Plaque Area In Aortic Root Research Articles

The Roles of Aerobic Exercise and Folate Supplementation in Hyperhomocysteinemia-Accelerated Atherosclerosis.

Hyperhomocysteinemia (HHcy) is an independent risk factor for atherosclerosis. Effective interventions to reduce HHcy-accelerated atherosclerosis are required. This study aimed to investigate the effects of aerobic exercise (AE) and folate (FA) supplementation on plasma homocysteine (Hcy) level and atherosclerosis development in a mouse model. Six-week-old female apoE-/- mice were grouped into five groups (N = 6-8): HHcy (1.8 g/L DL-homocysteine (DL-Hcy) in drinking water), HHcy + AE (1.8 g/L DL-Hcy and aerobic exercise training on a treadmill), HHcy + FA (1.8 g/L DL-Hcy and 0.006% folate in diet), HHcy + AE + FA (1.8 g/L DL-Hcy, 0.006% folate, and aerobic exercise training on a treadmill), and a control group (regular water and diet). All treatment was sustained for 8 weeks. Triglyceride, cholesterol, lipoprotein, and Hcy levels were determined enzymatically. Plaque and monocyte chemoattractant protein-1 (MCP-1) expression levels in mouse aortic roots were evaluated by immunohistochemistry. Compared to the HHcy group (18.88 ± 6.13 μmol/L), plasma Hcy concentration was significantly reduced in the HHcy + AE (14.79 ± 3.05 μmol/L, p = 0.04), HHcy + FA (9.4 ± 3.85 μmol/L, p < 0.001), and HHcy + AE + FA (9.33 ± 2.21 μmol/L, p < 0.001) groups. Significantly decreased aortic root plaque area and plaque burden were found in the HHcy + AE and HHcy + AE + FA groups compared to those in the HHcy group (both p < 0.05). Plasma MCP-1 level and MCP-1 expression in atherosclerotic lesions were significantly decreased in the HHcy + AE and HHcy + AE + FA groups compared to the HHcy group (all p < 0.05). AE reduced atherosclerosis development in HHcy apoE-/- mice independently of reducing Hcy levels. FA supplementation decreased plasma Hcy levels without attenuating HHcy-accelerated atherosclerosis. AE and FA supplementation have distinct mechanisms in benefiting atherosclerosis.

Abstract P3032: Liver-directed Mitochondrial Uncoupling Attenuates The Progression Of Early And Late-stage Atherosclerosis In Mice

Atherosclerotic cardiovascular disease (CVD) remains a leading cause of morbidity and mortality in people with type 2 diabetes (T2D) and new therapies are urgently needed. We recently developed an orally available, liver-directed controlled-release mitochondrial protonophore (CRMP) and showed that this agent safely reverses hypertriglyceridemia, fatty liver, and T2D in rodent and nonhuman primate models of obesity by promoting a subtle sustained increase in hepatic mitochondrial inefficiency. To determine the effect of CRMP on atherogenesis, we performed intervention studies in which 12-week Western-diet fed Ldlr -/- mice with established atherosclerosis were treated with CRMP (30 mg/kg-day) or vehicle control for an additional 12 weeks. CRMP-treated mice displayed a significant reduction in fasting plasma and hepatic triglyceride content, independently of changes in body weight, fasting plasma glucose, insulin or cholesterol levels. Morphometric analysis of the aortic root and brachiocephalic artery revealed that CRMP treatment significantly reduced total plaque area and neutral lipid accumulation. CRMP treatment also decreased markers of plaque vulnerability, as evidenced by a reduction in necrotic core area and increase in fibrous cap area ( P &lt;0.05 vs veh). To determine the mechanisms by which CRMP attenuated atherosclerosis, we performed progression studies in Ldlr -/- mice fed a Western diet containing CRMP or vehicle control for 12 weeks. Similarly to the intervention studies, CRMP significantly reduced aortic root plaque area, neutral lipid accumulation and necrotic core area. These changes were associated with a reduction in plasma triglyceride content and improvement in whole-body insulin sensitivity as assessed by hyperinsulinemic-euglycemic clamps (all P &lt;0.05 vs veh). Single-cell RNA sequencing of whole aortas from CRMP and vehicle-treated Ldlr -/- mice revealed that CRMP reduced the frequency of inflammatory macrophages compared to vehicle (~19% vs ~2%), consistent with an immune-dampening effect of CRMP. Taken together, these data support an anti-atherogenic role for CRMP and suggest the therapeutic potential of liver-directed mitochondrial uncouplers for the treatment of early and late-stage atherosclerosis.

The Mineralocorticoid Receptor in Myeloid Cells Promotes Vascular Inflammation and Atherosclerosis via Transcriptional Regulation of Selplg

Elevated plasma aldosterone (Aldo) is associated with increased risk of cardiovascular (CV) ischemia, and inhibition of the Aldo-activated mineralocorticoid receptor (MR) reduces CV-related mortality. Ischemic events including heart attack and stroke are caused by rupture of atherosclerotic plaques with abundant leukocytes. In mouse models of atherosclerosis, MR antagonists reduce plaque size and inflammation. MR in myeloid cells (MyMR) regulates macrophage (Mp) polarization in vitro, but its role in vascular inflammation in vivo is unknown. Here we test the hypothesis that MyMR contributes to vascular inflammation by facilitating leukocyte recruitment. A MyMR-knockout (KO) mouse was created (LysM-Cre/MRfl/fl) and crossed with atheroprone apolipoprotein E-KO (ApoE) mice. Eight-week-old male and female MyMR-intact/ApoE-KO and MyMR-KO/ApoE-KO littermates were fed high fat diet for 8 weeks to accelerate atherogenesis. Aortic root plaque area was modestly decreased with MyMR-KO. FACS analysis of aortic arch plaques revealed fewer Mp (37%, p < 0.01) and T cells (26%, p < 0.05) with MyMR-KO among both sexes. Female plaques were larger but had fewer myeloid (34%, p < 0.05) and T cells (30%, p < 0.01) compared to male plaques. Seven-week-old LysM-Cre/MRfl/fl mice were injected with TNFa intraperitoneally, and leukocyte trafficking was quantified in the mesenteric veins by intravital microscopy four hours later. Male and female MyMR-KO mice had 40% fewer slow-rolling cells (p < 0.0001) and 56% fewer adherent cells (p < 0.01) compared to MyMR-intact controls. There were 39% fewer slow-rolling cells in females versus males (p < 0.01). To explore mechanism, expression of leukocyte adhesion ligands was quantified by FACS in circulating leukocytes and RT-PCR in peritoneal Mp. Surface levels of P-selectin glycoprotein ligand-1 (Selplg) was attenuated on monocytes, but not on granulocytes or T cells, from MyMR-KO mice, particularly among males. Selplg mRNA was decreased by 35% in Mp from MyMR-KO mice (p < 0.05). To determine whether Selplg is transcriptionally regulated by the MR, U937 cells were pre-treated with the MR antagonist spironolactone (1 μM, Spiro) and then treated with Aldo (10 nM). Spiro alone decreased Selplg transcription (p < 0.05) compared to vehicle. Aldo increased Selplg transcription (p < 0.05) compared to vehicle, and this effect was blocked by Spiro (p < 0.0001). MyMR-KO decreases plaque size and inflammation, which may be partially due to a role of MyMR in leukocyte recruitment in early atherosclerosis likely by regulation of Selplg. The sex differences in leukocyte trafficking and plaque inflammation are worth further exploration as a mechanism for female protection from CV disease. This study suggests that MyMR regulation of vascular inflammation is a novel mechanism for the association of Aldo with increased ischemic events and supports testing of MR antagonists to prevent CV ischemia.

459-P: Liver-Targeted Mitochondrial Uncoupling by CRMP Improves Whole-Body Insulin Sensitivity and Attenuates Atherosclerosis in A LDLR-/- Mouse Model of Metabolic Syndrome

Progress in preventing cardiovascular disease (CVD) has been stalled by the growing epidemic of type 2 diabetes, which increases the relative risk of developing atherosclerosis four-fold compared to nondiabetic individuals. We recently developed an orally available, liver-targeted controlled release mitochondrial protonophore (CRMP) that promotes oxidation of hepatic triglycerides by promoting a subtle sustained increase in hepatic mitochondrial inefficiency and shown that this agent safely reverses dyslipidemia, fatty liver, and insulin resistance in rodents and nonhuman primates. While these studies suggest that CRMP may be a novel therapy for the major components of metabolic syndrome, its therapeutic utility for the treatment of CVD remains unknown. To assess the effect of CRMP on atherogenesis, we performed progression studies in Ldlr-/- mice fed a high-fat cholesterol diet and treated with CRMP (30 mg/kg-day) or vehicle control for 12 weeks. Here, we show that CRMP-treated mice display a 30% reduction in fasting plasma triglycerides (which could be attributed to a 20% decrease in VLDL-production) and a significant improvement in both hepatic and peripheral insulin sensitivity, due to reductions in hepatic and muscle ectopic lipid content. Importantly, CRMP-mediated decreases in hypertriglyceridemia and improvements in whole-body insulin sensitivity were associated with a 30% reduction in aortic root plaque area and neutral lipid accumulation (P&amp;lt;0.05). More detailed analysis of these plaques revealed that CRMP treatment also significantly lowered markers of plaque vulnerability, as evidenced by a 30% reduction in necrotic core area and increase in fibrous cap area (P&amp;lt;0.05). Conclusion: Taken together, these results support an anti-atherogenic role for CRMP and suggest the therapeutic potential of liver-targeted mitochondrial uncouplers for the treatment of cardiometabolic disorders. Disclosure L. Goedeke: None. N. Rotllan: None. K. Toussaint: None. A. Nasiri: Employee; Spouse/Partner; Medtronic. X. Zhang: None. J. Lee: None. X. Zhang: None. C. Fernández-Hernando: None. G.I. Shulman: Advisory Panel; Self; AstraZeneca, Janssen Research &amp; Development, LLC, Merck &amp; Co., Inc. Advisory Panel; Spouse/Partner; Merck &amp; Co., Inc. Consultant; Self; Novo Nordisk A/S. Consultant; Spouse/Partner; Novo Nordisk A/S. Other Relationship; Self; Gilead Sciences, Inc., iMetabolic Biopharma Corporation. Other Relationship; Spouse/Partner; iMetabolic Biopharma Corporation. Other Relationship; Self; Maze Therapeutics. Funding National Institutes of Health (R01DK119968, R01DK116774, P30DK045735 to G.I.S.), (K99 HL150234 to L.G.)

Leptin dose-dependently decreases atherosclerosis by attenuation of hypercholesterolemia and induction of adiponectin

ObjectivesConflicting evidence concerning leptin in atherosclerosis has been published. Furthermore, dose-dependent effects of leptin on atherogenesis have not been studied. MethodsLeptin-deficient low-density lipoprotein receptor (LDLR) knockout (LDLR−/−;ob/ob) mice were treated with saline, 0.1, 0.5, or 3.0mg/kg body weight (BW)/d recombinant leptin over 12weeks starting at 8weeks of age. Aortic root and brachiocephalic artery (BCA) atherosclerotic lesions were analyzed by oil red O staining. Furthermore, glucose homeostasis, lipid metabolism, and liver function including tissue studies were assessed in all animals. ResultsLeptin treatment dose-dependently decreased BW in LDLR−/−;ob/ob mice as compared to saline. Mice in the 0.1 and 0.5mg/kgBW/d groups remained heavier (i.e. subphysiological leptin dose) and in the 3.0mg/kgBW/d group had similar weight (i.e. physiological leptin dose) as compared to non-leptin-deficient LDLR−/− animals. Recombinant leptin dose-dependently reduced plaque area in the aortic root and the BCA by 36% and 58%, respectively. Leptin-mediated reductions of plasma total and LDL-cholesterol (Chol) remained independent predictors for aortic root plaque area. Chol content in liver, as well as hepatic expression of key lipid and proinflammatory genes, were dose-dependently regulated by leptin. Furthermore, leptin treatment increased circulating levels and adipose tissue mRNA expression of the adipokine adiponectin. ConclusionsLeptin administration within the subphysiological to physiological range diminishes atherosclerotic lesions. Leptin appears to mediate its antiatherogenic effects indirectly through reduction of hypercholesterolemia and liver steatosis, as well as upregulation of insulin-sensitizing and atheroprotective adiponectin.

Social disruption stress increases IL-6 levels and accelerates atherosclerosis in ApoE−/− mice

IntroductionWe have previously shown that different forms of stress have distinctive effects on atherogenesis in mice. We showed that social stress increase atherosclerosis in ApoE−/− mice, while more physical forms of stress do not. Here we evaluated the effect of social disruption (SDR) stress on atherogenesis and evaluated cytokine release after SDR-stress and five more physical stressors. MethodsMale ApoE−/− mice were exposed to SDR-stress during 12weeks, and atherosclerotic plaque area was assessed in aorta, aortic root and innominate artery. Further, male C57BL/6 mice were exposed to SDR-stress or five physical stressors, and cytokine and corticosterone levels were analyzed in plasma/serum samples immediately after stress. ResultsWe found a correlation between the level of SDR-stress and atherosclerotic plaque area in aorta and a numerical increased plaque area in aortic root. SDR stress did not affect histological features of plaque composition. However, SDR-stress increased levels of corticosterone, IL-6 and CXCL1. Plasma corticosterone increased for all five physical stressors, but IL-6 and CXCL1 only increased in the group exposed to restraint combined with rat odor. ConclusionsThese findings suggest that SDR-stress is indeed atherogenic, in contrast to our previous results using the physical stressors. A possible explanation to this difference is that SDR-stress, but not physical stressors, leads to release of the pro-inflammatory cytokines IL-6 and CXCL1.

Decreased expression of klotho gene in uremic atherosclerosis in apolipoprotein E-deficient mice

Chronic renal failure (CRF) markedly accelerates the development of atherosclerosis, but the pathogenesis of uremic atherosclerosis remains to be elucidated. The klotho gene, predominantly expressed in the kidney, plays a key role in regulating aging and the development of age-related diseases in mammals. A loss of klotho results in multiple aging-like phenotypes including atherosclerosis. This study examines the relationship between the klotho expression and the development of accelerated atherosclerosis in uremic state.Eight-week-old apolipoprotein E-deficient (apo-E−/−) male mice underwent 5/6 partial kidney ablation to induce CRF or sham-operation. At 6 wk after nephrectomy, CRF mice showed significantly increased aortic plaque area fraction, aortic root plaque area and aortic cholesterol content as compared with non-CRF mice. Serum urea, total cholesterol and triglyceride concentrations were significantly higher in CRF apo-E−/− mice compared with non-CRF controls. Moreover, the expression of renal klotho gene and the serum levels of klotho protein were markedly decreased in CRF mice compared with controls.These results suggested that CRF favored atherosclerosis in apo-E−/− mice and uremic atherosclerosis was accompanied by down-regulation of klotho expression.

Chronic renal failure accelerates atherogenesis in apolipoprotein E-deficient mice.

Cardiovascular mortality is 10 to 20 times increased in patients with chronic renal failure (CRF). Risk factors for atherosclerosis are abundant in patients with CRF. However, the pathogenesis of cardiovascular disease in CRF remains to be elucidated. The effect of CRF on the development of atherosclerosis in apolipoprotein E-deficient male mice was examined. Seven-week-old mice underwent 5/6 nephrectomy (CRF, n = 28), unilateral nephrectomy (UNX, n = 24), or no surgery (n = 23). Twenty-two weeks later, CRF mice showed increased aortic plaque area fraction (0.266 +/- 0.033 versus 0.045 +/- 0.006; P < 0.001), aortic cholesterol content (535 +/- 62 versus 100 +/- 9 nmol/cm(2) intimal surface area; P < 0.001), and aortic root plaque area (205,296 +/- 22,098 versus 143,662 +/- 13,302 micro m(2); P < 0.05) as compared with no-surgery mice; UNX mice showed intermediate values. The plaques from uremic mice contained CD11b-positive macrophages and showed strong staining for nitrotyrosine. Systolic BP and plasma homocysteine concentrations were similar in uremic and nonuremic mice. Plasma urea and cholesterol concentrations were elevated 2.6-fold (P < 0.001) and 1.5-fold (P < 0.001) in CRF compared with no-surgery mice. Both variables correlated with aortic plaque area fraction (r(2) = 0.5, P < 0.001 and r(2) = 0.3, P < 0.001, respectively) and with each other (r(2) = 0.5, P < 0.001). On multiple linear regression analysis, only plasma urea was a significant predictor of aortic plaque area fraction. In conclusion, the present findings suggest that uremia markedly accelerates atherogenesis in apolipoprotein E-deficient mice. This effect could not be fully explained by changes in BP, plasma homocysteine levels, or total plasma cholesterol concentrations. Thus, the CRF apolipoprotein E-deficient mouse is a new model for studying the pathogenesis of accelerated atherosclerosis in uremia.