Nondiabetic ApoE Research Articles

ER-Stress and Senescence Coordinately Promote Endothelial Barrier Dysfunction in Diabetes-Induced Atherosclerosis.

Diabetes mellitus is hallmarked by accelerated atherosclerosis, a major cause of mortality among patients with diabetes. Efficient therapies for diabetes-associated atherosclerosis are absent. Accelerated atherosclerosis in diabetic patients is associated with reduced endothelial thrombomodulin (TM) expression and impaired activated protein C (aPC) generation. Here, we directly compared the effects of high glucose and oxidized LDL, revealing that high glucose induced more pronounced responses in regard to maladaptive unfolded protein response (UPR), senescence, and vascular endothelial cell barrier disruption. Ex vivo, diabetic ApoE−/− mice displayed increased levels of senescence and UPR markers within atherosclerotic lesions compared with nondiabetic ApoE−/− mice. Activated protein C pretreatment maintained barrier permeability and prevented glucose-induced expression of senescence and UPR markers in vitro. These data suggest that high glucose-induced maladaptive UPR and associated senescence promote vascular endothelial cell dysfunction, which—however—can be reversed by aPC. Taken together, current data suggest that reversal of glucose-induced vascular endothelial cell dysfunction is feasible.

Dulaglutide exerts beneficial anti atherosclerotic effects in ApoE knockout mice with diabetes: the earlier, the better

There has been no report about the mechanism for anti-atherosclerotic effects of dulaglutide (Dula) and/or about the difference of its effectiveness between in an early and a late phase of diabetes. To address such questions, streptozotocin (STZ) was intraperitoneally injected to ApoE knockout mice at 8 weeks of age. Either Dula or vehicle was administered to STZ-induced diabetic ApoE knockout mice from 10 to 18 weeks of age as an early intervention group and from 18 to 26 weeks as a late intervention group. Next, non-diabetic ApoE knockout mice without STZ injection were subcutaneously injected with either Dula or vehicle. In an early intervention group, atherosclerotic lesion in aortic arch and Mac-2 and CD68-positive areas in aortic root were significantly smaller in Dula group. In abdominal aorta, expression levels of some villain factors were lower in Dula group. In a late intervention group, there were no immunohistological differences in aortic root and expression levels of various factors between two groups. Furthermore, even in non-diabetic ApoE knockout mice, expression levels of inflammatory and macrophage markers were reduced by treatment with Dula. Taken together, Dula exerts more beneficial anti-atherosclerotic effects in an early phase of diabetes rather than in a late phase.

N‑acetylcysteine inhibits atherosclerosis by correcting glutathione‑dependent methylglyoxal elimination and dicarbonyl/oxidative stress in the aorta of diabetic mice.

In diabetic animal models, high plasma/tissue levels of methylglyoxal (MG) are implicated in atherosclerosis. N-acetylcysteine (NAC) is a cysteine prodrug that replenishes intracellular glutathione (GSH) levels, which can increase the elimination of MG in diabetes mellitus (DM). The present study investigated the anti-atherosclerotic role of NAC in DM and aimed to determine whether the mechanism involved GSH-dependent MG elimination in the aorta. Apolipoprotein-E knockdown (ApoE−/−) mice injected with streptozotocin for 5 days exhibited enhanced atherosclerotic plaque size in the aortic root; notably, a high-lipid diet aggravated this alteration. NAC treatment in the drinking water for 12 weeks decreased the size of the atherosclerotic lesion, which was associated with a reduction in MG-dicarbonyl stress and oxidative stress, as indicated by decreased serum malondialdehyde levels, and increased superoxide dismutase-1 and glutathione peroxidase-1 levels in the diabetic aorta. Endothelial damage was also corrected by NAC, as indicated by an increase in the expression levels of phosphorylated (p-)Akt and p-endothelial nitric oxide synthase (eNOS) in the aorta, as well as nitric oxide (NO) in the serum. In addition, MG-treated human umbilical vein endothelial cells (HUVECs) exhibited increased reactive oxygen species and decreased antioxidant enzyme expression levels. NAC treatment corrected the alteration in HUVECs induced by MG, whereas the protective role of NAC was blocked via inhibition of GSH. These findings indicated that the diabetic aorta was more susceptible to atherosclerotic lesions compared with non-diabetic ApoE−/− mice. Furthermore, NAC may offer protection against atherosclerotic development in DM by altering aortic and systemic responses via correcting GSH-dependent MG elimination, leading to decreased oxidative stress and restoration of the p-Akt/p-eNOS pathway in the aorta.

436-P: Characterization of Autoimmunity in the Acceleration of Atherosclerosis in Type 1 Diabetes

Hyperglycemia, hyperlipidemia and hypertension have been evaluated extensively as risk factors for cardiovascular disease (CVD) in people with type 1 diabetes (T1DM). However, the impact of autoimmunity in T1DM on CVD has not been determined. We have generated several mice models of atherosclerosis including ApoE-/-/NOD, ApoE-/-/NOD (congenic non diabetes and non-autoimmune), ApoE-/-/NOD (autoimmunity with insulitis, nondiabetes) and ApoE-/-/NOD autoimmune diabetic mice. All groups of mice have high plasma lipids but only ApoE-/-/NOD diabetic mice had hyperglycemia. However, ApoE-/-/NOD (insulitis and nondiabetes) and ApoE-/-/NOD (insulitis and diabetes) had high titers of autoantibodies to IA2 compared to control CongApoE-/-/NOD mice or nondiabetic ApoE-/-/NOD mice (P<0.0001). For the the severity of atherosclerosis, the presence of hyperglycemia in ApoE-/-/NOD-DM mice showed greater levels of lipid deposition in the descending aorta (22%) by en face assessment as compared to nondiabetic ApoE-/-/NOD mice (P<0.01). Similarly, we also observed in the macrophage content of the descending aorta, was greater in numbers in the ApoE-/-/NOD mice than in ApoE-/-/CongNOD mice (P<0.05) but less than in ApoE-/-/NOD-DM mice. FACS of the descending aorta showed the elevated CD3+/CD28- T-cells (CD4 and CD8) by 4.5 folds and decreased CD3+/CD28+ Treg cells by 46% at the atherosclerotic plaques of ApoE-/-/NOD mice, compared to those of CongApoE-/-/NOD mice. To further confirm the elevated infiltrate and accumulated CD3+ T-cells in vivo, we will investigate the levels of macrophages and CD3+ T-cells in the arterial wall of the coronary artery from the Medalists group T1D and autoimmunity with positive HLA DR3/4 risk alleles and autoantibodies and lacking monogenic diabetic variants, as compared to the group lacking HLA DR3/4 risk alleles and autoantibodies. These studies suggest that autoimmunity exacerbates atherosclerosis in T1D, independently and synergically hyperglycemia. Disclosure K. Park: None. Q. Li: None. H. Park: None. R. St-Louis: None. J. Fu: None. C. Rask-Madsen: None. E. Maddaloni: Consultant; Self; Merck KGaA. Speaker’s Bureau; Self; Abbott, AstraZeneca, Pikdare. H. Yokomizo: None. S. Kissler: None. A.H. Lichtman: None. G.L. King: Research Support; Self; Janssen Pharmaceuticals, Inc. Funding National Institutes of Health (R01DK053105); Thomas J. Beatson, Jr. Foundation

Integrins α4β1 and αVβ3 are Reduced in Endothelial Progenitor Cells from Diabetic Dyslipidemic Mice and May Represent New Targets for Therapy in Aortic Valve Disease

Diabetes reduces the number and induces dysfunction in circulating endothelial progenitor cells (EPCs) by mechanisms that are still uncovered. This study aims to evaluate the number, viability, phenotype, and function of EPCs in dyslipidemic mice with early diabetes mellitus and EPC infiltration in the aortic valve in order to identify possible therapeutic targets in diabetes-associated cardiovascular disease. A streptozotocin-induced diabetic apolipoprotein E knock-out (ApoE−/−) mouse model was used to identify the early and progressive changes, at 4 or 7 days on atherogenic diet after the last streptozotocin or citrate buffer injection. Blood and aortic valves from diabetic or nondiabetic ApoE−/− animals were collected. EPCs were identified as CD34 and vascular endothelial growth factor receptor 2 positive monocytes, and the expression levels of α4β1, αVβ3, αVβ5, β1, αLβ2, α5 integrins, and C-X-C chemokine receptor type 4 chemokine receptor on EPC surface were assessed by flow cytometry. The number of CD34 positive cells in the aortic valve, previously found to be recruited progenitor cells, was measured by fluorescence microscopy. Our results show that aortic valves from mice fed 7 days with atherogenic diet presented a significantly higher number of CD34 positive cells compared with mice fed only 4 days with the same diet, and diabetes reversed this finding. We also show a reduction of circulatory EPC numbers in diabetic mice caused by cell senescence and lower mobilization. Dyslipidemia induced EPC death through apoptosis regardless of the presence of diabetes, as shown by the higher percent of propidium iodide positive cells and higher cleaved caspase-3 levels. EPCs from diabetic mice expressed α4β1 and αVβ3 integrins at a lower level, while the rest of the integrins tested were unaffected by diabetes or diet. In conclusion, reduced EPC number and expression of α4β1 and αVβ3 integrins on EPCs at 4 and 7 days after diabetes induction in atherosclerosis-prone mice have resulted in lower recruitment of EPCs in the aortic valve.

Vildagliptin, a DPP-4 Inhibitor, Attenuates Endothelial Dysfunction and Atherogenesis in Nondiabetic Apolipoprotein E-Deficient Mice.

Dipeptidyl peptidase-4 (DPP-4) inhibitors are novel antidiabetic agents with possible vascular protection effects. Endothelial dysfunction is an initiation step in atherogenesis. The purpose of this study was to investigate whether vildagliptin (Vilda) attenuates the development of endothelial dysfunction and atherosclerotic lesions in nondiabetic apolipoprotein E-deficient (ApoE-/-) mice. Eight-week-old nondiabetic ApoE-/- mice fed a Western-type diet received Vilda (50 mg/kg/day) for 20 weeks or 8 weeks. After 20 weeks of treatment, Vilda administration reduced atherogenesis in the aortic arch as determined by en face Sudan IV staining compared with the vehicle group (P < 0.05). Vilda also reduced lipid accumulation (P < 0.05) and vascular cell adhesion molecule-1 (VCAM-1) expression (P < 0.05) and tended to decrease macrophage infiltration (P = 0.05) into atherosclerotic plaques compared with vehicle. After 8 weeks of treatment, endothelium-dependent vascular reactivity was examined. Vilda administration significantly attenuated the impairment of endothelial function in nondiabetic ApoE-/- mice compared with the vehicle group (P < 0.05). Vilda treatment did not alter metabolic parameters, including blood glucose level, in both study protocols. To investigate the mechanism, aortic segments obtained from wild-type mice were incubated with exendin-4 (Ex-4), a glucagon-like peptide-1 (GLP-1) analog, in the presence or absence of lipopolysaccharide (LPS). Ex-4 attenuated the impairment of endothelium-dependent vasodilation induced by LPS (P < 0.01). Furthermore, Ex-4 promoted phosphorylation of eNOS at Ser1177 which was decreased by LPS in human umbilical endothelial cells (P < 0.05). Vilda inhibited the development of endothelial dysfunction and prevented atherogenesis in nondiabetic ApoE-/- mice. Our results suggested that GLP-1-dependent amelioration of endothelial dysfunction is associated with the atheroprotective effects of Vilda.

478-P: Accelerating Atherosclerosis by Autoimmune Process in Nonobese Diabetic Mice Made ApoE Deficient by CRISPR/Cas9 Gene Editing

Although metabolic risk factors that accelerate atherosclerosis are shared between people with type 1 (T1D) and 2 (T2D) diabetes, it remains unknown whether autoimmunity in T1D contribute to cardiovascular pathologies, which have been reported for other autoimmune diseases. In order to determine the role of autoimmunity with and without overt diabetes, we generated ApoE deficient NOD (ApoE-/--NOD) mice by CRISPR/Cas9 gene editing. The ApoE-/- NOD mice spontaneously developed autoimmune diabetes and atherosclerosis. We also generated congenic ApoE-/--NOD mice that do not carry a protective MHC class II allele (CongNOD), and these mice are prone to atherosclerosis but do not develop insulitis or diabetes to control for the effects of the NOD background independently of autoimmunity. ApoE deficiency in NOD mice was ascertained by PCR and DNA sequencing in both ApoE-/--NOD mice and ApoE-/--CongNOD mice The ApoE protein expression levels in the liver and plasma of ApoE-/--NOD mice was also confirmed by immunoblot analysis and ELISA. Female and male ApoE-/--NOD mice exhibited diabetes frequencies (blood glucoses &amp;gt;500 mg/dL) of 70% and 25%, respectively. Histological analysis of pancreatic islets sections by H&amp;E staining showed peri-insulitis (25%) and insulitis (75%), similar rates as hyperglycemia in NOD mice. Nondiabetic ApoE-/--NOD mice developed more severe atherosclerosis than ApoE-/--CongNOD mice after fed Western diet (6% vs. 1.5% plaque, P&amp;lt;0.01). Preliminary studies showed that greater extent of atherosclerosis was observed in diabetic ApoE-NOD than nondiabetic ApoE-/-NOD mice by 3.2 folds. Total plasma cholesterol (884mg/dL vs. 945mg/dL) and triglyceride (185mg/dL vs. 211mg/dL) levels were high but not significant different between ApoE-/--NOD mice and ApoE-/--CongNOD mice on either a regular diet or WD. These studies indicate that T1D autoimmunity with or without hyperglycemia can exacerbate the development of atherosclerosis. Disclosure K. Park: None. Q. Li: None. H. Wang: None. R. St-Louis: None. H. Yokomizo: None. E. Maddaloni: Speaker's Bureau; Self; Merck &amp; Co., Inc., Pikdare. T. Shinjo: None. J. Fu: None. I. Wu: None. S. Kissler: None. G.L. King: Research Support; Self; Sanofi. Funding Sanofi-Aventis; National Institute of Diabetes and Digestive and Kidney Diseases (R01DK053105-17)

Tofogliflozin Suppresses the Progression of Atherosclerosis and Reduces Inflammation in Macrophages of STZ-Diabetic ApoE KO Mice due to Improvement of Glucose Tolerance

Background: Selective sodium-glucose cotransporter 2 inhibitor (SGLT2i) has become widely used for treatment of diabetes. Recently, EMPA-REG OUTCOME and CANVAS Program showed that SGLT2i reduce cardiovascular events in patients with type 2 diabetes, but the mechanism still remains uncertain. We investigated the mechanisms of vascular protection of Tofogliflozin (Tofo), one of the SGLT2i. Method: 1) Streptozotocin (STZ)-diabetic apolipoprotein-E-deficient (ApoE KO) mice were separated into two groups, one group were fed normal chow and the other were fed normal chow containing 0.005% Tofo for ad libitum. After 6weeks, all mice were administered thioglycolate intraperitoneally, and 4 days later, peritoneal macrophages were collected to investigate the expressions of inflammatory cytokines of peritoneal macrophages by real-time PCR. Histological analyses were carried out by Sudan IV, Oil Red O, and MOMA-2 staining. 2) The same experiment targeted were carried out towards nondiabetic ApoE KO mice. Results: 1) Tofo increased food and water intake and decreased blood glucose, but there were no significant changes in body weight, serum levels of free fatty acid, triglyceride and total cholesterol between two groups. The legions of atherosclerosis and macrophages accumulations were significantly suppressed in Tofo group. Moreover, the expression levels of TNF-α, IL-β were significantly suppressed in macrophages from Tofo group. 2) Nondiabetic ApoE KO mice showed similar increase in food and water intake, but failed to exhibit differences in blood glucose, Sudan IV staining, and expressions of inflammatory cytokines in macrophages, as observed in diabetic ApoE KO mice. Conclusion: Tofogliflozin suppresses the progression of atherosclerosis and reduces inflammation in macrophages of STZ- diabetic ApoE KO mice. These beneficial effects may be exerted due to improvement of glucose tolerance. Disclosure M. Iwamoto: None. N. Kubota: None. T. Kubota: None. Y. Sakurai: None. N. Wada: None. I. Takamoto: None. S. Shioda: None. T. Kadowaki: Consultant; Self; Novo Nordisk A/S, AstraZeneca, Merck Sharp &amp; Dohme Corp.. Research Support; Self; Kissei Pharmaceutical Co., Ltd., Taisho Pharmaceutical Co., Ltd., Sanofi, Kyowa Hakko Kirin Co., Ltd., Novo Nordisk A/S, Astellas Pharma, Daiichi Sankyo Company, Limited, Takeda, Mitsubishi Tanabe Pharma Corporation, Ono Pharmaceutical Co., Ltd., Merck Sharp &amp; Dohme Corp., Nippon Boehringer Ingelheim Co. Ltd.. Speaker's Bureau; Self; Astellas Pharma, AstraZeneca, Merck Sharp &amp; Dohme Corp., Ono Pharmaceutical Co., Ltd., Takeda, Eli Lilly and Company, Nippon Boehringer Ingelheim Co. Ltd., Novo Nordisk A/S.

Abstract 089: Role of LncRNA Snhg18 in Diabetes Induced Macrophage Dysfunction and Atherosclerosis

Atherosclerotic vascular disease is the major cause of mortality in diabetic patients. Evidence from our laboratory and others showed that long non-coding RNAs (lncRNAs) play important roles in diabetic vascular complications. Here we investigated role of lncRNAs in hyperglycemia-induced macrophage dysfunction and accelerated atherosclerosis in diabetes. Hyperglycemia (~300-400 mg/dl) was induced in atherosclerosis-prone ApoE -/- mice by low dose Streptozotocin injections (50mg/kg/day i.p., 5 days) and were sacrificed at 20 weeks’ post diabetes. Aortic root F4/80 immunohistochemistry and morphometric analysis showed increased macrophage infiltration and enhanced atherosclerosis respectively in diabetic vs non-diabetic ApoE -/- mice. RNA-seq analysis identified ~45 up-regulated lncRNAs in bone marrow macrophages (BMM) from diabetic versus non-diabetic ApoE -/- mice. Among these, one of the robustly induced (~7.5 log 2 fold) lncRNA candidate was small nucleolar RNA host gene 18 ( Snhg18) located on mouse chromosome 15. Gene expression analysis by RT-qPCR validated Snhg18 upregulation in BMM from diabetic ApoE -/- mice and in peritoneal macrophages from type 2 diabetic db/db vs control db/+ mice. Moreover, diabetic-ApoE -/- aortic tissue also demonstrated increased expression of Snhg18 as compared to non-diabetic ApoE -/- s . Additionally, Snhg18 was significantly increased in high glucose (HG) (25mM) treated RAW mouse macrophages in vitro . A human ortholog, SNHG18 , located on chromosome 5 was also significantly increased in HG treated human THP1 monocytes. Cellular fractionation of RAW macrophages demonstrated that Snhg18 was localized in both cytoplasmic and nuclear compartments. Overexpression of Snhg18 in RAW macrophages significantly increased expression of proinflammatory ( Il1b , Il6 , and Tnf) and proatherogenic ( Thbs1 ) genes but downregulated a nearby gene, Semaphorin 5A ( Sema5a). These results suggest that diabetes induced lncRNA Snhg18 upregulates macrophage inflammatory phenotype to modulate diabetes induced accelerated macrophage dysfunction and atherosclerosis development.

Selective Imaging of Vascular Endothelial Growth Factor Receptor-1 and Receptor-2 in Atherosclerotic Lesions in Diabetic and Non-diabetic ApoE-/- Mice.

Plaque vulnerability is associated with inflammation and angiogenesis, processes that rely on vascular endothelial growth factor (VEGF) signaling via two receptors, VEGFR-1 and VEGFR-2. We have recently reported that enhanced uptake of scVEGF-PEG-DOTA/Tc-99m (scV/Tc) single photon emission computed tomography (SPECT) tracer that targets both VEGFR-1 and VEGFR-2, identifies accelerated atherosclerosis in diabetic relative to non-diabetic ApoE-/- mice. Since VEGFR-1 and VEGFR-2 may play different roles in atherosclerotic plaques, we reasoned that selective imaging of each receptor can provide more detailed information on plaque biology. Recently described VEGFR-1 and VEGFR-2 selective mutants of scVEGF, named scVR1 and scVR2, were site-specifically derivatized with Tc-99m chelator DOTA via 3.4kDa PEG linker, and their selectivity to the cognate receptors was confirmed in vitro. scVR1 and scVR2 conjugates were radiolabeled with Tc-99m to specific activity of 110±11MBq/nmol, yielding tracers named scVR1/Tc and scVR2/Tc. 34-40week old diabetic and age-matched non-diabetic ApoE-/- mice were injected with tracers, 2-3h later injected with x-ray computed tomography (CT) contrast agent and underwent hybrid SPECT/CT imaging. Tracer uptake, localized to proximal aorta and brachiocephalic vessels, was quantified as %ID from. Tracer uptake was also quantified as %ID/g from gamma counting of harvested plaques. Harvested atherosclerotic arterial tissue was used for immunofluorescent analyses of VEGFR-1 and VEGFR-2 and various lineage-specific markers. Focal, receptor-mediated uptake in proximal aorta and brachiocephalic vessels was detected for both scVR1/Tc and scVR2/Tc tracers. Uptake of scVR1/Tc and scVR2/Tc was efficiently inhibited only by "cold" proteins of the same receptor selectivity. Tracer uptake in this area, expressed as %ID, was higher in diabetic vs. non- diabetic mice for scVR1/Tc (p=0.01) but not for scVR2/Tc. Immunofluorescent analysis revealed enhanced VEGFR-1 prevalence in and around plaque area in diabetic mice. Selective VEGFR-1 and VEGFR-2 imaging of atherosclerotic lesions may be useful to explore plaque biology and identify vulnerability.

Neuregulin-1 attenuates development of nephropathy in a type 1 diabetes mouse model with high cardiovascular risk.

Neuregulin-1 (NRG-1) is an endothelium-derived growth factor with cardioprotective and antiatherosclerotic properties and is currently being tested in clinical trials as a treatment for systolic heart failure. In clinical practice, heart failure often coexists with renal failure, sharing an overlapping pathophysiological background. In this study, we hypothesized that NRG-1 might protect against cardiomyopathy, atherosclerosis, and nephropathy within one disease process. We tested this hypothesis in a hypercholesterolemic apolipoprotein E-deficient (apoE(-/-)) type 1 diabetes mouse model prone to the development of cardiomyopathy, atherosclerosis, and nephropathy and compared the effects of NRG-1 with insulin. Upon onset of hyperglycemia induced by streptozotocin, apoE(-/-)mice were treated with vehicle, insulin, or recombinant human (rh)NRG-1 for 14 wk and were compared with nondiabetic apoE(-/-)littermates. Vehicle-treated diabetic apoE(-/-)mice developed left ventricular (LV) dilatation and dysfunction, dense atherosclerotic plaques, and signs of nephropathy. Nephropathy was characterized by abnormalities including hyperfiltration, albuminuria, increased urinary neutrophil gelatinase-associated lipocalin (NGAL), upregulation of renal fibrotic markers, and glomerulosclerosis. rhNRG-1 treatment induced systemic activation of ErbB2 and ErbB4 receptors in both heart and kidneys and prevented LV dilatation, improved LV contractile function, and reduced atherosclerotic plaque size. rhNRG-1 also significantly reduced albuminuria, NGALuria, glomerular fibrosis, and expression of fibrotic markers. Regarding the renal effects of rhNRG-1, further analysis showed that rhNRG-1 inhibited collagen synthesis of glomerular mesangial cells in vitro but did not affect AngII-induced vasoconstriction of glomerular arterioles. In conclusion, systemic administration of rhNRG-1 in hypercholesterolemic type 1 diabetic mice simultaneously protects against complications in the heart, arteries and kidneys.

Amelioration of Hyperglycemia with a Sodium-Glucose Cotransporter 2 Inhibitor Prevents Macrophage-Driven Atherosclerosis through Macrophage Foam Cell Formation Suppression in Type 1 and Type 2 Diabetic Mice.

Direct associations between hyperglycemia and atherosclerosis remain unclear. We investigated the association between the amelioration of glycemia by sodium-glucose cotransporter 2 inhibitors (SGLT2is) and macrophage-driven atherosclerosis in diabetic mice. We administered dapagliflozin or ipragliflozin (1.0 mg/kg/day) for 4-weeks to apolipoprotein E-null (Apoe −/−) mice, streptozotocin-induced diabetic Apoe −/− mice, and diabetic db/db mice. We then determined aortic atherosclerosis, oxidized low-density lipoprotein (LDL)-induced foam cell formation, and related gene expression in exudate peritoneal macrophages. Dapagliflozin substantially decreased glycated hemoglobin (HbA1c) and glucose tolerance without affecting body weight, blood pressure, plasma insulin, and lipids in diabetic Apoe −/− mice. Aortic atherosclerotic lesions, atheromatous plaque size, and macrophage infiltration in the aortic root increased in diabetic Apoe −/− mice; dapagliflozin attenuated these changes by 33%, 27%, and 20%, respectively. Atherosclerotic lesions or foam cell formation highly correlated with HbA1c. Dapagliflozin did not affect atherosclerosis or plasma parameters in non-diabetic Apoe −/− mice. In db/db mice, foam cell formation increased by 4-fold compared with C57/BL6 mice, whereas ipragliflozin decreased it by 31%. Foam cell formation exhibited a strong correlation with HbA1c. Gene expression of lectin-like ox-LDL receptor-1 and acyl-coenzyme A:cholesterol acyltransferase 1 was upregulated, whereas that of ATP-binding cassette transporter A1 was downregulated in the peritoneal macrophages of both types of diabetic mice. SGLT2i normalized these gene expressions. Our study is the first to demonstrate that SGLT2i exerts anti-atherogenic effects by pure glucose lowering independent of insulin action in diabetic mice through suppressing macrophage foam cell formation, suggesting that foam cell formation is highly sensitive to glycemia ex vivo.

Abstract 13192: Dipeptidyl Peptidase-4 Inhibitor, Linagliptin, Ameliorates Endothelial Dysfunction and Atherogenesis in Apolipoprotein-e Deficient Mice Through GLP-1 Dependent and Independent Manners

Background: The dipeptidyl peptidase-4 (DDP-4) inhibitors are a novel class of drug for the treatment of diabetes mellitus. Several studies suggested that their anti-inflammatory effects contribute to the prevention of cardiovascular complication of diabetes. This study aimed to investigate whether linagliptin, a xanthine-based DPP-4 inhibitor, attenuates endothelial dysfunction and prevents subsequent atherogenesis in non-diabetic apolipoprotein-E deficient (ApoE KO) mice. Methods and Results: Linagliptin (10 mg/kg/day) was administered orally to 8-week-old ApoE KO mice for 20 weeks. Linagliptin administration reduced atherosclerotic lesion progression in the aortic arch as determined by en-face Sudan IV staining compared with the control group (P&lt;0.05) without the alteration of metabolic parameters including blood glucose level. Plasma active GLP-1 was significantly higher in the treated group. Histological and quantitative RT-PCR analyses demonstrated that linagliptin decreased macrophages accumulation and the expression of inflammatory molecules (e.g; MCP-1 and VCAM-1) in atherosclerotic aorta (P&lt;0.05, respectively). Furthermore, linagliptin significantly attenuated the impairment of endothelial function in ApoE KO mice, as determined by acetylcholine-dependent vasodilation. These vasoprotective effects of linagliptin were associated with the decreased ROS generation as determined by urinary 8-OHdG level and the expression of NOX-2, in the abdominal aorta. Incubation of aortic segments from C57BL/6 mice with exendin-4 (Ex-4), a GLP-1 analogue, ameliorated palmitic acid (PA)-induced impairment of endothelium-dependent vasodilation. Ex-4 ameliorated impaired phosphorylation of Akt and eNOSSer1177 caused by PA in human umbilical vein endothelial cells (HUVECs). In addition, linagliptin directly attenuated PA-induced and eNOSSer1177 phosphorylation in HUVECs. Conclusion: Linagliptin inhibited the development of atherogenesis in non-diabetic ApoE KO mice. Our results suggested that linagliptin ameliorated endothelial dysfunction and oxidative stress through GLP-1 dependent and independent manners

Dipeptidyl peptidase-4 inhibitor, linagliptin, ameliorates endothelial dysfunction and atherogenesis in normoglycemic apolipoprotein-E deficient mice

BackgroundDipeptidyl peptidase-4 (DPP-4) inhibitors have vasoprotective effects. This study investigated whether a recently approved DPP-4 inhibitor, linagliptin (Lina), suppresses atherogenesis in non-diabetic apolipoprotein-E deficient (ApoE−/−) mice, and examined its effects on endothelial function. Methods and resultsLina (10mg/kg/day) was administered orally to ApoE−/− mice for 20weeks. Lina reduced atherogenesis without alteration of metabolic parameters including blood glucose level compared with control (P<0.05). Results of immunohistochemical analyses and quantitative RT-PCR demonstrated that Lina significantly decreased inflammatory molecule expression and macrophage infiltration in the atherosclerotic aorta. Lina administration to ApoE−/− mice for 9weeks ameliorated endothelium-dependent vasodilation compared with that in untreated mice. Plasma active glucagon-like peptide-1 (GLP-1) level was significantly higher in the treated group (P<0.05). Exendin-4 (Ex-4), a GLP-1 analog, ameliorated endothelium-dependent vasodilation impaired by palmitic acid (PA) in wild-type mouse aortic segments. Ex-4 promoted phosphorylation of eNOSSer1177 and Akt, both of which were abrogated by PA, in human umbilical vein endothelial cells. In addition, Lina administration to ApoE−/− mice decreased oxidative stress, as determined by urinary 8-OHdG secretion and NADPH oxidase subunit expression in the abdominal aorta. ConclusionLina inhibited atherogenesis in non-diabetic ApoE−/− mice. Amelioration of endothelial dysfunction associated with a reduction of oxidative stress by GLP-1 contributes to the atheroprotective effects of Lina.

Attenuation of atherosclerotic lesions in diabetic apolipoprotein E-deficient mice using gene silencing of macrophage migration inhibitory factor.

Macrophage migration inhibitory factor (MIF) involves the pathogenesis of atherosclerosis (AS) and increased plasma MIF levels in diabetes mellitus (DM) patients are associated with AS. Here, we have been suggested that MIF could be a critical contributor for the pathological process of diabetes-associated AS by using adenovirus-mediated RNA interference. First, streptozotocin (STZ)-induced diabetic animal model was constructed in 114 apolipoprotein E-deficient mice (apoE−/− mice) fed on a regular chow diet. Then, the animals were randomly divided into three groups: Adenovirus-mediated MIF interference (Ad-MIFi), Ad-enhanced green fluorescent protein (EGFP) and normal saline (NS) group (n ≈ 33/group). Non-diabetic apoE−/− mice (n = 35) were served as controls. Ad-MIFi, Ad-EGFP and NS were, respectively, injected into the tail vein of mice from Ad-MIFi, Ad-EGFP and NS group, which were injected repeatedly 4 weeks later. Physical, biochemical, morphological and molecular parameters were measured. The results showed that diabetic apoE−/− mice had significantly aggravated atherosclerotic lesions. MIF gene interference attenuated atherosclerotic lesions and stabilized atheromatous plaque, accompanied by the decreased macrophages and lipids deposition and inflammatory cytokines production, improved glucose intolerance and plasma cholesterol level, the decreased ratio of matrix matalloproteinase-2/tissue inhibitor of metalloproteinase-1 and plaque instability index. An increased expression of MIF and its ligand CD74 was also detected in the diabetic patients with coronary artery disease. The results suggest that MIF gene interference is able to inhibit atherosclerotic lesions and increase plaque stability in diabetic apoE−/−mice. MIF inhibition could be a novel and promising approach to the treatment of DM-associated AS.

Abstract 13248: DPP-4 Inhibition Reduces Atherosclerosis by Priming Monocytes into Alternative M2 Macrophages

Introduction: Major parts of the population in the western world are suffering from atherosclerotic diseases like coronary and peripheral artery disease or stroke. Interventional and pharmacological therapies at present focus on the treatment of vascular stenoses, secondary prophylaxis or reduction of cardiovascular risk factors. Hypothesis: In this project, we want to establish the pharmacological inhibition of DPP4 as a new therapeutic concept focussing on macrophage polarization during development of atherosclerosis. Methods: Non-diabetic ApoE-/- mice were treated with normal diet or high fat diet for three months to induce arterial atherosclerotic lesion formation. The descending aorta was stained using Oil-Red-O to quantify atherosclerotic lesions. In parallel mice were treated with Sitagliptin or placebo. Macrophage subtype content (M1, M2) in the aortic wall was quantified using FACS. Results: Mice on high fat diet treated with Sitagliptin showed a dramatic reduction in atherosclerotic lesion formation in contrast to placebo treated animals. Regarding total macrophage content in the vascular wall we could not detect a difference between the treatment groups. However, the number of protective M2 macrophages was more than tripled in the gliptin-treated animals. Moreover, the number of mural M2 macrophages inversely correlated with the aortic plaque burden. In further analyses we could demonstrate that Sitagliptin favoured macrophage polarization to alternatively activated M2 macrophages via the CXCR4-signaling pathway. Conclusions: We demonstrated that long-term Sitagliptin treatment in ApoE-/- animals on high fat diet can successfully inhibit atherosclerotic lesion formation via induction of macrophage polarization to the protective M2 phenotype. Due to the promising results of this study we are currently planning to transfer the underlying therapeutical concept into a randomized clinical trial.

Pharmacological inhibition of NOX reduces atherosclerotic lesions, vascular ROS and immune–inflammatory responses in diabetic Apoe −/− mice

Enhanced vascular inflammation, immune cell infiltration and elevated production of reactive oxygen species (ROS) contribute significantly to pro-atherogenic responses in diabetes. We assessed the immunomodulatory role of NADPH oxidase (NOX)-derived ROS in diabetes-accelerated atherosclerosis. Diabetes was induced in male Apoe(-/-) mice with five daily doses of streptozotocin (55 mg kg(-1) day(-1)). Atherosclerotic plaque size, markers of ROS and immune cell accumulation were assessed in addition to flow cytometric analyses of cells isolated from the adjacent mediastinal lymph nodes (meLNs). The role of NOX-derived ROS was investigated using the NOX inhibitor, GKT137831 (60 mg/kg per day; gavage) administered to diabetic and non-diabetic Apoe(-/-) mice for 10 weeks. Diabetes increased atherosclerotic plaque development in the aortic sinus and this correlated with increased lesional accumulation of T cells and CD11c(+) cells and altered T cell activation in the adjacent meLNs. Diabetic Apoe(-/-) mice demonstrated an elevation in vascular ROS production and expression of the proinflammatory markers monocyte chemoattractant protein 1, vascular adhesion molecule 1 and IFNγ. Blockade of NOX-derived ROS using GKT137831 prevented the diabetes-mediated increase in atherosclerotic plaque area and associated vascular T cell infiltration and also significantly reduced vascular ROS as well as markers of inflammation and plaque necrotic core area. Diabetes promotes pro-inflammatory immune responses in the aortic sinus and its associated lymphoid tissue. These changes are associated with increased ROS production by NOX. Blockade of NOX-derived ROS using the NOX inhibitor GKT137831 is associated with attenuation of these changes in the immune response and reduces the diabetes-accelerated development of atherosclerotic plaques in Apoe(-/-) mice.

BMP4 is increased in the aortas of diabetic ApoE knockout mice and enhances uptake of oxidized low density lipoprotein into peritoneal macrophages

BackgroundBMP4, a member of the transforming growth factor-beta superfamily, is upregulated in the aortas of diabetic db/db mice. However, little is known about its role in diabetic atherosclerosis. Therefore, we examined the roles of BMP4 in the formation of diabetic atherosclerosis in apolipoprotein E knockout (ApoE KO) mice and in the uptake of oxidized low density lipoprotein (oxLDL) in peritoneal macrophages of wild-type mice.MethodsTo induce diabetes, ApoE KO mice were intraperitoneally injected with streptozotocin. Diabetic and non-diabetic ApoE KO mice were then fed a high-fat diet for 4 weeks. Next, to investigate a role of BMP4 in the peritoneal macrophages, we examined the uptake of oxLDL in BMP4-treated macrophages.ResultsDiabetic ApoE KO mice showed accelerated progression of aortic plaques accompanied by increased luminal plaque area. Western blot analysis showed that BMP4 expression in the whole aorta was greatly increased in diabetic ApoE KO mice, than non-diabetic mice. Western blot analysis showed that the BMP4/SMAD1/5/8 signaling pathway was strongly activated in the aorta from diabetic ApoE KO mice, compared with control ApoE KO mice. Double immunofluorescence staining showed that BMP4 was expressed in MOMA2-labeled macrophage in the aortic lesions of ApoE KO mice. BMP4 significantly increased the uptake of oxLDL into peritoneal macrophages in vitro.ConclusionWe show that in the aorta of diabetic ApoE KO mice, BMP4 is increased and activates SMAD1/5/8. Our in vitro findings indicate that BMP4 enhances oxLDL uptake in mouse peritoneal macrophages, suggesting BMP4 may be involved in aortic plaque formation in diabetic ApoE KO mice. Targeting BMP4 may offer a new strategy for inhibition of plaque progression and stabilization of atherosclerotic lesions.

Preventive Effect of Dipeptidyl Peptidase-4 Inhibitor on Atherosclerosis Is Mainly Attributable to Incretin's Actions in Nondiabetic and Diabetic Apolipoprotein E-Null Mice

AimSeveral recent reports have revealed that dipeptidyl peptidase (DPP)-4 inhibitors have suppressive effects on atherosclerosis in apolipoprotein E-null (Apoe −/−) mice. It remains to be seen, however, whether this effect stems from increased levels of the two active incretins, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP).MethodsNontreated Apoe −/− mice, streptozotocin-induced diabetic Apoe −/− mice, and db/db diabetic mice were administered the DPP-4 inhibitor vildagliptin in drinking water and co-infused with either saline, the GLP-1 receptor blocker, exendin(9–39), the GIP receptor blocker, (Pro3)GIP, or both via osmotic minipumps for 4 weeks. Aortic atherosclerosis and oxidized low-density lipoprotein-induced foam cell formation in exudate peritoneal macrophages were determined.ResultsVildagliptin increased plasma GLP-1 and GIP levels without affecting food intake, body weight, blood pressure, or plasma lipid profile in any of the animals tested, though it reduced HbA1c in the diabetic mice. Diabetic Apoe −/− mice exhibited further-progressed atherosclerotic lesions and foam cell formation compared with nondiabetic counterparts. Nondiabetic and diabetic Apoe −/− mice showed a comparable response to vildagliptin, namely, remarkable suppression of atherosclerotic lesions with macrophage accumulation and foam cell formation in peritoneal macrophages. Exendin(9–39) or (Pro3)GIP partially attenuated the vildagliptin-induced suppression of atherosclerosis. The two blockers in combination abolished the anti-atherosclerotic effect of vildagliptin in nondiabetic mice but only partly attenuated it in diabetic mice. Vildagliptin suppressed macrophage foam cell formation in nondiabetic and diabetic mice, and this suppressive effect was abolished by infusions with exendin(9–39)+(Pro3)GIP. Incubation of DPP-4 or vildagliptin in vitro had no effect on macrophage foam cell formation.ConclusionsVildagliptin confers a substantial anti-atherosclerotic effect in both nondiabetic and diabetic mice, mainly via the action of the two incretins. However, the partial attenuation of atherosclerotic lesions by the dual incretin receptor antagonists in diabetic mice implies that vildagliptin confers a partial anti-atherogenic effect beyond that from the incretins.

Supplementation of Cyanidin-3-O-β-Glucoside Promotes Endothelial Repair and Prevents Enhanced Atherogenesis in Diabetic Apolipoprotein E–Deficient Mice1–3

Atherosclerosis is accelerated in diabetes mellitus mainly due to the reduced availability and function of endothelial progenitor cells (EPCs). The purpose of this study was to determine the protective effects of the anthocyanin cyanidin-3-O-β-glucoside (C3G) on EPC function and endothelial repair in diabetic apolipoprotein E–deficient (apoE−/−) mice. Diabetes mellitus was induced in 8-wk-old male apoE−/− mice with streptozotocin. Diabetic apoE−/− mice were fed the AIN-93 diet or an AIN-93 diet supplemented with C3G (0.2% wt:wt) for 6 wk. Sham-injected apoE−/− mice fed the AIN-93 diet served as nondiabetic controls. The endothelium-dependent relaxation response to acetylcholine in the aortas of C3G-fed mice was greater by 51% compared with diabetic mice fed the AIN-93 diet (P < 0.05) and was similar to that in nondiabetic apoE−/− mice. The capacity of in vitro adhesion to fibronectin, migration, and tube formation was significantly impaired in diabetic EPCs (decreased by 83, 61.9, and 74.5%, respectively, compared with nondiabetic controls; all P < 0.01), which was significantly rescued in response to C3G (increased by 3.9-, 2-, and 1.8-fold compared with diabetic EPCs, respectively; all P < 0.05). At the molecular level, the phosphorylation levels of AMP-activated protein kinase (AMPK) Thr 172 and endothelial nitric oxide synthase (eNOS) Ser1177 were higher in EPCs derived from the C3G-treated diabetic mice compared with those in nondiabetic mice. Furthermore, compared with nondiabetic controls, diabetic apoE−/− mice had a 3.5-fold increase in the aortic lesion area, which was lowered by 45% in C3G-fed diabetic mice. This study extends our current knowledge that C3G improves the impairment of EPC function, enhances endothelial repair, and thus limits accelerated atherogenesis caused by diabetes. Our findings emphasize the potential utility of anthocyanin in the prevention and treatment of diabetic vascular complications.