[Increased iron store and its relationship with cardiovascular disease]. / Aumento de los depósitos de hierro y su relación con la enfermedad cardiovascular.

In the last years, great advance has been achieved in the control of several of the classic atherogenic risk factors; nonetheless, the incidence of cardiovascular disease (CVD) still remains high. Among the disorders which are associated with CVD, increased iron stores have been described as one of them. Its study gained relevance since the "iron hypothesis", which postulates that low iron levels exert a protective effect on cardiovascular system, was elaborated. In spite of the numerous studies carried out to test this hypothesis, the results have been controversial. On the other hand, much knowledge regarding iron metabolism has been gained since the description of the regulatory hormone, hepcidin. The studies on hepcidin physiologic functions allowed the elaboration of new hypothesis that could explain the results formerly conceived as inconsistent. The aim of the present review is to describe, in light of the newest advances in iron metabolism regulation and its association with inflammation, the current state of knowledge regarding the possible role of iron overload as a risk factor of CVD.

[Atherogenic lipoprotein remnants in humans]. / Lipoproteínas remanentes aterogénicas en humanos.

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.

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.

A functional nonsynonymous toll-like receptor 4 gene polymorphism is associated with metabolic syndrome, surrogates of insulin resistance, and syndromes of lipid accumulation.

Toll-like receptor 4 (TLR4) plays a key role in the activation of innate immune responses. Loss-of-function mutations in TLR4 prevent diet-induced obesity and insulin resistance (IR). We conducted a population cross-sectional study to evaluate whether Asp299Gly (rs4986790) TLR4 gene polymorphism is associated with metabolic syndrome (MS), surrogates of IR, and syndromes of lipid accumulation (SLAs) in Argentinean healthy male subjects. rs4986790 was genotyped in 621 healthy unrelated male blood donors. National Cholesterol Education Program/Adult Treatment Panel III-MS (NCEP/ATP III-MS); SLAs such as enlarged waist elevated triglyceride syndrome (EWET), hypertriglyceridemic waist (HW), and overweight-lipid syndrome (OLS); and surrogates of IR were assessed. The prevalence of MS, OLS, and EWET was significantly higher among Asp299Asp carriers (P < .05). These findings were confirmed using 32 000 bootstrap samples. Surrogate markers of IR were also significantly higher in Asp299Asp carriers (P < .05). Most findings were especially strengthened among individuals with C-reactive protein below the 95th percentile and/or total cholesterol to high-density lipoprotein cholesterol ratio >or=5. This is the first report to find, in Argentinean healthy male blood donors, associations between the Asp299Asp genotype of rs4986790 TLR4 gene polymorphism and high risk for NCEP/ATP III-MS, SLAs, and surrogates of IR. These findings are consistent with previous functional and observational studies showing that Asp299 allele, in comparison with Gly299, is associated with increased TLR4 activation, higher levels of inflammatory cytokines, acute-phase reactants and soluble adhesion molecules, and higher risk of atherosclerosis.

Proatherogenic disturbances in lipoprotein profile, associated enzymes and transfer proteins in women with iron deficiency anaemia.

OBJECTIVE: To characterize the lipid-related atherogenic risk factors in iron deficiency anaemia (IDA) patients. DESIGN AND METHODS: Twenty IDA women were compared to healthy age-matched controls. Lipoprotein profile, cholesteryl ester transfer protein (CETP), paraoxonase (PON) 1 and lipoprotein-associated phospholipase A(2) (LpPLA(2)) activities and plasma levels of oxidized-LDL were evaluated. RESULTS: Triglycerides were higher (median [range]) (1.0 [0.5-1.9] vs. 0.7 [0.5-1.5] mmol/L, p<0.05) and HDL-C lower (mean + or - SD) (1.3 + or - 0.3 vs. 1.6 + or - 0.4 mmol/L, p<0.01) in the patients group. CETP (197 + or - 29% vs. 151 + or - 29% mL(-1) h(-1), p<0.001), PON 1 (122 + or - 17 vs. 140 + or - 33 micromol mL(-1) min(-1), p<0.05) and LpPLA(2) (9.6 + or - 2.0 vs. 8.1 + or - 1.7 micromol mL(-1) h(-1), p<0.05) activities were different in IDA women. No difference was observed in oxidized-LDL. Haemoglobin correlated negatively with triglycerides (r=-0.35, p<0.05), CETP (r=-0.62, p<0.001) and LpPLA(2) (r=-0.34, p<0.05), while ferritin was positively associated with HDL-C (r=0.39, p<0.05) and inversely with CETP (r=-0.49, p<0.005). CONCLUSION: The alterations in lipoprotein profile, CETP, PON 1 and LpPLA(2) activities described in the present study indicate that non-treated IDA might represent a proatherogenic state.

Biomarcadores de aterosclerosis e indicadores de resistencia insulínica en pacientes acromegálicos no diabéticos / Biomarkers of Atherosclerosis and Indicators of Insulin Resistance in Non-Diabetic Acromegalic Patients

Introducción En la acromegalia, las comorbilidades cardiovasculares, respiratorias y metabólicas contribuyen a un aumento significativo de la mortalidad de los pacientes afectados. Asimismo, una proporción elevada de estos pacientes presentan diabetes mellitus. Pese a que el hallazgo de un perfil lipídico y lipoproteico anormal en pacientes acromegálicos suele ser habitual, cuando se intenta identificar y/o establecer el grado de modificaciones de parámetros específicos, los resultados son controversiales. Objetivos Evaluar la presencia de biomarcadores de aterosclerosis en pacientes con acromegalia activa no diabéticos y su asociación con la hormona del crecimiento (GH) y el factor de crecimiento similar a la insulina tipo 1 (IGF-1). Material y métodos Se estudiaron 14 pacientes y 14 controles sanos pareados por sexo y edad. Se midieron las concentraciones de GH e IGF-1 por inmunoensayos. Se evaluaron indicadores de resistencia insulínica (glucosa, insulina y HOMA), perfil lipoproteico, niveles plasmáticos de lipoproteínas de baja densidad oxidadas (LDLox), moléculas de adhesión celular vascular 1 (VCAM-1), endotelina-1 y actividad de fosfolipasa A2 asociada con lipoproteínas (LpPLA2). Resultados En comparación con los controles, los pacientes presentaron aumentos de GH (p < 0,05) e IGF-1 (p < 0,001), de los indicadores de resistencia insulínica (insulina p < 0,001; HOMA p < 0,001), triglicéridos (p < 0,05), apo B (p < 0,001), LDLox (117 ± 20 versus 89 ± 23 U/ L; p < 0,05) y endotelina-1 (0,9 ± 0,2 versus 0,7 ± 0,2 pg/ml; p < 0,05). Más aún, la GH y el IGF-1 se asociaron positivamente con (r; p <) insulina (0,40; 0,05 y 0,73; 0,001), HOMA (0,39; 0,05 y 0,74; 0,001), triglicéridos (0,57; 0,05 y 0,64; 0,001), colesterol de lipoproteínas de muy baja densidad (C-VLDL) (0,54; 0,05 y 0,47; 0,05), apo B (0,40; 0,05 y 0,54; 0,05), LDLox (0,59; 0,05 y 0,66; 0,05) y endotelina-1 (0,55; 0,05 y 0,51; 0,05). Conclusiones Los pacientes con acromegalia activa no diabéticos presentaron un estado de resistencia insulínica, así como modificaciones sutiles en el perfil lipoproteico y concentraciones elevadas de LDLox y endotelina-1. Las alteraciones descriptas podrían contribuir a un estado de mayor propensión al desarrollo de enfermedad cardiovascular aterosclerótica, la cual se sumaría a la miocardiopatía específica de la acromegalia.

Background Cardiovascular, respiratory and metabolic comorbidities associated with acromegaly contribute to a significant increase in the mortality of this disease. Many of these patients are also diabetic. Although it is frequent to find abnormal lipid and lipoprotein profiles in patients with acromegaly, controversial outcomes arise in an attempt to identify and/or establish the degree of the modifications of specific parameters. Objectives To assess the presence of biomarkers of atherosclerosis in non-diabetic patients with active acromegaly and its association with growth hormone (GH) and with insulin-like growth factor type 1 (IGF-1). Material and Methods The study included 14 patients and 14 healthy controls, pared by sex and age. Serum concentration of GH and IGF- 1 were determined by immunoassays. Indicators of insulin resistance (glucose, insulin and HOMA) were measured, as well as lipoprotein profile, plasmatic levels of oxidized LDL (oxLDL), vascular cell adhesion molecule 1 (VCAM-1), endothelin-1 and lipoprotein-associated phospholipase A2 activity (LpPLA2). Results Compared to controls, non-diabetic acromegalic patients had increased levels of GH (p<0.05) and IGF-1 (p<0.001), of indicators of insulin resistance (insulin p<0.001; HOMA p<0.001), triglycerides (p<0.05), apo B (p<0.001), oxLDL (117±20 versus 89±23 U/L; p<0.05) and endothelin-1 (0.9±0.2 versus 0.7±0.2 pg/ml; p<0.05). In addition, GH and IGF-1 were positively associated with (r; p <) insulin (0.40; 0.05 and 0.73; 0.001), HOMA (0.39; 0.05 and 0.74; 0.001), triglycerides (0.57; 0.05 and 0.64; 0.001), very low density lipoprotein-cholesterol (VLDL-C) (0.54; 0.05 and 0.47; 0.05), apo B (0.40; 0.05 and 0.54; 0.05), oxLDL (0.59; 0.05 and 0.66; 0.05) and endothelin-1 (0.55; 0.05 and 0.51; 0.05). Conclusions Non-diabetic patients with active acromegaly presented an insulin-resistant status, as well as subtle modifications of lipid profile and increased levels of oxLDL and endothelin- 1. These alterations could explain why these patients are more likely to develop atherosclerotic cardiovascular disease in addition to acromegalic cardiomyopathy.

Chronic renal failure in diabetic patients increases lipid risk factors for atherosclerosis.

Diabetic patients are at high risk of cardiovascular disease and the risk is amplified in the presence of nephropathy, which may be partially attributed to modifications in lipoproteins. Moreover, lipoprotein profile may be affected by incipient nephropathy, glomerulopathy, and mild or severe renal failure. The aim of our study was to evaluate whether chronic renal failure (CRF) changes lipoprotein profile and apo A-I urinary excretion in diabetic subjects with glomerulopathy in comparison with non-diabetic subjects with glomerulopathy and CRF. Diabetic (n=25) and non-diabetic (n=10) patients with glomerulopathy and CRF showed significantly higher LDL-cholesterol, non-HDL-cholesterol and HDL-triglyceride levels than diabetic individuals without CRF (n=10). Arylesterase and paraoxonase activities did not show any difference between groups. Apo A-I could not be detected in urine samples from diabetic patients without CRF. All diabetic subjects with glomerulopathy and CRF who presented proteinuria above 6.5 g/24 h showed detectable urinary apo A-I (range=13.1-61.0 mg/24 h). Similarly, all non-diabetic patients with glomerulopathy and CRF who had proteinuria above 8.0 g/24 h also evidenced detectable apo A-I in urine (range=25.6-557.3 mg/24 h). Urinary apo A-I showed positive and significant correlations with urea (r=0.73, p<0.05) and proteinuria (r=0.97, p<0.0001), and a negative correlation with albumin plasma levels (r=-0.68, p<0.05). In conclusion, the presence of CRF in diabetic patients was associated with a more atherogenic lipoprotein profile.

Sindrome de deficiencia parcial de lecitina-colesterol aciltransferasa (LCAT) / Partial lecithin-cholesterol acyltransferase (LCAT) deficiency syndrome

El síndrome de deficiencia parcial de la enzima lecitina-colesterol aciltransferasa (LCAT) es una en tidad patológica de baja incidencia que afecta fundamentalmente el metabolismo de las lipoproteínas de alta densidad (HDL). Comunicamos el primer caso reportado en nuestro país. Se presentó en una mujer de 63 años de edad que tenía opacidad corneal bilateral y xantomas eruptivos en brazos y antebrazos. El estudio lipoproteico reveló hipertrigliceridemia severa t colesterolemia normal, aunque la proporción de colesterol esterificado se hallaba substancialmente disminuida. Es de notar que los niveles plasmáticos de colesterol-HDL y de sus apoproteínas mayoritarias, A-I y A-IIm fueron insualmente bajos. Se observó además intolerancia a la glucosa y alteraciones hematológicas relacionadas con una composición lipídica anormal de las membranas eritrocitarias. La actividad plasmática de la LCAT, evaluada por el método del sustrato exógeno, fue un 82 por ciento menor en la paciente que en un individuo control. Es de destacar que la paciente aquí descripta mostró antecedentes de episodios cardíacos e hipertensión arterial, lo cual difere de muchos de los casos de deficiencia parcial de la enzima (LCAT).

Sindrome de deficiencia parcial de lecitina-colesterol aciltransferasa (LCAT) / Partial lecithin-cholesterol acyltransferase (LCAT) deficiency syndrome

El síndrome de deficiencia parcial de la enzima lecitina-colesterol aciltransferasa (LCAT) es una en tidad patológica de baja incidencia que afecta fundamentalmente el metabolismo de las lipoproteínas de alta densidad (HDL). Comunicamos el primer caso reportado en nuestro país. Se presentó en una mujer de 63 años de edad que tenía opacidad corneal bilateral y xantomas eruptivos en brazos y antebrazos. El estudio lipoproteico reveló hipertrigliceridemia severa t colesterolemia normal, aunque la proporción de colesterol esterificado se hallaba substancialmente disminuida. Es de notar que los niveles plasmáticos de colesterol-HDL y de sus apoproteínas mayoritarias, A-I y A-IIm fueron insualmente bajos. Se observó además intolerancia a la glucosa y alteraciones hematológicas relacionadas con una composición lipídica anormal de las membranas eritrocitarias. La actividad plasmática de la LCAT, evaluada por el método del sustrato exógeno, fue un 82 por ciento menor en la paciente que en un individuo control. Es de destacar que la paciente aquí descripta mostró antecedentes de episodios cardíacos e hipertensión arterial, lo cual difere de muchos de los casos de deficiencia parcial de la enzima (LCAT). (AU)