Potential Therapeutic Target For Atherosclerosis Research Articles

Macrophage-Derived GSDMD Plays an Essential Role in Atherosclerosis and Cross Talk Between Macrophages via the Mitochondria-STING-IRF3/NF-κB Axis.

Macrophages play a crucial role in atherosclerotic plaque formation, and the death of macrophages is a vital factor in determining the fate of atherosclerosis. GSDMD (gasdermin D)-mediated pyroptosis is a programmed cell death, characterized by membrane pore formation and inflammatory factor release. ApoE-/- and Gsdmd-/- ApoE-/- mice, bone marrow transplantation, and AAV-F4/80-shGSDMD were used to examine the effect of macrophage-derived GSDMD on atherosclerosis. Single-cell RNA sequencing was used to investigate the changing profile of different cellular components and the cellular localization of GSDMD during atherosclerosis. First, we found that GSDMD is activated in human and mouse atherosclerotic plaques and Gsdmd-/- attenuates the atherosclerotic lesion area in high-fat diet-fed ApoE-/- mice. We performed single-cell RNA sequencing of ApoE-/- and Gsdmd-/- ApoE-/- mouse aortas and showed that GSDMD is principally expressed in atherosclerotic macrophages. Using bone marrow transplantation and AAV-F4/80-shGSDMD, we identified the potential role of macrophage-derived GSDMD in aortic pyroptosis and atherosclerotic injuries in vivo. Mechanistically, GSDMD contributes to mitochondrial perforation and mitochondrial DNA leakage and subsequently activates the STING (stimulator of interferon gene)-IRF3 (interferon regulatory factor 3)/NF-κB (nuclear factor kappa B) axis. Meanwhile, GSDMD regulates the STING pathway activation and macrophage migration via cytokine secretion. Inhibition of GSDMD with GSDMD-specific inhibitor GI-Y1 can effectively alleviate the progression of atherosclerosis. Our study has provided a novel macrophage-derived GSDMD mechanism in the promotion of atherosclerosis and demonstrated that GSDMD can be a potential therapeutic target for atherosclerosis.

MiR-509-3p promotes oxidized low-density lipoprotein-induced apoptosis in mouse aortic endothelial cells

To investigate the effect of microRNA-509-3p (miR-509-3p) on the apoptosis of atherosclerotic vascular endothelial cells. Mouse aortic endothelial cells (MAECs) were divided into normal control group, oxidized low-density lipoprotein (ox-LDL) group, miR-509-3p overexpression group, miR-509-3p overexpression control group, miR-509-3p inhibitor + ox-LDL group, and miR-509-3p inhibitor control + ox-LDL group. MAEC were induced with 100 mg/L ox-LDL for 24 hours, and then transfected with miR-509-3p overexpression/inhibitor and corresponding control for 48 hours. The miR-509-3p expression in MAECs exposed to ox-LDL was detected using real-time fluorescence quantitative polymerase chain reaction (RT-qPCR). Flow cytometry was used to detect the level of apoptosis, and cell counting kit (CCK-8) was used to detect the proliferation activity of MAECs. The direct gene targets of miR-509-3p were predicted using bioinformatics analyses and confirmed using a dual luciferase reporter assay. The expression of Bcl-2 mRNA and protein was detected by RT-qPCR and Western blotting, respectively. Compared with the normal control group, miR-509-3p was significantly upregulated in ox-LDL-stimulated MAECs (1.68±0.85 vs. 1.00±0.30, t = 2.398, P < 0.05). After transfection of MAECs with miR-509-3p overexpression, the luciferase activity of the BCL2 3'UTR WT reporter gene was significantly lower than that of miR-509-3p overexpression control group (0.83±0.06 vs. 1.00±0.07, t = 4.531, P = 0.001). The luciferase activity of the BCL2 3'-UTR mutant (MUT) reporter gene was not significantly different from that of miR-509-3p overexpression control group (0.94±0.05 vs. 1.00±0.08, t = 1.414, P = 0.188). Compared with the normal control group and miR-509-3p mimics control group, the cell proliferation activity was decreased [(0.60±0.06)% vs. (1.00±0.09)%, (0.89±0.04)%, both P < 0.01], the percentage of apoptotic cells were increased [(23.46±2.02)% vs. (7.66±1.52)%, (10.40±0.78)%, both P < 0.05], and the mRNA and protein expression of Bcl-2 were significantly downregulated (Bcl-2 mRNA: 0.52±0.13 vs. 1.00±0.36, 1.10±0.19, Bcl-2 protein: 0.42±0.07 vs. 1.00±0.11, 0.93±0.10, both P < 0.01) in miR-509-3p overexpression group. Compared with the ox-LDL group, inhibition of miR-509-3p expression could increase the proliferation activity of MAECs induced by ox-LDL [(0.64±0.35)% vs. (0.34±0.20%)%, P < 0.05], and reduce the apoptosis rate [(13.59±2.22)% vs. (29.84±5.19)%, P < 0.01], and up-regulated the expression of Bcl-2 mRNA and protein in MAECs induced by ox-LDL (Bcl-2 mRNA relative expression: 0.82±0.09 vs. 0.52±0.10, Bcl-2 protein relative expression: 0.83±0.17 vs. 0.40±0.07, both P < 0.05). Bcl-2 was one of the target genes of miR-509-3p. miR-509-3p can reduce the proliferation activity of endothelial cells, reduce the expression of Bcl-2, and promote cell apoptosis, thereby promoting the occurrence and development of atherosclerosis. Inhibition of miR-509-3p expression may be a potential therapeutic target for atherosclerosis.

Macrophage KLF15 prevents foam cell formation and atherosclerosis via transcriptional suppression of OLR-1

BackgroundMacrophage-derived foam cells are a hallmark of atherosclerosis. Scavenger receptors, including lectin-like oxidized low-density lipoprotein (LDL) receptor-1 (OLR-1), are the principal receptors responsible for the uptake and modification of LDL, facilitating macrophage lipid load and the uptake of oxidized LDL by arterial wall cells. Krüppel-like factor 15 (KLF15) is a transcription factor that regulates the expression of genes by binding to the promoter during transcription. Therefore, this study aimed to investigate the precise role of macrophage KLF15 in atherogenesis. MethodsWe used two murine models of atherosclerosis: mice injected with an adeno-associated virus (AAV) encoding the Asp374-to-Tyr mutant version of human PCSK9, followed by 12 weeks on a high-fat diet (HFD), and ApoE−/−‐ mice on a HFD. We subsequently injected mice with AAV-KLF15 and AAV-LacZ to assess the role of KLF15 in the development of atherosclerosis in vivo. Oil Red O, H&E, and Masson's trichome staining were used to evaluate atherosclerotic lesions. Western blots and RT-qPCR were used to assess protein and mRNA levels, respectively. ResultsWe determined that KLF15 expression was downregulated during atherosclerosis formation, and KLF15 overexpression prevented atherosclerosis progression. KLF15 expression levels did not affect body weight or serum lipid levels in mice. However, KLF15 overexpression in macrophages prevented foam cell formation by reducing OLR-1-meditated lipid uptake. KLF15 directly targeted and transcriptionally downregulated OLR-1 levels. Restoration of OLR-1 reversed the beneficial effects of KLF15 in atherosclerosis. ConclusionMacrophage KLF15 transcriptionally downregulated OLR-1 expression to reduce lipid uptake, thereby preventing foam cell formation and atherosclerosis. Thus, our results suggest that KLF15 is a potential therapeutic target for atherosclerosis.

Abstract 12014: Macrophage-Specific DNaseII Deficiency Plays a Critical Role in Vascular Inflammation and Atherosclerosis in Apolipoprotein E-Deficient Mice

Background: Atherosclerosis is a chronic inflammatory disease of the walls of blood vessels. Macrophage activated by endogenous ligands plays an important role in chronic inflammation of blood vessels. Deoxyribonuclease (DNase) II in macrophages digests the endogenous DNA derived from apoptotic cells. Recent studies show that Toll-like receptor 9 (TLR9), one of the major receptors of endogenous DNA, activates macrophages, suggesting that DNA degradation by DNase II may contribute to the pathogenesis of inflammatory disease. We investigated whether DNase II in macrophages contributes to the development of vascular inflammation and atherogenesis using apolipoprotein E-deficient (ApoE-/-) mice. Methods: Macrophage specific DNase II deleted ApoE-/- (DNase2flox LysMCre ApoE-/-) mice and its control (DNase2flox ApoE-/-) mice were generated. For in vivo TLR9 inhibition, DNase2flox LysMCre ApoE-/- mice received TLR9 antagonist (iODN2088) or genetically lacked TLR9 (DNase2flox LysMCre ApoE-/- TLR9-/-) mice were also evaluated. All mice were fed a western-type diet and received subcutaneous angiotensin II infusion (1000 ng/kg per minute) for 8 weeks. Atherosclerotic lesions were investigated by en face Sudan IV staining and quantitative reverse transcription polymerase chain reaction. In vitro experiments using peritoneal macrophages were performed to confirm the proinflammatory roles of mitochondrial DNA (mtDNA) in the absence of DNase II. Results: Expression of DNase II and TLR9 increased in the atherosclerotic plaques. Macrophage-specific DNase II deletion significantly atherogenesis in the aortic arch in ApoE-/- mice (P&lt;0.05) and increased RNA expression of inflammatory molecules in the aorta. In vitro experiments demonstrated that mtDNA or TLR9 agonist significantly increased the expression of inflammatory molecules in DNase II deficient peritoneal macrophages. Activation of NF-κB signaling was involved in DNase II deficient vascular inflammation and macrophage activation. Conclusions: Macrophage-specific DNase II deletion accelerated vascular inflammation and atherogenesis, which are attenuated by genetic deletion or pharmacological blockade of TLR9. DNase II may be a potential therapeutic target for atherosclerosis.

Par3L, a polarity protein, promotes M1 macrophage polarization and aggravates atherosclerosis in mice via p65 and ERK activation.

Proinflammatory M1 macrophages are critical for the progression of atherosclerosis. The Par3-like protein (Par3L) is a homolog of the Par3 family involved in cell polarity establishment. Par3L has been shown to maintain the stemness of mammary stem cells and promote the survival of colorectal cancer cells. In this study, we investigated the roles of the polar protein Par3L in M1 macrophage polarization and atherosclerosis. To induce atherosclerosis, Apoe-/- mice were fed with an atherosclerotic Western diet for 8 or 16 weeks. We showed that Par3L expression was significantly increased in human and mouse atherosclerotic plaques. In primary mouse macrophages, oxidized low-density lipoprotein (oxLDL, 50 μg/mL) time-dependently increased Par3L expression. In Apoe-/- mice, adenovirus-mediated Par3L overexpression aggravated atherosclerotic plaque formation accompanied by increased M1 macrophages in atherosclerotic plaques and bone marrow. In mouse bone marrow-derived macrophages (BMDMs) or peritoneal macrophages (PMs), we revealed that Par3L overexpression promoted LPS and IFNγ-induced M1 macrophage polarization by activating p65 and extracellular signal-regulated kinase (ERK) rather than p38 and JNK signaling. Our results uncover a previously unidentified role for the polarity protein Par3L in aggravating atherosclerosis and favoring M1 macrophage polarization, suggesting that Par3L may serve as a potential therapeutic target for atherosclerosis.

Inhibition of DRP1-dependent mitochondrial fission by Mdivi-1 alleviates atherosclerosis through the modulation of M1 polarization

BackgroundInflammation and immune dysfunction with classically activated macrophages(M1) infiltration are important mechanisms in the progression of atherosclerosis (AS). Dynamin-related protein 1 (DRP1)-dependent mitochondrial fission is a novel target for alleviating inflammatory diseases. This study aimed to investigate the effects of DRP1 inhibitor Mdivi-1 on AS.MethodsApoE−/− mice were fed with a high-fat diet supplemented with or without Mdivi-1. RAW264.7 cells were stimulated by ox-LDL, pretreated with or without MCC950, Mito-TEMPO, or Mdivi-1. The burden of plaques and foam cell formation were determined using ORO staining. The blood lipid profles and inflammatory cytokines in serum were detected by commercial kits and ELISA, respectively. The mRNA expression of macrophage polarization markers, activation of NLRP3 and the phosphorylation state of DRP1 were detected. Mitochondrial reactive oxygen species (mito-ROS), mitochondrial staining, ATP level and mitochondrial membrane potential were detected by mito-SOX, MitoTracker, ATP determination kit and JC-1 staining, respectively.ResultsIn vivo, Mdivi-1 reduced the plaque areas, M1 polarization, NLRP3 activation and DRP1 phosphorylation at Ser616. In vitro, oxidized low-density lipoprotein (ox-LDL) triggered M1 polarization, NLRP3 activation and abnormal accumulation of mito-ROS. MCC950 and Mito-TEMPO suppressed M1 polarization mediated foam cell formation. Mito-TEMPO significantly inhibited NLRP3 activation. In addition, Mdivi-1 reduced foam cells by inhibiting M1 polarization. The possible mechanisms responsible for the anti-atherosclerotic effects of Mdivi-1 on reducing M1 polarization were associated with suppressing mito-ROS/NLRP3 pathway by inhibiting DRP1 mediated mitochondrial fission. In vitro, similar results were observed by DRP1 knockdown.ConclusionInhibition of DRP1-dependent mitochondrial fission by Mdivi-1 alleviated atherogenesis via suppressing mito-ROS/NLRP3-mediated M1 polarization, indicating DRP1-dependent mitochondrial fission as a potential therapeutic target for AS.

IRE1α: from the function to the potential therapeutic target in atherosclerosis.

Inositol requiring enzyme 1 (IRE1) is generally thought to control the most conserved pathway in the unfolded protein response (UPR). Two isoforms of IRE1, IRE1α and IRE1β, have been reported in mammals. IRE1α is a ubiquitously expressed protein whose knockout shows marked lethality. In contrast, the expression of IRE1β is exclusively restricted in the epithelial cells of the respiratory and gastrointestinal tracts, and IRE1β-knockout mice are phenotypically normal. As research continues to deepen, IRE1α was showed to be tightly linked to inflammation, lipid metabolism regulation, cell death and so on. Growing evidence also suggests an important role for IRE1α in promoting atherosclerosis (AS) progression and acute cardiovascular events through disrupting lipid metabolism balance, facilitating cells apoptosis, accelerating inflammatory responses and promoting foam cell formation. In addition, IRE1α was recognized as novel potential therapeutic target in AS prevention. This review provides some clues about the relationship between IRE1α and AS, hoping to contribute to further understanding roles of IRE1α in atherogenesis and to be helpful for the design of novel efficacious therapeutics agents targeting IRE1α-related pathways.

CD47 Activation by Thrombospondin-1 in Lymphatic Endothelial Cells Suppresses Lymphangiogenesis and Promotes Atherosclerosis.

TSP1 (thrombospondin-1)-a well-known angiogenesis inhibitor-mediates differential effects via interacting with cell surface receptors including CD36 (cluster of differentiation) and CD47. However, the role of TSP1 in regulating lymphangiogenesis is not clear. Our previous study suggested the importance of cell-specific CD47 blockade in limiting atherosclerosis. Further, our experiments revealed CD47 as a dominant TSP1 receptor in lymphatic endothelial cells (LECs). As the lymphatic vasculature is functionally linked to atherosclerosis, we aimed to investigate the effects of LEC TSP1-CD47 signaling inhibition on lymphangiogenesis and atherosclerosis. Murine atherosclerotic and nonatherosclerotic arteries were utilized to investigate TSP1 expression using Western blotting and immunostaining. LEC-specific knockout mice were used to determine the in vivo role of LEC Cd47 in lymphangiogenesis and atherosclerosis. Various in vitro cell-based assays, in vivo Matrigel plug implantation, molecular biological techniques, and immunohistological approaches were used to evaluate the underlying signaling mechanisms. Elevated TSP1 expression was observed in mouse atherosclerotic aortic tissue compared with nonatherosclerotic control tissue. TSP1 at pathological concentrations suppressed both in vitro and in vivo lymphangiogenesis. Mechanistically, TSP1 inhibited VEGF (vascular endothelial growth factor)-C-induced AKT and eNOS activation in LEC and attenuated NO (nitric oxide) production. Further, CD47 silencing in LEC prevented the effects of TSP1 on lymphangiogenic AKT-eNOS signaling and lymphangiogenesis. Atheroprone AAV (adeno-associated virus) 8-PCSK9-injected LEC-specific Cd47 knockout mice (Cd47ΔLEC) had reduced atherosclerosis in both aorta and aortic root compared with control mice (Cd47ΔWT). However, no differences in metabolic parameters including body weight, plasma total cholesterol levels, and fasting blood glucose were observed. Additional immunostaining experiments performed on aortic root cross-sections indicated higher lymphatic vessel density in Cd47ΔLEC mice in comparison to controls. These findings demonstrate that TSP1 inhibits lymphangiogenesis via activation of CD47 in LEC, and loss of LEC Cd47 attenuates atherosclerotic lesion formation. Collectively, these results identify LEC CD47 as a potential therapeutic target in atherosclerosis.

MALT1 accelerates proatherogenic vascular smooth muscle cell growth, invasion and synthetic phenotype switching via nuclear factor‑κB signaling‑dependent way.

Mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) modulates T helper cell differentiation and nuclear factor-κB (NF-κB) pathway-mediated inflammation and potentially regulates lipid metabolism, which are all critical factors involved in atherosclerosis. The present study aimed to investigate the effect of MALT1 on the cellular functions of proatherogenic vascular smooth muscle cells (VSMCs). Therefore, to establish a human proatherogenic VSMC model, VSMCs were treated with different doses of oxidized low-density lipoprotein (oxLDL). Subsequently, the effect of MALT1 overexpression or knockdown in proatherogenic VSMCs treated with or without NF-κB activator was also explored. The results showed that treatment of proatherogenic VSMCs with oxLDL significantly elevated the mRNA and protein expression levels of MALT1 in a dose-dependent manner. Furthermore, MALT1 overexpression enhanced cell viability, invasion and phenotype switching and reduced apoptosis in proatherogenic VSMCs. However, MALT1 knockdown exerted the opposite effect on the above cellular functions. Additionally, the results revealed that MALT1 could positively regulate the NF-κB pathway in proatherogenic VSMCs. Moreover, treatment of proatherogenic VSMCs with NF-κB activator not only exacerbated the dysregulation of cellular functions, but also hampered the effect of MALT1 knockdown on attenuating cell growth, invasion and synthetic phenotype switching, thus suggesting that NF-κB was essential for the regulation of MALT1-triggered functions in proatherogenic VSMCs. In conclusion, the current study suggested that MALT1 could exacerbate cell viability, mobility and synthetic phenotype switching of proatherogenic VSMCs in a NF-κB signaling-dependent manner. Therefore, MALT1 could be considered as a potential therapeutic target for atherosclerosis.

Long non-coding RNA PVT1 regulates atherosclerosis progression via the microRNA-106b-5p/ACSL4 axis

Long non-coding RNAs (lncRNAs) have been associated with atherosclerosis (AS), but the role of lncRNA PVT1 in this disease is still unknown. However, lncRNA PVT1 was found to be significantly upregulated in the serum of AS patients. In vitro experiments using human vascular endothelial cells (HUVECs) showed that oxidized low-density lipoprotein (ox-LDL) treatment enhanced PVT1 expression and impeded HUVEC proliferation, which could be reversed by PVT1 knockdown or miR-106b-5p mimics. Additionally, knockdown of PVT1 and overexpression of miR-106b-5p inhibited the increase of iron content, MDA level, lipid ROS, ACSL4, and PTGS2 in ox-LDL-induced HUVECs, as well as the decrease of GSH and GPX4. We also found that PVT1 knockdown reduced lipid deposition, atherosclerotic plaque number, and size in ApoE−/− mice. These results suggest that PVT1 plays a crucial role in AS progression by regulating the miR-106b-5p/ACSL4 axis in HUVECs, and may therefore be a potential therapeutic target for AS.

Inhibition of lncRNA NFIA-AS1 Alleviates Abnormal Proliferation and Inflammation of Vascular Smooth Muscle Cells in Atherosclerosis by Regulating miR-125a-3p/AKT1 Axis.

Vascular smooth muscle cells (VSMCs) are critical elements of the vascular wall and play a crucial role in the genesis and development of atherosclerosis (AS). Increasingly, studies have indicated that long noncoding RNAs (lncRNAs) regulate VSMC proliferation, apoptosis, and other biological processes. Nevertheless, the role of lncRNA NFIA-AS1 (hereinafter referred to as NFIA-AS1) in VSMCs and AS remains unclear. Quantitative real-time PCR (qRT-PCR) was performed to analyze the messenger RNA (mRNA) levels of NFIA-AS1 and miR-125a-3p. CCK-8 and EdU staining were performed to detect VSMC proliferation. VSMC apoptosis was evaluated by flow cytometry. The expression of various proteins was detected using western blotting. The levels of inflammatory cytokines secreted by VSMCs were measured by enzyme linked immunosorbent assay (ELISA). The binding sites of NFIA-AS1 and miR-125a-3p, as well as miR-125a-3p and AKT1, were analyzed using bioinformatics methods and validated using a luciferase reporter assay. The function of NFIA-AS1/miR-125a-3p/AKT1 in VSMCs was clarified through loss- and gain-of-functional experiments. We confirmed that NFIA-AS1 was highly expressed in AS tissues and VSMCs induced by oxidized low-density lipoprotein (Ox-LDL). Knockdown of NFIA-AS1 restrained the exceptional growth of Ox-LDL-induced VSMCs, promoted their apoptosis, and decreased the secretion of inflammatory factors and expression of adhesion factors. In addition, NFIA-AS1 regulated the proliferation, apoptosis, and inflammatory response of VSMCs through the miR-125a-3p/AKT1 axis, suggesting that NFIA-AS1 may be a potential therapeutic target for AS.

Circ-USP9X interacts with EIF4A3 to promote endothelial cell pyroptosis by regulating GSDMD stability in atherosclerosis

ABSTRACT Endothelial pyroptosis is a pathological mechanism of atherosclerosis (AS). Circular RNAs (circRNAs) are vital in AS progression by regulating endothelial cell functions. The study aimed to explore whether circ-USP9× regulated pyroptosis of endothelial cell to involve in AS development and the molecular mechanism. Pyroptosis was determined using lactate dehydrogenase (LDH) assay, enzyme linked immunosorbent assay (ELISA), flow cytometry, propidium iodide (PI) staining assay, and western blot. The mechanism of circ-USP9× was determined using RNA pull-down and RNA binding protein immunoprecipitation (RIP) assays. Results showed that circ-USP9× was upregulated in AS and oxidized low-density lipoprotein (ox-LDL)-treated human umbilical vein endothelial cells (HUVECs). Knockdown of circ-USP9× suppressed ox-LDL induced pyroptosis of HUVECs. Mechanically, circ-USP9× could bind to EIF4A3 in the cytoplasm. Moreover, EIF4A3 was bound to GSDMD and further affects GSDMD stability. Overexpression of EIF4A3 rescued cell pyroptosis induced by circ-USP9× depletion. In short, circ-USP9× interacted with EIF4A3 to enhance GSDMD stability, thus further promoting ox-LDL-induced pyroptosis of HUVECs. These findings suggested that circ-USP9× participates in AS progression and may be a potential therapeutic target for AS.

PAX5/ITGAX Contributed to the Progression of Atherosclerosis by Regulation of B Differentiation via TNF-α Signaling Pathway.

To investigate the effect of paired box protein 5 (PAX5)/integrin subunit alpha X (ITGAX) in atherosclerosis (AS). AS model was established using ApoE-/- mice (C57BL/6). Human vascular smooth muscle cells (HVSMCs) were stimulated with ox-LDL. Quantitative reverse transcription polymerase chain reaction and Western blotting were used to detect the expression levels of genes and proteins. Reporter constructs and luciferase assays were used to investigate the role of ITGAX and PAX5. Cells proliferation and inflammation factors were detected. The results presented that aortic plaque area, lipid content, serum triglyceride, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol levels were significantly increased in the high-fat diet group (p < 0.05). ITGAX was upregulated in atherosclerotic tissues. In addition, ox-LDL treatment induced HVSMCs proliferation, migration, and invasion. Reporter constructs and luciferase assays indicated ITGAX interaction with PAX5. Furthermore, siITGAX and siPAX5 cotransfection restored the rate of HVSMCs in G1 and S and G2/M phases, decreased the content of tumor necrosis factor-alpha (TNF-ɑ), interleukin (IL)-6, and IL-8 (p < 0.05). Interestingly, siITGAX and siPAX5 cotransfection also decreased the expression levels of TNF-α, TNF-R1, TNF-R2, CD19, and CD86 (p < 0.05). Our results suggest that ITGAX may be a potential therapeutic target for AS.

Identification of a Novel Angiogenesis Signalling circSCRG1/miR-1268b/NR4A1 Pathway in Atherosclerosis and the Regulatory Effects of TMP-PF In Vitro.

Angiogenesis contributes to plaque instability in atherosclerosis and further increases cardio-cerebrovascular risk. Circular RNAs (circRNAs) are promising biomarkers and potential therapeutic targets for atherosclerosis. Previous studies have demonstrated that tetramethylpyrazine (TMP) and paeoniflorin (PF) combination treatment (TMP-PF) inhibited oxidized low-density lipoprotein (ox-LDL)-induced angiogenesis in vitro. However, whether circRNAs regulate angiogenesis in atherosclerosis and whether TMP-PF can regulate angiogenesis-related target circRNAs in atherosclerosis are unknown. In this study, human RNA sequencing (RNA-seq) data were analysed to identify differentially expressed (DE) circRNAs in atherosclerosis and to obtain angiogenesis-associated circRNA-microRNA (miRNA)-messenger RNA (mRNA) networks. Target circRNA-related mechanisms in angiogenesis in atherosclerosis and the regulatory effects of TMP-PF on target circRNA signalling were studied in ox-LDL-induced human umbilical vein endothelial cells (HUVECs) by cell proliferation, migration, tube formation, and luciferase reporter assays, real-time quantitative polymerase chain reaction (RT-qPCR) and Western blotting. A novel circRNA (circular stimulator of chondrogenesis 1, circSCRG1) was initially identified associated with angiogenesis in atherosclerosis, and circSCRG1 silencing up-regulated miR-1268b expression, increased nuclear receptor subfamily 4 group A member 1 (NR4A1) expression and then promoted ox-LDL-induced angiogenesis. TMP-PF (1 μmol/L TMP combined with 10 μmol/L PF) up-regulated circSCRG1 expression, mediated miR-1268b to suppress NR4A1 expression and then inhibited ox-LDL-induced angiogenesis. However, circSCRG1 silencing abolished the inhibitory effects of TMP-PF on ox-LDL-induced angiogenesis, which were rescued by the miR-1268b inhibitor. In conclusion, circSCRG1 might serve as a new target regulating angiogenesis in atherosclerosis via the circSCRG1/miR-1268b/NR4A1 axis and TMP-PF could regulate the circSCRG1/miR-1268b/NR4A1 axis to inhibit angiogenesis in atherosclerosis in vitro, indicating a novel angiogenesis signalling circSCRG1/miR-1268b/NR4A1 pathway in atherosclerosis and the regulatory effects of TMP-PF, which might provide a new pharmaceutical strategy to combat atherosclerotic plaque instability.

Effects of Proteasome Inhibitor on Catalase Expression and Intima-media Thickness in the Aorta of Atherosclerotic Rats

Various studies have been carried out to obtain proper management for atherosclerosis. Proteasome, a subcellular enzyme complex, is a potential therapeutic target for atherosclerosis. However, the effect of proteasome inhibitors on atherosclerosis still needs to be explored. It was an experimental study with a post-test-only control group design conducted at the Faculty of Medicine, Universitas Riau in Juni–November 2021. This study aimed to analyze the effects of proteasome inhibitors on catalase expression and intima-media thickness (IMT) in the thoracic aorta of atherosclerotic rats. Fifteen male Wistar rats were randomly divided into three groups (five rats per group), namely rats given standard feed (control, group I), rats induced atherosclerosis (group II), and rats induced atherosclerosis and given proteasome inhibitor (group III). The proteasome inhibitor, bortezomib, 50 µg/kgBW/day was given intraperitoneally on days one and three. After 4 days, rats were terminated, and the thoracic aorta was taken for the IMT analysis and catalase expression assessment using immunohistochemistry. Catalase expression was carried out quantitatively using Adobe Photoshop software. Analysis of variance test was used to compare the expression of catalase and IMT. A p value&lt;0.05 was considered statistically significant. The results showed a significant decrease in IMT in group III compared to group II and an increase in catalase expression in group III compared to group II but not statistically significant. This study concludes that administration of bortezomib 50 µg/kg in atherosclerotic rats could inhibit thickening tunica intima-media in the thoracic aorta, although not significantly increasing the catalase expression.

The Role of Transcription Factors in Coronary Artery Disease and Myocardial Infarction.

Coronary artery disease (CAD) and its main complication, myocardial infarction (MI), is a complex disease caused by environmental and genetic factors and their interaction. Family-based linkage analysis and genome-wide association studies have indicated many of genetic variations related to CAD and MI in recent years. Some are in the coding sequence, which mediates the coding protein, while others are in the non-coding region, which affects the expression of adjacent genes and forms differential gene expression. These variants and differential expressions will have varying degrees of impact on the development of the cardiovascular system and normal heart electrical activity function, subsequently leading to CAD and MI. Among these affected genes, some Transcription Factors (TFs), as important means of transcriptional regulation, have a key role in the pathogenesis of coronary artery disease and myocardial infarction. The GATAs binding protein 2 (GATA2) enhances monocyte adhesion and promoted vessel wall permeabilization through vascular EC adhesion molecule 1 (VCAM-1) upregulation, further revealing its atherosclerosis-promoting role. Myocyte enhancer factor 2 (MEF2) has a role in fostering many functions of the atherosclerotic endothelium and is a potential therapeutic target for atherosclerosis, thrombosis, and inflammation. Nuclear factor-kappa B (NF-κB) is an important promoter of vascular endothelial growth factor (VEGF)-driven angiogenesis, and its pathway has a key role in atherosclerosis-related complications such as angiogenesis, inflammation, apoptosis, and immune effects. Activating transcription factor 3 (ATF3) may be a novel prognostic biomarker and therapeutic target for atherosclerosis. The important role of signal transducer and activator of transcription 3 (STAT3) (especially in mitochondria) in endothelial cells (EC) dysfunction, inflammation, macrophage polarization and immunity in atherosclerosis.

Abstract 13606: Deletion of CD47 Specifically in Lymphatic Endothelium Augments Arterial Lymphangiogenesis and Attenuates Atherosclerosis

Thrombospondin-1 (TSP1), an extracellular glycoprotein mediates differential physio- or pathological effects via interacting with cell surface receptors including CD36 and CD47. TSP1 is a well-known angiogenesis inhibitor, however, its role in regulating lymphangiogenesis is not clear. We recently reported that global CD47-deficient mice are protected from atherosclerosis, however, myeloid cell-specific CD47 loss augments lesion formation suggesting the importance of cell-specific CD47 blockade in atherosclerosis. Our experiments revealed CD47 as a dominant TSP1 receptor in lymphatic endothelial cells (LECs). As the lymphatic vasculature is functionally linked to atherosclerosis, we herein investigated the effects of LEC TSP1-CD47 signaling inhibition on lymphangiogenesis and atherosclerotic lesion formation. Our immunoblotting data demonstrated elevated TSP1 expression in human and mouse atherosclerotic aortic tissue compared to non-atherosclerotic control tissue. TSP1 at pathological concentrations inhibited VEGF-C-stimulated in vitro lymphangiogenesis. Mechanistically, TSP1 inhibited VEGF-C-induced Akt activation in LECs, leading to decreased eNOS phosphorylation and attenuated nitric oxide production. Further, TSP1-treated CD47-silenced LECs proliferate faster and have higher Akt and eNOS activation than TSP1-treated control cells. AAV8-PCSK9-injected LEC-specific CD47 knockout ( Cd47 f/f Lyve-1 Cre +/- ) mice had reduced atherosclerosis in both aorta and aortic root compared with control ( Cd47 f/f ) mice. Additional immunostaining experiments performed on aortic root cross-sections indicated improved lymphatic vessel density in Cd47 f/f Lyve-1 Cre +/- mice. These results demonstrate that TSP1-mediated LEC CD47 activation inhibits lymphangiogenesis and blockade of LEC CD47 signaling suppresses atherosclerosis. Altogether, these findings identify LEC CD47 as a potential therapeutic target in atherosclerosis.

Gene-dosage effect of Pfkfb3 on monocyte/macrophage biology in atherosclerosis.

Macrophage-rich atherosclerotic arteries are highly active in glycolysis. PFKFB3, a key glycolytic enzyme, has emerged as a potential therapeutic target in atherosclerosis. Small-molecule inhibitors of PFKFB3, such as 3PO and PFK158, have demonstrated efficacy in hampering atherogenesis in preclinical models. However, genetic studies elucidating the role of Pfkfb3 in atherogenesis need to be conducted to validate pharmacological findings and to unveil potential pharmacological side effects. Apoe-/- mice with global heterozygous or myeloid cell-specific Pfkfb3 deficiency were fed a Western diet (WD), after which atherosclerosis development was determined. Monocyte subsets in atherosclerotic mice and patients were examined by flow cytometry. Monocyte infiltration was assayed by a Ly6Chi monocyte-specific latex labelling procedure. In situ efferocytosis was assessed on mouse aortic root sections. Additionally, metabolic status, macrophage motility, efferocytosis, and involved mechanisms were analysed in peritoneal macrophages. Global heterozygous or myeloid cell-specific Pfkfb3 deficiency reduced atherogenesis in Apoe-/- mice. Mechanistic studies showed that PFKFB3 controlled the proliferation and infiltration of proinflammatory monocytes. Moreover, PFKFB3 expression was associated with inflammatory monocyte expansion in patients with atherosclerotic coronary artery disease. Surprisingly, homozygous loss of Pfkfb3 impaired macrophage efferocytosis and exacerbated atherosclerosis in Apoe-/- mice. Mechanistically, PFKFB3-driven glycolysis was shown to be essential for actin polymerization, thus aiding the efferocytotic function of macrophages. Collectively, these findings suggest the existence of a double-edged sword effect of myeloid PFKFB3 on the pathogenesis of atherosclerosis and highlight the need for caution in developing anti-atherosclerotic strategies that target PFKFB3.

Macrophage polarization as a potential therapeutic target for atherosclerosis: a dynamic stochastic modelling study.

We proposed a dynamic stochastic mathematical model to evaluate the role of macrophage polarization in plaque development. The dynamic process of macrophages from proliferation to death was simulated under different lipid microenvironments. The probability of macrophage phenotypic switching was described using a Bernoulli distribution where the stochastic variable was determined by the local lipid level. Moreover, the interactions between macrophages and microenvironmental factors vary with macrophage phenotype. We investigated the distribution of key microenvironmental factors, the dynamics of macrophage polarization and its influence on foam cell formation. M1 macrophages were found to predominate in advanced plaque corresponding to the exacerbated inflammation observed in mice experiments. The imbalance between the deposition of oxidized low-density lipoprotein and phagocytic effects of macrophages governed the formation of foam cells. Furthermore, we simulated targeted therapies by either directly inhibiting the polarization probability to M1 macrophages or indirectly regulating macrophage polarization due to high-density lipoprotein levels. Comparison of simulation results with experimental findings in both therapies indicated that the intervention and regulation of macrophage polarization could influence plaque microenvironment and subsequently induce plaque regression, especially in the early stage. The proposed modelling system can facilitate the evaluation of novel therapies targeting macrophage polarization.

CircRNA_0050486 promotes cell apoptosis and inflammation by targeting miR-1270 in atherosclerosis.

BackgroundAtherosclerosis (AS) is a chronic inflammatory disease that plays a major role in cardiovascular disease. Circular RNAs (circRNAs) are related to the pathogenesis of AS, including the inflammatory response. This study aimed to explore the underlying mechanisms of circRNAs and how they regulate the inflammatory response in AS.MethodsAnalyzed the expression profile of circRNAs in three oxidized low-density lipoprotein (oxLDL) treated macrophage samples and three macrophage control samples using bioinformatics methods. Expression and biological function of circRNA were verified in oxLDL-induced THP-1 macrophages. MiRNAs and target genes of circRNA were predicted by functional enrichment analysis. Expression and function of circRNA target miRNAs were explored in oxLDL-induced THP-1 macrophages. Finally, we predicted and analyzed the function of circRNAs-miRNAs target genes in AS.ResultsWe identified nine upregulated circRNAs and found that circ_0050486 was significantly upregulated in a THP-1 + PMA + oxLDL group compared with a THP-1 + PMA group. Additionally, circ_0050486 knockdown markedly inhibited IL-6 and TNF-α concentrations and the cell death rates in oxLDL-induced THP-1 macrophages. Furthermore, circ_0050486 targeted and inhibited miR-145 and miR-1270. Upregulated miR-1270 markedly inhibited IL-6 and TNF-α levels and the cell death rates in oxLDL-induced THP-1 macrophages. Finally, the target genes of miR-1270 and miR-145 were predicted by the miRDB, miRWalk, and Targetscan databases, and a functional analysis network of the target genes was constructed by Cytoscape GlueGO, including the regulation of the immune response and monocyte chemotaxis. The common target genes of miR-145 and miR-1270 were established by Cytoscape and included NF1A, among others.ConclusionsOur study suggested that circ_0050486 knockdown inhibited inflammation and apoptosis by targeting miR-1270 in oxLDL-induced THP-1 macrophages. This finding may provide a potential therapeutic target for atherosclerosis.