Renal Urokinase-Type Plasminogen Activator (uPA) Receptor but not uPA Deficiency Strongly Attenuates Ischemia Reperfusion Injury and Acute Kidney Allograft Rejection

Department of Nephrology, Medical School Hannover, Hannover, Germany.
The Journal of Immunology (Impact Factor: 4.92). 08/2008; 181(2):1179-89. DOI: 10.4049/jimmunol.181.2.1179
Source: PubMed


Central mechanisms leading to ischemia induced allograft rejection are apoptosis and inflammation, processes highly regulated by the urokinase-type plasminogen activator (uPA) and its specific receptor (uPAR). Recently, up-regulation of uPA and uPAR has been shown to correlate with allograft rejection in human biopsies. However, the causal connection of uPA/uPAR in mediating transplant rejection and underlying molecular mechanisms remain poorly understood. In this study, we evaluated the role of uPA/uPAR in a mice model for kidney ischemia reperfusion (IR) injury and for acute kidney allograft rejection. uPAR but not uPA deficiency protected from IR injury. In the allogenic kidney transplant model, uPAR but not uPA deficiency of the allograft caused superior recipient survival and strongly attenuated loss of renal function. uPAR-deficient allografts showed reduced generation of reactive oxygen species and apoptosis. Moreover, neutrophil and monocyte/macrophage infiltration was strongly attenuated and up-regulation of the adhesion molecule ICAM-1 was completely abrogated in uPAR-deficient allografts. Inadequate ICAM-1 up-regulation in uPAR(-/-) primary aortic endothelial cells after C5a and TNF-alpha stimulation was confirmed by in vitro experiments. Our results demonstrate that the local renal uPAR plays an important role in the apoptotic and inflammatory responses mediating IR-injury and transplant rejection.

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    • "Murine kidney transplantation has gained widespread use as genetically modified strains can be used to study the molecular mechanisms of renal allograft injury [1,2]. However, due to the technical complexity and high mortality rates, few laboratories in the world have mastered this procedure. "
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    ABSTRACT: Mouse renal transplantation is a technically challenging procedure. Although the first kidney transplants in mice were performed over 34 years ago and refined some years later, the classical techniques of mouse renal transplantation required clamping both vena cava and aorta simultaneously and carry out suture anastomoses of the renal artery and vein in a heterotopic position. In our laboratory, we have successfully developed mouse orthotopic kidney transplantation for the first time, using a rapid "cuffed" renal vein technique for vessel anastomosis, wherein the donor's renal vein was inserted through an intravenous catheter, folded back and tied. During grafting, the cuffed renal vein was directly inserted into the recipient's renal vein without the need for the clamping vena cava and suturing of renal vein. This technique allowed for the exact transplantation of the kidney into the original position, compared to the classical technique, and has significantly shortened the clamping time due to a quicker and precise anastomosis of renal vein as described. This also allowed for a quicker recovery of the lower extremity activity, reduction in myoglobinuria with resultant kidney graft survival of 88.9%. Thus we believe that the cuffed renal vein technique simplifies microvascular anastomoses and affords important additional benefits.
    PLoS ONE 10/2013; 8(10):e77278. DOI:10.1371/journal.pone.0077278 · 3.23 Impact Factor
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    • "We confirmed no significant changes in expression of other genes in CD2h tissues, with the exception of uPAR in the medullas. Although we do not know why uPAR gene expression was reduced in CD2h kidney medullas, ischemia/reperfusion injury is reportedly ameliorated in uPAR knockout mouse [22], suggesting that this change in expression uPAR gene is logical. "
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    ABSTRACT: The main objective of this study was to assess cardiac death (CD) kidney grafts before transplantation to determine whether blood oxygen level-dependent (BOLD) and diffusion MRI techniques can predict damage to these grafts after transplantation. We assessed CD kidney tissue by BOLD and diffusion MRI. We also examined pathological and gene expression changes in CD kidney grafts before and after transplantation. Although there was significantly more red cell congestion (RCC) in the inner stripe of the outer medulla (IS) in both 1 h after cardiac death (CD1h) and CD2h kidneys destined for grafts before transplantation compared with CD0h (p<0.05), CD2h, but not CD1h, kidney grafts had significantly different RCC in the IS 2 days after transplantation (p<0.05). Consistent with these pathological findings, tissue plasminogen activator (tPA) gene expression was increased only in the cortex and medulla of CD2h kidney grafts after transplantation. BOLD MRI successfully and non-invasively imaged and quantified RCC in the IS in both CD1h and CD2h kidney grafts (p<0.05). Diffusion MRI also non-invasively assessed increased the apparent diffusion coefficient in the IS and decreased it in the outer stripe (OS) of CD2h grafts, in concordance with interstitial edema in the IS and tubule cellular edema in the OS. These two types of edema in the outer medulla could explain the prolonged RCC in the IS only of CD2h kidney grafts, creating part of a vicious cycle inhibiting red cells coming out of capillary vessels in the IS. Perfusion with University of Wisconsin solution before MRI measurements did not diminish the difference in tissue damage between CD1h and CD2h kidney grafts. BOLD and diffusion MRI, which are readily available non-invasive tools for evaluating CD kidney grafts tissue damage, can predict prolonged organ damage, and therefore the outcome, of transplanted CD kidney grafts.
    PLoS ONE 05/2013; 8(5):e63573. DOI:10.1371/journal.pone.0063573 · 3.23 Impact Factor
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    ABSTRACT: The purpose of this study was to investigate the effects of minocycline on the renal dysfunction and injury caused by bilateral ischemia/reperfusion (I/R) of murine kidneys in vivo. Male C57BL/6 mice were administered minocycline (45 mg/kg i.v.) or saline (0.9%, v/v, NaCl) 36 hours prior to I/R. Mice were subjected to bilateral renal ischemia (35 min) followed by reperfusion (6 hours). Serum creatinine (sCr) and blood urea nitrogen (BUN) levels were measured. Additionally, renal superoxide dismutase (SOD) levels, malondialdehyde (MDA) levels and myeloperoxidase (MPO) activity were determined. The expression of intercellular adhesion molecule-1 (ICAM-1), caspase-3, caspase-8 and caspase-9 was determined using real time RT-PCR and Western blot analysis. Minocycline administration significantly reduced the increases in sCr and BUN caused by I/R, indicating attenuation of renal dysfunction and injury, and reduced histological evidence of renal damage caused by I/R. Minocycline administration also markedly reduced the evidence of oxidative stress (MPO activity, SOD and MDA levels), inflammation (ICAM-1 expression and MPO activity) and apoptosis (caspase-3, caspase-8 and caspase-9 expression) in mouse kidneys subjected to I/R. These findings provide good evidence that minocycline can reduce the renal dysfunction and injury caused by I/R of the kidney. Its mechanism may involve suppression of apoptosis, inflammatory response and oxidative stress.
    Clinical and investigative medicine. Medecine clinique et experimentale 01/2011; 34(2):E55-63. · 1.23 Impact Factor
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