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Enhanced sebocyte proliferation is associated with the pathogenesis of human skin diseases related to sebaceous gland hyperfunction and androgens, which are known to induce sebocyte proliferation, are key mediators of this process. Galectin-12, a member of the β-galactoside-binding lectin family that is preferentially expressed by adipocytes and functions as an intrinsic negative regulator of lipolysis, has been shown to be expressed by human sebocytes. In this study, we identified galectin-12 as an important intracellular regulator of sebocyte proliferation. Galectin-12 knockdown in the human SZ95 sebocyte line suppressed cell proliferation, and its overexpression promoted cell cycle progression. Inhibition of galectin-12 expression reduced the androgen-induced SZ95 sebocyte proliferation and growth of sebaceous glands in mice, respectively. The mRNA expression of the key cell cycle regulators cyclin A1 (CCNA1) and cyclin-dependent kinase 2CDK2 was reduced in galectin-12 knockdown SZ95 sebocytes, suggesting a pathway of galectin-12 regulation of sebocyte proliferation. Further, galectin-12 enhanced peroxisome proliferator-activated receptor gamma (PPARγ) expression and transcriptional activity in SZ95 sebocytes, consistent with our previous studies in adipocytes. Rosiglitazone, a PPARγ ligand, induced CCNA1 levels, suggesting that galectin-12 may upregulate CCNA1 expression via PPARγ. Our findings suggest the possibility of targeting galectin-12 to treat human sebaceous gland hyperfunction and androgen-associated skin diseases.

Galectin-1 (Gal-1), a 14kDa carbohydrate-binding protein of the galectin family found in humans, affects intracellular signaling pathways upon interaction with β-galactosides on cell-surface, cytosol, and nucleus. The structural information reveals that it consists of a monovalent dimer composed of subunits with one Carbohydrate Recognition Domain (CRD), which is the main active site to interact with various glycoproteins, and carbohydrates in the body to regulate cellular functions. Gal-1 contributes towards different events associated with cancer biology, including tumor transformation, cell cycle regulation, apoptosis, cell adhesion, migration, and inflammation. The extracellular existence and function of Gal-1 have been well-established, and it is known to express in many tumor types, including astrocytoma, melanoma, prostate, colon, bladder, and ovarian carcinomas, etc. Several studies suggested the upregulation of Gal-1 levels in multiple cancer cells. Thus, Gal-1 is a promising molecular target for the development of new therapeutic tools. The present review focuses on the functions of Gal-1 in tumor progression in multiple cancers and its structural insights.

NOD-, LRR-, and pyrin domain–containing protein 3 (NLRP3) inflammasome has been implicated in a variety of inflammatory disorders, and its activation should be tightly controlled to avoid detrimental effects. NLRP3 protein expression is considered as the rate-limiting step for NLRP3 inflammasome activation. In this study, we show that galectin-9 (encoded by lgals9) attenuated NLRP3 inflammasome activation by promoting the protein degradation of NLRP3 in primary peritoneal macrophages of C57BL/6J mice. Lgals9 deficiency enhances NLRP3 inflammasome activation and promotes NLRP3-dependent inflammation in C57BL/6J mice in vivo. Mechanistically, galectin-9 interacts with NLRP3, promotes the formation of NLRP3/p62 (an autophagic cargo receptor, also known as SQSTM1) complex, and thus facilitates p62-dependent autophagic degradation of NLRP3 in primary peritoneal macrophages of C57BL/6J mice and HEK293T cells. Therefore, we identify galectin-9 as an “eat-me” signal for selective autophagy of NLRP3 and uncover the potential roles of galectins in controlling host protein degradation. Furthermore, our work suggests galectin-9 as a priming therapeutic target for the diseases caused by improper NLRP3 inflammasome activation.

The gene for galectin-13 (Gal-13, placental protein 13) is only present in primates, and its low expression level in maternal serum may promote preeclampsia. In the present study, we used pull-down experiments and biolayer interferometry to assess the interaction between Gal-13 and actin. These studies uncovered that human Gal-13 (hGal-13) and Saimiri boliviensis boliviensis (sGal-13) strongly bind to α- and β-/γ-actin, with Ca2+ and adenosine triphosphate, significantly enhancing the interactions. This in turn suggests that h/sGal-13 may inhibit myosin-induced contraction when vascular smooth muscle cells undergo polarization. Here, we solved the crystal structure of sGal-13 bound to lactose and found that it exists as a monomer in contrast to hGal-13 which is a dimer. The distribution of sGal-13 in HeLa cells is similar to that of hGal-13, indicating that monomeric Gal-13 is the primary form in cells. Even though sGal-13 binds to actin, hGal-13 ligand-binding site mutants do not influence hGal-13/actin binding, whereas the monomeric mutant C136S/C138S binds to actin more strongly than the wild-type hGal-13. Overall, our study demonstrates that monomeric Gal-13 binds to actin, an interaction that is independent of the galectin canonical ligand-binding site.

Galectin-3 (Gal-3) is the most studied member of the animal galectin family, which comprises β-galactoside-binding lectins and participates in several cellular events. Its expression in cells involved in innate and adaptive immunity is related to anti- and proinflammatory functions, signaling an important role in inflammatory, infectious, and tumorigenesis processes. Mice deficient in Gal-3 exhibit important phenotypes, but it is unclear whether these phenotypes reflect an impairment of the functions of this protein. Gal-3 plays an important role in modulating the immune response to different pathogenic microorganisms. However, the role of Gal-3 in immunity to infection is still poorly understood. Therefore, we investigated the effects of Gal-3 deletion on the expression of genes involved in the innate immune response in the lungs, spleens, and brains of Gal-3 KO mice. Gene profiling expression analysis suggested that Gal-3 deletion resulted in differentially modulated expression of the genes encoding beta-glucan, mannose and chitin-responsive pattern recognition receptors, signal transduction, inflammation, and phagocytosis. Our data thus suggest the importance of Gal-3 expression in the host innate immune system.

Galectin-3 (Gal-3) is a β-galactoside binding protein associated with many disease pathologies, including chronic inflammation and fibrogenesis. It has been implicated in the disease severity of NASH, although its precise role is unknown. Inhibition of Gal-3 has shown to improve and prevent fibrosis progression and has now reached phase III clinical trial in NASH patients.This discusses the role of Gal-3 in NASH. It brings together the current findings of Gal-3 in NASH and hepatic fibrosis by analyzing recent data from animal model studies and clinical trials.Gal-3 inhibitors, in particular, Belapectin (GR-MD-02), have shown promising results for NASH with advanced fibrosis. In a phase 2 trial, Belapectin did not meet the primary endpoint. However, a sub-analysis of Belapectin among a separate group of patients without esophageal varices showed 2 mg/kg of GR-MD-02 reduced HVPG and the development of new varices. A subsequent study is under way, aiming to replicate the positive findings in phase 2 and demonstrate greater efficacy. If Belapectin is shown to be effective, it will be coupled with other drugs that target steatohepatitis to maximize efficacy and disease reversal.

Galectins are animal lectins that recognize carbohydrates and play important roles in maintaining cellular homeostasis. Recent studies have indicated that under a variety of challenges, intracellular galectins bind to host glycans displayed on damaged endocytic vesicles and accumulate around these damaged organelles. Accumulated galectins then engage cellular proteins and subsequently control cellular responses, such as autophagy. In this review, we have summarized the stimuli that lead to the accumulation of galectins, the molecular mechanisms of galectin accumulation, and galectin-mediated cellular responses, and elaborate on the differential regulatory effects among galectins.

Galectins, a family of evolutionary conserved β-galactoside-binding proteins, have been characterized in a wide range of species. Many reports have indicated vital roles of galectins in innate immunity, especially in the mucosal tissues against infection. However, the systematic identification of galectin gene family is still lacking in teleost. Here, we characterized the galectin gene family and investigated their expression profiles post bacterial challenge in turbot (Scophthalmus maximus L.). In this study, a total of 13 galectin genes were characterized in turbot, phylogenetic analyses revealed their strong relationships to half smooth tongue sole and puffer fish, and syntenic analyses confirmed the orthology suggested by the phylogenetic analysis. In addition, the copy number of galectin genes is similar across a broad spectrum of species from fish to amphibians, birds, and mammals, ranging from 8 to 16 genes. Furthermore, the galectin genes were widely expressed in all the examined turbot tissues, and most of the galectin genes were strongly expressed in mucosal tissues (skin, gill and intestine). Moreover, majority of the galectin genes were significantly regulated after Vibrio anguillarum infection in the intestine, gill and skin, suggesting that galectins were involved in the mucosal immune response to V. anguillarum infection in turbot. In addition, subcellular localization analysis showed lgals3a was distributed in the cytoplasm and nucleus. However, the knowledge of galectins are still limited in teleost species, further studies should be carried out to better characterize its detailed roles in teleost mucosal immunity.

Background Excretory-secretory (ES) products are crucial in maintaining helminths in the host. Consequently, the proteins of ES are potential vaccine molecules and potential therapeutic agents for autoimmune diseases. Heligmosomoides polygyrus bakeri, a gastrointestinal parasite of mice, is a model of hookworm infection in humans. ES produced by both sexes of H. polygyrus bakeri L4 stage cultured separately shows different immunomodulatory properties than ES obtained when both sexes are cultured together. Accordingly, the objective of this study was to identify and compare the excretory-secretory molecules from single-sex and mixed cultures. Methods The composition of ES of male and female L4 stage nematodes in the presence (cultured together) or absence (cultured alone) of the opposite sex was examined. Proteins were identified using mass spectrometry. The functions of identified proteins were explored with Blast2GO. Results A total of 258 proteins derived from mixed larval culture in the presence of sex pheromones were identified, 160 proteins from pure female cultures and 172 from pure male cultures. Exposure of nematodes to the sex pheromones results in abundant production of proteins with immunomodulatory properties such as Val proteins, acetylcholinesterases, TGF-β mimic 9 and HpARI. Proteins found only in ES from mixed larval cultures were TGF-β mimics 6 and 7 as well as galectin. Conclusions The presence of the opposite sex strongly influences the composition of ES products, probably by chemical (pheromone) communication between individuals. However, examination of the composition of ES from various conditions gives an opportunity for searching for new potentially therapeutic compounds and anthelminthics as well as components of vaccines. Manipulation of the nematode environment might be important for the studies on the immunomodulatory potential of nematodes. Graphical Abstract

Galectins are a family of proteins that bind β-galactosides and play key roles in a variety of cellular processes including host defence. They have been well studied in hosts but less so in gastrointestinal nematodes. Both host and parasite galectins are present in the gastrointestinal tract following infection. Parasite galectins can both bind antibody, especially highly glycosylated IgE and be bound by antibody. Parasite galectins may act as molecular sponges that soak up antibody. Host galectins promote mast cell degranulation while parasite galectins inhibit degranulation. Host and parasite galectins can also bind mucins and influence mucus viscosity. As the protective response against gastrointestinal nematode infection is partly dependent on IgE mediated mast cell degranulation and mucus, the interactions between host and parasite galectins play key roles in determining the outcome of infection.

Multiple clinical trials have shown that monoclonal antibodies (mAbs) against programmed death‐ligand 1 (PD‐1/PD‐L1) can benefit patients with lung cancer by increasing their progression‐free survival and overall survival. However, a significant proportion of patients do not respond to anti‐PD‐1/PD‐L1 mAbs. In the present study, we investigated whether galectin (Gal)‐3 inhibitors can enhance the antitumor effect of PD‐L1 blockade. Using the NSCLC‐derived cell line A549, we examined the expression of Gal‐3 in lung cancer cells under hypoxic conditions and investigated the regulatory effect of Gal‐3 on PD‐L1 expression, which is mediated by the STAT3 pathway. We also explored whether Gal‐3 inhibition can facilitate the cytotoxic effect of T cells induced by PD‐L1 blockade. The effects of combined use of a Gal‐3 inhibitor and PD‐L1 blockade on tumor growth and T‐cell function were also investigated, and we found that hypoxia increased the expression and secretion of Gal‐3 by lung cancer cells. Gal‐3 increased PD‐L1 expression via the upregulation of STAT3 phosphorylation, and administration of a Gal‐3 inhibitor enhanced the effect of PD‐L1 blockade on the cytotoxic activity of T cells against cancer cells in vitro. In a mouse xenograft model, the combination of a Gal‐3 inhibitor and PD‐L1 blockade synergistically suppressed tumor growth. Furthermore, the administration of a Gal‐3 inhibitor enhanced T‐cell infiltration and granzyme B release in tumors. Collectively, our results show that Gal‐3 increases PD‐L1 expression in lung cancer cells and that the administration of a Gal‐3 inhibitor as an adjuvant enhanced the antitumor activity of PD‐L1 blockade., Galectin (Gal)‐3 is involved in the immune response, and highly overexpressed and secreted by lung cancer cells. This study showed that the increased expression of Gal‐3 was induced by hypoxia, which then contributed to immune suppression through the STAT3 pathway in lung cancer. Furthermore, a Gal‐3 inhibitor enhanced the antitumor effect by PD‐L1 blockade through promoting T‐cell infiltration in lung cancer.

Adult progenitor cell populations typically exist in a quiescent state within a controlled niche environment. However, various stresses or forms of damage can disrupt this state, which often leads to dysfunction and aging. We built a glucocorticoid (GC)-induced liver damage model of mice, found that GC stress induced liver damage, leading to consequences for progenitor cells expansion. However, the mechanisms by which niche factors cause progenitor cells proliferation are largely unknown. We demonstrate that, within the liver progenitor cells niche, Galectin-3 (Gal-3) is responsible for driving a subset of progenitor cells to break quiescence. We show that GC stress causes aging of the niche, which induces the up-regulation of Gal-3. The increased Gal-3 population increasingly interacts with the progenitor cell marker CD133, which triggers focal adhesion kinase (FAK)/AMP-activated kinase (AMPK) signaling. This results in the loss of quiescence and leads to the eventual stemness exhaustion of progenitor cells. Conversely, blocking Gal-3 with the inhibitor TD139 prevents the loss of stemness and improves liver function. These experiments identify a stress-dependent change in progenitor cell niche that directly influence liver progenitor cell quiescence and function.

Our previous study has recorded that the recombinant protein of Nile tilapia (Oreochromis niloticus) galectin-2 (rOnGal-2) can enhance immune response against Streptococcus agalactiae (S.agalactiae) infection in vitro. In this study, we further explored the effects of OnGal-2 in immune response against bacterial infection in vivo. The administration of rOnGal-2 could improve serum antibacterial activity (ALKP, ACP, and LZM) and antioxidant capacity (CAT, POD, and SOD). After S. agalactiae infection, rOnGal-2 injection could reduce bacterial burden and decrease tissue damage in head kidney, spleen, and liver of tilapia. Also, rOnGal-2 regulated the inflammatory-related genes expression including IL-6, IL-8 and IL-10 during bacterial infection. Furthermore, rOnGal-2 administration could increase the relative percentage survival of tilapia infected with S.agalactiae. Taken together, our results indicate that OnGal-2 can protect fish from bacterial infection through reducing bacterial burden, impairing tissue damage and modulating anti-bacterial immune response, which also can be applied as a potential vaccine adjuvant in O.niloticus culture.

Femoral glands secrete a wax-like substance on the inner side of lizard hind legs, which is thought to function as a mode of chemical communication. Though the minor volatile fraction is well studied, the major protein fraction remains enigmatic. Here, we use proteomics to analyze proteins in femoral gland secretions of the Galápagos marine iguana. Although we found no evidence for proteins and peptides involved in chemical communication, we found several immune-regulatory proteins which also demonstrate anti-microbial functions. Accordingly, we show that femoral gland proteins and peptides function as a barrier against microbial infection and may prevent the rapid degradation of volatile substances., Graphical Abstract Highlights • Comprehensive transcriptome and proteome of the Galápagos Marine Iguana. • Analysis of femoral gland proteome. • Identification of antimicrobial activity in femoral gland secretions., Communication between individuals via molecules, termed chemosignaling, is widespread among animal and plant species. However, we lack knowledge on the specific functions of the substances involved for most systems. The femoral gland is an organ that secretes a waxy substance involved in chemical communication in lizards. Although the lipids and volatile substances secreted by the femoral glands have been investigated in several biochemical studies, the protein composition and functions of secretions remain completely unknown. Applying a proteomic approach, we provide the first attempt to comprehensively characterize the protein composition of femoral gland secretions from the Galápagos marine iguana. Using samples from several organs, the marine iguana proteome was assembled by next-generation sequencing and MS, resulting in 7513 proteins. Of these, 4305 proteins were present in the femoral gland, including keratins, small serum proteins, and fatty acid-binding proteins. Surprisingly, no proteins with discernible roles in partner recognition or inter-species communication could be identified. However, we did find several proteins with direct associations to the innate immune system, including lysozyme C, antileukoproteinase (ALP), pulmonary surfactant protein (SFTPD), and galectin (LGALS1) suggesting that the femoral glands function as an important barrier to infection. Furthermore, we report several novel anti-microbial peptides from the femoral glands that show similar action against Escherichia coli and Bacillus subtilis such as oncocin, a peptide known for its effectiveness against Gram-negative pathogens. This proteomics data set is a valuable resource for future functional protein analysis and demonstrates that femoral gland secretions also perform functions of the innate immune system.

Background As a critical cellular component in the hepatic stem cell niche, hepatic stellate cells (HSCs) play critical roles in regulating the expansion of hepatic stem cells, liver regeneration, and fibrogenesis. However, the signaling of HSCs, particularly that involved in promoting hepatic stem cell expansion, remains unclear. While the overexpression of galectins has been identified in regenerating liver tissues, their involvement in cell-cell interactions between HSCs and hepatic stem cells remains to be elucidated. Methods To generate a liver regeneration rat model and establish a hepatic oval cell microenvironment as a stem cell niche, 2-acetylaminofluorene treatment plus partial hepatectomy was performed. Immunofluorescence staining was conducted to detect the emergence of hepatic stem cells and their niche. Liver parenchymal cells, non-parenchymal cells, and HSCs were isolated for gene and protein expression analysis by qPCR or western blotting. To evaluate the effect of galectins on the colony-forming efficiency of hepatic stem cells, c-Kit−CD29+CD49f+/lowCD45−Ter-119− cells were cultured with recombinant galectin protein, galectin antibody, galectin-producing HSCs, and galectin-knockdown HSCs. Results Following liver injury, the cytokeratin 19+ ductal cells were robustly induced together with the emergence of OV6+CD44+CD133+EpCAM+ hepatic stem cells. The activated desmin+ HSCs were recruited around the periportal area and markedly enriched in the galectin-positive domain compared to the other non-parenchymal cells. Notably, the HSC fraction isolated from regenerating liver was accompanied by dramatically elevated gene and protein expression of galectins. Hepatic stem cells co-cultured with HSCs significantly enhanced colony-forming efficiency. Conversely, single or double knockdown of galectin-1 and galectin-3 led into a significant function loss, impaired the co-cultured hepatic stem cells to attenuated colony size, inhibited colony frequency, and reduced total cell numbers in colonies. On the other hand, the promotive function of galectins was further confirmed by recombinant galectin protein supplementation and galectins blocking antibodies. Conclusions Our findings, for the first time, demonstrated that galectins from activated HSCs contribute to hepatic stem cell expansion during liver regeneration, suggesting that galectins serve as important stem cell niche components.

Intracerebral hemorrhage (ICH) is a devastating disease with high rates of mortality and morbidity. Galactose lectin-9 (Gal-9) belongs to the family of β-galactoside-binding lectins, which has been shown to play a vital role in immune tolerance and inflammation. However, the function of Gal-9 in ICH has not been fully studied in details. Several experiments were carried out to explore the role of Gal-9 in the late period of ICH. Primarily, ICH models were established in male adult Sprague Dawley (SD) rats. Next, the relative protein levels of Gal-9 at different time points after ICH were examined and the result showed that the level of Gal-9 increased and peaked at the 7th day after ICH. Then we found that when the content of Gal-9 increased, both the number of M2-type microglia and the corresponding anti-inflammatory factors also increased. Through co-immunoprecipitation (CO-IP) analysis, it was found that Gal-9 combines with Toll-like receptor-4 (TLR-4) during the period of the recovery after ICH. TUNEL staining and Fluoro-Jade B staining (FJB) proved that the amount of cell death decreased with the increase of Gal-9 content. Additionally, several behavioral experiments also demonstrated that when the level of Gal-9 increased, the motor, sensory, learning, and memory abilities of the rats recovered better compared to the ICH group. In short, this study illustrated that Gal-9 takes a crucial role after ICH. Enhancing Gal-9 could alleviate brain injury and promote the recovery of ICH-induced injury, so that Gal-9 may exploit a new pathway for clinical treatment of ICH.

Galectin-9, as one of the important PRRs in host, could initiate the immune defense responses through recognizing and binding PAMPs on the surface of invading microorganisms. In this study, a new galectin-9 cDNA was identified and characterized in Qihe crucian carp Carassius auratus (named as CaGal-9). The complete cDNA sequence of CaGal-9 was 1318 bp, with an open reading frame (ORF) of 963 bp encoding 320 amino acids. The predicted CaGal-9 protein contained two non-identical carbohydrate recognition domains (CRDs), which possessed the representative motifs H-NPR and WG-EER to bind with β-galactoside. Based on the RT-qPCR detection, CaGal-9 was ubiquitously expressed at mRNA level in various tested tissues, and predominately expressed in spleen. Upon Aeromonas hydrophila and poly I: C challenge, the expressions of CaGal-9 were remarkably up-regulated in liver, spleen, kidney and head kidney in a time-depended manner. The recombinant CaGal-9 (rCaGal-9), purified from Escherichia coli BL21 (DE3), exhibited strong binding ability with lipopolysaccharide (LPS), peptidoglycan (PGN) and β-Glucan, as well as the examined microorganisms including fungus, Gram-negative bacteria, and Gram-positive bacteria. With regard to the agglutinating activity of rCaGal-9, it could agglutinate erythrocytes of rabbit and crucian carp, and the examined microorganisms. Taken together, in this study, it was suggested that CaGal-9 could play an important role in immune defense against pathogenic microorganisms in C. auratus, which functions as an important PRR to recognize PAMPs and agglutinate pathogenic microorganisms.

Galectins are a family of glycan-binding molecules with a characteristic affinity for ß-D-glycosides that mediate a variety of important cellular functions, including immune and inflammatory responses. Galectin-11 (LGALS-11) has been recently identified as a mediator induced specifically in animals against gastrointestinal nematodes and can interfere with parasite growth and development. Here, we report that at least two natural genetic variants of LGALS-11 exist in sheep, and demonstrate fundamental differences in anti-parasitic activity, correlated with their ability to dimerise. This study improves our understanding of the role of galectins in the host immune and inflammatory responses against parasitic nematodes and provides a basis for genetic studies toward selective breeding of animals for resistance to parasites., Sakthivel et al. report two natural genetic variants of galectin-11 in sheep and demonstrate that their ability to dimerise correlates with the differences in their anti-parasitic activity that triggers larval arrest. This study provides a basis for genetic studies toward selective breeding of animals to improve their resistance to parasites.

Background/purpose Eosinophils are recruited to the brain of mice after infection with Angiostrongylus canonensis. Several factors produced by infected mice are well known playing the role to chemoattract eosinophils from the blood into the brain. The purpose of this study is to investigate whether Angiostronylus cantonensis young-adult worms (AcYA) have components which have eosinophilic chemotactic activity. Methods Eosinophil chemotactic activity of AcYA was tested by Boyden blind-well chamber technique. The components of AcYA were analysed by SDS-PAGE and Mass spectrometry. Furthermore, galectin-9 in the cerebrospinal fluid (CSF) of infected mice and galectin-9-like in AcYA were measured by ELISA technic and also were recognized by western blot analysis respectively. Results Excretory-secretory products of AcYA did not show eosinophil chemotactic activity. However, the extracts of AcYA showed protein concentration-dependent eosinophil chemotactic activity and reached the peak at the 24 μg/ml. The eosinophil chemotactic activity was significantly reduced by lactose. The components of AcYA at molecular weights of approximatively 15 kDa and 35 kDa showed several galectins component in Mass spectrometric analysis. Furthermore, galectin-9-like in AcYA was recognized by ELISA and western blot analysis. In parallel with increase of galectin-9 in the CSF, eosinophils were also significantly increased in mouse after infected with A. cantonensis. Conclusion Galectin-9-like in AcYA and galectin-9 in mouse CSF were confirmed demonstrating eosinophil chemotactic activity both in vitro study and in the infection of mouse in this study.

Hepatic diseases include all diseases that occur in the liver, including hepatitis, cirrhosis, hepatocellular carcinoma, etc. Hepatic diseases worldwide are characterized by high incidences of digestive system diseases, which present with subtle symptoms, are difficult to treat and have high mortality. Galectins are β-galactoside-binding proteins that have been found to be aberrantly expressed during hepatic disease progression. An increasing number of studies have shown that abnormal expression of galectins is extensively involved in hepatic diseases, such as hepatocellular carcinoma (HCC), liver cirrhosis, hepatitis and liver fibrosis. Galectins function as intracellular and extracellular hepatic disease regulators mainly through the binding of their carbohydrate recognition domain to glycoconjugates expressed in hepatocytes. In this review, we summarize current research on the various roles of galectins in cirrhosis, hepatitis, liver fibrosis and HCC, which may provide a preliminary theoretical basis for the exploration of new targets for the treatment of hepatic diseases.

Hepatocytes are the targets in autoimmune hepatitis (AIH) that results in T cell-dependent liver injury. However, hepatocytes may also affect the hepatic T cells in AIH, but the underlying mechanisms are not fully understood. Here we report that hepatocytes could secrete galectin-9 (Gal-9) to suppress the intrahepatic production of Th1 cytokine IFN-γ and restrict AIH development, but hepatocyte damage resulted in opposite effects due to release of TLR2/4 ligands that promoted the intrahepatic production of IL-1β, IL-6, and IL-12. Through Tim-3, Gal-9 could efficiently suppress the intrahepatic T cell activation despite presence of TLR2/4 ligands, thus attenuating Th1 response in AIH. Intriguingly, intrahepatic IL-6/IL-12 suppressed the effect of TGF-β on Treg cells. Therefore, in AIH, Gal-9 promoted Foxp3 expression and function of hepatic Treg cells through TL1A signaling, although Treg function was still impaired, compared with that in naive state. Due to its promoting effect on Treg function, together with its effect on T effector cells in a Tim-3-independent way, Gal-9 could attenuate intrahepatic IFN-γ production by hindering the increase of hepatic CD4+CD43+ T cells resulting from extrahepatic T cell activation. TLR2/4 ligands attenuated the effects of Gal-9 on Treg cells and CD4+CD43+ T cells by increasing intrahepatic IL-6 and IL-12. Blocking TLR2/4 ligands could efficiently suppress intrahepatic IFN-γ production, liver injury, and hepatic fibrosis. These findings suggest that hepatocytes paradoxically affect Th1 response in AIH due to Gal-9 expression and TLR2/4 ligands release, and that targeting TLR2/4 signaling may provide an important approach in the therapeutic strategy for AIH.

Introduction: Nasopharyngeal carcinoma (NPC) is a major public health problem in several countries, especially those in Southeast Asia and North Africa. In its typical poorly differentiated form, the Epstein-Barr virus (EBV) genome is present in the nuclei of all malignant cells with restricted expression of a few viral genes. The malignant phenotype of NPC cells results from the influence of these viral products in combination with cellular genetic, epigenetic and functional alterations. With regard to host/tumor interactions, NPC is a remarkable example of immune escape in the context of a hot tumor.Areas covered: This article has an emphasis on emerging therapeutic targets that are considered upstream or at an early stage of clinical application. It examines targets related to cellular oncogenic alterations, latent EBV infection and tumor interactions with the immune system.Expert opinion: There is a remarkable emergence of new agents that target EBV products. The clinical application of these agents would benefit from a systematic and comprehensive molecular classification of NPCs and from easy access to pre-clinical models in public repositories. There is a strong rationale for more investigations on the potential of immune modulators, especially those related to NK cells.

Galectins belong to the family of carbohydrate-binding proteins and play major roles in the immune and inflammatory responses of both vertebrates and invertebrates. In the present study, one novel galectin-1 protein named AjGal-1 was identified from Apostichopus japonicas with an open reading frame of 1179 bp encoding a polypeptide of 392 amino acids. The deduced amino acids sequence of AjGal-1 contained three carbohydrate recognition domains (CRDs) which shared 34-37% identity with that of other galectin proteins from echinodermata, fishes, and birds. In the phylogenetic tree, AjGal-1 was closely clustered with galectins from Mesocentrotus nudus and Paracentrotus lividus. The mRNA transcripts of AjGal-1 were ubiquitously expressed in all the detected tissues, including gut, longitudinal muscle, gonad, coelomocytes, respiratory tree, tentacle and body wall, with the highest expression level in coelomocytes. After Vibrio splendidus stimulation, the mRNA expression levels of AjGal-1 in coelomocytes were significantly increased at 6 and 12 h (P 0.01) compared with that in control group, and went back to normal level at 72 h. The recombinant protein of AjGal-1 (rAjGal-1) could bind various PAMPs including d-galactose, lipopolysaccharide (LPS), peptidoglycan (PGN) and mannose (Man), and exhibited the highest affinity to d-galactose. Meanwhile, rAjGal-1 could also bind and agglutinate different kinds of microorganisms, including gram-negative bacteria (V. splendidus and Escherichia coli), gram-positive bacteria (Micrococus leteus), and fungi (Pichia pastoris). rAjGal-1 also exhibited anti-microbial activity against V. splendidus and E. coli. All these results suggested that AjGal-1 could function as an important PRR with broad spectrum of microbial recognition and anti-microbial activity against the invading pathogen in A. japonicas.

The concept of biomedical significance of the functional pairing between tissue lectins and their glycoconjugate counterreceptors has reached the mainstream of research on the flow of biological information. A major challenge now is to identify the principles of structure-activity relationships that underlie specificity of recognition and the ensuing post-binding processes. Toward this end, we focus on a distinct feature on the side of the lectin, i.e. its architecture to present the carbohydrate recognition domain (CRD). Working with a multifunctional human lectin, i.e. galectin-3, as model, its CRD is used in protein engineering to build variants with different modular assembly. Hereby, it becomes possible to compare activity features of the natural design, i.e. CRD attached to an N-terminal tail, with those of homo- and heterodimers and the tail-free protein. Thermodynamics of binding disaccharides proved full activity of all proteins at very similar affinity. The following glycan array testing revealed maintained preferential contact formation with N-acetyllactosamine oligomers and histo-blood group ABH epitopes irrespective of variant design. The study of carbohydrate-inhibitable binding of the test panel disclosed up to qualitative cell-type-dependent differences in sections of fixed murine epididymis and especially jejunum. By probing topological aspects of binding, the susceptibility to inhibition by a tetravalent glycocluster was markedly different for the wild-type vs the homodimeric variant proteins. The results teach the salient lesson that protein design matters: the type of CRD presentation can have a profound bearing on whether basically suited oligosaccharides, which for example tested positively in an array, will become binding partners in situ. When lectin-glycoconjugate aggregates (lattices) are formed, their structural organization will depend on this parameter. Further testing (ga)lectin variants will thus be instrumental (i) to define the full range of impact of altering protein assembly and (ii) to explain why certain types of design have been favored during the course of evolution, besides opening biomedical perspectives for potential applications of the novel galectin forms. Open Access funding provided by Projekt DEAL. We gratefully acknowledge inspiring discussions with Drs. B. Friday, A. Leddoz and A. W. L. Nose, valuable input during the review process and generous fnancial support by an NIH Grant (No. CA242351; to M.C.). peer-reviewed

Secreted animal lectins of the galectin family are key players in cancer growth and metastasis. Here we show that galectin-8 (gal-8) induces the expression and secretion of cytokines and chemokines such as SDF-1 and MCP-1 in a number of cell types. This involves gal-8 binding to a uPAR/LRP1/integrin complex that activates JNK and the NFkB pathway. Cytokine and chemokine secretion, induced by gal-8, promotes migration of cancer cells toward cells treated with this lectin. Indeed, immune-competent gal-8 knockout (KO) mice express systemic lower levels of cytokines and chemokines while the opposite is true for gal-8 transgenic animals. Accordingly, gal-8 KO mice experience reduced tumor size and smaller and fewer metastatic lesions when injected with cancer cells. These results suggest the existence of a ‘vicious cycle’ whereby gal-8 secreted by the tumor microenvironment, promotes secretion of chemoattractants at the metastatic niche that promote further recruitment of tumor cells to that site. This study further implicate gal-8 in control of cancer progression and metastasis through its effects on the production of immunoregulatory cytokines.

Galectin-9 is a risk gene in inflammatory bowel disease. By transcriptomic analyses of ileal biopsies and PBMCs from inflammatory bowel disease patients, we identified a positive correlation between galectin-9 expression and colitis severity. We observed that galectin-9–deficient T cells were less able to induce T cell–mediated colitis. However, several mouse-based studies reported that galectin-9 treatment induces T cell apoptosis and ameliorates autoimmune diseases in an exogenously modulated manner, indicating a complicated regulation of galectin-9 in T cells. We found that galectin-9 is expressed mainly inside T cells, and its secreted form is barely detected under physiological conditions. Endogenous galectin-9 was recruited to immune synapses upon T cell activation. Moreover, proximal TCR signaling was impaired in galectin-9–deficient T cells, and proliferation of these cells was decreased through an intracellularly modulated manner. Th17 cell differentiation was downregulated in galectin-9–deficient T cells, and this impairment can be rescued by strong TCR signaling. Taken together, these findings suggest that intracellular galectin-9 is a positive regulator of T cell activation and modulates the pathogenesis of autoimmune diseases.

Adaptive immunity relies on the efficient recruitment of T cells from the blood into peripheral tissues. However, the current understanding of factor(s) coordinating these events is incomplete. Previous studies on galectin-9 (Gal-9), have proposed a functionally significant role for this lectin in mediating leukocyte adhesion and transmigration. However, very little is known about its function in T cell migration. Here, we have investigated the role of the Gal-9 on the migration behaviour of both human primary CD4+ and CD8+ T cells. Our data indicate that Gal-9 supports both CD4+ and CD8+ T cell adhesion and transmigration in a glycan dependent manner, inducing L-selectin shedding and upregulation of LFA-1 and CXCR4 expression. Additionally, when immobilized, Gal-9 promoted capture and firm adhesion of T cells under flow, in a glycan and integrin-dependent manner. Using an in vivo model, dorsal air pouch, we found that Gal-9 deficient mice display impaired leukocyte trafficking, with a reduction in pro-inflammatory cytokines/chemokines generated locally. Furthermore, we also demonstrate that Gal-9 inhibits the chemotactic function of CXCL12 through direct binding. In conclusion, our study characterises, for the first time, the capture, adhesion, and migration behaviour of CD4+ and CD8+ T cells to immobilised /endothelial presented Gal-9, under static and physiological flow conditions. We also demonstrate the differential binding characteristics of Gal-9 to T cell subtypes, which could be of potential therapeutic significance, particularly in the treatment of inflammatory-based diseases, given Gal-9 ability to promote apoptosis in pathogenic T cell subsets.

Due to their high biodiversity and adaptation to a mutable and challenging environment, aquatic lophotrochozoan animals are regarded as a virtually unlimited source of bioactive molecules. Among these, lectins, i.e., proteins with remarkable carbohydrate-recognition properties involved in immunity, reproduction, self/nonself recognition and several other biological processes, are particularly attractive targets for biotechnological research. To date, lectin research in the Lophotrochozoa has been restricted to the most widespread phyla, which are the usual targets of comparative immunology studies, such as Mollusca and Annelida. Here we provide the first overview of the repertoire of the secretory lectin-like molecules encoded by the genomes of six target rotifer species: Brachionus calyciflorus, Brachionus plicatilis, Proales similis (class Monogononta), Adineta ricciae, Didymodactylos carnosus and Rotaria sordida (class Bdelloidea). Overall, while rotifer secretory lectins display a high molecular diversity and belong to nine different structural classes, their total number is significantly lower than for other groups of lophotrochozoans, with no evidence of lineage-specific expansion events. Considering the high evolutionary divergence between rotifers and the other major sister phyla, their widespread distribution in aquatic environments and the ease of their collection and rearing in laboratory conditions, these organisms may represent interesting targets for glycobiological studies, which may allow the identification of novel carbohydrate-binding proteins with peculiar biological properties.

Lectins are a unique group of nonimmune carbohydrate-binding proteins or glycopro-teins that exhibit specific and reversible carbohydrate-binding activity in a non-catalytic manner. Lectins have diverse sources and are classified according to their origins, such as plant lectins, animal lectins, and fish lectins. Marine organisms including fish, crustaceans, and mollusks produce a myriad of lectins, including rhamnose binding lectins (RBL), fucose-binding lectins (FTL), mannose-binding lectin, galectins, galactose binding lectins, and C-type lectins. The widely used method of extracting lectins from marine samples is a simple two-step process employing a polar salt solution and purification by column chromatography. Lectins exert several immunomodulatory functions, including pathogen recognition, inflammatory reactions, participating in various hemocyte functions (e.g., agglutination), phagocytic reactions, among others. Lectins can also control cell prolifer-ation, protein folding, RNA splicing, and trafficking of molecules. Due to their reported biological and pharmaceutical activities, lectins have attracted the attention of scientists and industries (i.e., food, biomedical, and pharmaceutical industries). Therefore, this review aims to update current information on lectins from marine organisms, their characterization, extraction, and biofunctionali-ties. © 2022 by the authors. Licensee MDPI, Basel, Switzerland. Ural Federal University, UrFU The author O.N.K is grateful to the “Priority 2030” program of the Ural Federal University for support.

Galectins are a family of animal lectins with high affinity for &beta, galactosides. Galectins are able to bind to bacteria, and a few mammalian galectins are known to kill the bound bacteria. In fish, no galectins with direct bactericidal effect have been reported. In the present study, we identified and characterized a tandem repeat galectin-8 from tongue sole Cynoglossus semilaevis (designated CsGal-8). CsGal-8 possesses conserved carbohydrate recognition domains (CRDs), as well as the conserved HXNPR and WGXEE motifs that are critical for carbohydrate binding. CsGal-8 was constitutively expressed in nine tissues of tongue sole and up-regulated in kidney, spleen, and blood by bacterial challenge. When expressed in HeLa cells, CsGal-8 protein was detected both in the cytoplasm and in the micro-vesicles secreted from the cells. Recombinant CsGal-8 (rCsGal-8) bound to lactose and other carbohydrates in a dose dependent manner. rCsGal-8 bound to a wide range of gram-positive and gram-negative bacteria and was co-localized with the bound bacteria in animal cells. Lactose, fructose, galactose, and trehalose effectively blocked the interactions between rCsGal-8 and different bacteria. Furthermore, rCsGal-8 exerted potent bactericidal activity against some gram-negative bacterial pathogens by directly damaging the membrane and structure of the pathogens. Taken together, these results indicate that CsGal-8 likely plays an important role in the immune defense against some bacterial pathogens by direct bacterial interaction and killing.

Neutrophil trafficking is a key component of the inflammatory response. Here, we have investigated the role of the immunomodulatory lectin Galectin-9 (Gal-9) on neutrophil recruitment. Our data indicate that Gal-9 is upregulated in the inflamed vasculature of RA synovial biopsies and report the release of Gal-9 into the extracellular environment following endothelial cell activation. siRNA knockdown of endothelial Gal-9 resulted in reduced neutrophil adhesion and neutrophil recruitment was significantly reduced in Gal-9 knockout mice in a model of zymosan-induced peritonitis. We also provide evidence for Gal-9 binding sites on human neutrophils; Gal-9 binding induced neutrophil activation (increased expression of β2 integrins and reduced expression of CD62L). Intra-vital microscopy confirmed a pro-recruitment role for Gal-9, with increased numbers of transmigrated neutrophils following Gal-9 administration. We studied the role of both soluble and immobilized Gal-9 on human neutrophil recruitment. Soluble Gal-9 significantly strengthened the interaction between neutrophils and the endothelium and inhibited neutrophil crawling on ICAM-1. When immobilized, Gal-9 functioned as an adhesion molecule and captured neutrophils from the flow. Neutrophils adherent to Gal-9 exhibited a spread/activated phenotype that was inhibited by CD18 and CD44 neutralizing antibodies, suggesting a role for these molecules in the pro-adhesive effects of Gal-9. Our data indicate that Gal-9 is expressed and released by the activated endothelium and functions both in soluble form and when immobilized as a neutrophil adhesion molecule. This study paves the way for further investigation of the role of Gal-9 in leukocyte recruitment in different inflammatory settings.

Environmentally-mediated drug resistance in B-cell precursor acute lymphoblastic leukemia (BCP-ALL) significantly contributes to relapse. Stromal cells in the bone marrow environment protect leukemia cells by secretion of chemokines as cues for BCP-ALL migration towards, and adhesion to, stroma. Stromal cells and BCP-ALL cells communicate through stromal galectin-3. Here, we investigated the significance of stromal galectin-3 to BCP-ALL cells. We used CRISPR/Cas9 genome editing to ablate galectin-3 in stromal cells and found that galectin-3 is dispensable for steady-state BCP-ALL proliferation and viability. However, efficient leukemia migration and adhesion to stromal cells are significantly dependent on stromal galectin-3. Importantly, the loss of stromal galectin-3 production sensitized BCP-ALL cells to conventional chemotherapy. We therefore tested novel carbohydrate-based small molecule compounds (Cpd14 and Cpd17) with high specificity for galectin-3. Consistent with results obtained using galectin-3-knockout stromal cells, treatment of stromal-BCP-ALL co-cultures inhibited BCP-ALL migration and adhesion. Moreover, these compounds induced anti-leukemic responses in BCP-ALL cells, including a dose-dependent reduction of viability and proliferation, the induction of apoptosis and, importantly, the inhibition of drug resistance. Collectively, these findings indicate galectin-3 regulates BCP-ALL cell responses to chemotherapy through the interactions between leukemia cells and the stroma, and show that a combination of galectin-3 inhibition with conventional drugs can sensitize the leukemia cells to chemotherapy.

Endometritis is a major infectious disease affecting dairy development. MicroRNAs are recognized as critical regulators of the innate immune response. However, the role and mechanism of Bta-miR-24-3p in the development of endometritis are still unclear. This study aimed to investigate the effect of Bta-miR-24-3p on the inflammatory response triggered by lipopolysaccharide (LPS) and to clarify the possible mechanism. LPS-treated bovine endometrial epithelial cells (BEECs) were cultured to investigate the role of Bta-miR-24-3p. The expression levels of Bta-miR-24-3p were downregulated, and galectin-9 (LGALS9) were measured by quantitative real-time polymerase chain reaction. The LPS-induced inflammatory response was assessed by the elevated secretion of inflammatory cytokines measured by using enzyme-linked immunosorbent assay and quantitative real-time polymerase chain reaction. Activation of nuclear factor-κB (NF-κB) and TLR4 pathway was assessed by Western blot. The interaction between Bta-miR-24-3p and LGALS9 was validated by bioinformatics analysis and a luciferase reporter assay. LPS-induction in BEECs with Bta-miR-24-3p was overexpressed leads inhibition of pro-inflammatory cytokines, LGALS9 expression, and TLR4/NF-ĸB pathway deactivation. Knockdown of LGALS9 inhibited the LPS-induced inflammatory response in BEECs. LGALS9 was validated as a target of Bta-miR-24-3p. Cloned overexpression of LGALS9 failed to alter the effect of Bta-miR-24-3p on the inflammatory response in BEECs. Overall, Bta-miR-24-3p attenuated the LPS-induced inflammatory response via targeting LGALS9. The immunotherapeutic stabilisation of Bta-miR-24-3p could give a therapeutic option for endometritis and other disorders commonly associated with endometritis, suggesting a novel avenue for endometritis treatment.

Gout is caused by depositing monosodium urate (MSU) crystals within the articular area. The infiltration of neutrophils and monocytes drives the initial inflammatory response followed by lymphocytes. Interestingly, emerging evidence supports the view that in situ imbalance of T helper 17 cells (Th17)/regulatory T cells (Treg) impacts the subsequent damage to target tissues. Galectin-9 (Gal-9) is a modulator of innate and adaptive immunity with both pro- and anti-inflammatory functions, dependent upon its expression and cellular location. However, the specific cellular and molecular mechanisms by which Gal-9 modulates the inflammatory response in the onset and progression of gouty arthritis has yet to be elucidated. In this study, we sought to comprehensively characterise the functional role of exogenous Gal-9 in an in vivo model of MSU crystal-induced gouty inflammation by monitoring in situ neutrophils, monocytes and Th17/Treg recruited phenotypes and related cyto-chemokines profile. Treatment with Gal-9 revealed a dose-dependent reduction in joint inflammation scores, knee joint oedema and expression of different pro-inflammatory cyto-chemokines. Furthermore, flow cytometry analysis highlighted a significant modulation of infiltrating inflammatory monocytes (CD11b+/CD115+/LY6-Chi) and Th17 (CD4+/IL-17+)/Treg (CD4+/CD25+/FOXP-3+) cells following Gal-9 treatment. Collectively the results presented in this study indicate that the administration of Gal-9 could provide a new therapeutic strategy for preventing tissue damage in gouty arthritic inflammation and, possibly, in other inflammatory-based diseases.

Angiogenesis, the growth of new blood vessels out of existing vessels, is a complex and tightly regulated process. It is executed by the cells that cover the inner surface of the vasculature, i.e., the endothelial cells. During angiogenesis, these cells adopt different phenotypes, which allows them to proliferate and migrate, and to form tube-like structures that eventually result in the generation of a functional neovasculature. Multiple internal and external cues control these processes and the galectin protein family was found to be indispensable for proper execution of angiogenesis. Over the last three decades, several members of this glycan-binding protein family have been linked to endothelial cell functioning and to different steps of the angiogenesis cascade. This review provides a basic overview of our current knowledge regarding galectins in angiogenesis. It covers the main findings with regard to the endothelial expression of galectins and highlights their role in endothelial cell function and biology.

Glycan–lectin interactions play an essential role in different cellular processes. One of their main functions is involvement in the immune response to pathogens or inflammation. However, cancer cells and viruses have adapted to avail themselves of these interactions. By displaying specific glycosylation structures, they are able to bind to lectins, thus promoting pathogenesis. While glycan–lectin interactions promote tumor progression, metastasis, and/or chemoresistance in cancer, in viral infections they are important for viral entry, release, and/or immune escape. For several years now, a growing number of investigations have been devoted to clarifying the role of glycan–lectin interactions in cancer and viral infections. Various overviews have already summarized and highlighted their findings. In this review, we consider the interactions of the lectins MGL, DC-SIGN, selectins, and galectins in both cancer and viral infections together. A possible transfer of ways to target and disrupt them might lead to new therapeutic approaches in different pathological backgrounds.

Lysosomal damage activates AMPK, a regulator of macroautophagy/autophagy and metabolism, and elicits a strong ubiquitination response. Here we show that the cytosolic lectin LGALS9 detects lysosomal membrane breach by binding to lumenal glycoepitopes, and directs both the ubiquitination response and AMPK activation. Proteomic analyses have revealed increased LGALS9 association with lysosomes, and concomitant changes in LGALS9 interactions with its newly identified partners that control ubiquitination-deubiquitination processes. An LGALS9-inetractor, deubiquitinase USP9X, dissociates from damaged lysosomes upon recognition of lumenal glycans by LGALS9. USP9X’s departure from lysosomes promotes K63 ubiquitination and stimulation of MAP3K7/TAK1, an upstream kinase and activator of AMPK hitherto orphaned for a precise physiological function. Ubiquitin-activated MAP3K7/TAK1 controls AMPK specifically during lysosomal injury, caused by a spectrum of membrane-damaging or -permeabilizing agents, including silica crystals, the intracellular pathogen Mycobacterium tuberculosis, TNFSF10/TRAIL signaling, and the anti-diabetes drugs metformin. The LGALS9-ubiquitin system activating AMPK represents a novel signal transduction system contributing to various physiological outputs that are under the control of AMPK, including autophagy, MTOR, lysosomal maintenance and biogenesis, immunity, defense against microbes, and metabolic reprograming. ABBREVIATIONS: AMPK: AMP-activated protein kinase; APEX2: engineered ascorbate peroxidase 2; ATG13: autophagy related 13; ATG16L1: autophagy related 16 like 1; BMMs: bone marrow-derived macrophages; CAMKK2: calcium/calmodulin dependent protein kinase kinase 2; DUB: deubiquitinase; GPN: glycyl-L-phenylalanine 2-naphthylamide; LLOMe: L-leucyl-L-leucine methyl ester; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MAP3K7/TAK1: mitogen-activated protein kinase kinase kinase 7; MERIT: membrane repair, removal and replacement; MTOR: mechanistic target of rapamycin kinase; STK11/LKB1: serine/threonine kinase 11; TNFSF10/TRAIL: TNF superfamily member 10; USP9X: ubiquitin specific peptidase 9 X-linked

Galectins are a group of animal lectins characterized by their specificity for β-galactosides. Of these, galectin-2 (Gal-2) is predominantly expressed in the gastrointestinal tract. In the current study, we used a mouse gastric mucous fraction to investigate whether Gal-2 is secreted from epithelial cells and identify its potential ligands in gastric mucus. Gal-2 was detected in the mouse gastric mucous fraction and could be eluted from it by the addition of lactose. Affinity chromatography using recombinant mouse galectin-2 (mGal-2)-immobilized adsorbent and subsequent LC-MS/MS identified MUC5AC, one of the major gastric mucin glycoproteins, as a potential ligand of mGal-2. Furthermore, MUC5AC was detected in the mouse gastric mucous fraction by Western blotting, and recombinant mGal-2 was adsorbed to this fraction in a carbohydrate-dependent manner. These results suggested that Gal-2 and MUC5AC in mouse gastric mucus interact in a β-galactoside-dependent manner, resulting in a stronger barrier structure protecting the mucosal surface.

Hydrothermal vents and cold seep zones are two special habitats in the deep sea. These habitats are always dark, and have extreme temperatures (low or high), heavy metals and toxic substances (sulfide, methane). Vesicomyidae clams, which maintain endosymbionts in their gills, are common species in these two special zones and are thought to develop an efficacious immune system against unusual habitats. In the present study, a novel galectin (Apgalectin) was identified from the Vesicomyidae clam Archivesica packardana. The phylogenetic tree indicated that Apgalectin had two CRDs and was closely clustered with galectins from invertebrates, especially mollusks. A branch-site model showed that 9 positively selected sites (ω2 = 6.83950) were identified comparing to galectins from the Order Veneroida, implying a different function of Vesicomyidae galectins. A microbe binding assay showed that rApgalectin could bind to gram-positive bacteria, gram-negative bacteria and fungi. A PAMP binding assay indicated that Apgalectin could bind LPS, PGN, β-1,3-glucan, glucan from yeast and Poly I:C in dose-dependent manner. Apgalectin only agglutinated Micrococcus luteus and agglutination could be inhibited by galactose which demonstrated that Apgalectin might be involved in immune defense by recognizing and binding bacteria in a β-galactoside manner. Further experiments showed that Apgalectin might play an indirect effector role in the immune response because of its limited antibacterial spectrum. All analyses validated that Apgalectin from Archivesica packardana plays a variety of functions in immune responses and provided basal information for the immune study of deep-sea mollusks.

Galectins play diverse roles in pathophysiology of infectious diseases and cancers. Galectin-3 is one of the most studied family member and the only chimeric type lectin. Many aspects of its biogenesis, range of activities, and the disease-modifying potential particularly during microbial infections are yet to be known. We review our current understanding of these issues and also highlight gaps in better defining the immune modulatory potential of galectin-3 during different stages of host responsiveness when an infection sets in. Additionally, we discuss commonly used strategies to disrupt galectin-3 functions both extracellulalry and intracellularly. Existing and improved novel strategies could help fine-tune immune responses to achieve better prognosis of infectious diseases.

The emerging multifunctionality of galectins by specific protein-glycan/protein interactions explains the interest to determine their expression during embryogenesis. Complete network analysis of all seven chicken galectins (CGs) is presented in the course of differentiation of eye lens that originates from a single type of progenitor cell. It answers the questions on levels of expression and individual patterns of distribution. A qualitative difference occurs in the CG-1A/B paralogue pair, underscoring conspicuous divergence. Considering different cell phenotypes, lens fiber and also epithelial cells can both express the same CG, with developmental upregulation for CG-3 and CG-8. Except for expression of the lens-specific CG (C-GRIFIN), no other CG appeared to be controlled by the transcription factors L-Maf and Pax6. Studying presence and nature of binding partners for CGs, we tested labeled galectins in histochemistry and in ligand blotting. Mass spectrometric (glyco)protein identification after affinity chromatography prominently yielded four types of crystallins, N-CAM, and, in the cases of CG-3 and CG-8, N-cadherin. Should such pairing be functional in situ, it may be involved in tightly packing intracellular lens proteins and forming membrane contact as well as in gaining plasticity and stability of adhesion processes. The expression of CGs throughout embryogenesis is postulated to give meaning to spatiotemporal alterations in the local glycome.

The work described in this research communication aimed to investigate whether rumen-protected methionine (Met) supplementation during the periparturient period would affect the expression of galectins in blood-derived neutrophils, and secretion of galectins, IL (interleukin)-1β, IL-6, myeloperoxidase (MPO), and glucose in plasma. Because supplementation of rumen-protected Met would alleviate inflammation and oxidative stress during the peripartal period, we hypothesized that enhancing Met supply would benefit the innate immune response at least in part by altering the expression of galectin genes associated with neutrophil activity and inflammation. Galectins (Gal) have an immuno-modulating effect acting like cell-surface receptors whose activation often results in signaling cascades stimulating cells such as neutrophils. This study revealed an association between Met supplementation and galectin expression and secretion. This implies that galectin expression and secretion can be modulated by Met supplementation. Further studies are needed to evaluate the regulation of galectin gene expression for therapeutic and dietary intervention in the peripartal cow.

Fasciola hepatica is a globally distributed zoonotic trematode that causes fasciolosis in livestock, wildlife, ruminants and humans. Fasciolosis causes a significant economic impact on the agricultural sector and affects human health. Due to the increasing prevalence of triclabendazole resistance in F. hepatica, alternative treatment methods are required. Many protein antigens have been trialled as vaccine candidates with low success, however, the tegument of F. hepatica is highly glycosylated and the parasite-derived glycoconjugate molecules have been identified as an important mediator in host-parasite interactions and as prime targets for the host immune system. Galectin-11 (LGALS-11) and galectin-14 (LGALS-14) are two ruminant-specific glycan-binding proteins, showing upregulation in the bile duct of sheep infected with F. hepatica, which are believed to mediate host-parasite interaction and innate immunity against internal parasites. For the first known time, this study presents the ligand profile of whole worm and tegument extracts of F. hepatica that interacted with immobilised LGALS-11 and LGALS-14. LGALS-14 interacted with a total of 255 F. hepatica proteins. The protein which had the greatest interaction was identified as an uncharacterised protein which contained a C-type lectin domain. Many of the other proteins identified were previously trialled vaccine candidates including glutathione S-transferase, paramyosin, cathepsin L, cathepsin B, fatty acid binding protein and leucine aminopeptidase. In comparison to LGALS-14, LGALS-11 interacted with only 49 F. hepatica proteins and it appears to have a much smaller number of binding partners in F. hepatica. This is, to our knowledge, the first time host-specific lectins have been used for the enrichment of F. hepatica glycoproteins and this study has identified a number of glycoproteins that play critical roles in host-parasite interactions which have the potential to be novel vaccine candidates.

Oligodendrocytes (OLG) are the cells resident in the CNS responsible for myelination. OLG undergo a succession of morphological and molecular changes along several maturational stages. Galectin-3 (Gal-3) is a 25- to 35-KDa protein belonging to the family of carbohydrate-binding galectins, which bind to glycoconjugates containing β-galactosides. Gal-3 lacks a specific receptor and its binding is thus rather unspecific, as it depends on the cellular environment and the repertoire of glycomolecules at the time when Gal-3 is present. Our previous work revealed that recombinant Gal-3 (rGal-3)-treated OLG showed accelerated differentiation, evidenced by an increase in the number of mature cells to the detriment of immature ones and accelerated actin cytoskeleton dynamics. These changes were a consequence of rGal-3 influence on Akt, Erk 1/2, and β-catenin signaling pathways. Considering this previous evidence, the aim of this study was to identify the temporal window of rGal-3 action on the OLG lineage to induce OLG maturation by using specific single pulses of rGal-3 over the different maturational stages of OLG, and to unravel its main direct targets promoting OLG differentiation by mass spectrometry analysis. Our results reveal a key temporal window spanning between OPC and pre-OLG states in which rGal-3 action promotes OLG differentiation, and identify several targets for rGal-3 binding including proteins related to the cytoskeleton, signaling pathways, metabolism and intracellular trafficking, among others. These results highlight the relevance of Gal-3 in signaling pathways regulating oligodendroglial differentiation and support a potential therapeutic role for rGal-3 in demyelinating diseases such as multiple sclerosis.

29 p.-4 fig.-1 tab.-1 fig.supl., Introduction: The discoveries that sugars are a highly versatile platform to generate biochemical messages and that glycan-specific receptors (lectins) are a link between these signals and their bioactivity explain the interest in endogenous lectins such as galectins. Their analysis is a highly dynamic field. It is often referred to as being promising for innovative drug design., Area covered: We present a primer to the concept of the sugar code by glycan-(ga)lectin recognition, followed by a survey on galectin-3 (considering common and distinct features within this family of multifunctional proteins expressed at various cellular sites and cell types). Finally, we discuss strategies capable of blocking (ga)lectin activity, with an eye on current challenges and inherent obstacles., Expert opinion: The emerging broad profile of homeostatic and pathophysiological bioactivities stimulates further efforts to explore galectin (Gal-3) functionality, alone and then in mixtures. Like thoroughly assessing the pros and cons of blocking approaches for a multifunctional protein active at different sites, identifying a clinical situation, in which the galectin is essential in the disease process, will be critical.