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In order to present an antigen to T-cells, the antigen must first be degraded by proteasomes. Following exposure to interferons, some proteasome subunits (ss1,ss2,ss5) are replaced by others (LMP2, LMP7, MECL-1) that have more optimal catalytic properties for peptide presentation; this more efficient organelle is termed the immuno-proteasome. Here we measured gene expression of various subunits in peripheral mononuclear cells of patients with IgA nephropathy, a disease with features of immune dysregulation. We used quantitative PCR to measure the expression of proteasomal subunit mRNA in mononuclear cells from IgA nephropathy patients, a group of proteinuric control patients with idiopathic nephrotic syndromes, and healthy controls. A significant switch in the expression of trypsin- and chymotrypsin-like proteasome subunits to corresponding immuno-proteasome subunits was found in patients as compared to healthy controls. Further, we found that nuclear translocation of NF-kappaB p50 and p65 was significantly greater in the IgA nephropathy patients, but this did not correlate with the switch to the immuno-proteasome phenotype. Patients with proteinuria greater than 0.5 g/1.73 m(2)/day had a significant switch of the chymotryptic-like beta5 protease to the LMP7 subunit, but this did not occur in patients with idiopathic nephrotic syndrome. The switch to an immuno-proteasome in peripheral blood mononuclear cells of patients with IgA nephropathy suggests an increased efficiency of antigen processing and presentation. This switch appears to be independent of a coincidental activation of the NF-kappaB pathway but is associated with high levels of proteinuria, a well known risk factor for progression of IgA nephropathy.

While sirolimus (SRL) is thought to be a non-nephrotoxic agent, cyclosporine A (CsA) toxicity is a serious problem in kidney transplantation. We compared the effects of the two drugs on T-helper (Th) subsets in kidney transplant patients. We examined 24 first cadaver kidney recipients equally randomized to receive SRL/mycophenolate mofetil (MMF)/methylprednisolone (MP), or cyclosporine with either MMF or MP. The Th1 and Th2 subsets in peripheral blood were separated based on their production of interferon-gamma (INFgamma) or interleukin (IL)-4/IL-5. The lymphocytes were stimulated with phytohemoagglutinin or with allogenic CD3-depeted and irradiated antigen-presenting cells. Furthermore, the conversion potential of Th0 to Th1 was determined by measuring IL-12 and IL-18 levels after lipopolysaccharide challenge. When peripheral blood lymphocytes taken from SRL-treated patients were stimulated by phytohemoagglutinin, there were significantly lower INFgamma-producing cells compared with the lymphocytes taken from patients treated with CsA. The number of IL-4/IL-5-producing cells did not differ among the patient groups. Release of IL-12 but not IL-18 from peripheral lymphocytes following treatment with lipopolysaccharide was significantly lower in the SRL-treated patients. These results show that compared with CsA, SRL caused a significant decrease in the Th1 lymphocyte subset associated with a significant reduction of IL-12 release.

Functional versus structural changes in the pathophysiology of acute ischemic renal failure in aging rats. The aim of the study was to gain further insight into the greater susceptibility to acute ischemic renal failure (ARF, 30min of renal arteries clamping) of old rats (O, 18 months) as against young rats (Y, 3 months). All the rats ate a hypoproteic diet (14% of casein) to avoid age-related glomerulosclerosis in O. Basal renal dynamics was similar in O and Y (Groups CON). One day after ARF, the decrease in GFR was more severe in O than in Y (-82% and -57% vs. respective CON, P

Role of inhibition of atrial natriuretic factor release in the down-regulation of salt excretion. We investigated the role of atrial natriuretic factor (ANF) in the down-regulation of sodium excretion (U Na V). Seven subjects were sequentially studied while injesting a normal-salt diet (220mmol NaCl/day, NSD), a very low-salt diet (20mmol NaCl/day, VLSD) for six days, and again at NSD for nine days. After one day of VLSD, a negative salt balance of 85mmol was achieved and plasma ANF decreased from 19.1 (SE 2.5) to 7.2 (SE 2.1) pg/ml, whereas plasma renin activity (PRA) and plasma aldosterone (ALD) increased after the third and second day, respectively. During restoration of volemia (NSD), ANF increased after the third day; in contrast, PRA and ALD decreased earlier. Seven other subjects kept at low-salt diet (50mmol NaCl/day) were studied during ANF infusion (at 2, 4, 8 ng/min/kg body wt). Increases of ANF from 10.3 (SE 0.9) pg/ml (basal condition) to levels of 24.0 (SE 1.9) pg/ml (infusion study), occurring physiologically in the same subjects after NSD, evoked increases in U Na V that accounted for 62% of U Na V rise necessary to balance the NSD, whereas PRA or ALD did not change. Plasma ANF, unlike PRA or ALD, was directly correlated with U Na V. In conclusion: (a) ANF changes earlier than PRA and plasma aldosterone during VLSD; (b) PRA and ALD respond more promptly than ANF in the recovery from hypovolemia; (c) during ingestion of a low-salt diet, changes in plasma ANF by infusion account for more than half the increase in U Na V following the shift from low- to normal-salt diet independently of alterations in PRA and ALD.

Vitamin E–loaded dialyzer resets PBMC-operated cytokine network in dialysis patients.BackgroundIn hemodialysis patients the activity of stimulated Th1 lymphocytes is depressed, while Th2 cells are constitutively primed. Such phenomena may depend on monocyte activation and altered release of interleukin (IL)-12 and IL-18, which regulate Th cell differentiation. Reactive oxygen species (ROS) activate monocytes; therefore, a hemodialyzer with antioxidant activity would contrast ROS, prevent monocyte activation, reset IL-12 and IL-18 release, and restore Th1/Th2 balance.MethodsTen patients on regular dialysis treatment (RDT) with cellulosic membrane (CM) were shifted to vitamin E–coated dialyzer (VE). During treatment with CM and after 3, 6, and 12months of treatment with VE, peripheral blood mononuclear cells (PBMC) and purified CD4+ cells were isolated, and cultured, resting, mitogen-stimulated, and interferon γ (IFNγ), IL-4, IL-10, IL-12, and IL-18 release was measured. Vitamin E and A plasma levels and the effects of a single dialysis session on peripheral blood NO levels were assayed.ResultsThe constitutive release of IL-4 and IL-10 by CD4+ cells was abated significantly by treatment with VE (nadir -77.8% and -55.3%, respectively, at 12months). INFγ release by mitogen-stimulated CD4+ recovered with VE (zenith +501% at 12months). PBMC constitutive production of IL-12 and IL-18 was significantly reduced by VE (nadir at 12months -64.7% and -51.3%, respectively). VE increased plasma levels of vitamins E and A. NO plasma levels fell after a single dialysis treatment with VE (-17%, P < 0.05) in contrast with CU (+27.1%, P < 0.05).ConclusionThe network of cytokines released by monocytes and Th cells is reset toward normality by treatment with vitamin E–coated dialyzer.

To the Editor: The risk for vascular disease is much higher in hemodialysis patients than in the general population [1]. Sex, hypertension, diabetes mellitus, being overweight, hyperlipidemia, hyperhomocysteinemia, and smoking are well-established risk factors of cardiovascular disease [2–3]. This study was undertaken to define the influence of sex on the prevalence of conventional risk factors in 54 long-term hemodialysis patients: 24 female, 30 male (mean age in years, 60 12 female and 65 15 male; mean dialytic age in months, 59 48 female and 61 55 male). All patients received thrice-weekly dialysis and ratio of urea clearance times dialysis duration to the volume that the urea is distributed in (Kt/v) was always 1.2. No patients at the time of the study were receiving folate or vitamin B supplements. Total homocysteine (Hcy) was tested by a standard highperformance liquid chromatography (HPLC) assay and the following biochemical parameters were also tested: albumin (g/L), cholesterol (mg/dL), and triglycerides (mg/dL). Male hemodialysis patients showed significantly higher Hcy levels when compared to female hemodialysis patients (66.8 49.1 vs. 40.6 21.7, P 0.02). Mean plasma—cholesterol (200 40 males vs. 201 46 females); triglycerides (204 126 males vs. 163 64 females); and albumin (20.0 40.3 males vs. 20.1 46.2 females) did not show any statistical difference. The prevalence of hypertension defined as blood pressure 140/80 mm Hg and smoking was similar between the two groups (76% males vs. 69% females). To our knowledge, this is the first observation of a significant difference between male and female serum Hcy levels. This finding may account for the different cardiovascular risk between the 2 populations of HD patients. Therapeutic approaches aimed to treat hyperhomocysteinemia should take into account different cut-off points according to gender.

Mesangial expression of intercellular adhesion molecule-1 in primary glomerulosclerosis. Frozen sections of renal biopsy specimens from eight patients with primary focal segmental glomerulosclerosis (FSGS) and 10 patients with membranous nephropathy (MN) were stained in immuno-peroxidase with the intercellular adhesion molecule-1 (ICAM-1) monoclonal antibody (MoAb), CL203.4. ICAM-1 was expressed by mesangial cells in six patients with FSGS. On the other hand, ICAM-1 was not detected in mesangial cells in patients with MN or in the non-affected portion of tumoral kidneys used to control normal renal expression of ICAM-1. De novo mesangial expression of ICAM-1 in FSGS suggests that sclerosis results from an inflammatory process, possibly associated with local release of cytokines.

A 16-year-old boy with known chronic renal failure was admitted because of seizures and confusion. Serum biochemistry showed sodium 109 mmol/l, potassium 4.9 mmol/l, calcium 9.5 mg/dl, glucose 80 mg/dl, and stable renal function with creatinine 2.8 mg/dl. After 72 hours of intravenous therapy, the serum sodium had increased to 130 mmol/l and the patient showed a progressive improvement of the neurological symptoms. Magnetic resonance imaging (MRI) was not performed at this time in order to avoid gadolinium nephrotoxicity in a patient with already reduced renal function. Ten days later, when the boy's serum sodium was normal but the seizures and confusion appeared again, an axial T2-weighted MRI (Figure 1b) showed bilateral high-intensity abnormalities localized in the lenticular nuclei and in the head of the caudate nucleus. At day 32, when the neurological syndrome progressed to quadriparesis, respiratory failure, and coma, these lesions appeared more pronounced (Figure 1c); and with fluid-attenuation inversion recovery, high-intensity lesions were observed in the precentral gyrus (Figure 1d). At day 60 spontaneous fistulization of an aberrant right subclavian artery with intratracheal rupture resulted in hemorrhagic shock and death. The patient had also had a normal MRI scan taken five months before the episode of severe hyponatremia, when his serum sodium was 140 mmol/l; this study was done after the patient's sister was diagnosed with hypopituitarism. Central myelinolysis after correction of severe hyponatremia is rare in childhood.

Mycophenolate mofetil is an immunosuppressive agent that blocks purine biosynthesis, inhibits T and B-lymphocyte and mesangial proliferation. Mycophenolate mofetil is not nephrotoxic like calcineurin inhibitors and is widely used in solid-organ transplantation. Recently, mycophenolate mofetil has been introduced in the treatment of autoimmune diseases and primary glomerulopathies. This review analyzes the literature currently available on the treatment of primary glomerulopathies with mycophenolate mofetil. Encouraging results have been obtained in minimal change nephropathy where it may help to reduce the use of steroids in these patients who are often very young. The results obtained in medium and high risk patients with focal segmental glomerulonephritis and idiopathic membranous nephropathy were less encouraging. Conflicting results have been reported on IgA nephropathy in controlled trials. None of these studies attained level A evidence, meaning that randomized control trials of sufficient statistical significance are necessary to estimate the real effectiveness of mycophenolate mofetil in primary glomerulopathies.

To the Editor: Hydrogen sulfide, H2S, the third endogenous gas with cardiovascular properties after nitric oxide and carbon monoxide, is a newly recognized vasorelaxant, and H2S deficiency is involved in the pathogenesis of hypertension and atherosclerosis.1 We demonstrated that in hemodialysis patients, H2S levels are decreased through transcriptional deregulation of genes encoding H2S-producing enzymes.2 In fact, gene expression of cystathionine γ-lyase (CSE), an enzyme implicated in H2S formation, is downregulated in these patients.2 We measured H2S levels before and after a single standard 4-h hemodialysis session in 131 patients, in two dialysis sessions separated by 1 month. Measurement was performed by a slight modification of our previously published method.2 Basically, a 20-min incubation period was added before deproteinization. Homocysteine is a main direct H2S precursor in vivo, which functions through the catalytic activity of either cystathionine β-synthase or CSE (see Perna et al.3 for a review). Plasma total homocysteine was also measured by using high-performance liquid chromatography separation and fluorescence detection.4

To the Editor: Homocysteine has an inhibitory effect on angiogenesis1. However, the vascular endothelial growth factor receptor-2 (VEGFR-2) gene has recently been found up-regulated on human atherosclerotic plaques2. In order to analyze the association between homocysteine and VEGFR-2 serum levels, we have randomly selected 26 regular hemodialysis (HD) patients ages 56 12 years (mean SD; M = 14, F = 12), and 26 age-matched kidney transplanted individuals (KTx), ages 52 8 years (M = 21, F = 5). KTx transplant age was 13 9 months and creatinine was 1.6 0.5 mg/dL. Nine age-matched healthy volunteers (47 5 years) were also recruited. HD samples were collected at the end of the long interval period. Serum homocysteine (Hcy) and VEGFR-2 were tested by high-performance liquid chromatography (HPLC) with fluorimetric detection and a commercial enzyme-linked immunosorbent assay (ELISA) kit, respectively. Hcy was higher in HD patients (57 36 mol/L) than in KTx patients (23 8 mol/L; P < 0.001) and control patients (15 6 mol/L; P < 0.01 vs. HD; P < 0.05 vs. KTx). VEGFR-2 was lower in HD patients (1705 387 pg/mL) than in KTx patients (2449 825 pg/mL; P = 0.014) or control patients (2150 464 pg/mL) Figure 1. The present study shows that Hcy and circulating VEGFR-2 are inversely associated, consistent with previous reports showing that homocysteine inhibits angiogenesis. Our data also suggest that up-regulation of the VEGFR-2 gene is probably a local finding, and that hyperhomocysteinemia may be involved in the release of VEGFR-2 into the systemic circulation.