The role of free radicals and antioxidants in human disease, particularly cardiovascular disease is an area of intensive research. Diabetes mellitus is the most common condition associated with increased oxidative stress and accelerated a therosclerosis.Increased levels of lipid peroxides and diminished antioxidant vitamin status have been reported in diabetic patients and are also implicated in the chronic complications of diabetes. The autoxidation and glycoxidation reactions of glucose are sources of free radicals in vitro and a preliminary investigation that these reactions may be a source of free radicals in vivo was undertaken in patients admitted to hospital with severe hyperglycaemia or diabetic ketoacidosis. Plasma lipid peroxides were elevated 2-7 fold above the reference range, but decreased during the recovery period in these patients. Plasma urate and ascorbate levels decreased rapidly, whilst interestingly, a-tocopherol levels / lipid ratios were preserved. The study indicated the resilient nature of the antioxidant defences in plasma, although further studies are required in order to elucidate fully the role of autoxidation and glycoxidation reactions in vivo. Insulin resistance and hyperinsulinaemia are also tightly linked with atherogenesisin type II diabetes and weight loss in obese subjects plays an important part in the reversal of insulin resistance. The safety and efficacy of two weight loss interventions - very low calorie diet (VLCD) and intensive conventional dietetic (ICD) therapy - on cardiovascular risk factors and indices of oxidative stress were investigated in obese diabetic and non-diabetic subjects. The ICD therapy produced modest weight loss in patients with established diabetes with transient improvements in diastolic blood pressure and plasma ascorbate, but with a reduction in vitamin E/ serum lipid ratios. The VLCD produced large and rapid weight loss in diabetic and non-diabetic patients with improvements in cardiovascular risk factors, lipid peroxides and vitamin E/ serum lipid ratios, which were maintained after 12 months. Plasma ascorbate concentrations were significantly lower in diabetic patients than nondiabetic patients on the VLCD, indicating that formulated diets may require higher concentrations of vitamin C for diabetic patients and this requires further investigation. The VLCD successfully reversed type II diabetes and normalized plasma lipid peroxide levels in two newly diagnosed patients.

Background: Recent studies have revealed an association between genetic variants at the ADAMTS7 (a disintegrin-like and metalloprotease with thrombospondin type 1 motif, 7) locus and susceptibility to coronary artery disease (CAD). ADAMTS-7 has been reported to facilitate vascular smooth muscle cell (VSMC) migration and promote neointima formation. We sought to study the functional mechanisms underlying this relationship and to further investigate the role of ADAMTS-7 in atherosclerosis. Methods and Results: In vitro assays showed that the CAD-associated non-synonymous single nucleotide polymorphism rs3825807, which results in a serine to proline (Ser-to- Pro) substitution at residue 214 in the ADAMTS-7 pro-domain, affected ADAMTS-7 prodomain cleavage. Immunohistochemical analyses showed that ADAMTS-7 localised to vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) in human coronary and carotid atherosclerotic plaques. Cell migration assays demonstrated that VSMCs and ECs from individuals who were homozygous for the adenine (A) allele (encoding the Ser214 isoform) had increased migratory ability compared with cells from individuals who were homozygous for the G allele (encoding the Pro214 isoform). Western blot analyses revealed that media conditioned by VSMCs of the A/A genotype contained more cleaved ADAMTS-7 pro-domain and more of the cleaved form of thrombospondin-5 (TSP-5, an ADAMTS-7 substrate that had been shown to be produced by VSMCs and inhibit VSMC migration). In in vitro angiogenesis assays, ECs of the A/A genotype exhibited increased capillary-like network formation. ADAMTS-7 over-expression in ECs by transfection of an ADAMTS7-214Ser expressing plasmid significantly accelerated EC migration and in vitro angiogenesis, whereas ADAMTS-7 knockdown by shRNA had opposite effects. Preliminary proteomics analyses of conditioned media of ECs overexpressing ADAMTS-7 and ECs with ADAMTS-7 knockdown indicated that ADAMTS- 7 can cleave thrombospondin-1 (TSP-1), a well-recognised angiogenesis inhibitor. Conclusion: The results of this study indicate that rs3825807 has a functional effect on ADAMTS-7 maturation, TSP-5 cleavage, VSMC and EC migration, and angiogenesis. As VSMC migration and angiogenesis play important roles in atherosclerosis, these results provide a mechanistic explanation for the association between rs3825807 and CAD.

Vascular smooth muscle cell (VSMC) accumulation is a hallmark of atherosclerosis and vascular injury. However, fundamental aspects of proliferation and the phenotypic changes within individual VSMCs, which underlie vascular disease remain unresolved. In particular, it is not known if all VSMCs proliferate and display plasticity, or whether individual cells can switch to multiple phenotypes. To assess whether proliferation and plasticity in disease is a general characteristic of VSMCs or a feature of a subset of cells, multi-colour lineage labelling is used to demonstrate that VSMCs in injury-induced neointimal lesions and in atherosclerotic plaques are oligo-clonal, derived from few expanding cells, within mice. Lineage tracing also revealed that the progeny of individual VSMCs contribute to both alpha Smooth muscle actin (aSma)-positive fibrous cap and Mac-3-expressing macrophage-like plaque core cells. Co-staining for phenotypic markers further identified a double-positive aSma+ Mac3+ cell population, which is specific to VSMC-derived plaque cells. In contrast, VSMC-derived cells generating the neointima after vascular injury generally retained expression of VSMC markers and upregulation of Mac3 was less pronounced. Monochromatic regions in atherosclerotic plaques and injury-induced neointima did not contain VSMC-derived cells expressing a different fluorescent reporter protein, suggesting that proliferation-independent VSMC migration does not make a major contribution to VSMC accumulation in vascular disease. Similarly, VSMC proliferation was examined in an Angiotensin II perfusion model of aortic aneurysm in mice, oligo-clonal proliferation was observed in remodelling regions of the vasculature, however phenotypic changes were observed in a large proportion of VSMCs, suggesting that the majority of VSMCs have some potential to modulate their phenotype. To understand the mechanisms behind the inherent VSMC heterogeneity and observed functionality, the single cell transcriptomic techniques Smart-seq2 and the Chromium 10X system were optimized for use on VSMCs. The work within this thesis suggests that extensive proliferation of a low proportion of highly plastic VSMCs results in the observed VSMC accumulation after injury, and the atherosclerotic and aortic aneurysm models of cardiovascular disease.

Typ-2-Diabetiker haben ein hohes kardiovaskuläres Risiko. Es wurden 23 Typ-2-Diabetiker in eine Interventions- und eine Kontrollgruppe randomisiert. Die Interventionsgruppe nahm an einem multifaktoriellen Sekundärpräventionsprogramm mit Fokus auf intensivem körperlichen Training teil. Die Kontrollgruppe wurde leitlinienkonform durch die Hausärzte therapiert. Nach einem vierwöchigen stationären Training trainierte die Interventionsgruppe über fünf Monate zu Hause. Beide Gruppen wurden bei Studienbeginn, nach vier Wochen und nach sechs Monaten umfassend untersucht (Ergometrie, Labordiagnostik verschiedener Stoffwechselparameter, Messung der Endothelfunktion, Quantifizierung der koronaren Plaquelast). Nach vier Wochen sowie nach sechs Monaten Training zeigte sich in der Interventionsgruppe eine Verbesserung von Gewicht, BMI, maximaler Trainingsintensität und Trainingsdauer. Weiterhin zeigte sich nach vier Wochen Training eine signifikante Verbesserung der Stoffwechselparameter, die nach sechs Monaten nicht mehr nachweisbar war. Die Endothelfunktion verbesserte sich erst nach sechs Monaten Training signifikant. Die koronare Plaquelast veränderte sich nicht. Die Kontrollgruppe zeigte zu keinem Zeitpunkt Veränderungen. Ein intensives multifaktorielles Interventionsprogramm kann die endotheliale Dysfunktion der Koronararterien von Typ-2-Diabetikern korrigieren, ohne eine quantitative Regression der Atherosklerose zu erreichen. Ein stationäres Training verbessert die Stoffwechselsituation gegenüber einem Heimtraining, vermutlich durch verbesserte Compliance und bessere diätetische Kontrolle.