Aortic Lipid Deposition Research Articles

Aged garlic oligosaccharides modulate host metabolism and gut microbiota to alleviate high-fat and high-cholesterol diet-induced atherosclerosis in ApoE−/− mice

Atherosclerosis (AS) is a cardiovascular disease caused by excessive accumulation of lipids in arterial walls. In this study, we developed an AS model in ApoE−/− mice using a high-fat, high-cholesterol diet and investigated the anti-AS mechanism of aged garlic oligosaccharides (AGOs) by focusing on the gut microbiota. Results revealed that AGOs exhibited significant anti-AS effects, reduced trimethylamine N-oxide levels from 349.9 to 189.2 ng/mL, and reduced aortic lipid deposition from 31.7 % to 9.5 %. AGOs significantly increased the levels of short-chain fatty acids in feces, in which acetic, propionic, and butyric acids were increased from 1.580, 0.364, and 0.469 mg/g to 2.233, 0.774, and 0.881 mg/g, respectively. An analysis of the gut microbiota indicated that AGOs restored alpha and beta diversity, decreased the Firmicutes/Bacteroidetes ratio, and promoted the dominance of the genus Akkermansia. A metagenomic analysis revealed that AGOs alleviated AS through the ABC transporter pathway and the lipopolysaccharide biosynthesis pathway.

The Lian-Dou-Qing-Mai Formula activates the PPARγ-LXRα-ABCA1/ABCG1 pathway by regulating IL-10, leading to the promotion of cholesterol efflux and a reduction in atherosclerotic plaques.

To observe the effect of the Lian-Dou-Qing-Mai (LDQM) formula on lipid metabolism in mice and explore its mechanism from the perspective of regulating the PPARγ/LXRα/ABCA1 signaling pathway. THP-1 cells were induced to transform into foam cells with ox-LDL. Atherosclerosis (AS) models were constructed using a high-fat diet in ApoE-/- mice. Detection kits were used to evaluate triglyceride (TG) and total cholesterol (TC) content; TNF-α, MCP-1, MMP-9, TMP-1, PPARγ, LXRα, ABCA1, and ABCG1 mRNA and protein expression were identified using real-time PCR and western blot. Interleukin-10 (IL-10) blood levels were measured using an enzyme-linked immunosorbent assay (ELISA), and aortic plaque development and lipid deposition were seen using hematoxylin and eosin (HE) and oil red O staining, respectively. In the cell model, LDQM could inhibit the formation of THP-1 macrophage-derived foam cells and the expression of inflammatory factors, promote macrophage cholesterol efflux, increase the expression of IL-10, and activate the PPARγ-LXRα-ABCA1/ABCG1 pathway. Additional IL-10 treatment further promotes LDQM-induced cholesterol efflux in THP-1 cells; in In vivo models, LDQM inhibited the area of atherosclerotic lesions, aortic lipid deposition, and inflammation levels in ApoE-/- mice through IL-10, and activated the expression level of the PPARγ-LXRα-ABCA1/ABCG1 pathway. LDQM may affect the PPARγ/LXRα/ABCA1 signaling pathway through IL-10, regulate lipid metabolism, reduce serum inflammatory expression and lipid deposition, and improve the formation of atheroplaques.

Sortilin-induced lipid accumulation and atherogenesis are suppressed by HNF1b SUMOylation promoted by flavone of Polygonatum odoratum.

This study aims to investigate the impact of hepatocyte nuclear factor 1β (HNF1b) on macrophage sortilin-mediated lipid metabolism and aortic atherosclerosis and explore the role of the flavone of Polygonatum odoratum (PAOA-flavone)-promoted small ubiquitin-related modifier (SUMO) modification in the atheroprotective efficacy of HNF1b. HNF1b was predicted to be a transcriptional regulator of sortilin expression via bioinformatics, dual-luciferase reporter gene assay, and chromatin immunoprecipitation. HNF1b overexpression decreased sortilin expression and cellular lipid contents in THP-1 macrophages, leading to a depression in atherosclerotic plaque formation in low-density lipoprotein (LDL) receptor-deficient (LDLR-/-) mice. Multiple SUMO1-modified sites were identified on the HNF1b protein and co-immunoprecipitation confirmed its SUMO1 modification. The SUMOylation of HNF1b protein enhanced the HNF1b-inhibited effect on sortilin expression and reduced lipid contents in macrophages. PAOA-flavone treatment promoted SUMO-activating enzyme subunit 1 (SAE1) expression and SAE1-catalyzed SUMOylation of the HNF1b protein, which prevented sortilin-mediated lipid accumulation in macrophages and the formation of atherosclerotic plaques in apolipoprotein E-deficient (ApoE-/-) mice. Interference with SAE1 abrogated the improvement in lipid metabolism in macrophage cells and atheroprotective efficacy in vivo upon PAOA-flavone administration. In summary, HNF1b transcriptionally suppressed sortilin expression and macrophage lipid accumulation to inhibit aortic lipid deposition and the development of atherosclerosis. This anti-atherosclerotic effect was enhanced by PAOA-flavone-facilitated, SAE1-catalyzed SUMOylation of the HNF1b protein.

Imbalance of helper T cell subtypes and adipokine secretion in perivascular adipose tissue as a trigger of atherosclerosis in chronic Porphyromonas gingivalis W83 infection

Periodontal disease, a prevalent oral disease, is an independent risk factor for atherosclerosis. Porphyromonas gingivalis (P.g), a keystone pathogen of periodontal disease, contributes to the pathogenesis of atherosclerosis. However, the exact mechanism remains unclear. An increasing number of studies have proposed the atherogenic influence of perivascular adipose tissue (PVAT) in pathological conditions including hyperlipidemia and diabetes. Nevertheless, the role of PVAT in atherosclerosis promoted by P.g infection has not been explored. In our study, we investigated the association between P.g colonization in PVAT and progression of atherosclerosis through experiments on clinical samples. We further investigated P.g invasion of PVAT, PVAT inflammation, aortic endothelial inflammation, aortic lipid deposition, and systemic inflammation in C57BL/6 J mice with or without P.g infection at 20, 24, and 28 weeks of age. PVAT inflammation, characterized by imbalance in Th1/Treg and dysregulated adipokine levels, was associated with P.g invasion, preceding endothelial inflammation that occurred independently of its direct invasion. The phenotype of systemic inflammation coincided with that of PVAT inflammation, but systemic inflammation occurred after endothelial inflammation. Therefore PVAT inflammation in early atherosclerosis could be a primary trigger of aortic endothelial inflammation and lipid deposition in chronic P.g infection, through the dysregulated paracrine secretion of T helper-1-related adipokines.

Rosuvastatin Attenuates Progression of Atherosclerosis and Reduces Serum IL6 and CCL2 Levels in Apolipoprotein-E-deficient Mice.

Apolipoprotein E-deficient (Apoe-/-) mice develop atherosclerotic lesions that closely resemble metabolic syndrome in humans. We sought to investigate how rosuvastatin mitigates the atherosclerotic profile of Apoe-/- mice over time and its effects on certain inflammatory chemokines. Eighteen Apoe-/- mice were allocated into three groups of six mice each receiving: standard chow diet (SCD; control group); high-fat diet (HFD); and HFD and rosuvastatin at 5 mg/kg/d orally via gavage for 20 weeks. Analysis of aortic plaques and lipid deposition was conducted by means of en face Sudan IV staining and Oil Red O staining. Serum cholesterol, low-density lipoprotein, high-density lipoprotein, plasma glucose and triglyceride levels were determined at baseline and after 20 weeks of treatment. Serum interleukin 6 (IL6), C-C motif chemokine ligand 2 (CCL2) and tumor necrosis factor-α (TNFα) levels were measured by enzyme-linked immunosorbent assay at the time of euthanasia. The lipidemic profile of Apoe-/- mice on HFD deteriorated over time. Apoe-/- mice on HFD developed atherosclerotic lesions over time. Sudan IV and Oil Red O-stained sections of the aorta revealed increased plaque formation and plaque lipid deposition in HFD-fed mice compared with SCD-fed mice and reduced plaque development in HFD-fed mice treated with rosuvastatin compared with mice not receiving statin treatment. Serum analysis revealed reduced metabolic parameters in HFD-fed mice on rosuvastatin compared with non-statin, HFD-fed mice. At the time of euthanasia, HFD-fed mice treated with rosuvastatin had significantly lower IL6 as well as CCL2 levels when compared with HFD-fed mice not receiving rosuvastatin. TNFα levels were comparable among all groups of mice, irrespective of treatment. IL6 and CCL2 positively correlated with the extent of atherosclerotic lesions and lipid deposition in atherosclerotic plaques. Serum IL6 and CCL2 levels might potentially be used as clinical markers of progression of atherosclerosis during statin treatment for hypercholesterolemia.

Sichuan dark tea improves lipid metabolism and prevents aortic lipid deposition in diet-induced atherosclerosis model rats.

Sichuan dark tea (ST), Zangcha, is a traditional fermented Chinese tea found in Sichuan and Tibet and claimed for beneficial effects against lifestyle-related metabolic disorders. We examined the effects of ST on lipid metabolism and atherosclerosis. Sichuan dark tea was given to fat-rich diet-induced atherosclerosis model rats in comparison with dark-fermented Chinese Pu-erh tea (PT) and Japanese green tea (GT). After 8 weeks of feeding, ST and PT induced an increase in high-density lipoprotein (HDL)-cholesterol and a decrease in glucose, and ST decreased triglyceride in plasma. ST also induced low pH in the cecum. There was no significant change in their body weight among the fat-feeding groups but a decrease was found in the visceral fat and liver weight in the ST group. Accordingly, ST reduced lipid deposition in the aorta in comparison with PT and GT. ST increased mRNA of LXRα, PPARα, PPARγ, and ABCA1 in the rat liver. The extract of ST stimulated the AMPK pathway to increase the expression of ABCA1 in J774 cells and increased expression of lipoprotein lipase and hormone-sensitive lipase in 3T3L1 cells, consistent with its anti-atherogenic effects in rats. High-performance liquid chromatography analysis showed unique spectra of original specific compounds of caffeine and catechins in each tea extract, but none of them was likely responsible for these effects. Sichuan dark tea increases plasma HDL and reduces plasma triglyceride to decrease atherosclerosis through AMPK activation. Further study is required to identify specific components for the effects of this tea preparation.

A High Cholesterol Diet During Late Pregnancy Impairs Long-Term Maternal Vascular Function in Mice.

Gestational dyslipidemia is associated with pregnancy complications including preeclampsia. However, whether gestational dyslipidemia leads postpartum vascular dysfunction, which could increase the risk for cardiovascular complications later in life, is not known. Here, we aimed to determine whether a gestational dyslipidemia affects postpartum vascular health and induces early signs of atherosclerosis. Pregnant C57BL/6 mice received a high cholesterol diet or control diet from gestational day 13.5 until term. After delivery, all mice received the control diet for ≈3 months postpartum (PP). Age-matched nulliparous females were on the same diets for equal periods. After 3 months, all mice were euthanized, serum was collected, and aortas were isolated to assess vascular function (wire myography) and markers of oxidative stress and early atherosclerosis. PP-high cholesterol diet females had increased circulating cholesterol levels compared with PP-control diet mice, without effect of the diet in nulliparous mice. Methacholine-induced vasodilation was impaired, and nitric oxide contribution reduced, by the high cholesterol diet in aortas of PP mice, but not in nulliparous mice. Exposure to oxidized low-density-protein cholesterol further impaired methylcholine-induced vasodilation in PP-high cholesterol diet aortas only. Compared with PP-control diet mice, aortic inducible nitric oxide synthase expression, reactive oxygen species and nitrotyrosine levels were increased in aortas from PP-high cholesterol diet mice. No differences in aortic lipid deposition and macrophage infiltration were found. Exposure to a high cholesterol diet in pregnancy impairs vascular function postpartum. Our results support the hypothesis that gestational dyslipidemia impacts maternal vascular function after pregnancy, which could potentially predispose these women to future cardiovascular complications.

Butter-Derived Ruminant Trans Fatty Acids Do Not Alleviate Atherosclerotic Lesions in High-Fat Diet-Fed ApoE-/- Mice.

Atherosclerosis (AS) is the most common cardiovascular disease (CVD). Currently, it is widely believed that R-TFA and I-TFA may cause different biological effects. In the present study, we aim to elucidate the effect of mixed R-TFA derived from butter on the development of AS in high-fat diet-fed ApoE-/- mice and find the possible mechanism. It was shown that butter-derived R-TFA promoted dyslipidemia, reduced thoracic and abdominal aorta diameters, and induced aortic lipid deposition and atherosclerotic lesions in high-fat diet-fed ApoE-/- mice. Meanwhile, butter-derived R-TFA affected the serum lipid profile of high-fat diet-fed ApoE-/- mice and the lipid metabolism of human umbilical vein endothelial cells (HUVECs). Through lipidomic techniques, we found that butter-derived R-TFA had a significant effect on the glycerophospholipid metabolic pathway. In conclusion, our results demonstrated that butter-derived R-TFA does not alleviate but promotes atherosclerotic lesions in high-fat diet-fed ApoE-/- mice and that the glycerophospholipid metabolic pathway plays a major role in this pro-atherosclerotic effect.

Altered Mitochondrial Opa1-Related Fusion in Mouse Promotes Endothelial Cell Dysfunction and Atherosclerosis.

Flow (shear stress)-mediated dilation (FMD) of resistance arteries is a rapid endothelial response involved in tissue perfusion. FMD is reduced early in cardiovascular diseases, generating a major risk factor for atherosclerosis. As alteration of mitochondrial fusion reduces endothelial cells’ (ECs) sprouting and angiogenesis, we investigated its role in ECs responses to flow. Opa1 silencing reduced ECs (HUVECs) migration and flow-mediated elongation. In isolated perfused resistance arteries, FMD was reduced in Opa1+/− mice, a model of the human disease due to Opa1 haplo-insufficiency, and in mice with an EC specific Opa1 knock-out (EC-Opa1). Reducing mitochondrial oxidative stress restored FMD in EC-Opa1 mice. In isolated perfused kidneys from EC-Opa1 mice, flow induced a greater pressure, less ATP, and more H2O2 production, compared to control mice. Opa1 expression and mitochondrial length were reduced in ECs submitted in vitro to disturbed flow and in vivo in the atheroprone zone of the mouse aortic cross. Aortic lipid deposition was greater in Ldlr−/--Opa1+/- and in Ldlr−/--EC-Opa1 mice than in control mice fed with a high-fat diet. In conclusion, we found that reduction in mitochondrial fusion in mouse ECs altered the dilator response to shear stress due to excessive superoxide production and induced greater atherosclerosis development.

Crocin ameliorates atherosclerosis by promoting the reverse cholesterol transport and inhibiting the foam cell formation via regulating PPARγ/LXR-α

ABSTRACT Crocin (CRO) is feasible in alleviating atherosclerosis (AS), the mechanism of which was therefore explored in the study. High-fat diet (HFD)-induced apolipoprotein E-deficient (ApoE−/−) mice and lysophosphatidic acid (LPA)-treated macrophages received CRO treatment. Treated macrophage viability was determined via MTT assay. In both murine and macrophage, the lipid level and total Cholesterol/Cholesteryl l Ester (TC/CE) levels were quantified by oil-red-O staining and ELISA, respectively. Lipid droplet, aortic plaque formation and collagen deposition were detected via Oil-red-O staining, hematoxylin–eosin staining and Masson staining, respectively. Liver X Receptor-α (LXR-α), Peroxisome Proliferator-Activated Receptor γ (PPARγ), CD68, PCSK9, CD36, ATP Binding Cassette Subfamily A Member 1 (ABCA1), phosphorylated (p)-AKT, and AKT expressions were detected via Western blot, the former three also being detected using Immunohistochemistry and the first being measured by qRT-PCR. CRO decreased HFD-induced weight gain, ameliorated the abnormal serum lipid levels of HFD-treated mice, and inhibited aortic plaque formation and lipid deposition, and increased collagen fibers, with upregulated high-density lipoprotein-cholesterol (HDL-C) and downregulated TC and low-density lipoprotein-cholesterol (LDL-C). CRO alleviated the HFD-induced upregulations of CD68, PCSK9 and CD36 as well as downregulations of PPARγ/LXR-α, ABCA1 and AKT phosphorylation. In LPA-treated macrophages, CRO alone exerted no effect on the viability yet inhibited the lipid droplets formation and downregulated TC/CE levels. Silent LXR-α reversed the effect of CRO on the lipid droplets formation and levels of lipid metabolism-related factors. CRO ameliorated AS by inhibiting foam cells formation and promoting reverse cholesterol transport via PPARγ/LXR-α.

Morphological and functional characterization of diabetic cardiomyopathy in db/db mice following exercise, metformin alone, or combination treatments

The aim of the study was to explore different effects of exercise, metformin alone, or exercise combined with metformin on cardiovascular morphological and functional changes in early stage of type 2 diabetes mellitus. Eight-week-old diabetic db/db mice and BKS mice were recruited and exposed to three different treatments (exercise, metformin alone, or their combination) for 8 weeks. Metformin was administered intragastrically, and aerobic exercise was performed using treadmill with 7–12 m/min, 30–40 min/day, 5 days/week. In the combination group, aerobic exercise was carried out for 30 min after intragastric administration of metformin. The results showed that all three treatments improved cardiac fibrosis and aortic lipid deposition. Exercise intervention failed to alleviate myocardial hypertrophy, but it improved the declined heart rate and diastolic blood pressure in diabetic db/db mice. In contrast, metformin caused opposite effects in these mice. The combination of exercise and metformin had additive effects on glucose intolerance and insulin sensitivity rather than on the improvement of myocardial and aortic structure. In conclusion, metformin improved changes in the morphology and structure of the heart and aorta, while exercise alone or in combination with metformin demonstrated more advantages in cardiac functional reserve through the physiological hypertrophy of myocardium in diabetic db/db mice.

Expression of Cyr61 in ApoE\u2212/\u2212 mice with chronic unilateral renal artery ligation

Cyr61 is a member of the CCN family of proteins that is expressed in atherosclerotic lesions and regulated by angiotensin II. It is unknown whether renal artery stenosis (RAS) increases Cyr61 expression. Male ApoE−/− mice were randomized to surgically induced RAS, RAS + treatment with either irbesartan, aliskiren or amlodipine or sham-surgery. RAS resulted in increased plasma angiotensin II levels, a mild, sustained increase in systolic blood pressure and increased aortic lipid deposition compared to sham-surgery. Surgically induced RAS led to the formation of atheroma in the infrarenal aorta and there was consistent and intense staining for Cyr61 within the atheroma. Treatment with irbesartan, aliskiren and amlodipine were associated with decreased aortic lipid deposition and decreased staining for Cyr61 in aortic atheroma. Serum levels of Cyr61 were not increased in mice or humans with RAS. In summary, Cyr61 expression in aortic atheroma but not serum is increased by RAS in ApoE−/− mice and is reduced by agents that lower blood pressure.

Kefir peptides alleviate high-fat diet-induced atherosclerosis by attenuating macrophage accumulation and oxidative stress in ApoE knockout mice

In the past decade, the high morbidity and mortality of atherosclerotic disease have been prevalent worldwide. High-fat food consumption has been suggested to be an overarching factor for atherosclerosis incidence. This study aims to investigate the effects of kefir peptides on high-fat diet (HFD)-induced atherosclerosis in apolipoprotein E knockout (ApoE−/−) mice. 7-week old male ApoE−/− and normal C57BL/6 mice were randomly divided into five groups (n = 8). Atherosclerotic lesion development in ApoE−/− mice was established after fed the HFD for 12 weeks compared to standard chow diet (SCD)-fed C57BL/6 and ApoE−/− control groups. Kefir peptides oral administration significantly improved atherosclerotic lesion development by protecting against endothelial dysfunction, decreasing oxidative stress, reducing aortic lipid deposition, attenuating macrophage accumulation, and suppressing the inflammatory immune response compared with the HFD/ApoE−/− mock group. Moreover, the high dose of kefir peptides substantially inhibited aortic fibrosis and restored the fibrosis in the aorta root close to that observed in the C57BL/6 normal control group. Our findings show, for the first time, anti-atherosclerotic progression via kefir peptides consumption in HFD-fed ApoE−/− mice. The profitable effects of kefir peptides provide new perspectives for its use as an anti-atherosclerotic agent in the preventive medicine.

SAT-041 Testosterone Reduces Atherosclerosis and Plaque Specific Inflammatory Markers in the ApoE-/- Mouse Model

Low serum testosterone in men is an established cardiovascular risk factor and epidemiological evidence demonstrates an association between low testosterone and with coronary events. Clinical evidence suggests that testosterone therapy (Tth) can improve key cardiovascular risk factors in men and surrogate measures of atherosclerosis, the chronic inflammatory process underlying cardiovascular disease. Atherosclerotic plaque-specific testosterone actions are not fully understood. The present study investigates the influence of testosterone on mediators of vascular inflammation and plaque burden in an in vivo model of atherosclerosis. ApoE-/- mice were either sham operated, castrated or castrated and received fortnightly intramuscular injections of physiological doses of testosterone (mixed testosterone esters, Sustanon 100) to create 3 experimental groups; normal testosterone, testosterone deficient and testosterone replaced respectively. All groups were fed a high-fat ‘Western’ diet for 16 weeks. Lipid deposition in the aortic root was assessed by Oil Red O as an indication of atherosclerotic burden. Plaque composition was assessed immunohistochemically for indicators of stability including collagen content via Masson’s trichrome, and α-smooth muscle actin (αSMA) as well as markers of inflammation including vascular cell adhesion molecule-1 (VCAM-1), intracellular adhesion molecule-1 (ICAM-1), endothelial-leukocyte adhesion molecule 1 (E-Selectin), and a pan monocyte/macrophage marker (MOMA2). Testosterone deficient castrated mice had significantly increased lipid accumulation in the aortic root compared to testosterone replete sham-operated littermates (48% intima-media area vs 40%, p<0.05). Tth in castrated mice reversed this effect (39%, p<0.05). Plaque stability was not altered between groups. MOMA2 staining indicated increased infiltration and localisation of monocytes/macrophages in the plaques of castrated mice compared to sham-operated (positive staining (% of plaque) 77% vs 59%, P=0.062) and Tth treatment reduced this (77% vs 63%, P=0.1). Vascular cell adhesion molecule-1 (VCAM-1) and intracellular adhesion molecule-1 (ICAM-1) expression were reduced in castrated mice receiving Tth compared to castrated mice receiving saline (33% vs 46%, p<0.05; and 39% vs 58%, P=0.084 respectively). No significant difference in expression of E-Selectin and αSMA were observed between groups. These findings demonstrate that low testosterone increases aortic root lipid deposition and inflammatory composition in a mouse model of atherosclerosis. Increasing testosterone levels through Tth reduces plaque specific inflammatory markers and atherosclerotic burden. This indicates an anti-inflammatory mechanism by which testosterone can protect against the development and progression of atherosclerosis to reduce cardiovascular risk in men.

473-P: Identification of Novel Genes Participating in Diabetic Macrovascular Complications by DNA Methylation Modulation

Diabetic vascular complications contribute to the increased morbidity and mortality of diabetic patients. However, the mechanism of diabetic macrovascular complication remains unclear. Objective: We intend to unleash the role of DNA methylation modification in the pathological process of diabetic macrovascular complication and identify the potential biomarkers that could be beneficial for early intervention. Methods: We screened for differentially methylated genes by methylated DNA immunoprecipitation chip (MeDIP-chip) in diabetic patients. The validation of MeDIP-chip was performed by methylation-specific PCR (MSP). Furthermore, we investigated the expressions of the aberrantly methylated genes and their functions in the model of diabetic mice. Results: Serval aberrantly methylated genes have been explored, including phospholipase C beta 1 (PLCB1), cam kinase I delta (CAMK1D), and dopamine receptor D5 (DRD5) which participated in calcium signaling pathway. Meanwhile, vascular endothelial growth factor B (VEGFB), placental growth factor (PLGF), fatty acid transport protein 3 (FATP3), coagulation factor II thrombin receptor (F2R), and fatty acid transport protein 4 (FATP4) which participated in vascular endothelial growth factor receptor (VEGFR) signaling pathway, were also been found. After MSP and gene expression validation in peripheral blood of patients, PLCB1, PLGF, FATP4, and VEGFB were corroborated. Combining with the detection of fatty acid uptake by radionuclide tracing, DNA methylation regulated VEGFR signaling pathway was demonstrated to mediate the lipid deposition in aortas of diabetic mice. Conclusions: Our study identifies novel biomarkers and therapeutic targets in diabetic macrovascular complications. DNA methylation in VEGFR signaling pathway might play an important role in diabetic macrovascular complications. Disclosure Y. Liao: None. L. Chen: None. T. Zeng: None. Funding National Natural Science Foundation of China

SAT-001 Supra-Physiological Testosterone Treatment Reduces Aortic Atheroma but Increases Markers of Cardiac Hypertrophy

Supra-physiological Testosterone Treatment Reduces Aortic Atheroma but Increases Markers of Cardiac Hypertrophy The impact of testosterone on the cardiovascular system is controversial and concerns have been raised in regard to the safety of testosterone replacement therapy (TTh) in hypogonadal men with cardiovascular disease. We have examined the effects of supra-physiological concentrations of testosterone upon aortic fatty streak formation in high-fat diet-fed testicular feminized (Tfm) mice, which exhibit non-functional androgen receptors (AR) and low circulating testosterone levels. Tfm mice were fed a high-cholesterol diet ad libitum for 28 weeks and received fortnightly intramuscular injections of either saline (Tfm, n=8, XY, n=8), 10uL of 250mg/mL testosterone alone (Tfm, n=8, XY, n=8), or in conjunction with either a 30uL intramuscular injection of 50mg/ml estrogen receptor-alpha antagonist fulvestrant (Tfm, n=8), or with 10mg/kg/day of aromatase inhibitor anastrazole in drinking water (Tfm, n=7). Cardiac tissue mRNA was analysed by qPCR for markers of hypertrophy (ANP, BNP, alpha-actin, MYH7, Gsk3-beta, SM22-alpha). A significant reduction in aortic fatty streak formation was observed in Tfm mice receiving supra-physiological testosterone compared to those receiving saline; 1.25+0.36% versus 2.85+0.37% respectively (p<0.01). No significant increase in aortic lipid deposition was observed in XY littermates administered supra-physiological testosterone compared to those receiving saline; 0.22+0.13% versus 0.32+0.12% respectively (p=ns). Aortic fatty streak formation in Tfm mice receiving supra-physiological testosterone in conjunction with fulvestrant or anastrazole was similar to that observed in Tfm mice receiving supra-physiological testosterone therapy alone; 0.71+0.18% and 1.09+0.81% respectively versus 1.25+0.36% (both p=ns) indicating non-genomic actions of testosterone. Hypertrophic markers and heart weights were elevated in XY littermates receiving supra-physiological testosterone but not in Tfm mice compared to placebo suggesting AR-dependent actions. This evidence suggests that supra-physiological levels of testosterone protect against diet induced aortic atheroma formation, at least in part, via non-genomic mechanisms but incur increased cardiovascular risk by potentially inducing cardiac hypertrophy via AR-dependent actions. Dose titration to physiological levels and careful monitoring of patients throughout treatment is key to eliciting the beneficial cardiovascular effects of TTh in hypogonadal men.

Reduced Levels of Testosterone Induce LDL Oxidation and Atherosclerotic Lesions Involving Inflammatory Imbalance and Reduced Macrophage Apoptosis

Atherosclerosis is among the major cardiovascular diseases that cause death in the world. Men who are deficient in androgen hormones are more susceptible to this disease. The aim of this study was to evaluate the influence of reduced levels of testosterone on the lipid profile, pro and anti-inflammatory cytokines, apoptosis of peritoneal macrophages and the development of atherosclerosis in LDLr-/-mice, as well as on the levels of OxLDL in healthy male humans. Tissues and organs of the experimental animals were used to evaluate lipid deposition in aorta and apoptosis of peritoneal macrophages. In humans the levels of testosterone and OxLDL were analyzed in blood samples from healthy male subjects, who were divided into two groups: low level and high level of testosterone. Animals with decreased testosterone did not present changes in the lipid profile or the levels of IL-6 and TNF-α. However, a decrease in IL-10 and an increase in the IL-6/IL-10 and TNF-α/IL-10 ratios were observed. An increase in the aorta lipid deposition was observed and a decrease in macrophage apoptosis was also demonstrated. In humans, there was an increase of OxLDL in the group with lower levels of testosterone. The findings suggest that decreasing endogenous testosterone levels may induce the development of atherosclerosis, with participation of inflammatory response and macrophage apoptosis. This is reinforced by our human studies, where individuals with low testosterone levels had higher LDL oxidation, which may predict a high atherosclerotic risk for these men.

Sortilin promotes macrophage cholesterol accumulation and aortic atherosclerosis through lysosomal degradation of ATP-binding cassette transporter A1 protein.

Sortilin is closely associated with hyperlipidemia and the risk of atherosclerosis (AS). The role of sortilin and the underlying mechanism in peripheral macrophage are not fully understood. In this study, we investigated the effect of macrophage sortilin on ATP-binding cassette transporter A1 (ABCA1) expression, ABCA1-mediated cholesterol efflux, and aortic AS. Macrophage sortilin expression was upregulated by oxidized low-density lipoproteins (ox-LDLs) in both concentration- and time-dependent manners. Its expression reached the peak level when cells were incubated with 50μg/ml ox-LDL for 24h. Overexpression of sortilin in macrophage reduced cholesterol efflux, leading to an increase in intracellular total cholesterol, free cholesterol, and cholesterol ester. Sortilin was found to bind with ABCA1 protein and suppress macrophage ABCA1 expression, resulting in a decrease in cholesterol efflux from macrophages. The inhibitory effect of sortilin in cholesterol efflux was partially reversed by treatment with chloroquine, a lysosomal inhibitor. On the contrary, the ABCA1 protein level and ABCA1-mediated cholesterol efflux is increased by sortilin short hairpin RNA transfection. The fecal and biliary cholesterol 3H-sterol from cholesterol-laden mouse peritoneal macrophage was reduced by sortilin overexpression through lentivirus vector (LV)-sortilin in low-density lipoprotein receptor knockout mice, which was prevented by co-treatment with chloroquine. Treatment with LV-sortilin reduced plasma high-density lipoprotein and increased plasma ox-LDL levels. Accordingly, aortic lipid deposition and plaque area were exacerbated, and ABCA1 expression was reduced in mice in response to infection with LV-sortilin alone. These effects of LV-sortilin were partially reversed by chloroquine. Sortilin enhances lysosomal degradation of ABCA1 protein and suppresses ABCA1-mediated cholesterol efflux from macrophages, leading to foam cell formation and AS development.

Vascular protease‐activated receptor 4 upregulation, increased platelet aggregation, and coronary lipid deposits induced by long‐term dabigatran administration – results from a diabetes animal model

Essentials The impact of long-term thrombin inhibition outside the coagulation cascade is far from clear. We aimed to assess the impact of dabigatran etexilate (DE) in diabetic and control rats. In diabetic rats, DE increased platelet aggregation and lead to coronary lipid deposits. Long-term thrombin inhibition may increase atherosclerotic and atherothrombotic risk. SUMMARY: Background Besides its role in the coagulation cascade, thrombin contributes to platelet aggregation and to a plethora of non-hemostatic functions. Objectives To assess the impact of long-term thrombin inhibition with dabigatran etexilate (DE) on platelet aggregation and on extrahemostatic thrombin-related functions in diabetic and control rats. Methods Markers of inflammation, endothelial dysfunction, oxidative stress, angiogenesis and cell adhesion molecules were quantified in control rats (Control; n = 6), DE-treated control rats (Control-Dabi; n = 8), diabetic rats (Diabetes; n = 5), and DE-treated diabetic rats (Diabetes-Dabi; n = 8). Agonist-induced platelet aggregation, aortic and coronary lipid deposits and aortic protease-activated receptor 4 (PAR4) expression were also assessed. Results Control-Dabi rats showed significantly higher high-sensitivity C-reactive protein, von Willebrand factor (VWF), vascular endothelial growth factor (VEGF) and fibronectin levels, and significantly lower PAR4 agonist-induced aggregation, than Control rats. Control-Dabi rats also showed mild aortic lipid deposits, whereas no such changes were observed in Control rats. Diabetes-Dabi rats showed significantly higher VWF, VEGF and fibronectin levels than Diabetes rats, and similar PAR4 agonist-induced aggregation as Diabetes rats, and significantly higher ADP-induced aggregation than Diabetes rats. Coronary lipid deposits were observed in 75% of Diabetes-Dabi rats and in none of the Diabetes rats. PAR4 expression was 20.4% higher in Control-Dabi rats and 27.4% higher in Diabetes-Dabi rats than in their non-treated peers. Conclusions This study indicates that long-term thrombin inhibition increases vascular PAR4 expression, promotes atherosclerosis-related mechanisms, and, in diabetic rats, increases platelet aggregation and favors the occurrence of coronary lipid deposits. These experimental data suggest that long-term thrombin inhibition may increase atherosclerotic and atherothrombotic risk, particularly in the presence of diabetes.

Stanozolol promotes lipid deposition in the aorta through an imbalance in inflammatory cytokines and oxidative status in LDLr knockout mice fed a normal diet.

The aim of the study was to evaluate the effect of an anabolic steroid, stanozolol, in a model of atherosclerosis and to investigate the involvement of the modulation of the inflammatory cytokines and oxidative stress in vascular lipid deposition. Low-density lipid receptor-deficient (LDLr-/-) mice were fed a standard chow diet and were each week injected subcutaneously either saline (control C group) or 20mg/kg stanozolol (S group). After 8weeks, the levels of cholesterol, oxidized LDL (OxLDL) and cytokines were measured in plasma, lipid deposition in aorta was evaluated by en face analysis, and thiobarbituric acid-reactive substances and oxidation protein were determined in liver. The S group demonstrated increases in vascular lipid deposition, triglycerides and non-HDL cholesterol levels. Stanozolol increased tumour necrosis factor alpha (TNF-α) and decreased interleukin-10 as well as increased the TNF-α/IL-10 ratio. Furthermore, oxidative stress was observed in the S group, as indicated by an increase in the plasma OxLDL, as well as by lipid peroxidation and oxidation of proteins in the liver. Chronic treatment with stanozolol promoted lipid deposition in the LDLr-/- mice that could be attributed to a modification of the circulating cytokine levels and systemic oxidative stress. Our results suggest that the anabolic steroid stanozolol in the absence of functional LDL receptors by increasing systemic inflammation and oxidative stress may increase the risk of development and progression of atherosclerosis.