Heparanase Is Essential for the Development of Acute Experimental Glomerulonephritis

Plasma for prevention and treatment of glycocalyx degradation in trauma and sepsis

The endothelial glycocalyx, a gel-like layer that lines the luminal surface of blood vessels, is composed of proteoglycans, glycoproteins, and glycosaminoglycans. The endothelial glycocalyx plays an essential role in vascular homeostasis, and its degradation in trauma and sepsis can lead to microvascular dysfunction and organ injury. While there are no proven therapies for preventing or treating endothelial glycocalyx degradation, some initial literature suggests that plasma may have a therapeutic role in trauma and sepsis patients. Overall, the literature suggesting the use of plasma as a therapy for endothelial glycocalyx degradation is non-clinical basic science or exploratory. Plasma is an established therapy in the resuscitation of patients with hemorrhage for restoration of coagulation factors. However, plasma also contains other bioactive components, including sphingosine-1 phosphate, antithrombin, and adiponectin, which may protect and restore the endothelial glycocalyx, thereby helping to maintain or restore vascular homeostasis. This narrative review begins by describing the endothelial glycocalyx in health and disease: we discuss the overlapping disease mechanisms in trauma and sepsis that lead to its damage and introduce plasma transfusion as a potential therapy for prevention and treatment of endothelial glycocalyx degradation. Second, we review the literature on plasma as an exploratory therapy for endothelial glycocalyx degradation in trauma and sepsis. Third, we discuss the safety of plasma transfusion by reviewing the adverse events associated with plasma and other blood product transfusions, and we examine modern transfusion precautions that have enhanced the safety of plasma transfusion. We conclude that the literature proposes that plasma may have the potential to prevent and treat endothelial glycocalyx degradation in trauma and sepsis, indicating the need for further research.

Impact of heparanase-2 (Hpa2) on cancer and inflammation: Advances and paradigms

HPSE2, the gene-encoding heparanase 2 (Hpa2), is mutated in urofacial syndrome (UFS), a rare autosomal recessive congenital disease attributed to peripheral neuropathy. Hpa2 lacks intrinsic heparan sulfate (HS)-degrading activity, the hallmark of heparanase (Hpa1), yet it exhibits a high affinity toward HS, thereby inhibiting Hpa1 enzymatic activity. Hpa2 regulates selected genes that promote normal differentiation, tissue homeostasis, and endoplasmic reticulum (ER) stress, resulting in antitumor, antiangiogenic, and anti-inflammatory effects. Importantly, stress conditions induce the expression of Hpa2, thus establishing a feedback loop, where Hpa2 enhances ER stress which, in turn, induces Hpa2 expression. In most cases, cancer patients who retain high levels of Hpa2 survive longer than patients bearing Hpa2-low tumors. Experimentally, overexpression of Hpa2 attenuates the growth of tumor xenografts, whereas Hpa2 gene silencing results in aggressive tumors. Studies applying conditional Hpa2 knockout (cHpa2-KO) mice revealed an essential involvement of Hpa2 contributed by the host in protecting against cancer and inflammation. This was best reflected by the distorted morphology of the Hpa2-null pancreas, including massive infiltration of immune cells, acinar to adipocyte trans-differentiation, and acinar to ductal metaplasia. Moreover, orthotopic inoculation of pancreatic ductal adenocarcinoma (PDAC) cells into the pancreas of Hpa2-null vs. wild-type mice yielded tumors that were by far more aggressive. Likewise, intravenous inoculation of cancer cells into cHpa2-KO mice resulted in a dramatically increased lung colonization reflecting the involvement of Hpa2 in restricting the formation of a premetastatic niche. Elucidating Hpa2 structure-activity-relationships is expected to support the development of Hpa2-based therapies against cancer and inflammation.

Destruction of vascular endothelial glycocalyx during formation of pre-metastatic niches

A special microenvironment called the "pre-metastatic niche" is thought to help primary tumor cells migrate to new tissues and invade them, in part because the normal barrier function of the vascular endothelium is compromised. While the primary tumor itself can promote the creation of such niches by secreting pro-metastatic factors, the underlying molecular mechanisms are still poorly understood. Here, we show that the injection of primary tumor-secreted pro-metastatic factors from B16F10 melanoma or 4T1 breast cancer cells into healthy mice can induce the destruction of the vascular endothelial glycocalyx, which is a polysaccharide coating on the vascular endothelial lumen that normally inhibits tumor cell passage into and out of the circulation. However, when human umbilical vein endothelial cultures were treated in vitro with these secreted pro-metastatic factors, no significant destruction of the glycocalyx was observed, implying that this destruction requires a complex in vivo microenvironment. The tissue section analysis revealed that secreted pro-metastatic factors could clearly upregulate macrophage-related molecules such as CD11b and tumor necrosis factor-α (TNF-α) in the heart, liver, spleen, lung, and kidney, which is associated with the upregulation and activation of heparanase. In addition, macrophage depletion significantly attenuated the degradation of the vascular endothelial glycocalyx induced by secreted pro-metastatic factors. This indicates that the secreted pro-metastatic factors that destroy the vascular endothelial glycocalyx rely primarily on macrophages. Our findings suggest that the formation of pre-metastatic niches involves degradation of the vascular endothelial glycocalyx, which may hence be a useful target for developing therapies to inhibit cancer metastasis.

Discovery of a novel tetrahydroimidazo[1,2-a]pyridine-5-carboxylic acid derivative as a potent and selective heparanase-1 inhibitor utilizing an improved synthetic approach

Heparanase-1 (HPSE1) is an endo-β-d-glucuronidase that catalyzes degradation of heparan sulfate proteoglycans. Inhibition of HPSE1 appears to be a useful therapeutic target against cancer and proteinuric kidney diseases. We previously reported tetrahydroimidazo[1,2-a]pyridine 2 as a potent HPSE1 inhibitor after optimization of the synthetic reaction. However, synthesis of 2 involves a total of 19 steps, including a cyclization process that accompanies a strong odor due to the use of Lawesson's reagent and an epimerization reaction; furthermore, 2 exhibited insufficient selectivity for HPSE1 over exo-β-d-glucuronidase (GUSβ) and glucocerebrosidase (GBA), which also needed to be addressed. First, the cyclization reaction was optimized to synthesize tetrahydroimidazo[1,2-a]pyridine without using Lawesson's reagent or epimerization, with reference to previous reports. Next, 16 and 17 containing a bulkier substituent at position 6 than the 6-methoxyl group in 2 were designed and synthesized using the improved cyclization conditions, so that the synthetic route of 16 and 17 was shortened by five steps as compared with that of 2. The inhibitory activities of 16 and 17 against GUSβ and GBA were reduced as compared with those of 2, that is, the compounds showed improved selectivity for HPSE1 over GUSβ and GBA. In addition, 16 showed enhanced inhibitory activity against HPSE1 as compared with that of 2. Compound 16 appears promising as an HPSE1 inhibitor with therapeutic potential due to its highly potent inhibitory activity against HPSE1 with high selectivity for HPSE1.

Endothelial cell activation and glycocalyx shedding - potential as biomarkers in patients with lupus nephritis

Lupus nephritis (LN) is a common and severe manifestation of systemic lupus erythematosus and an important cause of acute and chronic kidney injury. Early diagnosis of LN and preventing relapses are key to preserving renal reserve. However, due to the complexity and heterogeneity of the disease, clinical management remains challenging. Kidney biopsy remains the gold standard for confirming the diagnosis of LN and subsequent assessment of kidney histopathology, but it is invasive and cannot be repeated frequently. Current clinical indicators of kidney function such as proteinuria and serum creatinine level are non-specific and do not accurately reflect histopathological changes, while anti-dsDNA antibody and C3 levels reflect immunological status but not kidney injury. Identification of novel and specific biomarkers for LN is prerequisite to improve management. Renal function deterioration is associated with changes in the endothelial glycocalyx, a delicate gel-like layer located at the interface between the endothelium and bloodstream. Inflammation induces endothelial cell activation and shedding of glycocalyx constituents into the circulation. This review discusses the potential role of soluble glycocalyx components as biomarkers of active LN, especially in patients in whom conventional serological and biochemical markers do not appear helpful.

Structure-based lead optimization to improve potency and selectivity of a novel tetrahydroimidazo[1,2-a]pyridine-5-carboxylic acid series of heparanase-1 inhibitor

Heparanase-1 (HPSE1) is an endo-β-d-glucuronidase that is the only mammalian enzyme known to cleave heparan sulfate (HS) of heparan sulfate proteoglycans (HSPG), a key component of the glycocalyx layer of the vascular endothelium matrix. Inhibition of HPSE1 has therapeutic potential for cancer and proteinuric kidney diseases. We previously reported that 2 showed a moderate potency as an HPSE1 inhibitor and an issue of selectivity against exo-β-d-glucuronidase (GUSβ) and glucocerebrosidase (GBA) remained. A structure-based lead optimization of 2 using X-ray co-crystal structure analysis and fragment molecular orbital calculation resulted in 4e, which showed a more than 7-fold increase in HPSE1 inhibitory activity. The subsequent introduction of a methyl group into the 6-hydroxy group of 4e resulted in 18 with reduced inhibitory activities against GUSβ and GBA while maintaining the inhibitory activity against HPSE1. The inhibitory activities of 18 against serum HPSE1 in mice were significant and lasted for 4 h at doses of 3, 30, and 100 mg/kg. Compound 18 could be a novel lead compound for HPSE1 inhibitors with improved inhibitory activity against HPSE1 and increased HPSE1 selectivity over GUSβ and GBA.

Glycosaminoglycans and fucoidan have a protective effect on experimental glomerulonephritis

Background: The glomerular endothelial glycocalyx is degraded during inflammation. The glycocalyx plays a pivotal role in endothelial function and is involved in many processes including binding of chemokines and cytokines, leukocyte trafficking, and preventing proteinuria. HS-based therapeutics are a promising novel class of anti-inflammatory drugs to restore a compromised endothelial glycocalyx under inflammatory conditions. Recently, we demonstrated that treatment with HS extracted from unstimulated glomerular endothelial glycocalyx (unstimulated HS_glx) reduced albuminuria during anti-GBM induced glomerulonephritis. Since endothelial HS domains are distinct in unstimulated versus inflammatory conditions, we hypothesized that 1) unstimulated HS_glx, 2) LPS-stimulated HS_glx, 3) the HS-mimetic fucoidan and 4) the glycosaminoglycan preparation sulodexide, which is a mixture of low molecular weight heparin and dermatan sulfate, might have different beneficial effects in experimental glomerulonephritis. Methods: The effect of unstimulated HS_glx, LPS HS_glx, Laminaria japonica fucoidan, or sulodexide on experimental glomerulonephritis was tested in LPS-induced glomerulonephritis in mice. Analyses included urinary albumin creatinine measurement, cytokine expression in plasma and renal cortex, and renal influx of immune cells determined by flow cytometry and immunofluorescence staining. Furthermore, the observed in vivo effects were evaluated in cultured glomerular endothelial cells and peripheral blood mononuclear cells by measuring cytokine and ICAM-1 expression levels. The ability of the compounds to inhibit heparanase activity was assessed in a heparanase activity assay. Results: Treatment of mice with LPS HS_glx or sulodexide near-significantly attenuated LPS-induced proteinuria. All treatments reduced plasma MCP-1 levels, whereas only fucoidan reduced IL-6 and IL-10 plasma levels. Moreover, all treatments reversed cortical ICAM-1 mRNA expression and both fucoidan and sulodexide reversed cortical IL-6 and nephrin mRNA expression. Sulodexide decreased renal influx of CD45⁺ immune cells whereas renal influx of macrophages and granulocytes remained unaltered for all treatments. Although all compounds inhibited HPSE activity, fucoidan and sulodexide were the most potent inhibitors. Notably, fucoidan and sulodexide decreased LPS-induced mRNA expression of ICAM-1 and IL-6 by cultured glomerular endothelial cells. Conclusion: Our data show a potentially protective effect of glycosaminoglycans and fucoidan in experimental glomerulonephritis. Future research should be aimed at the further identification of defined HS structures that have therapeutic potential in the treatment of glomerular diseases.

Heparanase-2 protein and peptides have a protective effect on experimental glomerulonephritis and diabetic nephropathy

Introduction: The endothelial glycocalyx degrading enzyme heparanase-1 (HPSE1) is a major contributor to kidney diseases, such as glomerulonephritis and diabetic nephropathy. Therefore, inhibition of HPSE1 could be an interesting therapeutic strategy to treat glomerular diseases. A possible HPSE1 inhibitor is heparanase-2 (HPSE2) because HPSE2 is a structural homolog of HPSE1 without enzymatic activity. The importance of HPSE2 has been recently demonstrated in HPSE2-deficient mice, since these mice developed albuminuria and died within a few months after birth. We postulate that inhibition of HPSE1 activity by HPSE2 is a promising therapeutic strategy to target albuminuria and resulting renal failure. Methods: First, we evaluated the regulation of HPSE2 expression in anti-GBM and LPS-induced glomerulonephritis, streptozotocin-induced diabetic nephropathy, and adriamycin nephropathy by qPCR and ELISA. Second, we measured the HPSE1 inhibiting capacity of HPSE2 protein and 30 different HPSE2 peptides and assessed their therapeutic potential in both experimental glomerulonephritis and diabetic nephropathy using kidney function and cortical mRNA expression of HPSE1 and cytokines as outcome parameters. Results: HPSE2 expression was downregulated under inflammatory and diabetic conditions, whereas this effect on HPSE2 expression was absent with HPSE1 inhibition and in HPSE1-deficient mice. Both HPSE2 protein and a mixture of the three most potent HPSE1 inhibitory HPSE2 peptides could prevent LPS and streptozotocin induced kidney injury. Discussion: Taken together, our data suggest a protective effect of HPSE2 in (experimental) glomerular diseases and support the therapeutic potential of HPSE2 as HPSE1 inhibitor in glomerular diseases.

Peroxisome proliferator-activated receptor ɣ agonist mediated inhibition of heparanase expression reduces proteinuria

BACKGROUND

Proteinuria is associated with many glomerular diseases and a risk factor for the progression to renal failure. We previously showed that heparanase (HPSE) is essential for the development of proteinuria, whereas peroxisome proliferator-activated receptor ɣ (PPARɣ) agonists can ameliorate proteinuria. Since a recent study showed that PPARɣ regulates HPSE expression in liver cancer cells, we hypothesized that PPARɣ agonists exert their reno-protective effect by inhibiting glomerular HPSE expression.

METHODS

Regulation of HPSE by PPARɣ was assessed in the adriamycin nephropathy rat model, and cultured glomerular endothelial cells and podocytes. Analyses included immunofluorescence staining, real-time PCR, heparanase activity assay and transendothelial albumin passage assay. Direct binding of PPARɣ to the HPSE promoter was evaluated by the luciferase reporter assay and chromatin immunoprecipitation assay. Furthermore, HPSE activity was assessed in 38 type 2 diabetes mellitus (T2DM) patients before and after 16/24 weeks treatment with the PPARɣ agonist pioglitazone.

FINDINGS

Adriamycin-exposed rats developed proteinuria, an increased cortical HPSE and decreased heparan sulfate (HS) expression, which was ameliorated by treatment with pioglitazone. In line, the PPARɣ antagonist GW9662 increased cortical HPSE and decreased HS expression, accompanied with proteinuria in healthy rats, as previously shown. In vitro, GW9662 induced HPSE expression in both endothelial cells and podocytes, and increased transendothelial albumin passage in a HPSE-dependent manner. Pioglitazone normalized HPSE expression in adriamycin-injured human endothelial cells and mouse podocytes, and adriamycin-induced transendothelial albumin passage was reduced as well. Importantly, we demonstrated a regulatory effect of PPARɣ on HPSE promoter activity and direct PPARy binding to the HPSE promoter region. Plasma HPSE activity of T2DM patients treated with pioglitazone for 16/24 weeks was related to their hemoglobin A1c and showed a moderate, near significant correlation with plasma creatinine levels.

INTERPRETATION

PPARɣ-mediated regulation of HPSE expression appears an additional mechanism explaining the anti-proteinuric and renoprotective effects of thiazolidinediones in clinical practice.

FUNDING

This study was financially supported by the Dutch Kidney Foundation, by grants 15OI36, 13OKS023 and 15OP13. Consortium grant LSHM16058-SGF (GLYCOTREAT; a collaboration project financed by the PPP allowance made available by Top Sector Life Sciences & Health to the Dutch Kidney Foundation to stimulate public-private partnerships).

Lead identification of novel tetrahydroimidazo[1,2-a]pyridine-5-carboxylic acid derivative as a potent heparanase-1 inhibitor

Heparanase-1 (HPSE1) is an endo-β-d-glucuronidase that cleaves heparan sulfate proteoglycans into short-chain heparan sulfates (HS). The inhibition of HPSE1 has therapeutic potential for proteinuric diseases such as nephrotic syndrome because increased HPSE1 expression is associated with the loss of HS in the glomerular basement membrane, leading to the development of proteinuria. The present study examined the generation of a lead compound focusing on chemical structures with a sugar moiety, such as glycosides and sugar analogs, taking their physical properties into consideration. Compound 10, an exo-β-d-glucuronidase (GUSβ) inhibitor, was found to have a weak inhibitory activity against endo-β-d-glucuronidase HPSE1. A structure-activity relationship study using the X-ray co-crystal structure of 10 and HPSE1 resulted in 12a, which showed a more than 14-fold increase in HPSE1 inhibitory activity compared with that of 10. Compound 12a could be a novel lead compound for the development of a potent HPSE1 inhibitor.

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: A Novel Therapeutic Target for the Treatment of Atherosclerosis

Cardiovascular disease (CVD) is the leading cause of death and disability worldwide, and its management places a huge burden on healthcare systems through hospitalisation and treatment. Atherosclerosis is a chronic inflammatory disease of the arterial wall resulting in the formation of lipid-rich, fibrotic plaques under the subendothelium and is a key contributor to the development of CVD. As such, a detailed understanding of the mechanisms involved in the development of atherosclerosis is urgently required for more effective disease treatment and prevention strategies. Heparanase is the only mammalian enzyme known to cleave heparan sulfate of heparan sulfate proteoglycans, which is a key component of the extracellular matrix and basement membrane. By cleaving heparan sulfate, heparanase contributes to the regulation of numerous physiological and pathological processes such as wound healing, inflammation, tumour angiogenesis, and cell migration. Recent evidence suggests a multifactorial role for heparanase in atherosclerosis by promoting underlying inflammatory processes giving rise to plaque formation, as well as regulating lesion stability. This review provides an up-to-date overview of the role of heparanase in physiological and pathological processes with a focus on the emerging role of the enzyme in atherosclerosis.

Heparanase promotes endothelial-to-mesenchymal transition in diabetic glomerular endothelial cells through mediating ERK signaling

Glomerular endothelial cells (GEnCs) dysfunction occurs at the early stage of diabetic nephropathy (DN). One of its characteristics is endothelial-to-mesenchymal transition (EndMT). Heparanase (HPSE) is the only known mammalian endoglycosidase capable of degrading heparin sulfates and has a prominent role in DN pathogenesis. However, whether HPSE induces EndMT of GEnCs remains unknown. This study aimed to determine the effect and potential mechanism of HPSE on GEnCs phenotype under high-glucose conditions. In the early development of streptozotocin (STZ)-induced diabetic mice, HPSE overexpression was positively correlated with renal injury and the number of GEnCs undergoing EndMT, which was characterized by loss of endothelial marker CD31 and gain of mesenchymal markers including α-SMA and Snail1/2 by double immunofluorescence staining. Bioinformatics analysis revealed a positive correlation between HPSE and ERK. The counts of double positive staining of CD31 and p-ERK1/2 was significantly increased in the glomeruli of STZ-induced diabetic mice compared with sham mice. In cultured GEnCs, high glucose dramatically upregulated the expressions of HPSE and p-ERK1/2, both of which were markedly blocked by HPSE siRNA. Furthermore, recombinant mouse HPSE (rmHPSE) promoted the expressions of mesenchymal markers and p-ERK1/2 in a dosage- and time-dependent manner. U0126, a specific MEK/ERK inhibitor, significantly inhibited either high glucose or rmHPSE-induced EndMT of GEnCs. These data indicate that high glucose induces EndMT of GEnCs at least partially through upregulating HPSE and that HPSE promotes EndMT of GEnCs via activating ERK signaling. This study improves understanding the crucial role of HPSE in DN development and progression.

Renal microvascular endothelial cell responses in sepsis-induced acute kidney injury

Microvascular endothelial cells in the kidney have been a neglected cell type in sepsis-induced acute kidney injury (sepsis-AKI) research; yet, they offer tremendous potential as pharmacological targets. As endothelial cells in distinct cortical microvascular segments are highly heterogeneous, this Review focuses on endothelial cells in their anatomical niche. In animal models of sepsis-AKI, reduced glomerular blood flow has been attributed to inhibition of endothelial nitric oxide synthase activation in arterioles and glomeruli, whereas decreased cortex peritubular capillary perfusion is associated with epithelial redox stress. Elevated systemic levels of vascular endothelial growth factor, reduced levels of circulating sphingosine 1-phosphate and loss of components of the glycocalyx from glomerular endothelial cells lead to increased microvascular permeability. Although coagulation disbalance occurs in all microvascular segments, the molecules involved differ between segments. Induction of the expression of adhesion molecules and leukocyte recruitment also occurs in a heterogeneous manner. Evidence of similar endothelial cell responses has been found in kidney and blood samples from patients with sepsis. Comprehensive studies are needed to investigate the relationships between segment-specific changes in the microvasculature and kidney function loss in sepsis-AKI. The application of omics technologies to kidney tissues from animals and patients will be key in identifying these relationships and in developing novel therapeutics for sepsis.

Increased Plasma Heparanase Activity and Endothelial Glycocalyx Degradation in Dengue Patients Is Associated With Plasma Leakage

Background

Endothelial hyper-permeability with plasma leakage and thrombocytopenia are predominant features of severe dengue virus infection. It is well established that heparanase, the endothelial glycocalyx degrading enzyme, plays a major role in various diseases with vascular leakage. It is yet to be elucidated whether heparanase activity plays a major role in dengue-associated plasma leakage. Moreover, the major source of heparanase secretion and activation in dengue remains elusive. Since a relatively high amount of heparanase is stored in platelets, we postulate that heparanase released by activated platelets contributes to the increased plasma heparanase activity during dengue virus infection.

Methods

Heparanase activity (plasma and urine), and heparan sulfate and syndecan-1 (plasma levels) were measured in dengue patients with thrombocytopenia in acute phase (n=30), during course of disease (n=10) and in convalescent phase (n=25). Associations with clinical parameters and plasma leakage markers were explored. Platelets from healthy donors were stimulated with dengue non-structural protein-1, DENV2 virus and thrombin to evaluate heparanase release and activity ex vivo.

Results

Heparanase activity was elevated in acute dengue and normalized during convalescence. Similarly, glycocalyx components, such as heparan sulfate and syndecan-1, were increased in acute dengue and restored during convalescence. Increased heparanase activity correlated with the endothelial dysfunction markers heparan sulfate and syndecan-1, as well as clinical markers of plasma leakage such as ascites, hematocrit concentration and gall-bladder wall thickening. Notably, platelet number inversely correlated with heparanase activity. Ex vivo incubation of platelets with thrombin and live DENV2 virus, but not dengue virus-2-derived non-structural protein 1 induced heparanase release from platelets.

Conclusion

Taken together, our findings suggest that the increase of heparanase activity in dengue patients is associated with endothelial glycocalyx degradation and plasma leakage. Furthermore, thrombin or DENV2 activated platelets may be considered as a potential source of heparanase.

Helicobacter pylori-Induced Heparanase Promotes H. pylori Colonization and Gastritis

Chronic gastritis caused by Helicobacter pylori (H. pylori) infection has been widely recognized as the most important risk factor for gastric cancer. Analysis of the interaction between the key participants in gastric mucosal immunity and H. pylori infection is expected to provide important insights for the treatment of chronic gastritis and the prevention of gastric cancer. Heparanase is an endoglycosidase that degrades heparan sulfate, resulting in remodeling of the extracellular matrix thereby facilitating the extravasation and migration of immune cells towards sites of inflammation. Heparanase also releases heparan sulfate-bound cytokines and chemokines that further promote directed motility and recruitment of immune cells. Heparanase is highly expressed in a variety of inflammatory conditions and diseases, but its role in chronic gastritis has not been sufficiently explored. In this study, we report that H. pylori infection promotes up-regulation of heparanase in gastritis, which in turn facilitates the colonization of H. pylori in the gastric mucosa, thereby aggravating gastritis. By sustaining continuous activation, polarization and recruitment of macrophages that supply pro-inflammatory and pro-tumorigenic cytokines (i.e., IL-1, IL-6, IL-1β, TNF-α, MIP-2, iNOS), heparanase participates in the generation of a vicious circle, driven by enhanced NFκB and p38-MAPK signaling, that supports the development and progression of gastric cancer. These results suggest that inhibition of heparanase may block this self-sustaining cycle, and thereby reduce the risk of gastritis and gastric cancer.

Laminar flow substantially affects the morphology and functional phenotype of glomerular endothelial cells

Shear stress induced by laminar blood flow has a profound effect on the morphology and functional phenotype of macrovascular endothelial cells. The influence of laminar flow on the glomerular microvascular endothelium, however, remains largely elusive. The glomerular endothelium, including its glycocalyx, is a crucial part of the glomerular filtration barrier, which is involved in blood filtration. We therefore investigated the influence of laminar flow-induced shear stress on the glomerular endothelium. Conditionally immortalized mouse glomerular endothelial cells were cultured for 7 days under a laminar flow of 5 dyn/cm2 to mimic the glomerular blood flow. The cells were subsequently analysed for changes in morphology, expression of shear stress-responsive genes, nitric oxide production, glycocalyx composition, expression of anti-oxidant genes and the inflammatory response. Culture under laminar flow resulted in cytoskeletal rearrangement and cell alignment compared to static conditions. Moreover, production of nitric oxide was increased and the expression of the main functional component of the glycocalyx, Heparan Sulfate, was enhanced in response to shear stress. Furthermore, glomerular endothelial cells demonstrated a quiescent phenotype under flow, characterized by a decreased expression of the pro-inflammatory gene ICAM-1 and increased expression of the anti-oxidant enzymes HO-1 and NQO1. Upon exposure to the inflammatory stimulus TNFα, however, glomerular endothelial cells cultured under laminar flow showed an enhanced inflammatory response. In conclusion, laminar flow extensively affects the morphology and functional phenotype of glomerular endothelial cells in culture. Furthermore, glomerular endothelial cells respond differently to shear stress compared to macrovascular endothelium. To improve the translation of future in vitro studies with glomerular endothelial cells to the in vivo situation, it appears therefore crucial to culture glomerular endothelial cells under physiological flow conditions.

Endothelial Heparan Sulfate Proteoglycans in Sepsis: The Role of the Glycocalyx

There is increasing recognition of the importance of the endothelial glycocalyx and its in vivo manifestation, the endothelial surface layer, in vascular homeostasis. Heparan sulfate proteoglycans (HSPGs) are a major structural constituent of the endothelial glycocalyx and serve to regulate vascular permeability, microcirculatory tone, leukocyte and platelet adhesion, and hemostasis. During sepsis, endothelial HSPGs are shed through the induction of "sheddases" such as heparanase and matrix metalloproteinases, leading to loss of glycocalyx integrity and consequent vascular dysfunction. Less well recognized is that glycocalyx degradation releases HSPG fragments into the circulation, which can shape the systemic consequences of sepsis. In this review, we will discuss (1) the normal, homeostatic functions of HSPGs within the endothelial glycocalyx, (2) the pathological changes in HSPGs during sepsis and their consequences on the local vascular bed, and (3) the systemic consequences of HSPG degradation. In doing so, we will identify potential therapeutic targets to improve vascular function during sepsis as well as highlight key areas of uncertainty that require further mechanistic investigation.

Glomerular Endothelial Cells as Instigators of Glomerular Sclerotic Diseases

Glomerular endothelial cell (GEnC) dysfunction is important in the pathogenesis of glomerular sclerotic diseases, including Focal Segmental Glomerulosclerosis (FSGS) and overt diabetic nephropathy (DN). GEnCs form the first cellular barrier in direct contact with cells and factors circulating in the blood. Disturbances in these circulating factors can induce GEnC dysfunction. GEnC dysfunction occurs in early stages of FSGS and DN, and is characterized by a compromised endothelial glycocalyx, an inflammatory phenotype, mitochondrial damage and oxidative stress, aberrant cell signaling, and endothelial-to-mesenchymal transition (EndMT). GEnCs are in an interdependent relationship with podocytes and mesangial cells, which involves bidirectional cross-talk via intercellular signaling. Given that GEnC behavior directly influences podocyte function, it is conceivable that GEnC dysfunction may culminate in podocyte damage, proteinuria, subsequent mesangial activation, and ultimately glomerulosclerosis. Indeed, GEnC dysfunction is sufficient to cause podocyte injury, proteinuria and activation of mesangial cells. Aberrant gene expression patterns largely contribute to GEnC dysfunction and epigenetic changes seem to be involved in causing aberrant transcription. This review summarizes literature that uncovers the importance of cross-talk between GEnCs and podocytes, and GEnCs and mesangial cells in the context of the development of FSGS and DN, and the potential use of GEnCs as efficacious cellular target to pharmacologically halt development and progression of DN and FSGS.

Increased Plasma Heparanase Activity in COVID-19 Patients

Reports suggest a role of endothelial dysfunction and loss of endothelial barrier function in COVID-19. It is well established that the endothelial glycocalyx-degrading enzyme heparanase contributes to vascular leakage and inflammation. Low molecular weight heparins (LMWH) serve as an inhibitor of heparanase. We hypothesize that heparanase contributes to the pathogenesis of COVID-19, and that heparanase may be inhibited by LMWH. To test this hypothesis, heparanase activity and heparan sulfate levels were measured in plasma of healthy controls (n = 10) and COVID-19 patients (n = 48). Plasma heparanase activity and heparan sulfate levels were significantly elevated in COVID-19 patients. Heparanase activity was associated with disease severity including the need for intensive care, lactate dehydrogenase levels, and creatinine levels. Use of prophylactic LMWH in non-ICU patients was associated with a reduced heparanase activity. Since there is no other clinically applied heparanase inhibitor currently available, therapeutic treatment of COVID-19 patients with low molecular weight heparins should be explored.

Beneficial non-anticoagulant mechanisms underlying heparin treatment of COVID-19 patients

Coronavirus disease-2019 (COVID-19) is associated with severe inflammation in mainly the lung, and kidney. Reports suggest a beneficial effect of the use of heparin/low molecular weight heparin (LMWH) on mortality in COVID-19. In part, this beneficial effect could be explained by the anticoagulant properties of heparin/LMWH. Here, we summarise potential beneficial, non-anticoagulant mechanisms underlying treatment of COVID-19 patients with heparin/LMWH, which include: (i) Inhibition of heparanase activity, responsible for endothelial leakage; (ii) Neutralisation of chemokines, and cytokines; (iii) Interference with leukocyte trafficking; (iv) Reducing viral cellular entry, and (v) Neutralisation of extracellular cytotoxic histones. Considering the multiple inflammatory and pathogenic mechanisms targeted by heparin/LMWH, it is warranted to conduct clinical studies that evaluate therapeutic doses of heparin/LMWH in COVID-19 patients. In addition, identification of specific heparin-derived sequences that are functional in targeting non-anticoagulant mechanisms may have even higher therapeutic potential for COVID-19 patients, and patients suffering from other inflammatory diseases.

Involvement of Syndecan-1 and Heparanase in Cancer and Inflammation

The cell surface heparan sulfate proteoglycan Syndecan-1 acts as an important co-receptor for receptor tyrosine kinases and chemokine receptors, and as an adhesion receptor for structural glycoproteins of the extracellular matrix. It serves as a substrate for heparanase, an endo-β-glucuronidase that degrades specific domains of heparan sulfate carbohydrate chains and thereby alters the functional status of the proteoglycan and of Syndecan-1-bound ligands. Syndecan-1 and heparanase show multiple levels of functional interactions, resulting in mutual regulation of their expression, processing, and activity. These interactions are of particular relevance in the context of inflammation and malignant disease. Studies in animal models have revealed a mechanistic role of Syndecan-1 and heparanase in the regulation of contact allergies, kidney inflammation, multiple sclerosis, inflammatory bowel disease, and inflammation-associated tumorigenesis. Moreover, functional interactions between Syndecan-1 and heparanase modulate virtually all steps of tumor progression as defined in the Hallmarks of Cancer. Due to their prognostic value in cancer, and their mechanistic involvement in tumor progression, Syndecan-1 and heparanase have emerged as important drug targets. Data in preclinical models and preclinical phase I/II studies have already yielded promising results that provide a translational perspective.

Heparanase: Cloning, Function and Regulation

In 2019, we mark the 20th anniversary of the cloning of the human heparanase gene. Heparanase remains the only known enzyme to cleave heparan sulfate, which is an abundant component of the extracellular matrix. Thus, elucidating the mechanisms underlying heparanase expression and activity is critical to understanding its role in healthy and pathological settings. This chapter provides a historical account of the race to clone the human heparanase gene, describes the intracellular and extracellular function of the enzyme, and explores the various mechanisms regulating heparanase expression and activity at the gene, transcript, and protein level.

Glomerular endothelial cell heterogeneity in Alport syndrome

Glomerular endothelial cells (GEC) are a crucial component of the glomerular physiology and their damage contributes to the progression of chronic kidney diseases. How GEC affect the pathology of Alport syndrome (AS) however, is unclear. We characterized GEC from wild type (WT) and col4α5 knockout AS mice, a hereditary disorder characterized by progressive renal failure. We used endothelial-specific Tek-tdTomato reporter mice to isolate GEC by FACS and performed transcriptome analysis on them from WT and AS mice, followed by in vitro functional assays and confocal and intravital imaging studies. Biopsies from patients with chronic kidney disease, including AS were compared with our findings in mice. We identified two subpopulations of GEC (dim^tdT and bright^tdT) based on the fluorescence intensity of the Tek^tdT signal. In AS mice, the bright^tdT cell number increased and presented differential expression of endothelial markers compared to WT. RNA-seq analysis revealed differences in the immune and metabolic signaling pathways. In AS mice, dim^tdT and bright^tdT cells had different expression profiles of matrix-associated genes (Svep1, Itgβ6), metabolic activity (Apom, Pgc1α) and immune modulation (Apelin, Icam1) compared to WT mice. We confirmed a new pro-inflammatory role of Apelin in AS mice and in cultured human GEC. Gene modulations were identified comparable to the biopsies from patients with AS and focal segmental glomerulosclerosis, possibly indicating that the same mechanisms apply to humans. We report the presence of two GEC subpopulations that differ between AS and healthy mice or humans. This finding paves the way to a better understanding of the pathogenic role of GEC in AS progression and could lead to novel therapeutic targets.

Sirtuin 1 and endothelial glycocalyx

Sirtuin1 deficiency or reduced activity comprises one of the hallmarks of diseases as diverse as chronic cardiovascular, renal, and metabolic, some malignancies, and infections, as well as aging-associated diseases. In a mouse model of endothelium-limited defect in sirtuin 1 deacetylase activity, we found a dramatic reduction in the volume of endothelial glycocalyx. This was associated with the surge in the levels of one of key scaffolding heparan sulfate proteoglycans of endothelial glycocalyx, syndecan-4, and specifically, its extracellular domain (ectodomain). We found that the defect in endothelial sirtuin 1 deacetylase activity is associated with (a) elevated basal and stimulated levels of superoxide generation (via the FoxO1 over-acetylation mechanism) and (b) increased nuclear translocation of NF-kB (via p65 over-acetylation mechanism). These findings laid the foundation for the proposed novel function of sirtuin 1, namely, the maintenance of endothelial glycocalyx, particularly manifest in conditions associated with sirtuin 1 depletion. In the forthcoming review, we summarize the emerging conceptual framework of the enhanced glycocalyx degradation in the states of defective endothelial sirtuin 1 function, thus explaining a broad footprint of the syndrome of endothelial dysfunction, from impaired flow-induced nitric oxide production, deterrent leukocytes infiltration, increased endothelial permeability, coagulation, and pro-inflammatory changes to development of microvascular rarefaction and progression of an underlying disease.

Role of Heparanase in Macrophage Activation

Macrophages represent one of the most diverse immunocyte populations, constantly shifting between various phenotypes/functional states. In addition to execution of vital functions in normal physiological conditions, macrophages represent a key contributing factor in the pathogenesis of some of the most challenging diseases, such as chronic inflammatory disorders, diabetes and its complications, and cancer. Macrophage polarization studies focus primarily on cytokine-mediated mechanisms. However, to explore the full spectrum of macrophage action, additional, non-cytokine pathways responsible for altering macrophage phenotype have to be taken into consideration as well. Heparanase, the only known mammalian endoglycosidase that cleaves heparan sulfate glycosaminoglycans, has been shown to contribute to the altered macrophage phenotypes in vitro and in numerous animal models of inflammatory conditions, occurring either in the presence of microbial products or in the setting of non-infectious "aseptic" inflammation. Here we discuss the involvement of heparanase in shaping macrophage responses and provide information that may help to establish the rationale for heparanase-targeting interventions aimed at preventing abnormal macrophage activation in various disorders.

Heparanase in Kidney Disease

The primary filtration of blood occurs in the glomerulus in the kidney. Destruction of any of the layers of the glomerular filtration barrier might result in proteinuric disease. The glomerular endothelial cells and especially its covering layer, the glycocalyx, play a pivotal role in development of albuminuria. One of the main sulfated glycosaminoglycans in the glomerular endothelial glycocalyx is heparan sulfate. The endoglycosidase heparanase degrades heparan sulfate, thereby affecting glomerular barrier function, immune reactivity and inflammation. Increased expression of glomerular heparanase correlates with loss of glomerular heparan sulfate in many glomerular diseases. Most importantly, heparanase knockout in mice prevented the development of albuminuria after induction of experimental diabetic nephropathy and experimental glomerulonephritis. Therefore, heparanase could serve as a pharmacological target for glomerular diseases. Several factors that regulate heparanase expression and activity have been identified and compounds aiming to inhibit heparanase activity are currently explored.

Targeting Heparanase in Cancer: Inhibition by Synthetic, Chemically Modified, and Natural Compounds

Heparanase is an endoglycosidase involved in remodeling the extracellular matrix and thereby in regulating multiple cellular processes and biological activities. It cleaves heparan sulfate (HS) side chains of HS proteoglycans into smaller fragments and hence regulates tissue morphogenesis, differentiation, and homeostasis. Heparanase is overexpressed in various carcinomas, sarcomas, and hematological malignancies, and its upregulation correlates with increased tumor size, tumor angiogenesis, enhanced metastasis, and poor prognosis. In contrast, knockdown or inhibition of heparanase markedly attenuates tumor progression, further underscoring the potential of anti-heparanase therapy. Heparanase inhibitors were employed to interfere with tumor progression in preclinical studies, and selected heparin mimetics are being examined in clinical trials. However, despite tremendous efforts, the discovery of heparanase inhibitors with high clinical benefit and minimal adverse effects remains a therapeutic challenge. This review discusses the key roles of heparanase in cancer progression focusing on the status of natural, chemically modified, and synthetic heparanase inhibitors in various types of malignancies.

The Pulmonary Endothelial Glycocalyx in ARDS: A Critical Role for Heparan Sulfate

The endothelial glycocalyx is a glycosaminoglycan-enriched endovascular layer that, with the development of novel fixation and in vivo microscopy techniques, has been increasingly recognized as a major contributor to vascular homeostasis. Sepsis-associated degradation of the endothelial glycocalyx mediates the onset of the alveolar microvascular dysfunction characteristic of sepsis-induced lung injury (such as the Acute Respiratory Distress Syndrome, ARDS). Emerging evidence indicates that processes of glycocalyx reconstitution are necessary for endothelial repair and, as such, are promising therapeutic targets to accelerate lung injury recovery. This review discusses what has been learned about the homeostatic and pathophysiologic role of the pulmonary endothelial glycocalyx during lung health and injury, with the goal to identify promising new areas for future mechanistic investigation.

Xiao-Shen-Formula, a Traditional Chinese Medicine, Improves Glomerular Hyper-Filtration in Diabetic Nephropathy via Inhibiting Arginase Activation and Heparanase Expression

Hyperglycemia induces glomerular hyper-filtration, which contributes to the development of diabetic nephropathy (DN), a condition that remains a challenge for treatment. The present study investigated the effect of Xiao-Shen-Formula (XSF) used for treatment of renal injury in type 1 DN mice model induced by streptozotocin (STZ) and its underlying mechanism in cultured human glomerular endothelial cell (hGECs). Studies were performed using control, diabetic DN, DN treated with XSF groups (1 g/kg/d, LXSF or 3 g/kg/d, HXSF) for 6 weeks and hGECs were post-treated with mice serum containing HXSF (MS-HXSF) and arginase inhibitor (ABH, 100 μM) in high glucose medium. HXSF treatment restored STZ-induced renal hyper-filtration, glomerulosclerosis, renal microvascular remodeling and the increased levels of systemic reactive oxidative species and inflammatory cytokines, accompanied by preventing the decreased expression of glomerular heparin sulfate and the increased levels of cortical heparanase and argianse2 protein and arginase activity. In hGECs study, MS-HXSF ameliorated the enhancement in arginase activity, the protein/mRNA expression of heparanase, mRNA levels of vascular cell adhesion molecule-1, intercellular adhesion molecule-1, monocyte chemoattractant protein-1 and permeability of hGECs monolayers as well as the depression of nitric oxide production. Besides all these protective effects, XSF blunted the mRNA expression of TNF-α in vivo and vitro studies as well, which was not changed by the post-treatment of ABH or HXSF plus ABH. This study demonstrated that the protective effect of XSF might be related with vascular prevention, anti-inflammation and anti-oxidation through intervening multi-targets including glomerular endothelial arginase-heparanase signaling pathway in DN model.

Sialic Acid Blockade Suppresses Tumor Growth by Enhancing T-cell-Mediated Tumor Immunity

Sialic acid sugars on the surface of cancer cells have emerged as potent immune modulators that contribute to the immunosuppressive microenvironment and tumor immune evasion. However, the mechanisms by which these sugars modulate antitumor immunity as well as therapeutic strategies directed against them are limited. Here we report that intratumoral injections with a sialic acid mimetic Ac₅3F_axNeu5Ac block tumor sialic acid expression in vivo and suppress tumor growth in multiple tumor models. Sialic acid blockade had a major impact on the immune cell composition of the tumor, enhancing tumor-infiltrating natural killer cell and CD8⁺ T-cell numbers while reducing regulatory T-cell and myeloid regulatory cell numbers. Sialic acid blockade enhanced cytotoxic CD8⁺ T-cell-mediated killing of tumor cells in part by facilitating antigen-specific T-cell-tumor cell clustering. Sialic acid blockade also synergized with adoptive transfer of tumor-specific CD8⁺ T cells in vivo and enhanced CpG immune adjuvant therapy by increasing dendritic cell activation and subsequent CD8⁺ T-cell responses. Collectively, these data emphasize the crucial role of sialic acids in tumor immune evasion and provide proof of concept that sialic acid blockade creates an immune-permissive tumor microenvironment for CD8⁺ T-cell-mediated tumor immunity, either as single treatment or in combination with other immune-based intervention strategies.Significance: Sialic acid sugars function as important modulators of the immunosuppressive tumor microenvironment that limit potent antitumor immunity.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/78/13/3574/F1.large.jpg Cancer Res; 78(13); 3574-88. ©2018 AACR.

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.

Loss of intra-islet heparan sulfate is a highly sensitive marker of type 1 diabetes progression in humans

Type 1 diabetes (T1D) is an autoimmune disease in which insulin-producing beta cells in pancreatic islets are progressively destroyed. Clinical trials of immunotherapies in recently diagnosed T1D patients have only transiently and partially impacted the disease course, suggesting that other approaches are required. Our previous studies have demonstrated that heparan sulfate (HS), a glycosaminoglycan conventionally expressed in extracellular matrix, is present at high levels inside normal mouse beta cells. Intracellular HS was shown to be critical for beta cell survival and protection from oxidative damage. T1D development in Non-Obese Diabetic (NOD) mice correlated with loss of islet HS and was prevented by inhibiting HS degradation by the endoglycosidase, heparanase. In this study we investigated the distribution of HS and heparan sulfate proteoglycan (HSPG) core proteins in normal human islets, a role for HS in human beta cell viability and the clinical relevance of intra-islet HS and HSPG levels, compared to insulin, in human T1D. In normal human islets, HS (identified by 10E4 mAb) co-localized with insulin but not glucagon and correlated with the HSPG core proteins for collagen type XVIII (Col18) and syndecan-1 (Sdc1). Insulin-positive islets of T1D pancreases showed significant loss of HS, Col18 and Sdc1 and heparanase was strongly expressed by islet-infiltrating leukocytes. Human beta cells cultured with HS mimetics showed significantly improved survival and protection against hydrogen peroxide-induced death, suggesting that loss of HS could contribute to beta cell death in T1D. We conclude that HS depletion in beta cells, possibly due to heparanase produced by insulitis leukocytes, may function as an important mechanism in the pathogenesis of human T1D. Our findings raise the possibility that intervention therapy with dual activity HS replacers/heparanase inhibitors could help to protect the residual beta cell mass in patients recently diagnosed with T1D.

Heparanase regulates the M1 polarization of renal macrophages and their crosstalk with renal epithelial tubular cells after ischemia/reperfusion injury

Heparanase (HPSE) is part of the biologic network triggered by ischemia/reperfusion (I/R) injury, a complication of renal transplantation and acute kidney injury. During this period, the kidney or graft undergoes a process of macrophages recruitment and activation. HPSE may therefore control these biologic effects. We measured the ability of HPSE and its inhibitor, SST0001, to regulate macrophage polarization and the crosstalk between macrophages and HK-2 renal tubular cells during in vitro hypoxia/reoxygenation (H/R). Furthermore, we evaluated in vivo renal inflammation, macrophage polarization, and histologic changes in mice subjected to monolateral I/R and treated with SST0001 for 2 or 7 d. The in vitro experiments showed that HPSE sustained M1 macrophage polarization and modulated apoptosis, the release of damage associated molecular patterns in post-H/R tubular cells, the synthesis of proinflammatory cytokines, and the up-regulation of TLRs on both epithelial cells and macrophages. HPSE also regulated M1 polarization induced by H/R-injured tubular cells and the partial epithelial-mesenchymal transition of these epithelial cells by M1 macrophages. All these effects were prevented by inhibiting HPSE. Furthermore, the inhibition of HPSE in vivo reduced inflammation and M1 polarization in mice undergoing I/R injury, partially restored renal function and normal histology, and reduced apoptosis. These results show for the first time that HPSE regulates macrophage polarization as well as renal damage and repair after I/R. HPSE inhibitors could therefore provide a new pharmacologic approach to minimize acute kidney injury and to prevent the chronic profibrotic damages induced by I/R.-Masola, V., Zaza, G., Bellin, G., Dall'Olmo, L., Granata, S., Vischini, G., Secchi, M. F., Lupo, A., Gambaro, G., Onisto, M. Heparanase regulates the M1 polarization of renal macrophages and their crosstalk with renal epithelial tubular cells after ischemia/reperfusion injury.

More than a biomarker: the systemic consequences of heparan sulfate fragments released during endothelial surface layer degradation (2017 Grover Conference Series)

Advances in tissue fixation and imaging techniques have yielded increasing appreciation for the glycosaminoglycan-rich endothelial glycocalyx and its in vivo manifestation, the endothelial surface layer (ESL). Pathological loss of the ESL during critical illness promotes local endothelial dysfunction and, consequently, organ injury. Glycosaminoglycan fragments, such as heparan sulfate, are released into the plasma of animals and humans after ESL degradation and have thus served as a biomarker of endothelial injury. The development of state-of-the-art glycomic techniques, however, has revealed that these circulating heparan sulfate fragments are capable of influencing growth factor and other signaling pathways distant to the site of ESL injury. This review summarizes the current state of knowledge concerning the local (i.e. endothelial injury) and systemic (i.e. para- or endocrine) consequences of ESL degradation and identifies opportunities for future, novel investigations.

Opposing Functions of Heparanase-1 and Heparanase-2 in Cancer Progression

Heparanase, the sole heparan sulfate (HS)-degrading endoglycosidase, regulates multiple biological activities that enhance tumor growth, metastasis, angiogenesis, and inflammation. Heparanase accomplishes this by degrading HS and thereby regulating the bioavailability of heparin-binding proteins; priming the tumor microenvironment; mediating tumor-host crosstalk; and inducing gene transcription, signaling pathways, exosome formation, and autophagy that together promote tumor cell performance and chemoresistance. By contrast, heparanase-2, a close homolog of heparanase, lacks enzymatic activity, inhibits heparanase activity, and regulates selected genes that promote normal differentiation, endoplasmic reticulum stress, tumor fibrosis, and apoptosis, together resulting in tumor suppression. The emerging premise is that heparanase is a master regulator of the aggressive phenotype of cancer, while heparanase-2 functions as a tumor suppressor.

Systemic Monocyte Chemotactic Protein-1 Inhibition Modifies Renal Macrophages and Restores Glomerular Endothelial Glycocalyx and Barrier Function in Diabetic Nephropathy

Inhibition of monocyte chemotactic protein-1 (MCP-1) with the Spiegelmer emapticap pegol (NOX-E36) shows long-lasting albuminuria-reducing effects in diabetic nephropathy. MCP-1 regulates inflammatory cell recruitment and differentiation of macrophages. Because the endothelial glycocalyx is also reduced in diabetic nephropathy, we hypothesized that MCP-1 inhibition restores glomerular barrier function through influencing macrophage cathepsin L secretion, thus reducing activation of the glycocalyx-degrading enzyme heparanase. Four weeks of treatment of diabetic Apoe knockout mice with the mouse-specific NOX-E36 attenuated albuminuria without any change in systemic hemodynamics, despite persistent loss of podocyte function. MCP-1 inhibition, however, increased glomerular endothelial glycocalyx coverage, with preservation of heparan sulfate. Mechanistically, both glomerular cathepsin L and heparanase expression were reduced. MCP-1 inhibition resulted in reduced CCR2-expressing Ly6C^hi monocytes in the peripheral blood, without affecting overall number of kidney macrophages at the tissue level. However, the CD206⁺/Mac3⁺ cell ratio, as an index of presence of anti-inflammatory macrophages, increased in diabetic mice after treatment. Functional analysis of isolated renal macrophages showed increased release of IL-10, whereas tumor necrosis factor and cathepsin L release was reduced, further confirming polarization of tissue macrophages toward an anti-inflammatory phenotype during mouse-specific NOX-E36 treatment. We show that MCP-1 inhibition restores glomerular endothelial glycocalyx and barrier function and reduces tissue inflammation in the presence of ongoing diabetic injury, suggesting a therapeutic potential for NOX-E36 in diabetic nephropathy.

Hyperoside pre-treatment prevents glomerular basement membrane damage in diabetic nephropathy by inhibiting podocyte heparanase expression

Glomerular basement membrane (GBM) damage plays a pivotal role in pathogenesis of albuminuria in diabetic nephropathy (DN). Heparan sulfate (HS) degradation induced by podocyte heparanase is the major cause of GBM thickening and abnormal perm-selectivity. In the present study, we aimed to examine the prophylactic effect of hyperoside on proteinuria development and GBM damage in DN mouse model and the cultured mouse podocytes. Pre-treatment with hyperoside (30 mg/kg/d) for four weeks could significantly decrease albuminuria, prevent GBM damage and oxidative stress in diabetes mellitus (DM) mice. Immunofluorescence staining, Real time PCR and Western blot analysis showed that decreased HS contents and increased heparanase expression in DN mice were also significantly improved by hyperoside pre-treatment. Meanwhile, transmission electron microscope imaging showed that hyperoside significantly alleviated GBM thickening in DN mice. In addition, hyperoside pre-treatment inhibited the increased heparanase gene (HPR1) promoter activity and heparanase expression induced by high glucose or reactive oxidative species (ROS) in cultured podocytes. Our data suggested that hyperoside has a prophylactic effect on proteinuria development and GBM damage in DM mice by decreasing podocyte heparanase expression.

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.

Heparanase: From basic research to therapeutic applications in cancer and inflammation

Heparanase, the sole heparan sulfate degrading endoglycosidase, regulates multiple biological activities that enhance tumor growth, angiogenesis and metastasis. Heparanase expression is enhanced in almost all cancers examined including various carcinomas, sarcomas and hematological malignancies. Numerous clinical association studies have consistently demonstrated that upregulation of heparanase expression correlates with increased tumor size, tumor angiogenesis, enhanced metastasis and poor prognosis. In contrast, knockdown of heparanase or treatments of tumor-bearing mice with heparanase-inhibiting compounds, markedly attenuate tumor progression further underscoring the potential of anti-heparanase therapy for multiple types of cancer. Heparanase neutralizing monoclonal antibodies block myeloma and lymphoma tumor growth and dissemination; this is attributable to a combined effect on the tumor cells and/or cells of the tumor microenvironment. In fact, much of the impact of heparanase on tumor progression is related to its function in mediating tumor-host crosstalk, priming the tumor microenvironment to better support tumor growth, metastasis and chemoresistance. The repertoire of the physio-pathological activities of heparanase is expanding. Specifically, heparanase regulates gene expression, activates cells of the innate immune system, promotes the formation of exosomes and autophagosomes, and stimulates signal transduction pathways via enzymatic and non-enzymatic activities. These effects dynamically impact multiple regulatory pathways that together drive inflammatory responses, tumor survival, growth, dissemination and drug resistance; but in the same time, may fulfill some normal functions associated, for example, with vesicular traffic, lysosomal-based secretion, stress response, and heparan sulfate turnover. Heparanase is upregulated in response to chemotherapy in cancer patients and the surviving cells acquire chemoresistance, attributed, at least in part, to autophagy. Consequently, heparanase inhibitors used in tandem with chemotherapeutic drugs overcome initial chemoresistance, providing a strong rationale for applying anti-heparanase therapy in combination with conventional anti-cancer drugs. Heparin-like compounds that inhibit heparanase activity are being evaluated in clinical trials for various types of cancer. Heparanase neutralizing monoclonal antibodies are being evaluated in pre-clinical studies, and heparanase-inhibiting small molecules are being developed based on the recently resolved crystal structure of the heparanase protein. Collectively, the emerging premise is that heparanase expressed by tumor cells, innate immune cells, activated endothelial cells as well as other cells of the tumor microenvironment is a master regulator of the aggressive phenotype of cancer, an important contributor to the poor outcome of cancer patients and a prime target for therapy.

Glomerular basement membrane heparan sulfate in health and disease: A regulator of local complement activation

The glomerular basement membrane (GBM) is an essential component of the glomerular filtration barrier. Heparan sulfate proteoglycans such as agrin are major components of the GBM, along with α345(IV) collagen, laminin-521 and nidogen. A loss of GBM heparan sulfate chains is associated with proteinuria in several glomerular diseases and may contribute to the underlying pathology. As the major determinants of the anionic charge of the GBM, heparan sulfate chains have been thought to impart charge selectivity to the glomerular filtration, a view challenged by the negligible albuminuria in mice that lack heparan sulfate in the GBM. Recent studies provide increasing evidence that heparan sulfate chains modulate local complement activation by recruiting complement regulatory protein factor H, the major inhibitor of the alternative pathway in plasma. Factor H selectively inactivates C3b bound to surfaces bearing host-specific polyanions such as heparan sulfate, thus limiting complement activation on self surfaces such as the GBM, which are not protected by cell-bound complement regulators. We discuss mechanisms whereby the acquired loss of GBM heparan sulfate can impair the local regulation of the alternative pathway, exacerbating complement activation and glomerular injury in immune-mediated kidney diseases such as membranous nephropathy and lupus nephritis.

Endothelial Nitric Oxide Synthase Prevents Heparanase Induction and the Development of Proteinuria

Endothelial nitric oxide synthase (eNOS) deficiency exacerbates proteinuria and renal injury in several glomerular diseases, but the underlying mechanism is not fully understood. We recently showed that heparanase is essential for the development of experimental diabetic nephropathy and glomerulonephritis, and hypothesize that heparanase expression is regulated by eNOS. Here, we demonstrate that induction of adriamycin nephropathy (AN) in C57BL/6 eNOS-deficient mice leads to an increased glomerular heparanase expression accompanied with overt proteinuria, which was not observed in the AN-resistant wild type counterpart. In vitro, the eNOS inhibitor asymmetric dimethylarginine (ADMA) induced heparanase expression in cultured mouse glomerular endothelial cells. Moreover, ADMA enhanced transendothelial albumin passage in a heparanase-dependent manner. We conclude that eNOS prevents heparanase induction and the development of proteinuria.