Fucose-Galactose Polymers Inhibit Cholera Toxin Binding to Fucosylated Structures and Galactose-Dependent Intoxication of Human Enteroids

Jiedu Xiaozheng Yin extract targets cancer stem cells by Wnt signaling pathway in colorectal cancer

ETHNOPHARMACOLOGICAL RELEVANCE

The clinical application of the traditional Chinese medicinal formula Jiedu Xiaozheng Yin (JXY) for gastrointestinal tumors, particularly colorectal cancer (CRC), is well-established, yet the precise biological mechanism underlying its efficacy in CRC treatment remains elusive.

AIMS OF THE STUDY

This study endeavors to unravel the intricate mechanism through which JXY modulates colorectal cancer stem cells, thus elucidating the pathways by which it exerts its potent anti-tumor effects.

MATERIALS AND METHODS

In this study, the regulatory impact of JXY on the signaling pathway and function of CRC cells was analyzed through Network pharmacology. The ethyl acetate extract of JXY was detected the major compounds using HPLC and then treated the HCT-116 cells for RNA-Sequencing (RNA-Seq). Protein expression and stemness of HCT-15 and HCT-116 cells following JXY extract treatment were assessed using Western blot analysis and matrigel spheroid assays. Additionally, the β-catenin transcriptional activity was evaluated using a TOPflash reporter assay with or without Lithium chloride (LiCl) stimulation. Patient-derived organoids of CRC (CRC PDOs) were cultured using a stemness maintenance medium, and their viability was measured using ATP assays after treatment of JXY extract. Furthermore, the anti-tumor efficacy of JXY extract was assessed using a xenograft mice model derived from HCT-15 cells.

RESULTS

Network pharmacology emphasized the influence of JXY on cancer stem cells and the Wnt signaling pathway. HPLC analysis confirmed that the JXY extract contained the three most prevalent pharmaceutical compounds among the four herbs documented in the Chinese Pharmacopoeia (rosmarinic acid, quercetin, and kaempferol). RNA-Seq results further elucidated the effect of JXY extract, particularly targeting cancer stem cells and the Wnt signaling pathway. Furthermore, JXY extract inhibited spheroid formation in CRC cells and downregulated CRC CSC markers (CD133, DCLK1, and C-MYC). Additionally, JXY extract suppressed the β-catenin expression and transcriptional activity as well as the Wnt pathway target proteins, including C-MYC and Cyclin D1. Consistent with findings from cell lines, JXY extract suppressed the growth of CRC PDOs exhibiting stemness characteristics. And JXY extract demonstrated a significant inhibitory effect on tumor growth, C-MYC, and β-catenin protein levels in xenograft tumors.

CONCLUSIONS

These results highlight the novel function of JXY extract in targeting CRC CSCs by regulating Wnt signaling pathway, underscoring its potential as a therapeutic agent for treating CRC.

Lipid Rafts in Signalling, Diseases, and Infections: What Can Be Learned from Fluorescence Techniques?

Lipid rafts are dynamic microdomains in the membrane, rich in cholesterol and sphingolipids, that are critical for biological processes like cell signalling, membrane trafficking, and protein organization. Their essential role is claimed in both physiological and pathological conditions, including cancer, neurodegenerative diseases, and viral infections, making them a key area of research. Fluorescence-based approaches, including super-resolution fluorescence microscopy techniques, enable precise analysis of the organization, dynamics, and interactions of these microdomains, thanks also to the innovative design of appropriate fluorescent probes. Moreover, these non-invasive approaches allow for the study of live cells, facilitating the collection of quantitative data under physiologically relevant conditions. This review synthesizes the latest insights into the role of lipid rafts in biological and pathological processes and underscores how fluorescence techniques have advanced our understanding of these critical microdomains. The findings emphasize the pivotal role of lipid rafts in health and disease, providing a foundation for future research and potential therapeutic interventions.

Triblock Glycopolymers with Two 10-mer Blocks of Activating Sugars Enhance the Activation of Acrosomal Exocytosis in Mouse Sperm

Carbohydrate recognition is imperative for the induction of sperm acrosomal exocytosis (AE), an essential phenomenon in mammalian fertilization. In mouse sperm, polynorbornene 100-mers displaying fucose or mannose moieties were effective at inducing AE. In contrast, glycopolymers exhibiting glucose sugars resulted in no AE activation. To further elucidate the role of ligand density on the activation of AE in mouse sperm, a triple-stain flow cytometry assay was employed to determine the efficacy of polynorbornene block copolymers with barbell-like sequences as initiators of AE. Triblock (ABA or ABC) copolymers were synthesized by ring-opening metathesis polymerization (ROMP) with one or two activating sugars, mannose or fucose, and one nonactivating sugar, glucose. The active ligand fractions in the polymers varied from 10, 20, or 40%. Simultaneously, random copolymers comprising 20% activating ligands were prepared to confirm the importance of ligand positionality in AE activation in mouse sperm. Polynorbornene 100-mers possessing two 10-mer blocks of activating sugars were the most effective copolymers at inducing AE with levels of AE comparable to their homopolymer counterparts and more effective than their random analogues. Small-angle X-ray scattering (SAXS) was then performed to verify that there were no differences in the conformations of the glycopolymers contributing to their varying AE activity. SAXS data analysis confirmed that all of the glycopolymers assumed semiflexible cylindrical structures with similar radii and Kuhn lengths. These findings suggest that the overall ligand density of the sugar moieties in the polymer is less important than the positionality of short blocks of high-density ligands for AE activation in mouse sperm.

Advancements in understanding bacterial enteritis pathogenesis through organoids

Bacterial enteritis has a substantial role in contributing to a large portion of the global disease burden and serves as a major cause of newborn mortality. Despite advancements gained from current animal and cell models in improving our understanding of pathogens, their widespread application is hindered by apparent drawbacks. Therefore, more precise models are imperatively required to develop more accurate studies on host-pathogen interactions and drug discovery. Since the emergence of intestinal organoids, massive studies utilizing organoids have been conducted to study the pathogenesis of bacterial enteritis, revealing new mechanisms and validating established ones. In this review, we focus on the advancements of several bacterial pathogenesis mechanisms observed in intestinal organoid/enteroid models, exploring the host response and bacterial effectors during the infection process. Finally, we address the features that warrant additional investigation or could be enhanced in existing organoid models in order to guide future research endeavors.

Cholera intoxication of human enteroids reveals interplay between decoy and functional glycoconjugate ligands

Prior research on cholera toxin (CT) binding and intoxication has relied on human colonic cancer derived epithelial cells. While these transformed cell lines have been beneficial, they neither derive from small intestine where intoxication occurs, nor represent the diversity of small intestinal epithelial cells (SI-ECs) and variation in glycoconjugate expression among individuals. Here, we used human enteroids, derived from jejunal biopsies of multipledonors to study CT binding and intoxication of human non-transformed SI-ECs. We modulated surface expression of glycosphingolipids, glycoproteins and specific glycans to distinguish the role of each glycan/glycoconjugate. Cholera-toxin-subunit-B (CTB) mutants were generated to decipher the preference of each glycoconjugate to different binding sites and the correlation between CT binding and intoxication. Human enteroids contain trace amounts of GM1, but other glycosphingolipids may be contributing to CT intoxication. We discovered that inhibition of either fucosylation or O-glycosylation sensitize enteroids to CT-intoxication. This can either be a consequence of the removal of fucosylated "decoy-like-ligands" binding to CTB's non-canonical site and/or increase in the availability of Gal/GalNAc-terminating glycoconjugates binding to the canonical site. Furthermore, simultaneous inhibition of fucosylation and O-glycosylation increased the availability of additional Gal/GalNAc-terminating glycoconjugates but counteracted the sensitization in CT intoxication caused by inhibiting O-glycosylation because of reduction in fucose. This implies a dual role of fucose as a functional glycan and a decoy, the interplay of which influences CT binding and intoxication. Finally, while the results were similar for enteroids from different donors, they were not identical, pointing to a role for human genetic variation in determining sensitivity to CT.

Design of Glycopolymers for Controlling the Interactions with Lectins

Carbohydrates are involved in life activities through the interactions with their corresponding proteins (lectins). Pathogen infection and the regulation of cell activity are controlled by the binding between lectins and glycoconjugates on cell surfaces. A deeper understanding of the interactions of glycoconjugates has led to the development of therapeutic and preventive methods for infectious diseases. Glycopolymer is one of the classes of the materials present multiple carbohydrates. The properties of glycopolymers can be tuned through the molecular design of the polymer structures. This review focuses on research over the past decade on the design of glycopolymers with the aim of developing inhibitors against pathogens and manipulator of cellular functions.

Heat-labile enterotoxin enhances F4-producing enterotoxigenic E. coli adhesion to porcine intestinal epithelial cells by upregulating bacterial adhesins and STb enterotoxin

As one of the crucial enterotoxins secreted by enterotoxigenic Escherichia coli (ETEC), heat-labile enterotoxin (LT) enhances bacterial adherence both in vivo and in vitro; however, the underlying mechanism remains unclear. To address this, we evaluated the adherence of LT-producing and LT-deficient ETEC strains using the IPEC-J2 cell model. The expression levels of inflammatory cytokines and chemokines, and tight-junction proteins were evaluated in IPEC-J2 cells after infection with various ETEC strains. Further, the levels of adhesins and enterotoxins were also evaluated in F4ac-producing ETEC (F4 + ETEC) strains after treatment with cyclic AMP (cAMP). The adherence of the ΔeltAB mutant was decreased compared with the wild-type strain, whereas adherence of the 1836-2/pBR322-eltAB strain was markedly increased compared with the 1836-2 parental strain. Production of LT up-regulated the expression of TNF-α, IL-6, CXCL-8, and IL-10 genes. However, it did not appear to affect tight junction protein expression. Importantly, we found that cAMP leads to the upregulation of adhesin production and STb enterotoxin. Moreover, the F4 + ETEC strains treated with cAMP also had greater adhesion to IPEC-J2 cells, and the adherence of ΔfaeG, ΔfliC, and ΔestB mutants was decreased. These results indicate that LT enhances the adherence of F4 + ETEC due primarily to the upregulation of F4 fimbriae, flagellin, and STb enterotoxin expression and provide insights into the pathogenic mechanism of LT and ETEC.

From the Dish to the Real World: Modeling Interactions between the Gut and Microorganisms in Gut Organoids by Tailoring the Gut Milieu

The advent of human intestinal organoid systems has revolutionized the way we understand the interactions between the human gut and microorganisms given the host tropism of human microorganisms. The gut microorganisms have regionality (i.e., small versus large intestine) and the expression of various virulence factors in pathogens is influenced by the gut milieu. However, the culture conditions, optimized for human intestinal organoids, often do not fully support the proliferation and functionality of gut microorganisms. In addition, the regional identity of human intestinal organoids has not been considered to study specific microorganisms with regional preference. In this review we provide an overview of current efforts to understand the role of microorganisms in human intestinal organoids. Specifically, we will emphasize the importance of matching the regional preference of microorganisms in the gut and tailoring the appropriate luminal environmental conditions (i.e., oxygen, pH, and biochemical levels) for modeling real interactions between the gut and the microorganisms with human intestinal organoids.

Synthesis and Self-Assembling Properties of Peracetylated β-1-Triazolyl Alkyl D-Glucosides and D-Galactosides

Carbohydrate-based low-molecular-weight gelators (LMWGs) are useful classes of compounds due to their numerous applications. Among sugar-based LMWGs, certain peracetylated sugar beta-triazole derivatives were found to be effective organogelators and showed interesting self-assembling properties. To further understand the structural influence towards molecular assemblies and obtain new functional materials with interesting properties, we designed and synthesized a library of tetraacetyl beta-1-triazolyl alkyl-D-glucosides and D-galactosides, in which a two or three carbon spacer is inserted between the anomeric position and the triazole moiety. A series of 16 glucose derivatives and 14 galactose derivatives were synthesized and analyzed. The self-assembling properties of these new triazole containing glycoconjugates in different solvents were analyzed. Several glucose derivatives were found to be effective LMWGs, with compound 7a forming gels in a variety of organic solvents as well as in the presence of metal ions in aqueous solutions. The organogels formed by several compounds were characterized using optical microscopy, atomic force microscopy (AFM) and UV-vis spectroscopy, etc. The co-gels formed by compound 7a with the Fmoc derivative 7i showed interesting fluorescence enhancement upon gelation. Several gelators were also characterized using powder X-ray diffraction and FT-IR spectroscopy. The potential applications of these sugar-based gelators for drug delivery and dye removal were also studied.

Multifunctionalized Brush-Like Glycopolymers with High Affinity to P-Selectin and Antitumor Metastasis Activity

Glycopolymers that can mimic natural glycosaminoglycan, such as heparin, have shown great potentials in inhibition of cancer metastasis. In the current work, a novel series of brush-like glycopolymers (BGPs) with simultaneous functionalization of various monosaccharide or disaccharide compositions have been synthesized through a new grafting-polymerization strategy, in order to mimic the activities of both heparin and P-selectin ligand PSGL-1. In the subsequent in vitro assays of antiadhesion, platelets activation, heparanase inhibition, and so on, BGP-SFH, as one of the BGPs with the composition of the combined three sugar units, sialic acids, fucoses, and heparin disaccharides, showed the highest antimetastasis ability, similar to its prototype heparin. Moreover, in a mouse metastatic melanoma model, the BGP-SFH also inhibited B16 cell metastasis effectively. Thus, the current work not only demonstrated a type of promising antimetastasis glycopolymer BGPs, but also illustrated an easy synthetic approach to multifunctionalized glycopolymers, leading to potential applications for broader biomedical research.

Membrane-Disrupting Molecules as Therapeutic Agents: A Cautionary Note

Mechanistic studies have shown that aggregates of a common membrane disrupting molecule, Triton X-100, destroy the integrity of cholesterol-rich phospholipid bilayers via a catastrophic rupture process. In sharp contrast, attack on such membranes by monomers of Triton X-100 destroys their integrity through mild leakage events. This discovery of duplicity in the destruction of membrane integrity by a membrane-disrupting molecule has led to the design of derivatives of Amphotericin B that exhibit a lower tendency to aggregate and antifungal and hemolytic activities that are well-separated. An animal study with one such derivative has shown that its efficacy is similar to that of Amphotericin B but with substantially reduced toxicity. A related in vitro study of a series of derivatives of l-phenylalanine has revealed that monomers possess significant antibacterial activity, while aggregates of these same molecules exhibit hemolytic as well as antibacterial activity. Taken together, these experimental findings point to the need for paying special attention to differences in the selectivity between monomeric and aggregated forms of membrane-disrupting molecules as therapeutic agents, where monomers are expected to be the more selective species. Whether improving the selectivity of antimicrobial peptides and other antimicrobial agents is also possible by reducing their tendency to aggregate, and whether membrane-disrupting molecules can be created that exploit differences in the lipid composition between coronaviruses and mammalian cells, are two important questions that remain to be answered.

Research in a time of enteroids and organoids: how the human gut model has transformed the study of enteric bacterial pathogens

Enteric bacterial pathogens cause significant morbidity and mortality globally. Studies in tissue culture and animal models shaped our initial understanding of these host-pathogen interactions. However, intrinsic shortcomings in these models limit their application, especially in translational applications like drug screening and vaccine development. Human intestinal enteroid and organoid models overcome some limitations of existing models and advance the study of enteric pathogens. In this review, we detail the use of human enteroids and organoids to investigate the pathogenesis of invasive bacteria Shigella, Listeria, and Salmonella, and noninvasive bacteria pathogenic Escherichia coli, Clostridium difficile, and Vibrio cholerae. We highlight how these studies confirm previously identified mechanisms and, importantly, reveal novel ones. We also discuss the challenges for model advancement, including platform engineering to integrate environmental conditions, innate immune cells and the resident microbiome, and the potential for pre-clinical testing of recently developed antimicrobial drugs and vaccines.

Targeting Multiple Binding Sites on Cholera Toxin B with Glycomimetic Polymers Promotes the Formation of Protein-Polymer Aggregates

The canonical binding site on the B subunit of cholera toxin (CTB) binds to GM1 gangliosides on host cells. However, the recently discovered noncanonical binding site on CTB with affinity for fucosylated molecules has raised the possibility that both sites can be involved in initiating intoxication. Previously, we showed that blocking CTB binding to human and murine small intestine epithelial cells can be increased by simultaneously targeting both binding sites with multivalent norbornene-based glycopolymers [ACS Infect. Dis. 2020, 6, 5, 1192-1203]. However, the mechanistic origin of the increased blocking efficacy was unclear. Herein, we observed that mixing CTB pentamers and glycopolymers that display fucose and galactose sugars results in the formation of large aggregates, which further inhibits binding of CTB to human granulocytes. Dynamic light scattering analysis, small-angle X-ray scattering analysis, transmission electron microscopy, and turbidimetric assays revealed that the facial directionality of CTB promotes interchain cross-linking, which in turn leads to self-assembly of protein-polymer networks. This cross-linking-induced self-assembly occurs only when the glycopolymer system contains both galactose and fucose. In an assay of the glycopolymer's ability to block CTB binding to human granulocytes, we observed a direct correlation between IC₅₀ and self-assembly size. The aggregation mechanism of inhibition proposed herein has potential utility for the development of low-cost macromolecular clinical therapeutics for cholera that do not have exotic architectures and do not require complex synthetic sequences.