Síndrome de quilomicronemia familiar: primer caso reportado en Ecuador / Familial chylomicronemia syndrome: The first case reported in Ecuador

El síndrome de quilomicronemia familiar (SQF) es una entidad genética de herencia autosómica recesiva. Las mutaciones en genes (como APOC2, APOAV, LMF-1, GPIHBP-1) que codifican para proteínas que regulan la maduración, transporte o polimerización de lipoproteína lipasa-1 son las causas más comunes, pero no las únicas. El objetivo de este estudio fue reportar el primer caso documentado en el Ecuador.Caso clínico: hombre de 38 años que presentó hepatoesplenomegalia crónica, trombocitopenia, atrofia pancreática e hipertrigliceridemia severa refractaria al tratamiento. Se realizó un análisis molecular por secuenciación de nueva generación que determinó una deficiencia de lipoproteína lipasa OMIM #238600 en homocigosis. La confirmación genética es necesaria a fin de poder establecer la etiología de HTGS para un adecuado manejo de esta patología.(AU)

Familial chylomicronemia syndrome (FCS) is a genetic entity with autosomal recessive inheritance. Mutations in genes (such as APOC2, APOAV, LMF-1, GPIHBP-1) that code for proteins that regulate the maturation, transport, or polymerization of lipoprotein lipase-1 are the most common causes, but not the only ones. The objective of this study was to report the first documented case in Ecuador.Clinical caseA 38-year-old man presented with chronic hepatosplenomegaly, thrombocytopenia, pancreatic atrophy, and severe hypertriglyceridemia refractory to treatment. A molecular analysis was performed by next generation sequencing that determined a deficiency of Lipoprotein Lipase OMIM #238600 in homozygosis. Genetic confirmation is necessary in order to establish the etiology of HTGS for an adequate management of this pathology.(AU)

Familial chylomicronemia syndrome: The first case reported in Ecuador. / Síndrome de quilomicronemia familiar: primer caso reportado en Ecuador.

Familial chylomicronemia syndrome (FCS) is a genetic entity with autosomal recessive inheritance. Mutations in genes (such as APOC2, APOAV, LMF-1, GPIHBP-1) that code for proteins that regulate the maturation, transport, or polymerization of lipoprotein lipase-1 are the most common causes, but not the only ones. The objective of this study was to report the first documented case in Ecuador. CLINICAL CASE: A 38-year-old man presented with chronic hepatosplenomegaly, thrombocytopenia, pancreatic atrophy, and severe hypertriglyceridemia refractory to treatment. A molecular analysis was performed by next generation sequencing that determined a deficiency of Lipoprotein Lipase OMIM #238600 in homozygosis. Genetic confirmation is necessary in order to establish the etiology of HTGS for an adequate management of this pathology.

Triglyceride metabolism and classification of hypertriglyceridemias. / Metabolismo de los triglicéridos y clasificación de las hipertrigliceridemias.

Triglycerides (TG) are the most important molecules for the energy reserve of our body. After their hepatic or intestinal synthesis from fatty acids, they are carried by chylomicrons (QM (intestinal origin) or VLDL (hepatic origin) in plasma. Their catabolism is determined by the action of the lipoprotein lipase protein complex (LPL) and the hepatic receptors (RLDL and LRP-1) are responsible for their clearance are. Changes in the production or catabolism leads to hypertriglyceridaemia (HTG). The HTG are classified according to severity as, mild-moderate (150-885mg/dl), severe (>885mg/dl), or very severe (>1770mg/dl). They can be primary and secondary depending on origin. In the main primary form is highlighted Familial Chylomicronaemia Syndrome (CFS), a very severe form due to mutations in the LPL gene or associated proteins. Most HTG are due to a combination of genetic and environmental predisposing factors.

Lipid metabolism and classification of hyperlipaemias. / Metabolismo lipídico y clasificación de las hiperlipemias.

This chapter summarises, and updates, lipid metabolism. Both pathways, exogenous metabolisms route via the chylomicrons, and the endogenous pathway of very low-density lipoproteins (VLDL) and low-density lipoproteins (LDL). The reverse cholesterol metabolism will also be mentioned. It also includes the current classification of hyperlipidaemias or hyperlipoproteinaemias, with a reminder of the phenotype classification, and further developments of the aetiological classification. Both parts have updated references, with which knowledge of this vast subject can be expanded.

Rol del enterocito en la dislipidemia de la diabetes mellitus tipo 2 / Role of the enterocyte in type 2 diabetes mellitus associated dyslipidemia

En la diabetes mellitus tipo 2 el aumento en la producción de quilomicrón en el estado post-prandial se asocia a mayor riesgo cardiovascular. La evidencia actual posiciona al enterocito como actor principal en la dislipemia de la diabetes mellitus tipo 2 debido a que aumenta la producción de apolipoproteína B-48 en respuesta a una elevación de ácidos grasos libres y glucosa. El metabolismo del quilomicrón se encuentra regulado por múltiples factores independientes además de la ingesta de grasa alimentaria. Entre estos factores se destacan las hormonas intestinales, como el péptido similar al glucagón tipo 1 que disminuye la producción de apolipoproteína B-48 y el péptido similar al glucagón tipo 2 que la aumenta. Por otro lado, la insulina inhibe de forma aguda la producción de quilomicrón en el sujeto sano mientras que en la diabetes mellitus tipo 2, este efecto está ausente. La comprensión de los factores reguladores emergentes de la secreción de quilomicrón permite vislumbrar nuevos mecanismos de control en su metabolismo y aportar estrategias terapéuticas focalizadas en la hiperlipidemia posprandial en la diabetes mellitus tipo 2 con la reducción del riesgo cardiovascular.

In type 2 diabetes mellitus there is an overproduction of chylomicron in the postprandial state that is associated with increased cardiovascular risk. Current evidence points out a leading role of enterocyte in dyslipidemia of type 2 diabetes mellitus, since it increases the production of apolipoprotein B-48 in response to a raise in plasma free fatty acids and glucose. The chylomicron metabolism is regulated by many factors apart from ingested fat, including hormonal and metabolic elements. More recently, studies about the role of gut hormones, have demonstrated that glucagon-like peptide-1 decreases the production of apolipoprotein B-48 and glucagon-like peptide-2 enhances it. Insulin acutely inhibits intestinal chylomicron production in healthy humans, whereas this acute inhibitory effect on apolipoprotein B-48 production is blunted in type 2 diabetes mellitus. Understanding these emerging regulators of intestinal chylomicron secretion may offer new mechanisms of control for its metabolism and provide novel therapeutic strategies focalized in type 2 diabetes mellitus postprandial hyperlipidemia with the reduction of cardiovascular disease risk.

Lipoproteínas remanentes aterogénicas en humanos / Atherogenic lipoprotein remnants in humans

La lipoproteínas remanentes (RLPs) son el producto de la lipólisis de los triglicéridos transportados por las lipoproteínas de baja densidad (VLDL) de origen hepático e intestinal y de los quilomicrones intestinales. Dicha lipólisis es catalizada por la lipoproteína lipasa y se produce en pasos sucesivos, de manera que los productos son heterogéneos. Su concentración plasmática en ayunas es pequeña en pacientes normolipémicos y aumenta en el estado post-prandial. Las alteraciones genéticas en subtipos de su componente Apo-E aumentan notablemente su concentración plasmática y producen el fenotipo de disbetalipoproteinemia. Se las considera aterogénicas porque injurian el endotelio, sufren estrés oxidativo, son captadas por los macrófagos en el subendotelio vascular y generan las células espumosas que son precursoras de ateromas. Su origen metabólico, como productos de varios tipos de lipoproteínas, explican su estructura heterogénea, sus concentraciones plasmáticas variables y las dificultades metodológicas que dificultan su inclusión en el perfil lipoproteico como parte de los estudios epidemiológicos. Los últimos avances en los estudios metabólicos y la actualización de su papel clínico, justifican una revisión de los conocimientos actuales.

Remnant lipoproteins (RLPs) are the lipolytic product of triglycerides transported by very low density lipoproteins (VLDL) of hepatic and intestinal origin and intestinal chylomicrons. Lipoprotein lipase activity hydrolyse triglycerides in several steps, producing heterogeneous particles. Fasting plasma concentration in normolipidemic subjects is low, but it increases in post-prandial states. Genetic alterations in Apo-E subtypes increases RLPs plasma concentration and produce dyslipoproteinemia phenotype. RLPs atherogenicity depends on their role as endothelial injuring factors, their impaired recognition by lipoprotein receptors, and their susceptibility to oxidative stress. They also promote the circulation of molecular adhesion molecules, the internalization in subendothelial macrophages via scavenger receptors and the accumulation in foam cells, all of them early mechanisms of atheromatosis. RLPs metabolism has been a subject of controversial studies. Their origin from different lipoproteins may explain their structural heterogeneity, therefore increasing the methodological difficulties to include RLPs in the atherogenic lipoprotein profile in the epidemiological studies of the field. Last advances on metabolism of RLPs and their emergent clinical role justifies an up dated revision of RLPs.