FISABIO HOSPITAL UNIVERSITARIO DOCTOR PESET TRANSLATIONAL RESEARCH IN NUTRITION AND METABOLISM

Size: px

Start display at page:

Download "FISABIO HOSPITAL UNIVERSITARIO DOCTOR PESET TRANSLATIONAL RESEARCH IN NUTRITION AND METABOLISM"

Stephany Powers
5 years ago
Views:

1 HOSPITAL UNIVERSITARIO DOCTOR PESET HEAD OF RESEARCH SECTION ANTONIO HERNÁNDEZ MIJARES HERNANDEZ_ CALLE JUAN DE GARAY, / VALENCIA / SPAIN

ROLE OF MITOCHONDRIAL FUNCTION, OXIDATIVE STRESS AND ENDOPLASMIC RE- TICULUM STRESS IN THE DEVELOPMENT OF INSULIN RESISTANCE AND CARDIOVASCU- LAR DISEASE In recent years, the presence of oxidative

2 ROLE OF MITOCHONDRIAL FUNCTION, OXIDATIVE STRESS AND ENDOPLASMIC RE- TICULUM STRESS IN THE DEVELOPMENT OF INSULIN RESISTANCE AND CARDIOVASCU- LAR DISEASE In recent years, the presence of oxidative and endoplasmic reticulum stress has been associated with insulin resistance in the pancreas and in the target tissues of insulin: muscle, liver, and adipose tissue. In the pancreas, mitochondrial activity plays an important role in the release of insulin. In fact, research has shown that insulin secretion is reduced in pancreatic ß-cells with mitochondrial gene defects, evincing that mitochondrial function is crucial for the functioning of these cells and that changes in function contribute to the pathogenesis of type 2 diabetes (Figure 1). Insulin signalling involves a complex cascade network with multiple effectors. It starts when insulin binds its receptor in the target tissue, triggering a cascade in which several proteins are phosphorylated, including IRS proteins, ultimately resulting in the synthesis of glucose transporters and their presentation in the membrane surface. The main hypothesis explaining the development of insulin resistance proposes that the release of free radicals stimulates the proinflammatory cascade, activating JNK, which in turn phosphorylates IRS proteins and inhibits their activity, preventing signalling by insulin receptors. Consistent with this, many studies have found increased oxidative stress in obese patients with insulin resistance in different target tissues, be it muscle, liver or adipose tissue, and this increase correlates with the degree of insulin resistance. In fact, this association between oxidative stress and insulin resistance has not only been described in the pancreas or in tissues targeted by insulin, but our group has also found evidence of oxidative stress and mitochondrial dysfunction in peripheral blood leukocytes of patients with insulin resistance: type 2 diabetes and women with polycystic ovary syndrome. Specifically, we have observed an increased release of free radicals, mostly from complex I of the electron transport chain, associated with a reduction in antioxidant defences. Alterations in leukocyte function have a significant impact not only on the response to infectious agents, but also on the development of atherosclerosis. Leukocyte extravasation is an initial step in the atherogenic process, which is characterised by the formation of a lesion in the tunica intima that progressively occludes the arteriolar lumen. It develops in response to the presence of coronary risk factors, primarily abnormal levels of circulating lipids, which are associated to the production of free radicals and a reduced NO bioavailability. FIGURE 1 In the early stages it is characterised by an inflammatory response with lipid accumulation and increased adhesion of T cells and monocytes/macrophages to epithelial cells in association with elevated levels of adhesion molecules, such as P-selectin, ICAM-1 or VCAM-1 (Figure 2). The leukocyte extravasation process includes various stages. It starts with the initial leukocyte-endothelium interaction that leads to leukocyte rolling and the induction of leu- FUNDACIÓN PARA EL FOMENTO DE LA INVESTIGACIÓN SANITARIA Y BIOMÉDICA DE LA COMUNIDAD VALENCIANA () / AVENIDA DE CATALUÑA, 21 / VALENCIA / SPAIN

3 kocyte activation, which allows a firm adhesion to the endothelium and eventually results in transendothelial migration. In fact, assessment of leukocyte extravasation could provide information on an individual s predisposition to develop atherosclerosis. Several studies have found increased leukocyte-endothelium interactions in diseases associated with insulin resistance, such as polycystic ovary syndrome and type 2 diabetes. There is even evidence that in the latter patients, macrovascular complications such as silent myocardial ischaemia and microvascular complications such as nephropathy are associated with impaired endothelial function, which could contribute to the high vascular risk of these patients. Monocitos: Monocytes Citoquinas: Cytokines LDL: LDL Linfocitos T: T lymphocytes P-selectina: P-selectin Placa: Plaque Formación del trombo: Thrombus formation Daño endothelial: Endothelial damage ROS: ROS LDL oxidadas: Oxidated LDL Células espumosas: Foam cells Factores de crecimiento: Growth factors Apoptosis cellular: Apoptosis Migración y proliferación de células del músculo liso: Smooth muscle cell migration and proliferation. FIGURE 2 OBJECTIVES The main purpose on which we have focused our research activity is elucidating the role of endoplasmic reticulum (ER) stress and mitochondrial and endothelial dysfunction in the mechanisms that underlie insulin resistance in pathologies associated with type 2 diabetes, obesity and polycystic ovary syndrome, and their association with the risk of cardiovascular disease. We also evaluate potential therapeutic targets that could help understand the mechanism and source of ER stress in different cell models (ex vivo and in vitro), opening new lines of research in the search for alternative therapies. On the other hand, we are developing several projects that focus on new and emerging methods and technologies for the study of the efficacy of functional foods with health-promoting properties and for reducing the risk of chronic pathologies. 03 FUNDACIÓN PARA EL FOMENTO DE LA INVESTIGACIÓN SANITARIA Y BIOMÉDICA DE LA COMUNIDAD VALENCIANA () / AVENIDA DE CATALUÑA, 21 / VALENCIA / SPAIN

4 AREAS OF RESEARCH The areas of research that are currently active are the following: AREA 1. Pathophysiology of polycystic ovary syndrome and its relationship with insulin resistance and cardiovascular disease. This area of research focuses on determining the significance of endoplasmic reticulum (ER) stress in the pathogenesis of polycystic ovary syndrome (PCOS), delving into the analysis of the underlying mechanisms associated to insulin resistance that are the root of the comorbidities in this syndrome. Also, and more specifically, we propose that treatment with insulin-sensitising agents could improve ER stress markers in these patients. In this past year, we have demonstrated that while the diagnosis of PCOS in thin women does not seem to increase the risk of cardiovascular disease, when it is associated with obesity it tends to result in a worsening of lipid profiles characterised by the presence of atherogenic dyslipidaemia and altered HDL subfraction distributions. AREA 2. Morbid obesity: pathophysiology, comorbidities and treatment. The main objective of this area is to determine the role of ER stress and mitochondrial dysfunction in the pathogenesis of obesity, thoroughly analysing the mechanisms underlying inflammation that give rise to the associated metabolic diseases. More specifically, we aim to explore whether weight loss achieved by dietary measures or bariatric surgery can improve markers of ER stress and mitochondrial function, and therefore inflammatory parameters. Furthermore, for this pathology we have evaluated the association between RBP4 levels and different parameters of lipid and carbohydrate metabolism in individuals with morbid obesity and different degrees of insulin resistance. Thus far, our results show that in patients with morbid obesity, systemic RBP4 levels seem to play a role in lipid metabolism, increasing triglyceride levels and contributing to the formation of small HDL particles. Principal investigator: Milagros Rocha Barajas. AREA 3. Diabetes Mellitus, mitochondrial dysfunction and macrovascular and microvascular complications: pathophysiological and therapeutic implications. We intend to evaluate the link between mitochondrial dysfunction and the development of type 2 diabetes and its physiopathological and clinical implications. In the past year, we have demonstrated that there is a correlation between mitochondrial dysfunction and leukocyte-endothelium interactions in diabetic patients. This correlation was more pronounced in patients with silent myocardial ischaemia (SMI). At the same time, we have proven that there is a direct correlation between the presence of diabetic nephropathy, leukocyte-endothelium interactions and the levels of myeloperoxidase. Thus, we have identified myeloperoxidase as a fundamental target for the treatment of diabetic nephropathy. Principal investigator: Víctor M. Víctor González. AREA 4. Functional foods: impact on cardiovascular risk. The objective of this research area is to assess whether consumption of a new natural and functional ingredient (containing 4 g of pinitol, the active ingredient under study) could lower postprandial serum glucose levels both in healthy individuals and in patients with diabetes or with abnormal baseline and postprandial glucose levels. This would achieve a reduction of the associated oxidative stress, and improved endothelial function and a delay or resolution of atherosclerotic processes. This year we have published the results of the first phase of the trial, in which we evaluated the effects following acute ingestion of different doses of the product (containing 2.5, 4.0 and 6.0 g of the bioactive compound) on 04 FUNDACIÓN PARA EL FOMENTO DE LA INVESTIGACIÓN SANITARIA Y BIOMÉDICA DE LA COMUNIDAD VALENCIANA () / AVENIDA DE CATALUÑA, 21 / VALENCIA / SPAIN

5 glucose tolerance and insulin sensitivity in the healthy population, which allowed us to identify the appropriate dose for the second phase of the trial, in which the product will be administered for 12 weeks. AREA 5. Nanomedicine in Type 2 Diabetes: pathophysiology and clinical implications. The main objectives of this area of research are studying the performance, optimization and application of several nanoscale materials for the reduction of oxidative stress caused by mitochondrial dysfunction in type 2 diabetes. Specifically, we want to design and study different new types of nanomaterials, known as composites, for internalization by the leukocytes of patients with type 2 diabetes without toxic effects and which can interact with or be internalized by their mitochondria in order to: 1) reduce and regulate the excess of oxidative species that occurs in oxidative stress, that is, to use them as a new therapy; 2) be able to quantify the levels of oxidative species, that is, for diagnosis. Finally, once nanomaterials have been perfected to optimise their function at the cellular level, we will conduct studies in a model of hyperglycaemia and type 2 diabetes in Zuker fa/fa rats to study their pharmacokynetics and pharmacodynamics with the following objectives: 1) accumulation of nanomaterials in their targets (mitochondria and key organs) producing beneficial effects, with reduction of oxidative stress. To this end, we will assess the effects of various nanomaterials with different directing agents; 2) rapid path for their secretion outside the body without producing any adverse effects. Principal investigator: Víctor M. Víctor González. AREA 6. Study of the prevalence of malnutrition and its associated molecular mechanisms. The purpose of the current line of research is twofold: to determine the prevalence of malnutrition in the health care setting (hospital and primary care) comparing three different screening tools for malnutrition, and to assess the discriminative value of different biochemical markers used in the diagnosis of malnutrition. We will determine the association between markers of oxidative stress and leukocyte-endothelium interactions with the state of malnutrition, and study endoplasmic reticulum (ER) stress as a phenomenon associated to the inflammatory process. The knowledge and understanding of the reasons why there is mitochondrial dysfunction and increased ER stress in malnutrition, along with an acceleration of inflammatory processes, will be essential for the identification of therapeutic targets and understanding the mechanisms involved in this pathology. 05 RESEARCH GROUP DEPARTMENT OF ENDOCRINOLOGY & NUTRITION HOSPITAL UNIVERSITARIO DOCTOR PESET EDIFICIO CONSULTAS EXTERNAS CALLE JUAN DE GARAY, / VALENCIA T. LABORATORY (BASEMENT): T. OUTPATIENT CLINIC (2ND FLOOR): HEAD OF RESEARCH SECTION ANTONIO HERNÁNDEZ MIJARES HERNANDEZ_ANTMIJ@GVA.ES FOR MORE INFORMATION ON S ACTIVITIES AND SERVICES: W..SAN.GVA.ES / T / GROUP MEMBERS VÍCTOR M VÍCTOR GONZÁLEZ VMVIKTOR@GMAIL.COM MILAGROS ROCHA BARAJAS MILAGROS.ROCHA@UV.ES CELIA BAÑULS MORANT CELIA.BANULS@UV.ES SUSANA ROVIRA LLOPIS SUROLLO@ALUMNI.UV.ES SANDRA LÓPEZ DOMÉNECH SANDRLOPEZ@UV.ES NOELIA DIAZ MORALES NODIAZMO@ALUMNI.UV.ES ROSA FALCÓN TAPIADOR ROSAFALCON@GMAIL.COM RAQUEL CASTELLÓ PONS RAQUELCP@GMAIL.COM EVA SOLÁ IZQUIERDO EVA.SOLA@UV.ES CARLOS MORILLAS ARIÑO CARLOS.MORILLAS@UV.ES MARCELINO GÓMEZ BALAGUER MARCELINOHOSPITAL@GMAIL.COM SILVIA VESES MARTÍN SVESESM@GMAIL.COM ANA JOVER FERNÁNDEZ AJOFER@ALUMNI.UV.ES ICIAR CASTRO DE LA VEGA ICIARCV@GMAIL.COM NURIA MONZÓ ALBIACH NURIAMONZO@GMAIL.COM JOSE F MARCO EXPÓSITO FUNDACIÓN PARA EL FOMENTO DE LA INVESTIGACIÓN SANITARIA Y BIOMÉDICA DE LA COMUNIDAD VALENCIANA () / AVENIDA DE CATALUÑA, 21 / VALENCIA / SPAIN THE ELABORATION OF THIS DOCUMENT HAS BEEN FUNDED BY THE PROJECT AFI-01/14, IN THE CONTEXT OF THE GRANTS FOR PARTICIPATION IN EUROPEAN COMMISSION RESEARCH PROGRAMMES ON HEALTH GIVEN BY THE CONSELLERIA DE SANITAT UNIVERSAL I SALUT PÚBLICA OF THE GOVERNMENT OF VALENCIA FOR THE FISCAL PERIOD.

1Why lipids cannot be transported in blood alone? 2How we transport Fatty acids and steroid hormones?

1Why lipids cannot be transported in blood alone? 2How we transport Fatty acids and steroid hormones? 3How are dietary lipids transported? 4How lipids synthesized in the liver are transported? 5 Lipoprotien