Physicochemical Properties of Lipoproteins Assessed by Nuclear Magnetic Resonance as a Predictor of Premature Cardiovascular Disease. PRESARV-SEA Study

Cardiovascular diseases; Lipoproteins; Magnetic resonance spectroscopyEnfermedades cardiovasculares; Lipoproteínas; Espectroscopia de resonancia magnéticaMalalties cardiovasculars; Lipoproteïnes; Espectroscòpia de ressonància magnèticaSome lipoprotein disorders related to the residual risk of premature cardiovascular disease (PCVD) are not detected by the conventional lipid profile. In this case-control study, the predictive power of PCVD of serum sdLDL-C, measured using a lipoprotein precipitation method, and of the physicochemical properties of serum lipoproteins, analyzed by nuclear magnetic resonance (NMR) techniques, were evaluated. We studied a group of patients with a first PCVD event (n = 125) and a group of control subjects (n = 190). Conventional lipid profile, the size and number of Very Low Density Lipoproteins (VLDL), Low Density Lipoproteins (LDL), High Density Lipoproteins (HDL) particles, and the number of particles of their subclasses (large, medium, and small) were measured. Compared to controls, PCVD patients had lower concentrations of all LDL particles, and smaller and larger diameter of LDL and HDL particles, respectively. PCVD patients also showed higher concentrations of small dense LDL-cholesterol (sdLDL), and triglycerides (Tg) in LDL and HDL particles (HDL-Tg), and higher concentrations of large VLDL particles. Multivariate logistic regression showed that sdLDL-C, HDL-Tg, and large concentrations of LDL particles were the most powerful predictors of PCVD. A strong relationship was observed between increased HDL-Tg concentrations and PCVD. This study demonstrates that beyond the conventional lipid profile, PCVD patients have other atherogenic lipoprotein alterations that are detected by magnetic resonance imaging (MRI) analysis.This work was supported in part by the Spanish Ministry of Health (Carlos III Health Institute) through the Fondo de Investigación para la Salud (FIS), which is co-funded by the European Regional Development Fund, funded by the following grant codes: PI16/01094 and PI19/01032

Precipitated sdLDL: An easy method to estimate LDL particle size

Background: LDL-C lowering is the main measure in cardiovascular disease prevention but a residual risk of ischemic events still remains. Alterations of lipoproteins, specially, increase in small dense LDL (sdLDL) particles are related to this risk. Objective: To investigate the potential use of sdLDL cholesterol concentration (sdLDL-C) isolated by an easy precipitation method and to assess the impact of a set of clinical and biochemical variables determined by NMR on sdLDL concentration. Methods: sdLDL-C and NMR lipid profile were performed in 85 men samples. Association among them was evaluated using Pearson coefficients (rxy ). A multivariate regression was performed to identify the influence of NMR variables on sdLDL-C. Results: A strong association between sdLDL-C and LDLLDL-P (rxy = 0.687) and with LDL-Z (rxy = -0.603) was found. The multivariate regression explained a 56.8% in sdLDL-C variation (P = 8.77.10-12). BMI, ApoB, triglycerides, FFA, and LDL-Z showed a significant contribution. The most important ones were ApoB and LDL-Z; a 1nm increase (LDL-Z) leads to decrease 126 nmol/L in sdLDL-C. Conclusion: The association between sdLDL-C, LDL-Z, and LDL-P is clear. From a large number of variables, especially LDL-Z and apoB influence on sdLDL-C. Results show that the smaller the LDL size, the higher their cholesterol concentration. Therefore, sdLDL-C determination by using this easy method would be useful to risk stratification and to uncover cardiovascular residual risk

The Impact of the Mediterranean Diet and Lifestyle Intervention on Lipoprotein Subclass Profiles among Metabolic Syndrome Patients: Findings of a Randomized Controlled Trial

Metabolic syndrome (MetS) is associated with alterations of lipoprotein structure and function that can be characterized with advanced lipoprotein testing (ADLT). The effect of the Mediterranean diet (MedDiet) and weight loss on the lipoprotein subclass profile has been scarcely studied. Within the PREDIMED-Plus randomized controlled trial, a sub-study conducted at Bellvitge Hospital recruiting center evaluated the effects of a weight loss program based on an energy-reduced MedDiet (er-MedDiet) and physical activity (PA) promotion (intervention group) compared with energy-unrestricted MedDiet recommendations (control group) on ADLT-assessed lipoprotein subclasses. 202 patients with MetS (n = 107, intervention; n = 95, control) were included. Lipid profiles were determined, and ADLT was performed at baseline, 6, and 12 months. Linear mixed models were used to assess the effects of intervention on lipoprotein profiles. Compared to the control diet, at 12 months, the er-MedDiet+PA resulted in a significant additional 4.2 kg of body weight loss, a decrease in body mass index by 1.4 kg/m2, reduction in waist circumference by 2.2 cm, decreased triglycerides, LDL-cholesterol and non-HDL-cholesterol, and increased HDL-cholesterol. In er-MedDiet+PA participants, ADLT revealed a decrease in small dense-LDL-cholesterol (sd-LDL-C), intermediate-density lipoproteins, VLDL-triglyceride, and HDL-Triglyceride, and an increase in large LDL and large VLDL particles. In conclusion, compared to an ad libitum MedDiet (control group), er-MedDiet+PA decreased plasma triglycerides and the triglyceride content in HDL and VLDL particles, decreased sd-LDL-C, and increased large LDL particles, indicating beneficial changes against cardiovascular disease

Reference values assessment in a Mediterranean population for small dense low-density lipoprotein concentration isolated by an optimized precipitation method

Background: High serum concentrations of small dense low-density lipoprotein cholesterol (sd-LDL-c) particles are associated with risk of cardiovascular disease (CVD). Their clinical application has been hindered as a consequence of the laborious current method used for their quantification. Objective: Optimize a simple and fast precipitation method to isolate sd-LDL particles and establish a reference interval in a Mediterranean population. Materials and methods: Forty-five serum samples were collected, and sd-LDL particles were isolated using a modified heparin-Mg2+ precipitation method. sd-LDL-c concentration was calculated by subtracting high-density lipoprotein cholesterol (HDL-c) from the total cholesterol measured in the supernatant. This method was compared with the reference method (ultracentrifugation). Reference values were estimated according to the Clinical and Laboratory Standards Institute and The International Federation of Clinical Chemistry and Laboratory Medicine recommendations. sd-LDL-c concentration was measured in serums from 79 subjects with no lipid metabolism abnormalities. Results: The Passing-Bablok regression equation is y = 1.52 (0.72 to 1.73) + 0.07x (−0.1 to 0.13), demonstrating no significant statistical differences between the modified precipitation method and the ultracentrifugation reference method. Similarly, no differences were detected when considering only sd-LDL-c from dyslipidemic patients, since the modifications added to the precipitation method facilitated the proper sedimentation of triglycerides and other lipoproteins. The reference interval for sd-LDL-c concentration estimated in a Mediterranean population was 0.04-0.47 mmol/L. Conclusion: An optimization of the heparin-Mg2+ precipitation method for sd-LDL particle isolation was performed, and reference intervals were established in a Spanish Mediterranean population. Measured values were equivalent to those obtained with the reference method, assuring its clinical application when tested in both normolipidemic and dyslipidemic subjects

Collapsing Glomerulonephritis in a Kidney Transplant Recipient after mRNA SARS-CoV-2 Vaccination

With the vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), studies are describing cases of glomerulonephritis arising after vaccination. We present the first case of a kidney transplant patient who, after mRNA vaccination against SARS-CoV-2, developed nephrotic proteinuria and renal dysfunction, with a biopsy diagnostic of collapsing glomerulonephritis. No other triggers for this glomerulonephritis were identified. Antibodies against the spike protein were negative, but the patient developed a specific T-cell response. The close time between vaccination and the proteinuria suggests a possible determinant role of vaccination. We should be aware of nephropathies appearing after COVID-19 vaccination in kidney transplant recipients also

Physicochemical Properties of Lipoproteins Assessed by Nuclear Magnetic Resonance as a Predictor of Premature Cardiovascular Disease. PRESARV-SEA Study

Some lipoprotein disorders related to the residual risk of premature cardiovascular disease (PCVD) are not detected by the conventional lipid profile. In this case-control study, the predictive power of PCVD of serum sdLDL-C, measured using a lipoprotein precipitation method, and of the physicochemical properties of serum lipoproteins, analyzed by nuclear magnetic resonance (NMR) techniques, were evaluated. We studied a group of patients with a first PCVD event (n = 125) and a group of control subjects (n = 190). Conventional lipid profile, the size and number of Very Low Density Lipoproteins (VLDL), Low Density Lipoproteins (LDL), High Density Lipoproteins (HDL) particles, and the number of particles of their subclasses (large, medium, and small) were measured. Compared to controls, PCVD patients had lower concentrations of all LDL particles, and smaller and larger diameter of LDL and HDL particles, respectively. PCVD patients also showed higher concentrations of small dense LDL-cholesterol (sdLDL), and triglycerides (Tg) in LDL and HDL particles (HDL-Tg), and higher concentrations of large VLDL particles. Multivariate logistic regression showed that sdLDL-C, HDL-Tg, and large concentrations of LDL particles were the most powerful predictors of PCVD. A strong relationship was observed between increased HDL-Tg concentrations and PCVD. This study demonstrates that beyond the conventional lipid profile, PCVD patients have other atherogenic lipoprotein alterations that are detected by magnetic resonance imaging (MRI) analysis

Physicochemical Properties of Lipoproteins Assessed by Nuclear Magnetic Resonance as a Predictor of Premature Cardiovascular Disease. PRESARV-SEA Study

Some lipoprotein disorders related to the residual risk of premature cardiovascular disease (PCVD) are not detected by the conventional lipid profile. In this case-control study, the predictive power of PCVD of serum sdLDL-C, measured using a lipoprotein precipitation method, and of the physicochemical properties of serum lipoproteins, analyzed by nuclear magnetic resonance (NMR) techniques, were evaluated. We studied a group of patients with a first PCVD event (n = 125) and a group of control subjects (n = 190). Conventional lipid profile, the size and number of Very Low Density Lipoproteins (VLDL), Low Density Lipoproteins (LDL), High Density Lipoproteins (HDL) particles, and the number of particles of their subclasses (large, medium, and small) were measured. Compared to controls, PCVD patients had lower concentrations of all LDL particles, and smaller and larger diameter of LDL and HDL particles, respectively. PCVD patients also showed higher concentrations of small dense LDL-cholesterol (sdLDL), and triglycerides (Tg) in LDL and HDL particles (HDL-Tg), and higher concentrations of large VLDL particles. Multivariate logistic regression showed that sdLDL-C, HDL-Tg, and large concentrations of LDL particles were the most powerful predictors of PCVD. A strong relationship was observed between increased HDL-Tg concentrations and PCVD. This study demonstrates that beyond the conventional lipid profile, PCVD patients have other atherogenic lipoprotein alterations that are detected by magnetic resonance imaging (MRI) analysis

Contribución del colesterol en las partículas sdldl y el perfil lipídico avanzado al riesgo cardiovascular residual y su respuesta a la dieta mediterránea

Les estratègies per a la prevenció de les malalties cardiovasculars basades en la detecció de factors de risc cardiovascular (FRCV) i en el tractament centrat en la disminució de la concentració de C-LDL han aconseguit disminuir la morbimortalitat associada a aquestes malalties. No obstant això, tot i els esforços, segueixen tenint lloc esdeveniments isquèmics. Una possibilitat per explicar això, és que hi hagi un risc cardiovascular residual (RCVR). Aquest risc, està associat a la dislipèmia aterogènica (DA) i a alteracions en el metabolisme de les lipoproteïnes que afecten la seva concentració i composició. No obstant això, malgrat les eines per identificar-lo, encara hi ha pacients amb un RCV infraestimat. Tenint en compte les publicacions recents, és possible que l'estudi del perfil lipídic avançat pugui justificar aquest RCVR. Per això, en aquesta tesi es plantegen les següents hipòtesis: a) La determinació del perfil lipídic avançat podria ser d'utilitat per explicar el RCVR en pacients amb un perfil lipídic clàssic normal; b) La MedDiet podria tenir un impacte important en el perfil lipídic avançat i contribuir a millorar-lo La subfracció més aterogènica de les LDL són les sdLDL ja que s'infiltren més fàcilment en l'endoteli vascular causa de la seva petita mida i elevada densitat. Tot i l'evidència científica, no s'ha incorporat la seva determinació als laboratoris clínics causa de la falta d'estandardització d'un procediment de mesura practicable i de l'absència de valors de referència adequats. Dins el perfil lipídic avançat, també s'han pogut caracteritzar les diferents subclasses de lipoproteïnes i les seves subfraccions mitjançant les noves tècniques de Ressonància Magnètica Nuclear (RMN). A la primera part d'aquesta tesi es va estandarditzar un mètode de precipitació per a l'aïllament de les partícules sdLDL i mesurar la seva concentració de colesterol. Un cop realitzat aquest primer pas, es van calcular els valors de referència per C-sdLDL en una població sana. Posteriorment, es va demostrar la relació que hi havia entre el diàmetre de les LDL establert per RMN i la concentració de colesterol a les sdLDL. La relació entre ambdues propietats resultar ser que estaven relacionades inversament, i de forma significativa, de tal manera que a l'disminuir el diàmetre de les partícules augmenta la concentració de colesterol a les sdLDL. En tercer lloc, en aquesta tesi s'ha estudiat la influència del perfil lipídic avançat sobre el RCVR. Els resultats de la tercera part d'aquesta tesi doctoral han demostrat la contribució de la subfracció més voluminosa de les LDL (lLDL-P) i dels Tg continguts en les HDL (Tg-HDL) a el risc de patir un esdeveniment isquèmic prematur. Les lLDL-P tenen un efecte protector mentre que l'augment de Tg-HDL incrementa el risc de patir un esdeveniment isquèmic prematur. Finalment, per tancar aquesta tesi doctoral s'ha estudiat l'efecte de l'estil de vida sobre el perfil lipídic avançat amb l'objectiu d'estudiar si podria ajudar a millorar el RCVR un cop el C-LDL ja està controlat.L'estudi PREDIMED-PLUS està avaluant l'efecte de la MedDiet hipocalòrica, activitat física i teràpia conductual (erMedDiet + PA) enfront de la MedDiet i l'assistència sanitària tradicional. Els resultats obtinguts en el quart estudi d'aquesta tesi indiquen l'efecte beneficiós de la MedDiet en el perfil lipídic avançat, sobretot en la composició de les partícules LDL disminuint la concentració de C-sdLDL. També s'ha determinat que el programa erMedDiet + PA millora la composició de les lipoproteïnes LDL i de les VLDL enfront de la MedDiet tradicional. Tenint en compte els resultats obtinguts en aquesta tesi, es posa de manifest el valor afegit del perfil lipídic avançat en l'estudi del RCVR que no es pot abordar mitjançant un perfil lipídic clàssic.Las estrategias para la prevención de la enfermedad cardiovascular (ECV) basadas en la detección de factores de riesgo cardiovascular (FRCV) y en el tratamiento centrado en la disminución de la concentración de C-LDL han conseguido disminuir la morbimortalidad asociada a la ECV. Sin embargo, a pesar de los esfuerzos, siguen teniendo lugar eventos isquémicos. Una posibilidad para explicar esto, es que exista un riesgo cardiovascular residual (RCVR). Este riesgo, está asociado a la dislipemia aterogénica (DA) y a alteraciones en el metabolismo de las lipoproteínas que afectan a su concentración y composición. Sin embargo, a pesar de las herramientas para identificarlo, aún existen pacientes con un riesgo cardiovascular (RCV) infraestimado. Por ello, en esta tesis se plantean las siguientes hipótesis: a) La determinación del perfil lipídico avanzado podría ser de utilidad para explicar el RCVR en pacientes con un perfil lipídico clásico normal; b) La MedDiet podría tener un impacto importante en el perfil lipídico avanzado y contribuir a mejorarlo. La subfracción más aterogénica de las LDL son las sdLDL ya que se infiltran más fácilmente en el endotelio vascular debido a su pequeño tamaño y elevada densidad. A pesar de la evidencia científica, no se ha incorporado su determinación a los laboratorios clínicos debido a la falta de estandarización de un procedimiento de medida practicable y a la ausencia de valores de referencia adecuados. Dentro del perfil lipídico avanzado, además de la concentración de C-sdLDL también se han podido caracterizar las diferentes subclases de lipoproteínas y sus subfracciones mediante las nuevas técnicas de Resonancia Magnética Nuclear (RMN). El primer objetivo de esta tesis fue estandarizar un método de precipitación para el aislamiento de las partículas sdLDL y medir su concentración de colesterol. Una vez realizado este primer paso, se calcularon los valores de referencia para C-sdLDL en una población sana. En una segunda etapa, se quiso estudiar la relación entre el colesterol de las partículas sdLDL y las características de las lipoproteínas valoradas mediante RMN. De esta forma, se demostró la relación que había entre el diámetro de las LDL y la concentración de colesterol de las sdLDL. Ambas propiedades estaban relacionadas inversamente, y de forma significativa, de tal modo que al disminuir el diámetro de las partículas aumentaba la concentración del colesterol en las sdLDL. En tercer lugar, se ha estudiado el papel del perfil lipídico avanzado en la valoración del RCVR. Los resultados de la tercera parte de esta tesis doctoral han demostrado la contribución de la subfracción más voluminosa de las LDL (lLDL-P) y de los Tg contenidos en las HDL (Tg-HDL) al riesgo de sufrir un evento isquémico prematuro. Las lLDL-P tienen un efecto protector mientras que el aumento de Tg-HDL incrementa el riesgo de sufrir un evento isquémico prematuro. Finalmente, para concluir esta tesis doctoral se ha estudiado el efecto del estilo de vida sobre el perfil lipídico avanzado. Actualmente, el estudio PREDIMED-PLUS está evaluando el efecto de la MedDiet con restricción calórica, actividad física y terapia conductual (erMedDiet+PA) frente a la MedDiet y la asistencia sanitaria tradicional. Los resultados obtenidos en el cuarto estudio de esta tesis indican el efecto beneficioso de la MedDiet en el perfil lipídico avanzado, sobre todo en la composición de las partículas LDL disminuyendo la concentración de C-sdLDL. También se ha determinado que el programa erMedDiet+PA mejora la composición de las lipoproteínas LDL y de las VLDL frente a la MedDiet tradicional. Teniendo en cuenta los resultados obtenidos en esta tesis, se pone de manifiesto el valor añadido del perfil lipídico avanzado en el estudio del RCVR que no se puede abordar mediante un perfil lipídico clásico.Cardiovascular disease (CVD) prevention is based on cardiovascular risc factors (CVRF) early detection and lowering C-LDL concentration. These strategies have shown to reduce the morbidity and mortality related to CVD. However, ischemic events still occur because of the residual cardiovascular risk (RCVR). Commonly, is associated with atherogenic dyslipemia (AD) and with alterations in lipoproteins metabolism that affect their concentration and composition as well. However, some patients still present an underestimated CVR. Recent publications show that it is possible to explain this RCVR thanks to the advanced lipid profile. On the other hand, the MedDiet and its effect on the traditional lipid profile and weight has proved to reduce ischemic premature events. For this reason, it would be interesting to find out the impact of MedDiet on the advanced lipid profile and the RCVR. Therefore, in this thesis the following hypotheses are raised: a) Advanced lipid profile could be useful to explain the RCVR in patients with a normal classical lipid profile; b) MedDiet could have a significant impact on the advanced lipid profile and contribute to its improvement. The most atherogenic LDL subfractions are sdLDL, due to their small size and high density; these particles can easily pass through the vascular endothelium. Despite scientific evidence, its determination has not been included in clinical laboratories due to the lack of standardization of a practicable measurement procedure and adequate reference values. In addition to C-sdLDL concentration, different subclasses of lipoproteins have been characterized using Nuclear Magnetic Resonance (NMR) techniques. This method can provide information about the composition, concentration and particle number of lipoprotein subclasses. In the first part of this study, a precipitation method for sdLDL isolation was standardized and cholesterol concentration contained in these particles was measured. Reference values for C-sdLDL were calculated in a healthy population and published in a scientific journal. Subsequently, we study the relationship between C-sdLDL and LDL characteristics established by RMN. We find out that LDL diameter established by NMR is inversely correlated to C-sdLDL. These results are significant and proved that as the LDL diameter decreased, C-sdLDL increased. After that, the effect of advanced lipid profile on RCVR was also studied. Results obtained have demonstrated that large LDL subfraction (lLDL-P) and Tg contained in HDL (Tg-HDL) contribute to the risk of suffering a premature ischemic event. LLDL-P has a protective effect while Tg-HDL increases the risk of suffering a premature ischemic event. Finally, the effect of lifestyle on advanced lipid profile has been studied. The principal aim was to determine the effect on lipoprotein subclasses when C-LDL has achieved goal concentration. Considering that lifestyle changes are the first line on CVD treatment, it is important to determine the influence of healthy lifestyle habits and different types of diet on the advanced lipid profile. The PREDIMED study has already demonstrated the beneficial effects of MedDiet on reducing mortality related to CVD. Meanwhile, the PREDIMED-PLUS study is evaluating the effect of hypocaloric MedDiet, physical activity and behavioral therapy (erMedDiet + PA) versus MedDiet and traditional healthcare. Results obtained in this study indicate the beneficial effect of MedDiet on the advanced lipid profile, especially on the composition of LDL particles, reducing C-sdLDL. The erMedDiet + PA program has also improved LDL and VLDL lipoprotein composition over traditional MedDiet results. Taking into account results obtained in this research work, we have demonstrated the benefit of the advanced lipid profile on RCVR identification, which cannot be detected using the classic lipid profile

Contribución del colesterol en las partículas sdldl y el perfil lipídico avanzado al riesgo cardiovascular residual y su respuesta a la dieta mediterránea

Les estratègies per a la prevenció de les malalties cardiovasculars basades en la detecció de factors de risc cardiovascular (FRCV) i en el tractament centrat en la disminució de la concentració de C-LDL han aconseguit disminuir la morbimortalitat associada a aquestes malalties. No obstant això, tot i els esforços, segueixen tenint lloc esdeveniments isquèmics. Una possibilitat per explicar això, és que hi hagi un risc cardiovascular residual (RCVR). Aquest risc, està associat a la dislipèmia aterogènica (DA) i a alteracions en el metabolisme de les lipoproteïnes que afecten la seva concentració i composició. No obstant això, malgrat les eines per identificar-lo, encara hi ha pacients amb un RCV infraestimat. Tenint en compte les publicacions recents, és possible que l’estudi del perfil lipídic avançat pugui justificar aquest RCVR. Per això, en aquesta tesi es plantegen les següents hipòtesis: a) La determinació del perfil lipídic avançat podria ser d’utilitat per explicar el RCVR en pacients amb un perfil lipídic clàssic normal; b) La MedDiet podria tenir un impacte important en el perfil lipídic avançat i contribuir a millorar-lo La subfracció més aterogènica de les LDL són les sdLDL ja que s’infiltren més fàcilment en l’endoteli vascular causa de la seva petita mida i elevada densitat. Tot i l’evidència científica, no s’ha incorporat la seva determinació als laboratoris clínics causa de la falta d’estandardització d’un procediment de mesura practicable i de l’absència de valors de referència adequats. Dins el perfil lipídic avançat, també s’han pogut caracteritzar les diferents subclasses de lipoproteïnes i les seves subfraccions mitjançant les noves tècniques de Ressonància Magnètica Nuclear (RMN). A la primera part d’aquesta tesi es va estandarditzar un mètode de precipitació per a l’aïllament de les partícules sdLDL i mesurar la seva concentració de colesterol. Un cop realitzat aquest primer pas, es van calcular els valors de referència per C-sdLDL en una població sana. Posteriorment, es va demostrar la relació que hi havia entre el diàmetre de les LDL establert per RMN i la concentració de colesterol a les sdLDL. La relació entre ambdues propietats resultar ser que estaven relacionades inversament, i de forma significativa, de tal manera que a l’disminuir el diàmetre de les partícules augmenta la concentració de colesterol a les sdLDL. En tercer lloc, en aquesta tesi s’ha estudiat la influència del perfil lipídic avançat sobre el RCVR. Els resultats de la tercera part d’aquesta tesi doctoral han demostrat la contribució de la subfracció més voluminosa de les LDL (lLDL-P) i dels Tg continguts en les HDL (Tg-HDL) a el risc de patir un esdeveniment isquèmic prematur. Les lLDL-P tenen un efecte protector mentre que l’augment de Tg-HDL incrementa el risc de patir un esdeveniment isquèmic prematur. Finalment, per tancar aquesta tesi doctoral s’ha estudiat l’efecte de l’estil de vida sobre el perfil lipídic avançat amb l’objectiu d’estudiar si podria ajudar a millorar el RCVR un cop el C-LDL ja està controlat.L’estudi PREDIMED-PLUS està avaluant l’efecte de la MedDiet hipocalòrica, activitat física i teràpia conductual (erMedDiet + PA) enfront de la MedDiet i l’assistència sanitària tradicional. Els resultats obtinguts en el quart estudi d’aquesta tesi indiquen l’efecte beneficiós de la MedDiet en el perfil lipídic avançat, sobretot en la composició de les partícules LDL disminuint la concentració de C-sdLDL. També s’ha determinat que el programa erMedDiet + PA millora la composició de les lipoproteïnes LDL i de les VLDL enfront de la MedDiet tradicional. Tenint en compte els resultats obtinguts en aquesta tesi, es posa de manifest el valor afegit del perfil lipídic avançat en l’estudi del RCVR que no es pot abordar mitjançant un perfil lipídic clàssic.Las estrategias para la prevención de la enfermedad cardiovascular (ECV) basadas en la detección de factores de riesgo cardiovascular (FRCV) y en el tratamiento centrado en la disminución de la concentración de C-LDL han conseguido disminuir la morbimortalidad asociada a la ECV. Sin embargo, a pesar de los esfuerzos, siguen teniendo lugar eventos isquémicos. Una posibilidad para explicar esto, es que exista un riesgo cardiovascular residual (RCVR). Este riesgo, está asociado a la dislipemia aterogénica (DA) y a alteraciones en el metabolismo de las lipoproteínas que afectan a su concentración y composición. Sin embargo, a pesar de las herramientas para identificarlo, aún existen pacientes con un riesgo cardiovascular (RCV) infraestimado. Por ello, en esta tesis se plantean las siguientes hipótesis: a) La determinación del perfil lipídico avanzado podría ser de utilidad para explicar el RCVR en pacientes con un perfil lipídico clásico normal; b) La MedDiet podría tener un impacto importante en el perfil lipídico avanzado y contribuir a mejorarlo. La subfracción más aterogénica de las LDL son las sdLDL ya que se infiltran más fácilmente en el endotelio vascular debido a su pequeño tamaño y elevada densidad. A pesar de la evidencia científica, no se ha incorporado su determinación a los laboratorios clínicos debido a la falta de estandarización de un procedimiento de medida practicable y a la ausencia de valores de referencia adecuados. Dentro del perfil lipídico avanzado, además de la concentración de C-sdLDL también se han podido caracterizar las diferentes subclases de lipoproteínas y sus subfracciones mediante las nuevas técnicas de Resonancia Magnética Nuclear (RMN). El primer objetivo de esta tesis fue estandarizar un método de precipitación para el aislamiento de las partículas sdLDL y medir su concentración de colesterol. Una vez realizado este primer paso, se calcularon los valores de referencia para C-sdLDL en una población sana. En una segunda etapa, se quiso estudiar la relación entre el colesterol de las partículas sdLDL y las características de las lipoproteínas valoradas mediante RMN. De esta forma, se demostró la relación que había entre el diámetro de las LDL y la concentración de colesterol de las sdLDL. Ambas propiedades estaban relacionadas inversamente, y de forma significativa, de tal modo que al disminuir el diámetro de las partículas aumentaba la concentración del colesterol en las sdLDL. En tercer lugar, se ha estudiado el papel del perfil lipídico avanzado en la valoración del RCVR. Los resultados de la tercera parte de esta tesis doctoral han demostrado la contribución de la subfracción más voluminosa de las LDL (lLDL-P) y de los Tg contenidos en las HDL (Tg-HDL) al riesgo de sufrir un evento isquémico prematuro. Las lLDL-P tienen un efecto protector mientras que el aumento de Tg-HDL incrementa el riesgo de sufrir un evento isquémico prematuro. Finalmente, para concluir esta tesis doctoral se ha estudiado el efecto del estilo de vida sobre el perfil lipídico avanzado. Actualmente, el estudio PREDIMED-PLUS está evaluando el efecto de la MedDiet con restricción calórica, actividad física y terapia conductual (erMedDiet+PA) frente a la MedDiet y la asistencia sanitaria tradicional. Los resultados obtenidos en el cuarto estudio de esta tesis indican el efecto beneficioso de la MedDiet en el perfil lipídico avanzado, sobre todo en la composición de las partículas LDL disminuyendo la concentración de C-sdLDL. También se ha determinado que el programa erMedDiet+PA mejora la composición de las lipoproteínas LDL y de las VLDL frente a la MedDiet tradicional. Teniendo en cuenta los resultados obtenidos en esta tesis, se pone de manifiesto el valor añadido del perfil lipídico avanzado en el estudio del RCVR que no se puede abordar mediante un perfil lipídico clásico.Cardiovascular disease (CVD) prevention is based on cardiovascular risc factors (CVRF) early detection and lowering C-LDL concentration. These strategies have shown to reduce the morbidity and mortality related to CVD. However, ischemic events still occur because of the residual cardiovascular risk (RCVR). Commonly, is associated with atherogenic dyslipemia (AD) and with alterations in lipoproteins metabolism that affect their concentration and composition as well. However, some patients still present an underestimated CVR. Recent publications show that it is possible to explain this RCVR thanks to the advanced lipid profile. On the other hand, the MedDiet and its effect on the traditional lipid profile and weight has proved to reduce ischemic premature events. For this reason, it would be interesting to find out the impact of MedDiet on the advanced lipid profile and the RCVR. Therefore, in this thesis the following hypotheses are raised: a) Advanced lipid profile could be useful to explain the RCVR in patients with a normal classical lipid profile; b) MedDiet could have a significant impact on the advanced lipid profile and contribute to its improvement. The most atherogenic LDL subfractions are sdLDL, due to their small size and high density; these particles can easily pass through the vascular endothelium. Despite scientific evidence, its determination has not been included in clinical laboratories due to the lack of standardization of a practicable measurement procedure and adequate reference values. In addition to C-sdLDL concentration, different subclasses of lipoproteins have been characterized using Nuclear Magnetic Resonance (NMR) techniques. This method can provide information about the composition, concentration and particle number of lipoprotein subclasses. In the first part of this study, a precipitation method for sdLDL isolation was standardized and cholesterol concentration contained in these particles was measured. Reference values for C-sdLDL were calculated in a healthy population and published in a scientific journal. Subsequently, we study the relationship between C-sdLDL and LDL characteristics established by RMN. We find out that LDL diameter established by NMR is inversely correlated to C-sdLDL. These results are significant and proved that as the LDL diameter decreased, C-sdLDL increased. After that, the effect of advanced lipid profile on RCVR was also studied. Results obtained have demonstrated that large LDL subfraction (lLDL-P) and Tg contained in HDL (Tg-HDL) contribute to the risk of suffering a premature ischemic event. LLDL-P has a protective effect while Tg-HDL increases the risk of suffering a premature ischemic event. Finally, the effect of lifestyle on advanced lipid profile has been studied. The principal aim was to determine the effect on lipoprotein subclasses when C-LDL has achieved goal concentration. Considering that lifestyle changes are the first line on CVD treatment, it is important to determine the influence of healthy lifestyle habits and different types of diet on the advanced lipid profile. The PREDIMED study has already demonstrated the beneficial effects of MedDiet on reducing mortality related to CVD. Meanwhile, the PREDIMED-PLUS study is evaluating the effect of hypocaloric MedDiet, physical activity and behavioral therapy (erMedDiet + PA) versus MedDiet and traditional healthcare. Results obtained in this study indicate the beneficial effect of MedDiet on the advanced lipid profile, especially on the composition of LDL particles, reducing C-sdLDL. The erMedDiet + PA program has also improved LDL and VLDL lipoprotein composition over traditional MedDiet results. Taking into account results obtained in this research work, we have demonstrated the benefit of the advanced lipid profile on RCVR identification, which cannot be detected using the classic lipid profile.Universitat Autònoma de Barcelona. Programa de Doctorat en Bioquímica, Biologia Molecular i Biomedicin

Precipitated sdLDL: An easy method to estimate LDL particle size

International audienceBackground LDL-C lowering is the main measure in cardiovascular disease prevention but a residual risk of ischemic events still remains. Alterations of lipoproteins, specially, increase in small dense LDL (sdLDL) particles are related to this risk.Objective To investigate the potential use of sdLDL cholesterol concentration (sdLDL-C) isolated by an easy precipitation method and to assess the impact of a set of clinical and biochemical variables determined by NMR on sdLDL concentration.Methods sdLDL-C and NMR lipid profile were performed in 85 men samples. Association among them was evaluated using Pearson coefficients (r(xy)). A multivariate regression was performed to identify the influence of NMR variables on sdLDL-C.Results A strong association between sdLDL-C and LDLLDL-P (r(xy) = 0.687) and with LDL-Z (r(xy) = -0.603) was found. The multivariate regression explained a 56.8% in sdLDL-C variation (P = 8.77.10-12). BMI, ApoB, triglycerides, FFA, and LDL-Z showed a significant contribution. The most important ones were ApoB and LDL-Z; a 1nm increase (LDL-Z) leads to decrease 126 nmol/L in sdLDL-C.Conclusion The association between sdLDL-C, LDL-Z, and LDL-P is clear. From a large number of variables, especially LDL-Z and apoB influence on sdLDL-C. Results show that the smaller the LDL size, the higher their cholesterol concentration. Therefore, sdLDL-C determination by using this easy method would be useful to risk stratification and to uncover cardiovascular residual risk.Background LDL-C lowering is the main measure in cardiovascular disease prevention but a residual risk of ischemic events still remains. Alterations of lipoproteins, specially, increase in small dense LDL (sdLDL) particles are related to this risk.Objective To investigate the potential use of sdLDL cholesterol concentration (sdLDL-C) isolated by an easy precipitation method and to assess the impact of a set of clinical and biochemical variables determined by NMR on sdLDL concentration.Methods sdLDL-C and NMR lipid profile were performed in 85 men samples. Association among them was evaluated using Pearson coefficients (r(xy)). A multivariate regression was performed to identify the influence of NMR variables on sdLDL-C.Results A strong association between sdLDL-C and LDLLDL-P (r(xy) = 0.687) and with LDL-Z (r(xy) = -0.603) was found. The multivariate regression explained a 56.8% in sdLDL-C variation (P = 8.77.10-12). BMI, ApoB, triglycerides, FFA, and LDL-Z showed a significant contribution. The most important ones were ApoB and LDL-Z; a 1nm increase (LDL-Z) leads to decrease 126 nmol/L in sdLDL-C.Conclusion The association between sdLDL-C, LDL-Z, and LDL-P is clear. From a large number of variables, especially LDL-Z and apoB influence on sdLDL-C. Results show that the smaller the LDL size, the higher their cholesterol concentration. Therefore, sdLDL-C determination by using this easy method would be useful to risk stratification and to uncover cardiovascular residual risk