The Experts below are selected from a list of 141 Experts worldwide ranked by ideXlab platform
Yufeng Huang - One of the best experts on this subject based on the ideXlab platform.
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Inhibition of RNA-binding protein HuR reduces glomerulosclerosis in Experimental Nephritis.
Clinical science (London England : 1979), 2020Co-Authors: Simeng Liu, Zhimin Huang, Anna Tang, Jeffrey Aubé, Changying Xing, Yufeng HuangAbstract:Recent identification of an RNA-binding protein (HuR) that regulates mRNA turnover and translation of numerous transcripts via binding to an ARE in their 3'-UTR involved in inflammation and is abnormally elevated in varied kidney diseases offers a novel target for the treatment of renal inflammation and subsequent fibrosis. Thus, we hypothesized that treatment with a selective inhibition of HuR function with a small molecule, KH-3, would down-regulate HuR-targeted proinflammatory transcripts thereby improving glomerulosclerosis in Experimental Nephritis, where glomerular cellular HuR is elevated. Three Experimental groups included normal and diseased rats treated with or without KH-3. Disease was induced by the monoclonal anti-Thy 1.1 antibody. KH-3 was given via daily intraperitoneal injection from day 1 after disease induction to day 5 at the dose of 50 mg/kg BW/day. At day 6, diseased animals treated with KH-3 showed significant reduction in glomerular HuR levels, proteinuria, podocyte injury determined by ameliorated podocyte loss and podocin expression, glomerular staining for periodic acid-Schiff positive extracellular matrix proteins, fibronectin and collagen IV and mRNA and protein levels of profibrotic markers, compared with untreated disease rats. KH-3 treatment also reduced disease-induced increases in renal TGFβ1 and PAI-1 transcripts. Additionally, a marked increase in renal NF-κB-p65, Nox4, and glomerular macrophage cell infiltration observed in disease control group was largely reversed by KH-3 treatment. These results strongly support our hypothesis that down-regulation of HuR function with KH-3 has therapeutic potential for reversing glomerulosclerosis by reducing abundance of pro-inflammatory transcripts and related inflammation.
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Combining angiotensin II blockade and renin receptor inhibition results in enhanced antifibrotic effect in Experimental Nephritis
American journal of physiology. Renal physiology, 2011Co-Authors: Jiandong Zhang, Nancy A. Noble, Wayne A. Border, Yufeng HuangAbstract:The limited antifibrotic effect of therapeutic angiotensin blockade, the fact that angiotensin blockade dramatically elevates renin levels, and recent evidence that renin has an angiotensin-independent, receptor-mediated profibrotic action led us to hypothesize that combining renin receptor inhibition and ANG II blockade would increase the antifibrotic effect of angiotensin blockade alone. Using cultured nephritic glomeruli from rats with anti-Thy-1-induced glomeruloNephritis, the maximally effective dose of enalaprilate was determined to be 10(-4) M, which reduced mRNAs for transforming growth factor (TGF)-β1, fibronectin (FN), and plasminogen activator inhibitor-1 (PAI-1) by 49, 65, and 56% and production of TGF-β1 and FN proteins by 60 and 49%, respectively. Disease alone caused 6.8-fold increases in ANG II levels that were reduced 64% with enalaprilate. In contrast, two- and threefold disease-induced increases in renin mRNA and activity were further increased 2- and 3.7-fold with 10(-4) M enalaprilate treatment. Depressing the renin receptor by 80% with small interfering (si) RNA alone reduced fibrotic markers in a manner remarkably similar to enalaprilate alone but had no effect on glomerular renin expression. Enalaprilate and siRNA combination therapy further reduced disease markers. Notably, elevated TGF-β1 and FN production was reduced by 73 and 81%, respectively. These results support the notion of a receptor-mediated profibrotic action of renin, suggest that the limited effectiveness of ANG II blockade may be due, at least in part, to the elevated renin they induce, and support our hypothesis that adding renin receptor inhibitor to ANG II blockade in patients may have therapeutic potential.
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Mechanisms underlying the antifibrotic properties of noninhibitory PAI-1 (PAI-1R) in Experimental Nephritis
American journal of physiology. Renal physiology, 2009Co-Authors: Yufeng Huang, Wayne A. Border, Daniel A. Lawrence, Nancy A. NobleAbstract:Administration of a mutant, noninhibitory PAI-1 (PAI-1R), reduces disease in Experimental glomeruloNephritis. Here we investigated the importance of vitronectin (Vn) binding, PAI-1 stability and protease binding in this therapeutic effect using a panel of PAI-1 mutants differing in half-life, protease binding, and Vn binding. PAI-1R binds Vn normally but does not inhibit proteases. PAI-1AK has a complete defect in Vn binding but retains full inhibitory activity, with a short half-life similar to wild-type (wt)-PAI-1. Mutant 14-lb is identical to wt-PAI-1 but with a longer half-life. PAI-1K has defective Vn binding, inhibits proteases normally, and has a long half-life. In vitro wt-PAI-1 dramatically inhibited degradation of mesangial cell ECM while the AK mutant had much less effect. Mutants 14-1b and PAI-1K, like wt-PAI-1, inhibited matrix degradation but PAI-1R failed to reverse this inhibition although PAI-1R reversed the wt-PAI-1-induced inhibition of ECM degradation in a plasmin-, time-, and dose-dependent manner. Thus the ability of PAI-1 to inhibit ECM degradation is dependent both on its antiproteinase activity and on maintaining an active conformation achieved either by Vn binding or mutation to a stable form. Administration of these PAI-1 mutants to nephritic rats confirmed the in vitro data; only PAI-1R showed therapeutic effects. PAI-1K did not bind to nephritic kidney, indicating that Vn binding is essential to the therapeutic action of PAI-1R. The ability of PAI-1R to remain bound to Vn even in a high-protease environment is very likely the key to its therapeutic efficacy. Furthermore, because both PAI-1R and 14-1b bound to the nephritic kidney in the same pattern and differ only in their ability to bind proteases, lack of protease inhibition is also keyed to PAI-1R's therapeutic action.
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noninhibitory pai 1 enhances plasmin mediated matrix degradation both in vitro and in Experimental Nephritis
Kidney International, 2006Co-Authors: Yufeng Huang, Wayne A. Border, Daniel A. Lawrence, Nancy A. NobleAbstract:Plasminogen activator inhibitor-type 1 (PAI-1) is thought to be profibrotic by inhibiting plasmin generation, thereby decreasing turnover of pathological extracellular matrix (ECM). A mutant, noninhibitory PAI-1 (PAI-1R) was recently shown by us to increase glomerular plasmin generation and reduce disease in anti-thy-1 Nephritis. Here, in vitro and in vivo studies were performed to determine whether enhanced plasmin-dependent ECM degradation underlies the therapeutic effect of PAI-1R. 3H-labeled ECM was produced by rat mesangial cells (MCs). The effect of wild-type PAI-1 (wt-PAI-1) and PAI-1R on ECM degradation by newly plated MCs was measured by the release of 3H into medium. In vivo, anti-thy-1 Nephritis was assessed in normal, untreated diseased and PAI-1R treated rats with or without the plasmin/plasminogen inhibitor, tranexamic acid (TA). wt-PAI-1 totally inhibited plasmin generation and reduced ECM degradation by 76% when exogenous plasminogen was added. Although PAI-1R alone had no effect, PAI-1R in the presence of wt-PAI-1 reversed the wt-PAI-1 inhibition of ECM degradation in a time- and dose-dependent manner (P<0.001). Plasmin activity and zymography were consistent with ECM degradation. Plasmin inhibitors: alpha2-antiplasmin, aprotinin, and TA completely blocked PAI-1R's ability to normalize ECM degradation (P<0.001). Consistent with the in vitro results, TA reversed PAI-1R-induced reductions in glomerular fibrin and ECM accumulation. Other measures of disease severity were either unaltered or partially reversed. PAI-1R reduces pathological ECM accumulation, in large part through effectively competing with native PAI-1 thereby restoring plasmin generation and increasing plasmin-dependent degradation of matrix components.
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Noninhibitory PAI-1 enhances plasmin-mediated matrix degradation both in vitro and in Experimental Nephritis.
Kidney international, 2006Co-Authors: Yufeng Huang, Wayne A. Border, Daniel A. Lawrence, Nancy A. NobleAbstract:Plasminogen activator inhibitor-type 1 (PAI-1) is thought to be profibrotic by inhibiting plasmin generation, thereby decreasing turnover of pathological extracellular matrix (ECM). A mutant, noninhibitory PAI-1 (PAI-1R) was recently shown by us to increase glomerular plasmin generation and reduce disease in anti-thy-1 Nephritis. Here, in vitro and in vivo studies were performed to determine whether enhanced plasmin-dependent ECM degradation underlies the therapeutic effect of PAI-1R. 3H-labeled ECM was produced by rat mesangial cells (MCs). The effect of wild-type PAI-1 (wt-PAI-1) and PAI-1R on ECM degradation by newly plated MCs was measured by the release of 3H into medium. In vivo, anti-thy-1 Nephritis was assessed in normal, untreated diseased and PAI-1R treated rats with or without the plasmin/plasminogen inhibitor, tranexamic acid (TA). wt-PAI-1 totally inhibited plasmin generation and reduced ECM degradation by 76% when exogenous plasminogen was added. Although PAI-1R alone had no effect, PAI-1R in the presence of wt-PAI-1 reversed the wt-PAI-1 inhibition of ECM degradation in a time- and dose-dependent manner (P
Peter R. Mertens - One of the best experts on this subject based on the ideXlab platform.
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extracellular yb 1 blockade in Experimental Nephritis upregulates notch 3 receptor expression and signaling
Nephron Experimental Nephrology, 2011Co-Authors: Ute Raffetseder, Sonja Djudjaj, Peter Boor, Lydia Hanssen, Thomas Rauen, Björn C. Frye, Tammo Ostendorf, Jurgen Floege, Abdelaziz Ennia, Peter R. MertensAbstract:Background: Notch receptors are involved in kidney development and pathogenesis of inflammatory glomerular diseases. Given the secretion of Y- box (YB) protein-1 f
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YB-1 Acts as a Ligand for Notch-3 Receptors and Modulates Receptor Activation
The Journal of biological chemistry, 2009Co-Authors: Thomas Rauen, Sonja Djudjaj, Ute Raffetseder, Björn C. Frye, Philipp J.t. Mühlenberg, Frank Eitner, Urban Lendahl, Jürgen Bernhagen, Steven Dooley, Peter R. MertensAbstract:Y-box (YB) protein-1 is secreted by mesangial and immune cells after cytokine challenge, but extracellular functions are unknown. Here, we demonstrate that extracellular YB-1 associates with outer cell membrane components and interacts with extracellular Notch-3 receptor domains. The interaction appears to be specific for Notch-3, as YB-1-green fluorescent protein binds to the extracellular domains and full-length forms of Notch-3 but not to Notch-1. YB-1-green fluorescent protein and Notch-3 proteins co-localize at cell membranes, and extracellular YB-1 activates Notch-3 signaling, resulting in nuclear translocation of the Notch-3 intracellular domain and up-regulation of Notch target genes. The YB-1/Notch-3 interaction may be of particular relevance for inflammatory mesangioproliferative disease, as both proteins co-localize in an Experimental Nephritis model and receptor activation temporally and spatially correlates with YB-1 expression.
Nancy A. Noble - One of the best experts on this subject based on the ideXlab platform.
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Combining angiotensin II blockade and renin receptor inhibition results in enhanced antifibrotic effect in Experimental Nephritis
American journal of physiology. Renal physiology, 2011Co-Authors: Jiandong Zhang, Nancy A. Noble, Wayne A. Border, Yufeng HuangAbstract:The limited antifibrotic effect of therapeutic angiotensin blockade, the fact that angiotensin blockade dramatically elevates renin levels, and recent evidence that renin has an angiotensin-independent, receptor-mediated profibrotic action led us to hypothesize that combining renin receptor inhibition and ANG II blockade would increase the antifibrotic effect of angiotensin blockade alone. Using cultured nephritic glomeruli from rats with anti-Thy-1-induced glomeruloNephritis, the maximally effective dose of enalaprilate was determined to be 10(-4) M, which reduced mRNAs for transforming growth factor (TGF)-β1, fibronectin (FN), and plasminogen activator inhibitor-1 (PAI-1) by 49, 65, and 56% and production of TGF-β1 and FN proteins by 60 and 49%, respectively. Disease alone caused 6.8-fold increases in ANG II levels that were reduced 64% with enalaprilate. In contrast, two- and threefold disease-induced increases in renin mRNA and activity were further increased 2- and 3.7-fold with 10(-4) M enalaprilate treatment. Depressing the renin receptor by 80% with small interfering (si) RNA alone reduced fibrotic markers in a manner remarkably similar to enalaprilate alone but had no effect on glomerular renin expression. Enalaprilate and siRNA combination therapy further reduced disease markers. Notably, elevated TGF-β1 and FN production was reduced by 73 and 81%, respectively. These results support the notion of a receptor-mediated profibrotic action of renin, suggest that the limited effectiveness of ANG II blockade may be due, at least in part, to the elevated renin they induce, and support our hypothesis that adding renin receptor inhibitor to ANG II blockade in patients may have therapeutic potential.
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Mechanisms underlying the antifibrotic properties of noninhibitory PAI-1 (PAI-1R) in Experimental Nephritis
American journal of physiology. Renal physiology, 2009Co-Authors: Yufeng Huang, Wayne A. Border, Daniel A. Lawrence, Nancy A. NobleAbstract:Administration of a mutant, noninhibitory PAI-1 (PAI-1R), reduces disease in Experimental glomeruloNephritis. Here we investigated the importance of vitronectin (Vn) binding, PAI-1 stability and protease binding in this therapeutic effect using a panel of PAI-1 mutants differing in half-life, protease binding, and Vn binding. PAI-1R binds Vn normally but does not inhibit proteases. PAI-1AK has a complete defect in Vn binding but retains full inhibitory activity, with a short half-life similar to wild-type (wt)-PAI-1. Mutant 14-lb is identical to wt-PAI-1 but with a longer half-life. PAI-1K has defective Vn binding, inhibits proteases normally, and has a long half-life. In vitro wt-PAI-1 dramatically inhibited degradation of mesangial cell ECM while the AK mutant had much less effect. Mutants 14-1b and PAI-1K, like wt-PAI-1, inhibited matrix degradation but PAI-1R failed to reverse this inhibition although PAI-1R reversed the wt-PAI-1-induced inhibition of ECM degradation in a plasmin-, time-, and dose-dependent manner. Thus the ability of PAI-1 to inhibit ECM degradation is dependent both on its antiproteinase activity and on maintaining an active conformation achieved either by Vn binding or mutation to a stable form. Administration of these PAI-1 mutants to nephritic rats confirmed the in vitro data; only PAI-1R showed therapeutic effects. PAI-1K did not bind to nephritic kidney, indicating that Vn binding is essential to the therapeutic action of PAI-1R. The ability of PAI-1R to remain bound to Vn even in a high-protease environment is very likely the key to its therapeutic efficacy. Furthermore, because both PAI-1R and 14-1b bound to the nephritic kidney in the same pattern and differ only in their ability to bind proteases, lack of protease inhibition is also keyed to PAI-1R's therapeutic action.
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noninhibitory pai 1 enhances plasmin mediated matrix degradation both in vitro and in Experimental Nephritis
Kidney International, 2006Co-Authors: Yufeng Huang, Wayne A. Border, Daniel A. Lawrence, Nancy A. NobleAbstract:Plasminogen activator inhibitor-type 1 (PAI-1) is thought to be profibrotic by inhibiting plasmin generation, thereby decreasing turnover of pathological extracellular matrix (ECM). A mutant, noninhibitory PAI-1 (PAI-1R) was recently shown by us to increase glomerular plasmin generation and reduce disease in anti-thy-1 Nephritis. Here, in vitro and in vivo studies were performed to determine whether enhanced plasmin-dependent ECM degradation underlies the therapeutic effect of PAI-1R. 3H-labeled ECM was produced by rat mesangial cells (MCs). The effect of wild-type PAI-1 (wt-PAI-1) and PAI-1R on ECM degradation by newly plated MCs was measured by the release of 3H into medium. In vivo, anti-thy-1 Nephritis was assessed in normal, untreated diseased and PAI-1R treated rats with or without the plasmin/plasminogen inhibitor, tranexamic acid (TA). wt-PAI-1 totally inhibited plasmin generation and reduced ECM degradation by 76% when exogenous plasminogen was added. Although PAI-1R alone had no effect, PAI-1R in the presence of wt-PAI-1 reversed the wt-PAI-1 inhibition of ECM degradation in a time- and dose-dependent manner (P<0.001). Plasmin activity and zymography were consistent with ECM degradation. Plasmin inhibitors: alpha2-antiplasmin, aprotinin, and TA completely blocked PAI-1R's ability to normalize ECM degradation (P<0.001). Consistent with the in vitro results, TA reversed PAI-1R-induced reductions in glomerular fibrin and ECM accumulation. Other measures of disease severity were either unaltered or partially reversed. PAI-1R reduces pathological ECM accumulation, in large part through effectively competing with native PAI-1 thereby restoring plasmin generation and increasing plasmin-dependent degradation of matrix components.
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Noninhibitory PAI-1 enhances plasmin-mediated matrix degradation both in vitro and in Experimental Nephritis.
Kidney international, 2006Co-Authors: Yufeng Huang, Wayne A. Border, Daniel A. Lawrence, Nancy A. NobleAbstract:Plasminogen activator inhibitor-type 1 (PAI-1) is thought to be profibrotic by inhibiting plasmin generation, thereby decreasing turnover of pathological extracellular matrix (ECM). A mutant, noninhibitory PAI-1 (PAI-1R) was recently shown by us to increase glomerular plasmin generation and reduce disease in anti-thy-1 Nephritis. Here, in vitro and in vivo studies were performed to determine whether enhanced plasmin-dependent ECM degradation underlies the therapeutic effect of PAI-1R. 3H-labeled ECM was produced by rat mesangial cells (MCs). The effect of wild-type PAI-1 (wt-PAI-1) and PAI-1R on ECM degradation by newly plated MCs was measured by the release of 3H into medium. In vivo, anti-thy-1 Nephritis was assessed in normal, untreated diseased and PAI-1R treated rats with or without the plasmin/plasminogen inhibitor, tranexamic acid (TA). wt-PAI-1 totally inhibited plasmin generation and reduced ECM degradation by 76% when exogenous plasminogen was added. Although PAI-1R alone had no effect, PAI-1R in the presence of wt-PAI-1 reversed the wt-PAI-1 inhibition of ECM degradation in a time- and dose-dependent manner (P
Tilmann Ditting - One of the best experts on this subject based on the ideXlab platform.
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Neurogenic tachykinin mechanisms in Experimental Nephritis of rats
Pflügers Archiv - European Journal of Physiology, 2020Co-Authors: Kristina Rodionova, Karl F. Hilgers, Eva-maria Paulus, Gisa Tiegs, Christian Ott, Roland Schmieder, Mario Schiffer, Kerstin Amann, Roland Veelken, Tilmann DittingAbstract:We demonstrated earlier that renal afferent pathways combine very likely “classical” neural signal transduction to the central nervous system and a substance P (SP)–dependent mechanism to control sympathetic activity. SP content of afferent sensory neurons is known to mediate neurogenic inflammation upon release. We tested the hypothesis that alterations in SP-dependent mechanisms of renal innervation contribute to Experimental Nephritis. Nephritis was induced by OX-7 antibodies in rats, 6 days later instrumented for recording of blood pressure (BP), heart rate (HR), drug administration, and intrarenal administration (IRA) of the TRPV1 agonist capsaicin to stimulate afferent renal nerve pathways containing SP and electrodes for renal sympathetic nerve activity (RSNA). The presence of the SP receptor NK-1 on renal immune cells was assessed by FACS. IRA capsaicin decreased RSNA from 62.4 ± 5.1 to 21.6 ± 1.5 mV s (* p
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neurogenic tachykinin mechanisms in Experimental Nephritis of rats
Pflügers Archiv: European Journal of Physiology, 2020Co-Authors: Kristina Rodionova, Karl F. Hilgers, Eva-maria Paulus, Gisa Tiegs, Christian Ott, Mario Schiffer, Kerstin Amann, Roland Veelken, Roland E Schmieder, Tilmann DittingAbstract:We demonstrated earlier that renal afferent pathways combine very likely "classical" neural signal transduction to the central nervous system and a substance P (SP)-dependent mechanism to control sympathetic activity. SP content of afferent sensory neurons is known to mediate neurogenic inflammation upon release. We tested the hypothesis that alterations in SP-dependent mechanisms of renal innervation contribute to Experimental Nephritis. Nephritis was induced by OX-7 antibodies in rats, 6 days later instrumented for recording of blood pressure (BP), heart rate (HR), drug administration, and intrarenal administration (IRA) of the TRPV1 agonist capsaicin to stimulate afferent renal nerve pathways containing SP and electrodes for renal sympathetic nerve activity (RSNA). The presence of the SP receptor NK-1 on renal immune cells was assessed by FACS. IRA capsaicin decreased RSNA from 62.4 ± 5.1 to 21.6 ± 1.5 mV s (*p < 0.05) in controls, a response impaired in Nephritis. Suppressed RSNA transiently but completely recovered after systemic administration of a neurokinin 1 (NK1-R) blocker. NK-1 receptors occurred mainly on CD11+ dendritic cells (DCs). An enhanced frequency of CD11c+NK1R+ cell, NK-1 receptor+ macrophages, and DCs was assessed in Nephritis. Administration of the NK-1R antagonist aprepitant during Nephritis reduced CD11c+NK1R+ cells, macrophage infiltration, renal expression of chemokines, and markers of sclerosis. Hence, SP promoted renal inflammation by weakening sympathoinhibitory mechanisms, while at the same time, substance SP released intrarenally from afferent nerve fibers aggravated immunological processes i.e. by the recruitment of DCs.
Wayne A. Border - One of the best experts on this subject based on the ideXlab platform.
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Combining angiotensin II blockade and renin receptor inhibition results in enhanced antifibrotic effect in Experimental Nephritis
American journal of physiology. Renal physiology, 2011Co-Authors: Jiandong Zhang, Nancy A. Noble, Wayne A. Border, Yufeng HuangAbstract:The limited antifibrotic effect of therapeutic angiotensin blockade, the fact that angiotensin blockade dramatically elevates renin levels, and recent evidence that renin has an angiotensin-independent, receptor-mediated profibrotic action led us to hypothesize that combining renin receptor inhibition and ANG II blockade would increase the antifibrotic effect of angiotensin blockade alone. Using cultured nephritic glomeruli from rats with anti-Thy-1-induced glomeruloNephritis, the maximally effective dose of enalaprilate was determined to be 10(-4) M, which reduced mRNAs for transforming growth factor (TGF)-β1, fibronectin (FN), and plasminogen activator inhibitor-1 (PAI-1) by 49, 65, and 56% and production of TGF-β1 and FN proteins by 60 and 49%, respectively. Disease alone caused 6.8-fold increases in ANG II levels that were reduced 64% with enalaprilate. In contrast, two- and threefold disease-induced increases in renin mRNA and activity were further increased 2- and 3.7-fold with 10(-4) M enalaprilate treatment. Depressing the renin receptor by 80% with small interfering (si) RNA alone reduced fibrotic markers in a manner remarkably similar to enalaprilate alone but had no effect on glomerular renin expression. Enalaprilate and siRNA combination therapy further reduced disease markers. Notably, elevated TGF-β1 and FN production was reduced by 73 and 81%, respectively. These results support the notion of a receptor-mediated profibrotic action of renin, suggest that the limited effectiveness of ANG II blockade may be due, at least in part, to the elevated renin they induce, and support our hypothesis that adding renin receptor inhibitor to ANG II blockade in patients may have therapeutic potential.
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Mechanisms underlying the antifibrotic properties of noninhibitory PAI-1 (PAI-1R) in Experimental Nephritis
American journal of physiology. Renal physiology, 2009Co-Authors: Yufeng Huang, Wayne A. Border, Daniel A. Lawrence, Nancy A. NobleAbstract:Administration of a mutant, noninhibitory PAI-1 (PAI-1R), reduces disease in Experimental glomeruloNephritis. Here we investigated the importance of vitronectin (Vn) binding, PAI-1 stability and protease binding in this therapeutic effect using a panel of PAI-1 mutants differing in half-life, protease binding, and Vn binding. PAI-1R binds Vn normally but does not inhibit proteases. PAI-1AK has a complete defect in Vn binding but retains full inhibitory activity, with a short half-life similar to wild-type (wt)-PAI-1. Mutant 14-lb is identical to wt-PAI-1 but with a longer half-life. PAI-1K has defective Vn binding, inhibits proteases normally, and has a long half-life. In vitro wt-PAI-1 dramatically inhibited degradation of mesangial cell ECM while the AK mutant had much less effect. Mutants 14-1b and PAI-1K, like wt-PAI-1, inhibited matrix degradation but PAI-1R failed to reverse this inhibition although PAI-1R reversed the wt-PAI-1-induced inhibition of ECM degradation in a plasmin-, time-, and dose-dependent manner. Thus the ability of PAI-1 to inhibit ECM degradation is dependent both on its antiproteinase activity and on maintaining an active conformation achieved either by Vn binding or mutation to a stable form. Administration of these PAI-1 mutants to nephritic rats confirmed the in vitro data; only PAI-1R showed therapeutic effects. PAI-1K did not bind to nephritic kidney, indicating that Vn binding is essential to the therapeutic action of PAI-1R. The ability of PAI-1R to remain bound to Vn even in a high-protease environment is very likely the key to its therapeutic efficacy. Furthermore, because both PAI-1R and 14-1b bound to the nephritic kidney in the same pattern and differ only in their ability to bind proteases, lack of protease inhibition is also keyed to PAI-1R's therapeutic action.
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noninhibitory pai 1 enhances plasmin mediated matrix degradation both in vitro and in Experimental Nephritis
Kidney International, 2006Co-Authors: Yufeng Huang, Wayne A. Border, Daniel A. Lawrence, Nancy A. NobleAbstract:Plasminogen activator inhibitor-type 1 (PAI-1) is thought to be profibrotic by inhibiting plasmin generation, thereby decreasing turnover of pathological extracellular matrix (ECM). A mutant, noninhibitory PAI-1 (PAI-1R) was recently shown by us to increase glomerular plasmin generation and reduce disease in anti-thy-1 Nephritis. Here, in vitro and in vivo studies were performed to determine whether enhanced plasmin-dependent ECM degradation underlies the therapeutic effect of PAI-1R. 3H-labeled ECM was produced by rat mesangial cells (MCs). The effect of wild-type PAI-1 (wt-PAI-1) and PAI-1R on ECM degradation by newly plated MCs was measured by the release of 3H into medium. In vivo, anti-thy-1 Nephritis was assessed in normal, untreated diseased and PAI-1R treated rats with or without the plasmin/plasminogen inhibitor, tranexamic acid (TA). wt-PAI-1 totally inhibited plasmin generation and reduced ECM degradation by 76% when exogenous plasminogen was added. Although PAI-1R alone had no effect, PAI-1R in the presence of wt-PAI-1 reversed the wt-PAI-1 inhibition of ECM degradation in a time- and dose-dependent manner (P<0.001). Plasmin activity and zymography were consistent with ECM degradation. Plasmin inhibitors: alpha2-antiplasmin, aprotinin, and TA completely blocked PAI-1R's ability to normalize ECM degradation (P<0.001). Consistent with the in vitro results, TA reversed PAI-1R-induced reductions in glomerular fibrin and ECM accumulation. Other measures of disease severity were either unaltered or partially reversed. PAI-1R reduces pathological ECM accumulation, in large part through effectively competing with native PAI-1 thereby restoring plasmin generation and increasing plasmin-dependent degradation of matrix components.
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Noninhibitory PAI-1 enhances plasmin-mediated matrix degradation both in vitro and in Experimental Nephritis.
Kidney international, 2006Co-Authors: Yufeng Huang, Wayne A. Border, Daniel A. Lawrence, Nancy A. NobleAbstract:Plasminogen activator inhibitor-type 1 (PAI-1) is thought to be profibrotic by inhibiting plasmin generation, thereby decreasing turnover of pathological extracellular matrix (ECM). A mutant, noninhibitory PAI-1 (PAI-1R) was recently shown by us to increase glomerular plasmin generation and reduce disease in anti-thy-1 Nephritis. Here, in vitro and in vivo studies were performed to determine whether enhanced plasmin-dependent ECM degradation underlies the therapeutic effect of PAI-1R. 3H-labeled ECM was produced by rat mesangial cells (MCs). The effect of wild-type PAI-1 (wt-PAI-1) and PAI-1R on ECM degradation by newly plated MCs was measured by the release of 3H into medium. In vivo, anti-thy-1 Nephritis was assessed in normal, untreated diseased and PAI-1R treated rats with or without the plasmin/plasminogen inhibitor, tranexamic acid (TA). wt-PAI-1 totally inhibited plasmin generation and reduced ECM degradation by 76% when exogenous plasminogen was added. Although PAI-1R alone had no effect, PAI-1R in the presence of wt-PAI-1 reversed the wt-PAI-1 inhibition of ECM degradation in a time- and dose-dependent manner (P
