Β-galactoside Binding Lectin Research Articles

Effect of GB1107, a novel galectin-3 inhibitor on pro-fibrotic signalling in the liver

Background and PurposeGalectin-3 (Gal-3) is a pro-fibrotic β-galactoside binding lectin highly expressed in fibrotic liver and implicated in hepatic fibrosis. GB1107 is a novel orally active Gal-3 small molecule inhibitor that has high affinity for Gal-3 >1000-fold selectively over other galectins. The aim of this study was to characterise GB1107 and galectin-3 in vitro and in vivo in the context of fibrosis signalling and liver disease. Experimental ApproachLiver fibrosis was induced by administration of CCl4 twice weekly by intraperitoneal injection in mice for 8 weeks. GB1107 was orally administered once daily (10 mg/kg) for the last 4 weeks of CCl4 treatment. Fibrosis was assessed by picrosirius red staining of FFPE sections. Liver enzymes, Gal-3 and downstream biomarkers were assessed in liver and plasma. Paired-end sequencing was performed on the NextSeq 2000 platform. Pathway enrichment analysis was performed to determine enrichment of differentially expressed genes (DEGs) within Reactome pathways and Gene Ontology (GO) terms. Key ResultsGB1107 significantly reduced plasma transaminases and liver Gal-3 and reduced liver fibrosis. RNAseq analysis of whole liver showed that 1,659 DEGs were identified with CCl4 treatment compared to control. Pathways enriched in up-regulated genes in the CCl4 group included those related to the extracellular matrix, collagen biosynthesis and assembly, cell cycle and the immune system. Comparing GB1107 treatment with CCl4 control 1147 DEGs were identified. GB1107 effectively reversed the majority of the CCl4 induced gene changes. Conclusions and ImplicationsGB1107 attenuated liver fibrosis and highlights Gal-3 as a therapeutic target for hepatic fibrosis.

The galectin-3 inhibitor selvigaltin reduces liver inflammation and fibrosis in a high fat diet rabbit model of metabolic-associated steatohepatitis.

Galectin-3 is a pro-fibrotic β-galactoside binding lectin highly expressed in fibrotic liver and implicated in hepatic fibrosis. Selvigaltin (previously known as GB1211) is a novel orally active galectin-3 small molecule inhibitor that has high affinity for galectin-3 (human KD = 25nM; rabbit KD = 12nM) and high oral bioavailability in rabbits and man. In this study the efficacy of selvigaltin was investigated in a high fat diet (HFD) rabbit model of metabolic-associated steatohepatitis (MASH). Male New Zealand White rabbits were individually caged under standard conditions in a temperature and humidity-controlled room on a 12h light/darkness cycle. After 1week of regular diet (RD), rabbits were randomly assigned for 8 or 12weeks to different groups: RD/vehicle, RD/selvigaltin, HFD (8weeks), HFD/vehicle and HFD/selvigaltin (0.3, 1.0, 5.0 or 30mg/kg selvigaltin with vehicle/selvigaltin p.o. dosed therapeutically q.d. 5days per week from week 9 or 12). Liver inflammation, steatosis, ballooning, and fibrosis was measured via blood metabolic markers, histomorphological evaluation [Oil Red O, Giemsa, Masson's trichome, picrosirius red (PSR) and second harmonic generation (SHG)], and mRNA and protein expression. Steatosis, inflammation, ballooning, and fibrosis were all increased from RD to HFD/vehicle groups. Selvigaltin demonstrated target engagement by significantly decreasing galectin-3 levels in the liver as measured via immunohistochemistry and mRNA analysis. Selvigaltin dose-dependently reduced biomarkers of liver function (AST, ALT, bilirubin), inflammation (cells foci), and fibrosis (PSR, SHG), as well as decreasing the mRNA and protein expression of several key inflammation and fibrosis biomarkers (e.g., IL6, TGFβ3, SNAI2, collagen). Doses of 1.0 or 5.0mg/kg demonstrated consistent efficacy across most biological endpoints supporting the current clinical doses of selvigaltin being investigated in liver disease. Selvigaltin significantly reduced hepatic inflammation and fibrosis in an HFD rabbit model of MASH following therapeutic dosing for 4 weeks in a dose-dependent manner. These data support the human selvigaltin dose of 100mg b.i.d. that has been shown to reduce key liver biomarkers during a clinical study in liver cirrhosis.

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.

The ligation between ERMAP, galectin-9 and dectin-2 promotes Kupffer cell phagocytosis and antitumor immunity.

Kupffer cells, the liver tissue resident macrophages, are critical in the detection and clearance of cancer cells. However, the molecular mechanisms underlying their detection and phagocytosis of cancer cells are still unclear. Using in vivo genome-wide CRISPR-Cas9 knockout screening, we found that the cell-surface transmembrane protein ERMAP expressed on various cancer cells signaled to activate phagocytosis in Kupffer cells and to control of liver metastasis. ERMAP interacted with β-galactoside binding lectin galectin-9 expressed on the surface of Kupffer cells in a manner dependent on glycosylation. Galectin-9 formed a bridging complex with ERMAP and the transmembrane receptor dectin-2, expressed on Kupffer cells, to induce the detection and phagocytosis of cancer cells by Kupffer cells. Patients with low expression of ERMAP on tumors had more liver metastases. Thus, our study identified the ERMAP-galectin-9-dectin-2 axis as an 'eat me' signal for Kupffer cells.

The Critical Role of Galectin-12 in Modulating Lipid Metabolism in Sebaceous Glands

Sebaceous glands play an important role in maintaining the skin barrier function by producing lipids. Dysregulated lipid production in these glands may contribute to the pathogenesis of human skin diseases. Galectin-12, a member of the β-galactoside‒binding lectin family, is preferentially expressed in adipocytes, where it regulates adipogenesis and functions as an intrinsic negative regulator of lipolysis. It is also expressed by sebocytes and contributes to the proliferation of this cell type. In this study, we show the association between galectin-12 expression and sebocyte differentiation. Galectin-12 knockdown in a human sebocyte cell line reduced lipogenesis and decreased the production of cholesteryl esters, triglycerides, free fatty acids, and cholesterol. Metabolomic analysis of skin surface lipids showed that the levels of the lipids mentioned earlier decreased in sebaceous gland‒specific galectin-12‒knockout mice compared with that in wild-type mice. In addition, galectin-12 positively regulated peroxisome proliferator‒activated receptor-γ transcriptional activity in sebocytes stimulated with fatty acids. Downregulating galectin-12 suppressed the expression of peroxisome proliferator‒activated receptor-γ target genes-acetyl-coenzyme A synthetase 2 gene ACS2 and diacylglycerol O-acyltransferase 1 gene DGAT1-that are required for fatty acid activation and cholesterol and triglyceride biosynthesis. In conclusion, galectin-12 is a positive regulator of sebaceous lipid metabolism with a potential role in the maintenance of skin homeostasis.

Galectin-3 Binding to α5β1 Integrin in Pore Suspended Biomembranes.

Galectin-3 (Gal3) is a β-galactoside binding lectin that mediates many physiological functions, including the binding of cells to the extracellular matrix for which the glycoprotein α5β1 integrin is of critical importance. The mechanisms by which Gal3 interacts with membranes have not been widely explored to date due to the complexity of cell membranes and the difficulty of integrin reconstitution within model membranes. Herein, to study their interaction, Gal3 and α5β1 were purified, and the latter reconstituted into pore-suspended lipid bilayers comprised eggPC:eggPA. Using electrochemical impedance and fluorescence lifetime correlation spectroscopy, we found that on incubation with low nanomolar concentrations of wild-type Gal3, the membrane's admittance and fluidity, as well as integrin's lateral diffusivity, were enhanced. These effects were diminished in the following conditions: (i) absence of integrin, (ii) presence of lactose as a competitive inhibitor of glycan-Gal3 interaction, and (iii) use of a Gal3 mutant that lacked the N-terminal oligomerization domain (Gal3ΔNter). These findings indicated that WTGal3 oligomerized on α5β1 integrin in a glycan-dependent manner and that the N-terminal domain interacted directly with membranes in a way that is yet to be fully understood. At concentrations above 10 nM of WTGal3, membrane capacitance started to decrease and very slowly diffusing molecular species appeared, which indicated the formation of protein clusters made from WTGal3-α5β1 integrin assemblies. Overall, our study demonstrates the capacity of WTGal3 to oligomerize in a cargo protein-dependent manner at low nanomolar concentrations. Of note, these WTGal3 oligomers appeared to have membrane active properties that could only be revealed using our sensitive methods. At slightly higher WTGal3 concentrations, the capacity to generate lateral assemblies between cargo proteins was observed. In cells, this could lead to the construction of tubular endocytic pits according to the glycolipid-lectin (GL-Lect) hypothesis or to the formation of galectin lattices, depending on cargo glycoprotein stability at the membrane, the local Gal3 concentration, or plasma membrane intrinsic parameters. The study also demonstrates the utility of microcavity array-suspended lipid bilayers to address the biophysics of transmembrane proteins.

PSIII-A-4 Analysis of Galectin Gene Variants from Diverse Sheep and Goat Populations Genotyped with the Illumina Beadchip

Abstract Galectins are a highly conserved family of β-galactoside binding lectins encoded by lectin, galactosidebinding soluble genes (LGALS). They are found on a variety of cells and tissues of vertebrates and invertebrates. Understanding the roles of galectins in host–pathogen interaction and activation of host innate, and adaptive immunity has become an important research question. Galectins are known to play a role in parasitic infection in small ruminants. However, little is known about LGALS variants in sheep and goat breeds across the world. In this study, we investigated galectin single nucleotide polymorphism (SNP) variants on five distinct sheep breeds from different geographical regions of Ethiopia. A total of 88 sheep (Arsi-Bale=12, Horro=24, Menz=18, Wolayita=18 and Blackhead Somali=16) were genotyped with Ovine Infinium HD SNP BeadChip (600K). An In Silico approach with Ensembl database (https://useast.ensembl.org/index.html) and SNP BeadChip (perfect matched reference SNP along with their genomic position) identified a total of nineteen SNPs from LGALS-1, -2, -3, -4, -7, -8, -9, -11 and -12 with a consequence of upstream, downstream, and missense gene variant. For all these variants, a highly variable minor allele frequency (MAF) was observed across five sheep populations. We also investigated a total of 308 Chinese goat (Qinggeli=48, Nanjiang=48, Luoping=48, Liaoning=116, and Guangfeng=48) genotyped with Illumina Goat 50K BeadChip. The goat chip only contained a SNP from LGal-4 (rs268252010) which was also found at variable MAF level across the said populations. These results have implications for animal health and production and warrant further investigation using targeted sequencing of galectin genes across different local and international sheep and goat breeds.

422.2: Investigating Galectin-3 as a Novel Therapeutic Target To Block Inflammation and Reduce Ischemia Reperfusion Injury During Vascular Composite Allograft Transplantation

Introduction: Vascularized Composite Allograft (VCA) transplantation is a treatment option for complex injuries that leave patients with structural and functional deficits that cannot be adequately reconstructed. During transplantation, grafts are subjected to hypoxic/ischemic injury during procurement, storage, and reperfusion. Skin and muscle containing VCA are highly susceptible to ischemia reperfusion injury. Galectin-3 is an endogenous β-galactoside binding lectin known to play a role in driving inflammatory responses in response to hypoxic/ischemic stress. Blocking galectin-3 using known inhibitors including modified citrus pectin (MCP) has been shown in animal models to reduce inflammation and fibrosis. We hypothesized that galectin-3 significantly contributes to VCA IRI and that blocking galectin-3 can serve as a novel therapeutic approach to prevent or reduce IRI. We aimed to determine the role of galectin-3 in VCA ischemia reperfusion injury and the effect of blocking galectin-3 using MCP in syngeneic VCA models. Method: Male Brown Norway rats underwent syngeneic hind limb transplantation following 0, 6 or 24 hours of cold ischemia time. A group of rats receiving hind limbs subjected to 24 hours of static cold storage were treated with MCP (1% w/v) in the drinking water starting one week prior to transplantation. Recipient serum and donor VCA tissues were collected at end-of-study 6 days post transplantation. Sera and tissues collected from naive Brown Norway rats were included as controls. Sera levels of galectin-3 were determined by sandwich ELISA (Novus Biologics, Inc). Galectin-3 expression in the muscle was determined by Western Blotting. The degree of inflammation in the muscle tissue was determined by H&E. Results: Sera galectin-3 levels averaged 0.854±0.557ng/ml in naïve BN rats (n=7), 4.232±2.134ng/ml in recipients of grafts transplanted immediately without static cold storage (n=3), 12.86±1.292ng/ml in recipients of grafts subjected to 6 hours cold storage without MCP treatment (n=3),20.10±3.185ng/ml in recipients of grafts subjected to 24 hours cold storage without MCP treatment (n=6), and 12.77±2.098ng/ml in recipients of grafts subjected to 24 hours cold storage with MCP treatment (n=9) (Figure 1A). Galectin-3 expression in the VCA muscle increased according to the extent of cold ischemia. MCP treatment decreased muscle galectin-3 expression (Figure 1B) and inflammation in the muscle (Figure 2) post transplantation.Conclusion: Galectin-3 levels significantly increased in recipient sera and donor muscle within a week in rats transplanted with donor VCA grafts subjected to prolonged ischemia. Blocking galectin-3 using MCP can reduce the amount of galectin-3 in circulation and muscle tissue post transplantation and may decrease inflammation associated with VCA IRI. Galectin-3 may serve as a novel therapeutic target to reduce inflammation associated with ischemic injury and improve VCA outcomes. DOD CDMRP RTRP W81XWH1910163 RT180168.

Resistance to anti-PD-1/anti-PD-L1: GB1211 reverses galectin-3 induced blockade of pembrolizumab and atezolizumab binding to PD-1/PD-L1.

2607 Background: Galectin-3 (Gal-3) is a β-galactoside binding lectin highly expressed across many cancers (Li et al. Biomedicines, 2021) with high expression associated with poor response to the PD-1 inhibitor pembrolizumab (Capalbo et al., Int J Mol Sci, 2019). In addition, it has also been shown preclinically in in vivo mouse non-small cell lung carcinoma (NSCLC) models that inhibition of Gal-3 enhances the performance of checkpoint inhibitors targeting the PD-1/PD-L1 axis (Vuong et al., Cancer Res, 2019; Zhang et al., FEBS Open Bio, 2020). The mechanism by which Gal-3 negatively impacts the effect of PD-1/PD-L1 based checkpoint inhibitors is not fully understood. We investigated the hypothesis that anti-PD1/anti-PDL1 is induced by direct binding and blockade of Gal-3 to the PD-1/PD-L1 complex itself. Methods: SPR was used to investigate the effect of recombinant hGal-3 in combination with a Gal-3 inhibitor (GB1211) on the binding of recombinant hPD-L1 to hPD-1 in the absence and presence of either pembrolizumab or atezolizumab. SPR analysis was performed with a BIAcore (Cytiva, USA). hPD-1 was immobilized onto a CM5 Series S sensorchip via amine coupling and proteins, antibodies or small molecules flowed over in various combinations. Observations made at the protein level were further confirmed in cell binding assays using flow cytometry measuring pembrolizumab and atezolizumab binding to cells lines over expressing high levels of either PD-1 (Jurkat cells) or PD-L1 (RAJI-hPD-L1 cells), respectively. Results: Gal-3 potentiated the binding of PD-L1 to PD-1 with a 3-fold increase in its KD observed and the efficiency of pembrolizumab and atezolizumab binding to and blocking the PD-1/PD-L1 axis was reduced. A 6-fold reduction in KD of pembrolizumab for the PD-1/PD-L1 complex was observed in the presence of Gal-3. In addition, atezolizumab PD-L1 blockade was reversed in the presence of Gal-3 and dramatically improved by GB1211. Similarly, in cell systems expressing high levels of PD-1 or PD-L1, Gal-3 reduced the binding of pembrolizumab and atezolizumab to their respective targets on cell surfaces that was also reversed by GB1211. Conclusions: Gal-3 was shown to vastly reduce the binding of the checkpoint inhibitors pembrolizumab and atezolizumab, by potentiating the interaction between PD-1 and PD-L1. GB1211 restored the binding of the anti-PD1/anti-PDL1 therapeutics and may thus reduce tumor resistance to these agents. These findings harmonize excellently with in vivo and clinical data showing an association between Gal-3 expression and lack of efficacy of PD-1/PD-L1 targeted checkpoint inhibitors. Galecto is now investigating the safety and efficacy of GB1211 in combination with atezolizumab in NSCLC.

Galectin-1 and -3 in high amounts inhibit angiogenic properties of human retinal microvascular endothelial cells in vitro.

PurposeGalectin-1 and -3 are β-galactoside binding lectins with varying effects on angiogenesis and apoptosis. Since in retinal pigment epithelial cells high amounts of human recombinant galectin (hr-GAL)1 and 3 inhibit cell adhesion, migration and proliferation, we investigated if hr-GAL1 and 3 have homologous effects on human retinal microvascular endothelial cells (HRMEC) in vitro.MethodsTo investigate the effect of galectin-1 and -3 on HRMEC, proliferation, apoptosis and viability were analyzed after incubation with 30, 60 and 120 μg/ml hr-GAL1 or 3 by BrdU-ELISA, histone-DNA complex ELISA, live/dead staining and the WST-1 assay, respectively. Further on, a cell adhesion as well as tube formation assay were performed on galectin-treated HRMEC. Migration was investigated by the scratch migration assay and time-lapse microscopy. In addition, immunohistochemical staining on HRMEC for β-catenin, galectin-1 and -3 were performed and β-catenin expression was investigated by western blot analysis.ResultsIncubation with hr-GAL1 or 3 lead to a decrease in proliferation, migration, adhesion and tube formation of HRMEC compared to the untreated controls. No toxic effects of hr-GAL1 and 3 on HRMEC were detected. Intriguingly, after treatment of HRMEC with hr-GAL1 or 3, an activation of the proangiogenic Wnt/β-catenin signaling pathway was observed. However, incubation of HRMEC with hr-GAL1 or 3 drew intracellular galectin-1 and -3 out of the cells, respectively.ConclusionExogenously added hr-GAL1 or 3 inhibit angiogenic properties of HRMEC in vitro, an effect that might be mediated via a loss of intracellular endogenous galectins.

Molecular characterization and expression profiling of tandem-repeat galectin-8 from red-spotted grouper (Epinephelus akaara): Potential antibacterial, antiviral, and wound healing activities

Galectin-8 is a typical β-galactoside binding lectin, which primarily functions as a pattern recognition receptor and/or danger receptor that is engaged in pathogen recognition by the host innate immune system. Although several fish galectins have been identified, the role of galectin-8 in teleost immunity is still not fully understood. In this study, molecular, transcriptional, and immune-related functions of galectin-8 (EaGal8) from red-spotted grouper (Epinephelus akaara) were analyzed. The open reading frame of EaGal8 comprised 960 bp encoding 319 amino acids of a ∼35 kDa protein, composed of the N- and C-terminal carbohydrate recognition domains joined by a short hinge peptide. Phylogenetic analysis revealed that EaGal8 was closely related to the Epinephelus lanceolatus galectin-8-like protein. Although EaGal8 showed ubiquitous tissue expression, the highest expression level was observed in the blood. Immunostimulants, including lipopolysaccharide, poly(I:C), and nervous necrosis virus, significantly upregulated the EaGal8 transcription level in a time-dependent manner (p < 0.05). Furthermore, recombinant EaGal8 (rEaGal8) showed a binding affinity toward seven different carbohydrates in a concentration-dependent manner. In addition, rEaGal8 caused strong agglutination of fish red blood cells and several gram-positive and gram-negative bacteria, including Streptococcus iniae, Streptococcus parauberis, Lactococcus garvieae, Escherichia coli, Edwardsiella tarda, Vibrio alginolyticus, Vibrio parahaemolyticus, and Pseudomonas aeruginosa. For the first time in teleosts, we report the wound healing ability of galectin-8 in this study. At low concentrations, rEaGal8 showed potential wound healing responses in FHM cells, in vitro. Thus, this study reinforces the role of EaGal8 in innate immune responses against bacterial and viral infections and wound healing in red-spotted grouper.

Examination of Galectin-3 Recruitment into Multivesicular Bodies for Exosomal Secretion.

Cells use unconventional secretion to deliver the β-galactoside binding lectin galectin-3 from the cell interior into the extracellular milieu. This process starts with galectin-3 recruitment into intraluminal vesicles (ILVs), which are later released at the plasma membrane as exosomes. Electron microscopy is utilized to determine the location of GFP-tagged galectin-3 in pelleted exosomes. We also describe how these vesicles are harvested from cell culture media to determine their composition. The fluorescent protein GFP was fused with the exosomal sorting motif of galectin-3 to direct GFP into exosomes. Recruitment of this fusion construct into the lumen of exosomes can be assessed by proteinase K accessibility analysis.

Galectin‑3 blockade suppresses the growth of cetuximab‑resistant human oral squamous cell carcinoma.

Oral squamous cell carcinoma (OSCC) is a cancer associated with high mortality (accounting for 3.1/100,000 deaths per year in Brazil in 2013) and a high frequency of amplification in the expression of the epidermal growth factor receptor (EGFR). Treatment with the EGFR inhibitor cetuximab leads to drug resistance in patients with OSCC due to unknown mechanisms. Galectin-3 (Gal-3) is a β-galactoside binding lectin that regulates multiple signaling pathways in cells. The present study aimed to investigate the effect of Gal-3 in cetuximab-resistant (cet-R) OSCC. The OSCC HSC3 cell line was selected to establish a mouse xenograft model, which was treated with cetuximab to induce resistance. Subsequently, a Gal-3 inhibitor was used to treat cet-R tumors, and the tumor volume was monitored. The expression of Gal-3, phosphorylated (p)-ERK1/2 and p-Akt was assessed using immunohistochemistry. The combined effect of cetuximab and the Gal-3 inhibitor on HSC3 tumor xenografts was also investigated. HSC3 cells were cultured in vitro to investigate the regulatory effects of Gal-3 on ERK1/2 and Akt via western blotting. In addition, the effects of the Gal-3 inhibitor on the proliferation, colony formation, invasion and apoptosis of HSC3 cells were investigated by performing Cell Counting Kit-8, colony formation, Transwell and apoptosis assays, respectively. In cet-R OSCC tumors, increased expression of Gal-3, p-ERK1/2 and p-Akt was observed. Further research demonstrated that Gal-3 regulated the expression of both ERK1/2 and Akt in HSC3 cells by promoting phosphorylation. Moreover, the Gal-3 inhibitor decreased the proliferation and invasion, but increased the apoptosis of cet-R HSC3 cells. In addition, the Gal-3 inhibitor suppressed the growth of cet-R tumors. Collectively, the results indicated that the Gal-3 inhibitor and cetuximab displayed a synergistic inhibitory effect on OSCC tumors. In summary, the present study demonstrated that Gal-3 may serve an important role in cet-R OSCC. The combination of cetuximab and the Gal-3 inhibitor may display a synergistic antitumor effect, thereby inhibiting the development of cetuximab resistance in OSCC.

The Antiviral Role of Galectins toward Influenza A Virus Infection-An Alternative Strategy for Influenza Therapy.

Animal lectins are proteins with carbohydrate recognition activity. Galectins, the β-galactoside binding lectins, are expressed in various cells and have been reported to regulate several immunological and physiological responses. Recently, some galectins have been reported to regulate some viral infections, including influenza A virus (IAV); however, the mechanism is still not fully understood. Thus, we aim to review systemically the roles of galectins in their antiviral functions against IAVs. The PRISMA guidelines were used to select the eligible articles. Results indicated that only Galectin-1, Galectin-3, and Galectin-9 were reported to play a regulatory role in IAV infection. These regulatory effects occur extracellularly, through their carbohydrate recognition domain (CRD) interacting with glycans expressed on the virus surface, as well as endogenously, in a cell–cell interaction manner. The inhibition effects induced by galectins on IAV infection were through blocking virus–host receptors interaction, activation of NLRP-3 inflammasome, augment expression of antiviral genes and related cytokines, as well as stimulation of Tim-3 related signaling to enhance virus-specific T cells and humoral immune response. Combined, this study concludes that currently, only three galectins have reported antiviral capabilities against IAV infection, thereby having the potential to be applied as an alternative anti-influenza therapeutic strategy.

Possible value of galectin-3 on follow-up of cardiac remodeling during glucocorticoid treatment.

Glucocorticoids are among the most prescribed drugs globally due to their potent anti-inflammatory and immunosuppressive properties. Although they have positive effects on the treatment of various disease states; long-term administration is associated with high blood pressure, insulin resistance, and susceptibility to type 2 diabetes. The heart attempts to cope with increased blood pressure and a decrease in glucose utilization by developing pathological cardiac remodeling. However, in this process, cardiac fibrosis formation and deterioration in heart structure and functions occur. Galectin-3, a member of the β-galactoside binding lectins, is consistently associated with inflammation and fibrosis in the pathogenesis of various disease states including insulin resistance and heart failure. Galectin-3 expression is markedly increased in activated macrophages and a subset of activated fibroblasts and vascular cells. Also, failing and remodeling myocardium show increased Gal-3 expression and elevated Gal-3 levels are related to heart failure severity and prognosis. Furthermore, Gal-3-related pathways are recently suggested as therapeutic targets both pharmacologically and genetically to increase insulin sensitivity in vivo. The objective of this review is to provide a summary of our current understanding of the role of glucocorticoid-associated insulin resistance, which is important for some cardiac events, and the potential role of galectin in this pathophysiological process.

Galectin-1 Expression in CD8+ T Lymphocytes Controls Inflammation in Contact Hypersensitivity

Allergic contact dermatitis, also known as contact hypersensitivity, is a frequent T-cell‒mediated inflammatory skin disease characterized by red, itchy, swollen, and cracked skin. It is caused by the direct contact with an allergen and/or irritant hapten. Galectin-1 (Gal-1) is a β-galactoside‒binding lectin, which is highly expressed in several types of immune cells. The role of endogenous Gal-1 in contact hypersensitivity is not known. We found that Gal-1‒deficient mice display more sustained and prolonged skin inflammation than wild-type mice after oxazolone treatment. Gal-1‒deficient mice have increased CD8+ T cells and neutrophilic infiltration in the skin. After the sensitization phase, Gal-1‒depleted mice showed an increased frequency of central memory CD8+ T cells and IFN-γ secretion by CD8+ T cells. The absence of Gal-1 does not affect the migration of transferred CD4+ and CD8+ T cells from the blood to the lymph nodes or to the skin. The depletion of CD4+ T lymphocytes as well as adoptive transfer experiments demonstrated that endogenous expression of Gal-1 on CD8+ T lymphocytes exerts a major role in the control of contact hypersensitivity model. These data underscore the protective role of endogenous Gal-1 in CD8+ but not CD4+ T cells in the development of allergic contact dermatitis.

Galectin-8 Is Upregulated in Keratinocytes by IL-17A and Promotes Proliferation by Regulating Mitosis in Psoriasis

Psoriasis is a chronic inflammatory skin disease that develops under the influence of the IL-23/T helper 17 cell axis and is characterized by intense inflammation and prominent epidermal hyperplasia. In this study, we demonstrate that galectin-8, a β-galactoside‒binding lectin, is upregulated in the epidermis of human psoriatic skin lesions as well as in a mouse model of psoriasis induced by intradermal IL-23 injections and in IL-17A‒treated keratinocytes. We show that keratinocyte proliferation is less prominent in galectin-8‒knockout mice after intradermal IL-23 treatment than in wild-type mice. In addition, we show that galectin-8 levels in keratinocytes are positively correlated with the ability of the cells to proliferate and that transitioning from mitosis into G1 phase is delayed in galectin-8‒knockout HaCaT cells after cell-cycle synchronization and release. We demonstrate by immunofluorescence staining and immunoblotting the presence of galectin-8 within the mitotic apparatus. We reveal by coimmunoprecipitation and mass spectrometry analysis that α-tubulin interacts with galectin-8 during mitosis. Finally, we show that in the absence of galectin-8, pericentrin compactness is lessened and mitotic microtubule length is shortened, as demonstrated by immunofluorescence staining. We conclude that galectin-8 is upregulated in psoriasis and contributes to the hyperproliferation of keratinocytes by maintaining centrosome integrity during mitosis through interacting with α-tubulin.

Loss of Lgals3 Protects Against Gonadectomy-Induced Cortical Bone Loss in Mice.

Sex hormone deprivation commonly occurs following menopause in women or after androgen-depletion during prostate cancer therapy in men, resulting in rapid bone turnover and loss of bone mass. There is a need to identify novel therapies to improve bone mass in these conditions. Previously, we identified age- and sex-dependent effects on bone mass in mice with deletion of the gene encoding the β-galactoside binding lectin, galectin-3 (Lgals3-KO). Due to the influence of sex on the phenotype, we tested the role of sex hormones, estrogen (β-estradiol; E2), and androgen (5α-dihydroxytestosterone; DHT) in Lgals3-KO mice. To address this, we subjected male and female wild-type and Lgals3-KO mice to gonadectomy ± E2 or DHT rescue and compared differential responses in bone mass and bone formation. Following gonadectomy, male and female Lgals3-KO mice had greater cortical bone expansion (increased total area; T.Ar) and reduced loss of bone area (B.Ar). While T.Ar and B.Ar were increased in response to DHT in wild-type mice, DHT did not alter these parameters in Lgals3-KO mice. E2 rescue more strongly increased B.Ar in Lgals3-KO compared to wild-type female mice due to a failure of E2 to repress the increase in T.Ar following gonadectomy. Lgals3-KO mice had more osteoblasts relative to bone surface when compared to wild-type animals in sham, gonadectomy, and E2 rescue groups. DHT suppressed this increase. This study revealed a mechanism for the sex-dependency of the Lgals3-KO aging bone phenotype and supports targeting galectin-3 to protect against bone loss associated with decreased sex hormone production.

Galectin-3: multiple clinical applications

Galectin-3 is a β-galactoside binding lectin, containing carbohydrate-recognition domain, which interacts with a number of ligands. It is found in many tissues and is distributed intra– and extracellularly. The localization of the biomarker determines its function. Galectin-3 is involved in variety of biological processes sush as inflammation, fibrosis, immunological response and neoplastic growth. It may be used as a diagnostic or prognostic biomarker especially in cancer and cardiovascular diseases. The present review summarizes some of the properties of this biomarker.

Galectin-3 prospects as a therapeutic agent for multiple sclerosis.

Galectin-3 prospects as a therapeutic agent for multiple sclerosis.