The Importance of Early Diagnosis and Intervention in Chronic Kidney Disease: Calls-to-Action from Nephrologists Based Mainly in Central/Eastern Europe.

BACKGROUND: Chronic kidney disease (CKD) has a global prevalence of 9.1-13.4%. Comorbidities are abundant and may cause and affect CKD. Cardiovascular disease strongly correlates with CKD, increasing the burden of both diseases. SUMMARY: As a group of 15 clinical nephrologists primarily practicing in 12 Central/Eastern European countries, as well as Israel and Kazakhstan, herein we review the significant unmet needs for patients with CKD and recommend several key calls-to-action. Early diagnosis and treatment are imperative to ensure optimal outcomes for patients with CKD, with the potential to greatly reduce both morbidity and mortality. Lack of awareness of CKD, substandard indicators of kidney function, suboptimal screening rates, and geographical disparities in reimbursement often hamper access to effective care. KEY MESSAGES: Our key calls-to-action to address these unmet needs, thus improving the standard of care for patients with CKD, are the following: increase disease awareness, such as through education; encourage provision of financial support for patients; develop screening algorithms; revisit primary care physician referral practices; and create epidemiological databases that rectify the paucity of data on early-stage disease. By focusing attention on early detection, diagnosis, and treatment of high-risk and early-stage CKD populations, we aim to reduce the burdens, progression, and mortality of CKD.

Spectrally and Time-Resolved Fluorescence Imaging of 22-NBD-Cholesterol in Human Peripheral Blood Mononuclear Cells in Chronic Kidney Disease Patients.

The interaction of the fluorescent probe 22-NBD-cholesterol with membranes of human peripheral blood mononuclear cells (PBMC) was tested by time- and spectrally resolved fluorescence imaging to monitor the disturbance of lipid metabolism in chronic kidney disease (CKD) and its treatment with statins. Blood samples from healthy volunteers (HV) and CKD patients, either treated or untreated with statins, were compared. Spectral imaging was done using confocal microscopy at 16 spectral channels in response to 458 nm excitation. Time-resolved imaging was achieved by time-correlated single photon counting (TCSPC) following excitation at 475 nm. The fluorescence of 22-NBD-cholesterol was mostly integrated into plasmatic membrane and/or intracellular membrane but was missing from the nuclear region. The presence of two distinct spectral forms of 22-NBD-cholesterol was uncovered, with significant variations between studied groups. In addition, two fluorescence lifetime components were unmasked, changing in CKD patients treated with statins. The gathered results indicate that 22-NBD-cholesterol may serve as a tool to study changes in the lipid metabolism of patients with CKD to monitor the effect of statin treatment.

[Vitamin D3 supplementation and cellular calcium homeostasis in patients with chronic kidney disease]. / Suplementácia vitamínu D3 a bunková homeostáza vápnika u pacientov pri chronickej chorobe obliciek.

Mini review summarizes the results of our studies focused on elucidation of the pathophysiological mechanisms of altered calcium homeostasis in nonexcitable cells from patients with early stages of chronic kidney disease (CKD), as well as on determining the effect of vitamin D3 supplementation on these mechanisms. The basic mechanisms of calcium entry to and removal of the cell are already changed in early stages of CKD. These disturbances cause an increased the concentration of cytosolic free calcium ([Ca2+]i), which may change a number of cellular processes, and the expression of various signaling molecules. Vitamin D3 supplementation is a standard procedure of vitamin D insufficiency/ deficiency correction in these patients. The pleiotropic effects of vitamin D may be involved in the modulation of cellular calcium homeostasis. Vitamin D3 supplementation resulted in a reduction in [Ca2+]i by affecting of specific transport systems of calcium cations entry to and removal of the cell. The normalization [Ca2+]i can have a beneficial effect on intracellular signalling, and thus positively influence the functioning of cells, tissues or organs.Key words: cellular calcium homeostasis - chronic kidney disease - intracellular calcium - vitamin D.

The Impact of Vitamin D3 Supplementation on Mechanisms of Cell Calcium Signaling in Chronic Kidney Disease.

Intracellular calcium concentration in peripheral blood mononuclear cells (PBMCs) of patients with chronic kidney disease (CKD) is significantly increased, and the regulatory mechanisms maintaining cellular calcium homeostasis are impaired. The purpose of this study was to examine the effect of vitamin D3 on predominant regulatory mechanisms of cell calcium homeostasis. The study involved 16 CKD stages 2-3 patients with vitamin D deficiency treated with cholecalciferol 7000-14000 IU/week for 6 months. The regulatory mechanisms of calcium signaling were studied in PBMCs and red blood cells. After vitamin D3 supplementation, serum concentration of 25(OH)D3 increased (P < 0.001) and [Ca(2+)]i decreased (P < 0.001). The differences in [Ca(2+)]i were inversely related to differences in 25(OH)D3 concentration (P < 0.01). Vitamin D3 supplementation decreased the calcium entry through calcium release activated calcium (CRAC) channels and purinergic P2X7 channels. The function of P2X7 receptors was changed in comparison with their baseline status, and the expression of these receptors was reduced. There was no effect of vitamin D3 on P2X7 pores and activity of plasma membrane Ca(2+)-ATPases. Vitamin D3 supplementation had a beneficial effect on [Ca(2+)]i decreasing calcium entry via CRAC and P2X7 channels and reducing P2X7 receptors expression.

Purinergic P2X7 receptors participate in disturbed intracellular calcium homeostasis in peripheral blood mononuclear cells of patients with chronic kidney disease.

BACKGROUND: P2X(7) receptors intervene with lymphocyte activation and are responsible for multiple processes, including calcium influx. Here, we studied the participation of P2X(7) receptors in disturbed intracellular calcium homeostasis regulation in early-stage chronic kidney disease (CKD). METHODS: The study involved 20 healthy volunteers and 20 CKD stage 2-3 patients. The free cytosolic calcium concentration ([Ca(2+)](i)) was measured using fluorimetry. The P2X(7) pore function was evaluated by the fluorescent dye ethidium bromide. RESULTS: In peripheral blood mononuclear cells (PBMCs) of patients, [Ca(2+)](i), intracellular calcium stores and the capacitative calcium entry were increased when compared with healthy subjects. The agonist of P2X(7) receptor BzATP caused a sustained increase in [Ca(2+)](i) in both groups, but the effect was smaller in patients. The antagonist at the P2X(7) receptor KN-62 reduced [Ca(2+)](i) in patients, but had no effect in healthy subjects. In patients, the permeability of ethidium bromide through P2X(7) pores, as well as through BzATP-activated and KN-62-inhibited pores, was distinct from permeability in healthy volunteers. CONCLUSIONS: These results demonstrate that the calcium signaling pathway in PBMCs of CKD patients is defective already in CKD stage 2-3, and the pore-forming P2X(7) receptors are involved in these pathophysiological processes.

Intracellular calcium homeostasis in patients with early stages of chronic kidney disease: effects of vitamin D3 supplementation.

BACKGROUND: Chronic renal failure has been referred to as a state of cellular calcium toxicity. The aim of this study was to investigate the status of free cytosolic calcium ([Ca(2+)](i)), intracellular calcium reserves and the capacitative calcium entry in peripheral blood mononuclear cells (PBMCs) of early-stage chronic kidney disease (CKD) patients, and to determine the effect of vitamin D(3) supplementation on these parameters. METHODS: The study involved 44 patients with CKD stages 2-3; 27 of them were treated with cholecalciferol (5000 IU/week) for 12 months. [Ca(2+)](i) was measured using Fluo-3 AM fluorimetry. Intracellular calcium reserves were emptied by the application of thapsigargin (Tg), a specific inhibitor of endoplasmic reticulum Ca(2+)-ATPase. 2-Aminoethyl-diphenyl borate (2APB) was used to examine the capacitative calcium entry. RESULTS: [Ca(2+)](i) of CKD patients was substantially higher in comparison with healthy subjects: 123 (115-127) versus 102 (98-103) nmol/l, P < 0.001. The calcium concentration of Tg-sensitive stores and the capacitative calcium entry were also significantly increased in CKD patients. After the 12-month vitamin D(3) supplementation, there was a marked decrease in [Ca(2+)](i) [105 (103-112) nmol/l, P < 0.001 versus baseline], independently of the increase in 25(OH)D(3) or the decrease in PTH levels. No significant changes in intracellular calcium reserves and the capacitative calcium entry were found. CONCLUSIONS: Our results demonstrate that (1) [Ca(2+)](i), intracellular calcium stores and the capacitative calcium entry were significantly increased already in early stages of CKD; (2) long-term vitamin D(3) supplementation normalized [Ca(2+)](i) without any effect on intracellular calcium reserves or the capacitative calcium entry.

Effects of long-term cholecalciferol supplementation on mineral metabolism and calciotropic hormones in chronic kidney disease.

BACKGROUND: Data on the efficacy and safety of long-term vitamin D supplementation in chronic kidney disease (CKD) are scarce. We assessed the effects of the 12-month vitamin D(3) treatment on mineral metabolism and calciotropic hormones in patients with CKD stages 2-4. METHODS: Eighty-seven patients (mean age 66 years, men/women 33/54) were randomized to cholecalciferol treatment with either 5,000 or 20,000 IU/week. Serum calcium, phosphate, 25(OH)D(3), 1,25(OH)(2)D(3), PTH and urinary mineral concentrations were obtained at baseline and after 4, 8 and 12 months. RESULTS: The median serum mineral concentrations were normal and not changed throughout the study. The number of hypercalciuric patients slightly increased with higher dose, but no sustained rise in calciuria was present. Vitamin D insufficiency/deficiency was revealed in 72 (83%) patients at baseline and 37 (43%) at month 12. The 25(OH)D(3) levels increased more with higher dose; a rise in 1,25(OH)(2)D(3) was less impressive. The parathyroid hormone (PTH) concentrations were reduced, but the number of subjects with PTH below the lower limit for CKD stage 3 increased equally with both doses. CONCLUSIONS: Vitamin D insufficiency/deficiency in CKD significantly improved after the 12-month cholecalciferol treatment, with higher dose being more effective and equally safe. Further studies of vitamin D(3) effects on bone metabolism are warranted.

Oral sulodexide reduces albuminuria in microalbuminuric and macroalbuminuric type 1 and type 2 diabetic patients: the Di.N.A.S. randomized trial.

Diabetic nephropathy may be effectively prevented and treated by controlling glycemia and administering angiotensin-converting enzyme (ACE) inhibitors. However, strict metabolic control can be difficult, and ACE inhibitors may be poorly tolerated and only partially effective, particularly in diabetes mellitus type 2 (DM2), warranting the search for ancillary treatment. Sulodexide is a glycosaminoglycan, a new class of drug that has demonstrated nephroprotective activity in experimental investigations. The Di.N.A.S. study was a randomized, double-blind, placebo-controlled, multicenter, dose-range finding trial to evaluate the extent and duration of the hypoalbuminuric effect of oral sulodexide in diabetic patients. A total of 223 microalbuminuric and macroalbuminuric DM1 and DM2 patients with serum creatinine < or =150 micromol/L and stable BP and metabolic control were recruited. They were randomly allocated to one of four groups: 50 mg/d, 100 mg/d, or 200 mg/d sulodexide daily or placebo for 4 mo (T0 to T4), with 4 mo of follow-up after drug suspension (T4 to T8). Treatment with 200 mg/d sulodexide for 4 mo significantly reduced log albumin excretion rate (logAER) from 5.25 +/- 0.18 at T0 to 3.98 +/- 0.11 at T4 (P < 0.05), which was maintained till T8 (4.11 +/- 0.13; P < 0.05 versus T0). Moreover, the sulodexide-induced percent reductions in AER at T4 were significantly different from the placebo value at T4 and approximately linear to dose increments (30% [confidence limits, 4 to 49%], P = 0.03; 49% [30 to 63%], P = 0.0001; and 74% [64 to 81%], P = 0.0001 in the sulodexide 50, 100, and 200 mg/d groups, respectively. At T8, the sulodexide 200 mg/d group maintained a 62% (45 to 73%) AER significant reduction versus placebo (P = 0.0001). Subanalysis by type of diabetes (DM1 versus DM2, microalbuminuric versus macroalbuminuric, or on concomitant ACE inhibitors versus not on ACE inhibitors) demonstrated similar findings. These effects were obtained without any significant variation in metabolic control and BP or serum creatinine. Very few adverse events were reported; none were serious. In conclusion, a 4-mo course of high doses of sulodexide significantly and dose-dependently improves albuminuria in DM1 and DM2 patients and micro- or macroalbuminuric patients with or without concomitant ACE inhibition. The effect on albuminuria is long-lasting and seemingly additive to the ACE inhibitory effect.