Lipid homeostasis and the formation of macrophage-derived foam cells in atherosclerosis

Pharmacological mechanisms by which baicalin ameliorates cardiovascular disease

Baicalin is a flavonoid glycoside obtained from the dried root of Scutellaria baicalensis Georgi, which belongs to the Labiatae family. Accumulating evidence indicates that baicalin has favorable therapeutic effects on cardiovascular diseases. Previous studies have revealed the therapeutic effects of baicalin on atherosclerosis, myocardial ischemia/reperfusion injury, hypertension, and heart failure through anti-inflammatory, antioxidant, and lipid metabolism mechanisms. In recent years, some new ideas related to baicalin in ferroptosis, coagulation and fibrinolytic systems have been proposed, and new progress has been made in understanding the mechanism by which baicalin protects cardiomyocytes. However, many relevant underlying mechanisms remain unexplained, and much experimental data is lacking. Therefore, further research is needed to determine these mechanisms. In this review, we summarize the mechanisms of baicalin, which include its anti-inflammatory and antioxidant effects; inhibition of endothelial cell apoptosis; modulation of innate immunity; suppression of vascular smooth muscle cells proliferation, migration, and contraction; regulation of coagulation and fibrinolytic systems; inhibition of myocardial hypertrophy; prevention of myocardial fibrosis; and anti-apoptotic effects on cardiomyocytes.

Antagonism of let-7c reduces atherosclerosis and macrophage lipid accumulation by promoting PGC-1α/LXRα/ABCA1/G1 pathway

Changes in circulating let-7c were significantly associated with the alter in lipid profile, but its role in intracellular lipid metabolism remains unknown. This work was conducted to explore the effects of let-7c on the lipid accumulation in macrophages and uncover the underlying mechanism. Our results showed that let-7c inhibition relieved atherosclerosis progression in apoE-/- mice. In ox-LDL-treatment macrophages, let-7c knockdown suppressed lipid accumulation but does no affect cholesterol intake. Consistent with this, overexpression of let-7c promoted lipid accumulation by reducing the expression of LXRα and ABCA1/G1. Mechanistically, let-7c targeted PGC-1α to repress the expression of LXRα and ABCA1/G1, thereby regulating cholesterol homeostasis in macrophages. Taken together, these findings suggest that antagonism of let-7c reduces atherosclerosis and macrophage lipid accumulation through the PGC-1α/LXRα/ABCA1/G1 axis.

Multiparameter Assessment of Foam Cell Formation Progression Using a Dual-Color Switchable Fluorescence Probe

The assessment of atherosclerosis (AS) progression has emerged as a prominent area of research. Monitoring various pathological features of foam cell (FC) formation is imperative to comprehensively assess AS progression. Herein, a simple benzospiropyran-julolidine-based probe, BSJD, with switchable dual-color imaging ability was developed. This probe can dynamically and reversibly adjust its molecular structure and fluorescent properties in different polar and pH environments. Such a polarity and pH dual-responsive characteristic makes it superior to single-responsive probes in dual-color imaging of lipid droplets (LDs) and lysosomes as well as monitoring their interaction. By simultaneously tracking various pathological features, including LD accumulation and size changes, lysosome dysfunction, and dynamically regulated lipophagy, more comprehensive information can be obtained for multiparameter assessment of FC formation progression. Using BSJD, not only the activation of lipophagy in the early stages and inhibition in the later phases during FC formation are clearly observed but also the important roles of lipophagy in regulating lipid metabolism and alleviating FC formation are demonstrated. Furthermore, BSJD is demonstrated to be capable of rapidly imaging FC plaque sites in AS mice with fast pharmacokinetics. Altogether, BSJD holds great promise as a dual-color organelle-imaging tool for investigating disease-related LD and lysosome changes and their interactions.

Guanidinoacetic acid ameliorates hepatic steatosis and inflammation and promotes white adipose tissue browning in middle-aged mice with high-fat-diet-induced obesity

Guanidinoacetic acid (GAA) is a naturally occurring amino acid derivative that plays a critical role in energy metabolism. In recent years, a growing body of evidence has emerged supporting the importance of GAA in metabolic dysfunction. Hence, we aimed to investigate the effects of GAA on hepatic and adipose tissue metabolism, as well as systemic inflammatory responses in obese middle-aged mice models and attempted to explore the underlying mechanism. We found that dietary supplementation of GAA inhibited inguinal white adipose tissue (iWAT) hypertrophy in high-fat diet (HFD)-fed mice. In addition, GAA supplementation observably decreased the levels of some systemic inflammatory factors, including IL-4, TNF-α, IL-1β, and IL-6. Intriguingly, GAA supplementation ameliorated hepatic steatosis and lipid deposition in HFD-fed mice, which was revealed by decreased levels of TG, TC, LDL-C, PPARγ, SREBP-1c, FASN, ACC, FABP1, and APOB and increased levels of HDL-C in the liver. Moreover, GAA supplementation increased the expression of browning markers and mitochondrial-related genes in the iWAT. Further investigation showed that dietary GAA promoted the browning of the iWAT via activating the AMPK/Sirt1 signaling pathway and might be associated with futile creatine cycling in obese mice. These results indicate that GAA has the potential to be used as an effective ingredient in dietary interventions and thus may play an important role in ameliorating and preventing HFD-induced obesity and related metabolic diseases.

Immuno-modulatory role of baicalin in atherosclerosis prevention and treatment: current scenario and future directions

Atherosclerosis (AS) is recognized as a chronic inflammatory condition characterized by the accumulation of lipids and inflammatory cells within the damaged walls of arterial vessels. It is a significant independent risk factor for ischemic cardiovascular disease, ischemic stroke, and peripheral arterial disease. Despite the availability of current treatments such as statins, proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, and lifestyle modifications for prevention, AS remains a leading cause of morbidity and economic burden worldwide. Thus, there is a pressing need for the development of new supplementary and alternative therapies or medications. Huangqin (Scutellaria baicalensis Georgi. [SBG]), a traditional Chinese medicine, exerts a significant immunomodulatory effect in AS prevention and treatment, with baicalin being identified as one of the primary active ingredients of traditional Chinese medicine. Baicalin offers a broad spectrum of pharmacological activities, including the regulation of immune balance, antioxidant and anti-inflammatory effects, and improvement of lipid metabolism dysregulation. Consequently, it exerts beneficial effects in both AS onset and progression. This review provides an overview of the immunomodulatory properties and mechanisms by which baicalin aids in AS prevention and treatment, highlighting its potential as a clinical translational therapy.

PPARs in atherosclerosis: The spatial and temporal features from mechanism to druggable targets

BACKGROUND

Atherosclerosis is a chronic and complex disease caused by lipid disorder, inflammation, and other factors. It is closely related to cardiovascular diseases, the chief cause of death globally. Peroxisome proliferator-activated receptors (PPARs) are valuable anti-atherosclerosis targets that showcase multiple roles at different pathological stages of atherosclerosis and for cell types at different tissue sites.

AIM OF REVIEW

Considering the spatial and temporal characteristics of the pathological evolution of atherosclerosis, the roles and pharmacological and clinical studies of PPARs were summarized systematically and updated under different pathological stages and in different vascular cells of atherosclerosis. Moreover, selective PPAR modulators and PPAR-pan agonists can exert their synergistic effects meanwhile reducing the side effects, thereby providing novel insight into future drug development for precise spatial-temporal therapeutic strategy of anti-atherosclerosis targeting PPARs.

KEY SCIENTIFIC

Concepts of Review: Based on the spatial and temporal characteristics of atherosclerosis, we have proposed the importance of stage- and cell type-dependent precision therapy. Initially, PPARs improve endothelial cells' dysfunction by inhibiting inflammation and oxidative stress and then regulate macrophages' lipid metabolism and polarization to improve fatty streak. Finally, PPARs reduce fibrous cap formation by suppressing the proliferation and migration of vascular smooth muscle cells (VSMCs). Therefore, research on the cell type-specific mechanisms of PPARs can provide the foundation for space-time drug treatment. Moreover, pharmacological studies have demonstrated that several drugs or compounds can exert their effects by the activation of PPARs. Selective PPAR modulators (that specifically activate gene subsets of PPARs) can exert tissue and cell-specific effects. Furthermore, the dual- or pan-PPAR agonist could perform a better role in balancing efficacy and side effects. Therefore, research on cells/tissue-specific activation of PPARs and PPAR-pan agonists can provide the basis for precision therapy and drug development of PPARs.

Long-term polystyrene nanoplastic exposure disrupt hepatic lipid metabolism and cause atherosclerosis in ApoE-/- mice

Nanoplastics (NPs) exposure is usually linked with abnormal inflammation and oxidative stress, which are high-risk triggers of atherosclerosis; however, whether this exposure causes the development of atherosclerosis is vague. Here, we found that PS NPs co-exposure with ox-LDL induces significant accumulation of lipid, as well as oxidative stress and inflammation in RAW264.7 macrophages. Using an ultrasound biomicroscope (UBM), we observed the emergence of atherosclerotic plaques at the aortic arch of apolipoprotein knockout (ApoE-/-) mice after being exposed to PS NPs for three months. Oil-red O and hematoxylin-eosin (H&E) staining at the mice's aortic root also observed the deposition of lipids with plaque formation. Moreover, the development of atherosclerotic disease is associated with disturbances in lipid metabolism and oxidative stress damage in the mice liver. In conclusion, this study provides additional evidence to further understand the possible cardiovascular damage caused by NPs exposure.

LDL-Binding IL-10 Reduces Vascular Inflammation in Atherosclerotic Mice

Atherosclerosis is a chronic inflammatory disease associated with the accumulation of low-density lipoprotein (LDL) in arterial walls. Higher levels of the anti-inflammatory cytokine IL-10 in serum are correlated with reduced plaque burden. However, cytokine therapies have not translated well to the clinic, partially due to their rapid clearance and pleiotropic nature. Here, we engineered IL-10 to overcome these challenges by hitchhiking on LDL to atherosclerotic plaques. Specifically, we constructed fusion proteins in which one domain is IL-10 and the other is an antibody fragment (Fab) that binds to protein epitopes of LDL. In murine models of atherosclerosis, we show that systemically administered Fab-IL-10 constructs bind circulating LDL and traffic to atherosclerotic plaques. One such construct, 2D03-IL-10, significantly reduces aortic immune cell infiltration to levels comparable to healthy mice, whereas non-targeted IL-10 has no therapeutic effect. Mechanistically, we demonstrate that 2D03-IL-10 preferentially associates with foamy macrophages and reduces pro-inflammatory activation markers. This platform technology can be applied to a variety of therapeutics and shows promise as a potential targeted anti-inflammatory therapy in atherosclerosis.

Bile salt signaling and bile salt-based therapies in cardiometabolic disease

Bile salts have an established role in the emulsification and intestinal absorption of dietary lipids, and their homeostasis is tightly controlled by various transporters and regulators in the enterohepatic circulation. Notably, emerging evidence points toward bile salts as major modulators of cardiometabolic disease (CMD), an umbrella disease of disorders affecting the heart and blood vessels that is caused by systemic metabolic diseases such as Type 2 diabetes mellitus (T2DM) and metabolic dysfunction-associated steatotic liver disease (MASLD), the latter encompassing also metabolic dysfunction-associated steatohepatitis (MASH). The underlying mechanisms of protective effects of bile salts are their hormonal properties, enabling them to exert versatile metabolic effects by activating various bile salt-responsive signaling receptors with the nuclear farnesoid X receptor (FXR) and the Takeda G-protein-coupled receptor 5 (TGR5) as most extensively investigated. Activation of FXR and TGR5 is involved in the regulation of glucose, lipid and energy metabolism, and inflammation. Bile salt-based therapies directly targeting FXR and TGR5 signaling have been evaluated for their therapeutic potential in CMD. More recently, therapeutics targeting bile salt transporters thereby modulating bile salt localization, dynamics, and signaling, have been developed and evaluated in CMD. Here, we discuss the current knowledge on the contribution of bile salt signaling in the pathogenesis of CMD and the potential of bile salt-based therapies for the treatment of CMD.

lncRNA TUG1 as potential novel biomarker for prognosis of cardiovascular diseases

Globally, cardiovascular diseases (CVDs) are among the leading causes of death. In light of the high prevalence and mortality of CVDs, it is imperative to understand the molecules involved in CVD pathogenesis and the signaling pathways that they initiate. This may facilitate the development of more precise and expedient diagnostic techniques, the identification of more effective prognostic molecules and the identification of potential therapeutic targets. Numerous studies have examined the role of lncRNAs, such as TUG1, in CVD pathogenesis in recent years. According to this review article, TUG1 can be considered a biomarker for predicting the prognosis of CVD.

Haemodynamic Effects on the Development and Stability of Atherosclerotic Plaques in Arterial Blood Vessel

Studying the formation and stability of atherosclerotic plaques in the hemodynamic field is essential for understanding the growth mechanism and preventive treatment of atherosclerotic plaques. In this paper, based on a multiplayer porous wall model, we established a two-way fluid-solid interaction with time-varying inlet flow. The lipid-rich necrotic core (LRNC) and stress in atherosclerotic plaque were described for analyzing the stability of atherosclerotic plaques during the plaque growth by solving advection-diffusion-reaction equations with finite-element method. It was found that LRNC appeared when the lipid levels of apoptotic materials (such as macrophages, foam cells) in the plaque reached a specified lower concentration, and increased with the plaque growth. LRNC was positively correlated with the blood pressure and was negatively correlated with the blood flow velocity. The maximum stress was mainly located at the necrotic core and gradually moved toward the left shoulder of the plaque with the plaque growth, which increases the plaque instability and the risk of the plaque shedding. The computational model may contribute to understanding the mechanisms of early atherosclerotic plaque growth and the risk of instability in the plaque growth.

Roles of IL-33 in the Pathogenesis of Cardiac Disorders

Interleukin-33 (IL-33) is a member of the IL-1 cytokine family and is believed to play important roles in different diseases by binding to its specific receptor suppression of tumorigenicity 2 (ST2). In the heart, IL-33 is expressed in different cells including cardiomyocytes, fibroblasts, endothelium, and epithelium. Although many studies have been devoted to investigating the effects of IL-33 on heart diseases, its roles in myocardial injuries remain obscure, and thus further studies are mandatory to unravel the underlying molecular mechanisms. We highlighted the current knowledge of the molecular and cellular characteristics of IL-33 and then summarized its major roles in different myocardial injuries, mainly focusing on infection, heart transplantation, coronary atherosclerosis, myocardial infarction, and diabetic cardiomyopathy. This narrative review will summarize current understanding and insights regarding the implications of IL-33 in cardiac diseases and its diagnostic and therapeutic potential for cardiac disease management.

Tanshinone IIA alleviates atherosclerosis in LDLR-/- mice by regulating efferocytosis of macrophages

Background: Tanshinone IIA (TIIA) is the major lipid-soluble active ingredient of the traditional Chinese medicine Salvia miltiorrhiza, which slows down atherosclerosis (AS). However, it remains unclear whether TIIA has the potential to enhance macrophage efferocytosis and thereby improve atherosclerosis. Objective: The focus of this examination was to determine if TIIA could reduce lipid accumulation and treat AS by enhancing efferocytosis. Methods: Firstly, we conducted in vivo experiments using LDLR knockout (LDLR-/-) mice for a period of 24 weeks, using histopathological staining, immunofluorescence and Western blot experiments to validate from the efficacy and mechanism parts, respectively; in addition, we utilized cells to validate our study again in vitro. The specific experimental design scheme is as follows: In vivo, Western diet-fed LDLR-/- mice for 12 weeks were constructed as an AS model, and normal diet-fed LDLR-/- mice were taken as a blank control group. The TIIA group and positive control group (atorvastatin, ATO) were intervened for 12 weeks by intraperitoneal injection (15 mg/kg/d) and gavage (1.3 mg/kg/d), respectively. In vitro, RAW264.7 cells were cultured with ox-LDL (50 ug/mL) or ox-LDL (50 ug/mL) + TIIA (20 uM/L or 40 uM/L). Pathological changes in aortic plaques and foam cell formation in RAW264.7 cells were evaluated using Masson and Oil Red O staining, respectively. Biochemical methods were used to detect lipid levels in mice. The immunofluorescence assay was performed to detect apoptotic cells and efferocytosis-related signal expression at the plaques. RT-qPCR and Western blot were carried out to observe the trend change of efferocytosis-related molecules in both mouse aorta and RAW264.7 cells. We also used the neutral red assay to assess RAW264.7 cells' phagocytic capacity. Results: Compared with the model group, TIIA decreased serum TC, TG, and LDL-C levels (p < 0.01), reduced the relative lumen area of murine aortic lipid-rich plaques (p < 0.01), enhanced the stability of murine aortic plaques (p < 0.01), reduced ox-LDL-induced lipid build-up in RAW264.7 cells (p < 0.01), and upregulated efferocytosis-related molecules expression and enhance the efferocytosis rate of ox-LDL-induced RAW264.7 cells. Conclusion: TIIA might reduce lipid accumulation by enhancing the efferocytosis of macrophages and thus treat AS.

Which Biomarker(s) Augment the Diagnostic Value of the Positive Exercise Electrocardiography Test: Systemic Inflammatory Index, Plasma Atherogenic Index, or Monocyte/HDL-C Ratio?

The exercise electrocardiography test (EET) is still used before coronary angiography in the diagnosis of chronic coronary syndromes. This study aimed to demonstrate the value of the combination of a positive EET with the systemic inflammatory index (SII), the plasma atherogenic index (PAI), and the monocyte/HDL-C ratio (MHR) in the determination of obstructive coronary artery disease (CAD). This single-center, retrospective study included 540 patients who underwent coronary angiography after ETT. The patients were separated into Group 1, comprising 434 patients with normal coronary arteries and non-obstructive CAD, and Group 2, including 106 with obstructive CAD. In Group 2, the patients were separated into SYNTAX ≤ 22 or ≥23. Glucose, low-density lipoprotein, white blood cells, and MHR were determined to be significantly higher in Group 2 (p < 0.05). According to the multivariate logistic regression analysis, age, gender, diabetes mellitus, and low-density lipoprotein were determined to be independent predictors of CAD. In the ROC curve analysis, a cut-off value of 12 for the MHR in the determination of obstructive CAD had a sensitivity of 60.4% and a specificity of 53.0%. The main result of this study was that a high MHR is an indicator of obstructive CAD in patients with positive EET and suspected CAD.

Biofilms exacerbate atherogenesis through macrophage-induced inflammatory responses in a fibrous plaque microsystem model

BACKGROUND

Microbes have been implicated in atherosclerosis development and progression, but the impact of bacterial-based biofilms on fibrous plaque rupture remains poorly understood.

RESULTS

Here, we developed a comprehensive atherosclerotic model to reflect the progression of fibrous plaque under biofilm-induced inflammation (FP-I). High expressions of biofilm-specific biomarkers algD, pelA and pslB validated the presence of biofilms. Biofilm promotes the polarization of macrophages towards a pro-inflammatory (M1) phenotype, as demonstrated by an increase in M1 macrophage-specific marker CD80 expression in CD68+ macrophages. The increase in the number of intracellular lipid droplets (LDs) and foam cell percentage highlighted the potential role of biofilms on lipid synthesis or metabolic pathways in macrophage-derived foam cells. In addition, collagen I production by myofibroblasts associated with the fibrous cap was significantly reduced along with the promotion of apoptosis of myofibroblasts, indicating that biofilms affect the structural integrity of the fibrous cap and potentially undermine its strength.

CONCLUSION

We validated the unique role of biofilm-based inflammation in exacerbating fibrous plaque damage in the FP-I model, increasing fibrous plaque instability and risk of thrombosis. Our results lay the foundation for mechanistic studies of the role of biofilms in fibrous plaques, allowing the evaluation of preclinical combination strategies for drug therapy.

STATEMENT OF SIGNIFICANCE

A microsystem-based model was developed to reveal interactions in fibrous plaque during biofilm-induced inflammation (FP-I). Real-time assessment of biofilm formation and its role in fibrous plaque progression was achieved. The presence of biofilms enhanced the expression of pro-inflammatory (M1) specific marker CD80, lipid droplets, and foam cells and reduced anti-inflammatory (M2) specific marker CD206 expression. Fibrous plaque exposure to biofilm-based inflammation reduced collagen I expression and increased apoptosis marker Caspase-3 expression significantly. Overall, we demonstrate the unique role of biofilm-based inflammation in exacerbating fibrous plaque damage in the FP-I model, promoting fibrous plaque instability and enhanced thrombosis risk. Our findings lay the groundwork for mechanistic studies, facilitating the evaluation of preclinical drug combination strategies.

Impact of air pollution on cardiovascular aging

The world population is aging rapidly, and by some estimates, the number of people older than 60 will double in the next 30 years. With the increase in life expectancy, adverse effects of environmental exposures start playing a more prominent role in human health. Air pollution is now widely considered the most detrimental of all environmental risk factors, with some studies estimating that almost 20% of all deaths globally could be attributed to poor air quality. Cardiovascular diseases are the leading cause of death worldwide and will continue to account for the most significant percentage of non-communicable disease burden. Cardiovascular aging with defined pathomechanisms is a major trigger of cardiovascular disease in old age. Effects of environmental risk factors on cardiovascular aging should be considered in order to increase the health span and reduce the burden of cardiovascular disease in older populations. In this review, we explore the effects of air pollution on cardiovascular aging, from the molecular mechanisms to cardiovascular manifestations of aging and, finally, the age-related cardiovascular outcomes. We also explore the distinction between the effects of air pollution on healthy aging and disease progression. Future efforts should focus on extending the health span rather than the lifespan.

Surfactant protein A promotes atherosclerosis through mediating macrophage foam cell formation

BACKGROUND

Atherosclerosis is a progressive inflammatory disease where macrophage foam cells play a central role in the pathogenesis. Surfactant protein A (SPA) is a lipid-associating protein involved with regulating macrophage function in various inflammatory diseases. However, the role of SPA in atherosclerosis and macrophage foam cell formation has not been investigated.

METHODS

Primary resident peritoneal macrophages were extracted from wildtype (WT) and SPA deficient (SPA -/- ) mice to determine the functional effects of SPA in macrophage foam cell formation. SPA expression was assessed in healthy vessels and atherosclerotic aortic tissue from the human coronary artery and WT or apolipoprotein e-deficient (ApoE -/- ) mice brachiocephalic arteries fed high fat diets (HFD) for 4 weeks. Hypercholesteremic WT and SPA -/- mice fed a HFD for 6 weeks were investigated for atherosclerotic lesions in vivo .

RESULTS

In vitro experiments revealed that global SPA deficiency reduced intracellular cholesterol accumulation and macrophage foam cell formation. Mechanistically, SPA -/- dramatically decreased CD36 cellular and mRNA expression. SPA expression was increased in atherosclerotic lesions in humans and ApoE -/- mice. In vivo SPA deficiency attenuated atherosclerosis and reduced the number of lesion-associated macrophage foam cells.

CONCLUSIONS

Our results elucidate that SPA is a novel factor for atherosclerosis development. SPA enhances macrophage foam cell formation and atherosclerosis through increasing scavenger receptor cluster of differentiation antigen 36 (CD36) expression.

Sesquiterpenoids from the Florets of Carthamus tinctorius (Safflower) and Their Anti-Atherosclerotic Activity

(1) Background: The florets of Carthamus tinctorius L. are traditionally used as a blood-activating drug and can be used for the treatment of atherosclerosis, but no compounds with anti-atherosclerotic activity have been reported. (2) Methods: This study investigated the chemical compounds from the florets of C. tinctorius. Comprehensive spectroscopic techniques revealed their structures, and ECD calculations established their absolute configurations. Nile Red staining, Oil Red O staining, and cholesterol assessment were performed on these compounds and their aglycones for the inhibitory activity against the formation of foam cells induced by oxidized low-density lipoprotein (ox-LDL) in RAW264.7 macrophages. In addition, RAW264.7 macrophages were tested for their anti-inflammatory activity by measuring the inhibition of NO production caused by LPS. (3) Results: Five new sesquiterpenoids (1-5) isolated from the florets of C. tinctorius were identified as (-)-(1R,4S,9S,11R)-caryophyll-8(13)-en-14-ol-5-one (1), (+)-(1R,4R,9S,11R)-caryophyll-8(13)-en-14-ol-5-one (2), (-)-(3Z,1R,5S,8S,9S,11R)-5,8-epoxycaryophyll-3-en-14-O-β-D-glucopyranoside (3), (+)-(1S,7R,10S)-guai-4-en-3-one-11-O-β-D-fucopyranoside (4), and (-)-(2R,5R,10R)-vetispir-6-en-8-one-11-O-β-D-fucopyranoside (5). All compounds except for compound 3 reduced the lipid content in ox-LDL-treated RAW264.7 cells. Compounds 3 and 4 and their aglycones were found to reduce the level of total cholesterol (TC) and free cholesterol (FC) in ox-LDL-treated RAW264.7 cells. However, no compounds showed anti-inflammatory activity. (4) Conclusion: Sesquiterpenoids from C. tinctorius help to decrease the content of lipids, TC and FC in RAW264.7 cells, but they cannot inhibit NO production, which implies that their anti-atherogenic effects do not involve the inhibition of inflammation.

Advances in imaging and treatment of atherosclerosis based on organic nanoparticles

Atherosclerosis, a systemic chronic inflammatory disease, can lead to thrombosis and vascular occlusion, thereby inducing a series of serious vascular diseases. Currently, distinguishing unstable plaques early and achieving more effective treatment are the two main clinical concerns in atherosclerosis. Organic nanoparticles have great potential in atherosclerotic imaging and treatment, showing superior biocompatibility, drug-loading capacity, and synthesis. This article illustrates the process of atherosclerosis onset and the key targeted cells, then systematically summarizes recent progress made in organic nanoparticle-based imaging of different types of targeted cells and therapeutic methods for atherosclerosis, including optical and acoustic-induced therapy, drug delivery, gene therapy, and immunotherapy. Finally, we discuss the major impediments that need to be addressed in future clinical practice. We believe this article will help readers to develop a comprehensive and in-depth understanding of organic nanoparticle-based atherosclerotic imaging and treatment, thus advancing further development of anti-atherosclerosis therapies.

Microglia and Cholesterol Handling: Implications for Alzheimer's Disease

Cholesterol is essential for brain function and structure, however altered cholesterol metabolism and transport are hallmarks of multiple neurodegenerative conditions, including Alzheimer's disease (AD). The well-established link between apolipoprotein E (APOE) genotype and increased AD risk highlights the importance of cholesterol and lipid transport in AD etiology. Whereas more is known about the regulation and dysregulation of cholesterol metabolism and transport in neurons and astrocytes, less is known about how microglia, the immune cells of the brain, handle cholesterol, and the subsequent implications for the ability of microglia to perform their essential functions. Evidence is emerging that a high-cholesterol environment, particularly in the context of defects in the ability to transport cholesterol (e.g., expression of the high-risk APOE4 isoform), can lead to chronic activation, increased inflammatory signaling, and reduced phagocytic capacity, which have been associated with AD pathology. In this narrative review we describe how cholesterol regulates microglia phenotype and function, and discuss what is known about the effects of statins on microglia, as well as highlighting areas of future research to advance knowledge that can lead to the development of novel therapies for the prevention and treatment of AD.

LRPPRC inhibits autophagy and promotes foam cell formation in atherosclerosis

Lipid-laden macrophages are considered as the main source of foam cells in atherosclerosis; however, the mechanism for macrophage foam cell formation remains unknown. Here, we explore the mechanism behind foam cell formation to potentially identify a novel treatment for atherosclerosis. Our data demonstrated that leucine-rich pentatricopeptide repeat-containing protein (LRPPRC) increased in the atherosclerotic plaques of LDLR^-/- mice fed with a Western diet. LRPPRC was also upregulated in mice peritoneal macrophages and RAW 264.7 cells treated with oxidative low density lipoprotein, whereas knockdown of LRPPRC by transfecting with small interfering (Si)-LRPPRC in RAW 264.7 cells decreased foam cell formation. Furthermore, Si-LRPPRC promoted autophagy and increased the expression of cholesterol efflux protein ATP-binding cassette transporter A1 in RAW 264.7 cells. Moreover, intervention with MHY1485 in RAW 264.7 cells revealed that autophagy was inhibited by LRPPRC via the Akt-mechanistic target of rapamycin pathway. Taken together, we confirm for the first time that LRPPRC is increased within the atherosclerotic plaques of mice and enhances the process of foam cell formation. The knockdown of LRPPRC inhibited foam cell formation by activating macrophage autophagy. Our findings indicate that the regulation of macrophage LRPPRC expression may be a novel strategy for ameliorating atherosclerosis.

Alveolar macrophage metabolic programming via a C-type lectin receptor protects against lipo-toxicity and cell death

Alveolar macrophages (AM) hold lung homeostasis intact. In addition to the defense against inhaled pathogens and deleterious inflammation, AM also maintain pulmonary surfactant homeostasis, a vital lung function that prevents pulmonary alveolar proteinosis. Signals transmitted between AM and pneumocytes of the pulmonary niche coordinate these specialized functions. However, the mechanisms that guide the metabolic homeostasis of AM remain largely elusive. We show that the NK cell-associated receptor, NKR-P1B, is expressed by AM and is essential for metabolic programming. Nkrp1b^-/- mice are vulnerable to pneumococcal infection due to an age-dependent collapse in the number of AM and the formation of lipid-laden AM. The AM of Nkrp1b^-/- mice show increased uptake but defective metabolism of surfactant lipids. We identify a physical relay between AM and alveolar type-II pneumocytes that is dependent on pneumocyte Clr-g expression. These findings implicate the NKR-P1B:Clr-g signaling axis in AM-pneumocyte communication as being important for maintaining metabolism in AM.

Retinoic Acid Receptor Alpha (RARα) in Macrophages Protects from Diet-Induced Atherosclerosis in Mice

Retinoic acid signaling plays an important role in regulating lipid metabolism and inflammation. However, the role of retinoic acid receptor alpha (RARα) in atherosclerosis remains to be determined. In the current study, we investigated the role of macrophage RARα in the development of atherosclerosis. Macrophages isolated from myeloid-specific Rarα-/- (RarαMac-/-) mice showed increased lipid accumulation and inflammation and reduced cholesterol efflux compared to Rarαfl/fl (control) mice. All-trans retinoic acid (AtRA) induced ATP-binding cassette subfamily A member 1 (Abca1) and Abcg1 expression and cholesterol efflux in both RarαMac-/- mice and Rarαfl/fl mice. In Ldlr-/- mice, myeloid ablation of RARα significantly reduced macrophage Abca1 and Abcg1 expression and cholesterol efflux, induced inflammatory genes, and aggravated Western diet-induced atherosclerosis. Our data demonstrate that macrophage RARα protects against atherosclerosis, likely via inducing cholesterol efflux and inhibiting inflammation.

Liposomes trigger bone marrow niche macrophage "foam" cell formation and affect hematopoiesis in mice

Liposomes are the most widely used nanocarrier platform for the delivery of therapeutic and diagnostic agents, and a number of liposomes have been approved for use in clinical practice. After systemic administration, most liposomes are cleared by macrophages in the mononuclear phagocyte system, such as the liver and bone marrow (BM). However, the majority of studies have focused on investigating the therapeutic results of liposomal drugs, and too few studies have evaluated the potential side effects of empty nanocarriers on the functions of macrophages in the mononuclear phagocyte system. Here, we evaluate the potential effects of empty liposomes on the functions of BM niche macrophages. Following liposome administration, we observed lipid droplet (LD) accumulation in cultured primary macrophages and BM niche macrophages. We found that these LD-accumulating macrophages, similar to foam cells, exhibited increased expression of inflammatory cytokines, such as IL-1β and IL-6. We further provided evidence that liposome deposition and degradation induced LD biogenesis on the endoplasmic reticulum membrane and subsequently disturbed endoplasmic reticulum homeostasis and activated the inositol-requiring transmembrane kinase/endoribonuclease 1α/NF-κB signaling pathway, which is responsible for the inflammatory activation of macrophages after liposome engulfment. Finally, we also showed the side effects of dysfunctional BM niche macrophages on hematopoiesis in mice, such as the promotion of myeloid-biased output and impairment of erythropoiesis. This study not only draws attention to the safety of liposomal drugs in clinical practice but also provides new directions for the design of lipid-based drug carriers in preclinical studies.

Three polymethoxyflavones from the peel of Citrus reticulata “Chachi” inhibits oxidized low-density lipoprotein-induced macrophage-derived foam cell formation

Foam cell formation is the hallmark of the development and progression of atherosclerosis. The aim of this study was to investigate the regulatory effects of three polymethoxyflavones (PMFs), namely, tangeretin (TAN), 5,6,7,3′,4′,5′-hexamethoxyflavone (HxMF), and 3,5,6,7,8,3′,4′-heptamethoxyflavone (HpMF) on macrophage-derived foam cell formation and to further explore the molecular mechanisms. The RAW264.7 macrophage-derived foam cell model was successfully induced by oxidized low-density lipoprotein (ox-LDL) (80 μg/ml). It showed that TAN, HxMF, and HpMF alleviated ox-LDL-induced NO release while also inhibiting the expression of IL-1β, IL-6, and TNF-α in RAW264.7 cells. Uptake of excess ox-LDL was inhibited by TAN, HxMF, and HpMF, resulting in the reduction of its foam cell formation. Moreover, TAN, HxMF, and HpMF promoted HDL-mediated cholesterol efflux. Western blot experiment showed that TAN, HxMF, and HpMF inhibited the expression of scavenger receptor class A type I (SRA1) and cluster of differentiation 36 (CD36), while upregulating peroxisome proliferator-activated receptor γ (PPARγ), liver X receptor α (LXRα), phospholipid ATP-binding cassette transporter G1 (ABCG1), and scavenger receptor class B type I (SRB1) expression. Together, our findings suggested that PMFs inhibited foam cell formation might inhibit lipid uptake via downregulating SRA1/CD36 expression and promote cholesterol efflux from foam cells via upregulating PPARγ/LXRα/ABCG1/SRB1 expression. This antiatherosclerotic activity is expected to provide new insights into the development of healthcare uses for PMFs.

Hypoxia signaling in human health and diseases: implications and prospects for therapeutics

Molecular oxygen (O₂) is essential for most biological reactions in mammalian cells. When the intracellular oxygen content decreases, it is called hypoxia. The process of hypoxia is linked to several biological processes, including pathogenic microbe infection, metabolic adaptation, cancer, acute and chronic diseases, and other stress responses. The mechanism underlying cells respond to oxygen changes to mediate subsequent signal response is the central question during hypoxia. Hypoxia-inducible factors (HIFs) sense hypoxia to regulate the expressions of a series of downstream genes expression, which participate in multiple processes including cell metabolism, cell growth/death, cell proliferation, glycolysis, immune response, microbe infection, tumorigenesis, and metastasis. Importantly, hypoxia signaling also interacts with other cellular pathways, such as phosphoinositide 3-kinase (PI3K)-mammalian target of rapamycin (mTOR) signaling, nuclear factor kappa-B (NF-κB) pathway, extracellular signal-regulated kinases (ERK) signaling, and endoplasmic reticulum (ER) stress. This paper systematically reviews the mechanisms of hypoxia signaling activation, the control of HIF signaling, and the function of HIF signaling in human health and diseases. In addition, the therapeutic targets involved in HIF signaling to balance health and diseases are summarized and highlighted, which would provide novel strategies for the design and development of therapeutic drugs.

Novel Indel Variation of NPC1 Gene Associates With Risk of Sudden Cardiac Death

Background and Aims: Sudden cardiac death (SCD) was defined as an unexpected death from cardiac causes during a very short duration. It has been reported that Niemann-Pick type C1 (NPC1) gene mutations might be related to cardiovascular diseases. The purpose of the study is to investigate whether common genetic variants of NPC1 is involved in SCD susceptibility.

Methods: Based on a candidate-gene-based approach and systematic screening strategy, this study analyzed an 8-bp insertion/deletion polymorphism (rs150703258) within downstream of NPC1 for the association with SCD risk in Chinese populations using 158 SCD cases and 524 controls. The association of rs150703258 and SCD susceptibility was analyzed using logistic regression. Genotype-phenotype correlation analysis was performed using public database including 1000G, expression quantitative trait loci (eQTL), and further validated by human heart tissues using PCR. Dual-luciferase assay was used to explore the potential regulatory role of rs150703258. Gene expression profiling interactive analysis and transcription factors prediction were performed.

Results: Logistic regression analysis exhibited that the deletion allele of rs150703258 significantly increased the risk of SCD [odds ratio (OR) = 1.329; 95% confidence interval (95%CI):1.03–1.72; p = 0.0289]. Genotype-phenotype correlation analysis showed that the risk allele was significantly associated with higher expression of NPC1 at mRNA and protein expressions level in human heart tissues. eQTL analysis showed NPC1 and C18orf8 (an adjacent gene to NPC1) are both related to rs150703258 and have higher expression level in the samples with deletion allele. Dual-luciferase activity assays indicate a significant regulatory role for rs150703258. Gene expression profiling interactive analysis revealed that NPC1 and C18orf8 seemed to be co-regulated in human blood, arteries and heart tissues. In silico analysis showed that the rs150703258 deletion variant may create transcription factor binding sites. In addition, a rare 12-bp allele (4-bp longer than the insertion allele) of rs150703258 was discovered in the current cohort.

Conclusion: In summary, our study revealed that rs150703258 might contribute to SCD susceptibility by regulating NPC1 and C18orf8 expression. This indel may be a potential marker for risk stratification and molecular diagnosis of SCD. Validations in different ethnic groups with larger sample size and mechanism explorations are warranted to confirm our findings.

Healthy Immunity on Preventive Medicine for Combating COVID-19

Immunomodulation is influenced by the consumption of nutrients, and healthy immunity is pivotal to defending an individual from a variety of pathogens. The immune system is a network of intricately regulated biological processes that is comprised of many organs, cellular structures, and signaling molecules. A balanced diet, rich in vitamins, minerals, and antioxidants, is key to a strengthened immune system and, thus, crucial to proper functioning of various physiological activities. Conversely, deficiencies of these micronutrients, involving impaired immunity, are linked to numerous health complications, along with a host of pathologies. Coronavirus disease 2019 (COVID-19) is a dangerous infectious disease caused by a β-form of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its genomic variants, which enter host cells upon binding to the angiotensin converting enzyme 2 receptors, and is associated with substantial morbidities and mortalities globally. Patients afflicted with COVID-19 display asymptomatic to severe symptoms, occurrences of which are multifactorial and include diverse immune responses, sex and gender differences, aging, and underlying medical conditions. Geriatric populations, especially men in comparison to women, regardless of their states, are most vulnerable to severe COVID-19-associated infections and complications, with fatal outcomes. Advances in genomic and proteomic technologies help one understand molecular events, including host–pathogen interactions and pathogenesis of COVID-19 and, subsequently, have developed a variety of preventive measures urgently, ranging from mask wearing to vaccination to medication. Despite these approaches, no unique strategy is available today that can effectively prevent and/or treat this hostile disease. As a consequence, the maintenance of a boosted immune system could be considered a high priority of preventive medicine for combating COVID-19. Herein, we discuss the current level of understanding underlining the contribution of healthy immunity and its relevance to COVID-19 molecular pathogenesis, and potential therapeutic strategies, in the management of this devastating disease.

Atherosclerosis: nexus of vascular dynamics and cellular cross talks

Cardiovascular diseases (CVDs) are the foremost cause of mortality worldwide. Atherosclerosis is the underlying pathology behind CVDs. Atherosclerosis is manifested predominantly by lipid deposition, plaque formation, and inflammation in vascular intima. Initiation and progression of plaque require many years. With aging, atherosclerotic plaques become vulnerable. Localization of these plaques in the coronary artery leads to myocardial infarction. A complete understanding of the pathophysiology of this multifaceted disease is necessary to achieve the clinical goal to provide early diagnosis and the best therapeutics. The triggering factors of atherosclerosis are biomechanical forces, hyperlipidemia, and chronic inflammatory response. The current review focuses on crucial determinants involved in the disease, such as location, hemodynamic factors, oxidation of low-density lipoproteins, and the role of endothelial cells, vascular smooth muscle cells, and immune cells, and better therapeutic targets.

USP14: Structure, Function, and Target Inhibition

Ubiquitin-specific protease 14 (USP14), a deubiquitinating enzyme (DUB), is associated with proteasomes and exerts a dual function in regulating protein degradation. USP14 protects protein substrates from degradation by removing ubiquitin chains from proteasome-bound substrates, whereas promotes protein degradation by activating the proteasome. Increasing evidence have shown that USP14 is involved in several canonical signaling pathways, correlating with cancer, neurodegenerative diseases, autophagy, immune responses, and viral infections. The activity of USP14 is tightly regulated to ensure its function in various cellular processes. Structural studies have demonstrated that free USP14 exists in an autoinhibited state with two surface loops, BL1 and BL2, partially hovering above and blocking the active site cleft binding to the C-terminus of ubiquitin. Hence, both proteasome-bound and phosphorylated forms of USP14 require the induction of conformational changes in the BL2 loop to activate its deubiquitinating function. Due to its intriguing roles in the stabilization of disease-causing proteins and oncology targets, USP14 has garnered widespread interest as a therapeutic target. In recent years, significant progress has been made on identifying inhibitors targeting USP14, despite the complexity and challenges in improving their selectivity and affinity for USP14. In particular, the crystal structures of USP14 complexed with IU1-series inhibitors revealed the underlying allosteric regulatory mechanism and enabled the further design of potent inhibitors. In this review, we summarize the current knowledge regarding the structure, regulation, pathophysiological function, and selective inhibition of USP14, including disease associations and inhibitor development.

DNA Microarray-Based Global Gene Expression Profiling in Human Amniotic Epithelial Cells Predicts the Potential of Microalgae-Derived Squalene for the Nervous System and Metabolic Health

In recent years, perinatal stem cells, such as human amniotic epithelial cells (hAECs), have attracted increasing interest as a novel tool of stem cell-based high-throughput drug screening. In the present study, we investigated the bioactivities of squalene (SQ) derived from ethanol extract (99.5%) of a microalgae Aurantiochytrium Sp. (EEA-SQ) in hAECs using whole-genome DNA microarray analysis. Tissue enrichment analysis showed that the brain was the most significantly enriched tissue by the differentially expressed genes (DEGs) between EEA-SQ-treated and control hAECs. Further gene set enrichment analysis and tissue-specific functional analysis revealed biological functions related to nervous system development, neurogenesis, and neurotransmitter modulation. Several adipose tissue-specific genes and functions were also enriched. Gene-disease association analysis showed nervous system-, metabolic-, and immune-related diseases were enriched. Altogether, our study suggests the potential health benefits of microalgae-derived SQ and we would further encourage investigation in EEA-SQ and its derivatives as potential therapeutics for nervous system- and metabolism-related diseases.

CISD1 protects against atherosclerosis by suppressing lipid accumulation and inflammation via mediating Drp1

Atherosclerosis still remains the leading cause of morbidity and mortality worldwide, and deeper understanding of target signaling that protect from the atherosclerosis progression may provide novel therapeutic strategies. CDGSH iron-sulfur domain-containing protein 1 (CISD1) is a protein localized on the outer membrane of mitochondria, and plays key roles in regulating cell death and oxidative stress. However, its potential on atherosclerosis development and the underlying mechanisms are largely unknown. Here, in our study, we found markedly decreased CISD1 expression in lipid-laden THP1 macrophages. Notably, lentivirus (LV)-mediated CISD1 over-expression remarkably ameliorated lipid deposition in macrophages stimulated by ox-LDL. Furthermore, cellular total ROS and mitochondrial ROS generation, and impairment of mitochondrial membrane potential (MMP) were highly induced by ox-LDL in THP1 cells, while being considerably reversed upon CISD1 over-expression. Inflammatory response caused by ox-LDL was also significantly restrained in macrophages with CISD1 over-expression. Mechanistically, we found that CISD1 could interact with dynamin-related protein 1 (Drp1). Intriguingly, CISD1-improved mitochondrial dysfunction and inflammation in ox-LDL-treated macrophages were strongly abolished by Drp1 over-expression, indicating that Drp1 suppression might be necessary for CISD1 to perform its protective effects in vitro. In high fat diet (HFD)-fed apolipoprotein E-deficient (ApoE-/-) mice, tail vein injection of lentiviral vector expressing CISD1 remarkably decreased atherosclerotic lesion area, serum LDL cholesterol levels and triglyceride contents. Inflammatory response, cellular total and mitochondrial ROS production, and Drp1 expression levels in aorta tissues were also dramatically ameliorated in HFD-fed ApoE-/- mice, contributing to the inhibition of atherosclerosis in vivo. Therefore, improving CISD1 expression may be a novel therapeutic strategy for atherosclerosis treatment.

Endonuclease V Regulates Atherosclerosis Through C-C Motif Chemokine Ligand 2-Mediated Monocyte Infiltration

Background

In cardiovascular diseases, atherosclerotic disorder are the most frequent and important with respect to morbidity and mortality. Inflammation mediated by immune cells is central in all parts of the atherosclerotic progress, and further understanding of the underlying mechanisms is needed. Growing evidence suggests that deamination of adenosine‐to‐inosine in RNA is crucial for a correct immune response; nevertheless, the role of adenosine‐to‐inosine RNA editing in atherogenesis has barely been studied. Several proteins have affinity for inosines in RNA, one being ENDOV (endonuclease V), which binds and cleaves RNA at inosines. Data on ENDOV in atherosclerosis are lacking.

Methods and Results

Quantitative polymerase chain reaction on ENDOV mRNA showed an increased level in human carotid atherosclerotic plaques compared with control veins. Inosine‐ribonuclease activity as measured by an enzyme activity assay is detected in immune cells relevant for the atherosclerotic process. Abolishing EndoV in atherogenic apolipoprotein E‐deficient (ApoE^−/−) mice reduces the atherosclerotic plaque burden, both in size and lipid content. In addition, in a brain stroke model, mice without ENDOV suffer less damage than control mice. Finally, lack of EndoV reduces the recruitment of monocytes to atherosclerotic lesions in atherogenic ApoE^−/− mice.

Conclusions

ENDOV is upregulated in human atherosclerotic lesions, and data from mice suggest that ENDOV promotes atherogenesis by enhancing the monocyte recruitment into the atherosclerotic lesion, potentially by increasing the effect of CCL2 activation on these cells.

Inhibition of miR-200b-3p alleviates lipid accumulation and promotes cholesterol efflux by targeting ABCA1 in macrophage-derived foam cells

Atherosclerosis (As) is a chronic cardiovascular disease characterized by abnormal of lipid accumulation and cholesterol efflux. The present study aimed to investigate whether the micro-RNA (miR)-200b-3p could exacerbate As by promoting lipid accumulation and inhibiting cholesterol efflux via ATP-binding cassette transporter A1 (ABCA1) in macrophage-derived foam cells. Blood samples from 30 patients with As and 30 healthy people were collected at Quanzhou First Hospital. RAW264.7 cells were used to establish foam cells using oxidized low-density lipoprotein. The expression of miR-200b-3p and ABCA1 was evaluated by reverse transcription quantitative PCR and western blotting. Lipid accumulation was analyzed by Oil Red O staining and cholesterol content was assessed by ELISA. A targeting relationship between miR-200b-3p and ABCA1 was demonstrated by luciferase reporter assays. Compared with healthy volunteers and RAW264.7 cells, the expression level of miR-200b-3p was significantly increased whereas the expression level of ABCA1 was significantly decreased in patients with As and foam cells. Furthermore, miR-200b-3p expression was negatively correlated with ABCA1 expression in the blood of the patients with As. Lipid content was significantly decreased and cholesterol efflux was significantly increased in foam cells transfected with the miR-200b-3p inhibitor compared with inhibitor control cells. In addition, ABCA1 was shown to be targeted by miR-200b-3p. Furthermore, the lipid content in foam cells transfected with the miR-200b-3p inhibitor and small interfering-ABCA1 was significantly increased, while the cholesterol efflux was significantly decreased compared with foam cells transfected with the miR-200b-3p inhibitor. In conclusion, the findings from the present study indicated that inhibition of miR-200b-3p may alleviate lipid accumulation and promote cholesterol efflux by targeting ABCA1 in macrophage-derived foam cells.

Identification of prognostic lipid droplet-associated genes in pancreatic cancer patients via bioinformatics analysis

BACKGROUND

Pancreatic cancer is the fourth leading cause of cancer deaths in the United States both in females and in males, and is projected to become the second deadliest cancer by 2030. The overall 5-year survival rate remains at around 10%. Cancer metabolism and specifically lipid metabolism plays an important role in pancreatic cancer progression and metastasis. Lipid droplets can not only store and transfer lipids, but also act as molecular messengers, and signaling factors. As lipid droplets are implicated in reprogramming tumor cell metabolism and in invasion and migration of pancreatic cancer cells, we aimed to identify lipid droplet-associated genes as prognostic markers in pancreatic cancer.

METHODS

We performed a literature search on review articles related to lipid droplet-associated proteins. To select relevant lipid droplet-associated factors, bioinformatics analysis on the GEPIA platform (data are publicly available) was carried out for selected genes to identify differential expression in pancreatic cancer versus healthy pancreatic tissues. Differentially expressed genes were further analyzed regarding overall survival of pancreatic cancer patients.

RESULTS

65 factors were identified as lipid droplet-associated factors. Bioinformatics analysis of 179 pancreatic cancer samples and 171 normal pancreatic tissue samples on the GEPIA platform identified 39 deferentially expressed genes in pancreatic cancer with 36 up-regulated genes (ACSL3, ACSL4, AGPAT2, BSCL2, CAV1, CAV2, CAVIN1, CES1, CIDEC, DGAT1, DGAT2, FAF2, G0S2, HILPDA, HSD17B11, ICE2, LDAH, LIPE, LPCAT1, LPCAT2, LPIN1, MGLL, NAPA, NCEH1, PCYT1A, PLIN2, PLIN3, RAB5A, RAB7A, RAB8A, RAB18, SNAP23, SQLE, VAPA, VCP, VMP1) and 3 down-regulated genes (FITM1, PLIN4, PLIN5). Among 39 differentially expressed factors, seven up-regulated genes (CAV2, CIDEC, HILPDA, HSD17B11, NCEH1, RAB5A, and SQLE) and two down-regulation genes (BSCL2 and FITM1) were significantly associated with overall survival of pancreatic cancer patients. Multivariate Cox regression analysis identified CAV2 as the only independent prognostic factor.

CONCLUSIONS

Through bioinformatics analysis, we identified nine prognostic relevant differentially expressed genes highlighting the role of lipid droplet-associated factors in pancreatic cancer.

CTRP12 ameliorates atherosclerosis by promoting cholesterol efflux and inhibiting inflammatory response via the miR-155-5p/LXRα pathway

C1q tumor necrosis factor-related protein 12 (CTRP12), a conserved paralog of adiponectin, is closely associated with cardiovascular disease. However, little is known about its role in atherogenesis. The aim of this study was to examine the influence of CTRP12 on atherosclerosis and explore the underlying mechanisms. Our results showed that lentivirus-mediated CTRP12 overexpression inhibited lipid accumulation and inflammatory response in lipid-laden macrophages. Mechanistically, CTRP12 decreased miR-155-5p levels and then increased its target gene liver X receptor α (LXRα) expression, which increased ATP binding cassette transporter A1 (ABCA1)- and ABCG1-dependent cholesterol efflux and promoted macrophage polarization to the M2 phenotype. Injection of lentiviral vector expressing CTRP12 decreased atherosclerotic lesion area, elevated plasma high-density lipoprotein cholesterol levels, promoted reverse cholesterol transport (RCT), and alleviated inflammatory response in apolipoprotein E-deficient (apoE-/-) mice fed a Western diet. Similar to the findings of in vitro experiments, CTRP12 overexpression diminished miR-155-5p levels but increased LXRα, ABCA1, and ABCG1 expression in the aortas of apoE-/- mice. Taken together, these results suggest that CTRP12 protects against atherosclerosis by enhancing RCT efficiency and mitigating vascular inflammation via the miR-155-5p/LXRα pathway. Stimulating CTRP12 production could be a novel approach for reducing atherosclerosis.

TFEB: A Emerging Regulator in Lipid Homeostasis for Atherosclerosis

Atherosclerosis, predominantly characterized by the disturbance of lipid homeostasis, has become the main causation of various cardiovascular diseases. Therefore, there is an urgent requirement to explore efficacious targets that act as lipid modulators for atherosclerosis. Transcription factor EB (TFEB), whose activity depends on post-translational modifications, such as phosphorylation, acetylation, SUMOylation, ubiquitination, etc., is significant for normal cell physiology. Recently, increasing evidence implicates a role of TFEB in lipid homeostasis, via its functionality of promoting lipid degradation and efflux through mediating lipophagy, lipolysis, and lipid metabolism-related genes. Furthermore, a regulatory effect on lipid transporters and lipid mediators by TFEB is emerging. Notably, TFEB makes a possible therapeutic target of atherosclerosis by regulating lipid metabolism. This review recapitulates the update and current advances on TFEB mediating lipid metabolism to focus on two intracellular activities: a) how cells perceive external stimuli and initiate transcription programs to modulate TFEB function, and b) how TFEB restores lipid homeostasis in the atherosclerotic process. In-depth research is warranted to develop potent agents against TFEB to alleviate or reverse the progression of atherosclerosis.

Decidua basalis and acute atherosis: Expression of atherosclerotic foam cell associated proteins

INTRODUCTION

Uteroplacental acute atherosis is frequently observed in preeclampsia, and shares features with early atherosclerotic lesions, including artery wall foam cells. The lipid-associated proteins FABP4 (fatty acid binding protein 4), perilipin-2, and LOX-1 (lectin-like oxidized LDL-receptor 1) are involved in atherosclerotic foam cell formation. Increased levels of these proteins have been associated with preeclampsia systemically and in placental tissue. Their role in acute atherosis is yet unidentified. Our aim was to describe the presence of these proteins in acute atherosis, and compare our findings to what is known in early atherosclerotic lesions.

METHODS

Serial sections of decidua basalis tissue from 12 normotensive (4 with acute atherosis) and 23 preeclamptic pregnancies (16 with acute atherosis) were stained with HE and immunostained for CK7, CD68, FABP4, perilipin-2, and LOX-1. Artery wall and perivascular protein expression was assessed in 190 spiral artery sections; 55 with acute atherosis.

RESULTS

Acute atherosis foam cells were commonly positive for perilipin-2 (55%), less often for FABP4 (13%), and never for LOX-1. LOX-1 was frequently observed in intramural trophoblasts of normal spiral arteries. Perivascularly, LOX-1 positivity of decidual stromal cells surrounding arteries with acute atherosis was significantly increased as compared to arteries lacking acute atherosis (38% vs. 15%, p < 0.001).

DISCUSSION

We found that perilipin-2 and FABP4 are expressed by acute atherosis foam cells, similar to atherosclerosis, supporting possible shared pathways for foam cell generation. Unlike atherosclerosis, LOX-1 is not present in acute atherosis, possibly explained by pregnancy-specific routes to decidua basalis foam cell generation.

Downregulation of GSK-3β Expression via Ultrasound-Targeted Microbubble Destruction Enhances Atherosclerotic Plaque Stability in New Zealand Rabbits

Accumulating evidence suggests that atherosclerosis (AS) is the underlying cause of vascular diseases, including heart disease and stroke. Ultrasound-targeted microbubble destruction (UTMD) technology provides a tolerable, efficient and effective system for drug delivery and gene transfection, which has broad application prospects in the treatment of AS. In addition, glycogen synthase kinase (GSK)-3β has been implicated as a potentially valuable therapeutic agent for AS treatment; however, the specific molecular mechanisms remain unknown. Therefore, this study was conducted to explore the effect of downregulation of GSK-3β expression via UTMD on atherosclerotic plaque stability. We established a THP-1 macrophage-derived foam cell model in vitro and an atherosclerotic plaque model in the right common carotid artery of New Zealand rabbits. We determined levels of the relevant vulnerable plaque stability elements. The results indicate that GSK-3β was upregulated in the foam cells and in atherosclerotic rabbits. Downregulation of GSK-3β expression by UTMD suppressed vulnerable plaque factors and inflammation in vitro and in vivo, changed the cytoskeleton of the foam cells in vitro, increased Young's modulus and decreased the peak intensity of atherosclerotic plaque in vivo. Moreover, GSK-3β inhibition by UTMD did not influence the viability of the foam cells. Collectively, our results indicate that GSK-3β could be a potential target for anti-atherogenic interventions and, in particular, can improve the stability of AS plaques in combination with UTMD.

MicroRNA-320b Modulates Cholesterol Efflux and Atherosclerosis

Aim: ATP-binding cassette (ABC) transporters and endonuclease-exonuclease-phosphatase family domain containing 1 (EEPD1) are reported to regulate cellular cholesterol efflux in macrophages. Bioinformatics analysis has revealed that ABCG1 and EEPD1 might be potential targets of microRNA (miR)-320b. This study aimed to elucidate the roles of miR-320b in cholesterol efflux from macrophages and the pathogenesis of atherosclerosis.

Methods: Microarray was conducted to profile microRNA (miRNA) expression, and quantitative real-time PCR (qPCR) was used to validate the differentially expressed miRNAs in peripheral blood mononuclear cells of coronary artery disease (CAD) patients and healthy controls. Luciferase assay was conducted to evaluate the activity of reporter construct containing the 3´-untranslated region (3´-UTR) of target genes. Besides, NBD-cholesterol efflux induced by high-density lipoprotein (HDL) and lipid-free apolipoprotein A1 (apoA1) was detected using fluorescence intensity, respectively. Apoe^−/− mice were injected with adeno-associated virus (AAV)2-miR-320b or control via tail vein, thereafter fed with 14 week atherogenic diet to study the roles of miR-320b in vivo .

Results: MiR-320b was highly expressed in CAD patients compared with that in the healthy controls in both the microarray analysis and qPCR analysis. In vitro study showed that miR-320b decreased HDL- and apoA1-mediated cholesterol efflux from macrophages partly by directly targeting ABCG1 and EEPD1 genes and partly via suppressing the LXRα-ABCA1/G1 pathway. Consistently, in vivo administration of AAV2-miR-320b into Apoe^−/− mice attenuated cholesterol efflux from peritoneal macrophages, which showed reduced expression of ABCA1/G1 and EEPD1, and increased lipid LDL-C level, with a down-regulation of hepatic LDLR and ABCA1. AAV2-miR-320b treatment also increased atherosclerotic plaque size and lesional macrophage content and enhanced pro-inflammatory cytokines levels through the elevated phosphorylation level of nuclear factor-κB p65 in macrophages.

Conclusion: We identify miR-320b as a novel modulator of macrophage cholesterol efflux and that it might be a promising therapeutic target for atherosclerosis treatment.

Cell of all trades: oligodendrocyte precursor cells in synaptic, vascular, and immune function

Oligodendrocyte precursor cells (OPCs) are not merely a transitory progenitor cell type, but rather a distinct and heterogeneous population of glia with various functions in the developing and adult central nervous system. In this review, we discuss the fate and function of OPCs in the brain beyond their contribution to myelination. OPCs are electrically sensitive, form synapses with neurons, support blood-brain barrier integrity, and mediate neuroinflammation. We explore how sex and age may influence OPC activity, and we review how OPC dysfunction may play a primary role in numerous neurological and neuropsychiatric diseases. Finally, we highlight areas of future research.

T cell co-stimulator inducible co-stimulatory (ICOS) exerts potential anti-atherosclerotic roles through downregulation of vascular smooth muscle phagocytosis and proliferation

Background

Atherosclerosis (AS) is a chronic inflammatory disease. The role of the immune system in the etiology of the disease, particularly T cells, has been widely studied and is well established. T cell activation directly regulates co-signaling molecules present in immune synapses. Targeting one or several of these co-signaling molecules can inhibit T cell-mediated inflammation and delay or reduce AS. In recent years, this strategy has increasingly become a research focus. As such, we explored the role and therapeutic potential of the T cell co-stimulatory molecule inducible co-stimulatory (ICOS) in AS.

Methods

We compared the expression of ICOS in early AS lesions occurring in ApoE-deficient (ApoE-KO) rats fed a fat-diet and wild type (WT) rats fed the same diet. Eight-week old ApoE-KO and WT rats [ApoE-KO(0) and WT(0)] were fed a high-fat diet for 16 weeks [ApoE-KO(16) and WT(16)]. ICOS expression in aortic tissues was analyzed by quantitative real-time PCR, western blot, and confocal microscopy. The effect of ICOS overexpression in a transfected human T cell line on the phagocytosis and proliferation of co-cultured human aortic smooth muscle cells (HASMCs) was studied in vitro.

Results

Compared with WT(0), ApoE-KO(0), and WT(16) rats, ICOS expression in ApoE-KO(16) rats was significantly down-regulated both at the mRNA and protein levels. In vitro experiments indicated that ICOS overexpression reduces phagocytosis and proliferation by HASMCs, and may therefore produce an anti-atherosclerotic effect.

Conclusions

The immune synaptic co-signaling molecule ICOS has an anti-atherosclerotic effect through inhibition of HASMC phagocytosis and proliferation, and can be used to delay plaque formation during the early stages of AS.

Cell type-specific lipid storage changes in Parkinson's disease patient brains are recapitulated by experimental glycolipid disturbance

Neurons are dependent on proper trafficking of lipids to neighboring glia for lipid exchange and disposal of potentially lipotoxic metabolites, producing distinct lipid distribution profiles among various cell types of the central nervous system. Little is known of the cellular distribution of neutral lipids in the substantia nigra (SN) of Parkinson's disease (PD) patients and its relationship to inflammatory signaling. This study aimed to determine human PD SN neutral lipid content and distribution in dopaminergic neurons, astrocytes, and microglia relative to age-matched healthy subject controls. The results show that while total neutral lipid content was unchanged relative to age-matched controls, the levels of whole SN triglycerides were correlated with inflammation-attenuating glycoprotein non-metastatic melanoma protein B (GPNMB) signaling in human PD SN. Histological localization of neutral lipids using a fluorescent probe (BODIPY) revealed that dopaminergic neurons and midbrain microglia significantly accumulated intracellular lipids in PD SN, while adjacent astrocytes had a reduced lipid load overall. This pattern was recapitulated by experimental in vivo inhibition of glucocerebrosidase activity in mice. Agents or therapies that restore lipid homeostasis among neurons, astrocytes, and microglia could potentially correct PD pathogenesis and disease progression.

Deubiquitination of CD36 by UCHL1 promotes foam cell formation

Atherosclerosis-associated cardiovascular diseases are main causes leading to high mortality worldwide. Macrophage-derived foam cell formation via uptaking modified lipoproteins is the initial and core step in the process of atherosclerosis. Meanwhile, scavenger receptor is indispensable for the formation of foam cells. UCHL1, a deubiquitinase, has been widely studied in multiple cancers. UCHL1 could be an oncogene or a tumor suppressor in dependent of tumor types. It remains unknown whether UCHL1 influences cellular oxLDL uptake. Herein we show that UCHL1 deletion significantly inhibits lipid accumulation and foam cell formation. Subsequently, we found that UCHL1 inhibitor or siRNA downregulates the expression of CD36 protein whereas SR-A, ABCA1, ABCG1, Lox-1, and SR-B1 have no significant change. Furthermore, the treatment of UCHL1 inhibition increases the abundance of K48-polyubiquitin on CD36 and the suppression of lipid uptake induced by UCHL1 deficiency is attenuated by blocking CD36 activation. Our study concluded that UCHL1 deletion decreases foam cell formation by promoting the degradation of CD36 protein, indicating UCHL1 may be a potential target for atherosclerosis treatment.

Formation and characterization of lipid droplets of the bovine corpus luteum

Establishment and maintenance of pregnancy depends on progesterone synthesized by luteal tissue in the ovary. Our objective was to identify the characteristics of lipid droplets (LDs) in ovarian steroidogenic cells. We hypothesized that LDs are a major feature of steroidogenic luteal cells and store cholesteryl esters. Whole bovine tissues, isolated ovarian steroidogenic cells (granulosa, theca, small luteal, and large luteal), and isolated luteal LDs were assessed for LD content, LD-associated proteins and lipid analyses. Bovine luteal tissue contained abundant lipid droplets, LD-associated perilipins 2/3/5, hormone-sensitive lipase, and 1-acylglycerol-3-phosphate O-acyltransferase ABHD5. Luteal tissue was enriched in triglycerides (TGs) compared to other tissues, except for adipose tissue. Luteal cells were distinguishable from follicular cells by the presence of LDs, LD-associated proteins, and increased TGs. Furthermore, LDs from large luteal cells were numerous and small; whereas, LDs from small luteal cells were large and less numerous. Isolated LDs contained nearly all of the TGs and cholesteryl esters present in luteal tissue. Isolated luteal LDs were composed primarily of TG, with lesser amounts of cholesteryl esters, diglyceride and other phospholipids. Bovine luteal LDs are distinct from LDs in other bovine tissues, including follicular steroidogenic cells.

Bergaptol from blossoms of Citrus aurantium L. var. amara Engl inhibits LPS-induced inflammatory responses and ox-LDL-induced lipid deposition

Aberrant activation of inflammation and excess accumulation of lipids play pivotal roles in atherosclerosis (AS) progression. Constituents from Citrus aurantium Linn variant amara Engl (CAVA) were effectively investigated for their various bioactivities, especially anti-inflammation. Bergaptol (BER) is particularly abundant in Citrus products. Accumulating studies have confirmed its predominant anti-cancer and antioxidant functions, whereas few studies focused on its antiatherogenic functions. In the current study, BER was isolated from CAVA for the first time. Macrophages were stimulated with lipopolysaccharides (LPSs) or oxidized low-density lipoproteins (ox-LDL) to mimic inflammatory responses and AS development. BER treatment significantly inhibited LPS-induced production of nitric oxide (NO), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α), and gene expression of inducible nitric oxide synthase (iNOS), IL-6, TNF-α, interleukin-1 beta (IL-1β) and cyclooxygenase-2 (COX-2). BER also potently blocked LPS-induced mitogen-activated protein kinase (MAPK) phosphorylation and nuclear factor-kappa B (NF-κB) activation, as evidenced by the inhibitory effects on c-Jun N-terminal kinase (JNK), P38, P65, IκBα and IκKα/β phosphorylation, and NF-κB nuclear translocation. Furthermore, BER treatment markedly mitigated ox-LDL-induced foam cell formation by inhibiting scavenger receptor class A type I (SRA1) and cluster of differentiation 36 (CD36)-dependent cholesterol uptake. In conclusion, BER might be a novel therapeutic agent for AS prevention through inhibiting inflammatory responses and cholesterol uptake.

Retinoic acid receptor-related orphan receptor α reduces lipid droplets by upregulating neutral cholesterol ester hydrolase 1 in macrophages

Background

Neutral cholesterol ester hydrolase 1 (NCEH1) catalyzes the hydrolysis of cholesterol ester (CE) in macrophages. Genetic ablation of NCEH1 promotes CE-laden macrophages and the development of atherosclerosis in mice. Dysregulation of NCEH1 levels is involved in the pathogenesis of multiple disorders including metabolic diseases and atherosclerosis; however, relatively little is known regarding the mechanisms regulating NCEH1. Retinoic acid receptor-related orphan receptor α (RORα)-deficient mice exhibit several phenotypes indicative of aberrant lipid metabolism, including dyslipidemia and increased susceptibility to atherosclerosis.

Results

In this study, inhibition of lipid droplet formation by RORα positively regulated NCEH1 expression in macrophages. In mammals, the NCEH1 promoter region was found to harbor putative RORα response elements (ROREs). Electrophoretic mobility shift, chromatin immunoprecipitation, and luciferase reporter assays showed that RORα binds and responds to ROREs in human NCEH1. Moreover, NCEH1 was upregulated through RORα via a phorbol myristate acetate-dependent mechanism during macrophage differentiation from THP1 cells. siRNA-mediated knockdown of RORα significantly downregulated NCEH1 expression and accumulated lipid droplets in human hepatoma cells. In contrast, NCEH1 expression and removal of lipid droplets were induced by RORα agonist treatments and RORα overexpression in macrophages.

Conclusion

These data strongly suggested that NCEH1 is a direct RORα target, defining potential new roles for RORα in the inhibition of lipid droplet formation through NCEH1.