Maria Aparecida Dalboni

Phosphate Binder Impact on Bone Remodeling and Coronary Calcification – Results from the BRiC Study

Backgroundand Aims: Calcium-containing phosphate binders have been shown to increase the progression of vascular calcification in hemodialysis patients. This is a prospective study that compares the effects of calcium acetate and sevelamer on coronary calcification (CAC) and bone histology. Methods: 101 hemodialysis patients were randomized for each phosphate binder and submitted to multislice coronary tomographies and bone biopsies at entry and 12 months. Results: The 71 patients who concluded the study had similar baseline characteristics. On follow-up, the sevelamer group had higher levels of intact parathyroid hormone (498 ± 352 vs. 326 ± 236 pg/ml, p = 0.017), bone alkaline phosphatase (38 ± 24 vs. 28 ± 15 U/l, p = 0.03) and deoxypyridinoline (135 ± 107 vs. 89 ± 71 nmol/l, p = 0.03) and lower LDL cholesterol (74 ± 21 vs. 91 ± 28 mg/dl, p = 0.015). Phosphorus (5.8 ± 1.0 vs. 6 ± 1.0 mg/dl, p = 0.47) and calcium (1.27 ± 0.07 vs. 1.23 ± 0.08 mmol/l, p = 0.68) levels did not differ between groups. CAC progression (35 vs. 24%, p = 0.94) and bone histological diagnosis at baseline and 12 months were similar in both groups. Patients of the sevelamer group with a high turnover at baseline had an increase in bone resorption (eroded surface, ES/BS = 9.0 ± 5.9 vs. 13.1 ± 9.5%, p = 0.05), whereas patients of both groups with low turnover at baseline had an improvement in bone formation rate (BFR/BS = 0.015 ± 0.016 vs. 0.062 ± 0.078, p = 0.003 for calcium and 0.017 ± 0.016 vs. 0.071 ± 0.084 μm3/μm2/day, p = 0.010 for sevelamer). Conclusions: There was no difference in CAC progression or changes in bone remodeling between the calcium and the sevelamer groups.

Association of Changes in Bone Remodeling and Coronary Calcification in Hemodialysis Patients: A Prospective Study

BACKGROUND Vascular calcification is common and constitutes a prognostic marker of mortality in the hemodialysis population. Derangements of mineral metabolism may influence its development. The aim of this study is to prospectively evaluate the association between bone remodeling disorders and progression of coronary artery calcification (CAC) in hemodialysis patients. STUDY DESIGN Cohort study nested within a randomized controlled trial. SETTING & PARTICIPANTS 64 stable hemodialysis patients. PREDICTOR Bone-related laboratory parameters and bone histomorphometric characteristics at baseline and after 1 year of follow-up. OUTCOMES Progression of CAC assessed by means of coronary multislice tomography at baseline and after 1 year of follow-up. Baseline calcification score of 30 Agatston units or greater was defined as calcification. Change in calcification score of 15% or greater was defined as progression. RESULTS Of 64 patients, 38 (60%) of the patients had CAC and 26 (40%) did not [corrected]. Participants without CAC at baseline were younger (P < 0.001), mainly men (P = 0.03) and nonwhite (P = 0.003), and had lower serum osteoprotegerin levels (P = 0.003) and higher trabecular bone volume (P = 0.001). Age (P = 0.003; beta coefficient = 1.107; 95% confidence interval [CI], 1.036 to 1.183) and trabecular bone volume (P = 0.006; beta coefficient = 0.828; 95% CI, 0.723 to 0.948) were predictors for CAC development. Of 38 participants who had calcification at baseline, 26 (68%) had CAC progression in 1 year. Progressors had lower bone-specific alkaline phosphatase (P = 0.03) and deoxypyridinoline levels (P = 0.02) on follow-up, and low turnover was mainly diagnosed at the 12-month bone biopsy (P = 0.04). Low-turnover bone status at the 12-month bone biopsy was the only independent predictor for CAC progression (P = 0.04; beta coefficient = 4.5; 95% CI, 1.04 to 19.39). According to bone histological examination, nonprogressors with initially high turnover (n = 5) subsequently had decreased bone formation rate (P = 0.03), and those initially with low turnover (n = 7) subsequently had increased bone formation rate (P = 0.003) and osteoid volume (P = 0.001). LIMITATIONS Relatively small population, absence of patients with severe hyperparathyroidism, short observational period. CONCLUSIONS Lower trabecular bone volume was associated with CAC development, whereas improvement in bone turnover was associated with lower CAC progression in patients with high- and low-turnover bone disorders. Because CAC is implicated in cardiovascular mortality, bone derangements may constitute a modifiable mortality risk factor in hemodialysis patients.

Coronary Artery Calcification, Systemic Inflammation Markers and Mineral Metabolism in a Peritoneal Dialysis Population

Aims: To assess the prevalence of coronary artery calcification (CAC) in peritoneal dialysis (PD) patients and to determine whether comorbidities such as inflammation, dyslipidemia and mineral metabolism disorders correlate with its development. Methods: Forty-nine PD patients (45% male; median age, 52 years) were submitted to multislice computed tomography. Inflammatory markers, anti-oxidized LDL antibody, calcium–phosphate balance and lipid profiles were assessed. Results: Twenty-nine patients (59.2%) presented CAC (median calcium score, 234.7 Agatston units). Patients with CAC were older than those without, more frequently presented a history of coronary artery disease or hypertension and had lower HDL cholesterol levels, as well as presenting higher levels of osteoprotegerin and LDL oxidation. The logistic regression revealed that the independent determinants of CAC were age (odds ratio = 1.12; p = 0.006) and number of prescribed anti-hypertensive drugs (odds ratio = 2.38; p = 0.048). When the population was stratified by calcium score quartile, soluble Fas levels were significantly higher in patients with severe calcification. In patients younger than 45, CAC correlated positively with phosphorus levels (r = 0.52; p = 0.04). Conclusion: In PD patients, CAC is highly prevalent. Our results indicate that conditions such as inflammation and mineral disturbances are associated with its development.

Nec-1 Protects against Nonapoptotic Cell Death in Cisplatin-Induced Kidney Injury

Background/aims: Necrostatin-1 (Nec-1) inhibits necroptosis, a nonapoptotic cell death pathway. Acute kidney injury (AKI) is a clinical problem of high incidence and mortality. It involves several mechanisms of cell death. We aim to evaluate the effect of Nec-1 in the toxic kidney injury model by cisplatin. Methods: We analyzed the effect of Nec-1 in AKI by cisplatin in human proximal tubule cells by flow cytometry. Results: Our results show that Nec-1 has no effect on apoptosis in renal tubular epithelial cells (Nec-1 + Cis group 13.4 ± 1.7% vs. Cis group 14.6 ± 1.4%) (p > 0.05). But, in conditions in which apoptosis was blocked by benzyloxy-carbonyl-Val-Ala-Asp-fluoromethyl ketone (z-VAD-fmk) the use of Nec-1 completely reversed cell viability (Nec-1 + Cis + z-VAD group 72.9 ± 6.3% vs. Cis group 35.5 ± 2.2%) (p < 0.05) suggesting that Nec-1 has effect on nonapoptotic cell death (necroptosis). Conclusion: Our findings suggest that the combined use of apoptosis and necroptosis inhibitors can provide additional cytoprotection in AKI. Furthermore, this is the first study to demonstrate that Nec-1 inhibits tubular kidney cell death and restores cell viability via a nonapoptotic mechanism.

Association of endothelial nitric oxide synthase gene intron 4 polymorphism with end-stage renal disease.

Background:  Nitric oxide (NO) released from endothelial cells is related to the maintenance of physiological vascular tone. The impairment of endothelial NO generation brought about by gene polymorphism is considered one of the deterioration factors in progressive renal disease. In the endothelial nitric oxide synthase (eNOS) intron 4 polymorphism, the presence of the aa genotype has been associated with cardiovascular and renal disease. The aim of this study was to investigate the presence of eNOS gene intron 4 polymorphism in patients with end‐stage renal disease (ESRD).

TNF-α modulates statin effects on secretion and expression of MCP-1, PAI-1 and adiponectin in 3T3-L1 differentiated adipocytes

PURPOSE Systemic inflammatory conditions, as seen in obesity and in the metabolic syndrome, are associated with high plasmatic levels of proatherogenic and prothromboticadipokines and low levels of adiponectin. Inhibitors of HMG-CoA reductase have beneficial effects in reducing cardiovascular events attributed predominantly to its lipid-lowering effects and recent studies suggest that these effects might be due to its anti-inflammatory properties. Based on the pleiotropic properties of simvastatin we studied the effects of this drug on the secretion and expression of adiponectin, PAI-1 and MCP-1 in mature adipocytes under baseline conditions and after an inflammatory stimulation. MATERIALS AND METHODS The differentiated adipocytes were incubated with 10 μM simvastatin or vehicle and TNF-α 10 ng/mL or vehicle were added to treatment media. After 24h of incubation, the media was harvested and the proteins of interest were analyzed by Multiplex method. Gene expression was analyzed by real time-PCR. RESULTS The addition of TNF-α increased the expression and secretion of MCP-1 and PAI-1. However, stimulation did not interfere with the secretion of adiponectin, despite having significantly reduced its expression. Our data also demonstrated that simvastatin reduced the expression and secretion of MCP-1, under baseline (770.4 ± 199.9 vs 312.7 ± 113.7 and 1.00 ± 0.14 vs 0.63 ± 0.13, p<0.05, respectively) and inflammatory conditions (14945 ± 228.7 vs 7837.6 ± 847.4 and 24.16 ± 5.49 vs 14.97 ± 2.67, p<0.05, p<0.05, respectively). Simvastatin also attenuated the increase in expression and secretion of PAI-1 induced by TNF-α (16898.6 ± 1663.3 vs 12922.1 ± 843.9 and 5.19 ± 3.12 vs 0.59 ± 0.16, respectively p<0.05), but under baseline conditions had no effect on the expression or secretion of PAI-1. The statin increased the expression of adiponectin under baseline conditions and inflammatory stimulation (1.03 ± 0.08 vs 4.0 ± 0.96 and 0.77 ± 0.19 vs 2.16 ± 0.23, respectively, p<0.05) and also increased the secretion of this adipokine but only with the inflammatory stimulus (5347.7 ± 1789.3 vs 7327.3 ± 753.6, p<0.05). CONCLUSIONS Our findings suggested that simvastatin counteracted the stimulatory effect of TNF-α on secretion and expression of MCP-1, PAI-1 and adiponectin, implying a potential anti-atherogenic effect during the inflammatory process; these pleitropic effects were more pronounced with HMG-CoA reductase inhibitor.

Effect of phosphate binders on oxidative stress and inflammation markers in hemodialysis patients

It has been suggested that phosphate binders may reduce the inflammatory state of hemodialysis (HD) patients. However, it is not clear whether it has any effect on oxidative stress. The objective of this study was to evaluate the effect of sevelamer hydrochloride (SH) and calcium acetate (CA) on oxidative stress and inflammation markers in HD patients. Hemodialysis patients were randomly assigned to therapy with SH (n=17) or CA (n=14) for 1 year. Before the initiation of therapy (baseline) and at 12 months, we measured in vitro reactive oxygen species (ROS) production by stimulated and unstimulated polymorphonuclear neutrophils and serum levels of tumor necrosis factor α, interleukin‐10, C‐reactive protein, and albumin. There was a significant reduction of spontaneous ROS production in both groups after 12 months of therapy. There was a significant decrease of Staphylococcus aureus stimulated ROS production in the SH group. There was a significant increase in albumin serum levels only in the SH group. In the SH group, there was also a decrease in the serum levels of tumor necrosis factor α and C‐reactive protein. Our results suggest that compared with CA treatment, SH may lead to a reduction in oxidative stress and inflammation. Therefore, it is possible that phosphate binders exert pleiotropic effects on oxidative stress and inflammation, which could contribute toward decreasing endothelial injury in patients in HD.

Ascorbic acid reduces gentamicin-induced nephrotoxicity in rats through the control of reactive oxygen species

BACKGROUND & AIM Oxidative stress has been implicated in the pathophysiology of many forms of acute renal failure. The aim was examine the effect of vitamin C on oxidative stress and its relationship with nitric oxide on gentamicin-induced nephrotoxicity in rats. METHODS We utilized 32 Wistar rats allocated in four groups of eight animals each: control (CTL), vitamin C (VIT C), gentamicin (GENTA), and GENTA + VIT C; all groups were treated during seven days. RESULTS Serum urea and creatinine, serum and renal tissue malondialdehyde, blood superoxide anion and hydrogen peroxide in GENTA were increased vs CTL and vs VIT C, and decreased in GENTA + VIT C vs GENTA (all P < 0.05). Serum nitric oxide increased in GENTA vs CTL and vs VIT C, and reduced in GENTA + VIT C vs GENTA (P < 0.001). Urinary nitric oxide was reduced in GENTA vs CTL and vs VIT C and increased in GENTA + VIT C vs GENTA (P < 0.001). Severe degeneration of proximal tubules was present in GENTA, but only mild lesions were observed in GENTA + VIT C. CONCLUSION This study suggests that VIT C is a valuable tool to protect against GENTA-induced nephrotoxicity, by reducing reactive oxygen species and increasing the nitric oxide.

Clinical correlations and prognostic relevance of HGF, VEGF AND FGF expression in Brazilian patients with non-Hodgkin lymphoma

The aims of this study were to correlate HGF, VEGF and FGF serum levels and microvessel density (MVD) with cell origin, biological behavior, tumor load and prognosis in NHL. Eighty-seven consecutive previously untreated NHL patients had serum samples collected; 37 (42%) of them also had serum follow-up samples; the control group was composed of 10 healthy blood donors. Cytokine serum levels were determined by ELISA, and MVD was measured by CD34 staining in paraffin blocks. HGF mean serum level was significantly higher in both early and advanced NHL stages when compared with the control group. HGF was also significantly higher in aggressive and indolent NHL when compared with the control group. Also, mean serum level of HGF in aggressive NHL was significantly higher than in indolent NHL. Regarding International Prognostic Index (IPI), HGF mean serum level at diagnosis was significantly higher for patients with IPI >2 when compared to IPI ≤2. Sequential analyses of HGF, VEGF and FGF serum levels in NHL showed that serum HGF and VEGF levels decreased significantly after 6 months of treatment completion. Our findings suggest that HGF serum level is associated with tumor load and aggressiveness, and response to treatment results in a decrease in HGF serum levels in NHL patients.

Balance between cytokine production by peripheral blood mononuclear cells and reactive oxygen species production by monocytes in patients with chronic kidney disease.

Hemodialysis (HD) and peritoneal dialysis are associated with inflammatory events and immunological incompetence. The purpose of this study was to evaluate the effect of both uremia and dialysis modality on the production of cytokines and reactive oxygen species (ROS) by monocytes. four groups of subjects were studied: 28 chronic kidney disease (CKD) patients, 14 chronic HD patients, 14 patients on continuous ambulatory peritoneal dialysis (CAPD) patients, and 14 healthy volunteers. peripheral blood mononuclear cells (PBMC) were isolated from blood samples and incubated for 24 hr with or without lipopolysaccharide (LPS). TNF‐α and IL‐10 production by PBMC and serum levels of these cytokines were quantified by ELISA. Aliquots of whole blood were incubated in vitro and ROS production and phagocytosis were quantified by flow cytometry. Compared to the control group, Staphylococcus aureus–stimulated ROS production by monocytes was significantly lower in the HD group. The highest levels of unstimulated TNF‐α production in vitro were observed in the HD group. In the CKD group, as well as in the whole population, there were a negative correlation between TNF‐α production by unstimulated PBMC and ROS production by S. aureus–stimulated monocytes and a positive correlation between PMA‐stimulated ROS production by monocytes and unstimulated and LPS‐stimulated IL‐10 production by PBMC suggesting that the pro‐inflammatory state in CKD patients is associated with decreased response to infectious challenges.