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.

Losartan prevents the development of the pro-inflammatory monocytes CD14+CD16+ in haemodialysis patients.

BACKGROUND: The principal cause of mortality in haemodialysis (HD) patients is cardiovascular disease, which is linked to chronic inflammation. Recent studies have demonstrated that angiotensin II receptor AT1 antagonists have anti-inflammatory properties. In this study, we evaluated the effect of losartan on CD14+CD16+ monocytes in HD patients. In addition, we developed an in vitro model to study the mechanisms by which losartan modulates these cells. METHODS: We divided 18 HD patients into two groups, based on anti-hypertensive treatment: 9 patients were treated with losartan (losartan group) and 9 received other anti-hypertensive drugs that did not affect the renin-angiotensin axis (no-losartan group). Losartan was withdrawn in five patients from the losartan group for 2 months. Ten healthy subjects were included as controls. Invitro, we studied the differentiation of monocytes from healthy donors on stimulation with interleukin (IL)-10, IL-4 and granulocyte monocytes colony-stimulating factor with or without losartan in the culture medium. RESULTS: In patients who were taking losartan, the percentage of monocytes that expressed CD14+CD16+ was lower compared with patients in the no-losartan group. The percentage of CD14+CD16+ was similar in the losartan group and healthy subjects. When losartan was withdrawn from five patients in the losartan group, the percentage of CD14+CD16+ monocytes increased compared with before withdrawal. In vitro, when we added losartan to the culture medium, CD14++CD16- monocytes failed to differentiate into CD14+CD16+ cells. CONCLUSION: Losartan acts as an immunomodulator that prevents the development of CD14+CD16+ pro-inflammatory monocytes in HD patients.

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.

Efficiency of Original versus Generic Intravenous Iron Formulations in Patients on Haemodialysis.

AIMS: The appropriate use of intravenous (i.v.) iron is essential to minimise the requirements for erythropoiesis-stimulating agents (ESAs). The clinical efficacy of generic i.v. iron compared to the original formulation is controversial. We evaluated the changes that were induced after switching from a generic i.v. iron to an original formulation in a stable, prevalent haemodialysis (HD) population. METHODS: A total of 342 patients were included, and the follow-up period was 56 weeks for each formulation. Anaemia parameters and doses of ESA and i.v. iron were prospectively recorded before and after the switch from generic to original i.v. iron. RESULTS: To maintain the same haemoglobin (Hb) levels after switching from the generic to the original formulation, the requirements for i.v. iron doses were reduced by 34.3% (from 52.8±33.9 to 34.7±31.8 mg/week, p<0.001), and the ESA doses were also decreased by 12.5% (from 30.6±23.6 to 27±21 µg/week, p<0.001). The erythropoietin resistance index declined from 8.4±7.7 to 7.4±6.7 IU/kg/week/g/dl after the switch from the generic to the original drug (p = 0.001). After the switch, the transferrin saturation ratio (TSAT) and serum ferritin levels rose by 6.8% (p<0.001) and 12.4% (p = 0.001), respectively. The mortality rate was similar for both periods. CONCLUSIONS: The iron and ESA requirements are lower with the original i.v. iron compared to the generic drug. In addition, the uses of the original formulation results in higher ferritin and TSAT levels despite the lower dose of i.v. iron. Further studies are necessary to analyse the adverse effects of higher i.v. iron dosages.

Effectiveness of haemodiafiltration with ultrafiltrate regeneration in the reduction of light chains in multiple myeloma with renal failure.

Acute kidney failure in multiple myeloma (MM) occurs in 12%-20% of patients and is a poor prognostic factor for patient survival. Recent studies have shown that dialysis with a High-Cut-Off membrane (HCO) removes free light chains (FLC) effectively although with significant albumin loss. Other adsorption-based techniques, such as haemodiafiltration with ultrafiltrate regeneration by adsorption in resin (SUPRA-HFR), have not been studied. We present three cases of MM, all haemodialysis-dependent since diagnosis. Two cases were IgG kappa and one was IgA lambda. All patients were treated with chemotherapy and SUPRA-HFR. The aim of this study was to evaluate the effectiveness of SUPRA-HFR in the reduction of FLC and its effect on albumin. We collected blood samples pre- and post-dialysis, and ultrafiltrate (UF) samples pre- and post-resin 5 minutes into the session and 5 minutes from the end. The mean reduction rate of FLC in blood per session in the three patients was 53% and 63% (kappa) and 38% (lambda). In the UF, the mean FLC reduction rate was close to 99%, both at the start and at the end of dialysis, without the removal of albumin. With the results obtained we can conclude that this technique achieves an effective reduction of FLC, which is maintained throughout the session, without resin saturation and without albumin loss. Therefore, SUPRA-HFR is effective as an adjunctive therapy for MM.

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.

The imbalance in the ratio of Th1 and Th2 helper lymphocytes in uraemia is mediated by an increased apoptosis of Th1 subset.

BACKGROUND: In uraemia there is a reduction in the total number of T lymphocytes and an imbalance in the ratio of Th1/Th2 T-helper (Th) lymphocytes. A higher rate of apoptosis in T lymphocytes has been reported in haemodialysis patients. The aims of the present study were to assess the Th1/Th2 pattern in uraemia and to evaluate whether a relative increase in Th1 apoptosis may explain the Th1/Th2 imbalance observed in uraemic patients. METHODS: Seventeen non-dialysed uraemic patients were evaluated; eight healthy volunteers served as controls. Intracellular interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) were measured by direct intracellular immunofluorescence and flow cytometry. Apoptosis was determined by flow cytometry using annexin V or TUNEL. Mechanisms of apoptosis were assessed by determination of Fas and Bcl-2 expression. RESULTS: Cell production of cytokines is significantly higher in uraemic patients than in controls. In addition, in uraemic patients only 5.1+/-2.1% of the T lymphocytes contained IFN-gamma (Th1 cells) while 61.9 +/- 14.8% contained IL-4 (Th2 cells) (P < 0.0001). The percentage of apoptosis was 29.6 +/- 6.3% and 4.7 +/- 1.6% in Th1 and Th2 lymphocytes, respectively (P < 0.001). Fas expression was higher in Th1 than in Th2 cells and the expression of Bcl-2 was lower in Th1 than in Th2 cells. The apoptosis induced by anti-Fas antibodies was similar in both types of lymphocytes. CONCLUSIONS: In uraemia there is a reduction in the proportion of Th1 lymphocytes due to a higher rate of apoptosis in this subset of lymphocytes. Th1 from uraemic patients show a higher expression of Fas and a lower expression of Bcl-2 than Th2. This makes uraemic Th1 cells more susceptible to apoptosis. The Th1/Th2 imbalance may contribute to alterations in cellular immunity observed in chronic kidney disease patients.