Andréa E. M. Stinghen

Impact of Cholecalciferol Treatment on Biomarkers of Inflammation and Myocardial Structure in Hemodialysis Patients Without Hyperparathyroidism

INTRODUCTION Vitamin D (25-hydroxyvitamin D, 25(OH)D) deficiency, hypovitaminosis D, is highly prevalent in chronic kidney disease patients and is potentially involved with complications in the hemodialysis (HD) population. The aim of this study was to evaluate the impact of cholecalciferol supplementation on biomarkers of mineral metabolism, inflammation, and cardiac function in a group of HD patients presenting with hypovitaminosis D and low intact parathyroid hormone (iPTH) levels. MATERIAL AND METHODS HD patients with iPTH levels of <300 pg/mL, not receiving vitamin D therapy, and presenting with 25(OH)D levels of <30 ng/mL were enrolled in this prospective study. Oral cholecalciferol was prescribed once a week in the first 12 weeks (50,000 IU) and in the last 12 weeks (20,000 IU) of the study. High-sensitivity C-reactive protein, interleukin-6, and serum albumin were used as inflammatory markers. Echocardiograms were performed on a midweek interdialytic day at baseline and after 6 months of cholecalciferol supplementation. RESULTS In all, 30 patients were included in the final analysis. We observed a significant increase in serum 25(OH)D levels after 3 months (46.2 ± 14.4 ng/mL vs. 18.1 ± 6.6 ng/mL; P < .001) and after 6 months (40.4 ± 10.4 ng/mL vs. 18.1 ± 6.6 ng/mL; P < .001) of cholecalciferol supplementation. There were no significant changes in alkaline phosphatase, iPTH, phosphorus, and serum albumin levels, but there was a slight but significant increase in calcium levels after 6 months of cholecalciferol supplementation (9.4 ± 0.6 mg/dL vs. 9.0 ± 0.6 mg/dL; P = .02). Additionally, we observed a significant reduction in high-sensitivity C-reactive protein levels after 3 months (median: 0.62 [0.05 to 29.6] mg/L vs. 0.32 [0.02 to 3.13] mg/L; P = .02) and after 6 months (median: 0.62 [0.05 to 29.6] mg/L vs. 0.50 [0.02 to 5.66] mg/L; P = .04) of cholecalciferol supplementation, as well as a significant reduction in interleukin-6 levels (median: 6.44 pg/mL vs. 3.83 pg/mL; P = .018) after 6 months of supplementation. Left ventricular mass index was significantly reduced at the end of supplementation (159 ± 55 g/m(2) vs. 175 ± 63 g/m(2); P = .03). CONCLUSIONS Cholecalciferol supplementation in HD patients was found to be safe and efficient to correct hypovitaminosis D and established little impact on mineral metabolism markers. Additionally, we observed a reduction in important surrogate markers of cardiovascular risk, namely systemic inflammation and left ventricular hypertrophy, suggesting an anti-inflammatory action and possibly an improvement of cardiac dysfunction.

Increased plasma and endothelial cell expression of chemokines and adhesion molecules in chronic kidney disease.

Chemokines and adhesion molecules are involved in early events of atherogenesis. In the present study, we investigated the effects of the uremic milieu on the expression of monocyte chemoattractant protein-1 (MCP-1), interleukin-8 (IL-8), soluble vascular adhesion molecule-1 (sVCAM-1) and soluble intercellular adhesion molecule-1 (sICAM-1) and their relationship to cardiovascular status. Plasma samples were obtained from patients in different stages of chronic kidney disease (CKD). Cardiovascular status was evaluated by intima-media thickness and endothelial dysfunction by flow mediation dilatation and proteinuria. In vitro studies were performed using human umbilical endothelial cells exposed to uremic plasma or plasma from healthy subjects. MCP-1, IL-8, sVCAM-1 and sICAM-1 levels in plasma and in supernatant were analyzed by enzyme-linked immunosorbent assay. The population consisted of 73 (mean age 57 years; 48% males) CKD patients with glomerular filtration rate (GFR) of 37 ± 2 ml/min. MCP-1 and sVCAM-1 plasma levels were negatively correlated with GFR (ρ = –0.40, p < 0.0005 and ρ = –0.42, p < 0.0005, respectively). Fibrinogen was positively correlated with MCP-1, sICAM-1 and sVCAM-1 (ρ = 0.33, p < 0.005, ρ = 0.32, p < 0.05 and ρ = 0.25, p < 0.05, respectively) and ultra-high-sensitivity C-reactive protein was positively correlated with sICAM-1 (ρ = 0.25, p < 0.0005). Plasma IL-8 had a significant positive correlation with proteinuria (ρ = 0.31, p < 0.01). There was a time- and CKD-stage-dependent MCP-1, IL-8 and sVCAM-1 endothelial expression (p < 0.05). In summary, plasma levels of markers of endothelial cell activation (MCP-1 and sVCAM-1) are increased in more advanced CKD. Exposure of endothelial cells to uremic plasma results in a time- and CKD-stage-dependent increased expression of MCP-1, IL-8 and sVCAM-1, suggesting a link between vascular activation, systemic inflammation and uremic toxicity. Future studies are necessary to investigate whether these biomarkers add predictive value in comparison to the previously described ones. Also, endothelial response to uremic toxicity should be viewed as a potential target for intervention in order to reduce morbidity and mortality in CKD-related cardiovascular disease.

Sevelamer decreases systemic inflammation in parallel to a reduction in endotoxemia.

Introduction: Uremic toxins play a pivotal role in the development of systemic complications of chronic kidney disease (CKD), which are largely mediated by the activation of the immune system. Triggers of inflammation in CKD are largely unknown and strategies aiming to reduce circulating ligands that could start the inflammatory response are potentially important. In the present study, we investigated the impact of sevelamer hydrochloride treatment in reducing endotoxemia and inflammation in a group of hemodialysis (HD) patients. Material and Methods: HD patients, who were converted from calcium carbonate treatment to sevelamer according to KDOQI guidelines, were included and prospectively followed for 6 months. Systemic inflammation was evaluated by serum ultra-high-sensitivity C-reactive protein (hsCRP) using an automated immunoturbidimetric assay. Endotoxin was measured using Limulus amebocyte lysate chromogenic endpoint assay. All the analyses were performed immediately before conversion and after 6 months of treatment. Results: After the exclusion of patients discontinuing the treatment, 20 patients (mean dialysis time 12 ± 4 months on HD, age 52 ± 2 years, 38% males, 11% diabetics) were included in the analysis. No significant changes were observed in Ca, P and PTH levels, while a reduction in cholesterol levels was seen. Plasma concentration of hsCRP and endotoxin significantly decreased after 6 months of conversion to sevelamer compared with baseline. Conclusion: We conclude that sevelamer treatment leads to a decrease in hsCRP levels, which was accompanied by a parallel decrease in endotoxemia, suggesting that endotoxemia may contribute to the systemic inflammation in HD patients, which was partially reduced by the use of sevelamer.

A gut feeling on endotoxemia: causes and consequences in chronic kidney disease.

Chronic inflammation is closely linked to several complications of chronic kidney disease (CKD), such as vascular calcification, accelerated atherosclerosis, loss of appetite, insulin resistance, increased muscle catabolism and anemia. As a consequence, inflammation is a predictor of mortality in this group of patients. Specific causes of the activation of the immune system in CKD are largely unknown. Endotoxin (ET) release to the circulation represents a potentially important target for interventions aiming to reduce mortality in CKD patients. In this minireview, we propose that there are several potential sources of endotoxemia in CKD and that gut translocation, leading to the generation of ligands of the innate immune response, represents a potentially reversible cause. Prevention of endotoxemia, through treating foci of ET (periodontal disease, catheters, vascular access) or reducing translocation from the gut, will potentially reduce the inflammatory response.

Immune Mechanisms Involved in Cardiovascular Complications of Chronic Kidney Disease

A sustained status of chronic inflammation is closely linked to several complications of chronic kidney disease (CKD), such as vascular degeneration, myocardial fibrosis, loss of appetite, insulin resistance, increased muscle catabolism and anemia. These consequences of a chronically activated immune system impact on the acceleration of atherosclerosis, vascular calcification and development of heart dysfunction. Recent evidence suggests that these immune-mediated consequences of uremic toxicity are not only important to stratify the risk and understand the mechanisms of disease, but also represent an important area for intervention. Thus, the aim of this brief review is to discuss the immune mechanisms behind atherosclerosis and myocardiopathy in CKD. We also display the emerging evidence that strategies focusing on modulating the immune response or reducing the generation of triggers of inflammation may represent an important tool to reduce mortality in this group of patients. Ongoing studies may generate the evidence that will translate these strategies to definitive changes in clinical practice.

Hypovitaminosis D Is Associated with Systemic Inflammation and Concentric Myocardial Geometric Pattern in Hemodialysis Patients with Low iPTH Levels

Background: Vitamin D [25(OH)D] deficiency is a cardiovascular risk factor in the hemodialysis (HD) population. The aim of this study was to identify hypovitaminosis D in HD patients without signs of hyperparathyroidism and to analyze its association to inflammation and echocardiographic alterations. Methods: Patients on HD with iPTH <300 pg/ml not receiving vitamin D therapy were recruited. Hypovitaminosis D was defined as 25(OH)D <30 ng/ml. High-sensitivity C-reactive protein, interleukin-6 and serum albumin were used as inflammation markers. Echocardiograms were performed in an interdialytic mid-week day. Results: Sixty-one patients (mean age of 56 ± 15 years, 52% males, 93% Caucasians, 31% diabetic) were included, and 75% presented hypovitaminosis D. Inflammation was more prevalent among those with hypovitaminosis D, and these patients presented higher relative wall thickness (0.48 ± 0.11 vs. 0.42 ± 0.10 mm; p = 0.05) and lower left ventricular diastolic (49.8 ± 6.2 vs. 54.7 ± 5.8 mm; p = 0.013) and systolic (31.9 ± 5.7 vs. 36.8 ± 7.2 mm; p = 0.012) diameters. Conclusions: Hypovitaminosis D is associated with inflammation and concentric geometric pattern of the left ventricle, even in the absence of high iPTH levels. Vitamin D repletion (aiming to reduce cardiovascular complications) should also be considered in HD patients with normal or low iPTH levels.

Vascular Damage in Kidney Disease: Beyond Hypertension

Chronic kidney disease (CKD) is highly prevalent and a multiplier of cardiovascular disease (CVD) and cannot be completely explained by traditional Framinghan risk factors. Consequently, greater emphasis has been placed in nontraditional risk factors, such as inflammation, endothelial dysfunction, sympathetic overactivation, protein-energy wasting oxidative stress, vascular calcification, and volume overload. The accumulation of uremic toxins (and the involvement of genetic factors) is responsible for many of the clinical consequences of a condition known as uremia. In this brief paper, we discuss mechanisms involved in the vascular damage of CKD patients, aiming to point out that important factors beyond hypertension are largely responsible for endothelial activation and increased CVD risk, with potential impact on risk stratification and development of novel therapeutic options.

Acetylcholinesterase inhibitory activity of uleine from Himatanthus lancifolius.

Application of acetylcholinesterase (AChE) inhibitors is the primary treatment for Alzheimer’s disease. Alkaloids, such as physostigmine, galanthamine, and huperzine A, play an important role as AChE inhibitors. The aim of this work was to evaluate Himatanthus lancifolius (Muell. Arg.) Woodson, a Brazilian species of Apocynaceae, and its main indole alkaloid uleine, in order to identify new AChE inhibitors. The plant fluid extract, fractions, and uleine were tested for AChE inhibitory activity using Ellman’s colorimetric method for thin-layer chromatography (TLC), 96-well microplates, and also Marston’s TLC colorimetric method. Both TLC assays showed similar results. At 5 mg/mL, the fluid extract inhibited the AChE enzyme by (50.71 ± 8.2)%. The ethyl acetate fraction exhibited the highest level of AChE inhibition, followed by the dichloromethane fraction. The isolated alkaloid uleine displayed an IC50 value of 0.45 μM.

Ação da uleína sobre a produção de óxido nítrico em células RAEC e B16F10

The influence of the rich alkaloidal fraction and of the major substance in this fraction, uleine, isolated from the barks of Himatanthus lancifolius (Muell. Arg.) Woodson, Apocynaceae, popularly known as agoniada, on the nitric oxide production in RAEC and B16F10 cells and its correlation with the antioxidant activity, were investigated. For the antioxidant activity the methods of formation of a phosphomolybdenum complex and the reduction of the free radical DPPH were used. The results demonstrated an antioxidant activity of 59.3 ± 0.8% for the alkaloidal fraction, while for uleine the effect was of 0.5 ± 0.1% in the reduction of the phosphomolibdenium method. In the assay of DPPH, the alkaloidal fraction presented IC50 = 196.3 ± 8.9 µg/mL and for uleine, 6475.0 ± 25.0 µg/mL. Uleine also stimulated a maximum nitric oxide production in the concentrations of 0.1 µg/mL (20.9 ± 1.4 µM) and 1 µg/mL (41.1 ± 0.2 µM) using RAEC and B16F10 cells, respectively, demonstrating that the effect of uleine in the cells occurs by promoting the nitric oxide production pathway, but not through a free radical scavenger effect.

The quest for a better understanding of chronic kidney disease complications: an update on uremic toxins

Chronic kidney disease is characterized by a progressive reduction of glomerular filtration rate and/or the appearance of proteinuria, and subsequently the progressive retention of organic waste compounds called uremic toxins (UT). Over the last decades, a large number of such compounds have been identified and their effects on organs and tissues, especially the cardiovascular system, has been demonstrated. In this review, we present the current classification of UT, as proposed by the EUTox Group, and the effects of some of the probably most important UTs, such as phosphate, FGF-23, PTH, AGEs, indoxyl sulfate and para-cresyl sulfate. We provide an overview on therapeutic approaches aimed to increase their extracorporeal removal via convective and/or adsorptive strategies and to lower their intestinal production/ absorption via dietetic and pharmacological interventions. The recognition that multiple toxins contribute to the uremia supports the need for new therapeutic targets, with a potentially positive impact on CKD progression and survival.