Differential Impact In Vivo of Pf4-ΔCre-Mediated and Gp1ba-ΔCre-Mediated Depletion of Cyclooxygenase-1 in Platelets in Mice.

BACKGROUND: Low-dose aspirin is widely used for the secondary prevention of cardiovascular disease. The beneficial effects of low-dose aspirin are attributable to its inhibition of platelet Cox (cyclooxygenase)-1-derived thromboxane A2. Until recently, the use of the Pf4 (platelet factor 4) Cre has been the only genetic approach to generating megakaryocyte/platelet ablation of Cox-1 in mice. However, Pf4-ΔCre displays ectopic expression outside the megakaryocyte/platelet lineage, especially during inflammation. The use of the Gp1ba (glycoprotein 1bα) Cre promises a more specific, targeted approach. METHODS: To evaluate the role of Cox-1 in platelets, we crossed Pf4-ΔCre or Gp1ba-ΔCre mice with Cox-1flox/flox mice to generate platelet Cox-1-/- mice on normolipidemic and hyperlipidemic (Ldlr-/-; low-density lipoprotein receptor) backgrounds. RESULTS: Ex vivo platelet aggregation induced by arachidonic acid or adenosine diphosphate in platelet-rich plasma was inhibited to a similar extent in Pf4-ΔCre Cox-1-/-/Ldlr-/- and Gp1ba-ΔCre Cox-1-/-/Ldlr-/- mice. In a mouse model of tail injury, Pf4-ΔCre-mediated and Gp1ba-ΔCre-mediated deletions of Cox-1 were similarly efficient in suppressing platelet prostanoid biosynthesis. Experimental thrombogenesis and attendant blood loss were similar in both models. However, the impact on atherogenesis was divergent, being accelerated in the Pf4-ΔCre mice while restrained in the Gp1ba-ΔCres. In the former, accelerated atherogenesis was associated with greater suppression of PGI2 biosynthesis, a reduction in the lipopolysaccharide-evoked capacity to produce PGE2 (prostaglandin E) and PGD2 (prostanglandin D), activation of the inflammasome, elevated plasma levels of IL-1ß (interleukin), reduced plasma levels of HDL-C (high-density lipoprotein receptor-cholesterol), and a reduction in the capacity for reverse cholesterol transport. By contrast, in the latter, plasma HDL-C and α-tocopherol were elevated, and MIP-1α (macrophage inflammatory protein-1α) and MCP-1 (monocyte chemoattractant protein 1) were reduced. CONCLUSIONS: Both approaches to Cox-1 deletion similarly restrain thrombogenesis, but a differential impact on Cox-1-dependent prostanoid formation by the vasculature may contribute to an inflammatory phenotype and accelerated atherogenesis in Pf4-ΔCre mice.

Discovery of analogues of non-ß oxidizable long-chain dicarboxylic fatty acids as dual inhibitors of fatty acids and cholesterol synthesis: Efficacy of lead compound in hyperlipidemic hamsters reveals novel mechanism.

BACKGROUND AND AIMS: Cholesterol and triglycerides are risk factors for developing cardiovascular disease. Therefore, appropriate cells and assays are required to discover and develop dual cholesterol and fatty acid inhibitors. A predictive hyperlipidemic animal model is needed to evaluate mechanism of action of lead molecule for therapeutic indications. METHODS AND RESULTS: Primary hepatocytes from rat, hamster, rabbit, and humans were compared for suitability to screen compounds by de novo lipogenesis (DNL) using14C-acetate. Hyperlipidemic hamsters were used to evaluate efficacy and mode of action. In rat hepatocytes DNL assay, both the central moiety and carbon chain length influenced the potency of lipogenesis inhibition. In hyperlipidemic hamsters, ETC-1002 decreased plasma cholesterol and triglycerides by 41% and 49% at the 30 mg/kg dose. Concomitant decreases in non-esterified fatty acids (-34%) and increases in ketone bodies (20%) were associated with induction of hepatic CPT1-α. Reductions in proatherogenic VLDL-C and LDL-C (-71% and -64%) occurred partly through down-regulation of DGAT2 and up-regulation of LPL and PDK4. Activation of PLIN1 and PDK4 dampened adipogenesis and showed inverse correlation with adipose mass. Hepatic concentrations of cholesteryl ester and TG decreased by 67% and 64%, respectively. Body weight decreased with concomitant decreases in epididymal fat. Plasma and liver concentrations of ETC-1002 agreed with the observed dose-response efficacy. CONCLUSIONS: Taken together, ETC-1002 reduced proatherogenic lipoproteins, hepatic lipids and adipose tissues in hyperlipidemic hamsters via induction of LPL, CPT1-α, PDK4, and PLIN1, and downregulation of DGAT2. These characteristics may be useful in the treatment of fatty livers that causes non-alcoholic steatohepatitis.

Bis(µ-Tartrato)Di(µ-Hydroxy) Germanate (IV) Triethanolammonium as a Mononuclear Alkaline Phospholipase A2 Inhibitor.

It was established that the administration of an aqueous solution of bis(µ-tartrato)di(µ-hydroxy) germanate (IV) triethanolammonium to animals daily for 2 months at a dose of the active substance of 10 mg/kg of the animal's weight leads to inhibition of the total activity of the alkaline phospholipase A2 of mononuclear cells. The results of the study can be used to correct lipid metabolism in the development of disorders in hyperlipidemia. This makes it possible to expand the scope of use of the studied substance and create new pharmaceuticals based on bis(µ-tartrato)di(µ-hydroxy) germanate (IV) triethanolammonium prevent and inhibit the development of hyperlipidemia.

New Insight Into Metformin-Induced Cholesterol-Lowering Effect Crosstalk Between Glucose and Cholesterol Homeostasis via ChREBP (Carbohydrate-Responsive Element-Binding Protein)-Mediated PCSK9 (Proprotein Convertase Subtilisin/Kexin Type 9) Regulation.

[Figure: see text].

Kanglexin, a new anthraquinone compound, attenuates lipid accumulation by activating the AMPK/SREBP-2/PCSK9/LDLR signalling pathway.

Hyperlipidaemia is one of the major risk factors for atherosclerosis, coronary heart disease, stroke and diabetes. In the present study, we synthesized a new anthraquinone compound, 1,8-dihydroxy-3-succinic acid monoethyl ester-6-methylanthraquinone, and named it Kanglexin (KLX). The aim of this study was to evaluate whether KLX has a lipid-lowering effect and to explore the potential molecular mechanism. In this study, Sprague-Dawley rats were fed a high fat diet (HFD) for 5 weeks to establish a hyperlipidaemia model; then, the rats were orally administered KLX (20, 40, and 80 mg kg-1·d-1) or atorvastatin calcium (AT, 10 mg kg-1·d-1) once a day for 2 weeks. KLX had prominent effects on reducing blood lipids, hepatic lipid accumulation, body weight and the ratio of liver weight/body weight. Furthermore, KLXdramatically reduced the total cholesterol (TC) and triglyceride (TG) levels and lipid accumulation in a HepG2 cell model of dyslipidaemia induced by 1 mmol/L oleic acid (OA). KLX may decrease lipid levels by phosphorylating adenosine monophosphate-activated protein kinase (AMPK) and the downstream sterol regulatory element binding protein 2 (SREBP-2)/proprotein convertase subtilisin/kexin type 9 (PCSK9)/low-density lipoprotein receptor (LDLR) signalling pathway in the HFD rats and OA-treated HepG2 cells. The effects of KLX on the AMPK/SREBP-2/PCSK9/LDLR signalling pathway were abolished when AMPK was inhibited by compound C (a specific AMPK inhibitor) in HepG2 cells. In summary, KLX has an efficient lipid-lowering effect mediated by activation of the AMPK/SREBP-2/PCSK9/LDLR signalling pathway. Our findings may provide new insight into and evidence for the discovery of a new lipid-lowering drug for the prevention and treatment of hyperlipidaemia, fatty liver, and cardiovascular disease in the clinic.

Circulating Rather Than Intestinal PCSK9 (Proprotein Convertase Subtilisin Kexin Type 9) Regulates Postprandial Lipemia in Mice.

OBJECTIVE: Increased postprandial lipemia (PPL) is an independent risk factor for atherosclerotic cardiovascular diseases. PCSK9 (Proprotein convertase subtilisin kexin type 9) is an endogenous inhibitor of the LDLR (low-density lipoprotein receptor) pathway. We previously showed that PCSK9 inhibition in mice reduces PPL. However, the relative contribution of intracellular intestinal PCSK9 or liver-derived circulating PCSK9 to this effect is still unclear. Approach and Results: To address this issue, we generated the first intestine-specific Pcsk9-deficient (i-Pcsk9-/-) mouse model. PPL was measured in i-Pcsk9-/- as well as in wild-type and streptozotocin-induced diabetic mice following treatment with a PCSK9 monoclonal antibody (alirocumab). Blocking the circulating form of PCSK9 with alirocumab significantly reduced PPL, while overexpressing human PCSK9 in the liver of full Pcsk9-/- mice had the opposite effect. Alirocumab regulated PPL in a LDLR-dependent manner as this effect was abolished in Ldlr-/- mice. In contrast, i-Pcsk9-/- mice did not exhibit alterations in plasma lipid parameters nor in PPL. Finally, PPL was highly exacerbated by streptozotocin-induced diabetes mellitus in Pcsk9+/+ but not in Pcsk9-/- mice, an effect that was mimicked by the use of alirocumab in streptozotocin-treated Pcsk9+/+ mice. CONCLUSIONS: Taken together, our data demonstrate that PPL is significantly altered by full but not intestinal PCSK9 deficiency. Treatment with a PCSK9 monoclonal antibody mimics the effect of PCSK9 deficiency on PPL suggesting that circulating PCSK9 rather than intestinal PCSK9 is a critical regulator of PPL. These data validate the clinical relevance of PCSK9 inhibitors to reduce PPL, especially in patients with type 2 diabetes mellitus.

Ginsenoside Rb1 Alleviates Oxidative Low-Density Lipoprotein-Induced Vascular Endothelium Senescence via the SIRT1/Beclin-1/Autophagy Axis.

Oxidative low-density lipoprotein (ox-LDL) induces endothelium senescence and promotes atherosclerosis. Ginsenoside Rb1 (gRb1) has been proved to protect human umbilical vein cells (HUVECs), but its effect on ox-LDL-induced endothelium senescence and the underlying mechanism remains unknown. This study is to explore the involvement of the SIRT1/Beclin-1/autophagy axis in the effect of gRb1 on protecting endothelium against ox-LDL-induced senescence. Hyperlipidemia of Sprague Dawley rats was induced by high-fat diet, and gRb1 was intraperitoneal injected. A senescence model of HUVECs induced by ox-LDL was also established. The results showed that gRb1 alleviated hyperlipidemia-induced endothelium senescence and ox-LDL-induced HUVECs senescence. GRb1 also restored the reductions in SIRT1 and autophagy, which were involved in the anti-senescence effects. Beclin-1 acetylation was reduced, and the correlation between SIRT1 and Beclin-1 was increased by gRb1. Results of our study demonstrated the anti-senescence function of gRb1 against hyperlipidemia in the endothelium, and the underlying mechanism involves the SIRT1/Beclin-1/autophagy axis.

Partial analytical validation of the VetScan cPL rapid test.

BACKGROUND: Serum canine pancreatic lipase immunoreactivity (cPLI) concentrations have become the standard laboratory test used to diagnose canine pancreatitis. Recently, a new point-of-care assay for cPLI, the VetScan cPL rapid test (VetScan cPL), has become available, but analytical validation data have not yet been published. OBJECTIVE: This study aimed to perform a partial analytical validation of the VetScan cPL. METHODS: Leftover serum samples from a diagnostic laboratory were used. Adherence to the manufacturer's guidelines, linearity, repeatability, and reproducibility were evaluated. Results of the VetScan cPL were correlated with the Spec cPL results. RESULTS: Observed-to-expected ratios for dilutional parallelism ranged from 77.4% to 162.9% (mean 119.3%). Intra-assay and inter-assay variabilities ranged from 16.9% to 36.7% (mean 25.1%) and from 14.1% to 51.2% (mean 31.8%), respectively. Adherence to the manufacturer's specification regarding results within ± 60 µg/L of the Spec cPL result was only achieved for 39% of the measurements. The VetScan cPL and Spec cPL correlation showed a Spearman's r of .758 for 29 data pairs. CONCLUSIONS: Under the conditions of this study, the VetScan cPL did not adhere to the manufacturer's specifications for most measurements. Also, the VetScan cPL showed suboptimal linearity and was not precise. In conclusion, the VetScan cPL failed basic analytical validation.

1,25(OH)2D3 improves blood lipid metabolism, liver function, and atherosclerosis by constraining the TGF-ß/Smad signaling pathway in rats with hyperlipidemia.

1,25(OH)2D3 has already been reported to function in some diseases. However, its role in hyperlipidemia (HLP) remains unknown. This study aims to investigate the effect of 1,25(OH)2D3 on HLP rats. Rat models were established by high-fat diet feeding, perfusion of different doses of 1,25-(OH)2D3 and injection of TGF-ß1 siRNA. Whole blood viscosity, plasma viscosity, hematocrit, and erythrocyte aggregation index were detected, together with levels of biochemical indexes, 6-keto-PGF1α, and TXB2 in serum. Levels of oxidative stress indexes and inflammatory factors in serum and liver tissues were determined. TGF-ß1 and Smad3 expression in serum, liver tissues, and aorta was detected. 1,25(OH)2D3 lowered HLP-induced rise of whole blood viscosity, red blood cell aggregation index, plasma viscosity, and hematocrit, TC, TG, LDL-C, apoB, ALT, AST, TXB2, MDA, IL-1ß, TNF-α, and increased HLP-induced decrease of HDL-C, apoAI, 6-keto-PGF1α, SOD, GSH-Px, CAT, and T-AOC. TGF-ß1 and Smad3 expression in serum, liver tissue, and aorta of 1,25(OH)2D3-treated rats reduced. High 1,25(OH)2D3 dose and inhibited TGF-ß/Smad signaling pathway alleviated lipid metabolism, liver function, and atherosclerotic injury in HLP rats. Our study found that 1,25(OH)2D3 improves blood lipid metabolism, liver function, and atherosclerosis injury by constraining the TGF-ß/Smad signaling pathway in rats with HLP.

Vascular peroxide 1 promotes ox-LDL-induced programmed necrosis in endothelial cells through a mechanism involving ß-catenin signaling.

BACKGROUND AND AIMS: Vascular peroxidase 1 (VPO1) plays a key role in mediation of cardiovascular oxidative injury. This study aims to determine whether VPO1 can promote programmed necrosis of endothelial cells and the underlying mechanisms. METHODS AND RESULTS: Human umbilical vein endothelial cells (HUVECs) were incubated with oxidized low-density lipoprotein (ox-LDL, 100 µg/mL) for 48 h to induce cell injury, which showed an elevation in cell necrosis (reflected by the increased propidium iodide (PI) positive-staining cells, LDH release and decreased cell viability), concomitant with an increase in programmed necrosis-relevant proteins including receptor-interacting protein kinase 1/3 (RIPK1/3), p-RIPK3 and mixed lineage kinase domain like (MLKL); these phenomena were attenuated by necrostatin-1(Nec-1) and RIPK3 siRNA. Meanwhile, VPO1 was up-regulated in ox-LDL-treated endothelial cells accompanied by a decrease in GSK-3ß activity and p-ß-catenin levels, and an elevation of ß-catenin levels; these phenomena were reversed in the presence of VPO1 siRNA or hypochlorous acid (HOCl) inhibitor; replacement of ox-LDL with HOCl could also induce endothelial programmed necrosis and activate the ß-catenin signaling; ß-catenin inhibitor could also suppress ox-LDL-induced RIPK-dependent necrosis. In hyperlipidemic patients, the plasma level of VPO1 was obviously increased concomitant with an elevation in plasma levels of RIPK1, RIPK3 and MLKL, and they were positively correlated. CONCLUSIONS: VPO1 plays an important role in promotion of endothelial programmed necrosis under hyperlipidemic conditions through activation of ß-catenin signaling. It may serve as a novel therapeutic target for prevention of endothelial dysfunction in hyperlipidemia.

Antioxidant activity of purified ulvan in hyperlipidemic mice.

Several studies have reported that ulvan from the alga Ulva pertusa (Chlorophyta) exhibits substantial antioxidant and antihyperlipidemic activities; however, which group of heteropolysaccharides play roles in these activities remains unknown. In this study, three purified ulvan (PU1, PU2 and PU3) have been obtained by DEAE-Sepharose fast-flow column. The antioxidant activity was detected via the model of hyperlipidemic Kunming mice, including malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) in liver. PU3, which possessed the highest uronic acid content (24.09%) and sulfate content (23.99%) as well as the lowest average molecular weight (83,094 Da), exhibited the stronger antioxidant activity than other examples. It significantly decreased MDA (29.2%; P < 0.05), increased SOD (36.4%; P < 0.05) and CAT (43.6%; P < 0.05) compared with hyperlipidemia group. In conclusion, PU3 may be potential sources of natural antioxidant to protecting against the liver damage of oxidative stress induced by cholesterol-rich diet.

Pomegranate leaf attenuates lipid absorption in the small intestine in hyperlipidemic mice by inhibiting lipase activity.

Pomegranate leaf (PGL) has a definite role in regulating lipid metabolism. However, pharmacokinetic results show the main active ingredient, ellagic acid, in PGL has lower oral bioavailability, suggesting that the lipid-lowering effect of PGL may act through inhibiting lipid absorption in the small intestine. Our results demonstrated that pomegranate leaf and its main active ingredients (i.e., ellagic acid, gallic acid, pyrogallic acid and tannic acid) were capable of inhibiting pancreatic lipase activity in vitro. In computational molecular docking, the four ingredients had good affinity for pancreatic lipase. Acute lipid overload experiments showed that a large dosage of PGL significantly reduced serum total cholesterol (TG) and triglycerides (TC) levels in addition to inhibiting intestinal lipase activity, which demonstrated that PGL could inhibit lipase activity and reduce the absorption of lipids. We also found that PGL could reverse the reduced tight-junction protein expression due to intestinal lipid overload, promote Occludin and Claudin4 expression in the small intestine, and enhance the intestinal mucosal barrier. In conclusion, we demonstrated that PGL can inhibit lipid absorption and reduce blood TG and TC by targeting pancreatic lipase, promoting tight-junction protein expression and thereby preventing intestinal mucosa damage from an overload of lipids in the intestine.

Development of Wheat Bran Oil Concentrates Rich in Bioactives with Antioxidant and Hypolipidemic Properties.

Wheat bran, an abundant byproduct of the milling industry, comprises fat-soluble bioactives and fibers. In the present study, two concentrates were prepared from wheat bran oil (WBO) using silicic acid coupled with acetone (WBA) and hexane (WBH). WBA extract had enhanced color and viscosity and was enriched with fat-soluble bioactives (sterols, oryzanol-like compounds, tocopherols, and carotenoids) as evidenced from NMR and other techniques. In in vitro studies, WBA exhibited significant free radical scavenging activity, limited DNA and LDL oxidation, and inhibiting HMG-CoA reductase and lipase activity better than WBH and WBO. Further, an in vivo study with WBA 2 or 3.5% containing high fat diet ameliorated malonaldehyde (MDA) level, lipid profile, and antioxidant enzyme (SOD, catalase, GPx, and GR) activities in liver. A possible reason for this effect is downregulation of HMG-CoA reductase expression with WBA. Thus, WBA has significant potential as an ingredient in health food formulations.

[Effect of Electroacupuncture on Cerebro-cortex Caspase-3 Expression and Blood Lipid Levels in Hyperlipemia Rats with Cerebral Ischemia].

OBJECTIVE: To observe the effect of electroacupuncture (EA) stimulation of "Fenglong" (ST 40), "Sanyinjiao" (SP 6) plus manual acupuncture (MA) stimulation of "Shuigou" (GV 26) and "Baihui" (GV 20) on Caspase-3 protein expression in the cerebral cortex of rats with hyperlipemia and cerebral ischemia(HL-CI),so as to reveal its mechanisms underlying improvement of HL-CI. METHODS: Forty-five rats were randomly divided into normal control,sham operation,model,EA group I(EA+MA was given for 14 days, i.e., 7 days before CI, and 7 days more after HL-CI)and EA group Ⅱ (EA+MA was given for only 7 days after HL-CI),with 9 rats being in each group. The HL-CI model was established by feeding the animals with high fat forage for 6 weeks and then making an occlusion of the unilateral middle cerebral artery by regional application of quantitative paper adsorbing 50% FeCl3 solution (10 µL). Rats of the sham operation group were treated with the same procedures only without application of FeCl3 solution. For rats of the EA group I,EA (1-3 mA, 2 Hz/100 Hz) was applied to bilateral acupoints SP 6 and ST 40 (for 20 min),and MA stimulation applied to GV 26 and GV 20. EA was conducted once daily for 7 days after 6 weeks' high fat fo-rage feeding, and EA+MA intervention was conducted once daily for 7 days after CI modeling. For rats in the EA group Ⅱ, EA+MA was applied to the same 4 acupoints once a day for 7 days only after CI modeling. The neurological impairment was assessed by Zea Longa's scoring. The blood sample was taken from the abdominal aorta for measuring the contents of serum cholesterol (CHO),triglyceride (TG) and high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C). Pathological changes of the cerebral cortex were observed after H.E. staining, and the expression of cerebro-cortex Caspase-3 was analyzed by immunohistochemistry. RESULTS: Following modeling,the neurological score,CHO, TG and LDL-C contents, and the number of Caspase-3 positive cells as well as Caspase-3 immunoactivity level were significantly increased in the model group(P<0.05), while serum HDL-C level was obviously decreased(P<0.05). After the treatment,the increased neurological score, CHO, TG and LDL-C contents, and the number of Caspase-3 positive cells and Caspase-3 immunoactivity level were considerably decreased in the EA group I and Ⅱ(P<0.05)while the decreased HDL-C level was notably increased relevant to the model group(P<0.05). The effects of the EA group I were notably superior to those of EA group Ⅱ in down-regulating the neurological score,CHO, TG and LDL-C levels and the expression of Caspase-3 protein(P<0.05). No significant differences were found between the normal control and sham operation groups in the neurological scores 20 min and 7 days after modeling and Caspase-3 expression levels (P>0.05). H.E. staining showed a reduction of the apoptotic cells and inflammatory cells in both EA group I and Ⅱ. CONCLUSIONS: Both EA and EA+MA interventions can improve neurological function in HL-CI rats,which may be related to their effects in adjusting the levels of serum lipids and down-regulating the expression of cell apoptosis-related Caspase-3 protein in the ischemic cortex. Moreover, the cerebral ischemia injury may be lightened by EA-lowering hyperlipemia first.

Attenuated Superoxide Dismutase 2 Activity Induces Atherosclerotic Plaque Instability During Aging in Hyperlipidemic Mice.

BACKGROUND: Atherosclerosis progression during aging culminates in the development of vulnerable plaques, which may increase the risk of cardiovascular events. Increased generation and/or decreased scavenging of reactive oxygen species in the vascular wall are major contributors to atherogenesis. We previously showed that superoxide dismutase 2 deficiency increased vascular oxidative stress and reduced aortic compliance in aged wild-type mice and that young Apoe-/-/Sod2+/- had increased mitochondrial DNA damage and atherosclerosis versus young Apoe-/- mice. Here we investigated the effects of superoxide dismutase 2 deficiency on atherosclerosis progression and plaque morphology in middle-aged Apoe-/- mice. METHODS AND RESULTS: Compared with Apoe-/-, middle-aged Apoe-/-/Sod2+/- mice had increased vascular wall reactive oxygen species (P<0.05) and higher atherosclerotic lesion area (P<0.001). The atherosclerotic plaques in middle-aged Apoe-/-/Sod2+/- mice had an increased necrotic core with higher inflammatory cell infiltration, a thinned fibrous cap with depleted smooth muscle content, and intraplaque hemorrhage. In addition, the plaque shoulder area had higher levels of calpain-2, caspase-3, and matrix metalloproteinase-2 in intimal smooth muscle cells and depleted fibrous cap collagen. Targeting mitochondrial reactive oxygen species with MitoTEMPO attenuated features of atherosclerotic plaque vulnerability in middle-aged Apoe-/-/Sod2+/- mice by lowering expression of calpain-2, caspase-3, and matrix metalloproteinase-2 and decreasing smooth muscle cell apoptosis and matrix degradation. CONCLUSIONS: Enhanced mitochondrial oxidative stress under hyperlipidemic conditions in aging induces plaque instability, in part by increasing smooth muscle cell apoptosis, necrotic core expansion, and matrix degradation. Targeting mitochondrial reactive oxygen species or its effectors may be a viable therapeutic strategy to prevent aging-associated and oxidative stress-related atherosclerosis complications.

Role of CaMKII in free fatty acid/hyperlipidemia-induced cardiac remodeling both in vitro and in vivo.

RATIONALE: The cellular mechanisms of obesity/hyperlipidemia-induced cardiac remodeling are many and not completely elucidated. Ca2+/calmodulin-dependent protein kinase II (CaMKII), a multifunctional serine/threonine kinase, has been reported to be involved in a variety of cardiovascular diseases. However, its role in obesity/hyperlipidemia-induced cardiac remodeling is still unknown. OBJECTIVE: The objective of this study was to demonstrate the role of CaMKII in the pathogenesis of obesity/hyperlipidemia-induced cardiac remodeling both in vitro and in vivo. METHODS AND RESULTS: In cardiac-derived H9C2 cells, palmitate treatment induced cell apoptosis coupled with activation of the mitochondrial apoptotic pathway, and cell hypertrophic and fibrotic responses. All of these alterations were inhibited by pharmacological inhibition of CaMKII with either of two specific inhibitors, Myr-AIP and KN93. In addition, an increased inflammatory response coupled with activation of the MAPKs and NF-κB signaling pathway, exaggerated oxidative stress, ER stress and autophagy were also observed in palmitate-treated H9C2 cells, while pretreatment with CaMKII inhibitors decreased these pathological signals. Furthermore, we also demonstrated that TLR4 is upstream signal of CaMKII in palmitate-treated H9C2 cells. In APOE-/- mice fed a high-fat diet (HFD) for 16weeks, serum lipid profiles (FFAs, TG, TC) and blood glucose levels were significantly increased compared with mice fed a normal diet. In addition, apparent cardiac hypertrophy, fibrosis and apoptosis associated with increased inflammation, ER stress, and autophagy were also observed in the hearts of HFD-fed mice. However, all these changes were reversed by 8-weeks of KN93 peritoneal injections. KN93 also increased antioxidant defense as evidenced by increased expression of the Nrf2 system in the hearts of HFD-fed mice. CONCLUSIONS: Taken together, our results demonstrate a critical role of CaMKII in the pathogenesis of obesity/hyperlipidemia-induced cardiac remodeling. Also, TLR4 may be an upstream signal of cardiac CaMKII under hyperlipidemia conditions. These results suggest that CaMKII has the potential to be a therapeutic target in the prevention of obesity/hyperlipidemia-induced cardiac remodeling.

Specificity of, and influence of hemolysis, lipemia, and icterus on serum lipase activity as measured by the v-LIP-P slide.

BACKGROUND: Measurement of pancreatic lipase in serum is being used for the diagnosis of pancreatitis. OBJECTIVES: The aims of this study were to measure serum lipase activity by the v-LIP-P slide and serum canine pancreatic lipase immunoreactivity (cPLI) concentration by Spec cPL in dogs with exocrine pancreatic insufficiency (EPI) and in serum samples that were hemolyzed, lipemic, or icteric. METHODS: Serum samples from 50 dogs with EPI, 8 samples spiked with canine hemoglobin, Intralipid, or ditaurobilirubin, and 8 samples from dogs with severe hypertriglyceridemia were evaluated using v-LIP-P and Spec cPL assays. RESULTS: Serum lipase activity (v-LIP-P) was in the lower 20% of the RI in 58% of EPI dogs, while serum cPLI (as measured by Spec cPL) was in the lower 20% of the RI in 98% of EPI dogs. The mean (±SD) observed-to-expected ratios for serum samples spiked with canine hemoglobin, Intralipid, or ditaurobilirubin were 63.0 ± 25.1%, 489.2 ± 469.7%, and 80.2 ± 11.6% for the v-LIP-P slide, respectively, and 99.3 ± 6.8%, 96.9 ± 9.4%, and 98.7 ± 11.0% for Spec cPL, respectively. However, naturally occurring hypertriglyceridemia did not appear to have a significant effect on serum lipase activity as measured by the v-LIP-P slide. CONCLUSIONS: These results show that Spec cPL is specific for pancreatic lipase, while the v-LIP-P slide is not. In addition, hemolysis and lipemia had no effect on Spec cPL, while severe icterus resulted in a slight decrease in Spec cPL. Hemolysis and icterus had a significant effect on the v-LIP-P slide. The effect of lipemia on the v-LIP-P slide cannot be conclusively established based on this study.

Paraoxonase-1 and myeloperoxidase correlate with vascular biomarkers in overweight patients with newly diagnosed untreated hyperlipidaemia.

BACKGROUND: In hyperlipidaemic state, increased levels of myeloperoxidase (MPO) and decreased paraoxonase-1 (PON1) activity have been reported; however, their relationships with other atherosclerotic biomarkers have not been completely clarified. PATIENTS AND METHODS: Serum concentrations of lipid and inflammatory parameters, MPO levels, and PON1 activities were investigated in 167 untreated hyperlipidaemic patients with and without vascular complications and in 32 healthy controls. Additionally, levels of CD40 ligand (sCD40L) and asymmetric dimethyl arginine (ADMA), soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion molecule-1, and oxidized LDL were determined. RESULTS: We found elevated C-reactive protein (CRP), ADMA, sCD40L, sICAM-1 concentrations, and higher MPO levels in patients with vascular complications compared to those without. The PON1 arylesterase activity correlated negatively with sCD40L, ADMA, and sICAM-1 levels, respectively. In contrast, MPO concentrations showed positive correlations with sCD40L, ADMA, and sICAM-1 levels, respectively. CONCLUSIONS: It can therefore be stated that PON1 activity and MPO level correlate strongly with the vascular biomarkers, highlighting the importance of the HDL-associated pro- and antioxidant enzymes in the development of endothelial dysfunction and atherogenesis.

CaMKII Activation Promotes Cardiac Electrical Remodeling and Increases the Susceptibility to Arrhythmia Induction in High-fat Diet-Fed Mice With Hyperlipidemia Conditions.

BACKGROUND: Obesity/hyperlipidemia is closely related to both atrial and ventricular arrhythmias. CaMKII, a multifunctional serine/threonine kinase, has been involved in cardiac arrhythmias of different etiologies. However, its role in obesity/hyperlipidemia-related cardiac arrhythmia is unexplored. The aim of this was to determine the involvement of CaMKII in the process. METHODS: Adult male APOE mice were fed a high-fat diet (HFD), administrated with KN93 (10 mg·kg·2d), a specific inhibitor of CaMKII. Serum lipid and glucose profile, cardiac function, and surface electrocardiogram were determined. Electrophysiological study and epicardial activation mapping were performed in Langendorff-perfused heart. Expression of cardiac ion channels, gap junction proteins, Ca handling proteins, and CaMKII were evaluated, coupled with histological analysis. RESULTS: A hyperlipidemia condition was induced by HFD in the APOE mice, which was associated with increased expression and activity of CaMKII in the hearts. In Langendorff-perfused hearts, HFD-induced heart showed increased arrhythmia inducibility, prolonged action potential duration, and decreased action potential duration alternans thresholds, coupled with slow ventricular conduction, connexin-43 upregulation, and interstitial fibrosis. Downregulation of ion channels including Cav1.2 and Kv4.2/Kv4.3 and disturbed Ca handling proteins were also observed in HFD-induced heart. Interestingly, all these alterations were significantly inhibited by KN93 treatment. CONCLUSION: Our results demonstrated an adverse effect of metabolic components on cardiac electrophysiology and implicated an important role of CaMKII underlying this process.

Use of a Fluorescent Substrate to Measure ACE2 Activity in the Mouse Abdominal Aorta.

The use of fluorogenic substrates to measure enzymatic activity is widely used to understand function within different experimental models. ACE2 is important in understanding the balance between AngII and Ang-(1-7) and how this balance could then in turn influence hypertension or other disease outcomes. Here, we describe a method to measure ACE2 activity in abdominal aorta of hyperlipidemic mice under both saline and AngII infusion.