Blood ceramides as novel markers for renal impairment in systemic lupus erythematosus.

BACKGROUND: Lupus nephritis (LN) is the most common organ manifestation in systemic lupus erythematosus (SLE) and associated with a poor prognosis. Still, a noninvasive but reliable method to diagnose LN has not been established. Thus, we evaluated whether blood sphingolipids could serve as valid biomarkers for renal injury. METHODS: In this cross-sectional study, 82 participants were divided into three groups: 36 healthy controls and 17 SLE patients without renal injury (both: estimated glomerular filtration rate (eGFR) ≥ 80 ml/min/1.73 m2 and albumin/creatinine ≤ 30 mg/g) and 29  LN patients. LN patients were identified by renal biopsies and impaired renal function (eGFR < 80 ml/min/1.73 m2 and albumin/creatinine ratio > 30 mg/g). Venous blood was collected from all participants and sphingolipid levels in plasma and serum were measured by LC-MS/MS. RESULTS: Most interesting, concentrations of some specific ceramides, C16ceramide (Cer), C18Cer, C20Cer and C24:1Cer, were elevated in both, plasma and serum samples of patients suffering from biopsy-proven LN and impaired renal function, compared to healthy controls as well as SLE patients without renal injury. C24:1dhCer levels were elevated in plasma and serum samples from LN patients compared to SLE patients. Sphingosine levels were higher in plasma and serum of LN patients compared to healthy controls, but not compared to SLE patients. Sphinganine concentrations were significantly elevated in serum samples from LN patients compared to healthy controls and SLE. S1P and SA1P levels were higher in plasma samples of SLE and LN patients compared to healthy controls. Subsequent ROC analyses of plasma and serum data of the most altered ceramide species (C16Cer, C18Cer, C20Cer, C24:1Cer) between LN patients and SLE patients display a high diagnostic differentiation with significant AUCs especially for C24:1Cer serum levels. Further, C24:1Cer serum levels were not affected by glucocorticoid treatment and did not correlate with other renal markers, such as serum creatinine, eGFR and albumin/creatinine ratio. CONCLUSION: Our data reveal that chain-length specific ceramides in blood, most likely C24:1Cer levels in serum, could act as potent biomarkers for renal impairment in patients suffering from SLE.

CTGF Is Expressed During Cystic Remodeling in the PKD/Mhm (cy/+) Rat Model for Autosomal-Dominant Polycystic Kidney Disease (ADPKD).

Connective tissue growth factor (CTGF, also named CCN2) plays an important role in the development of tubulointerstitial fibrosis, which most critically determines the progression to end-stage renal failure in autosomal-dominant polycystic kidney disease (ADPKD), the most common genetically caused renal disease. We determined CTGF expression in a well-characterized animal model of human ADPKD, the PKD/Mhm (cy/+) rat. Kidneys of 12 weeks old (cy/+) as well as (+/+) non-affected rats were analyzed for CTGF RNA and protein expression by RT-PCR, Northern and Western blot analyses, in situ hybridization, and IHC. Besides the established expression of CTGF in glomerular cells in kidneys of wild-type (+/+) animals, in (cy/+) rats, CTGF mRNA and protein were robustly expressed in interstitial, stellate-shaped cells, located in a scattered pattern underlying the cystic epithelium and in focal areas of advanced tubulointerstitial remodeling. Renal CTGF mRNA and protein expression levels were significantly higher in (cy/+) rats compared with their (+/+) littermates. Detection of CTGF expression in cells adjacent to cystic epithelium and in areas of marked fibrosis suggests a role in the local response to cyst development and indicates that CTGF may be a relevant factor contributing to tubulointerstitial fibrosis in polycystic kidney disease.

Kidney Injury Molecule-1 Is Specifically Expressed in Cystically-Transformed Proximal Tubules of the PKD/Mhm (cy/+) Rat Model of Polycystic Kidney Disease.

Expression of kidney injury molecule-1 (Kim-1) is rapidly upregulated following tubular injury, constituting a biomarker for acute kidney damage. We examined the renal localization of Kim-1 expression in PKD/Mhm (polycystic kidney disease, Mannheim) (cy/+) rats (cy: mutated allel, +: wild type allel), an established model for autosomal dominant polycystic kidney disease, with chronic, mainly proximal tubulointerstitial alterations. For immunohistochemistry or Western blot analysis, kidneys of male adult heterozygously-affected (cy/+) and unaffected (+/+) littermates were perfusion-fixed or directly removed. Kim-1 expression was determined using peroxidase- or fluorescence-linked immunohistochemistry (alone or in combination with markers for tubule segments or differentiation). Compared to (+/+), only in (cy/+) kidneys, a chronic expression of Kim-1 could be detected by Western blot analysis, which was histologically confined to an apical cellular localization in areas of cystically-transformed proximal tubules with varying size and morphology, but not in distal tubular segments. Kim-1 was expressed by cystic epithelia exhibiting varying extents of dedifferentiation, as shown by double labeling with aquaporin-1, vimentin or osteopontin, yielding partial cellular coexpression. In this model, in contrast to other known molecules indicating renal injury and/or repair mechanisms, the chronic renal expression of Kim-1 is strictly confined to proximal cysts. Its exact role in interfering with tubulo-interstitial alterations in polycystic kidney disease warrants future investigations.

Short-term preconditioning enhances the therapeutic potential of adipose-derived stromal/stem cell-conditioned medium in cisplatin-induced acute kidney injury.

The development of new strategies to preserve renal function after acute kidney injury (AKI) is necessary due to limited clinical intervention options. The organ-protective effects of mesenchymal stromal/stem cells (MSCs) and their conditioned medium (CM) have been investigated demonstrating that both separately promoted tubular recovery and ameliorated the outcome of AKI. Nevertheless, strategies to optimise the regenerative potential of both are highly needed. Here we investigated the effects of CM from adipose-derived MSCs (ASCs) preincubated in a hypoxic environment (Hyp). Protective factors were investigated by PCR analysis and a protein array in vitro. The expression of 64 of the 308 proteins assayed was found to be more than two-fold increased after Hyp. CM of Hyp-pretreated ASCs (pCM) was used to enhance regeneration in a mouse model of cisplatin-induced AKI (cisAKI). Renal function was assessed by measurements of markers for AKI and serum cytokine levels. The pCM significantly ameliorated serum creatinine and neutrophil gelatinase-associated lipocalin values, and also the levels of inflammatory cytokines IL-1ß and IL-6 in the serum of mice with AKI. Our work clearly showed that a Hyp preconditioning significantly increases the release of protective factors in ASCs and enhances the therapeutic effects of CM in cisAKI in mice.

Secreted frizzled-related protein 4 predicts progression of autosomal dominant polycystic kidney disease.

BACKGROUND: Autosomal dominant polycystic kidney disease (ADPKD) is a common autosomal dominant condition associated with renal cysts and development of renal failure. With the availability of potential therapies, one major obstacle remains the lack of readily available parameters that identify patients at risk for disease progression and/or determine the efficacy of therapeutic interventions within short observation periods. Increased total kidney volume (TKV) correlates with disease progression, but it remains unknown how accurate this parameter can predict disease progression at early stages. METHODS: To identify additional parameters that help to stratify ADPKD patients, we measured secreted frizzled-related protein 4 (sFRP4) serum concentrations at baseline and over the course of 18 months in 429 ADPKD patients. RESULTS: Serum creatinine and sFRP4 as well as TKV increased over time, and were significantly different from baseline values within 1 year. CONCLUSION: Elevated sFRP4 levels at baseline predicted a more rapid decline of renal function at 2, 3 and 5 years suggesting that sFRP4 serum levels may provide additional information to identify ADPKD patients at risk for rapid disease progression.

Combined peri-ischemic administration of Bß15-42 in treating ischemia reperfusion injury of the mouse kidney.

The disruption of endothelial integrity is a crucial step for the development of vascular leakage and consequently ischemia-reperfusion injury (IRI). Regarding the molecular cell-cell interaction, the fibrinopeptide Bß15-42 prevents vascular leakage by stabilizing the inter-endothelial junctions via association with the vascular endothelial-cadherin. In a previous study we showed that a renoprotective effect in early IRI may be achieved by intravenous administration of Bß15-42 at the time of reperfusion. We now aimed to investigate whether additional pre-ischemic application of Bß15-42 could enhance this effect. Therefore C57BL/6 mice were subjected to 0.5h bilateral renal ischemia followed by reperfusion. The animals were randomized into 6 groups (n=6): two control groups treated with i.v. administration of NaCl at reperfusion for 0.5h (NaCl 1h) and 2.5h (NaCl 3h), two groups with Bß15-42 at reperfusion for 0.5h (Bß(rep) 1h) and 2.5h (Bß(rep) 3h), and two groups with administration of Bß15-42 immediately pre-ischemic as well as at reperfusion for 0.5h (Bß(peri) 1h) and 2.5h (Bß(peri) 3h). We found that both Bß(rep) and Bß(peri) mice displayed reduced early renal damage compared with NaCl treated mice. However, there was no further reduction of the IR damage through added pre-ischemic application of Bß15-42. Overall, we detected significantly reduced endothelial activation, lower tissue infiltration of neutrophils as well as lower tissue levels of neutrophil gelatinase-associated lipocalin (NGAL) in all mice treated with Bß15-42 compared to mice treated with NaCl. Our data confirm the renoprotective effect of Bß15-42 in the early therapeutic treatment of acute kidney injury due to ischemia and reperfusion. However, a combined pre-and post-ischemic administration of Bß15-42 appears to provide no additional benefit compared with a sole administration at reperfusion.

Upper and lower urinary tract infections can be detected early but not be discriminated by urinary NGAL in adults.

PURPOSE: We investigated whether the recently established biomarkers of acute kidney injury, neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1), may help to diagnose acute urinary tract infections (UTI) in adults and are able to distinguish between upper or lower localization. METHODS: NGAL levels were measured in blood and urine, and KIM-1 concentrations in urine of 97 subjects. We recruited age- and gender-matched groups of 30 patients with acute upper UTI and 29 patients with acute lower UTI as well as 38 healthy controls. NGAL and KIM-1 were determined by ELISA, serum and urine creatinine applying the Jaffé's method. RESULTS: Urinary NGAL (uNGAL) was significantly increased in patients with upper as well as with lower UTI compared with the healthy controls (P < 0.01; P < 0.05). Accordingly, uNGAL normalized on urinary creatinine (uNGAL/uCrea) was markedly higher in patients with lower UTI compared with the control group (P < 0.05), and uNGAL/uCrea levels were still raised in patients with upper UTI, though not reaching statistical significance (P = 0.07). However, neither uNGAL nor uNGAL/uCrea levels displayed significant differences between patients with upper or lower UTI (P = 0.75; P = 0.97). uKIM-1 levels were close to the detection limit and too low to reliably reveal differences between the three groups. CONCLUSIONS: While uKIM-1 seems not to serve as a helpful biomarker in this setting, increased levels of uNGAL indicate inflammatory processes in the urinary tract in adults. However, the determination of uNGAL levels does not allow to differentiate between upper and lower UTI.

Direct acute tubular damage contributes to Shigatoxin-mediated kidney failure.

The pathogenesis and therapy of Shigatoxin 2 (Stx2)-mediated kidney failure remain controversial. Our aim was to test whether, during an infection with Stx2-producing E. coli (STEC), Stx2 exerts direct effects on renal tubular epithelium and thereby possibly contributes to acute renal failure. Mice represent a suitable model because they, like humans, express the Stx2-receptor Gb3 in the tubular epithelium but, in contrast to humans, not in glomerular endothelia, and are thus free of glomerular thrombotic microangiopathy (TMA). In wild-type mice, Stx2 caused acute tubular dysfunction with consequent electrolyte disturbance, which was most likely the cause of death. Tubule-specific depletion of Gb3 protected the mice from acute renal failure. In vitro, Stx2 induced secretion of proinflammatory cytokines and apoptosis in human tubular epithelial cells, thus implicating a direct effect of Stx2 on the tubular epithelium. To correlate these results to human disease, kidney biopsies and outcome were analysed in patients with Stx2-associated kidney failure (n = 11, aged 22-44 years). The majority of kidney biopsies showed different stages of an ongoing TMA; however, no glomerular complement activation could be demonstrated. All biopsies, including those without TMA, showed severe acute tubular damage. Due to these findings, patients were treated with supportive therapy without complement-inhibiting antibodies (eculizumab) or immunoadsorption. Despite the severity of the initial disease [creatinine 6.34 (1.31-17.60) mg/dl, lactate dehydrogenase 1944 (753-2792) U/l, platelets 33 (19-124)/nl and haemoglobin 6.2 (5.2-7.8) g/dl; median (range)], all patients were discharged after 33 (range 19-43) days with no neurological symptoms and no dialysis requirement [creatinine 1.39 (range 0.84-2.86) mg/dl]. The creatinine decreased further to 0.90 (range 0.66-1.27) mg/dl after 24 months. Based on these data, one may surmise that acute tubular damage represents a separate pathophysiological mechanism, importantly contributing to Stx2-mediated acute kidney failure. Specifically in young adults, an excellent outcome can be achieved by supportive therapy only.

Serum and urinary NGAL but not KIM-1 raises in human postrenal AKI.

BACKGROUND: We examined the value of the novel acute kidney injury (AKI) markers neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) in acute postrenal impairment. These biomarkers have been evaluated in prerenal and intrarenal AKI so far, but not in human acute postrenal kidney injury. With regard to multimorbid and critically ill patients the discrimination of different AKI origins often remains a challenge. As the trend goes towards a diagnostic panel of AKI markers, we hereby aim to contribute to evaluate further options of discrimination in an observational case-control study. MATERIALS AND METHODS: Blood and urine samples were obtained from 53 patients with acute obstructive nephropathy secondary to ureteral calculi and 52 age-matched healthy controls. Serum NGAL (sNGAL), urinary NGAL (uNGAL) and urinary KIM-1 (uKIM-1) levels were determined using a commercially available ELISA kit, creatinine applying the Jaffé's method. RESULTS: While urinary levels of KIM-1 were not significantly different between patients with obstructive nephropathy and controls, a striking increase in sNGAL (P < 0·001) and uNGAL (P < 0·01) levels was detected in the obstructive nephropathy group. Within the obstructive nephropathy group, sNGAL (P = 0·01) and uNGAL (P = 0·049) but not uKIM-1 correlated positively with the white blood cell count and uNGAL correlated positively (P = 0·002) with the extent of leucocyturia. CONCLUSIONS: High levels of sNGAL and uNGAL observed in stone-induced acute obstructive nephropathy may represent a valuable marker of postrenal AKI. Low uKIM-1 levels may help to discriminate postrenal AKI events using a panel of markers in this setting.

The small fibrinopeptide Bß15-42 as renoprotective agent preserving the endothelial and vascular integrity in early ischemia reperfusion injury in the mouse kidney.

Disruption of the renal endothelial integrity is pivotal for the development of a vascular leak, tissue edema and consequently acute kidney injury. Kidney ischemia amplifies endothelial activation and up-regulation of pro-inflammatory mechanisms. After restoring a sufficient blood flow, the kidney is damaged through complex pathomechanisms that are classically referred to as ischemia and reperfusion injury, where the disruption of the inter-endothelial connections seems to be a crucial step in this pathomechanism. Focusing on the molecular cell-cell interaction, the fibrinopeptide Bß15-42 prevents vascular leakage by stabilizing these inter-endothelial junctions. The peptide associates with vascular endothelial-cadherin, thus preventing early kidney dysfunction by preserving blood perfusion efficacy, edema formation and thus organ dysfunction. We intended to demonstrate the early therapeutic benefit of intravenously administered Bß15-42 in a mouse model of renal ischemia and reperfusion. After 30 minutes of ischemia, the fibrinopeptide Bß15-42 was administered intravenously before reperfusion was commenced for 1 and 3 hours. We show that Bß15-42 alleviates early functional and morphological kidney damage as soon as 1 h and 3 h after ischemia and reperfusion. Mice treated with Bß15-42 displayed a significantly reduced loss of VE-cadherin, indicating a conserved endothelial barrier leading to less neutrophil infiltration which in turn resulted in significantly reduced structural renal damage. The significant reduction in tissue and serum neutrophil gelatinase-associated lipocalin levels reinforced our findings. Moreover, renal perfusion analysis by color duplex sonography revealed that Bß15-42 treatment preserved resistive indices and even improved blood velocity. Our data demonstrate the efficacy of early therapeutic intervention using the fibrinopeptide Bß15-42 in the treatment of acute kidney injury resulting from ischemia and reperfusion. In this context Bß15-42 may act as a potent renoprotective agent by preserving the endothelial and vascular integrity.

Current developments in early diagnosis of acute kidney injury.

Acute kidney injury (AKI) is a very frequent and serious clinical problem, accounting for overall high morbidity and mortality. Up to date, mortality due to AKI is virtually unchanged over the past 50 years. This may partly be explained due to a delay in initiating renal protective and appropriate therapeutic measures since until now there are no reliable early-detecting biomarkers. The gold standard, serum creatinine, displays poor specificity and sensitivity with regard to identification of the incipient phase of AKI, and this is also true for cystatin C. We aimed to review novel biomarkers of AKI in urine and serum which have now progressed to the clinical phase. The main focus refers to their diagnostic and prognostic value. For this purpose, a web-based literature search using PubMed was performed comprising the following terms: renal failure, acute kidney injury and biomarkers. New molecules such as neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), N-acetyl-ß-D-glucosaminidase (NAG), monocyte chemotactic peptide (MCP-1), Il-18, liver-type fatty acid-binding protein (L-FABP) and Netrin-1 are available and represent promising new markers that, however, need to be further evaluated in the clinical setting for suitability. In clinical settings with incipient AKI, not only the development and the implementation of more sensitive, practicable and accurate biomarkers are required for well-timed treatment initiation. Just as important is a substantial improvement of refined and applicable prophylactic therapeutic options in these situations. Before full adoption in clinical practice can be accomplished, adequately powered clinical trials testing a row of biomarkers are strongly warranted.

Biomarkers of kidney injury.

CONTEXT: Acute kidney injury (AKI) represents a common serious clinical problem. Up to date mortality due to AKI, especially in intensive care units, has not been changed significantly over the past 50 years. This is partly due to a delay in initiating renal protective and appropriate therapeutic measures since until now there are no reliable early-detecting biomarkers. The gold standard, serum creatinine, displays poor specificity and sensitivity with regard to recognition of the early period of AKI. OBJECTIVE: Our objective was to review established markers versus novel urine and serum biomarkers of AKI in humans, which have progressed to clinical phase with regard to their diagnostic and prognostic value. MATERIALS AND METHODS: A review was performed on the basis of literature search of renal failure, acute kidney injury, and biomarkers in Pubmed. RESULTS: Next to established biomarkers as creatinine and cystatin C, other molecules such as neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), monocyte chemotactic peptide (MCP-1), Netrin-1, and interleukin (IL)-18 are available and represent promising new markers that, however, need to be further evaluated in the clinical setting for suitability. DISCUSSION: In clinical settings with incipient AKI, not only the development and the implementation of more sensitive biomarkers are required for earlier treatment initiation in order to attenuate the severity of kidney injury, but also equally important remains the substantial improvement and application of refined and prophylactic therapeutic options in these situations. CONCLUSION: Adequately powered clinical trials testing a row of biomarkers are warranted before they may qualify for full adoption in clinical practice.

Transitional cell carcinoma of the native urinary tract after kidney transplantation: recommendations following a long-term retrospective analysis.

INTRODUCTION: The aim of the current study was to explore the clinico-oncological characteristics, and the therapeutic and survival parameters, of renal transplant recipients who developed de novo transitional cell carcinoma (TCC) over a 30-year period at the authors' center. METHODS: Retrospective analysis of records from all registered patients who underwent kidney transplantation at the center between November 1979 and January 2010 who developed de novo TCC of the urinary tract. RESULTS: From all 2001 patients analyzed during the study period, 21 recipients developed 19 TCCs of the bladder and 6 TCCs of the upper urinary tract. Among bladder TCCs, 13 (68.4%) cases were confined to mucosa (pTa or carcinoma in situ, n = 7) or submucosa (pT1, n = 6) and 6 others (31.6%) infiltrated the detrusor muscle (≥p T2); the grading distribution was 5 cases of G1, 6 of G2 and 8 of G3. All recurrent cases (n = 8) revealed local or systemic progression. The overall and tumor-specific patient survival rates were 80.2%, 54.0% and 30.0% and 84.9%, 67.4% and 58.9% for 1, 5 and 10 years, respectively. CONCLUSIONS: In the light of the observed increased aggressiveness of TCC in renal transplant recipients, more frequent examinations and possibly more invasive follow-up protocols should be considered for patients with 1 or more risk factors for development of TCC. Urine cytology (including ureteral wash cytology) may be used as a reliable diagnostic tool in these patients. Prophylactic contralateral nephroureterectomy might be an option in patients at high risk.

De novo renal cell carcinoma of native and graft kidneys in renal transplant recipients.

OBJECTIVE: • To access the epidemiological, clinical and survival features of renal transplant patients with de novo renal cell carcinoma of native and graft kidneys. PATIENTS AND METHODS: • We performed a retrospective examination of the data of 2001 consecutive renal transplant recipients at our centre between November 1979 and January 2010. RESULTS: • In the patient cohort examined, 30 renal cell carcinomas were observed in 26 individuals (incidence 1.5%) with 25 tumours in the native and five in allograft kidneys. Mean tumour size in surgical specimens was 44 ± 36 mm. The rate of papillary cancer was 37.5%. • After a mean follow-up of 58.6 ± 62.3 months, 15.4% of the patients died from cancer and 57.7% were in complete remission. • Overall and tumour-specific survival rates at 1, 5 and 10 years were 86.1%, 75.1% and 43.8%, and 90.4%, 83.5% and 66.8%, respectively. CONCLUSIONS: • Due to increasingly improved survival after renal transplantation, de novo malignancies might soon become the main cause of intermediate- or long-term mortality. • Current data support an increased risk of renal cell carcinoma in renal transplant recipients in a particularly aggressive way, but low tendency for metachronous contralateral evolution. • With continuous radiological follow-ups, acceptable oncological outcome can be achieved. Graft tumours may have a favourable prognosis.

Transgenic overexpression of Anks6(p.R823W) causes polycystic kidney disease in rats.

The PKD/Mhm(cy/+) rat is a widely used animal model for the study of human autosomal dominant polycystic kidney disease, one of the most common genetic disorders, affecting one in 1000 individuals. We identified a new gene, Anks6, which is mutated (Anks6((p.R823W))) in PKD/Mhm(cy/+) rats. The evidence for a causal link between Anks6((p.R823W)) and cystogenesis is still lacking, and the function of Anks6 is presently unknown. This study presents a novel transgenic rat model that overexpresses the mutated 2.8-kb Anks6((p.R823W)) cDNA in the renal tubular epithelium. The transgenic Anks6((p.R823W)) acts in a dominant-negative fashion and causes a predictable polycystic phenotype that largely mimics the general characteristics of the PKD/Mhm(cy/+) rats. Cyst development is accompanied by enhanced c-myc expression and continuous proliferation, apoptosis, and de-differentiation of the renal tubular epithelium as well as by a lack of translational up-regulation of p21 during aging. Using Northern blot analysis and in situ hybridization studies, we identified the first 10 days of age as the period during which transgene expression precedes and initiates cystic growth. Thus, we not only provide the first in vivo evidence for a causal link between the novel Anks6((p.R823W)) gene mutation and polycystic kidney disease, but we also developed a new transgenic rat model that will serve as an important resource for further exploration of the still unknown function of Anks6.

Candidate exome capture identifies mutation of SDCCAG8 as the cause of a retinal-renal ciliopathy.

Nephronophthisis-related ciliopathies (NPHP-RC) are recessive disorders that feature dysplasia or degeneration occurring preferentially in the kidney, retina and cerebellum. Here we combined homozygosity mapping with candidate gene analysis by performing 'ciliopathy candidate exome capture' followed by massively parallel sequencing. We identified 12 different truncating mutations of SDCCAG8 (serologically defined colon cancer antigen 8, also known as CCCAP) in 10 families affected by NPHP-RC. We show that SDCCAG8 is localized at both centrioles and interacts directly with OFD1 (oral-facial-digital syndrome 1), which is associated with NPHP-RC. Depletion of sdccag8 causes kidney cysts and a body axis defect in zebrafish and induces cell polarity defects in three-dimensional renal cell cultures. This work identifies loss of SDCCAG8 function as a cause of a retinal-renal ciliopathy and validates exome capture analysis for broadly heterogeneous single-gene disorders.

Development of urological cancers in renal transplant recipients: 30-year experience at the Frankfurt Transplant Center.

Fatal post-transplant malignancies with a high proportion of genitourinary neoplasms represent a serious long-term challenge. With continuous improvement of the allograft and patient survival, cancer development after renal transplantation may soon turn to the leading morbidity cause. In a retrospective single-center study of 1990 renal transplant recipients between November 1979 and November 2009, records of patients with urological neoplasms including epidemiological, clinical and survival parameters were accessed. Sixty-six de novo urological malignancies in 58 recipients were recorded in the study period, being most common after skin cancers (15.6% of enregistered tumors). From these, 29 were renal cell cancers, including five neoplasms of transplanted kidney, 24 transitional cell carcinomas, 11 prostate carcinomas, and two germ cell carcinomas with incidence rates of 1.5%, 1.2%, 0.9% and 0.2%, respectively. The patient follow up was virtually complete. Tumor-related death was found in 44% of cases. By multivariate analysis, no influence of either duration of dialysis, mode or duration of immunosuppression, gender or age at transplantation on overall patient survival could be demonstrated. This study, documenting a 30-year single center experience, emphasizes the increased risk for urological neoplasms occuring after renal transplantation. Screening strategies for urological cancers should be optimized.

Everolimus in patients with autosomal dominant polycystic kidney disease.

BACKGROUND: Autosomal dominant polycystic kidney disease (ADPKD) is a slowly progressive hereditary disorder that usually leads to end-stage renal disease. Although the underlying gene mutations were identified several years ago, efficacious therapy to curtail cyst growth and prevent renal failure is not available. Experimental and observational studies suggest that the mammalian target of rapamycin (mTOR) pathway plays a critical role in cyst growth. METHODS: In this 2-year, double-blind trial, we randomly assigned 433 patients with ADPKD to receive either placebo or the mTOR inhibitor everolimus. The primary outcome was the change in total kidney volume, as measured on magnetic resonance imaging, at 12 and 24 months. RESULTS: Total kidney volume increased between baseline and 1 year by 102 ml in the everolimus group, versus 157 ml in the placebo group (P=0.02) and between baseline and 2 years by 230 ml and 301 ml, respectively (P=0.06). Cyst volume increased by 76 ml in the everolimus group and 98 ml in the placebo group after 1 year (P=0.27) and by 181 ml and 215 ml, respectively, after 2 years (P=0.28). Parenchymal volume increased by 26 ml in the everolimus group and 62 ml in the placebo group after 1 year (P=0.003) and by 56 ml and 93 ml, respectively, after 2 years (P=0.11). The mean decrement in the estimated glomerular filtration rate after 24 months was 8.9 ml per minute per 1.73 m2 of body-surface area in the everolimus group versus 7.7 ml per minute in the placebo group (P=0.15). Drug-specific adverse events were more common in the everolimus group; the rate of infection was similar in the two groups. CONCLUSIONS: Within the 2-year study period,as compared with placebo, everolimus slowed the increase in total kidney volume of patients with ADPKD but did not slow the progression of renal impairment [corrected]. (Funded by Novartis; EudraCT number, 2006-001485-16; ClinicalTrials.gov number, NCT00414440.)

CXCL16 is expressed in podocytes and acts as a scavenger receptor for oxidized low-density lipoprotein.

Podocytes are a crucial cell type in the kidney and play an important role in the pathology of glomerular kidney diseases like membranous nephropathy (MN). The identification of new factors involved in the progression of glomerular kidney diseases is of great importance to the development of new strategies for the treatment of renal injury. Here we demonstrate that CXCL16 and ADAM10 are constitutively expressed in human podocytes in normal renal tissue. Proinflammatory cytokines like interferon-gamma and tumor necrosis factor-alpha induced the expression of cellular CXCL16 and the release of its soluble form from human podocytes. Using different metalloproteinase inhibitors, we provide evidence that ADAM10 is involved in the interferon-gamma- and tumor necrosis factor-alpha-induced shedding of CXCL16 from human podocytes. In addition, ADAM10 knockdown by siRNA significantly increased both CXCL16 levels and, surprisingly, its ADAM17-mediated release. Notably, targeting of CXCL16 in human podocytes both decreased the chemotaxis of CXCR6-expressing T cells and strongly reduced oxidized low-density lipoprotein uptake in human podocytes. Importantly, in kidney biopsies of patients with MN, increased glomerular CXCL16 expression was accompanied by high levels of oxidized low-density lipoprotein and decreased expression of ADAM10. In addition, we found increased glomerular ADAM17 expression in patients diagnosed with MN. In summary, we presume important roles for CXCL16, ADAM10, and ADAM17 in the development of MN, suggesting these proteins as new therapeutic targets in this glomerular kidney disease.

Tumoural CXCL16 expression is a novel prognostic marker of longer survival times in renal cell cancer patients.

The aim of our study was to analyse the expression of CXCL16, ADAM10 and CXCR6 in renal cell carcinoma (RCC) tissue and to correlate the expression pattern with clinicopathologic data, including patient survival. Furthermore, we investigated CXCL16, ADAM10 and CXCR6 expressions by FACS, immunofluorescence and ELISA analysis in renal carcinoma cell lines. Our immunohistochemical analysis on tissue microarray of renal cancer samples of 104 patients revealed that ADAM10 correlated significantly with tumour stage, pathological nodal status, M status and lymphangiosis carcinomatosa. CXCL16, CXCR6 and ADAM10 were significantly increased in papillary carcinomas. Importantly, high levels of CXCL16 expression in renal cancer tissue correlated with better survival of patients, and CXCL16 correlated inversely to the tumour stage. In addition, inhibition of CXCL16 induced the migration of renal cancer cells assuming an anti-migratory function of transmembrane CXCL16. Taken together, our data demonstrate that downregulation of CXCL16 plays an important role in renal cancer development and progression, and that CXCL16 in RCC is an independent prognostic marker for better patient survival.