Sagrario Soriano

Carbamylated low-density lipoprotein induces oxidative stress and accelerated senescence in human endothelial progenitor cells

Carbamylated low‐density lipoprotein (cLDL) plays a role in atherosclerosis. In this study we evaluate the effect of uremia on LDL carbamylation and the effect of cLDL and oxidized LDL (oxLDL;200 µg/ml) on number, function, and genomic stability of endothelial progenitor cells (EPCs) obtained from healthy volunteers. cLDL was generated after incubation of native LDL (nLDL) with uremic serum from patients with chronic kidney disease (CKD) stages 2–4. Oxidative stress was measured by flow cytometry and fluorescent microscopy, mitochondrial depolarization by flow cytometry, senescence by β‐galactosidase activity and telomere length, and DNA damage by phosphorylated histone H2AX (γH2AX). The percentage of cLDL by uremic serum was related to the severity of CKD. Compared with nLDL, cLDL induced an increase in oxidative stress (62±5 vs. 8±3%, P<0.001) and cells with mitochondrial depolarization (73±7 vs. 9±5%, P<0.001), and a decrease in EPC proliferation and angiogenesis. cLDL also induced accelerated senescence (73±16 vs. 12±9%, P≪ 0.001), which was associated with a decrease in the expression of γH2AX (62±9 vs. 5±3%, P<0.001). The degree of injury induced by cLDLwas comparable to that observed with oxLDL. This study supports the hypothesis that cLDL triggers genomic damage in EPCs, resulting in premature senescence. We can, therefore, hypothesize that EPCs injury by cLDL contributes to an increase in atherosclerotic disease in CKD.—Carracedo, J., Merino, A., Briceño, C., Soriano, S., Buendía, P., Calleros, L., Rodriguez, M., Martín‐Malo, A., Aljama, P., Ramírez, R. Carbamy‐lated low‐density lipoprotein induces oxidative stress and accelerated senescence in human endothelial progenitor cells. FASEBJ. 25, 1314–1322 (2011). www.fasebj.org

Effects of intravenous iron on mononuclear cells during the haemodialysis session

BACKGROUND This study analysed, in vivo and in vitro, the effects of four different intravenous iron preparations (iron gluconate, iron sucrose, iron dextran and ferric carboxymaltose) on activation and damage of mononuclear cells. METHODS A randomized prospective study was conducted in 10 haemodialysis (HD) patients. Blood samples were collected at baseline (T0); 1 h after starting HD, just before the iron or saline administration (T1); 30 min after the iron or saline infusion (T2) and at the end of HD (T3). In addition, peripheral blood mononuclear cells from 10 healthy individuals and 9 chronic kidney disease Stage-5 (CKD-5) without HD treatment were cultured with the 4 iron preparations. RESULTS Iron infusion during the HD session increased the percentage of mononuclear cells with reactive oxygen species (ROS) production, Inter-Cellular Adhesion Molecule-1 (ICAM-1) and apoptosis. There were no significant differences between the four iron preparations. Culture of mononuclear cells from healthy individuals and CKD-5 patients with the different iron preparations resulted in a significant increase in ROS, ICAM-1 and apoptosis as compared with control. In an additional study, the effect of original iron sucrose formulation on mononuclear cells was compared with that of one generic formulation. The generic formulation produced a greater increase in ROS, ICAM-1 and apoptosis than the original iron sucrose. CONCLUSIONS Our results suggest that intravenous iron has deleterious effects on mononuclear cells. The four iron compounds evaluated produced similar effects on oxidative stress, cell activation and apoptosis. However, the effects of iron compounds with the same formulation were different, thus further investigation may be required to establish the safety of iron preparations that theoretically have the same composition.

Klotho Prevents NFκB Translocation and Protects Endothelial Cell From Senescence Induced by Uremia

In patients with renal disease, uremia raises oxidative stress and senescence in endothelial cells, which can lead to endothelial dysfunction and cardiovascular disease. Klotho protein is a β-glucuronidase capable of hydrolyzing steroid β-glucuronides. This protein is recognized as an antiaging gene, that modulate both stress-induced senescence and functional response. The aim of the study was to investigate how senescence and oxidative stress induced by uremia in endothelial cells affects Klotho expression and whether intra or extracellular Klotho has effects on the response of these cells. Senescence and oxidative stress was obtained by exposure to uremic serum. Telomere length, the enzyme β-galactosidase, and oxidative stress were studied by flow cytometry. Nuclear factor kappa B activity was determined by electrophoretic mobility shift assay. The expression of Klotho decreased with the uremia and preceded the manifestations of cell aging. Levels of intracellular Klotho decreases associated to endothelial senescence, and exogenous Klotho prevents cellular senescence by inhibiting the increase in oxidative stress induced by uremia and diminished the nuclear factor kappa B-DNA binding ability.

Cellular senescence determines endothelial cell damage induced by uremia.

Renal dysfunction is closely associated with endothelial damage leading to cardiovascular disease. However, the extent to which endothelial damage induced by uremia is modulated by aging is poorly known. Aging can render endothelial cells more susceptible to apoptosis through an oxidative stress-dependent pathway. We examined whether senescence-associated to oxidative stress determines the injury induced by the uremia in endothelial cells. Human umbilical vein endothelial cells (HUVEC) was incubated with human uremic serum and, in the animal model, endothelial cells were obtained from aortas of uremic and no uremic rats. Vitamin C was used to prevent oxidative stress. Senescence, assessed by telomere length and enzyme-betagalactosidase (β-gal), reactive oxygen species (ROS), mitochondrial depolarization (JC-1 probe), caspase 3, and apoptosis were determined by flow cytometry. NF-κB activity was determined by Western blot. Uremic serum increased ROS and NF-κB in young and aging HUVEC. However only in aging cells, uremic serum induced apoptosis (vs young HUVEC, p<0.01). The endothelial damage induced by uremia seems to be related with the increased oxidative stress, since in both HUVEC and in the experimental model of renal disease in rats, vitamin C prevents endothelial apoptosis. However, vitamin C did not decrease the oxidative stress associated to senescence. These results showed that as compared with young cells, senescent cells have high sensitivity to damage associated to the oxidative stress induced by the uremia. Consequently, protecting senescent endothelial cells from increased oxidative stress might be an effective therapeutic approach in the treatment of vascular disorders in chronic kidney diseases.

CD14+CD16+ monocytes from chronic kidney disease patients exhibit increased adhesion ability to endothelial cells.

Chronic kidney disease (CKD) patients present an inflammatory process that induces endothelial damage and therefore plays a role in the high rates of cardiovascular morbidity and mortality reported in these patients. Although new therapies have reduced the elevated serum levels of inflammatory mediators such as cytokines and CRP in CKD patients, the rise in the level of activated immunocompetent cells is maintained in peripheral blood, which appears to play a prominent role in the endothelial damage suffered by these patients. CD14+CD16+ monocytes are a subset of activated monocytes that are found in greater numbers in the peripheral blood of CKD patients. The increased presence of these cells is related to the endothelial damage suffered by these patients. However, the mechanism through which these cells damage the vascular endothelium is still unclear. One of the characteristics that differentiate CD14+CD16+ monocytes is their powerful ability to produce inflammatory cytokines, which may be responsible for causing damage to endothelial cells. However, it is difficult to imagine that the cytokines produced by a relatively small proportion of these cells are capable of damaging the endothelium. For this reason, we have suggested that these cells do not release their cytokines into the bloodstream, but that they possess cellular mechanisms that lead them to produce and release cytokines after adhering to the layer of endothelial cells. This hypothesis is based on the fact that unlike the CD14++CD16- monocytes found in healthy subjects, CD14+CD16+ monocytes in CKD patients show a high level of expression of chemokines that favors their migration to the vascular wall, and a low level of chemokines such as CCR2 that would prevent such migration. Furthermore, these CD14+CD16+ monocytes express a large number of adhesion molecules, which helps them attach to endothelial cells. In view of this scenario, it is easy to suggest that a moderate number of CD14+CD16+ monocytes might well be capable of producing endothelial damage; therefore, the rise in the number of these cells in CKD patients may play an important role in the development of vascular disease.

Endothelial damage and vascular calcification in patients with chronic kidney disease

Vascular calcification (VC) is a frequent complication of chronic kidney disease (CKD) and is a predictor of cardiovascular morbidity and mortality. In the present study, we investigated the potential involvement of endothelial microparticles (MPs) and endothelial progenitor cells (EPCs) in the generation of VC in CKD patients. The number of circulating EMPs is greater in patients with VC than without VC (307 ± 167 vs. 99 ± 75 EMPs/μl, P < 0.001). The percentage of EPCs is significantly lower in patient with VC than in patients without VC (0.14 ± 0.11% vs. 0.25 ± 0.18%, P = 0.002). The number of EPCs expressing osteocalcin (OCN) was higher in VC patients (349 ± 63 cells/100,000) than in non-VC patients (139 ± 75 cells/100,000, P < 0.01). In vitro, MPs obtained from CKD patients were able to induce OCN expression in EPCs from healthy donors; the increase in OCN expression was more accentuated if MPs were obtained from CKD patients with VC. MPs from CKD patients also induced OCN expression in vascular smooth muscle cells and fibroblasts. In CKD patients, the rise in endothelial MPs associated with a decrease in the number of EPCs, suggesting an imbalance in the processes of endothelial damage and repair in CKD patients, mainly those with VC. Our results suggest that EPCs, through OCN expression, may directly participate in the process of VC.

Lymphocyte Apoptosis: Role of Uremia and Permeability of Dialysis Membrane

Background: Uremia is associated to host defense mechanism disorders. Lymphocyte apoptosis, which may cause alteration of the immune system, is increased in uremic patients. The aim of the present study was to determine if, in addition to uremia, dialysis membranes with different biocompatibility and permeability have an effect on lymphocyte apoptosis. Methods: Cell apoptosis and Fas expression were assessed using flow cytometry in four groups of patients: (1) uremic non-dialyzed (Non-D) patients; (2) hemodialysis (HD) patients on hemophan; (3) low-flux polysulfone, and (4) high-flux polysulfone membrane. Ten healthy volunteers were used ascontrols. Results: At baseline, lymphocytes from patients on hemophan showed an increase in apoptosis (18.4 ± 6.9%) as compared with Non-D (7.2 ± 2.8%; p < 0.001), low-flux (6.4 ± 2.4%; p < 0.001), high-flux (2.6 ± 1.2%; p < 0.001) and controls (2.0 ± 1.0%; p < 0.001). Fas expression was similar in lymphocytes from Non-D and hemophan dialyzed patients (40.5 ± 5% vs. 40.4 ± 6%), and in both groups it was greater than low-flux (30%±7%; p < 0.001), high-flux (11 ± 4%; p < 0.001) and controls (12.6 ± 3%; p < 0.001). When lymphocytes were cultured for 48 h, apoptosis was similar in Non-D and hemophan (27.0 ± 4.3% vs. 27.1 ± 6.9%); apoptosis of lymphocyte from patients on low-flux (14.1 ± 3.5%) was greater than on high-flux polysulfone membrane (7.0 ± 2.0%; p < 0.001). Conclusion: These findings suggest that in dialysis patients lymphocyte apoptosis is influenced not only by the biocompatibility but also by the permeability of the dialysis membrane.

Monocytes from dialysis patients exhibit characteristics of senescent cells: does it really mean inflammation?

Hemodialysis treatment induces mononuclear cell activation particularly if cellulosic hemodialysis membrane is used. In normal cells, repeated activation induce a process of accelerate cellular senescence. The aim of the present study was to evaluate whether the mononuclear cell activation associated to hemodialysis with cellulosic membranes favors a process of accelerate senescence in mononuclear cells. Our results show that mononuclear cells from patients dialyzed with cellulosic membranes, exhibit: decrease telomere length, increase percentage of cells CD14dim/CD16bright and increase production of IL-1beta, IL1Ra and IL6 cytokines. After culture in vitro, these cells shown increase susceptibility to undergoing spontaneous apoptosis, that is enhanced by IL-4 and prevented by IL-1beta or LPS. All of these characteristics have been reported associated to senescence of monocytes, and not are observed in cells from controls subjects or patients dialyzed with non-cellulosic membranes, suggesting that hemodialysis with cellulosic membranes induce a process of senescence in mononuclear cells.

Tandem Plasmapheresis and Hemodialysis: Efficacy and Safety

Background: Hemodialysis (HD) and plasmapheresis (PE) are usually performed independently on patients who require renal replacement therapy. We analyzed our experience using a technique that performs both modalities simultaneously. Methods: Thirty-six patients who were treated with 287 tandem PE and HD (TPH) sessions (mean 7.97 ± 5.6 per patient) were included. PE was connected 30 min after HD started. The mean HD blood flow was 313.7 ± 44 mL/min, the mean PE blood flow was 141 ± 25 mL/min, and the duration of TPH was no longer than 240 min. The heparin dose was similar to that used for a standard HD procedure. Results: In 287 TPH sessions performed, 10.45% experienced minor complications. There were significant changes in mean blood pressure after connection of the PE system. However, these differences were not clinically relevant since patients remained asymptomatic and they did not require saline infusion. At the end of treatment, 38.9% of patients were no longer dependent on dialysis. Conclusions: Our results suggest that TPH is a safe and effective treatment that decreases exposure to an extracorporeal circuit, reducing the risks that are associated with anticoagulation agents and improving the comfortability of the patient.

Hemodiafiltration With Endogenous Reinfusion Improved Microinflammation and Endothelial Damage Compared With Online-Hemodiafiltration: A Hypothesis Generating Study.

Hemodiafiltration with endogenous reinfusion (HFR) after ultrafiltrate passage through a resin cartridge combines adsorption, convection, and diffusion. Our prospective single-center crossover study compared HFR and online-hemodiafiltration (OLHDF) effects on two uremic toxins and 13 inflammatory, endothelial status, or oxidative stress markers. After an 8-week run-in period of high-flux hemodialysis, 17 eligible stable dialysis patients (median age 65 years, 10 male) without overt clinical inflammation were scheduled for four 8-week periods in the sequence: HFR/OLHDF/HFR/OLHDF. Relative to OLHDF, HFR was associated with greater indoxyl sulfate removal and lesser abnormalities in all other study variables, namely circulating interleukin-6, tumor necrosis factor-alpha, proportions of activated proinflammatory (CD14+CD16+, CD14++CD16+) monocytes, endothelial progenitor cells, apoptotic endothelial microparticles, vascular endothelial growth factor, vascular cellular adhesion molecule, angiopoietins 2 and 1, annexin V, and superoxide dismutase. Differences were significant (P < 0.05) in median values of 13/15 variables. Study period comparisons were generally consistent with dialysis technique comparisons, as were data from the subgroup completing all study periods (n = 9). Our investigation provides hypothesis-generating results suggesting that compared with OLHDF, HFR improves protein-bound toxin removal, inflammatory and endothelial status, and oxidative stress.