression of immune response in largemouth bass (Micropterus salmoides)

Yinchenhao Decoction (YD), a Chinese herbal medicine, has been traditionally used for treatment of metabolic liver diseases. A 10-week feeding trail was carried out to examine the effects of YD supplementation in a high carbohydrate diet (HCD) on liver histopathology, immune response, disease resistance, and expression of genes associated with endoplasmic reticulum stress, autophagy, apoptosis, necroptosis and inflammation in juvenile largemouth. A diet containing 9% carbohydrate was used as a low carbohydrate diet (LCD), and a HCD was formulated to contain 18% carbohydrate and supplemented with 0, 0.5, 1, 2 or 4% YD (HCD, HCD+0.5YD, HCD+1YD, HCD+2YD and HCD+4YD). Triplicate groups of fish (5.6 ± 0.2 g) were feed the test diets to visual satiety for 10 weeks. The highest survival rate after Nocardia seriolae challenge was recorded for the HCD+4YD group. YD application led to reduced ACP, AKP, AST and ALT activities. HCD-induced cells swelling, ruptured cell membrane, migrated nuclei and increasing inflammatory cells in hepatocytes were mitigated by YD addition. Moreover, YD decreased the expressions of pro-inflammation genes (TNF-α, IL-1β, IL-8, hepcidin1, NF-κB, COX2, CD80 and CD83) and increased the mRNA levels of anti-inflammation genes (IL-10 and IKBα). The mode of liver cell death was preferably changed to programed apoptosis rather than uncontrolled necroptosis by application of YD in HCD. Furthermore, the expression of UPR genes (IRE1, Eif2α, ATF6, XBP1 and GRP78/Bip) and autophagy genes (LC3-2, BNIP3 and P62) was increased by YD supplementation. In summary, our results demonstrated that YD addition in HCD enhances UPR, autophagy and programed apoptosis maintaining the homeostasis, and decreases uncontrolled necroptosis and inflammation, ultimately leading to improved immune response in largemouth bass.

Identification and Validation of TREM2 in Intracranial Aneurysms

Background: Intracranial aneurysm (IA) is a cerebrovascular disease that seriously endangers human heath and life. However, the pathogenesis of IA has not been clarified. Objective: In this study, we explored the role of the triggering receptor expressed on myeloid cells-2 (TREM2) gene to explore a novel mechanism underlying IA. Methods: First, we verified the role of the candidate gene, TREM2 in a modified mouse model of IA. Second, we verified elevated expression of TREM2 using the Gene Expression Omnibus (GEO) database (GSE54083 and GSE75436) and developed protein interaction (PPI) network analysis using the top one hundred DEGs from GSE75436 dataset. Finally, we predicted a likely mechanism by which TREM2 is involved in the pathology of IA using single-gene Gene Set Enrichment Analysis (GSEA). Results: The expression of TREM2 and inflammatory factors was significantly increased in the modified mouse IA model, and showed a positive correlation. Elevated expression of TREM2 was also found in IA patients tissues from the GSE54083 and GSE75436 data sets. PPI network analyses suggested that the DEGs were involved in a variety of inflammatory processes. The GSEA results suggest that TREM2 may participate in IA progression by regulating macrophage function. Conclusion: TREM2 is highly expressed in both human and mouse IA tissues, and may participate in IA progression by regulating macrophage function and inflammatory factor expression. The molecular mechanism of TREM2 involvement in the IA process can be further studied using our modified mouse IA model.

Geniposide Combined With Notoginsenoside R1 Attenuates Inflammation and Apoptosis in Atherosclerosis via the AMPK/mTOR/Nrf2 Signaling Pathway

Inflammation and apoptosis of vascular endothelial cells play a key role in the occurrence and development of atherosclerosis (AS), and the AMPK/mTOR/Nrf2 signaling pathway plays an important role in alleviating the symptoms of AS. Geniposide combined with notoginsenoside R1 (GN combination) is a patented supplement for the prevention and treatment of AS. It has been proven to improve blood lipid levels and inhibit the formation of AS plaques; however, it is still unclear whether GN combination can inhibit inflammation and apoptosis in AS by regulating the AMPK/mTOR/Nrf2 signaling pathway and its downstream signals. Our results confirmed that the GN combination could improve blood lipid levels and plaque formation in ApoE^−/− mice fed with a high-fat diet (HFD), inhibit the secretion of serum inflammatory factors and oxidative stress factors. It also decreased the expression of pyrin domain containing protein 3 (NLRP3) inflammasome-related protein and Bax/Bcl2/caspase-3 pathway-related proteins. At the same time, the GN combination could also inhibit the H₂O₂-induced inflammatory response and apoptosis of human umbilical vein endothelial cells (HUVECs), which is mainly related to the activation of the AMPK/mTOR pathway by GN combination, which in turn induces the activation of Nrf2/HO-1 signal. In addition, the above phenomenon could be significantly reversed by dorsomorphin. Therefore, our experiments proved for the first time that the GN combination can effectively inhibit AS inflammation and apoptosis by activating the AMPK/mTOR/Nrf2 signaling pathway to inhibit the NLRP3 inflammasome and Bax/Bcl2/caspase-3 pathway.

Relationship Between Autophagy and Metabolic Syndrome Characteristics in the Pathogenesis of Atherosclerosis

Atherosclerosis is the main cause of mortality in metabolic-related diseases, including cardiovascular disease and type 2 diabetes (T2DM). Atherosclerosis is characterized by lipid accumulation and increased inflammatory cytokines in the vascular wall, endothelial cell and vascular smooth muscle cell dysfunction and foam cell formation initiated by monocytes/macrophages. The characteristics of metabolic syndrome (MetS), including obesity, glucose intolerance, dyslipidemia and hypertension, may activate multiple mechanisms, such as insulin resistance, oxidative stress and inflammatory pathways, thereby contributing to increased risks of developing atherosclerosis and T2DM. Autophagy is a lysosomal degradation process that plays an important role in maintaining cellular metabolic homeostasis. Increasing evidence indicates that impaired autophagy induced by MetS is related to oxidative stress, inflammation, and foam cell formation, further promoting atherosclerosis. Basal and mild adaptive autophagy protect against the progression of atherosclerotic plaques, while excessive autophagy activation leads to cell death, plaque instability or even plaque rupture. Therefore, autophagic homeostasis is essential for the development and outcome of atherosclerosis. Here, we discuss the potential role of autophagy and metabolic syndrome in the pathophysiologic mechanisms of atherosclerosis and potential therapeutic drugs that target these molecular mechanisms.

A Review of APOE Genotype-Dependent Autophagic Flux Regulation in Alzheimer's Disease

Autophagy is a basic physiological process maintaining cell renewal, the degradation of dysfunctional organelles, and the clearance of abnormal proteins and has recently been identified as a main mechanism underlying the onset and progression of Alzheimer's disease (AD). The APOE ɛ4 genotype is the strongest genetic determinant of AD pathogenesis and initiates autophagic flux at different times. This review synthesizes the current knowledge about the potential pathogenic effects of ApoE4 on autophagy and describes its associations with the biological hallmarks of autophagy and AD from a novel perspective. Via a remarkable variety of widely accepted signaling pathway markers, such as mTOR, TFEB, SIRT1, LC3, p62, LAMP1, LAMP2, CTSD, Rabs, and V-ATPase, ApoE isoforms differentially modulate autophagy initiation; membrane expansion, recruitment, and enclosure; autophagosome and lysosome fusion; and lysosomal degradation. Although the precise pathogenic mechanism varies for different genes and proteins, the dysregulation of autophagic flux is a key mechanism on which multiple pathogenic processes converge.