Evaluation of myocardial insulin sensitivity in murin models of diabetic cardiopathy

Orientador: Andrei Carvalho SpositoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências MédicasResumo: Introdução: A resistência insulínica (RI) no miocárdio é um mecanismo central no remodelamento fenotípico cardíaco no diabetes. Embora modelos de cardiopatia diabética em ratos tenham sido utilizados para descrever distúrbios com impacto fisiopatogênico na doença cardiovascular, não há descrição do desenvolvimento de RI no tecido miocárdico e, portanto, de plausibilidade para interpretação dos efeitos cardíacos direto da RI. Assim, investigamos o desenvolvimento de RI miocárdica na dieta hiperlipídica (HFD), dieta rica em frutose (FRD) e no modelo poligênico Goto-Kakizaki. Métodos. Ratos machos da linhagem Wistar com 6 semanas de idade foram divididos nos seguintes grupos: controle, HFD e FRD e receberam dieta convencional, dieta rica em ácidos graxos (31,2%) e caseína (20%) e dieta rica em frutose (47%), respectivamente. Ratos machos da linhagem Goto-Kakizaki foram investigados com 8 semanas de idade. Teste de tolerância à glicose (TTG) e teste de tolerância à insulina (TTI) foram medidos. Em seguida dois minutos após a injeção de insulina ou solução salina para avaliar as condições basais, coração, fígado e tecido adiposo epididimal foram removidos e investigados para caracterização da RI miocárdica. Resultados. Os animais HFD e FRD mostraram ganho de peso significativo em comparação com os animais do grupo controle. Como esperado, os ratos GK apresentaram menor ganho de peso que os animais controle. GTT revelou resistência periférica à insulina em ratos HFD, FRD e GK em comparação com ratos controle. Em concordância com estes dados, a ITT mostra que os grupos FRD e GK exibiram comprometimento da sensibilidade à insulina. A análise de transferência de Western da sinalização de insulina demonstrou resistência à insulina cardíaca apenas em ratos GK. Especificamente, a fosforilação de Akt na Ser473 mostrou resistência à insulina hepática nos grupos FRD e GK. Os ratos HFD e FRD também demonstraram um aumento atenuado da fosforilação da proteína Akt estimulada por insulina no tecido adiposo branco. Conclusão. Em conclusão, apesar da tolerância à glicose sistêmica prejudicada, modelos baseados apenas em dieta exibiram sinalização de insulina cardíaca preservada. Em contraste, os ratos GK poligênicos demonstraram RI sistêmica e cardíacaAbstract: Introduction: Insulin resistance (IR) in the myocardium is a central mechanism in cardiac phenotypic remodeling in diabetes. Although models of diabetic heart disease in rats have been used to describe disorders with pathophysiological impact on cardiovascular disease, there is no description of the development of IR in myocardial tissue and hence plausibility for interpretation of the direct cardiac effects of IR. Thus, we investigated the development of myocardial RI in the hyperlipid diet (HFD), high fructose diet (FRD) and the polygenic model Goto-Kakizaki. Methods. Male Wistar rats were divided into the following groups: control, HFD and FRD and received a conventional diet, diet rich in fatty acids (31.2%) and casein (20%) and a high fructose diet (47 %), respectively. Male rats of the Goto-Kakizaki strain were investigated at 8 weeks of age. Glucose tolerance test (GTT) and insulin tolerance test (ITT) were measured. After 2 minutes after the injection of insulin or saline to evaluate basal conditions, heart, liver and epididymal adipose tissue were removed and investigated for characterization of myocardial IR. Results. The HFD and FRD animals showed significant weight gain compared to control animals. As expected, GK mice had lower weight gain than control animals. TTG revealed peripheral insulin resistance in HFD, FRD and GK rats compared to control rats. In agreement with these data, TTI shows that the FRD and GK groups exhibited impaired insulin sensitivity. Western blot analysis of insulin signaling demonstrated cardiac insulin resistance only in GK rats. Specifically, Akt phosphorylation in Ser473 showed resistance to hepatic insulin in the FRD and GK groups. HFD and FRD rats also demonstrated an attenuated increase in the phosphorylation of the insulin-stimulated Akt protein in white adipose tissue. Conclusion. In conclusion, despite impaired systemic glucose tolerance, diet-only models exhibited preserved cardiac insulin signaling. In contrast, polygenic GK rats demonstrated systemic and cardiac RIMestradoPesquisa ClínicaMestra em Ciências427224/2016-0CNP

Heart defibrillation : relationship between pacing threshold and defibrillation probability

Considering the clinical importance of the ventricular fibrillation and that the most used therapy to reverse it has a critical side effect on the cardiac tissue, it is desirable to optimize defibrillation parameters to increase its efficiency. In this study, we investigated the influence of stimuli duration on the relationship between pacing threshold and defibrillation probability. We found out that 0.5-ms-long pulses had a lower ratio of defibrillation probability to the pacing threshold, although the higher the pulse duration the lower is the electric field intensity required to defibrillate the hearts. The appropriate choice of defibrillatory shock parameters is able to increase the efficiency of the defibrillation improving the survival chances after the occurrence of a severe arrhythmia. The relationship between pulse duration and the probability of reversal of fibrillation shows that this parameter cannot be underestimated in defibrillator design since different pulse durations have different levels of safety.181COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPNão tem2011/51199-6; 2011/51199-6The authors are grateful to the R&D team at CEB/UNICAMP and NMCE-Núcleo de Medicina e Cirurgia Experimental at Faculty of Medical Science-UNICAMP for the valuable technical support. This study was supported by CAPES (Coordination of Improvement of Higher Education Personnel, in Portuguese, scholarship to Priscila C. Antoneli) and FAPESP (Foundation for Research of the State of São Paulo, in Portuguese, Proc. N 2011/51199-6). This study was supported by CAPES (Coordination of Improvement of Higher Education Personnel, in Portuguese, scholarship to Priscila C. Antoneli) and FAPESP (Foundation for Research of the State of São Paulo, in Portuguese, Proc. N 2011/51199-6

HDL preserves mitochondrial complex I activity during myocardial reperfusion injury

Introduction. Myocardial reperfusion injury answers for half of final infarct size following myocardial infarction, although no effective therapy has yet been discovered. Modulation of mitochondrial activity stands as an attractive target, as its impairment following reperfusion impairs ATP generation and henceforth turns cardiac recovery less prone to occur. HDL reduced final infarct size in different ischemia-reperfusion injury models for unknown mechanisms. Whether this effect involves mitochondrial activity modulation is unknown. Hypothesis. HDL post-conditioning preserves mitochondrial activity. Methods. Hearts extracted from male adult Wistar rats were subjected to 35min of regional ischemia, followed by 90min of reperfusion in a Langendorff apparatus. HDL (200ug/mL) or saline solution (PBS) was administered during the 7 first minutes of reperfusion. Infarct size was determined as percentage of total ventricular area, considering area at risk (AAR) as the delineated by Evans Blue. Cardiac samples underwent high-resolution oxygraph, and maximal oxygen consumption rate was calculated after the addition of saturating concentrations of ADP (1mM). Mitochondrial viability and complex I activity were assessed by colorimetric assays. Statistical analysis. Data are mean ± standard error. Means were compared by Student`s t test and p value < 0,05 was considered significant. Results. Treatment with HDL improved cardiac recovery, as indicated by better recovery of LVDP and dP/dT, and reduction of coronary artery resistance in comparison to control group (30,5 vs. 46,7%, 26 vs. 54,7% and 144±30 Vs. 98±14mmHg/mL, respectively; p<0.01). Treatment with HDL reduced final infarct size by 30% in comparison to control (69.2±3.7% Vs. 49.2±13%; p<0.001). The HDL group showed higher ADP-stimulated oxygen consumption rate (7.1±2.2 Vs. 33.8±6.6pmol/s.mg; p<0.05; n=6) and greater complex I activity (12.7±4.2 vs. 30.7±4.4mOD/min; p<0.05; n=3 per group) compared to control, though mitochondrial content was comparable (1.1±0.8 vs. 1.1±0.8AU; n=3; ns). Conclusions. Ischemic postconditioning with HDL reduces infarct size and preserves complex I activity, improving myocardial recovery following reperfusion injury

The Reciprocal Relationship between LDL Metabolism and Type 2 Diabetes Mellitus

International audienceType 2 diabetes mellitus and insulin resistance feature substantial modifications of the lipoprotein profile, including a higher proportion of smaller and denser low-density lipoprotein (LDL) particles. In addition, qualitative changes occur in the composition and structure of LDL, including changes in electrophoretic mobility, enrichment of LDL with triglycerides and ceramides, prolonged retention of modified LDL in plasma, increased uptake by macrophages, and the formation of foam cells. These modifications affect LDL functions and favor an increased risk of cardiovascular disease in diabetic individuals. In this review, we discuss the main findings regarding the structural and functional changes in LDL particles in diabetes pathophysiology and therapeutic strategies targeting LDL in patients with diabetes

Adverse interaction between HDL and the mass of myocardial infarction

Coronary reperfusion with HDL from healthy volunteers attenuates ischemia and reperfusion injury in animal models. In myocardial infarction (MI) patients, such an interaction is unclear. Hence, our first objective was to verify if there is interaction between HDL-C and MI mass in patients and the role of coronary reperfusion in the interaction. Furthermore, we investigated whether the effect in MI size of reperfusion with HDL obtained from healthy participants or MI patients could differ. HDL-C was measured the first day after MI and MI mass was quantified by cardiac magnetic resonance (n = 94) and peak CKMB (n = 393). In an ex vivo rat heart model, we compared MI area and dP/dt max after coronary reperfusion with HDL from MI patients or healthy volunteers. HDL-C above the median (35 mg/dL) was associated with higher peak CKMB [255 (145–415) vs. 136 (84–287) UI/L; p = 0.02], higher MI mass [17 (9–21) vs. 10 (6–14) g; p < 0.01] and lower left ventricular ejection fraction [47 (34–53) vs. 51 (43–59); p = 0.02] than their counterparts. In restricted cubic spline and multivariate linear regression, HDL-C was directly associated with peak CKMB (p < 0.01) and MI mass (p < 0.01) only in reperfused patients with time to reperfusion <4 h. Reperfusion with healthy HDL, but not from MI patients, reduced MI mass (p < 0.01) and improved dP/dt max (p = 0.02). In MI patients undergoing early coronary reperfusion, HDL-C levels at admission are directly associated with MI size. In contrast to healthy HDL, reperfusion with HDL from MI patients do not reduce MI area in an ex vivo animal model.281916The Brasilia Heart Study group is coordinated by Prof. Sposito and the authors of this manuscript are among those responsible for the presented data. We thank the Brasilia Heart Study participants as well as the other investigators of the study for their contributio

Rationale and design of the expanded combination of evolocumab plus empagliflozin in diabetes: EXCEED-BHS3 trial

International audienceBackground: Patients with type 2 diabetes mellitus (T2DM) remain at increased cardiovascular residual risk and endothelial dysfunction, even after optimizing metabolic control and treatment by sodium-glucose-2 transporter inhibitors (SGLT2-is). The present study was based on the hypothesis that proprotein convertase subtilisin/kexin 9 inhibitor (PCSK9i) therapy may mitigate endothelial dysfunction in T2DM patients who are on regular treatment by SGLT2-i.Methods: The EXCEED-BHS3 is a prospective, single-center, investigator-blinded, open-label, randomized clinical trial. Participants (n= 110) will be randomized (1:1) to either empagliflozin 25 mg/day alone or empagliflozin 25 mg/day plus evolocumab 140 mg every 2 weeks in addition to optimal medical care. The primary endpoint was defined as the change in the 1-min flow-mediated dilation (FMD) after 16 weeks of treatment. The secondary endpoint is the FMD change after ischemia/reperfusion injury protocol (reserve FMD) after 16 weeks of treatment. Exploratory outcomes comprise the change in FMD and reserve FMD after 8 weeks of treatment and the change after 16 weeks of treatment in the following parameters: plasma levels of nitric oxide, vascular cell adhesion molecule-1 and isoprostane, high-density lipoprotein (HDL) and low-density lipoprotein subfractions profile, HDL function, blood pressure, body mass index, waist circumference and adipokines.Conclusion: This will be the first study to evaluate the add-on effect of PCSK9i on endothelial function of T2DM patients under regular use of empagliflozin

Comparative effectiveness and cost-effectiveness of cardioprotective glucose-lowering therapies for type 2 diabetes in Brazil: a Bayesian network model

Abstract Background The escalating prevalence of type 2 diabetes (T2DM) poses an unparalleled economic catastrophe to developing countries. Cardiovascular diseases remain the primary source of costs among individuals with T2DM, incurring expenses for medications, hospitalizations, and surgical interventions. Compelling evidence suggests that the risk of cardiovascular outcomes can be reduced by three classes of glucose-lowering therapies (GLT), including SGLT2i, GLP-1A, and pioglitazone. However, an evidence-based and cost-effective protocol is still unavailable for many countries. The objective of the current study is to compare the effectiveness and cost-effectiveness of GLT in individuals with T2DM in Brazil. Methods We employed Bayesian Networks to calculate the incremental cost-effectiveness ratios (ICER), expressed in international dollars (Int$) per disease-adjusted life years [DALYs] averted. To determine the effectiveness of GLT, we conducted a systematic review with network meta-analysis (NMA) to provide insights for our model. Additionally, we obtained cardiovascular outcome incidence data from two real-world cohorts comprising 851 and 1337 patients in primary and secondary prevention, respectively. Our cost analysis took into account the perspective of the Brazilian public health system, and all values were converted to Int$. Results In the NMA, SGLT2i [HR: 0.81 (95% CI 0.69–0.96)], GLP-1A [HR: 0.79 (95% CI 0.67–0.94)], and pioglitazone [HR: 0.73 (95% CI 0.59–0.91)] demonstrated reduced relative risks of non-fatal cardiovascular events. In the context of primary prevention, pioglitazone yielded 0.2339 DALYs averted, with an ICER of Int$7,082 (95$12,061 (95% CI: 7,227–18,121) and Int$29,119 (95$26,700. Notably, pioglitazone consistently exhibited the highest probability of being cost-effective in both scenarios. Conclusions In Brazil, pioglitazone presented a higher probability of being cost-effective both in primary and secondary prevention, followed by SGLT2i and GLP-1A. Our findings support the use of cost-effectiveness models to build optimized and hierarchical therapeutic strategy in the management of T2DM. Trial registration CRD42020194415

Compliance with Cardiovascular Prevention Guidelines in Type 2 Diabetes Individuals in a Middle-Income Region: A Cross-Sectional Analysis

Stricter control of risk factors has been pursued as a compelling strategy to mitigate cardiovascular events (CVE) in type 2 diabetes (T2D) individuals. However, the achievement rate of the recommended goals has remained low in clinical practice. This study investigated the 2019 ESC guideline recommendation attainment among T2D individuals enrolled in a national cohort held in Brazil. Data from 1030 individuals (mean age: 58 years old; 54% male; mean T2D duration: 9.7 years) were analyzed. The control rates were 30.6% for SBP, 18.8% for LDL-C, and 41% for A1c, and only 3.2% of the study participants met all three targets. Statins and high-intensity lipid-lowering therapy prescription rates were 45% and 8.2%, respectively. Longer T2D duration and those at higher CV risk were less likely to be controlled. Longer diabetes duration and higher CV risk were inversely related to the chance of achieving the recommended targets. Treatment escalation using conventional therapies would be sufficient to gain optimal control in most of the study sample. In conclusion, a minimal proportion of T2D individuals comply with guidelines-oriented CV prevention targets. Given the significant burden of the disease, and the substantial effect size predicted for these therapies, bridging this gap between guidelines and clinical practice should be considered an urgent call to public health managers

Reciprocal Multifaceted Interaction Between HDL (High-Density Lipoprotein) and Myocardial Infarction

Despite decades of therapeutic advances, myocardial infarction remains a leading cause of death worldwide. Recent studies have identified HDLs (high-density lipoproteins) as a potential candidate for mitigating coronary ischemia/reperfusion injury via a broad spectrum of signaling pathways. HDL ligands, such as S1P (sphingosine-1-phosphate), Apo (apolipoprotein) A-I, clusterin, and miRNA, may influence the opening of the mitochondrial channel, insulin sensitivity, and production of vascular autacoids, such as NO, prostacyclin, and endothelin-1. In parallel, antioxidant activity and sequestration of oxidized molecules provided by HDL can attenuate the oxidative stress that triggers ischemia/reperfusion. Nevertheless, during myocardial infarction, oxidation and the capture of oxidized and proinflammatory molecules generate large phenotypic and functional changes in HDL, potentially limiting its beneficial properties. In this review, new findings from cellular and animal models, as well as from clinical studies, will be discussed to describe the cardioprotective benefits of HDL on myocardial infarction. Furthermore, mechanisms by which HDL modulates cardiac function and potential strategies to mitigate postmyocardial infarction risk damage by HDL will be detailed throughout the review

Assessment of dapagliflozin effect on diabetic endothelial dysfunction of brachial artery (ADDENDA-BHS2 trial): rationale, design, and baseline characteristics of a randomized controlled trial

Endothelial dysfunction (ED) is a hallmark in type 2 diabetes mellitus (T2DM) that favor both atherogenesis and ischemia and reperfusion injury (IRI). Sodium-glucose-2 co-transporter inhibitors (SGLT2i) may hypothetically improve microvascular and macrovascular functions via a broad spectrum of mechanisms, being superior to traditional antidiabetic therapy such as sulfonylurea, even in subjects under equivalent glycemic control. Hence, the present clinical trial was designed to compare the effect of these two treatments on markers of arterial wall function and inflammation in T2DM patients as well as on the potential mediating parameters. ADDENDA-BHS2 is a prospective, single-center, active-controlled, open, randomized trial. Ninety-eight participants (40-70years old) with HbA1c 7-9% were randomized (1:1, stratified by gender, BMI and HbA1c levels) to either dapagliflozin 10mg/day or glibenclamide 5mg/day on top of metformin. The primary endpoint was the change of flow-mediated dilation (FMD) after a 12-week period of treatment evaluated at rest and after IRI between dapagliflozin and glibenclamide arms. Secondary outcomes were defined as the difference between treatments regarding: plasma nitric oxide (NO) change after FMD, plasma isoprostane, plasma levels of vascular inflammatory markers and systemic inflammatory markers, plasma levels of adipokines, anthropometric measures, glucose control parameters, office and ambulatory BP control. Safety endpoints were defined as systolic and diastolic function assessed by echocardiography and retinopathy change. Serious adverse events were recorded. The study protocol was approved by the Independent Scientific Advisory Committee. The ADDENDA-BHS2 trial is an investigator-initiated clinical trial comparing the effect of dapagliflozin versus glibenclamide on several aspects of vascular function in high cardiovascular risk T2DM patients. Besides, a large clinical and biochemical phenotype assessment will be obtained for exploring potential mediations and associations.11CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ301465/2017-