Low serum fetuin-A concentration predicts poor outcome only in the presence of inflammation in prevalent haemodialysis patients.

BACKGROUND: Fetuin-A, a negative acute phase protein that inhibits vascular calcification, has a controversial association with mortality in chronic kidney disease (CKD) patients. Chronic inflammation, which is common in CKD, may promote vascular calcification. MATERIALS AND METHODS: We investigated the impact of inflammation on the relationship between serum fetuin-A and mortality (42 months) in 222 prevalent haemodialysis (HD) patients. RESULTS: Serum fetuin correlated negatively with comorbidity score (assessed by Davies score) and circulating inflammatory markers. Patients with low fetuin-A levels (< median) had higher mortality (Hazard ratio 'HR' 2.2; CI 1.4-3.5, P < 0.001), but this association was lost after adjustment for age, gender, comorbidities score, dialysis vintage and inflammation (CRP > median). In inflamed patients with low fetuin a significantly independent association with mortality (HR 2.3; CI 1.2-4.5, P = 0.01) was observed compared to non-inflamed patients with high fetuin-A, after adjusting for the same variables. Non-inflamed patients with low fetuin-A and inflamed patients with high fetuin-A did not have increased mortality compared to non-inflamed patients with high fetuin-A. CONCLUSIONS: The results show that low levels of serum fetuin-A are associated with increased mortality in HD patients only in the presence of inflammation. This suggests that coexistence of a low serum fetuin-A level and low-grade inflammation exerts an additive effect on the risk of death in HD patients.

The long pentraxin PTX-3 in prevalent hemodialysis patients: associations with comorbidities and mortality.

BACKGROUND: Pentraxin (PTX)-3, a new candidate marker for inflammation is expressed in a variety of cell types. Recently, we have shown that increase in PTX-3 level is associated with clinical outcome in incident CKD stage 5 patients at start of renal replacement therapy. However, no data are available on PTX-3 and its relationship with clinical outcome in prevalent dialysis patients. METHODS: We analyzed plasma PTX-3 concentrations in relation to comorbidities (Davies score), protein-energy wasting (PEW) and inflammation markers in 200 prevalent hemodialysis (HD) patients, aged 64 +/- 14 years, who had been on HD treatment for a median period of 36 months. Survival (42 months) was analyzed in relation to PTX-3 levels (high PTX-3 tertile vs. low two tertiles). RESULTS: Plasma PTX-3 correlated positively with C-reactive protein and interleukin-6, and negatively with s-albumin and fetuin-A. Patients with cardiovascular disease (CVD) and PEW had higher levels of PTX-3 than their counterparts and PTX-3 was associated with comorbidity score. In multiple logistic regression analysis, the high comorbidity score and PEW were the significant predictive variables of high PTX-3. In unadjusted analysis high PTX-3 was significantly associated with all-cause mortality. After adjustment for sex, age, dialysis vintage, comorbidity score, PEW and CRP using the multivariate Cox regression analysis, death rate was still significantly higher in patients with high PTX-3 (HR 1.7; CI 1.1-2.7, P = 0.03). CONCLUSION: Markedly increased levels of PTX-3 were found in HD patients with signs of CVD and PEW. In addition, the concentration of PTX-3 was associated with inflammation markers and comorbidity score. Our data also shows that high PTX-3 level was independently associated with all-cause mortality.

Clinical and biochemical implications of low thyroid hormone levels (total and free forms) in euthyroid patients with chronic kidney disease.

OBJECTIVES: In this study, we explore the associations of decreased thyroid hormone levels with inflammation, wasting and survival in biochemically euthyroid patients with end-stage renal disease (ESRD). DESIGN: After exclusion of 23 patients with thyroid-stimulating hormone (TSH) values outside the normal range (0.1-4.5 mIU L(-1)), 187 clinically and biochemically euthyroid incident ESRD stage 5 patients starting dialysis were followed for a median of 20 (range 1-60) months. Measurements of total and free forms of thyroid hormones, s-albumin, hs-CRP, interleukin (IL)-6, vascular adhesion molecule (VCAM)-1 and insulin-like growth factor 1 (IGF-1) were performed at baseline. RESULTS: In this population, 17 out of 210 patients (8%) were defined as subclinically hypothyroid. Multivariate analysis, according to receiver operating characteristic (ROC) curves, showed that mortality was best predicted by total triiodothyronine (T3). When using the cut-off levels derived from ROC, low T3 levels were associated with increased inflammation (higher hs-CRP, IL-6 and VCAM-1) and lower concentration of both s-albumin and IGF-1. Finally, low T3 but not low free triiodothyronine was associated with worse all-cause (Likelihood ratio = 45.4; P < 0.0001) and cardiovascular mortality (Likelihood ratio = 47.8; P < 0.0001) after adjustment for confounding factors. CONCLUSION: This study showed that low T3 levels are independent predictors of all-cause and also cardiovascular disease mortality in biochemically euthyroid patients, perhaps due to an intimate association with inflammation. Based on these results, the use of T3 levels in studies assessing the relationship between thyroid dysfunction and mortality risk is recommended.

Plasma pentosidine and total homocysteine levels in relation to change in common carotid intima-media area in the first year of dialysis therapy.

BACKGROUND: Homocysteine and advanced glycation end-products (AGEs), which accumulate in chronic kidney disease (CKD), are recently proposed cardiovascular risk factors. In this study, we evaluated the association between changes in calculated intima media (cIM) area of the common carotid artery during the first year of dialysis therapy and plasma total homocysteine (tHcy) level as well as circulating AGEs such as plasma pentosidine level. METHODS: We studied 63 CKD patients (38 males) aged 52 +/- 12 years at a time-point close to start of dialysis treatment and after 12 months of dialysis treatment (41 on peritoneal and 22 on hemodialysis). The tHcy and plasma pentosidine levels were measured by HPLC. Change in cIM area was evaluated by non-invasive B mode ultrasonography. Malnutrition was assessed by subjective global assessment (SGA). RESULTS: At basal, 70% of the patients had carotid plaques, 32% had symptomatic CVD, 38% had malnutrition, 30% had inflammation (CRP > or = 1 mg/dl) and 23% had diabetes mellitus, respectively. At baseline, the mean plasma pentosidine levels were similar in the patients with and without carotid plaques (36 +/- 21 vs 36 +/- 19 pmol/mg albumin, respectively), whereas the median plasma tHcy was significantly lower in the patients with carotid plaques than in the patients without carotid plaques (32 +/- 21 vs 52 +/- 42 pmol/l, p < 0.01, respectively). The prevalence of hyperhomocysteinemia (tHcy level > 13.7 micromol/l) was 95%. In univariate analysis, the change in cIM area during the first year of dialysis was significantly correlated with basal plasma pentosidine level (p = 0.31, p = 0.01), but not with basal tHcy (p = -0.11). However, neither pentosidine nor tHcy levels were correlated with cIM area at basal or at 12 months. In a stepwise multiple regression model, age and plasma pentosidine content, but not the tHcy level, associated with changes in the cIM area. CONCLUSION: Progression of atherosclerosis, as indicated by changes in carotid intima-media area during the course of dialysis treatment, was associated with pentosidine, but not with tHcy, levels at baseline in these CKD patients. This suggests that the accumulation of AGEs in CKD patients may have a role in the pathogenesis of CVD in these patients. Since almost all CKD patients have hyperhomocysteinemia, this finding, however, does not exclude a role ofhomocysteine as a risk factor for CVD in CKD patients.

Effect of hepatitis C serology on C-reactive protein in a cohort of Brazilian hemodialysis patients.

Hepatitis C (HCV) is not an uncommon feature in hemodialysis (HD) patients and may be a cause of systemic inflammation. Plasma cytokine interleukin-6 (IL-6) is mainly produced by circulating and peripheral cells and induces the hepatic synthesis of C-reactive protein (CRP), which is the main acute phase reactant. The aim of this study was to investigate the influence of HCV on two markers of systemic inflammation, serum CRP and IL-6, in HD patients. The study included 118 HD patients (47% males, age 47 +/- 13 years, 9% diabetics) who had been treated by standard HD for at least 6 months. The patients were divided into two groups depending on the presence (HCV+) or absence (HCV-) of serum antibodies against HCV. Serum albumin (S-Alb), plasma high sensitivity CRP (hsCRP), IL-6, and alanine aminotransferase (ALT) were measured and the values were compared with those for 22 healthy controls. Median hsCRP and IL-6 values and hsCRP/IL-6 ratio were: 3.5 vs 2.1 mg/l, P < 0.05; 4.3 vs 0.9 pg/ml, P < 0.0001, and 0.8 vs 2.7, P < 0.0001, for patients and controls, respectively. Age, gender, S-Alb, IL-6 and hsCRP did not differ between the HCV+ and HCV- patients. However, HCV+ patients had higher ALT (29 +/- 21 vs 21 +/- 25 IU/l) and had been on HD for a longer time (6.1 +/- 3.0 vs 4.0 +/- 2.0 years, P < 0.0001). Moreover, HCV+ patients had a significantly lower median hsCRP/IL-6 ratio (0.7 vs 0.9, P < 0.05) compared to the HCV- group. The lower hsCRP/IL-6 ratio in HCV+ patients than in HCV- patients suggests that hsCRP may be a less useful marker of inflammation in HCV+ patients and that a different cut-off value for hsCRP for this population of patients on HD may be required to define inflammation.

Effect of hepatitis C serology on C-reactive protein in a cohort of Brazilian hemodialysis patients

Hepatitis C (HCV) is not an uncommon feature in hemodialysis (HD) patients and may be a cause of systemic inflammation. Plasma cytokine interleukin-6 (IL-6) is mainly produced by circulating and peripheral cells and induces the hepatic synthesis of C-reactive protein (CRP), which is the main acute phase reactant. The aim of this study was to investigate the influence of HCV on two markers of systemic inflammation, serum CRP and IL-6, in HD patients. The study included 118 HD patients (47 percent males, age 47 ± 13 years, 9 percent diabetics) who had been treated by standard HD for at least 6 months. The patients were divided into two groups depending on the presence (HCV+) or absence (HCV-) of serum antibodies against HCV. Serum albumin (S-Alb), plasma high sensitivity CRP (hsCRP), IL-6, and alanine aminotransferase (ALT) were measured and the values were compared with those for 22 healthy controls. Median hsCRP and IL-6 values and hsCRP/IL-6 ratio were: 3.5 vs 2.1 mg/l, P < 0.05; 4.3 vs 0.9 pg/ml, P < 0.0001, and 0.8 vs 2.7, P < 0.0001, for patients and controls, respectively. Age, gender, S-Alb, IL-6 and hsCRP did not differ between the HCV+ and HCV- patients. However, HCV+ patients had higher ALT (29 ± 21 vs 21 ± 25 IU/l) and had been on HD for a longer time (6.1 ± 3.0 vs 4.0 ± 2.0 years, P < 0.0001). Moreover, HCV+ patients had a significantly lower median hsCRP/IL-6 ratio (0.7 vs 0.9, P < 0.05) compared to the HCV- group. The lower hsCRP/IL-6 ratio in HCV+ patients than in HCV- patients suggests that hsCRP may be a less useful marker of inflammation in HCV+ patients and that a different cut-off value for hsCRP for this population of patients on HD may be required to define inflammation.

Hyperhomocysteinemia in chronic renal failure patients: relation to nutritional status and cardiovascular disease.

A moderate increase in plasma total homocysteine (tHcy) is considered to be an independent risk factor for cardiovascular disease (CVD) in the general population. Almost all chronic renal failure (CRF) patients have plasma concentration of tHcy that is elevated 3 to 4 times above normal. The prevalence of CVD, diabetes mellitus, malnutrition and hypoalbuminemia is high in CRF patients. Previous investigations have focused on the role of vitamin status on plasma tHcy in CRF patients, but little information exists on the influence of nutritional status and hypoalbuminemia on plasma tHcy in CRF, although a substantial fraction of tHcy (>70%) is protein-bound, mainly to albumin. Our study in patients with end-stage renal disease showed that more than 90% of the patients had elevated plasma tHcy levels, which were higher in patients with normal nutritional status than in malnourished patients. Moreover, plasma tHcy was inversely correlated with subjective global nutritional assessment (high values denote malnutrition) and positively correlated with serum albumin and protein intake. Hence, it seems likely that serum-albumin is a strong determinant of plasma tHcy in CRF patients and this may contribute to the lower tHcy levels in malnourished patients. Patients with diabetes mellitus had lower serum-albumin and plasma tHcy than non-diabetic patients, irrespective whether they were malnourished or not. Patients with CVD had lower (although still elevated) plasma tHcy levels than those without CVD. An explanation may be that the prevalence of diabetes mellitus, malnutrition and hypoalbuminema, i.e. factors that decrease tHcy, was higher in patients with CVD, which may explain why they had less elevated values. Assuming that hyperhomocysteinemia carries an independent risk of CVD, this implies that almost all CRF patients are exposed to this risk. CRF patients with CVD had a higher prevalence of malnutrition, hypoalbuminemia and diabetes mellitus, which was associated with a lower plasma Hcy level. This may explain why plasma tHcy was lower (although still abnormally high) in patients with CVD than in patients without CVD. The lower tHcy levels in CVD patients do not contradict the assumption that hyperhomocysteinemia is a risk factor for CVD since almost all patients are exposed to this risk, and other factors might be present that confound the relationship between the absolute tHcy levels and CVD. Our findings imply that nutritional status and serum albumin, as well as the presence of diabetes mellitus, should be taken into consideration when evaluating tHcy as a risk factor for CVD in CRF patients.

Effects of methionine loading on plasma and erythrocyte sulphur amino acids and sulph-hydryls before and after co-factor supplementation in haemodialysis patients.

BACKGROUND: Hyperhomocysteinaemia, which is potentially atherogenic, is common in chronic haemodialysis (HD) patients but the reason for this is not yet known. The methionine (Met) loading test (MLT) is used to test the capacity of homocysteine (Hcy) disposal by the trans-sulphuration pathway and thus may provide information on the metabolism of sulphur amino acids. The availability of vitamin B(6) and folic acid, as co-factors for Hcy metabolism may affect the response to MLT. In the present study, we compared the effect of Met loading on plasma and erythrocyte (RBC) sulphur amino acids and sulph-hydryls before and after co-factor supplementation in healthy subjects and HD patients. METHODS: In 10 HD patients and 10 healthy subjects the effect of Met loading, 0.1 g/kg BW, on plasma and RBC methionine metabolites was studied over 7 h, before and after 4 weeks supplementation with high daily doses of vitamin B(6) (200 mg) and folic acid (15 mg). RESULTS: MLT before vitamin supplementation in HD patients, compared to the healthy subjects, caused significantly greater increases in plasma Hcy levels (43+/-12 vs 15+/-5 micromol/l), cysteinesulphinic acid (CSA) (1.34 vs 0.36 micromol/l) and gamma-glutamylcysteine (0.98+/-0.83 vs -01+/-0.42 micromol/l) and no decline in plasma cysteine (Cys) (0.5+/-33.9 vs -31+/-26 micromol/l), but no significant differences in plasma taurine, cysteinylglycine, and glutathione concentrations. In RBCs there was a small increase in Hcy levels and a more marked increase in Tau levels, with no difference between the healthy subjects and HD patients. Vitamin supplementation in pharmacological doses failed to correct the abnormal responses to MLT in the HD patients. CONCLUSIONS: Oral methionine loading in HD patients leads to higher accumulation of Hcy and other Met metabolites in plasma and RBCs than in healthy subjects, indicating impaired metabolism of sulphur amino acids via the trans-sulphuration pathway. Supplementation with high doses of vitamin B(6) and folic acid does not correct this impairment, suggesting that it most probably is not due to lack of these co-factors.

Hyperhomocysteinemia, nutritional status, and cardiovascular disease in hemodialysis patients.

BACKGROUND: Hyperhomocysteinemia, cardiovascular disease (CVD), and malnutrition are common in patients with end-stage renal disease (ESRD). This study was designed to assess possible relationships between total plasma homocysteine (tHcy), nutritional status, and ischemic CVD. METHODS: We performed a cross-sectional study in 117 unselected patients on maintenance hemodialysis (HD) treatment, among whom there was a high prevalence of malnutrition (56%), as assessed by the subjective global nutritional assessment (SGNA), and a high prevalence of CVD (60%), and prospectively, we followed-up the overall mortality for four years. RESULTS: The level of tHcy was elevated in 95% of the HD patients, and that of total plasma cysteine (tCys) was also significantly elevated, while the plasma concentrations of methionine (Met), serine (Ser), and taurine (Tau) were significantly lower than those in healthy controls. The 65 patients who were malnourished according to the SGNA score had significantly lower levels of serum albumin (SAlb), plasma IFG-1 (p-IGF-1), tHcy, tCys, and Met than the 52 patients with normal nutritional status, whereas the levels of Ser, Tau, plasma folate, and vitamin B12 were similar in the two groups. The prevalence of malnutrition was 30% in the 47 patients without CVD and was significantly higher (70%, P < 0.001) in the 70 patients with CVD, who also had lower tHcy, SAlb, plasma IGF-1, serum creatinine (SCr), and blood hemoglobin. The tHcy levels were positively correlated with SAlb, Met, tCys, and SCr. Stepwise, multiple-regression analysis showed that tCys, SAlb, and normalized protein equivalent of nitrogen appearance (nPNA), an indicator of protein intake, were independent predictors of tHcy. The patients with tHcy <24 micromol/L (median value) had a significantly worse four-year survival than those with a higher tHcy (> or =24 micromol/L). CONCLUSIONS: Our results demonstrate that most of HD patients have grossly elevated tHcy levels, but that the absolute level appears to be dependent on nutritional status, protein intake, and SAlb. The results also suggest that the lower tHcy levels in patients with CVD than in those without CVD may be related to the higher prevalence of malnutrition and hypoalbuminemia in the CVD patients. This is also in accordance with our observation that the patients with lower tHcy had a worse survival rate than those with higher tHcy, considering that malnutrition is a strong risk factor for mortality and that CVD is the most common cause of death in ESRD patients.

Effects of high-dose folic acid and pyridoxine on plasma and erythrocyte sulfur amino acids in hemodialysis patients.

In this investigation, sulfur amino acids (sAA) and sulfhydryls were determined in the plasma and erythrocytes (RBC) of 10 uremic patients on regular hemodialysis (HD) treatment and 10 healthy subjects, before and after supplementation with 15 mg/d of folic acid and 200 mg/d of pyridoxine for 4 wk. The basal total plasma concentrations of homocysteine (Hcy), cysteine (Cys), cysteinylglycine (Cys-Gly), gamma-glutamylcysteine (gamma-Glu-Cys), glutathione (GSH), and free cysteinesulfinic acid (CSA) were significantly higher in HD patients when compared to healthy subjects, whereas methionine (Met) and taurine (Tau) concentrations were the same in the two groups. HD patients showed significantly higher RBC levels of Hcy and Cys-Gly, whereas the RBC concentrations of Met, Cys, Tau, and GSH were not different from those in the healthy subjects. The plasma concentrations of sAA and sulfhydryls differed compared with RBC levels in the healthy subjects and HD patients. In both groups, supplementation with high doses of folic acid and pyridoxine reduced the plasma Hcy concentration. In addition, increased plasma concentrations of Cys-Gly and GSH were found in the HD patients and of CSA in the healthy subjects. After vitamin supplementation, the RBC concentrations of Hcy, Cys, and GSH increased and that of Tau decreased in healthy subjects. The only significant finding in RBC of HD patients was an increase in GSH levels after supplementation. This study shows several RBC and plasma sAA and sulfhydryl abnormalities in HD patients, which confirms earlier findings that RBC and plasma pools play independent roles in interorgan amino acid transport and metabolism. Moreover, high-dose supplementation with folic acid and pyridoxine significantly reduced Hcy levels, but did not restore the sAA and sulfhydryl abnormalities to normal levels. The increase that was observed in GSH after vitamin supplementation may have a beneficial effect in improving blood antioxidant status in uremic patients. Finally, the findings of elevated plasma Cys levels correlating to the elevated plasma Hcy levels in the presence of elevated plasma CSA levels, both before and after vitamin supplementation, led to the hypothesis that a block in decarboxylation of CSA is linked to hyperhomocysteinemia in end-stage renal failure.

IL-8 mRNA expression by in situ hybridisation in human pituitary adenomas.

Several cytokines have been shown to be expressed in normal and adenomatous pituitary tissue. Recently, interleukin-8 (IL-8) mRNA was identified by reverse transcription (RT)-PCR in each of a series of 17 pituitary tumours examined. We have investigated further the presence of IL-8 mRNA, using in situ hybridisation in two normal human anterior pituitary specimens and 25 human pituitary adenomas. IL-8 mRNA was not identified in either of the two normal pituitary specimens. Only three of the 25 adenomas were positive for IL-8 mRNA. In these three tumours, which included two null cell adenomas and one gonadotrophinoma, the majority of tumour cells (>90%) were positive for IL-8 mRNA. The remaining 22 adenomas were completely negative. There was no difference in tumour size or type between the IL-8 positive and the IL-8 negative tumours, and immunocytochemistry for von Willebrandt factor showed that the two groups were also similar in their degree of vascularisation. In conclusion, IL-8 mRNA was found in 12% of pituitary adenomas studied and was histologically identified within the tumour cells. In situ hybridisation is a more appropriate technique for assessing cytokine mRNA production by human pituitary tumours because RT-PCR may be too sensitive, identifying very small, possibly pathologically insignificant, quantities of mRNA that could be produced by supporting cells such as fibroblasts, endothelial cells or macrophages.

Total, free, and protein-bound sulphur amino acids in uraemic patients.

Fasting plasma concentrations of sulphur amino acids (sAA) were measured in nine non-dialysed (ND) chronic uraemic patients on conservative treatment, 10 patients on continuous ambulatory peritoneal dialysis (CAPD), nine patients on haemodialysis (HD) treatment, and 10 healthy subjects (HS). Methionine and taurine concentrations were significantly decreased in the CAPD and HD patients and tended to be low in the ND patients. Cysteine sulphinic acid (CSA) levels were significantly higher in all patient groups. Total (t), free (f), and protein-bound (pb) homocysteine (Hcy) and cysteine (Cys) were significantly increased in all patient groups. Serine, a substrate for cystathionine synthesis from Hcy, showed significantly lower concentrations in all patient groups. The percentages of pbHcy were significantly higher in the CAPD and HD patients than in the ND patients (P < 0.0001, P = 0.002 respectively) or in the HS (P < 0.0001, P = 0.008 respectively), whereas the percentages of pbCys in CAPD and HD patients were significantly higher than in ND patients (P = 0.0006, P = 0.009 respectively) and tended to be high without reaching statistical significance compared to the HS. A single HD treatment decreased tHcy by 26%, fHcy by 39%, and pbHcy by 22%, as well as tCys by 40%, fCys by 54%, and pbCys by 27%. The tHcy concentration, although decreased by HD treatment, remained higher than in HS, whereas tCys was normalized by the dialysis session. In addition, HD treatment significantly decreased the plasma concentrations of methionine, CSA, taurine, and serine. We conclude that, except for methionine and taurine, the plasma sAA in their different forms are markedly increased in dialysed and non-dialysed uraemic patients. The percentages of pbHcy and pbCys were significantly higher in dialysed than in ND uraemic patients. HD treatment can normalize the tCys concentration, and decrease the tHcy concentration but not normalize it. The observed hyperhomocysteineaemia and low taurine levels may contribute to the high incidence of cardiovascular disease in uraemic patients.

Evidence of taurine depletion and accumulation of cysteinesulfinic acid in chronic dialysis patients.

Methionine, taurine and cysteinesulfinic acid (CSA) were determined by reversed-phase high-performance liquid chromatography (RP-HPLC) in plasma from ten patients treated with hemodialysis (HD) and eight patients treated with continuous ambulatory peritoneal dialysis (CAPD). The patients' data were compared with data obtained from ten healthy controls. Significant reductions in plasma taurine levels were observed in the HD patients (34 +/- 13 mumol/liter, mean +/- SD) and the CAPD patients (47 +/- 12 mumol/liter) compared to the controls (66 +/- 5 mumol/liter), while the CSA levels were markedly higher in the HD patients (9.1 +/- 2.8 mumol/liter) and the CAPD patients (9.1 +/- 2.4 mumol/liter) than in the controls (0.79 +/- 0.15 mumol/liter). A single HD treatment significantly reduced the plasma taurine and CSA concentrations (P < 0.01 and P < 0.001), respectively. The plasma methionine levels were normal in both patient groups. The finding of a low plasma taurine level and a large accumulation of CSA suggests that the metabolic conversion of CSA to taurine is impaired in uremic patients and this metabolic abnormality may cause taurine depletion.