non-invasive-imaging-acute-allograft-rejection-after-rat-renal

Non-invasive Imaging of Acute Allograft Rejection after Rat Renal Transplantation Using <sup>18</sup>F-FDG PET

The number of patients with end-stage renal  disease, and the number of kidney allograft recipients continuously increases.  Episodes of acute cellular ...

induction-an-inflammatory-response-primary-hepatocyte-cultures-from

Induction of an Inflammatory Response in Primary Hepatocyte Cultures from Mice

The liver plays a decisive role in the regulation of systemic inflammation. In chronic kidney disease in particular, the liver reacts in response to the ...

Kidney transplantation (RTx) leads to amelioration of endothelial function in patients with advanced renal failure. Endothelial progenitor cells (EPCs) may play a key role in this repair process. The aim of this study was to determine the impact of RTx and immunosuppressive therapy on the number of circulating EPCs.

Circulating endothelial progenitor cells in kidney transplant patients.

Nierentransplantation (RTx) f&uuml;hrt zur Verbesserung der endothelialen Funktion bei Patienten mit fortgeschrittenen Nierenversagen. Endothelial Progenitor Cells (EPCs) k&ouml;nnen in diesem Reparaturprozess eine Schl&uuml;sselrolle spielen. Ziel dieser Studie war die Auswirkung der RTx und immunsuppressive Therapie auf die Anzahl der zirkulierenden EPC bestimmen.

Zirkulierenden endothelialen Vorl&auml;uferzellen in Niere transplant Patienten.

Renal ischemia-reperfusion (IR) injury (IRI) is a common and important trigger of acute renal injury (AKI). It is inevitably linked to transplantation. Involving both, the innate and the adaptive immune response, IRI causes subsequent sterile inflammation. Attraction to and transmigration of immune cells into the interstitium is associated with increased vascular permeability and loss of endothelial and tubular epithelial cell integrity. Considering the important role of cytoskeletal reorganization, mainly regulated by RhoGTPases, in the development of IRI we hypothesized that a preventive, selective inhibition of the Rho effector Rho-associated coiled coil containing protein kinase (ROCK) by hydroxyfasudil may improve renal IRI outcome. Using an IRI-based animal model of AKI in male Sprague Dawley rats, animals treated with hydroxyfasudil showed reduced proteinuria and polyuria as well as increased urine osmolarity when compared with sham-treated animals. In addition, renal perfusion (as assessed by (18)F-fluoride Positron Emission Tomography (PET)), creatinine- and urea-clearances improved significantly. Moreover, endothelial leakage and renal inflammation was significantly reduced as determined by histology, (18)F-fluordesoxyglucose-microautoradiography, Evans Blue, and real-time PCR analysis. We conclude from our study that ROCK-inhibition by hydroxyfasudil significantly improves kidney function in a rat model of acute renal IRI and is therefore a potential new therapeutic option in humans.

Hydroxyfasudil-mediated inhibition of ROCK1 and ROCK2 improves kidney function in rat renal acute ischemia-reperfusion injury.

Renale Isch&auml;mie-Reperfusion (IR) Verletzung (IRI) ist eine h&auml;ufige und wichtige Trigger akute renale Sch&auml;digung (AKI). Es wird unweigerlich bis zur Transplantation verbunden. Bei denen sowohl die angeborene und adaptive Immunantwort, verursacht IRI nachfolgende sterilen Entz&uuml;ndung. Anziehungskraft und Seelenwanderung von Immunzellen in das Interstitium ist erh&ouml;hte vaskul&auml;re Permeabilit&auml;t und Verlust der Integrit&auml;t der endothelial und tubul&auml;re Epithelzellen zugeordnet. In Anbetracht der wichtigen Rolle der Zytoskelett Reorganisation, haupts&auml;chlich durch RhoGTPases geregelt, in der Entwicklung von IRI vermutet wir, dass eine vorbeugende, selektive Hemmung der der Rho Effektor Rho-assoziierte Spulengebiet enthaltenden Proteinkinase (ROCK) von Hydroxyfasudil renale IRI-Ergebnis verbessern kann. Mit IRI-basierte Tiermodell aki bei m&auml;nnlichen Sprague-Dawley Ratten, Tiere, behandelt mit Hydroxyfasudil zeigte verminderte Proteinurie und Polyurie sowie erh&ouml;hte Urin-Osmolarit&auml;t Schein-behandelten Tieren gegen&uuml;ber. Dar&uuml;ber hinaus die renale Perfusion (als beurteilt (18) F-Fluorid Positronen-Emissions-Tomographie (PET)), Kreatinin und Harnstoff-Freigaben deutlich verbessert. Dar&uuml;ber hinaus endothelial Leckage und renalen Entz&uuml;ndung war deutlich reduziert durch Histologie, F-Fluordesoxyglucose-Microautoradiography (18), Evans Blue und Echtzeit-PCR-Analyse bestimmt. Wir schlie&szlig;en unsere Studie, dass ROCK-Hemmung von Hydroxyfasudil erheblich verbessert die Nierenfunktion in einem Rattenmodell f&uuml;r akute renale IRI und daher eine m&ouml;gliche neue Therapieoption beim Menschen ist.

Hydroxyfasudil-vermittelte Hemmung der ROCK1 und ROCK2 verbessert die Nierenfunktion Ratte renale akute Isch&auml;mie-Reperfusion Verletzungen.

Chronic kidney disease is directly associated with cardiovascular complications. Heart remodelling, including fibrosis, hypertrophy, and decreased vascularization, is frequently present in renal diseases. Our objective was to investigate the impact of calcineurin inhibitors (CNI) on cardiac remodelling and function in a rat model of renal disease.

Cardioprotective effect of calcineurin inhibition in an animal model of renal disease.

Chronischer Nierenerkrankung ist direkt verbunden mit Herz-Kreislauf-Komplikationen. Herz Umbau, ist einschlie&szlig;lich Fibrose, Hypertrophie und verminderte Vaskularisierung, h&auml;ufig in Nierenkrankheiten vorhanden. Unser Ziel war es, die Auswirkungen der Calcineurin-Inhibitoren (CNI) auf kardiale Umbau und Funktion in einem Rattenmodell f&uuml;r Nierenerkrankung zu untersuchen.

Kardioprotektive Wirkung von Calcineurin-Hemmung in einem Tiermodell der Nierenerkrankung.

Human organic cation transporter 2 (hOCT2) is involved in transport of many endogenous and exogenous organic cations, mainly in kidney and brain cells. Because the quaternary structure of transmembrane proteins plays an essential role for their cellular trafficking and function, we investigated whether hOCT2 forms oligomeric complexes, and if so, which part of the transporter is involved in the oligomerization. A yeast 2-hybrid mating-based split-ubiquitin system (mbSUS), fluorescence resonance energy transfer, Western blot analysis, cross-linking experiments, immunofluorescence, and uptake measurements of the fluorescent organic cation 4-(4-(dimethylamino)styryl)-N-methylpyridinium were applied to human embryonic kidney 293 (HEK293) cells transfected with hOCT2 and partly also to freshly isolated human proximal tubules. The role of cysteines for oligomerization and trafficking of the transporter to the plasma membranes was investigated in cysteine mutants of hOCT2. hOCT2 formed oligomers both in the HEK293 expression system and in native human kidneys. The cysteines of the large extracellular loop are important to enable correct folding, oligomeric assembly, and plasma membrane insertion of hOCT2. Mutation of the first and the last cysteines of the loop at positions 51 and 143 abolished oligomer formation. Thus, the cysteines of the extracellular loop are important for correct trafficking of the transporter to the plasma membrane and for its oligomerization.

The cysteines of the extracellular loop are crucial for trafficking of human organic cation transporter 2 to the plasma membrane and are involved in oligomerization.

The number of patients necessitating treatment for end-stage organ failure, and therefore, the number of allograft recipients, increases. Despite the introduction of new and effective immunosuppressive drugs, acute cellular graft rejection (AR) is still a major risk for graft survival. Hence, early detection and treatment of AR is crucial to limit the inflammatory process and preserve the function of the transplant. Nowadays, AR can only be definitively diagnosed by biopsy. As an invasive procedure, biopsy carries the risk of significant graft injury and is not feasible in patients taking anticoagulant medication. Moreover, limited sampling site (randomly taken exceedingly small portions of tissue) may lead to false negative results, i.e., when rejection is focal or patchy. Thus, in diagnostics, entirely image-based methods would be superior. As AR is characterized by recruitment of activated leukocytes into the transplant several diagnostic strategies exist. We herein review the current approaches (experimental and clinical scenarios with a special focus on renal AR) in noninvasive molecular imaging-based diagnostics of acute AR using either single photon (gamma) imaging or positron emission tomography.

Strategies for non-invasive molecular imaging of acute allograft rejection by gamma scintigraphy and positron emission tomography.

Erh&ouml;ht sich die Zahl der Patienten, die Behandlung von terminaler Organversagen und daher die Anzahl der Allograft Empf&auml;nger, erfordern. Trotz der Einf&uuml;hrung neuer und wirksamer Immunsuppressiva ist akute zellul&auml;re Transplantat Ablehnung (AR) immer noch ein gro&szlig;es Risiko f&uuml;r das Transplantat-&uuml;berleben. Fr&uuml;herkennung und Behandlung von AR ist entscheidend f&uuml;r den Entz&uuml;ndungsprozess zu begrenzen und die Funktion der Transplantation zu erhalten. Heutzutage kann AR endg&uuml;ltig nur durch Biopsie diagnostiziert werden. Als ein invasives Verfahren Biopsie tr&auml;gt das Risiko der erheblichen Transplantat Verletzungen und ist nicht m&ouml;glich bei Patienten, die gerinnungshemmende Medikamente. Dar&uuml;ber hinaus kann begrenzte Stichproben-Website (nach dem Zufallsprinzip genommen &uuml;beraus kleine Portionen von Gewebe) zu falsch negative Ergebnisse, d.h. f&uuml;hren Ablehnung fokale oder l&uuml;ckenhaft ist. Somit w&uuml;rde komplett Image-basierte Methoden in der Diagnostik, &uuml;berlegen sein. Wie AR durch Rekrutierung von Gewebsreaktionen in der Transplantation gekennzeichnet ist gibt es mehrere diagnostische Strategien. Hier &uuml;berpr&uuml;fen wir die aktuellen Ans&auml;tze (experimentelle und klinische Szenarien mit besonderem Schwerpunkt auf renale AR) in der nichtinvasiven Bildgebung-basierte Molekulardiagnostik akute AR mit single-Photon (Gamma) Bildgebung oder Positronen-Emissions-Tomographie.

Strategien zur nicht-invasiven Molekulare Bildgebung der akuten Allograft Ablehnung durch Gamma-Szintigraphie und Positronen-Emissions-Tomographie.

We proposed small-animal PET with (18)F-FDG-labeled T lymphocytes as a new method for image-based diagnosis of acute allogeneic renal transplant rejection (AR) established in a rat model.

PET with 18F-FDG-labeled T lymphocytes for diagnosis of acute rat renal allograft rejection.

The endothelial glycocalyx (eGC), a mesh of anionic biopolymers covering the luminal surface of endothelial cells, is considered as an intravascular compartment that protects the vessel wall against pathogenic insults in cardiovascular disease. We hypothesized that chronic kidney disease (CKD) is associated with reduced eGC integrity and subsequent endothelial dysfunction.

Damage of the endothelial glycocalyx in chronic kidney disease.

Molecular imaging techniques such as single photon emission computed tomography (SPECT) or positron emission tomography are promising tools for noninvasive diagnosis of acute allograft rejection (AR). Given the importance of renal transplantation and the limitation of available donors, detailed analysis of factors that affect transplant survival is important. Episodes of acute allograft rejection are a negative prognostic factor for long-term graft survival. Invasive core needle biopsies are still the "goldstandard" in rejection diagnostics. Nevertheless, they are cumbersome to the patient and carry the risk of significant graft injury. Notably, they cannot be performed on patients taking anticoagulant drugs. Therefore, a noninvasive tool assessing the whole organ for specific and fast detection of acute allograft rejection is desirable. We herein review SPECT- and PET-based approaches for noninvasive molecular imaging-based diagnostics of acute transplant rejection.

SPECT- and PET-based approaches for noninvasive diagnosis of acute renal allograft rejection.

Activation of fibroblast growth factor receptor (FGFR)-dependent signalling by FGF23 may contribute to the complex pathogenesis of left ventricular hypertrophy (LVH) in chronic kidney disease (CKD). Pan FGFR blockade by PD173074 prevented development of LVH in the 5/6 nephrectomy rat model of CKD, but its ability to treat and reverse established LVH is unknown.

Treatment of established left ventricular hypertrophy with fibroblast growth factor receptor blockade in an animal model of CKD.

Chronic kidney disease (CKD) is a worldwide public health threat that increases risk of death due to cardiovascular complications, including left ventricular hypertrophy (LVH). Novel therapeutic targets are needed to design treatments to alleviate the cardiovascular burden of CKD. Previously, we demonstrated that circulating concentrations of fibroblast growth factor (FGF) 23 rise progressively in CKD and induce LVH through an unknown FGF receptor (FGFR)-dependent mechanism. Here, we report that FGF23 exclusively activates FGFR4 on cardiac myocytes to stimulate phospholipase Cγ/calcineurin/nuclear factor of activated T cell signaling. A specific FGFR4-blocking antibody inhibits FGF23-induced hypertrophy of isolated cardiac myocytes and attenuates LVH in rats with CKD. Mice lacking FGFR4 do not develop LVH in response to elevated FGF23, whereas knockin mice carrying an FGFR4 gain-of-function mutation spontaneously develop LVH. Thus, FGF23 promotes LVH by activating FGFR4, thereby establishing FGFR4 as a pharmacological target for reducing cardiovascular risk in CKD.

Activation of Cardiac Fibroblast Growth Factor Receptor 4 Causes Left Ventricular Hypertrophy.

In chronic kidney disease (CKD), multiple factors contribute to the development of cardiac hypertrophy by directly targeting the heart or indirectly by inducing systemic changes such as hypertension, anemia, and inflammation. Furthermore, disturbances in phosphate metabolism have been identified as nonclassical risk factors for cardiovascular mortality in these patients. With declining kidney function, the physiologic regulators of phosphate homeostasis undergo changes in their activity as well as their circulating levels, thus potentially contributing to cardiac hypertrophy once they are out of balance. Recently, two of these phosphate regulators, fibroblast growth factor 23 (FGF23) and Klotho, have been shown to affect cardiac remodeling, thereby unveiling a novel pathomechanism of cardiac hypertrophy in CKD. Here we discuss the potential direct versus indirect effects of FGF23 and the soluble form of Klotho on the heart, and their crosstalk in the regulation of cardiac hypertrophy.

The role of fibroblast growth factor 23 and Klotho in uremic cardiomyopathy.

Patients with chronic kidney disease (CKD) develop increased levels of the phosphate-regulating hormone, fibroblast growth factor (FGF) 23, that are associated with a higher risk of mortality. Increases in inflammatory markers are another common feature that predicts poor clinical outcomes. Elevated FGF23 is associated with higher circulating levels of inflammatory cytokines in CKD, which can stimulate osteocyte production of FGF23. Here, we studied whether FGF23 can directly stimulate hepatic production of inflammatory cytokines in the absence of α-klotho, an FGF23 coreceptor in the kidney that is not expressed by hepatocytes. By activating FGF receptor isoform 4 (FGFR4), FGF23 stimulated calcineurin signaling in cultured hepatocytes, which increased the expression and secretion of inflammatory cytokines, including C-reactive protein. Elevating serum FGF23 levels increased hepatic and circulating levels of C-reactive protein in wild-type mice, but not in FGFR4 knockout mice. Administration of an isoform-specific FGFR4 blocking antibody reduced hepatic and circulating levels of C-reactive protein in the 5/6 nephrectomy rat model of CKD. Thus, FGF23 can directly stimulate hepatic secretion of inflammatory cytokines. Our findings indicate a novel mechanism of chronic inflammation in patients with CKD and suggest that FGFR4 blockade might have therapeutic anti-inflammatory effects in CKD.

Fibroblast growth factor 23 directly targets hepatocytes to promote inflammation in chronic kidney disease.

CD63 is a ubiquitously expressed member of the tetraspanin superfamily. Using a mating-based split-ubiquitin-yeast 2-hybrid system, pull-down experiments, total internal reflection fluorescence microscopy, Förster resonance energy transfer, and biotinylation assays, we found that CD63 interacts with human organic cation transporter 2 (hOCT2), which transports endogenous and exogenous substrates, such as neurotransmitters and drugs in several epithelial cells. CD63 overexpression affects cellular localization of hOCT2 expressed in human embryonic kidney (HEK)293 cells. Studies with CD63 knockout mice indicate that in renal proximal tubules, CD63 determines the insertion of the mouse ortholog of the transporter into the proper membrane domain and mediates transporter regulation by trafficking processes. In polarized Madin-Darby kidney canine kidney (MDCK) epithelial cells, CD63 and hOCT2 colocalize with the small GTPase Rab4, which controls the rapid recycling from sorting endosomes back to the cell surface. Suitable negative and positive control experiments were performed for each experimental approach. Empty vector transfected cells and wild-type mice were used as control. CD63 seems to play a role in the recycling of hOCT2 from endosomes to the basolateral membrane in polarized epithelia. These data indicate that CD63 has a previously uncharacterized function in regulating trafficking of specific membrane proteins in polarized cells.-Schulze, U., Brast, S., Grabner, A., Albiker, C., Snieder, B., Holle, S., Schlatter, E., Schröter, R., Pavenstädt, H., Herrmann, E., Lambert, C., Spoden, G. A., Florin, L., Saftig, P., Ciarimboli, G. Tetraspanin CD63 controls basolateral sorting of organic cation transporter 2 in renal proximal tubules.

ArticleTotal : 2	Year
Publication title Cited by 12	2013
Publication title Cited by 7	2017

Article	Year
Circulating endothelial progenitor cells in kidney transplant patients. PloS one\| PubMed ID: 21931640	2011
Hydroxyfasudil-mediated inhibition of ROCK1 and ROCK2 improves kidney function in rat renal acute ischemia-reperfusion injury. PloS one\| PubMed ID: 22031832	2011
Cardioprotective effect of calcineurin inhibition in an animal model of renal disease. European heart journal\| PubMed ID: 21138940	2011
The cysteines of the extracellular loop are crucial for trafficking of human organic cation transporter 2 to the plasma membrane and are involved in oligomerization. FASEB journal : official publication of the Federation of American Societies for Experimental Biology\| PubMed ID: 22085643	2012
Strategies for non-invasive molecular imaging of acute allograft rejection by gamma scintigraphy and positron emission tomography. Current radiopharmaceuticals\| PubMed ID: 22191611	2011
PET with 18F-FDG-labeled T lymphocytes for diagnosis of acute rat renal allograft rejection. Journal of nuclear medicine : official publication, Society of Nuclear Medicine\| PubMed ID: 23670903	2013
Damage of the endothelial glycocalyx in chronic kidney disease. Atherosclerosis\| PubMed ID: 24727235	2014
SPECT- and PET-based approaches for noninvasive diagnosis of acute renal allograft rejection. BioMed research international\| PubMed ID: 24804257	2014
Treatment of established left ventricular hypertrophy with fibroblast growth factor receptor blockade in an animal model of CKD. Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association\| PubMed ID: 24875663	2014
Activation of Cardiac Fibroblast Growth Factor Receptor 4 Causes Left Ventricular Hypertrophy. Cell metabolism\| PubMed ID: 26437603	2015
The role of fibroblast growth factor 23 and Klotho in uremic cardiomyopathy. Current opinion in nephrology and hypertension\| PubMed ID: 27219043	2016
Fibroblast growth factor 23 directly targets hepatocytes to promote inflammation in chronic kidney disease. Kidney international\| PubMed ID: 27457912	2016
Tetraspanin CD63 controls basolateral sorting of organic cation transporter 2 in renal proximal tubules. FASEB journal : official publication of the Federation of American Societies for Experimental Biology\| PubMed ID: 28031320	2016

Alexander Grabner

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