Elevated urine heparanase levels are associated with proteinuria and decreased renal allograft function

Proteomic analyses of urinary exosomes identify novel potential biomarkers for early diagnosis of sickle cell nephropathy, a sex-based study

Sickle cell nephropathy (SCN) is a leading cause of morbidity and mortality in sickle cell disease (SCD). Early intervention is crucial for mitigating its effects. However, current diagnostic methods rely on generic tests and may not detect SCN until irreversible renal damage occurs. Therefore, specific biomarkers for early diagnosis of SCN are needed. Urinary exosomes, membrane-bound vesicles secreted by renal podocytes and epithelial cells, contain both common and cell type-specific membrane and cytosolic proteins, reflecting the physiologic and pathophysiologic states of the kidney. Using proteomics, we analyzed the proteomes of urinary exosomes from humanized SCD mice at 2 months (without albuminuria) and 4 months (with albuminuria) of age. Excretion of 164 proteins were significantly increased and 176 proteins was significantly decreased in the exosomes when mice developed albuminuria. Based on the relevance to SCD, chronic kidney disease and Western blot confirmation in mice, we analyzed protein abundance of heparanase, cathepsin C, α2-macroglobulin and sarcoplasmic endoplasmic Ca2+ ATPase-3 (SERCA3) in the urinary exosomes and urine of 18 SCD subjects without albuminuria and 12 subjects with albuminuria using Western blot analyses. Both male and female subjects increased or tended to increase the excretion of these proteins in their urinary exosomes upon developing albuminuria, but female subjects demonstrated stronger correlations between the excretion of these proteins and urine albumin creatinine ratio (UACR) compared to male subjects. In contrast, exosomal excretion of Tamm-Horsfall protein, β-actin and SHP-1 was independent of albuminuria. These findings provide a foundation for a time-course study to determine whether increases in the levels of these proteins precede the onset of albuminuria in patients, which will help determine the potential of these proteins as biomarkers for early detection of SCN.

Plasma glycocalyx pattern: a mirror of endothelial damage in chronic kidney disease

Background

Endothelial damage and cardiovascular disease complicate chronic kidney disease (CKD). The increased atherogenicity observed in patients with CKD can be linked to microinflammation and endothelial damage. Circulating endothelial glycocalyx degradation products, such as perlecan and decorin, tend to be elevated in CKD. We aimed to explore the association between the plasma perlecan and decorin levels and this pro-inflammatory and atherogenic state by studying monocyte subpopulations and intracellular adhesion molecule (ICAM)-1 expression in patients with CKD.

Methods

We studied 17 healthy controls, 23 patients with advanced CKD, 25 patients on haemodialysis, 23 patients on peritoneal dialysis and 20 patients who underwent kidney transplantation. Perlecan and decorin levels were evaluated using enzyme-linked immunosorbent assays, and the monocyte phenotype was analysed using direct immunofluorescence and flow cytometry.

Results

The plasma perlecan levels were higher in patients with CKD than in the healthy controls. These levels were associated with a higher prevalence of ICAM-1+ monocytes. Conversely, patients with advanced CKD (pre-dialysis) had higher plasma decorin levels, which were associated with a reduced ICAM-1 expression per monocyte.

Conclusions

Elevated perlecan levels in CKD may be associated with a higher prevalence of ICAM-1+ monocytes and a pro-inflammatory phenotype. Elevated decorin levels may act as a negative regulator of ICAM-1 expression in monocytes. Therefore, perlecan and decorin may be related to inflammation and monocyte activation in CKD and may act as potential markers of endothelial damage.

Design of an Ultralow Molecular Weight Heparin That Resists Heparanase Biodegradation

Heparanase, an endo-β-d-glucuronidase produced by a variety of cells and tissues, cleaves the glycosidic linkage between glucuronic acid (GlcA) and a 3-O- or 6-O-sulfated glucosamine, typified by the disaccharide -[GlcA-GlcNS3S6S]-, which is found within the antithrombin-binding domain of heparan sulfate or heparin. As such, all current forms of heparin are susceptible to degradation by heparanase with neutralization of anticoagulant properties. Here, we have designed a heparanase-resistant, ultralow molecular weight heparin as the structural analogue of fondaparinux that does not contain an internal GlcA residue but otherwise displays potent anticoagulant activity. This heparin oligosaccharide was synthesized following a chemoenzymatic scheme and displays nanomolar anti-FXa activity yet is resistant to heparanase digestion. Inhibition of thrombus formation was further demonstrated after subcutaneous administration of this compound in a murine model of venous thrombosis. Thrombus inhibition was comparable to that observed for enoxaparin with a similar effect on bleeding time.

Assessment of the Role of Urinary Heparanase in Lupus Nephritis Patients and Its Correlation with Disease Activity

Assessing the activity of lupus nephritis (LN) with novel biomarkers is a promising noninvasive diagnostic tool for managing systemic lupus erythematosus (SLE). We assessed the ability of urinary heparanase to identify LN and its relation to the disease's activity. This crosssectional study had 90 subjects: 70 patients with SLE and 20 healthy controls. A full medical history, clinical examination, and routine investigations were carried out for the patients and controls. Immunological assays and assessments of the disease's activity with the SLE Disease Activity Index (SLEDAI) and the renal SLEDAI (r-SLEDAI) were carried out for LN groups. Urinary heparanase levels were measured using an enzyme-linked immunosorbent assay for all subjects. Of our patients, 20 had active LN, 17 had nonactive LN, 18 had active lupus without renal involvement, and 15 had nonactive lupus without renal involvement. The level of urinary heparanase was significantly higher in the LN groups than in the non-LN groups and the controls and was significantly higher in those with active LN than in those with nonactive LN. There were significant positive correlations between urinary heparanase and 24-h urinary protein, total SLEDAI, and r-SLEDAI, and significant negative correlations between urinary heparanase and Complements 3 and 4. Urinary heparanase predicted the activity of LN with a sensitivity of 80% and a specificity of 91.43%. Urinary heparanase levels were higher in patients with active LN and correlated with the markers of disease activity, indicating that it can serve as a useful new biomarker for the activity of LN.

Heparanase Increases Podocyte Survival and Autophagic Flux after Adriamycin-Induced Injury

The kidney glomerular filtration barrier (GFB) is enriched with heparan sulfate (HS) proteoglycans, which contribute to its permselectivity. The endoglycosidase heparanase cleaves HS and hence appears to be involved in the pathogenesis of kidney injury and glomerulonephritis. We have recently reported, nonetheless, that heparanase overexpression preserved glomerular structure and kidney function in an experimental model of Adriamycin-induced nephropathy. To elucidate mechanisms underlying heparanase function in podocytes-key GFB cells, we utilized a human podocyte cell line and transgenic mice overexpressing heparanase. Notably, podocytes overexpressing heparanase (H) demonstrated significantly higher survival rates and viability after exposure to Adriamycin or hydrogen peroxide, compared with mock-infected (V) podocytes. Immunofluorescence staining of kidney cryo-sections and cultured H and V podocytes as well as immunoblotting of proteins extracted from cultured cells, revealed that exposure to toxic injury resulted in a significant increase in autophagic flux in H podocytes, which was reversed by the heparanase inhibitor, Roneparstat (SST0001). Heparanase overexpression was also associated with substantial transcriptional upregulation of autophagy genes BCN1, ATG5, and ATG12, following Adriamycin treatment. Moreover, cleaved caspase-3 was attenuated in H podocytes exposed to Adriamycin, indicating lower apoptotic cell death in H vs. V podocytes. Collectively, these findings suggest that in podocytes, elevated levels of heparanase promote cytoprotection.

Heparanase as a potential player in SARS-CoV-2 infection and induced coagulopathy

During the current formidable COVID-19 pandemic, it is appealing to address ideas that may invoke therapeutic interventions. Clotting disorders are well recognized in patients infected with severe acute respiratory syndrome (SARS) caused by a novel coronavirus (SARS-CoV-2), which lead to severe complications that worsen the prognosis in these subjects. Increasing evidence implicate Heparan sulfate proteoglycans (HSPGs) and Heparanase in various diseases and pathologies, including hypercoagulability states. Moreover, HSPGs and Heparanase are involved in several viral infections, in which they enhance cell entry and release of the viruses. Herein we discuss the molecular involvement of HSPGs and heparanase in SARS-CoV-2 infection, namely cell entry and release, and the accompanied coagulopathy complications, which assumedly could be blocked by heparanase inhibitors such as Heparin and Pixatimod.

A rechargeable anti-thrombotic coating for blood-contacting devices

Despite the potential of anti-thrombogenic coatings, including heparinized surfaces, to improve the performance of blood-contacting devices, the inevitable deterioration of bioactivity remains an important factor in device failure and related thrombotic complications. As a consequence, the ability to restore the bioactivity of a surface coating after implantation of a blood-contacting device provides a potentially important strategy to enhance its clinical performance. Here, we report the regeneration of a multicomponent anti-thrombogenic coating through use of an evolved sortase A to mediate reversible transpeptidation. Both recombinant thrombomodulin and a chemoenzymatically synthesized ultra-low molecular weight heparin were repeatedly and selectively immobilized or removed in a sequential, alternating, or simultaneous manner. The generation of activated protein C (aPC) and inhibition of activated factor X (FXa) was consistent with the molecular composition of the surface. The fabrication of a rechargeable anti-thrombogenic surface was demonstrated on an expanded polytetrafluoroethylene (ePTFE) vascular graft with reconstitution of the surface bound coating 4 weeks after in vivo implantation in a rat model.

Heparan Sulfate Proteoglycans in Diabetes

Diabetes is a complex disorder responsible for the mortality and morbidity of millions of individuals worldwide. Although many approaches have been used to understand and treat diabetes, the role of proteoglycans, in particular heparan sulfate proteoglycans (HSPGs), has only recently received attention. The HSPGs are heterogeneous, highly negatively charged, and are found in all cells primarily attached to the plasma membrane or present in the extracellular matrix (ECM). HSPGs are involved in development, cell migration, signal transduction, hemostasis, inflammation, and antiviral activity, and regulate cytokines, chemokines, growth factors, and enzymes. Hyperglycemia, accompanying diabetes, increases reactive oxygen species and upregulates the enzyme heparanase that degrades HSPGs or affects the synthesis of the HSPGs altering their structure. The modified HSPGs in the endothelium and ECM in the blood vessel wall contribute to the nephropathy, cardiovascular disease, and retinopathy seen in diabetes. Besides the blood vessel, other cells and tissues in the heart, kidney, and eye are affected by diabetes. Although not well understood, the adipose tissue, intestine, and brain also reveal HSPG changes associated with diabetes. Further, HSPGs are significantly involved in protecting the β cells of the pancreas from autoimmune destruction and could be a focus of prevention of type I diabetes. In some circumstances, HSPGs may contribute to the pathology of the disease. Understanding the role of HSPGs and how they are modified by diabetes may lead to new treatments as well as preventative measures to reduce the morbidity and mortality associated with this complex condition.

The Endothelial Glycocalyx as a Target of Ischemia and Reperfusion Injury in Kidney Transplantation-Where Have We Gone So Far?

The damage of the endothelial glycocalyx as a consequence of ischemia and/or reperfusion injury (IRI) following kidney transplantation has come at the spotlight of research due to potential associations with delayed graft function, acute rejection as well as long-term allograft dysfunction. The disintegration of the endothelial glycocalyx induced by IRI is the crucial event which exposes the denuded endothelial cells to further inflammatory and oxidative damage. The aim of our review is to present the currently available data regarding complex links between shedding of the glycocalyx components, like syndecan-1, hyaluronan, heparan sulphate, and CD44 with the activation of intricate immune system responses, including toll-like receptors, cytokines and pro-inflammatory transcription factors. Evidence on modes of protection of the endothelial glycocalyx and subsequently maintenance of endothelial permeability as well as novel nephroprotective molecules such as sphingosine-1 phosphate (S1P), are also depicted. Although advances in technology are making the visualization and the analysis of the endothelial glycocalyx possible, currently available evidence is mostly experimental. Ongoing progress in understanding the complex impact of IRI on the endothelial glycocalyx, opens up a new era of research in the field of organ transplantation and clinical studies are of utmost importance for the future.

Kidney allograft fibrosis: what we learned from latest translational research studies

To add new molecular and pathogenetic insights into the biological machinery associated to kidney allograft fibrosis is a major research target in nephrology and organ transplant translational medicine. Interstitial fibrosis associated to tubular atrophy (IF/TA) is, in fact, an inevitable and progressive process that occurs in almost every type of chronic allograft injury (particularly in grafts from expanded criteria donors) characterized by profound remodeling and excessive production/deposition of fibrillar extracellular matrix (ECM) with a great clinical impact. IF/TA is detectable in more than 50% of kidney allografts at 2 years. However, although well studied, the complete cellular/biological network associated with IF/TA is only partially evaluated. In the last few years, then, thanks to the introduction of new biomolecular technologies, inflammation in scarred/fibrotic parenchyma areas (recently acknowledged by the BANFF classification) has been recognized as a pivotal element able to accelerate the onset and development of the allograft chronic damage. Therefore, in this review, we focused on some new pathogenetic elements involved in graft fibrosis (including epithelial/endothelial to mesenchymal transition, oxidative stress, activation of Wnt and Hedgehog signaling pathways, fatty acids oxidation and cellular senescence) that, in our opinion, could become in future good candidates as potential biomarkers and therapeutic targets.

Glycocalyx Degradation in Ischemia-Reperfusion Injury

The glycocalyx is a layer coating the luminal surface of vascular endothelial cells. It is vital for endothelial function as it participates in microvascular reactivity, endothelium interaction with blood constituents, and vascular permeability. Structural and functional damage to glycocalyx occurs in various disease states. A prominent clinical situation characterized by glycocalyx derangement is ischemia-reperfusion (I/R) of the whole body as well as during selective I/R to organs such as the kidney, heart, lung, or liver. Degradation of the glycocalyx is now considered a cornerstone in I/R-related endothelial dysfunction, which further impairs local microcirculation with a feed-forward loop of organ damage, due to vasoconstriction, leukocyte adherence, and activation of the immune response. Glycocalyx damage during I/R is evidenced by rising plasma levels of its principal constituents, heparan sulfate and syndecan-1. By contrast, the concentrations of these compounds in the circulation decrease after successful protective interventions in I/R, suggesting their use as surrogate biomarkers of endothelial integrity. In light of the importance of the glycocalyx in preserving endothelial cell integrity and its involvement in pathologic conditions, several promising therapeutic strategies to restore the damaged glycocalyx and to attenuate its deleterious consequences have been suggested. This review focuses on alterations of glycocalyx during I/R injury in general (to vital organs in particular), and on maneuvers aimed at glycocalyx recovery during I/R injury.

Heparanase in Acute Kidney Injury

Recent years have brought about fledgling realization of the role played by heparanase in the pathogenesis of diverse diseases including kidney diseases and, specifically, acute kidney injury. Human heparanase-1 is critically and uniquely engaged in cleavage of heparan sulfate, an integral part of glycocalyx and extracellular matrix where it harbors distinct growth factors, cytokines, and other biologically active molecules. The enzyme is induced and activated in acute kidney injury regardless of its causes, ischemic, nephrotoxic, septic or transplantation-related. This event unleashes a host of sequelae characteristic of the pathogenesis of acute kidney injury, such as induction and reinforcement of innate immune responses, predisposition to thrombosis, activation of monocytes/macrophages and remodeling of the extracellular matrix, thus setting up the stage for future fibrotic complications and development of chronic kidney disease. We briefly discuss the emerging therapeutic strategies of inhibiting heparanase, as well as the diagnostic value of detecting products of heparanase activity for prognostication and treatment.

The blood compatibility challenge. Part 4: Surface modification for hemocompatible materials: Passive and active approaches to guide blood-material interactions

Biomedical devices in the blood flow disturb the fine-tuned balance of pro- and anti-coagulant factors in blood and vessel wall. Numerous technologies have been suggested to reduce coagulant and inflammatory responses of the body towards the device material, ranging from camouflage effects to permanent activity and further to a responsive interaction with the host systems. However, not all types of modification are suitable for all types of medical products. This review has a focus on application-oriented considerations of hemocompatible surface fittings. Thus, passive versus bioactive modifications are discussed along with the control of protein adsorption, stability of the immobilization, and the type of bioactive substance, biological or synthetic. Further considerations are related to the target system, whether enzymes or cells should be addressed in arterial or venous system, or whether the blood vessel wall is addressed. Recent developments like feedback controlled or self-renewing systems for drug release or addressing cellular regulation pathways of blood platelets and endothelial cells are paradigms for a generation of blood contacting devices, which are hemocompatible by cooperation with the host system. STATEMENT OF SIGNIFICANCE: This paper is part 4 of a series of 4 reviews discussing the problem of biomaterial associated thrombogenicity. The objective was to highlight features of broad agreement and provide commentary on those aspects of the problem that were subject to dispute. We hope that future investigators will update these reviews as new scholarship resolves the uncertainties of today.

Plasma heparanase is associated with blood glucose levels but not urinary microalbumin excretion in type 2 diabetic nephropathy at the early stage

Aim: To explore the possible correlations between plasma heparanase and albuminuria, glucose and lipid metabolism in the type 2 diabetic nephropathy patients at the early stage.

Methods: One hundred and forty patients with type 2 diabetic nephropathy at early stage were recruited into the study. Plasma heparanase and the characterized advanced glycation end products (AGEs), carboxymethyllysine (CML) were measured by enzyme-linked immunosorbent assay.

Results: Plasma heparanase was positively associated with fasting blood glucose (R = 0.24, p = .01) while heparanase was not significantly correlated with the urinary microalbumin to creatinine ratio (urinary mAlb/Cr) (R = 0.05, p = .58) and CML (R = 0.16, p = .26). On stepwise linear regression analysis, fasting blood glucose was the main independent determinants of plasma heparanase concentration.

Conclusion: Plasma heparanase is not significantly associated with urinary mAlb/Cr while it is correlated positively with blood glucose levels in the early stage of diabetic nephropathy. Plasma heparnase might be regarded as a marker for vascular endothelial cells injury in diabetic patients.

Heparanase inhibition attenuates atherosclerosis progression and liver steatosis in E0 mice

BACKGROUND AND AIMS

Increased oxidative stress is associated with accelerated atherosclerosis. Emerging evidence highlights the role of heparanase in atherogenesis, where heparanase inhibitor PG545 reduces oxidative stress in apolipoprotein E deficient mice (E₀ mice). Herein, we studied the effects of PG545 on atherosclerosis progression in E₀ mice.

METHODS

Male E₀ mice fed a high-fat diet (n = 20) were divided into 3 groups treated with weekly intraperitoneal injections of either low (0.2 mg/mouse) or high dose (0.4 mg/mouse)PG545 or normal saline (controls) for twelve weeks. Body weight and food intake were measured weekly. At the end of the treatment period, blood pressure was measured, animals were sacrificed and serum samples were collected and assessed for biochemical parameters and oxidative stress. Aortic vessels and livers were collected for atherosclerotic plaques and histopathological analysis, respectively.

RESULTS

Blood pressure decreased in mice treated with low, but not high dose of PG545. In addition, heparanase inhibition caused a dose-dependent reduction in serum oxidative stress, total cholesterol, low-density lipoproteins, triglycerides, high-density lipoproteins, and aryl esterase activity. Although food intake was not reduced by PG545, body weight gain was significantly attenuated in PG545 treated groups. Both doses of PG545 caused a marked reduction in aortic wall thickness and atherosclerosis development, and liver steatosis. Liver enzymes and serum creatinine were not affected by PG545.

CONCLUSIONS

Heparanase inhibition by PG545 caused a significant reduction in lipid profile and serum oxidative stress along with attenuation of atherosclerosis, aortic wall thickness, and liver steatosis. Moreover, PG545 attenuated weight gain without reducing food intake. Collectively, these findings suggest that heparanase blockade is highly effective in slowing atherosclerosis formation and progression, and decreasing liver steatosis.

Involvement of heparanase in the pathogenesis of acute kidney injury: nephroprotective effect of PG545

Despite the high prevalence of acute kidney injury (AKI) and its association with increased morbidity and mortality, therapeutic approaches for AKI are disappointing. This is largely attributed to poor understanding of the pathogenesis of AKI. Heparanase, an endoglycosidase that cleaves heparan sulfate, is involved in extracellular matrix turnover, inflammation, kidney dysfunction, diabetes, fibrosis, angiogenesis and cancer progression. The current study examined the involvement of heparanase in the pathogenesis of ischemic reperfusion (I/R) AKI in a mouse model and the protective effect of PG545, a potent heparanase inhibitor. I/R induced tubular damage and elevation in serum creatinine and blood urea nitrogen to a higher extent in heparanase over-expressing transgenic mice vs. wild type mice. Moreover, TGF-β, vimentin, fibronectin and α-smooth muscle actin, biomarkers of fibrosis, and TNFα, IL6 and endothelin-1, biomarkers of inflammation, were upregulated in I/R induced AKI, primarily in heparanase transgenic mice, suggesting an adverse role of heparanase in the pathogenesis of AKI. Remarkably, pretreatment of mice with PG545 abolished kidney dysfunction and the up-regulation of heparanase, pro-inflammatory (i.e., IL-6) and pro-fibrotic (i.e., TGF-β) genes induced by I/R. The present study provides new insights into the involvement of heparanase in the pathogenesis of ischemic AKI. Our results demonstrate that heparanase plays a deleterious role in the development of renal injury and kidney dysfunction, attesting heparanase inhibition as a promising therapeutic approach for AKI.

Heparanase Inhibition Reduces Glucose Levels, Blood Pressure, and Oxidative Stress in Apolipoprotein E Knockout Mice

Background

Atherosclerosis is a multifactorial process. Emerging evidence highlights a role of the enzyme heparanase in various disease states, including atherosclerosis formation and progression.

Objective

The aim of the study was to investigate the effect of heparanase inhibition on blood pressure, blood glucose levels, and oxidative stress in apoE−/− mice.

Methods

Male apoE−/− mice were divided into two groups: one treated by the heparanase inhibitor PG545, administered intraperitoneally weekly for seven weeks, and the other serving as control group (injected with saline). Blood pressure was measured a day before sacrificing the animals. Serum glucose levels and lipid profile were measured. Assessment of oxidative stress was performed as well.

Results

PG545 significantly lowered blood pressure and serum glucose levels in treated mice. It also caused significant reduction of the serum oxidative stress. For safety concerns, liver enzymes were assessed, and PG545 caused significant elevation only of alanine aminotransferase, but not of the other hepatic enzymes.

Conclusion

Heparanase inhibition by PG545 caused marked reduction of blood pressure, serum glucose levels, and oxidative stress in apolipoprotein E deficient mice, possibly via direct favorable metabolic and hemodynamic changes caused by the inhibitor. Possible hepatotoxic and weight wasting effects are subject for future investigation.

Heparanase: roles in cell survival, extracellular matrix remodelling and the development of kidney disease

Heparanase has regulatory roles in various processes, including cell communication, gene transcription and autophagy. In addition, it is the only known mammalian endoglycosidase that is capable of degrading heparan sulfate (HS). HS chains are important constituents and organizers of the extracellular matrix (ECM), and have a key role in maintaining the integrity and function of the glomerular filtration barrier. In addition, HS chains regulate the activity of numerous bioactive molecules, such as cytokines and growth factors, at the cell surface and in the ECM. Given the functional diversity of HS, its degradation by heparanase profoundly affects important pathophysiological processes, including tumour development, neovascularization and inflammation, as well as progression of kidney disease. Heparanase-mediated degradation and subsequent remodelling of HS in the ECM of the glomerulus is a key mechanism in the development of glomerular disease, as exemplified by the complete resistance of heparanase-deficient animals to diabetes and immune-mediated kidney disease. This Review summarizes the role of heparanase in the development of kidney disease, and its potential as a therapeutic target.

Protective effects of Danggui Buxue Tang on renal function, renal glomerular mesangium and heparanase expression in rats with streptozotocin-induced diabetes mellitus

Danggui Buxue Tang (DBT) is a simple combination of Radix Astragali and Radix Angelica sinensis (5:1), with a variety pharmacological activities. In the present study, a single intravenous injection of 30 mg/kg streptozotocin and subsequent six weeks of high glucose diet in Sprague Dawley rats were used to induce diabetic nephropathy. Rats with diabetes mellitus showed increased levels of fasting blood glucose (FBG), blood urea nitrogen (BUN), serum creatinine (Scr), serum and urine β2-microglobulins (β2-MG), and type IV collagen (all P<0.05). DBT treatment significantly decreased the levels of FBG, BUN, Scr, serum and urine β2-MG, and type IV collagen. Furthermore, DBT treatment significantly and dose-dependently restored the ultrastructural injury, and reduced the expression of heparanase, compared with the vehicle (P<0.05). Therefore, DBT may be a novel therapeutic approach for the prevention and treatment of diabetic nephrology.

Impact of heparanase on renal fibrosis

Tubulo-interstitial fibrosis has been recognized as the hallmark of progression of chronic kidney disease, but, despite intensive research studies, there are currently no biomarkers or effective treatments for this condition. In this context, a promising candidate could be heparanase-1 (HPSE), an endoglycosidase that cleaves heparan sulfate chains and thus takes part in extracellular matrix remodeling. As largely described, it has a central role in the pathogenesis of cancer and inflammation, and it participates in the complex biological machinery involved in the onset of different renal proteinuric diseases (e.g., diabetic nephropathy, glomerulonephritis). Additionally, HPSE may significantly influence the progression of chronic kidney damage trough its major role in the biological pathway of renal fibrogenesis. Here, we briefly summarize data supporting the role of HPSE in renal damage, focusing on recent evidences that demonstrate the capability of this enzyme to modulate the signaling of pro-fibrotic factors such as FGF-2 and TGF-β and consequently to control the epithelial-mesenchymal transition in renal tubular cells. We also emphasize the need of the research community to undertake studies and clinical trials to assess the potential clinical employment of this enzyme as diagnostic and prognostic tool and/or its role as therapeutic target for new pharmacological interventions.

Nephroprotective effect of heparanase in experimental nephrotic syndrome

BACKGROUND

Heparanase, an endoglycosidase that cleaves heparan sulfate (HS), is involved in various biologic processes. Recently, an association between heparanase and glomerular injury was suggested. The present study examines the involvement of heparanase in the pathogenesis of Adriamycin-induced nephrotic syndrome (ADR-NS) in a mouse model.

METHODS

BALB/c wild-type (wt) mice and heparanase overexpressing transgenic mice (hpa-TG) were tail-vein injected with either Adriamycin (ADR, 10 mg/kg) or vehicle. Albuminuria was investigated at days 0, 7, and 14 thereafter. Mice were sacrificed at day 15, and kidneys were harvested for various analyses: structure and ultrastructure alterations, podocyte proteins expression, and heparanase enzymatic activity.

RESULTS

ADR-injected wt mice developed severe albuminuria, while ADR-hpa-TG mice showed only a mild elevation in urinary albumin excretion. In parallel, light microscopy of stained cross sections of kidneys from ADR-injected wt mice, but not hpa-TG mice, showed mild to severe glomerular and tubular damage. Western blot and immunofluorescence analyses revealed significant reduction in nephrin and podocin protein expression in ADR-wt mice, but not in ADR-hpa-TG mice. These results were substantiated by electron-microscopy findings showing massive foot process effacement in injected ADR-wt mice, in contrast to largely preserved integrity of podocyte architecture in ADR-hpa-TG mice.

CONCLUSIONS

Our results suggest that heparanase may play a nephroprotective role in ADR-NS, most likely independently of HS degradation. Moreover, hpa-TG mice comprise an invaluable in vivo platform to investigate the interplay between heparanase and glomerular injury.

Glycosaminoglycans, hyperglycemia, and disease

SIGNIFICANCE

Diabetes is a widespread disease with many clinical pathologies. Despite numerous pharmaceutical strategies for treatment, the incidence of diabetes continues to increase. Hyperglycemia, observed in diabetes, causes endothelial injury resulting in microvascular and macrovascular complications such as nephropathy, retinopathy, neuropathy, and increased atherosclerosis.

RECENT ADVANCES

Proteoglycans are chemically diverse macromolecules consisting of a protein core with glycosaminoglycans (GAGs) attached. Heparan sulfate proteoglycans are important compounds found on the endothelial cell membrane and in the extracellular matrix, which play an important role in growth regulation and serve as a reservoir for cytokines and other bioactive molecules. Endothelial cells are altered in hyperglycemia by a reduction in heparan sulfate and upregulation and secretion of heparanase, an enzyme that degrades heparan sulfate GAGs on proteoglycans. Reactive oxygen species, increased in diabetes, also destroy GAGs.

CRITICAL ISSUES

Preservation of heparan sulfate proteoglycans on endothelial cells may be a strategy to prevent angiopathy associated with diabetes. The use of GAGs and GAG-like compounds may increase endothelial heparan sulfate and prevent an increase in the heparanase enzyme.

FUTURE DIRECTIONS

Elucidating the mechanisms of GAG depletion and its significance in endothelial health may help to further understand, prevent, and treat cardiovascular complications associated with diabetes. Further studies examining the role of GAGs and GAG-like compounds in maintaining endothelial health, including their effect on heparanase, will determine the feasibility of these compounds in diabetes treatment. Preservation of heparan sulfate by decreasing heparanase may have important implications not only in diabetes, but also in cardiovascular disease and tumor biology.

Beyond tissue injury-damage-associated molecular patterns, toll-like receptors, and inflammasomes also drive regeneration and fibrosis

Tissue injury initiates an inflammatory response through the actions of immunostimulatory molecules referred to as damage-associated molecular patterns (DAMPs). DAMPs encompass a group of heterogenous molecules, including intracellular molecules released during cell necrosis and molecules involved in extracellular matrix remodeling such as hyaluronan, biglycan, and fibronectin. Kidney-specific DAMPs include crystals and uromodulin released by renal tubular damage. DAMPs trigger innate immunity by activating Toll-like receptors, purinergic receptors, or the NLRP3 inflammasome. However, recent evidence revealed that DAMPs also trigger re-epithelialization upon kidney injury and contribute to epithelial-mesenchymal transition and, potentially, to myofibroblast differentiation and proliferation. Thus, these discoveries suggest that DAMPs drive not only immune injury but also kidney regeneration and renal scarring. Here, we review the data from these studies and discuss the increasingly complex connection between DAMPs and kidney diseases.

Everolimus-induced epithelial to mesenchymal transition in immortalized human renal proximal tubular epithelial cells: key role of heparanase

BACKGROUND

Everolimus (EVE) is a drug widely used in several renal transplant protocols. Although characterized by a relatively low nephrotoxicity, it may induce several adverse effects including severe fibro-interstitial pneumonitis. The exact molecular/biological mechanism associated to these pro-fibrotic effects is unknown, but epithelial to mesenchymal transition (EMT) may have a central role. Additionally, heparanase, an enzyme recently associated with the progression of chronic allograft nephropathy, could contribute to activate this machinery in renal cells.

METHODS

Several biomolecular strategies (RT-PCR, immunofluorescence, zymography and migration assay) have been used to assess the capability of EVE (10, 100, 200 and 500 nM) to induce an in vitro heparanase-mediated EMT in wild-type (WT) and Heparanase (HPSE)-silenced immortalized human renal epithelial proximal tubular cells (HK-2). Additionally, microarray technology was used to find additional biological elements involved in EVE-induced EMT.

RESULTS

Biomolecular experiments demonstrated a significant up-regulation (more than 1.5 fold increase) of several genes encoding for well known EMT markers [(alpha-smooth muscle actin (α-SMA), Vimentin (VIM), Fibronectin (FN) and matrix metalloproteinase-9 (MMP9)], enhancement of MMP9 protein level and increment of cells motility in WT HK2 cells treated with high concentrations of EVE (higher than 100 nM). Similarly, immunofluorescence analysis showed that 100 nM of EVE increased α-SMA, VIM and FN protein expression in WT HK2 cells. All these effects were absent in both HPSE- and AKT-silenced cell lines. AKT is a protein having a central role in EMT. Additionally, microarray analysis identified other 2 genes significantly up-regulated in 100 nM EVE-treated cells (p < 0.005 and FDR < 5%): transforming growth factor beta-2 (TGFβ2) and epidermal growth factor receptor (EGFR). Real-time PCR analysis validated microarray.

CONCLUSIONS

Our in vitro study reveals new biological/cellular aspects of the pro-fibrotic activity of EVE and it demonstrates, for the first time, that an heparanase-mediated EMT of renal tubular cells may be activated by high doses of this drug. Additionally, our results suggest that clinicians should administer the adequate dosage of EVE in order to increase efficacy and reduce adverse effects. Finally heparanase could be a new potential therapeutic target useful to prevent/minimize drug-related systemic fibrotic adverse effects.

Heparanase in inflammation and inflammation-associated cancer

Recent years have seen a growing body of evidence that enzymatic remodeling of heparan sulfate proteoglycans profoundly affects a variety of physiological and pathological processes, including inflammation, neovascularization, and tumor development. Heparanase is the sole mammalian endoglycosidase that cleaves heparan sulfate. Extensively studied in cancer progression and aggressiveness, heparanase was recently implicated in several inflammatory disorders as well. Although the precise mode of heparanase action in inflammatory reactions is still not completely understood, the fact that heparanase activity is mechanistically important both in malignancy and in inflammation argues that this enzyme is a candidate molecule linking inflammation and tumorigenesis in inflammation-associated cancers. Elucidation of the specific effects of heparanase in cancer development, particularly when inflammation is a causal factor, will accelerate the development of novel therapeutic/chemopreventive interventions and help to better define target patient populations in which heparanase-targeting therapies could be particularly beneficial.

Involvement of heparanase in atherosclerosis and other vessel wall pathologies

Heparanase, the sole mammalian endoglycosidase degrading heparan sulfate, is causally involved in cancer metastasis, angiogenesis, inflammation and kidney dysfunction. Despite the wide occurrence and impact of heparan sulfate proteoglycans in vascular biology, the significance of heparanase in vessel wall disorders is underestimated. Blood vessels are highly active structures whose morphology rapidly adapts to maintain vascular function under altered systemic and local conditions. In some pathologies (restenosis, thrombosis, atherosclerosis) this normally beneficial adaptation may be detrimental to overall function. Enzymatic dependent and independent effects of heparanase on arterial structure mechanics and repair closely regulate arterial compliance and neointimal proliferation following endovascular stenting. Additionally, heparanase promotes thrombosis after vascular injury and contributes to a pro-coagulant state in human carotid atherosclerosis. Importantly, heparanase is closely associated with development and progression of atherosclerotic plaques, including stable to unstable plaque transition. Consequently, heparanase levels are markedly increased in the plasma of patients with acute myocardial infarction. Noteworthy, heparanase activates macrophages, resulting in marked induction of cytokine expression associated with plaque progression towards vulnerability. Together, heparanase emerges as a regulator of vulnerable lesion development and potential target for therapeutic intervention in atherosclerosis and related vessel wall complications.

Heparanase induced by advanced glycation end products (AGEs) promotes macrophage migration involving RAGE and PI3K/AKT pathway

Background

Advanced glycation end products (AGEs), inflammatory-associated macrophage migration and accumulation are crucial for initiation and progression of diabetic vascular complication. Enzymatic activity of heparanase (HPA) is implicated strongly in dissemination of metastatic tumor cells and cells of the immune system. In addition, HPA enhances the phosphorylation of selected signaling molecules including AKT pathway independent of enzymatic activity. However, virtually nothing is presently known the role of HPA during macrophage migration exposed to AGEs involving signal pathway.

Methods

These studies were carried out in Ana-1 macrophages. Macrophage viability was measured by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assays. HPA and AKT protein expression in macrophages are analysed by Western blotting and HPA mRNA expression by real time quantitative RT-PCR. Release of HPA was determined by ELISA. Macrophage migration was assessed by Transwell assays.

Results

HPA protein and mRNA were found to be increased significantly in AGEs-treated macrophages. Pretreatment with anti-HPA antibody which recognizes the nonenzymatic terminal of HPA prevented AGEs-induced AKT phosphorylation and macrophage migration. LY294002 (PI3k/AKT inhibitor) inhibited AGEs-induced macrophage migration. Furthermore, pretreatment with anti-receptor for advanced glycation end products (RAGE) antibody attenuated AGEs-induced HPA expression, AKT phosphorylation and macrophage migration.

Conclusions

These data indicate that AGEs-induced macrophage migration is dependent on HPA involving RAGE-HPA-PI3K/AKT pathway. The nonenzymatic activity of HPA may play a key role in AGEs-induced macrophage migration associated with inflammation in diabetic vascular complication.