Syndecans in wound healing, inflammation and vascular biology

Endocytic Pathways Unveil the Role of Syndecans in the Seeding and Spreading of Pathological Protein Aggregates: Insights into Neurodegenerative Disorders

Alzheimer's disease and other neurodegenerative disorders are characterized by the accumulation of misfolded proteins, such as amyloid-beta, tau, and α-synuclein, which disrupt neuronal function and contribute to cognitive decline. Heparan sulfate proteoglycans, particularly syndecans, play a pivotal role in the seeding, aggregation, and spreading of toxic protein aggregates through endocytic pathways. Among these, syndecan-3 is particularly critical in regulating the internalization of misfolded proteins, facilitating their propagation in a prion-like manner. This review examines the mechanisms by which syndecans, especially SDC3, contribute to the seeding and spreading of pathological protein aggregates in neurodegenerative diseases. Understanding these endocytic pathways provides valuable insights into the potential of syndecans as biomarkers and therapeutic targets for early intervention in Alzheimer's disease and other related neurodegenerative disorders.

Syndecan-3 positively regulates the pro-inflammatory function of macrophages

The tumour microenvironment (TME) is a highly structured ecosystem that surrounds a tumour and plays a crucial role in tumorigenesis. As one of the most abundant cell types in the TME, tumour-associated-macrophages (TAMs) can promote disease progression and resistance to therapy. Syndecan-3 (SDC3) is a cell-surface heparan sulphate proteoglycan expressed by TAMs, although its functional relevance in these cells remains unknown. Here, we demonstrated that pro-inflammatory cytokines drive the expression of SDC3 on the cell surface of macrophages. Genetic ablation of SDC3 in macrophages led to aberrant proliferation, adhesion and expression of CD40 and CD86 surface markers. Moreover, SDC3 defective macrophages exhibited distinctive gene expression patterns, leading to impaired tumour cell phagocytosis and increased tumour cell proliferation. Mechanistically, a decrease in the secretion of pro-inflammatory cytokines was observed in SDC3 KO macrophages, concomitant with impaired T cell effector functions. Additionally, a higher angiogenic capacity was observed in endothelial cells when co-cultured with macrophages deficient for SDC3, possibly mediated through an increased release of VEGFA, PECAM-1 and IL-8 by SDC3 KO cells. Collectively, we have identified SDC3 as a modulator of macrophage functions aiming at supporting a pro-inflammatory and anti-tumour phenotype in these cells.

Glycosaminoglycans, Instructive Biomolecules That Regulate Cellular Activity and Synaptic Neuronal Control of Specific Tissue Functional Properties

Glycosaminoglycans (GAGs) are a diverse family of ancient biomolecules that evolved over millennia as key components in the glycocalyx that surrounds all cells. GAGs have molecular recognition and cell instructive properties when attached to cell surface and extracellular matrix (ECM) proteoglycans (PGs), which act as effector molecules that regulate cellular behavior. The perception of mechanical cues which arise from perturbations in the ECM microenvironment allow the cell to undertake appropriate biosynthetic responses to maintain ECM composition and tissue function. ECM PGs substituted with GAGs provide structural support to weight-bearing tissues and an ability to withstand shear forces in some tissue contexts. This review outlines the structural complexity of GAGs and the diverse functional properties they convey to cellular and ECM PGs. PGs have important roles in cartilaginous weight-bearing tissues and fibrocartilages subject to tension and high shear forces and also have important roles in vascular and neural tissues. Specific PGs have roles in synaptic stabilization and convey specificity and plasticity in the regulation of neurophysiological responses in the CNS/PNS that control tissue function. A better understanding of GAG instructional roles over cellular behavior may be insightful for the development of GAG-based biotherapeutics designed to treat tissue dysfunction in disease processes and in novel tissue repair strategies following trauma. GAGs have a significant level of sophistication over the control of cellular behavior in many tissue contexts, which needs to be fully deciphered in order to achieve a useful therapeutic product. GAG biotherapeutics offers exciting opportunities in the modern glycomics arena.

Role of endothelial glycocalyx in central nervous system diseases and evaluation of the targeted therapeutic strategies for its protection: a review of clinical and experimental data

Central nervous system (CNS) diseases, such as stroke, traumatic brain injury, dementia, and demyelinating diseases, are generally characterized by high morbidity and mortality, which impose a heavy economic burden on patients and their caregivers throughout their lives as well as on public health. The occurrence and development of CNS diseases are closely associated with a series of pathophysiological changes including inflammation, blood-brain barrier disruption, and abnormal coagulation. Endothelial glycocalyx (EG) plays a key role in these changes, making it a novel intervention target for CNS diseases. Herein, we review the current understanding of the role of EG in common CNS diseases, from the perspective of individual pathways/cytokines in pathophysiological and systematic processes. Furthermore, we emphasize the recent developments in therapeutic agents targeted toward protection or restoration of EG. Some of these treatments have yielded unexpected pharmacological results, as previously unknown mechanisms underlying the degradation and destruction of EG has been brought to light. Furthermore, the anti-inflammatory, anticoagulative, and antioxidation effects of EG and its protective role exerted via the blood-brain barrier have been recognized.

Rivaroxaban as a Protector of Oxidative Stress-Induced Vascular Endothelial Glycocalyx Damage via the IQGAP1/PAR1-2/PI3K/Akt Pathway

INTRODUCTION

The vascular endothelial glycocalyx, crucial for blood vessel integrity and homeostasis, is vulnerable to oxidative stress, leading to endothelial dysfunction, which strongly correlates with cardiovascular disease (CVD). This study investigates the protective effects of rivaroxaban, a factor X inhibitor, on the glycocalyx under oxidative stress condition.

METHODS

We examined the impact of rivaroxaban on human umbilical vein endothelial cells exposed to acute and chronic H2O2-induced oxidative stress.

RESULTS

Rivaroxaban dose-dependently suppressed syndecan-1, a key component of the glycocalyx, shedding from cell surface, and enhanced protease-activated receptor (PAR)1-PAR2/phosphatidylinositol-3-kinase (PI3K)-dependent cell viability after acute induction of H2O2. This protective effect was linked to the translocation of IQGAP1, a scaffold protein that modulates the actin cytoskeleton, to the perinucleus from the cell membrane. Under chronic H2O2 treatments, rivaroxaban improves cell viability accompanied by an increase in hyaluronidase activities, aiding the turnover and remodeling of hyaluronic acid within the glycocalyx.

CONCLUSION

We identify that rivaroxaban protects against oxidative stress-induced endothelial glycocalyx damage and cell viability through IQGAP1/PAR1-2/PI3K/Akt pathway, offering a potential to be a therapeutic target for CVD prevention.

INTRODUCTION

The vascular endothelial glycocalyx, crucial for blood vessel integrity and homeostasis, is vulnerable to oxidative stress, leading to endothelial dysfunction, which strongly correlates with cardiovascular disease (CVD). This study investigates the protective effects of rivaroxaban, a factor X inhibitor, on the glycocalyx under oxidative stress condition.

METHODS

We examined the impact of rivaroxaban on human umbilical vein endothelial cells exposed to acute and chronic H2O2-induced oxidative stress.

RESULTS

Rivaroxaban dose-dependently suppressed syndecan-1, a key component of the glycocalyx, shedding from cell surface, and enhanced protease-activated receptor (PAR)1-PAR2/phosphatidylinositol-3-kinase (PI3K)-dependent cell viability after acute induction of H2O2. This protective effect was linked to the translocation of IQGAP1, a scaffold protein that modulates the actin cytoskeleton, to the perinucleus from the cell membrane. Under chronic H2O2 treatments, rivaroxaban improves cell viability accompanied by an increase in hyaluronidase activities, aiding the turnover and remodeling of hyaluronic acid within the glycocalyx.

CONCLUSION

We identify that rivaroxaban protects against oxidative stress-induced endothelial glycocalyx damage and cell viability through IQGAP1/PAR1-2/PI3K/Akt pathway, offering a potential to be a therapeutic target for CVD prevention.

Extracellular Matrix Components and Mechanosensing Pathways in Health and Disease

Glycosaminoglycans (GAGs) and proteoglycans (PGs) are essential components of the extracellular matrix (ECM) with pivotal roles in cellular mechanosensing pathways. GAGs, such as heparan sulfate (HS) and chondroitin sulfate (CS), interact with various cell surface receptors, including integrins and receptor tyrosine kinases, to modulate cellular responses to mechanical stimuli. PGs, comprising a core protein with covalently attached GAG chains, serve as dynamic regulators of tissue mechanics and cell behavior, thereby playing a crucial role in maintaining tissue homeostasis. Dysregulation of GAG/PG-mediated mechanosensing pathways is implicated in numerous pathological conditions, including cancer and inflammation. Understanding the intricate mechanisms by which GAGs and PGs modulate cellular responses to mechanical forces holds promise for developing novel therapeutic strategies targeting mechanotransduction pathways in disease. This comprehensive overview underscores the importance of GAGs and PGs as key mediators of mechanosensing in maintaining tissue homeostasis and their potential as therapeutic targets for mitigating mechano-driven pathologies, focusing on cancer and inflammation.

Exploring Syndecan-4 and MLP and Their Interaction in Primary Cardiomyocytes and H9c2 Cells

The transmembrane proteoglycan syndecan-4 is known to be involved in the hypertrophic response to pressure overload. Although multiple downstream signaling pathways have been found to be involved in this response in a syndecan-4-dependent manner, there are likely more signaling components involved. As part of a larger syndecan-4 interactome screening, we have previously identified MLP as a binding partner to the cytoplasmic tail of syndecan-4. Interestingly, many human MLP mutations have been found in patients with hypertrophic (HCM) and dilated cardiomyopathy (DCM). To gain deeper insight into the role of the syndecan-4-MLP interaction and its potential involvement in MLP-associated cardiomyopathy, we have here investigated the syndecan-4-MLP interaction in primary adult rat cardiomyocytes and the H9c2 cell line. The binding of syndecan-4 and MLP was analyzed in total lysates and subcellular fractions of primary adult rat cardiomyocytes, and baseline and differentiated H9c2 cells by immunoprecipitation. MLP and syndecan-4 localization were determined by confocal microscopy, and MLP oligomerization was determined by immunoblotting under native conditions. Syndecan-4-MLP binding, as well as MLP self-association, were also analyzed by ELISA and peptide arrays. Our results showed that MLP-WT and syndecan-4 co-localized in many subcellular compartments; however, their binding was only detected in nuclear-enriched fractions of isolated adult cardiomyocytes. In vitro, syndecan-4 bound to MLP at three sites, and this binding was reduced in some HCM-associated MLP mutations. While MLP and syndecan-4 also co-localized in many subcellular fractions of H9c2 cells, these proteins did not bind at baseline or after differentiation into cardiomyocyte-resembling cells. Independently of syndecan-4, mutated MLP proteins had an altered subcellular localization in H9c2 cells, compared to MLP-WT. The DCM- and HCM-associated MLP mutations, W4R, L44P, C58G, R64C, Y66C, K69R, G72R, and Q91L, affected the oligomerization of MLP with an increase in monomeric at the expense of trimeric and tetrameric recombinant MLP protein. Lastly, two crucial sites for MLP self-association were identified, which were reduced in most MLP mutations. Our data indicate that the syndecan-4-MLP interaction was present in nuclear-enriched fractions of isolated adult cardiomyocytes and that this interaction was disrupted by some HCM-associated MLP mutations. MLP mutations were also linked to changes in MLP oligomerization and self-association, which may be essential for its interaction with syndecan-4 and a critical molecular mechanism of MLP-associated cardiomyopathy.

The significance of Syndecan 1, a new marker for endothelial dysfunction, in cases of fetal growth retardation

PROBLEM

In the current study we aimed to investigate Syndecan 1 (SDC1) levels in pregnant women diagnosed with fetal growth restriction (FGR) and the relationship between SDC1 levels and clinical and doppler parameters in FGR cases associated with endothelial dysfunction, angiogenesis and uteroplacental insufficiency METHOD OF STUDY: A total of 90 pregnant women included in the study, (45 with FGR, 45 healthy control) matched by week of gestation and maternal age. Venous blood samples were collected and plasma concentrations of SDC1 were determined by a specific immunoassay. Doppler examination was performed to evaluate the relationship between the SDC1 levels and placental blood supply.

RESULTS

Doppler parameters; mean UtA-PI (p < .001), CPR (p = .002) and CPUR (p < .001) were different between the groups, however MCA PI, umbilical artery PI and umbilical artery S/D were not (p > .05). While gestational age at delivery, birth weight, APGAR score at 1 and 5 min were significantly lower (all, p < .001) in the study group, non-reassure fetal heart rate tracing (p = .09) and NICU admission (p = .02) were significantly higher. SDC 1 level was 2,00 ± 1,47 ng/mL and 2,34 ± 1,12 ng/mL in the FGR and control groups, respectively (p = .008). In the study group SDC 1 level was 1,69 ± 2,00 in those with gestational age below 32 weeks and 2,13 ± 1,18 in those with gestational age above 32 weeks and there was a statistically significant difference between the groups (p = .015). Plasma SDC 1 concentration of 2,1850 ng/mL or less had a sensitivity of 70%, a specificity of 72%, area under the ROC curve .65 (p < .005).

CONCLUSIONS

Low maternal plasma SDC1 level may be associated with placental insufficiency and FGR. Low levels of SDC1 may be helpful as a predictor for the development of FGR during gestation.

Syndecans, Exostosins and Sulfotransferases as Potential Synovial Inflammation Moderators in Patients with Hip Osteoarthritis

The gradual deterioration of articular cartilage was thought to be the central event in osteoarthritis (OA), but recent studies demonstrated the importance of low-grade synovitis in the progression of OA. The Syndecan (SDC) family of membrane proteoglycans is known to be involved in the regulation of inflammation, but there is limited evidence considering the role of syndecans in OA synovitis. Our study aimed to investigate the hip OA synovial membrane expression patterns of SDC1, SDC2 and SDC4, as well as exostosins and sulfotransferases (enzymes involved in the polymerisation and modification of syndecans' heparan sulphate chains). Synovial membrane samples of patients with OA (24) were divided into two groups according to their Krenn synovitis score severity. The immunohistochemical expressions of SDC1, SDC2, SDC4, EXT1, EXT2, NDST1 and NDST2 in synovial intima and subintima were then analysed and compared with the control group (patients with femoral neck fracture). According to our study, the immunoexpression of SDC1, NDST1 and EXT2 is significantly increased in the intimal cells of OA synovial membrane in patients with lower histological synovitis scores and SDC4 in patients with higher synovitis scores, in comparison with non-OA controls. The difference in the expression of SDC2 among the OA and non-OA groups was insignificant. SDC1, SDC4, NDST1 and EXT2 seem to be involved as inflammation moderators in low-grade OA synovitis and, therefore, should be further investigated as potential markers of disease progression and therapeutic goals.

Roles of extracellular matrix in lung diseases

Extracellular matrix (ECM) is a non-cellular constituent found in all tissues and organs. Although ECM was previously recognized as a mere "molecular glue" that supports the tissue structure of organs such as the lungs, it has recently been reported that ECM has important biological activities for tissue morphogenesis, inflammation, wound healing, and tumor progression. Proteoglycans are the main constituent of ECM, with growing evidence that proteoglycans and their associated glycosaminoglycans play important roles in the pathogenesis of several diseases. However, their roles in the lungs are incompletely understood. Leukocyte migration into the lung is one of the main aspects involved in the pathogenesis of several lung diseases. Glycosaminoglycans bind to chemokines and their interaction fine-tunes leukocyte migration into the affected organs. This review focuses on the role chemokine and glycosaminoglycan interactions in neutrophil migration into the lung. Furthermore, this review presents the role of proteoglycans such as syndecan, versican, and hyaluronan in inflammatory and fibrotic lung diseases.

Gas Plasma Exposure Alters Microcirculation and Inflammation during Wound Healing in a Diabetic Mouse Model

Diabetes can disrupt physiological wound healing, caused by decreased levels or impaired activity of angiogenic factors. This can contribute to chronic inflammation, poor formation of new blood vessels, and delayed re-epithelialization. The present study describes the preclinical application of medical gas plasma to treat a dermal, full-thickness ear wound in streptozotocin (STZ)-induced diabetic mice. Gas plasma-mediated effects occurred in both sexes but with gender-specific differences. Hyperspectral imaging demonstrated gas plasma therapy changing microcirculatory parameters, particularly oxygen saturation levels during wound healing, presumably due to the gas plasma's tissue delivery of reactive species and other bioactive components. In addition, gas plasma treatment significantly affected cell adhesion by regulating focal adhesion kinase and vinculin, which is important in maintaining skin barrier function by regulating syndecan expression and increasing re-epithelialization. An anticipated stimulation of blood vessel formation was detected via transcriptional and translational increase of angiogenic factors in gas plasma-exposed wound tissue. Moreover, gas plasma treatment significantly affected inflammation by modulating systemic growth factors and cytokine levels. The presented findings may help explain the mode of action of successful clinical plasma therapy of wounds of diabetic patients.

Acute pyelonephritis in pregnancy and plasma syndecan-1: evidence of glycocalyx involvement

BACKGROUND

Acute pyelonephritis, a risk factor for maternal sepsis, adult respiratory distress syndrome, and preterm labor, is a frequent cause of hospitalization. This condition is characterized by excessive intravascular inflammation and endothelial cell activation and dysfunction. Syndecan-1, a major component of the glycocalyx, is a gel-like layer that covers the luminal surface of healthy endothelial cells, preserving and mediating many endothelial functions. During pregnancy, there is an additional potential source of syndecan-1, the "syncytiotrophoblast glycocalyx," which lines the intervillous space. Insults that damage the glycocalyx lead to a shedding of syndecan-1 into the circulation. Hence, syndecan-1 has been proposed as a marker of endothelial injury in conditions such as sepsis, trauma, cardiovascular disease, and diabetes mellitus.

OBJECTIVE

The objective of this study was to determine whether the plasma syndecan-1 concentration changes in women with acute pyelonephritis in the presence or absence of bacteremia.

STUDY DESIGN

This cross-sectional study included three groups: (1) non-pregnant women (n = 25); (2) women with an uncomplicated pregnancy from whom samples were collected preterm (n = 61) or at term (n = 69); and (3) pregnant women diagnosed with acute pyelonephritis from whom samples were collected at the time of diagnosis during the second and third trimesters (n = 33). The diagnosis of acute pyelonephritis was based on clinical findings and a positive urine culture for bacteria. Blood culture results were available in 85% (28/33) of women with acute pyelonephritis. Plasma concentrations of syndecan-1 were determined by a validated immunoassay.

RESULTS

(1) Women with an uncomplicated pregnancy had a higher plasma concentration of syndecan-1 than non-pregnant women. The geometric mean (95% confidence interval [CI]) of syndecan-1 concentration was 51.0 (12.1-216.1) ng/mL in non-pregnant controls; 1280 (365-4487) ng/mL in normal preterm gestations; and 1786 (546-5834) ng/mL in normal term gestations (adjusted p < .005 for all three between group comparisons); (2) plasma syndecan-1 concentrations increased with gestational age among women with a normal pregnancy (p < .001, R2 = 0.27); (3) syndecan-1 multiple of the mean (MoM) values in pregnant patients with acute pyelonephritis were higher than those in normal pregnant women based on second- and third-trimester samples (p = .048, 1.26-fold change). The increase was driven primarily by cases with a positive blood culture (p = .009, 1.74-fold change); (4) when data from third-trimester samples were compared, overall differences in syndecan-1 MoM values between cases and controls were slightly larger (p = .03, 1.36- fold change), which were especially contributed to by cases with a positive blood culture (p = .023, fold change 1.79-fold change).

CONCLUSIONS

Plasma syndecan-1 concentration is higher in pregnant women and increases as a function of gestational age. Patients with acute pyelonephritis have a higher plasma concentration of syndecan-1, and this is particularly the case in the presence of bacteremia.

Low-molecular weight sulfated marine polysaccharides: Promising molecules to prevent neurodegeneration in mucopolysaccharidosis IIIA?

Mucopolysaccharidosis IIIA is a hereditary disease caused by mutations in the sulfamidase enzyme that participates in catabolism of heparan sulfate (HS), leading to HS fragment accumulation and multisystemic failure. No cure exists and death occurs around the second decade of life. Two low molecular weight highly sulfated compounds derived from marine diabolican and infernan exopolysaccharides (A5_3 and A5_4, respectively) with heparanase inhibiting properties were tested in a MPSIIIA cell line model, resulting in limited degradation of intracellular HS. Next, we observed the effects of intraperitoneal injections of the diabolican derivative A5_3 from 4 to 12 weeks of age on MPSIIIA mice. Brain metabolism and microstructure, levels of proteins and genes involved in MPSIIIA brain pathophysiology were also investigated. 1H-Magnetic Resonance Spectroscopy (MRS) indicated deficits in energetic metabolism, tissue integrity and neurotransmission at both 4 and 12 weeks in MPSIIIA mice, with partial protective effects of A5_3. Ex-vivo Diffusion Tensor Imaging (DTI) showed white matter microstructural damage in MPSIIIA, with noticeable protective effects of A5_3. Protein and gene expression assessments displayed both pro-inflammatory and pro-apoptotic profiles in MPSIIIA mice, with benefits of A5_3 counteracting neuroinflammation. Overall, derivative A5_3 was well tolerated and was shown to be efficient in preventing brain metabolism failure and inflammation, resulting in preserved brain microstructure in the context of MPSIIIA.

Endothelial dysfunction triggers acute respiratory distress syndrome in patients with sepsis: a narrative review

Acute respiratory distress syndrome (ARDS) is a severe organ failure occurring mainly in critically ill patients as a result of different types of insults such as sepsis, trauma or aspiration. Sepsis is the main cause of ARDS, and it contributes to a high mortality and resources consumption both in hospital setting and in the community. ARDS develops mainly an acute respiratory failure with severe and often refractory hypoxemia. ARDS also has long term implications and sequelae. Endothelial damage plays an important role in the pathogenesis of ARDS. Understanding the mechanisms of ARDS presents opportunities for novel diagnostic and therapeutic targets. Biochemical signals can be used in concert to identify and classify patients into ARDS phenotypes allowing earlier effective treatment with personalised therapies. This is a narrative review where we aimed to flesh out the pathogenetic mechanisms and heterogeneity of ARDS. We examine the links between endothelium damage and its contribution to organ failure. We have also investigated future strategies for treatment with a special emphasis in endothelial damage.

Multi-Omics Endotypes in ICU Sepsis-Induced Immunosuppression

It is evident that the admission of some patients with sepsis and septic shock to hospitals is occurring late in their illness, which has contributed to the increase in poor outcomes and high fatalities worldwide across age groups. The current diagnostic and monitoring procedure relies on an inaccurate and often delayed identification by the clinician, who then decides the treatment upon interaction with the patient. Initiation of sepsis is accompanied by immune system paralysis following "cytokine storm". The unique immunological response of each patient is important to define in terms of subtyping for therapy. The immune system becomes activated in sepsis to produce interleukins, and endothelial cells express higher levels of adhesion molecules. The proportions of circulating immune cells change, reducing regulatory cells and increasing memory cells and killer cells, having long-term effects on the phenotype of CD8 T cells, HLA-DR, and dysregulation of microRNA. The current narrative review seeks to highlight the potential application of multi-omics data integration and immunological profiling at the single-cell level to define endotypes in sepsis and septic shock. The review will consider the parallels and immunoregulatory axis between cancer and immunosuppression, sepsis-induced cardiomyopathy, and endothelial damage. Second, the added value of transcriptomic-driven endotypes will be assessed through inferring regulatory interactions in recent clinical trials and studies reporting gene modular features that inform continuous metrics measuring clinical response in ICU, which can support the use of immunomodulating agents.

The role of the alveolar epithelial glycocalyx in acute respiratory distress syndrome

The alveolar epithelial glycocalyx is a dense anionic layer of glycosaminoglycans (GAGs) and proteoglycans that lines the apical surface of the alveolar epithelium. In contrast to the pulmonary endothelial glycocalyx, which has well-established roles in vascular homeostasis and septic organ dysfunction, the alveolar epithelial glycocalyx is less understood. Recent preclinical studies demonstrated that the epithelial glycocalyx is degraded in multiple murine models of acute respiratory distress syndrome (ARDS), particularly those that result from inhaled insults (so-called "direct" lung injury), leading to shedding of GAGs into the alveolar airspaces. Epithelial glycocalyx degradation also occurs in humans with respiratory failure, as quantified by analysis of airspace fluid obtained from ventilator heat moisture exchange (HME) filters. In patients with ARDS, GAG shedding correlates with the severity of hypoxemia and is predictive of the duration of respiratory failure. These effects may be mediated by surfactant dysfunction, as targeted degradation of the epithelial glycocalyx in mice was sufficient to cause increased alveolar surface tension, diffuse microatelectasis, and impaired lung compliance. In this review, we describe the structure of the alveolar epithelial glycocalyx and the mechanisms underlying its degradation during ARDS. We additionally review the current state of knowledge regarding the attributable effect of epithelial glycocalyx degradation in lung injury pathogenesis. Finally, we address glycocalyx degradation as a potential mediator of ARDS heterogeneity, and the subsequent value of point-of-care quantification of GAG shedding to potentially identify patients who are most likely to respond to pharmacological agents aimed at attenuating glycocalyx degradation.

Endothelial Damage and the Microcirculation in Critical Illness

Endothelial integrity maintains microcirculatory flow and tissue oxygen delivery. The endothelial glycocalyx is involved in cell signalling, coagulation and inflammation. Our ability to treat critically ill and septic patients effectively is determined by understanding the underpinning biological mechanisms. Many mechanisms govern the development of sepsis and many large trials for new treatments have failed to show a benefit. Endothelial dysfunction is possibly one of these biological mechanisms. Glycocalyx damage is measured biochemically. Novel microscopy techniques now mean the glycocalyx can be indirectly visualised, using sidestream dark field imaging. How the clinical visualisation of microcirculation changes relate to biochemical laboratory measurements of glycocalyx damage is not clear. This article reviews the evidence for a relationship between clinically evaluable microcirculation and biological signal of glycocalyx disruption in various diseases in ICU. Microcirculation changes relate to biochemical evidence of glycocalyx damage in some disease states, but results are highly variable. Better understanding and larger studies of this relationship could improve phenotyping and personalised medicine in the future. Damage to the glycocalyx could underpin many critical illness pathologies and having real-time information on the glycocalyx and microcirculation in the future could improve patient stratification, diagnosis and treatment.

Promalignant effects of antiangiogenics in the tumor microenvironment

Antiangiogenic therapies are considered a promising strategy against solid tumors. Their aim is to inhibit the formation of new blood vasculature, thereby reducing the oxygen and nutrient supply to prevent further tumor growth and spreading. However, the strategy has seen limitations, as survival benefits are modest and often accompanied with increased tumor aggressiveness in form of invasion and metastasis. Antiangiogenic induced changes in the tumor microenvironment, such as hypoxia, mechanical stress or extracellular acidification can activate different receptors of tumoral and stromal cells and induce an extensive remodeling of the entire tumor microenvironment, with the overall goal to invade nearby tissues and regain access to the vasculature. In this regard, receptor tyrosine kinases have been studied intensively and especially the inhibition of c-Met has given promising results, characterized by a reduction in invasiveness and prolonged survival. Receptors that sense changes in the extracellular matrix like integrins or proteoglycans can also induce downstream signaling that stimulates the expression of remodeling factors such as new matrix components, enzymes or chemoattractants. Targeting multiple receptors and sensors of cancer cells simultaneously might represent an effective second line treatment that prevents the formation of malignant side effects.

Heparan Sulfate Glycosaminoglycan Is Predicted to Stabilize Inflammatory Infiltrate Formation and RANKL/OPG Ratio in Severe Periodontitis in Humans

Since chronically inflamed periodontal tissue exhibits extracellular matrix (ECM) degradation, the possible alternative to standard periodontitis treatment is to restore ECM by supplementing its components, including heparan sulfate glycosaminoglycan (HS GAG). Supplementation of the degraded ECM with synthetic derivatives of HS GAGs has been shown to be effective for periodontal tissue regeneration in experimental animal models of periodontitis. However, the potential of HS GAG supplementation for the treatment of periodontal disease in humans is still unknown. Here, we used a statistical model to investigate the role of HS GAG on inflammatory infiltrate formation and alveolar bone resorption in humans with severe periodontitis. The model was based on data from immunofluorescence staining (IF) of human gingiva samples, and reconstruction of a subset of HS GAG -related proteins from STRING reactome database. According to predictions, increased expression of native HS GAG might stabilize the accumulation of gingival inflammatory infiltrate (represented by the general inflammatory cell marker CD45) and alveolar bone resorption (represented by Receptor Activator of Nuclear ΚΒ ligand (RANKL) and osteoprotegerin (OPG) ratio) but could not restore them to healthy tissue levels. Therefore, supplementation of native HS GAG may be of limited benefits for the treatment of sever periodontitis in humans.

New Insight on 2D In Vitro Angiogenesis Models: All That Stretches Is Not a Tube

Highlights

Abstract

A Matrigel-based tube formation assay is a simple and widely accepted 2D angiogenesis model in vitro. Extracellular matrix (EM) proteins and growth factors (GFs) from Matrigel^TM exclusively trigger endothelial cell (EC) tubular network (ETN) formation. Co-culture of ECs with mesenchymal stromal cells (MSCs) is another and more reliable in vitro angiogenesis assay. MSCs modulate ETN formation through intercellular interactions and as a supplier of EM and GFs. The aim of the present study was to compare the expression profile of ECs in both models. We revealed upregulation of the uPA, uPAR, Jagged1, and Notch2 genes in dividing/migrating ECs and for ECs in both experimental models at 19 h. The expression of endothelial–mesenchymal transition genes largely increased in co-cultured ECs whereas Notch and Hippo signaling pathway genes were upregulated in ECs on Matrigel^TM. We showed that in the co-culture model, basement membrane (BM) deposition is limited only to cell-to-cell contacts in contrast to Matrigel^TM, which represents by itself fully pre-assembled BM matrix. We suggest that ETN in a co-culture model is still in a dynamic process due to immature BM whereas ECs in the Matrigel^TM assay seem to be at the final stage of ETN formation.

Can Micro RNA-24 Affect the Cardiovascular Morbidity in Systemic Lupus Erythematosus by Targeting YKL-40?

Background

Systemic lupus erythematosus (SLE) is an autoimmune disease with inflammatory nature. One of the leading causes of death in SLE patients is cardiovascular (CVS) morbidity. MiRNA-24 is highly expressed in vascular endothelial cells (VECs). This dysregulated expression pattern is associated with dysfunction or even damage of VECs and leads to the occurrence of cardiovascular diseases. YKL- 40 is an inflammatory glycoprotein involved in the pathogenesis of endothelial dysfunction and thereby atherosclerosis. In this work, we aimed at illustrating the possible role of miR-24 and its target YKL-40 in the pathogenesis of the CVS morbidity associated with SLE.

Methods

This work was conducted on 40 SLE patients and 40 healthy controls. Quantitative real-time PCR (qPCR) was done to estimate the expression level of miRNA-24 in serum. In addition, we measured the serum level of YKL-40 using ELISA.

Results

miR-24-fold change was found to be down-regulated, whereas serum YKL- 40 was up-regulated among SLE patients with observed significant and negative correlation between the two parameters.

Conclusion

Our study provided an insight about the role of miR-24 and its target serum YKL-40 protein in the development of SLE-related inflammation and atherosclerosis.

Inflammatory markers calprotectin, NETs, syndecan-1 and neopterin in COVID-19 convalescent blood donors

Persisting inflammation has been discovered in lungs and other parenchymatous organs of some COVID-19 convalescents. Calprotectin, neutrophil extracellular traps (NETs), syndecan-1 and neopterin are general key inflammatory markers, and systemically enhanced levels of them may remain after the COVID-19 infection. These inflammatory markers were therefore measured in serum samples of 129 COVID-19 convalescent and 27 healthy blood donors or employees at Oslo Blood bank, Norway. Also antibodies against SARS-CoV-2 nucleocapsid antigen were measured, and timing of sampling and severity of infection noted. Whereas neopterin and NETs values remained low and those for syndecan-1 were not raised to statistically significant level, concentrations for calprotectin, as measured by a novel mixed monoclonal assay, were significantly increased in the convalescents. Antibodies against SARS-CoV-2 nucleocapsid antigen were elevated, but did not correlate with levels of inflammatory markers. Difference between the groups in only one biomarker makes evaluation of ongoing or residual inflammation in the convalescents difficult. If there is a low-grade inflammation, it would in that case involve neutrophils.

The INSR/AKT/mTOR pathway regulates the pace of myogenesis in a syndecan-3-dependent manner

Muscle stem cells (MuSCs) are indispensable for muscle regeneration. A multitude of extracellular stimuli direct MuSC fate decisions from quiescent progenitors to differentiated myocytes. The activity of these signals is modulated by coreceptors such as syndecan-3 (SDC3). We investigated the global landscape of SDC3-mediated regulation of myogenesis using a phosphoproteomics approach which revealed, with the precision level of individual phosphosites, the large-scale extent of SDC3-mediated regulation of signal transduction in MuSCs. We then focused on INSR/AKT/mTOR as a key pathway regulated by SDC3 during myogenesis and mechanistically dissected SDC3-mediated inhibition of insulin receptor signaling in MuSCs. SDC3 interacts with INSR ultimately limiting signal transduction via AKT/mTOR. Both knockdown of INSR and inhibition of AKT rescue Sdc3^-/- MuSC differentiation to wild type levels. Since SDC3 is rapidly downregulated at the onset of differentiation, our study suggests that SDC3 acts a timekeeper to restrain proliferating MuSC response and prevent premature differentiation.

Usefulness of Serum Biomarkers of Endothelial Glycocalyx Damage in Prognosis of Decompensated Patients with Heart Failure with Reduced Ejection Fraction

The surface layer of endothelium contains the endothelial glycocalyx (eGC), consisting of proteoglycan polymers. Syndecan-1, heparan sulfate, and hyaluronic acid are major constituents of eGC, and their increasing detection in serum represents active degradation of eGC. Serum was obtained from patients with no heart failure (non-HF) and with HF with reduced ejection fraction (HFrEF) of <40%, either stable chronic HF (CHF) or acute decompensated HF (ADHF). Syndecan-1, heparan sulfate, and hyaluronic acid were measured for comparisons in the groups, adjusting for clinical and laboratory values. In our study cohort, 51 non-HF, 66 ADHF, and 72 patients with CHF were enrolled. Between ADHF and CHF, left ventricular (LV) mass index, LV ejection fraction, and pulmonary capillary wedge pressure did not differ. Patients with ADHF had significantly higher levels of eGC constituents compared with CHF and non-HF. During follow-up, 21 patients with HF died, and the mortality rate was higher in patients with higher serum syndecan-1 or heparan sulfate (log-rank p = 0.007 and 0.016, respectively). In multivariate analysis, a doubling of serum heparan sulfate concentration amounted to a 31.5% increase in all-cause mortality (hazard ratio = 1.315, confidence interval = 1.012-1.709, p = 0.040). In conclusion, serum biomarkers of eGC were elevated in ADHF (but not in CHF) in patients with HFrEF, suggesting the potential roles of eGC degradation and endothelial dysfunction in HF decompensation. Only elevated heparin sulfate was associated with higher all-cause mortality after adjusting for traditional risk variables in patients with HFrEF.

Balancing Microthrombosis and Inflammation via Injectable Protein Hydrogel for Inflammatory Bowel Disease

Emerging evidence indicates that a vicious cycle between inflammation and microthrombosis catalyzes the pathogenesis of inflammatory bowel disease (IBD). Over-stimulated inflammation triggers a coagulation cascade and leads to microthrombosis, which further complicates the injury through tissue hypoxia and ischemia. Herein, an injectable protein hydrogel with anti-thrombosis and anti-inflammation competency is developed to impede this cycle, cross-linked by silver ion mediated metal-ligand coordination and electronic interaction with sulfhydryl functionalized bovine serum albumin and heparin, respectively. The ex vivo experiments show that the hydrogel, HEP-Ag-BSA, exhibits excellent self-healing ability, injectability, biocompatibility, and sustained drug release. HEP-Ag-BSA also demonstrates anti-coagulation and anti-inflammation abilities via coagulation analysis and lipopolysaccharide stimulation assay. The in vivo imaging confirms the longer retention time of HEP-Ag-BSA at inflammatory sites than in normal mucosa owing to electrostatic interactions. The in vivo study applying a mouse model with colitis also reveals that HEP-Ag-BSA can robustly inhibit inflammatory microthrombosis with reduced bleeding risk. This versatile protein hydrogel platform can definitively hinder the "inflammation and microthrombosis" cycle, providing a novel integrated approach against IBD.

Syndecan-1 Is Overexpressed in Human Thoracic Aneurysm but Is Dispensable for the Disease Progression in a Mouse Model

Glycosaminoglycans (GAGs) pooling has long been considered as one of the histopathological characteristics defining thoracic aortic aneurysm (TAA) together with smooth muscle cells (SMCs) apoptosis and elastin fibers degradation. However, little information is known about GAGs composition or their potential implication in TAA pathology. Syndecan-1 (SDC-1) is a heparan sulfate proteoglycan that is implicated in extracellular matrix (ECM) interaction and assembly, regulation of SMCs phenotype, and various aspects of inflammation in the vascular wall. Therefore, the aim of this study was to determine whether SDC-1 expression was regulated in human TAA and to analyze its role in a mouse model of this disease. In the current work, the regulation of SDC-1 was examined in human biopsies by RT-qPCR, ELISA, and immunohistochemistry. In addition, the role of SDC-1 was evaluated in descending TAA in vivo using a mouse model combining both aortic wall weakening and hypertension. Our results showed that both SDC-1 mRNA and protein are overexpressed in the media layer of human TAA specimens. RT-qPCR experiments revealed a 3.6-fold overexpression of SDC-1 mRNA (p = 0.0024) and ELISA assays showed that SDC-1 protein was increased 2.3 times in TAA samples compared with healthy counterparts (221 ± 24 vs. 96 ± 33 pg/mg of tissue, respectively, p = 0.0012). Immunofluorescence imaging provided evidence that SMCs are the major cell type expressing SDC-1 in TAA media. Similarly, in the mouse model used, SDC-1 expression was increased in TAA specimens compared to healthy samples. Although its protective role against abdominal aneurysm has been reported, we observed that SDC-1 was dispensable for TAA prevalence or rupture. In addition, SDC-1 deficiency did not alter the extent of aortic wall dilatation, elastin degradation, collagen deposition, or leukocyte recruitment in our TAA model. These findings suggest that SDC-1 could be a biomarker revealing TAA pathology. Future investigations could uncover the underlying mechanisms leading to regulation of SDC-1 expression in TAA.

The positive effect of malaria IPTp-SP on birthweight is mediated by gestational weight gain but modifiable by maternal carriage of enteric pathogens

BACKGROUND

Poor pregnancy and birth outcomes are common in sub-Saharan Africa and have complex aetiologies. Sulfadoxine-pyrimethamine (SP), given for intermittent preventive therapy of malaria in pregnancy (IPTp), is one of few existing interventions that improves outcomes of both mother and baby despite widespread SP-resistant malaria. Compelling evidence exists that malaria-independent pathways contribute to this protective effect, but the exact sources of non anti-malarial protection remained unknown. We hypothesized that the beneficial effect of SP on birthweight is mediated by SP activity on maternal factors, including increased gestational weight gain and antibiotic activity on pathogens in the maternal gut.

METHODS

Expectant mothers from a larger randomized control trial comparing the efficacy of IPTp-SP to IPTp with dihydroartemisinin-piperaquine (DP) were also enrolled in this sub-study study at their first antenatal care visit before commencement of IPTp (n = 105). Participants were followed monthly until delivery. Weights and mid-to-upper-arm circumferences (MUAC) were recorded. Monthly stool samples were collected and screened for five Escherichia coli pathotypes, Shigella spp., Vibrio cholerae, Salmonella, Campylobacter coli/jejuni, and three protozoa (Giardia spp., Entameba histolytica, and Cryptosporidium spp.) using previously validated molecular assays.

FINDINGS

IPTp-SP vs. IPTP-DP was associated with higher maternal gestational weight gain (GWG) and nutritional indicators (MUAC and body-mass index, BMI). GWG was found to be a mediator of the birthweight and IPTp-SP relationship, as the birthweight of SP infants, but not DP infants, varied according to maternal GWG. The burden of maternal enteric infections was high. The three most commonly observed pathogens were enteroaggregative E. coli (EAEC), atypical enteropathogenic E.coli/enterohaemorrhagic E. coli (aEPEC/EHEC), and typical enteropathogenic E.coli (tEPEC). We found that SP reduced the prevalence of EAEC in a dose-dependent manner. After 3 or more doses, SP-recipients were 90% less likely to be infected with EAEC compared to DP-recipients (ORadj = 0.07, CI95 = 0.12, 0.39, p = 0.002). Compared to DP, this coincided with higher maternal gestational weight gain (GWG) and nutritional indicators (MUAC and body-mass index, BMI). The beneficial effect of SP on maternal GWG, MUAC and BMI, was lower if SP mothers had detectable EAEC, aEPEC/EHEC, tEPEC, and LT-ETEC at baseline. Maternal EAEC and tEPEC at baseline associated with lower birthweight for babies of both SP mothers and DP mothers. When comparing IPTp regimens, the positive effect of SP on birthweight compared to DP was only observed for infants of women who did not test positive for EAEC at baseline (adjusted mean birthweight difference SP vs. DP = 156.0 g, CI95 = -18.0 g, 336.9 g, p = 0.087), though confidence intervals crossed the null.

INTERPRETATION

Our findings indicate that in pregnant Malawian women, IPTp-SP vs. IPTp-DP is consistently associated with higher MUAC, BMI, and GWG following the WHO-recommended regimen of at least 3 doses, but carriage of maternal gut pathogens before initiation of IPTp lessens this effect. Because GWG was a mediator of the association between birthweight and SP, we show that SP's previously proven positive effect on birthweight is by promoting maternal weight gain. Overall, our results present one plausible pathway SP exerts malaria-independent protection against poor birth outcomes in the context of its waning antimalarial activity and warrants further investigation.

FUNDING

A full list of funding bodies that contributed to this study can be found in the Acknowledgements section.

B-cell maturation antigen targeting strategies in multiple myeloma treatment, advantages and disadvantages

B cell maturation antigen (BCMA), a transmembrane glycoprotein member of the tumor necrosis factor receptor superfamily 17 (TNFRSF17), highly expressed on the plasma cells of Multiple myeloma (MM) patients, as well as the normal population. BCMA is used as a biomarker for MM. Two members of the TNF superfamily proteins, including B-cell activating factor (BAFF) and A proliferation-inducing ligand (APRIL), are closely related to BCMA and play an important role in plasma cell survival and progression of MM. Despite the maximum specificity of the monoclonal antibody technologies, introducing the tumor-specific antigen(s) is not applicable for all malignancies, such as MM that there plenty of relatively specific antigens such as GPCR5D, MUC1, SLAMF7 and etc., but higher expression of BCMA on these cells in comparison with normal ones can be regarded as a relatively exclusive marker. Currently, different monoclonal antibody (mAb) technologies applied in anti-MM therapies such as daratuzumab, SAR650984, GSK2857916, and CAR-T cell therapies are some of these tools that are reviewed in the present manuscript. By the way, the structure, function, and signaling of the BCMA and related molecule(s) role in normal plasma cells and MM development, evaluated as well as the potential side effects of its targeting by different CAR-T cells generations. In conclusion, BCMA can be regarded as an ideal molecule to be targeted in immunotherapeutic methods, regarding lower potential systemic and local side effects.

The Role and Therapeutic Value of Syndecan-1 in Cancer Metastasis and Drug Resistance

Metastasis and relapse are major causes of cancer-related fatalities. The elucidation of relevant pathomechanisms and adoption of appropriate countermeasures are thus crucial for the development of clinical strategies that inhibit malignancy progression as well as metastasis. An integral component of the extracellular matrix, the type 1 transmembrane glycoprotein syndecan-1 (SDC-1) binds cytokines and growth factors involved in tumor microenvironment modulation. Alterations in its localization have been implicated in both cancer metastasis and drug resistance. In this review, available data regarding the structural characteristics, shedding process, and nuclear translocation of SDC-1 are detailed with the aim of highlighting strategies directly targeting SDC-1 as well as SDC-1-mediated carcinogenesis.

Human induced pluripotent stem cell-derived macrophages ameliorate liver fibrosis

With an increasing number of patients with degenerative hepatic diseases, such as liver fibrosis, and a limited supply of donor organs, there is an unmet need for therapies that can repair or regenerate damaged liver tissue. Treatment with macrophages that are capable of phagocytosis and anti-inflammatory activities such as secretion of matrix metalloproteinases (MMPs) provide an attractive cellular therapy approach. Human induced pluripotent stem cells (iPSCs) are capable of efficiently generating a large-scale, homogenous population of human macrophages using fully defined feeder- and serum-free differentiation protocol. Human iPSC-macrophages exhibit classical surface cell markers and phagocytic activity similar to peripheral blood-derived macrophages. Moreover, gene and cytokine expression analysis reveal that these macrophages can be efficiently polarized to pro-inflammatory M1 or anti-inflammatory M2 phenotypes in presence of LPS + IFN-γ and IL-4 + IL-13, respectively. M1 macrophages express high level of CD80, TNF-α, and IL-6 while M2 macrophages show elevated expression of CD206, CCL17, and CCL22. Here, we demonstrate that treatment of liver fibrosis with both human iPSC-derived macrophage populations and especially M2 subtype significantly reduces fibrogenic gene expression and disease associated histological markers including Sirius Red, αSMA and desmin in immunodeficient Rag2-/- γc-/- mice model, making this approach a promising cell-based avenue to ameliorate fibrosis.

Glycosaminoglycans: Sweet as Sugar Targets for Topical Skin Anti-Aging

Glycosaminoglycans (GAGs) are long, linear polysaccharides comprised of repeating disaccharide units with pleiotropic biological functions, with the non-sulfated GAG hyaluronic acid (HA), and sulfated GAGs dermatan sulfate, chondroitin sulfate, heparan sulfate, keratan sulfate, and to a lesser extent heparin all being expressed in skin. Their ability to regulate keratinocyte proliferation and differentiation, inflammatory processes and extracellular matrix composition and quality demonstrates their critical role in regulating skin physiology. Similarly, the water-binding properties of GAGs and structural qualities, particularly for HA, are crucial for maintaining proper skin form and hydration. The biological importance of GAGs, as well as extensive evidence that their properties and functions are altered in both chronological and extrinsic skin aging, makes them highly promising targets to improve cosmetic skin quality. Within the present review, we examine the cutaneous biological activity of GAGs alongside the protein complexes they form called proteoglycans and summarize the age-related changes of these molecules in skin. We also examine current topical interventional approaches to modulate GAGs for improved skin quality such as direct exogenous administration of GAGs, with a particular interest in strategies targeted at potentiating GAG levels in skin through either attenuating GAG degradation or increasing GAG production.

Pro-angiogenic effects of pregnancy-specific glycoproteins in endothelial and extravillous trophoblast cells

We previously reported that binding to heparan sulfate (HS) is required for the ability of the placentally secreted pregnancy-specific glycoprotein 1 (PSG1) to induce endothelial tubulogenesis. PSG1 is composed of four immunoglobulin-like domains but which domains of the protein bind to HS remains unknown. To analyze the interaction of PSG1 with HS, we generated several recombinant proteins, including the individual domains, chimeric proteins between two PSG1 domains, and mutants. Using flow cytometric and surface plasmon resonance studies, we determined that the B2 domain of PSG1 binds to HS and that the positively charged amino acids encompassed between amino acids 43-59 are required for this interaction. Furthermore, we showed that the B2 domain of PSG1 is required for the increase in the formation of tubes by endothelial cells (EC) including a human endometrial EC line and two extravillous trophoblast (EVT) cell lines and for the pro-angiogenic activity of PSG1 observed in an aortic ring assay. PSG1 enhanced the migration of ECs while it increased the expression of matrix metalloproteinase-2 in EVTs, indicating that the pro-angiogenic effect of PSG1 on these two cell types may be mediated by different mechanisms. Despite differences in amino acid sequence, we observed that all human PSGs bound to HS proteoglycans and confirmed that at least two other members of the family, PSG6 and PSG9, induce tube formation. These findings contribute to a better understanding of the pro-angiogenic activity of human PSGs and strongly suggest conservation of this function among all PSG family members.

Circulating CD138 enhances disease progression by augmenting autoreactive antibody production in a mouse model of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a progressive autoimmune disease characterized by high levels of antibodies directed against nuclear antigens. Elevated serum CD138, a heparan sulfate–bearing proteoglycan, correlates with increased disease activity in patients with SLE, but the contribution of CD138 to lupus disease is not known. Corroborating patient data, we detected an increase in serum CD138 in MRL/MpJ-Fas^lpr/J (MRL/Lpr) mice (a model for SLE disease) parallel to disease activity. Although T-cell receptor β (TCRβ)+CD138+ T cells typically expand in MRL/Lpr mice as the disease progresses, surprisingly, TCRβ+CD138− cells were the primary source of circulating CD138, as the transfer of TCRβ+CD138− cells, but not TCRβ+CD138+ cells, to young MRL/Lpr mice resulted in higher serum CD138 in the recipients. We found that trypsin was able to cleave CD138 from TCRβ+CD138+ cells, and that trypsin was highly expressed in TCRβ+CD138− cells. Moreover, trypsin inhibitors, the “defined trypsin inhibitor” and leupeptin, increased CD138 expression on TCRβ+CD138− cells, suggesting a contribution of cleaved CD138 to the increase in blood CD138 levels. Furthermore, soluble CD138 was able to bind “a proliferation-inducing ligand” (APRIL) and enhance APRIL-mediated plasma cell generation and autoreactive antibody production through the phosphorylation of extracellular signal–regulated kinase in B cells. The APRIL receptor “transmembrane activator, calcium modulator, and cyclophilin ligand interactor” was involved in the enhancement of APRIL activity by CD138, as the synergistic effect of APRIL and CD138 was ablated in transmembrane activator, calcium modulator, and cyclophilin ligand interactor–deficient B cells. These findings indicate a regulatory role for soluble CD138 in B-cell differentiation and autoreactive antibody production in SLE disease.

Therapeutic potential of targeting membrane-spanning proteoglycan SDC4 in hepatocellular carcinoma

Syndecan-4 (SDC4) functions as a major endogenous membrane-associated receptor and widely regulates cytoskeleton, cell adhesion, and cell migration in human tumorigenesis and development, which represents a charming anti-cancer therapeutic target. Here, SDC4 was identified as a direct cellular target of small-molecule bufalin with anti-hepatocellular carcinoma (HCC) activity. Mechanism studies revealed that bufalin directly bond to SDC4 and selectively increased SDC4 interaction with substrate protein DEAD-box helicase 23 (DDX23) to induce HCC genomic instability. Meanwhile, pharmacological promotion of SDC4/DDX23 complex formation also inactivated matrix metalloproteinases (MMPs) and augmented p38/JNK MAPKs phosphorylation, which are highly associated with HCC proliferation and migration. Notably, specific knockdown of SDC4 or DDX23 markedly abolished bufalin-dependent inhibition of HCC proliferation and migration, indicating SDC4/DDX23 signaling axis is highly involved in the HCC process. Our results indicate that membrane-spanning proteoglycan SDC4 is a promising druggable target for HCC, and pharmacological regulation of SDC4/DDX23 signaling axis with small-molecule holds great potential to benefit HCC patients.

The Diagnostic Usefulness of Circulating Profile of Extracellular Matrix Components: Sulfated Glycosaminoglycans (sGAG), Hyaluronan (HA) and Extracellular Part of Syndecan-1 (sCD138) in Patients with Crohn's Disease and Ulcerative Colitis

The described research focused on the diagnostic usefulness of sulfated glycosaminoglycans (sGAG), hyaluronan (HA), and extracellular part of syndecan-1 (sCD138) as new markers related to extracellular matrix (ECM) remodeling in the intestine during the two most common forms of inflammatory bowel diseases (IBD), i.e., ulcerative colitis (UC) and Crohn’ disease (CD). Inflammatory markers belonging to ECM components were assessed in serum of patients with IBD using an immunoenzymatic method (HA and sCD138) and a method based on the reaction with dimethylmethylene blue (sulfated GAG). Measurements were carried out twice: at baseline and after one year of therapy with prednisone (patients with CD) or adalimumab (patients with UC). No quantitative changes were observed in serum sGAG, HA, and sCD138 concentrations between patients newly diagnosed with CD and the healthy group. In the case of patients with UC, the parameter which significantly differentiated healthy subjects and patients with IBD before biological therapy was HA. Significant correlation between serum HA level and inflammation activity, expressed as Mayo score, was also observed in patients with UC. Moreover, the obtained results have confirmed that steroid therapy with prednisone significantly influenced the circulating profile of all examined ECM components (sGAG, HA, and sCD138), whereas adalimumab therapy in patients with UC led to a significant change in only circulating sGAG levels. Moreover, the significant differences in serum HA levels between patients with UC and CD indicate that quantification of circulating HA may be useful in the differential diagnosis of CD and UC.

Pathological Angiogenesis Requires Syndecan-4 for Efficient VEGFA-Induced VE-Cadherin Internalization

[Figure: see text].

Soluble syndecan-1 and glycosaminoglycans in preeclamptic and normotensive pregnancies

Preeclampsia, an important cause of maternal and fetal morbidity and mortality, is associated with increased sFLT1 levels and with structural and functional damage to the glycocalyx contributing to endothelial dysfunction. We investigated glycocalyx components in relation to preeclampsia in human samples. While soluble syndecan-1 and heparan sulphate were similar in plasma of preeclamptic and normotensive pregnant women, dermatan sulphate was increased and keratan sulphate decreased in preeclamptic women. Dermatan sulphate was correlated with soluble syndecan-1, and inversely correlated with blood pressure and activated partial thromboplastin time. To determine if syndecan-1 was a prerequisite for the sFlt1 induced increase in blood pressure in mice we studied the effect of sFlt1 on blood pressure and vascular contractile responses in syndecan-1 deficient and wild type male mice. The classical sFlt1 induced rise in blood pressure was absent in syndecan-1 deficient mice indicating that syndecan-1 is a prerequisite for sFlt1 induced increase in blood pressure central to preeclampsia. The results show that an interplay between syndecan-1 and dermatan sulphate contributes to sFlt1 induced blood pressure elevation in pre-eclampsia.

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

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

Effects and mechanisms of histatins as novel skin wound-healing agents

Wound healing is a complex and important physiological process that maintains the integrity of skin after various injuries. Abnormal wound healing, especially of chronic wounds, impairs normal physical function. Therefore, the search for effective and safe healing agents is one of the main concerns. Histatins are histidine-rich low molecular weight peptides that are expressed in the saliva of both humans and higher primates. Histatins have two main biological effects, cell stimulation and bacteria killing, with the former playing an important role in wound healing by promoting epithelial cell and fibroblast migration and angiogenesis and enhancing the re-epithelialization of the wounded area. Because of these biological effects, histatins have been shown to be promising agents of improved wound healing. Histatins are categorized into many subtypes, of which histatin 1 and its hydrolysates are the most effective in promoting wound healing. This review addresses the bioactivity of histatins in wound healing, such as their stimulatory effects on epithelial cells and fibroblasts, and elucidates the possible mechanisms by which histatin subtypes induce their biological effects.

A stem cell reporter based platform to identify and target drug resistant stem cells in myeloid leukemia

Intratumoral heterogeneity is a common feature of many myeloid leukemias and a significant reason for treatment failure and relapse. Thus, identifying the cells responsible for residual disease and leukemia re-growth is critical to better understanding how they are regulated. Here, we show that a knock-in reporter mouse for the stem cell gene Musashi 2 (Msi2) allows identification of leukemia stem cells in aggressive myeloid malignancies, and provides a strategy for defining their core dependencies. Specifically, we carry out a high throughput screen using Msi2-reporter blast crisis chronic myeloid leukemia (bcCML) and identify several adhesion molecules that are preferentially expressed in therapy resistant bcCML cells and play a key role in bcCML. In particular, we focus on syndecan-1, whose deletion triggers defects in bcCML growth and propagation and markedly improves survival of transplanted mice. Further, live imaging reveals that the spatiotemporal dynamics of leukemia cells are critically dependent on syndecan signaling, as loss of this signal impairs their localization, migration and dissemination to distant sites. Finally, at a molecular level, syndecan loss directly impairs integrin β7 function, suggesting that syndecan exerts its influence, at least in part, by coordinating integrin activity in bcCML. These data present a platform for delineating the biological underpinnings of leukemia stem cell function, and highlight the Sdc1-Itgβ7 signaling axis as a key regulatory control point for bcCML growth and dissemination.

Cleavage of proteoglycans, plasma proteins and the platelet-derived growth factor receptor in the hemorrhagic process induced by snake venom metalloproteinases

Envenoming by viperid snakes results in a complex pattern of tissue damage, including hemorrhage, which in severe cases may lead to permanent sequelae. Snake venom metalloproteinases (SVMPs) are main players in this pathogenesis, acting synergistically upon different mammalian proteomes. Hemorrhagic Factor 3 (HF3), a P-III class SVMP from Bothrops jararaca, induces severe local hemorrhage at pmol doses in a murine model. Our hypothesis is that in a complex scenario of tissue damage, HF3 triggers proteolytic cascades by acting on a partially known substrate repertoire. Here, we focused on the hypothesis that different proteoglycans, plasma proteins, and the platelet derived growth factor receptor (PDGFR) could be involved in the HF3-induced hemorrhagic process. In surface plasmon resonance assays, various proteoglycans were demonstrated to interact with HF3, and their incubation with HF3 showed degradation or limited proteolysis. Likewise, Western blot analysis showed in vivo degradation of biglycan, decorin, glypican, lumican and syndecan in the HF3-induced hemorrhagic process. Moreover, antithrombin III, complement components C3 and C4, factor II and plasminogen were cleaved in vitro by HF3. Notably, HF3 cleaved PDGFR (alpha and beta) and PDGF in vitro, while both receptor forms were detected as cleaved in vivo in the hemorrhagic process induced by HF3. These findings outline the multifactorial character of SVMP-induced tissue damage, including the transient activation of tissue proteinases, and underscore for the first time that endothelial glycocalyx proteoglycans and PDGFR are targets of SVMPs in the disruption of microvasculature integrity and generation of hemorrhage.

Disease Stage-Specific Pathogenicity of CD138 (Syndecan 1)-Expressing T Cells in Systemic Lupus Erythematosus

CD138 (syndecan 1), a member of the heparan-sulfate proteoglycan family, regulates diverse biological responses by interacting with chemokines, cytokines, growth factors, and adhesion molecules. Expression of CD138 has been detected on T cells from both healthy and sick mice mimicking systemic lupus erythematosus (SLE) disease. However, the characteristics and the role of CD138+ T cells in SLE pathogenesis remain largely unknown. We analyzed the lupus-prone MRL/Lpr mice and the control MRL/MpJ strain as well as the common laboratory strains Balb/c, and C57BL/6 for CD138-expression and found that only the MRL/Lpr strain harbored TCRβ+CD138+ cells in various organs. The frequency of TCRβ+CD138+ cells progressively expanded in MRL/Lpr mice with age and correlated with disease severity. Majority of the TCRβ+CD138+ cells were CD4 and CD8 double-negative and 20% were CD4. At least a portion of TCRβ+CD138+ cells originated from CD4+ cells because substantial number of CD4+TCRβ+CD138- cells expressed CD138 after in vitro cultivation. Compared to TCRβ+CD138- cells, TCRβ+CD138+ cells exhibited central memory (Tcm) phenotype with reduced ability to proliferate and produce the cytokines IFNγ and IL-17. When co-cultured with B cells, the ability of TCRβ+CD138+ cells to promote plasma cell formation and autoreactive antibody production was dependent on the presence of autoantigen, CD4 co-receptor expression and cell-to-cell contact. Surprisingly, adoptively transferred TCRβ+CD138+ T cells slowed down disease progression in young recipient MRL/Lpr mice but had the opposite effect when DNA was co-administered with TCRβ+CD138+ T cells or when TCRβ+CD138+ cells were transferred to older MRL/Lpr mice with established disease. Thus, CD138-expressing T cells with Tcm phenotype enhance disease progression in SLE by rapidly activating autoreactive B cells when self-antigens are exposed to the immune system.

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.

Mapping the Interactome of the Nuclear Heparan Sulfate Proteoglycan Syndecan-1 in Mesothelioma Cells

Syndecan-1 (SDC1) is a cell surface heparan sulfate proteoglycan (HSPG), which regulates various signaling pathways controlling the proliferation and migration of malignant mesothelioma and other types of cancer. We have previously shown that SDC1 can translocate to the nucleus in mesothelioma cells through a tubulin-dependent transport mechanism. However, the role of nuclear SDC1 is largely unknown. Here, we performed co-immunoprecipitation (Co-IP) of SDC1 in a mesothelioma cell line to identify SDC1 interacting proteins. The precipitates contained a large number of proteins, indicating the recovery of protein networks. Proteomic analysis with a focus on nuclear proteins revealed an association with pathways related to cell proliferation and RNA synthesis, splicing and transport. In support of this, the top RNA splicing candidates were verified to interact with SDC1 by Co-IP and subsequent Western blot analysis. Further loss- and gain-of-function experiments showed that SDC1 influences RNA levels in mesothelioma cells. The results identify a proteomic map of SDC1 nuclear interactors in a mesothelioma cell line and suggest a previously unknown role for SDC1 in RNA biogenesis. The results should serve as a fundament for further studies to discover the role of nuclear SDC1 in normal and cancer cells of different origin.

Syndecan-4 is regulated by IL-1β in β-cells and human islets

Syndecans (SDC) are important multifunctional components of the extracellular matrix mainly described in endothelial cells. We studied the expression and regulation of SDC in cultured MIN6B1 cells and pancreatic islets. qRT-PCR revealed that syndecan-4 (SDC4) was the predominant isoform expressed in MIN6B1 cells and islets compared to other forms of SDC. Immunofluorescence in mouse and human pancreas sections revealed that SDC4 is mainly expressed in β-cells compared to other pancreatic cells. Exposure of MIN6B1 and human islets to IL-1β dose-dependently induced a rapid and transient expression of SDC4 while SRC and STAT3 inhibitors decreased this effect. Exposure of human islets to Il-1β caused an increase of SDC4 shedding, however treatment with STAT3 and SRC inhibitors inhibited this effect. These results indicate that SDC4 is upregulated by IL-1β through the SRC-STAT3 pathway and this pathway is also involved in SDC4 shedding in islets.

Adhesion and growth factor receptor crosstalk mechanisms controlling cell migration

Cell migration requires cells to sense and interpret an array of extracellular signals to precisely co-ordinate adhesion dynamics, local application of mechanical force, polarity signalling and cytoskeletal dynamics. Adhesion receptors and growth factor receptors (GFRs) exhibit functional and signalling characteristics that individually contribute to cell migration. Integrins transmit bidirectional mechanical forces and transduce long-range intracellular signals. GFRs are fast acting and highly sensitive signalling machines that initiate signalling cascades to co-ordinate global cellular processes. Syndecans are microenvironment sensors that regulate GTPases to control receptor trafficking, cytoskeletal remodelling and adhesion dynamics. However, an array of crosstalk mechanisms exists, which co-ordinate and integrate the functions of the different receptor families. Here we discuss the nature of adhesion receptor and GFR crosstalk mechanisms. The unifying theme is that efficient cell migration requires precise spatial and temporal co-ordination of receptor crosstalk. However, a higher order of complexity emerges; whereby multiple crosstalk mechanisms are integrated and subject to both positive and negative feedbacks. Exquisite and sensitive control of these mechanisms ensures that mechanical forces and pro-migratory signals are triggered in the right place and at the right time during cell migration. Finally, we discuss the challenges, and potential therapeutic benefits, associated with deciphering this complexity.

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

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