A novel non-genetic murine model of hyperglycemia and hyperlipidemia-associated accelerated atherosclerosis

Objective: Atherosclerosis, the main pathology underlying cardiovascular diseases is accelerated in diabetic patients. Genetic mouse models require breeding efforts which are time-consuming and costly. To establish a new non-genetic model of inducible metabolic risk factors mimicking hyperlipidemia, hyperglycemia, or both and allowing to detect phenotypic differences dependent on the metabolic stressor(s). Methods and Results: Wild type mice were injected with gain-of-function PCSK9D377Y (proprotein convertase subtilisin/kexin type 9) mutant adeno-associated viral particles (AAV) and streptozotocin and fed either a high-fat diet (HFD) or high-cholesterol/high fat-diet (Paigen diet, PD). Combined hyperlipidemic and hyperglycemic (HGHCi) mice, but not hyperlipidemia (HCi) alone, display characteristic features of accelerated atherosclerosis. Atherosclerotic plaques of HGHCi animals were larger, showed a less stable phenotype, contained more macrophages and less smooth muscle cells. These findings were observed both at early (12 weeks) and late (20 weeks) time points on both HFD or PD diet. Differences between the HGHCi and HCi model were confirmed using RNAseq analysis revealing that significantly more genes are dysregulated in mice with combined hyperlipidemia and hyperglycemia as compared to the hyperlipidemia only group. The HGHCi-associated genes were related to pathways regulating inflammation, cellular metabolism and collagen degradation. PD accelerates atherosclerosis in mice and shows plaque formation already after 8 weeks, therefore, representing a fast direct inducible hyperglycemic atherosclerosis model. Conclusion: We established a non-genetic inducible mouse model allowing comparative analyses of atherosclerosis in HCi and HGHCi conditions and its modification by diet, allowing analyses of multiple metabolic hits in mice.

Establishment of Type 2 Diabetes Mellitus Models Using High-Fat Diet and STZ in Bama Minipigs

BackgroundIn the past 20 years, the number of adults with diabetes has tripled. For most of the researches are often conducted in rodent T2DM models, and effective drugs developed have low clinical conversion efficiency. Therefore, it is urgent to establish a large animal model to explore the pathogenesis of T2DM and formulate disease prevention and control strategies. MethodsThis study was designed to establish and validate a T2DM model in minipigs with notable hyperglycemia using a high-fat diet and low-dose streptozotocin (STZ)，and examined the influence of STZ infusion time, the difference between a high-fat diet and a high-cholesterol and high-fat diet, and the atherosclerotic lesions accelerated by diabetes. Male Bama minipigs (n=24) were randomly divided into 5 groups; the control group was fed with normal diet for 9 months; STZ+HFD group and STZ+HCFD group were infused with 90 mg/kg STZ and then fed with a high-fat diet or high-cholesterol and high-fat diet for 9 months, respectively; HFD + STZ group and HCFD + STZ group were fed with a high-fat diet or high-cholesterol and high-fat diet, respectively, for nine months (after 3 months, pigs were injected with 90 mg/kg STZ intravenously). ResultsThe results showed the serum glucose concentrations were within the normal range in all groups except for HFD + STZ group and HCFD + STZ group. Animals fed with a high-fat diet for 9 months, did not develop apparent atherosclerotic lesions; nevertheless, atherosclerotic lesions were seen in animals fed with high-cholesterol and high-fat diets. Moreover, hyperglycemia accelerated atherosclerosis (lesions on the intimal surface of the abdominal aorta, 0.44±0.29 vs. 0.28±0.26) in minipigs. ConclusionsHigh-fat/high-cholesterol and high-fat diet combined with low-dose streptozotocin successfully established T2DM in minipigs. High-fat diet could not induce apparent atherosclerosis lesions but high-cholesterol and high-fat diet could during the nine months period. Hyperglycemia accelerated atherosclerosis in the minipigs.

α1-nAchR-Mediated Signaling Through Lipid Raft Is Required for Nicotine-Induced NLRP3 Inflammasome Activation and Nicotine-Accelerated Atherosclerosis

BackgroundNicotine exerts direct effects on multiple cell types in the cardiovascular system by associating with its high-affinity nicotinic acetylcholine receptors (nAchRs). Lipid raft is a membrane microdomain that recruits various receptors and signaling molecules for coordinating cellular immune response and many others signaling processes. Here, we aim to identify the essential role of lipid raft in mediating nicotine-triggered inflammatory and nicotine-accelerated atherosclerosis, and to figure out the specific receptor of nicotine-induced Nod-like receptor protein 3 (NLRP3) inflammasome activation in macrophage.Methods and ResultsApoE–/– mice were fed with a high-fat diet to build atherosclerosis model. Methyl-β-cyclodextrin was used to interrupt intact lipid raft. We confirmed that nicotine triggered NLRP3 inflammasome activation and induced macrophage migration into atherosclerotic plaque, thus accelerated atherosclerosis in apoE–/– mice fed with a high-fat diet. Mechanically, nicotine increased the expression of α1-nAChR and stimulated the accumulation of α1-nAChR in lipid raft, leading to NLRP3 inflammasome activation in macrophage. Conversely, silencing of α1-nAChR in macrophage sufficiently blocked the pro-inflammasome activation effect of nicotine, indicating that α1-nAChR was the specific receptor for nicotine in triggering NLRP3 inflammasome in macrophage. Furthermore, both the destruction of lipid raft by methyl-β-cyclodextrin and the interference of lipid raft clustering by silencing acid sphingomyelinase reversed nicotine-induced NLRP3 inflammasome activation by reducing the accumulation of α1-nAChR in lipid raft in macrophage, suggesting lipid raft–mediated accumulation of α1-nAChR was the key event in regulating the pro-inflammatory effects of nicotine in macrophage. Importantly, nicotine-induced NLRP3 inflammasome activation and macrophage migration into atherosclerotic plaque were reversed by methyl-β-cyclodextrin, making a significant improvement for atherosclerosis in apoE–/– mice fed with a high-fat diet.Conclusionα1-nAChR-mediated signaling through lipid raft is required for NLRP3 inflammasome activation and pro-atherosclerotic property of nicotine.

Metformin Suppresses the Progress of Diabetes-Accelerated Atherosclerosis by Inhibition of Vascular Smooth Muscle Cell Migration Through AMPK–Pdlim5 Pathway

Backgrounds: Our previous work revealed that AMP-activated protein kinase (AMPK) activation inhibits vascular smooth muscle cell migration in vitro by phosphorylating PDZ and LIM domain 5 (Pdlim5). As metformin is an AMPK activator, we used a mouse vascular smooth muscle cell (VSMC) line and a Myh11-cre-EGFP mice to investigate whether metformin could inhibit the migration of VSMCs in vitro and in a wire-injury model in vivo. It is recognized that VSMCs contribute to the major composition of atherosclerotic plaques. In order to investigate whether the AMPK–Pdlim5 pathway is involved in the protective function of metformin against atherosclerosis, we utilized ApoE−/− male mice to investigate whether metformin could suppress diabetes-accelerated atherosclerosis by inhibition of VSMC migration via the AMPK–Pdlim5 pathway.Methods: The mouse VSMC cell line was exogenously transfected wild type, phosphomimetic, or unphosphorylatable Pdlim5 mutant before metformin exposure. Myh11-cre-EGFP mice were treated with saline solution or metformin after these were subjected to wire injury in the carotid artery to study whether metformin could inhibit the migration of medial VSMCs into the neo-intima. In order to investigate whether the AMPK–Pdlim5 pathway is involved in the protective function of metformin against atherosclerosis, ApoE−/− male mice were divided randomly into control, streptozocin (STZ), and high-fat diet (HFD)-induced diabetes mellitus; STZ+HFD together with metformin or Pdlim5 mutant carried the adenovirus treatment groups.Results: It was found that metformin could induce the phosphorylation of Pdlim5 and inhibit cell migration as a result. The exogenous expression of phosphomimetic S177D-Pdlim5 inhibits lamellipodia formation and migration in VSMCs. It was also demonstrated that VSMCs contribute to the major composition of injury-induced neointimal lesions, while metformin could alleviate the occlusion of the carotid artery. The data of ApoE−/− mice showed that increased plasma lipids and aggravated vascular smooth muscle cell infiltration into the atherosclerotic lesion in diabetic mice were observed Metformin alleviated diabetes-induced metabolic disorders and atherosclerosis and also reduced VSMC infiltration in atherosclerotic plaques, while the Pdlim5 phospho-abolished mutant that carried adenovirus S177A-Pdlim5 undermines the protective function of metformin.Conclusions: The activation of the AMPK–Pdlim5 pathway by metformin could interrupt the migratory machine of VSMCs and inhibit cell migration in vitro and in vivo. The maintenance of AMPK activity by metformin is beneficial for suppressing diabetes-accelerated atherosclerosis.

S-nitrosylation-mediated coupling of G-protein alpha-2 with CXCR5 induces Hippo/YAP-dependent diabetes-accelerated atherosclerosis

Atherosclerosis-associated cardiovascular disease is one of the main causes of death and disability among patients with diabetes mellitus. However, little is known about the impact of S-nitrosylation in diabetes-accelerated atherosclerosis. Here, we show increased levels of S-nitrosylation of guanine nucleotide-binding protein G(i) subunit alpha-2 (SNO-GNAI2) at Cysteine 66 in coronary artery samples from diabetic patients with atherosclerosis, consistently with results from mice. Mechanistically, SNO-GNAI2 acted by coupling with CXCR5 to dephosphorylate the Hippo pathway kinase LATS1, thereby leading to nuclear translocation of YAP and promoting an inflammatory response in endothelial cells. Furthermore, Cys-mutant GNAI2 refractory to S-nitrosylation abrogated GNAI2-CXCR5 coupling, alleviated atherosclerosis in diabetic mice, restored Hippo activity, and reduced endothelial inflammation. In addition, we showed that melatonin treatment restored endothelial function and protected against diabetes-accelerated atherosclerosis by preventing GNAI2 S-nitrosylation. In conclusion, SNO-GNAI2 drives diabetes-accelerated atherosclerosis by coupling with CXCR5 and activating YAP-dependent endothelial inflammation, and reducing SNO-GNAI2 is an efficient strategy for alleviating diabetes-accelerated atherosclerosis.

The Effect of Metformin and Glimepiride on Platelet Count and Indices Among Diabetic Patients Attending Jaber Abu Aliz Diabetic Center in Khartoum State

BackgroundDiabetes mellitus (DM) is a global pandemic, Platelets have crucial role in accelerated atherosclerosis and thrombosis which characterize DM.AimThe aim of the study was to detect the effect of two major oral hypoglycemic drugs (Metformin and Glimepiride) on platelet count and indices MPV (Mean platelet volume), PLCR (platelet large cell ratio), PDW (platelet distribution width). Beside, to study the effects of variation in Age, sex, duration of the drug, dose of drug, HbA1C level and associated complications.Material and methods96 diabetic patients have been included in this study in addition 50 apparently healthy non-diabetic matching for age and sex subjects have been tested as control group.EDTA anti-coagulated venous blood samples has been taken from each , platelet count and indices were measured using automatic blood counter (Sysmex KX-21N) and HbA1C was Measured using Ichroma II . Statistics was performed by SPSS (version 22). ResultsThe results showed that both types of treatment have reduced platelets indices but the reduction in Glimepiride was insignificant except in PDW when compared with control. Also both have no effect on platelet count. Both treatments have insignificant variation on measured parameters when considering age, gender, dose and treatment duration though significant variation in Glimepiride study population was detected due to associated complications and HbA1C level.ConclusionIt is concluded that both types of drugs reduce platelet indices which have a good prognostic effect on the Pro-thrombotic state and accelerated atherosclerosis which is associated with type 2 Diabetic patients. Metformin have better effect on platelet indices than Glimepiride. Further case control trails are required.