Imágenes en obesidad: contribuyendo a un entendimiento más profundo de la enfermedad / Imaging in obesity: contributing to a deeper understanding of the disease

Resumen: la obesidad constituye un problema mayor de salud pública relevante en la actualidad, considerando que cumple un doble rol al actuar como factor de riesgo para la mayoría de las enfermedades crónicas no transmisibles y constituir una entidad nosológica independiente. Los estudios de imágenes han contribuido, desde diferentes perspectivas, a dilucidar los mecanismos propios de la enfermedad, sus complicaciones, progresión, mecanismos cognitivos involucrados y respuesta a diversos esquemas terapéuticos. El objetivo del presente artículo es proveer de una visión general respecto a cómo los estudios imagenológicos, especialmente basados en resonancia magnética, han profundizado la comprensión de los mecanismos metabólicos y neurocognitivos, relacionados, así como elementos vinculados al tratamiento. Adicionalmente se discuten posibles direcciones futuras en este campo.

Abstract: Obesity constitutes a relevant issue in public health. It acts both like a risk factor for most of the non-communicable diseases and as an independent nosologic entity. The imaging studies have contributed, from several perspectives, to elucidate the underlying mechanisms of the disease. its complications, progression, involved cognitive phenomena and the response to different therapeutic approaches. The objective of this article is to provide a global view about how the imaging studies, particularly those based on magnetic resonance imaging, have given a deeper comprehension of the related metabolic and cognitive mechanisms and some facts related to the treatment. Additionally, future directions of this field are discussed.

Impairment of Angiogenic Sphingosine Kinase-1/Sphingosine-1-Phosphate Receptors Pathway in Preeclampsia.

Preeclampsia (PE), is a serious pregnancy disorder characterized in the early gestation by shallow trophoblast invasion, impaired placental neo-angiogenesis, placental hypoxia and ischemia, which leads to maternal and fetal morbidity and mortality. Here we hypothesized that angiogenic sphingosine kinase-1 (SPHK1)/sphingosine-1-phosphate (S1P) receptors pathway is impaired in PE. We found that SPHK1 mRNA and protein expression are down-regulated in term placentae and term chorionic villous explants from patients with PE or severe PE (PES), compared with controls. Moreover, mRNA expression of angiogenic S1PR1 and S1PR3 receptors were decreased in placental samples of PE and PES patients, whereas anti-angiogenic S1PR2 was up-regulated in chorionic villous tissue of PES subjects, pointing to its potential atherogenic and inflammatory properties. Furthermore, in in vitro (JAR cells) and ex vivo (chorionic villous explants) models of placental hypoxia, SPHK1 mRNA and protein were strongly up-regulated under low oxygen tension (1% 02). In contrast, there was no change in SPHK1 expression under the conditions of placental physiological hypoxia (8% 02). In both models, nuclear protein levels of HIF1A were increased at 1% 02 during the time course, but there was no up-regulation at 8% 02, suggesting that SPHK1 and HIF1A might be the part of the same canonical pathway during hypoxia and that both contribute to placental neovascularization during early gestation. Taken together, this study suggest the SPHK1 pathway may play a role in the human early placentation process and may be involved in the pathogenesis of PE.

Placental Aromatase Is Deficient in Placental Ischemia and Preeclampsia.

INTRODUCTION: Preeclampsia is a maternal hypertensive disorder with uncertain etiology and a leading cause of maternal and fetal mortality worldwide, causing nearly 40% of premature births delivered before 35 weeks of gestation. The first stage of preeclampsia is characterized by reduction of utero-placental blood flow which is reflected in high blood pressure and proteinuria during the second half of pregnancy. In human placenta androgens derived from the maternal and fetal adrenal glands are converted into estrogens by the enzymatic action of placental aromatase. This implies that alterations in placental steroidogenesis and, subsequently, in the functionality or bioavailability of placental aromatase may be mechanistically involved in the pathophysiology of PE. METHODS: Serum samples were collected at 32-36 weeks of gestation and placenta biopsies were collected at time of delivery from PE patients (n = 16) and pregnant controls (n = 32). The effect of oxygen tension on placental cells was assessed by incubation JEG-3 cells under 1% and 8% O2 for different time periods, Timed-mated, pregnant New Zealand white rabbits (n = 6) were used to establish an in vivo model of placental ischemia (achieved by ligature of uteroplacental vessels). Aromatase content and estrogens and androgens concentrations were measured. RESULTS: The protein and mRNA content of placental aromatase significantly diminished in placentae obtained from preeclamptic patients compared to controls. Similarly, the circulating concentrations of 17-ß-estradiol/testosterone and estrone/androstenedione were reduced in preeclamptic patients vs. controls. These data are consistent with a concomitant decrease in aromatase activity. Aromatase content was reduced in response to low oxygen tension in the choriocarcinoma JEG-3 cell line and in rabbit placentae in response to partial ligation of uterine spiral arteries, suggesting that reduced placental aromatase activity in preeclamptic patients may be associated with chronic placental ischemia and hypoxia later in gestation. CONCLUSIONS: Placental aromatase expression and functionality are diminished in pregnancies complicated by preeclampsia in comparison with healthy pregnant controls.