PPAR-γ agonist rosiglitazone protects peritoneal membrane from dialysis fluid-induced damage.

Exposure to non-physiological solutions during peritoneal dialysis (PD) produces structural alterations to the peritoneal membrane and ultrafiltration dysfunction. The high concentration of glucose and glucose degradation products in standard PD fluids induce a local diabetic environment, which leads to the formation of advanced glycation end products (AGEs) that have an important role in peritoneal membrane deterioration. Peroxisome proliferator-activated receptor γ (PPAR-γ) agonists are used to treat type II diabetes and they have beneficial effects on inflammation, fibrosis, and angiogenesis. Hence, we evaluated the efficacy of the PPAR-γ agonist rosiglitazone (RSG) in ameliorating peritoneal membrane damage in a mouse PD model, and we analyzed the mechanisms underlying the protection offered by RSG. Exposure of the peritoneum to PD fluid resulted in AGEs accumulation, an inflammatory response, the loss of mesothelial cell monolayer and invasion of the compact zone by mesothelial cells, fibrosis, angiogenesis, and functional impairment of the peritoneum. Administration of RSG diminished the accumulation of AGEs, preserved the mesothelial monolayer, decreased the number of invading mesothelial cells, reduced fibrosis and angiogenesis, and improved peritoneal function. Interestingly, instead of reducing the leukocyte recruitment, RSG administration enhanced this process and specifically, the recruitment of CD3+ lymphocytes. Furthermore, RSG treatment augmented the levels of the anti-inflammatory cytokine interleukin (IL)-10 and increased the recruitment of CD4+ CD25+ FoxP3+ cells, suggesting that regulatory T cells mediated the protection of the peritoneal membrane. In cell-culture experiments, RSG did not prevent or reverse the mesothelial to mesenchymal transition, although it decreased mesothelial cells apoptosis. Accordingly, RSG appears to produce pleiotropic protective effects on the peritoneal membrane by reducing the accumulation of AGEs and inflammation, and by preserving the mesothelial cells monolayer, highlighting the potential of PPAR-γ activation to ameliorate peritoneal deterioration in PD patients.

Peritoneal dialysis and epithelial-to-mesenchymal transition of mesothelial cells.

BACKGROUND: During continuous ambulatory peritoneal dialysis, the peritoneum is exposed to bioincompatible dialysis fluids that cause denudation of mesothelial cells and, ultimately, tissue fibrosis and failure of ultrafiltration. However, the mechanism of this process has yet to be elucidated. METHODS: Mesothelial cells isolated from effluents in dialysis fluid from patients undergoing continuous ambulatory peritoneal dialysis were phenotypically characterized by flow cytometry, confocal immunofluorescence, Western blotting, and reverse-transcriptase polymerase chain reaction. These cells were compared with mesothelial cells from omentum and treated with various stimuli in vitro to mimic the transdifferentiation observed during continuous ambulatory peritoneal dialysis. Results were confirmed in vivo by immunohistochemical analysis performed on peritoneal-biopsy specimens. RESULTS: Soon after dialysis is initiated, peritoneal mesothelial cells undergo a transition from an epithelial phenotype to a mesenchymal phenotype with a progressive loss of epithelial morphology and a decrease in the expression of cytokeratins and E-cadherin through an induction of the transcriptional repressor snail. Mesothelial cells also acquire a migratory phenotype with the up-regulation of expression of alpha2 integrin. In vitro analyses point to wound repair and profibrotic and inflammatory cytokines as factors that initiate mesothelial transdifferentiation. Immunohistochemical studies of peritoneal-biopsy specimens from patients undergoing continuous ambulatory peritoneal dialysis demonstrate the expression of the mesothelial markers intercellular adhesion molecule 1 and cytokeratins in fibroblast-like cells entrapped in the stroma, suggesting that these cells stemmed from local conversion of mesothelial cells. CONCLUSIONS: Our results suggest that mesothelial cells have an active role in the structural and functional alteration of the peritoneum during peritoneal dialysis. The findings suggest potential targets for the design of new dialysis solutions and markers for the monitoring of patients.

Ex vivo analysis of dialysis effluent-derived mesothelial cells as an approach to unveiling the mechanism of peritoneal membrane failure.

During peritoneal dialysis (PD), the peritoneum is exposed to bioincompatible dialysis fluids, which causes progressive fibrosis and angiogenesis and, ultimately, ultrafiltration failure. In addition, repeated episodes of peritonitis or hemoperitoneum may accelerate all these processes. Fibrosis has been classically considered the main cause of peritoneal membrane functional decline. However, in parallel with fibrosis, the peritoneum also displays increases in capillary number (angiogenesis) and vasculopathy in response to PD. Nowadays, there is emerging evidence pointing to peritoneal microvasculature as the main factor responsible for increased solute transport and ultrafiltration failure. However, the pathophysiologic mechanism(s) involved in starting and maintaining peritoneal fibrosis and angiogenesis remain(s) elusive. Peritoneal stromal fibroblasts have been considered (for many years) the cell type mainly involved in structural and functional alterations of the peritoneum; whereas mesothelial cells have been considered mere victims of peritoneal injury caused by PD. Recently, ex vivo cultures of effluent-derived mesothelial cells, in conjunction with immunohistochemical analysis of peritoneal biopsies from PD patients, have identified mesothelial cells as culprits, at least in part, in peritoneal membrane deterioration. This review discusses recent findings that suggest new peritoneal myofibroblastic cells may arise from local conversion of mesothelial cells by epithelial-to-mesenchymal transition during the repair responses that take place in PD. The transdifferentiated mesothelial cells may retain a permanent mesenchymal state, as long as initiating stimuli persist, and contribute to PD-induced fibrosis and angiogenesis, and hence to membrane failure. Future therapeutic interventions could be designated in order to prevent or reverse epithelial-to-mesenchymal transition of mesothelial cells, or its pernicious effects.

Nebivolol, a ß1-adrenergic blocker, protects from peritoneal membrane damage induced during peritoneal dialysis.

UNLABELLED: Peritoneal dialysis (PD) is a form of renal replacement treatment, which employs the peritoneal membrane (PM) to eliminate toxins that cannot be removed by the kidney. The procedure itself, however, contributes to the loss of the PM ultrafiltration capacity (UFC), leading consequently to the technique malfunction. ß-blockers have been considered deleterious for PM due to their association with loss of UFC and induction of fibrosis. Herein we analyzed the effects of Nebivolol, a new generation of ß1-blocker, on PM alterations induced by PD fluids (PDF).In vitro: We found that mesothelial cells (MCs) express ß1-adrenergic receptor. MCs were treated with TGF-ß to induce mesothelial-to-mesenchymal transition (MMT) and co-treated with Nebivolol. Nebivolol reversed the TGF-ß effects, decreasing extracellular matrix synthesis, and improved the fibrinolytic capacity, decreasing plasminogen activator inhibitor-1 (PAI-1) and increasing tissue-type plasminogen activator (tPA) supernatant levels. Moreover, Nebivolol partially inhibited MMT and decreased vascular endothelial growth factor (VEGF) and IL-6 levels in supernatants.In vivo: Twenty-one C57BL/6 mice were divided into 3 groups. Control group carried a catheter without PDF infusion. Study group received intraperitoneally PDF and oral Nebivolol during 30 days. PDF group received PDF alone. Nebivolol maintained the UFC and reduced PM thickness, MMT and angiogenesis promoted by PDF. It also improved the fibrinolytic capacity in PD effluents decreasing PAI-1 and IL-8 and increased tPA levels. CONCLUSION: Nebivolol protects PM from PDF-induced damage, promoting anti-fibrotic, anti-angiogenic, anti-inflammatory and pro-fibrinolytic effects.

Mesenchymal conversion of mesothelial cells as a mechanism responsible for high solute transport rate in peritoneal dialysis: role of vascular endothelial growth factor.

BACKGROUND: During peritoneal dialysis (PD), the peritoneum is exposed to bioincompatible dialysis fluids that cause epithelial-to-mesenchymal transition of mesothelial cells, fibrosis, and angiogenesis. Ultrafiltration failure is associated with high transport rates and increased vascular surface, indicating the implication of vascular endothelial growth factor (VEGF). Sources of VEGF in vivo in PD patients remain unclear. We analyzed the correlation between epithelial-to-mesenchymal transition of mesothelial cells and both VEGF level and peritoneal functional decline. METHODS: Effluent mesothelial cells were isolated from 37 PD patients and analyzed for mesenchymal conversion. Mass transfer coefficient for creatinine (Cr-MTC) was used to evaluate peritoneal function. VEGF concentration was measured by using standard procedures. Peritoneal biopsy specimens from 12 PD patients and 6 controls were analyzed immunohistochemically for VEGF and cytokeratin expression. RESULTS: Nonepithelioid mesothelial cells from effluent produced a greater amount of VEGF ex vivo than epithelial-like mesothelial cells (P < 0.001). Patients whose drainage contained nonepithelioid mesothelial cells had greater serum VEGF levels than those with epithelial-like mesothelial cells in their effluent (P < 0.01). VEGF production ex vivo by effluent mesothelial cells correlated with serum VEGF level (r = 0.6; P < 0.01). In addition, Cr-MTC correlated with VEGF levels in culture (r = 0.8; P < 0.001) and serum (r = 0.35; P < 0.05). Cr-MTC also was associated with mesothelial cell phenotype. VEGF expression in stromal cells, retaining mesothelial markers, was observed in peritoneal biopsy specimens from high-transporter patients. CONCLUSION: These results suggest that mesothelial cells that have undergone epithelial-to-mesenchymal transition are the main source of VEGF in PD patients and therefore may be responsible for a high peritoneal transport rate.

Peritoneal dialysis solutions inhibit the differentiation and maturation of human monocyte-derived dendritic cells: effect of lactate and glucose-degradation products.

Peritoneal dialysis (PD) is a well-established therapy for end-stage renal failure, but its efficiency is limited by recurrent peritonitis. As PD solutions impair local inflammatory responses within the peritoneal cavity, we have analyzed their influence on the in vitro maturation of human monocyte-derived dendritic cells (MDDC). Evaluation of MDDC maturation parameters [expression of adhesion and costimulatory molecules, receptor-mediated endocytosis, allogeneic T cell activation, production of tumor necrosis factor alpha, interleukin (IL)-6 and IL-12 p70, and nuclear factor (NF)-kappaB activation] revealed that currently used PD solutions differentially inhibit the lipopolysaccharide (LPS)-induced maturation of MDDC, an inhibition that correlated with their ability to impair the LPS-stimulated NF-kappaB activation. Evaluation of PD components revealed that sodium lactate and glucose-degradation products impaired the acquisition of maturation parameters and NF-kappaB activation in a dose-dependent manner. Moreover, PD solutions impaired monocyte-MDDC differentiation, inhibiting the acquisition of DC markers such as CD1a and DC-specific intercellular adhesion molecule-3 grabbing nonintegrin (CD209). These findings have important implications for the initiation of immune responses under high lactate conditions, such as those occurring within tumor tissues or after macrophage activation.

Immunohistochemical characterization of fibroblast subpopulations in normal peritoneal tissue and in peritoneal dialysis-induced fibrosis.

Peritoneal fibrosis is one of the most common morphological changes observed in continuous ambulatory peritoneal dialysis (CAPD) patients. Both resident fibroblasts and new fibroblast-like cells derived from the mesothelium by epithelial-to-mesenchymal transition are the main cells involved fibrogenesis. In order to establish markers of peritoneal impairment and pathogenic clues to explain the fibrogenic process, we conducted an immunohistochemical study focused on peritoneal fibroblasts. Parietal peritoneal biopsies were collected from four patient groups: normal controls ( n = 15), non-CAPD uremic patients ( n = 17), uremic patients on CAPD ( n = 27) and non-renal patients with inguinal hernia ( n = 12). To study myofibroblastic conversion of mesothelial cells, alpha-smooth muscle actin (SMA), desmin, cytokeratins and E-cadherin were analyzed. The expression of CD34 by fibroblasts was also analyzed. Fibroblasts from controls and non-CAPD uremic patients showed expression of CD34, but no myofibroblastic or mesothelial markers. The opposite pattern was present during CAPD-related fibrosis. Expression of cytokeratins and E-cadherin by fibroblast-like cells and alpha-SMA by mesothelial and stromal cells supports that mesothelial-to-myofibroblast transition occurs during CAPD. Loss of CD34 expression correlated with the degree of peritoneal fibrosis. The immunophenotype of fibroblasts varies during the progression of fibrosis. Myofibroblasts seem to derive from both activation of resident fibroblasts and local conversion of mesothelial cells.

Increased severity of Escherichia coli peritonitis in peritoneal dialysis patients independent of changes in in vitro antimicrobial susceptibility testing.

OBJECTIVE: Despite improvements in peritoneal dialysis (PD) technique, peritonitis continues to be one of the most frequent complications of PD. Nonresolving peritonitis remains a risk for severe anatomical peritoneal changes that may limit the viability of the membrane for dialysis purposes. We have observed remarkably poor outcome of peritonitis caused by Escherichia coli in the past 6 years. With its very low response rate to broad-spectrum antibiotics, the increased severity of E. coli peritonitis deteriorates peritoneal function and affects patient outcome. DESIGN: Retrospective study. SETTING: Two large PD units in two university hospitals. PATIENTS AND METHODS: The total number of patients reviewed was 456. The records of 49 E. coli peritonitis episodes were studied.The observation period started in 1980 and ended in March 2001. Sixteen males and 19 females were included. Severity was defined in terms of days of peritoneal inflammation, lack of response to a potentially useful antibiotic, requirement for catheter removal, and/or laparotomy. Study cases (study group) were those episodes appearing after 1996 (when the first severe cases appeared) and historic controls were episodes occurring before 1996. RESULTS: In the study group, 18 peritonitis episodes developed in 15 patients. In the control group, 31 peritonitis episodes developed in 20 patients. There were no significant differences in clinical presentation; however, the outcome was significantly poorer for the later period. A severe outcome occurred in 50% of study versus 10% of control patients. In fact, 68% of the episodes registered before 1996 were cured in 3 days or less. Concurring with this trend, the numbers of surgical interventions and catheter removals were also higher in the study group. Strikingly, E. coli did not show changes in in vitro susceptibility testing to antibiotics, although the in vivo response was much worse. CONCLUSIONS: We describe a change in the virulence of E. coli peritonitis episodes over the past 5 years leading to a high percentage of treatment failure, which does not depend on antibiotic sensitivity and seems to be dependent on changes in host response mechanisms.

Clinical experience with a new bicarbonate (25 mmol/L)/lactate (10 mmol/L) peritoneal dialysis solution.

OBJECTIVE: Physiological bicarbonate/lactate-based solutions may correct acidosis in a better way than standard lactate-based solutions. In this study, a new 25 mmol/L bicarbonate/10 mmol/L lactate peritoneal dialysis (PD) solution was compared with a standard 35 mmolL lactate solution. DESIGN: This was a prospective open label study. All patients had a 2-week baseline period using the standard lactate solution, followed by 8 weeks on the bicarbonate/ lactate solution and 2 weeks on the lactate-based solution. SETTING: Four Danish and four Spanish nephrology centers. PATIENTS: 40 well-dialyzed (creatinine clearance > 55 L/week/1.73 m2 body surface area) patients on continuous ambulatory PD. INTERVENTIONS: Blood samples were taken for biochemistry (including venous blood gases) at week -2, day 1, weeks 2, 4, and 8, and at follow-up. A physical examination, a peritoneal equilibration test (PET), and quality of life (K/DQOL), ultrafiltration, and adequacy assessments were performed at baseline and at week 8. Vital signs and other safety parameters were followed at each visit. Extraneal (Baxter Healthcare, Castlebar, Ireland) was used by all patients for the long dwell. MAIN OUTCOME MEASURE: Effect on the venous plasma bicarbonate level. RESULTS: Venous plasma bicarbonate levels rose from 24.4 mmol/L when patients were on the pure lactate to 26.1 mmol/L when using the bicarbonate/lactate solution (p < 0.001). When patients were using the bicarbonate/ lactate solution, 66% of values were maintained within the venous normal range of 24-30 mmol/L, versus 46.2% when patients were on the pure lactate solution (p < 0.001). There were no adverse findings with respect to clinical symptoms, vital signs, or physical examination. The PET and adequacy, ultrafiltration, and K/DQOL assessment results were unchanged. CONCLUSIONS: The new 25 mmol/L bicarbonate/ 10 mmol/L lactate solution provided better correction of acidosis than an equivalent 35 mmol/L standard lactate solution, without any safety issues.

Severe peritoneal mononucleosis associated with icodextrin use in continuous ambulatory peritoneal dialysis.

Icodextrin is a glucose polymer obtained from starch hydrolysis. It is used as an osmotic agent at 7.5% for peritoneal dialysis (PD). Its use in PD has been associated with several side effects separate from the one reported here, the most frequent being sterile peritonitis. Recently, three mechanisms have been proposed to explain the occurrence of sterile peritonitis: allergy to dextrin, production of anti-dextran antibodies, and impurities introduced during manufacture. Here, we report a peritoneal mononucleosis outbreak that is highly suggestive of being a consequence of the last-mentioned mechanism. During the period December 2001 to May 2002, a group of 8 Spanish hospitals whose individual PD programs regularly share information and activity reported 29 cases of sterile peritonitis associated with icodextrin use in continuous ambulatory peritoneal dialysis (CAPD) patients [mean age: 60.7 +/- 14.47 years; 8 women (27.59%), 21 men (72.41%); mean time on PD: 25.21 +/- 35.31 months; mean time on icodextrin: 15.17 +/- 11.03 months]. Of the 29 patients, 51.8% showed no symptoms. The remainder presented with mild abdominal discomfort and anorexia. Only 2 patients showed general malaise, severe nausea, fever, and abdominal pain. The initial white cell count in peritoneal effluent was 512 +/- 386 cells/mL (45.0% +/- 28% neutrophils, 44.92% +/- 32.6% mono-nuclear cells, 7.75% +/- 12% eosinophils). In 5 of the patients, we performed an immunophenotype (CD14) study, demonstrating the monocyte nature of 60%-80% (mean: 70.6%) of the cells. Microbiology cultures were always negative. A rechallenge with the same batches of PD fluid was tried. In 100% of the patients, the clinical and cellular patterns relapsed. No short-term changes in peritoneal function have been observed. The manufacturer informed us that the icodextrin was contaminated with a peptidoglycan. In this sterile peritonitis outbreak with a simultaneous, similar clinical presentation in a group of patients treated with icodextrin solution (presumably contaminated with peptidoglycan), clinical outcome was, for the most part, mild-to-moderate. Symptoms disappeared immediately after icodextrin withdrawal and relapsed after rechallenge with the relevant fluid batches. Monocyte cell counts predominated during the episode. Although we cannot rule out an allergic cause, the massive peritoneal mononuclear cell recruitment suggests a particular mechanism. This is a new mechanism for peritoneal cell recruitment in PD.

Pathogenic significance of hypertrophic mesothelial cells in peritoneal effluent and ex vivo culture.

The presence of hypertrophic mesothelial cells (HMCs) in peritoneal effluent (PE) has been considered a possible marker for peritoneal sclerosis. We conducted the present study to evaluate if the presence of HMCs in PE or in culture was related to peritoneal function alterations or to the development of sclerosing peritonitis. We prospectively studied 32 new peritoneal dialysis (PD)patients every 4 months, determining the presence of HMCs in culture (completing 129 studies in total). We isolated mesothelial cells from nocturnal PE and cultured them ex vivo in T-25 flasks. Cell morphology was estimated using the May-Grünwald/Giemsa method. We also examined the histories of a large patient group to determine HMCs directly in PE, and we evaluated 4 of those patients (6%) who showed persistent HMCs. In 10 of 32 prospectively studied patients, we found HMCs during the culture phase. The cells appeared in the first evaluation in 4 patients and in subsequent cultures in the remaining 6 patients. Ultrafiltration (UF) and solute transport capacity in the 10 patients were similar to those of patients who did not show HMCs. Demographic parameters were not different between the two groups. None of the prospectively studied patients showed any clinical or peritoneal functional abnormality during the study. Cultures performed after the observation of HMCs showed very poor growth capacity. The evolution of the 4 patients in the historic group occurred as follows: We 1 patient transferred to hemodialysis 2 years after the observation of HMCs. 1 patient died of an unrelated cause after 1 year on PD. 1 patient received a successful kidney graft 5 years after the observation of HMCs. 1 patient developed type I UF failure 10 years after the first observation.

Ghrelin plasma levels and appetite in peritoneal dialysis patients.

Anorexia-associated malnutrition is a severe complication that increases mortality in peritoneal dialysis (PD) patients. Ghrelin is a recently-discovered orexigenic hormone with actions in brain and stomach. We analyzed, in 42 PD patients, the possible relationship between ghrelin and appetite regulation with regard to other orexigens [neuropeptide Y (NPY), NO3] and anorexigens [cholecystokinin (CCK), leptin, glucose-dependent insulinotropic peptide (GIP), tumor necrosis factor alpha (TNFalpha)]. All orexigens and anorexigens were determined in plasma. Eating motivation was evaluated using a visual analog scale (VAS). The patients were divided into three groups: those with anorexia (n = 12), those with obesity associated with high intake (n = 12), and those with no eating behavior disorders (n = 18). A control group of 10 healthy volunteers was also evaluated. Mean plasma levels of ghrelin were high (3618.6 +/- 1533 mg/mL), with 36 patients showing values above the normal range (< 2600 mg/mL). Patients with anorexia had lower ghrelin and NPY levels and higher peptide-C, CCK, interleukin-1 (IL-1), TNFalpha, and GIP levels than did the other patients. Patients with anorexia also had an early satiety score and low desire and pleasure in eating on the VAS and diet survey. We observed significant positive linear correlations between ghrelin and albumin (r = 0.43, p < 0.05), prealbumin (r = 0.51, p < 0.05), transferrin (r = 0.4, p < 0.05), growth hormone (r = 0.66, p < 0.01), NO3 (r = 0.36, p < 0.05), and eating motivation (VAS). At the same time, negative relationships were observed between blood ghrelin and GIP (r = -0.42, p < 0.05), insulin (r = -0.4, p < 0.05), leptin (r = -0.45, p < 0.05), and creatinine clearance [r = -0.33, p = 0.08 (nonsignificant)]. Ghrelin levels were not related to Kt/V or to levels of CCK and cytokines. Ghrelin plasma levels are elevated in PD patients. Uremic patients with anorexia show relatively lower ghrelin plasma levels than the levels seen in obese patients or in patients with normal appetite. The role of ghrelin in appetite modulation is altered in uremic PD patients, and that alteration is possibly associated with disorders in insulin and growth hormone metabolism.

Malnutrition-inflammation syndrome is associated with endothelial dysfunction in peritoneal dialysis patients.

Endothelial dysfunction with atherosclerosis is a recognized complication of uremic patients. The hypoalbuminemia of peritoneal dialysis (PD) patients can induce a hypercoagulable and atherogenic state. In this study, we investigated the role played by malnutrition-inflammation syndrome on endothelial function markers in PD patients. We measured markers of nutrition [normalized protein catabolic rate (nPCR), albumin, prealbumin, insulin-like growth factor 1 (IGF-1), transferrin, and cholesterol], markers of endothelial damage and function [tissue-type plasminogen activator (tPA), thrombomodulin (TM), von Willebrand factor (vWF), and NO3 (representing NO)], markers of a coagulable state [fibrinogen and plasminogen activator inhibitor 1 (PAI-1)], markers of inflammation [tumor necrosis factor alpha (TNF alpha) and C-reactive protein (CRP)], and other endothelial injury factors [lipoprotein(a) [Lp(a)] and homocysteine]. We also performed an endothelial stimulation test consisting of right-arm venous occlusion (VO) for 10 minutes. The patients were divided into four groups according to their clinical atherosclerotic score (CAS). We studied 45 clinically stable PD patients. At baseline, statistically significant negative linear correlations were found between albumin and age (r = -0.54, p < 0.05), albumin and vWF post-VO (r = -0.54, p < 0.05), and albumin and TM (r = -0.36, p < 0.05), which are endothelial damage markers and prothrombotic factors. A positive linear correlation was seen between albumin and NO3 post-VO (r = 0.48, p < 0.05), indicating a high vasodilatation capacity. C-Reactive protein and TNF alpha showed a positive linear correlation (r = 0.5, p < 0.01). Similarly, TNF alpha showed a positive linear correlation with cardiovascular risk markers such as fibrinogen (r = 0.79, p < 0.01), PAI-1 (r = 0.44, p < 0.05), and homocysteine (r = 0.37, p < 0.05). Creatinine clearance showed a negative linear correlation with TM (r = -0.36, p < 0.05). Patients with albumin < 4 g/dL showed a lower tPA ratio, lower NO3, and a higher CRP, TNF alpha, and Lp(a) than did patients with albumin > 4 g/dL [tPA ratio: 2.1 +/- 1.56 (n = 29) vs. 2.6 +/- 2.3 (n = 16), p < 0.05; NO3: 47 +/- 27 micrograms/mL vs. 69 +/- 33 micrograms/mL, p < 0.05; CRP: 1.8 +/- 3 mg/dL vs. 1.1 +/- 1.6 mg/dL, p < 0.05; TNF alpha: 44.4 +/- 16 pg/mL vs. 36.6 +/- 21.4 pg/mL, p < 0.05; Lp(a): 55 +/- 39 mg/dL vs. 33 +/- 21 mg/dL, p < 0.05]. Patients with a worse CAS showed higher homocysteine levels and lower albumin values. Those relationships were maintained in both periods of the study. We found no relationships between dialysis dose and endothelial function markers. In conclusion, malnutrition-inflammation syndrome may contribute to endothelial dysfunction and, consequently, to prothrombotic and proatherogenic processes in PD patients.

Thoughts on the start and withdrawal of dialysis.

Increased life expectancy and the availability of treatments provided by modern medicine have given rise to a new situation in which survival may be prolonged without the patient having an acceptable quality of life. Renal replacement therapy (RRT) to treat End Stage Renal Disease (ESRD) may involve the use of aggressive techniques designed to improve and prolong the lives of patients with high comorbidity and very low short term survival expectancy. RRT often means lowering patients’ quality of life, it is a significant burden on families and survival expectancy is low. Patients must actively participate in decision-making, but to do so, the information about the prognosis of their disease and how the treatment will affect their quality of life must be more comprehensive. As nephrologists, we will be able to contribute better to decision-making by improving prognostic tools and participating collectively with the patient and their family in the final decision. It is necessary to offer appropriate care to patients who opt for conservative treatment by implementing multidisciplinary teams within ESRD units.

Table showing dietary phosphorus/protein ratio for the Spanish population. Usefulness in chronic kidney disease.

BACKGROUND: The K/DOQI guidelines recommend the use of phosphorus/protein food ratios for proper control of dietary phosphorus. Evidence exists from tables with phosphorus to protein ratios for common foods. No such table exists for common foods consumed by the Spanish population with ratio estimations. OBJECTIVES: To estimate the phosphorus to protein ratio in foods commonly used by the Spanish population and to establish its usefulness in the selection of foods for patients with chronic kidney disease. METHOD: Tables with the phosphorus to protein ratio were prepared from two data sources concerning Spanish food composition. We evaluated chemical composition per 100g of raw food. The tables do not include phosphorus additives. No foods with high ratio of phosphorus to protein were eliminated in order to allow comparisons between different foods from each group. RESULTS: Shown in the tables. CONCLUSIONS: The dietary prescription for patients with chronic kidney disease should take into consideration not only the absolute phosphorus value of food consumed, but also the phosphorus to protein ratio of each food and the total amount of phosphorus in the diet. The more "natural" a diet is, the more likely that the patient will reach an acceptable phosphorus to protein ratio of less than 16mg/g, which does not increase mortality. There is clearly a need for an educational program on nutrition and phosphorus sources in which food ratio tables could be a useful tool for the multidisciplinary teams caring for renal patients.

Oral paricalcitol as antiproteinuric agent in chronic kidney disease.

BACKGROUND: Vitamin D has an important regulatory effect on the renin-angiotensin-aldosterone system, playing a central role in the regulation of proteinuria. We therefore studied the antiproteinuric effect of paricalcitol. METHODS: 36 patients with an estimated GFR of 30-90 mL/min/1.73 m² and proteinuria >400 mg/d with a stable dose of ACE inhibitor or ARB for at least 3 months were recruited. Patients received oral paricalcitol 1 µg/day for 12 months. Primary endpoint was decrease in proteinuria from baseline. Secondary endpoints were changes in creatinine, eGFR, serum levels of calcium, phosphorus, iPTH, 25(OH)vitD, C-Reactive Protein and blood presure. RESULTS: Mean proteinuria was 2806 mg/d and fell to 2199 mg/d at month 6 (p<.0001) and 1931.5 mg/d at month 12 (P<.0001). Patients with >3000 mg/d baseline proteinuria (n=12) saw smaller relative reductions in proteinuria (5956.9±2492.6 mg/d to 4220.4±2613 mg/d at 12 months) than patients with <3000 mg/d baseline proteinuria (1371±627.5 mg/d to 821.3±491.5mg/d at 12 months). There were no changes in BP, eGFR and CRP. We observed significant changes in serum levels of calcium, phosphorus, iPTH, 25(OH) vitamin D. CONCLUSION: Our study shows an important reduction in proteinuria with a low dose of oral paricalcitol in CKD, that is particularly robust with baseline proteinuria between 1-3 g/d.

Reflexiones sobre la entrada y la retirada de diálisis / Thoughts on the start and withdrawal of dialysis

El aumento de las expectativas de vida y la disponibilidad de tratamientos proporcionados por la medicina actual han dado lugar a nuevas situaciones en las que se puede prolongar la supervivencia en condiciones de calidad de vida inaceptables. El tratamiento sustitutivo renal (TSR) para el tratamiento de la enfermedad renal crónica avanzada (ERCA) puede implicar el uso de técnicas agresivas, diseñadas para mejorar y prolongar la vida, a pacientes con elevada comorbilidad y expectativas de supervivencia muy limitadas a corto plazo. Con frecuencia, el inicio de TSR implica un empeoramiento de la calidad de vida de los pacientes y una importante sobrecarga familiar, con una limitada supervivencia. Los pacientes deben participar activamente en la toma de decisiones, pero para ello han de disponer de una información más completa sobre el pronóstico de su enfermedad y cómo va a influir el tratamiento en su calidad de vida. Los nefrólogos podremos contribuir mejor en la toma de decisiones perfeccionando las herramientas pronósticas y participando de forma colegiada con el paciente y su familia en la decisión final. Es necesario ofrecer a los pacientes que opten por el tratamiento conservador una adecuada asistencia mediante la implantación de equipos multidisciplinarios dentro de las unidades de ERCA (AU)

Increased life expectancy and the availability of treatments provided by modern medicine have given rise to a new situation in which survival may be prolonged without the patient having an acceptable quality of life. Renal replacement therapy (RRT) to treat End Stage Renal Disease (ESRD) may involve the use of aggressive techniques designed to improve and prolong the lives of patients with high comorbidity and very low short term survival expectancy. RRT often means lowering patients' quality of life, it is a significant burden on families and survival expectancy is low. Patients must actively participate in decision-making, but to do so, the information about the prognosis of their disease and how the treatment will affect their quality of life must be more comprehensive. As nephrologists, we will be able to contribute better to decision-making by improving prognostic tools and participating collectively with the patient and their family in the final decision. It is necessary to offer appropriate care to patients who opt for conservative treatment by implementing multidisciplinary teams within ESRD units (AU)

Tablas de ratio fósforo/proteína de alimentos para población española. Utilidad en la enfermedad renal crónica / Table showing dietary phosphorus/protein ratio for the Spanish population. Usefulness in chronic kidney disease

Antecedentes: Las guías K/DOQI recomiendan el uso del ratio fósforo/proteína de los alimentos para un buen control del fósforo de la dieta. Existe evidencia de tablas con el ratio fósforo/proteína. No existe hasta el momento una tabla de alimentos habituales en la población española con la estimación del ratio. Objetivos: Estimar el ratio fósforo/proteína de alimentos de uso general en la población española y establecer su utilidad en la selección de alimentos para los pacientes con enfermedad renal crónica. Método: Las tablas con el ratio fósforo/proteína se han elaborado a partir de dos fuentes de datos de composición de alimentos españolas. Se ha considerado la composición química por cada 100 g de alimento crudo. Las tablas no incluyen el fósforo de los aditivos. No se eliminaron los alimentos con ratio fósforo/proteína elevado para poder establecer una comparación entre los distintos alimentos de cada grupo. Resultados: Se encuentran comprendidos en las tablas. Conclusiones: La prescripción dietética de los pacientes con enfermedad renal crónica debería tener en consideración no solo el valor absoluto de fósforo del alimento en cuestión, sino también el ratio fósforo/proteína de cada alimento y el total de la dieta. Cuanto más «natural» sea la dieta, más fácil será que alcance un ratio fósforo/proteína aceptable y mayor probabilidad de ser menor de 16 mg/g, no aumentando la morbimortalidad. Resulta evidente la necesidad de establecer un programa educativo sobre fuentes de fósforo y nutrición en el que la tabla pueda ser una herramienta útil para el equipo multidisciplinar que atiende al enfermo renal (AU)

Background: The K/DOQI guidelines recommend the use of phosphorus/protein food ratios for proper control of dietary phosphorus. Evidence exists from tables with phosphorus to protein ratios for common foods. No such table exists for common foods consumed by the Spanish population with ratio estimations. Objectives: To estimate the phosphorus to protein ratio in foods commonly used by the Spanish population and to establish its usefulness in the selection of foods for patients with chronic kidney disease. Method: Tables with the phosphorus to protein ratio were prepared from two data sources concerning Spanish food composition. We evaluated chemical composition per 100g of raw food. The tables do not include phosphorus additives. No foods with high ratio of phosphorus to protein were eliminated in order to allow comparisons between different foods from each group. Results: Shown in the tables. Conclusions: The dietary prescription for patients with chronic kidney disease should take into consideration not only the absolute phosphorus value of food consumed, but also the phosphorus to protein ratio of each food and the total amount of phosphorus in the diet. The more "natural" a diet is, the more likely that the patient will reach an acceptable phosphorus to protein ratio of less than 16mg/g, which does not increase mortality. There is clearly a need for an educational program on nutrition and phosphorus sources in which food ratio tables could be a useful tool for the multidisciplinary teams caring for renal patients (AU)

Oral paricalcitol as antiproteinuric agent in chronic kidney disease

Background: Vitamin D has an important regulatory effect on the renin-angiotensin-aldosterone system, playing a central role in the regulation of proteinuria. We therefore studied the antiproteinuric effect of paricalcitol. Methods: 36 patients with an estimated GFR of 30-90mL/min/1.73m2 and proteinuria >400mg/d with a stable dose of ACE inhibitor or ARB for at least 3 months were recruited. Patients received oral paricalcitol 1µg/day for 12 months. Primary endpoint was decrease in proteinuria from baseline. Secondary endpoints were changes in creatinine, eGFR, serum levels of calcium, phosphorus, iPTH, 25(OH)vitD, C-Reactive Protein and blood presure. Results: Mean proteinuria was 2806mg/d and fell to 2199mg/d at month 6 (p<.0001) and 1931.5mg/d at month 12 (p<.0001). Patients with >3000mg/d baseline proteinuria (n=12) saw smaller relative reductions in proteinuria (5956.9±2492.6mg/d to 4220.4±2613mg/d at 12 months) than patients with <3000mg/d baseline proteinuria (1371±627.5 mg/d to 821.3±491.5mg/d at 12 months). There were no changes in BP, eGFR and CRP. We observed significant changes in serum levels of calcium, phosphorus, iPTH, 25(OH) vitamin D. Conclusion: Our study shows an important reduction in proteinuria with a low dose of oral paricalcitol in CKD, that is particularly robust with baseline proteinuria between 1-3g/d (AU)

Introducción: La vitamina D posee un efecto regulatorio del eje renina-angiotensina-aldosterona, jugando, por lo tanto, un papel importante en cuanto a proteinuria se refiere. Presentamos nuestra experiencia en el uso de paricalcitol como antiproteinúrico. Métodos: Incluimos 36 pacientes con un eGFR of 30-90 ml/min/1,73 m2 y proteinuria > 400 mg/d con dosis estables de inhibidores del SRAA durante 3 meses. Se le admistró durante 12 meses 1 µg/día de paricalcitol. Como objetivo primario estudiamos el descenso de proteinuria; como secundarios cambios en Cr, eFG, calcio, fósforo, iPTH, 25(OH)vitD, PCR y tension arterial. Resultados: La proteinuria media fue 2806 mg/d cayendo hasta 2199 mg/d en el mes 6 (p < 0,0001) y 1931,5 mg/d a los 12 meses (p < 0,0001). Aquellos con una proteinuria basal > 3000 mg/d (n=12) sufrieron una menor disminución (5956,9 ± 2492,6 mg/d a 4220,4 ± 2613 mg/d en mes 12) respecto a aquellos con una proteinuria < 3000 mg/d (1371 ± 627,5 mg/d a 821,3 ± 491,5 mg/d en mes 12). No se objetivaron cambios en tension arterial, eGFR y PCR. Los cambios en calcio, fósforo, iPTH y vitamina D 25(OH) fueron estadísticamente significativos. Conclusión: Nuestro estudio demuestra una reducción importante de proteinuria con dosis bajas de paricalcitol en pacientes con IRC, que es de particular importancia en aquellos con porteinuria basal entre 1-3 g/d (AU)