Dissociation between mature phenotype and impaired transmigration in dendritic cells from heparanase-deficient mice

Heparanase promotes the onset and progression of atherosclerosis in apolipoprotein E gene knockout mice

BACKGROUND AND AIMS

Atherosclerosis is the primary underlying cause of myocardial infarction and stroke, which are the major causes of death globally. Heparanase (Hpse) is a pro-inflammatory extracellular matrix degrading enzyme that has been implicated in atherogenesis. However, to date the precise roles of Hpse in atherosclerosis and its mechanisms of action are not well defined. This study aims to provide new insights into the contribution of Hpse in different stages of atherosclerosis in vivo.

METHODS

We generated Hpse gene-deficient mice on the atherosclerosis-prone apolipoprotein E gene knockout (ApoE-/-) background to investigate the impact of Hpse gene deficiency on the initiation and progression of atherosclerosis after 6 and 14 weeks high-fat diet feeding, respectively. Atherosclerotic lesion development, blood serum profiles, lesion composition and aortic immune cell populations were evaluated.

RESULTS

Hpse-deficient mice exhibited significantly reduced atherosclerotic lesion burden in the aortic sinus and aorta at both time-points, independent of changes in plasma cholesterol levels. A significant reduction in the necrotic core size and an increase in smooth muscle cell content were also observed in advanced atherosclerotic plaques of Hpse-deficient mice. Additionally, Hpse deficiency reduced circulating and aortic levels of VCAM-1 at the initiation and progression stages of disease and circulating MCP-1 levels in the initiation but not progression stage. Moreover, the aortic levels of total leukocytes and dendritic cells in Hpse-deficient ApoE-/- mice were significantly decreased compared to control ApoE-/-mice at both disease stages.

CONCLUSIONS

This study identifies Hpse as a key pro-inflammatory enzyme driving the initiation and progression of atherosclerosis and highlighting the potential of Hpse inhibitors as novel anti-inflammatory treatments for cardiovascular disease.

Heparanase and the hallmarks of cancer

Heparanase is the only mammalian enzyme that cleaves heparan sulphate, an important component of the extracellular matrix. This leads to the remodelling of the extracellular matrix, whilst liberating growth factors and cytokines bound to heparan sulphate. This in turn promotes both physiological and pathological processes such as angiogenesis, immune cell migration, inflammation, wound healing and metastasis. Furthermore, heparanase exhibits non-enzymatic actions in cell signalling and in regulating gene expression. Cancer is underpinned by key characteristic features that promote malignant growth and disease progression, collectively termed the 'hallmarks of cancer'. Essentially, all cancers examined to date have been reported to overexpress heparanase, leading to enhanced tumour growth and metastasis with concomitant poor patient survival. With its multiple roles within the tumour microenvironment, heparanase has been demonstrated to regulate each of these hallmark features, in turn highlighting the need for heparanase-targeted therapies. However, recent discoveries which demonstrated that heparanase can also regulate vital anti-tumour mechanisms have cast doubt on this approach. This review will explore the myriad ways by which heparanase functions as a key regulator of the hallmarks of cancer and will highlight its role as a major component within the tumour microenvironment. The dual role of heparanase within the tumour microenvironment, however, emphasises the need for further investigation into defining its precise mechanism of action in different cancer settings.

Heparanase in Acute Pancreatitis

Acute pancreatitis (AP) is one of the most common diseases in gastroenterology, affecting 2% of all hospitalized patients. Nevertheless, neither the etiology nor the pathophysiology of the disease is fully characterized, and no specific or effective treatment has been developed. Heparanase (Hpa) is an endoglycosidase that cleaves heparan sulfate (HS) side chains of heparan sulfate proteoglycans (HSPGs) into shorter oligosaccharides, activity that is highly implicated in cell invasion associated with cancer metastasis and inflammation. Given that AP is a typical inflammatory disease, we investigated whether Hpa plays a role in AP. Our results provide keen evidence that Hpa expression and activity are significantly increased following cerulein-induced AP in wild type mice. In parallel to the classic manifestations of AP, namely elevation of amylase and lipase levels, pancreas edema and inflammation as well as induction of cytokines and signaling molecules, have been detected in this experimental model of the disease. Noteworthy, these features were far more profound in transgenic mice overexpressing heparanase (Hpa-Tg), suggesting that these mice can be utilized as a model system to reveal the molecular mechanism by which Hpa functions in AP. Further support for the involvement of Hpa in the pathogenesis of AP emerged from our observation that treatment of experimental AP with PG545 or SST0001(= Ronepastat), two potent Hpa inhibitors, markedly attenuated the biochemical, histological and immunological manifestations of the disease. Hpa, therefore, emerges as a potential new target in AP, and Hpa inhibitors are hoped to prove beneficial in AP along with their promising efficacy as anti-cancer compounds.

Heparanase is Involved in Leukocyte Migration

Leukocyte migration is essential for exerting self-defense mechanisms. During the extravasation process, leukocytes transmigrate through the endothelial lining and the subendothelial basement membrane. Accumulating evidence supports the involvement of heparanase in this process. Altered cellular distribution resulting in relocalization of heparanase to the leading edge of migration is a key event to rapidly turn on the function of the enzyme during migration. This review presents current research investigating the cellular machinery that builds up a functional subcellular structure for leukocyte attachment to and degradation of the extracellular matrix. Recent advances in the understanding of the roles of heparanase in inflammatory diseases and pharmacological approaches to control heparanase-mediated actions during inflammation are also discussed.

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.

Microbial metabolites and derivatives targeted at inflammation and bone diseases therapy: chemistry, biological activity and pharmacology

Microbial metabolites have attracted increasing interest as a source of therapeutics and as probes for biological mechanisms. New microbial metabolites and derivatives targeted at inflammation and bone disease therapy have been identified by focusing on prostaglandin release, osteoblast differentiation and immune cell functions. These modulators of inflammatory processes and bone disease contribute to our understanding of biological mechanisms and support identification of the therapeutic potential of drug lead candidates. The present review describes recent advances in the chemistry and analysis of inhibitors of prostaglandin release or other functional molecules of immune cells, as well as inducers of osteoblast differentiation, including biological and pharmacological activities.The Journal of Antibiotics advance online publication, 1 November 2017; doi:10.1038/ja.2017.138.

NK cell heparanase controls tumor invasion and immune surveillance

NK cells are highly efficient at preventing cancer metastasis but are infrequently found in the core of primary tumors. Here, have we demonstrated that freshly isolated mouse and human NK cells express low levels of the endo-β-D-glucuronidase heparanase that increase upon NK cell activation. Heparanase deficiency did not affect development, differentiation, or tissue localization of NK cells under steady-state conditions. However, mice lacking heparanase specifically in NK cells (Hpsefl/fl NKp46-iCre mice) were highly tumor prone when challenged with the carcinogen methylcholanthrene (MCA). Hpsefl/fl NKp46-iCre mice were also more susceptible to tumor growth than were their littermate controls when challenged with the established mouse lymphoma cell line RMA-S-RAE-1β, which overexpresses the NK cell group 2D (NKG2D) ligand RAE-1β, or when inoculated with metastatic melanoma, prostate carcinoma, or mammary carcinoma cell lines. NK cell invasion of primary tumors and recruitment to the site of metastasis were strictly dependent on the presence of heparanase. Cytokine and immune checkpoint blockade immunotherapy for metastases was compromised when NK cells lacked heparanase. Our data suggest that heparanase plays a critical role in NK cell invasion into tumors and thereby tumor progression and metastases. This should be considered when systemically treating cancer patients with heparanase inhibitors, since the potential adverse effect on NK cell infiltration might limit the antitumor activity of the inhibitors.

Glycan Sulfation Modulates Dendritic Cell Biology and Tumor Growth

In cancer, proteoglycans have been found to play roles in facilitating the actions of growth factors, and effecting matrix invasion and remodeling. However, little is known regarding the genetic and functional importance of glycan chains displayed by proteoglycans on dendritic cells (DCs) in cancer immunity. In lung carcinoma, among other solid tumors, tumor-associated DCs play largely subversive/suppressive roles, promoting tumor growth and progression. Herein, we show that targeting of DC glycan sulfation through mutation in the heparan sulfate biosynthetic enzyme N-deacetylase/N-sulfotransferase-1 (Ndst1) in mice increased DC maturation and inhibited trafficking of DCs to draining lymph nodes. Lymphatic-driven DC migration and chemokine (CCL21)-dependent activation of a major signaling pathway required for DC migration (as measured by phospho-Akt) were sensitive to Ndst1 mutation in DCs. Lewis lung carcinoma tumors in mice deficient in Ndst1 were reduced in size. Purified CD11c + cells from the tumors, which contain the tumor-infiltrating DC population, showed a similar phenotype in mutant cells. These features were replicated in mice deficient in syndecan-4, the major heparan sulfate proteoglycan expressed on the DC surface: Tumors were growth-impaired in syndecan-4–deficient mice and were characterized by increased infiltration by mature DCs. Tumors on the mutant background also showed greater infiltration by NK cells and NKT cells. These findings indicate the genetic importance of DC heparan sulfate proteoglycans in tumor growth and may guide therapeutic development of novel strategies to target syndecan-4 and heparan sulfate in cancer.

The Role of Heparanase in the Pathogenesis of Acute Pancreatitis: A Potential Therapeutic Target

Acute pancreatitis (AP) is one of the most common diseases in gastroenterology. However, neither the etiology nor the pathophysiology of the disease is fully understood and no specific or effective treatment has been developed. Heparanase is an endoglycosidase that cleaves heparan sulfate (HS) side chains of HS sulfate proteoglycans into shorter oligosaccharides, activity that is highly implicated in cellular invasion associated with cancer metastasis and inflammation. Given that AP involves a strong inflammatory aspect, we examined whether heparanase plays a role in AP. Here, we provide evidence that pancreatic heparanase expression and activity are significantly increased following cerulein treatment. Moreover, pancreas edema and inflammation, as well as the induction of cytokines and signaling molecules following cerulein treatment were attenuated markedly by heparanase inhibitors, implying that heparanase plays a significant role in AP. Notably, all the above features appear even more pronounced in transgenic mice over expressing heparanase, suggesting that these mice can be utilized as a sensitive model system to reveal the molecular mechanism by which heparanase functions in AP. Heparanase, therefore, emerges as a potential new target in AP, and heparanase inhibitors, now in phase I/II clinical trials in cancer patients, are hoped to prove beneficial also in AP.

Heparanase regulation of cancer, autophagy and inflammation: new mechanisms and targets for therapy

Because of its impact on multiple biological pathways, heparanase has emerged as a major regulator of cancer, inflammation and other disease processes. Heparanase accomplishes this by degrading heparan sulfate which regulates the abundance and location of heparin-binding growth factors thereby influencing multiple signaling pathways that control gene expression, syndecan shedding and cell behavior. In addition, heparanase can act via nonenzymatic mechanisms that directly activate signaling at the cell surface. Clinical trials testing heparanase inhibitors as anticancer therapeutics are showing early signs of efficacy in patients further emphasizing the biological importance of this enzyme. This review focuses on recent developments in the field of heparanase regulation of cancer and inflammation, including the impact of heparanase on exosomes and autophagy, and novel mechanisms whereby heparanase regulates tumor metastasis, angiogenesis and chemoresistance. In addition, the ongoing development of heparanase inhibitors and their potential for treating cancer and inflammation are discussed.

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.

An iminosugar-based heparanase inhibitor heparastatin (SF4) suppresses infiltration of neutrophils and monocytes into inflamed dorsal air pouches

Local infiltration of inflammatory cells is regulated by a number of biological steps during which the cells likely penetrate through subendothelial basement membranes that contain heparan sulfate proteoglycans. In the present study, we examined whether administration of heparastatin (SF4), an iminosugar-based inhibitor of heparanase, could suppress local inflammation and degradation of heparan sulfate proteoglycans in basement membranes. In a carrageenan- or formyl peptide-induced dorsal air pouch inflammation model, the number of infiltrated neutrophils and monocytes was significantly lower in mice after topical administration of heparastatin (SF4). The concentration of chemokines MIP-2 and KC in pouch exudates of drug-treated mice was similar to control. In a zymosan-induced peritonitis model, the number of infiltrated cells was not altered in drug-treated mice. To further test how heparastatin (SF4) influences transmigration of inflammatory neutrophils, its suppressive effect on migration and matrix degradation was examined in vitro. In the presence of heparastatin (SF4), the number of neutrophils that infiltrated across a Matrigel-coated polycarbonate membrane was significantly lower, while the number of neutrophils passing through an uncoated membrane was not altered. Lysate of bone marrow-derived neutrophils released sulfate-radiolabeled macromolecules from basement membrane-like extracellular matrix, which was suppressed by heparastatin (SF4). Heparan sulfate degradation activity was almost completely abolished after incubation of lysate with protein G-conjugated anti-heparanase monoclonal antibody, strongly suggesting that the activity was due to heparanase-mediated degradation. Taken together, in a dorsal air pouch inflammation model heparastatin (SF4) potentially suppresses extravasation of inflammatory cells by impairing the degradation of basement membrane heparan sulfate.

Dendritic cells and the extracellular matrix: A challenge for maintaining tolerance/homeostasis

The importance of the extracellular matrix (ECM) in contributing to structural, mechanical, functional and tissue-specific features in the body is well appreciated. While the ECM was previously considered to be a passive bystander, it is now evident that it plays active, dynamic and flexible roles in shaping cell survival, differentiation, migration and death to varying extents depending on the specific site in the body. Dendritic cells (DCs) are recognized as potent antigen presenting cells present in many tissues and in blood, continuously scrutinizing the microenvironment for antigens and mounting local and systemic host responses against harmful agents. DCs also play pivotal roles in maintaining homeostasis to harmless self-antigens, critical for preventing autoimmunity. What is less understood are the complex interactions between DCs and the ECM in maintaining this balance between steady-state tissue residence and DC activation during inflammation. DCs are finely tuned to inflammation-induced variations in fragment length, accessible epitopes and post-translational modifications of individual ECM components and correspondingly interpret these changes appropriately by adjusting their profiles of cognate binding receptors and downstream immune activation. The successful design and composition of novel ECM-based mimetics in regenerative medicine and other applications rely on our improved understanding of DC-ECM interplay in homeostasis and the challenges involved in maintaining it.

Heparanase of murine effector lymphocytes and neutrophils is not required for their diapedesis into sites of inflammation

Heparanase, the exclusive mammalian heparan sulfate-degrading enzyme, has been suggested to be utilized by leukocytes to penetrate through the dense basement membranes surrounding blood venules. Despite its established role in tumor cell invasion, heparanase function in leukocyte extravasation has never been demonstrated. We found that TH1/TC1-type effector T cells are highly enriched for this enzyme, with a 3.6-fold higher heparanase mRNA expression compared with naive lymphocytes. Using adoptive transfer of wild-type and heparanase-deficient effector T cells into inflamed mice, we show that T-cell heparanase was not required for extravasation inside inflamed lymph nodes or skin. Leukocyte extravasation through acute inflamed skin vessels was also heparanase independent. Furthermore, neutrophils emigrated to the inflamed peritoneal cavity independently of heparanase expression on either the leukocytes or on the endothelial and mesothelial barriers, and overexpression of the enzyme on neutrophils did not facilitate their emigration. However, heparanase absence significantly reduced monocyte emigration into the inflamed peritoneal cavity. These results collectively suggest that neither leukocyte nor endothelial heparanase is required for T-cell and neutrophil extravasation through inflamed vascular barriers, whereas this enzyme is required for optimal monocyte recruitment to inflamed peritoneum.

Mice deficient in heparanase exhibit impaired dendritic cell migration and reduced airway inflammation

Heparanase is a β-d-endoglucuronidase that cleaves heparan sulphate, a key component of the ECM and basement membrane. The remodelling of the ECM by heparanase has been proposed to regulate both normal physiological and pathological processes, including wound healing, inflammation, tumour angiogenesis and cell migration. Heparanase is also known to exhibit non-enzymatic functions by regulating cell adhesion, cell signalling and differentiation. In this study, constitutive heparanase-deficient (Hpse(-/-) ) mice were generated on a C57BL/6 background using the Cre/loxP recombination system, with a complete lack of heparanase mRNA, protein and activity. Although heparanase has been implicated in embryogenesis and development, Hpse(-/-) mice are anatomically normal and fertile. Interestingly, consistent with the suggested function of heparanase in cell migration, the trafficking of dendritic cells from the skin to the draining lymph nodes was markedly reduced in Hpse(-/-) mice. Furthermore, the ability of Hpse(-/-) mice to generate an allergic inflammatory response in the airways, a process that requires dendritic cell migration, was also impaired. These findings establish an important role for heparanase in immunity and identify the enzyme as a potential target for regulation of an immune response.

Heparan sulfate: a ubiquitous glycosaminoglycan with multiple roles in immunity

Heparan sulfate (HS) is a highly acidic linear polysaccharide with a very variable structure. It is ubiquitously expressed on cell surfaces and in the extracellular matrix and basement membrane of mammalian tissues. Synthesized attached to various core proteins to form HS-proteoglycans, HS is capable of interacting with various polypeptides and exerting diverse functions. In fact, a bioinformatics analysis of mammalian proteins that express a heparin/HS-binding motif and are associated with the immune system identified 235 candidate proteins, the majority having an intracellular location. This simple analysis suggests that HS may, in fact, interact with many more components of the immune system than previously realized. Numerous studies have also directly demonstrated that HS plays multiple prominent functional roles in the immune system that are briefly reviewed in this article. In particular, the molecule has been shown to regulate leukocyte development, leukocyte migration, immune activation, and inflammatory processes.

Versatile role of heparanase in inflammation

Heparanase is the only known mammalian endoglycosidase capable of degrading heparan sulfate glycosaminoglycan, both in extracellular space and within the cells. It is tightly implicated in cancer progression and over the past few decades significant progress has been made in elucidating the multiple functions of heparanase in malignant tumor development, neovascularization and aggressive behavior. Notably, current data show that in addition to its well characterized role in cancer, heparanase activity may represent an important determinant in the pathogenesis of several inflammatory disorders, such as inflammatory lung injury, rheumatoid arthritis and chronic colitis. Nevertheless, the precise mode of heparanase action in inflammatory reactions remains largely unclear and recent observations suggest that heparanase can either facilitate or limit inflammatory responses, when tissue/cell-specific contextual cues may dictate an outcome of heparanase action in inflammation. In this review the involvement of heparanase in modulation of inflammatory reactions is discussed through a few illustrative examples, including neuroinflammation, sepsis-associated lung injury and inflammatory bowel disease. We also discuss possible action of the enzyme in coupling inflammation and tumorigenesis in the setting of inflammation-triggered cancer.

Membrane-associated matrix proteolysis and heart failure

The extracellular matrix (ECM) is a complex entity containing a large portfolio of structural proteins, signaling molecules, and proteases. Changes in the overall integrity and activational state of these ECM constituents can contribute to tissue structure and function, which is certainly true of the myocardium. Changes in the expression patterns and activational states of a family of ECM proteolytic enzymes, the matrix metalloproteinases (MMPs), have been identified in all forms of left ventricle remodeling and can be a contributory factor in the progression to heart failure. However, new clinical and basic research has identified some surprising and unpredicted changes in MMP profiles in left ventricle remodeling processes, such as with pressure or volume overload, as well as with myocardial infarction. From these studies, it has become recognized that proteolytic processing of signaling molecules by certain MMP types, particularly the transmembrane MMPs, actually may facilitate ECM accumulation and modulate fibroblast transdifferentiation; both are critical events in adverse left ventricle remodeling. Based on the ever-increasing substrates and diversity of biological actions of MMPs, it is likely that continued research about the relationship of left ventricle remodeling in this family of proteases will yield new insights into the ECM remodeling process and new therapeutic targets.

Rehmannia glutinosa polysaccharide induces maturation of murine bone marrow derived Dendritic cells (BMDCs)

Purified Rehmannia glutinosa polysaccharide (RGP) is used as functional foods for the prevention and treatment of various diseases. In this study, we examined the effects of RGP on phenotypic and functional maturation of murine bone marrow derived Dendritic cells (BMDCs). Phenotypic maturation of BMDCs was confirmed by conventional scanning electron microscopy (SEM), flow cytometry (FCM) and functional maturation by transmission electron microscopy (TEM), cytochemistry assay, Acid phosphatase (ACP) activity, FITC-dextran, bio-assay and enzyme linked immunosorbent assay (ELISA).We found that RGP up-regulated the expression of CD40, CD80, CD83, CD86 and MHC II molecules of BMDCs, down-regulated pinocytosis and phagocytosis activity, induced IL-12 and TNF-α production of BMDCs. It is therefore concluded that RGP can effectively promote the maturation of DCs. Our study provides evidence and rationale on using RGP in various clinical conditions to enhance host immunity and suggests RGP as a potent adjuvant for the design of DC-based vaccines.