Gliflozins Have an Anti-Inflammatory Effect on Renal Proximal Tubular Epithelial Cells in a Diabetic and Inflammatory Microenvironment In Vitro.

Inflammation is intimately involved in the pathogenesis of diabetic kidney disease. Inhibition of SGLT-2 by a specific class of drugs, gliflozins, has been shown to reduce inflammation and attenuate the progression of diabetic nephropathy, in addition to its main effect of inhibiting renal glucose reabsorption. We used highly purified human renal proximal tubular epithelial cells (PTCs) as an in vitro model to study the cellular response to a diabetic (high glucose) and inflammatory (cytokines) microenvironment and the effect of gliflozins. In this context, we investigated the influence of SGLT-2 inhibition by empa- and dapagliflozin (500 nM) on the expression of pro-inflammatory factors (IL-1ß, IL-6, TNF-α, MCP-1, and ICAM-1). The results clearly indicate an anti-inflammatory effect of both gliflozins. Although induced expression of the four cytokines was only slightly attenuated, there was a clear effect on the expression of the adhesion molecule ICAM-1, a master regulator of cellular responses in inflammation and injury resolution. The induced expression of ICAM-1 mRNA was significantly reduced by approximately 13.5% by empagliflozin and also showed an inhibitory trend with dapagliflozin. However, induced ICAM-1 protein expression was significantly inhibited from 24.71 ± 1.0 ng/mL to 18.81 ± 3.9 (empagliflozin) and 19.62 ± 2.1 ng/mL (dapagliflozin). In conclusion, an additional anti-inflammatory effect of empa- and dapagliflozin in therapeutically observed concentrations was demonstrated in primary human PTCs in vitro.

Cardiac biomarkers in chronic kidney disease are independently associated with myocardial edema and diffuse fibrosis by cardiovascular magnetic resonance.

BACKGROUND: High sensitivity cardiac troponin T (hs-cTnT) and NT-pro-brain natriuretic peptide (NT-pro BNP) are often elevated in chronic kidney disease (CKD) and associated with both cardiovascular remodeling and outcome. Relationship between these biomarkers and quantitative imaging measures of myocardial fibrosis and edema by T1 and T2 mapping remains unknown. METHODS: Consecutive patients with established CKD and estimated glomerular filtration rate (eGFR) < 59 ml/min/1.73 m2 (n = 276) were compared to age/sex matched patients with eGFR ≥ 60 ml/min/1.73 m2 (n = 242) and healthy controls (n = 38). Comprehensive cardiovascular magnetic resonance (CMR) with native T1 and T2 mapping, myocardial ischemia and scar imaging was performed with venous sampling immediately prior to CMR. RESULTS: Patients with CKD showed significant cardiac remodeling in comparison with both healthy individuals and non-CKD patients, including a stepwise increase of native T1 and T2 (p < 0.001 between all CKD stages). Native T1 and T2 were the sole imaging markers independently associated with worsening CKD in patients [B = 0.125 (95% CI 0.022-0.235) and B = 0.272 (95% CI 0.164-0.374) with p = 0.019 and < 0.001 respectively]. At univariable analysis, both hs-cTnT and NT-pro BNP significantly correlated with native T1 and T2 in groups with eGFR 30-59 ml/min/1.73 m2 and eGFR < 29 ml/min/1.73 m2 groups, with associations being stronger at lower eGFR (NT-pro BNP (log transformed, lg10): native T1 r = 0.43 and r = 0.57, native T2 r = 0.39 and r = 0.48 respectively; log-transformed hs-cTnT(lg10): native T1 r = 0.23 and r = 0.43, native T2 r = 0.38 and r = 0.58 respectively, p < 0.001 for all, p < 0.05 for interaction). On multivariable analyses, we found independent associations of native T1 with NT-pro BNP [(B = 0.308 (95% CI 0.129-0.407), p < 0.001 and B = 0.334 (95% CI 0.154-0.660), p = 0.002 for eGFR 30-59 ml/min/1.73 m2 and eGFR < 29 ml/min/1.73 m2, respectively] and of T2 with hs-cTnT [B = 0.417 (95% CI 0.219-0.650), p < 0.001 for eGFR < 29 ml/min/1.73 m2]. CONCLUSIONS: We demonstrate independent associations between cardiac biomarkers with imaging markers of interstitial expansion, which are CKD-group specific. Our findings indicate the role of diffuse non-ischemic tissue processes, including excess of myocardial fluid in addition to diffuse fibrosis in CKD-related adverse remodeling.

Acute kidney injury after in-hospital cardiac arrest in a predominant internal medicine and cardiology patient population: incidence, risk factors, and impact on survival.

INTRODUCTION: Prognosis of survivors from cardiac arrest is generally poor. Acute kidney injury (AKI) is a common finding in these patients. In general, AKI is well characterized as a marker of adverse outcome. In-hospital cardiac arrest (IHCA) represents a special subset of cardiac arrest scenarios with differential predisposing factors and courses after the event, compared to out-of-hospital resuscitations. Data about AKI in survivors after in-hospital cardiac arrest are scarce. METHODS: In this study, we retrospectively analyzed patients after IHCA for incidence and risk factors of AKI and its prognostic impact on mortality. For inclusion in the analysis, patients had to survive at least 48 h after IHCA. RESULTS: A total of 238 IHCA events with successful resuscitation and survival beyond 48 h after the initial event were recorded. Of those, 89.9% were patients of internal medicine, and 10.1% of patients from surgery, neurology or other departments. In 120/238 patients (50.4%), AKI was diagnosed. In 28 patients (23.3%), transient or permanent renal replacement therapy had to be initiated. Male gender, preexisting chronic kidney disease and a non-shockable first ECG rhythm during resuscitation were significantly associated with a higher incidence of AKI in IHCA-survivors. In-hospital mortality in survivors from IHCA without AKI was 29.7%, and 60.8% in patients after IHCA who developed AKI (p < 0.01 between groups).By multivariate analysis, AKI after IHCA persisted as an independent predictor of in-hospital mortality (HR 3.7 (95% CI 2.14-6.33, p ≤ 0.01)). CONCLUSION: In this cohort of survivors from IHCA, AKI is a frequent finding, with adverse impact on outcome. Therefore, therapeutic strategies to prevent AKI in post-IHCA patients are warranted.

Kidney Inflammation, Injury and Regeneration 2020.

The kidneys play a vital role in the basic physiological functions of the body [...].

Characterization of Extracellular Vesicles from Preconditioned Human Adipose-Derived Stromal/Stem Cells.

Cell-free therapy using extracellular vesicles (EVs) from adipose-derived mesenchymal stromal/stem cells (ASCs) seems to be a safe and effective therapeutic option to support tissue and organ regeneration. The application of EVs requires particles with a maximum regenerative capability and hypoxic culture conditions as an in vitro preconditioning regimen has been shown to alter the molecular composition of released EVs. Nevertheless, the EV cargo after hypoxic preconditioning has not yet been comprehensively examined. The aim of the present study was the characterization of EVs from hypoxic preconditioned ASCs. We investigated the EV proteome and their effects on renal tubular epithelial cells in vitro. While no effect of hypoxia was observed on the number of released EVs and their protein content, the cargo of the proteins was altered. Proteomic analysis showed 41 increased or decreased proteins, 11 in a statistically significant manner. Furthermore, the uptake of EVs in epithelial cells and a positive effect on oxidative stress in vitro were observed. In conclusion, culture of ASCs under hypoxic conditions was demonstrated to be a promising in vitro preconditioning regimen, which alters the protein cargo and increases the anti-oxidative potential of EVs. These properties may provide new potential therapeutic options for regenerative medicine.

CD4+ T cell lymphopenia predicts mortality from Pneumocystis pneumonia in kidney transplant patients.

BACKGROUND: Pneumocystis jirovecii pneumonia (PcP) remains a life-threatening opportunistic infection after solid organ transplantation, even in the era of Pneumocystis prophylaxis. The association between risk of developing PcP and low CD4+ T cell counts has been well established. However, it is unknown whether lymphopenia in the context of post-renal transplant PcP increases the risk of mortality. METHODS: We carried out a retrospective analysis of a cohort of kidney transplant patients with PcP (n = 49) to determine the risk factors for mortality associated with PcP. We correlated clinical and demographic data with the outcome of the disease. For CD4+ T cell counts, we used the Wilcoxon rank sum test for in-hospital mortality and a Cox proportional-hazards regression model for 60-day mortality. RESULTS: In univariate analyses, high CRP, high neutrophils, CD4+ T cell lymphopenia, mechanical ventilation, and high acute kidney injury network stage were associated with in-hospital mortality following presentation with PcP. In a receiver-operator characteristic (ROC) analysis, an optimum cutoff of ≤200 CD4+ T cells/µL predicted in-hospital mortality, CD4+ T cell lymphopenia remained a risk factor in a Cox regression model. CONCLUSIONS: Low CD4+ T cell count in kidney transplant recipients is a biomarker for disease severity and a risk factor for in-hospital mortality following presentation with PcP.

Incidence, Risk Factors, and Outcome of Acute Kidney Injury in Neurocritical Care.

PURPOSE: Acute kidney injury (AKI) is a severe complication in medical and surgical intensive care units accounting for a high morbidity and mortality. Incidence, risk factors, and prognostic impact of this deleterious condition are well established in this setting. Data concerning the neurocritically ill patients is scarce. Therefore, aim of this study was to determine the incidence of AKI and elucidate risk factors in this special population. METHODS: Patients admitted to a specialized neurocritical care unit between 2005 and 2011 with a length of stay above 48 hours were analyzed retrospectively for incidence, cause, and outcome of AKI (AKI Network-stage ≥2). RESULTS: The study population comprised 681 neurocritically ill patients from a mixed neurosurgical and neurological intensive care unit. The prevalence of chronic kidney disease (CKD) was 8.4% (57/681). Overall incidence of AKI was 11.6% with 36 (45.6%) patients developing dialysis-requiring AKI. Sepsis was the main cause of AKI in nearly 50% of patients. Acute kidney injury and renal replacement therapy are independent predictors of worse outcome (hazard ratio [HR]: 3.704; 95% confidence interval [CI]: 1.867-7.350; P < .001; and HR: 2.848; CI: 1.301-6.325; P = .009). Chronic kidney disease was the strongest independent risk factor (odds ratio: 12.473; CI: 5.944-26.172; P < .001), whereas surgical intervention or contrast agents were not associated with AKI. CONCLUSIONS: Acute kidney injury in neurocritical care has a high incidence and is a crucial risk factor for mortality independently of the underlying neurocritical condition. Sepsis is the main cause of AKI in this setting. Therefore, careful prevention of infectious complications and considering CKD in treatment decisions may lower the incidence of AKI and hereby improve outcome in neurocritical care.

Kidney Inflammation, Injury and Regeneration.

Damage to kidney cells can occur due to a variety of ischemic and toxic insults and leads to inflammation and cell death, which can result in acute kidney injury (AKI) [...].

No Cytotoxic and Inflammatory Effects of Empagliflozin and Dapagliflozin on Primary Renal Proximal Tubular Epithelial Cells under Diabetic Conditions In Vitro.

Gliflozins are inhibitors of the renal proximal tubular sodium-glucose co-transporter-2 (SGLT-2), that inhibit reabsorption of urinary glucose and they are able to reduce hyperglycemia in patients with type 2 diabetes. A renoprotective function of gliflozins has been proven in diabetic nephropathy, but harmful side effects on the kidney have also been described. In the current project, primary highly purified human renal proximal tubular epithelial cells (PTCs) have been shown to express functional SGLT-2, and were used as an in vitro model to study possible cellular damage induced by two therapeutically used gliflozins: empagliflozin and dapagliflozin. Cell viability, proliferation, and cytotoxicity assays revealed that neither empagliflozin nor dapagliflozin induce effects in PTCs cultured in a hyperglycemic environment, or in co-medication with ramipril or hydro-chloro-thiazide. Oxidative stress was significantly lowered by dapagliflozin but not by empagliflozin. No effect of either inhibitor could be detected on mRNA and protein expression of the pro-inflammatory cytokine interleukin-6 and the renal injury markers KIM-1 and NGAL. In conclusion, empa- and dapagliflozin in therapeutic concentrations were shown to induce no direct cell injury in cultured primary renal PTCs in hyperglycemic conditions.

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

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

Lectin Affinity Plasmapheresis for Middle East Respiratory Syndrome-Coronavirus and Marburg Virus Glycoprotein Elimination.

BACKGROUND/AIMS: Middle East respiratory syndrome coronavirus (MERS-CoV) and Marburg virus (MARV) are among the World Health Organization's top 8 emerging pathogens. Both zoonoses share nonspecific early symptoms, a high lethality rate, and a reduced number of specific treatment options. Therefore, we evaluated extracorporeal virus and glycoprotein (GP) elimination by lectin affinity plasmapheresis (LAP). METHODS: For both MERS-CoV (pseudovirus) as well as MARV (GPs), 4 LAP devices (Mini Hemopurifiers, Aethlon Medical, San Diego, CA, USA) and 4 negative controls were tested. Samples were collected every 30 min and analyzed for reduction in virus infectivity by a flow cytometry-based infectivity assay (MERS-CoV) and in soluble GP content (MARV) by an immunoassay. RESULTS: The experiments show a time-dependent clearance of MERS-CoV of up to 80% within 3 h (pseudovirus). Up to 70% of MARV-soluble GPs were eliminated at the same time. Substantial saturation of the binding resins was detected within the first treatment hour. CONCLUSION: MERS-CoV (pseudovirus) and MARV soluble GPs are eliminated by LAP in vitro. Considering the high lethality and missing established treatment options, LAP should be evaluated in vivo. Especially early initiation, continuous therapy, and timed cartridge exchanges could be of importance.

How to Prevent Renal Cachexia? A Clinical Randomized Pilot Study Testing Oral Supplemental Nutrition in Hemodialysis Patients With and Without Human Immunodeficiency Virus Infection.

OBJECTIVE: End-stage renal disease associates with catabolism and sarcopenia. Hypothetically, peroral supplemental nutrition over 6 months prevents catabolism in hemodialysis patients. DESIGN: Prospective randomized pilot study (ClinicalTrials.gov Identifier: NCT00687050). SUBJECTS: Twenty-three hemodialysis patients (15 males and 7 females) with or without human immunodeficiency virus (HIV) infection of 2 ambulatory hemodialysis centers. INTERVENTION: HIV-positive hemodialysis patients (n = 7, Group 1) were started on supplemental nutrition drinks (250 kcal/day), HIV-negative hemodialysis patients (n = 16, Group 2) were randomized to supplemental nutrition drinks (250 kcal/day) or received none. MAIN OUTCOME MEASURES: Body impedance analysis, anthropometric measures, magnetic resonance imaging results for mid-iliopsoas muscle cross-sectional area and laboratory parameters including albumin, cytokines at baseline, and at 6 months follow-up. RESULTS: Seven patients in Group 1 (mean age: 50.6 ± 9.6 years) and 16 patients in Group 2 (mean age: 54.0 ± 13.3 years) were recruited. Serum creatinine (Group 1: 6.4 ± 3.0 mg/dL; Group 2: 10.7 ± 2.5 mg/dL; P < .01), Body impedance analysis-derived phase angle alpha (Group 1: 5.1 ± 1.2; Group 2: 6.9 ± 1.6; P < .01), mid-arm circumference (Group 1: 26.1 ± 1.3 cm; Group 2: 29.6 ± 2.4 cm; P < .01) were less in Group 1 versus Group 2 patients at baseline suggesting that HIV-positive hemodialysis patients had a poorer nutritional status at baseline. At 6-month follow-up, mortality was higher in Group 1 patients (29%) than in Group 2 patients (6%). There was no significant treatment effect on nutritional status in survivors of Group 1 or in the supplemental nutrition arm of Group 2 when compared with baseline or to untreated controls. CONCLUSIONS: A new oral supplemental nutrition over 6 months had no treatment effect in surviving HIV-positive hemodialysis patients or in maintenance hemodialysis patients without HIV infection. The limitations of this study were small study size and unexpected high mortality among HIV-positive hemodialysis patients.

Tracking of Adipose-Derived Mesenchymal Stromal/Stem Cells in a Model of Cisplatin-Induced Acute Kidney Injury: Comparison of Bioluminescence Imaging versus qRT-PCR.

Determining the cell fate and the distribution of mesenchymal stromal/stem cells (MSCs) after transplantation are essential parts of characterizing the mechanisms of action and biosafety profile of stem cell therapy. Many recent studies have shown that MSCs migrate into injured tissues, but are only detectable at extremely low frequencies. We investigated the cell fate of MSCs after transplantation in an acute kidney injury (AKI) mouse model using in vivo bioluminescence imaging (BLI) and subsequent verification of cell migration using quantitative real-time polymerase chain reaction (qRT-PCR). The AKI was induced by a single injection of cisplatin (8 or 12 mg/kg). One day later, adipose-derived mesenchymal stromal/stem cells isolated from luciferase transgenic mice (Luc⁺-mASCs, 5 × 105) were intravenously transplanted. Migration kinetics of the cells was monitored using BLI on day 1, 3, and 6, and finally via quantitative real-time PCR at the endpoint on day 6. Using BLI, infused Luc⁺-mASCs could only be detected in the lungs, but not in the kidneys. In contrast, PCR endpoint analysis revealed that Luc-specific mRNA could be detected in injured renal tissue; compared to the control group, the induction was 2.2-fold higher for the 8 mg/kg cisplatin group (p < 0.05), respectively 6.1-fold for the 12 mg/kg cisplatin group (p < 0.001). In conclusion, our study demonstrated that Luc-based real-time PCR rather than BLI is likely to be a better tool for cell tracking after transplantation in models such as cisplatin-induced AKI.

Effect of Different Preconditioning Regimens on the Expression Profile of Murine Adipose-Derived Stromal/Stem Cells.

Stem cell-based therapies require cells with a maximum regenerative capacity in order to support regeneration after tissue injury and organ failure. Optimization of this regenerative potential of mesenchymal stromal/stem cells (MSC) or their conditioned medium by in vitro preconditioning regimens are considered to be a promising strategy to improve the release of regenerative factors. In the present study, MSC were isolated from inguinal adipose tissue (mASC) from C57BL/6 mice, cultured, and characterized. Then, mASC were either preconditioned by incubation in a hypoxic environment (0.5% O2), or in normoxia in the presence of murine epidermal growth factor (EGF) or tumor necrosis factor α (TNFα) for 48 h. Protein expression was measured by a commercially available array. Selected factors were verified by PCR analysis. The expression of 83 out of 308 proteins (26.9%) assayed was found to be increased after preconditioning with TNFα, whereas the expression of 61 (19.8%) and 70 (22.7%) proteins was increased after incubation with EGF or in hypoxia, respectively. Furthermore, we showed the proliferation-promoting effects of the preconditioned culture supernatants on injured epithelial cells in vitro. Our findings indicate that each preconditioning regimen tested induced an individual expression profile with a wide variety of factors, including several growth factors and cytokines, and therefore may enhance the regenerative potential of mASC for cell-based therapies.

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

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

Anatomy Revisited: Hemodialysis Catheter Malposition in the Left Ascending Lumbar Vein.

In selected cases, cuffed tunneled catheters via the iliac vein are implanted as a last resort access for hemodialysis. To monitor the correct position, sonography of the inferior vena cava (IVC) is sufficient in most cases. Position control using an X-ray of the abdomen is not routinely recommended when femoral catheters are implanted. In this report, we describe the case of a 59-year-old patient on chronic hemodialysis due to granulomatosis with polyangiitis and complex shunt history with multiple shunt occlusions and revisions. The implantation of an iliac-cuffed tunneled catheter led to complications because the catheter was malpositioned into the left ascending lumbar vein (ALV). It is important to be aware of potential incorrect positioning of dialysis catheters into the ALV. Due to the anatomical relation to the IVC, this happens more frequently on the left side than on the right side. In case of doubt, the correct placement of large-bore catheters via iliac access route should be verified by means of appropriate imaging before hemodialysis is performed.

Long-Term Therapy Outcomes When Treating Chronic Kidney Disease Patients with Paricalcitol in German and Austrian Clinical Practice (TOP Study).

Paricalcitol is approved for prevention and therapy of secondary hyperparathyroidism (sHPT) in patients with chronic kidney disease (CKD), with only short-term data in clinical routine settings. A 12-month observational study was conducted in Germany and Austria (90 centers, 761 patients) from 2008 to 2013. Laboratory values, demographical, and clinical data were documented in 629 dialysis patients and 119 predialysis patients. In predialysis patients, median intact parathormone (iPTH) was 180.0 pg/mL (n = 105) at the start of the study, 115.7 pg/mL (n = 105) at last documentation, and 151.8 pg/mL (n = 50) at month 12, with 32.4% of the last documented iPTH values in the KDOQI (Kidney Disease Outcomes Quality Initiative) target range. In dialysis patients, median iPTH was 425.5 pg/mL (n = 569) at study start, 262.3 pg/mL (n = 569) at last documentation, and 266.1 pg/mL (n = 318) at month 12, with 36.5% of dialysis patients in the KDOQI target range. Intravenous paricalcitol showed more homogenous iPTH control than oral treatment. Combined analysis of all dialysis patients indicated comparable and stable mean serum calcium and phosphate levels throughout the study. Clinical symptoms, such as itching, bone pain, and fatigue, were improved compared with study entry. The spectrum and frequency of adverse events mirrored the known pattern for patients on dialysis. Paricalcitol is efficacious and has a consistent safety profile in sHPT over 12 months.

Pretransplant human leukocyte antigen antibodies detected by single-antigen bead assay are a risk factor for long-term kidney graft loss even in the absence of donor-specific antibodies.

Clinical relevance of ELISA- and single-antigen bead assay (SAB)-detected pretransplant HLA antibodies (SAB-HLA-Ab) for kidney graft survival was evaluated retrospectively in 197 patients transplanted between 2002 and 2009 at the University Clinic Frankfurt. Having adjusted for retransplantation and delayed graft function, a significantly increased risk for death-censored graft loss was found in patients with pretransplant SAB-HLA-Ab [HR: 4.46; 95% confidence interval (CI): 1.47-13.48; P = 0.008]. The risk for increased graft loss was also significant in patients with pretransplant SAB-HLA-Ab but without SAB-detected donor-specific Ab (SAB-DSA) (HR: 4.91; 95% CI of 1.43-16.991; P = 0.012). ELISA was not sufficient to identify pretransplant immunized patients with an increased risk for graft loss. In immunized patients, graft loss was predominantly present in patients who received transplants with a mismatch on the HLA-DR locus. In conclusion, even if our study is limited due to small sample size, the results show an increased risk for long-term graft loss in patients with pretransplant SAB-HLA, even in the absence of DSA. SAB-HLA-Ab-positive patients, being negative in ELISA or CDC assay, might profit from a well-HLA-DR-matched graft and intensified immunosuppression.

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

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

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

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