Plasma levels of vasoactive regulatory peptides in patients receiving regular hemodialysis treatment

Adipokines and Gut Hormones in End-Stage Renal Disease

Cachexia is common in end-stage renal disease (ESRD) patients, and it is an important risk factor for poor quality of life and increased mortality and morbidity. Chronic inflammation is an important cause of cachexia in ESRD patients. In the present review, we examine recent evidence suggesting that adipokines or adipocytokines such as leptin, adiponectin, resistin, tumor necrosis factor α, interleukin-6, and interleukin-1β may play important roles in uremic cachexia. We also review the physiology and the potential roles of gut hormones, including ghrelin, peptide YY, and cholecystokinin in ESRD. Understanding the molecular pathophysiology of these novel hormones in ESRD may lead to novel therapeutic strategies.

Effect of Short-term Erythropoietin Therapy on Insulin Resistance and Serum Levels of Leptin and Neuropeptide Y in Hemodialysis Patients

INTRODUCTION

Insulin resistance (IR) is a known complication of end-stage kidney disease (ESKD). It may be an important therapeutic target in stages of chronic kidney disease.

AIM

The study was conducted to evaluate the effect of short-term treatment with recombinant human erythropoietin (rHuEpo) therapy on IR, serum leptin, and neuropeptide Y in ESKD patients on hemodialysis.

MATERIALS AND METHODS

Thirty ESKD patients were enrolled in the study and were randomly assigned into two groups. Erythropoietin (rHuEpo) group consisted of 15 patients (7 females, 8 males, mean age 47.8 ± 9.3 years) treated with rHuEpo therapy after each session of dialysis. No-rHuEpo group consisted of 15 patients (7 females, 8 males, mean age 45.5 ± 8.6 years) not treated with rHuEpo. In addition to, control group consisted of 15 healthy controls (6 females, 9 males, mean age 48.8 ± 11 years).

RESULTS

The mean fasting insulin (11 ± 4.2 mU/L) and homeostatic model assessment of IR (HOMA-IR) test (2.6 ± 1.1) were significantly higher in ESKD patients than control group (6.6 ± 1.4 mU/L and 1.5 ± 0.3, respectively). There were significant decreases in glycated hemoglobin (HbA1c) (5.6 ± 1%), fasting insulin level (9.3 ± 3.1 μU/mL), HOMA-IR (2.2 ± 0.7), and serum leptin levels (17.4 ± 8.7 ng/mL) also significant increase in neuropeptide Y levels (113 ± 9.9 pg/mL) after 3 months of rHuEpo therapy, in addition to further significantly decrease fasting insulin levels (7.1 ± 2.1 μU/mL) and HOMA-IR (1.7 ± 6) after 6 months in rHuEpo group. In contrast, there were significantly increases in HbA1c% (5.9 ± 0.5%) and leptin levels (42.3 ± 25.3 ng/mL) in No-rHuEpo group throughout the study.

CONCLUSION

IR and hyperleptinemia are improved by recombinant human erythropoietin therapy.

Neurohumoral changes in patients with left ventricular dysfunction following acute myocardial infarction and the effect of nitrate therapy: a randomized, double-blind, placebo-controlled long-term study

BACKGROUND

Several neurohumoral mechanisms involved in cardiovascular regulation are activated in the failing heart, but only limited information is available regarding the influence of long-term nitrate therapy.

MATERIALS AND METHODS

This was a double-blind, randomized comparison of isosorbide-5-mononitrate (IS-5-MN), 60 mg given orally, once daily for 11 months to patients (n = 47) with left ventricular (LV) dysfunction following acute myocardial infarction (AMI). Forty-five patients received placebo. All patients received ramipril.Plasma natriuretic peptides (atrial [ANP] and brain [BNP] natriuretic peptide), epinephrine, norepinephrine (NEPI), antidiuretic hormone, aldosterone (Aldo), renin activity (PRA), substance P, neuropeptide Y-like immunoreactivity, calcitonin gene-related peptide, and vasoactive intestinal peptide were measured at baseline and at the end of the treatment period. Clinical, echocardiographic, and hemodynamic data were also obtained.

RESULTS AND CONCLUSIONS

Chronic nitrate therapy does not significantly affect the neurohumoral status in patients with LV dysfunction after AMI, apart from a decrease in ANP. Some hormones are more closely associated with diastolic dysfunction/increased volume load (ANP and BNP) and others are more closely associated with systolic dysfunction (PRA, NEPI, Aldo). There is a temporal dissociation of these 2 groups of hormones 1 year post infarction: ANP and BNP decrease, whereas NEPI and Aldo show a slight increase. BNP levels do not reflect all important pathophysiologic mechanisms in heart failure. Consequently, the use of other neurohormonal factors than BNP for monitoring of heart failure therapy should be explored.

Cardiopulmonary bypass influences the plasma levels of calcitonin gene-related peptides in dogs: effects of hemofiltration and hemodilution

Calcitonin gene-related peptides (CGRP), which are potent vasodilators, are elevated during cardiopulmonary bypass (CPB) in humans. We evaluated the plasma levels of CGRP in dogs during CPB with hemofiltration with and without hemodilution. Female beagles were divided into control (n=5) and hemodilution (n=5) groups. The CPB with hemofiltration was performed with or without hemodilution. For the measurement of CGRP, blood samples were collected pre-CPB, during CPB, and post-CPB. The concentrations of CGRP in the hemofiltration solution were measured. Although the CPB elevated the plasma CGRP levels in both groups, its elevation was significant in the hemodilution group when compared to the pre-CPB levels. CGRP levels returned to normal post-CPB. Significant differences were found between the two groups in the CGRP amount in hemofiltration. The results show that hemofiltration should be used during CPB to decrease the plasma levels of CGRP.

Lipid peroxidation is not increased in heart failure patients on modern pharmacological therapy

BACKGROUND

Previous studies support a role of oxygen-free radicals in the development of congestive heart failure (CHF). The aim of this study was to investigate whether lipid peroxidation is increased in CHF patients on modern pharmacological therapy and whether there is a positive correlation between plasma levels of markers of lipid peroxidation and severity of heart failure (HF). Plasma malondialdehyde (MDA) and isoprostanes are often used as markers of lipid peroxidation and oxidative stress. We also studied whether long-term treatment with isosorbide-5-mononitrate (IS-5-MN) in combination with standard HF therapy affects P-MDA levels in patients with evidence of left ventricular (LV) dysfunction following acute myocardial infarction (AMI).

MATERIALS AND METHODS

Ninety-two patients with clinical or echocardiographic evidence of LV-dysfunction following AMI were randomized to treatment with either IS-5-MN or placebo. In a subgroup of 83 patients with available plasma MDA, echocardiography, right-heart catherization, and plasma natriuretic peptides were evaluated. Control subjects were 80 healthy blood donors. A second study group consisted of 56 patients with CHF, evaluated with respect to LV function, brain natriuretic peptide and markers of oxidative stress (P-MDA and 8-isoprostane). The second control group comprised 50 healthy subjects.

RESULTS

Lipid peroxidation measured by P-MDA and 8-isoprostane was not increased in patients with LV dysfunction treated with standard HF therapy. No positive correlation was found to the severity of HF. Long-term IS-5-MN therapy did not influence P-MDA concentrations.

CONCLUSIONS

Although results from many experimental and clinical studies suggest that oxidative stress is increased in HF, this may not be true for patients treated with beta blockers and inhibitors of the renin-angiotensin system.

Prospective Study of Neuropeptide Y as an Adverse Cardiovascular Risk Factor in End-Stage Renal Disease

ABSTRACT. Chronic renal insufficiency is a situation characterized by high plasma concentration of neuropeptide Y (NPY). Because this neuropeptide interferes with cardiovascular (CV) function, it is possible that it is involved in the high CV-related morbidity and mortality of these patients. To test this hypothesis, a follow-up study was performed (average duration, 34 mo; range 0.2 to 52.0 mo) in a cohort of 277 patients with end-stage renal disease receiving chronic dialysis. Univariate analysis revealed that plasma NPY was directly related to plasma norepinephrine (r = 0.37, P < 0.001) and epinephrine (r = 0.17, P = 0.005), exceeding the upper limit of the normal range in the majority of patients with end-stage renal disease (170 of 277, 61%). One hundred thirteen patients had one or more fatal and nonfatal CV events; 112 patients died, 66 of them (59%) of CV causes. Plasma NPY failed to predict all-cause mortality but was an independent predictor of adverse CV outcomes (hazard ratio [10 pmol/L increase in plasma NPY], 1.32; 95% confidence interval, 1.09 to 1.60; P = 0.004) in a Cox proportional-hazard model that included a series of traditional and nontraditional CV risk factors. Plasma NPY maintained its predictive power for CV events in statistical model including plasma norepinephrine. Plasma NPY predicts incident CV complications in end-stage renal disease. Controlled trials are needed to establish whether interference with the sympathetic system, NPY, or both may reduce the high CV morbidity and mortality of dialysis patients. E-mail: carmine.zoccali@tin.it

Increased plasma levels of neuropeptide Y in hepatorenal syndrome

BACKGROUND/AIMS

To investigate the relationship between neuropeptide Y (NPY), a potent renal vasoconstrictor peptide released upon marked stimulations of sympathetic nervous system (SNS), and renal and circulatory function in cirrhosis.

METHODS

Plasma levels of NPY (radioimmunoassay) and norepinephrine and renal function parameters were determined in 17 healthy controls, nine patients with cirrhosis without ascites, and 37 patients with cirrhosis and ascites, of whom 12 had hepatorenal syndrome (HRS).

RESULTS

Patients with ascites showed circulating levels of NPY similar to those of patients without ascites and controls (73+/-4, +/-4 and 68+/-4 pmol/l, respectively; NS). However, patients with HRS had significantly increased levels of NPY with respect to the other groups (110+/-6 pmol/l; P<0.001). NPY levels correlated inversely with renal plasma flow and glomerular filtration rate and directly with norepinephrine. In patients with HRS (n=6) treatment with terlipressin and albumin was associated with a marked improvement in circulatory and renal function and marked suppression of NPY and norepinephrine levels.

CONCLUSIONS

Patients with HRS have increased levels of NPY which are related to circulatory dysfunction and SNS activation and may contribute to renal vasoconstriction.

Circulating levels of neuropeptides (CGRP, VIP, NPY) in patients with fulminant hepatic failure

The present study investigated the circulating levels and cerebral fluxes of calcitonin gene-related peptide (CGRP), vasoactive intestinal peptide (VIP), and neuropeptide Y (NPY) and their relation to cerebral blood flow (CBF) during normoventilation and hyperventilation in patients with fulminant hepatic failure (FHF). Sixteen patients with FHF were studied and compared to six patients with cirrhosis of the liver. CBF was measured by the (133)Xe wash-out technique. Blood samples were obtained simultaneously from the artery and internal jugular bulb. Concentrations of CGRP and VIP were higher in FHF than in cirrhosis, 87 (55-218) vs. 29 (21-42) pmol/L, and 11 (6-29) vs. 5 (3-9)pmol/L, respectively. NPY was normal, none of the measures were related to CBF, and there was no detectable net brain fluxes. Hyperventilation did not alter any of the measures. CGRP and VIP in FHF seem to reflect hemodynamic changes in the systemic rather than in the cerebral circulation.

Blood pressure and metabolic factors in relation to chronic pain

Physical pain is a major trigger for changes in many homeostatic systems of the body physiology. Our aim was to study the relationship between blood pressure, metabolism and pain perception in subjects with chronic pain symptoms. This was undertaken in a population-based study in primary health care, including subjects with widespread pain (n = 16), or localized pain (n = 15), and pain-free controls (n = 14). The main outcome measures were office and ambulatory blood pressure, glucose, insulin, lipids, and beta-endorphin. Subjects with widespread pain were more obese and showed higher levels than controls (p < 0.05) of fasting glucose (4.9 vs 4.5 mmol/l), cholesterol (6.9 vs 5.8 mmol/l) and office systolic blood pressure (133 vs 120 mmHg), while the subjects reporting localized pain had values in-between. Ambulatory blood pressure, insulin and beta-endorphin levels did not differ between the groups. In conclusion, subjects with widespread and/or intense chronic pain have higher BMI, more pronounced metabolic disturbances and higher (office) systolic blood pressure, but not ambulatory blood pressure, than subjects without chronic pain. Future epidemiological studies are needed to test whether this is compatible with increased cardiovascular risk.

Elevated plasma concentrations of neuropeptide Y in children and adults with chronic and terminal renal failure

Neuropeptide Y (NPY) is a peptide hormone that is expressed, stored, and released in sympathetic neurones together with noradrenaline. Elevated plasma concentrations of NPY have been reported in patients with neural crest tumors (neuroblastoma, pheochromocytoma) and following exercise. We studied plasma concentrations of NPY in children and adults with chronic and terminal renal failure and compared them with those in healthy controls. Neuropeptide Y was significantly higher in children and adolescents receiving peritoneal dialysis (5.3 +/- 2.8 pmol/L; n = 11 [mean +/- SD]) or hemodialysis (5.4 +/- 2.1 pmol/L; n = 14) than in healthy children (2.3 +/- 0.9 pmol/L; n = 19) or pediatric patients with impaired renal function who are not receiving dialysis (2.7 +/- 0.6 pmol/L; n = 8; mean glomerular filtration rate, 41 mL/min x 1.73 m2). There was a small but insignificant negative correlation between glomerular filtration rate and NPY concentrations in children with impaired renal function (r = 0.49; P = 0.25). In healthy adults, NPY concentration was similar to that in healthy children (1.8 +/- 1.0 pmol/L; n = 13), and it was significantly elevated in adults receiving hemodialysis (5.9 +/- 1.7 pmol/L; n = 16). No significant changes in NPY concentrations were found before and after hemodialysis in pediatric or adult patients. We conclude that plasma concentrations of NPY are elevated in patients with chronic renal failure who are receiving either peritoneal or hemodialysis, but not in patients with moderately impaired renal function. Whether elevated NPY concentration indicates increased sympathetic activity or is caused by reduced NPY clearance remains to be shown.

Effects of haemodialysis session on plasma beta-endorphin, ACTH and cortisol in patients with end-stage renal disease

The effect of a regular haemodialysis session on the plasma concentrations of beta-endorphin, ACTH and cortisol was investigated in 14 patients with end-stage renal disease and 20 healthy controls. Blood for analysis of beta-endorphin, ACTH and cortisol was sampled before and immediately after haemodialysis. In four patients the dialysate was studied for presence of these hormones, but showed no specific activity. The predialysis beta-endorphin, ACTH and cortisol levels did not differ significantly from the control values. The postdialysis levels were significantly higher than the predialysis. Significant linear correlation was found between plasma ACTH and beta-endorphin values in the postdialysis samples. The similarity of plasma beta-endorphin, ACTH and cortisol levels in patients with end-stage renal disease before dialysis and in normal controls indicated integrity of the hypothalamic pituitary-adrenal axis. The significantly increased levels after the dialysis session and the significant correlation between postdialysis plasma beta-endorphin and ACTH suggest that the haemodialysis session was a stressful event.

Circulating neuropeptide Y in plasma from uremic patients consists of multiple peptide fragments

Increased plasma levels of neuropeptide Y (NPY)-like immunoreactivity (p-NPY-LI) have been described in hemodialysis (HD) patients. In this investigation the effect of a standard HD on p-NPY-LI, analyzed by radioimmunoassay and reverse-phase high performance liquid chromatography (HPLC), was studied. During dialysis p-NPY-LI increased from 128 +/- 5 to 154 +/- 8 pmol/l (p < 0.01). The change in p-NPY-LI during the treatment correlated with the ultrafiltration volume (rs = +0.72, p < 0.05). The HPLC separation revealed a complex pattern of NPY-immunoreactive peptides. This was true of the plasma of the control subjects as well as of the uremic plasma. In the case of the controls and the HD patients prior to dialysis, the amount of NPY-LI was rather small. After the dialysis qualitative as well as quantitative changes of the chromatogram were found. Some of the peaks seemed to have a retention time similar to that of the known fragments of synthetic human NPY used as markers. In conclusion, an increase in p-NPY-LI occurred during the dialysis, probably due to fluid removal. The increased level of NPY-LI in uremic plasma represents a mixture of different NPY fragments.

Endothelin-1 in children with chronic renal failure

Endothelin-1 (ET-1) was measured after extraction from plasma of normal adults (5.9 +/- 1.9 pg/ml, n = 22), normal children (7.1 +/- 1.86 pg/ml, n = 29), non-haemodialysed children with chronic renal failure (CRF) (11.1 +/- 1.8 pg/ml), n = 10), renal graft recipients (9.5 +/- 3.4 pg/ml, n = 37), haemodialysed children 24 h after a haemodialysis session (20.02 +/- 10.9 pg/ml, n = 26) and haemodialysed children before and after a haemodialysis session (15.31 +/- 10.6 and 13.8 +/- 8.5 respectively, n = 14). A sensitive and specific radioimmunoassay was used. ET-1 was significantly higher in non-haemodialysed CRF children and in renal graft recipients than in normal children (P < 0.001 and P < 0.01, respectively) and significantly higher in haemodialysed children when compared with normal children, non-haemodialysed CRF children and renal graft recipients (P < 0.001). ET-1 concentrations were similar in normal children and normal adults. ET-1 was inversely correlated with glomerular filtration rate in non-haemodialysed CRF children (r = -0.39, P < 0.01) and positively correlated with extracellular volume in haemodialysed children (r = 0.435, P < 0.03). After haemodialysis, ET-1 increased in 6 and decreased in 8 of the 14 children studied before and after a haemodialysis session.