Nephron Extra最新文献

Background/aims: Gene therapy involves delivery of exogenous DNA to provide a therapeutic protein. Ideally, a gene therapy vector should be non-toxic, non-immunogenic, easy to produce, and efficient in protecting and delivering DNA into target cells.

Methods: Adeno-associated virus (AAV) offers these advantages and few, if any, disadvantages, and over 100 isolates exist. We previously showed that AAV-mediated gene therapy can be used to restore vision to patients with Leber's congenital amaurosis, a disease of childhood blindness.

Results: Here we show that novel recombinant AAV2/8 and AAV2/9 transduce kidney tubule cells with high efficiency both in vitroin cell culture and in vivoin mice. In addition, we adapted and modified a retrograde approach to allow for optimal transgene delivery to renal tubular cells that further minimizes the risk of an immunogenic reaction.

Conclusions: We believe that recombinant AAV2, especially AAV2/8, gene delivery to renal tubule cells via a retrograde approach represents a viable method for gene therapy for a multitude of renal disorders ranging from autosomal dominant polycystic kidney disease to acute kidney injury.

Background/aims: Nephropathic cystinosis (NC) is a severe systemic disease and cysteamine improves its prognosis. Lysosomal cystine accumulation is the hallmark of cystinosis and is regarded as the primary defect due to mutations in the CTNS gene. However, there is great evidence that cystine accumulation itself is not responsible for all abnormalities observed in NC. Studies have demonstrated altered ATP metabolism, increased apoptosis, and cell oxidation. An increased number of autophagosomes and autophagic vacuoles have been observed in cystinotic fibroblasts and renal epithelial cells, suggesting that altered autophagy plays a role in NC, leading to increased production of reactive oxygen species. Therefore, cystinosis patients can be more susceptible to oxidative stress (OS) and it can contribute to the progression of the renal disease. Our goal was to evaluate a marker of OS (serum TBARS) in NC children, and to compare the results with those observed in healthy controls and correlated with renal function parameters.

Methods: The study included patients aged under 18 years, with good adherence to the treatment and out of renal replacement therapy. The following parameters were evaluated: serum creatinine, BUN, creatinine clearance estimated by stature and serum TBARS levels.

Results: We selected 20 patients aged 8.0 ±3.6 years and observed serum TBARS levels of 4.03 ±1.02 nmol/ml. Serum TBARS levels in the 43 healthy controls, aged 7.4 ±1.1 years, were 1.60 ±0.04 nmol/ml. There was a significant difference between the plasma TBARS levels among the 2 groups (p < 0.0001). We detected no significant correlation between plasma TBARS levels and renal function.

Conclusion: An increased level of serum TBARS in patients with NC was observed and this abnormality was not correlated with the renal function status degree. This is the first report that shows increased oxidative stress in serum of NC patients.

Background/aims: We have previously shown that aquaporin-2 (AQP2) is down-regulated in the renal medulla of rats made hypertensive by chronic inhibition of nitric oxide synthase. It has been shown that AQP2 expression is regulated by the calcineurin/nuclear factor of activated T cells (NFATc). Nitric oxide (NO) regulates the activity of NFATc via c-Jun-N-terminal kinase 2 (JNK2). Therefore, we hypothesized that increases in NO enhance NFATc-mediated up-regulation of AQP2 promoter activity.

Methods: AQP2 mRNA and protein expression were detected in mouse renal papilla. AQP2 promoter luciferase reporter- and NFAT luciferase reporter-transfected MDCK cells were used to determine AQP2 promoter activity and NFATc activity, respectively. Cells were incubated with classic activators and inhibitors of NFATc and the NO pathway.

Results: Our results demonstrate that both Ca(2+) and NO have a synergistic effect resulting in an increase in AQP2 mRNA and protein in mouse papilla and activation of the AQP2 promoter in kidney-derived cells. In addition, NO enhances Ca(2+)-induced NFATc activation. The underlying mechanism involves increased NFATc nuclear import and decreased export via protein kinase G-mediated inhibition of JNK1/2.

Conclusions: This is the first study defining novel regulatory roles for NO and NFATc in the control of AQP2, which is an important renal protein.

Background/aims: In view of ongoing controversy, we wished to study whether patient characteristics and/or continuous venovenous hemofiltration (CVVH) characteristics contribute to the outcome of non-septic critically ill patients with acute kidney injury (AKI).

Methods: We retrospectively studied 102 consecutive patients in the intensive care unit (ICU) with non-septic AKI needing CVVH. Patient and CVVH characteristics were evaluated. Primary outcome was mortality up to day 28 after CVVH initiation.

Results: Forty-four patients (43%) died during the 28-day period after the start of CVVH. In univariate analyses, non-survivors had more often a cardiovascular reason for ICU admission, greater disease acuity/severity and organ failure, lower initial creatinine levels, less use of heparin and more use of bicarbonate-based substitution fluid. The latter two can be attributed to high lactate levels and bleeding tendency in non-survivors necessitating withholding lactate-buffered fluid and heparin, respectively, according to our clinical protocol. In multivariate analyses, mortality was predicted by disease severity, use of bicarbonate-based fluids and lack of heparin, while initial creatinine and CVVH dose did not contribute.

Conclusion: The outcome of non-septic AKI in need of CVVH is more likely to be determined by underlying or concurrent, acute and severe disease rather than by CVVH characteristics, including timing and dose.

Background/aims: Decreased thrombopoiesis has been ascribed a role in the pathogenesis of uremic bleeding in chronic renal failure (CRF). However, serum thrombopoietin (TPO) levels are usually elevated in CRF patients, suggesting increased thrombopoiesis. The aim of this study was to determine the thrombopoietic activity in CRF.

Methods: Male Sprague-Dawley rats that underwent 5/6 nephrectomy were used as the model of CRF. Age-matched sham-operated rats were used as controls. Single megakaryocytes were isolated from the rat bone marrow, and their size distribution was examined. Megakaryocyte membrane invaginations were monitored by confocal imaging of di-8-ANEPPS staining, and patch clamp whole-cell recordings of membrane capacitance. TPO gene expression was assessed in various tissues.

Results: Circulating platelet counts and the number of large megakaryocytes were increased in the bone marrow of CRF rats. Massive di-8-ANEPPS staining and increased membrane capacitance in large megakaryocytes demonstrated increased membrane invaginations. Unaffected Kv1.3-channel currents per cell surface area demonstrated unaltered channel densities. TPO transcription was decreased in the renal cortex but increased in the liver and bone marrow of CRF rats.

Conclusion: Increased thrombopoiesis in CRF was thought to be a reactive mechanism to platelet dysfunction. Increased TPO production from the liver and bone marrow compensated for decreased production from damaged kidneys.

Background/aims: Dietary protein deprivation during pregnancy causes hypertension in offspring when they become adults. This study examined if postnatal rearing had an effect on blood pressure and glomerular number in male rats whose mothers were fed either a control diet or a low protein diet.

Methods: Neonates were cross fostered at 1 day of age to a different mother. After birth, all nursing and weaned rats were fed a control diet. Blood pressure and glomerular number were measured in adult offspring.

Results: Control rats cross fostered to another control mother had a lower blood pressure than low protein rats cross fostered to another low protein mother (133 ± 4 vs. 151 ± 4 mm Hg, p < 0.05) and a greater number of glomeruli (28,388 ± 989 vs. 25,045 ± 851, p < 0.05). Fostering pups from the 20% group to mothers that were fed a 6% diet during pregnancy did not cause hypertension or a reduction in the number of glomeruli. However, fostering the 6% group on to mothers that were fed a 20% protein diet during pregnancy resulted in normalization of the blood pressure and number of glomeruli.

Conclusion: The hypertension and reduced glomerular number resulting from prenatal dietary protein deprivation can be normalized by improving the postnatal environment.

The development of well-tolerated and effective therapies that target the pathogenesis of membranous nephropathy (MN) would be useful. Our objective was to evaluate the efficacy of rituximab in MN. We analyzed the outcome of 28 patients treated with rituximab for idiopathic MN. Anti-PLA(2)R antibodies in serum and PLA(2)R antigen in kidney biopsy were assessed in 10 and 9 patients, respectively. Proteinuria was significantly decreased by 56, 62 and 87% at 3, 6 and 12 months, respectively. At 6 months, 2 patients achieved complete remission (CR) and 12 partial remission (PR; overall renal response, 50%). At 12 months (n = 23), CR was achieved in 6 patients and PR in 13 patients (overall renal response, 82.6%). Three patients suffered a relapse of nephrotic proteinuria 27-50 months after treatment. Univariate analysis suggested that the degree of renal failure (MDRD estimated glomerular filtration rate <45/ml/min/1.73 m(2)) is an independent factor that predicts lack of response to rituximab. Anti-PLA(2)R antibodies were detected in the serum of 10 patients, and PLA(2)R antigen in immune deposits in 8 of 9 patients. Antibodies became negative in all 5 responsive patients with available follow-up sera. In this retrospective study, a high rate of remission was achieved 12 months after treatment.

Background/aim: The effect of hypertension on mortality in haemodialysis patients is controversial and can be confounded by non-traditional risk factors like systemic inflammation. This study examined the effect of systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse pressure (PP) on mortality in haemodialysis patients, separately with and without markers of systemic inflammation.

Methods: Data from the United States Renal Data System were analysed for 9,862 patients receiving haemodialysis on December 31, 1993, followed through May 2005.

Results: In Cox regression analysis, increased age, diabetes, low albumin, high white blood count, low cholesterol, low haemoglobin, high phosphate, low DBP, and cardiovascular comorbidity were associated with high mortality, but SBP was not. Elevated PP adjusted for SBP, age, diabetes, haemoglobin, albumin, cholesterol, calcium, phosphate, parathyroid hormone, and white blood count was associated with higher mortality [adjusted hazard ratio, PP 1.006 (95% confidence interval, CI, 1.002-1.010); SBP 0.993 (95% CI 0.990-0.996)]. In dual models, PP adjusted for SBP then DBP was associated with higher mortality [PP 1.029 (95% CI 1.027-1.032); SBP 0.981 (95% CI 0.979-0.983); PP 1.010 (95% CI 1.008-1.011); DBP 0.981 (95% CI 0.979-0.983)]. Increasing PP deciles >70 mm Hg were associated with increasing mortality in the absence of markers of systemic inflammation (white blood count >10 × 10(9)/l, albumin <3.5 g/dl, diabetes), but not in their presence.

Conclusion: PP was a better indicator of adverse outcome than DBP or SBP. Inflammation-associated injury may mask the effect of PP on mortality in haemodialysis patients.

Background: High levels of alkaline phosphatase (ALP) have been associated with increased mortality in patients with advanced chronic kidney disease (CKD). We hypothesize that elevated ALP could be partly explained by subclinical liver congestion related to left ventricular diastolic dysfunction.

Methods: Doppler echocardiography was performed in 68 patients with advanced CKD followed up for a median of 2.1 years. Time-averaged levels of ALP and γ-glutamyl transferase (GGT) were compared between patients with and without diastolic dysfunction. We also evaluated the effect of intensifying diuretic treatment on ALP levels in a small group of 16 patients with high ALP and signs of volume overload.

Results: ALP correlated significantly (p < 0.001) with GGT but not with parathyroid hormone (p = 0.09). Patients with diastolic dysfunction showed higher ALP (p = 0.01), higher GGT (p = 0.03) and lower albumin (p = 0.04). The highest values of ALP were observed in patients with diastolic dysfunction plus pulmonary hypertension (p = 0.01). Intensifying diuretic therapy in a subgroup of patients with signs of fluid overload induced a significant reduction in body weight, GGT (p < 0.001) and ALP levels (p < 0.001).

Conclusions: Elevated ALP in patients with advanced CKD could be partly explained by subclinical liver congestion related to left ventricular diastolic dysfunction, hypervolemia or both. The worse prognosis of these patients could be explained by their myocardial damage.

Background: Chronic kidney disease (CKD) is associated with left-ventricular (LV) diastolic dysfunction (LVDD) which progresses to diastolic heart failure. However, biomarkers predicting LVDD in patients with CKD are largely unknown.

Methods: In 93 patients with non-diabetic CKD, the relationships among echocardiography, high-sensitivity cardiac troponin T (hs-cTnT), B-type natriuretic peptide (BNP), and renal function were evaluated. LV mass index, peak early diastolic mitral filling velocity (E), peak early diastolic mitral annular velocity (E'), and E/E' were recorded.

Results: The E' values were significantly decreased and E/E', BNP, and hs-cTnT increased with increasing CKD stage. The CKD patients with LVDD with E' <5 cm/s had a significantly higher hs-cTnT level as well as a significantly higher BNP level compared to those with E' ≥5 cm/s. The area under the receiver-operating characteristic curve for hs-cTnT and BNP to detect E' <5 cm/s was 0.880 (p = 0.0101) and 0.741 (p = 0.0570), respectively. In multivariate analysis, hs-cTnT and albuminuria were significantly associated with E', and estimated glomerular filtration rate with the hs-cTnT level, after adjusting for age, cause of CKD, and other parameters.

Conclusions: These data suggest that hs-cTnT may be a useful biomarker of LVDD in non- diabetic CKD patients.