Endothelial Dysfunction in Patients Undergoing Cardiac Surgery: A Narrative Review and Clinical Implications

Cardiac surgery is one of the highest-risk procedures, usually involving cardiopulmonary bypass and commonly inducing endothelial injury that contributes to the development of perioperative and postoperative organ dysfunction. Substantial scientific efforts are being made to unravel the complex interaction of biomolecules involved in endothelial dysfunction to find new therapeutic targets and biomarkers and to develop therapeutic strategies to protect and restore the endothelium. This review highlights the current state-of-the-art knowledge on the structure and function of the endothelial glycocalyx and mechanisms of endothelial glycocalyx shedding in cardiac surgery. Particular emphasis is placed on potential strategies to protect and restore the endothelial glycocalyx in cardiac surgery. In addition, we have summarized and elaborated the latest evidence on conventional and potential biomarkers of endothelial dysfunction to provide a comprehensive synthesis of crucial mechanisms of endothelial dysfunction in patients undergoing cardiac surgery, and to highlight their clinical implications.

Sulodexide Prevents Hyperglycemia-Induced Endothelial Dysfunction and Oxidative Stress in Porcine Retinal Arterioles

Diabetes mellitus may cause severe damage to retinal blood vessels. The central aim of this study was to test the hypothesis that sulodexide, a mixture of glycosaminoglycans, has a protective effect against hyperglycemia-induced endothelial dysfunction in the retina. Functional studies were performed in isolated porcine retinal arterioles. Vessels were cannulated and incubated with highly concentrated glucose solution (HG, 25 mM D-glucose) +/- sulodexide (50/5/0.5 μg/mL) or normally concentrated glucose solution (NG, 5.5 mM D-glucose) +/- sulodexide for two hours. Endothelium-dependent and endothelium-independent vasodilatation were measured by videomicroscopy. Reactive oxygen species (ROS) were quantified by dihydroethidium (DHE) fluorescence. Using high-pressure liquid chromatography (HPLC), the intrinsic antioxidant properties of sulodexide were investigated. Quantitative PCR was used to determine mRNA expression of regulatory, inflammatory, and redox genes in retinal arterioles, some of which were subsequently quantified at the protein level by immunofluorescence microscopy. Incubation of retinal arterioles with HG caused significant impairment of endothelium-dependent vasodilation, whereas endothelium-independent responses were not affected. In the HG group, ROS formation was markedly increased in the vascular wall. Strikingly, sulodexide had a protective effect against hyperglycemia-induced ROS formation in the vascular wall and had a concentration-dependent protective effect against endothelial dysfunction. Although sulodexide itself had only negligible antioxidant properties, it prevented hyperglycemia-induced overexpression of the pro-oxidant redox enzymes, NOX4 and NOX5. The data of the present study provide evidence that sulodexide has a protective effect against hyperglycemia-induced oxidative stress and endothelial dysfunction in porcine retinal arterioles, possibly by modulation of redox enzyme expression.

Circulating Heparan Sulfate Proteoglycans as Biomarkers in Health and Disease

Cell-surface heparan sulfate proteoglycans (HSPGs) play key roles in regulating cell behavior, cell signaling, and cell matrix interactions in both physiological and pathological conditions. Their soluble forms from glycocalyx shedding are not merely waste products, but, rather, bioactive molecules, detectable in serum, which may be useful as diagnostic and prognostic markers. In addition, as in the case of glypican-3 in hepatocellular carcinoma, they may be specifically expressed by pathological tissue, representing promising targets for immunotherapy. The primary goal of this comprehensive review is to critically survey the main findings of the clinical data from the last 20 years and provide readers with an overall picture of the diagnostic and prognostic value of circulating HSPGs. Moreover, issues related to the involvement of HSPGs in various pathologies, including cardiovascular disease, thrombosis, diabetes and obesity, kidney disease, cancer, trauma, sepsis, but also multiple sclerosis, preeclampsia, pathologies requiring surgery, pulmonary disease, and others will be discussed.

Sulodexide for Diabetic-Induced Disabilities: A Systematic Review and Meta-Analysis

INTRODUCTION

Micro- and macrovascular complications of diabetes are leading morbidities in the world population. They are responsible not only for increased mortality but also severe disabilities, which jeopardize quality of life (e.g., blindness, walking limitations, and renal failure requiring dialysis). The new antidiabetic agents (e.g., glucagon-like peptide 1 receptor agonists and sodium-glucose cotransporter inhibitors) are increasingly recognized as breakthrough agents in the treatment of diabetes and prevention of diabetic complications. However, drugs effective in preventing and treating diabetic disabilities are still needed and sulodexide could be one of those able to address the unmet clinical needs of the new antidiabetic agents.

METHODS

We searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, and the World Health Organization (WHO) International Clinical Trials Registry Platform Search Portal. We also manually searched potentially relevant journals, conference proceedings, and journal supplements. Any study monitoring any effect of sulodexide in subjects with diabetes, in relation to renal, vascular, and ocular complication, was considered. Treatment effects were estimated using standardized mean differences (SMDs), mean differences (MDs), and risk ratios (RRs), as appropriate. We calculated 95% confidence interval (CIs) and heterogeneity (Q, tau, and I²).

RESULTS

The search found 45 studies with 2817 participants (mean age 57 years; 63% male). The 26 randomized controlled studies included 2074 participants (mean age 58.8 years; 66% male). Sulodexide reduced the impact of diabetic retinopathy; increased the pain-free and maximal walking distance in peripheral arterial disease; accelerated the healing of diabetes-associated trophic ulcers; and decreased the rate of albumin excretion in subjects with nephropathy. The risk of adverse events (AEs) was not different between sulodexide and controls.

CONCLUSION

Sulodexide has a beneficial effect on the ocular, peripheral arterial disease, trophic ulcers, and renal complications of diabetes without increasing the risk of AEs.

The endothelial glycocalyx: Structure and function in health and critical illness

OBJECTIVE

To conduct a narrative review of the current literature in reference to the structure and function of the endothelial glycocalyx (EG) and its contribution to the pathophysiology of conditions relevant to the veterinary emergency and critical care clinician. Novel therapies for restoring or preserving the EG will also be discussed.

DATA SOURCES

Online databases (PubMed, CAB abstracts, Scopus) were searched between January 1st 2017 and May 1st 2017 for English language articles without publication date restriction. Keywords included EG, endothelial surface layer, degradation, syndecan-1, heparan sulfate, critical illness, sepsis, trauma, and therapeutics.

DATA SYNTHESIS

The EG is a complex and important structure located on the luminal surface of all blood vessels throughout the body. It plays an important role in normal vascular homeostasis including control of fluid exchange across the vascular barrier. Loss or degradation of the EG has an impact on inflammation, coagulation, and vascular permeability and tone. These changes are essential components in the pathophysiology of many conditions including sepsis and trauma. A substantial body of experimental animal and human clinical research over the last decade has demonstrated increased circulating concentrations of EG degradation products in these conditions. However, veterinary-specific research into the EG and critical illness is currently lacking. The utility of EG degradation products as diagnostic and prognostic tools continues to be investigated and new therapies to preserve or improve EG structure and function are under development.

CONCLUSIONS

The recognition of the presence of the EG has changed our understanding of transvascular fluid flux and the pathophysiology of many conditions of critical illness. The EG is an exciting target for novel therapeutics to improve morbidity and mortality in conditions such as sepsis and trauma.

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.

Sulodexide attenuates endoplasmic reticulum stress induced by myocardial ischaemia/reperfusion by activating the PI3K/Akt pathway

Acute myocardial ischaemia/reperfusion (MI/R) injury causes severe arrhythmias with a high rate of lethality. Extensive research focus on endoplasmic reticulum (ER) stress and its dysfunction which leads to cardiac injury in MI/R Our study evaluated the effects of sulodexide (SDX) on MI/R by establishing MI/R mice models and in vitro oxidative stress models in H9C2 cells. We found that SDX decreases cardiac injury during ischaemia reperfusion and decreased myocardial apoptosis and infarct area, which was paralleled by increased superoxide dismutase and reduced malondialdehyde in mice plasm, increased Bcl‐2 expression, decreased BAX expression in a mouse model of MI/R. In vitro, SDX exerted a protective effect by the suppression of the ER stress which induced by tert‐butyl hydroperoxide (TBHP) treatment. Both of the in vivo and in vitro effects were involved in the phosphatidylinositol 3‐kinase (PI3K)/Akt signalling pathway. Inhibition of PI3K/Akt pathway by specific inhibitor, LY294002, partially reduced the protective effect of SDX. In short, our results suggested that the cardioprotective role of SDX was related to the suppression of ER stress in mice MI/R models and TBHP‐induced H9C2 cell injury which was through the PI3K/Akt signalling pathway.

Endothelial glycocalyx: basic science and clinical implications

The classic Starling principle proposed that microvascular fluid exchange was determined by a balance of hydrostatic and oncotic pressures relative to the vascular wall and this movement of water was regulated by gaps in the intercellular spaces. However, current literature on the endothelial glycocalyx (a jelly-like protective layer covering the luminal surface of the endothelium) has revised Starling's traditional concepts. This article aims to summarise the literature on the glycocalyx related to its basic science, clinical settings inciting injury, protective strategies and clinical perspectives. Perioperative damage to the glycocalyx structure can increase vascular permeability leading to interstitial fluid shifts, oedema, and increased surgical morbidity. Pathological shedding of the glycocalyx occurs in response to mechanical cellular stress, endotoxins, inflammatory mediators, atrial natriuretic peptide, ischaemia-reperfusion injury, free oxygen radicals and hyperglycaemia. Increased understanding of the endothelial glycocalyx may change perioperative fluid management, and therapeutic strategies aimed at its preservation may improve patient outcomes.

Sulodexide prevents activation of the PLA2/COX-2/VEGF inflammatory pathway in human retinal endothelial cells by blocking the effect of AGE/RAGE

Diabetic retinopathy is characterized by the breakdown of endothelial blood-retinal barrier. We tested the hypothesis that sulodexide (SDX), a highly purified glycosaminoglycan composed of 80% iduronylglycosaminoglycan sulfate and 20% dermatan sulfate, protects human retinal endothelial cells (HREC) from high glucose (HG)-induced damage, through the suppression of inflammatory ERK/cPLA2/COX-2/PGE₂ pathway, by blocking the effect of advanced glycation end-products (AGEs). HREC were treated with HG (25mM) or AGEs (glycated-BSA, 2mg/ml) for 48h, with or without SDX (60μg/ml) or aflibercept (AFL, 40μg/ml), a VEGF-trap. SDX protected HREC from HG-induced damage (MTT and LDH release) and preserved their blood-retinal barrier-like properties (Trans Endothelial Electrical Resistance and junction proteins, claudin-5, VE-cadherin and occludin, immunofluorescence and immunoblot) as well as their angiogenic potential (Tube Formation Assay). Both HG and AGEs increased phosphoERK and phospho-cPLA₂, an effect counteracted by SDX and, less efficiently, by AFL. Both HG and exogenous VEGF (80ng/ml) increased PGE₂ release, an effect partially reverted by SDX for HG and by AFL for VEGF. Analysis of NFκB activity revealed that HG increased the abundance of p65 in the nuclear fraction (nuclear translocation), an effect entirely reverted by SDX, but only partially by AFL. SDX, AFL and SDX+AFL protected HREC even when added 24h after HG. These data show that SDX protects HREC from HG damage and suggest that it counteracts the activation of ERK/cPLA2/COX-2/PGE₂ pathway by reducing AGE-related signaling and downstream NFκB activity. This mechanism, partially distinct from VEGF blockade, may contribute to the therapeutic effect of SDX.

Mechanistic insight of diabetic nephropathy and its pharmacotherapeutic targets: An update

Diabetic nephropathy (DN), a chronic complication of diabetes, is charecterized by glomerular hypertrophy, proteinuria, decreased glomerular filtration, and renal fibrosis resulting in the loss of renal function. Although the exact cause of DN remains unclear, several mechanisms have been postulated, such as hyperglycemia-induced renal hyper filtration and renal injury, AGEs-induced increased oxidative stress, activated PKC-induced increased production of cytokines, chemokines, and different inflammatory and apoptotic signals. Among various factors, oxidative stress has been suggested to play a major role underlying the onset and propagation of DN. It triggers several signaling pathways involved in DN, like AGEs, PKC cascade, JAK/STAT signaling, MAPK, mTOR, and SMAD. Oxidative stress-induced activation of both inflammatory and apoptotic signals are two major problems in the pathogenesis of DN. The FDA approved pharmacotherapeutic agents affecting against polyol pathway principally include anti-oxidants, like α-lipoic acid, vitamin E, and vitamin C. Kremezin and benfotiamine are the FDA approved AGEs inhibitors, another therapeutic target against DN. Ruboxistaurin, telmizartan, rapamycin, fenofibrate, aliskiren, and manidipine are some FDA approved pharmacotherapeutics effective against DN via diverse mechanisms. Beside this, some therapeutic agents are still waiting for FDA approval and few drugs without FDA approval are also prescribed in some countries for the management of DN. Despite the medications available in the market to treat DN, the involvement of multiple mechanisms makes it difficult to choose an optimum therapeutic agent. Therefore, much research is required to find out new therapeutic agent/strategies for an adequate pharmacotherapy of DN.

Effectiveness of sulodexide might be associated with inhibition of complement system in hepatitis B virus-associated membranous nephropathy: An inspiration from a pilot trial

BACKGROUND

The activation of complement system is associated with the development of hepatitis B virus-associated membranous nephropathy (HBV-MN) and heparin could inhibit the activation of complement system.

METHODS

This was a three-center trial. Seventy-nine patients with HBV-MN participated in the study. The follow-up of the study consisted of two periods: Stage 1 (S1) and Stage 2 (S2). All patients received 0.5mg entecavir plus 150-300mg/day of irbesartan but sulodexide was prescribed during S1. They were randomized into 4 groups according to sulodexide dose: blank (Group 1), 250 lipasemic unit (lsu)/day for 1year (Group 2), 500 lsu/day for 1year (Group 3) and 1000 lsu/day for 6months followed by 250 lsu/day for 6months (Group 4). Major clinical outcomes were valid remission (VR): (1) urine albumin/creatinine ratio (UACR) <150mg/mmol and >50% decline of baseline; (2) albumin >35g/L; (3) glomerular filtration rate (GFR) >90ml/(min*1.73m(2)).

RESULTS

(1) Groups 3 and 4 had significantly lower UACR and higher albumin than did Groups 1 and 2 at major visits; (2) Groups 3 and 4 achieved more VR compared with Group 1 (42.1% and 60.0% vs. 9.1%, p both<0.05); (3) in Groups 3 and 4, instead of Groups 1 and 2, more C3 deposition in the kidney was observed in those achieving VR; (4) plasma C3a, C5a and C5b-9 decreased significantly in Groups 3 and 4 during S1.

CONCLUSIONS

(1) The prescription of both sulodexide and entecavir could improve the prognosis of patients with HBV-MN but their mechanisms might be different; (2) the renoprotection of sulodexide in HBV-MN might probably relate to the inhibition of complement system.

Sulodexide therapy for the treatment of diabetic nephropathy, a meta-analysis and literature review

Sulodexide is a heterogeneous group of sulfated glycosaminoglycans (GAGs) that is mainly composed of low-molecular-weight heparin. Clinical studies have demonstrated that sulodexide is capable of reducing urinary albumin excretion rates in patients with type 1 and type 2 diabetes, suggesting that sulodexide has renal protection. However, this efficacy remains inconclusive. In this article, we used meta-analysis to summarize the clinical results of all prospective clinical studies in order to determine the clinical efficacy and safety of sulodexide in diabetic patients with nephropathy. Overall, sulodexide therapy was associated with a significant reduction in urinary protein excretion. In the sulodexide group, 220 (17.7%) achieved at least a 50% decrease in albumin excretion rate compared with only 141 (11.5%) in the placebo. The odds ratio comparing proportions of patients with therapeutic success between the sulodexide and placebo groups was 3.28 (95% confidence interval, 1.34-8.06; P=0.01). These data suggest a renoprotective benefit of sulodexide in patients with diabetes and micro- and macroalbuminuria, which will provide important information for clinical use of this drug as a potential modality for diabetic nephropathy, specifically, the prevention of end-stage renal disease that is often caused by diabetes.

Improvements in the Management of Diabetic Nephropathy

The burden of diabetes mellitus is relentlessly increasing. Diabetic nephropathy is the most common cause of end-stage renal disease (ESRD) worldwide and a major cause of morbidity and mortality in patients with diabetes. The current standard therapy of diabetic nephropathy involves intensive treatment of hyperglycemia and strict blood pressure control, mainly via blockade of the renin-angiotensin system (RAS). Attention has been drawn to additional beneficial effects of oral hypoglycemic drugs and fibrates on other aspects of diabetic nephropathy. On the other hand, antiproteinuric effects of RAS combination therapy do not seem to enhance the prevention of renal disease progression, and it has been associated with an increased rate of serious adverse events. Novel agents, such as bardoxolone methyl, pentoxifylline, inhibitors of protein kinase C (PKC), sulodexide, pirfenidone, endothelin receptor antagonists, vitamin D supplements, and phosphate binders have been associated with controversial outcomes or significant side effects. Although new insights into the pathogenetic mechanisms have opened new horizons towards novel interventions, there is still a long way to go in the field of DN research. The aim of this review is to highlight the recent progress made in the field of diabetes management based on the existing evidence. The article also discusses novel targets of therapy, with a special focus on the major pathophysiologic mechanisms implicated in the initiation and progression of diabetic nephropathy.

Sulodexide inhibits retinal neovascularization in a mouse model of oxygen-induced retinopathy

Sulodexide is a mixed glycosaminoglycan composed of heparin and dermatan sulfate. In this study, the anti-angiogenic effect of sulodexide was investigated using an oxygen-induced retinopathy (OIR) mouse model. The retinas of sham-injected OIR mice (P17) had a distinctive central area of nonperfusion, and this area was significantly decreased in sulodexide-injected mice. The number of neovascular tufts measured by SWIFT_NV and mean neovascular lumen number were significantly decreased in sulodexide-injected mice. Hyperbaric oxygen exposure resulted in increased levels of VEGF, MMP-2 and MMP-9, and when mice were treated with sulodexide, a dose-dependent reduction in VEGF, MMP-2 and MMP-9 levels was observed. Our results clearly demonstrate the anti-angiogenic effect of sulodexide and highlight sulodexide as a candidate supplementary substance to be used for the treatment of ocular pathologies that involve neovascularization. [BMB Reports 2014; 47(11): 637-642]

Degradation of the endothelial glycocalyx in clinical settings: searching for the sheddases

The endothelial glycocalyx has a profound influence at the vascular wall on the transmission of shear stress, on the maintenance of a selective permeability barrier and a low hydraulic conductivity, and on attenuating firm adhesion of blood leukocytes and platelets. Major constituents of the glycocalyx, including syndecans, heparan sulphates and hyaluronan, are shed from the endothelial surface under various acute and chronic clinical conditions, the best characterized being ischaemia and hypoxia, sepsis and inflammation, atherosclerosis, diabetes, renal disease and haemorrhagic viral infections. Damage has also been detected by in vivo microscopic techniques. Matrix metalloproteases may shed syndecans and heparanase, released from activated mast cells, cleaves heparan sulphates from core proteins. According to new data, not only hyaluronidase but also the serine proteases thrombin, elastase, proteinase 3 and plasminogen, as well as cathepsin B lead to loss of hyaluronan from the endothelial surface layer, suggesting a wide array of potentially destructive conditions. Appropriately, pharmacological agents such as inhibitors of inflammation, antithrombin and inhibitors of metalloproteases display potential to attenuate shedding of the glycocalyx in various experimental models. Also, plasma components, especially albumin, stabilize the glycocalyx and contribute to the endothelial surface layer. Though symptoms of the above listed diseases and conditions correlate with sequelae expected from disturbance of the endothelial glycocalyx (oedema, inflammation, leukocyte and platelet adhesion, low reflow), therapeutic studies to prove a causal connection have yet to be designed. With respect to studies on humans, some clinical evidence exists for benefits from application of sulodexide, a preparation delivering precursors of the glycocalyx constituent heparan sulphate. At present, the simplest option for protecting the glycocalyx seems to be to ensure an adequate level of albumin. However, also in this case, definite proof of causality needs to be delivered.

[Endothelial glycocalyx of blood circulation. II. Biological functions, state at norm and pathology, bioengineering application]

In normal state, a complex multicomponent system called glycocalyx is present on the surface of endothelial vascular system. Due to complexity of its composition and location on the border between vessel wall and blood circulation, glycocalyx participates in a number of functions supporting the metabolism of the vascular wall. In pathological conditions undergo complete or partial loss of this structure, which leads to inconsistencies in the vascular wall and change its functions. The functions of endothelial glycocalyx are its involvement in the regulation of vascular permeability, transduction and transformation by the shear stress of blood flow on endothelium, the molecular regulation of glycocalyx microenvironment and its interaction with circulating blood cells. Also briefly be considered participation of glycocalyx in the implementation of cardiovascular diseases, their correction, bioengineering application of glycocalyx and its components.

Novel Therapies of Diabetic Nephropathy

Diabetic nephropathy is currently the most common cause of end stage renal disease not only in the Western hemisphere but also in the developing nations. While the available therapeutic options remain not very effective, there is a strong ongoing effort to understand the pathogenesis better and develop more useful biomarkers. As the pathogenic mediators and signaling pathways get better defined, the scope of novel pharmaceutical agents to address such mediating factors as therapeutic targets is advancing. This review provides, in addition to a brief synopsis of currently used strategies, a comprehensive review of potential therapies that have been evolving in the past decade with a specific focus on the promising agents.

Development and use of sulodexide in vascular diseases: implications for treatment

Sulodexide (SDX), a sulfated polysaccharide complex extracted from porcine intestinal mucosa, is a blend of two glycosaminoglycan (GAG) entities, namely a fast-moving heparin (HP) fraction and a dermatan sulfate (DS; 20%) component. The compound is unique among HP-like substances in that it is biologically active by both the parenteral and oral routes. A main feature of the agent is to undergo extensive absorption by the vascular endothelium. For this reason, in preclinical studies, SDX administered parenterally displays an antithrombotic action similar to that of HPs but associated with fewer alterations of the blood clotting mechanisms and tests, thus being much less conducive to bleeding risk than HPs. When given orally, SDX is associated with minimal changes in classic coagulation tests, but maintains a number of important effects on the structure and function of endothelial cells (EC), and the intercellular matrix. These activities include prevention or restoration of the integrity and permeability of EC, counteraction versus chemical, toxic or metabolic EC injury, regulation of EC-blood cell interactions, inhibition of microvascular inflammatory and proliferative changes, and other similar effects, thus allowing oral SDX to be considered as an endothelial-protecting agent. The best available clinical evidence of the efficacy of SDX administered orally with or without an initial parenteral phase is the following: alleviation of symptoms in chronic venous disease and especially acceleration of healing of venous leg ulcers; prevention of cardiovascular events in survivors after acute myocardial infarction; marked improvement of intermittent claudication in patients with peripheral occlusive arterial disease; and abatement of proteinuria in patients with diabetic nephropathy that may contribute to the amelioration or stabilization of kidney function. Although further clinical trials are warranted, SDX is presently widely accepted in many countries as an effective and safe long-term, endothelial-protecting drug.

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

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.

Treatment of 5/6 nephrectomy rats with sulodexide: a novel therapy for chronic renal failure

AIM

Sulodexide, a glycosaminoglycan, could reduce albuminuria in diabetic patients. The aim of this study was to determine whether sulodexide could be used to treat chronic kidney failure in rats.

METHODS

Sixty Wistar rats undergone 5/6 nephrectomy, then were randomly divided into 4 groups: the model group, sulodexide group (sulodexide 5 mg/kg per day, im), irbesartan group irbesartan (20 mg/kg per day, ig) and sulodexide plus irbesartan group. Another 12 rats were enrolled into the sham operation group. After the treatments for 4, 8 and 12 weeks, urinary protein and serum creatinine levels were measured. After 12 weeks, serum cholesterin and triglycerides levels were measured, and the degrees of glomerular sclerosis and renal tubulointerstitial fibrosis were scored. The expression of aminopeptidase P (JG-12) in the renal tissue was examined using immunohistochemical staining. The renal expressions of endothelial nitric oxide synthase (eNOS) and tissue type plasminogen activator (tPA) were detected with RT-PCR and Western blot.

RESULTS

Proteinuria was markedly attenuated in the sulodexide-treated groups. After 4 and 8 weeks only the sulodexide-treated groups showed significant reduction in serum creatinine; while after 12 weeks all the three treatment groups showed significant reduction in serum creatinine. Furthermore, all the three treatment groups showed significant reduction in the scores of glomerular sclerosis and tubulointerstitial fibrosis. The glomerular expression of JG-12 was increased in both the sulodexide group and the sulodexide plus irbesartan group, but not in the irbesartan group. The eNOS mRNA and protein expression was decreased and the tPA mRNA and protein expression was significantly increased in the model group compared with Sham group. Sulodexide, irbesartan, and their combination reversed the decrease of eNOS expression but increased the tPA expression much more compared with model group.

CONCLUSION

Sulodexide was similar to irbesartan that can decrease proteinuria and attenuate renal lesions in 5/6 nephrectomy rats. The renal protection by sulodexide might be achieved via its impact on renal vascular endothelial cells.

New options and perspectives for proteinuria management after kidney transplantation

Proteinuria has been strongly correlated with reduced function and graft survival in kidney-transplanted patients. Data regarding new strategies in proteinuria treatment and subsequent allograft survival are lacking. Similarities between chronic graft injury and chronic kidney disease (CKD) suggest that the same therapeutic antiproteinuric tools should be effective in kidney-transplanted patients. The classic strategies to decrease proteinuria such as blood pressure control, nicotine cessation, low-salt diet, and maintaining an ideal body weight seem to be not enough to achieve proteinuria control. Improvements in our understanding of the pathogenesis of CKD have led to the identification of several novel targets for proteinuria management. In this review, we discuss novel pharmacological approaches that aim to decrease proteinuria in CKD patients, including the use of direct renin inhibitors, vitamin D analogs, pentoxifylline, and endothelin receptor antagonists. We also discuss the promise of using antifibrotic agents to treat proteinuria. The identification of new biomarkers of CKD and its progression can help in the selection of the most effective treatment for decreasing proteinuria and maintaining kidney function.

Heparanase levels are elevated in the urine and plasma of type 2 diabetes patients and associate with blood glucose levels

Heparanase is an endoglycosidase that specifically cleaves heparan sulfate side chains of heparan sulfate proteoglycans. Utilizing an ELISA method capable of detection and quantification of heparanase, we examined heparanase levels in the plasma and urine of a cohort of 29 patients diagnosed with type 2 diabetes mellitus (T2DM), 14 T2DM patients who underwent kidney transplantation, and 47 healthy volunteers. We provide evidence that heparanase levels in the urine of T2DM patients are markedly elevated compared to healthy controls (1162 ± 181 vs. 156 ± 29.6 pg/ml for T2DM and healthy controls, respectively), increase that is statistically highly significant (P<0.0001). Notably, heparanase levels were appreciably decreased in the urine of T2DM patients who underwent kidney transplantation, albeit remained still higher than healthy individuals (P<0.0001). Increased heparanase levels were also found in the plasma of T2DM patients. Importantly, urine heparanase was associated with elevated blood glucose levels, implying that glucose mediates heparanase upregulation and secretion into the urine and blood. Utilizing an in vitro system, we show that insulin stimulates heparanase secretion by kidney 293 cells, and even higher secretion is observed when insulin is added to cells maintained under high glucose conditions. These results provide evidence for a significant involvement of heparanase in diabetic complications.

Effect of sulodexide on endothelial glycocalyx and vascular permeability in patients with type 2 diabetes mellitus

AIMS/HYPOTHESIS

Endothelial glycocalyx perturbation contributes to increased vascular permeability. In the present study we set out to evaluate whether: (1) glycocalyx is perturbed in individuals with type 2 diabetes mellitus, and (2) oral glycocalyx precursor treatment improves glycocalyx properties.

METHODS

Male participants with type 2 diabetes (n = 10) and controls (n = 10) were evaluated before and after 2 months of sulodexide administration (200 mg/day). The glycocalyx dimension was estimated in two different vascular beds using sidestream dark field imaging and combined fluorescein/indocyanine green angiography for sublingual and retinal vessels, respectively. Transcapillary escape rate of albumin (TER(alb)) and hyaluronan catabolism were assessed as measures of vascular permeability.

RESULTS

Both sublingual dimensions (0.64 [0.57-0.75] μm vs 0.78 [0.71-0.85] μm, p < 0.05, medians [interquartile range]) and retinal glycocalyx dimensions (5.38 [4.88-6.59] μm vs 8.89 [4.74-11.84] μm, p < 0.05) were reduced in the type 2 diabetes group compared with the controls whereas TER(alb) was increased (5.6 ± 2.3% vs 3.7 ± 1.7% in the controls, p < 0.05). In line with these findings, markers of hyaluronan catabolism were increased with diabetes (hyaluronan 137 ± 29 vs 81 ± 8 ng/ml and hyaluronidase 78 ± 4 vs 67 ± 2 U/ml, both p < 0.05). Sulodexide increased both the sublingual and retinal glycocalyx dimensions in participants with diabetes (to 0.93 [0.83-0.99] μm and to 5.88 [5.33-6.26] μm, respectively, p < 0.05). In line, a trend towards TER(alb) normalisation (to 4.0 ± 2.3%) and decreases in plasma hyaluronidase (to 72 ± 2 U/ml, p < 0.05) were observed in the diabetes group.

CONCLUSION/INTERPRETATION

Type 2 diabetes is associated with glycocalyx perturbation and increased vascular permeability, which are partially restored following sulodexide administration. Further studies are warranted to determine whether long-term treatment with sulodexide has a beneficial effect on cardiovascular risk.

TRIAL REGISTRATION

www.trialregister.nl NTR780/ http://isrctn.org ISRCTN82695186

FUNDING

An unrestricted Novartis Foundation for Cardiovascular Excellence grant (2006) to M. Nieuwdorp/E. S. G. Stroes, Dutch Heart Foundation (grant number 2005T037).

Preclinical and clinical evidence of nephro- and cardiovascular protective effects of glycosaminoglycans

Despite advances in pharmacological treatment, diabetic nephropathy is still the leading cause of end-stage renal disease and an important cause of morbidity and mortality in diabetics. Glycosaminoglycans are long, unbranched mucopolysaccharides that play an important role in establishing a charge-selective barrier that restricts the passage of negatively charged molecules, such as albumin and other proteins, at the level of the glomerular basal membrane. Their loss is associated with loss of selectivity and proteinuria. Extensive preclinical evidence and some clinical trials suggest that glycosaminoglycans replacement is associated with improvement of glomerular selectivity and of proteinuria. Sulodexide could also have some other effects, potentially useful to reduce the renal damage and the cardiovascular disease associated with proteinuria, such as improvement of haemorheological and blood lipid parameters, an endothelium protective effect and anti-inflammatory action. This review will discuss the evidence supporting the potential nephroprotective effects of sulodexide and other glycosaminoglycans.

Nephroprotective action of glycosaminoglycans: why the pharmacological properties of sulodexide might be reconsidered

A relatively large body of evidence supports the notion that glomerular capillary wall and mesangial alterations in diabetic nephropathy involve biochemical alterations of glycoproteins in these structures. Evidence in experimental animals rendered diabetic reveals that the administration of heparin and other anionic glycoproteins can effectively prevent the biochemical alterations that promote albuminuria. Moreover, angiotensin II inhibits heparan sulfate synthesis, while heparins modulate angiotensin II signaling in glomerular cells, inhibiting aldosterone synthesis and lowering proteinuria in diabetes patients. Sulodexide, a mixture of heparin and dermatan sulfate, appears to be a promising treatment for diabetic proteinuria partially resistant to renin-angiotensin system blocking agents. Sulodexide prevents heparan sulfate degradation, thus allowing reconstruction of heparan sulfate content and restoration of glomerular basement membrane ionic permselectivity. The antiproteinuric effect appears to be mainly related to the basal proteinuria and consequently to the duration of treatment in a relatively large number of small clinical trials. On the other hand, several sulodexide pharmacodynamic properties could improve the prognosis of chronic kidney disease patients, also independently from its antiproteinuric effect. However, sulodexide development as an antiproteinuric drug needs to be continued, in order to define which kind of patients could better respond to this treatment.

Potential new therapeutic agents for diabetic kidney disease

Diabetic nephropathy is the leading cause of end-stage renal disease, and both the incidence and prevalence of diabetic nephropathy continue to increase. Currently, various treatment regimens and combinations of therapies provide only partial renoprotection. It is obvious that new approaches are desperately needed to retard the progression of diabetic nephropathy. Recently, a number of new agents have been described that have the potential to delay the progression of diabetic kidney disease and minimize the growing burden of end-stage renal disease. These include inhibitors and breakers of advanced glycation end products, receptor antagonists for advanced glycation end products, protein kinase C inhibitors, NADPH (reduced nicotinamide adenine dinucleotide phosphate) oxidase inhibitors, glycosaminoglycans, endothelin receptor antagonists, antifibrotic agents, and growth factor inhibitors. This review addresses these promising new therapeutic agents for delaying the progression of diabetic kidney disease.