Telomere Length in Peripheral Blood Mononuclear Cells of Patients on Chronic Hemodialysis Is Related With Telomerase Activity and Treatment Duration.

Telomere shortening to a critical limit is associated with replicative senescence. This process is prevented by the enzyme telomerase. Oxidative stress and chronic inflammation are factors accelerating telomere loss. Chronic hemodialysis, typically accompanied by oxidative stress and inflammation, may be also associated with replicative senescence. To test this hypothesis, we determined telomere length and telomerase activity in peripheral blood mononuclear cells (PBMCs) in a cross-sectional study. Hemodialysis patients at the University Hospital Larissa and healthy controls were studied. Telomere length was determined by the TeloTAGGG Telomere Length Assay and telomerase activity by Telomerase PCR-ELISA (Roche Diagnostics GmbH, Mannheim, Germany). We enrolled 43 hemodialysis patients (17 females; age 65.0 ± 12.7 years) and 23 controls (six females; age 62.1 ± 15.7 years). Between the two groups, there was no difference in telomere length (6.95 ± 3.25 vs. 7.31 ± 1.96 kb; P = 0.244) or in telomerase activity (1.82 ± 2.91 vs. 2.71 ± 3.0; P = 0.085). Telomere length correlated inversely with vintage of hemodialysis (r = -0.332, P = 0.030). In hemodialysis patients, positive telomerase activity correlated with telomere length (r = 0.443, P = 0.030). Only age, and neither telomere length nor telomerase activity, was an independent survival predictor (hazard ratio 1.116, 95% confidence interval 1.009-1.234, P = 0.033). In this study, telomere length and telomerase activity in PBMCs are not altered in hemodialysis patients compared with healthy controls. Long duration of hemodialysis treatment is associated with telomere shortening and positive telomerase activity with an increased telomere length in PBMCs of hemodialysis patients. The underlying mechanism and clinical implications of our findings require further investigation.

Replacement of mycophenolate acid with everolimus in patients who became neutropenic after renal transplant.

OBJECTIVES: Neutropenia after kidney transplant is an adverse event usually treated with a dosage reduction of mycophenolic acid. We evaluated the efficacy and safety of substituting mycophenolic acid with everolimus in patients with persistent neutropenia after kidney transplant. MATERIALS AND METHODS: This study was a retrospective analysis. A total of 17 patients who were initially treated with mycophenolic acid (1912 ± 196 mg/d), calcineurin inhibitors, and methylprednisolone for kidney transplant were included. RESULTS: In 15 patients, neutropenia occurred within the first 3 months (during valganciclovir administration), and in 2 patients between the fourth and sixth month after transplant. One hundred eighteen episodes of neutropenia were recorded, originally treated by reducing the dosage of mycophenolic acid (765 ± 390 mg/d) and administering granulocyte colony-stimulating factor. Three patients experienced acute rejection 5 to 10 days after reducing the dosage of mycophenolic acid, and they were successfully treated with pulse steroids. Five patients developed cytomegalovirus infection 108 ± 65 days after the onset of neutropenia. After replacing mycophenolic acid with everolimus, episodes of neutropenia were observed in 6 patients. In 1 patient, discontinuing everolimus was necessary after 1.5 months of treatment. In 5 patients with cytomegalovirus infection, neutropenia subsided after termination of valganciclovir treatment. In the remaining 11 patients, no episodes of neutropenia were observed. No episodes of acute rejection occurred, and renal function remained stable during a followup of 47 ± 30 months (estimated glomerular filtration rate [eGFRMDRD6]: 45 ± 14 mL/min/1.73 m2→47 ± 22 mL/min/1.73 m2]. CONCLUSIONS: Replacing mycophenolic acid with everolimus appears to be a safe and effective alternative treatment in neutropenic renal transplant recipients.

Endothelin-1 plasma levels in hemodialysis treatment--the influence of type 2 diabetes.

In patients on chronic hemodialysis the prevalence of atherosclerosis is increased and is by far the leading cause of morbidity and mortality. Endothelin-1, an endothelium-derived peptide with vasoconstrictive and mitogenic effects on vascular smooth muscles, is involved in the pathogenesis of atherosclerosis. The aim of the present study was to investigate the time course of plasma endothelin-1 levels during a hemodialysis session and to explore the influence of preexisting type 2 diabetes mellitus. Forty-five clinically stable hemodialysis patients (21 females, 24 males; mean age 62 +/- 12 years) were evaluated. Patients with type 2 diabetes (n= 11) were compared with the group of patients without diabetes (n=34). Relative blood volume (BV) changes (hemoglobinometry) and blood pressure (BP) was measured. Samples were taken before, every hour during, and after hemodialysis. Plasma endothelin-1 levels were measured by enzyme-linked immunoassay (ELISA) and results were corrected according to hemoconcentration. Hemodialysis with an ultrafiltration of 2215 +/- 952 mL was performed. Total BV at the end of hemodialysis was 89.3% +/- 8.3% of the pretreatment volume. Plasma endothelin-1 was enhanced in hemodialysis patients compared to normal subjects and increased from 1.28 +/- 0.47 before to 1.44 +/- 0.54 pg/mL (ref. 0.3-0.9) at the end of hemodialysis (p<0.05). The BV change (r=0.41) and the BP (mean BP: r=0.34) correlated with plasma endothelin-1 at the end of hemodialysis (p<0.05). The levels of endothelin-1 were significantly higher in the group of dialysis patients with type 2 diabetes compared to nondiabetics in all measurements (p<0.05). These findings suggest a potential role of endothelin-1 in the pathogenesis of vascular dysfunction in diabetes mellitus. The dialysis procedure per se, through vasoconstriction due to BV decrease, local endothelial injury (a.v. fistula), or bioincompatibility reactions (foreign surface contact) may additionally alter endothelial cell functions.

Hemodialysis procedure does not affect the levels of sICAM-1 and sVCAM-1 in patients with end stage renal disease.

Atherosclerosis is by far the leading cause of mortality and morbidity in patients with end stage renal disease undergoing chronic hemodialysis (HD). Vascular endothelial cell adhesion molecules like the intercellular adhesion molecule-1 (ICAM-1) and the vascular cell adhesion molecule-1 (VCAM-1) are involved in the pathogenesis of atherosclerosis. Their soluble forms (sICAM-1, sVCAM-1) are considered potential serum markers of endothelial activation and atherosclerosis. The aim of this study was to clarify the influence of the HD procedure on the levels of sICAM-1 and sVCAM-1 in patients with end stage renal disease. We evaluated 35 clinically stable patients (18 males, 17 females, mean age 61 +/- 12) on chronic HD treatment. Diabetes mellitus coexisted in eight patients and arterial hypertension in 23 patients. Blood was drawn before, every hour during, and after a single HD session in each patient. Low-flux cuprophane dialyzers (GFS 12, Gambro, Lund, Sweden) were used in 22 and high-flux polysulfone dialyzers (Hemoflow F 60S, Fresenius, Oberursel, Germany) in 13 cases. At 30 min into the HD session (n=31, 20 low-flux HD, 11 high-flux HD) blood was drawn simultaneously from the entrance and the exit line of the dialyzer. From all these samples, serum concentrations of sICAM-1 and sVCAM-1 were determined by commercially available enzyme immunoassays (ELISA, R&D Systems, Minneapolis, USA). Results were corrected according to hemoconcentration, where appropriate. Plasma levels of sVCAM-1 were elevated in patients with end stage renal disease before the beginning of the dialysis session when compared to healthy controls (1449 +/- 497 ng/mL vs. 691 +/- 118 ng/mL). On the contrary, such an elevation was not found in the case of sICAM-1 (231 +/- 58.5 ng/mL vs. 236.4 +/- 96.8 ng/mL in healthy controls). These levels remained stable in all measurements throughout the dialysis procedure. Furthermore, serum sICAM-1 and sVCAM-1 levels remained unaltered after the passage of the dialyzer. The levels of sICAM-1 and sVCAM-1 were not influenced by the existence of diabetes mellitus, hypertension, or by the utilization of biocompatible, high flux dialyzers. Our study confirms that in chronic HD patients serum levels for sVCAM-1 are elevated. The levels of adhesion molecules are not affected by the HD procedure. These findings probably can be attributed to a decreased renal clearance or catabolism of sICAM-1 and sVCAM-1 and to the different sources of the two molecules. Neither coexisting diabetes mellitus nor arterial hypertension influences the circulating levels of these adhesion molecules. The functional role of sVCAM-1 and sICAM-1, the exact renal contribution to their metabolism, and their role as markers of atherosclerosis in chronic renal disease need further evaluation.