Hannover, Germany
Hannover, Germany

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Rong S.,Hannover Medical School | Rong S.,Affiliated Hospital | Hueper K.,Hannover Medical School | Kirsch T.,Hannover Medical School | And 13 more authors.
American Journal of Physiology - Renal Physiology | Year: 2014

Acute kidney injury (AKI) increases the risk of morbidity and mortality after major surgery and transplantation. We investigated the effect of PKC-ε deficiency on AKI and ischemic allograft damage after kidney transplantation. PKC-ε-deficient and wild type (WT) control mice were subjected to 35 min of renal pedicle clamping to induce AKI. PKC-ε deficiency was associated with a marked improvement in survival and an attenuated loss of kidney function. Furthermore, functional MRI experiments revealed better renal perfusion in PKC-ε-deficient mice than in WT mice one day after IRI. Acute tubular necrosis and neutrophil infiltration were markedly reduced in PKC-ε-deficient mice. To determine whether this resistance to ischemia-reperfusion injury resulted from changes in local renal cells or infiltrating leukocytes, we studied a life-supporting renal transplant model of ischemic graft injury. We transplanted kidneys from H2b PKC-ε-deficient mice (129/SV) and their corresponding WT littermates into major histocompatibility complex-incompatible H2d recipients (BALB/c) and induced ischemic graft injury by prolonged cold ischemia time. Recipients of WT allografts developed severe renal failure and died within 10 days of transplantation. Recipients of PKC-ε-deficient allografts had better renal function and survival; they had less generation of ROS and upregulation of proinflammatory proteins (i.e., ICAM-1, inducible nitric oxide synthase, and TNF-α) and showed less tubular epithelial cell apoptosis and inflammation in their allografts. These data suggest that local renal PKC-ε expression mediates proapoptotic and proinflammatory signaling and that an inhibitor of PKC-ε signaling could be used to prevent hypoxia-induced AKI. © 2014 the American Physiological Society.


Lu X.,Tongji Hospital | Li N.,The Center Hospital of Wuhan | Shushakova N.,Hannover Medical School | Shushakova N.,Phenos GmbH | And 10 more authors.
Journal of Nephrology | Year: 2012

Background: C57BL/6 and 129/Sv are the 2 most commonly used strains of mice in renal ischemia-reperfusion injury (IRI) studies, yet there are currently no studies that contrast differences in the degree of renal injury after ischemia-reperfusion. Methods: To evaluate renal IRI in male C57BL/6 and 129/Sv mice, we performed unilateral clamping of the left renal pedicle for 45 minutes and compared the degree of renal tissue damage and function. To measure function and tissue damage we examined: glomerular filtration rate (GFR; by inulin clearance), renal blood flow (RBF; by p-aminohippurate [PAH] clearance), renal morphology, immunohistochemistry for infiltrating leukocytes, and fibrogenic markers by Sirius red staining. Results: After unilateral IRI, 129/sv mice had significantly less GFR and RBF disfunction at both day 14 (d14) and d28. 129/sv mice also had significantly less acute tubular necrosis on d1 and fewer infiltrating leukocytes on d28, as well as less collagen deposition on d28 than C57BL/6 mice. Conclusions: C57BL/6 mice were much more sensitive to damage caused by renal IRI than are 129/Sv mice. © 2011 Società Italiana di Nefrologia.


Gueler F.,Hannover Medical School | Shushakova N.,Hannover Medical School | Shushakova N.,Phenos GmbH | Mengel M.,University of Alberta | And 10 more authors.
PLoS ONE | Year: 2015

January Ischemia followed by reperfusion contributes to the initial damage to allografts after kidney transplantation (ktx). In this study we tested the hypothesis that a tetrapeptide EA-230 (AQGV), might improve survival and attenuate loss of kidney function in a mouse model of renal ischemia/reperfusion injury (IRI) and ischemia-induced delayed graft function after allogenic kidney transplantation. IRI was induced in male C57Bl/6N mice by transient bilateral renal pedicle clamping for 35 min. Treatment with EA-230 (20-50mg/kg twice daily i.p. for four consecutive days) was initiated 24 hours after IRI when acute kidney injury (AKI) was already established. The treatment resulted in markedly improved survival in a dose dependent manner. Acute tubular injury two days after IRI was diminished and tubular epithelial cell proliferation was significantly enhanced by EA-230 treatment. Furthermore, CTGF upregulation, a marker of post-ischemic fibrosis, at four weeks after IRI was significantly less in EA-230 treated renal tissue. To learn more about these effects, we measured renal blood flow (RBF) and glomerular filtration rate (GFR) at 28 hours after IRI. EA-230 improved both GFR and RBF significantly. Next, EA-230 treatment was tested in a model of ischemiainduced delayed graft function after allogenic kidney transplantation. The recipients were treated with EA-230 (50 mg/kg) twice daily i.p. which improved renal function and allograft survival by attenuating ischemic allograft damage. In conclusion, EA-230 is a novel and promising therapeutic agent for treating acute kidney injury and preventing IRI-induced post-transplant ischemic allograft injury. Its beneficial effect is associated with improved renal perfusion after IRI and enhanced regeneration of tubular epithelial cells. © 2015 Gueler et al.


Willenberg I.,University of Veterinary Medicine Hannover | Meschede A.K.,University of Veterinary Medicine Hannover | Gueler F.,Hannover Medical School | Jang M.-S.,Hannover Medical School | And 4 more authors.
PLoS ONE | Year: 2015

Epidemiologic studies show a correlation between the dietary intake of food polyphenols and beneficial health effects. Several in vitro studies indicate that the anti-inflammatory potential of polyphenols is, at least in part, mediated by a modulation of the enzymes of the arachidonic acid cascade, such as the prostaglandin forming cyclooxygenases (COXs). Evidence that this mode of action can be transferred to the situation in vivo is scarce. This study characterized effects of a subset of polyphenols on COX-2 expression and activity in vitro and compared the potency with known drugs. Next, the in vivo relevance of the observed in vitro effects was tested. Enzyme assays and incubations of polyphenols with the cancer cell line HCA-7 and lipopolysaccharide (LPS) stimulated primary monocytes support the hypothesis that polyphenols can effect COX-2 expression and activity in vitro. The effects were most pronounced in the monocyte assay for wogonin, apigenin, resveratrol and genistein with IC50 values of 1.5 μM, 2.6 μM, 2.8 μM and 7.4 μM. However, these values are 100- to 1000-fold higher in comparison to those of the known pharmaceuticals celecoxib, indomethacin and dexamethasone. In an animal model of LPS induced sepsis, pretreatment with polyphenols (i. p. 100 mg/kg bw) did not result in decreased plasma or tissue prostaglandin levels, whereas the positive control celecoxib effectively attenuated LPS induced prostaglandin formation. These data suggest that despite the moderate potency in vitro, an effect of polyphenols on COX-2 during acute inflammation is unlikely, even if a high dose of polyphenols is ingested. © 2015 Willenberg et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


Vallabhaneni K.C.,Hannover Medical School | Tkachuk S.,Hannover Medical School | Kiyan Y.,Hannover Medical School | Shushakova N.,Hannover Medical School | And 4 more authors.
Cardiovascular Research | Year: 2011

Aims Multipotent mesenchymal stem cells (MSCs) have regenerative properties and are recognized as putative players in the pathogenesis of cardiovascular diseases. The underlying molecular mechanisms remain, however, sparsely explored. Our study was designed to elucidate a probable role for the multifunctional urokinase (uPA)/urokinase receptor (uPAR) system in MSC regulation. Though uPAR has been implicated in a broad spectrum of pathophysiological processes, nothing is known about uPAR in MSCs. Methods and resultsuPAR was required to mobilize MSCs from the bone marrow (BM) of mice stimulated with granulocyte colony-stimulating factor (G-CSF) in vivo. An insignificant amount of MSCs was mobilized in uPAR-/- C57BL/6J mice, whereas in wild-type animals G-CSF induced an eight-fold increase of mobilized MSCs. uPAR-/- mice revealed up-regulated expression of G-CSF and stromal cell-derived factor 1 (CXCR4) receptors in BM. uPAR down-regulation leads to inhibition of human MSC migration, as shown in different migration assays. uPAR down- or up-regulation resulted in inhibition or stimulation of MSC differentiation into vascular smooth muscle cells (VSMCs) correspondingly, as monitored by changes in cell morphology and expression of specific marker proteins. Injection of fluorescently labelled MSCs in non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mice after femoral artery wire injury demonstrated impaired engraftment of uPAR-deficient MSCs at the place of injury. Conclusion sThese data suggest a multifaceted function of uPAR in MSC biology contributing to vascular repair. uPAR might guide and control the trafficking of MSCs to the vascular wall in response to injury or ischaemia and their differentiation towards functional VSMCs at the site of arterial injury. © 2010 The Author.


Menne J.,Hannover Medical School | Menne J.,Phenos GmbH | Shushakova N.,Hannover Medical School | Shushakova N.,Phenos GmbH | And 6 more authors.
Diabetes | Year: 2013

Activation of protein kinase C (PKC) has been implicated in the pathogenesis of diabetic nephropathy with proteinuria and peritubular extracellular matrix production. We have previously shown that the PKC isoforms α and β mediate different cellular effects. PKC-β contributes to hyperglycemia-induced renal matrix production, whereby PKC-α is involved in the development of albuminuria. We further tested this hypothesis by deletion of both isoforms and used a PKC inhibitor. We analyzed the phenotype of nondiabetic and streptozotocin (STZ)-induced diabetic homozygous PKC-α/β double-knockout mice (PKC-α/β-/-). After 8 weeks of diabetes mellitus, the high-glucose-induced renal and glomerular hypertrophy as well as transforming growth factorβ1) and extracellular matrix production were diminished in the PKC-α/β -/- mice compared with wild-type controls. Urinary albumin/ creatinine ratio also was significantly reduced, however, it was not completely abolished in diabetic PKC-α/β-/- mice. Treatment with CGP41252, which inhibits PKC-α and PKC-β, is able to prevent the development of albuminuria and to reduce existing albuminuria in type 1 (STZ model) or type 2 (db/db model) diabetic mice. These results support our hypothesis that PKC-α and PKC-β contribute to the pathogenesis of diabetic nephropathy, and that dual inhibition of the classical PKC isoforms is a suitable therapeutic strategy in the prevention and treatment of diabetic nephropathy. © 2013 by the American Diabetes Association.


Wang L.,Hannover Medical School | Wang L.,Huazhong University of Science and Technology | Balzer M.S.,Hannover Medical School | Rong S.,Hannover Medical School | And 12 more authors.
Kidney International | Year: 2016

Chronic exposure to commercial glucose-based peritoneal dialysis fluids during peritoneal dialysis induces peritoneal membrane damage leading to ultrafiltration failure. In this study the role of protein kinase C (PKC) α in peritoneal membrane damage was investigated in a mouse model of peritoneal dialysis. We used 2 different approaches: blockade of biological activity of PKCα by intraperitoneal application of the conventional PKC inhibitor Go6976 in C57BL/6 wild-type mice and PKCα-deficient mice on a 129/Sv genetic background. Daily administration of peritoneal dialysis fluid for 5 weeks induced peritoneal upregulation and activation of PKCα accompanied by epithelial-to-mesenchymal transition of peritoneal mesothelial cells, peritoneal membrane fibrosis, neoangiogenesis, and macrophage and T cell infiltration, paralleled by reduced ultrafiltration capacity. All pathological changes were prevented by PKCα blockade or deficiency. Moreover, treatment with Go6976 and PKCα deficiency resulted in strong reduction of proinflammatory, profibrotic, and proangiogenic mediators. In cell culture experiments, both treatment with Go6976 and PKCα deficiency prevented peritoneal dialysis fluid–induced release of MCP-1 from mouse peritoneal mesothelial cells and ameliorated transforming growth factor-β1–induced epithelial-to-mesenchymal transition and peritoneal dialysis fluid–induced MCP-1 release in human peritoneal mesothelial cells. Thus, PKCα plays a crucial role in the pathophysiology of peritoneal membrane dysfunction induced by peritoneal dialysis fluids, and we suggest that its therapeutic inhibition might be a valuable treatment option for peritoneal dialysis patients. © 2016 International Society of Nephrology


Hoehlig K.,Noxxon Pharma | Maasch C.,Noxxon Pharma | Shushakova N.,Phenos GmbH | Buchner K.,Noxxon Pharma | And 4 more authors.
Molecular Therapy | Year: 2013

Complement factor C5a is a potent proinflammatory mediator that contributes to the pathogenesis of numerous inflammatory diseases. Here, we describe the discovery of NOX-D20, a PEGylated biostable mirror-image mixed (l-)RNA/DNA aptamer (Spiegelmer) that binds to mouse and human C5a with picomolar affinity. In vitro, NOX-D20 inhibited C5a-induced chemotaxis of a CD88-expressing cell line and efficiently antagonized the activation of primary human polymorphonuclear leukocytes (PMN) by C5a. Binding of NOX-D20 to the C5a moiety of human C5 did not interfere with the formation of the terminal membrane attack complex (MAC). In sepsis, for which a specific interventional therapy is currently lacking, complement activation and elevated levels of C5a are suggested to contribute to multiorgan failure and mortality. In the model of polymicrobial sepsis induced by cecal ligation and puncture (CLP), NOX-D20 attenuated inflammation and organ damage, prevented the breakdown of the vascular endothelial barrier, and improved survival. Our study suggests NOX-D20 as a new therapeutic candidate for the treatment of sepsis. © The American Society of Gene & Cell Therapy.

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