Human Galectin-3 Research Articles

Galectin-8 Contributes to Human Trophoblast Cell Invasion.

Galectins are a class of lectins that are extensively expressed in all organisms. Galectins are involved in a range of functions, including early development, tissue regeneration, cancer and inflammation. It has been shown that galectin-8 is expressed in the villous and extravillous trophoblast (EVT) cells of the human placenta; however, its physiological role in pregnancy establishment has not been elucidated. Taking these factors into account, we investigated the functional role of galectin-8 in HTR-8/SVneo cells-a human EVT cell line-and human primary cytotrophoblast cells isolated from a first-trimester placenta. We analyzed the effects of recombinant human galectin-8 (rh galectin-8) on the adhesion, migration and invasion of HTR-8/SVneo cells. We used qPCR, cell-based ELISA (cELISA) and gelatin zymography to study the effects of galectin-8 on mediators of these processes, such as integrin subunits alpha-1 and beta-1 and matrix metalloproteinases (MMPs)-2 and -9, on the mRNA and protein levels. Further, we studied the effects of galectin-8 on primary cytotrophoblast cells' invasion. Galectin-8 stimulated the adhesion, migration and invasion of HTR-8/SVneo cells, as well as the invasion of primary cytotrophoblasts. In addition, the MMP-2 and -9 levels were increased, while the expression of integrins alpha-1 and beta-1 was not affected. Galectin-8 has the ability to positively affect EVTs' invasion, so it can be considered a significant factor in the trophoblast cell invasion process.

CH-π Interactions Are Required for Human Galectin-3 Function.

Glycan-binding proteins, or lectins, recognize distinct structural elements of polysaccharides, to mediate myriad biological functions. Targeting glycan-binding proteins involved in human disease has been challenging due to an incomplete understanding of the molecular mechanisms that govern protein-glycan interactions. Bioinformatics and structural studies of glycan-binding proteins indicate that aromatic residues with the potential for CH-π interactions are prevalent in glycan-binding sites. However, the contributions of these CH-π interactions to glycan binding and their relevance in downstream function remain unclear. An emblematic lectin, human galectin-3, recognizes lactose and N-acetyllactosamine-containing glycans by positioning the electropositive face of a galactose residue over the tryptophan 181 (W181) indole forming a CH-π interaction. We generated a suite of galectin-3 W181 variants to assess the importance of these CH-π interactions to glycan binding and function. As determined experimentally and further validated with computational modeling, variants with smaller or less electron-rich aromatic side chains (W181Y, W181F, W181H) or sterically similar but nonaromatic residues (W181M, W181R) showed poor or undetectable binding to lactose and attenuated ability to bind mucins or agglutinate red blood cells. The latter functions depend on multivalent binding, highlighting that weakened CH-π interactions cannot be overcome by avidity. Two galectin-3 variants with disrupted hydrogen bonding interactions (H158A and E184A) showed similarly impaired lactose binding. Molecular simulations demonstrate that all variants have decreased binding orientation stability relative to native galectin-3. Thus, W181 collaborates with the endogenous hydrogen bonding network to enhance binding affinity for lactose, and abrogation of these CH-π interactions is as deleterious as eliminating key hydrogen bonding interactions. These findings underscore the critical roles of CH-π interactions in carbohydrate binding and lectin function and will aid the development of novel lectin inhibitors.

Exploring galectin interactions with human milk oligosaccharides and blood group antigens identifies BGA6 as a functional galectin-4 ligand

Galectins (Gals), a family of multifunctional glycan-binding proteins, have been traditionally defined as β-galactoside binding lectins. However, certain members of this family have shown selective affinity towards specific glycan structures including human milk oligosaccharides (HMOs) and blood group antigens. In this work, we explored the affinity of human galectins (particularly Gal-1, -3, -4, -7 and -12) towards a panel of oligosaccharides including HMOs and blood group antigens using a complementary approach based on both experimental and computational techniques. While prototype Gal-1 and Gal-7 exhibited differential affinity for type I vs. type II Lac/LacNAc residues and recognized fucosylated neutral glycans, chimera-type Gal-3 showed high binding affinity towards poly-LacNAc structures including LNnH and LNnO. Notably, the tandem-repeat human Gal-12 showed preferential recognition of 3-fucosylated glycans, a unique feature among members of the galectin family. Finally, Gal-4 presented a distinctive glycan-binding activity characterized by preferential recognition of specific blood group antigens, also validated by saturation transfer difference nuclear magnetic resonance (STD-NMR) experiments. Particularly, we identified oligosaccharide blood group A type 6 (BGA6) as a biologically relevant Gal-4 ligand, which specifically inhibited IL-6 secretion induced by this lectin on human peripheral blood mononuclear cells. These findings highlight unique determinants underlying specific recognition of HMOs and blood group antigens by human galectins, emphasizing the biological relevance of Gal-4-BGA6 interactions, with critical implications in the development and regulation of inflammatory responses.

Biophysical and Structural Characterization of the Interaction between Human Galectin-3 and the Lipopolysaccharide from Pseudomonas aeruginosa.

Given the significant involvement of galectins in the development of numerous diseases, the aim of the following work is to further study the interaction between galectin-3 (Gal3) and the LPS from Pseudomonas aeruginosa. This manuscript focused on the study of the interaction of the carbohydrate recognition domain of Gal3 with the LPS from Pseudomonas aeruginosa by means of different complementary methodologies, such as circular dichroism; spectrofluorimetry; dynamic and static light scattering and evaluation of the impact of Gal3 on the redox potential membranes of Escherichia coli and P. aeruginosa cells, as well as ITC and NMR studies. This thorough investigation reinforces the hypothesis of an interaction between Gal3 and LPS, unraveling the structural details and providing valuable insights into the formation of these intricate molecular complexes. Taken together, these achievements could potentially prompt the design of therapeutic drugs useful for the development of agonists and/or antagonists for LPS receptors such as galectins as adjunctive therapy for P. aeruginosa.

Glycomimetic inhibitors of tandem-repeat galectins: Simple and efficient

The binding of human galectins by glycomimetic inhibitors is a promising therapeutic approach. The structurally distinct group of tandem-repeat galectins has scarcely been studied so far, and there is hardly any knowledge on their ligand specificity or their inhibitory potential, particularly concerning non-natural carbohydrates. Here, we present the synthesis of a library of seven 3-O-disubstituted thiodigalactoside-derived glycomimetics and their affinity to two tandem-repeat galectins, Gal-8 and Gal-9. The straightforward synthesis of these glycomimetics involved dibutyltin oxide-catalyzed 3,3́-O-disubstitution of commercially available unprotected thiodigalactoside, and conjugation of various aryl substituents by copper-catalyzed Huisgen azide-alkyne cycloaddition (CuAAC). The inhibitory potential of the prepared glycomimetics for Gal-8 and Gal-9 was assessed, and compared with the established galectins Gal-1 and Gal-3. The introduction of C-3 substituents resulted in an over 40-fold increase in affinity compared with unmodified TDG. The structure-affinity relations within the studied series were discussed using molecular modeling. Furthermore, the prepared glycomimetics were shown to scavenge Gal-8 and Gal-9 from the surface of cancer cells. This pioneering study on the synthetic inhibitors especially of Gal-9 identified lead compounds that may be used in further biomedical research.

Identification of benzothiazole derived monosaccharides as potent, selective, and orally bioavailable inhibitors of human and mouse galectin-3; a rare example of using a S···O binding interaction for drug design

As a result of our continued efforts to pursue Gal-3 inhibitors that could be used to fully evaluate the potential of Gal-3 as a therapeutic target, two novel series of benzothiazole derived monosaccharides as potent (against both human and mouse Gal-3) and orally bioavailable Gal-3 inhibitors, represented by 4 and 5, respectively, were identified. These discoveries were made based on proposals that the benzothiazole sulfur atom could interact with the carbonyl oxygen of G182/G196 in h/mGal-3, and that the anomeric triazole moiety could be modified into an N-methyl carboxamide functionality. The interaction between the benzothiazole sulfur and the carbonyl oxygen of G196 in mGal-3 was confirmed by an X-ray co-crystal structure of early lead 9, providing a rare example of using a S···O binding interaction for drug design. It was found that for both the series, methylation of 3-OH in the monosaccharides caused no loss in h &mGal-3 potencies but significantly improved permeability of the molecules.

Galectin-3 – A novel ligand of complement protein C1q

In the present study we report a novel interaction of human C1q, a primary activator of the Complement system, with human Galectin-3 (Gal-3). We investigated the potential recognition between C1q and Gal-3 on a solid hydrophobic surface by ELISA, by fluorescence spectroscopy, molecular docking and molecular dynamics (MD). The data showed that C1q and Gal-3 had a pronounced affinity for protein-protein interaction and supramolecular binding, locating the binding sites within the globular domains of C1q (gC1q) and on the backside of the carbohydrate recognition domain (CRD) of Gal-3. Fluorescence spectroscopy gave quantitative assessment of the recognition with KD value of 0.04 μM. MD analysis showed that when the active AAs of the two proteins interacted, electrostatic attraction, aided by a large number of hydrogen bonds, was dominant for the stabilization of the complex. When the contact of C1q and Gal-3 was not limited to active residues, the complex between them was stabilized mainly by Van der Waals interactions and smaller in number but stronger hydrogen bonds. This is the first report analyzing the interaction of Gal-3 with C1q, which could open the way to new applications of this protein-protein complex.

Saturation Transfer Difference NMR and Molecular Docking Interaction Study of Aralkyl-Thiodigalactosides as Potential Inhibitors of the Human-Galectin-3 Protein.

Human Galectin-3 (hGal-3) is a protein that selectively binds to β-galactosides and holds diverse roles in both normal and pathological circumstances. Therefore, targeting hGal-3 has become a vibrant area of research in the pharmaceutical chemistry. As a step towards the development of novel hGal-3 inhibitors, we synthesized and investigated derivatives of thiodigalactoside (TDG) modified with different aromatic substituents. Specifically, we describe a high-yielding synthetic route of thiodigalactoside (TDG); an optimized procedure for the synthesis of the novel 3,3'-di-O-(quinoline-2-yl)methyl)-TDG and three other known, symmetric 3,3'-di-O-TDG derivatives ((naphthalene-2yl)methyl, benzyl, (7-methoxy-2H-1-benzopyran-2-on-4-yl)methyl). In the present study, using competition Saturation Transfer Difference (STD) NMR spectroscopy, we determined the dissociation constant (Kd) of the former three TDG derivatives produced to characterize the strength of the interaction with the target protein (hGal-3). Based on the Kd values determined, the (naphthalen-2-yl)methyl, the (quinolin-2-yl)methyl and the benzyl derivatives bind to hGal-3 94, 30 and 24 times more strongly than TDG. Then, we studied the binding modes of the derivatives in silico by molecular docking calculations. Docking poses similar to the canonical binding modes of well-known hGal-3 inhibitors have been found. However, additional binding forces, cation-π interactions between the arginine residues in the binding pocket of the protein and the aromatic groups of the ligands, have been established as significant features. Our results offer a molecular-level understanding of the varying affinities observed among the synthesized thiodigalactoside derivatives, which can be a key aspect in the future development of more effective ligands of hGal-3.

Bacterial surface display of human lectins in Escherichia coli.

Lectin-glycan interactions sustain fundamental biological processes involved in development and disease. Owing to their unique sugar-binding properties, lectins have great potential in glycobiology and biomedicine. However, their relatively low affinities and broad specificities pose a significant challenge when used as analytical reagents. New approaches for expression and engineering of lectins are in demand to overcome current limitations. Herein, we report the application of bacterial display for the expression of human galectin-3 and mannose-binding lectin in Escherichia coli. The analysis of the cell surface expression and binding activity of the surface-displayed lectins, including point and deletion mutants, in combination with molecular dynamics simulation, demonstrate the robustness and suitability of this approach. Furthermore, the display of functional mannose-binding lectin in the bacterial surface proved the feasibility of this method for disulfide bond-containing lectins. This work establishes for the first time bacterial display as an efficient means for the expression and engineering of human lectins, thereby increasing the available toolbox for glycobiology research.

Ferrocene- and ruthenium arene-containing glycomimetics as selective inhibitors of human galectin-1 and -3

This work presents a novel series of galectin inhibitors with ferrocene and ruthenium arene motifs. Diferrocene thiodigalactoside exhibited high binding affinity and selectivity for human galectin-1 over human galectin-3.

Galectin-3 does not interact with RNA directly.

Galectin-3, well characterized as a glycan binding protein, has been identified as a putative RNA binding protein, possibly through participation in pre-mRNA maturation through interactions with splicosomes. Given recent developments with cell surface RNA biology, the putative dual-function nature of galectin-3 evokes a possible non-classical connection between glycobiology and RNA biology. However, with limited functional evidence of a direct RNA interaction, many molecular-level observations rely on affinity reagents and lack appropriate genetic controls. Thus, evidence of a direct interaction remains elusive. We demonstrate that antibodies raised to endogenous human galectin-3 can isolate RNA-protein crosslinks, but this activity remains insensitive to LGALS3 knock-out. Proteomic characterization of anti-galectin-3 IPs revealed enrichment of galectin-3, but high abundance of hnRNPA2B1, an abundant, well-characterized RNA-binding protein with weak homology to the N-terminal domain of galectin-3, in the isolate. Genetic ablation of HNRNPA2B1, but not LGALS3, eliminates the ability of the anti-galectin-3 antibodies to isolate RNA-protein crosslinks, implying either an indirect interaction or cross-reactivity. To address this, we introduced an epitope tag to the endogenous C-terminal locus of LGALS3. Isolation of the tagged galectin-3 failed to reveal any RNA-protein crosslinks. This result suggests that the galectin-3 does not directly interact with RNA and may be misidentified as an RNA-binding protein, at least in HeLa where the putative RNA associations were first identified. We encourage further investigation of this phenomenon employ gene deletions and, when possible, endogenous epitope tags to achieve the specificity required to evaluate potential interactions.

Strong Binding of C-Glycosylic1,2-Thiodisaccharides to Galectin-3─Enthalpy-Driven Affinity Enhancement by Water-Mediated Hydrogen Bonds.

Galectin-3 is involved in multiple pathways of many diseases, including cancer, fibrosis, and diabetes, and it is a validated pharmaceutical target for the development of novel therapeutic agents to address unmet medical needs. Novel 1,2-thiodisaccharides with a C-glycosylic functionality were synthesized by the photoinitiated thiol-ene click reaction of O-peracylated 1-C-substituted glycals and 1-thio-glycopyranoses. Subsequent global deprotection yielded test compounds, which were studied for their binding to human galectin-3 by fluorescence polarization and isothermal titration calorimetry to show low micromolar Kd values. The best inhibitor displayed a Kd value of 8.0 μM. An analysis of the thermodynamic binding parameters revealed that the binding Gibbs free energy (ΔG) of the new inhibitors was dominated by enthalpy (ΔH). The binding mode of the four most efficient 1,2-thiodisaccharides was also studied by X-ray crystallography that uncovered the unique role of water-mediated hydrogen bonds in conferring enthalpy-driven affinity enhancement for the new inhibitors. This 1,2-thiodisaccharide-type scaffold represents a new lead for galectin-3 inhibitor discovery and offers several possibilities for further development.

Galectin-3 in the blood serum of patients with bone tumors

Background. Due to diversity of cancer, the functional role of galectin-3 is rather controversial; however, for many types of neoplasms, the marker acts as a tumor growth promoter.Aim. To perform a comparative analysis of galectin-3 levels in the blood serum of healthy individuals and patients with benign, borderline, and malignant bone tumors divided into two age groups (under and over 18 years of age) based on the main clinical and morphological characteristics of the disease and prognosis.Materials and methods. The study included 201 patients with benign, borderline (giant cell tumors, locally aggressive tumors), and malignant bone tumors and 31 healthy donors. The galectin-3 level was determined in the blood serum before treatment with Human Galectin-3 ELISA kit (R&D, USA).Results. The level of galectin-3 in the blood serum of patients with benign and malignant bone tumors was statistically significantly higher than that in the control group of patients both under and over 18 years. In patients with borderline bone tumors, a trend toward an increase in the galectin-3 concentration compared with the controls was revealed. The ROC analysis for galectin-3 in patients with bone sarcomas showed that the area under the curve (AUC) comprised 0.795 (р < 0.0001) in the group of patients over 18 years and 0.868 (р = 0.0008) in the individuals under 18 years. For malignant bone tumors in patients over 18 years, the sensitivity of this method was 71.3%, and specificity was 71.43% (optimal cut-off level was 8.09 ng / ml; р < 0.0001), while in patients under 18 years, the sensitivity of the method was 80%, and specificity was 90% (optimal cut-off level was 5.49 ng / ml; р < 0.001). No significant associations between the serum galectin-3 level and the clinical and morphological characteristics of bone neoplasms were found both in patients under and over 18 years of age. However, it could be noted that the highest concentration of the marker was found in chordomas and at earlier stages of the disease. In patients over 18 years with chondrosarcoma and osteosarcoma, no correlation between the marker and the disease prognosis was found.Conclusion. An increase in the galectin-3 level in the blood serum was observed in all age groups of patients with both benign and malignant bone tumors. However, the sensitivity and specificity of the method assessed by the ROC analysis do not allow to apply this marker for the diagnosis of bone tumors.

Evaluating the affinity and kinetics of small molecule glycomimetics for human and mouse galectin-3 using surface plasmon resonance.

Galectin-3 is a beta-galactoside-binding mammalian lectin that is one of a 15-member galectin family that can bind several cell surface glycoproteins via its carbohydrate recognition domain (CRD). As a result, it can influence a range of cellular processes including cell activation, adhesion and apoptosis. Galectin-3 has been implicated in various diseases, including fibrotic disorders and cancer, and is now being therapeutically targeted by both small and large molecules. Historically, the screening and triaging of small molecule glycomimetics that bind to the galectin-3 CRD has been completed in fluorescence polarisation (FP) assays to determine KD values. Surface plasmon resonance (SPR) has not been widely used for compound screening and in this study it was used to compare human and mouse galectin-3 affinity measures between FP and SPR, as well as investigate compound kinetics. The KD estimates for a set of compounds selected from mono- and di-saccharides with affinities across a 550-fold range, correlated well between FP and SPR assay formats for both human and mouse galectin-3. Increases in affinity for compounds binding to human galectin-3 were driven by changes in both kon and koff whilst for mouse galectin-3 this was primarily due to kon. The reduction in affinity observed between human to mouse galectin-3 was also comparable between assay formats. SPR has been shown to be a viable alternative to FP for early drug discovery screening and determining KD values. In addition, it can also provide early kinetic characterisation of small molecule galectin-3 glycomimetics with robust kon and koff values generated in a high throughput manner.

Linker remodels human Galectin-8 structure and regulates its hemagglutination and pro-apoptotic activity

Numerous articles have reported the involvement of linker in regulating bioactivity of tandem-repeat galectins. We hypothesize that linker interacts with N/C-CRDs to regulate the bioactivity of tandem-repeat galectins. To further investigate structural molecular mechanism of linker in regulating bioactivity of Gal-8, Gal-8LC was crystallized. Gal-8LC structure revealed formation of β-strand S1 by Asn174 to Pro176 from linker. S1-strand interacts with C-terminal of C-CRD via hydrogen bond interactions, mutually influencing their spatial structures. Our Gal-8 NL structure have demonstrated that linker region from Ser154 to Gln158 interacts with the N-terminal of Gal-8. Ser154 to Gln158 and Asn174 to Pro176 are likely involved in regulation of Gal-8's biological activity. Our preliminary experiment results revealed different hemagglutination and pro-apoptotic activities between full-length and truncated forms of Gal-8, indicating involvement of linker in regulating these activities. We generated several mutant and truncated forms of Gal-8 (Gal-8 M3, Gal-8 M5, Gal-8TL1, Gal-8TL2, Gal-8LC-M3 and Gal-8_177–317). Ser154 to Gln158 and Asn174 to Pro176 were found to be involved in regulating hemagglutination and pro-apoptotic activities of Gal-8. Ser154 to Gln158 and Asn174 to Pro176 are critical functional regulatory regions within linker. Our study holds significant importance in providing a profound understanding of how linker regulates biological activity of Gal-8.

THE RELATIONSHIP BETWEEN SERUM GALECTIN-3 LEVEL AND CAROTID FEMORAL PULSE WAVE VELOCITY IN PATIENTS WITH ACROMEGALY

Objective: To the best our knowledge, there are no studies showing the relationship between galectin-3 level and carotid femoral pulse wave velocity (CF-PWV) in acromegaly and more studies are needed. We aimed to investigate the relationship between galectin-3 level, which is thought to change due to early inflammation and atherosclerosis, and CF-PWV in patients with acromegaly. Design and method: In our study, forty patients between the ages of 18 and 65 who were diagnosed with acromegaly in Adana City Training and Research Hospital and 40 healthy controls were included. Insulin-like growth factor-1 (IGF-1), GH levels, hemogram and biochemistry values of the patients were evaluated. Galectin-3 level was measured using Human galectin-3 kits and Enzyme-Linked Immuno Sorbent Assay method. CF-PWV measurements of the patients were performed using doppler ultrasonography and simultaneous electrocardiography. Results: In our study; we found that galectin-3 level, which is an indicator of fibrosis and inflammation, and CF-PWV, which is the gold standard indicator of arterial stiffness, were higher in the acromegaly patient group than in the control group and were statistically significant. In correlation analysis, we found that serum galectin-3 level was associated with IGF-1 level and CF-PWV measurements. In the linear regression analysis, we found that the level of IGF-1 was independently associated with galectin-3 level. Conclusions: Galectin-3 may be a new diagnostic, prognostic biomarker and a new promising therapeutic target for cardiovascular disease development in patients with acromegaly. Galectin-3 level and CF-PWV measurement can be used to detect and predict cardiovascular disease in acromegaly patients at an early stage.

Galectin-3 and matrix metalloproteinases 2 and 9 in peripheral blood of gastric cancer patients

Background: High incidence of gastric cancer (GC), its aggressive clinical course, rapid tumor dissemination, low sensitivity to chemotherapy and lack of reliable laboratory diagnostic criteria urgently require a search for the most informative markers associated with key biologic properties of the tumors.
 Aim: Comparative analysis of galectin-3, matrix metalloproteinase (MMP)-2, and MMP-9 levels in peripheral blood of GC patients and healthy donors, assessment of association of these markers with clinical morphological characteristics of the disease, and prognosis of overall and relapse-free survival.
 Materials and methods: Sixty (60) primary treatment-nave GC patients (38 men, 22 women) aged 29 to 81 years and 90 healthy donors compatible with their age and sex were included into the study. Galectin-3 was measured in EDTA plasma, MMP-2 and MMP-9 in serum with standard direct enzyme immunoassay kits "Human MMP-2 (total)", "Human MMP-9 (total)", "Human Galectin-3" (RD Systems, USA).
 Results: Plasma galectin-3 concentration in the GC patients was significantly higher than in the healthy controls (median 12.9 and 10.6 ng/ml, respectively; p 0.0001). No difference in serum MMP-9 levels between GC patients and control subjects were found, while MMP-2 level in the control group was significantly higher, than in the GC patients (p = 0.039). No association between galectin-3, MMP-2, and MMP-9 blood levels in the GC patients could be identified. In contrast to GC patients, there was a positive correlation of plasma galectin-3 with age in the control group (rs = 0.51, p 0.005). No associations between the biomarkers levels in blood and clinical and morphological characteristics of GC were established, except MMP-9 being higher at Т4а invasion depth as compared to the earlier Т2 level. Marked differences in the overall survival depending on plasma galectin-3 levels were found, with the cut-off level of 12.9 ng/ml: the 5-year overall survival in the patients with low galectin-3 was better, than in those with its higher level (50 and 43%, respectively; however, the difference was non-significant, р 0.1). Both overall and relapse-free survival of the GC patients was higher in those with low ( 212 ng/ml) serum MMP-2: the 5-year overall survival in this group comprised 60% versus 23% in the patients with higher MMP-2 (p = 0.018). The difference in relapse-free survival was non-significant. Serum MMP-9 levels had no significant impact on the survival of GC patients.
 Conclusion: The ambiguous data on the clinical role of galectin-3, MMP-2, MMP-9 in GC obtained in this study indicate the necessity of further investigation of their possible utility for the diagnostics and prognosis of treatment results.

Molecular Recognition of Glycan-Bearing Glycomacromolecules Presented at Membrane Surfaces by Lectins: An NMR View.

Lectin-glycan interactions are at the heart of a multitude of biological events. Glycans are usually presented in a multivalent manner on the cell surface as part of the so-called glycocalyx, where they interact with other entities. This multivalent presentation allows us to overcome the typical low affinities found for individual glycan-lectin interactions. Indeed, the presentation of glycans may drastically impact their binding by lectins, highly affecting the corresponding binding affinity and even selectivity. In this context, we herein present the study of the interaction of a variety of homo- and heteromultivalent lactose-functionalized glycomacromolecules and their lipid conjugates with two human galectins. We have employed as ligands the glycomacromolecules, as well as liposomes decorated with those structures, to evaluate their interactions in a cell-mimicking environment. Key details of the interaction have been unravelled by NMR experiments, both from the ligand and receptor perspectives, complemented by cryo-electron microscopy methods and molecular dynamics simulations.

Human galectin-9 potently enhances SARS-CoV-2 replication and inflammation in airway epithelial cells.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has caused a global economic and health crisis. Recently, plasma levels of galectin-9 (Gal-9), a β-galactoside-binding lectin involved in immune regulation and viral immunopathogenesis, were reported to be elevated in the setting of severe COVID-19 disease. However, the impact of Gal-9 on SARS-CoV-2 infection and immunopathology remained to be elucidated. In this study, we demonstrate that Gal-9 treatment potently enhances SARS-CoV-2 replication in human airway epithelial cells (AECs), including immortalized AECs and primary AECs cultured at the air-liquid interface. Gal-9-glycan interactions promote SARS-CoV-2 attachment and entry into AECs in an angiotensin-converting enzyme 2 (ACE2)-dependent manner, enhancing the binding of the viral spike protein to ACE2. Transcriptomic analysis revealed that Gal-9 and SARS-CoV-2 infection synergistically induced the expression of key pro-inflammatory programs in AECs, including the IL-6, IL-8, IL-17, EIF2, and TNFα signaling pathways. Our findings suggest that manipulation of Gal-9 should be explored as a therapeutic strategy for SARS-CoV-2 infection.

Galectin-3, a damage-associated molecular pattern, in tears of patients with vernal keratoconjunctivitis.

Galectin-3 is a damage-associated molecular pattern (DAMPs), released from damaged or dying cells. In this study, we investigated the concentration and source of galectin-3 in the tears of patients with vernal keratoconjunctivitis (VKC) and evaluated whether the concentration of galectin-3 in tears represents a biomarker of corneal epithelial damage. Clinical and experimental. We measured the concentration of galectin-3 in tear samples from 26 patients with VKC and 6 healthy controls by enzyme-linked immunosorbent assay (ELISA). The expression of galectin-3 in cultured human corneal epithelial cells (HCEs) stimulated with or without tryptase or chymase was investigated by polymerase chain reaction (PCR), ELISA, and Western blotting. We also estimated the concentration of galectin-3 in the supernatants of cultured HCEs induced to necrosis. Finally, we investigated whether recombinant galectin-3 induced the expression of various genes related to cell migration or the cell cycle in HCEs by using microarray analysis. High concentrations of galectin-3 were detected in the tears of patients with VKC. The concentration showed significant correlation with the severity of corneal epithelial damage. Stimulation of cultured HCEs with various concentrations of tryptase or chymase had no effect on the expression of galectin-3. However, high concentrations of galectin-3 were detected in the supernatants of necrotic HCEs. Recombinant human galectin-3 induced various cell migration- and cell cycle-related genes. The concentrations of galectin-3 in the tears of patients with VKC may represent a biomarker of the severity of corneal epithelial damage.