Heparan sulfate proteoglycans: structure, protein interactions and cell signaling

Docking heparan sulfate-based ligands as a promising inhibitor for SARS-CoV-2

CONTEXT

Heparan sulfate (HS) linear polysaccharide glycosaminoglycan compound is linked to components from the cell surface and the extracellular matrix. HS mediates SARS-CoV-2 infection through spike protein binding to cell surface receptors and is required to bind ACE2, prompting the need for electronic structure and molecular docking evaluation of this core system to exploit this attachment in developing new derivatives. Therefore, we have studied five molecules based on HS using molecular docking and electronic structure analysis. Non-covalent interaction analysis shows hydrogen bonding and van der Waals interactions in the binding to RBD-ACE2 interface and 3CLpro. SDM3 and SDM1 molecules present the lowest gap, including solvent effect under 154.6 kcal/mol, and exhibit the most reactivity behavior in this group, potentially leading to enhanced interaction in docking studies.

METHODS

Heparan sulfate and four derivatives were optimized using B3LYP functional with two basis sets 6-31 + G(d,p) and def2SVP. Electronic structure was used to explore the main interactions and the reactivity of these molecules, and these optimized structures were used in the molecular docking study against 3CLpro, RBD, and ACE2.

Glycocalyx Interactions Modulate the Cellular Uptake of Albumin-Coated Nanoparticles

Albumin-based nanoparticles (ABNPs) represent promising drug carriers in nanomedicine due to their versatility and biocompatibility, but optimizing their effectiveness in drug delivery requires understanding their interactions with and uptake by cells. Notably, albumin interacts with the cellular glycocalyx, a phenomenon particularly studied in endothelial cells. This observation suggests that the glycocalyx could modulate ABNP uptake and therapeutic efficacy, although this possibility remains unrecognized. In this study, we elucidate the critical role of the glycocalyx in the cellular uptake of a model ABNP system consisting of silica nanoparticles (NPs) coated with native, cationic, and anionic albumin variants (BSA, BSA+, and BSA-). Using various methodologies-including fluorescence anisotropy, dynamic light scattering, microscale thermophoresis, surface plasmon resonance spectroscopy, and computer simulations─we found that both BSA and BSA+, but not BSA-, interact with heparin, a model glycosaminoglycan (GAG). To explore the influence of albumin-GAG interactions on NP uptake, we performed comparative uptake studies in wild-type and GAG-mutated Chinese hamster ovary cells (CHO), along with complementary approaches such as enzymatic GAG cleavage in wild-type cells, chemical inhibition, and competition assays with exogenous heparin. We found that the glycocalyx enhances the cell uptake of NPs coated with BSA and BSA+, while serving as a barrier to the uptake of NPs coated with BSA-. Furthermore, we showed that harnessing albumin-GAG interactions increases cancer cell death induced by paclitaxel-loaded albumin-coated NPs. These findings underscore the importance of albumin-glycocalyx interactions in the rational design and optimization of albumin-based drug delivery systems.

High salt intake and HIV infection on endothelial glycocalyx shedding in salt-sensitive hypertension

The endothelial glycocalyx is closely associated with various physiological and pathophysiological events. Significant modification of the endothelial glycocalyx is an early process in the pathogenesis of cardiovascular disease. High dietary salt and HIV infection damages the endothelial glycocalyx causing endothelial dysfunction and increasing the risk for salt-sensitive hypertension and cardiovascular disease. The two factors, HIV infection and dietary salt are critical independent predictors of hypertension and cardiovascular disease and often synergize to exacerbate and accelerate disease pathogenesis. Salt-sensitive hypertension is more common among people living with HIV and is associated with risk for cardiovascular disease, stroke, heart attack and even death. However, the underlying mechanisms linking endothelial glycocalyx damage to dietary salt and HIV infection are lacking. Yet, both HIV infection/treatment and dietary salt are closely linked to endothelial glycocalyx damage and development of salt-sensitive hypertension. Moreover, the majority of individuals globally, consume more salt than is recommended and the burden of HIV especially in sub-Sahara Africa is disproportionately high. In this review, we have discussed the missing link between high salt and endothelial glycocalyx shedding in the pathogenesis of salt-sensitive hypertension. We have further elaborated the role played by HIV infection and treatment in modifying endothelial glycocalyx integrity to contribute to the development of hypertension and cardiovascular disease.

Excess Dally-like Induces Malformation of Drosophila Legs

Glypicans are closely associated with organ development and tumorigenesis in animals. Dally-like (Dlp), a membrane-bound glypican, plays pivotal roles in various biological processes in Drosophila. In this study, we observed that an excess of Dlp led to the malformation of legs, particularly affecting the distal part. Accordingly, the leg disc was shrunken and frequently exhibited aberrant morphology. In addition, elevated Dlp levels induced ectopic cell death with no apparent cell proliferation changes. Furthermore, Dlp overexpression in the posterior compartment significantly altered Wingless (Wg) distribution. We observed a marked expansion of Wg distribution within the posterior compartment, accompanied by a corresponding decrease in the anterior compartment. It appears that excess Dlp guides Wg to diffuse to cells with higher Dlp levels. In addition, the distal-less (dll) gene, which is crucial for leg patterning, was up-regulated significantly. Notably, dachshund (dac) and homothorax (hth) expression, also essential for leg patterning and development, only appeared to be negligibly affected. Based on these findings, we speculate that excess Dlp may contribute to malformations of the distal leg region of Drosophila, possibly through its influence on Wg distribution, dll expression and induced cell death. Our research advances the understanding of Dlp function in Drosophila leg development.

Internalization of PEI-based complexes in transient transfection of HEK293 cells is triggered by coalescence of membrane heparan sulfate proteoglycans like Glypican-4

Polymer-cationic mediated gene delivery is a well-stablished strategy of transient gene expression (TGE) in mammalian cell cultures. Nonetheless, its industrial implementation is hindered by the phenomenon known as cell density effect (CDE) that limits the cell density at which cultures can be efficiently transfected. The rise in personalized medicine and multiple cell and gene therapy approaches based on TGE, make more relevant to understand how to circumvent the CDE. A rational study upon DNA/PEI complex formation, stability and delivery during transfection of HEK293 cell cultures has been conducted, providing insights on the mechanisms for polyplexes uptake at low cell density and disruption at high cell density. DNA/PEI polyplexes were physiochemically characterized by coupling X-ray spectroscopy, confocal microscopy, cryo-transmission electron microscopy (TEM) and nuclear magnetic resonance (NMR). Our results showed that the ionic strength of polyplexes significantly increased upon their addition to exhausted media. This was reverted by depleting extracellular vesicles (EVs) from the media. The increase in ionic strength led to polyplex aggregation and prevented efficient cell transfection which could be counterbalanced by implementing a simple media replacement (MR) step before transfection. Inhibiting and labeling specific cell-surface proteoglycans (PGs) species revealed different roles of PGs in polyplexes uptake. Importantly, the polyplexes uptake process seemed to be triggered by a coalescence phenomenon of HSPG like glypican-4 around polyplex entry points. Ultimately, this study provides new insights into PEI-based cell transfection methodologies, enabling to enhance transient transfection and mitigate the cell density effect (CDE).

Alterations in the Structure, Composition, and Organization of Galactosaminoglycan-Containing Proteoglycans and Collagen Correspond to the Progressive Stages of Dupuytren's Disease

Dupuytren's disease (DD) is a prevalent fibroproliferative disorder of the hand, shaped by genetic, epigenetic, and environmental influences. The extracellular matrix (ECM) is a complex assembly of diverse macromolecules. Alterations in the ECM's content, structure and organization can impact both normal physiological functions and pathological conditions. This study explored the content and organization of glycosaminoglycans, proteoglycans, and collagen in the ECM of patients at various stages of DD, assessing their potential as prognostic indicators. This research reveals, for the first time, relevant changes in the complexity of chondroitin/dermatan sulfate structures, specifically an increase of disaccharides containing iduronic acid residues covalently linked to either N-acetylgalactosamine 6-O-sulfated or N-acetylgalactosamine 4-O-sulfated, correlating with the disease's severity. Additionally, we noted an increase in versican expression, a high molecular weight proteoglycan, across stages I to IV, while decorin, a small leucine-rich proteoglycan, significantly diminishes as DD progresses, both confirmed by mRNA analysis and protein detection via confocal microscopy. Coherent anti-Stokes Raman scattering (CARS) microscopy further demonstrated that collagen fibril architecture in DD varies importantly with disease stages. Moreover, the urinary excretion of both hyaluronic and sulfated glycosaminoglycans markedly decreased among DD patients.Our findings indicate that specific proteoglycans with galactosaminoglycan chains and collagen arrangements could serve as biomarkers for DD progression. The reduction in glycosaminoglycan excretion suggests a systemic manifestation of the disease.

N-glycomic profiling of capsid proteins from Adeno-Associated Virus serotypes

Adeno-associated virus (AAV) vector has become the leading platform for gene delivery. Each serotype exhibits a different tissue tropism, immunogenicity, and in vivo transduction performance. Therefore, selecting the most suitable AAV serotype is critical for efficient gene delivery to target cells or tissues. Genome divergence among different serotypes is due mainly to the hypervariable regions of the AAV capsid proteins. However, the heterogeneity of capsid glycosylation is largely unexplored. In the present study, the N-glycosylation profiles of capsid proteins of AAV serotypes 1 to 9 have been systemically characterized and compared using a previously developed high-throughput and high-sensitivity N-glycan profiling platform. The results showed that all 9 investigated AAV serotypes were glycosylated, with comparable profiles. The most conspicuous feature was the high abundance mannosylated N-glycans, including FM3, M5, M6, M7, M8, and M9, that dominated the chromatograms within a range of 74 to 83%. Another feature was the relatively lower abundance of fucosylated and sialylated N-glycan structures, in the range of 23%-40% and 10%-17%, respectively. However, the exact N-glycan composition differed. These differences may be utilized to identify potential structural relationships between the 9 AAV serotypes. The current research lays the foundation for gaining better understanding of the importance of N-glycans on the AAV capsid surface that may play a significant role in tissue tropism, interaction with cell surface receptors, cellular uptake, and intracellular processing.

Sweet but Challenging: Tackling the Complexity of GAGs with Engineered Tailor-Made Biomaterials

Glycosaminoglycans (GAGs) play a crucial role in tissue homeostasis by regulating the activity and diffusion of bioactive molecules. Incorporating GAGs into biomaterials has emerged as a widely adopted strategy in medical applications, owing to their biocompatibility and ability to control the release of bioactive molecules. Nevertheless, immobilized GAGs on biomaterials can elicit distinct cellular responses compared to their soluble forms, underscoring the need to understand the interactions between GAG and bioactive molecules within engineered functional biomaterials. By controlling critical parameters such as GAG type, density, and sulfation, it becomes possible to precisely delineate GAG functions within a biomaterial context and to better mimic specific tissue properties, enabling tailored design of GAG-based biomaterials for specific medical applications. However, this requires access to pure and well-characterized GAG compounds, which remains challenging. This review focuses on different strategies for producing well-defined GAGs and explores high-throughput approaches employed to investigate GAG-growth factor interactions and to quantify cellular responses on GAG-based biomaterials. These automated methods hold considerable promise for improving the understanding of the diverse functions of GAGs. In perspective, the scientific community is encouraged to adopt a rational approach in designing GAG-based biomaterials, taking into account the in vivo properties of the targeted tissue for medical applications.

Disruption of the endothelial glycocalyx layer is associated with idiopathic complete atrioventricular block in the elderly population: An observational pilot study

Idiopathic atrioventricular block (iCAVB) is the most common reason for the need for a permanent pacemaker in the elderly population. The fibrotic process that occurs in the conduction system of the heart with aging is the main pathogenesis in the development of iCAVB. However, the processes that trigger the development of iCAVB in the elderly population have not been fully elucidated. In this study, we aimed to reveal the possible relationship between the endothelial glycocalyx (EG) layer and idiopathic complete atrioventricular block. A group of 68 consecutive patients who developed iCAVB and a group of 68 healthy subjects matched for age, sex, and cardiovascular risk factors were included in the study. The groups were compared for clinical, laboratory, and levels of Syndecan-1 (SDC1), an EG layer marker. In the study, SDC1 levels were found to be significantly higher in the iCAVB group compared to the control group (23.7 ± 7.5 vs 16.7 ± 5.2; p = 0.009). In multivariable regression analysis, SDC1 was determined as an independent potential predictor for iCAVB (OR: 1.200; 95% CI: 1.119-1.287; p < 0.001). In the receiver operating characteristic curve analysis, SDC1 predicted iCAVB with 74% sensitivity and 72% specificity at the best cut-off value of 18.5 ng/mL (area under the curve: 0.777; confidence interval: 0.698-0.856; p < 0.001). Disruption of the endothelial glycolic layer may be one of the main triggering factors for the process leading to iCAVB.

Unique structural characteristics and biological activities of heparan sulfate isolated from the mantle of the scallop Chlamys farreri

Marine animals are a huge resource of various glycosaminoglycans (GAGs) with specific structures and functions. A large number of byproducts, such as low-edible mantle, are produced during the processing of Chlamys farreri, which is one of the most cultured scallops in China. In this study, a major GAG component was isolated from the mantle of C. farreri, and its structural characteristics and biological activities were determined in detail. Preliminary analysis by agarose electrophoresis combined with specific enzymatic degradation evaluations showed that this component was heparan sulfate and was named CMHS. Further analysis by HPLC and NMR revealed that CMHS has an average molecular weight of 35.9 kDa and contains a high proportion (80%) of 6-O-sulfated N-acetyl-D-glucosamine/N-sulfated-D-glucosamine (6-O-sulfated GlcNAc/GlcNS) residues and rare 3-O-sulfated β-D-glucuronic acid residues. Bioactivity analysis showed that CMHS has much lower anticoagulant activity than heparin and it can interact with various growth factors with high affinity. Moreover, CMHS binds strongly to the morphogen Wnt 3a to inhibit glypican-3-stimulated Wnt 3a signaling. Thus, the identification of CMHS with unique structural and bioactive features will provide a promising candidate for the development of GAG-type pharmaceutical products and promote the high-value utilization of C. farreri mantle.

SULF1 Activates the VEGFR2/PI3K/AKT Pathway to Promote the Development of Cervical Cancer

BACKGROUND AND PURPOSE

Sulfatase 1 (SULF1) can regulate the binding of numerous signaling molecules by removing 6-O-sulfate from heparan sulfate proteoglycans (HSPGs) to affect numerous physiological and pathological processes. Our research aimed to investigate the effect of the SULF1-mediated VEGFR2/PI3K/AKT signaling pathway on tumorigenesis and development of cervical cancer (CC).

METHODS

The expression and prognostic values of SULF1 in patients with CC were analyzed through bioinformatics analysis, qRT-PCR, immunohistochemistry, and western blot. The function and regulatory mechanism of SULF1 in proliferation, migration, and invasion of cervical cancer cells were examined through lentivirus transduction, CCK8, flow cytometry analysis, plate colony formation assay, scratch assay, transwell assay, western blot, VEGFR2 inhibitor (Ki8751), and mouse models.

RESULTS

SULF1 expression was significantly upregulated in CC tissues, which was significantly associated with poor prognosis of patients with CC. In vitro, the upregulation of SULF1 expression in HeLa cells promoted cell proliferation, colony formation, migration, and invasion while inhibiting apoptosis. Conversely, the downregulation of SULF1 expression had the opposite effect. In vivo, the upregulation of SULF1 expression resulted in a significant increase in both tumor growth and angiogenesis, while its downregulation had the opposite effect. Furthermore, western blot detection and cell function rescue assay confirmed that the upregulation of SULF1 in HeLa cells promoted the tumorigenic behaviors of cancer cells by activating the VEGFR2/PI3K/AKT signaling pathway.

CONCLUSION

SULF1 plays an oncogenic role in the tumorigenesis and development of CC, indicating its potential as a novel molecular target for gene-targeted therapy in patients with CC.

NMR Structural Study of Syndecan-4 Transmembrane Domain with Cytoplasmic Region

Syndecan-4 (SDC4) consists of transmembrane heparan sulfate proteoglycan (HSPG) belonging to the syndecan family. It is present in most cell types of Mammalia. Its structure contains a heparan-sulfate-modified extracellular domain, a single transmembrane domain, and a short C-terminal cytoplasmic domain. Regarding the overall cellular function of SDC4, other cells or ligands can bind to its ecto-domain. In addition, 4,5-bisphosphate phosphatidylinositol (PIP2) or protein kinase Cα can bind to its cyto-domain to activate downstream signaling pathways. To understand the signal transduction mechanism of syndecan, it is important to know the interactions between their actual structure and function in vivo. Therefore, it is important to identify the structure of SDC4 to understand the ligand binding behavior of SDC4. In this study, expression and purification were performed to reveal structures of the short ecto-domain, the transmembrane domain, and the cytoplasmic domain of Syd4-eTC (SDC4). Solution-state NMR spectroscopy and solid-state NMR spectroscopy were used to study the structure of Syd4-eTC in membrane environments and to demonstrate the interaction between Syd4-eTC and PIP2.

The Tumorigenicity of Breast Cancer Cells Is Reduced upon Treatment with Small Extracellular Vesicles Isolated from Heparin Treated Cell Cultures

As a member of the HPSG family, heparin is often used as a specific probe of their role in cell physiology; indeed, we have previously shown a reduction in the tumorigenicity of breast cancer cells when cultured in its presence. However, a partial reversal of the anti-tumorigenic effect occurred when the treated cells were cultured in fresh medium without heparin, which led us to consider whether a more persistent effect could be achieved by treatment of the cells with small extracellular vesicles (sEV) from heparin-treated cells. The tumorigenicity was analyzed using sEV isolated from the culture medium of heparin-treated MCF-7 and MDA-MB231 breast cancer cells (sEV-HT) or from conditioned medium following the termination of treatment (heparin discontinued, sEV-HD). Tumorigenicity was reduced in cells cultured in the presence of sEV-HT compared to that of cells cultured in the presence of sEV from untreated cells (sEV-Ctrl). sEV-HD were also observed to exert an anti-tumorigenic effect on the expression of pro-tumorigenic and cell cycle regulatory proteins, as well as signaling activities when added to fresh cultures of MCF-7 and MDA-MB231 cells. The anti-tumorigenic activity of the heparin-derived sEV may arise from observed changes in the miRNA content or from heparin, which was observed to be bound to the sEV. sEV may constitute a relatively stable reservoir of circulating heparin, allowing heparin activity to persist in the circulation even after therapy has been discontinued. These findings can be considered as a special additional pharmacological characteristic of heparin clinical therapy.

The Glycosaminoglycan Side Chains and Modular Core Proteins of Heparan Sulphate Proteoglycans and the Varied Ways They Provide Tissue Protection by Regulating Physiological Processes and Cellular Behaviour

This review examines the roles of HS-proteoglycans (HS-PGs) in general, and, in particular, perlecan and syndecan as representative examples and their interactive ligands, which regulate physiological processes and cellular behavior in health and disease. HS-PGs are essential for the functional properties of tissues both in development and in the extracellular matrix (ECM) remodeling that occurs in response to trauma or disease. HS-PGs interact with a biodiverse range of chemokines, chemokine receptors, protease inhibitors, and growth factors in immune regulation, inflammation, ECM stabilization, and tissue protection. Some cell regulatory proteoglycan receptors are dually modified hybrid HS/CS proteoglycans (betaglycan, CD47). Neurexins provide synaptic stabilization, plasticity, and specificity of interaction, promoting neurotransduction, neurogenesis, and differentiation. Ternary complexes of glypican-1 and Robbo-Slit neuroregulatory proteins direct axonogenesis and neural network formation. Specific neurexin-neuroligin complexes stabilize synaptic interactions and neural activity. Disruption in these interactions leads to neurological deficits in disorders of functional cognitive decline. Interactions with HS-PGs also promote or inhibit tumor development. Thus, HS-PGs have complex and diverse regulatory roles in the physiological processes that regulate cellular behavior and the functional properties of normal and pathological tissues. Specialized HS-PGs, such as the neurexins, pikachurin, and Eyes-shut, provide synaptic stabilization and specificity of neural transduction and also stabilize the axenome primary cilium of phototoreceptors and ribbon synapse interactions with bipolar neurons of retinal neural networks, which are essential in ocular vision. Pikachurin and Eyes-Shut interactions with an α-dystroglycan stabilize the photoreceptor synapse. Novel regulatory roles for HS-PGs controlling cell behavior and tissue function are expected to continue to be uncovered in this fascinating class of proteoglycan.

The prevalence of foot-and-mouth disease in Asia

Foot-and-mouth disease (FMD) is listed among the highly contagious diseases in animals and is endemic throughout the Asian continent. The disease is caused by the Foot-and-mouth disease virus (FMDV) and affects a wide variety of domesticated animals as well as wild ungulates. Clinically, the disease is described as a vesicular lesion on the tongue, muzzle, lips, gum, dental pad, interdigital cleft, coronary band, and heel of the foot. Sometimes these lesions give rise to lameness. Mastitis is also caused due to teat lesions. A biochemical test reveals that during FMD infection, there are elevated levels of interleukin-1 (IL-1), tumor necrosis factor-alpha, interferon-gamma (IFN-γ), interleukin-6, serum amyloid A protein, lactoferrin, mannose-binding lectin, and monocytes chemo-attractant protein-1 in the serum of infected animals. There is no specific treatment for FMD although some antivirals are given as prophylaxis and antibiotics are given to prevent secondary bacterial infection. This review presents comprehensive data on the prevalence of FMD and serotypes of FMDV that are attributable to the cause of FMD from a regional point of view. It also explains the worldwide dynamics of the seven serotypes of FMD and tries to identify epidemiological clusters of FMD in various geographical areas. Furthermore, the pathology associated with the foot and mouth disease virus along with the pathophysiology is discussed. The continent-wide prevalence and diversity patterns of FMD suggest that there is a need for stringent policies and legislation implementation regarding research and development aimed at manufacturing strain-specific vaccination, infection prevention, and control of the disease.

Spatiotemporal Localisation of Heparan Sulphate Proteoglycans throughout Mouse Lens Morphogenesis

Heparan sulphate proteoglycans (HSPGs) consist of a core protein decorated with sulphated HS-glycosaminoglycan (GAG) chains. These negatively charged HS-GAG chains rely on the activity of PAPSS synthesising enzymes for their sulfation, which allows them to bind to and regulate the activity of many positively charged HS-binding proteins. HSPGs are found on the surfaces of cells and in the pericellular matrix, where they interact with various components of the cell microenvironment, including growth factors. By binding to and regulating ocular morphogens and growth factors, HSPGs are positioned to orchestrate growth factor-mediated signalling events that are essential for lens epithelial cell proliferation, migration, and lens fibre differentiation. Previous studies have shown that HS sulfation is essential for lens development. Moreover, each of the full-time HSPGs, differentiated by thirteen different core proteins, are differentially localised in a cell-type specific manner with regional differences in the postnatal rat lens. Here, the same thirteen HSPG-associated GAGs and core proteins as well as PAPSS2, are shown to be differentially regulated throughout murine lens development in a spatiotemporal manner. These findings suggest that HS-GAG sulfation is essential for growth factor-induced cellular processes during embryogenesis, and the unique and divergent localisation of different lens HSPG core proteins indicates that different HSPGs likely play specialized roles during lens induction and morphogenesis.

Drug-Induced Gingival Overgrowth-Molecular Aspects of Drug Actions

Drug-induced gingival overgrowth (DIGO) is one of the side effects produced by therapeutic agents, most commonly phenytoin, nifedipine and cyclosporin A. However, the precise mechanism of DIGO is not entirely understood. A literature search of the MEDLINE/PubMed databases was conducted to identify the mechanisms involved in DIGO. The available information suggests that the pathogenesis of DIGO is multifactorial, but common pathogenic sequelae of events emerge, i.e., sodium and calcium channel antagonism or disturbed intracellular handling of calcium, which finally lead to reductions in intracellular folic acid levels. Disturbed cellular functions, mainly in keratinocytes and fibroblasts, result in increased collagen and glycosaminoglycans accumulation in the extracellular matrix. Dysregulation of collagenase activity, as well as integrins and membrane receptors, are key mechanisms of reduced degradation or excessive synthesis of connective tissue components. This manuscript describes the cellular and molecular factors involved in the epithelial-mesenchymal transition and extracellular matrix remodeling triggered by agents producing DIGO.

Heparan sulfate proteoglycans (HSPGs) of the ocular lens

Heparan sulfate proteoglycans (HSPGs) reside in most cells; on their surface, in the pericellular milieu and/or extracellular matrix. In the eye, HSPGs can orchestrate the activity of key signalling molecules found in the ocular environment that promote its development and homeostasis. To date, our understanding of the specific roles played by individual HSPG family members, and the heterogeneity of their associated sulfated HS chains, is in its infancy. The crystalline lens is a relatively simple and well characterised ocular tissue that provides an ideal stage to showcase and model the expression and unique roles of individual HSPGs. Individual HSPG core proteins are differentially localised to eye tissues in a temporal and spatial developmental- and cell-type specific manner, and their loss or functional disruption results in unique phenotypic outcomes for the lens, and other ocular tissues. More recent work has found that different HS sulfation enzymes are also presented in a cell- and tissue-specific manner, and that disruption of these different sulfation patterns affects specific HS-protein interactions. Not surprisingly, these sulfated HS chains have also been reported to be required for lens and eye development, with dysregulation of HS chain structure and function leading to pathogenesis and eye-related phenotypes. In the lens, HSPGs undergo significant and specific changes in expression and function that can drive pathology, or in some cases, promote tissue repair. As master signalling regulators, HSPGs may one day serve as valuable biomarkers, and even as putative targets for the development of novel therapeutics, not only for the eye but for many other systemic pathologies.

Longitudinal Assessment of Plasma Syndecan-1 Predicts 60-Day Mortality in Patients with COVID-19

Background: Endotheliopathy is a common pathologic finding in patients with acute and long COVID-19. It may be associated with disease severity and predispose patients to long-term complications. Plasma levels of a proteoglycan, syndecan-1, are found to be significantly elevated in patients with COVID-19, but its roles in assessing disease severity and predicting long-term outcome are not fully understood. Methods: A total of 124 consecutive hospitalized patients with SARS-CoV-2 infection were prospectively enrolled and blood samples were collected on admission (T1), 3−4 days following treatment (T2), and 1−2 days prior to discharge or death (T3). Plasma levels of syndecan-1 were determined using an immunosorbent assay; various statistical analyses were performed to determine the association between plasma syndecan-1 levels and disease severity or the 60-day mortality rate. Results: Compared with those in the healthy controls, plasma levels of syndecan-1 in patients with critical COVID-19 were significantly higher (p < 0.0001). However, there was no statistically significant difference among patients with different disease severity (p > 0.05), resulting from large individual variability. Longitudinal analysis demonstrated that while the levels fluctuated during hospitalization in all patients, plasma syndecan-1 levels were persistently elevated from baseline in critical COVID-19 patients. Cox proportional hazard regression analyses revealed that elevated plasma levels of syndecan-1 (>260 ng/mL at T1, >1018 ng/mL at T2, and >461 ng/mL at T3) were significantly associated with the 60-day mortality rate. Conclusions: Endotheliopathy, marked by glycocalyx degradation and elevated plasma syndecan-1, occurs in nearly all hospitalized patients with SARS-CoV-2 infection; elevated plasma syndecan-1 is associated with increased mortality in COVID-19 patients.

Broad-Spectrum Virus Trapping with Heparan Sulfate-Modified DNA Origami Shells

Effective broadband antiviral platforms that can act on existing viruses and viruses yet to emerge are not available, creating a need to explore treatment strategies beyond the trodden paths. Here, we report virus-encapsulating DNA origami shells that achieve broadband virus trapping properties by exploiting avidity and a widespread background affinity of viruses to heparan sulfate proteoglycans (HSPG). With a calibrated density of heparin and heparan sulfate (HS) derivatives crafted to the interior of DNA origami shells, we could encapsulate adeno, adeno-associated, chikungunya, dengue, human papilloma, noro, polio, rubella, and SARS-CoV-2 viruses or virus-like particles, in one and the same HS-functionalized shell system. Additional virus-type-specific binders were not needed for the trapping. Depending on the relative dimensions of shell to virus particles, multiple virus particles may be trapped per shell, and multiple shells can cover the surface of clusters of virus particles. The steric occlusion provided by the heparan sulfate-coated DNA origami shells can prevent viruses from further interactions with receptors, possibly including those found on cell surfaces.

Importance of Heparan Sulfate Proteoglycans in Pancreatic Islets and β-Cells

β-cells in the islets of Langerhans of the pancreas secrete insulin in response to the glucose concentration in the blood. When these pancreatic β-cells are damaged, diabetes develops through glucose intolerance caused by insufficient insulin secretion. High molecular weight polysaccharides, such as heparin and heparan sulfate (HS) proteoglycans, and HS-degrading enzymes, such as heparinase, participate in the protection, maintenance, and enhancement of the functions of pancreatic islets and β-cells, and the demand for studies on glycobiology within the field of diabetes research has increased. This review introduces the roles of complex glycoconjugates containing high molecular weight polysaccharides and their degrading enzymes in pancreatic islets and β-cells, including those obtained in studies conducted by us earlier. In addition, from the perspective of glycobiology, this study proposes the possibility of application to diabetes medicine.

New anti-angiogenic compound based on chemically modified heparin

PURPOSE

The purpose of this study was to measure the anti-angiogenic effect of N-desulfated Re-N-acetylated, a chemically modified heparin (mHep).

METHODS

In vitro assays (cell tube formation, viability, proliferation, and migration) with endothelial cells were performed after 24 h of treatment with mHep at 10, 100, and 1000 ng/mL or saline. In vivo tests were performed after laser-induced choroidal neovascularization (CNV) in rats, followed by an intravitreal injection (5 µL) of mHep (10, 100, 1000 ng/mL) or balanced salt solution. Immunofluorescence analysis of the CNV was performed after 14 days.

RESULTS

mHep produced a statistically significant reduction in cell proliferation, tube formation, and migration, without cell viability changes when compared to saline. Mean measures of CNV area were 54.84 × 10⁶ pixels/mm (± 12.41 × 10⁶), 58.77 × 10⁶ pixels/mm (± 17.52 × 10⁶), and 59.42 × 10⁶ pixels/mm (± 17.33 × 10⁶) in groups 100, 1000, and 10,000 ng/mL, respectively, while in the control group, mean area was 72.23 × 10⁶ (± 16.51 × 10⁶). The P value was 0.0065. Perimeter analysis also demonstrated statistical significance (P = 0.0235) with the mean measure of 93.55 × 10⁴, 94.23 × 10⁴, and 102 × 10⁴ in the 100 ng/mL, 1000 ng/mL, and control groups, respectively.

CONCLUSIONS

These results suggest that mHep N-DRN is a potent anti-angiogenic, anti-proliferative, and anti-migratory compound with negligible anticoagulant or hemorrhagic action and no cytotoxicity for retina cells. This compound may serve as a candidate for treating choroidal neovascularization.

Cell-surface glycosaminoglycans regulate the cellular uptake of charged polystyrene nanoparticles

Engineered nanoparticles approaching the cell body will first encounter and interact with cell-surface glycosaminoglycans (GAGs) before reaching the plasma membrane and becoming internalized. However, how surface GAGs may regulate the cellular entry of nanoparticles remains poorly understood. Herein, it is shown that the surface GAGs of Chinese hamster ovary cells perform as a charge-based barrier against the cellular internalization of anionic polystyrene nanoparticles (PS NPs). In contrast, cationic PS NPs interact favorably with the surface GAGs and thereby are efficiently internalized. Anionic PS NPs eventually reaching the plasma membrane bind to scavenger receptors and are endocytosed by clathrin-mediated and lipid raft/cholesterol-dependent mechanisms, whereas cationic PS NPs are primarily internalized via clathrin-mediated endocytosis and macropinocytosis. Upon the enzymatic shedding of surface GAGs, the uptake of anionic PS NPs increases while that of cationic PS NPs is dramatically reduced. Interestingly, the diminished uptake of cationic PS NPs is observed only when heparan sulfate, but not chondroitin sulfate, is cleaved from the cell surface. Heparan sulfate therefore serves as anchors/first receptors to facilitate the cellular entry of cationic PS NPs. These findings contribute to advance the basic science of nanoparticle endocytosis while also having important implications for the use of engineered nanocarriers as intracellular drug-delivery systems.

Heparin-Assisted Amyloidogenesis Uncovered through Molecular Dynamics Simulations

Glycosaminoglycans (GAGs), in particular, heparan sulfate and heparin, are found colocalized with Aβ amyloid. They have been shown to enhance fibril formation, suggesting a possible pathological connection. We have investigated heparin's assembly of the KLVFFA peptide fragment using molecular dynamics simulation, to gain a molecular-level mechanistic understanding of how GAGs enhance fibril formation. The simulations reveal an exquisite process wherein heparin accelerates peptide assembly by first "gathering" the peptide molecules and then assembling them. Heparin does not act as a mere template but is tightly coupled to the peptides, yielding a composite protofilament structure. The strong intermolecular interactions suggest composite formation to be a general feature of heparin's interaction with peptides. Heparin's chain flexibility is found to be essential to its fibril promotion activity, and the need for optimal heparin chain length and concentration has been rationalized. These insights yield design rules (flexibility; chain-length) and protocol guidance (heparin:peptide molar ratio) for developing effective heparin mimetics and other functional GAGs.

Biological role of heparan sulfate in osteogenesis: A review

Heparan sulfate (HS) is extensively expressed in cells, for example, cell membrane and extracellular matrix of most mammalian cells and tissues, playing a key role in the growth and development of life by maintaining homeostasis and implicating in the etiology and diseases. Recent studies have revealed that HS is involved in osteogenesis via coordinating multiple signaling pathways. The potential effect of HS on osteogenesis is a complicated and delicate biological process, which involves the participation of osteocytes, chondrocytes, osteoblasts, osteoclasts and a variety of cytokines. In this review, we summarized the structural and functional characteristics of HS and highlighted the molecular mechanism of HS in bone metabolism to provide novel research perspectives for the further medical research.

Synergistic impact of platelet rich plasma-heparin sulfate with hydroxyapatite/zirconia on the osteoblast differentiation potential of adipose-derived mesenchymal stem cells

3D porous hydroxyapatite (HA) has been reinforced by zirconia (ZrO₂) coating and impregnation with a combination of platelet rich plasma (PRP) as a source of growth factors (GFs) and Heparin sulfate (HS) to sustain the release of GFs. Adipose mesenchymal stem cells (ADMSCs) were characterized by flow cytometry for CD (cluster of differentiation) 44, CD105, CD106, CD34 and CD144, along with checking the multipotency by differentiation into the adipocytes and osteoblasts. Then, they were cultured on the scaffold treated with and without osteogenic media on days 7, 14 and 21. Electron micrograph and PKH staining show that the ADMSCs have a fusiform phenotype in the absence of osteogenic induction. Cell viability assay shows a higher number of the viable cells on the PRP-containing scaffolds than PRP-free scaffolds on day 7. Colorimetric evaluation, quantitative RT-PCR and immunocytochemistry demonstrate that PRP and HS significantly elevate the alkaline phosphatase enzyme activity and also accelerate the production of both early and mid-osteogenic markers, including collagen I and osteopontin expression with and without osteogenic conditions. The PRP-HS also accelerates the expression of the late osteogenic marker, osteocalcin, in both mRNA and protein level expression with a peak on day 21. In conclusion, supplementation of HA/ZrO₂ with PRP/HS has a synergistic impact on the ADMSCs, even in the absence of chemical induction. It seems that HA/ZrO₂/PRP/HS scaffold provides a higher osteoconductive microenvironment for stem cell differentiation to osteoblasts.

Proteoglycan profiling of human, rat and mouse insulin-secreting cells

Proteoglycans (PGs) are proteins with glycosaminoglycan (GAG) chains, such as chondroitin sulfate (CS) or heparan sulfate (HS), attached to serine residues. We have earlier shown that prohormones can carry CS, constituting a novel class of PGs. The mapping of GAG modifications of proteins in endocrine cells may thus assist us in delineating possible roles of PGs in endocrine cellular physiology. With this aim, we applied a glycoproteomic approach to identify PGs, their GAG chains and their attachment sites in insulin-secreting cells. Glycopeptides carrying GAG chains were enriched from human pancreatic islets, rat (INS-1 832/13) and mouse (MIN6, NIT-1) insulinoma cell lines by exchange chromatography, depolymerized with GAG lyases, and analyzed by nanoflow liquid chromatography tandem mass spectrometry. We identified CS modifications of chromogranin-A (CgA), islet amyloid polypeptide, secretogranin-1 and secretogranin-2, immunoglobulin superfamily member 10, and protein AMBP. Additionally, we identified two HS-modified prohormones (CgA and secretogranin-1), which was surprising, as prohormones are not typically regarded as HSPGs. For CgA, the glycosylation site carried either CS or HS, making it a so-called hybrid site. Additional HS sites were found on syndecan-1, syndecan-4, nerurexin-2, protein NDNF and testican-1. These results demonstrate that several prohormones, and other constituents of the insulin-secreting cells are PGs. Cell-targeted mapping of the GAG glycoproteome forms an important basis for better understanding of endocrine cellular physiology, and the novel CS and HS sites presented here provide important knowledge for future studies.

The Heparan Sulfate Binding Peptide in Tumor Progression of Triple-Negative Breast Cancer

Angiogenesis is the formation of new vessels from pre-existing vasculature. The heparan sulfate chains from endothelial cell proteoglycans interact with the major angiogenic factors, regulating blood vessels´ formation. Since the FDA´s first approval, anti-angiogenic therapy has shown tumor progression inhibition and increased patient survival. Previous work in our group has selected an HS-binding peptide using a phage display system. Therefore, we investigated the effect of the selected peptide in angiogenesis and tumor progression. The HS-binding peptide showed a higher affinity for heparin N-sulfated. The HS-binding peptide was able to inhibit the proliferation of human endothelial umbilical cord cells (HUVEC) by modulation of FGF-2. It was verified a significant decrease in the tube formation of human endothelial cells and capillary formation of mice aorta treated with HS-binding peptide. HS-binding peptide also inhibited the formation of sub-intestinal blood vessels in zebrafish embryos. Additionally, in zebrafish embryos, the tumor size decreased after treatment with HS-binding peptide.

Enzymatic Degradation of Glycosaminoglycans and Proteoglycan-Mimetic Materials in Solution and on Polyelectrolyte Multilayer Surfaces

Proteoglycans (PGs) play many important roles in biology, contributing to the mechanical properties of tissues, helping to organize extracellular matrix components, and participating in signaling mechanisms related to mechanotransduction, cell differentiation, immune responses, and wound healing. Our lab has designed two different types of PG mimics: polyelectrolyte complex nanoparticles (PCNs) and PG-mimetic graft copolymers (GCs), both of which are prepared using naturally occurring glycosaminoglycans. This work evaluates the enzymatic stability of these PG mimics using hyaluronidases (I-S, IV-S, and II), chondroitinase ABC, and lysozyme, for PG mimics suspended in solution and adsorbed onto surfaces. Hyaluronan (HA)- and chondroitin sulfate (CS)-containing PG mimics are degraded by the hyaluronidases. PCNs prepared with CS and GCs prepared with heparin are the only CS- and HA-containing PG mimics protected from chondroitinase ABC. None of the materials are measurably degraded by lysozyme. Adsorption to polyelectrolyte multilayer surfaces protects PG mimics from degradation, compared to when PG mimics are combined with enzymes in solution; all surfaces are still intact after 21 days of enzyme exposure. This work reveals how the stability of PG mimics is controlled by both the composition and macromolecular assembly of the PG mimic and also by the size and specificity of the enzyme. Understanding and tuning these degradation susceptibilities are essential for advancing their applications in cardiovascular materials, orthopedic materials, and growth factor delivery applications.

Sulfatase 1 and sulfatase 2 as novel regulators of macrophage antigen presentation and phagocytosis

Background

Sulfation of heparan sulfate proteoglycans (HSPGs) is critical for the binding and signaling of ligands that mediate inflammation. Extracellular 6-O-endosulfatases regulate posttranslational sulfation levels and patterns of HSPGs. In this study, extracellular 6-O-endosulfatases, sulfatase (Sulf)-1 and Sulf-2, were evaluated for their expression and function in inflammatory cells and tissues.

Methods

Harvested human peripheral blood mononuclear cells were treated with phytohemagglutinin and lipopolysaccharide, and murine peritoneal macrophages were stimulated with interleukin (IL)-1β for the evaluation of Sulf-1 and Sulf-2 expression. Sulf expression in inflammatory cells was examined in the human rheumatoid arthritis (RA) synovium by immunofluorescence staining. The antigen presentation and phagocytic activities of macrophages were compared according to the expression state of Sulfs. Sulfs-knockdown macrophages and Sulfs-overexpressing macrophages were generated using small interfering RNAs and pcDNA3.1 plasmids for Sulf-1 and Sulf-2, respectively.

Results

Lymphocytes and monocytes showed weak Sulf expression, which remained unaffected by IL-1β. However, peritoneal macrophages showed increased expression of Sulfs upon stimulation with IL-1β. In human RA synovium, two-colored double immunofluorescent staining of Sulfs and CD68 revealed active upregulation of Sulfs in macrophages of inflamed tissues, but not in lymphocytes of lymphoid follicles. Macrophages are professional antigen-presenting cells. The antigen presentation and phagocytic activities of macrophages were dependent on the level of Sulf expression, suppressed in Sulfs-knockdown macrophages, and enhanced in Sulfs-overexpressing macrophages.

Conclusion

The results demonstrate that upregulation of Sulfs in macrophages occurs in response to inflammation, and Sulfs actively regulate the antigen presentation and phagocytic activities of macrophages as novel immune regulators.

Heparan sulfate proteoglycans in beta cells provide a critical link between endoplasmic reticulum stress, oxidative stress and type 2 diabetes

Heparan sulfate proteoglycans (HSPGs) consist of a core protein with side chains of the glycosaminoglycan heparan sulfate (HS). We have previously identified (i) the HSPGs syndecan-1 (SDC1), and collagen type XVIII (COL18) inside mouse and human islet beta cells, and (ii) a critical role for HS in beta cell survival and protection from reactive oxygen species (ROS). The objective of this study was to investigate whether endoplasmic reticulum (ER) stress contributes to oxidative stress and type 2 diabetes (T2D) by depleting beta cell HSPGs/HS. A rapid loss of intra-islet/beta cell HSPGs, HS and heparanase (HPSE, an HS-degrading enzyme) accompanied upregulation of islet ER stress gene expression in both young T2D-prone db/db and Akita Ins2^WT/C96Y mice. In MIN6 beta cells, HSPGs, HS and HPSE were reduced following treatment with pharmacological inducers of ER stress (thapsigargin or tunicamycin). Treatment of young db/db mice with Tauroursodeoxycholic acid (TUDCA), a chemical protein folding chaperone that relieves ER stress, improved glycemic control and increased intra-islet HSPG/HS. In vitro, HS replacement with heparin (a highly sulfated HS analogue) significantly increased the survival of wild-type and db/db beta cells and restored their resistance to hydrogen peroxide-induced death. We conclude that ER stress inhibits the synthesis/maturation of HSPG core proteins which are essential for HS assembly, thereby exacerbating oxidative stress and promoting beta cell failure. Diminished intracellular HSPGs/HS represent a previously unrecognized critical link bridging ER stress, oxidative stress and beta cell failure in T2D.

Conformational changes of GDNF-derived peptide induced by heparin, heparan sulfate, and sulfated hyaluronic acid - Analysis by circular dichroism spectroscopy and molecular dynamics simulation

Glial-cell-line-derived neurotrophic factor (GDNF) is a protein that has therapeutic potential in the treatment of Parkinson's disease and other neurodegenerative diseases. The activity of GDNF is highly dependent on the interaction with sulfated glycans which bind at the N-terminus consisting of 19 residues. Herein, we studied the influence of different glycosaminoglycan (i.e., glycan; GAG) molecules on the conformation of a GDNF-derived peptide (GAG binding motif, sixteen amino acid residues at the N-terminus) using both experimental and theoretical studies. The GAG molecules employed in this study are heparin, heparan sulfate, hyaluronic acid, and sulfated hyaluronic acid. Circular dichroism spectroscopy was employed to detect conformational changes induced by the GAG molecules; molecular dynamics simulation studies were performed to support the experimental results. Our results revealed that the sulfated GAG molecules bind strongly with GDNF peptide and induce alpha-helical structure in the peptide to some extent.

Fluorometric coupled enzyme assay for N-sulfotransferase activity of N-deacetylase/N-sulfotransferase (NDST)

N-Deacetylase/N-sulfotransferases (NDST) are critical enzymes in heparan sulfate (HS) biosynthesis. Radioactive labeling assays are the preferred methods to determine the N-sulfotransferase activity of NDST. In this study, we developed a fluorometric coupled enzyme assay that is suitable for the study of enzyme kinetics and inhibitory properties of drug candidates derived from a large-scale in silico screening targeting the sulfotransferase moiety of NDST1. The assay measures recombinant mouse NDST1 (mNDST1) sulfotransferase activity by employing its natural substrate adenosine 3'-phophoadenosine-5'-phosphosulfate (PAPS), a bacterial analog of desulphated human HS, Escherichia coli K5 capsular polysaccharide (K5), the fluorogenic substrate 4-methylumbelliferylsulfate, and a double mutant of rat phenol sulfotransferase SULT1A1 K56ER68G. Enzyme kinetic analysis of mNDST1 performed with the coupled assay under steady state conditions at pH 6.8 and 37 °C revealed Km (K5) 34.8 μM, Km (PAPS) 10.7 μM, Vmax (K5) 0.53 ± 0.13 nmol/min/μg enzyme, Vmax (PAPS) 0.69 ± 0.05 nmol/min/μg enzyme, and the specific enzyme activity of 394 pmol/min/μg enzyme. The pH optimum of mNDST1 is pH 8.2. Our data indicate that mNDST1 is specific for K5 substrate. Finally, we showed that the mNDST1 coupled assay can be utilized to assess potential enzyme inhibitors for drug development.

Glycosaminoglycans Are Involved in the Adhesion of Candida albicans and Malassezia Species to Keratinocytes But Not to Dermal Fibroblasts

BACKGROUND AND OBJECTIVE

Superficial mycoses are some of the most common diseases worldwide. The usual culprits-yeasts belonging to the genera Malassezia and Candida-are commensal species in the skin that can cause opportunistic infections. We aimed to determine whether these yeasts use glycosaminoglycans (GAGs) as adhesion receptors to mediate binding to epithelial cells.

MATERIAL AND METHODS

In keratinocyte and dermal fibroblast cultures, we used rhodamine B and genistein to inhibit GAG synthesis to study the role these molecules play in the adhesion of Candida albicans and Malassezia species to cells. We also analyzed GAG involvement by means of enzyme digestion, using specific lyases.

RESULTS

Rhodamine B partially inhibited the adhesion of both fungi to keratinocytes but not to fibroblasts. Selective digestion of heparan sulfate enhanced the binding of Malassezia species to keratinocytes and of both fungi to fibroblasts. Chondroitin sulfate digestion decreased Calbicans adhesion to keratinocytes, but increased the adhesion of the filamentous forms of this species to fibroblasts.

CONCLUSIONS

Cell surface GAGs appear to play a role in the adhesion of Calbicans and Malasezzia species to keratinocytes. In contrast, their adhesion to fibroblasts appears to be enhanced by GAG inhibition, suggesting that some other type of receptor is the mediator.

Binding of the human antioxidation protein α1-microglobulin (A1M) to heparin and heparan sulfate. Mapping of binding site, molecular and functional characterization, and co-localization in vivo and in vitro

Heparin and heparan sulfate (HS) are linear sulfated disaccharide polymers. Heparin is found mainly in mast cells, while heparan sulfate is found in connective tissue, extracellular matrix and on cell membranes in most tissues. α1-microglobulin (A1M) is a ubiquitous protein with thiol-dependent antioxidant properties, protecting cells and matrix against oxidative damage due to its reductase activities and radical- and heme-binding properties. In this work, it was shown that A1M binds to heparin and HS and can be purified from human plasma by heparin affinity chromatography and size exclusion chromatography. The binding strength is inversely dependent of salt concentration and proportional to the degree of sulfation of heparin and HS. Potential heparin binding sites, located on the outside of the barrel-shaped A1M molecule, were determined using hydrogen deuterium exchange mass spectrometry (HDX-MS). Immunostaining of endothelial cells revealed pericellular co-localization of A1M and HS and the staining of A1M was almost completely abolished after treatment with heparinase. A1M and HS were also found to be co-localized in vivo in the lungs, aorta, kidneys and skin of mice. The redox-active thiol group of A1M was unaffected by the binding to HS, and the cell protection and heme-binding abilities of A1M were slightly affected. The discovery of the binding of A1M to heparin and HS provides new insights into the biological role of A1M and represents the basis for a novel method for purification of A1M from plasma.

Endothelial Glycocalyx as a Regulator of Fibrotic Processes

The endothelial glycocalyx, the gel layer covering the endothelium, is composed of glycosaminoglycans, proteoglycans, and adsorbed plasma proteins. This structure modulates vessels’ mechanotransduction, vascular permeability, and leukocyte adhesion. Thus, it regulates several physiological and pathological events. In the present review, we described the mechanisms that disturb glycocalyx stability such as reactive oxygen species, matrix metalloproteinases, and heparanase. We then focused our attention on the role of glycocalyx degradation in the induction of profibrotic events and on the possible pharmacological strategies to preserve this delicate structure.

In the Age of Viral Pandemic, Can Ingredients Inspired by Human Milk and Infant Nutrition Be Repurposed to Support the Immune System?

In 2020, with the advent of a pandemic touching all aspects of global life, there is a renewed interest in nutrition solutions to support the immune system. Infants are vulnerable to infection and breastfeeding has been demonstrated to provide protection. As such, human milk is a great model for sources of functional nutrition ingredients, which may play direct roles in protection against viral diseases. This review aims to summarize the literature around human milk (lactoferrin, milk fat globule membrane, osteopontin, glycerol monolaurate and human milk oligosaccharides) and infant nutrition (polyunsaturated fatty acids, probiotics and postbiotics) inspired ingredients for support against viral infections and the immune system more broadly. We believe that the application of these ingredients can span across all life stages and thus apply to both pediatric and adult nutrition. We highlight the opportunities for further research in this field to help provide tangible nutrition solutions to support one's immune system and fight against infections.

Virus-Host Interactions in Foot-and-Mouth Disease Virus Infection

Foot-and-mouth disease (FMD) is a highly contagious disease of cloven-hoofed animals, which has been regarded as a persistent challenge for the livestock industry in many countries. Foot-and-mouth disease virus (FMDV) is the etiological agent of FMD that can spread rapidly by direct and indirect transmission. FMDV is internalized into host cell by the interaction between FMDV capsid proteins and cellular receptors. When the virus invades into the cells, the host antiviral system is quickly activated to suppress the replication of the virus and remove the virus. To retain fitness and host adaptation, various viruses have evolved multiple elegant strategies to manipulate host machine and circumvent the host antiviral responses. Therefore, identification of virus-host interactions is critical for understanding the host defense against virus infections and the pathogenesis of the viral infectious diseases. This review elaborates on the virus-host interactions during FMDV infection to summarize the pathogenic mechanisms of FMD, and we hope it can provide insights for designing effective vaccines or drugs to prevent and control the spread of FMD and other diseases caused by picornaviruses.

Biopolymer-based Scaffolds for Tissue Engineering Applications

Tissue engineering is governed by the use of cells and polymers. The cells may be accounted for the type of tissue to be targeted, while polymers may vary from natural to synthetic. The natural polymers have advantages such as non-immunogenic and complex structures that help in the formation of bonds in comparison to the synthetic ones. Various targeted drug delivery systems have been prepared using polymers and cells, such as nanoparticles, hydrogels, nanofibers, and microspheres. The design of scaffolds depends on the negative impact of material used on the human body and they have been prepared using surface modification technique or neo material synthesis. The dermal substitutes are a distinctive array that aims at the replacement of skin parts either through grafting or some other means. This review focuses on biomaterials for their use in tissue engineering. This article shall provide the bird's eye view of the scaffolds and dermal substitutes, which are naturally derived.

Glycosaminoglycans Are Involved in the Adhesion of Candida albicans and Malassezia Species to Keratinocytes But Not to Dermal Fibroblasts

BACKGROUND AND OBJECTIVE

Superficial mycoses are some of the most common diseases worldwide. The usual culprits - yeasts belonging to the genera Malassezia and Candida - are commensal species in the skin that can cause opportunistic infections. We aimed to determine whether these yeasts use glycosaminoglycans (GAGs) as adhesion receptors to mediate binding to epithelial cells.

MATERIAL AND METHODS

In keratinocyte and dermal fibroblast cultures, we used rhodamine B and genistein to inhibit GAG synthesis to study the role these molecules play in the adhesion of Candida albicans (C. albicans) and Malassezia species to cells. We also analyzed GAG involvement by means of enzyme digestion, using specific lyases.

RESULTS

Rhodamine B partially inhibited the adhesion of both fungi to keratinocytes but not to fibroblasts. Selective digestion of heparan sulfate enhanced the binding of Malassezia species to keratinocytes and of both fungi to fibroblasts. Chondroitin sulfate digestion decreased C. albicans adhesion to keratinocytes, but increased the adhesion of the filamentous forms of this species to fibroblasts.

CONCLUSIONS

Cell surface GAGs appear to play a role in the adhesion of C albicans and Malasezzia species to keratinocytes. In contrast, their adhesion to fibroblasts appears to be enhanced by GAG inhibition, suggesting that some other type of receptor is the mediator.

Effect of Natural and Artificial Dentin Conditioners on the Release of Vascular Endothelial Growth Factor

INTRODUCTION

The purpose of this study was to observe the release of vascular endothelial growth factor (VEGF) after conditioning with etidronic acid (also known as 1-hydroxyethylidene-1 and 1-bisphosphonate [HEDP]) and phytic acid (inositol hexakisphosphate [IP6]) in comparison with EDTA on human dentin disks and cylinders.

METHODS

Human dentin disks were disinfected and prepared by the standardized method. Seventeen percent EDTA, 9% HEDP, 1% IP6, and distilled water (5 minutes) were used to immerse dentin disks. The dentin cylinders were prepared by following disinfection and the standardized preparation method to achieve a truncated cone-shaped canal with a 1-mm open apex. The dentin cylinder samples were irrigated with sodium hypochlorite (5 mL/5 minutes) and then rinsed with 17% EDTA, 9% HEDP, 1% IP6 and distilled water (5 mL/5 min). Enzyme-linked immunosorbent essay was performed to measure VEGF release. One-way analysis of variance was used to compare the mean release of VEGF between study groups and controls at a significance level of .05. A post hoc Tukey test was used for multiple comparisons between study groups.

RESULTS

Among conditioners, HEDP released more VEGF from both disks and cylinders. In cylinders, VEGF release by HEDP was significantly greater than the other conditioners, whereas in disks the release of VEGF was similar with all conditioners.

CONCLUSIONS

The release of VEGF by 9% HEDP and 1% IP6 was comparable with 17% EDTA from dentin disks; however, HEDP demonstrated more release from dentin cylinders than EDTA and IP6.

Inflammatory Response Mechanisms of the Dentine-Pulp Complex and the Periapical Tissues

The macroscopic and microscopic anatomy of the oral cavity is complex and unique in the human body. Soft-tissue structures are in close interaction with mineralized bone, but also dentine, cementum and enamel of our teeth. These are exposed to intense mechanical and chemical stress as well as to dense microbiologic colonization. Teeth are susceptible to damage, most commonly to caries, where microorganisms from the oral cavity degrade the mineralized tissues of enamel and dentine and invade the soft connective tissue at the core, the dental pulp. However, the pulp is well-equipped to sense and fend off bacteria and their products and mounts various and intricate defense mechanisms. The front rank is formed by a layer of odontoblasts, which line the pulp chamber towards the dentine. These highly specialized cells not only form mineralized tissue but exert important functions as barrier cells. They recognize pathogens early in the process, secrete antibacterial compounds and neutralize bacterial toxins, initiate the immune response and alert other key players of the host defense. As bacteria get closer to the pulp, additional cell types of the pulp, including fibroblasts, stem and immune cells, but also vascular and neuronal networks, contribute with a variety of distinct defense mechanisms, and inflammatory response mechanisms are critical for tissue homeostasis. Still, without therapeutic intervention, a deep carious lesion may lead to tissue necrosis, which allows bacteria to populate the root canal system and invade the periradicular bone via the apical foramen at the root tip. The periodontal tissues and alveolar bone react to the insult with an inflammatory response, most commonly by the formation of an apical granuloma. Healing can occur after pathogen removal, which is achieved by disinfection and obturation of the pulp space by root canal treatment. This review highlights the various mechanisms of pathogen recognition and defense of dental pulp cells and periradicular tissues, explains the different cell types involved in the immune response and discusses the mechanisms of healing and repair, pointing out the close links between inflammation and regeneration as well as between inflammation and potential malignant transformation.

Myeloperoxidase mediated alteration of endothelial function is dependent on its cationic charge

Endothelial cell (EC) glycocalyx (GLX) comprise a multicomponent layer of proteoglycans and glycoproteins. Alteration of its integrity contributes to chronic vascular inflammation and leads to the development of cardiovascular diseases. Myeloperoxidase (MPO), a highly abundant enzyme released by polymorphonuclear neutrophils, binds to the GLX and deleteriously affects vascular EC functions. The focus of this study was to elucidate the mechanisms of MPO-mediated alteration of GLX molecules, and to unravel subsequent changes in endothelial integrity and function. MPO binding to GLX of human ECs and subsequent internalization was mediated by cell surface heparan sulfate chains. Moreover, interaction of MPO, which is carrying a cationic charge, with anionic glycosaminoglycans (GAGs) resulted in reduction of their relative charge. By means of micro-viscometry and atomic force microscopy, we disclosed that MPO can crosslink GAG chains. MPO-dependent modulation of GLX structure was further supported by alteration of wheat germ agglutinin staining. Increased expression of ICAM-1 documented endothelial cell activation by both catalytically active and also inactive MPO. Furthermore, MPO increased vascular permeability connected with reorganization of intracellular junctions, however, this was dependent on MPO's catalytic activity. Novel proteins interacting with MPO during transcytosis were identified by proteomic analysis. Altogether, these findings provide evidence that MPO through interaction with GAGs modulates overall charge of the GLX, causing modification of its structure and thus affecting EC function. Importantly, our results also suggest a number of proteins interacting with MPO that possess a variety of cellular localizations and functions.

Human Health Implication of Major and Trace Elements Present in Commercial Crustaceans of a Traditional Seafood Marketing Region, Egypt

The present study focused on the distribution of some major and trace elements (S (as SO₄^2-), Na, K, B, Ca, Mg, F, Li, Al, Fe, Zn, Cu, Mn, Ni, Co, Cd, and Pb) in both flesh (Fl) and total cephalon/exoskeleton (C/E) tissues of selected crustacean species obtained from an Egyptian traditional seafood marketing region. The sequence of studied elements in (Fl) and (C/E) tissues in descending orders was S (as SO₄^2-) > Na > K > B > Mg > Ca > Li > F > Al > Zn > Fe > Cu > Pb > Ni > Mn > Co > Cd, and S (as SO₄^2-) > Na > B > K > Mg > Ca > F > Li > Al > Fe > Cu > Zn > Mn > Pb > Ni > Co > Cd, respectively. Both length-weight relationship and Fulton's condition factor showed the physical and biological statuses of the crustaceans. Ion quotient calculations of the studied tissues pointed to their importance in decreasing hypertension, preeclampsia, and heart disease. Human health risk due to the consumption of the crustacean species was determined using some guideline limits, metal pollution index (MPI), estimated daily intake (EDI), health comparison values (CVs), dietary intake (DRI-ULs), target hazard quotient (THQ), total target hazard quotient (TTHQ), and provisional tolerable weekly intake (%PTWI). MPI values of cephalon/exoskeleton tissues were greater than those of the flesh with ranges between 11.4-24.0 and 4.6-14.3, respectively. Interestingly, the calculations of TTHQ of toddler and adult were lesser than one and not expected to pose any risk concern to human from crustaceans' consumption.

Type IV collagen conforms to the organization of polylaminin adsorbed on planar substrata

Tissue engineering demands the development of scaffolds that mimic natural extracellular matrices (ECM). Despite the success in obtaining synthetic interstitial ECM, the production of an artificial basement membrane (BM), the specialized thin sheet of ECM that is pivotal for the functional organization of most tissues and internal organs, is still not achieved. With the long-term aim of developing a flat BM-like structure here we investigated the behavior of acid-soluble Col IV during simultaneous assembly with laminin (LM) in acidic conditions. The underlying rationale was the previously observed phenomenon of acid-triggered LM polymerization, giving rise to biomimetic polylaminin (polyLM) that can be adsorbed on the substrate. Unexpectedly, we found that Col IV (that does not polymerize in acidic conditions) readily incorporated into the polyLM layer, forming a network that mimics to a great extent the characteristic polygonal morphology of single polyLM observable at micrometric scale. Scanning calorimetry and light scattering measurements supported the notion that polyLM and Col IV could directly interact. The biological properties of the proposed artificial BM-like structure were characterized using human keratinocytes (HACAT) and umbilical vein endothelial cells (HUVEC). HACAT formed stratified cell layers on the hybrid polyLM/Col IV layer, but not on Matrigel, nor on LM or Col IV alone, while HUVEC improved cortical F-actin and tight juctions organization on polyLM/Col IV. Thus, the proposed artificial BM reproduces not only morphological but also some functional properties of the natural BM. STATEMENT OF SIGNIFICANCE: Basement membranes (BMs) are flat biological matrices separating tissue compartments in the body. Their peculiar sheet-like structure is thought to result from the association of two independent protein networks of laminin and collagen IV. While pursuing the development of an artificial BM, we found that, when mixed with acid-induced polymerized laminin, collagen IV immediately conformed to the laminin shape. This implies that the protein networks may not be independently assembled as believed so far, but instead that laminin may command the assembly of collagen IV. Our hybrid matrix was structurally more stable than the commercial BM extract Matrigel and, unlike the latter, supported in vitro formation of a stratified layer of keratinocytes that approximated the organization of the natural epidermis.

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.

The Good and Bad Sides of Heparanase-1 and Heparanase-2

In this chapter, we will emphasize the importance of heparan sulfate proteoglycans (HSPG) in controlling various physiological and pathological molecular mechanisms and discuss how the heparanase enzyme can modulate the effects triggered by HSPG. Additionally, we will also navigate about the existing knowledge of the possible role of heparanase-2 in biological events. Heparan sulfate is widely distributed and evolutionarily conserved, evidencing its vital importance in cell development and functions such as cell proliferation, migration, adhesion, differentiation, and angiogenesis. During remodeling of the extracellular matrix, the breakdown of heparan sulfate by heparanase results in the release of molecules containing anchored glycosaminoglycan chains of great interest in heparanase-mediated cell signaling pathways in various physiological states, tumor development, inflammation, and other diseases. Taken together, it appears that heparanase plays a key role in the maintenance of the pathology of cancer and inflammatory diseases and is a potential target for anti-cancer therapies. Therefore, heparanase inhibitors are currently being examined in clinical trials as novel cancer therapeutics. Heparanase-2 has no enzymatic activity, displays higher affinity for heparan sulfate and the coding region alignment shows 40% identity with the heparanase gene. Heparanase-2 plays an important role in embryogenic development however its mode of action and biological function remain to be elucidated. Heparanase-2 functions as an inhibitor of the heparanase-1 enzyme and also inhibits neovascularization mediated by VEGF. The HPSE2 gene is repressed by the Polycomb complex, together suggesting a role as a tumor suppressor.