Endothelial sphingosine kinase/SPNS2 axis is critical for vessel-like formation by human mesoangioblasts

Microbiota-derived imidazole propionate inhibits type 2 diabetic skin wound healing by targeting SPNS2-mediated S1P transport

Imidazole propionate (ImP) is a recently discovered metabolite of T2DM-related gut microbiota. The effect of ImP on T2DM wound healing has not been studied yet. In this research, the changes of ImP-producing bacteria on the skin are firstly evaluated. 16sRNA sequencing results showed that the abundance of ImP-producing bacteria-Streptococcus in the intestine and skin of T2DM mice is significantly increased. Animal experiments show that ImP can inhibit the process of wound healing and inhibit the formation of blood vessels in the process of wound healing. Molecular mechanism research results show that ImP can inhibit S1P secretion mediated by SPNS2, and inhibit the activation of Rho signaling pathway, thereby affecting the angiogenesis process of HUVEC cells. This work also provides a potential drug HMPA that promotes T2DM wound healing.

Sphingosine-1-phosphate in mitochondrial function and metabolic diseases

Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid metabolite. The past decade has witnessed exponential growth in the field of S1P research, partly attributed to drugs targeting its receptors or kinases. Accumulating evidence indicates that changes in the S1P axis (i.e., S1P production, transport, and receptors) may modify metabolism and eventually mediate metabolic diseases. Dysfunction of the mitochondria on a master monitor of cellular metabolism is considered the leading cause of metabolic diseases, with aberrations typically induced by abnormal biogenesis, respiratory chain complex disorders, reactive oxygen species overproduction, calcium deposition, and mitophagy impairment. Accordingly, we discuss decades of investigation into changes in the S1P axis and how it controls mitochondrial function. Furthermore, we summarize recent scientific advances in disorders associated with the S1P axis and their involvement in the pathogenesis of metabolic diseases in humans, including type 2 diabetes mellitus and cardiovascular disease, from the perspective of mitochondrial function. Finally, we review potential challenges and prospects for S1P axis application to the regulation of mitochondrial function and metabolic diseases; these data may provide theoretical guidance for the treatment of metabolic diseases.

S1P Signalling Axis Is Necessary for Adiponectin-Directed Regulation of Electrophysiological Properties and Oxidative Metabolism in C2C12 Myotubes

Background: Adiponectin (Adn), released by adipocytes and other cell types such as skeletal muscle, has insulin-sensitizing and anti-inflammatory properties. Sphingosine 1-phosphate (S1P) is reported to act as effector of diverse biological actions of Adn in different tissues. S1P is a bioactive sphingolipid synthesized by the phosphorylation of sphingosine catalyzed by sphingosine kinase (SK) 1 and 2. Consolidated findings support the key role of S1P in the biology of skeletal muscle. Methods and Results: Here we provide experimental evidence that S1P signalling is modulated by globular Adn treatment being able to increase the phosphorylation of SK1/2 as well as the mRNA expression levels of S1P₄ in C2C12 myotubes. These findings were confirmed by LC-MS/MS that showed an increase of S1P levels after Adn treatment. Notably, the involvement of S1P axis in Adn action was highlighted since, when SK1 and 2 were inhibited by PF543 and ABC294640 inhibitors, respectively, not only the electrophysiological changes but also the increase of oxygen consumption and of aminoacid levels induced by the hormone, were significantly inhibited. Conclusion: Altogether, these findings show that S1P biosynthesis is necessary for the electrophysiological properties and oxidative metabolism of Adn in skeletal muscle cells.

Uncovering the 'sphinx' of sphingosine 1-phosphate signalling: from cellular events to organ morphogenesis

Sphingosine 1-phosphate (S1P) is a bioactive sphingolipid metabolite, functioning as a signalling molecule in diverse cellular processes. Over the past few decades, studies of S1P signalling have revealed that the physiological activity of S1P largely depends on S1P metabolizing enzymes, transporters and receptors on the plasma membrane, as well as on the intracellular proteins that S1P binds directly to. In addition to its roles in cancer signalling, immunity and inflammation, a large body of evidence has identified a close link of S1P signalling with organ morphogenesis. Here we discuss the vital role of S1P signalling in orchestrating various cellular events during organ morphogenesis through analysing each component along the extracellular and intracellular S1P signalling axes. For each component, we review advances in our understanding of S1P signalling and function from the upstream regulators to the downstream effectors and from cellular behaviours to tissue organization, primarily in the context of morphogenetic mechanisms. S1P-mediated vesicular trafficking is also discussed as a function independent of its signalling function. A picture emerges that reveals a multifaceted role of S1P-dependent pathways in the development and maintenance of organ structure and function.

Synthesis and characterization of modified magnetic nanoparticles as theranostic agents: in vitro safety assessment in healthy cells

Over the past few decades nanotechnology has paved its way into cancer treatment procedures with the use of nanoparticles (NPs) for contrast media and therapeutic agents. Iron based NPs are the most investigated since they can be used for drug delivery, imaging and when magnetically activate employed as local heat sources in cancer hyperthermia. In this work, was performed synthesis, characterization and biological evaluation of different types of iron oxide nanoparticles (mNPs'), as promising material for tumor hyperthermia. The surface of mNPs' has modified with inorganic stabilizing agents to particularly improve characteristics such as their magnetic properties, colloidal stability and biocompatibility. The successful coating of mNPs' was confirmed by morphological and structural characterization by transmission electron microscopy (TEM) and Fourier-Transform Infra-Red spectroscopy (FT-IR), while their hydrodynamic diameter was studied by using Dynamic light scattering (DLS). X-ray Diffraction (XRD) proved that the crystallite phase of mNPs' is the same with the pattern of magnetite. Superparamagnetic behavior and mNPs' response under the application of alternating magnetic field (AMF) were also thoroughly investigated and showed good heating efficiency in magnetic hyperthermia experiments. The contrast ability in magnetic resonance imaging (MRI) is also discussed indicating that mNPs are negative MRI contrast types. Nonetheless the effects of mNPs on cell viability was performed by MTT on human keratinocytes, human embryonic kidney cells, endothelial cells and by hemolytic assay on erythrocytes. In healthy keratinocytes wound healing assay in different time intervals was performed, assessing both the cell migration and wound closure. Endothelial cells have also been studied in functional activity performing capillary morphogenesis. In vitro studies showed that mNPs are safely taken by the healthy cells and do not interfere with the biological processes such as cell migration and motility.

Spinster homolog 2 in cancers, its functions and mechanisms

Spinster homolog 2 (SPNS2) is a multi-transmembrane transporter, widely located in the cell membrane and organelle membranes. It transports sphingosine-1-phosphate (S1P) into the extracellular space and the circulatory system, thus alters the concentration and the distribution of S1P, sphingosine-1-phosphate receptor (S1PRs) and S1P related enzymes, meaning that it exerts its functions via S1P signaling pathways. Studies also show that ectopic SPNS2 mediates parts of the physiological process of the cells. As of now, SPNS2 has been reported to participate in physiological processes such as angiogenesis, embryonic development, immune response and metabolisms. It is also associated with the transformation from inflammation to cancer as well as the proliferation and metastasis of cancer cells. In this review, we summarize the functions and the mechanisms of SPNS2 in the pathogenesis of cancer to provide new insights for the diagnosis and the treatments of cancer.

Mechanisms of Endothelial Regeneration and Vascular Repair and Their Application to Regenerative Medicine

Endothelial barrier integrity is required for maintaining vascular homeostasis and fluid balance between the circulation and surrounding tissues and for preventing the development of vascular disease. Despite comprehensive understanding of the molecular mechanisms and signaling pathways that mediate endothelial injury, the regulatory mechanisms responsible for endothelial regeneration and vascular repair are incompletely understood and constitute an emerging area of research. Endogenous and exogenous reparative mechanisms serve to reverse vascular damage and restore endothelial barrier function through regeneration of a functional endothelium and re-engagement of endothelial junctions. In this review, mechanisms that contribute to endothelial regeneration and vascular repair are described. Targeting these mechanisms has the potential to improve outcome in diseases that are characterized by vascular injury, such as atherosclerosis, restenosis, peripheral vascular disease, sepsis, and acute respiratory distress syndrome. Future studies to further improve current understanding of the mechanisms that control endothelial regeneration and vascular repair are also highlighted.

Sphingolipids in neurodegeneration (with focus on ceramide and S1P)

For many decades, research on sphingolipids associated with neurodegenerative disease focused on alterations in glycosphingolipids, particularly glycosylceramides (cerebrosides), sulfatides, and gangliosides. This seemed quite natural since many of these glycolipids are constituents of myelin and accumulated in lipid storage diseases (sphingolipidoses) resulting from enzyme deficiencies in glycolipid metabolism. With the advent of recognizing ceramide and its derivative, sphingosine-1-phosphate (S1P), as key players in lipid cell signaling and regulation of cell death and survival, research focus shifted toward these two sphingolipids. Ceramide and S1P are invoked in a plethora of cell biological processes participating in neurodegeneration such as ER stress, autophagy, dysregulation of protein and lipid transport, exosome secretion and neurotoxic protein spreading, neuroinflammation, and mitochondrial dysfunction. Hence, it is timely to discuss various functions of ceramide and S1P in neurodegenerative disease and to define sphingolipid metabolism and cell signaling pathways as potential targets for therapy.

A bidirectional crosstalk between glioblastoma and brain endothelial cells potentiates the angiogenic and proliferative signaling of sphingosine-1-phosphate in the glioblastoma microenvironment

Glioblastoma is one of the most malignant, angiogenic, and incurable tumors in humans. The aberrant communication between glioblastoma cells and tumor microenvironment represents one of the major factors regulating glioblastoma malignancy and angiogenic properties. Emerging evidence implicates sphingosine-1-phosphate signaling in the pathobiology of glioblastoma and angiogenesis, but its role in glioblastoma-endothelial crosstalk remains largely unknown. In this study, we sought to determine whether the crosstalk between glioblastoma cells and brain endothelial cells regulates sphingosine-1-phosphate signaling in the tumor microenvironment. Using human glioblastoma and brain endothelial cell lines, as well as primary brain endothelial cells derived from human glioblastoma, we report that glioblastoma-co-culture promotes the expression, activity, and plasma membrane enrichment of sphingosine kinase 2 in brain endothelial cells, leading to increased cellular level of sphingosine-1-phosphate, and significant potentiation of its secretion. In turn, extracellular sphingosine-1-phosphate stimulates glioblastoma cell proliferation, and brain endothelial cells migration and angiogenesis. We also show that, after co-culture, glioblastoma cells exhibit enhanced expression of S1P₁ and S1P₃, the sphingosine-1-phosphate receptors that are of paramount importance for cell growth and invasivity. Collectively, our results envision glioblastoma-endothelial crosstalk as a multi-compartmental strategy to enforce pro-tumoral sphingosine-1-phosphate signaling in the glioblastoma microenvironment.

One pot environmental friendly synthesis of gold nanoparticles using Punica Granatum Juice: A novel antioxidant agent for future dermatological and cosmetic applications

HYPOTHESIS

The interesting properties of Gold Nanoparticles (AuNPs) make them attractive for different application fields such as cosmetology, medicine and clinical nanotechnologies. In this work a fast, easy and eco-friendly method for the AuNPs synthesis is proposed by using the Punica Granatum Juice (PGJ) with potential dermatological and cosmetic applications. The AuNPs antioxidant activity, due to the presence of phenols from the juice, and their use as booster for improving the Sun Protection Factor (SPF) in commercial sunscreen formulations, are thus expounded.

EXPERIMENTS

By using appropriate amounts of PGJ and HAuCl₄, under mild work conditions, AuNPs with a mean size of 100 ± 40 nm are observed and carefully characterized. Solution pH, temperature, and volume were also changed for optimizing the AuNPs formation and features. The antioxidant activity was studied, by evaluating the AuNP ability of scavenging the radical 2,2-diphenyl-1-picrylhydrazylhydrate (DPPH). This finding was confirmed performing special experiments focused on the reaction between AuNPs and H₂O₂, by using suitable probes, such as 4-thiothymidine (S⁴TdR) and Cytochrome-c (Cyt-c). The SPF value was also calculated.

FINDINGS

The synthetized AuNPs showed a surface plasmon in visible range at 577 nm and resulted stable for long time in aqueous medium, also changing the pH values in the range 2-12. The studied antioxidant activity, confirmed also by performing special experiments with suitable probes, demonstrated the high performance of AuNPs. The AuNP photostability under sun irradiation is also shown. The calculated SPF values were in the range 3-18, related to AuNPs concentration in the range 1.80 × 10^-12-1.00 × 10^-11 M. The same AuNPs concentrations were used for cellular experiments. Indeed, since the AuNPs-PGJ mediated will be potentially introduced by dermal contact, dermal fibroblasts (Human Dermal Fibroblasts, HDF) and Human Microvascular Endothelial Cells (HMVEC) were used to evaluate the possible effects of these nanoparticles as a preliminary step. The results indicated that an AuNP concentrations in the range 1.80 × 10^-12-3.60 × 10^-12 M could be adopted since they do not appeared cyctotoxic.

3D Imaging and Quantitative Analysis of Vascular Networks: A Comparison of Ultramicroscopy and Micro-Computed Tomography

Rationale: Classic histology is the gold standard for vascular network imaging and analysis. The method however is laborious and prone to artefacts. Here, the suitability of ultramicroscopy (UM) and micro-computed tomography (CT) was studied to establish potential alternatives to histology.

Methods: The vasculature of murine organs (kidney, heart and atherosclerotic carotid arteries) was visualized using conventional 2D microscopy, 3D light sheet ultramicroscopy (UM) and micro-CT. Moreover, spheroid-based human endothelial cell vessel formation in mice was quantified. Fluorescently labeled Isolectin GS-IB4 A647 was used for in vivo labeling of vasculature for UM analysis, and analyses were performed ex vivo after sample preparation. For CT imaging, animals were perfused postmortem with radiopaque contrast agent.

Results: Using UM imaging, 3D vascular network information could be obtained in samples of animals receiving in vivo injection of the fluorescently labeled Isolectin GS-IB4. Resolution was sufficient to measure single endothelial cell integration into capillaries in the spheroid-based matrigel plug assay. Because of the selective staining of the endothelium, imaging of larger vessels yielded less favorable results. Using micro-CT or even nano-CT, imaging of capillaries was impossible due to insufficient X-ray absorption and thus insufficient signal-to-noise ratio. Identification of lumen in murine arteries using micro-CT was in contrast superior to UM.

Conclusion: UM and micro-CT are two complementary techniques. Whereas UM is ideal for imaging and especially quantifying capillary networks and arterioles, larger vascular structures are easier and faster to quantify and visualize using micro-CT. 3D information of both techniques is superior to 2D histology. UM and micro-CT together may open a new field of clinical pathology diagnosis.

Expansion of Sphingosine Kinase and Sphingosine-1-Phosphate Receptor Function in Normal and Cancer Cells: From Membrane Restructuring to Mediation of Estrogen Signaling and Stem Cell Programming

Sphingolipids, sphingolipid metabolizing enzymes, and their receptors network are being recognized as part of the signaling mechanisms, which govern breast cancer cell growth, migration, and survival during chemotherapy treatment. Approximately 70% of breast cancers are estrogen receptor (ER) positive and, thus, rely on estrogen signaling. Estrogen activates an intracellular network composed of many cytoplasmic and nuclear mediators. Some estrogen effects can be mediated by sphingolipids. Estrogen activates sphingosine kinase 1 (SphK1) and amplifies the intracellular concentration of sphingosine-1-phosphate (S1P) in breast cancer cells during stimulation of proliferation and survival. Specifically, Estrogen activates S1P receptors (S1PR) and induces growth factor receptor transactivation. SphK, S1P, and S1PR expression are causally associated with endocrine resistance and progression to advanced tumor stages in ER-positive breast cancers in vivo. Recently, the network of SphK/S1PR was shown to promote the development of ER-negative cancers and breast cancer stem cells, as well as stimulating angiogenesis. Novel findings confirm and broaden our knowledge about the cross-talk between sphingolipids and estrogen network in normal and malignant cells. Current S1PRs therapeutic inhibition was indicated as a promising chemotherapy approach in non-responsive and advanced malignancies. Considering that sphingolipid signaling has a prominent role in terminally differentiated cells, the impact should be considered when designing specific SphK/S1PR inhibitors. This study analyzes the dynamic of the transformation of sphingolipid axis during a transition from normal to pathological condition on the level of the whole organism. The sphingolipid-based mediation and facilitation of global effects of estrogen were critically accented as a bridging mechanism that should be explored in cancer prevention.

Tumor-tropic endothelial colony forming cells (ECFCs) loaded with near-infrared sensitive Au nanoparticles: A "cellular stove" approach to the photoablation of melanoma

In the photothermal treatments (PTs) of tumor, the localization of a high number of near-infrared (NIR) absorbing gold nanoparticles in the tumor mass is still a challenging issue. Here, we propose a promising strategy to deliver therapeutic chitosan-coated gold nanoparticles to tumor cells as hidden cargo of Endothelial Colony Forming Cells (ECFCs) endowed with an innate tumor-tropism. Remarkably, ECFC gold enrichement doesn't affect cell viability and preserves the endothelial lineage characteristics such as capillary morphogenesis and cell migration. We demonstrate that heavily Au-doped ECFCs are able to efficiently warm up the tumor environment, and kill the cancer cells via hyperthermic heating both in vitro as well as in vivo. Thus, we show an excellent thermotransductive property of gold enriched ECFCs and their capability to kill melanoma cells at moderate NIR light intensities.

Control of inflammatory responses by ceramide, sphingosine 1-phosphate and ceramide 1-phosphate

Inflammation is a network of complex processes involving a variety of metabolic and signaling pathways aiming at healing and repairing damage tissue, or fighting infection. However, inflammation can be detrimental when it becomes out of control. Inflammatory mediators involve cytokines, bioactive lipids and lipid-derived metabolites. In particular, the simple sphingolipids ceramides, sphingosine 1-phosphate, and ceramide 1-phosphate have been widely implicated in inflammation. However, although ceramide 1-phosphate was first described as pro-inflammatory, recent studies show that it has anti-inflammatory properties when produced in specific cell types or tissues. The biological functions of ceramides and sphingosine 1-phosphate have been extensively studied. These sphingolipids have opposing effects with ceramides being potent inducers of cell cycle arrest and apoptosis, and sphingosine 1-phosphate promoting cell growth and survival. However, the biological actions of ceramide 1-phosphate have only been partially described. Ceramide 1-phosphate is mitogenic and anti-apoptotic, and more recently, it has been demonstrated to be key regulator of cell migration. Both sphingosine 1-phosphate and ceramide 1-phosphate are also implicated in tumor growth and dissemination. The present review highlights new aspects on the control of inflammation and cell migration by simple sphingolipids, with special emphasis to the role played by ceramide 1-phosphate in controlling these actions.

Trafficking and Functions of Bioactive Sphingolipids: Lessons from Cells and Model Membranes

Ceramide and sphingosine and their phosphorylated counterparts are recognized as "bioactive sphingolipids" and modulate membrane integrity, the activity of enzymes, or act as ligands of G protein-coupled receptors. The subcellular distribution of the bioactive sphingolipids is central to their function as the same lipid can mediate diametrically opposite effects depending on its location. To ensure that these lipids are present in the right amount and in the appropriate organelles, cells employ selective lipid transport and compartmentalize sphingolipid-metabolizing enzymes to characteristic subcellular sites. Our knowledge of key mechanisms involved in sphingolipid signaling and trafficking has increased substantially in the past decades-thanks to advances in biochemical and cell biological methods. In this review, we focus on the bioactive sphingolipids and discuss how the combination of studies in cells and in model membranes have contributed to our understanding of how they behave and function in living organisms.