Regulation Of Cholesterol Efflux Research Articles

C1q/Tumor Necrosis Factor-Related Protein-9 Enhances Macrophage Cholesterol Efflux and Improves Reverse Cholesterol Transport via AMPK Activation.

Cholesterol efflux from foam cells in atherosclerotic plaques is crucial for reverse cholesterol transport (RCT), an important antiatherogenic event. ATP-binding cassette (ABC) transporters, ABCA1 and ABCG1, are key receptors in the cholesterol efflux pathway. C1q/tumor necrosis factor-related protein-9 (CTRP9) is a newly discovered adipokine and exhibits an atheroprotective activity. However, the role of CTRP9 in RCT still remains unknown. In this work, we investigated the effect of subcutaneous administration of CTRP9 protein on RCT and atherosclerotic lesion formation in ApoE-/- mice fed with a high-fat diet. CTRP9-dependent regulation of cholesterol efflux and ABC transporters in RAW 264.7 foam cells was determined. Our results showed that CTRP9 protein decreased atherosclerotic lesions, increased cholesterol efflux, and upregulated liver ABCA1 and ABCG1 expression in ApoE-/- mice. CTRP9 treatment dose-dependently increased mRNA and protein expression of ABCA1, ABCG1, and LXR-α in RAW 264.7 foam cells. Moreover, the expression and phosphorylation of AMPK was potentiated upon CTRP9 treatment. Notably, CTRP9-induced cholesterol efflux and upregulation of ABCA, ABCG1, and LXR-α were impaired when AMPK was knocked down. AMPK depletion restored cholesterol accumulation in CTRP9-treated RAW 264.7 cells. Taken together, subcutaneous injection is an effective novel delivery route for CTRP9 protein, and exogenous CTRP9 can facilitate cholesterol efflux and promote RCT in an animal model of atherosclerosis. The atheroprotective activity of CTRP9 is mediated through the activation of AMPK signaling.

Oncolytic adenovirus encoding apolipoprotein A1 suppresses metastasis of triple-negative breast cancer in mice

BackgroundDysregulation of cholesterol metabolism is associated with the metastasis of triple-negative breast cancer (TNBC). Apolipoprotein A1 (ApoA1) is widely recognized for its pivotal role in regulating cholesterol efflux and maintaining cellular cholesterol homeostasis. However, further exploration is needed to determine whether it inhibits TNBC metastasis by affecting cholesterol metabolism. Additionally, it is necessary to investigate whether ApoA1-based oncolytic virus therapy can be used to treat TNBC.MethodsIn vitro experiments and mouse breast cancer models were utilized to evaluate the molecular mechanism of ApoA1 in regulating cholesterol efflux and inhibiting breast cancer progression and metastasis. The gene encoding ApoA1 was inserted into the adenovirus genome to construct a recombinant adenovirus (ADV-ApoA1). Subsequently, the efficacy of ADV-ApoA1 in inhibiting the growth and metastasis of TNBC was evaluated in several mouse models, including orthotopic breast cancer, spontaneous breast cancer, and human xenografts. In addition, a comprehensive safety assessment of Syrian hamsters and rhesus monkeys injected with oncolytic adenovirus was conducted.ResultsThis study found that dysregulation of cholesterol homeostasis is critical for the progression and metastasis of TNBC. In a mouse orthotopic model of TNBC, a high-cholesterol diet promoted lung and liver metastasis, which was associated with keratin 14 (KRT14), a protein responsible for TNBC metastasis. Furthermore, studies have shown that ApoA1, a cholesterol reverse transporter, inhibits TNBC metastasis by regulating the cholesterol/IKBKB/FOXO3a/KRT14 axis. Moreover, ADV-ApoA1 was found to promote cholesterol efflux, inhibit tumor growth, reduce lung metastasis, and prolonged the survival of mice with TNBC. Importantly, high doses of ADV-ApoA1 administered intravenously and subcutaneously were well tolerated in rhesus monkeys and Syrian hamsters.ConclusionsThis study provides a promising oncolytic virus treatment strategy for TNBC based on targeting dysregulated cholesterol metabolism. It also establishes a basis for subsequent clinical trials of ADV-ApoA1 in the treatment of TNBC.

Huayu Qutan Recipe promotes lipophagy and cholesterol efflux through the mTORC1/TFEB/ABCA1-SCARB1 signal axis.

This study aims to investigate the mechanism of the anti-atherosclerosis effect of Huayu Qutan Recipe (HYQT) on the inhibition of foam cell formation. Invivo, the mice were randomly divided into three groups: CTRL group, MOD group and HYQT group. The HYQT group received HYQT oral administration twice a day (20.54 g/kg/d), and the plaque formation in ApoE-/- mice was observed using haematoxylin-eosin (HE) staining and oil red O (ORO) staining. The co-localization of aortic macrophages and lipid droplets (LDs) was examined using fluorescent labelling of CD11b and BODIPY fluorescence probe. Invitro, RAW 264.7 cells were exposed to 50 μg/mL ox-LDL for 48 h and then treated with HYQT for 24 h. The accumulation of LDs was evaluated using ORO and BODIPY. Cell viability was assessed using the CCK-8 assay. The co-localization of LC3b and BODIPY was detected via immunofluorescence and fluorescence probe. LysoTracker Red and BODIPY 493/503 were used as markers for lysosomes and LDs, respectively. Autophagosome formation were observed via transmission electron microscopy. The levels of LC3A/B II/LC3A/B I, p-mTOR/mTOR, p-4EBP1/4EBP1, p-P70S6K/P70S6K and TFEB protein level were examined via western blotting, while SQSTM1/p62, Beclin1, ABCA1, ABCG1 and SCARB1 were examined via qRT-PCR and western blotting. The nuclear translocation of TFEB was detected using immunofluorescence. The components of HYQT medicated serum were determined using Q-Orbitrap high-resolution MS analysis. Molecular docking was employed to identify the components of HYQT medicated serum responsible for the mTOR signalling pathway. The mechanism of taurine was illustrated. HYQT has a remarkable effect on atherosclerotic plaque formation and blood lipid level in ApoE-/- mice. HYQT decreased the co-localization of CD11b and BODIPY. HYQT (10% medicated serum) reduced the LDs accumulation in RAW 264.7 cells. HYQT and RAPA (rapamycin, a mTOR inhibitor) could promote cholesterol efflux, while chloroquine (CQ, an autophagy inhibitor) weakened the effect of HYQT. Moreover, MHY1485 (a mTOR agonist) also mitigated the effects of HYQT by reduced cholesterol efflux. qRT-PCR and WB results suggested that HYQT improved the expression of the proteins ABCA1, ABCG1 and SCARB1.HYQT regulates ABCA1 and SCARB1 protein depending on the mTORC1/TFEB signalling pathway. However, the activation of ABCG1 does not depend on this pathway. Q-Orbitrap high-resolution MS analysis results demonstrated that seven core compounds have good binding ability to the mTOR protein. Taurine may play an important role in the mechanism regulation. HYQT may reduce cardiovascular risk by promoting cholesterol efflux and degrading macrophage-derived foam cell formation. It has been observed that HYQT and ox-LDL regulate lipophagy through the mTOR/TFEB signalling pathway, rather than the mTOR/4EBP1/P70S6K pathway. Additionally, HYQT is found to regulate cholesterol efflux through the mTORC1/TFEB/ABCA1-SCARB1 signal axis, while taurine plays a significant role in lipophagy.

ANGPTL3 is a novel HDL component that regulates HDL function

BackgroundAngiopoietin-like protein 3 (ANGPTL3) is secreted by hepatocytes and inhibits lipoprotein lipase and endothelial lipase activity. Previous studies reported the correlation between plasma ANGPTL3 levels and high-density lipoprotein (HDL). Recently ANGPTL3 was found to preferentially bind to HDL in healthy human circulation. Here, we examined whether ANGPTL3, as a component of HDL, modulates HDL function and affects HDL other components in human and mice with non-diabetes or type 2 diabetes mellitus.MethodsHDL was isolated from the plasma of female non-diabetic subjects and type-2 diabetic mellitus (T2DM) patients. Immunoprecipitation, western blot, and ELISA assays were used to examine ANGPTL3 levels in HDL. Db/m and db/db mice, AAV virus mediated ANGPTL3 overexpression and knockdown models and ANGPTL3 knockout mice were used. The cholesterol efflux capacity induced by HDL was analyzed in macrophages preloaded with fluorescent cholesterol. The anti-inflammation capacity of HDL was assessed using flow cytometry to measure VCAM-1 and ICAM-1 expression levels in TNF-α-stimulated endothelial cells pretreated with HDL.ResultsANGPTL3 was found to bind to HDL and be a component of HDL in both non-diabetic subjects and T2DM patients. Flag-ANGPTL3 was found in the HDL of transgenic mice overexpressing Flag-ANGPTL3. ANGPLT3 of HDL was positively associated with cholesterol efflux in female non-diabetic controls (r = 0.4102, p = 0.0117) but not in female T2DM patients (r = − 0.1725, p = 0.3224). Lower ANGPTL3 levels of HDL were found in diabetic (db/db) mice compared to control (db/m) mice and were associated with reduced cholesterol efflux and inhibition of VCAM-1 and ICAM-1 expression in endothelial cells (p < 0.05 for all). Following AAV-mediated ANGPTL3 cDNA transfer in db/db mice, ANGPTL3 levels were found to be increased in HDL, and corresponded to increased cholesterol efflux and decreased ICAM-1 expression. In contrast, knockdown of ANGPTL3 levels in HDL by AAV-mediated shRNA transfer led to a reduction in HDL function (p < 0.05 for both). Plasma total cholesterol, total triglycerides, HDL-c, protein components of HDL and the cholesterol efflux function of HDL were lower in ANGPTL3−/− mice than ANGPTL3+/+ mice, suggesting that ANGPTL3 in HDL may regulate HDL function by disrupting the balance of protein components in HDL.ConclusionANGPTL3 was identified as a component of HDL in humans and mice. ANGPTL3 of HDL regulated cholesterol efflux and the anti-inflammatory functions of HDL in T2DM mice. Both the protein components of HDL and cholesterol efflux capacity of HDL were decreased in ANGPTL3−/− mice. Our findings suggest that ANGPTL3 in HDL may regulate HDL function by disrupting the balance of protein components in HDL. Our study contributes to a more comprehensive understanding of the role of ANGPTL3 in lipid metabolism.

The ability and optimal cutoff value of serum cell division cycle 42 in estimating major adverse cardiac event in STEMI patients treated with percutaneous coronary intervention.

Cell division cycle 42 (CDC42) regulates cholesterol efflux, chronic inflammation, and reendothelialization in various atherosclerotic diseases. This study aimed to investigate the correlation of serum CDC42 with myocardial injury indicators and major adverse cardiac event (MACE) in ST-elevation myocardial infarction (STEMI) patients who were treated with percutaneous coronary intervention (PCI). In 250 STEMI patients about to receive PCI, serum samples were collected at enrollment before PCI treatment, and the serum samples were also obtained from 100 healthy controls (HCs) at enrollment. Serum CDC42 was detected by enzyme-linked immunosorbent assay. Serum CDC42 was decreased (versus HCs, P < 0.001) and negatively correlated with diabetes mellitus (P = 0.017), multivessel disease (P = 0.016), cardiac troponin I (P < 0.001), creatine kinase MB (P = 0.012), stent diameter ≥ 3.5mm (P = 0.039), white blood cell (P < 0.001), low-density lipoprotein cholesterol (P = 0.049), and C-reactive protein (P < 0.001) in STEMI patients. Besides, 29 (11.6%) STEMI patients experienced MACE. The 1-year, 2-year, and 3-year accumulating MACE rates were 7.5%, 17.3%, and 19.3%, accordingly. Serum CDC42 was reduced in STEMI patients who experienced MACE compared to those who did not (P = 0.001). Serum CDC42 ≥ 250 pg/mL, ≥ 400 pg/mL, ≥ 700 pg/mL (cut by near integer value of 1/4th quartile, median, and 3/4th quartile) were associated with decreased accumulating MACE rates in STEMI patients (all P < 0.050). Notably, serum CDC42 ≥ 250 pg/mL (hazard ratio = 0.435, P = 0.031) was independently related to reduced accumulating MACE risk in STEMI patients. A serum CDC42 level of ≥ 250 pg/mL well predicts decreased MACE risk in STEMI patients who are treated with PCI.

Estrogen contributes to sex differences in M2a macrophages during multi-walled carbon nanotube-induced respiratory inflammation.

Lung diseases characterized by type 2 inflammation are reported to occur with a female bias in prevalence/severity in both humans and mice. This includes previous work examining multi-walled carbon nanotube (MWCNT)-induced eosinophilic inflammation, in which a more exaggerated M2a phenotype was observed in female alveolar macrophages (AMs) compared to males. The mechanisms responsible for this sex difference in AM phenotype are still unclear, but estrogen receptor (ER) signaling is a likely contributor. Accordingly, male AMs downregulated ERα expression after MWCNT exposure while female AMs did not. Thus, ER antagonist Fulvestrant was administered prior to MWCNT instillation. In females, Fulvestrant significantly attenuated MWCNT-induced M2a gene expression and eosinophilia without affecting IL-33. In males, Fulvestrant did not affect eosinophil recruitment but reduced IL-33 and M2a genes compared to controls. Regulation of cholesterol efflux and oxysterol synthesis is a potential mechanism through which estrogen promotes the M2a phenotype. Levels of oxysterols 25-OHC and 7α,25-OHC were higher in the airways of MWCNT-exposed males compared to MWCNT-females, which corresponds with the lower IL-1β production and greater macrophage recruitment previously observed in males. Sex-based changes in cholesterol efflux transporters Abca1 and Abcg1 were also observed after MWCNT exposure with or without Fulvestrant. Invitro culture with estrogen decreased cellular cholesterol and increased the M2a response in female AMs, but did not affect cholesterol content in male AMs and reduced M2a polarization. These results reveal the modulation of (oxy)sterols as a potential mechanism through which estrogen signaling may regulate AM phenotype resulting in sex differences in downstream respiratory inflammation.

MicroRNA-206-3p suppresses hepatic lipogenesis and cholesterol synthesis while driving cholesterol efflux.

Hepatosteatosis, hypertriglyceridemia, and hypertriglyceridemia are interconnected metabolic disorders. This study is designed to characterize how microRNA-206-3p (miR-206) simultaneously prevents de novo lipogenesis (DNL), cholesterol synthesis, and VLDL production in hepatocytes while promoting cholesterol efflux in macrophages. MiR-206 levels were reduced in hepatocytes and macrophages of mice subjected to a high-fat, high-cholesterol diet (HFHC). A negative feedback between LXRα (liver X receptor) and miR-206 is formed to maintain high LXRα and low miR-206 in hepatocytes. Systemic administration of miR-206 alleviated hepatosteatosis, hypertriglyceridemia and hypercholesterolemia in mice. A significant reduction in LDL-cholesterol and VLDL-cholesterol but unaltered HDL-cholesterol was observed in miR-206-treated mice. Mirroring these findings, miR-206 reprogrammed the transcriptome of hepatocytes towards inhibition of DNL, cholesterol synthesis, and assembly and secretion of VLDL. In macrophages, miR-206 activated expression of genes regulating cholesterol efflux. Hepatocyte-specific expression of miR-206 reduced hepatic and circulating triglycerides and cholesterol as well as VLDL production, while transplantation of macrophages bearing miR-206 facilitated cholesterol efflux. Mechanistically, miR-206 directly targeted Lxrα and Hmgcr in hepatocytes but facilitated expression of Lxrα in macrophages by targeting macrophage-specific TRPS1 (tricho-rhino-phalangeal syndrome 1), a transcription repressor of Lxrα. By targeting Hmgcr and Lxrα, miR-206 inhibited DNL, VLDL production and cholesterol synthesis in hepatocytes, whereas it drove cholesterol efflux by activating the TRPS1-LXRα axis. MiR-206, through differentially modulating LXRα signaling in hepatocytes and macrophages, inhibits DNL, promotes cholesterol efflux, and concurrently hinders cholesterol synthesis and VLDL production. MiR-206 simulates the functions of lipid-lowering medications, statins and LXRα agonists.

ABCG1 is Expressed in an LXR-Independent Manner in Patients with Type 2 Diabetes Mellitus.

Patients with type 2 diabetes mellitus have a high cardiovascular risk due, in part, to abnormalities of high-density lipoprotein mediated cholesterol efflux. The ATP-binding cassette A1 and G1 play a pivotal role in the regulation of cholesterol efflux. However, the regulation of these transporters in type 2 diabetes mellitus remains obscure. This study aimed to investigate the expression of ATP-binding cassette A1 and G1 and their regulation by Liver X receptors in monocyte-derived macrophages in type 2 diabetes mellitus, and to determine whether the alteration of these transporters might affect cholesterol efflux from macrophages. Blood was collected from type 2 diabetic patients and healthy controls. Peripheral monocytes were differentiated into macrophages. Quantitative real-time PCR, western blots, and cholesterol efflux assays were performed. The Liver X receptor and Liver X receptor element complex in the ATP-binding cassette G1 gene promoter were detected by electrophoretic mobility supershift assay. Macrophage ATP-binding cassette G1 expression and high density lipoproteininduced cholesterol efflux were significantly reduced in type 2 diabetic patients. However, the mRNA expression of ATP-binding cassette G1 in type 2 diabetic patients was not inhibited by Liver X receptor siRNA and the Liver X receptor- Liver X receptor element complexes remain unchanged similarly. The study suggested that the expression of ATP-binding cassette G1 and high density lipoprotein-induced cholesterol efflux in macrophages were reduced in type 2 diabetes mellitus. Impairment of cholesterol efflux and ATP-binding cassette G1 gene expression in type 2 diabetes mellitus might be regulated by a Liver X receptorindependent pathway.

Jieduquyuziyin prescription alleviates SLE complicated by atherosclerosis via promoting cholesterol efflux and suppressing TLR9/MyD88 activation.

Jieduquyuziyin prescription (JP), as a traditional Chinese medicine formula, is extensively applied to treat systemic lupus erythematosus (SLE). Its prescription is based on clinical practice and an evidence-based application of traditional medicines. It is approved by use in Chinese hospitals as a clinical prescription that can be directly used. The study aims to elucidate JP's efficacy on lupus-like disease combined with atherosclerosis and to explore its mechanism. To conduct in vivo experiments, we established a model of lupus-like disease with atherosclerosis in ApoE-/- mice fed a high-fat diet and injected intraperitoneally with pristane. In addition, oxidized low-density lipoprotein (ox-LDL) and a TLR9 agonist (CpG-ODN2395) were utilized to examine the mechanism of JP on SLE combined with AS in RAW264.7 macrophages in vitro. Results indicated that JP reduced hair loss and levels of the spleen index, maintained stable body weight, alleviated kidney damage in mice, and reduced the expression levels of urinary protein, autoantibodies, and inflammatory factors in serum. Furthermore, JP is effective at alleviating the lupus-like symptoms observed in mice. In mice, JP inhibited aortic plaque deposition, stimulated lipid metabolism, and increased the expression of genes that regulate cholesterol efflux, including ATP-binding cassette transporter A1 (ABCA1), ATP-binding cassette subfamily G member 1 (ABCG1), scavenger receptor class B type I (SR-BI), and peroxisome proliferator-activated receptor γ (PPAR-γ). In vivo, JP inhibited the expression of the Toll-like receptor 9 (TLR9)-induced signaling pathway, which links TLR9/MyD88/NF-kB to the expression of subsequent inflammatory factors. Furthermore, JP inhibited the expression of TLR9 and MyD88 in vitro. In addition, the JP treatment effectively reduced foam cell formation in RAW264.7 macrophages by increasing the expression of ABCA1/G1, PPAR-γ and SR-BI. JP played a therapeutic role in ApoE-/- mice with pristane-induced lupus-like diseases and AS, possibly through inhibition of TLR9/MyD88 signaling and promotion of cholesterol efflux.

Genomic assessment of early‐onset AD identifies novel risk loci and an incomplete genetic overlap with late‐onset AD

AbstractBackgroundEarly Onset Alzheimer Disease (EOAD, age at onset [AAO] &lt; = 65) is a severe form of AD, often occurring when patients are still caring for children or adults. Despite this, most genetic studies of EOAD have focused on autosomal dominant forms, and there is little understanding of similarities and differences between early and late onset forms of AD (LOAD, [AAO]&gt;65). To address this, we present a genome‐wide association study of non‐Mendelian EOAD and compare it to LOAD GWAS.MethodsPrimary single‐variant analyses were performed using two additive logistic regression for case‐control models (full: SNPs, PCs, sex and APOE‐ɛ4 dosage as covariates; reduced: SNPs and PCs); secondary models included PCs+sex and PCs+APOE. Models were applied on data derived from the Alzheimer Disease Genetics Consortium (ADGC), composed by unrelated individuals. Samples varied from 1293‐1459 cases and 8894‐9366 controls for EOAD, and 8795‐9508 cases and 9702‐10273 controls for LOAD, depending on the considered model. The SNP heritability (h2) and genetic correlation (rg) were estimated using LD score regression. Gene‐based and pathway analysis (gene sets from Msigdb‐v7.0) were performed using FUMA/MAGMA‐v1.6.ResultsWe identified two novel loci associated with EOAD: Chromosome 4 (full model: chr4:102027610, P = 2.98×10−08, near PPP3CA gene) and Chromosome 12 (PCs+sex model: rs117001070, P = 2.11×10−08, intergenic between LINC02444 and LINC02882). We additionally confirmed BIN1 and APOE in the EOAD subset. Several known genes also showed a significant association with LOAD. Heritability analyses showed higher h2 values for EOAD (h2 = 0.29, 0.29, 0.29 and 0.27) than LOAD (h2 = 0.19, 0.16, 0.19, and 0.15), for full, reduced, PCs+sex and PCs+APOE models respectively. Genetic correlation showed moderate but incomplete genetic correlation between EOAD and LOAD. Other than APOE (p = 3.89×10−12), gene‐based tests showed nominal association for EOAD C8orf44‐SGK3 (p = 9.95×10−06), SGK3 (p = 2.01×10−05) and HIST1H2AC (p = 3.04×10−05), and plausible pathways such as HDL remodeling (p = 5.50×10−05) and positive regulation of cholesterol efflux (p = 9.79×10−05). These pathways were nominally associated with LOAD (p = 0.04 and p = 4.05×10−03).ConclusionsWe identified two novel loci associated to EOAD not previously reported by LOAD studies. Heritability and genetic correlation results suggest that the genetic etiology of EOAD has an incomplete genetic overlap with LOAD.

Genetic dissection of the impact of lncRNA AI662270 during the development of atherosclerosis

BackgroundAtherosclerosis is driven by synergistic interactions between pathological biomechanical and lipid metabolic factors. Long noncoding RNAs (LncRNAs) have been implicated in atherogenesis. The purpose of this study was to investigate the potential mechanism of lncRNA AI662270 on macrophage cholesterol transport in atherosclerosis.MethodsApolipoprotein E deficiency (ApoE−/−) mice were fed a high fat diet for 16 weeks to construct atherosclerotic model, and the mice were injected with recombinant lentivirus carrying AI662270 gene to overexpress AI662270. Macrophages were cleared by liposomal clondronate in vivo. Fundamental experiments and functional assays, hematoxylin and eosin staining, oil red O staining and others, were performed to evaluate the function of AI662270 on atherogenesis. Peritoneal macrophages were treated with oxidized low density lipoprotein (ox-LDL) to simulate in vitro model. Mechanism assays, RNA-interacting protein immunoprecipitation, RNA–protein pulldown and others, were performed to study the regulatory mechanism of AI662270 in macrophages.ResultsThe novel AI662270 was mainly enriched in macrophages, but not in endothelial cells, smooth muscle cells and fibroblasts of mouse atherosclerotic lesions and was upregulated by ox-LDL. Overexpression of AI662270 resulted in lipid accumulation, larger atherosclerotic plaques and cardiac dysfunction in vivo. After macrophages were removed, the pro-atherogenic effect of AI662270 disappeared. Downregulation of AI662270 in macrophages protected against foam cell formation by potentiating cholesterol efflux and reducing intracellular total cholesterol. The opposite effect was observed in macrophage-specific AI662270-overexpressed cells in vitro. AI662270 bound to adenosine triphosphate-binding cassette transporter A1 (Abca1) responsible for regulating cholesterol efflux in macrophages. Forced expression of AI662270 in macrophages decreased Abca1 expression. The reverse occurred when expression of AI662270 was repressed.ConclusionThese findings reveal an essential role for AI662270 in atherosclerosis progression by regulating cholesterol efflux from macrophages.

Esterase D interacts with metallothionein 2A and inhibits the migration of A549 lung cancer cells in vitro.

Esterase D (ESD) is a nonspecific esterase widely distributed in various organisms. ESD plays an important role in regulating cholesterol efflux, inhibiting viral replication and lung cancer growth. MT2A (metallothionein 2A) is the most important isoform of metallothionein (MTs) in human and high expression of MT2A in tumors represents poor prognosis and metastatic behavior. However, there are no reports about the molecular mechanism of ESD in the regulation of tumor metastasis. In this study, we found for the first time that activation ESD promoted its interaction with MT2A and decreased the protein level of MT2A, which resulting in the concentration of free zinc ions up-regulated, and inhibited the migration of A549 lung cancer cells in vitro.

Qihuang Zhuyu Formula Attenuates Atherosclerosis via Targeting PPARγ to Regulate Cholesterol Efflux and Endothelial Cell Inflammation.

At present, due to the limitations of drug therapy targets for atherosclerosis, some patients fail to achieve satisfactory efficacy. Cholesterol efflux dysfunction and endothelial cell inflammation are considered to be important factors in the development of atherosclerosis. Peroxisome proliferator-activated receptor gamma (PPARγ), a promising therapeutic target for atherosclerosis, plays a dual role in regulating cholesterol efflux and endothelial cell inflammation. However, the use of PPARγ agonist in clinical practice is greatly limited as it could lead to water and sodium retention and hence result in congestive heart failure. Qihuang Zhuyu Formula (QHZYF) is a hospital preparation of Jiangsu Province Hospital of Chinese Medicine which has definite effect in the treatment of atherosclerosis, but its pharmacological mechanism has not been clear. In this study, we successfully predicted that QHZYF might regulate cholesterol efflux and endothelial inflammation via targeting PPARγ-mediated PPARγ/LXRα/ABCA1-ABCG1 and PPARγ/NF-κB p65 pathways by using UPLC-Q-TOF/MS, network pharmacology, bioinformatics analysis, and molecular docking technology. Subsequently, we confirmed in vivo that QHZYF could attenuate atherosclerosis in ApoE-/- mice and regulate the expression levels of related molecules in PPARγ/LXRα/ABCA1-ABCG1 and PPARγ/NF-κB p65 pathways of ApoE-/- mice and C57BL/6 wild-type mice. Finally, in in vitro experiments, we found that QHZYF could reduce lipid content and increase cholesterol efflux rate of RAW 264.7 cells, inhibit the inflammatory response of HUVECs, and regulate the expression levels of related molecules in the two pathways. In addition, the above effects of QHZYF were significantly weakened after PPARγ knockdown in the two kinds of cells. In conclusion, our study revealed that QHZYF attenuates atherosclerosis via targeting PPARγ-mediated PPARγ/LXRα/ABCA1-ABCG1 and PPARγ/NF-κB p65 pathways to regulate cholesterol efflux and endothelial cell inflammation. More importantly, our study offers a promising complementary and alternative therapy which is expected to make up for the limitation of current drug treatment methods and provide a valuable reference for new drugs development in the future.

Dual effect of ultraviolet B on cholesterol efflux and regulated by ultraviolet radiation resistance-associated gene-mediated autophagy.

In addition to diet and metabolism, the occurrence of foam cells and atherosclerosis are also related to environmental factors. Individual studies have shown that ultraviolet B (UVB) can regulate the progression of atherosclerosis, but with different results. Whether or not UVB has a dual effect on atherosclerosis and what mechanism is involved has not been reported. After THP-1-derived foam cells were treated with UVB in different ways, the effects of UVB on foam cells were investigated by western blotting, cholesterol efflux experiment, oil red O staining and other methods. UVB plays a dual role on foam cell formation, and this effect is related to cholesterol efflux. UVB of 50mJ/cm2 can promote cholesterol efflux in foam cells, while UVB of 200mJ/cm2 can inhibit cholesterol efflux. UVB induces cholesterol efflux from foam cells in an autophagy-dependent manner, as the beneficial effect of UVB at 50mJ/cm2 can be reversed by the autophagy inhibitor 3-Methyladenine (3-MA). In addition, silencing the expression of ultraviolet radiation resistance-associated gene (UVRAG) can inhibit autophagy and reduce cholesterol efflux, and overexpressing UVRAG yields the opposite result. In conclusion, our research proves that UVB exhibits a dual role in foam cell formation by regulating cholesterol efflux. Further more, we also reveal that UVRAG-mediated autophagy is the underlying mechanism of UVB-induced cholesterol efflux.

Antagonism of miR-148a attenuates the progression of atherosclerosis in APOBTGApobec-/-Ldlr+/- mice

Background and Aims : miR-148a is a hepatic and immune enriched miRNA that regulates lipoprotein metabolism and macrophage cholesterol homeostasis and inflammation. We have characterized miR-148a as a negative regulator of LDLR expression and activity. Moreover, we have demostrated that miR-148a regulates hepatic ABCA1 expression and circulating HDL-C levels. In addition to the regulation of circulating cholesterol, miR-148a is highly expressed in macrophages, which regulate cholesterol efflux and inflammation.

Cholesterol homeostasis regulated by ABCA1 is critical for retinal ganglion cell survival.

Genome-wide association studies have suggested a link between primary open-angle glaucoma and the function of ABCA1. ABCA1 is a key regulator of cholesterol efflux and the biogenesis of high-density lipoprotein (HDL) particles. Here, we showed that the POAG risk allele near ABCA1 attenuated ABCA1 expression in cultured cells. Consistently, POAG patients exhibited lower ABCA1 expression, reduced HDL, and higher cholesterol in white blood cells. Ablation of Abca1 in mice failed to form HDL, leading to elevated cholesterol levels in the retina. Counting retinal ganglion cells (RGCs) by using an artificial intelligence (AI) program revealed that Abca1-deficient mice progressively lost RGCs with age. Single-cell RNA sequencing (scRNA-seq) revealed aberrant oxidative phosphorylation in the Abca1-/- retina, as well as activation of the mTORC1 signaling pathway and suppression of autophagy. Treatment of Abca1-/- mice using atorvastatin reduced the cholesterol level in the retina, thereby improving metabolism and protecting RGCs from death. Collectively, we show that lower ABCA1 expression and lower HDL are risk factors for POAG. Accumulated cholesterol in the Abca1-/- retina causes profound aberrant metabolism, leading to a POAG-like phenotype that can be prevented by atorvastatin. Our findings establish statin use as a preventive treatment for POAG associated with lower ABCA1 expression.

Cyclodextrin boostered-high density lipoprotein for antiatherosclerosis by regulating cholesterol efflux and efferocytosis

A promising therapy for atherosclerosis treatment was designed by targeting LXR receptor (LXR) on atherosclerotic macrophage, where LXR activation could regulate cholesterol efflux and efferocytosis. Herein, a sequential-targeting nanoplatform (HT-rHDL) was constructed to deliver LXR agonist into macrophage, which was composed of discoidal reconstituted high-density lipoprotein (d-rHDL) core for agonist encapsulation and external modifications: (i) the outermost hyaluronan, targeting injured endothelium; (ii) modified β-cyclodextrin of d-rHDL, accelerating cholesterol efflux of foam cells; (iii) conjugated apolipoprotein A-I of d-rHDL, targeting macrophage. This design underlines that the nanoplatform could increase its plaque accumulation, accomplish cholesterol efflux-remodeling-drug delivery behavior and specifically activate LXR in macrophage. After a 3-month treatment with HT-rHDL, 31.47% plaque area reduction, 56.0% lipid accumulation decrease, obvious inflammation resolution and enhanced plaque stability were observed. Furthermore, the atherosclerosis intervention was demonstrated to benefit from the upregulations of ABC transporters and Mer tyrosine kinase. Collectively, HT-rHDL provides new strategies to regress atherosclerosis.

Abstract 396: CHROMR Coordinates Interferon Signaling And Lipid Metabolism In Viral Infection

COVID-19, caused by SARS-CoV-2 infection, is associated with atherosclerotic cardiovascular complications like acute coronary syndrome, myocardial infarction, and stroke, but the underlying mechanisms are poorly understood. Long non-coding RNAs (lncRNAs) have emerged as important regulators of gene expression in the immune response. RNA-seq of whole blood from hospitalized patients with COVID-19, influenza A virus and matched controls identified 190 lncRNAs deregulated in both viral infections. Among the top mutually upregulated lncRNAs, we noted CHROMR (alias CHROME ) , a primate-specific lncRNA previously identified as a competing endogenous RNA that regulates cholesterol efflux and fatty acid oxidation via microRNA sequestration. Here, we report a complementary role for CHROMR in coordinating the interferon (IFN) signaling response to respiratory viruses. CHROMR expression is induced in macrophages in response to SARS-CoV-2 and influenza A infection and accumulates in the nucleus where it binds the transcriptional co-repressor IRF2BP2, a negative regulator of IFN-stimulated gene (ISG) expression. CHROMR is essential for mounting an anti-viral response, as its depletion in macrophages reduces histone acetylation at ISGs, activation of IRF signaling, and ISG expression. These findings suggest that CHROMR sequesters the nuclear IRF-2/IRF2BP2 repressor complex releasing its inhibitory effect on transcription of ISGs. Consistent with this, CHROMR expression is required to restrict influenza virus replication in macrophages. Notably, many viruses rewire host lipid synthesis and metabolism to facilitate replication, and thus, increased CHROMR expression in virus infected cells would both mitigate cellular lipid accumulation and increase ISG transcription to mount an anti-viral immune response. Collectively, our findings underscore the merit of investigating lncRNAs to decipher novel regulatory mechanisms that govern lipid metabolism and inflammation in humans.

HDL and microRNAs.

In previous chapters, we know that high-density lipoproteins (HDLs) could act at multiple cell lines and then trigger intracellular molecular pathway to prevent several metabolic diseases. Besides the classic genes regulating cholesterol efflux and reverse cholesterol transport (RCT), microRNAs (miRNAs) could also affect HDLs biogenesis, metabolism, and functions. This chapter summarizes the miRNAs, which regulate HDLs functions in table. In addition, HDLs are good vectors for miRNAs. They could carry miRNAs in circulation and take them into several cells such as macrophages and endothelial cells. Complete understanding of the miRNAs associated with HDL regulation would give us broader insights to prevent and treat metabolic diseases.

MiR-125b downregulates macrophage scavenger receptor type B1 and reverse cholesterol transport

ObjectiveTo determine whether miR-125b regulates cholesterol efflux in vivo and in vitro through the regulation of scavenger receptor type B1 (SR-B1). Approach and resultsWe demonstrated that miR-125b is up-regulated in the human aortas of patients with CAD and is located in macrophages and vascular smooth muscle cells (VSMCs). We identified SCARB1 as a direct target of miR-125b by repressing the activity of the SCARB1 3′-untranslated region reporter construct. Moreover, the overexpression of miR-125b in both human and mouse macrophages as well as VSMCs was found to downregulated the expression of the SCARB1 and the SR-B1 protein levels, thereby impairing α-HDL-mediated macrophage cholesterol efflux in vitro. The in vivo reverse cholesterol transport (RCT) rate from non-cholesterol-loaded macrophages transfected with miR-125b to feces was also found to be decreased when compared with that of control mimic-transfected macrophages. ConclusionsTogether, these results provide evidence that miR-125b downregulates SCARB1 and SR-B1 in both human and mouse macrophages as well as VSMCs, thereby impairing macrophage cholesterol efflux in vitro and the whole macrophage-specific RCT pathway in vivo.