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      A new mechanism of action of sulodexide in diabetic nephropathy: inhibits heparanase-1 and prevents FGF-2-induced renal epithelial-mesenchymal transition

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          Abstract

          Background

          Epithelial-mesenchymal transition of tubular cells is a widely recognized mechanism that sustains interstitial fibrosis in diabetic nephropathy (DN). The signaling of FGF-2, a growth factor involved in this mechanism, is regulated by glycosaminoglycans. Heparanase-1, an endoglycosidase that cleaves heparan sulfate, is implicated in the pathogenesis of diabetic nephropathy and is necessary to FGF-2 for the induction of tubular cells transition. Well known Heparanase-1 inhibitors are heparin(s) and sulodexide, a low-molecular weight heparin – dermatan sulphate blend, which is effective in the treatment of DN.

          Methods

          We have investigated the inhibition by sulodexide and its components of Heparanase-1 by an ELISA assay. We have analyzed its effect on the epithelial-mesenchymal transition of tubular cells by real time gene expression analysis, zymography and migration assay.

          Results

          Results show that sulodexide is an effective heparanase-1 inhibitor, exclusively in virtue to the heparin component, with an IC50 of 5 μg/ml. In FGF-2 treated tubular cells, sulodexide also prevents the over-expression of the mesenchymal markers αSMA, vimentin and fibronectin and the motility increase, i.e. the epithelial-mesenchymal transition of tubular cells. Moreover, sulodexide prevents FGF-2 induced heparanase-1 and MMP9 increase switching off the autocrine loop that FGF-2 activates to support its signal.

          Conclusions

          The findings highlight the capacity of sulodexide to inhibit heparanase-1 and to control tubular fibrosis triggered by epithelial-mesenchymal transition. In conclusion, these sulodexide activities support the value of this agent in controlling the progression of nephropathy to renal failure.

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          Most cited references26

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          Role of basic fibroblast growth factor-2 in epithelial-mesenchymal transformation.

          Epithelial-mesenchymal transformation (EMT) plays an important role in embryonic development and tumorigenesis and has been described in organ remodeling during fibrogenesis. In the kidney, EMT can be induced efficiently in cultured proximal tubular epithelium by coincubation of transforming growth factor (TGF)-beta1 and epidermal growth factor (EGF). Recently, we also have observed overexpression of basic fibroblast growth factor-2 (FGF-2) protein and mRNA in human kidneys with marked interstitial fibrosis. The aims of the present study were to compare the effects of FGF-2 as a facilitator of EMT in tubular epithelial cells with EGF and TGF-beta1. We analyzed the morphogenic effects of the three cytokines on four different aspects of EMT: cell motility, expression and regulation of cellular markers, synthesis and secretion of extracellular matrix (ECM) proteins as well as matrix degradation. Cell motility was studied by a migration assay and cell differentiation markers were analyzed by immunofluorescence and immunoblots. In addition, regulation of the epithelial adhesion molecule E-cadherin and fibroblast-specific protein 1 (FSP1) were analyzed by luciferase reporter constructs and stable transfections. ELISAs for collagen types I and IV and fibronectin were used for ECM synthesis, and zymograms were utilized for analysis of matrix degradation. FGF-2 induced cell motility across a tubular basement membrane in two tubular cell lines. All three cytokines induced the expression of vimentin and FSP1, but only FGF-2 and TGF-beta1 reduced cytokeratin expression by immunofluorescence. These effects were most demonstrable in the distal tubular epithelial cell line and were confirmed by immunoblot analyses. Expression of E-cadherin was reduced by 61.5 +/- 3.3% and expression of cytokeratin by 91 +/- 0.5% by TGF-beta1 plus FGF-2. Conversely, the mesenchymal markers alpha-smooth muscle actin (SMA) and FSP1 were induced with FGF-2 by 2.2 +/- 0.1-fold and 6.8 +/- 0.9-fold, respectively. Interestingly, de novo expression of the mesenchymal marker OB-cadherin was induced only by FGF-2 and EGF but not by TGF-beta1. All three cytokines stimulated FSP1 and decreased E-cadherin promoter activity. FGF-2 also induced intracellular fibronectin synthesis but not secretion, the latter of which was stimulated exclusively by TGF-beta1. Finally, zymographic analyses demonstrated that FGF-2 induced MMP-2 activity by 2.6 +/- 0.5-fold and MMP-9 activity by 2.4 +/- 0.1-fold, providing a mechanism for basement membrane disintegration and migratory access of transforming epithelium to the interstitium. FGF-2 makes an important contribution to the mechanisms of EMT by stimulating microenvironmental proteases essential for disaggregation of organ-based epithelial units. Furthermore, the expression of epithelial and mesenchymal marker proteins seems to be affected at the promoter level.
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            Renal tubulointerstitial fibrosis: common but never simple.

            Regardless of etiology, all patients with chronic renal disease show a progressive decline in renal function with time. Fibrosis, so-called scarring, is a key cause of this pathophysiology. Fibrosis involves an excess accumulation of extracellular matrix (primarily composed of collagen) and usually results in loss of function when normal tissue is replaced with scar tissue. While recent major advances have led to a much better understanding of this process, many problems remain. We for instance know little about why some wounds heal and others scar and little about how many putative antifibrotic agents work. This review discusses recent advances in our understanding of the mechanisms of tubulointerstitial fibrosis, focusing on the regulation and role of the myofibroblast in this process, the role of recently recognized endogenous antifibrotic factors, controversy surrounding the effects of metalloproteinases, and the opportunities presented by new treatment strategies that abrogate and may even reverse fibrosis.
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              Heparanase Is Essential for the Development of Diabetic Nephropathy in Mice

              Diabetic nephropathy (DN) is the major life-threatening complication of diabetes. Abnormal permselectivity of glomerular basement membrane (GBM) plays an important role in DN pathogenesis. Heparanase is the predominant enzyme that degrades heparan sulfate (HS), the main polysaccharide of the GBM. Loss of GBM HS in diabetic kidney was associated with increased glomerular expression of heparanase; however, the causal involvement of heparanase in the pathogenesis of DN has not been demonstrated. We report for the first time the essential involvement of heparanase in DN. With the use of Hpse-KO mice, we found that deletion of the heparanase gene protects diabetic mice from DN. Furthermore, by investigating the molecular mechanism underlying induction of the enzyme in DN, we found that transcription factor early growth response 1 (Egr1) is responsible for activation of heparanase promoter under diabetic conditions. The specific heparanase inhibitor SST0001 markedly decreased the extent of albuminuria and renal damage in mouse models of DN. Our results collectively underscore the crucial role of heparanase in the pathogenesis of DN and its potential as a highly relevant target for therapeutic interventions in patients with DN.
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                Author and article information

                Journal
                J Transl Med
                J Transl Med
                Journal of Translational Medicine
                BioMed Central
                1479-5876
                2012
                24 October 2012
                : 10
                : 213
                Affiliations
                [1 ]Department of Biomedical Sciences, University of Padova, Padova, Italy
                [2 ]Department of Medicine, Section of Nephrology, University of Verona, Verona, Italy
                [3 ]Division of Nephrology and Dialysis, Institute of Internal Medicine and Medical Specialties, Columbus-Gemelli University Hospital, Renal Program, Catholic University, Via Moscati, 31., Rome, 00168, Italy
                Article
                1479-5876-10-213
                10.1186/1479-5876-10-213
                3562257
                23095131
                1ee03e23-76db-473c-b5ec-5fe910d32726
                Copyright ©2012 Masola et al.; licensee BioMed Central Ltd.

                This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

                History
                : 26 July 2012
                : 16 October 2012
                Categories
                Research

                Medicine
                sulodexide,tubular cells,heparanase-1,epithelial-mesenchymal transition,diabetic nephropathy,fibrosis

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