Role of Globotriaosylceramide in Physiology and Pathology

The Stereochemical Outcome of Galactosylations Is Influenced by Both the Position and Electron-Withdrawing Power of Distal Acyl Protecting Groups

The stereodirecting effect of various distal benzoyl esters on the anomeric selectivity in galactopyranosylations was investigated. It was found that esters on O-6 of galactosyl donors of the phenyl thioglycoside type had a negligible influence on the anomeric selectivity. Instead, α-selective galactosylations were observed with 4-O-benzoyl, 3,4-di-O-benzoyl, and 4,6-di-O-benzoyl protected galactosyl donors, with the highly electron-withdrawing p-nitrobenzoyl (pNO2Bz) protecting group providing the most α-selective galactosylations. Furthermore, the α-selectivity was enhanced by replacing the thiophenyl aglycon functionality with the highly reactive cyclohexyl aglycon functionality. These findings enabled the successful synthesis of the biologically relevant α-d-Gal(1→4)Gal linkage. The obtained results do not suggest distal participation as a course for the observed anomeric selectivities.

Human sensory-like neuron surfaceome analysis

Acral and triggerable pain is a hallmark of diseases involving small nerve fiber impairment, yet the underlying cellular mechanisms remain elusive. A key role is attributed to pain-related proteins located within the neuronal plasma membrane of nociceptive neurons. To explore this, we employed human induced pluripotent stem cell-derived sensory-like neurons and enriched their surface proteins by biotinylation. Samples from three independent cell differentiations were analyzed via liquid chromatography tandem mass spectrometry. Detected proteins were categorized by cellular location and function, followed by generating an interaction network for deregulated surface proteins. Gene expression of selected proteins was quantified using real-time PCR. A comparative analysis was performed between a patient with Fabry disease (FD) and a healthy control, which we used as model system. We successfully extracted surfaceome proteins from human sensory-like neurons, revealing deregulation of 48 surface proteins in FD-derived neurons. Among the candidates with potential involvement in pain pathophysiology were CACNA2D3, GPM6A, EGFR, and ABCA7. Despite the lack of gene expression differences in these candidates, the interaction network indicated compromised neuronal network integrity. Our approach successfully enabled the extraction and comprehensive analysis of the surfaceome from human sensory-like neurons, establishing a novel methodological framework for investigating human sensory-like neuron biology and cellular disease mechanisms.

Divergent Chemoenzymatic Synthesis of Sulfated Ganglio-Oligosaccharides for Probing Ligand Requirements of Glycan Binding Proteins

Sulfoglycolipids are an important class of acidic glycosphingolipids that have been implicated in a multitude of biological processes. Little is known about the interactome of sulfated gangliosides, and it is not well understood how a possible interplay between sialylation and sulfation influences molecular recognition. Here, we describe a chemoenzymatic strategy that readily provided a panel of twenty-one sulfated and sialylated ganglio-oligosaccharides. It is based on the chemical synthesis of a core tetra- and pentasaccharide that are equipped with the orthogonal protecting groups allyloxycarbonate (Alloc), levulinate ester (Lev) and t-butyldimethylsilyl ether (TBS). Selective removal of one or more protecting groups followed by sulfation of the resulting alcohol(s) and deprotecting gave several ganglio-oligosaccharides. Compound lacking an internal sialic acid could be prepared by exposing several derivatives to a sialidase. Compounds having an unmodified terminal galactoside could enzymatically be sialylated to give hybrid structures, which could be further extended to provide 2,8-sialosides. The synthetic glycans were printed as a microarray which was used to examine ligand requirements of a series of glycan-binding proteins including antibodies, toxins, galectins and siglecs. It was found that sulfation regulates protein binding in complex manners and in general sulfation and sialylation of C-3 of the terminal Gal influences protein binding in different ways.

Sphingolipid metabolites involved in the pathogenesis of atherosclerosis: perspectives on sphingolipids in atherosclerosis

Atherosclerosis, with its complex pathogenesis, is a leading underlying cause of many cardiovascular diseases, which are increasingly prevalent in the population. Sphingolipids play an important role in the development of atherosclerosis. Key metabolites and enzymes in sphingolipid metabolism influence the pathogenesis of atherosclerosis in a variety of ways, including inflammatory responses and oxidative stress. Thus, an investigation of sphingolipid metabolism-related metabolites and key enzymes may provide novel insights and treatment targets for atherosclerosis. This review discusses various mechanisms and research progress on the relationship between various sphingolipid metabolites, related enzymes, and atherosclerosis. Finally, we look into the future research direction of phytosphingolipids.

[Thrombopenia and hemolytic anemia in acute and emergency medicine : Detailed view at thrombotic microangiopathies]

Recognizing anemia and thrombpenia in acute and emergency medicine is easy. Acute (microangiopathic hemolytic) anemia and thrombopenia can be a sign of thrombotic microangiopathy (TMA). TMA syndromes are potentially life-threatening diseases. Diagnosing a TMA syndrome, causal differentiation and treatment require specialist knowledge that is not always available in acute and emergency medicine. Many differential diagnoses and examinations are usually necessary to make a correct diagnosis. Therefore, a standardized diagnostic algorithm is helpful for early diagnosis and treatment initiation.

Sugar Highs: Recent Notable Breakthroughs in Glycobiology

Glycosylation is biochemically complex and functionally critical to a wide range of processes and disease states, making it a vibrant area of contemporary research. Here, we highlight a selection of notable recent advances in the glycobiology of SARS-CoV-2 infection and immunity, cancer biology and immunotherapy, and newly discovered glycosylated RNAs. Together, these studies illustrate the significance of glycosylation in normal biology and the great promise of manipulating glycosylation for therapeutic benefit in disease.

High-fat and high-carbohydrate diets worsen the mouse brain susceptibility to damage produced by enterohemorrhagic Escherichia coli Shiga toxin 2

Background

Nutrition quality could be one of the reasons why, in the face of a Shiga toxin-producing enterohemorrhagic Escherichia coli outbreak, some patients experience more profound deleterious effects than others, including unfortunate deaths. Thus, the aim of this study was to determine whether high-fat and/or high-carbohydrate diets could negatively modulate the deleterious action of Shiga toxin 2 on ventral anterior and ventral lateral thalamic nuclei and the internal capsule, the neurological centers responsible for motor activity.

Methods

Mice were fed a regular, high-fat, high-carbohydrate diet or a combination of both previous to the intravenous administration of Shiga toxin 2 or vehicle. Four days after intravenous administration, mice were subjected to behavioral tests and then sacrificed for histological and immunofluorescence assays to determine alterations in the neurovascular unit at the cellular and functional levels. Statistical analysis was performed using one-way analysis of variance followed by Bonferroni post hoc test. The criterion for significance was p = 0.0001 for all experiments.

Results

The high-fat and the high-carbohydrate diets significantly heightened the deleterious effect of Stx2, while the combination of both diets yielded the worst results, including endothelial glycocalyx and oligodendrocyte alterations, astrocyte and microglial reactivity, neurodegeneration, and motor and sensitivity impairment.

Conclusions

In view of the results presented here, poor nutrition could negatively influence patients affected by Stx2 at a neurological level. Systemic effects, however, cannot be ruled out.

Complement System and Adhesion Molecule Skirmishes in Fabry Disease: Insights into Pathogenesis and Disease Mechanisms

Fabry disease is a rare X-linked lysosomal storage disorder caused by mutations in the galactosidase alpha (GLA) gene, resulting in the accumulation of globotriaosylceramide (Gb3) and its deacetylated form, globotriaosylsphingosine (Lyso-Gb3) in various tissues and fluids throughout the body. This pathological accumulation triggers a cascade of processes involving immune dysregulation and complement system activation. Elevated levels of complement 3a (C3a), C5a, and their precursor C3 are observed in the plasma, serum, and tissues of patients with Fabry disease, correlating with significant endothelial cell abnormalities and vascular dysfunction. This review elucidates how the complement system, particularly through the activation of C3a and C5a, exacerbates disease pathology. The activation of these pathways leads to the upregulation of adhesion molecules, including vascular cell adhesion molecule 1 (VCAM1), intercellular adhesion molecule 1 (ICAM1), platelet and endothelial cell adhesion molecule 1 (PECAM1), and complement receptor 3 (CR3) on leukocytes and endothelial cells. This upregulation promotes the excessive recruitment of leukocytes, which in turn exacerbates disease pathology. Targeting complement components C3a, C5a, or their respective receptors, C3aR (C3a receptor) and C5aR1 (C5a receptor 1), could potentially reduce inflammation, mitigate tissue damage, and improve clinical outcomes for individuals with Fabry disease.

Lipidomic Profiling of Kidney Cortical Tubule Segments Identifies Lipotypes with Physiological Implications

A detailed knowledge of the lipid composition of components of nephrons is crucial for understanding physiological processes and the development of kidney diseases. However, the lipidomic composition of kidney tubular segments is unknown. We manually isolated the proximal convoluted tubule (PCT), the cortical thick ascending limb of Henle's loop, and the cortical collecting duct from 5 lean and obese mice and subjected the samples to shotgun lipidomics analysis by high-resolution mass spectrometry acquisition. Across all samples, more than 500 lipid species were identified, quantified, and compared. We observed significant compositional differences among the 3 tubular segments, which serve as true signatures. These intrinsic lipidomic features are associated with a distinct proteomic program that regulates highly specific physiological functions. The distinctive lipidomic features of each of the 3 segments are mostly based on the relative composition of neutral lipids, long-chain polyunsaturated fatty acids, sphingolipids, and ether phospholipids. These features support the hypothesis of a lipotype assigned to specific tubular segments. Obesity profoundly impacts the lipotype of PCT. In conclusion, we present a comprehensive lipidomic analysis of 3 cortical segments of mouse kidney tubules. This valuable resource provides unparalleled detail that enhances our understanding of tubular physiology and the potential impact of pathological conditions.

Tracing the lipidome in inborn errors of metabolism

Inborn errors of metabolism (IEM) represent a heterogeneous group of more than 1800 rare disorders, many of which are causing significant childhood morbidity and mortality. More than 100 IEM are linked to dyslipidaemia, but yet our knowledge in connecting genetic information with lipidomic data is limited. Stable isotope tracing studies of the lipid metabolism (STL) provide insights on the dynamic of cellular lipid processes and could thereby facilitate the delineation of underlying metabolic (patho)mechanisms. This mini-review focuses on principles as well as technical limitations of STL and describes potential clinical applications by discussing recently published STL focusing on IEM.

Fabry Disease: Cardiac Implications and Molecular Mechanisms

PURPOSE OF REVIEW

This review explores the interplay among metabolic dysfunction, oxidative stress, inflammation, and fibrosis in Fabry disease, focusing on their potential implications for cardiac involvement. We aim to discuss the biochemical processes that operate in parallel to sphingolipid accumulation and contribute to disease pathogenesis, emphasizing the importance of a comprehensive understanding of these processes.

RECENT FINDINGS

Beyond sphingolipid accumulation, emerging studies have revealed that mitochondrial dysfunction, oxidative stress, and chronic inflammation could be significant contributors to Fabry disease and cardiac involvement. These factors promote cardiac remodeling and fibrosis and may predispose Fabry patients to conduction disturbances, ventricular arrhythmias, and heart failure. While current treatments, such as enzyme replacement therapy and pharmacological chaperones, address disease progression and symptoms, their effectiveness is limited. Our review uncovers the potential relationships among metabolic disturbances, oxidative stress, inflammation, and fibrosis in Fabry disease-related cardiac complications. Current findings suggest that beyond sphingolipid accumulation, other mechanisms may significantly contribute to disease pathogenesis. This prompts the exploration of innovative therapeutic strategies and underscores the importance of a holistic approach to understanding and managing Fabry disease.

Translocation across a human enteroid monolayer by zoonotic Streptococcus suis correlates with the presence of Gb3-positive cells

Streptococcus suis is a zoonotic pathogen that can cause meningitis and septicaemia. The consumption of undercooked pig products is an important risk factor for zoonotic infections, suggesting an oral route of infection. In a human enteroid model, we show that the zoonotic CC1 genotype has a 40% higher translocation frequency than the non-zoonotic CC16 genotype. Translocation occurred without increasing the permeability or disrupting the adherens junctions and tight junctions of the epithelial monolayer. The translocation of zoonotic S. suis was correlated with the presence of Gb3-positive cells, a human glycolipid receptor found on Paneth cells and targeted by multiple enteric pathogens. The virulence factors Streptococcal adhesin Protein and suilysin, known to interact with Gb3, were not essential for translocation in our epithelial model. Thus, the ability to translocate across an enteroid monolayer correlates with S. suis core genome composition and the presence of Gb3-positive cells in the intestinal epithelium.

Identification of GB3 as a Novel Biomarker of Tumor-Derived Vasculature in Neuroblastoma Using a Stiffness-Based Model

Neuroblastoma (NB) is a childhood cancer in sympathetic nervous system cells. NB exhibits cellular heterogeneity, with adrenergic and mesenchymal states displaying distinct tumorigenic potentials. NB is highly vascularized, and blood vessels can form through various mechanisms, including endothelial transdifferentiation, leading to the development of tumor-derived endothelial cells (TECs) associated with chemoresistance. We lack specific biomarkers for TECs. Therefore, identifying new TEC biomarkers is vital for effective NB therapies. A stiffness-based platform simulating human arterial and venous stiffness was developed to study NB TECs in vitro. Adrenergic cells cultured on arterial-like stiffness transdifferentiated into TECs, while mesenchymal state cells did not. The TECs derived from adrenergic cells served as a model to explore new biomarkers, with a particular focus on GB3, a glycosphingolipid receptor implicated in angiogenesis, metastasis, and drug resistance. Notably, the TECs unequivocally expressed GB3, validating its novelty as a marker. To explore targeted therapeutic interventions, nanoparticles functionalized with the non-toxic subunit B of the Shiga toxin were generated, because they demonstrated a robust affinity for GB3-positive cells. Our results demonstrate the value of the stiffness-based platform as a predictive tool for assessing NB aggressiveness, the discovery of new biomarkers, and the evaluation of the effectiveness of targeted therapeutic strategies.

In vitro characterization of cells derived from a patient with the GLA variant c.376A>G (p.S126G) highlights a non-pathogenic role in Fabry disease

Fabry disease (FD) is a life-limiting disorder characterized by intracellular globotriaosylceramide (Gb3) accumulations. The underlying α-galactosidase A (α-GAL A) deficiency is caused by variants in the gene GLA. Variants of unknown significance (VUS) are frequently found in GLA and challenge clinical management. Here, we investigated a 49-year old man with cryptogenic lacunar cerebral stroke and the chance finding of the VUS S126G, who was sent to our center for diagnosis and initiation of a costly and life-long FD-specific treatment. We combined clinical examination with in vitro investigations of dermal fibroblasts (HDF), induced pluripotent stem cells (iPSC), and iPSC-derived sensory neurons. We analyzed α-GAL A activity in iPSC, Gb3 accumulation in all three cell types, and action potential firing in sensory neurons. Neurological examination and small nerve fiber assessment was normal except for reduced distal skin innervation. S126G iPSC showed normal α-GAL A activity compared to controls and no Gb3 deposits were found in all three cell types. Baseline electrophysiological characteristics of S126G neurons showed no difference compared to healthy controls as investigated by patch-clamp recordings. We pioneer multi-level cellular characterization of the VUS S126G using three cell types derived from a patient and provide further evidence for the benign nature of S126G in GLA, which is of great importance in the management of such cases in clinical practice.

The diverse landscape of AB5-type toxins

AB5-type toxins are a group of secreted protein toxins that are central virulence factors for bacterial pathogens such as Shigella dysenteriae, Vibrio cholerae, Bordetella pertussis, and certain lineages of pathogenic Escherichia coli and Salmonella enterica. AB5 toxins are composed of an active (A) subunit that manipulates host cell biology in complex with a pentameric binding/delivery (B) subunit that mediates the toxin's entry into host cells and its subsequent intracellular trafficking. Broadly speaking, all known AB5-type toxins adopt similar structural architectures and employ similar mechanisms of binding, entering and trafficking within host cells. Despite this, there is a remarkable amount of diversity amongst AB5-type toxins; this includes different toxin families with unrelated activities, as well as variation within families that can have profound functional consequences. In this review, we discuss the diversity that exists amongst characterized AB5-type toxins, with an emphasis on the genetic and functional variability within AB5 toxin families, how this may have evolved, and its impact on human disease.

Structure-function analysis of bacterial GH31 α-galactosidases specific for α-(1→4)-galactobiose

Glycoside hydrolase family 31 (GH31) contains α-glycoside hydrolases with different substrate specificities involved in various physiological functions. This family has recently been classified into 20 subfamilies using sequence similarity networks. An α-galactosidase from the gut bacterium Bacteroides salyersiae (BsGH31_19, which belongs to GH31 subfamily 19) was reported to have hydrolytic activity against the synthetic substrate p- nitrophenyl α-galactopyranoside, but its natural substrate remained unknown. BsGH31_19 shares low sequence identity (around 20%) with other reported GH31 α-galactosidases, PsGal31A from Pseudopedobacter saltans and human myogenesis-regulating glycosidase (MYORG), and was expected to have distinct specificity. Here, we characterized BsGH31_19 and its ortholog from a soil Bacteroidota bacterium, Flavihumibacter petaseus (FpGH31_19), and demonstrated that they showed high substrate specificity against α-(1→4)-linkages in α-(1→4)-galactobiose and globotriose [α-Gal-(1→4)-β-Gal-(1→4)-Glc], unlike PsGal31A and MYORG. The crystallographic analyses of BsGH31_19 and FpGH31_19 showed that their overall structures resemble those of MYORG and form a dimer with an interface different from that of PsGal31A and MYORG dimers. The structures of FpGH31_19 complexed with d-galactose and α-(1→4)-galactobiose revealed that amino acid residues that recognize a galactose residue at subsite +1 are not conserved between FpGH31_19 and BsGH31_19. The tryptophan (Trp153) that recognizes galactose at subsite -1 is homologous to the tryptophan residues in MYORG and α-galactosidases belonging to GH27, GH36, and GH97, but not in the bacterial GH31 member PsGal31A. Our results provide structural insights into molecular diversity and evolutionary relationships in the GH31 α-galactosidase subfamilies and the other α-galactosidase families.

Cognitive Deficits Found in a Pro-inflammatory State are Independent of ERK1/2 Signaling in the Murine Brain Hippocampus Treated with Shiga Toxin 2 from Enterohemorrhagic Escherichia coli

Shiga toxin 2 (Stx2) from enterohemorrhagic Escherichia coli (EHEC) produces hemorrhagic colitis, hemolytic uremic syndrome (HUS), and acute encephalopathy. The mortality rate in HUS increases significantly when the central nervous system (CNS) is involved. Besides, EHEC also releases lipopolysaccharide (LPS). Many reports have described cognitive dysfunctions in HUS patients, the hippocampus being one of the brain areas targeted by EHEC infection. In this context, a translational murine model of encephalopathy was employed to establish the deleterious effects of Stx2 and the contribution of LPS in the hippocampus. The purpose of this work is to elucidate the signaling pathways that may activate the inflammatory processes triggered by Stx2, which produces cognitive alterations at the level of the hippocampus. Results demonstrate that Stx2 produced depression-like behavior, pro-inflammatory cytokine release, and NF-kB activation independent of the ERK1/2 signaling pathway, while co-administration of Stx2 and LPS reduced memory index. On the other hand, LPS activated NF-kB dependent on ERK1/2 signaling pathway. Cotreatment of Stx2 with LPS aggravated the pathologic state, while dexamethasone treatment succeeded in preventing behavioral alterations. Our present work suggests that the use of drugs such as corticosteroids or NF-kB signaling inhibitors may serve as neuroprotectors from EHEC infection.

Expression, purification, characterization, and cytotoxic evaluation of the ML1-STxB fusion protein

Targeted delivery of a toxin substance to cancer cells is one of the most recent cancer treatment options. Mistletoe Lectin-1 (ML1) in Viscum album L. is a Ribosome-inactivating proteins with anticancer properties. Therefore, it appears that a recombinant protein with selective permeability can be generated by fusing ML1 protein with Shiga toxin B, which can bind to Gb3 receptor that is abundantly expressed on cancer cells. In this study, we sought to produce and purify a fusion protein containing ML1 fused to STxB and evaluate its cytotoxic activities. The ML1-STxB fusion protein coding sequence was cloned into the pET28a plasmid, then was transformed into E. coli BL21-DE3 cells. Following induction of protein expression, Ni-NTA affinity chromatography was used to purify the protein. Using SDS-PAGE and western blotting, the expression and purification processes were validated. On the SkBr3 cell line, the cytotoxic effects of the recombinant proteins were evaluated. On SDS-PAGE and western blotting membrane, analysis of purified proteins revealed a band of approximately 41 kDa for rML1-STxB. Ultimately, statistical analysis demonstrated that rML1-STxB exerted significant cytotoxic effects on SkBr3 cells at 18.09 and 22.52 ng/L. The production, purification, and encapsulation of rML1-STxB fusion protein with potential cancer cell-specific toxicity were successful. However, additional research must be conducted on the cytotoxic effects of this fusion protein on other malignant cell lines and in vivo cancer models.

Clickable Shiga Toxin B Subunit for Drug Delivery in Cancer Therapy

In recent years, receptor-mediated drug delivery has gained major attention in the treatment of cancer. The pathogen-derived Shiga Toxin B subunit (STxB) can be used as a carrier that detects the tumor-associated glycosphingolipid globotriaosylceramide (Gb3) receptors. While drug conjugation via lysine or cysteine offers random drug attachment to carriers, click chemistry has the potential to improve the engineering of delivery systems as the site specificity can eliminate interference with the active binding site of tumor ligands. We present the production of recombinant STxB in its wild-type (STxB_wt) version or incorporating the noncanonical amino acid azido lysine (STxB_AzK). The STxB_wt and STxB_AzK were manufactured using a growth-decoupled Escherichia coli (E. coli)-based expression strain and analyzed via flow cytometry for Gb3 receptor recognition and specificity on two human colorectal adenocarcinoma cell lines-HT-29 and LS-174-characterized by high and low Gb3 abundance, respectively. Furthermore, STxB_AzK was clicked to the antineoplastic agent monomethyl auristatin E (MMAE) and evaluated in cell-killing assays for its ability to deliver the drug to Gb3-expressing tumor cells. The STxB_AzK-MMAE conjugate induced uptake and release of the MMAE drug in Gb3-positive tumor cells, reaching 94% of HT-29 cell elimination at 72 h post-treatment and low nanomolar doses while sparing LS-174 cells. STxB_AzK is therefore presented as a well-functioning drug carrier, with a possible application in cancer therapy. This research demonstrates the feasibility of lectin carriers used in delivering drugs to tumor cells, with prospects for improved cancer therapy in terms of straightforward drug attachment and effective cancer cell elimination.

Shiga Toxin, Stx2e, Influences the Activity of Porcine Lymphocytes In Vitro

Oedema disease (OD) in piglets is one of the most important pathologies, as it causes significant losses due to the high mortality because of the Shiga toxin family, which produces Escherichia coli (STEC) strains. The main toxin responsible for the characteristic pathologies in pigs is Shiga toxin 2 subtype e (Stx2e). Moreover, there is growing evidence that Stx's family of toxins also targets immune cells. Therefore, this study evaluated the effect of different concentrations of Stx2e on porcine immune cells. Porcine peripheral blood mononuclear cells were pre-incubated with Stx2e, at three different concentrations (final concentrations of 10, 500, and 5000 CD50/mL) and with a negative control group. Cells were then stimulated with polyclonal mitogens: concanavalin A, phytohemagglutinin, pokeweed mitogen, or lipopolysaccharides. Cell proliferation was assessed by BrdU (or EdU) incorporation into newly created DNA. The activation of the lymphocyte subsets was assessed by the detection of CD25, using flow cytometry. The toxin significantly decreased mitogen-driven proliferation activity, and the effect was partially dose-dependent, with a significant impact on both T and B populations. The percentage of CD25+ cells was slightly lower in the presence of Stx2e in all the defined T cell subpopulations (CD4+, CD8+, and γδTCR+)-in a dose-dependent manner. B cells seemed to be the most affected populations. The negative effects of different concentrations of Stx2e on the immune cells in this study may explain the negative impact of the subclinical course of OD.

The choanoflagellate pore-forming lectin SaroL-1 punches holes in cancer cells by targeting the tumor-related glycosphingolipid Gb3

Choanoflagellates are primitive protozoa used as models for animal evolution. They express a large variety of multi-domain proteins contributing to adhesion and cell communication, thereby providing a rich repertoire of molecules for biotechnology. Adhesion often involves proteins adopting a β-trefoil fold with carbohydrate-binding properties therefore classified as lectins. Sequence database screening with a dedicated method resulted in TrefLec, a database of 44714 β-trefoil candidate lectins across 4497 species. TrefLec was searched for original domain combinations, which led to single out SaroL-1 in the choanoflagellate Salpingoeca rosetta, that contains both β-trefoil and aerolysin-like pore-forming domains. Recombinant SaroL-1 is shown to bind galactose and derivatives, with a stronger affinity for cancer-related α-galactosylated epitopes such as the glycosphingolipid Gb3, when embedded in giant unilamellar vesicles or cell membranes. Crystal structures of complexes with Gb3 trisaccharide and GalNAc provided the basis for building a model of the oligomeric pore. Finally, recognition of the αGal epitope on glycolipids required for hemolysis of rabbit erythrocytes suggests that toxicity on cancer cells is achieved through carbohydrate-dependent pore-formation.

A curated lectin database, structural characterization, and in vitro assays show that choanoflagellate lectin SaroL-1 binds to cancer-related α-galactosylated epitopes and can be toxic to cancer cells through a carbohydrate-dependent pore-formation mechanism.

Novel lectin-based chimeric antigen receptors target Gb3-positive tumour cells

The link between cancer and aberrant glycosylation has recently become evident. Glycans and their altered forms, known as tumour-associated carbohydrate antigens (TACAs), are diverse, complex and difficult to target therapeutically. Lectins are naturally occurring glycan-binding proteins  that offer a unique opportunity to recognise TACAs. T cells expressing chimeric antigen receptors (CARs) have proven to be a successful immunotherapy against leukaemias, but so far have shown limited success in solid tumours. We developed a panel of lectin-CARs that recognise the glycosphingolipid globotriaosylceramide (Gb3), which is overexpressed in various cancers, such as Burkitt's lymphoma, colorectal, breast and pancreatic. We have selected the following lectins: Shiga toxin's B-subunit from Shigella dysenteriae, LecA from Pseudomonas aeruginosa, and the engineered lectin Mitsuba from Mytilus galloprovincialis as antigen-binding domains and fused them to a well-known second-generation CAR. The Gb3-binding lectin-CARs have demonstrated target-specific cytotoxicity against Burkitt's lymphoma-derived cell lines as well as solid tumour cells from colorectal and triple-negative breast cancer. Our findings reveal the big potential of lectin-based CARs as therapeutical applications to target Gb3 and other TACAs expressed in haematological malignancies and solid tumours.

Cytokines expression from altered motor thalamus and behavior deficits following sublethal administration of Shiga toxin 2a involve the induction of the globotriaosylceramide receptor

Encephalopathy associated with hemolytic uremic syndrome is produced by enterohemorrhagic E. coli (EHEC) infection, which releases the virulence factors Shiga toxin (Stx) and lipopolysaccharide (LPS). Neurological compromise is a poor prognosis and mortality factor of the disease, and the thalamus is one of the brain areas most frequently affected. We have previously demonstrated the effectiveness of anti-inflammatory drugs to ameliorate the deleterious effects of these toxins. However, the thalamic production of cytokines involved in pro-inflammatory processes has not yet been acknowledged. The aim of this work attempts to determine whether systemic sublethal Stx2a or co-administration of Stx2a with LPS are able to rise a proinflammatory profile accompanying alterations of the neurovascular unit in anterior and lateral ventral nuclei of the thalamus (VA-VL) and motor behavior in mice. After 4 days of treatment, Stx2a affected the lectin-bound microvasculature distribution while increasing the expression of GFAP in reactive astrocytes and producing aberrant NeuN distribution in degenerative neurons. In addition, increased swimming latency was observed in a motor behavioral test. All these alterations were heightened when Stx2a was co-administered with LPS. The expression of pro-inflammatory cytokines TNFα, INF-γ and IL-2 was detected in VA-VL. All these effects were concomitant with increased expression of the Stx receptor globotriaosylceramide (Gb3), which hints at receptor involvement in the neuroinflammatory process as a key finding of this study. In conclusion, Stx2a to Gb3 may be determinant in triggering a neuroinflammatory event, which may resemble clinical outcomes and should thus be considered in the development of preventive strategies.