Plasma osteoprotegerin, arterial stiffness, and mortality in normoalbuminemic Japanese hemodialysis patients.

UNLABELLED: A high circulating osteoprotegerin (OPG) level may be a risk factor for vascular calcification and mortality in hemodialysis patients. OPG and pulse wave velocity (PWV) were measured at baseline in 151 normoalbuminemic, long-term (>3 years) Japanese hemodialysis patients who were prospectively followed for 6 years. In long-term normoalbuminemic Japanese hemodialysis patients, OPG levels were strongly linked with both arterial stiffness and worse outcome. INTRODUCTION: A high circulating OPG level is reported to be a risk factor for vascular calcification and mortality in Western chronic kidney disease (CKD) patients but it is not known if this is true for Japanese CKD patients, where a different risk profile may operate. METHODS: OPG and PWV were measured at baseline in 151 normoalbuminemic, long-term (>3 years) Japanese hemodialysis patients (median age 62 years) who were prospectively followed for 6 years. RESULTS: OPG levels were associated in multivariate analysis with age, dialysis vintage, history of cardiovascular disease (CVD) and parathyroid hormone levels. C-reactive protein levels did not correlate with OPG. Patients with clinical history of CVD had significantly higher OPG levels and OPG levels were positively correlated to PWV, an index of arterial stiffness. These associations were independent of age, sex, dialysis vintage, and diabetes. During the follow-up period, 40 deaths, including 25 cardiovascular deaths, were recorded. In crude analysis, each unit of increase in OPG was associated with increased all-cause (hazard ratios 1.14, 95% confidence interval 1.08-1.20) and CVD mortality (1.14 [1.07-1.21]), which persisted after adjustment for age, sex, dialysis vintage, diabetes, and baseline CVD (1.12 [1.05-1.19] and 1.11 [1.02-1.19], all-cause and CVD mortality, respectively). CONCLUSIONS: In long-term normoalbuminemic Japanese hemodialysis patients, with low prevalence of inflammation, OPG levels were strongly linked with both arterial stiffness and worse outcome.

Endogenous estrogen may prevent bone loss in postmenopausal hemodialysis patients throughout life.

SUMMARY: Postmenopausal hemodialysis patients are at risk of complications related to renal mineral and bone disorder, and postmenopausal osteoporosis. In 112 postmenopausal hemodialysis patients, free estrogen index was positively correlated with bone mineral density (BMD) Z-score and the annual percent change of BMD in multiple regression analysis. Endogenous estrogen may prevent bone loss in postmenopausal hemodialysis patients throughout life. INTRODUCTION: Women on dialysis are not only at risk of developing mineral and bone disorder, but also suffer from postmenopausal osteoporosis. We assessed the effect of sex hormones on bone metabolism in postmenopausal hemodialysis patients. METHODS: We enrolled 112 postmenopausal hemodialysis patients with a mean age of 68.4 ± 10.4 years. We measured the serum levels of estradiol, testosterone, sex hormone-binding globulin (SHBG), and intact parathyroid hormone (intact-PTH), as well as bone metabolism parameters and radial bone mineral density (BMD). The free estrogen index (FEI) was calculated from the estradiol and SHBG values. After conventional dialysis was performed for 12 months, BMD was measured again and the annual percent change was calculated. Estradiol and SHBG were also measured in 25 postmenopausal women without chronic kidney disease. RESULTS: Estradiol levels were higher in the hemodialysis patients than in the postmenopausal women without chronic kidney disease. In patients with relatively normal bone turnover (intact-PTH: from 150 to 300 pg/ml), the FEI showed a positive correlation with the BMD Z-score. The annual percent change of BMD showed a positive correlation with the FEI according to multiple regression analysis. CONCLUSIONS: Endogenous estrogen may prevent bone loss in postmenopausal hemodialysis patients throughout life.

Renal histology before and after effective enzyme replacement therapy in a patient with classical Fabry's disease.

A 38-year-old man underwent renal biopsy because of proteinuria. It revealed swelling and vacuolation of glomerular epithelial cells, as well as myelin-like structures characteristic of Fabry's disease. Detection of decreased plasma activity of alpha-galactosidase A confirmed the diagnosis. Enzyme replacement therapy was provided with recombinant agalsidase-beta, resulting in improvement of his symptoms. When renal biopsy was repeated, specific staining for globotriaosylceramide showed that renal deposits were decreased by enzyme therapy.

Oral mizoribine pulse therapy for steroid-dependent focal segmental glomerulosclerosis.

A 24-year-old woman with focal segmental glomerulosclerosis was referred to our hospital for treatment of nephrotic syndrome. Though she experienced partial remission following treatment with prednisone and cyclosporine, she had a relapse of nephrotic syndrome when her prednisone was tapered off to 30 mg/day. The prednisone could not be tapered to less than 30 mg/day due to repeated relapses. After introduction of oral mizoribine (MZR) pulse therapy, the patient's prednisone was tapered to 15 mg/day and she had no signs of relapse for more than 1 year. This case suggests that oral MZR pulse therapy is a good therapeutic option for patients with steroid-dependent nephrotic syndrome.

Beneficial effect of low-density lipoprotein apheresis (LDL-A) on refractory nephrotic syndrome (NS) due to focal glomerulosclerosis (FGS).

AIMS: Hypercholesterolemia is one of the factors which deteriorate renal function in NS especially due to FGS. LDL-A is a potential option for treating NS due to FGS accompanied by hypercholesterolemia and resistant to conventional drug therapy with steroids and/or cyclosporine A (CsA). As reported by Muso et al. [2001], LDL-A combined with drug therapy yields more rapid relief from NS and better prognosis than drug therapy alone. However, very limited data are available on outcome at several years after treatment. The aim of this study was to clarify long-term outcome of NS patients treated with LDL-A and to evaluate the effectiveness of this treatment. PATIENTS AND METHODS: To clarify the long-term outcome of LDL-A, we conducted a retrospective survey on outcome up to 5 years. From 36 hospitals in Japan, 41 patients with NS whose short-term outcomes with LDL-A were reported from 1999-2004 were collected and analyzed. RESULTS: In all, 29 and 15 patients with outcomes determined at 2 and 5 years after treatment, respectively, were obtained. At 2 and 5 years after treatment, 62 and 87% of patients, respectively, were classified into complete or Type 1 incomplete remission. The strength of correlations between outcome and several factors including parameters of renal function measured before and after treatment and treatment condition revealed that early administration of LDL-A after the onset of NS provided a good long-term outcome. The data also suggest that more drastic decrease of LDL favored a better prognosis. CONCLUSIONS: In NS due to FGS treated with LDL-A, long-term outcome was as good as short-term outcome. Early administration of LDL-A after the onset of NS provided a good long-term outcome. To obtain more precise findings regarding the effects of this treatment, a large-scale prospective study will be needed.

PDGF receptor tyrosine kinase inhibitor suppresses mesangial cell proliferation involving STAT3 activation.

Proliferation of mesangial cells is a hallmark of glomerular disease, and understanding the regulatory mechanisms is critically important. The purpose of this study was to examine the relationship between mesangial cell proliferation and phosphorylated signal transducer and activator of transcription (STAT) 3 and to determine whether the PDGF receptor tyrosine kinase inhibitor STI 571 inhibited mesangial cell proliferation via modulation of STAT3. In this study, we investigated for the first time, the glomerular expression of phosphorylated STAT3 in paraffin sections from animals with experimental mesangial proliferative glomeronephritis. Phosphorylated STAT3 colocalized with many proliferating mesangial cells. We also demonstrated that treatment with STI 571 reduced mesangial cell proliferation and phosphorylated STAT3 signalling both in vitro and in vivo. In vivo, STI 571 treatment reduced the number of glomerular mesangial cells positive for both phosphorylated STAT3 and proliferating cell nuclear antigen. In summary, phosphorylated STAT3 is strongly expressed during mesangial cell proliferation and STI 571 induced suppression of mesangial cell proliferation involves inhibition of phosphorylated STAT3 signalling.

Osteoprotegerin and bone mineral density in hemodialysis patients.

INTRODUCTION: Osteoprotegerin is a soluble glycoprotein that belongs to the tumor-necrosis-factor receptor superfamily. In vitro, osteoprotegerin blocks osteoclastogenesis in a dose-dependent manner. The serum osteoprotegerin level shows a positive correlation with bone metabolism markers and a negative correlation with bone mineral density in healthy persons, but these relationships are unclear in hemodialysis patients. We investigated the role of osteoprotegerin in bone loss in hemodialysis patients. METHODS: We measured baseline serum osteoprotegerin, bone metabolism markers, and bone mineral density in hemodialysis patients. A total of 201 patients (114 men and 87 women) were followed for 12 months, and bone mineral density was measured again to calculate the annual percent change in bone mineral density. Serum osteoprotegerin was also measured in 20 healthy persons. RESULTS: The osteoprotegerin levels of the hemodialysis patients were about three times higher than those of the healthy controls. The osteoprotegerin level showed a negative correlation with various bone metabolism markers. In multiple regression analysis, the annual percent change in bone mineral density showed a positive correlation with osteoprotegerin level, while there was a negative correlation with duration of hemodialysis and intact parathyroid hormone level. The osteoprotegerin levels of the hemodialysis patients were about three times higher than those of the healthy controls. The osteoprotegerin level showed a negative correlation with various bone metabolism markers. In multiple regression analysis, the annual percent change in bone mineral density showed a positive correlation with osteoprotegerin level, while there was a negative correlation with duration of hemodialysis and intact parathyroid hormone level. CONCLUSIONS: These correlations of osteoprotegerin are opposite to those found in healthy persons. However, osteoprotegerin might act to prevent bone loss even in hemodialysis patients.

HMG-CoA reductase inhibitors prevent bone loss in patients with Type 2 diabetes mellitus.

AIMS: It has been reported that 3-hydroxy-3-methylglutaryl co-enzyme A (HMG-CoA) reductase inhibitors increase bone mineral density (BMD) in vivo. We investigated the effect of HMG-CoA reductase inhibitors on BMD in patients with Type 2 diabetes mellitus. PATIENTS AND METHODS: We selected 122 patients with Type 2 diabetes, who were not taking active vitamin D preparations. Their mean age was 67.3 +/- 9.2 years. They were divided into a control group (n=63) without HMG-CoA reductase inhibitor therapy and an HMG-CoA group (n=59) who were treated with these drugs. The BMD of the distal one-third of the radius was measured by dual-energy X-ray adsorptiometry at baseline and after 2 years. RESULTS: There were no significant differences between the control and HMG-CoA groups at baseline with respect to age, gender, body mass index, duration of diabetes, haemoglobin A1c, fasting plasma glucose, adjusted calcium, serum phosphorus, alkaline phosphatase, albumin excretion rate and radial BMD. However, there was a significantly smaller annual decrease of the radial BMD in the HMG-CoA group. Multiple regression analysis with a forward elimination procedure revealed a positive correlation of the radial BMD Z-score with body mass index, while there was a negative correlation with alkaline phosphatase and albumin excretion rate. In addition, the annual rate of change of the radial BMD showed a positive correlation with HMG-CoA reductase inhibitor therapy. CONCLUSIONS: These findings suggest that HMG-CoA reductase inhibitors may prevent bone loss in patients with Type 2 diabetes.

Radial bone mineral density in hemodialysis patients with adynamic bone disease.

Adynamic bone disease (ABD) has attracted attention as the most frequent type of renal osteodystrophy, but there are few reports about the bone mineral density (BMD) in ABD patients. This study investigated the BMD in hemodialysis patients with ABD and with relatively normal bone turnover. We measured the BMD of the distal one-third of the radius by dual-energy X-ray adsorptiometry. In the ABD group (intact PTH<65 pg/ml, intact osteocalcin<30 ng/ml), there were 19 men and 17 women with a mean age of 56.4 +/- 12.0 years. In the relatively normal bone turnover group (intact PTH: 120-250 pg/ml), there were 24 men and 16 women with a mean age of 57.1 +/- 14.7 years. Although there were no significant differences between the two groups with respect to age, gender, and duration of hemodialysis, a significant increase of the BMD and the calcium x phosphate product was observed in the ABD group (radial BMD: 0.648 +/- 0.137 g/cm2 versus 0.572 +/- 0.132 g/cm2, calcium x phosphate product: 57.53 +/- 14.92 mg2/dl2 versus 49.76 +/- 12.13 mg2/dl2). These findings suggest that an increase in radial BMD may not be a useful marker of the improvement in bone lesions in ABD patients.

Reiter's syndrome associated with HLA-B51: a case report.

A 32-year-old Japanese man developed polyarthritis with mild fever and conjunctivitis. Clinical assessment indicated non-specific arthritis, aseptic pyuria induced by infection with Chlamydia, and conjunctivitis. He was diagnosed with reactive arthritis (Reiter's syndrome). Serotyping of human leucocyte antigen (HLA) class I and II revealed positivity for B51(5), A2, A33(19), B44(12), Cw1, DR4 and DR6, but B27 was negative. He was treated with a combination of doxycycline, oral prednisolone, diclofenac sodium and salazosulphapyridine. Fever and arthralgia improved and he became negative for anti-Chlamydia immunoglobulin (Ig) A and IgG antibodies. HLA-B51 may be involved in the pathogenesis of Reiter's syndrome in this Japanese patient.

Dose-dependent effect of an oral adsorbent, AST-120, in patients with early chronic renal failure.

We evaluated the dose dependence of an oral adsorbent, AST-120, in 31 patients with early chronic renal failure (baseline serum creatinine: 1.2-3.0 mg/dl). Twenty-three patients were given AST-120 and eight patients were not. AST-120 was administered at three different maintenance doses, < 3.0 g, 3.0 g and 6.0 g/day, according to patients' ability to tolerate treatment. The treatment period was 12 months. The slope of the reciprocal of serum-creatinine concentration versus time was calculated to assess the progression of renal failure. This slope became significantly less steep after AST-120 treatment at 6.0 g/day, but did not change significantly at the other doses. These findings suggest that 6.0 g/day of AST-120 may delay the initiation of dialysis in patients with early chronic renal failure.

Endothelial nitric oxide synthase intron 4 polymorphism influences the progression of renal disease.

BACKGROUND/AIM: Nitric oxide is a potent regulator of intrarenal hemodynamics and may influence the renal function. We investigated whether polymorphism of intron 4 of the endothelial constitutive nitric oxide synthase (ecNOS) gene is related to the progression of chronic renal failure. METHODS: Polymorphism of ecNOS intron 4 was studied in 1,005 hemodialysis patients (710 with nondiabetic nephropathy and 295 with diabetic nephropathy) and was compared with the findings in 189 healthy subjects. ecNOS genotypes were determined by the polymerase chain reaction, followed by agarose gel electrophoresis. RESULTS: The frequencies of ecNOS4a/a, ecNOS4a/b, and ecNOS4b/b genotypes were, respectively, 0% (0/189), 13.8% (26/189), and 86.2% (163/189) in the control group; 1.7% (12/710), 22.1% (157/710), and 76.2% (541/710) in the nondiabetic nephropathy group, and 1.0% (3/295), 22.7% (67/295), and 76.3% (225/295) in the diabetic nephropathy group. The frequency of ecNOS4a (ecNOSa/a and ecNOSa/b) was significantly higher in both the nondiabetic group and in the diabetic group than in the controls (p = 0.0025 and p = 0.0438, respectively). CONCLUSION: There was a significantly higher frequency of the a allele of intron 4 in both nondiabetic and diabetic hemodialysis patients, so the polymorphism of intron 4 of the ecNOS gene may have a wide influence on the progression of renal disease.

Hexamethylene bisacetamide protects peritoneal mesothelial cells from glucose.

BACKGROUND: Peritoneal dialysis causes damage to peritoneal mesothelial cells primarily because dialysis fluids have a high glucose concentration. This study examined the abnormalities of gap junctional intercellular communication (GJIC) in human peritoneal mesothelial cells (HPMCs) exposed to relatively high levels of glucose. Also, ability of hexamethylene bisacetamide (HMBA) to up-regulate GJIC in HPMCs exposed to high levels of glucose was measured. METHODS: An assay that monitors the recovery of fluorescence after photobleaching was used to measure GJIC in primary cultured HPMCs. The cells were exposed to a low (10 mmol/L) or high (50 or 90 mmol/L) glucose level for a total of six days, and some cells were also incubated with or without HMBA (1 or 6 mmol/L) from day 4. The effects of incubation in these various environments on expression of the connexin 43 (Cx43) gene were investigated by the reverse transcription-polymerase chain reaction (to detect Cx43 mRNA) or by immunofluorescence and Western blotting (to detect Cx43 protein). To evaluate the influence of protein kinase C (PKC) or mitogen-activated protein kinase (MAPK) on GJIC, specific inhibitors were added to cultures in a high glucose medium. RESULTS: Gap junctional intercellular communication was inhibited in a concentration- and time-dependent manner when cells were exposed to high glucose. The addition of 6 mmol/L HMBA to cultures significantly enhanced GJIC despite the presence of a high glucose concentration. High glucose also down-regulated Cx43 mRNA and protein expression, with the dose-dependent decrease of Cx43 protein at gap junctions paralleled by a decrease in the phosphorylation of this protein. As expected, treatment of cells with 6 mmol/L HMBA increased both Cx43 mRNA and protein levels despite exposure to high glucose. The addition of PKC or MAPK inhibitors to high glucose cultures did not restore GJIC, and there was no significant change of Cx43 phosphorylation in the presence of these inhibitors. CONCLUSIONS: High glucose down-regulates GJIC in human peritoneal mesothelial cells. It also decreases the levels of both Cx43 mRNA and Cx43 protein, with the latter becoming hypophosphorylated. HMBA appears to reverse all of these changes. These results are consistent with our hypothesis that HMBA protects HPMCs from the adverse effects of high glucose by reversing various processes that would otherwise lead to harmful loss of GJIC.

Effect of prednisolone on increased expression of laminin by human peritoneal mesothelial cells cultured with high glucose.

This study aimed to clarify the role of laminin (a component of the extracellular matrix) in the mechanism of peritoneal fibrosis in continuous ambulatory peritoneal dialysis (CAPD) patients, and the effect of prednisolone on such fibrosis. We used semiquantitative reverse-transcriptase polymerase chain reaction (RT-PCR) and ELISA to study laminin mRNA expression and laminin protein production by human peritoneal mesothelial cells (HPMCs) cultured under various conditions. After 6 hours, medium 199 with a high glucose content (4.0%) increased laminin mRNA expression by 1.38-fold relative to control medium (0.1% glucose). Prednisolone (1 mumol/L) suppressed this increase by 92.9%. The laminin protein level in culture supernatant was increased 1.83-fold after incubation for 24 hours in high-glucose medium. Prednisolone (1 mumol/L) suppressed this increase by 58.3%. The effects of prednisolone were prevented by a glucocorticoid receptor antagonist (RU486) at 100 mumol/L. We conclude that culture of HPMCs in high-glucose medium increases laminin mRNA and protein expression, while prednisolone suppresses these changes via the glucocorticoid receptor, suggesting that prednisolone may prevent peritoneal fibrosis in CAPD patients.

Mechanism of increased serum soluble interleukin-2 receptor levels in patients on continuous ambulatory peritoneal dialysis.

OBJECTIVE: The aim of this study was to investigate the mechanism underlying the increase of serum soluble interleukin-2 receptor (IL-2R) levels in patients on continuous ambulatory peritoneal dialysis. MATERIAL AND METHODS: In 13 dialysis patients and 17 healthy controls, serum soluble IL-2R levels were determined by enzyme-linked immunosorbent assay, and CD25-positive (cell surface IL-2R-positive) cells were detected by flow cytometry. Soluble IL-2R levels were also measured in the supernatant of cultured peripheral blood mononuclear cells. RESULTS: The serum soluble IL-2R level was significantly higher in the patients than in the healthy controls (p < 0.0001). In contrast, both the percentage and the absolute count of CD25-positive cells showed no significant differences, and neither did the soluble IL-2R level in culture supernatant. Serum soluble IL-2R levels showed a positive correlation with the serum beta2-microglobulin level (p < 0.01), the age of the patients (p < 0.05), and duration of dialysis (p < 0.05), as well as a negative correlation with the urine volume (p < 0.05). CONCLUSIONS: The increase of serum soluble IL-2R in patients on peritoneal dialysis may be caused by accumulation due to its low transperitoneal clearance and low urinary excretion.

Serum cystatin C may predict the prognostic stages of patients with IgA nephropathy prior to renal biopsy.

The relationship between the levels of serum cystatin C and the prognostic stages of IgA nephropathy was determined in a multicenter trial in Japan. The levels of serum cystatin C in patients with IgA nephropathy were measured using the Dade Behring N Latex Cystain C assay. In 1995, the Joint Committee of the Special Study Group on Progressive Glomerular Diseases, Ministry of Health and Welfare of Japan, and the Japanese Society of Nephropathy reported four prognostic stages. These are: good prognosis group (Group I), relatively good prognosis group (Group II), relatively poor prognosis group (Group III), and poor prognosis group (Group IV), for this disease. Three-hundred and six patients with IgA nephropathy and other glomerular diseases were examined. There were no significant changes in the levels of serum creatinine (Cr) or creatinine clearance (CCr) between Group I and Group II. The mean levels of serum cystatin C in Group II were significantly higher than those in Group I (P < 0.05). The mean levels of serum cystatin C in Group III or IV were significantly higher than those in Group I (P < 0.001, P < 0.005, respectively). These suggest that the measurement of serum cystatin C may predict the prognostic stages of patients with IgA nephropathy prior to renal biopsy.

Measurement of serum IgA and C3 may predict the diagnosis of patients with IgA nephropathy prior to renal biopsy.

The levels of serum IgA and C3 in patients with IgA nephropathy were determined using international standard serum (IFCC/CRM470) in a multicenter trial in Japan. The ratio of serum IgA to C3 (serum IgA/C3 ratio) without any information from renal biopsy was used for the diagnosis of IgA nephropathy. Three hundred and six patients with IgA nephropathy and other glomerular diseases, and 418 healthy adults were examined. The new diagnostic standardized criterion in patients with IgA nephropathy, obtained by nephelometric immune assay based on the international reference preparation CRM470, was 315 mg/dl. The serum IgA/C3 ratio was a more useful marker for distinguishing IgA nephropathy from non-IgA nephropathy together with serum IgA levels. This suggests that the measurement of serum IgA and C3 may predict the diagnosis of patients with IgA nephropathy prior to renal biopsy.