Sweet role of platelet endothelial cell adhesion molecule in understanding angiogenesis

Endothelial Glycocalyx of Peritubular Capillaries in Experimental Diabetic Nephropathy: A Target of ACE Inhibitor-Induced Kidney Microvascular Protection

Peritubular capillary rarefaction is a recurrent aspect of progressive nephropathies. We previously found that peritubular capillary density was reduced in BTBR ob/ob mice with type 2 diabetic nephropathy. In this model, we searched for abnormalities in the ultrastructure of peritubular capillaries, with a specific focus on the endothelial glycocalyx, and evaluated the impact of treatment with an angiotensin-converting enzyme inhibitor (ACEi). Mice were intracardially perfused with lanthanum to visualise the glycocalyx. Transmission electron microscopy analysis revealed endothelial cell abnormalities and basement membrane thickening in the peritubular capillaries of BTBR ob/ob mice compared to wild-type mice. Remodelling and focal loss of glycocalyx was observed in lanthanum-stained diabetic kidneys, associated with a reduction in glycocalyx components, including sialic acids, as detected through specific lectins. ACEi treatment preserved the endothelial glycocalyx and attenuated the ultrastructural abnormalities of peritubular capillaries. In diabetic mice, peritubular capillary damage was associated with an enhanced tubular expression of heparanase, which degrades heparan sulfate residues of the glycocalyx. Heparanase was also detected in renal interstitial macrophages that expressed tumor necrosis factor-α. All these abnormalities were mitigated by ACEi. Our findings suggest that, in experimental diabetic nephropathy, preserving the endothelial glycocalyx is important in order to protect peritubular capillaries from damage and loss.

Gemcitabine alters sialic acid binding of the glycocalyx and induces inflammatory cytokine production in cultured endothelial cells

Gemcitabine (GEM) is an anticancer drug inhibiting DNA synthesis. Glomerular thrombotic microangiopathy (TMA) has been reported as an adverse effect. However, the precise mechanism of GEM-induced endothelial injury remains unknown. Cultured human umbilical vein endothelial cells (HUVECs) in the confluent phase were exposed to GEM (5-100 μM) for 48 h and evaluated cell viability and morphology, lectin binding concerning sialic acid of endothelial glycocalyx (GCX), and immunofluorescent staining of platelet-endothelial cell adhesion molecule (PECAM) and vascular endothelial growth factor receptor 2 (VEGFR2). The mRNA expression of α2,6-sialyltransferase (ST6Gal1), sialidase (neuraminidase-1: NEU-1), and interleukin (IL)-1β and IL-6 was also evaluated. GEM exposure at 5 μM induced cellular shrinkage and intercellular dissociation, accompanied by slight attenuation of PECAM and VEGFR2 immunostaining, although cell viability was still preserved. At this concentration, lectin binding showed a reduction of terminal sialic acids in endothelial GCX, probably associated with reduced ST6Gal1 mRNA expression. IL-1β and IL-6 mRNA expression was significantly increased after GEM exposure. GEM reduced terminal sialic acids in endothelial GCX through mRNA suppression of ST6Gal1 and induced inflammatory cytokine production in HUVECs. This phenomenon could be associated with the mechanism of GEM-induced TMA.

A prominent environmental endocrine disruptor, 4-nonylphenol, promotes endometriosis development via plasmacytoid dendritic cells

Endometriosis is an estrogen-dependent chronic inflammatory disease and is associated etiologically with environmental endocrine disruptor (EED) exposure. 4-nonylphenol (NP), a widely found EED, has weak estrogenic activity and modulates plasmacytoid dendritic cell (pDC) function in vitro and in vivo. We aimed to elucidate the immunomodulatory effect of NP on the development of endometriosis, particularly focusing on pDCs. This study established a surgically induced endometriosis murine model (C57BL/6) under conditions of NP treatment that are relevant to the level and route of human exposure. Multi-parametric flow cytometry was used for analysis of infiltrated immune cell subsets in lesions. The results showed that NP exposure significantly promoted endometriotic lesion growth, survival and angiogenesis development of lesions as well as pDC accumulation in the lesions in mice. Adoptive transfer of NP-conditioned pDCs into mice significantly enhanced lesion development and local pDC infiltration, whereas NP-conditioned conventional dendritic cells did not affect lesion growth. In vitro functional analysis showed that NP-conditioned pDCs in lesions expressed high levels of CD36, a scavenger receptor and NP-conditioned splenic pDCs secreted an enhanced level of IL-10 in response to apoptotic cell recognition in a CD36-dependent manner. Furthermore, we observed that local treatment with blocking antibodies against IL-10 and CD36 on the day of surgery significantly inhibited lesion development. NP exposure also altered the estrous cycle in mice. The results suggest that chronic and low-dose exposure to NP enhances endometriotic lesion growth by altering pDC homeostasis and function. This study has important implications for understanding the environment-innate immunity interaction in human endometriosis.

Placental Glycoredox Dysregulation Associated with Disease Progression in an Animal Model of Superimposed Preeclampsia

Pregnancies carried by women with chronic hypertension are at increased risk of superimposed preeclampsia, but the placental pathways involved in disease progression remain poorly understood. In this study, we used the stroke-prone spontaneously hypertensive rat (SHRSP) model to investigate the placental mechanisms promoting superimposed preeclampsia, with focus on cellular stress and its influence on galectin-glycan circuits. Our analysis revealed that SHRSP placentas are characterized by a sustained activation of the cellular stress response, displaying significantly increased levels of markers of lipid peroxidation (i.e., thiobarbituric acid reactive substances (TBARS)) and protein nitration and defective antioxidant enzyme expression as early as gestation day 14 (which marks disease onset). Further, lectin profiling showed that such redox imbalance was associated with marked alterations of the placental glycocode, including a prominent decrease of core 1 O-glycan expression in trophoblasts and increased decidual levels of sialylation in SHRSP placentas. We also observed significant changes in the expression of galectins 1, 3 and 9 with pregnancy progression, highlighting the important role of the galectin signature as dynamic interpreters of placental microenvironmental challenges. Collectively, our findings uncover a new role for the glycoredox balance in the pathogenesis of superimposed preeclampsia representing a promising target for interventions in hypertensive disorders of pregnancy.

Plump endothelial cells integrated into pre-existing venules contribute to the formation of 'mother' and 'daughter' vessels in pyogenic granuloma: possible role of galectin-1, -3 and -8

INTRODUCTION

Pyogenic granuloma (PG) is a reactive inflammatory vascular lesion of the skin and mucous membranes, characterised by the presence of enlarged venules and seamed and seamless capillaries with plump endothelial cells (EC), and numerous macrophages. EC activation upregulates the synthesis of galectins and induces their translocation to the EC surface promoting angiogenesis and lymphangiogenesis, particularly galectin-1 (Gal-1), Gal-3 and Gal-8. However, the presence and distribution of Gal-1, -3 and -8, as well as their implications in the pathogenesis of PG, has not been considered.

MATERIALS AND METHODS

Eight biopsies from patients diagnosed with PG were selected. The presence of PECAM-1/CD31, IL-1β, VEGF-C, VEGFR-2, VEGFR-3, integrin β1, CD44, fibronectin and Gal-1, -3 and -8 was assessed by immunofluorescence staining using confocal laser scanning microscopy.

RESULTS AND DISCUSSION

Immunostaining revealed that these molecules were present in the enlarged venules with plump ECs, in some macrophages and other immune cells. We propose that macrophages release VEGF-A and VEGF-C inducing VEGFR-2/VEGFR-3 expression and activation, leading macrophages to transdifferentiate into plump ECs that might integrate into pre-existing venules, contributing to the formation of enlarged venules with transluminal bridges and capillaries. EC activation, induced by certain cytokines, has been shown to stimulate galectin expression and changes in the cellular localisation through association and activation of specific EC surface glycoproteins. Therefore, it is plausible that Gal-1, -3 and -8, acting in a concerted manner, could be mediating the transdifferentiation of macrophages into plump ECs and facilitating their migration and incorporation into the new vessels.

LAY SUMMARY

In this study, immunostaining of pyogenic granuloma (PG) tissue sections showed immunoreactivity for PECAM-1/CD31, IL-1β, VEGF-C, VEGFR-2 and VEGFR-3, and galectin-1, -3 and -8 in enlarged venules with plump endothelial cells (EC), as well as in some macrophages and other immune cells. Interestingly, enlarged and thin-walled transient vessels lined by PECAM-1/CD31 and VEGFR-2 immunopositive ECs that form from pre-existing normal venules in response to VEGF-A (called 'mother' vessels [MV]) and that undergo intraluminal bridging evolving into various types of capillaries (called 'daughter' vessels [DV]) have been observed in benign and malignant tumours, in physiological and pathological angiogenesis as well as in vascular malformations, suggesting an important role for VEGF-A and VEGFR-2 in such a process. However, it is not only the mechanisms by which the MVs evolve in different types of DVs that remains to be elucidated, but also whether the cells that form intraluminal bridges proceed from locally activated ECs or whether they are derived from bone marrow precursors or from resident macrophages.Given that the formation of homodimers by Gal-1 and Gal-8 and pentamers by Gal-3 to generate gal-glycan lattices at the cell surface and in the extracellular space has been shown, it is possible that in PG tissue Gal-1, -3 and -8, through their binding partners, form a supramolecular structure at the surface of ECs and plump ECs, macrophages and in the extracellular space that might be mediating the transdifferentiation of macrophages into plump ECs and facilitating the migration and incorporation of these cells into the pre-existing venules, thus contributing to the formation of MVs and DVs.

Congenital thrombocytopenia associated with GNE mutations in twin sisters: a case report and literature review

Background

Neonatal thrombocytopenia is common in preterm and term neonates admitted to neonatal intensive care units. The etiology behind neonatal thrombocytopenia is complex. Inherited thrombocytopenia is rare and usually results from genetic mutations.

Case presentation

Here we report a case of twins with severe inherited thrombocytopenia presented in the neonatal period who were shown to be compound heterozygotes for 2 UDP-N-acetylglucosamine 2-epimerase (GNE) gene mutations, c.1351C > T and c.1330G > T, of which c.1330G > T is a novel mutation.

Conclusion

These two GNE mutations may help in the diagnosis and management of thrombocytopenia diagnosed in neonates.

IL-10 from plasmacytoid dendritic cells promotes angiogenesis in the early stage of endometriosis

An elevated level of IL‐10 has been considered a critical factor for the development of endometriosis; however, its detailed mechanism and causal relationship remain unclear. This study explored the cellular source and angiogenic activity of local IL‐10 during the early stage of endometriosis. Using a surgical murine model, we found that localised treatment with exogenous recombinant IL‐10 on the day of surgery significantly enhanced endometriotic lesion growth and angiogenesis, whereas blocking local IL‐10 activity using mAbs significantly suppressed those effects. Adoptive transfer of Il10^+/+ plasmacytoid dendritic cells into mice significantly enhanced lesion development, whereas Il10^−/− plasmacytoid dendritic cells significantly inhibited lesion development. Furthermore, in vitro angiogenesis analyses demonstrated that the IL‐10 and IL‐10 receptor pathway stimulated the migratory and tube formation ability of HUVECs as well as ectopic endometrial mesenchymal stem cells through, at least in part, a VEGF‐dependent pathway. We also found that recombinant IL‐10 directly stimulated angiogenesis, based on a Matrigel plug assay as well as a zebrafish model. Pathological results from human endometrioma tissues showed the increased infiltration of CD123⁺ plasmacytoid dendritic cells and higher percentages of cells that express the IL‐10 receptor and CD31 as compared with the corresponding normal counterparts. Taken together, these results show that IL‐10 secreted from local plasmacytoid dendritic cells promotes endometriosis development through pathological angiogenesis during the early disease stage. This study provides a scientific basis for a potential therapeutic strategy targeting the IL‐10—IL‐10 receptor pathway in the endometriotic milieu. © 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Glycosylation in the Tumor Microenvironment: Implications for Tumor Angiogenesis and Metastasis

Just as oncogene activation and tumor suppressor loss are hallmarks of tumor development, emerging evidence indicates that tumor microenvironment-mediated changes in glycosylation play a crucial functional role in tumor progression and metastasis. Hypoxia and inflammatory events regulate protein glycosylation in tumor cells and associated stromal cells in the tumor microenvironment, which facilitates tumor progression and also modulates a patient's response to anti-cancer therapeutics. In this review, we highlight the impact of altered glycosylation on angiogenic signaling and endothelial cell adhesion, and the critical consequences of these changes in tumor behavior.

The effect of nacre extract on cord blood-derived endothelial progenitor cells: A natural stimulus to promote angiogenesis?

Angiogenesis is a critical parameter to consider for the development of tissue-engineered bone substitutes. The challenge is to promote sufficient vascularization in the bone substitute to prevent cell death and to allow its efficient integration. The capacity of nacre extract to restore the osteogenic activity of osteoarthritis osteoblasts has already been demonstrated. However, their angiogenic potential on endothelial progenitor cells (EPCs) was not yet explored. Therefore, the current study aimed at investigating if nacreous molecules affect EPC behavior. The gene and protein expression levels of endothelial cell (EC)-specific markers were determined in EPCs cultivated in presence of a nacre extract (ethanol soluble matrix [ESM] at two concentrations: 100 μg/mL and 200 μg/mL (respectively abbreviated ESM100 and ESM200)). Cell functionality was explored by proangiogenic factors production and in vitro tube formation assay. ESM200 increased the expression of some EC-specific genes. The in vitro tube formation assay demonstrated that ESM200 stimulated tubulogenesis affecting angiogenic parameters. We demonstrated that a stimulation with 200 μg/mL of ESM increased angiogenesis key elements. This in vitro study strongly highlights the proangiogenic effect of ESM. Due to its osteogenic properties, previously demonstrated, ESM could constitute the key element to develop an ideal prevascularized bone substitute. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2019.

Glycosylation controls cooperative PECAM-VEGFR2-β3 integrin functions at the endothelial surface for tumor angiogenesis

Most of the angiogenesis inhibitors clinically used in cancer treatment target the vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) pathway. However, the current strategies for treating angiogenesis have limited efficacy. The issue of how to treat angiogenesis and endothelial dysfunction in cancer remains a matter of substantial debate. Here we demonstrate a glycosylation-dependent regulatory mechanism for tumor angiogenesis. St6gal1^-/- mice, lacking the α2,6-sialylation enzyme, were shown to exhibit impaired tumor angiogenesis through enhanced endothelial apoptosis. In a previous study, St6gal1^-/- endothelial cells exhibited a reduction in the cell surface residency of platelet endothelial cell adhesion molecule (PECAM). In this study, we found that cooperative functionality of PECAM-VEGFR2-integrin β3 was disturbed in St6gal1^-/- mice. First, cell surface PECAM-VEGFR2 complexes were lost, and both VEGFR2 internalization and the VEGFR-dependent signaling pathway were enhanced. Second, enhanced anoikis was observed, suggesting that the absence of α2,6-sialic acid leads to dysregulated integrin signaling. Notably, ectopic expression of PECAM increased cell surface integrin-β3, indicating that the reduction of cell surface integrin-β3 involves loss-of-endothelial PECAM. The results suggest that the cell surface stability of these glycoproteins is significantly reduced by the lack of α2,6-sialic acid, leading to abnormal signal transduction. The present findings highlight that α2,6-sialylation is critically involved in endothelial survival by controlling the cell surface stability and signal transduction of angiogenic molecules, and could be a novel target for anti-angiogenesis therapy.

The relationship of plasma decoy receptor 3 and coronary collateral circulation in patients with coronary artery disease

OBJECTIVE

Previously, decoy receptor 3 (DcR3) was found to be a potential angiogenetic factor, while the relationship of DcR3 with coronary collateral circulation formation has not been investigated. In this study, we aimed to investigate whether plasma decoy receptor 3 levels was associated with CCC formation and evaluate its predictive power for CCC status in patients with coronary artery disease.

METHODS

Among patients who underwent coronary angiography with coronary artery disease and had a stenosis of ≥90% were included in our study. Collateral degree was graded according to Rentrope Cohen classification. Patients with grade 2 or 3 collateral degree were enrolled in good CCC group and patients with grade 0 or 1 collateral degree were enrolled in poor CCC group.

RESULTS

Plasma DcR3 level was significantly higher in good CCC group (328.00±230.82 vs 194.84±130.63ng/l, p<0.01) and positively correlated with Rentrope grade (p<0.01). In addition, plasma DcR3 was also positively correlated with VEGF-A. Both ROC (receiver operating characteristic curve) and multinomial logistical regression analysis showed that plasma DcR3 displayed potent predictive power for CCC status.

CONCLUSIONS

Higher plasma DcR3 level was related to better CCC formation and displayed potent predictive power for CCC status.

Galectin-3 interacts with the cell-surface glycoprotein CD146 (MCAM, MUC18) and induces secretion of metastasis-promoting cytokines from vascular endothelial cells

The galactoside-binding protein galectin-3 is increasingly recognized as an important player in cancer development, progression, and metastasis via its interactions with various galactoside-terminated glycans. We have shown previously that circulating galectin-3, which is increased up to 30-fold in cancer patients, promotes blood-borne metastasis in an animal cancer model. This effect is partly attributable to the interaction of galectin-3 with unknown receptor(s) on vascular endothelial cells and causes endothelial secretion of several metastasis-promoting cytokines. Here we sought to identify the galectin-3-binding molecule(s) on the endothelial cell surface responsible for the galectin-3-mediated cytokine secretion. Using two different galectin-3 affinity purification processes, we extracted four cell membrane glycoproteins, CD146/melanoma cell adhesion molecule (MCAM)/MUC18, CD31/platelet endothelial cell adhesion molecule-1 (PECAM-1), CD144/VE-cadherin, and CD106/Endoglin, from vascular endothelial cells. CD146 was the major galectin-3-binding ligand and strongly co-localized with galectin-3 on endothelial cell surfaces treated with exogenous galectin-3. Moreover, galectin-3 bound to N-linked glycans on CD146 and induced CD146 dimerization and subsequent activation of AKT signaling. siRNA-mediated suppression of CD146 expression completely abolished the galectin-3-induced secretion of IL-6 and G-CSF cytokines from the endothelial cells. Thus, CD146/MCAM is the functional galectin-3-binding ligand on endothelial cell surfaces responsible for galectin-3-induced secretion of metastasis-promoting cytokines. We conclude that CD146/MCAM interactions with circulating galectin-3 may have an important influence on cancer progression and metastasis.

Biological roles of glycans

Simple and complex carbohydrates (glycans) have long been known to play major metabolic, structural and physical roles in biological systems. Targeted microbial binding to host glycans has also been studied for decades. But such biological roles can only explain some of the remarkable complexity and organismal diversity of glycans in nature. Reviewing the subject about two decades ago, one could find very few clear-cut instances of glycan-recognition-specific biological roles of glycans that were of intrinsic value to the organism expressing them. In striking contrast there is now a profusion of examples, such that this updated review cannot be comprehensive. Instead, a historical overview is presented, broad principles outlined and a few examples cited, representing diverse types of roles, mediated by various glycan classes, in different evolutionary lineages. What remains unchanged is the fact that while all theories regarding biological roles of glycans are supported by compelling evidence, exceptions to each can be found. In retrospect, this is not surprising. Complex and diverse glycans appear to be ubiquitous to all cells in nature, and essential to all life forms. Thus, >3 billion years of evolution consistently generated organisms that use these molecules for many key biological roles, even while sometimes coopting them for minor functions. In this respect, glycans are no different from other major macromolecular building blocks of life (nucleic acids, proteins and lipids), simply more rapidly evolving and complex. It is time for the diverse functional roles of glycans to be fully incorporated into the mainstream of biological sciences.

PECAM-1 Leu125Val (rs688) Polymorphism and Diabetic Nephropathy in Caucasians with Type 2 Diabetes Mellitus

Objectives. Platelet endothelial cell adhesion molecule-1 (PECAM-1) plays a key role in the transendothelial migration of circulating leukocytes during inflammation and in the maintenance of vascular endothelial integrity. We hypothesized that genetic variation in PECAM-1 gene could be associated with diabetic nephropathy (DN) and with the level of soluble PECAM-1 in Caucasians with type 2 diabetes mellitus (T2DM). Design and Methods. We analyzed the rs688 single nucleotide polymorphism of PECAM-1 gene C373G (Leu125Val) at exon 3, which encodes the first extracellular Ig-like domain that mediates the homophilic binding of PECAM-1, in 276 T2DM subjects with documented DN (cases) and 375 T2DM subjects without DN (controls), using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) strategy. Level of plasma soluble PECAM-1 (sPECAM-1) was measured by ELISA in a subpopulation of 120 diabetics with DN. Results. We found no association between the Leu125Val polymorphism and DN in subjects with T2DM. Likewise, the Leu125Val polymorphism was not associated with serum sPECAM-1 levels in a subpopulation of 120 diabetics with DN. Conclusion. The Leu125Val polymorphism of PECAM-1 and the level of sPECAM-1 are not associated with DN in T2DM subjects of Slovenian origin.

VEGF-A/VEGFR2 signaling network in endothelial cells relevant to angiogenesis

Vascular endothelial growth factor-A (VEGF-A) is essential for endothelial cell functions associated with angiogenesis. Signal transduction networks initiated by VEGFA/VEGFR2, the most prominent ligand-receptor complex in the VEGF system, leads to endothelial cell proliferation, migration, survival and new vessel formation involved in angiogenesis. Considering its biomedical importance, we have developed the first comprehensive map of endothelial cell-specific signaling events of VEGFA/VEGFR2 system pertaining to angiogenesis. Screening over 20,000 published research articles and following the post-translational modification (PTM) and site specificity of VEGFR2, we have documented 240 proteins and their diverse PTM-dependent reactions involved in VEGFA/VEGFR2 signal transduction. From the ligand-receptor complex, this map has been extended to the level of major transcriptionally regulated genes for which the signaling cascades leading to their transcription factors are reported. We believe that this map would serve as a novel platform for reference, integration, and representation and more significantly, the progressive analysis of dynamic features of VEGF signaling in endothelial cells including their cross-talks with other ligand-receptor systems involved in angiogenesis.

Different Sialoside Epitopes on Collagen Film Surfaces Direct Mesenchymal Stem Cell Fate

3'-Sialyllactose and 6'-sialyllactose have been covalently linked to collagen films. Preliminary in vitro study on the behavior of mesenchymal stem cells (MSCs) in terms of cell viability, proliferation and induction of osteogenic and chondrogenic related genes has been performed. Results indicate that sialoside epitopes on collagen surface represent a suitable support for MSCs adhesion and cell proliferation, moreover, the neoglycosylation provide MSCs with different and specific stimuli, saccharide-type depending, in term of expression of osteogenic and chondrogenic related genes. In particular, 3'-sialyllactose significantly upregulate the expression of RUNX2 and ALP, well-known markers of osteogenesis, whereas 6'-sialyllactose up-regulate the expression of chondrocyte marker ACAN. Because no osteogenic or chondrogenic supplements in culture media were added, the inductive effect in terms of increased gene expression has to be ascribed uniquely to collagen surface functionalization. These results support the promising role of sialosides in the regulation of stem cells fate and open brilliant perspective for the future use of the presented approach toward osteochondral tissue engineering applications.