IntroductionAngiotensin II (ANG II) is known to be a potent growth promoting factor for vascular smooth muscle cells and fibroblasts but little is known about its influence on growth in endothelial cells. We studied the effects of ANG II Angiotensin II (ANG II),' the main effector peptide of the renin-angiotensin system, has long been known to play an important role in the regulation of blood pressure and body fluid homeostasis. More recently, ANG II has been reported to induce hyperplasia or hypertrophy in cultured vascular smooth muscle cells derived from the aorta ( 1-4), in small resistance arteries (5) and in cardiomyocytes (6).We have previously observed that chronic oral treatment of spontaneously hypertensive rats (SHR) with an angiotensin converting enzyme inhibitor induced myocardial capillary growth independently of the antihypertensive and antihypertrophic actions of the drug (7). Theoretically, this effect could be due to a potentiation of endogenous kinins or to a reduced generation of ANG II. In the latter case, one would have to expect an antiproliferative effect of ANG II on myocardial endothelial cells which gives rise to cardiac capillaries. This hypothesis is at variance with the widely accepted idea of ANG II being a growth promoting factor in cardiovascular tissues. However, using coronary endothelial cells (CEC) from SHR and normotensive Wistar Kyoto rats in primary culture, we recently found that ANG II significantly attenuated proliferation when growth was stimulated by fetal calf serum (8, 9). Thus, in contrast to its proliferating effects on vascular smooth muscle cells (VSMC), ANG II may indeed exert antiproliferative actions on vascular endothelial cells.VSMC in culture, a common cell line to study the trophic effects of ANG II, exclusively express ATI-and no AT2-receptors (10). Therefore, ANG 11-induced growth shown in VSMC in vitro has been attributed to the ATl-receptor. The obvious discrepancy between the effects of ANG II on VSMC and on microvascular endothelial cells could be explained twofold. First, angiotensin receptors on endothelial cells could be identical to those on VSMC (i.e., ATI) but coupled to intracellular pathways different from those present in VSMC. Second, the antiproliferative response to treatment with ANG II, as observed in endothelial cells, could be due to the stimulation of an angiotensin receptor subtype different from AT1, for instance the AT2-receptor. In addition, the antiproliferative effect of ANG II could be a phenomenon occurring in serum-stimulated rat cardiac microvascular endothelial cells but not a general feature of CEC under stimulation with defined growth factors.In the present study we investigated, first, whether ANG II is antimitogenic for CEC stimulated to proliferate by the administration of a defined growth factor and second, by which angiotensin receptor subtype, ATl or AT2, the antimitogenic

The European Cooperation in Science and Technology (COST) provides an ideal framework to establish multi-disciplinary research networks. COST Action BM1203 (EU-ROS) represents a consortium of researchers from different disciplines who are dedicated to providing new insights and tools for better understanding redox biology and medicine and, in the long run, to finding new therapeutic strategies to target dysregulated redox processes in various diseases. This report highlights the major achievements of EU-ROS as well as research updates and new perspectives arising from its members. The EU-ROS consortium comprised more than 140 active members who worked together for four years on the topics briefly described below. The formation of reactive oxygen and nitrogen species (RONS) is an established hallmark of our aerobic environment and metabolism but RONS also act as messengers via redox regulation of essential cellular processes. The fact that many diseases have been found to be associated with oxidative stress established the theory of oxidative stress as a trigger of diseases that can be corrected by antioxidant therapy. However, while experimental studies support this thesis, clinical studies still generate controversial results, due to complex pathophysiology of oxidative stress in humans. For future improvement of antioxidant therapy and better understanding of redox-associated disease progression detailed knowledge on the sources and targets of RONS formation and discrimination of their detrimental or beneficial roles is required. In order to advance this important area of biology and medicine, highly synergistic approaches combining a variety of diverse and contrasting disciplines are needed.

Hyperglycemia associated with inflammation and oxidative stress is a major cause of vascular dysfunction and cardiovascular disease in diabetes. Recent data reports that a selective sodium-glucose co-transporter 2 inhibitor (SGLT2i), empagliflozin (Jardiance®), ameliorates glucotoxicity via excretion of excess glucose in urine (glucosuria) and significantly improves cardiovascular mortality in type 2 diabetes mellitus (T2DM). The overarching hypothesis is that hyperglycemia and glucotoxicity are upstream of all other complications seen in diabetes. The aim of this study was to investigate effects of empagliflozin on glucotoxicity, β-cell function, inflammation, oxidative stress and endothelial dysfunction in Zucker diabetic fatty (ZDF) rats. Male ZDF rats were used as a model of T2DM (35 diabetic ZDF‐Leprfa/fa and 16 ZDF-Lepr+/+ controls). Empagliflozin (10 and 30 mg/kg/d) was administered via drinking water for 6 weeks. Treatment with empagliflozin restored glycemic control. Empagliflozin improved endothelial function (thoracic aorta) and reduced oxidative stress in the aorta and in blood of diabetic rats. Inflammation and glucotoxicity (AGE/RAGE signaling) were epigenetically prevented by SGLT2i treatment (ChIP). Linear regression analysis revealed a significant inverse correlation of endothelial function with HbA1c, whereas leukocyte-dependent oxidative burst and C-reactive protein (CRP) were positively correlated with HbA1c. Viability of hyperglycemic endothelial cells was pleiotropically improved by SGLT2i. Empagliflozin reduces glucotoxicity and thereby prevents the development of endothelial dysfunction, reduces oxidative stress and exhibits anti-inflammatory effects in ZDF rats, despite persisting hyperlipidemia and hyperinsulinemia. Our preclinical observations provide insights into the mechanisms by which empagliflozin reduces cardiovascular mortality in humans (EMPA-REG trial).

ObjectiveIn diabetes, vascular dysfunction is characterized by impaired endothelial function due to increased oxidative stress. Empagliflozin, as a selective sodium-glucose co-transporter 2 inhibitor (SGLT2i), offers a novel approach for the treatment of type 2 diabetes by enhancing urinary glucose excretion. The aim of the present study was to test whether treatment with empagliflozin improves endothelial dysfunction in type I diabetic rats via reduction of glucotoxicity and associated vascular oxidative stress.MethodsType I diabetes in Wistar rats was induced by an intravenous injection of streptozotocin (60 mg/kg). One week after injection empagliflozin (10 and 30 mg/kg/d) was administered via drinking water for 7 weeks. Vascular function was assessed by isometric tension recording, oxidative stress parameters by chemiluminescence and fluorescence techniques, protein expression by Western blot, mRNA expression by RT-PCR, and islet function by insulin ELISA in serum and immunohistochemical staining of pancreatic tissue. Advanced glycation end products (AGE) signaling was assessed by dot blot analysis and mRNA expression of the AGE-receptor (RAGE).ResultsTreatment with empagliflozin reduced blood glucose levels, normalized endothelial function (aortic rings) and reduced oxidative stress in aortic vessels (dihydroethidium staining) and in blood (phorbol ester/zymosan A-stimulated chemiluminescence) of diabetic rats. Additionally, the pro-inflammatory phenotype and glucotoxicity (AGE/RAGE signaling) in diabetic animals was reversed by SGLT2i therapy.ConclusionsEmpagliflozin improves hyperglycemia and prevents the development of endothelial dysfunction, reduces oxidative stress and improves the metabolic situation in type 1 diabetic rats. These preclinical observations illustrate the therapeutic potential of this new class of antidiabetic drugs.