Classifying Hypotonic Hyponatremia by Projected Treatment Effects - A Quantitative 3-Dimensional Framework

Introduction

The diagnostic algorithms currently used for hypotonic hyponatremia focus primarily on impaired urinary dilution and often neglect the influence of free water intake and solute excretion. We hypothesized that, in each case of hypotonic hyponatremia different pathophysiological mechanisms play a role simultaneously.

Methods

Using clinical data of the previous observational Co-Med study, we defined each case of hypotonic hyponatremia concurrently in 3 dimensions as follows: (i) high net free water intake (HNFWI), (ii) impaired dilution of the urine (IDU), and (iii) low nonelectrolyte solute excretion (LNESE). For each dimension, a "standard delta sodium" (sdna) was calculated reflecting the expected difference to the serum sodium concentration, that would result from changing a dimension to a specific and equivalent target level.

Results

Results from 279 patients were used for this analysis. With target levels of free water intake and urine osmolality at the fifth percentile, and nonelectrolyte solute excretion at the 95th percentile, median (interquartile range) sdna values were 7.1 (4.8-10.2) for HNFWI, 11.8 (7.0-18.6) for IDU and 2.6 (1.6-4.2) mmol/l per 24 hours for LNESE. Sdna results in individual patients were highest with IDU in 68.5%, HNFWI in 30.8% and 0.7% with LNESE. At an sdna-level of at least 4mmol/l per 24 hours, the prevalence of HNFWI was 78.9%, IDU 87.1%, and LNESE 26.5%. 77.5% of patients had 2 or all 3 mechanisms present. Hyponatremia was mostly multifactorial in subgroups according to classic categories of hyponatremia and typical comorbidities as well.

Conclusion

Hypotonic hyponatremia can be quantitatively defined by 3 dimensions. Most cases should be considered multifactorial.

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 non-formers 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 non-stone 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 CT-scan proven non-stone 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 non-stone 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 (β coeff[95% CI]= - 0.23[- 0.41; - 0.06]), coffee (β coeff= - 0.21[- 0.37; - 0.05]), teas (β coeff= - 0.52[- 0.92; - 0.11]) and alcoholic beverages (β 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 non-stone formers. For the other food groups, stone formers and non-formers 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 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.

Novel classification of proximal forearm perforator vein in the planning and creation of percutaneous and surgical Gracz-type arteriovenous fistulae

BACKGROUND

The perforator vein determines whether it is feasible to create a percutaneous (pAVF) or surgical "Gracz-type" arteriovenous fistula (sAVF). Creating a standard anatomic classification of the antecubital region is beneficial to both the selection of the appropriate device and/or procedure and technical outcomes. Accordingly, an analysis of a large cohort of patients undergoing pAVF/sAVF was performed, focusing on perforator vein anatomical suitability, and a novel anatomical classification of the antecubital region was developed and proposed.

METHODS

Between August 2018 and July 2022, chronic or end-stage kidney disease patients as well as patients anticipated an initiation of apheresis, who were referred for vascular access planning, underwent a standardized evaluation of upper extremities. A vessel mapping summary detailing the vasculature and the access creation plan was completed, indicating the anatomical suitability for sAVF and pAVF (Ellipsys and WavelinQ) techniques.

RESULTS

Of 524 patients, 36.5% were female (average age 65 years). 53.2% were on dialysis, 41.6% had diabetes, and 13.2% had a previously failed permanent dialysis access. The anatomy for successful pAVF creation was judged to be suitable in 54% of patients for an Ellipsys-pAVF, and 29.8% for WavelinQ-pAVF. Of the WavelinQ group, 54.4% had suitable anatomy for ulnar, 26.9% for radial, and 18.6% for both ulnar/radial anastomoses. Additionally, 60.7% had suitable anatomy for pAVF creation with at least one of the systems, while 22.5% were suited for both types of pAVF-systems. 80.3% were candidates for creation of a Gracz-AVF.

CONCLUSION

Overall, we found that about 60% of patients are likely candidates for a pAVF, with 80% being candidates for creation of a Gracz-AVF. Male patients have significantly higher suitability for most types of AVF creation, and younger patients are more suitable for Ellipsys-pAVF and RCAVFs. Most importantly, a universal classification of perforator vein was developed, which is indispensable in modern vascular access planning.

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.

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.

Admission kidney function is a strong predictor for the response to nutritional support in patients at nutritional risk

BACKGROUND

Patients with chronic kidney disease (CKD) are at substantial risk of malnutrition, which negatively affects clinical outcomes. We investigated the association of kidney function assessed at hospital admission and effectiveness of nutritional support in hospitalized medical patients at risk of malnutrition.

METHODS

This is a secondary analysis of an investigator-initiated, randomized-controlled, Swiss multicenter trial (EFFORT) that compared individualised nutritional support with usual hospital food on clinical outcomes. We compared effects of nutritional support on mortality in subgroups of patients stratified according to kidney function at the time of hospital admission (estimated glomerular filtration rates [eGFR] <15, 15-29, 30-59, 60-89 and ≥ 90 ml/min/1.73 m²).

RESULTS

We included 1943 of 2028 patients (96%) from the original trial with known admission creatinine levels. Admission eGFR was a strong predictor for the beneficial effects of nutritional support in regard to lowering of 30-day mortality. Patients with an eGFR <15, 15-29 and 30-59 had the strongest mortality benefit (odds ratios [95%CI] of 0.24 [0.05 to 1.25], 0.37 [0.14 to 0.95] and 0.39 [0.21 to 0.75], respectively), while patients with less severe impairment in kidney function had a less pronounced mortality benefits (p for interaction 0.001). A similar stepwise association of kidney function and response to nutritional support was found also for other secondary outcomes.

CONCLUSION

In medical inpatients at nutritional risk, admission kidney function was a strong predictor for the response to nutritional therapy. Initial kidney function may help to individualize nutritional support in the future by identification of patients with most clinical benefit.

CLINICAL TRIAL REGISTRATION

Registered under ClinicalTrials.gov Identifier no. NCT02517476.

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.

Amelioration of Murine Autoimmune Pancreatitis by Targeted LTβR Inhibition and Anti-CD20 Treatment

Autoimmune pancreatitis (AIP) is a rare form of chronic pancreatitis, for which treatment options, especially the long-term management, are limited. The only therapy that has been established and accepted so far is corticosteroids, but the relapse rate is significant. In the current study, we discern the effector mechanisms of targeted LTβR pathway inhibition using LTβR-Ig. Furthermore, the efficacy of LTβR-Ig therapy is compared with the depletion of immune cell subsets (CD4⁺ and CD20⁺), which are suggested to play a pathological role in AIP development. Three well-established mouse models of AIP were used to examine treatment efficacies and mechanisms. Tg(Ela1-Lta,b) mice represent a genetic model, in which AIP develops spontaneously. In MRL/Mp and IL-10^-/- mice, AIP is induced by repeated polyinosinic:polycytidylic acid injection. Mice with AIP were treated with anti-CD20, anti-CD4 mAbs, or targeted LTβR-Ig. LTβR-Ig and anti-CD20 treatment led to significant improvement of AIP, including a decrease in autoantibody production and pancreatic inflammation in Tg(Ela1-Lta,b) and IL-10^-/- mice. The molecular mechanism of this beneficial effect possibly involves the downregulation of Stat3 and noncanonical NF-κb activation. Anti-CD4 treatment reduced Th1 and Th2 signature but did not alleviate AIP. Additionally, in contrast to anti-CD20 or anti-CD4 treatments, blocking LTβR signaling disrupted tertiary lymphoid organs in all three models. We demonstrate that treatment with LTβR-Ig or anti-CD20 Ab alleviated murine AIP. LTβR-Ig treatment for AIP was effective in both lymphotoxin-dependent and lymphotoxin-independent AIP models, possibly because of its dual anti-inflammatory and antiautoimmune mechanisms.

Estimated glomerular filtration rate predicts 30-day mortality in medical emergency departments: Results of a prospective multi-national observational study

BACKGROUND

Renal failure is common in patients seeking help in medical emergency departments. Decreased renal function is associated with increased mortality in patients with heart failure or sepsis. In this study, the association between renal function (reflected by estimated glomerular filtration rate (eGFR) at the time of admission) and clinical outcome was evaluated.

METHODS/OBJECTIVES

Data was used from a prospective, multi-national, observational cohort of patients treated in three medical emergency departments of tertiary care centers. The eGFR was calculated from the creatinine at the time of admission (using the Chronic Kidney Disease-Epidemiology Collaboration equation,CKD-EPI). Uni- and multivariate regression models were used for eGFR and 30-day mortality, in hospital mortality, length of stay and intensive care unit admission rate.

RESULTS

6983 patients were included. The 30-day mortality was 1.8%, 3.5%, 6.9%, 11.1%, 13.6%, and 14.2% in patients with eGFR of above 90, 60-89, 45-59, 30-44, 15-29, and <15 ml/min/1.73m2, respectively. Using multivariate regression, the adjusted odds ratio (OR) was 2.31 (for 15-29 ml/min/1.73m2, 95% confidence interval 1.36 to 3.90, p = 0.002) and 3.73 (for eGFR <15ml/min/1.73m2 as compared to >90 ml/min/1.73m2, 95% CI 2.04 to 6.84, p<0.001). For 10 ml/min/1.73m2 decrease in eGFR the OR for the 30-day mortality was 1.15 (95% CI1.09 to 1.22, p<0.001).The eGFR was also significantly associated with in-hospital mortality, the percentage of ICU-admissions, and with a longer hospital stay. No association was found with hospital readmission within 30 days. As limitations, only eGFR at admission was available and the number of patients on hemodialysis was unknown.

CONCLUSION

Reduced eGFR at the time of admission is a strong and independent predictor for adverse outcome in this large population of patients admitted to medical emergency departments.

Finding the Right Position: A Three-Year, Single-Center Experience with the “Self-Locating” Catheter

Background

Peritoneal dialysis (PD) catheter displacement is a major cause of dysfunction. Various catheter forms have been designed to improve outcome. One of them is based on the classical Tenckhoff catheter, but includes a small tungsten cylinder at the distal end to optimize location and to prevent dislocations.

Methods

In this retrospective study, we analyzed the functionality and complication profile of the self-locating catheter implanted at our center from November 2005 to September 2008 in our PD program.

Results

Data from 27 self-locating catheters implanted in 25 patients (12 women) were obtained. Patients were followed for up to 30 months (median observation time: 13 months), resulting in a cumulative study period of 357 PD months. A total of 22 complications were identified, including 1 episode of peritonitis per 52 patient–months, 1 tunnel infection, and 1 exit-site infection. The “functional catheter failure incidence rate” was approximately 0.01 catheters per month on PD (or approximately 1 catheter loss per 100 PD months). The catheter survival was 93% at 1 year.

Conclusions

The “self-locating” PD catheter demonstrates low rates of catheter migration and dislocations, and good catheter survival.

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.

Clostridium Ramosum-A Rare Cause of Peritoneal Dialysis-Related Peritonitis

We present the first report of a patient with peritoneal dialysis (PD)-related peritonitis due to Clostridium ramosum, an anaerobe bacterium that is commonly found in normal fecal flora. On rare occasions, it can be pathogenic in immunocompromised individuals. Clostridium species, including Clostridium ramosum, should be included in the differential diagnosis of PD-related peritonitis.

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.

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.

Lymphotoxin expression in human and murine renal allografts

The kidney is the most frequently transplanted solid organ. Recruitment of inflammatory cells, ranging from diffuse to nodular accumulations with defined microarchitecture, is a hallmark of acute and chronic renal allograft injury. Lymphotoxins (LTs) mediate the communication of lymphocytes and stromal cells and play a pivotal role in chronic inflammation and formation of lymphoid tissue. The aim of this study was to assess the expression of members of the LT system in acute rejection (AR) and chronic renal allograft injury such as transplant glomerulopathy (TG) and interstitial fibrosis/tubular atrophy (IFTA). We investigated differentially regulated components in transcriptomes of human renal allograft biopsies. By microarray analysis, we found the upregulation of LTβ, LIGHT, HVEM and TNF receptors 1 and 2 in AR and IFTA in human renal allograft biopsies. In addition, there was clear evidence for the activation of the NFκB pathway, most likely a consequence of LTβ receptor stimulation. In human renal allograft biopsies with transplant glomerulopathy (TG) two distinct transcriptional patterns of LT activation were revealed. By quantitative RT-PCR robust upregulation of LTα, LTβ and LIGHT was shown in biopsies with borderline lesions and AR. Immunohistochemistry revealed expression of LTβ in tubular epithelial cells and inflammatory infiltrates in transplant biopsies with AR and IFTA. Finally, activation of LT signaling was reproduced in a murine model of renal transplantation with AR. In summary, our results indicate a potential role of the LT system in acute renal allograft rejection and chronic transplant injury. Activation of the LT system in allograft rejection in rodents indicates a species independent mechanism. The functional role of the LT system in acute renal allograft rejection and chronic injury remains to be determined.

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.

Alteration of membrane complement regulators is associated with transporter status in patients on peritoneal dialysis

Introduction

A growing body of evidence from animal models and cell culture studies indicate an important role of a local regulatory complement system (CS) in peritoneal injury during peritoneal dialysis (PD). We investigated the expression of the local regulatory CS (reflected by CD46,CD55,CD59) in the peritoneal tissue of patients with different membrane function characteristics.

Patients and methods

Biopsies from the parietal peritoneum were taken from 24 patients on PD, 22 uremic patients prior to PD. PD patients were grouped according to the dialysate-to-plasma ratio of creatinine (D/P Cre) and ratio of dialysate glucose at 4 hours versus dialysate glucose at time zero (D/D0 glucose) into low or low-average peritoneal transport status (L/LA) and high-average or high-transport status (HA/H) groups. CD46, CD55, and CD59 RNA expression were analyzed by real-time polymerase chain reaction (RT-PCR). Further localization of membrane complement regulators (CRegs) and semiquantitatively analysis was done by immunohistochemistry (IHC).

Results

CD46 and CD59 expression were similar in all groups. CD55 expression was significantly decreased in the HA/H group compared to the L/LA group and to uremic controls (p < 0.05 and p = 0.05, respectively). No statistically significant differences in CD46, CD55, and CD55 expression were detected when considering the history of peritonitis. There was no statistically significant correlation between PD duration and the expressions of CD46, CD55, and CD59. IHC revealed strong CD46, CD55, and CD59 expression in mesothelial cells. CD55 and CD59 were additionally detected in the vasculature. Using IHC, CD46 was lower in PD patients compared to uremic controls (p>0.05), but there was no difference between the L/LA compared to the H/HA group. Moreover IHC confirmed decreased expression of CD55 in the HA/H group compared to the L/LA group and uremic controls (p<0.0001 and p = 0.0001, respectively).

Conclusion

CD55 expression is decreased in patients with fast transporter membrane function, whereas peritonitis and PD duration do not appear to alter CReg expression.

Electrocardiographic abnormalities and relative bradycardia in patients with hantavirus-induced nephropathia epidemica

BACKGROUND

Nephropathia epidemica (NE), caused by Puumala virus (PUUV), is characterized by acute kidney injury (AKI) and thrombocytopenia. Cardiac involvement with electrocardiographic (ECG) abnormalities has been previously reported in NE; however, its prognostic value is unknown. Relative bradycardia is an important clinical sign in various infectious diseases, and previous smaller studies have described pulse-temperature deficit in patients with PUUV infection.

METHODS

We performed a cross-sectional survey of 471 adult patients with serologically confirmed NE. Data were collected retrospectively from medical records and prospectively at follow-up visits. Patients for whom ECGs were recorded during the acute phase of disease were enrolled retrospectively (n=263). Three patients were excluded because of documented pre-existing ECG abnormalities prior to NE. All patients with ECG abnormalities during the acute phase underwent follow-up.

RESULTS

A total of 46 patients had ECG abnormalities at the time of admission to hospital (18%). T-wave inversion was the most frequent ECG abnormality (n=31 patients), followed by ST segment changes (nine patients with elevation and six with depression). No major adverse cardiac events occurred during follow-up (median 37months; range 34-63months). Of note, ECG abnormalities reverted to normal in the majority of the patients during follow-up. During the acute phase of NE, 149 of 186 patients had relative bradycardia, without implications for disease course.

CONCLUSIONS

Transient ECG abnormalities were detected in 18% of patients during acute NE but were not associated with negative cardiovascular outcome. Relative bradycardia was identified in 80% of the patients with acute NE.

The number of patients with severe encapsulating peritoneal sclerosis is decreasing in a large referral center in Germany

Background

Encapsulating peritoneal sclerosis (EPS) is the most severe complication associated with long-term peritoneal dialysis (PD). Previous studies noticed a sharp decline in new patients with severe EPS. We investigated the number of severe EPS patients in our large referral center over almost 20 years.

Methods

All late-stage EPS patients who underwent major surgery due to extensive symptoms caused by bowel obstruction (vomiting, abdominal pain, and weight loss) between March 1997 and end of December 2015 in our hospital were included in the present study. An index was calculated between the number of patients with severe EPS and the implanted PD catheters in our center.

Results

Between 1979 and 2015, a total of 745 PD catheters were implanted in our center, with a steady increase in the numbers between 2003 and 2015. First patient with severe EPS was treated in 1998, then a rise in the number of patients with EPS was present in 2005. The number of patients with EPS peaked in the period of 2010–2012 (15 patients within 3 years). Afterward, both the absolute numbers and the index between the number of patients with severe EPS and the implanted catheters demonstrated a prominent reduction in the next 3-year period from 2013 to 2015.

Conclusion

Our data support the hypothesis that there seems to be a decrease of late-stage EPS incidence over the last years, but data about milder or asymptomatic patients are lacking. This should be kept in mind while giving the patients information about different renal replacement therapies at start of dialysis.

Smoking Is a Risk Factor for Severe Acute Kidney Injury in Hantavirus-Induced Nephropathia Epidemica

BACKGROUND/AIMS

Hantaviruses are zoonotic pathogens causing emerging diseases worldwide. Patients typically present with fever, acute kidney injury (AKI) and thrombocytopenia. Puumala virus (PUUV) that causes nephropathia epidemica (NE) is common in Germany. Recently, a study from Finland revealed an association between nicotine consumption and the severity of AKI in NE. Differences between individuals in Finland and Germany might modulate the effect; therefore, the aim of our study was to prove that smoking is a risk factor for a severe course of NE in Germany.

METHODS

A cross-sectional prospective survey of 485 patients with hantavirus infections was performed. Clinical and laboratory data during the acute course of the disease were obtained from medical reports and files, while follow-up (including smoking status) data were collected prospectively.

RESULTS

Smoking information was available for 298 out of 485 patients (61%). Male was the predominant gender (67%), median age at the time of diagnosis was 50 (interquartile range, IQR 41-60) years and 34% of patients were current smokers during the phase of acute NE. Patients in the smoking group were significantly younger than in the non-smoking group (p < 0.0001). Peak serum creatinine levels were significantly higher in the smoking group than in the non-smoking patients (median 301 (IQR 186-469 μmol/l) vs. median 240 (IQR 137-469 μmol/l), p < 0.05). In addition, severe AKI (stages 2 and 3 using KDIGO criteria) was more common in current smokers (80%) than in the non-smokers (68%, p < 0.05).

CONCLUSION

Current smoking is a risk factor for severity of AKI in patients with acute PUUV infection in Germany. Therefore, information about smoking habits needs to be an integral part of the documentation in patients with suspected acute PUUV infection, and increased monitoring of kidney function should be done in NE patients who are current smokers.

[Thrombotic thrombocytopenic purpura after circumcision]

After circumcision, a young man developed a wound healing disorder. After presenting to our hospital for further wound care, laboratory results showed acute renal failure with hemolytic anemia and thrombocytopenia, which led to the diagnosis of postoperative thrombotic thrombocytopenic purpura (TTP). After therapy with plasma exchange and immunosuppressive therapy with prednisolone and rituximab, the patient recovered with normalization of laboratory results. The TTP is associated with low activity of ADAMTS13 with microvascular platelet aggregation and hemolytic anemia.

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

Abstract. 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.

The Role of T Cell Costimulation via DNAM-1 in Kidney Transplantation

DNAX accessory protein-1 (DNAM-1, CD226) is a co-stimulatory and adhesion molecule expressed mainly by natural killer cells and T cells. DNAM-1 and its two ligands CD112 and CD155 are important in graft-versus-host disease, but their role in solid organ transplantation is largely unknown. We investigated the relevance of this pathway in a mouse kidney transplantation model. CD112 and CD155 are constitutively expressed on renal tubular cells and strongly upregulated in acutely rejected renal allografts. In vitro DNAM-1 blockade during allogeneic priming reduced the allospecific T cell response but not the allospecific cytotoxicity against renal tubular epithelial cells. Accordingly, absence of DNAM-1 in recipient mice or absence of CD112 or CD155 in the kidney allograft did not significantly influence renal function and severity of rejection after transplantation, but led to a higher incidence of infarcts in CD112 and CD155 deficient kidney allografts. Thus, DNAM-1 blockade is not effective in preventing transplant rejection. Despite of being highly expressed, CD112 and CD155 do not appear to play a major immunogenic role in kidney transplantation. Considering the high incidence of renal infarcts in CD112 and CD155 deficient grafts, blocking these molecules might be detrimental.

Inhibition of Aerobic Glycolysis Attenuates Disease Progression in Polycystic Kidney Disease

Dysregulated signaling cascades alter energy metabolism and promote cell proliferation and cyst expansion in polycystic kidney disease (PKD). Here we tested whether metabolic reprogramming towards aerobic glycolysis (“Warburg effect”) plays a pathogenic role in male heterozygous Han:SPRD rats (Cy/+), a chronic progressive model of PKD. Using microarray analysis and qPCR, we found an upregulation of genes involved in glycolysis (Hk1, Hk2, Ldha) and a downregulation of genes involved in gluconeogenesis (G6pc, Lbp1) in cystic kidneys of Cy/+ rats compared with wild-type (+/+) rats. We then tested the effect of inhibiting glycolysis with 2-deoxyglucose (2DG) on renal functional loss and cyst progression in 5-week-old male Cy/+ rats. Treatment with 2DG (500 mg/kg/day) for 5 weeks resulted in significantly lower kidney weights (-27%) and 2-kidney/total-body-weight ratios (-20%) and decreased renal cyst index (-48%) compared with vehicle treatment. Cy/+ rats treated with 2DG also showed higher clearances of creatinine (1.98±0.67 vs 1.41±0.37 ml/min), BUN (0.69±0.26 vs 0.40±0.10 ml/min) and uric acid (0.38±0.20 vs 0.21±0.10 ml/min), and reduced albuminuria. Immunoblotting analysis of kidney tissues harvested from 2DG-treated Cy/+ rats showed increased phosphorylation of AMPK-α, a negative regulator of mTOR, and restoration of ERK signaling. Assessment of Ki-67 staining indicated that 2DG limits cyst progression through inhibition of epithelial cell proliferation. Taken together, our results show that targeting the glycolytic pathway may represent a promising therapeutic strategy to control cyst growth in PKD.

The lymphotoxin β 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 β receptor (LTβR) signaling is crucial for the formation of lymphoid tissue, and inhibition of LTβR signaling has ameliorated several non-renal inflammatory models. Therefore, we tested whether LTβR signaling could also have a role in renal injury. Renal biopsies from patients with GN were found to express both LTα and LTβ ligands, as well as LTβR. The LTβR protein and mRNA were localized to tubular epithelial cells, parietal epithelial cells, crescents, and cells of the glomerular tuft, whereas LTβ was found on lymphocytes and tubular epithelial cells. Human tubular epithelial cells, mesangial cells, and mouse parietal epithelial cells expressed both LTα and LTβ mRNA upon stimulation with TNF in vitro. Several chemokine mRNAs and proteins were expressed in response to LTβR signaling. Importantly, in a murine lupus model, LTβR 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 LTβR signaling is involved in renal injury and may be a suitable therapeutic target in renal diseases.

Inhibition of Sodium-Glucose Cotransporter 2 with Dapagliflozin in Han: SPRD Rats with Polycystic Kidney Disease

BACKGROUND/AIMS

Dapagliflozin (DAPA) is a selective inhibitor of the sodium-glucose cotransporter 2 (SGLT2) which induces glucosuria and osmotic diuresis. The therapeutic effect of DAPA in progressing stages of polycystic kidney disease (PKD) has not been studied.

METHODS

We examined the effect of DAPA in the Han: SPRD rat model of PKD. DAPA (10 mg/kg/day) or vehicle (VEH) was administered orally via gavage to 5 week old male Han: SPRD (Cy/+) or control (+/+) rats (n = 8-9 per group) for 5 weeks. Blood and urine were collected at baseline and after 2.5 and 5 weeks of treatment to assess renal function and albuminuria. At the end of the treatment, rats were sacrificed and kidneys were excised for histological analysis.

RESULTS

After 5 weeks of treatment, DAPA-treated Cy/+ and +/+ rats exhibited significantly higher glucosuria, water intake and urine output than VEH-treated rats. DAPA-treated Cy/+ rats also exhibited significantly higher clearances for creatinine and BUN and less albuminuria than VEH-treated Cy/+ rats. DAPA treatment for 5 weeks resulted in a significant increase of the kidney weight in Cy/+ rats but no change in cyst growth. The degree of tubular epithelial cell proliferation, macrophage infiltration and interstitial fibrosis was also similar in DAPA-and VEH-treated Cy/+ rats.

CONCLUSION

The induction of glucosuria with the SGLT2-specific inhibitor DAPA was associated with improved renal function and decreased albuminuria, but had no effect on cyst growth in Cy/+ rats. Overall the beneficial effects of DAPA in this PKD model were weaker than the previously described effects of the combined SGLT1/2 inhibitor phlorizin.

Puumala Hantavirus-Induced Hemorrhagic Fever with Renal Syndrome Must Be Considered across the Borders of Nephrology to Avoid Unnecessary Diagnostic Procedures

Background

Nephropathia epidemica (NE), a milder form of hemorrhagic fever with renal syndrome, is caused by Puumala virus and is characterized by acute kidney injury and thrombocytopenia.

Methods

A cross-sectional prospective survey of 456 adult patients with serologically confirmed NE was performed.

Results

Of the 456 investigated patients, 335 had received inpatient treatment. At time of admission to hospital, 72% of the patients had still an AKI and thrombocytopenia was present in 64% of the patients. The 335 patients were treated in 29 different hospitals and 6 of which had nephrology departments. 10 out of 335 patients received treatment in university hospitals and 63% of patients admitted themselves to hospital. Initially, the patients were admitted to 12 different clinical departments (29% of the patients were referred to a nephrology department) and during the course of the disease, 8% of the patients were transferred to another department in the same hospital and 3% were transferred to a nephrology department at another hospital. Regarding diagnostic procedures, in 28% of the inpatients computed tomography to exclude pulmonary embolism or due to severe gastrointestinal symptoms, lumbar puncture to exclude meningitis, magnetic resonance tomography of the brain owing to suspected stroke because of visual disorders, gastroscopy, or colonoscopy due to gastrointestinal symptoms was performed at time of admission to hospital.

Conclusions

NE must be considered by physicians across the borders of nephrology to avoid unnecessary diagnostic procedures especially in areas where NE is endemic.

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

The consequences of associated hematuria may be long-lasting, and hantavirus IgG is detectable years after acute infection.

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.

C-reactive protein levels in combination with abdominal CT scans is a useful tool to predict the macroscopic appearance in late-stage EPS patients prior to surgery

Background

Diagnosis of encapsulating peritoneal sclerosis (EPS) is based on clinical symptoms, radiologic findings, and macroscopic or histological criteria. Two diagnostic scores for radiologic findings in computed tomography (CT) scans of patients with EPS have been established in the past (by Tarzi et al and Vlijm et al). The macroscopic appearance of EPS has previously been separated into three types. The use of CT scan as a tool to predict different macroscopic phenotypes, leading to specific surgical techniques and different medical treatment, has not yet been investigated.

Methods

We retrospectively analyzed 30 patients with late-stage EPS who underwent major surgery with peritonectomy and enterolysis. The preoperative CT scans were scored according to the two aforementioned established diagnostic CT scores. The macroscopic phenotype, surgical procedure, and laboratory values at the time of surgery were evaluated. CT findings in the different macroscopic phenotypes were analyzed.

Results

All patients had highly predictive CT scores for EPS. The macroscopic Type III had significantly higher CT scores compared with the other macroscopic phenotypes. Patients with macroscopic Type I had significantly higher C-reactive protein values compared to EPS Type III. Operation time was significantly longer, and repeated surgery and intraoperative complications were more frequent in EPS Type I compared with EPS Type III (P<0.05). Using the CT score and CRP level, the sensitivities for prediction of EPS I and III were 78% and 87% with corresponding specificities of 67% and 93%.

Conclusion

Abdominal CT scans might help to identify patients with a higher risk of complications and provide important information for the surgical intervention prior to surgery.

An infectious cause of acute kidney injury with low serum potassium

A 67-year-old man was referred to our hospital because of acute kidney injury, thrombocytopenia and hyperbilirubinemia. Despite severe kidney failure, hypokalemia was present. One infectious cause explained the whole clinical picture.

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.

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.

Effect of Sodium-Glucose Cotransport Inhibition on Polycystic Kidney Disease Progression in PCK Rats

The sodium-glucose-cotransporter-2 (SGLT2) inhibitor dapagliflozin (DAPA) induces glucosuria and osmotic diuresis via inhibition of renal glucose reabsorption. Since increased diuresis retards the progression of polycystic kidney disease (PKD), we investigated the effect of DAPA in the PCK rat model of PKD. DAPA (10 mg/kg/d) or vehicle was administered by gavage to 6 week old male PCK rats (n=9 per group). Renal function, albuminuria, kidney weight and cyst volume were assessed after 6 weeks of treatment. Treatment with DAPA markedly increased glucose excretion (23.6 ± 4.3 vs 0.3 ± 0.1 mmol/d) and urine output (57.3 ± 6.8 vs 19.3 ± 0.8 ml/d). DAPA-treated PCK rats had higher clearances for creatinine (3.1 ± 0.1 vs 2.6 ± 0.2 ml/min) and BUN (1.7 ± 0.1 vs 1.2 ± 0.1 ml/min) after 3 weeks, and developed a 4-fold increase in albuminuria. Ultrasound imaging and histological analysis revealed a higher cyst volume and a 23% higher total kidney weight after 6 weeks of DAPA treatment. At week 6 the renal cAMP content was similar between DAPA and vehicle, and staining for Ki67 did not reveal an increase in cell proliferation. In conclusion, the inhibition of glucose reabsorption with the SGLT2-specific inhibitor DAPA caused osmotic diuresis, hyperfiltration, albuminuria and an increase in cyst volume in PCK rats. The mechanisms which link glucosuria to hyperfiltration, albuminuria and enhanced cyst volume in PCK rats remain to be elucidated.

Determination of procalcitonin levels in patients with nephropathia epidemica - a useful tool or an unnecessary diagnostic procedure?

BACKGROUND/AIMS

Puumala virus causes nephropathia epidemica (NE), a milder form of hemorrhagic fever with renal syndrome that occurs in Central and Northern Europe. Several studies have sought to identify risk factors for severe NE. However, elevated procalcitonin (PCT) levels have not previously been investigated as a predictive marker for a severe course of NE.

METHODS

A cross-sectional prospective survey of 456 adults with serologically confirmed NE was performed.

RESULTS

PCT levels at the time of diagnosis were available for 43 out of 456 patients, and in 24 of these patients (56%) PCT levels were elevated ("PCT positive"). C-reactive protein (CRP) levels at admission to hospital and peak CRP levels during the acute course of the disease were higher in the PCT-positive compared with the PCT-negative group (p<0.05). Severe acute kidney injury (AKI) (RIFLE I and F) was present in similar numbers of PCT-positive and -negative patients (p=0.7), but antibiotics were more frequently used in the PCT-positive than the PCT-negative group (p<0.05). Within the PCT-positive group, PCT levels were similar among those receiving and not receiving antibiotics (p=0.13), and neither the duration of hospital stay nor CRP peak levels were lower in those treated with antibiotics (p=0.12 and p=0.13, respectively).

CONCLUSIONS

Elevated PCT levels are common in patients with acute NE. There was no association between PCT levels and severity of disease, including AKI or thrombocytopenia. It is important to distinguish Puumala virus infection from other causes of AKI with thrombocytopenia. However, PCT might not be useful in differentiating hantavirus infection from bacterial infection.

Polyuria in Hantavirus Infection Reflects Disease Severity and Is Associated with Prolonged Hospital Stay: A Systematic Analysis of 335 Patients from Southern Germany

Background/Aims: Puumala virus (PUUV) infection leads to nephropathia epidemica (NE), especially in endemic areas in Central Europe. The clinical course of NE is characterized by acute kidney injury (AKI) with thrombocytopenia followed by polyuria to a different degree. The prevalence of polyuria and its associated risk factors have not been reported in a large cohort of NE patients. Methods: Clinical and laboratory data during the acute phase of the disease were obtained from the medical reports and files of 335 patients who received in-hospital treatment during acute hantavirus infection. Comprehensive statistical models were developed to estimate the probability of polyuria. Results: The median age at diagnosis was 47 years (interquartile range, IQR 40-59) and 48% of the patients developed polyuria with a urinary output of 5,100 ml/day (IQR 4,200-7,300). The hospital stay was significantly longer in the polyuric group compared to the nonpolyuric group [8 days (IQR 6-10) vs. 6 days (IQR 5-8); p = 0.04]. Using logistic regression analysis, male gender (odds ratio, OR = 1.6; 95% confidence interval, CI 1.05-2.58; p = 0.03), oliguria/anuria during NE (OR = 2.56; 95% CI 1.65-4.01; p < 0.001), severe AKI (OR = 1.87; 95% CI 1.22-2.9; p < 0.001), and hematuria (OR = 1.78; 95% CI 1.02-3.15; p = 0.04) were significantly associated with the development of polyuria. In a multivariate model, the probability of polyuria was 0.19 (SEM ± 0.05) in female patients presenting with mild/moderate AKI without anuria/oliguria. Conclusions: Almost 50% of hospitalized NE patients developed polyuria, which was associated with a prolonged hospital stay. The probability of the development of polyuria was lowest in female patients with mild/moderate, non-oliguric/anuric AKI. © 2014 S. Karger AG, Basel.

Platelet-derived growth factor receptor-β expression in human peritoneum

INTRODUCTION

Simple peritoneal fibrosis and encapsulating peritoneal sclerosis (EPS) are important lesions in the peritoneum of patients on peritoneal dialysis (PD). We have previously described a population of podoplanin-positive myofibroblasts in peritoneal biopsies from patients with EPS. Platelet-derived growth factor receptor-β (PDGFRβ) is a marker of pericytes, and PDGFs might be involved in the fibrotic response of the peritoneum. This study aimed to describe PDGFRβ in the human peritoneum.

METHODS

In this retrospective analysis, we localized PDGFRβ in peritoneal biopsies from patients with EPS (n = 6) and patients on PD without signs of EPS (n = 5), and compared them with normal peritoneum (n = 4) and peritoneum from uremic patients (n = 5). Consecutive sections were stained for smooth-muscle actin (SMA) and podoplanin. Slides were scored semiquantitatively by 2 observers blinded to the diagnosis.

RESULTS

PDGFRβ was expressed by cells of arterial walls in all biopsies. A prominent population of PDGFRβ-positive cells was present in the normal peritoneum, which were SMA negative on consecutive sections. In patients on PD, a high number of PDGFRβ were also positive for SMA. In EPS, the majority of podoplanin-positive cells were positive for PDGFRβ. In peritoneal biopsies from normal and uremic patients, the expression of SMA was mainly restricted to cells of arterial walls. Podoplanin expression was restricted to lymphatic vessels in normal peritoneum, in uremic patients, and in patients on PD without EPS.

CONCLUSIONS

As podoplanin-positive myofibroblasts express PDGFRβ, these cells might be related to pericytes (rather than other sources of fibroblasts). PDGFRβ might turn out to be a therapeutic target in EPS.

Acute effects of haemodialysis on central venous and arterial pressure characteristics

AIM

Haemodynamic stability of patients during haemodialysis (HD) sessions is of pivotal importance and accurate determination of dry weight remains a challenge. Little information is available about central venous and aortic pressure during dialysis. In this pilot study we used a non-invasive technique to describe the changes in central venous pressure (CVP) during dialysis.

METHODS

An ultrasound-assisted pressure-manometer was used at the cephalic vein during haemodialysis to quantify CVP. Central aortic pressure changes were assessed as aortic augmentation index and subendocardial viability ratio. Bioimpedance was applied to measure total body water, as well as extracellular and intracellular water before and after HD. Measurements were performed prior during and after 1 and 2 h on HD.

RESULTS

Ten patients were included with a median age of 72 years (23-82). Haemodialysis reduced the weight by 2.0 kg, corresponding to a measured decrease in total body water of 1.9 L. The mean CVP showed a significant decrease (9.0-0.8 cmH₂O; P = 0.0005) during dialysis. The significant drop in CVP was found during the first hour (9-2.8 cmH₂O). Starting and stopping dialysis was reflected by a reduction of 2.6 cmH₂O and a rise of 2.8 cmH₂O (n.s.). Aortic augmentation index decreased from 26.1% to 21.0% (n.s.). Subendocardial viability ratio increased from 126% to 156% (P < 0.05) during HD, and decreased to 139% direct after HD (n.s.).

CONCLUSION

This is the first study that illustrates a prominent reduction of CVP during the first hour of haemodialysis. Non-invasive CVP measurement is feasible during haemodialysis and adds another piece in the puzzle of factors involved in haemodynamic stability.