Increasing the Magnesium Concentration in Various Dialysate Solutions Differentially Modulates Oxidative Stress in a Human Monocyte Cell Line

Oxidative stress is exacerbated in hemodialysis patients by several factors, including the uremic environment and the use of dialysis fluids (DFs). Since magnesium (Mg) plays a key role in modulating immune function and in reducing oxidative stress, we aimed to evaluate whether increasing the Mg concentration in different DFs could protect against oxidative stress in immunocompetent cells in vitro. Effect of ADF (acetate 3 mM), CDF (citrate 1 mM), and ACDF (citrate 0.8 mM + acetate 0.3 mM) dialysates with Mg at standard (0.5 mM) or higher (1, 1.25, and 2 mM) concentrations were assessed in THP-1 monocyte cultures. Reactive oxygen species (ROS) and malondialdehyde (MDA) levels were quantified under basal and uremic conditions (indoxyl sulfate (IS) treatment). Under uremic conditions, the three DFs with 0.5 mM Mg promoted higher ROS production and lipid damage than the control solution. However, CDF and ACDF induced lower levels of ROS and MDA, compared to that induced by ADF. High Mg concentration (1.25 and/or 2 mM) in CDF and ACDF protected against oxidative stress, indicated by reduced ROS and MDA levels compared to respective DFs with standard concentration of Mg. Increasing Mg concentrations in ADF promoted high ROS production and MDA content. Thus, an increase in Mg content in DFs has differential effects on the oxidative stress in IS-treated THP-1 cells depending on the dialysate used.Instituto de Salud Carlos IIISociedad Española de Nefrologí

A high magnesium concentration in citrate dialysate prevents oxidative stress and damage in human monocytes in vitro

Background. The use of dialysis fluids (DFs) during haemodialysis has been associated with increased oxidative stress and reduced serum magnesium (Mg) levels, contributing to chronic inflammation. Since the role of Mg in modulating immune function and reducing oxidative stress has been demonstrated, the aim of this study was to characterize in vitro whether increasing the Mg concentration in DFs could protect immune cells from oxidative stress and damage. Methods. The effect of citrate [citrate dialysis fluid (CDF), 1 mM] or acetate [acetate dialysis fluid (ADF), 3 mM] dialysates with low (0.5 mM; routinely used) or high (1 mM, 1.25 mM and 2 mM) Mg concentrations was assessed in THP-1 human monocytes. The levels of reactive oxygen species (ROS), malondialdehyde (MDA) and oxidized/reduced (GSSG/GSH) glutathione were quantified under basal and inflammatory conditions (stimulation with lipopolysaccharide, LPS). Results. The increase of Mg in CDF resulted in a significant reduction of ROS production under basal and inflammatory conditions (extremely marked in 2 mM Mg; P< 0.001). These effects were not observed in ADF. Interestingly, in a dose-dependent manner, high Mg doses in CDF reduced oxidative stress in monocytes under both basal and inflammatory conditions. In fact, 2 mM Mg significantly decreased the levels of GSH, GSSG and MDA and the GSSG/GSH ratio in relation to 0.5 mM Mg. Conclusions. CDF produces lower oxidative stress than ADF. The increase of Mg content in DFs, especially in CDF, could have a positive and protective effect in reducing oxidative stress and damage in immune cells, especially under inflammatory conditions.Instituto de Salud Carlos IIISociedad Española de NefrologíaUniversidad Complutense de MadridUniversidad de AlcaláFondo Europeo de Desarrollo Regional-FEDE

El papel del envejecimiento en el desarrollo de enfermedades cardiovasculares asociadas a patologías renales

El envejecimiento esconsiderado un factor de riesgo para el desarrollo de enfermedades cardiovasculares(ECV), y el proceso de senescencia endotelial es el desencadenante de patologías isquémicas y ECVcomo la arteriosclerosisy la enfermedad renal crónica (ERC).En la senescencia endotelial, las células endoteliales pierden su capacidad de proliferación por el efecto de agentes lesivos como el estrés oxidativo y/o la inflamación generada en el proceso deenvejecimiento. Laspatologías cardiovasculares, junto al desarrollo de calcificaciones en lapared vascular, presentan una incidencia y prevalencia entre los enfermos con ERC muy superior a la que se observa en la población general.El desarrollo decalcificaciones cardiovasculares es unhallazgo habitual en los enfermos con ERC, sobre todo cuando estos enfermos requieren terapia renal sustitutiva con hemodiálisis (HD). De hecho, entre estos pacientes, las ECV constituyen la principal causa de morbi-mortalidad,aunque numerosas evidencias indican un carácter plurietiológico para las ECV en los enfermos con ERC.El incremento de estas patologías entre los enfermos en HDsugiere que existen elementos inherentes a la propia HD queactúan como factor patogénico en el desarrollo de las ECV.La caracterización de estos factores para desarrollar elementos de ayuda diagnóstica que permitan identificar enfermos en HD en riesgode padecer ECV, y desarrollar terapias que eviten el desarrollo de estas patologíases el objetivo de nuestro grupo de investigaciónAging is considered a risk factor for the development of cardiovascular diseases (CVD), and the endothelial senescence process is the trigger for ischemic pathologies and CVD, such as arteriosclerosis. In endothelial senescence, cells lose their proliferation capacity becauseof damaging agents among themoxidative stress and/or the inflammation generated in the aging process. Endothelial senescence stimulatesthe development of pathologies associated with age, likeCVD and chronic kidney disease (CKD). Cardiovascular pathologiesassociatedwith the development of calcifications in the vascular section, present an incidence and prevalence among patients with CKD higher compared withthe general population. The development of cardiovascular calcifications is a common finding in patients with CKD, especially when these patients are underrenal replacement therapy with hemodialysis (HD). Among these patients, CVD are the maincause of morbidity and mortality, although the evidence indicates a multietiological characterfor CVD in patients with CKD. The increase in these pathologies, particularly betweenHD patients, may have elements inherent to HD byitself that act as a pathogenic factor in the development of CVD. To date, all studies have focused on the characterization of these factors to develop elements of diagnostic that maydetect HD patients at risk of CVD and in thedeveloping oftherapies that prevent the development of these pathologie

Micropartículas: mediadores del daño endotelial en la insuficiencia renal crónica

En pacientes con insuficiencia renal crónica (IRC) existe una disfunción endotelial que supone uno de los mayores riesgos sobre la incidencia y prevalencia de enfermedad cardiovascular. La relación entre insuficiencia renal crónica y enfermedad vascular es un hecho desde hace décadas. La acumulación de toxinas urémicas en IRC, provoca un daño endotelial que se ve reflejado entre otras cosas, en la variación, composición y número de micropartículas (MPs) que liberan las células del mismo. Las micropartículas, son vesículas de membrana que oscilan entre 100-1000 nm de tamaño que participan en el intercambio de señales entre distintas células. Las MPs producidas por las células endoteliales activadas reflejan el daño endotelial pudiéndose considerar un biomarcador del mismo. En nuestro estudio hemos desarrollado un modelo in vitro de IRC con indoxil sulfato y p-cresol, dos de las toxinas más importantes en esta enfermedad, para evaluar el papel de las micropartículas endoteliales (MPEs) como mediadores del daño endotelial. También queremos determinar que procesos celulares pueden verse alterados por MPEs de génesis patológica. Los resultados obtenidos muestran que las MPEs producidas bajo el efecto de las toxinas anteriormente mencionadas median en el daño endotelial por disminución en la proliferación y reparación de herida y un aumento de la senescencia. Además también hemos demostrado que la producción de MPEs liberadas bajo el efecto de ambas toxinas difiere de las producidas por las células en condiciones fisiológicas, no sólo en número, sino también en concentración proteic

Mechanisms of Cardiovascular Disorders in Patients With Chronic Kidney Disease: A Process Related to Accelerated Senescence

Cardiovascular diseases (CVDs), especially those involving a systemic inflammatory process such as atherosclerosis, remain the leading cause of morbidity and mortality in patients with chronic kidney disease (CKD). CKD is a systemic condition affecting approximately 10% of the general population. The prevalence of CKD has increased over the past decades because of the aging of the population worldwide. Indeed, CVDs in patients with CKD constitute a premature form of CVD observed in the general population. Multiple studies indicate that patients with renal disease undergo accelerated aging, which precipitates the appearance of pathologies, including CVDs, usually associated with advanced age. In this review, we discuss several aspects that characterize CKD-associated CVDs, such as etiopathogenic elements that CKD patients share with the general population, changes in the cellular balance of reactive oxygen species (ROS), and the associated process of cellular senescence. Uremia-associated aging is linked with numerous changes at the cellular and molecular level. These changes are similar to those observed in the normal process of physiologic aging. We also discuss new perspectives in the study of CKD-associated CVDs and epigenetic alterations in intercellular signaling, mediated by microRNAs and/or extracellular vesicles (EVs), which promote vascular damage and subsequent development of CVD. Understanding the processes and factors involved in accelerated senescence and other abnormal intercellular signaling will identify new therapeutic targets and lead to improved methods of diagnosis and monitoring for patients with CKD-associated CVDs.Instituto de Salud Carlos IIISociedad Española de NefrologíaUniversidad de AlcaláGrupo Santande

Microvesicles from the plasma of elderly subjects and from senescent endothelial cells promote vascular calcification

Vascular calcification is commonly seen in elderly people, though it can also appear in middle-aged subjects affected by premature vascular aging. The aim of this work is to test the involvement of microvesicles (MVs) produced by senescent endothelial cells (EC) and from plasma of elderly people in vascular calcification. The present work shows that MVs produced by senescent cultured ECs, plus those found in the plasma of elderly subjects, promote calcification in vascular smooth muscle cells. Only MVs from senescent ECs, and from elderly subjects' plasma, induced calcification. This ability correlated with these types of MVs' carriage of: a) increased quantities of annexins (which might act as nucleation sites for calcification), b) increased quantities of bonemorphogenic protein, and c) larger Ca contents. The MVs of senescent, cultured ECs, and those present in the plasma of elderly subjects, promote vascular calcification. The present results provide mechanistic insights into the observed increase in vascular calcification-related diseases in the elderly, and in younger patients with premature vascular aging, paving the way towards novel therapeutic strategies.Instituto de Salud Carlos IIIRed de Investigación RenalUniversidad de AlcaláConsejería de Innovación, Ciencia y Empresa, Junta de AndalucíaFondos Feder Europea

Effect of Kidney Transplantation on Accelerated Immunosenescence and Vascular Changes Induced by Chronic Kidney Disease.

Kidney transplantation is the best option for patients with end-stage renal disease. Despite the improvement in cardiovascular burden (leading cause of mortality among patients with chronic kidney disease), cardiovascular adverse outcomes related to the inflammatory process remain a problem. Thus, the aim of the present study was to characterize the immune profile and microvesicles of patients who underwent transplantation. We investigated the lymphocyte phenotype (CD3, CD4, CD8, CD19, and CD56) and monocyte phenotype (CD14, CD16, CD86, and CD54) in peripheral blood, and endothelium-derived microvesicles (annexin V+CD31+CD41&-) in plasma of patients with advanced chronic kidney disease (n = 40), patients with transplantation (n = 40), and healthy subjects (n = 18) recruited from the University Hospital "12 de Octubre" (Madrid, Spain). Patients with kidney transplantation had B-cell lymphopenia, an impairment in co-stimulatory (CD86) and adhesion (CD54) molecules in monocytes, and a reduction in endothelium-derived microvesicles in plasma. The correlations between those parameters explained the modifications in the expression of co-stimulatory and adhesion molecules in monocytes caused by changes in lymphocyte populations, as well as the increase in the levels of endothelial-derived microvesicles in plasma caused by changes in lymphocyte and monocytes populations. Immunosuppressive treatment could directly or indirectly induce those changes. Nevertheless, the particular characteristics of these cells may partly explain the persistence of cardiovascular and renal alterations in patients who underwent transplantation, along with the decrease in arteriosclerotic events compared with advanced chronic kidney disease. In conclusion, the expression of adhesion molecules by monocytes and endothelial-derived microvesicles is related to lymphocyte alterations in patients with kidney transplantation.Instituto de Salud Carlos IIISociedad Española de NefrologíaComunidad de MadridFondo Social Europe