Proyectos

Las micotoxinas son metabolitos producidos por algunos hongos del tipo Aspergillus, Penicillum o Fusarium, contaminantes habituales de alimentos que necesitan secado como granos, frutos secos y condimentos. Las micotoxinas son extremadamente tóxicas y afectan tanto a animales como humanos; las de mayor significancia son la ocratoxina A, aflatoxina, fumonisina, tricotecenos y zearalenona. En términos generales, las micotoxinas al ser ingeridas son absorbidas en el tracto gastrointestinal, metabolizadas en el hígado a través de reacciones de Fase I (oxidación) y Fase II (conjugación), y finalmente excretadas por orina y heces. El principal órgano afectado por la exposición a micotoxinas es el hígado, órgano central del metabolismo, incrementando el tamaño hepático, el estrés oxidativo y modificando los niveles de lisofosfatidilcolina, que puede aumentar la apoptosis a través de la producción de especies reactivas de oxígeno. Además, se ha descrito que algunas de las micotoxinas pueden tener efectos endocrinos, principalmente de tipo estrogénico. La zearalenona (ZEN) es una de las micotoxinas más importantes producidas por Fusarium spp. Los hongos del tipo Fusarium son uno de los más frecuentes encontrados en Chile, y se ve aumentada en condiciones de estrés hídrico. La ZEN es termoestable y no se degrada por el procesamiento. La ZEN es una fusariotoxina estrogénica, es decir se clasifica como un fitoestrógeno o como un micoestrógeno, ya que su estructura química es análoga a la de los estrógenos naturales. Esto permite su unión con los sitios receptores estrogénicos, lo que conduce a una estrogenicidad amplificada. Como resultado, la intoxicación por ZEN conduce con mayor frecuencia a disrupción endocrina y trastornos del sistema reproductivo. Los metabolitos hepáticos pueden tener aun mayor afinidad con los receptores estrogénicos; por ejemplo, el alfa-zearalenol (α-ZEL) es 60 veces más estrogénico que ZEN. Si bien en Chile se han realizado estudios de biomonitoreo de micotoxinas, no existe en la actualidad información sobre la exposición a ZEN y sus metabolitos especialmente en mujeres y sus posibles efectos como disruptores hormonales. En este contexto, existe una condición endocrinometabólica muy prevalente en la población chilena denominada “Síndrome de ovario poliquístico” (SOP), la cual se caracteriza por la presencia de un exceso de hormonas andrógenicas, irregularidad menstrual y morfología de ovarios poliquísticos. Además, las mujeres con SOP poseen un mayor riesgo de desarrollar alteraciones metabólicas como resistencia a la insulina, diabetes tipo 2, síndrome metabólico y enfermedad cardiovascular, impactando su calidad de vida. El estudio de la fisiopatología del SOP es desafiante ya que es una condición muy heterogénea, sin embargo, se ha descrito que el hiperandrogenismo, la disfunción ovulatoria, alteraciones en la pulsatilidad de la hormona liberadora de gonadotrofinas (GnRH) y la resistencia a la insulina, tienen un rol clave en el desarrollo de esta condición. Por otra parte, el exceso de andrógenos incrementa los niveles de insulina y reduce la producción de la globulina transportadora de hormonas sexuales (SHBG) en el hígado, lo que aumenta la circulación de testosterona bioactiva libre. Además, la hiperinsulinemia estimula la síntesis de andrógenos activando la vía de la esteroidogénesis e incrementa estados de inflamación y estrés oxidativo, debido a la disfunción mitocondrial, promoviendo el desarrollo de un círculo vicioso. Sin embargo, la contribución individual de estos factores puede variar entre las pacientes, dando cuenta de la heterogeneidad clínica que se observa en la clínica. Aunque en su etiología se han implicado factores genéticos y de estilo de vida, cada vez hay más pruebas de que la exposición a contaminantes ambientales, incluyendo los disruptores endocrinos, también pueden contribuir significativamente al desarrollo y la fisiopatología del SOP. En este contexto, el rol de las micotoxinas como disruptores endocrinos no ha sido estudiado extensamente en el contexto del SOP, y debido a posibles efectos acumulativos e interacciones sinérgicas entre estos contaminantes, se requiere evaluar su potencial impacto en la fisiopatología del SOP. En particular, se ha considerado que las micotoxinas con actividad estrogénica, como la zearalenona, podrían influir en el equilibrio hormonal de las mujeres y potencialmente contribuir al desarrollo o exacerbación del SOP. De esta manera, el objetivo general de esta propuesta es evaluar los niveles circulantes de ZEN y sus metabolitos como posibles factores de riesgo dietarios, y determinar su posible asociación con alteraciones endocrinometabólicas en mujeres chilenas con SOP. Este objetivo será abordado mediante un estudio clínico en mujeres chilenas y un estudio in vitro. La investigación propuesta aportará información valiosa y novedosa sobre cómo factores dietarios contribuyen al desarrollo y severidad del SOP, abriendo nuevas vías para la comprensión y manejo de esta condición. Finalmente, esta propuesta se enmarca dentro del objetivo de vincular el ICA3 y el Instituto de Ciencias de la Salud, contribuyendo al objetivo estratégico de la Universidad de consolidar los Institutos de Investigación mediante la colaboración estrecha e interdisciplinaria. Más aún, el estudio aportará con formación de estudiantes de ambos institutos, la divulgación y difusión de los resultados del proyecto.

EPIGENOMIC PROGRAMMING IN THE EARLY FETAL BLOOD-BRAIN BARRIER BY GESTATIONAL HYPOXIA: CONSEQUENCES FOR THE NEURO-ENDOTHELIAL LIFESPAN.

Frailty is increasingly becoming an important public health challenge worldwide because it is associated with older age, and with adverse outcomes such as reduced quality of life, increased mortality rates, hospitalizations, falls, depression, and dementia. Frailty is defined as dynamic state affecting an individual who experiences losses in one or more domains of human functioning (physical, psychological, social) that are caused by the influence of a range of variables, and which increases the risk of adverse outcomes. This more integral conceptual definition promotes the collaboration of scientists, social and behavioral professionals as well as clinicians from diverse specialties. In this proposal an interdisciplinary group (Biochemistry, Geriatric, Occupational Therapist, Kinesiologist, social worker, bioengineer, statistician among others) aims to evaluate frailty in Chile with a biopsychosocial approach with the final purpose to identify and manage frailty while taking into consideration all the dimensions. Additionally, we aim to design a multidomain personalized person-base intervention for a healthy aging that can uncover a circulating microRNA biomarker panel that can allow an early-detection of frailty, leading to a new multidimensional geriatric assessment. We propose the following hypothesis: A personalized multidimensional training program reduces the frailty prevalence, increasing adherence and participation in the program among community-living older adults. This intervention will be paralleled by a distinctive miRNA profile reflecting the multiple domains of frailty, as well as improvements in diverse psychosocial traits.

Frailty is increasingly becoming an important public health challenge worldwide because it is associated with older age, and with adverse outcomes such as reduced quality of life, increased mortality rates, hospitalizations, falls, depression, and dementia. Frailty is defined as dynamic state affecting an individual who experiences losses in one or more domains of human functioning (physical, psychological, social) that are caused by the influence of a range of variables, and which increases the risk of adverse outcomes. This more integral conceptual definition promotes the collaboration of scientists, social and behavioral professionals as well as clinicians from diverse specialties. In this proposal an interdisciplinary group (Biochemistry, Geriatric, Occupational Therapist, Kinesiologist, social worker, bioengineer, statistician among others) aims to evaluate frailty in Chile with a biopsychosocial approach with the final purpose to identify and manage frailty while taking into consideration all the dimensions. Additionally, we aim to design a multidomain personalized person-base intervention for a healthy aging that can uncover a circulating microRNA biomarker panel that can allow an early-detection of frailty, leading to a new multidimensional geriatric assessment. We propose the following hypothesis: A personalized multidimensional training program reduces the frailty prevalence, increasing adherence and participation in the program among community-living older adults. This intervention will be paralleled by a distinctive miRNA profile reflecting the multiple domains of frailty, as well as improvements in diverse psychosocial traits.

Analizar los procesos de enseñanza, integración curricular, evaluación y acreditación en carreras del área de salud en grado y posgrado y su relación con la trayectoria académica de los estudiantes y la actividad docente en Argentina y Chile.

The proposal focuses on understanding the neuro-vascular aging mechanisms associated with alterations in fetal growth by intrauterine hypoxia using molecular biology and physiology as an area. The aim of the study is to demonstrate that impaired fetal growth conditions are associated with epigenetic programming of aging-related DNA methylation, chromatin remodeling, and miRNA-omic profile of junctional complex genes in the neuroendothelium, which can alter BBB integrity and permeability, increasing cerebral damage which impacts the juvenile and adulthood neurocognitive function.

Analizar los procesos de enseñanza, integración curricular, evaluación y acreditación en carreras del área de salud en grado y posgrado y su relación con la trayectoria académica de los estudiantes y la actividad docente en Argentina y Chile.

The brain is an energy intensive organ that requires a robust supply of nutrients and oxygen. The vasculature irrigating the brain is a huge and complex network of blood vessels fulfilling this requirement, while also protecting the neural tissue from blood-borne toxic substances. This regulated nutrient supply is accomplished by the formation of a highly selective molecular barrier, termed the blood-brain barrier (BBB). Dysfunction of the BBB or malformations of the vascular network are associated with pathological conditions that impair brain function, and can lead to death. Thus, appropriate morphogenesis and establishment of the brain vasculature is necessary for a healthy life. The brain vasculature forms during intrauterine development, matching brain growth in this same period. Anatomically, blood vessels grow first surrounding the brain primordium and then penetrate the parenchyma until they vascularize the periventricular zone. The molecular regulation of this patterned growth is not completely understood. Several signaling pathways are known to be involved in brain angiogenesis, including WNT, TGF-β, Hh, and NOTCH, which differentially regulate vascular growth. Recently, cholesterol has been shown to modulate angiogenic growth in other vascular beds by regulating the activity of the NOTCH pathway, suggesting that cholesterol levels could influence developmental angiogenesis in the brain. Interestingly, cholesterol is also required for signal transduction of the Hh pathway. In preliminary in vitro experiments, we have observed that brain endothelial cells activate an angiogenic program after cholesterol depletion. Here, we will extend those studies to in vivo models to determine the role of cholesterol in developmental brain angiogenesis. We propose that an increase in vascular cell cholesterol activates NOTCH and attenuates Hh signaling pathways, restricting sprouting angiogenesis and blood-brain barrier formation in mouse embryo brain vasculature. To test this hypothesis, we will study mouse embryos with altered cholesterol levels by dietary, pharmacological, and genetic manipulations. We expect these manipulations to induce a reduction or an increase in cholesterol levels in the brain vasculature during embryonic development, which we will evaluate by measuring cholesterol content in isolated vascular fragments. In all these models, we will (Specific aim 1) study vascularization in the brain during intrauterine development using immunofluorescence with specific antibodies against endothelium proteins. In addition, we will measure the levels of transcript and proteins of general key regulators of angiogenesis in isolated vascular fragments, using qPCR and Western blot. We will (Specific aim 2) also evaluate the state of the BBB in the brain vasculature of these models at a fetal stage when the barrier is already formed and functional. For this, we will use immunofluorescence to detect the presence of marker proteins of the BBB in vascular fragments, and we will measure their levels by Western blot. Further, we will test the functionality of the barrier by injecting a fluorescent tracer and evaluating its extravasation in the brain. Finally, we will (Specific aim 3) determine the activation of the NOTCH and Hh pathways in the brain vasculature of the models at the stage of maximal angiogenesis. We will use qPCR and Western blot to measure the levels of marker genes and proteins for these two pathways in vascular fragments, and Proximity Ligation In Situ Hybridization in tissue sections to evaluate the transcript levels of those markers in situ. We expect that the different models of dietary, pharmacological, and genetic interventions will increase or reduce cholesterol levels in the brain vasculature. These changes are expected to correlate with opposing effects on angiogenesis in the brain during development (i.e. low cholesterol will increase angiogenesis, while high cholesterol will inhibit it). In the same way, we expect that distinct cholesterol levels will have opposing effects on the integrity of the BBB. These changes in angiogenesis and BBB function are expected to be associated with concomitant disruption of the NOTCH and Hh pathways. In summary, in this proposal we aim to cover a knowledge gap regarding the role of cholesterol in the regulation of developmental angiogenesis in the brain. These experiments may uncover new mechanisms driving vascular growth and barrier establishment in the brain, which could lead to new strategies for the prevention and treatment of pathologies involving the brain vasculature.

Non-communicable diseases (NCDs) are responsible for 74% of worldwide human deaths, with cardiovascular causes in the first place (1). NCDs are determined by a combination of environmental, genetic and epigenetic factors. In fact, adverse intrauterine conditions, such as reduced oxygen availability (hypoxia) and oxidative stress, can increase the risk of developing diseases during life, a phenomenon known as Fetal Programming or Developmental Origins of Health and Disease (DOHaD). Intrauterine hypoxia (IUH) affects most of the pregnancies in high altitudes populations (> 2500m) (2-4) and 3-4% in lowlands, with uteroplacental and developmental complications (4,5). We, and a couple of others, have recently shown that IUH determines cardiovascular oxidative stress during lifespan affecting endothelial function and vasodilator capacity, similar to what is seen with aging. The hypoxia-induced responses during development are responsible for fetal survival, but also determine mechanisms that program postnatal cardiovascular function that may increase cardiovascular health risks and accelerate aging (6). This proposal aims to determine the mechanisms and trace the origins and outcomes of cardiovascular dysfunction resulting from intrauterine hypoxia and oxidative stress, and further identify the interrelated senescence mechanisms in the heart and blood vessels. To assess the aforementioned, we will study the effects of IUH on cardiovascular aging along lifespan, as important regulators of the function, structure and biomechanical properties of the cardiovascular system.

Non-communicable diseases (NCDs) are responsible for 74% of worldwide human deaths, with cardiovascular causes in the first place (1). NCDs are determined by a combination of environmental, genetic and epigenetic factors. In fact, adverse intrauterine conditions, such as reduced oxygen availability (hypoxia) and oxidative stress, can increase the risk of developing diseases during life, a phenomenon known as Fetal Programming or Developmental Origins of Health and Disease (DOHaD). Intrauterine hypoxia (IUH) affects most of the pregnancies in high altitudes populations (> 2500m) (2-4) and 3-4% in lowlands, with uteroplacental and developmental complications (4,5). We, and a couple of others, have recently shown that IUH determines cardiovascular oxidative stress during lifespan affecting endothelial function and vasodilator capacity, similar to what is seen with aging. The hypoxia-induced responses during development are responsible for fetal survival, but also determine mechanisms that program postnatal cardiovascular function that may increase cardiovascular health risks and accelerate aging (6). This proposal aims to determine the mechanisms and trace the origins and outcomes of cardiovascular dysfunction resulting from intrauterine hypoxia and oxidative stress, and further identify the interrelated senescence mechanisms in the heart and blood vessels. To assess the aforementioned, we will study the effects of IUH on cardiovascular aging along lifespan, as important regulators of the function, structure and biomechanical properties of the cardiovascular system.