Galectins in innate immunity: dual functions of host soluble beta-galactoside-binding lectins as damage-associated molecular patterns (DAMPs) and as receptors for pathogen-associated molecular patterns (PAMPs)

Decoding the multifaceted roles of galectins in self-defense

In this review, we aim to explore the multifaceted roles of galectins in host defense from a broader perspective, particularly regarding their functions when host integrity is compromised. Numerous comprehensive reviews on galectin functions in immunity have already been published. For researchers new to the field, this wealth of information may create an impression of galectins as proteins involved in a wide array of biological processes. Furthermore, due to the heterogeneity of galectin ligands, glycans, there is a risk of perceiving galectin-specific functions as ambiguous, potentially obscuring their core biological significance. To address this, we revisit foundational aspects, focusing on the significance of the recognition of galactose, a "late-comer" monosaccharide in evolutionary terms, provide an overview of galectin glycan binding specificity, with emphasis on the potential biological importance of each carbohydrate-recognition domain. We also discuss the biological implications of the galectin location paradox wherein these cytosolic lectins function in host defense despite their glycan ligands being synthesized in the secretory pathway. Additionally, we examine the role of galectins in liquid-liquid phase separation on membranes, which may facilitate their diverse functions in cellular responses. Through this approach, we aim to re-evaluate the complex and diverse biological roles of galectins in host defense.

Galectin-3 plays a key role in controlling infection by Toxoplasma gondii in human trophoblast cells and human villous explants

Galectin-3 (Gal-3) is a β-galactoside-binding lectin expressed in cells of the placental microenvironment. This lectin is involved in various biological processes, such as modulation of the immune system and control of parasitic illness. Toxoplasma gondii infection can lead to congenital transmission and cause miscarriages, prematurity and fetal anomalies. However, little is known about the role of Gal-3 in T. gondii infection in the placental microenvironment. This study aimed to unravel the underlying mechanisms of Gal-3 during T. gondii infection. For this purpose, we promoted the knockdown of Gal-3 expression by using RNA interference (RNAi) in BeWo cells or by using a synthetic inhibitor (GB1107) in human villous explants. We showed that the decreased Gal-3 expression in BeWo cells and human villous explants increases the invasion and proliferation of T. gondii probably by downregulating MIF and IL6 levels, highlighting thus the role of this lectin in modulating the immune response. Collectively, our study reveals Gal-3 as a promising target protein during congenital toxoplasmosis.

Efficiency of IL-6 in Early Prognosis and Follow-Up in Critically Ill Patients with Septic Shock

Background/Objectives: The aim of this study was to investigate the response of interleukin-6 (IL-6) during the first few hours of a patient's stay in the Intensive Care Unit (ICU) in a sample of critically ill patients with septic shock, compared to healthy subjects as controls. Additionally, the study examined the association of IL-6 with morbidity and mortality in these patients, as well as its relationship with biomarkers such as lactic acid, C-reactive protein (CRP) and procalcitonin (PCT). Methods: This was a prospective analytical study involving 28 critically ill patients with septic shock, monitored from ICU admission through to their first three days of stay. Demographic data, comorbidities and clinical information, including IL-6 and severity scores, were recorded. Results: IL-6 levels were significantly higher in patients with septic shock compared to healthy subjects (p < 0.001) upon admission. IL-6 levels decreased by the third day of ICU stay (p < 0.005). An association between IL-6 and mortality was observed (areas under the curve 0.826, confidence interval (CI) 95% 0.659-0.994, p < 0.008). Significant correlations between IL-6 and lactic acid (p < 0.009 and p < 0.018) and partial thromboplastin time (p < 0.004 and p < 0.007) were found on the first and third days, respectively. IL-6 was also the correlated with an anion gap at admission to the ICU (p < 0.009). Conclusions: In conclusion, this study suggests that IL-6 could be a valuable marker for early sepsis follow-up in ICU patients, particularly during the first 72 h of hospitalization, providing important prognostic information in patients with septic shock.

Development and validation of Galectin-3 and CVAI-based model for predicting cognitive impairment in type 2 diabetes

OBJECTIVE

The objective of this study is to develop a predictive model combining multiple indicators to quantify the risk of mild cognitive impairment (MCI) in T2DM patients.

METHODS

This study included Chinese T2DM patients who were hospitalized at Zhongda Hospital between November 2021 and May 2023. Clinical data, including demographics, medical history, biochemical tests, and cognitive status, were collected. Cognitive assessment was performed using neuropsychological tests, and MCI was diagnosed based on the Montreal Cognitive Assessment (MoCA) scores. The dataset was randomly divided into a training set and a validation set in a 7:3 ratio. Logistic regression analysis was conducted to identify factors influencing MCI in the training set. A nomogram-based scoring model was then developed by integrating these findings with high-risk clinical variables, and its performance was validated in the validation set.

RESULTS

In this study, T2DM patients were divided into a training set and a validation set in a 7:3 ratio. There were no significant differences in MCI incidence, demographics, or clinical characteristics between the two groups, confirming the appropriateness of model construction. In the training set, Galectin-3 and CVAI were significantly negatively correlated with cognitive function (MoCA and MMSE scores), and this negative correlation remained after adjusting for confounding variables. Logistic regression analysis revealed that age, CVAI, and Galectin-3 significantly increased the risk of MCI, while years of education had a protective effect. The constructed nomogram model, which integrated age, sex, education level, hypertension, CVAI, and Galectin-3 levels, exhibited high predictive performance (C-index of 0.816), with AUCs of 0.816 in the training set and 0.858 in the validation set, outperforming single indicators. PR curve analysis further validated the superiority of the nomogram model.

CONCLUSION

The straightforward, highly accurate, and interactive nomogram model developed in this study facilitate the early risk prediction of MCI in individuals with T2DM by incorporating Galectin-3, CVAI, and other common clinical risk factors.

Galectin-9 Mediates the Functions of Microglia in the Hypoxic Brain Tumor Microenvironment

Galectin-9 (Gal-9) is a multifaceted regulator of various pathophysiologic processes that exerts positive or negative effects in a context-dependent manner. In this study, we elucidated the distinctive functional properties of Gal-9 on myeloid cells within the brain tumor microenvironment (TME). Gal-9-expressing cells were abundant at the hypoxic tumor edge in the tumor-bearing ipsilateral hemisphere compared with the contralateral hemisphere in an intracranial mouse brain tumor model. Gal-9 was highly expressed in microglia and macrophages in tumor-infiltrating cells. In primary glia, both the expression and secretion of Gal-9 were influenced by tumors. Analysis of a human glioblastoma bulk RNA sequencing dataset and a single-cell RNA sequencing dataset from a murine glioma model revealed a correlation between Gal-9 expression and glial cell activation. Notably, the Gal-9high microglial subset was functionally distinct from the Gal-9neg/low subset in the brain TME. Gal-9high microglia exhibited properties of inflammatory activation and higher rates of cell death, whereas Gal-9neg/low microglia displayed a superior phagocytic ability against brain tumor cells. Blockade of Gal-9 suppressed tumor growth and altered the activity of glial and T cells in a mouse glioma model. Additionally, glial Gal-9 expression was regulated by hypoxia-inducible factor-2α in the hypoxic brain TME. Myeloid-specific hypoxia-inducible factor-2α deficiency led to attenuated tumor progression. Together, these findings reveal that Gal-9 on myeloid cells is an immunoregulator and putative therapeutic target in brain tumors. Significance: Galectin-9 serves as an immune checkpoint molecule that modulates the functional properties of microglia in the brain tumor microenvironment and could potentially be targeted to effectively treat brain tumors.

Farnesylthiosalicylic Acid Through Inhibition of Galectin-3 Improves Neuroinflammation in Alzheimer Disease via Multiple Pathways

AIMS

Many factors affect the neuroinflammatory response in patients with Alzheimer disease (AD). Galectin-3 (Gal-3) is closely related to microglial activation in the nervous system and can promote the aggregation of cancer cells in tumors. This study aimed to investigate the mechanism by which farnesylthiosalicylic acid (FTS) affects neuroinflammation in Aβ1-42 mice through Gal-3.

METHODS

We used the Morris water maze, reverse transcription-polymerase chain reaction (RT-PCR), Western blotting, enzyme-linked immunosorbent assay (ELISA), and immunofluorescence to conduct our study.

RESULTS

FTS reduced the levels of proinflammatory factors and microglial activation in Aβ1-42 mice. FTS inhibited total and membrane expression levels of Gal-3 in Aβ1-42 mice, and the anti-inflammatory effect of FTS was reversed by Gal-3-adeno-associated viral (AAV). FTS reduced the expression levels of toll-like receptors (TLRs), effects that were reversed by Gal-3-AAV. Moreover, FTS ameliorated Aβ oligomerization and accumulation in Aβ1-42 mice, effects that were also reversed by Gal-3-AAV. FTS, through the inhibition of the Gal-3-c-Jun N-terminal kinase (JNK) pathway, reduced PS1 expression; in addition, inhibition of Gal-3 increased the Aβ-degrading enzymes in Aβ1-42 mice. FTS-induced improvements in cognition in Aβ1-42 mice were reversed by Gal-3-AAV.

CONCLUSION

FTS may through inhibiting Gal-3 reduce the expression of TLR4 and CD14 and alleviate Aβ pathology, downregulating Aβ-stimulated TLR2, TLR4, and CD14 expression, and thus alleviate neuroinflammation in Aβ1-42 mice.

A comprehensive study on the multifunctional properties of galectin-4 in red-lip mullet (Planiliza haematocheilus): Insights into molecular interactions, antimicrobial defense, and cell proliferation

Galectin-4 belongs to the galactoside-binding protein family and is a type of tandem repeat galectin. Despite previous studies indicating its importance in fish immunology, a comprehensive investigation is necessary to fully understand its role in immunomodulatory functions and cellular dynamics. Therefore, this study aimed to explore the immunomodulatory functions of galectin-4 with a particular focus on its antimicrobial and cellular proliferative properties. The open reading frame of PhGal4 spans 1092 base pairs and encodes a soluble protein of 363 amino acids with a theoretical isoelectric point (IEP) of 6.39 and a molecular weight of 39.411 kDa. Spatial expression analysis under normal physiological conditions revealed ubiquitous expression of PhGal4 across all examined tissues, with the highest level observed in intestinal tissue. Upon stimulation with poly I:C, LPS, and L. garvieae, a significant increase (p < 0.05) in PhGal4 expression was observed in both blood and spleen tissues. Subsequent subcellular localization assay demonstrated that PhGal4 was predominantly localized in the cytoplasm. The recombinant PhGal4 (rPhGal4) exhibited specific binding capabilities to pathogen-associated molecular patterns (PAMPs), including LPS and peptidoglycan, but not poly I:C. The rPhGal4 negatively affected the bacterial growth kinetics. Additionally, rPhGal4 demonstrated complete hemagglutination of fish erythrocytes, which could be inhibited by the presence of D-galactose and α-lactose. The overexpression of PhGal4 in FHM epithelial cells demonstrated a significant suppression of viral replication during VHSV infection. Furthermore, the in vitro scratch assay and WST-1 assay demonstrated a wound healing effect of PhGal4 overexpression in FHM cells, potentially achieved through the promotion of cell proliferation by activating genes involved in cell cycle regulation. In conclusion, the responsive expression to immune stimuli, antimicrobial properties, and cell proliferation promotion of PhGal4 suggest that it plays a crucial role in immunomodulation and cellular dynamics of red-lip mullet. The findings in this study shed light on the multifunctional nature of galectin-4 in teleost fish.

Damage-associated molecular patterns in viral infection: potential therapeutic targets

Frequent viral infections leading to infectious disease outbreaks have become a significant global health concern. Fully elucidating the molecular mechanisms of the immune response against viral infections is crucial for epidemic prevention and control. The innate immune response, the host's primary defense against viral infection, plays a pivotal role and has become a breakthrough in research mechanisms. A component of the innate immune system, damage-associated molecular patterns (DAMPs) are involved in inducing inflammatory responses to viral infections. Numerous DAMPs are released from virally infected cells, activating downstream signaling pathways via internal and external receptors on immune cells. This activation triggers immune responses and helps regulate viral host invasion. This review examines the immune regulatory mechanisms of various DAMPs, such as the S100 protein family, high mobility group box 1 (HMGB1), and heat shock proteins, in various viral infections to provide a theoretical basis for designing novel antiviral drugs.

Exploring galectin-3's role in predicting mild cognitive impairment in type 2 diabetes and its regulation by miRNAs

Objective

This study aimed to investigate the role of galectin-3 (Gal-3; coded by LGALS3 gene), as a biomarker for MCI in T2DM patients and to develop and validate a predictive nomogram integrating galectin-3 with clinical risk factors for MCI prediction. Additionally, microRNA regulation of LGALS3 was explored.

Methods

The study employed a cross-sectional design. A total of 329 hospitalized T2DM patients were recruited and randomly allocated into a training cohort (n = 231) and a validation cohort (n = 98) using 7:3 ratio. Demographic data and neuropsychological assessments were recorded for all participants. Plasma levels of galectin-3 were measured using ELISA assay. We employed Spearman's correlation and multivariable linear regression to analyze the relationship between galectin-3 levels and cognitive performance. Furthermore, univariate and multivariate logistic regression analyses were conducted to identify independent risk factors for MCI in T2DM patients. Based on these analyses, a predictive nomogram incorporating galectin-3 and clinical predictors was developed. The model's performance was evaluated in terms of discrimination, calibration, and clinical utility. Regulatory miRNAs were identified using bioinformatics and their interactions with LGALS3 were confirmed through qRT-PCR and luciferase reporter assays.

Results

Galectin-3 was identified as an independent risk factor for MCI, with significant correlations to cognitive decline in T2DM patients. The developed nomogram, incorporating Gal-3, age, and education levels, demonstrated excellent predictive performance with an AUC of 0.813 in the training cohort and 0.775 in the validation cohort. The model outperformed the baseline galectin-3 model and showed a higher net benefit in clinical decision-making. Hsa-miR-128-3p was significantly downregulated in MCI patients, correlating with increased Gal-3 levels, while Luciferase assays confirmed miR-128-3p's specific binding and influence on LGALS3.

Conclusion

Our findings emphasize the utility of Gal-3 as a viable biomarker for early detection of MCI in T2DM patients. The validated nomogram offers a practical tool for clinical decision-making, facilitating early interventions to potentially delay the progression of cognitive impairment. Additionally, further research on miRNA128's regulation of Gal-3 levels is essential to substantiate our results.

The Possible Effects of Galectin-3 on Mechanisms of Renal and Hepatocellular Injury Induced by Intravascular Hemolysis

Intravascular hemolysis is a central feature of congenital and acquired hemolytic anemias, complement disorders, infectious diseases, and toxemias. Massive and/or chronic hemolysis is followed by the induction of inflammation, very often with severe damage of organs, which enhances the morbidity and mortality of hemolytic diseases. Galectin-3 (Gal-3) is a β-galactoside-binding lectin that modulates the functions of many immune cells, thus affecting inflammatory processes. Gal-3 is also one of the main regulators of fibrosis. The role of Gal-3 in the development of different kidney and liver diseases and the potential of therapeutic Gal-3 inhibition have been demonstrated. Therefore, the objective of this review is to discuss the possible effects of Gal-3 on the process of kidney and liver damage induced by intravascular hemolysis, as well as to shed light on the potential therapeutic targeting of Gal-3 in intravascular hemolysis.

Galectin-3 inhibition alleviated LPS-induced periodontal inflammation in gingival fibroblasts and experimental periodontitis mice

OBJECTIVES

Clinical studies have confirmed that galectin-3 (Gal-3) levels are significantly elevated in periodontitis patients. The present study aimed to explore the effects of Gal-3 inhibition on periodontal inflammation in vitro and in vivo.

METHODS

Human gingival fibroblasts (HGFs) with or without Gal-3 knockdown were stimulated by lipopolysaccharide (LPS), and a ligation-induced mouse periodontitis model treated with a Gal-3 inhibitor was established. Hematoxylin-eosin (H&E) and immunohistochemistry (IHC) staining were used to evaluate Gal-3 levels in gingival tissues. Quantitative real-time polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA) were used to detect Gal-3, interleukin (IL)-6, IL-8, and C-C motif ligand 2 (CCL2) expression. Immunofluorescence and western blotting were used to detect NF-κB and ERK signaling pathway activation. Micro-computed tomography was used to analyse the degree of bone loss.

RESULTS

Gal-3 was significantly up-regulated in inflamed gingival tissues and LPS-induced HGFs. Gal-3 knockdown markedly decreased LPS-induced IL-6, IL-8, and CCL2 expression and blocked NF-κB and ERK signaling pathway activation in HGFs. In the mouse periodontitis model, Gal-3 inhibition significantly alleviated IL-1β and IL-6 infiltration in gingival tissue and mitigated periodontal bone loss.

CONCLUSIONS

Gal-3 inhibition notably alleviated periodontal inflammation partly through blocking NF-κB and ERK signaling pathway activation.

Serum Mac-2 binding protein glycosylation isomer and galectin-3 levels in adult-onset Still's disease and their association with cytokines

Background

Autoinflammation with cytokine dysregulation may be implicated in the pathophysiology of adult-onset Still's disease (AOSD); however, the relationship between galectins and cytokines in patients with active AOSD remains unknown. We aimed to examine the relationship between circulating cytokines/chemokines and galectin-3 (Gal-3) or its ligand, Mac-2 binding protein glycosylation isomer (M2BPGi), in Japanese patients with AOSD.

Methods

We recruited 44 consecutive patients diagnosed with AOSD according to the Yamaguchi criteria, 50 patients with rheumatoid arthritis (RA) as disease controls, and 27 healthy participants. Serum M2BPGi levels were directly measured using a HISCL M2BPGi reagent kit and an automatic immunoanalyzer (HISCL-5000). Serum Gal-3 concentrations were measured by enzyme-linked immunosorbent assay. The serum levels of 69 cytokines were analyzed in patients with AOSD using a multi-suspension cytokine array. We performed a cluster analysis of each cytokine expressed in patients with AOSD to identify specific molecular networks.

Results

Significant increases in the serum concentrations of Gal-3 and M2BPGi were found in the serum of patients with AOSD compared with patients with RA and healthy participants (both p <0.001). There were significant positive correlations between serum Gal-3 levels and AOSD disease activity score (Pouchot score, r=0.66, p <0.001) and serum ferritin levels. However, no significant correlations were observed between serum M2BPGi levels and AOSD disease activity scores (Pouchot score, r = 0.32, p = 0.06) or serum ferritin levels. Furthermore, significant correlations were observed between the serum levels of Gal-3 and various inflammatory cytokines, including interleukin-18, in patients with AOSD. Immunosuppressive treatment in patients with AOSD significantly reduced serum Gal-3 and M2BPGi levels (p = 0.03 and 0.004, respectively).

Conclusions

Although both Gal-3 and M2BPGi were elevated in patients with AOSD, only Gal-3 was a useful biomarker for predicting disease activity in AOSD. Our findings suggest that circulating Gal-3 reflects the inflammatory component of AOSD, which corresponds to proinflammatory cytokine induction through inflammasome activation cascades.

Unraveling the role of galectin-3 in cardiac pathology and physiology

Galectin-3 (Gal-3) is a carbohydrate-binding protein with multiple functions. Gal-3 regulates cell growth, proliferation, and apoptosis by orchestrating cell-cell and cell-matrix interactions. It is implicated in the development and progression of cardiovascular disease, and its expression is increased in patients with heart failure. In atherosclerosis, Gal-3 promotes monocyte recruitment to the arterial wall boosting inflammation and atheroma. In acute myocardial infarction (AMI), the expression of Gal-3 increases in infarcted and remote zones from the beginning of AMI, and plays a critical role in macrophage infiltration, differentiation to M1 phenotype, inflammation and interstitial fibrosis through collagen synthesis. Genetic deficiency of Gal-3 delays wound healing, impairs cardiac remodeling and function after AMI. On the contrary, Gal-3 deficiency shows opposite results with improved remodeling and function in other cardiomyopathies and in hypertension. Pharmacologic inhibition with non-selective inhibitors is also protective in cardiac disease. Finally, we recently showed that Gal-3 participates in normal aging. However, genetic absence of Gal-3 in aged mice exacerbates pathological hypertrophy and increases fibrosis, as opposed to reduced fibrosis shown in cardiac disease. Despite some gaps in understanding its precise mechanisms of action, Gal-3 represents a potential therapeutic target for the treatment of cardiovascular diseases and the management of cardiac aging. In this review, we summarize the current knowledge regarding the role of Gal-3 in the pathophysiology of heart failure, atherosclerosis, hypertension, myocarditis, and ischemic heart disease. Furthermore, we describe the physiological role of Gal-3 in cardiac aging.

Galectin-1 Modulates the Fusogenic Activity of Placental Endogenous Retroviral Envelopes

Syncytin-1 and -2 are glycoproteins encoded by human endogenous retrovirus (hERV) that, through their fusogenic properties, are needed for the formation of the placental syncytiotrophoblast. Previous studies suggested that these proteins, in addition to the EnvP(b) envelope protein, are also involved in other cell fusion events. Since galectin-1 is a β-galactoside-binding protein associated with cytotrophoblast fusion during placental development, we previously tested its effect on Syncytin-mediated cell fusion and showed that this protein differently modulates the fusogenic potential of Syncytin-1 and -2. Herein, we were interested in comparing the impact of galectin-1 on hERV envelope proteins in different cellular contexts. Using a syncytium assay, we first demonstrated that galectin-1 increased the fusion of Syncytin-2- and EnvP(b)-expressing cells. We then tested the infectivity of Syncytin-1 and -2 vs. VSV-G-pseudotyped viruses toward Cos-7 and various human cell lines. In the presence of galectin-1, infection of Syncytin-2-pseudotyped viruses augmented for all cell lines. In contrast, the impact of galectin-1 on the infectivity of Syncytin-1-pseudotyped viruses varied, being cell- and dose-dependent. In this study, we report the functional associations between three hERV envelope proteins and galectin-1, which should provide information on the fusogenic activity of these proteins in the placenta and other biological and pathological processes.

Galectins in Protozoan Parasitic Diseases: Potential Applications in Diagnostics and Therapeutics

Neglected tropical diseases (NTDs) constitute a group of diseases that generally develop in tropical or subtropical climatic conditions and are related to poverty. Within the spectrum of NTDs, diseases caused by protozoa such as malaria, Chagas disease, and leishmaniasis exhibit elevated mortality rates, thereby constituting a substantial public health concern. Beyond their protozoan etiology, these NTDs share other similarities, such as the challenge of control and the lack of affordable, safe, and effective drugs. In view of the above, the need to explore novel diagnostic predictors and therapeutic targets for the treatment of these parasitic diseases is evident. In this context, galectins are attractive because they are a set of lectins bound to β-galactosides that play key roles in a variety of cellular processes, including host-parasite interaction such as adhesion and entry of parasites into the host cells, and participate in antiparasitic immunity in either a stimulatory or inhibitory manner, especially the galectins-1, -2, -3, and -9. These functions bestow upon galectins significant therapeutic prospects in the context of managing and diagnosing NTDs. Thus, the present review aims to elucidate the potential role of galectins in the diagnosis and treatment of malaria, leishmaniasis, and Chagas disease.

Morphology Dictated Immune Activation with Framework Nucleic Acids

Framework nucleic acids (FNAs) of various morphologies, designed using the precise and programmable Watson-Crick base pairing, serve as carriers for biomolecule delivery in biology and biomedicine. However, the impact of their shape, size, concentration, and the spatial presentation of cytosine-phosphate-guanine oligodeoxynucleotides (CpG ODNs) on immune activation remains incompletely understood. In this study, representative FNAs with varying morphologies are synthesized to explore their immunological responses. Low concentrations (50 nM) of all FNAs elicited no immunostimulation, while high concentrations of elongated DNA nanostrings and tetrahedrons triggered strong activation due to their larger size and increased cellular uptake, indicating that the innate immune responses of FNAs depend on both dose and morphology. Notably, CpG ODNs' immune response can be programmed by FNAs through regulating the spatial distance, with optimal spacing of 7-8 nm eliciting the highest immunostimulation. These findings demonstrate FNAs' potential as a designable tool to study nucleic acid morphology's impact on biological responses and provide a strategy for future CpG-mediated immune activation carrier design.

A unique maternal and placental galectin signature upon SARS-CoV-2 infection suggests galectin-1 as a key alarmin at the maternal-fetal interface

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic imposed a risk of infection and disease in pregnant women and neonates. Successful pregnancy requires a fine-tuned regulation of the maternal immune system to accommodate the growing fetus and to protect the mother from infection. Galectins, a family of β-galactoside-binding proteins, modulate immune and inflammatory processes and have been recognized as critical factors in reproductive orchestration, including maternal immune adaptation in pregnancy. Pregnancy-specific glycoprotein 1 (PSG1) is a recently identified gal-1 ligand at the maternal-fetal interface, which may facilitate a successful pregnancy. Several studies suggest that galectins are involved in the immune response in SARS-CoV-2-infected patients. However, the galectins and PSG1 signature upon SARS-CoV-2 infection and vaccination during pregnancy remain unclear. In the present study, we examined the maternal circulating levels of galectins (gal-1, gal-3, gal-7, and gal-9) and PSG1 in pregnant women infected with SARS-CoV-2 before vaccination or uninfected women who were vaccinated against SARS-CoV-2 and correlated their expression with different pregnancy parameters. SARS-CoV-2 infection or vaccination during pregnancy provoked an increase in maternal gal-1 circulating levels. On the other hand, levels of PSG1 were only augmented upon SARS-CoV-2 infection. A healthy pregnancy is associated with a positive correlation between gal-1 concentrations and gal-3 or gal-9; however, no correlation was observed between these lectins during SARS-CoV-2 infection. Transcriptome analysis of the placenta showed that gal-1, gal-3, and several PSG and glycoenzymes responsible for the synthesis of gal-1-binding glycotopes (such as linkage-specific N-acetyl-glucosaminyltransferases (MGATs)) are upregulated in pregnant women infected with SARS-CoV-2. Collectively, our findings identify a dynamically regulated "galectin-specific signature" that accompanies the SARS-CoV-2 infection and vaccination in pregnancy, and they highlight a potentially significant role for gal-1 as a key pregnancy protective alarmin during virus infection.

Matricellular proteins in atherosclerosis development

The extracellular matrix (ECM) is an intricate network composed of various multi-domain macromolecules like collagen, proteoglycans, and fibronectin, etc., that form a structurally stable composite, contributing to the mechanical properties of tissue. However, matricellular proteins are non-structural, secretory extracellular matrix proteins, which modulate various cellular functions via interacting with cell surface receptors, proteases, hormones, and cell-matrix. They play essential roles in maintaining tissue homeostasis by regulating cell differentiation, proliferation, adhesion, migration, and several signal transduction pathways. Matricellular proteins display a broad functionality regulated by their multiple structural domains and their ability to interact with different extracellular substrates and/or cell surface receptors. The expression of these proteins is low in adults, however, gets upregulated following injuries, inflammation, and during tumor growth. The marked elevation in the expression of these proteins during atherosclerosis suggests a positive association between their expression and atherosclerotic lesion formation. The role of matricellular proteins in atherosclerosis development has remained an area of research interest in the last two decades and studies revealed these proteins as important players in governing vascular function, remodeling, and plaque formation. Despite extensive research, many aspects of the matrix protein biology in atherosclerosis are still unknown and future studies are required to investigate whether targeting pathways stimulated by these proteins represent viable therapeutic approaches for patients with atherosclerotic vascular diseases. This review summarizes the characteristics of distinct matricellular proteins, discusses the available literature on the involvement of matrix proteins in the pathogenesis of atherosclerosis and suggests new avenues for future research.

Galectins are critical regulators of cytokine signalling at feto-maternal interface in infection-associated spontaneous preterm birth

INTRODUCTION

Spontaneous preterm birth (sPTB) is a global health issue. Studies suggest infections are chiefly associated with sPTB and galectins (gals) play a role in regulation of innate and adaptive maternal immune response against pathogens during sPTB. The aim of this study was to describe the gene expression of gal -1, -3, -8, -9, -13 in relation to gene expression of cyclooxygenase-2 (COX-2) and the cytokines IL-8, IL-10, TNF-α, IFN-ϒ in the setting of sPTB and confirmed infection with Chlamydia trachomatis, Mycoplasma hominis, and Ureaplasma urealyticum.

METHODS

Placental samples were collected from 120 term control and 120 sPTB pregnancies. PCR was used to detect specific pathogens. Gene expression of galectins, cytokines, and COX-2 was performed using real time qPCR.

RESULTS

Fold-change expression of gal -1, -3, -8, -9, -13 was 5.13, 6.11, 1.14, 5.23 and 7.16 (p<0.001), respectively; while IL-10, IL-8, TNF-α, IFN-ϒ and COX-2 was 6.29, 6.55, 6.35, 6.36 and 2.73-fold upregulated (p<0.05), respectively in infected sPTB. Gal-1 was positively correlated with IL-10 (r=0.49, p=0.003) while gal-3 showed significant correlation with IL-8 (r=0.42, p=0.0113), TNF-α (r=0.65, p=< 0.001) and COX-2 (r=0.72, p=0.001). However, gal-8 was not significantly correlated with any cytokine. Gal-9, -13 were negatively correlated with IFN-ϒ (r=-0.45, p=0.006) and IL-8 (r=-0.39, p=0.018).

DISCUSSION

Gal-1, -9, -13 are anti-inflammatory and might play role in immune-tolerance while gal-3 is pro-inflammatory and possibly responsible for immunogenic response, having potential to anticipate the clinical beginning of preterm labour during infection.

Molecular Cloning and Functional Characterization of Galectin-1 in Yellow Drum (Nibea albiflora)

Galectins are proteins that are involved in the innate immune response against pathogenic microorganisms. In the present study, the gene expression pattern of galectin-1 (named as NaGal-1) and its function in mediating the defense response to bacterial attack were investigated. The tertiary structure of NaGal-1 protein consists of homodimers and each subunit has one carbohydrate recognition domain. Quantitative RT-PCR analysis indicated that NaGal-1 was ubiquitously distributed in all the detected tissues and highly expressed in the swim-bladder of Nibea albiflora, and its expression could be upregulated by the pathogenic Vibrio harveyi attack in the brain. Expression of NaGal-1 protein in HEK 293T cells was distributed in the cytoplasm as well as in the nucleus. The recombinant NaGal-1 protein by prokaryotic expression could agglutinate red blood cells from rabbit, Larimichthys crocea, and N. albiflora. The agglutination of N. albiflora red blood cells by the recombinant NaGal-1 protein was inhibited by peptidoglycan, lactose, D-galactose, and lipopolysaccharide in certain concentrations. In addition, the recombinant NaGal-1 protein agglutinated and killed some gram-negative bacteria including Edwardsiella tarda, Escherichia coli, Photobacterium phosphoreum, Aeromonas hydrophila, Pseudomonas aeruginosa, and Aeromonas veronii. These results set the stage for further studies of NaGal-1 protein in the innate immunity of N. albiflora.

Unraveling the pathophysiologic role of galectin-3 in chronically injured liver

Galectin-3 (Gal-3) previously referred to as S-type lectins, is a soluble protein that specifically binds to β-galactoside carbohydrates with high specificity. Gal-3 plays a pivotal role in a variety of pathophysiological processes such as cell proliferation, inflammation, differentiation, angiogenesis, transformation and apoptosis, pre-mRNA splicing, metabolic syndromes, fibrosis, and host defense. The role of Gal-3 has also been implicated in liver diseases. Gal-3 is activated upon a hepatotoxic insult to the liver and its level has been shown to be upregulated in fatty liver diseases, inflammation, nonalcoholic steatohepatitis, fibrosis, cholangitis, cirrhosis, and hepatocellular carcinoma (HCC). Gal-3 directly interacts with the NOD-like receptor family, pyrin domain containing 3, and activates the inflammasome in macrophages of the liver. In the chronically injured liver, Gal-3 secreted by injured hepatocytes and immune cells, activates hepatic stellate cells (HSCs) in a paracrine fashion to acquire a myofibroblast like collagen-producing phenotype. Activated HSCs in the fibrotic liver secrete Gal-3 which acts via autocrine signaling to exacerbate extracellular matrix synthesis and fibrogenesis. In the stromal microenvironment, Gal-3 activates cancer cell proliferation, migration, invasiveness, and metastasis. Clinically, increased serum levels and Gal-3 expression were observed in the liver tissue of nonalcoholic steatohepatitis, fibrotic/cirrhotic, and HCC patients. The pathological role of Gal-3 has been experimentally and clinically reported in the progression of chronic liver disease. Therefore, this review discusses the pathological role of Gal-3 in the progression of chronic liver diseases.

Galectin-3 as an important prognostic marker for COVID-19 severity

Galectin-3 (Gal-3), multifunctional protein plays important roles in inflammatory response, infection and fibrosis. The goal of study was to determine the association of Gal-3, immune response, clinical, biochemical, and radiographic findings with COVID-19 severity. Study included 280 COVID-19 patients classified according to disease severity into mild, moderate, severe and critical group. Cytokines, clinical, biochemical, radiographic data and peripheral blood immune cell make up were analyzed. Patients in critical group had significantly higher serum level of Gal-3, IL-1β, TNF-α, IL-12, IL-10 compared to the patients in less severe stages of disease. Strong positive correlation was detected between Gal-3 and IL-1β, moderate positive correlation between Gal-3, TNF-α and IL-12, moderate negative correlation between Gal-3, IL-10/IL-1β and IL-10/TNF-α. Moderate positive correlation noted between Gal-3 and urea, D dimer, CXR findings. Strong negative correlation detected between Gal-3 and p0₂, Sa0_2, and moderate negative correlation between Gal-3, lymphocyte and monocyte percentage. In the peripheral blood of patients with more severe stages of COVID-19 we detected significantly increased percentages of CD56^- CD3⁺TNF-α⁺T cells and CD56^- CD3⁺Gal-3⁺T cells and increased expression of CCR5 in PBMCs. Our results predict Gal-3 as an important marker for critical stage of COVID-19. Higher expression of Gal-3, TNF-α and CCR5 on T cells implicate on promoting inflammation and more severe form of disease.

The role of galectins in immunity and infection

The galectin family consists of carbohydrate (glycan) binding proteins that are expressed by a wide variety of cells and bind to galactose-containing glycans. Galectins can be located in the nucleus or the cytoplasm, or can be secreted into the extracellular space. They can modulate innate and adaptive immune cells by binding to glycans on the surface of immune cells or intracellularly via carbohydrate-dependent or carbohydrate-independent interactions. Galectins expressed by immune cells can also participate in host responses to infection by directly binding to microorganisms or by modulating antimicrobial functions such as autophagy. Here we explore the diverse ways in which galectins have been shown to impact immunity and discuss the opportunities and challenges in the field.

The interplay of galectins-1, -3, and -9 in the immune-inflammatory response underlying cardiovascular and metabolic disease

Galectins are β-galactoside-binding proteins that bind and crosslink molecules via their sugar moieties, forming signaling and adhesion networks involved in cellular communication, differentiation, migration, and survival. Galectins are expressed ubiquitously across immune cells, and their function varies with their tissue-specific and subcellular location. Particularly galectin-1, -3, and -9 are highly expressed by inflammatory cells and are involved in the modulation of several innate and adaptive immune responses. Modulation in the expression of these proteins accompany major processes in cardiovascular diseases and metabolic disorders, such as atherosclerosis, thrombosis, obesity, and diabetes, making them attractive therapeutic targets. In this review we consider the broad cellular activities ascribed to galectin-1, -3, and -9, highlighting those linked to the progression of different inflammatory driven pathologies in the context of cardiovascular and metabolic disease, to better understand their mechanism of action and provide new insights into the design of novel therapeutic strategies.

Crosslinking of membrane CD13 in human neutrophils mediates phagocytosis and production of reactive oxygen species, neutrophil extracellular traps and proinflammatory cytokines

Aminopeptidase N, or CD13, is a cell membrane ectopeptidase highly expressed in myeloid cells. Through its enzymatic activity, CD13 regulates the activity of several bioactive peptides, such as endorphins and enkephalins, chemotactic peptides like MCP-1 and IL-8, angiotensin III, bradikinin, etc. In recent years, it has been appreciated that independently of its peptidase activity, CD13 can activate signal transduction pathways and mediate effector functions such as phagocytosis and cytokine secretion in monocytes and macrophages. Although neutrophils are known to express CD13 on its membrane, it is currently unknown if CD13 can mediate effector functions in these cells. Here, we show that in human neutrophils CD13 can mediate phagocytosis, which is dependent on a signaling pathway that involves Syk, and PI3-K. Phagocytosis mediated by CD13 is associated with production of reactive oxygen species (ROS). The level of phagocytosis and ROS production mediated by CD13 are similar to those through FcγRIII (CD16b), a widely studied receptor of human neutrophils. Also, CD13 ligation induces the release of neutrophil extracellular traps (NETs) as well as cytokine secretion from neutrophils. These results support the hypothesis that CD13 is a membrane receptor able to activate effector functions in human neutrophils.

The Expression of IL-1β Correlates with the Expression of Galectin-3 in the Tissue at the Maternal-Fetal Interface during the Term and Preterm Labor

The inflammatory processes that occur at the maternal−fetal interface are considered one of the factors that are responsible for preterm birth. The pro-inflammatory roles of the Gal-3-induced activation of NLRP3 inflammasome and the consecutive production of IL-1β have been described in several acute and chronic inflammatory diseases, but the role of this inflammatory axis in parturition has not been studied. The aim of this study was to analyze the protein expression of Gal-3, NLRP3, and IL-1β in the decidua, villi, and fetal membranes, and to analyze their mutual correlation and correlation with the clinical parameters of inflammation in preterm birth (PTB) and term birth (TB). The study included 40 women that underwent a preterm birth (gestational age of 25.0−36.6) and histological chorioamnionitis (PTB) and control subjects, 22 women that underwent a term birth (gestational age of 37.0−41.6) without histological chorioamnionitis (TB). An analysis of the tissue sections that were stained with anti- Gal-3, -NLRP3, and -IL-1β antibodies was assessed by three independent investigators. The expression levels of Gal-3 and IL-1β were significantly higher (p < 0.001) in the decidua, villi, and fetal membranes in the PTB group when they compared to those of the TB group, while there was no difference in the expression of NLRP3. A further analysis revealed that there was no correlation between the protein expression of NLRP3 and the expression of Gal-3 and IL-1β, but there was a correlation between the expression of Gal-3 and IL-1β in decidua (R = 0.401; p = 0.008), villi (R = 0.301; p = 0.042) and the fetal membranes (R = 0.428; p = 0.002) in both of the groups, PTB and TB. In addition, the expression of Gal-3 and IL-1β in decidua and the fetal membranes was in correlation with the parameters of inflammation in the maternal and fetal blood (C-reactive protein, leukocyte number, and fibrinogen). The strong correlation between the expression of Gal-3 and IL-1β in the placental and fetal tissues during labor indicates that Gal-3 may participate in the regulation of the inflammatory processes in the placenta, leading to increased production of IL-1β, a cytokine that plays the main role in both term and preterm birth.

NLRP3 inflammasome activation mechanism and its role in autoimmune liver disease

The NLRP3 inflammasome is a multiprotein binding compound comprising NLRP3, connector protein ASC, and effector protein pro-caspase-1. When the NLRP3 inflammasome senses a danger signal from the host or pathogen, activated caspase-1 cleaves the precursors of interleukin (IL)-1β and IL-18 into mature proinflammatory cytokines, simultaneously causing lysis via the pore-forming protein gasdermin D. This induction of cell inflammatory pyroptosis suggests that it is a key process in the innate immune response to pathogens or cellular stress. Recent studies have shown that NLRP3 inflammasome also plays an important role in regulating autoimmune liver diseases, including autoimmune hepatitis, primary biliary cholangitis, and primary sclerosclerotic cholangitis. In this review, we summarize the structure, activation and modulation of the NLRP3 inflammasome, highlight the progress in research on the role of NLRP3 inflammasome in the occurrence and development of autoimmune liver diseases, and discuss potential strategies for targeting the NLRP3 inflammasome in the treatment of autoimmune liver diseases.

An Automated Approach to Assess Relative Galectin-Glycan Affinity Following Glycan Microarray Analysis

Numerous studies have highlighted the utility of glycan microarray analysis for the elucidation of protein-glycan interactions. However, most current glycan microarray studies analyze glycan binding protein (GBP)-glycan interactions at a single protein concentration. While this approach provides useful information related to a GBP's overall binding capabilities, extrapolation of true glycan binding preferences using this method fails to account for printing variations or other factors that may confound relative binding. To overcome this limitation, we examined glycan array binding of three galectins over a range of concentrations to allow for a more complete assessment of binding preferences. This approach produced a richer data set than single concentration analysis and provided more accurate identification of true glycan binding preferences. However, while this approach can be highly informative, currently available data analysis approaches make it impractical to perform binding isotherms for each glycan present on currently available platforms following GBP evaluation. To overcome this limitation, we developed a method to directly optimize the efficiency of assessing association constants following multi-GBP concentration glycan array analysis. To this end, we developed programs that automatically analyze raw array data (kdMining) to generate output graphics (kaPlotting) following array analysis at multiple doses. These automatic programing methods reduced processing time from 32.8 h to 1.67 min. Taken together, these results demonstrate an effective approach to glycan array analysis that provides improved detail and efficiency when compared to previous methods.

Cellular and Molecular Mechanism of Pulmonary Fibrosis Post-COVID-19: Focus on Galectin-1, -3, -8, -9

Pulmonary fibrosis is a consequence of the pathological accumulation of extracellular matrix (ECM), which finally leads to lung scarring. Although the pulmonary fibrogenesis is almost known, the last two years of the COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its post effects added new particularities which need to be explored. Many questions remain about how pulmonary fibrotic changes occur within the lungs of COVID-19 patients, and whether the changes will persist long term or are capable of resolving. This review brings together existing knowledge on both COVID-19 and pulmonary fibrosis, starting with the main key players in promoting pulmonary fibrosis, such as alveolar and endothelial cells, fibroblasts, lipofibroblasts, and macrophages. Further, we provide an overview of the main molecular mechanisms driving the fibrotic process in connection with Galactin-1, -3, -8, and -9, together with the currently approved and newly proposed clinical therapeutic solutions given for the treatment of fibrosis, based on their inhibition. The work underlines the particular pathways and processes that may be implicated in pulmonary fibrosis pathogenesis post-SARS-CoV-2 viral infection. The recent data suggest that galectin-1, -3, -8, and -9 could become valuable biomarkers for the diagnosis and prognosis of lung fibrosis post-COVID-19 and promising molecular targets for the development of new and original therapeutic tools to treat the disease.

Innate immune Galectin-7 specifically targets microbes that decorate themselves in blood group-like antigens

Adaptive immunity can target a nearly infinite range of antigens, yet it is tempered by tolerogenic mechanisms that limit autoimmunity. Such immunological tolerance, however, creates a gap in adaptive immunity against microbes decorated with self-like antigens as a form of molecular mimicry. Our results demonstrate that the innate immune lectin galectin-7 (Gal-7) binds a variety of distinct microbes, all of which share features of blood group-like antigens. Gal-7 binding to each blood group expressing microbe, including strains of Escherichia coli, Klebsiella pneumoniae, Providencia alcalifaciens, and Streptococcus pneumoniae, results in loss of microbial viability. Although Gal-7 also binds red blood cells (RBCs), this interaction does not alter RBC membrane integrity. These results demonstrate that Gal-7 recognizes a diverse range of microbes, each of which use molecular mimicry while failing to induce host cell injury, and thus may provide an innate form of immunity against molecular mimicry.

Galectin-3 Involvement in Cognitive Processes for New Therapeutic Considerations

Cognitive impairment may be a consequence of the normal aging process, but it may also be the hallmark of various neurodegenerative and psychiatric diseases. Early identification of individuals at particular risk for cognitive decline is critical, as it is imperative to maintain a cognitive reserve in these neuropsychiatric entities. In recent years, galectin-3 (Gal-3), a member of the galectin family, has received considerable attention with respect to aspects of neuroinflammation and neurodegeneration. The mechanisms behind the putative relationship between Gal-3 and cognitive impairment are not yet clear. Intrigued by this versatile molecule and its unique modular architecture, the latest data on this relationship are presented here. This mini-review summarizes recent findings on the mechanisms by which Gal-3 affects cognitive functioning in both animal and human models. Particular emphasis is placed on the role of Gal-3 in modulating the inflammatory response as a fine-tuner of microglia morphology and phenotype. A review of recent literature on the utility of Gal-3 as a biomarker is provided, and approaches to strategically exploit Gal-3 activities with therapeutic intentions in neuropsychiatric diseases are outlined.

Microglial Inflammatory-Metabolic Pathways and Their Potential Therapeutic Implication in Major Depressive Disorder

Increasing evidence supports the notion that neuroinflammation plays a critical role in the etiology of major depressive disorder (MDD), at least in a subset of patients. By virtue of their capacity to transform into reactive states in response to inflammatory insults, microglia, the brain's resident immune cells, play a pivotal role in the induction of neuroinflammation. Experimental studies have demonstrated the ability of microglia to recognize pathogens or damaged cells, leading to the activation of a cytotoxic response that exacerbates damage to brain cells. However, microglia display a wide range of responses to injury and may also promote resolution stages of inflammation and tissue regeneration. MDD has been associated with chronic priming of microglia. Recent studies suggest that altered microglial morphology and function, caused either by intense inflammatory activation or by senescence, may contribute to depression and associated impairments in neuroplasticity. In this context, modifying microglia phenotype by tuning inflammatory pathways might have important translational relevance to harness neuroinflammation in MDD. Interestingly, it was recently shown that different microglial phenotypes are associated with distinct metabolic pathways and analysis of the underlying molecular mechanisms points to an instrumental role for energy metabolism in shaping microglial functions. Here, we review various canonical pro-inflammatory, anti-inflammatory and metabolic pathways in microglia that may provide new therapeutic opportunities to control neuroinflammation in brain disorders, with a strong focus on MDD.

Galectin-3 in Kidney Diseases: From an Old Protein to a New Therapeutic Target

Galectin-3 (Gal-3) is a 30KDa lectin implicated in multiple pathophysiology pathways including renal damage and fibrosis. Gal-3 binds β-galactoside through its carbohydrate-recognition domain. From intra-cellular to extra-cellular localization, Gal-3 has multiple roles including transduction signal pathway, cell-to-cell adhesion, cell to extracellular matrix adhesion, and immunological chemoattractant protein. Moreover, Gal-3 has also been linked to kidney disease in both preclinical models and clinical studies. Gal-3 inhibition appears to improve renal disease in several pathological conditions, thus justifying the development of multiple drug inhibitors. This review aims to summarize the latest literature regarding Gal-3 in renal pathophysiology, from its role as a biomarker to its potential as a therapeutic agent.

The Role of Anti-Viral Effector Molecules in Mollusc Hemolymph

Molluscs are major contributors to the international and Australian aquaculture industries, however, their immune systems remain poorly understood due to limited access to draft genomes and evidence of divergences from model organisms. As invertebrates, molluscs lack adaptive immune systems or 'memory', and rely solely on innate immunity for antimicrobial defence. Hemolymph, the circulatory fluid of invertebrates, contains hemocytes which secrete effector molecules with immune regulatory functions. Interactions between mollusc effector molecules and bacterial and fungal pathogens have been well documented, however, there is limited knowledge of their roles against viruses, which cause high mortality and significant production losses in these species. Of the major effector molecules, only the direct acting protein dicer-2 and the antimicrobial peptides (AMPs) hemocyanin and myticin-C have shown antiviral activity. A better understanding of these effector molecules may allow for the manipulation of mollusc proteomes to enhance antiviral and overall antimicrobial defence to prevent future outbreaks and minimize economic outbreaks. Moreover, effector molecule research may yield the description and production of novel antimicrobial treatments for a broad host range of animal species.

Galectins in Chagas Disease: A Missing Link Between Trypanosoma cruzi Infection, Inflammation, and Tissue Damage

Trypanosoma cruzi, the protozoan parasite causative agent of Chagas disease, affects about seven million people worldwide, representing a major global public health concern with relevant socioeconomic consequences, particularly in developing countries. In this review, we discuss the multiple roles of galectins, a family of β-galactoside-binding proteins, in modulating both T. cruzi infection and immunoregulation. Specifically, we focus on galectin-driven circuits that link parasite invasion and inflammation and reprogram innate and adaptive immune responses. Understanding the dynamics of galectins and their β-galactoside-specific ligands during the pathogenesis of T. cruzi infection and elucidating their roles in immunoregulation, inflammation, and tissue damage offer new rational opportunities for treating this devastating neglected disease.

What Happens If a Human Galectin Enters the Endoplasmic Reticulum?

Mammalian galectins have no signal peptide, and it is not known what would happen if a galectin is directed to take the classical export route. The corresponding engineering of galectin-specific cDNA will answer questions on the fate of a signal peptide-bearing protein variant after its entry into the endoplasmic reticulum (ER). Affinity chromatography and mass-spectrometric analysis of occupancy of potential N-glycosylation sites for the galectin, binding and functional assays with cells as well as subcellular fractionation by density gradient ultracentrifugation and immunocytochemical colocalization with ER/Golgi markers report on aspects of the consequences of letting a galectin enter new territory. Applying these methods will help to clarify why galectins are leaderless and thus produced by free ribosomes.

Galectins in Early Pregnancy and Pregnancy-Associated Pathologies

Galectins are a family of conserved soluble proteins defined by an affinity for β-galactoside structures present on various glycoconjugates. Over the past few decades, galectins have been recognized as important factors for successful implantation and maintenance of pregnancy. An increasing number of studies have demonstrated their involvement in trophoblast cell function and placental development. In addition, several lines of evidence suggest their important roles in feto-maternal immune tolerance regulation and angiogenesis. Changed or dysregulated galectin expression is also described in pregnancy-related disorders. Although the data regarding galectins' clinical relevance are still at an early stage, evidence suggests that some galectin family members are promising candidates for better understanding pregnancy-related pathologies, as well as predicting biomarkers. In this review, we aim to summarize current knowledge of galectins in early pregnancy as well as in pregnancy-related pathologies.

Therapeutic Interventions Targeting Innate Immune Receptors: A Balancing Act

The innate immune system is an organism's first line of defense against an onslaught of internal and external threats. The downstream adaptive immune system has been a popular target for therapeutic intervention, while there is a relative paucity of therapeutics targeting the innate immune system. However, the innate immune system plays a critical role in many human diseases, such as microbial infection, cancer, and autoimmunity, highlighting the need for ongoing therapeutic research. In this review, we discuss the major innate immune pathways and detail the molecular strategies underpinning successful therapeutics targeting each pathway as well as previous and ongoing efforts. We will also discuss any recent discoveries that could inform the development of novel therapeutic strategies. As our understanding of the innate immune system continues to develop, we envision that therapies harnessing the power of the innate immune system will become the mainstay of treatment for a wide variety of human diseases.

Transgenic Overexpression of Galectin-3 in Pancreatic β Cells Attenuates Hyperglycemia in Mice: Synergistic Antidiabetic Effect With Exogenous IL-33

Galectin-3 (Gal-3) has diverse roles in inflammatory and autoimmune diseases. There is evidence that Gal-3 plays a role in both type 1 and type 2 diabetes. While the role of Gal-3 expression in immune cells invading the pancreatic islets in the experimental model of type 1 diabetes mellitus has been already studied, the importance of the overexpression of Gal-3 in the target β cells is not defined. Therefore, we used multiple low doses of streptozotocin (MLD–STZ)–induced diabetes in C57Bl/6 mice to analyze the effect of transgenic (TG) overexpression of Gal-3 in β cells. Our results demonstrated that the overexpression of Gal-3 protected β cells from apoptosis and attenuated MLD–STZ–induced hyperglycemia, glycosuria, and ketonuria. The cellular analysis of pancreata and draining lymph nodes showed that Gal-3 overexpression significantly decreased the number of pro-inflammatory cells without affecting the presence of T-regulatory cells. As the application of exogenous interleukin 33 (IL-33) given from the beginning of MLD–STZ diabetes induction attenuates the development of disease, by increasing the presence of regulatory FoxP3⁺ ST2⁺ cells, we evaluated the potential synergistic effect of the exogenous IL-33 and TG overexpression of Gal-3 in β cells at the later stage of diabetogenesis. The addition of IL-33 potentiated the survival of β cells and attenuated diabetes even when administered later, after the onset of hyperglycemia (12–18 days), suggesting that protection from apoptosis and immunoregulation by IL-33 may attenuate type 1 diabetes.

The seasonal behaviour of COVID-19 and its galectin-like culprit of the viral spike

Seasonal behaviour is an attribute of many viral diseases. Like other 'winter' RNA viruses, infections caused by the causative agent of COVID-19, SARS-CoV-2, appear to exhibit significant seasonal changes. Here we discuss the seasonal behaviour of COVID-19, emerging viral phenotypes, viral evolution, and how the mutational landscape of the virus affects the seasonal attributes of the disease. We propose that the multiple seasonal drivers behind infectious disease spread (and the spread of COVID-19 specifically) are in 'trade-off' relationships and can be better described within a framework of a 'triangle of viral persistence' modulated by the environment, physiology, and behaviour. This 'trade-off' exists as one trait cannot increase without a decrease in another. We also propose that molecular components of the virus can act as sensors of environment and physiology, and could represent molecular culprits of seasonality. We searched for flexible protein structures capable of being modulated by the environment and identified a galectin-like fold within the N-terminal domain of the spike protein of SARS-CoV-2 as a potential candidate. Tracking the prevalence of mutations in this structure resulted in the identification of a hemisphere-dependent seasonal pattern driven by mutational bursts. We propose that the galectin-like structure is a frequent target of mutations because it helps the virus evade or modulate the physiological responses of the host to further its spread and survival. The flexible regions of the N-terminal domain should now become a focus for mitigation through vaccines and therapeutics and for prediction and informed public health decision making.

The marriage of chemokines and galectins as functional heterodimers

Trafficking of leukocytes and their local activity profile are of pivotal importance for many (patho)physiological processes. Fittingly, microenvironments are complex by nature, with multiple mediators originating from diverse cell types and playing roles in an intimately regulated manner. To dissect aspects of this complexity, effectors are initially identified and structurally characterized, thus prompting familial classification and establishing foci of research activity. In this regard, chemokines present themselves as role models to illustrate the diversification and fine-tuning of inflammatory processes. This in turn discloses the interplay among chemokines, their cell receptors and cognate glycosaminoglycans, as well as their capacity to engage in new molecular interactions that form hetero-oligomers between themselves and other classes of effector molecules. The growing realization of versatility of adhesion/growth-regulatory galectins that bind to glycans and proteins and their presence at sites of inflammation led to testing the hypothesis that chemokines and galectins can interact with each other by protein-protein interactions. In this review, we present some background on chemokines and galectins, as well as experimental validation of this chemokine-galectin heterodimer concept exemplified with CXCL12 and galectin-3 as proof-of-principle, as well as sketch out some emerging perspectives in this arena.

The Role of Epithelial Damage in the Pulmonary Immune Response

Pulmonary epithelial cells are widely considered to be the first line of defence in the lung and are responsible for coordinating the innate immune response to injury and subsequent repair. Consequently, epithelial cells communicate with multiple cell types including immune cells and fibroblasts to promote acute inflammation and normal wound healing in response to damage. However, aberrant epithelial cell death and damage are hallmarks of pulmonary disease, with necrotic cell death and cellular senescence contributing to disease pathogenesis in numerous respiratory diseases such as idiopathic pulmonary fibrosis (IPF), chronic obstructive pulmonary disease (COPD) and coronavirus disease (COVID)-19. In this review, we summarise the literature that demonstrates that epithelial damage plays a pivotal role in the dysregulation of the immune response leading to tissue destruction and abnormal remodelling in several chronic diseases. Specifically, we highlight the role of epithelial-derived damage-associated molecular patterns (DAMPs) and senescence in shaping the immune response and assess their contribution to inflammatory and fibrotic signalling pathways in the lung.

Galectin-1 secreted by bone marrow-derived mesenchymal stem cells mediates anti-inflammatory responses in acute airway disease

The hallmarks of allergic airway disease (AAD) include infiltration of inflammatory cells into the bronchoalveolar space. Bone marrow derived mesenchymal stem cells (BMSCs) show anti-inflammatory properties in AAD. In addition, galectin-1 (Gal-1) is a lectin significantly upregulated upon inflammation and is also known to mediate potential anti-inflammatory responses. We hypothesized that BMSCs regulated inflammatory responses by secretion of Gal-1 during AAD pathogenesis. BMSCs were isolated from murine femurs and tibiae and adoptively transferred into an ovalbumin-induced AAD mouse model. Knockdown of Gal-1 in BMSCs was performed using shRNA. Flow cytometry, ELISAs, and immunohistology were performed to analyze inflammatory responses in mice, and a Transwell system was used to establish an in vitro co-culture system of lung epithelial cells (MLE-12) and BMSCs. Administration of BMSCs significantly upregulated Gal-1 expression upon inflammation and decreased infiltration of inflammatory cells and secretion of proinflammatory cytokines in vivo. In addition, we showed that this function was mediated by reduced activation of the MAPK p38 signaling pathway. Similar observations were found using an in vitro lipopolysaccharide-induced model when MLE-12 cells were co-cultured with BMSCs. Gal-1 secretion by BMSCs alleviated inflammatory responses observed in AAD and hence provides a promising therapeutic alternative to AAD patients insensitive to conventional drug treatments.

Therapeutic potential of galectin-1 and galectin-3 in autoimmune diseases

Galectins are a highly conserved protein family that binds to β-galactosides. Different members of this family play a variety of biological functions in physiological and pathological processes such as angiogenesis, regulation of immune cell activity, and cell adhesion. Galectins are widely distributed and play a vital role both inside and outside cells. It can regulate homeostasis and immune function in vivo through mechanisms such as apoptosis. Recent studies indicate that galectins exhibit pleiotropic roles in inflammation. Furthermore, emerging studies have found that galectins are involved in the occurrence and development of autoimmune diseases such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), type 1 diabetes (T1D) and systemic sclerosis (SSc) by regulating cell adhesion, apoptosis, and other mechanisms. This review will briefly discuss the biological characteristics of the two most widely expressed and extensively explored members of the galectin family, galectin-1 and galectin-3, as well as their pathogenetic and therapeutic roles in autoimmune diseases. These information may provide a novel and promising therapeutic target for autoimmune diseases.

Protozoan-Viral-Bacterial Co-Infections Alter Galectin Levels and Associated Immunity Mediators in the Female Genital Tract

Co-infections with sexually transmittable pathogens are common and more likely in women with disturbed vaginal bacteriome. Among those pathogens, the protozoan parasite Trichomonas vaginalis (TV) is most common after accounting for the highly persistent DNA viruses human papillomavirus (HPV) and genital herpes. The parasitic infection often concurs with the dysbiotic syndrome diagnosed as bacterial vaginosis (BV) and both are associated with risks of superimposed viral infections. Yet, the mechanisms of microbial synergisms in evading host immunity remain elusive. We present clinical and experimental evidence for a new role of galectins, glycan-sensing family of proteins, in mixed infections. We assessed participants of the HIV Epidemiology Research Study (HERS) at each of their incident TV visits (223 case visits) matched to controls who remained TV-negative throughout the study. Matching criteria included age, race, BV (by Nugent score), HIV status, hysterectomy, and contraceptive use. Non-matched variables included BV status at 6 months before the matched visit, and variables examined at baseline, within 6 months of and/or at the matched visit e.g. HSV-2, HPV, and relevant laboratory and socio-demographic parameters. Conditional logistic regression models using generalized estimating equations calculated odds ratios (OR) for incident TV occurrence with each log₁₀ unit higher cervicovaginal concentration of galectins and cytokines. Incident TV was associated with higher levels of galectin-1, galectin-9, IL-1β and chemokines (ORs 1.53 to 2.91, p <0.001). Galectin-9, IL-1β and chemokines were up and galectin-3 down in TV cases with BV or intermediate Nugent versus normal Nugent scores (p <0.001). Galectin-9, IL-1β and chemokines were up in TV-HIV and down in TV-HPV co-infections. In-vitro, TV synergized with its endosymbiont Trichomonasvirus (TVV) and BV bacteria to upregulate galectin-1, galectin-9, and inflammatory cytokines. The BV-bacterium Prevotella bivia alone and together with TV downregulated galectin-3 and synergistically upregulated galectin-1, galectin-9 and IL-1β, mirroring the clinical findings of mixed TV–BV infections. P. bivia also downregulated TVV+TV-induced anti-viral response e.g. IP-10 and RANTES, providing a mechanism for conducing viral persistence in TV-BV co-infections. Collectively, the experimental and clinical data suggest that galectin-mediated immunity may be dysregulated and exploited by viral–protozoan–bacterial synergisms exacerbating inflammatory complications from dysbiosis and sexually transmitted infections.

Proteomic analysis of differentially expressed whey proteins in Saanen goat milk from different provinces in China using a data-independent acquisition technique

Whey proteins of Saanen goat milk samples from 3 provinces in China (Guangdong, GD; Inner Mongolia, IM; Shaanxi, SX) were characterized and compared using data-independent acquisition quantitative proteomics technique. A total of 550 proteins were quantified in all 3 samples. There were 44, 44, and 33 differentially expressed proteins (DEP) for GD versus IM, GD versus SX, and IM versus SX, respectively. Gene ontology annotation analysis showed that the largest number of DEP for the 3 comparisons were as follows: for biological processes: response to progesterone, glyceraldehyde-3-phosphate metabolic process, and negative regulation of megakaryocyte differentiation; for molecular functions: antioxidant activity, binding, and peroxiredoxin activity; and for cellular components: the same category of extracellular regions for the 3 comparisons, respectively. Pathways for the DEP of 3 comparisons were (1) disease; (2) synthesis and metabolism; and (3) synthesis, degradation, and metabolism. Protein-protein interaction network analysis showed that DEP for GD versus SX had the most interactions.

Galectin-3 as prognostic biomarker in patients with COVID-19 acute respiratory failure

Objectives

Galectin-3 is β-galactoside-binding lectin with several roles in immune-inflammatory response. To date, there is no evidence of Galectin-3 role as a prognostic biomarker in COVID-19 disease. The aim of this study is to clarify the prognostic role of Galectin-3 in patients with COVID 19 acute respiratory failure.

Methods

We enrolled 156 consecutive patients with COVID-19 disease. Routine laboratory test, arterial blood gas, chest X-ray or Computed Tomography and Galectin-3 dosage were performed. The primary outcome was to assess Galectin-3 predictive power for 30-day mortality. Secondary outcomes were 30-day Intensive Care Unit admission and Acute Respiratory Distress Syndrome stratification according to Galectin-3 dosage. We performed Mann-Whitney U and Kruskal-Wallis tests for continuous variables comparison. Fisher's exact test or Chi-square test were used for categorical variables analysis. Receiver Operating Characteristic curves estimated Galectin-3 predictive power for the endpoints. With a fixed cut-off of 35.3 ng/ml, Kaplan-Meier with Log-Rank test and Cox Regression were performed to assess mortality and Intensive Care Unit admission risk.

Results

Galectin-3 correlated with many other prognostic predictors tested in our analysis. Moreover, patients with serum levels of Galectin-3 above 35.3 ng/ml had increased risk for mortality, Intensive Care Unit admission and severe Acute Respiratory Distress Syndrome.

Conclusions

Our study demonstrates the role of Galectin-3 as a predictor of mortality, Intensive Care Unit access and ARDS stratification in patients with COVID 19 acute respiratory failure.

Postharvest Drying Techniques Regulate Secondary Metabolites and Anti-Neuroinflammatory Activities of Ganoderma lucidum

Ganoderma lucidum extract is a potent traditional remedy for curing various ailments. Drying is the most important postharvest step during the processing of Ganoderma lucidum. The drying process mainly involves heat (36 h at 60 °C) and freeze-drying (36 h at −80 °C). We investigated the effects of different postharvest drying protocols on the metabolites profiling of Ganoderma lucidum using GC-MS, followed by an investigation of the anti-neuroinflammatory potential in LPS-treated BV2 microglial cells. A total of 109 primary metabolites were detected from heat and freeze-dried samples. Primary metabolite profiling showed higher levels of amino acids (17.4%) and monosaccharides (8.8%) in the heat-dried extracts, whereas high levels of organic acids (64.1%) were present in the freeze-dried samples. The enzymatic activity, such as ATP-citrate synthase, pyruvate kinase, glyceraldehyde-3-phosphatase dehydrogenase, glutamine synthase, fructose-bisphosphate aldolase, and D-3-phosphoglycerate dehydrogenase, related to the reverse tricarboxylic acid cycle were significantly high in the heat-dried samples. We also observed a decreased phosphorylation level of the MAP kinase (Erk1/2, p38, and JNK) and NF-κB subunit p65 in the heat-dried samples of the BV2 microglia cells. The current study suggests that heat drying improves the production of ganoderic acids by the upregulation of TCA-related pathways, which, in turn, gives a significant reduction in the inflammatory response of LPS-induced BV2 cells. This may be attributed to the inhibition of NF-κB and MAP kinase signaling pathways in cells treated with heat-dried extracts.

Interleukin-18 Is a Potential Biomarker to Discriminate Active Adult-Onset Still's Disease From COVID-19

Background

Hyperinflammation with dysregulated production of galectins and cytokines may develop in COVID-19 or adult-onset Still's disease (AOSD). Given the similar clinical features in both diseases, it is necessary to identify biomarkers that can differentiate COVID-19 from AOSD. However, the related data remain scarce currently.

Methods

In this cross-sectional study, plasma levels of galectin-3, galectin-9, and soluble TIM-3 (sTIM-3) were determined by ELISA in 55 COVID-19 patients (31 non-severe and 24 severe), 23 active AOSD patients, and 31 healthy controls (HC). The seropositivity for SARS-CoV-2 was examined using an immunochromatographic assay, and cytokine profiles were determined with the MULTIPLEX platform.

Results

Significantly higher levels of galectin-3, galectin-9, IL-1β, IL-1Ra, IL-10, IFN-α2, IL-6, IL-18, and TNF-α were observed in severe COVID-19 and active AOSD patients compared with HC (all p<0.001). AOSD, but not COVID-19, showed significantly higher IFN-γ and IL-17A compared with HC (both p<0.01). Moreover, active AOSD patients had 68-fold higher IL-18 levels and 5-fold higher ferritin levels than severe COVID-19 patients (both p<0.001). IL-18 levels at the cut-off value 190.5pg/mL had the highest discriminative power for active AOSD and severe COVID-19, with AUC 0.948, sensitivity 91.3%, specificity 95.8%, and accuracy of 91.5% (p<0.005). Multivariate regression analysis revealed IL-18 as a significant predictor of active AOSD (p<0.05).

Conclusion

Active AOSD patients share features of hyperinflammation and cytokine storm with severe COVID-19 patients but possess a distinct cytokine profile, including elevated IL-18, IL-6, IFN-γ, and IL-17A. IL-18 is a potential discriminator between AOSD and COVID-19 and may significantly predict active AOSD.