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Zhang P, Sun C, Mo S, Hu C, Ning Y, Liang H, Liu Z, Fan X, Wang Y. Salvaging donated kidneys from prolonged warm ischemia during ex vivo hypothermic oxygenated perfusion. Kidney Int 2024; 106:273-290. [PMID: 38789038 DOI: 10.1016/j.kint.2024.04.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 03/28/2024] [Accepted: 04/25/2024] [Indexed: 05/26/2024]
Abstract
Prolonged warm ischemic is the main cause discarding donated organs after cardiac death. Here, we identified that prolonged warm ischemic time induced disseminated intravascular coagulation and severe capillary vasospasm after cardiac death of rat kidneys. Additionally, we found a significant accumulation of fibrinogen in a hypoxic cell culture of human umbilical vein epithelial cells and in isolated kidneys exposed to prolonged warm ischemic following flushing out of blood. However, pre-flushing the kidney with snake venom plasmin in a 90-minute warm ischemic model maximized removal of micro thrombi and facilitated the delivery of oxygen and therapeutic agents. Application of carbon monoxide-releasing CORM-401 during ex vivo hypothermic oxygenated perfusion achieved multipath protective effects in prolonged warm ischemic kidneys. This led to significant improvements in perfusion parameters, restoration of the microcirculation, amelioration of mitochondrial injury, oxidative stress, and apoptosis. This benefit resulted in significantly prolonged warm ischemic kidney recipient survival rates of 70%, compared with none in those receiving ex vivo hypothermic oxygenated perfusion alone. Significantly, ex vivo hypothermic oxygenated perfusion combined with cytoprotective carbon monoxide releasing CORM-401 treatment meaningfully protected the donated kidney after cardiac death from ischemia-reperfusion injury by reducing inflammation, oxidative stress, apoptosis, and pathological damage. Thus, our study suggests a new combination treatment strategy to potentially expand the donor pool by increasing use of organs after cardiac death and salvaging prolonged warm ischemic kidneys.
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Affiliation(s)
- Peng Zhang
- Zhongnan Hospital of Wuhan University, Institute of Hepatobiliary Diseases of Wuhan University, Wuhan, Hubei, P.R. China; Zhongnan Hospital of Wuhan University, Transplant Center of Wuhan University, Wuhan, Hubei, P.R. China
| | - Chao Sun
- Zhongnan Hospital of Wuhan University, Institute of Hepatobiliary Diseases of Wuhan University, Wuhan, Hubei, P.R. China; Zhongnan Hospital of Wuhan University, Transplant Center of Wuhan University, Wuhan, Hubei, P.R. China
| | - Shuyong Mo
- Zhongnan Hospital of Wuhan University, Institute of Hepatobiliary Diseases of Wuhan University, Wuhan, Hubei, P.R. China; Zhongnan Hospital of Wuhan University, Transplant Center of Wuhan University, Wuhan, Hubei, P.R. China
| | - Chaoyu Hu
- Zhongnan Hospital of Wuhan University, Institute of Hepatobiliary Diseases of Wuhan University, Wuhan, Hubei, P.R. China; Zhongnan Hospital of Wuhan University, Transplant Center of Wuhan University, Wuhan, Hubei, P.R. China
| | - Yuxiang Ning
- Zhongnan Hospital of Wuhan University, Institute of Hepatobiliary Diseases of Wuhan University, Wuhan, Hubei, P.R. China; Zhongnan Hospital of Wuhan University, Transplant Center of Wuhan University, Wuhan, Hubei, P.R. China
| | - Han Liang
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, P.R. China
| | - Zhongzhong Liu
- Zhongnan Hospital of Wuhan University, Institute of Hepatobiliary Diseases of Wuhan University, Wuhan, Hubei, P.R. China; Zhongnan Hospital of Wuhan University, Transplant Center of Wuhan University, Wuhan, Hubei, P.R. China
| | - Xiaoli Fan
- Zhongnan Hospital of Wuhan University, Institute of Hepatobiliary Diseases of Wuhan University, Wuhan, Hubei, P.R. China; Zhongnan Hospital of Wuhan University, Transplant Center of Wuhan University, Wuhan, Hubei, P.R. China
| | - Yanfeng Wang
- Zhongnan Hospital of Wuhan University, Institute of Hepatobiliary Diseases of Wuhan University, Wuhan, Hubei, P.R. China; Zhongnan Hospital of Wuhan University, Transplant Center of Wuhan University, Wuhan, Hubei, P.R. China.
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Clarke-Bland CE, Bill RM, Devitt A. Emerging roles for AQP in mammalian extracellular vesicles. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183826. [PMID: 34843700 PMCID: PMC8755917 DOI: 10.1016/j.bbamem.2021.183826] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 11/18/2021] [Accepted: 11/19/2021] [Indexed: 12/13/2022]
Abstract
Recent research in the aquaporin (AQP) field has identified a role for diverse AQPs in extracellular vesicles (EV). Though still in its infancy, there is a growing body of knowledge in the area; AQPs in EV have been suggested as biomarkers for disease, as drug targets and show potential as therapeutics. To advance further in this field, AQPs in EV must be better understood. Here we summarize current knowledge of the presence and function of AQPs in EV and hypothesise their roles in health and disease.
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Affiliation(s)
| | - Roslyn M Bill
- College of Health and Life Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Andrew Devitt
- College of Health and Life Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK.
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3
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Oshikawa-Hori S, Yokota-Ikeda N, Sonoda H, Ikeda M. Urinary extracellular vesicular release of aquaporins in patients with renal transplantation. BMC Nephrol 2019; 20:216. [PMID: 31185935 PMCID: PMC6580655 DOI: 10.1186/s12882-019-1398-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Accepted: 05/28/2019] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND Diuresis has been observed within a week following renal transplantation, suggesting that the procedure causes acute disturbance of renal water homeostasis. Aquaporin (AQP) 1 and AQP2, important proteins for renal water reabsorption, have been identified in urinary extracellular vesicles (uEV-AQP1 and -AQP2), and experimental studies have shown that the presence of uEV-AQP1 and -AQP2 may be an indicator of their levels of expression in the kidney. However, the release patterns of uEV-AQP1 and -AQP2 during the acute phase following renal transplantation are largely unknown. METHODS In this study, we examined the release of uEV-AQP1 and -AQP2 in recipients until 6 days (day 6) after renal transplantation. At Miyazaki prefectural Miyazaki Hospital, Japan, uEVs were obtained from 7 recipients, all of whom had received renal allografts from living donors. uEVs were isolated by differential centrifugation. RESULTS Immunoblotting analysis showed that the release of uEV-AQP2 was significantly decreased on day 1 in comparison with a control sample (from 3 healthy volunteers), accompanied by high urine output and low urine osmolality. Thereafter, the level increased gradually to the control level by day 6. The release pattern of uEV-AQP1 was similar to that of uEV-AQP2, but the levels did not reach statistical significance in comparison with the control level at any of the time points examined. Evaluation of the relationship between urinary osmolality and uEV-AQPs revealed a significant correlation for uEV-AQP2, but not for uEV-AQP1. CONCLUSION These results indicate that acute diuresis after renal transplantation might be due to a decrease in the renal expression of AQP2, whose level can be estimated from the amount released in uEVs.
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Affiliation(s)
- Sayaka Oshikawa-Hori
- Department of Veterinary Pharmacology, Faculty of Agriculture, University of Miyazaki, Gakuenkibanadai-Nishi 1-1, Miyazaki, 889-2192 Japan
| | - Naoko Yokota-Ikeda
- Nephrology, Miyazaki Prefectural Miyazaki Hospital, Kitatakamatsu 5-30, Miyazaki, 880-8510 Japan
| | - Hiroko Sonoda
- Department of Veterinary Pharmacology, Faculty of Agriculture, University of Miyazaki, Gakuenkibanadai-Nishi 1-1, Miyazaki, 889-2192 Japan
| | - Masahiro Ikeda
- Department of Veterinary Pharmacology, Faculty of Agriculture, University of Miyazaki, Gakuenkibanadai-Nishi 1-1, Miyazaki, 889-2192 Japan
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Baban B, Marchetti C, Khodadadi H, Malik A, Emami G, Lin PC, Arbab AS, Riccardi C, Mozaffari MS. Glucocorticoid-Induced Leucine Zipper Promotes Neutrophil and T-Cell Polarization with Protective Effects in Acute Kidney Injury. J Pharmacol Exp Ther 2018; 367:483-493. [PMID: 30301736 DOI: 10.1124/jpet.118.251371] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 10/01/2018] [Indexed: 12/11/2022] Open
Abstract
The glucocorticoid-induced leucine zipper (GILZ) mediates anti-inflammatory effects of glucocorticoids. Acute kidney injury (AKI) mobilizes immune/inflammatory mechanisms, causing tissue injury, but the impact of GILZ in AKI is not known. Neutrophils play context-specific proinflammatory [type 1 neutrophil (N1)] and anti-inflammatory [type 2 neutrophil (N2)] functional roles. Also, regulatory T lymphocytes (Tregs) and regulatory T-17 (Treg17) cells exert counterinflammatory effects, including the suppression of effector T lymphocytes [e.g., T-helper (Th) 17 cells]. Thus, utilizing cell preparations of mice kidneys subjected to AKI or sham operation, we determined the effects of GILZ on T cells and neutrophil subtypes in the context of its renoprotective effect; these studies used the transactivator of transcription (TAT)-GILZ or the TAT peptide. AKI increased N1 and Th-17 cells but reduced N2, Tregs, and Treg17 cells in association with increased interleukin (IL)-17+ but reduced IL-10+ cells accompanied with the disruption of mitochondrial membrane potential (ψ m) and increased apoptosis/necrosis compared with sham kidneys. TAT-GILZ, compared with TAT, treatment reduced N1 and Th-17 cells but increased N2 and Tregs, without affecting Treg17 cells, in association with a reduction in IL-17+ cells but an increase in IL-10+ cells; TAT-GILZ caused less disruption of ψ m and reduced cell death in AKI. Importantly, TAT-GILZ increased perfusion of the ischemic-reperfused kidney but reduced tissue edema compared with TAT. Utilizing splenic T cells and bone marrow-derived neutrophils, we further showed marked reduction in the proliferation of Th cells in response to TAT-GILZ compared with response to TAT. Collectively, the results indicate that GILZ exerts renoprotection accompanied by the upregulation of the regulatory/suppressive arm of immunity in AKI, likely via regulating cross talk between T cells and neutrophils.
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Affiliation(s)
- Babak Baban
- Department of Oral Biology and Diagnostic Sciences, Dental College of Georgia (B.B., H.K., A.M., G.E., M.S.M.) and Georgia Cancer Center (P.-C.L., A.S.A.), Augusta University, Augusta, Georgia; and Department of Medicine, University of Perugia, Perugia, Italy (C.M., C.R.)
| | - Cristina Marchetti
- Department of Oral Biology and Diagnostic Sciences, Dental College of Georgia (B.B., H.K., A.M., G.E., M.S.M.) and Georgia Cancer Center (P.-C.L., A.S.A.), Augusta University, Augusta, Georgia; and Department of Medicine, University of Perugia, Perugia, Italy (C.M., C.R.)
| | - Hesam Khodadadi
- Department of Oral Biology and Diagnostic Sciences, Dental College of Georgia (B.B., H.K., A.M., G.E., M.S.M.) and Georgia Cancer Center (P.-C.L., A.S.A.), Augusta University, Augusta, Georgia; and Department of Medicine, University of Perugia, Perugia, Italy (C.M., C.R.)
| | - Aneeq Malik
- Department of Oral Biology and Diagnostic Sciences, Dental College of Georgia (B.B., H.K., A.M., G.E., M.S.M.) and Georgia Cancer Center (P.-C.L., A.S.A.), Augusta University, Augusta, Georgia; and Department of Medicine, University of Perugia, Perugia, Italy (C.M., C.R.)
| | - Golnaz Emami
- Department of Oral Biology and Diagnostic Sciences, Dental College of Georgia (B.B., H.K., A.M., G.E., M.S.M.) and Georgia Cancer Center (P.-C.L., A.S.A.), Augusta University, Augusta, Georgia; and Department of Medicine, University of Perugia, Perugia, Italy (C.M., C.R.)
| | - Ping-Chang Lin
- Department of Oral Biology and Diagnostic Sciences, Dental College of Georgia (B.B., H.K., A.M., G.E., M.S.M.) and Georgia Cancer Center (P.-C.L., A.S.A.), Augusta University, Augusta, Georgia; and Department of Medicine, University of Perugia, Perugia, Italy (C.M., C.R.)
| | - Ali S Arbab
- Department of Oral Biology and Diagnostic Sciences, Dental College of Georgia (B.B., H.K., A.M., G.E., M.S.M.) and Georgia Cancer Center (P.-C.L., A.S.A.), Augusta University, Augusta, Georgia; and Department of Medicine, University of Perugia, Perugia, Italy (C.M., C.R.)
| | - Carlo Riccardi
- Department of Oral Biology and Diagnostic Sciences, Dental College of Georgia (B.B., H.K., A.M., G.E., M.S.M.) and Georgia Cancer Center (P.-C.L., A.S.A.), Augusta University, Augusta, Georgia; and Department of Medicine, University of Perugia, Perugia, Italy (C.M., C.R.)
| | - Mahmood S Mozaffari
- Department of Oral Biology and Diagnostic Sciences, Dental College of Georgia (B.B., H.K., A.M., G.E., M.S.M.) and Georgia Cancer Center (P.-C.L., A.S.A.), Augusta University, Augusta, Georgia; and Department of Medicine, University of Perugia, Perugia, Italy (C.M., C.R.)
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Baban B, Hoda N, Malik A, Khodadadi H, Simmerman E, Vaibhav K, Mozaffari MS. Impact of cannabidiol treatment on regulatory T-17 cells and neutrophil polarization in acute kidney injury. Am J Physiol Renal Physiol 2018; 315:F1149-F1158. [PMID: 29897289 DOI: 10.1152/ajprenal.00112.2018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Hallmark features of acute kidney injury (AKI) include mobilization of immune and inflammatory mechanisms culminating in tissue injury. Emerging information indicates heterogeneity of neutrophils with pro- and anti-inflammatory functions (N1 and N2, respectively). Also, regulatory T-17 (Treg17) cells curtail T helper 17 (Th-17)-mediated proinflammatory responses. However, the status of Treg17 cells and neutrophil phenotypes in AKI are not established. Furthermore, cannabidiol exerts immunoregulatory effects, but its impact on Treg17 cells and neutrophil subtypes is not established. Thus, we examined the status of Treg17 cells and neutrophil subtypes in AKI and determined whether cannabidiol favors regulatory neutrophils and T cells accompanied with renoprotection. Accordingly, mice were subjected to bilateral renal ischemia-reperfusion injury (IRI), without or with cannabidiol treatment; thereafter, kidneys were processed for flow cytometry analyses. Renal IRI increased N1 and Th-17 but reduced N2 and Treg17 cells accompanied with disruption of mitochondrial membrane potential (ψm) and increased apoptosis/necrosis and kidney injury molecule-1 (KIM-1) immunostaining compared with their sham controls. Importantly, cannabidiol treatment preserved ψm and reduced cell death and KIM-1 accompanied by restoration of N1 and N2 imbalance and preservation of Treg17 cells while decreasing Th-17 cells. The ability of cannabidiol to favor development of Treg17 cells was further established using functional mixed lymphocytic reaction. Subsequent studies showed higher renal blood flow and reduced serum creatinine in cannabidiol-treated IRI animals. Collectively, our novel observations establish that renal IRI causes neutrophil polarization in favor of N1 and also reduces Treg17 cells in favor of Th-17, effects that are reversed by cannabidiol treatment accompanied with significant renoprotection.
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Affiliation(s)
- Babak Baban
- Department of Oral Biology, Dental College of Georgia, Augusta University , Augusta, Georgia.,Department of Neurology, Medical College of Georgia, Augusta University , Augusta, Georgia
| | - Nasrul Hoda
- Department of Neurology, Medical College of Georgia, Augusta University , Augusta, Georgia.,Department of Medical Laboratory, Imaging, and Radiological Sciences, College of Allied Health Sciences, Augusta University , Augusta, Georgia
| | - Aneeq Malik
- Department of Oral Biology, Dental College of Georgia, Augusta University , Augusta, Georgia
| | - Hesam Khodadadi
- Department of Oral Biology, Dental College of Georgia, Augusta University , Augusta, Georgia
| | - Erika Simmerman
- Department of Surgery, Medical College of Georgia, Augusta University , Augusta, Georgia
| | - Kumar Vaibhav
- Department of Neurosurgery, Medical College of Georgia, Augusta University , Augusta, Georgia
| | - Mahmood S Mozaffari
- Department of Oral Biology, Dental College of Georgia, Augusta University , Augusta, Georgia
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Klein K, Rübenacker S, Schaefer SM, Kihm LP, Schwenger V, Macher-Goeppinger S, Schemmer P, Süsald C, Zeier M, Morath C, Becker LE. Tissue Expression of Aquaporin 2 Is Correlated to Urine Output and Allograft Function in Sensitized Kidney Transplant Patients. Transplant Proc 2017; 48:2629-2636. [PMID: 27788793 DOI: 10.1016/j.transproceed.2016.06.056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Revised: 05/05/2016] [Accepted: 06/06/2016] [Indexed: 01/23/2023]
Abstract
BACKGROUND Salt and water disturbances often occur during acute kidney allograft dysfunction that contribute to graft failure, but this condition has been poorly investigated in the alloreactivity setting. We evaluated the tissue expression of aquaporins (AQP1 and AQP2) and the epithelial sodium channel (ENAC) in kidney biopsy specimens from sensitized kidney transplant recipients. METHODS Eighty-six biopsy specimens from 33 sensitized patients were divided into 3 groups according to clinical context: time-zero (n = 9), protocol (n = 9), and indication (n = 68). The indication biopsy specimens were further divided into 3 subgroups according to the presence of acute tubular necrosis or rejection. Normal kidney tissue samples (n = 6) served as the control specimens. Immmunohistochemical expression of AQP1, AQP2, and ENAC was determined by using image analyzing software. RESULTS Significantly lower AQP1 expression was observed in the time-zero and indication biopsy specimens with rejection compared with control specimens (P = .03 and P = .04, respectively). AQP2 expression was significantly lower in patients with an indication biopsy specimen compared with control and protocol biopsy specimens (P = .05 and P = .005). For ENAC, a lower expression was noted in the indication biopsy specimens compared with the control specimens (P = .04). Both AQP1 and AQP2 tissue expressions were significantly correlated to urine output (r = 0.45 and r = 0.32; P = .001 and P = .02), and AQP2 was correlated with the glomerular filtration rate estimated by using the Modification of Diet in Renal Disease Study equation at biopsy (r = 0.23; P = .05). CONCLUSIONS These findings partially confirm previous experimental data showing downregulation of AQP1 expression after ischemia/reperfusion injury and during rejection. AQP2 downregulation seems to be rejection-independent, occurring during deteriorating or poor kidney graft function.
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Affiliation(s)
- K Klein
- Division of Nephrology, University of Heidelberg, Heidelberg, Germany
| | - S Rübenacker
- Division of Nephrology, University of Heidelberg, Heidelberg, Germany
| | - S M Schaefer
- Division of Nephrology, University of Heidelberg, Heidelberg, Germany
| | - L P Kihm
- Division of Nephrology, University of Heidelberg, Heidelberg, Germany
| | - V Schwenger
- Division of Nephrology, University of Heidelberg, Heidelberg, Germany
| | | | - P Schemmer
- Department of Transplantation Surgery, University of Heidelberg, Heidelberg, Germany
| | - C Süsald
- Department of Transplant Immunology, University of Heidelberg, Heidelberg, Germany
| | - M Zeier
- Division of Nephrology, University of Heidelberg, Heidelberg, Germany
| | - C Morath
- Division of Nephrology, University of Heidelberg, Heidelberg, Germany
| | - L E Becker
- Division of Nephrology, University of Heidelberg, Heidelberg, Germany.
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Goel P, Manning JA, Kumar S. NEDD4-2 (NEDD4L): the ubiquitin ligase for multiple membrane proteins. Gene 2014; 557:1-10. [PMID: 25433090 DOI: 10.1016/j.gene.2014.11.051] [Citation(s) in RCA: 122] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Revised: 11/14/2014] [Accepted: 11/21/2014] [Indexed: 12/20/2022]
Abstract
NEDD4-2 (also known as NEDD4L, neural precursor cell expressed developmentally down-regulated 4-like) is a ubiquitin protein ligase of the Nedd4 family which is known to bind and regulate a number of membrane proteins to aid in their internalization and turnover. Several of the NEDD4-2 substrates include ion channels, such as the epithelial and voltage-gated sodium channels. Given the critical function of NEDD4-2 in regulating membrane proteins, this ligase is essential for the maintenance of cellular homeostasis. In this article we review the biology and function of this important ubiquitin-protein ligase and discuss its pathophysiological significance.
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Affiliation(s)
- Pranay Goel
- Centre for Cancer Biology, University of South Australia, Adelaide, SA 5001, Australia; Department of Medicine, The University of Adelaide, Adelaide, SA 5005, Australia
| | - Jantina A Manning
- Centre for Cancer Biology, University of South Australia, Adelaide, SA 5001, Australia
| | - Sharad Kumar
- Centre for Cancer Biology, University of South Australia, Adelaide, SA 5001, Australia; Department of Medicine, The University of Adelaide, Adelaide, SA 5005, Australia.
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Effect of Poria cocos on Puromycin Aminonucleoside-Induced Nephrotic Syndrome in Rats. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2014; 2014:570420. [PMID: 25165480 PMCID: PMC4140122 DOI: 10.1155/2014/570420] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 07/08/2014] [Accepted: 07/13/2014] [Indexed: 01/26/2023]
Abstract
Nephrotic syndrome is associated with altered renal handling of water and sodium and changes in the levels of aquaporins (AQPs) and epithelial Na channels (ENaCs). The dried sclerotia of Poria cocos Wolf (WPC) have been used for treating chronic edema and nephrosis. We evaluated the effects of WPC on puromycin aminonucleoside- (PAN-) induced renal functional derangement and altered renal AQP2 and ENaC expression. In the nephrotic syndrome rat model, animals were injected with 75 mg/kg PAN and then treated with Losartan (30 mg·kg−1·day−1) or WPC (200 mg·kg−1·day−1) for 7 days. In the WPC group, proteinuria and ascites improved significantly. Plasma levels of triglyceride, total cholesterol, and low-density lipoprotein- (LDL-) cholesterol reduced significantly in the WPC group. In addition, the WPC group exhibited attenuation of the PAN-induced increase in AQP2 and ENaC α/β subunit protein and mRNA levels. WPC suppressed significantly PAN-induced organic osmolyte regulators, reducing serum- and glucocorticoid-inducible protein kinase (Sgk1) and sodium-myo-inositol cotransporter (SMIT) mRNA expression. Our results show that WPC improves nephrotic syndrome, including proteinuria and ascites, through inhibition of AQP2 and ENaC expression. Therefore, WPC influences body-fluid regulation via inhibition of water and sodium channels, thereby, improving renal disorders such as edema or nephrosis.
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Grabner A, Kentrup D, Edemir B, Sirin Y, Pavenstädt H, Schlatter E, Schober O, Schäfers M, Schnöckel U, Reuter S. PET with 18F-FDG-labeled T lymphocytes for diagnosis of acute rat renal allograft rejection. J Nucl Med 2013; 54:1147-53. [PMID: 23670903 DOI: 10.2967/jnumed.112.109231] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
UNLABELLED 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. METHODS One and 2 h after tail vein injection of 30 × 10(6) ex vivo (18)F-FDG-labeled human T cells into male 10-wk-old uninephrectomized, allogeneically transplanted rats (aTX; Lewis-brown Norway [LBN] to Lewis), whole-body radioactivity distribution was assessed in vivo by small-animal PET (postoperative day 4), and percentage injected dose (%ID) as a parameter of T-cell infiltration was assessed and compared between graft and native kidney. In vivo results were confirmed by autoradiography and staining of human CD3 after postmortem dissection. Syngeneically transplanted rats (sTX) (LBN to LBN), rats with ischemia-reperfusion injury (IRI) (45-min warm ischemia), and rats subjected to acute cyclosporine A (CSA) toxicity (50 mg/kg for 2 d intraperitoneally) served as controls. RESULTS The accumulation of labeled cells was significantly elevated in allografts with AR (1.07 ± 0.28 %ID), compared with native control kidneys (0.49 ± 0.18 %ID) (P < 0.0001). No differences were found among native controls, sTX, CSA toxicity, and kidneys with IRI. In vivo uptake of (18)F-FDG cells measured in the PET scanner correlated with results obtained by autoradiography, histologic evaluation, and polymerase chain reaction. CONCLUSION We proposed graft PET imaging using (18)F-FDG-labeled T cells as a new option to detect rat renal AR with a low dose of (18)F-FDG in a noninvasive, fast, and specific manner in rats.
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Affiliation(s)
- Alexander Grabner
- Department of Internal Medicine D, Experimental Nephrology, University of Münster, Münster, Germany
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10
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Ciarimboli G, Schröter R, Neugebauer U, Vollenbröker B, Gabriëls G, Brzica H, Sabolić I, Pietig G, Pavenstädt H, Schlatter E, Edemir B. Kidney transplantation down-regulates expression of organic cation transporters, which translocate β-blockers and fluoroquinolones. Mol Pharm 2013; 10:2370-80. [PMID: 23607617 DOI: 10.1021/mp4000234] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Kidney transplanted patients are often treated with immunosuppressive, antihypertensive, and antibiotic drugs such as cyclosporine A (CsA), β-blockers, and fluoroquinolones, respectively. Organic cation transporters (OCT) expressed in the basolateral membrane of proximal tubules represent an important drug excretion route. In this work, the renal expression of OCT after syngeneic and allogeneic kidney transplantation in rats with or without CsA immunosuppression was studied. Moreover, the interactions of CsA, β-blockers (pindolol/atenolol), and fluoroquinolones (ofloxacin/norfloxacin) with rOCT1, rOCT2, hOCT1, and hOCT2 in stably transfected HEK293-cells were studied. Kidney transplantation was associated with reduced expression of rOCT1, while rOCT2 showed only reduced expression after allogeneic transplantation. All drugs interacted subtype- and species-dependently with OCT. However, only atenolol, pindolol, and ofloxacin were transported by hOCT2, the main OCT in human kidneys. While CsA is not an OCT substrate, it exerts a short-term effect on OCT activity, changing their affinity for some substrates. In conclusion, appropriate drug dosing in transplanted patients is difficult partly because OCT are down-regulated and because concomitant CsA treatment may influence the affinity of the transporters. Moreover, drug-drug competition at the transporter can also alter drug excretion rate.
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Affiliation(s)
- Giuliano Ciarimboli
- Medizinische Klinik D, Experimentelle Nephrologie, Universitätsklinikum Münster, Albert-Schweitzer-Campus 1/A14, Münster D-48149, Germany
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Grabner A, Kentrup D, Schnöckel U, Gabriëls G, Schröter R, Pavenstädt H, Schober O, Schlatter E, Schäfers M, Reuter S. Non-invasive imaging of acute allograft rejection after rat renal transplantation using 18F-FDG PET. J Vis Exp 2013:e4240. [PMID: 23644348 DOI: 10.3791/4240] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The number of patients with end-stage renal disease, and the number of kidney allograft recipients continuously increases. Episodes of acute cellular allograft rejection (AR) are a negative prognostic factor for long-term allograft survival, and its timely diagnosis is crucial for allograft function (1). At present, AR can only be definitely diagnosed by core-needle biopsy, which, as an invasive method, bares significant risk of graft injury or even loss. Moreover, biopsies are not feasible in patients taking anticoagulant drugs and the limited sampling site of this technique may result in false negative results if the AR is focal or patchy. As a consequence, this gave rise to an ongoing search for new AR detection methods, which often has to be done in animals including the use of various transplantation models. Since the early 60s rat renal transplantation is a well-established experimental method for the examination and analysis of AR (2). We herein present in addition small animal positron emission tomography (PET) using (18)F-fluorodeoxyglucose (FDG) to assess AR in an allogeneic uninephrectomized rat renal transplantation model and propose graft FDG-PET imaging as a new option for a non-invasive, specific and early diagnosis of AR also for the human situation (3). Further, this method can be applied for follow-up to improve monitoring of transplant rejection (4).
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Affiliation(s)
- Alexander Grabner
- Department of Internal Medicine D, Experimental Nephrology, University of Münster.
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Different effects of CsA and FK506 on aquaporin-2 abundance in rat primary cultured collecting duct cells. Pflugers Arch 2011; 462:611-22. [PMID: 21773745 DOI: 10.1007/s00424-011-0994-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 07/04/2011] [Accepted: 07/06/2011] [Indexed: 10/18/2022]
Abstract
Calcineurin (Cn) inhibitors (CnI) such as cyclosporine A (CsA) and FK506 are nephrotoxic immunosuppressant drugs, which decrease tubular function. Here, we examined the direct effect of CnI on aquaporin-2 (AQP2) expression in rat primary cultured inner medullary collecting duct cells. CsA (0.5-5 μM) but not FK 506 (0.01-1 μM) decreased expression of AQP2 protein and messenger RNA (mRNA) in a concentration and time dependent manner, without affecting mRNA stability. This effect was observed despite similar inhibition of Cn activity by both CnI, thereby suggesting that the CsA-dependent decrease in AQP2 expression was Cn independent. Another inhibitor of cyclophilin A, the primary intracellular target of CsA, had no effect on AQP2 expression. In order to investigate the mechanism of decreased AQP2 transcription, we studied activation status of two suggested transcriptional regulators of AQP2, cAMP-responsive element binding protein (CREB), and tonicity enhancer binding protein (TonEBP). Localization of TonEBP, as well as TonEBP-mediated gene transcription, was not affected by CsA. Phosphorylation of CREB at an activating phosphorylation site (S133) was decreased by CsA, but not by FK506. However, both CnI did not affect cellular cAMP levels. We show that CsA decreases transcription of AQP2, a process that is in part independent of Cn or cyclophilin A and suggests dependence on decreased activity of CREB.
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Differential effects of taurine treatment and taurine deficiency on the outcome of renal ischemia reperfusion injury. J Biomed Sci 2010; 17 Suppl 1:S32. [PMID: 20804608 PMCID: PMC2994366 DOI: 10.1186/1423-0127-17-s1-s32] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Taurine possesses membrane stabilization, osmoregulatory and antioxidant properties, aspects of relevance to ischemic injury. We tested the hypothesis that body taurine status is a determinant of renal ischemic injury. Accordingly, renal function and structure were examined in control (C), taurine-treated (TT) and taurine deficient (TD) rats that were subjected to bilateral renal ischemia (60 min) followed by reperfusion (IR); sham operated rats served as controls. Baseline urine osmolality was greater in the TD group than in the control and the TT groups, an effect associated with increased renal aquaporin 2 level. The IR insult reduced urine osmolality (i.e., day-1 post insult); the TD/IR group displayed a more marked recovery in urine osmolality by day-6 post insult than the other two groups. Fluid and sodium excretions were lower in the TD/IR group, suggesting propensity to retention. Histopathological examination revealed the presence of tubular necrotic foci in the C/IR group than sham controls. While renal architecture of the TD/IR group showed features resembling sham controls, the TT/IR group showed dilated tubules, which lacked immunostaining for aquaporin 2, but not 1, suggestive of proximal tubule origin. Finally, assessment of cell proliferation and apoptosis revealed lower proliferation but higher apoptotic foci in the TT/IR group than other IR groups. Collectively, the results indicate that body taurine status is a major determinant of renal IR injury.
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Immunological tolerance induced by galectin-1 in rat allogeneic renal transplantation. Int Immunopharmacol 2010; 10:643-7. [DOI: 10.1016/j.intimp.2010.03.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2010] [Revised: 02/25/2010] [Accepted: 03/02/2010] [Indexed: 11/19/2022]
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Reuter S, Reiermann S, Wörner R, Schröter R, Edemir B, Buck F, Henning S, Peter-Katalinic J, Vollenbröker B, Amann K, Pavenstädt H, Schlatter E, Gabriëls G. IF/TA-related metabolic changes--proteome analysis of rat renal allografts. Nephrol Dial Transplant 2010; 25:2492-501. [PMID: 20176611 DOI: 10.1093/ndt/gfq043] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Chronic allograft nephropathy, now more specifically termed interstitial fibrosis and tubular atrophy without evidence of any specific aetiology (IF/TA), is still an important cause of late graft loss. There is no effective therapy for IF/TA, in part due to the disease's multifactorial nature and its incompletely understood pathogenesis. METHODS We used a differential in-gel electrophoresis and mass spectrometry technique to study IF/TA in a renal transplantation model. Dark Agouti (DA) kidneys were allogeneically transplanted to Wistar-Furth (DA-WF, aTX) rats. Syngeneic grafts (DA-DA, sTX) served as controls. Nine weeks after transplantation, blood pressure, renal function and electrolytes were studied, in addition to real-time PCR, western blot analysis, histology and immunohistochemistry. RESULTS In contrast to sTX, the aTX developed IF/TA-dependent renal damage. Ten differentially regulated proteins were identified by 2D gel analysis and mass spectrometry, whereupon five proteins are mainly related to oxidative stress (aldo-keto reductase, peroxiredoxin-1, NAD(+)-dependent isocitrate dehydrogenase, iron-responsive element-binding protein-1 and serum albumin), two participate in cytoskeleton organization (l-plastin and ezrin) and three are assigned to metabolic functions (creatine kinase, ornithine aminotransferase and fructose-1,6-bisphosphatase). CONCLUSION The proteins related to IF/TA and involved in oxidative stress, cytoskeleton organization and metabolic functions may correspond with novel therapeutic targets.
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Affiliation(s)
- Stefan Reuter
- Department of Medicine D, University of Münster, Münster, Germany.
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Impact of Reduced Nephron Mass on Cyclosporine- and/or Sirolimus-Induced Nephrotoxicity. Transplantation 2009; 88:1323-31. [DOI: 10.1097/tp.0b013e3181bd5951] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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17
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The physiological impact of the serum and glucocorticoid-inducible kinase SGK1. Curr Opin Nephrol Hypertens 2009; 18:439-48. [PMID: 19584721 DOI: 10.1097/mnh.0b013e32832f125e] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
PURPOSE OF REVIEW The role of serum and glucocorticoid-inducible kinase 1 (SGK1) in renal physiology and pathophysiology is reviewed with particular emphasis on recent advances. RECENT FINDINGS The mammalian target of rapamycin complex 2 has been shown to phosphorylate SGK1 at Ser422 (the so-called hydrophobic motif). Ser397 and Ser401 are two additional SGK1-phosphorylation sites required for maximal SGK1 activity. A 5' variant alternate transcript of human Sgk1 has been identified that is widely expressed and shows improved stability, enhanced membrane association, and greater stimulation of epithelial Na+ transport. SGK1 is essential for optimal processing of the epithelial sodium channel and also regulates the expression of the Na+-Cl- cotransporter. With regard to pathophysiology, SGK1 participates in the stimulation of renal tubular glucose transport in diabetes, the renal profibrotic effect of both angiotensin II and aldosterone, and in fetal programing of arterial hypertension. SUMMARY The outlined recent findings advanced our understanding of the molecular regulation of SGK1 as well as the role of the kinase in renal physiology and the pathophysiology of renal disease and hypertension. Future studies using pharmacological inhibitors of SGK1 will reveal the utility of the kinase as a new therapeutic target.
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Reuter S, Schnöckel U, Schröter R, Schober O, Pavenstädt H, Schäfers M, Gabriëls G, Schlatter E. Non-invasive imaging of acute renal allograft rejection in rats using small animal F-FDG-PET. PLoS One 2009; 4:e5296. [PMID: 19390685 PMCID: PMC2669171 DOI: 10.1371/journal.pone.0005296] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2008] [Accepted: 03/30/2009] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND At present, renal grafts are the most common solid organ transplants world-wide. Given the importance of renal transplantation and the limitation of available donor kidneys, detailed analysis of factors that affect transplant survival are important. Despite the introduction of new and effective immunosuppressive drugs, acute cellular graft rejection (AR) is still a major risk for graft survival. Nowadays, AR can only be definitively by renal biopsy. However, biopsies carry a risk of renal transplant injury and loss. Most important, they can not be performed in patients taking anticoagulant drugs. METHODOLOGY/PRINCIPAL FINDINGS We present a non-invasive, entirely image-based method to assess AR in an allogeneic rat renal transplantation model using small animal positron emission tomography (PET) and (18)F-fluorodeoxyglucose (FDG). 3 h after i.v. injection of 30 MBq FDG into adult uni-nephrectomized, allogeneically transplanted rats, tissue radioactivity of renal parenchyma was assessed in vivo by a small animal PET-scanner (post operative day (POD) 1,2,4, and 7) and post mortem dissection. The mean radioactivity (cps/mm(3) tissue) as well as the percent injected dose (%ID) was compared between graft and native reference kidney. Results were confirmed by histological and autoradiographic analysis. Healthy rats, rats with acute CSA nephrotoxicity, with acute tubular necrosis, and syngeneically transplanted rats served as controls. FDG-uptake was significantly elevated only in allogeneic grafts from POD 1 on when compared to the native kidney (%ID graft POD 1: 0.54+/-0.06; POD 2: 0.58+/-0.12; POD 4: 0.81+/-0.06; POD 7: 0.77+/-0.1; CTR: 0.22+/-0.01, n = 3-28). Renal FDG-uptake in vivo correlated with the results obtained by micro-autoradiography and the degree of inflammatory infiltrates observed in histology. CONCLUSIONS/SIGNIFICANCE We propose that graft FDG-PET imaging is a new option to non-invasively, specifically, early detect, and follow-up acute renal rejection. This method is potentially useful to improve post-transplant rejection monitoring.
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Affiliation(s)
- Stefan Reuter
- Medizinische Klinik und Poliklinik D, Experimentelle Nephrologie, Universitätsklinikum Münster, Münster, Germany.
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Ma SK, Bae EH, Kim IJ, Choi KC, Kim SH, Lee J, Kim SW. Increased renal expression of nitric oxide synthase and atrial natriuretic peptide in rats with glycyrrhizic-acid-induced hypertension. Phytother Res 2009; 23:206-11. [DOI: 10.1002/ptr.2588] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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20
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Reuter S, Velic A, Edemir B, Schröter R, Pavenstädt H, Gabriëls G, Bleich M, Schlatter E. Protective role of NHE-3 inhibition in rat renal transplantation undergoing acute rejection. Pflugers Arch 2008; 456:1075-84. [PMID: 18335234 DOI: 10.1007/s00424-008-0484-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2007] [Revised: 02/11/2008] [Accepted: 02/23/2008] [Indexed: 12/26/2022]
Abstract
Acute rejection in renal transplantation disturbs solute and volume maintenance in humans accompanied by delayed graft function and poor prognosis. We recently reported that decreased expression and function of Na+/H+ exchanger type 3 (NHE-3) in proximal tubules and epithelial Na+ channels and aquaporin 2 in collecting ducts are major mechanisms involved in Na+ and water imbalances shortly after transplantation in rat undergoing acute rejection. We performed kidney transplantations in rats with bilaterally nephrectomized recipients with acute rejection and, in addition, systemically administered a specific inhibitor of NHE-3 (NHE-I). NHE inhibition in acute renal failure was shown to improve tubular function and recovery. The aim of this therapy was to reduce energy consumption of the graft and preserve NHE-3 function. Imbalances in electrolyte excretion declined in NHE-I-treated animals and NHE-3 activity was preserved. Observed NHE-I-dependent changes in electrolyte excretion, polyuria, and reduced protein reabsorption in the acute postoperative phase are predictors of favorable graft outcome in humans.
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Affiliation(s)
- Stefan Reuter
- Medizinische Klinik und Poliklinik D, Experimentelle Nephrologie, Universitätsklinikum Münster, Münster, Germany
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Edemir B, Kurian SM, Eisenacher M, Lang D, Müller-Tidow C, Gabriëls G, Salomon DR, Schlatter E. Activation of counter-regulatory mechanisms in a rat renal acute rejection model. BMC Genomics 2008; 9:71. [PMID: 18261221 PMCID: PMC2262896 DOI: 10.1186/1471-2164-9-71] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2007] [Accepted: 02/08/2008] [Indexed: 12/05/2022] Open
Abstract
BACKGROUND Microarray analysis provides a powerful approach to identify gene expression alterations following transplantation. In patients the heterogeneity of graft specimens, co-morbidity, co-medications and the challenges in sample collection and preparation complicate conclusions regarding the underlying mechanisms of graft injury, rejection and immune regulation. RESULTS We used a rat kidney transplantation model with strict transplant and sample preparation procedures to analyze genome wide changes in gene expression four days after syngeneic and allogeneic transplantation. Both interventions were associated with substantial changes in gene expression. After allogeneic transplantation, genes and pathways related to transport and metabolism were predominantly down-regulated consistent with rejection-mediated graft injury and dysfunction. Up-regulated genes were primarily related to the acute immune response including antigen presentation, T-cell receptor signaling, apoptosis, interferon signaling and complement cascades. We observed a cytokine and chemokine expression profile consistent with activation of a Th1-cell response. A novel finding was up-regulation of several regulatory and protective genes after allogeneic transplantation, specifically IL10, Bcl2a1, C4bpa, Ctla4, HO-1 and the SOCS family. CONCLUSION Our data indicate that in parallel with the predicted activation of immune response and tissue injury pathways, there is simultaneous activation of pathways for counter regulatory and protective mechanisms that would balance and limit the ongoing inflammatory/immune responses. The pathophysiological mechanisms behind and the clinical consequences of alterations in expression of these gene classes in acute rejection, injury and dysfunction vs. protection and immunoregulation, prompt further analyses and open new aspects for therapeutic approaches.
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Affiliation(s)
- Bayram Edemir
- Experimentelle Nephrologie, Medizinische Klinik und Poliklinik D, Universitätsklinikum Münster, Germany
| | - Sunil M Kurian
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Martin Eisenacher
- Integrierte Funktionelle Genomik, Interdisziplinäres Zentrum für Klinische Forschung, Universitätsklinikum Münster, Germany
| | - Detlef Lang
- Experimentelle Nephrologie, Medizinische Klinik und Poliklinik D, Universitätsklinikum Münster, Germany
| | - Carsten Müller-Tidow
- Hämatologie und Onkologie, Medizinische Klinik und Poliklinik A, Universitätsklinikum Münster, Germany
| | - Gert Gabriëls
- Experimentelle Nephrologie, Medizinische Klinik und Poliklinik D, Universitätsklinikum Münster, Germany
| | - Daniel R Salomon
- Hämatologie und Onkologie, Medizinische Klinik und Poliklinik A, Universitätsklinikum Münster, Germany
| | - Eberhard Schlatter
- Experimentelle Nephrologie, Medizinische Klinik und Poliklinik D, Universitätsklinikum Münster, Germany
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Edemir B, Reuter S, Borgulya R, Schröter R, Neugebauer U, Gabriëls G, Schlatter E. Acute rejection modulates gene expression in the collecting duct. J Am Soc Nephrol 2008; 19:538-46. [PMID: 18216318 DOI: 10.1681/asn.2007040513] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Kidney transplantation, especially when associated with acute rejection, leads to changes in the expression of many genes, including those encoding solute transporters and water channels. In a rat model of acute rejection after allogeneic renal transplantation, impaired renal function, increased urine volume, and increased fractional excretion of sodium were observed. Gene array analysis revealed that these findings were associated with significant downregulation of water channels (aquaporin-1, -2, -3, and -4) and transporters of sodium, glucose, urea, and other solutes. In addition, changes in expression of various receptors, kinases, and phosphatases that modulate the expression or activity of renal transport systems were observed. Syngeneic transplantation or treatment with cyclosporine A following allogeneic transplantation did not impair graft function but did lead to the downregulation of aquaporin-1, -3, and -4 and several solute transporters. However, expression of aquaporin-2 and the epithelial sodium channel did not change, suggesting that the downregulation of these transporters following allogeneic transplantation is rejection-dependent. In conclusion, changes in gene expression may explain the impaired handling of solute and water after allogeneic transplantation, especially during acute rejection. Treatment with cyclosporine A improves the regulation of solute and water by preventing the downregulation of aquaporin-2 and epithelial sodium channel, even though many other transporter genes remain downregulated.
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Affiliation(s)
- Bayram Edemir
- Medizinische Klinik und Poliklinik D, Experimentelle Nephrologie, Domagkstrasse 3a, 48149 Münster, Germany.
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Lang F, Böhmer C, Palmada M, Seebohm G, Strutz-Seebohm N, Vallon V. (Patho)physiological significance of the serum- and glucocorticoid-inducible kinase isoforms. Physiol Rev 2006; 86:1151-78. [PMID: 17015487 DOI: 10.1152/physrev.00050.2005] [Citation(s) in RCA: 516] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The serum- and glucocorticoid-inducible kinase-1 (SGK1) is ubiquitously expressed and under genomic control by cell stress (including cell shrinkage) and hormones (including gluco- and mineralocorticoids). Similar to its isoforms SGK2 and SGK3, SGK1 is activated by insulin and growth factors via phosphatidylinositol 3-kinase and the 3-phosphoinositide-dependent kinase PDK1. SGKs activate ion channels (e.g., ENaC, TRPV5, ROMK, Kv1.3, KCNE1/KCNQ1, GluR1, GluR6), carriers (e.g., NHE3, GLUT1, SGLT1, EAAT1-5), and the Na+-K+-ATPase. They regulate the activity of enzymes (e.g., glycogen synthase kinase-3, ubiquitin ligase Nedd4-2, phosphomannose mutase-2) and transcription factors (e.g., forkhead transcription factor FKHRL1, beta-catenin, nuclear factor kappaB). SGKs participate in the regulation of transport, hormone release, neuroexcitability, cell proliferation, and apoptosis. SGK1 contributes to Na+ retention and K+ elimination of the kidney, mineralocorticoid stimulation of salt appetite, glucocorticoid stimulation of intestinal Na+/H+ exchanger and nutrient transport, insulin-dependent salt sensitivity of blood pressure and salt sensitivity of peripheral glucose uptake, memory consolidation, and cardiac repolarization. A common ( approximately 5% prevalence) SGK1 gene variant is associated with increased blood pressure and body weight. SGK1 may thus contribute to metabolic syndrome. SGK1 may further participate in tumor growth, neurodegeneration, fibrosing disease, and the sequelae of ischemia. SGK3 is required for adequate hair growth and maintenance of intestinal nutrient transport and influences locomotive behavior. In conclusion, the SGKs cover a wide variety of physiological functions and may play an active role in a multitude of pathophysiological conditions. There is little doubt that further targets will be identified that are modulated by the SGK isoforms and that further SGK-dependent in vivo physiological functions and pathophysiological conditions will be defined.
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Affiliation(s)
- Florian Lang
- Department of Physiology, University of Tuebingen, Tuebingen, Germany.
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Liang X, Peters KW, Butterworth MB, Frizzell RA. 14-3-3 isoforms are induced by aldosterone and participate in its regulation of epithelial sodium channels. J Biol Chem 2006; 281:16323-32. [PMID: 16613846 DOI: 10.1074/jbc.m601360200] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Aldosterone increases sodium absorption across renal collecting duct cells primarily by increasing the apical membrane expression of ENaC, the sodium entry channel. Nedd4-2, a ubiquitin-protein isopeptide ligase, tags ENaC with ubiquitin for internalization and degradation, but when it is phosphorylated by the aldosterone-induced kinase, SGK1, Nedd4-2 is inhibited and apical ENaC density and sodium absorption increase. We evaluated the hypothesis that 14-3-3 proteins participate in the aldosterone-mediated regulation of ENaC by associating with phosphorylated Nedd4-2. Mouse cortical collecting duct (mCCD) epithelia cultured on filters expressed several 14-3-3 isoforms; this study focused on an isoform whose expression was induced 3-fold by aldosterone, 14-3-3beta. In polarized mCCD epithelia, aldosterone elicited significant, time-dependent increases in the expression of alpha-ENaC, SGK1, phospho-Nedd4-2, and 14-3-3beta without altering total Nedd4-2. Aldosterone decreased the interaction of alpha-ENaC with Nedd4-2, and with similar kinetics increased the association of 14-3-3beta with phospho-Nedd4-2. Short interfering RNA-induced knockdown of 14-3-3beta blunted the aldosterone-induced increase in alpha-ENaC expression, returned alpha-ENaC-Nedd4-2 binding toward prealdosterone levels, and blocked the aldosterone-stimulated increase in transepithelial sodium transport. Incubation of cell extracts with a selective phospho-Nedd4-2 antibody blocked the aldosterone-induced association of 14-3-3beta with Nedd4-2, implicating SGK1 phosphorylation at Ser-328 as the primary site of 14-3-3beta binding. Our studies show that aldosterone increases the expression of 14-3-3beta, which interacts with phospho-Nedd4-2 to block its interaction with ENaC, thus enhancing sodium absorption by increasing apical membrane ENaC density.
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Affiliation(s)
- Xiubin Liang
- Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, 3500 Terrace Street, Pittsburgh, PA 15261, USA
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