Extended-Spectrum Beta-Lactamase–Producing Enterobacteriaceae–Related Urinary Tract Infection in Kidney Transplant Recipients: Risk Factors,Treatment, and Long-Term Outcome

Background

Prevalence of extended-spectrum beta-lactamase–producing Enterobacteriaceae (ESBL-E) has risen in kidney transplant (KT) patients, with no long-term data so far on graft function or survival.

Urinary Tract Infections in the First Year Post–Kidney Transplantation: Potential Benefits of Treating Asymptomatic Bacteriuria

Background

Urinary tract infections (UTIs) are the commonest infectious complication in kidney transplant recipients (KTRs). No recommendations exist regarding treatment of asymptomatic bacteriuria. We aimed to identify potential risk factors and microbiological profile for UTIs, the role of treatment of asymptomatic bacteriuria, and effects on graft outcomes of bacteriuria within the first year post-transplantation.

Clinical Pictures and Novel Mutations of WT1-Associated Denys–Drash Syndrome in Two Chinese Children

Denys–Drash syndrome (DDS) is characterized by early onset of nephropathy, genitalia malformation, and Wilms’ tumor, where WT1 is the gene that is mutated in most patients. We report two de novo mutations in WT1 found in two Chinese DDS children. Patient 1 was a boy with complete DDS who was presented with progressive nephropathy, unilateral Wilms’ tumor, bilateral cryptorchidism, and renal histology showing diffuse mesangial sclerosis (DMS). When the patient was 24 months old, a liver ultrasound showed multiple nodules, and the patient died of pneumonia 1 month later. The de novo novel mutation, c.1130A>T (p.His377Leu), was identified; the mutation replaces histidine with leucine in the zinc finger (Znf) structure and is predicted to change the local spatial structure of the protein. Patient 2 had 46 XX with incomplete DDS and presented with normal genitalia, proteinuria, unilateral Wilms’ tumor with renal pedicle lymph node metastasis, and renal histology showing DMS. Her renal function remains normal after 48 months. A de novo mutation, c.1168C>T (p.Arg390Term), was identified; it truncates 60 amino acids at the C terminus, and it is predicted to result in loss of the DNA-binding capacities of the WT1 protein.     

Comparison of RIFLE and AKIN Criteria in the Evaluation of the Frequency of Acute Kidney Injury in Post–Liver Transplantation Patients

BackgroundAcute renal dysfunction is presented quite often after orthotopic liver transplantation (LT), with a reported incidence of 12–64%. The “RIFLE” criteria were introduced in 2004 for the definition of acute kidney injury (AKI) in critically ill patients, and a revised definition was proposed in 2007 by the Acute Kidney Injury Network (AKIN), introducing the AKIN criteria. The aim of this study was to record the incidence of AKI in patients after LT by both classifications and to evaluate their prognostic value on mortality.MethodsWe retrospectively evaluated the records of patients with LT over 2 years (2011–2012) and recorded the incidence of AKI as defined by the RIFLE and AKIN criteria. Preoperative and admission severity of disease scores, duration of mechanical ventilation, intensive care unit length of stay, and 30- and 180-day survivals were also recorded.ResultsSeventy-one patients were included, with an average age of 51.78 ± 10.3 years. The incidence of AKI according to the RIFLE criteria was 39.43% (Risk, 12.7%; Injury, 12.7%; Failure, 14.1%), whereas according to the AKIN criteria it was 52.1% (stage I, 22.5%; stage II, 7%; stage II 22.55%). AKI, regardless of the classification used, was related to the Model for End-Stage Liver Disease score, the volume of transfusions, the duration of mechanical ventilation, and survival. The presence of AKI was related to higher mortality, which rose proportionally with the severity of AKI as defined by the stages of either the RIFLE or the AKIN criteria.ConclusionsAKI classifications according to the RIFLE and AKIN criteria are useful tools in the recognition and classification of the severity of renal dysfunction in patients after LT, because they are associated with higher mortality, which rises proportionally with the severity of renal disease.     

Role of Urinary Neutrophil Gelatinase–Associated Lipocalin for Predicting the Severity of Renal Functions in Patients With Autosomal-Dominant Polycystic Kidney Disease

Background

Autosomal-dominant polycystic kidney disease (ADPKD) has a feature of disruption of tubular integrity with increased cellular proliferation and apoptosis. There are several known tubular membrane proteins in the pathogenesis of ADPKD, and one of these proteins is the neutrophil gelatinase-associated lipocalin (NGAL). NGAL is a protein expressed on renal tubular cells of which production is markedly increased in response to harmful stimuli such as ischemia or toxicity.

The Prognostic Value of E-Cadherin, α-, β-, and γ-Catenin in Urothelial Cancer of the Upper Urinary Tract

Objectives

To determine the value of loss of the expression of E-cadherin and cadherin-associated molecules as useful markers for both prognosis and bladder recurrence in patients with upper urinary tract cancer.

Materials and methods

In 61 paraffin-embedded nephroureterectomy specimens, the expression of E-cadherin and α-, β-, and γ-catenin was examined by immunohistochemical staining. To evaluate the prognostic significance, Kaplan-Meier survival curves were calculated and compared by the log-rank test. A multivariate test was performed to detect prognostic markers.

Results

Normal expression was found in 32 cases (52.5%) for E-cadherin, 41 cases (67.2%) for α-catenin, 42 cases (68.9%) for β-catenin, and 31 cases (50.8%) for γ-catenin. The expression patterns of E-cadherin and α-, β- and γ-catenin were significantly correlated with each other. Survival analysis showed a significant difference between normal and aberrant expression in each staining. Multivariate analysis revealed that tumor stage and the expression of E-cadherin were independent prognostic factors for cause-specific survival. In contrast, there was no significant correlation between the expression of E-cadherin and α-, β-, and γ-catenin and bladder recurrence.

Conclusion

Our data suggest E-cadherin may be a good prognostic marker for patients with upper urinary tract cancer.     

Altered Phenotype of β-Cells and Other Pancreatic Cell Lineages in Patients With Diffuse Congenital Hyperinsulinism in Infancy Caused by Mutations in the ATP-Sensitive K-Channel

Diffuse congenital hyperinsulinism in infancy (CHI-D) arises from mutations inactivating the K_ATP channel; however, the phenotype is difficult to explain from electrophysiology alone. Here we studied wider abnormalities in the β-cell and other pancreatic lineages. Islets were disorganized in CHI-D compared with controls. PAX4 and ARX expression was decreased. A tendency toward increased NKX2.2 expression was consistent with its detection in two-thirds of CHI-D δ-cell nuclei, similar to the fetal pancreas, and implied immature δ-cell function. CHI-D δ-cells also comprised 10% of cells displaying nucleomegaly. In CHI-D, increased proliferation was most elevated in duct (5- to 11-fold) and acinar (7- to 47-fold) lineages. Increased β-cell proliferation observed in some cases was offset by an increase in apoptosis; this is in keeping with no difference in INSULIN expression or surface area stained for insulin between CHI-D and control pancreas. However, nuclear localization of CDK6 and P27 was markedly enhanced in CHI-D β-cells compared with cytoplasmic localization in control cells. These combined data support normal β-cell mass in CHI-D, but with G₁/S molecules positioned in favor of cell cycle progression. New molecular abnormalities in δ-cells and marked proliferative increases in other pancreatic lineages indicate CHI-D is not solely a β-cell disorder.     

Predictive Value of the Combination of Peripheral Blood Lymphocyte Count and Urinary Cytology in BK Polyomavirus–associated Nephropathy

BackgroundGraft biopsy is the gold standard for diagnosis of BK polyomavirus–associated nephropathy (BKPyVAN), and polymerase chain reaction is the most specific screening technique. Development of a noninvasive, cost-effective marker for BKPyVAN is important.MethodsWe reviewed 492 adult kidney transplant patients. We investigated peripheral blood lymphocyte (PBL) count and urinary cytology at graft biopsy in patients with BKVPyAN (n = 21), acute T-cell–mediated rejection (n = 79), and no evidence of acute rejection (n = 149). We performed univariate and multivariate logistic regression and receiver operating characteristics analyses to compare the test performance of PBL count, urinary cytology, and their combination for diagnosis of BKPyVAN.ResultsThe PBL count at biopsy was significantly lower in the BKPyVAN group than the acute T-cell–mediated rejection and no acute rejection groups (959 ± 290/μL, 1433 ± 673/μL, and 1531 ± 549/μL, respectively; P < .01). The PBL count was 959 ± 290/μL at diagnosis of BKPyVAN and increased to 1123 ± 377/μL, 1238 ± 419/μL, and 1292 ± 491/μL at 1, 2, and 3 months after treatment, respectively (P < .05). On univariate analysis, the area under the curve was significantly higher for the combined model than for PBL and cytology alone (0.930, 0.797, and 0.875, respectively; P < .01). The improved test performance in the combined model remained significant after multivariate adjustment (0.972, 0.844, and 0.928, respectively; P < .01).ConclusionsDecreased PBL count was found in BKPyVAN, and the predictive performance of the combination of PBL count and urinary cytology was significantly enhanced for diagnosis of BKPyVAN.     

Bacillus Calmette-Guérin Failure in Patients with Non–Muscle-invasive Urothelial Carcinoma of the Bladder May Be Due to the Urologist's Failure to Detect Urothelial Carcinoma of the Upper Urinary Tract and Urethra

BackgroundVarious reasons exist for so-called bacillus Calmette-Guérin (BCG) failure in patients with non–muscle-invasive urothelial bladder carcinoma (NMIBC).ObjectiveTo explore whether urothelial carcinoma of the upper urinary tract (UUT) and/or prostatic urethra may be a cause for BCG failure.Design, setting, and participantsRetrospective analysis of 110 patients with high-risk NMIBC repeatedly treated with intravesical BCG, diagnosed with disease recurrence, and followed for a median time of 9.1 yr.InterventionTwo or more intravesical BCG induction courses without maintenance.Outcome measurements and statistical analysisPrimary outcome was pattern of disease recurrence (BCG failure) within the urinary tract categorised into UUT and/or urethral carcinoma (with or without intravesical recurrence), and intravesical recurrence alone. Secondary outcome was survival. Predictors of UUT and/or urethral carcinoma and the effect of pattern of disease recurrence on cancer-specific survival were assessed with multivariable Cox regression analysis adjusting for multiple clinical and tumour characteristics.Results and limitationsOf the 110 patients, 57 (52%) had UUT and/or urethral carcinoma (with or without intravesical recurrence), and 53 (48%) had intravesical recurrence alone. In patients with UUT and/or urethral carcinoma, bladder carcinoma in situ (Tis) before the first and second BCG course was present in 42 of 57 (74%) and 47 of 57 (82%) patients, respectively. On multivariable analysis, bladder Tis before the first and/or second BCG course was the only independent predictor of UUT and/or urethral carcinoma. Of the 110 patients, 69 (63%) were alive at last follow-up visit, 18 (16%) had died due to metastatic urothelial carcinoma, and 23 (21%) had died of other causes. Pattern of disease recurrence within the urinary tract was not an independent predictor of cancer-specific survival. Main study limitations were retrospective design and limited power for survival analysis.ConclusionsIn our patients with high-risk NMIBC failing after two or more courses of intravesical BCG, UUT and/or urethral carcinoma was detected in >50% of the cases during follow-up. The vast majority of these patients had bladder Tis before the first and/or second BCG course. In patients experiencing the so-called BCG failure, a diagnostic work-up of UUT and prostatic urethra should always be performed to exclude urothelial carcinoma before additional intravesical therapy or even a radical cystectomy is considered.     

A Protein Kinase A–Independent Pathway Controlling Aquaporin 2 Trafficking as a Possible Cause for the Syndrome of Inappropriate Antidiuresis Associated with Polycystic Kidney Disease 1 Haploinsufficiency

Renal water reabsorption is controlled by arginine vasopressin (AVP), which binds to V2 receptors, resulting in protein kinase A (PKA) activation, phosphorylation of aquaporin 2 (AQP2) at serine 256, and translocation of AQP2 to the plasma membrane. However, AVP also causes dephosphorylation of AQP2 at S261. Recent studies showed that cyclin-dependent kinases (cdks) can phosphorylate AQP2 peptides at S261 in vitro. We investigated the possible role of cdks in the phosphorylation of AQP2 and identified a new PKA-independent pathway regulating AQP2 trafficking. In ex vivo kidney slices and MDCK-AQP2 cells, R-roscovitine, a specific inhibitor of cdks, increased pS256 levels and decreased pS261 levels. The changes in AQP2 phosphorylation status were paralleled by increases in cell surface expression of AQP2 and osmotic water permeability in the absence of forskolin stimulation. R-Roscovitine did not alter cAMP-dependent PKA activity but specifically reduced protein phosphatase 2A (PP2A) expression and activity in MDCK cells. Notably, we found reduced PP2A expression and activity and reduced pS261 levels in Pkd1^+/− mice displaying a syndrome of inappropriate antidiuresis with high levels of pS256, despite unchanged AVP and cAMP. Similar to previous findings in Pkd1^+/− mice, R-roscovitine treatment caused a significant decrease in intracellular calcium in MDCK cells. Our data indicate that reduced activity of PP2A, secondary to reduced intracellular Ca²⁺ levels, promotes AQP2 trafficking independent of the AVP–PKA axis. This pathway may be relevant for explaining pathologic states characterized by inappropriate AVP secretion and positive water balance.In most mammals, regulation of water balance is critically dependent on water intake and excretion, which is under control of the antidiuretic hormone arginine vasopressin (AVP). In the kidney, AVP binds to the V2 vasopressin (V2R) receptor, activating the cAMP/protein kinase A (PKA) signal transduction cascade, promoting the fusion of intracellular vesicles containing aquaporin 2 (AQP2) to the apical plasma membrane, and increasing luminal permeability.^1–3 This translocation is accompanied by AVP-dependent phosphorylation of AQP2 at serine-256 (pS256).Mice in which S256 could not be phosphorylated (AQP2-S256L) develop polyuria and hydronephrosis because of a defect in AQP2 trafficking to the plasma membrane.⁴ Interestingly, it connects to polycystic kidney disease (PKD). Mutations in polycystin-1 (Pkd1^+/−) gene cause PKD, whereas PKD1 haplo-insufficient mice (Pkd1^+/−), showing an inappropriate antidiuresis, display significantly higher levels of pS256 compared with wild-type (WT) littermates; the prominent expression at the apical plasma membrane of collecting duct principal cells, despite normal V2R expression and normal cAMP levels, is associated with unchanged AVP expression in the brain, despite chronic hypo-osmolality.⁵These observations underscore the crucial role of AQP2 phosphorylation at S256 in controlling the cellular distribution and fate of AQP2.^1,6,7 As for many proteins, the function and the trafficking of AQP2 are modulated by a balance of reversible phosphorylation and dephosphorylation. Preventing dephosphorylation of AQP2 with okadaic acid, inhibitor of phosphatase 1 (PP1), inhibitor of phosphatase 2A (PP2A), and inhibitor of phosphatase 2B (PP2B) significantly increased AQP2-pS256.⁸ Proteomic analysis of inner medulla collecting duct identified PP2A as a phosphoprotein isolated from inner medullary collecting duct samples treated with either calyculin-A, a specific PP2A inhibitor, or vasopressin,⁹ suggesting the possible participation of this phosphatase in cellular events triggered by physiologic stimulus, such as vasopressin in renal collecting duct cells.The complexity of AQP2 regulation was further increased by phosphoproteomics studies showing that, other than S256, vasopressin modulates the phosphorylation status of three other sites within the C terminus (S261, S264, and S269). Although vasopressin increases S264 and S269 phosphorylation, it decreases S261 phosphorylation.^9–12 Regarding the potential kinases responsible for the phosphorylation of these sites, c-Jun N-terminal kinase, p38, and cyclin-dependent kinases (cdks) cdk1 and cdk5 can phosphorylate AQP2 peptides at S261 in vitro.^13,14 Here, in the attempt to investigate the potential involvement of cdks in AQP2 regulation, we discovered a new PKA-independent signal transduction pathway regulating AQP2 phosphorylation and localization. We found that selective inhibition of cdks with R-roscovitine is associated with a decrease of intracellular Ca²⁺ levels and a significant downregulation of the phosphatase PP2A activity, resulting in an increase of AQP2 phosphorylation at S256 and targeting to the apical membrane. Physiologically, this novel regulatory mechanism might be of clinical interest, because it better elucidates the molecular bases of pathologic states characterized by disturbances in water balance.     

Tailored Eculizumab Therapy in the Management of Complement Factor H–Mediated Atypical Hemolytic Uremic Syndrome in an Adult Kidney Transplant Recipient: A Case Report

Atypical hemolytic uremic syndrome (aHUS) is characterized by thrombocytopenia, microangiopathic hemolytic anemia, and acute kidney injury (AKI) which frequently progresses to end-stage renal disease (ESRD). In 50% of affected patients, mutations in complement regulatory proteins cause inappropriate complement activation with endothelial injury. Complement factor H (CFH) mutations cause 25% of aHUS cases; these patients have an 80% recurrence risk after kidney transplantation. Eculizumab, an anti-C5 antibody, is effective in limiting hemolysis episodes in patients with aHUS, but less is known about preventing recurrence after kidney transplantation. Herein we report the use of prophylactic eculizumab in an adult with aHUS who underwent kidney transplantation. A 31-year-old female presented with aHUS and progressive AKI associated with low complement 3 level leading to ESRD despite plasmapheresis and corticosteroids. She had a heterozygous nonsense mutation in CFH and reduced plasma CFH levels. She was given preoperative plasmapheresis and eculizumab and underwent living unrelated renal transplantation. Postoperatively, eculizumab was dosed to achieve low functional complement 5 levels and low soluble membrane attack complex levels and she has maintained excellent graft function without aHUS recurrence. We propose that eculizumab with titrated dosing should be used in CFH-mediated aHUS patients who are at a high risk of recurrence.     

Translation,Cultural Adaptation and Validation of the Kidney Disease Quality of Life–Short Form 1.3 in an African Country

Background

The impact of dialysis on patient quality of life has been recognized as an important outcome measure. The Dialysis Outcomes and Practice Patterns Study compared quality of life in 4 continents [1], but very scarce information is available about dialysis patients' quality of life in Africa. The objective of this study was to translate the Kidney Disease Quality of Life–Short Form (KDQOL-SF) into Moroccan and measure its psychometric properties.

Methods

The questionnaire was first translated into Moroccan by 2 independent translators, and then 2 backward translations into English were performed after pretesting in 10 dialysis patients. The final questionnaire was then administered to 80 dialysis patients. Reliability was estimated by internal consistency and test–retest reliability. Validity was assessed using known group comparisons and correlations between overall health rating and scales scores.

Results

Some activities were substituted since they were not common in Morocco. All subscales had a Cronbach α above the recommended value except for 3 scales. All of the items showed good test–retest reliability. Correlation of items within subscales was higher than that of items outside subscales in 87% of cases. Regarding construct validity, all KDQOL-SF scales had significant correlation with overall health rating except for sexual function and dialysis staff encouragement. Furthermore, the questionnaire could be used to discriminate between subgroups of the patients.

Conclusions

The psychometric properties of the KDQOL-SF resulting from this first-time administration of the instrument support the validity and reliability of the KDQOL-SF as a measure of quality of life of patients having hemodialysis in Morocco.     

Catalase Overexpression Prevents Nuclear Factor Erythroid 2–Related Factor 2 Stimulation of Renal Angiotensinogen Gene Expression,Hypertension, and Kidney Injury in Diabetic Mice

This study investigated the impact of catalase (Cat) overexpression in renal proximal tubule cells (RPTCs) on nuclear factor erythroid 2–related factor 2 (Nrf2) stimulation of angiotensinogen (Agt) gene expression and the development of hypertension and renal injury in diabetic Akita transgenic mice. Additionally, adult male mice were treated with the Nrf2 activator oltipraz with or without the inhibitor trigonelline. Rat RPTCs, stably transfected with plasmid containing either rat Agt or Nrf2 gene promoter, were also studied. Cat overexpression normalized systolic BP, attenuated renal injury, and inhibited RPTC Nrf2, Agt, and heme oxygenase-1 (HO-1) gene expression in Akita Cat transgenic mice compared with Akita mice. In vitro, high glucose level, hydrogen peroxide, and oltipraz stimulated Nrf2 and Agt gene expression; these changes were blocked by trigonelline, small interfering RNAs of Nrf2, antioxidants, or pharmacological inhibitors of nuclear factor-κB and p38 mitogen-activated protein kinase. The deletion of Nrf2-responsive elements in the rat Agt gene promoter abolished the stimulatory effect of oltipraz. Oltipraz administration also augmented Agt, HO-1, and Nrf2 gene expression in mouse RPTCs and was reversed by trigonelline. These data identify a novel mechanism, Nrf2-mediated stimulation of intrarenal Agt gene expression and activation of the renin-angiotensin system, by which hyperglycemia induces hypertension and renal injury in diabetic mice.