Endothelial Dysfunction in Cardiovascular Disease

The measurement of endothelial function might predict the presence of CAD in patients. Therefore, we tested in part I of this thesis the applicability of peripheral endothelial dysfunction as a measurement for the presence of coronary artery disease (CAD) in symptomatic patients. We showed that endothelial function measurement with peripheral arterial tonometry is a heterogeneous measurement with poor correlation with traditional measurements. Moreover, the measurement failed to predict revascularization within one year. Therefore, in spite of the pathophysiological basis of endothelial dysfunction in CAD, no evidence was found for peripheral endothelial function measurement as a diagnostic tool to detect clinically relevant CAD. Since patient studies to unravel underlying disease processes are usually hampered by limited measurements because of ethical concerns; experimental disease models in animals can enhance our understanding of the pathogenesis of CAD. Therefore, we studied and developed an animal model of CAD, in which we studied the coronary microcirculation. We demonstrated that small coronary arteries showed functional alterations in vitro in the process of early systemic atherosclerosis development in diabetic pigs on a high fat diet, reflecting an altered coronary microvascular balance. This balance changed over time during CAD progression and was shown to be a systemic process. In part II of this thesis, we studied endothelial dysfunction in relation to percutaneous coronary interventions. We demonstrated that specific first generation drug

Dietary saturated fat/cholesterol, but not unsaturated fat or starch, induces C-reactive protein associated early atherosclerosis and ectopic fat deposition in diabetic pigs

Background: Diabetes is thought to accelerate cardiovascular disease depending on the type of diet. This study in diabetic subjects was performed to investigate the metabolic, inflammatory and cardiovascular effects of nutritional components typically present in a Western, Mediterranean or high glycaemic diet.Methods: Streptozotocin-diabetic pigs (~45 kg) were fed for 10 weeks supplemental (40% of dietary energy) saturated fat/cholesterol (SFC), unsaturated fat (UF) or starch (S) in an eucaloric dietary intervention study.Results: Fasting plasma total, LDL and HDL cholesterol concentrations were 3-5 fold higher (p < 0.01) in SFC compared to UF and S pigs. Fasting plasma NEFA concentrations (mmol/L) were highest (p < 0.05) in SFC (1.09 ± 0.17), intermediate in UF (0.80 ± 0.14) and lowest in S pigs (0.58 ± 0.14) whereas plasma glucose (~13 mmol/L), triglyceride (~0.5 mmol/L) and insulin (~24 pmol/L) concentrations were comparable among SFC, UF and S pigs. The postprandial response area under the curves (AUC, 0-4 h) for glucose but not for insulin and triglyceride responses were intermediate in SFC (617 ± 144) and lowest (p < 0.05) in UF (378 ± 157) compared to S pigs (925 ± 139). Fasting hepatic glucose production, hepatic and peripheral insulin sensitivity and blood pressure were not different among pigs. C-reactive protein (CRP) concentrations (mg/L) were highest (p < 0.05) in SFC (25 ± 4), intermediate in S (21 ± 3) and lowest in UF pigs (14 ± 2). Liver weights, liver and muscle triglyceride concentrations, and the surface area of aorta fatty streaks were highest (p < 0.01) in SFC pigs. A positive correlation between postprandial plasma CRP and aorta fatty streaks was observed in SFC pigs (R2= 0.95). Retroperitoneal fat depot weight (g) was intermediate in SFC (260 ± 72), lowest in S (135 ± 51) and highest (p < 0.05) in UF (571 ± 95) pigs.Conclusion: Dietary saturated fat/cholesterol induces inflammation, atherosclerosis and ectopic fat deposition whereas an equally high dietary unsaturated fat load does not induce these abnormalities and shows beneficial effects on postprandial glycaemia in diabetic pigs

Combined renin inhibition/(Pro)renin receptor blockade in diabetic retinopathy- a study in transgenic (mREN2)27 rats

Dysfunction of renin-angiotensin system (RAS) contributes to the pathogenesis of diabetic retinopathy (DR). Prorenin, the precursor of renin is highly elevated in ocular fluid of diabetic patients with proliferative retinopathy. Prorenin may exert local effects in the eye by binding to the so-called (pro)renin receptor ((P)RR). Here we investigated the combined effects of the renin inhibitor aliskiren and the putative (P)RR blocker handle-region peptide (HRP) on diabetic retinopathy in streptozotocin (STZ)-induced diabetic transgenic (mRen2)27 rats (a model with high plasma prorenin levels) as well as prorenin stimulated cytokine expression in cultured Müller cells. Adult (mRen2)27 rats were randomly divided into the following groups: (1) non-diabetic; (2) diabetic treated with vehicle; (3) diabetic treated with aliskiren (10 mg/kg per day); and (4) diabetic treated with aliskiren+HRP (1 mg/kg per day). Age-matched non-diabetic wildtype Sprague-Dawley rats were used as control. Drugs were administered by osmotic minipumps for three weeks. Transgenic (mRen2)27 rat retinas showed increased apoptotic cell death of both inner retinal neurons and photoreceptors, increased loss of capillaries, as well as increased expression of inflammatory cytokines. These pathological changes were further exacerbated by diabetes. Aliskiren treatment of diabetic (mRen2)27 rats prevented retinal gliosis, and reduced retinal apoptotic cell death, acellular capillaries and the expression of inflammatory cytokines. HRP on top of aliskiren did not provide additional protection. In cultured Müller cells, prorenin significantly increased the expression levels of IL-1α and TNF-α, and this was completely blocked by aliskiren or HRP, their combination, (P)RR siRNA and the AT1R blocker losartan, suggesting that these effects entirely depended on Ang II generation by (P)RR-bound prorenin. In conclusion, the lack of effect of HRP on top of aliskiren, and the Ang II-dependency of t

Early systemic microvascular damage in pigs with atherogenic diabetes mellitus coincides with renal angiopoietin dysbalance

Background: Diabetes mellitus (DM) is associated with a range of microvascular complications including diabetic nephropathy (DN). Microvascular abnormalities in the kidneys are common histopathologic findings in DN, which represent one manifestation of ongoing systemic microvascular damage. Recently, sidestream dark-field (SDF) imaging has emerged as a noninvasive tool that enables one to visualize the microcirculation. In this study, we investigated whether changes in the systemic microvasculature induced by DM and an atherogenic diet correlated spatiotemporally with renal damage. Methods: Atherosclerotic lesion development was triggered in streptozotocin-induced DM pigs (140 mg/kg body weight) by administering an atherogenic diet for approximately 11 months. Fifteen months following induction of DM, microvascular morphology was visualized in control pigs (n = 7), non-diabetic pigs fed an atherogenic diet (ATH, n = 5), and DM pigs fed an atherogenic diet (DM+ATH, n = 5) using SDF imaging of oral mucosal tissue. Subsequently, kidneys were harvested from anethesized pigs and the expression levels of well-established markers for microvascular integrity, such as Angiopoietin-1 (Angpt1) and Angiopoietin-2 (Angpt2) were determined immunohistochemically, while endothelial cell (EC) abundance was determined by immunostaining for von Willebrand factor (vWF). Results: Our study revealed an increase in the capillary tortuosity index in DM+ATH pigs (2.31±0.17) as compared to the control groups (Controls 0.89±0.08 and ATH 1.55±0.11; p<0.05). Kidney biopsies showed marked glomerular lesions consisting of mesangial expansion and podocyte lesions. Furthermore, we observed a disturbed Angpt2/ Angpt1balance in the cortex of the kidney, as evidenced by increased expression of Angpt2 in DM+ATH pigs as compared to Control pigs (p<0.05). Conclusion: In the setting of DM, atherogenesis leads to the augmentation of mucosal capillary tortuosity, indicative of systemic microvascular damage. Concomitantly, a dysbalance in renal angiopoietins was correlated with the development of diabetic nephropathy. As such, our studies strongly suggest that defects in the systemic microvasculature mirror the accumulation of microvascular damage in the kidney

The effect of bioresorbable vascular scaffold implantation on distal coronary endothelial function in dyslipidemic swine with and without diabetes

Background: We studied the effect of bioresorbable vascular scaffold (BVS) implantation on distal coronary endothelial function, in swine on a high fat diet without (HFD) or with diabetes (DM + HFD). Methods: Five DM + HFD and five HFD swine underwent BVS implantation on top of coronary plaques, and were studied six months later. Conduit artery segments >. 5. mm proximal and distal to the scaffold and corresponding control segments of non-scaffolded coronary arteries, as well as segments of small arteries within the flow-territories of scaffolded and non-scaffolded arteries were harvested for in vitro vasoreactivity studies. Results: Conduit segments proximal and distal to the BVS edges showed reduced endothelium-dependent vasodilation as compared to control vessels (p <. 0.01), with distal segments being most prominently affected (p <. 0.01). Endothelial dysfunction was only observed in DM + HFD swine and was principally due to a loss of NO. Endothelium-independent vasodilation and vasoconstriction were unaffected. Surprisingly, segments from the microcirculation distal to the BVS showed enhanced endothelium-dependent vasodilation (p <. 0.01), whereas endothelium-independent vasodilation and vasoconstriction were unaltered. This enhanced vasorelaxation was only observed in DM + HFD swine, and did not appear to be either NO- or EDHF-mediated. Conclusions: Six months of BVS implantation in DM + HFD swine causes NO-mediated endothelial dysfunction in nearby coronary segments, which is accompanied by a, possibly compensatory, increase in endothelial function of the distal microcirculation. Endothelial dysfunction extending into coronary conduit segments beyond the implantation-site, is in agreement with recent reports expressing concern for late scaffold thrombosis and of early BVS failure in diabetic patients

Serial Coronary Imaging of Early Atherosclerosis Development in Fast-Food-Fed Diabetic and Nondiabetic Swine

Patients with diabetes mellitus (DM) are at increased risk for atherosclerosis-related events compared to non-DM (NDM) patients. With an expected worldwide epidemic of DM, early detection of anatomic and functional coronary atherosclerotic changes is gaining attention. To improve our understanding of early atherosclerosis development, we studied a swine model that gradually developed coronary atherosclerosis. Interestingly, optical coherence tomography, near-infrared spectroscopy (NIRS), vascular function, and histology demonstrated no differences between development of early atherosclerosis in fast-food-fed (FF) DM swine and that in FF-NDM swine. Coronary computed tomography angiography did not detect early atherosclerosis, but optical coherence tomography and near-infrared spectroscopy demonstrated coronary atherosclerosis development in FF-DM and FF-NDM swine

Neoatherosclerosis development following bioresorbable vascular scaffold implantation in diabetic and non-diabetic swine

Background: DM remains a risk factor for poor outcome after stent-implantation, but little is known if and how DM affects the vascular response to BVS. Aim: The aim of our study was to examine coronary responses to bioresorbable vascular scaffolds (BVS) in swine with and without diabetes mellitus fed a ‘fast-food’ diet (FF-DM and FF-NDM, respectively) by sequential optical coherence tomography (OCT)-imaging and histology. Methods: Fifteen male swine were evaluated. Eight received streptozotocin-injection to induce DM. After 9 months (M), 32 single BVS were implanted in epicardial arteries with a stent to artery (S/A)-ratio of 1.1:1 under quantitative coronary angiography (QCA) and OCT guidance. Lumen, scaffold, neointimal coverage and composition were assessed by QCA, OCT and near-infrared spectroscopy (NIRS) pre- and/or post-procedure, at 3M and 6M. Additionally, polarization-sensitive (PS)-OCT was performed in 7 swine at 6M. After sacrifice at 3M and 6M, histology and polymer degradation analysis were performed. Results: Late lumen loss was high (~60%) within the first 3M after BVS-implantation (P0.20). Neointimal coverage was highly heterogeneous in all swine (DM vs. NDM P>0.05), with focal lipid accumulation, irregular collagen distribution and neointimal calcification. Likewise, polymer mass loss was low (~2% at 3M, ~5% at 6M;P>0.20) and not associated with DM or inflammation. Conclusion: Scaffold coverage showed signs of neo-atherosclerosis in all FF-DM and FF-NDM swine, scaffold polymer was preserved and the vascular response to BVS was not influenced by diabetes

Guideline implementation, drug sequencing, and quality of care in heart failure:design and rationale of TITRATE-HF

Aims: Current heart failure (HF) guidelines recommend to prescribe four drug classes in patients with HF with reduced ejection fraction (HFrEF). A clear challenge exists to adequately implement guideline-directed medical therapy (GDMT) regarding the sequencing of drugs and timely reaching target dose. It is largely unknown how the paradigm shift from a serial and sequential approach for drug therapy to early parallel application of the four drug classes will be executed in daily clinical practice, as well as the reason clinicians may not adhere to new guidelines. We present the design and rationale for the real-world TITRATE-HF study, which aims to assess sequencing strategies for GDMT initiation, dose titration patterns (order and speed), intolerance for GDMT, barriers for implementation, and long-term outcomes in patients with de novo, chronic, and worsening HF. Methods and results: A total of 4000 patients with HFrEF, HF with mildly reduced ejection fraction, and HF with improved ejection fraction will be enrolled in &gt;40 Dutch centres with a follow-up of at least 3 years. Data collection will include demographics, physical examination and vital parameters, electrocardiogram, laboratory measurements, echocardiogram, medication, and quality of life. Detailed information on titration steps will be collected for the four GDMT drug classes. Information will include date, primary reason for change, and potential intolerances. The primary clinical endpoints are HF-related hospitalizations, HF-related urgent visits with a need for intravenous diuretics, all-cause mortality, and cardiovascular mortality. Conclusions: TITRATE-HF is a real-world multicentre longitudinal registry that will provide unique information on contemporary GDMT implementation, sequencing strategies (order and speed), and prognosis in de novo, worsening, and chronic HF patients.</p