The Swiss Kidney Stone Cohort: A Longitudinal, Multicentric, Observational Cohort to Study Course and Causes of Kidney Stone Disease in Switzerland.

BACKGROUND: Kidney stone disease has a high prevalence worldwide of approximately 10% of the population and is characterized by a high recurrence rate. Kidney stone disease results from a combination of genetic, environmental, and lifestyle risk factors, and the dissection of these factors is complex. METHODS: The Swiss Kidney Stone Cohort (SKSC) is an investigator-initiated prospective, multicentric longitudinal, observational study in patients with kidney stones followed with regular visits over a period of 3 years after inclusion. Ongoing follow-ups by biannual telephone interviews will provide long-term outcome data. SKSC comprises 782 adult patients (age >18 years) with either recurrent stones or a single stone event with at least one risk factor for recurrence. In addition, a control cohort of 207 individuals without kidney stone history and absence of kidney stones on a low-dose CT scan at enrolment has also been recruited. SKSC includes extensive collections of clinical data, biochemical data in blood and 24-h urine samples, and genetic data. Biosamples are stored at a dedicated biobank. Information on diet and dietary habits was collected through food frequency questionnaires and standardized recall interviews by trained dieticians with the Globodiet software. CONCLUSION: SKSC provides a unique opportunity and resource to further study cause and course of kidney disease in a large population with data and samples collected of a homogeneous collective of patients throughout the whole Swiss population.

Performance of synacthen test in chronic hemodialysis patients.

BACKGROUND: Adrenal function tests (Synacthen test) in chronic hemodialysis (HD) patients are currently performed off dialysis. The study aimed to demonstrate equivalence of serum cortisol concentrations pre- and during HD, each for standard-dose (250 µg) and low-dose (1 µg) Synacthen test. METHODS: In a single-center cross-over diagnostic equivalence study, Synacthen tests were performed in four settings, in standard- and low-dose as well as pre- and during HD. Serum cortisol concentration was measured at 30 and 60 min after Synacthen administration, and additionally at 20 min in low dose test. Based on a multivariable linear mixed model the means of cortisol concentration on log-scale were estimated in each dose and test time combination. Differences in means were calculated and the TOST approach was applied to test for equivalence. Equivalence was proven if the 90% confidence interval of the difference of two cortisol means was entirely between - 0.22 and 0.22. RESULTS: In 28 chronic HD patients, serum cortisol concentrations at 30 and 60 min after Synacthen administration in both standard- and low-dose were shown to be equivalent pre- and during HD. In 10 of 56 low-dose tests, the cortisol peak was already reached after 20 min. However, cortisol concentrations at 20 and 30 min after low-dose Synacthen test pre- and during HD showed no significant difference. CONCLUSION: These results suggest that the adrenal function test may be carried out during an ongoing HD session, leading to a more patient-friendly performance of the test, less organizational effort and potentially earlier diagnosis of adrenal insufficiency.

Differences in the Food Consumption Between Kidney Stone Formers and Nonformers in the Swiss Kidney Stone Cohort.

OBJECTIVE: Diet has a major influence on the formation and management of kidney stones. However, kidney stone formers' diet is difficult to capture in a large population. Our objective was to describe the dietary intake of kidney stone formers in Switzerland and to compare it to nonstone formers. METHODS: We used data from the Swiss Kidney Stone Cohort (n = 261), a multicentric cohort of recurrent or incident kidney stone formers with additional risk factors, and a control group of computed tomography-scan proven nonstone formers (n = 197). Dieticians conducted two consecutive 24-h dietary recalls, using structured interviews and validated software (GloboDiet). We took the mean consumption per participant of the two 24-h dietary recalls to describe the dietary intake and used two-part models to compare the two groups. RESULTS: The dietary intake was overall similar between stone and nonstone formers. However, we identified that kidney stone formers had a higher probability of consuming cakes and biscuits (odds ratio (OR) [95% CI] = 1.56[1.03; 2.37]) and soft drinks (OR = 1.66[1.08; 2.55]). Kidney stone formers had a lower probability of consuming nuts and seeds (OR = 0.53[0.35; 0.82]), fresh cheese (OR = 0.54[0.30; 0.96]), teas (OR = 0.50[0.3; 0.84]), and alcoholic beverages (OR = 0.35[0.23; 0.54]), especially wine (OR = 0.42[0.27; 0.65]). Furthermore, among consumers, stone formers reported smaller quantities of vegetables (ß coeff[95% CI] = - 0.23[- 0.41; - 0.06]), coffee (ß coeff = - 0.21[- 0.37; - 0.05]), teas (ß coeff = - 0.52[- 0.92; - 0.11]) and alcoholic beverages (ß coeff = - 0.34[- 0.63; - 0.06]). CONCLUSION: Stone formers reported lower intakes of vegetables, tea, coffee, and alcoholic beverages, more specifically wine, but reported drinking more frequently soft drinks than nonstone formers. For the other food groups, stone formers and nonformers reported similar dietary intakes. Further research is needed to better understand the links between diet and kidney stone formation and develop dietary recommendations adapted to the local settings and cultural habits.

The Duffy antigen receptor for chemokines transports chemokines and supports their promigratory activity.

The Duffy antigen receptor for chemokines (DARC) belongs to a family of 'silent' heptahelical chemokine receptors that do not couple to G proteins and fail to transmit measurable intracellular signals. DARC binds most inflammatory chemokines and is prominently expressed on venular endothelial cells, where its function has remained contentious. Here we show that DARC, like other silent receptors, internalized chemokines but did not effectively scavenge them. Instead, DARC mediated chemokine transcytosis, which led to apical retention of intact chemokines and more leukocyte migration across monolayers expressing DARC. Mice overexpressing DARC on blood vessel endothelium had enhanced chemokine-induced leukocyte extravasation and contact-hypersensitivity reactions. Thus, interactions of chemokines with DARC support their activity on apposing leukocytes in vitro and in vivo.

Vascular endothelial growth factor D is a biomarker of fluid overload in haemodialysis patients.

BACKGROUND: Improved understanding and assessment of the complex physiology of volume regulation in haemodialysis (HD) patients are required to improve patient care and reduce mortality associated with fluid overload (FO). METHODS: We searched for FO-related biomarkers among 184 peptides associated with cardiovascular disease in a cohort of 30 HD patients. First, we assessed the direct impact of HD on the peptides of interest by comparing plasma concentrations before and after treatment. Then, we compared cardiovascular peptide profiles between patients with and without FO as defined by bioimpedance analysis (BIA). The plasma concentration of selected candidate biomarkers for FO was determined by enzyme-linked immunosorbent assay (ELISA) and correlated with previously described FO-related clinical and laboratory parameters. For validation, results were confirmed in an independent cohort of 144 HD patients. RESULTS: We found seven peptides positively [NT-proBNP, B-type natriuretic peptide (BNP), vascular endothelial growth factor D (VEGFD), tumour necrosis factor-related apoptosis-inducing ligand receptor 2, growth differentiation factor 15, tumour necrosis factor ligand superfamily member 13B, chitinase-3-like protein 1] and five negatively (leptin, renin, epidermal growth factor receptor, interleukin-1 receptor antagonist, myeloblastin) correlated to FO. In addition to natriuretic peptides, VEGFD emerged as third peptide highly correlated with BIA (ρ = 0.619, P < 0.0001). In line with this, VEGFD concentration verified by ELISA correlated with BIA, BNP and soluble CD146 but not with vascular endothelial growth factor C (VEGFC). Notably, levels of VEGFD were unrelated to cardiac systolic function (P = 0.63), contrary to BNP (P = 0.0003). Finally, we observed that 1-year all-cause mortality was higher in patients with high BNP (P = 0.0002), FO (defined by BIA, P = 0.04) and high VEGFD (P = 0.02), but not with high VEGFC (P = 0.48). CONCLUSION: VEGFD is a novel FO-related biomarker with unique diagnostic and prognostic properties.

Renal allograft DARCness in subclinical acute and chronic active ABMR.

Gene expression profiling of renal allograft biopsies revealed the Duffy antigen receptor for chemokines (DARC) as being strikingly upregulated in antibody-mediated rejection (ABMR). DARC has previously been shown to be associated with endothelial injury. This study aimed at assessing the value of DARC immunohistochemistry as diagnostic marker in ABMR. The study was performed on 82 prospectively collected biopsies of a clinically well-defined population (BORTEJECT trial, NCT01873157) of DSA-positive patients with gene expression data available for all biopsies. Diagnostic histologic assessment of biopsies was performed according to the Banff diagnostic scheme. DARC expression was focally accentuated, on peritubular capillaries (PTC) mostly in areas of interstitial fibrosis and/or inflammation. DARC positivity was associated with diagnosis of ABMR and correlated with DARC gene expression levels detected by microarray analysis. Still, as previously described, a substantial number of biopsies without signs of rejection showed DARC-positive PTC. We did not observe significantly reduced graft survival in cases showing histologic signs of ABMR and being DARC-positive, as compared to DARC-negative ABMR. In summary, the upregulation of DARC, detected by immunohistochemistry, is associated with but not specific for ABMR. We did not observe reduced graft survival in DARC-positive patients.

Dialysis after graft loss: a Swiss experience.

BACKGROUND: Patients returning to dialysis after graft loss have high early morbidity and mortality. METHODS: We used data from the Swiss Transplant Cohort Study to describe the current practice and outcomes in Switzerland. All patients who received a renal allograft between May 2008 and December 2014 were included. The patients with graft loss were divided into two groups depending on whether the graft loss occurred within 1 year after transplantation (early graft loss group) or later (late graft loss group). Patients with primary non-function who never gained graft function were excluded. RESULTS: Seventy-seven out of 1502 patients lost their graft during follow-up, 40 within 1 year after transplantation. Eleven patients died within 30 days after allograft loss. Patient survival was 86, 81 and 74% at 30, 90 and 365 days after graft loss, respectively. About 92% started haemodialysis, 62% with definitive vascular access, which was associated with decreased mortality (hazard ratio = 0.28). At the time of graft loss, most patients were on triple immunosuppressive therapy with significant reduction after nephrectomy. One year after graft loss, 77.5% (31 of 40) of patients in the early and 43.2% (16 out of 37) in the late-loss group had undergone nephrectomy. Three years after graft loss, 36% of the patients with early and 12% with late graft loss received another allograft. CONCLUSION: In summary, our data illustrate high mortality, and a high number of allograft nephrectomies and re-transplantations. Patients commencing haemodialysis with a catheter had significantly higher mortality than patients with definitive access. The role of immunosuppression reduction and allograft nephrectomy as interdependent factors for mortality and re-transplantation needs further evaluation.

Development of autoimmune pancreatitis is independent of CDKN1A/p21-mediated pancreatic inflammation.

OBJECTIVE: Chronic pancreatitis (CP) and autoimmune pancreatitis (AIP) are characterised by different inflammatory processes. If pancreatic inflammation is a prerequisite for autoimmunity is still unclear. AIP is considered mostly a T cell-mediated disease; however, in induction of CP, macrophages play a pivotal role. p21-a member of cyclin-dependent kinase inhibitors-can influence inflammatory processes, in particular can regulate T cell activation and promote macrophage development. We therefore examined the role of p21-mediated inflammation in AIP. DESIGN: We intercrossed lymphotoxin (LT) overexpressing mice (Tg(Ela1-LTa,b))-a model to study AIP development-with p21-deficient mice. Furthermore, we characterised p21 expression in human AIP and non-AIP specimens. RESULTS: p21 deficiency in LT mice (LTp21-/-) prevented early pancreatic injury and reduced inflammation. In acinar cells, diminished proliferation and abrogated activation of non-canonical nuclear factor kappa-light-chain-enhancer of activated B cell (NF-κB) pathway was observed. In contrast, 12-month-old LT mice with and without p21 had similar inflammatory signatures and T-B cell infiltration. Interestingly, LT and LTp21-/- mice had comparable tertiary lymphoid organs (TLOs), autoantibodies and elevated IgG levels. However, acinar cell proliferation, acinar-to-ductal metaplasia and acinar non-canonical NF-κB pathway activation remained impaired in LTp21-/- pancreata. CONCLUSIONS: Our findings indicate that p21 is crucial for pancreatic inflammation in LT-driven pancreatic injury. p21 is involved in early acinar secretion of inflammatory mediators that attract innate immune cells. However, p21 is not essential for humoral immune response, accountable for autoimmunity. Remarkably, p21 renders acinar cells less susceptible to proliferation and transdifferentiation. We therefore suggest that AIP can also develop independent of chronic inflammatory processes.

Soluble CD146 and B-type natriuretic peptide dissect overhydration into functional components of prognostic relevance in haemodialysis patients.

Background: Accurate volume status evaluation and differentiation of cardiac and non-cardiac components of overhydration (OH) are fundaments of optimal haemodialysis (HD) management. Methods: This study, by combining bioimpedance measurements, cardiovascular biomarkers and echocardiography, aimed at dissecting OH into its major functional components, and prospectively tested the association between cardiac and non-cardiac components of OH with mortality. In the first part, we validated soluble CD146 (sCD146) as a non-cardiac biomarker of systemic congestion in a cohort of 30 HD patients. In the second part, we performed a prospective 1-year follow-up study in an independent cohort of 144 HD patients. Results: sCD146 incrementally increased after the short and long intervals after HD (+53 ng/mL, P = 0.006 and +91 ng/mL, P < 0.001), correlated with OH as determined by bioimpedance and well-diagnosed OH (area under the receiver operating characteristics curve 0.72, P = 0.005). The prevalence of OH was lower for low-sCD146 and low-BNP patients (B-type natriuretic peptide, 29%) compared with subjects with either one or both biomarkers elevated (65-74%, P < 0.001). Notably, most low-BNP but high-sCD146 subjects were overhydrated. Systolic dysfunction was 2- to 3-fold more prevalent among high-BNP compared with low-BNP patients (44-68% versus 21-23%, chi-square P < 0.001), regardless of sCD146. One-year all-cause mortality was markedly higher in patients with high-BNP (P = 0.001) but not with high-sCD146. In multivariate analysis, systolic dysfunction and BNP, but not OH, were associated with lower survival. Conclusions: The combination of BNP and sCD146 dissects OH into functional components of prognostic value. OH in HD patients is associated with higher mortality only if resulting from cardiac dysfunction.

High accuracy of proximity extension assay technology for the quantification of plasma brain natriuretic peptide.

BACKGROUND: Novel multiplex assays allow the simultaneous identification of a large number of plasma proteins. While these new technologies have been shown to be highly sensitive and accurate for the identification of plasma proteins, the use of this technology to quantify those proteins has not been properly investigated. In this pilot study, we tested the accuracy of the proximity extension assay (PEA) for the quantification of the cardiac biomarker brain natriuretic peptide (BNP) compared to a standard clinically approved method. METHODS: Concentrations of BNP were assessed in 120 plasma samples from 30 patients with PEA and compared to chemiluminescent microparticle immunoassay (CMIA). Venous blood samples were collected from in tubes containing ethylenediaminetetraacetic acid, centrifuged within 6 hours at 3,500 rpm for 15 minutes at 4°C, frozen and stored at -80°C until analyzed. Correlation between the CMIA and PEA techniques was tested using the Spearman's rank correlation coefficient (rho) and the agreement was described with a Bland-Altman plot. RESULTS: Brain natriuretic peptide values obtained by CMIA and PEA were highly correlated (Spearman's rho = 0.865, P < .0001). In two patients, PEA consistently overestimated resp. underestimated BNP values compared to CMIA. After removal of those two patients, a very high correlation between the two techniques was shown (rho = 0.966, P < .0001). A high agreement between the two techniques over the whole range of tested concentrations was shown. CONCLUSION: This pilot study showed for the first time an excellent correlation between a clinically approved method and the PEA-based approach for quantification of circulating plasma BNP.

Gender-Specific Differences in Peritoneal Dialysis.

BACKGROUND/AIMS: Gender-specific differences between patients on renal replacement therapy have so far rarely been investigated. In the present study we aimed to describe gender-specific differences in a large cohort of peritoneal dialysis (PD) patients. METHODS: Clinical information for all patients who started PD at our center has been collected since the start of the PD-program in 1979. We used Cox regression to examine associations between technique failure and gender. We estimated hazard ratios (HRs) with 95% confidence intervals (CIs). RESULTS: A total of 745 patients (315 women and 430 men with a median age of 57 years; IQR 43-67) started PD between 1979 and 2015 in our center. Women were significantly younger at PD start 54 (40-65) years vs. 58 (47-68) years, p<0.001. Within the last almost 15 years, more man than women started PD, but technical survival rates were significantly better in female compared to men (HR=0.662, CI 95% (0.496-0.885) P=0.005). Cardiovascular events were the main cause of death over the study period in both sexes, but decreased over time. Additionally, death due to PD-associated peritonitis decreased significantly over the three decades in both sexes. CONCLUSIONS: Our data suggest that technical survival rates were significantly better in female compared to men over three decades and death due to cardiovascular events and PD-associated peritonitis decreased significantly over the three decades in both sexes.

CD147 expression in peritoneal injury.

BACKGROUND: Peritoneal injury is an important cause of technical failure of long-term peritoneal dialysis (PD). Encapsulating peritoneal sclerosis (EPS) is a severe complication of long-term PD with potentially life threatening consequences. CD147 is a glycoprotein with diverse functions including modulation of extracellular matrix via induction of matrix metalloproteinases, cell adhesion, and regulation of immune reactions. We hypothesized that CD 147 plays a role in the peritoneal cavity. METHODS: In this retrospective study, we localized CD147 by immunohistochemistry in peritoneal biopsies from uremic patients not on PD (n = 8), on PD without signs of EPS (n = 7), and in biopsies in patients with the diagnosis of EPS (n = 7). Double immunofluorescence was used to co-localize α-smooth-muscle actin (α-SMA) and CD147 in selected biopsies from each group. Expression was scored semi-quantitatively. RESULTS: In biopsies from uremic controls, CD147 was prominently expressed in mesothelial cells, focally between fat cells and by some perivascular cells. In patients on PD, a similar distribution was present (although mesothelium was rarely conserved), with some focal accentuation. In EPS, layers of fibroblastic cells were positive for CD147. EPS biopsies demonstrated a significantly higher score in a blinded evaluation, compared to uremic patients. Cells expressing CD147 were α-SMA positive myofibroblasts as demonstrated by double immunofluorescence. Mean CD147 scores did not differ between patients with different transporter status. CONCLUSIONS: This is the first study demonstrating CD147 on a major part of fibroblastic cells in EPS. Future studies need to address the role of these cells in this severe complication of long-term PD.

Human proximal tubule cells form functional microtissues.

The epithelial cells lining the proximal tubules of the kidney mediate complex transport processes and are particularly vulnerable to drug toxicity. Drug toxicity studies are classically based on two-dimensional cultures of immortalized proximal tubular cells. Such immortalized cells are dedifferentiated, and lose transport properties (including saturable endocytic uptake) encountered in vivo. Generating differentiated, organotypic human microtissues would potentially alleviate these limitations and facilitate drug toxicity studies. Here, we describe the generation and characterization of kidney microtissues from immortalized (HK-2) and primary (HRPTEpiC) human renal proximal tubular epithelial cells under well-defined conditions. Microtissue cultures were done in hanging drop GravityPLUS™ culture plates and were characterized for morphology, proliferation and differentiation markers, and by monitoring the endocytic uptake of albumin. Kidney microtissues were successfully obtained by co-culturing HK-2 or HRPTEpiC cells with fibroblasts. The HK-2 microtissues formed highly proliferative, but dedifferentiated microtissues within 10 days of culture, while co-culture with fibroblasts yielded spherical structures already after 2 days. Low passage HRPTEpiC microtissues (mono- and co-culture) were less proliferative and expressed tissue-specific differentiation markers. Electron microscopy evidenced epithelial differentiation markers including microvilli, tight junctions, endosomes, and lysosomes in the co-cultured HRPTEpiC microtissues. The co-cultured HRPTEpiC microtissues showed specific uptake of albumin that could be inhibited by cadmium and gentamycin. In conclusion, we established a reliable hanging drop protocol to obtain functional kidney microtissues with proximal tubular epithelial cell lines. These microtissues could be used for high-throughput drug and toxicology screenings, with endocytosis as a functional readout.

The lymphotoxin ß receptor is a potential therapeutic target in renal inflammation.

Accumulation of inflammatory cells in different renal compartments is a hallmark of progressive kidney diseases including glomerulonephritis (GN). Lymphotoxin ß receptor (LTßR) signaling is crucial for the formation of lymphoid tissue, and inhibition of LTßR signaling has ameliorated several non-renal inflammatory models. Therefore, we tested whether LTßR signaling could also have a role in renal injury. Renal biopsies from patients with GN were found to express both LTα and LTß ligands, as well as LTßR. The LTßR protein and mRNA were localized to tubular epithelial cells, parietal epithelial cells, crescents, and cells of the glomerular tuft, whereas LTß was found on lymphocytes and tubular epithelial cells. Human tubular epithelial cells, mesangial cells, and mouse parietal epithelial cells expressed both LTα and LTß mRNA upon stimulation with TNF in vitro. Several chemokine mRNAs and proteins were expressed in response to LTßR signaling. Importantly, in a murine lupus model, LTßR blockade improved renal function without the reduction of serum autoantibody titers or glomerular immune complex deposition. Thus, a preclinical mouse model and human studies strongly suggest that LTßR signaling is involved in renal injury and may be a suitable therapeutic target in renal diseases.

Vertebral and internal mammary artery steal syndrome in patients with hemodialysis access.

BACKGROUND: Increased flow in the subclavian artery feeding a vascular access for hemodialysis can induce steal phenomena in the vertebral (VA) and internal mammary artery (IMA). The aim of this study was to describe the hemodynamic effects of access flow on the VA and IMA in patients with native fistulas and grafts. PATIENTS AND METHODS: Peak systolic (PSV) and end diastolic (EDV) velocity measurements of the VA, IMA and carotid arteries, as well as flow volume measurements of the subclavian artery, were performed. Flow measurements at the side of the vascular access were compared with the contralateral side. Fifty-five patients were consecutively included, most with a radio-cephalic fistula on the left arm with a mean shunt volume of 1156 ml/min. RESULTS: Pathologic flow patterns were observed in the ipsilateral VA in four patients (7.3 %); contralateral VA flow was normal in all patients. Peak systolic velocity of the VA was significantly decreased at the side of the shunt arm with a PSV of 42.6 ± 11.8 cm/s compared to 48.4 ± 15.6 cm/s contralateral (p < 0.05). The IMA flow pattern were normal in all patients. The PSV of the IMA was significantly decreased (p < 0.01) at the side of the shunt arm (87.5 ± 29.1 cm/s) compared to the non-shunt arm (95.9 ± 27.4 cm/s). CONCLUSION: We describe significant hemodynamic effects of fistulas to the vertebral and internal mammary arteries. Doppler spectral analysis of the vertebral and internal mammary arteries should be integrated in ultrasound, especially in patients with cerebrovascular or cardiac symptoms.

Activation of nuclear factor of activated T cells 5 in the peritoneal membrane of uremic patients.

Peritoneal inflammation and fibrosis are responses to the uremic milieu and exposure to hyperosmolar dialysis fluids in patients on peritoneal dialysis. Cells respond to high osmolarity via the transcription factor nuclear factor of activated T cells (NFAT5). In the present study, the response of human peritoneal fibroblasts to glucose was analyzed in vitro. Expression levels of NFAT5 and chemokine (C-C motif) ligand (CCL2) mRNA were quantified in peritoneal biopsies of five nonuremic control patients, five uremic patients before PD (pPD), and eight patients on PD (oPD) using real-time PCR. Biopsies from 5 control patients, 25 pPD patients, and 25 oPD patients were investigated using immunohistochemistry to detect the expression of NFAT5, CCL2, NF-κB p50, NF-κB p65, and CD68. High glucose concentrations led to an early, dose-dependent induction of NFAT5 mRNA in human peritoneal fibroblasts. CCL2 mRNA expression was upregulated by high concentrations of glucose after 6 h, but, most notably, a concentration-dependent induction of CCL2 was present after 96 h. In human peritoneal biopsies, NFAT5 mRNA levels were increased in uremic patients compared with nonuremic control patients. No significant difference was found between the pPD group and oPD group. CCL2 mRNA expression was higher in the oPD group. Immunohistochemistry analysis was consistent with the results of mRNA analysis. CD68-positive cells were significantly increased in the oPD group. In conclusion, uremia results in NFAT5 induction, which might promote early changes of the peritoneum. Upregulation of NFAT5 in PD patients is associated with NFκB induction, potentially resulting in the recruitment of macrophages.

Clinical course and long-term outcome of hantavirus-associated nephropathia epidemica, Germany.

Human infection with Puumala virus (PUUV), the most common hantavirus in Central Europe, causes nephropathia epidemica (NE), a disease characterized by acute kidney injury and thrombocytopenia. To determine the clinical phenotype of hantavirus-infected patients and their long-term outcome and humoral immunity to PUUV, we conducted a cross-sectional prospective survey of 456 patients in Germany with clinically and serologically confirmed hantavirus-associated NE during 2001-2012. Prominent clinical findings during acute NE were fever and back/limb pain, and 88% of the patients had acute kidney injury. At follow-up (7-35 mo), all patients had detectable hantavirus-specific IgG; 8.5% had persistent IgM; 25% had hematuria; 23% had hypertension (new diagnosis for 67%); and 7% had proteinuria. NE-associated hypertension and proteinuria do not appear to have long-term consequences, but NE-associated hematuria may. All patients in this study had hantavirus-specific IgG up to years after the infection.

The Rho-GTPase binding protein IQGAP2 is required for the glomerular filtration barrier.

Podocyte dysfunction impairs the size selectivity of the glomerular filter, leading to proteinuria, hypoalbuminuria, and edema, clinically defined as nephrotic syndrome. Hereditary forms of nephrotic syndrome are linked to mutations in podocyte-specific genes. To identify genes contributing to podocyte dysfunction in acquired nephrotic syndrome, we studied human glomerular gene expression data sets for glomerular-enriched gene transcripts differentially regulated between pretransplant biopsy samples and biopsies from patients with nephrotic syndrome. Candidate genes were screened by in situ hybridization for expression in the zebrafish pronephros, an easy-to-use in vivo assay system to assess podocyte function. One glomerulus-enriched product was the Rho-GTPase binding protein, IQGAP2. Immunohistochemistry found a strong presence of IQGAP2 in normal human and zebrafish podocytes. In zebrafish larvae, morpholino-based knockdown of iqgap2 caused a mild foot process effacement of zebrafish podocytes and a cystic dilation of the urinary space of Bowman's capsule upon onset of urinary filtration. Moreover, the glomerulus of zebrafish morphants showed a glomerular permeability for injected high-molecular-weight dextrans, indicating an impaired size selectivity of the glomerular filter. Thus, IQGAP2 is a Rho-GTPase binding protein, highly abundant in human and zebrafish podocytes, which controls normal podocyte structure and function as evidenced in the zebrafish pronephros.

Acute kidney injury and tools for risk-stratification in 456 patients with hantavirus-induced nephropathia epidemica.

BACKGROUND: Puumala virus (PUUV) is the most common species of hantavirus in Central Europe. Nephropathia epidemica (NE), caused by PUUV, is characterized by acute kidney injury (AKI) and thrombocytopenia. The major goals of this study were to provide a clear clinical phenotyping of AKI in patients with NE and to develop an easy prediction rule to identify patients, who are at lower risk to develop severe AKI. METHODS: A cross-sectional prospective survey of 456 adult patients with serologically confirmed NE was performed. Data were collected from medical records and prospectively at follow-up visit. Severe AKI was defined by standard criteria according to the RIFLE (Risk, Injury, Failure, Loss, End-stage kidney disease) classification. Fuller statistical models were developed and validated to estimate the probability for severe AKI. RESULTS: During acute NE, 88% of the patients had AKI according to the RILFE criteria during acute NE. A risk index score for severe AKI was derived by using three independent risk factors in patients with normal kidney function at time of diagnosis: thrombocytopenia [two points; odds ratios (OR): 3.77; 95% confidence intervals (CI): 1.82, 8.03], elevated C-reactive protein levels (one point; OR: 3.02; 95% CI: 1.42, 6.58) and proteinuria (one point; OR: 3.92; 95% CI: 1.33, 13.35). On the basis of a point score of one or two, the probability of severe AKI was 0.18 and 0.28 with an area under the curve of 0.71. CONCLUSION: This clinical prediction rule provides a novel and diagnostically accurate strategy for the potential prevention and improved management of kidney complications in patients with NE and, ultimately, for a possible decrease in unnecessary hospitalization in a high number of patients.

Evaluation of lipase levels in patients with nephropathia epidemica--no evidence for acute pancreatitis.

BACKGROUND: The most common causative agent for hemorrhagic fever with renal syndrome in Germany is Puumala virus (PUUV) and a high percentage of patients with PUUV infection have gastrointestinal (GI) symptoms. The aim of the present study was to determine the prevalence of increased lipase levels and acute pancreatitis during nephropathia epidemica (NE) in 166 patients from Germany. METHODS: Clinical and laboratory data during the acute phase of the disease were obtained from medical reports and files from 456 patients during acute hantavirus infection. Patients in whom serum lipase levels were determined during acute course of the disease were included in the study. RESULTS: Lipase levels at the time of diagnosis were determined in 166 of the 456 NE patients (36%). Of the 166 patients, 25 (15%) had elevated lipase levels at the time of admission to hospital or first contact with general practitioner/nephrologist. In total 7 patients had a threefold increased serum lipase above the normal range. Abdominal pain was not more often present in the group of patients with elevated serum lipase compared to the lipase-negative group (9/25 vs 58/141). Abdominal ultrasound and CT scans revealed no signs of pancreatitis in any of the patients. Patients with elevated serum lipase had higher serum creatinine peak levels (p = 0.03) during the course of the disease. CONCLUSIONS: Elevated lipase levels were common in our patient cohort and might reflect a more severe form of NE. NE does not lead to acute pancreatitis.