Growth Differentiation Factor-15 and Syndecan-1 Are Potential Biomarkers of Cardiac and Renal Involvement in Classical Fabry Disease under Enzyme Replacement Therapy.

BACKGROUND AND AIMS: Inflammation and endothelial damage play a pivotal role in Fabry disease (FD) manifestations. In daily clinical practice, FD is mainly monitored by traditional biomarkers of target organ injury, such as serum creatinine and proteinuria, which provide no information about inflammation and endothelial damage. MATERIALS AND METHODS: We investigated the serum levels of 3-nitrotyrosine (3-NT), an oxidative stress biomarker, and of growth differentiation factor-15 (GDF-15) and syndecan-1 in classical FD patients on enzyme replacement therapy (ERT) for at least 6 months and their relationship with Fabry-related cardiac and renal manifestations. RESULTS: Fifty-two classical FD patients (37 females) on ERT for 62.0 ± 27.5 months were included in the study. The main clinical manifestations included nephropathy (67.3%) and cardiomyopathy (21.1%). Serum levels of 3-NT, syndecan-1, and GDF-15 were 33.3 (4.8-111.1) nmol/mL, 55.7 (38.8-74.9) ng/mL, and 541.8 (392.2-784.4) pg/mL, respectively. There was a direct correlation between interventricular septal thickness and serum GDF-15 (r = 0.59; p < 0.001) and syndecan-1 (r = 0.30, p = 0.04). Among kidney parameters, there was a significant correlation between estimated glomerular filtration rate and GDF-15 (r = -0.61; p < 0.001), as well as between 24 h proteinuria and syndecan-1 (r = 0.28; p = 0.04). Serum GDF-15 levels were significantly higher in patients with cardiomyopathy (p = 0.03) as well in those with both nephropathy and cardiomyopathy (p = 0.02) than in patients without these comorbidities. Serum GDF-15 levels were also significantly higher in patients who started ERT at an older age (≥40 years). In multivariate analysis, syndecan-1, 3-NT, GDF-15, time on ERT, and arterial pressure differentiated Fabry patients with both cardiac and renal involvement from those without these manifestations. CONCLUSIONS: GDF-15 and syndecan-1 were associated with parameters of cardiac and renal involvement in classic FD patients on ERT. Their potential association with residual risk and disease outcomes should be investigated.

Chloroquine may induce endothelial injury through lysosomal dysfunction and oxidative stress.

COVID-19 is a pandemic with no end in sight. There is only one approved antiviral agent but global stocks are deemed insufficient. Despite in vitro antiviral activity, clinical trials of chloroquine and hydroxychloroquine were disappointing, and they may even impair outcomes. Chloroquine causes zebroid deposits reminiscent of Fabry disease (α-galactosidase A deficiency) and endothelial cells are key targets of COVID-19. We have explored the effect of chloroquine on cultured endothelial cells and its modulation by recombinant α-galactosidase A (agalsidase). Following dose-response studies, 0.5 µg/mL chloroquine was added to cultured human endothelial cells. Neutral red and Lysotracker were used to assess lysosomes. Cytotoxicity was evaluated by the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) - MTT assay and cell stress by assessing reactive oxygen species (ROS) and nitric oxide (NO). In endothelial cells, chloroquine induced dose-dependent cytotoxicity at in vitro test concentrations for COVID-19 therapy. At a sublethal concentration, chloroquine significantly induced the accumulation of acid organelles (P < 0.05), increased ROS levels, and decreased NO production (P < 0.05). These adverse effects of chloroquine on endothelial cell biology were decreased by agalsidase-ß (P < 0.05). Chloroquine-induced endothelial cell cytotoxicity and stress is attenuated by agalsidase-ß treatment. This suggests that endothelial cell injury may contribute to the failure of chloroquine as therapy for COVID-19 and may be at least in part related to causing dysfunction of the lysosomal enzyme α-galactosidase A.

Role of Organic Anion Transporters in the Uptake of Protein-Bound Uremic Toxins by Human Endothelial Cells and Monocyte Chemoattractant Protein-1 Expression.

Organic anion transporters (OATs) are involved in the uptake of uremic toxins such as p-cresyl sulfate (PCS) and indoxyl sulfate (IS), which play a role in endothelial dysfunction in patients with chronic kidney diseases (CKD). In this study, we investigated the role of OAT1 and OAT3 in the uptake of PCS and IS into human endothelial cells. PCS was synthesized via p-cresol sulfation and characterized using analytical methods. The cells were treated with PCS and IS in the absence and presence of probenecid (Pb), an OAT inhibitor. Cell viability was assessed using the MTT assay. The absorbed toxins were analyzed using chromatography, OAT expression using immunocytochemistry and western blot, and monocyte chemoattractant protein-1 (MCP-1) expression using enzyme-linked immunosorbent assay. Cell viability decreased after toxin treatment in a dose-dependent manner. PCS and IS showed significant internalization after 60 min treatment, while no internalization was observed in the presence of Pb, suggesting that OATs are involved in the transport of both toxins. Immunocytochemistry and western blot demonstrated OAT1 and OAT3 expression in endothelial cells. MCP-1 expression increased after toxins treatment but decreased after Pb treatment. PCS and IS uptake were mediated by OATs, and OAT blockage could serve as a therapeutic strategy to inhibit MCP-1 expression.

Uremic Toxicity of Advanced Glycation End Products in CKD.

Advanced glycation end products (AGEs), a heterogeneous group of compounds formed by nonenzymatic glycation reactions between reducing sugars and amino acids, lipids, or DNA, are formed not only in the presence of hyperglycemia, but also in diseases associated with high levels of oxidative stress, such as CKD. In chronic renal failure, higher circulating AGE levels result from increased formation and decreased renal clearance. Interactions between AGEs and their receptors, including advanced glycation end product-specific receptor (RAGE), trigger various intracellular events, such as oxidative stress and inflammation, leading to cardiovascular complications. Although patients with CKD have a higher burden of cardiovascular disease, the relationship between AGEs and cardiovascular disease in patients with CKD is not fully characterized. In this paper, we review the various deleterious effects of AGEs in CKD that lead to cardiovascular complications and the role of these AGEs in diabetic nephropathy. We also discuss potential pharmacologic approaches to circumvent these deleterious effects by reducing exogenous and endogenous sources of AGEs, increasing the breakdown of existing AGEs, or inhibiting AGE-induced inflammation. Finally, we speculate on preventive and therapeutic strategies that focus on the AGE-RAGE axis to prevent vascular complications in patients with CKD.

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.

Comparative metabolomic study of high-flux hemodialysis and high volume online hemodiafiltration in the removal of uremic toxins using 1H NMR spectroscopy.

Uremic toxins (UTs) accumulate in the circulation of patients with chronic kidney disease (CKD). High volume hemodiafiltration (HDF) improves clearance of low and medium molecular weight UTs compared to HD. The present study is a post-hoc analysis comparing the metabolomic profile in serum from patients under high flux HD (hf-HD) and HDF in HDFIT, a multicentric randomized controlled trial (RCTs). Per protocol, serum samples were collected pre- and post- dialysis treatments at randomization (baseline) and at the end of the follow up (6 months) and stored in a biorepository. Random (pre- and post-dialysis) samples from nine patients in study arm were selected at baseline and at the end of the follow up. To compare the samples, 26 possibly matching metabolites were identified by a t-test among the four groups using 1H nuclear magnetic resonance (NMR). To evaluate the comparison between the modalities is a single treatment session, the clearance rates (CRs) of each metabolite were calculated based on pre-dialysis and post-dialysis samples. In addition, to evaluate to effect of UT removal during the trial follow up period, the pre-dialysis metabolite concentrations at the baseline and at 6 months were compared among the two arms of the study. There was no significant difference between in the single session CRs of metabolites when hf-HD and HDF were compared. On the other hand, the comparison between baseline and 6-month (long-term evolution) led to the identification of 16 metabolites that differentiated the hf-HD and the HDF evolutions. Most of these 16 metabolites are involved in several important metabolic pathways, such as metabolism of phenylalanine and biosynthesis of phenylalanine, tyrosine, and tryptophan, which are related to UTs and cardiovascular disease development. Although no difference was observed between hf-HD and HDF samples before and after a single session, concentrations of CKD-relevant metabolites and associated pathologies were stable in the HDF samples, but not in the hf-HD samples, over the six-month period, suggesting that HDF enhances long-term stability.

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.

Ilex paraguariensis extract as an alternative to pain medications.

Pain is a common and distressing symptom of many diseases and its clinical treatment generally involves analgesics and anti-inflammatory drugs. This study evaluated the toxicity of Ilex paraguariensis A. St.-Hil. (Aquifoliaceae) aqueous extract (leaves, petioles and branches) and its performance in a nociceptive response. Hepatotoxicity, psycho-stimulant test and evaluation of enzyme markers for liver damage were also tested. Chromatographic analysis by UPLC-MS demonstrated a series of isomeric monocaffeoylquinic acids, isomers of dicaffeoylquinic acid, flavonol glycosides, and saponins. Phase I and II of nociception were obtained for meloxicam, dexamethasone and aqueous Ilex paraguariensis extract. Ilex paraguariensis extract concentration was negatively correlated (R = -0.887) with alanine aminotransferase (p < 0.05) in acetaminophen-induced hepatotoxicity test, indicating hepatoprotective activity of this extract. Ilex paraguariensis extract also presented analgesic properties equivalent to drugs that already have proven efficacy. Notably, the administration of multiple doses of Ilex paraguariensis extract was considered safe from the therapeutic point of view.

In vitro anti-inflammatory effects of vitamin D supplementation may be blurred in hemodialysis patients.

OBJECTIVES: This study aimed to evaluate the potential anti-inflammatory effects of vitamin D supplementation under uremic conditions, both in vivo and in vitro, and its effects on the parameters of mineral metabolism. METHODS: Thirty-two hemodialysis patients were randomly assigned to receive placebo (N=14) or cholecalciferol (N=18) for six months. Serum levels of calcium, phosphate, total alkaline phosphatase, intact parathyroid hormone (iPTH), and vitamin D were measured at baseline and after three and six months. The levels of fibroblast growth factor-23 (FGF-23), interleukin-1ß (IL-1ß), and high-sensitivity C-reactive protein (hs-CRP) were also measured at baseline and at six months. Human monocytes were used for in vitro experiments and treated with cholecalciferol (150 nM) and uremic serum. Cell viability, reactive oxygen species (ROS) production, and cathelicidin (CAMP) expression were evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, dichloro-dihydro-fluorescein diacetate assay, and real time-quantitative polymerase chain reaction, respectively. RESULTS: Both patient groups were clinically and biochemically similar at baseline. After six months, the levels of vitamin D and iPTH were higher and lower, respectively, in the cholecalciferol group than in the placebo group (p<0.05). There was no significant difference between the parameters of mineral metabolism, such as IL-1ß and hs-CRP levels, in both groups. Treatment with uremic serum lowered the monocyte viability (p<0.0001) and increased ROS production (p<0.01) and CAMP expression (p<0.05); these effects were counterbalanced by cholecalciferol treatment (p<0.05). CONCLUSIONS: Thus, cholecalciferol supplementation is an efficient strategy to ameliorate hypovitaminosis D in hemodialysis patients, but its beneficial effects on the control of secondary hyperparathyroidism are relatively unclear. Even though cholecalciferol exhibited anti-inflammatory effects in vitro, its short-term supplementation was not effective in improving the inflammatory profile of patients on hemodialysis, as indicated by the IL-1ß and hs-CRP levels.

The toxicity of Aspidosperma subincanum to MCF7 cells is related to modulation of oxidative status and proinflammatory pathways.

ETHNOPHARMACOLOGICAL RELEVANCE: Cancer is an inflammatory disease because carcinogenesis and tumor progression depend on intrinsic and extrinsic inflammatory pathways. Although species of the genus Aspidosperma are widely used to treat tumors, and there is ethnopharmacological evidence for traditional use of the species A. subincanum as an anti-inflammatory agent, its antineoplastic potential is unknown. AIM OF THE STUDY: To evaluate toxic effects of the indole alkaloid-rich fraction (IAF) of A. subincanum on the MCF7 cell line and identify some of the anti-inflammatory mechanisms involved. MATERIALS AND METHODS: Chromatographic analyses were performed by ultra-high-performance liquid chromatography with electrospray ionization mass spectrometry, and cytotoxic and antiproliferative effects of IAF were verified by MTT and clonogenic assays. Cell cycle alterations were analyzed by measuring DNA content, while propidium iodide and acridine orange staining was performed to determine the type of induced cell death. The expression of apoptosis markers and proteins involved in cell proliferation and survival pathways was analyzed by immunoblotting, RT-qPCR, and ELISAs. Interference with redox status was investigated using a DCFH-DA probe and by measuring catalase activity. RESULTS: Chromatographic analyses showed that IAF is a complex mixture containing indole alkaloids. IAF selectively exerted toxic and antiproliferative effects, elevating the Bax/Bcl-xL ratio and inducing apoptosis in MCF7 cells. IAF decreased intracellular reactive oxygen species levels and increased catalase activity, while reducing the IL-8 level and suppressing COX-2 expression. CONCLUSIONS: IAF induces apoptosis in MCF7 cells by suppressing COX-2 expression while reducing IL-8 levels and intracellular content of reactive oxygen species.

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.

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 microM.

Characteristics and causes of immune dysfunction related to uremia and dialysis.

From the immunologic viewpoint, chronic kidney disease (CKD) is characterized by disorders of both the innate and adaptive systems, generating a complex and still not fully understood immune dysfunction. Markers of a chronically activated immune system are closely linked to several complications of CKD and represent powerful predictors for mortality in the CKD population. On the other hand, CKD patients respond poorly to vaccination and to challenges such as bacterial infection. Interestingly, the main causes of death in patients with CKD are cardiovascular and infectious diseases, both being pathologic processes closely linked to immune function. Therefore, accelerated tissue degeneration (as a consequence of chronic inflammation) and increased rate of sepsis (because of a poorly orchestrated immune response) represent the most important targets for interventions aiming to reduce mortality in CKD patients. Understanding the mechanisms behind the immune dysfunction that is peculiar to CKD generates a perspective to improve outcomes in this group of patients.

Sevelamer reduces endothelial inflammatory response to advanced glycation end products.

BACKGROUND: Advanced glycation end products (AGEs) have been related to the pathogenesis of cardiovascular diseases (CVD), chronic kidney disease (CKD) and diabetes mellitus. We sought to investigate the binding capacity of sevelamer to both AGEs and uremic serum in vitro and then test this pharmaceutical effect as a potential vascular anti-inflammatory strategy. METHODS: AGEs were prepared by albumin glycation and characterized by absorbance and electrophoresis. Human endothelial cells were incubated in culture media containing AGEs and uremic serum with or without sevelamer. Receptor for advanced glycation end product (RAGE) expression was evaluated through immunocytochemistry and western blot to explore the interactions between AGEs and the endothelium. Inflammatory and endothelial dysfunction biomarkers, such as interleukin 6 (IL-6) and IL-8, monocyte chemoattractant protein-1 (MCP-1), plasminogen activator inhibitor-1 (PAI-1) and serum amyloid A (SAA) were also measured in cell supernatant. The chemotactic property of the supernatant was evaluated. RESULTS: AGEs significantly induced the expression of RAGE, inflammatory and endothelial activation biomarkers [IL-6, (P < 0.005); IL-8, MCP-1, PAI-1 and SAA (P < 0.001)] and monocyte chemotaxis as compared with controls. In addition, AGEs increased the levels of inflammatory biomarkers, which were observed after 6 h of endothelial cell incubation with uremic serum [IL-6 (P < 0.001) IL-8, MCP-1 and PAI-1 (P < 0.05)]. On the other hand, after 6 h of endothelial cell treatment with sevelamer, RAGE expression (P < 0.05) and levels of inflammatory biomarkers [IL-6 and IL-8 (P < 0.001), MCP-1 (P < 0.01), PAI-1 and SAA (P < 0.005)] significantly decreased compared with the AGEs/uremic serum treatment alone. CONCLUSIONS: Sevelamer decreased both endothelial expression of RAGE and endothelial dysfunction biomarkers, induced by AGEs, and uremic serum. Further studies are necessary for a better understanding of the potential protective role of sevelamer on uremic serum and AGEs-mediated endothelial dysfunction.

The Impact of Uremic Toxicity Induced Inflammatory Response on the Cardiovascular Burden in Chronic Kidney Disease.

Uremic toxin (UT) retention in chronic kidney disease (CKD) affects biological systems. We aimed to identify the associations between UT, inflammatory biomarkers and biomarkers of the uremic cardiovascular response (BUCVR) and their impact on cardiovascular status as well as their roles as predictors of outcome in CKD patients. CKD patients stages 3, 4 and 5 (n = 67) were recruited and UT (indoxyl sulfate/IS, p-cresil sulfate/pCS and indole-3-acetic acid/IAA); inflammatory biomarkers [Interleukin-6 (IL-6), high sensitivity C reactive protein (hsCRP), monocyte chemoattractant protein-1 (MCP-1), soluble vascular adhesion molecule-1 (sVCAM-1), soluble intercellular adhesion molecule-1 (sICAM-1) and soluble Fas (sFas)] and BUCVRs [soluble CD36 (sCD36), soluble receptor for advanced glycation end products (sRAGE), fractalkine] was measured. Patients were followed for 5.2 years and all causes of death was used as the primary outcome. Artery segments collected at the moment of transplantation were used for the immunohistochemistry analysis in a separate cohort. Estimated glomerular filtration rate (eGFR), circulating UT, plasma biomarkers of systemic and vascular inflammation and BUCVR were strongly interrelated. Patients with plaque presented higher signs of UT-induced inflammation and arteries from CKD patients presented higher fractalkine receptor (CX3CR1) tissue expression. Circulating IS (p = 0.03), pCS (p = 0.007), IL-6 (p = 0.026), sFas (p = 0.001), sCD36 (p = 0.01) and fractalkine (p = 0.02) were independent predictors of total mortality risk in CKD patients. Our results reinforce the important role of uremic toxicity in the pathogenesis of cardiovascular disease (CVD) in CKD patients through an inflammatory pathway.

Uremia Impacts VE-Cadherin and ZO-1 Expression in Human Endothelial Cell-to-Cell Junctions.

Endothelial dysfunction in uremia can result in cell-to-cell junction loss and increased permeability, contributing to cardiovascular diseases (CVD) development. This study evaluated the impact of the uremic milieu on endothelial morphology and cell junction's proteins. We evaluated (i) serum levels of inflammatory biomarkers in a cohort of chronic kidney disease (CKD) patients and the expression of VE-cadherin and Zonula Occludens-1 (ZO-1) junction proteins on endothelial cells (ECs) of arteries removed from CKD patients during renal transplant; (ii) ECs morphology in vitro under different uremic conditions, and (iii) the impact of uremic toxins p-cresyl sulfate (PCS), indoxyl sulfate (IS), and inorganic phosphate (Pi) as well as of total uremic serum on VE-cadherin and ZO-1 gene and protein expression in cultured ECs. We found that the uremic arteries had lost their intact and continuous endothelial morphology, with a reduction in VE-cadherin and ZO-1 expression. In cultured ECs, both VE-cadherin and ZO-1 protein expression decreased, mainly after exposure to Pi and uremic serum groups. VE-cadherin mRNA expression was reduced while ZO-1 was increased after exposure to PCS, IS, Pi, and uremic serum. Our findings show that uremia alters cell-to-cell junctions leading to an increased endothelial damage. This gives a new perspective regarding the pathophysiological role of uremia in intercellular junctions and opens new avenues to improve cardiovascular outcomes in CKD patients.

Controlling inflammation in peritoneal dialysis: the role of pd-related factors as potential intervention targets.

Cardiovascular (CV) disease is the main cause of death in peritoneal dialysis (PD) patients, but the mechanisms mediating the increased CV risk observed in this group of patients are still largely unknown, which limits the perspective on effective therapeutic strategies. Patients on PD are already exposed to a number of traditional risk factors from the start of their chronic kidney disease (CKD), because many of those risk factors are common to CV disease and CKD alike. As renal dysfunction progresses, CKD-related risk factors are introduced, changing the profile of both the CV disease and the markers of risk. In this phase, which usually starts when glomerular filtration rate falls below 60 mL/min, the list of risk factors is expanded to include disturbances of mineral metabolism, anemia, fluid overload, uremic toxicity, and increased signs of oxidative stress and inflammation. Although many of the risk factors linked to CV burden are not related to the dialytic procedure, additional harm is introduced after the initiation of PD--with, for example, the presence of chronic infections and factors related to PD fluids, particularly reabsorption of glucose. In the present article, we review the impact of the novel risk factors introduced with the initiation of PD therapy, and we propose potential therapeutic strategies (which remain to be tested) for reducing CV mortality in this group of patients.

Comment on Indoxyl Sulfate-Review of Toxicity and Therapeutic Strategies. Toxins 2016, 8, 358.

Recently, the clinical and experimental evidences that support the toxic effects of indoxyl sulfate, a protein-bound uremic toxin in chronic kidney disease (CKD) patients, has been discussed. In this panorama, the authors described several in vitro and in vivo studies, suggesting that indoxyl sulfate may play a part in the pathogenesis of low turnover bone disease. However, the discussion claims the need for relevant clinical studies in CKD patients whose bone turnover biomarkers and bone histomorphometry were assessed in order to demonstrate the association between serum levels of indoxyl sulfate and bone turnover. We would like to underline the availability of this clinical data to support the concept that indoxyl sulfate may play a part in the pathogenesis of low turnover bone disease in CKD patients.

In vitro anti-inflammatory effects of vitamin D supplementation may be blurred in hemodialysis patients

OBJECTIVES: This study aimed to evaluate the potential anti-inflammatory effects of vitamin D supplementation under uremic conditions, both in vivo and in vitro, and its effects on the parameters of mineral metabolism. METHODS: Thirty-two hemodialysis patients were randomly assigned to receive placebo (N=14) or cholecalciferol (N=18) for six months. Serum levels of calcium, phosphate, total alkaline phosphatase, intact parathyroid hormone (iPTH), and vitamin D were measured at baseline and after three and six months. The levels of fibroblast growth factor-23 (FGF-23), interleukin-1β (IL-1β), and high-sensitivity C-reactive protein (hs-CRP) were also measured at baseline and at six months. Human monocytes were used for in vitro experiments and treated with cholecalciferol (150 nM) and uremic serum. Cell viability, reactive oxygen species (ROS) production, and cathelicidin (CAMP) expression were evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, dichloro-dihydro-fluorescein diacetate assay, and real time-quantitative polymerase chain reaction, respectively. RESULTS: Both patient groups were clinically and biochemically similar at baseline. After six months, the levels of vitamin D and iPTH were higher and lower, respectively, in the cholecalciferol group than in the placebo group (p<0.05). There was no significant difference between the parameters of mineral metabolism, such as IL-1β and hs-CRP levels, in both groups. Treatment with uremic serum lowered the monocyte viability (p<0.0001) and increased ROS production (p<0.01) and CAMP expression (p<0.05); these effects were counterbalanced by cholecalciferol treatment (p<0.05). CONCLUSIONS: Thus, cholecalciferol supplementation is an efficient strategy to ameliorate hypovitaminosis D in hemodialysis patients, but its beneficial effects on the control of secondary hyperparathyroidism are relatively unclear. Even though cholecalciferol exhibited anti-inflammatory effects in vitro, its short-term supplementation was not effective in improving the inflammatory profile of patients on hemodialysis, as indicated by the IL-1β and hs-CRP levels.

Effect of PKC-ß Signaling Pathway on Expression of MCP-1 and VCAM-1 in Different Cell Models in Response to Advanced Glycation End Products (AGEs).

Advanced glycation end products (AGEs) are compounds classified as uremic toxins in patients with chronic kidney disease that have several pro-inflammatory effects and are implicated in the development of cardiovascular diseases. To explore the mechanisms of AGEs-endothelium interactions through the receptor for AGEs (RAGE) in the PKC-ß pathway, we evaluated the production of MCP-1 and VCAM-1 in human endothelial cells (HUVECs), monocytes, and a coculture of both. AGEs were prepared by albumin glycation and characterized by absorbance and electrophoresis. The effect of AGEs on cell viability was assessed with an MTT assay. The cells were also treated with AGEs with and without a PKC-ß inhibitor. MCP-1 and VCAM-1 in the cell supernatants were estimated by ELISA, and RAGE was evaluated by immunocytochemistry. AGEs exposure did not affect cell viability, but AGEs induced RAGE, MCP-1, and VCAM-1 expression in HUVECs. When HUVECs or monocytes were incubated with AGEs and a PKC-ß inhibitor, MCP-1 and VCAM-1 expression significantly decreased. However, in the coculture, exposure to AGEs and a PKC-ß inhibitor produced no significant effect. This study demonstrates, in vitro, the regulatory mechanisms involved in MCP-1 production in three cellular models and VCAM-1 production in HUVECs, and thus mimics the endothelial dysfunction caused by AGEs in early atherosclerosis. Such mechanisms could serve as therapeutic targets to reduce the harmful effects of AGEs in patients with chronic kidney disease.