Galectin-9 signaling through TIM-3 is involved in neutrophil-mediated Gram-negative bacterial killing: an effect abrogated within the cystic fibrosis lung

Extracellular vesicles derived from nasopharyngeal carcinoma induce the emergence of mature regulatory dendritic cells using a galectin-9 dependent mechanism

Nasopharyngeal carcinoma-derived small extracellular vesicles (NPCSEVs) have an immunosuppressive impact on the tumour microenvironment. In this study, we investigated their influence on the generation of tolerogenic dendritic cells and the potential involvement of the galectin-9 (Gal9) they carry in this process. We analysed the phenotype and immunosuppressive properties of NPCSEVs and explored the ability of DCs exposed to NPCSEVs (NPCSEV-DCs) to regulate T cell proliferation. To assess their impact at the pathophysiological level, we performed real-time fluorescent chemoattraction assays. Finally, we analysed phenotype and immunosuppressive functions of NPCSEV-DCs using a proprietary anti-Gal9 neutralising antibody to assess the role of Gal9 in this effect. We described that NPCSEV-DCs were able to inhibit T cell proliferation despite their mature phenotype. These mature regulatory DCs (mregDCs) have a specific oxidative metabolism and secrete high levels of IL-4. Chemoattraction assays revealed that NPCSEVs could preferentially recruit NPCSEV-DCs. Finally, and very interestingly, the reduction of the immunosuppressive function of NPCSEV-DCs using an anti-Gal9 antibody clearly suggested an important role for vesicular Gal9 in the induction of mregDCs. These results revealed for the first time that NPCSEVs promote the emergence of mregDCs using a galectin-9 dependent mechanism and open new perspectives for antitumour immunotherapy targeting NPCSEVs.

Galectin-9 Expression is Correlated to Cervical Squamous Cell Carcinoma Progression and Overall Survival

Purpose

To determine whether galectin-9 gene (LGALS9) expression is correlated with cervical cancer progression, clinicopathological characteristics, and overall survival. To determine the biological processes and the abundance of tumour infiltrating immune cells related to the expression of LGALS9.

Patients and Methods

The study was conducted in two phases: 1) The expression level of LGALS9 was determined using the data of 193 squamous cell carcinoma (SCC) samples from The Cancer Genome Atlas (TCGA) database. Biological processes and tumour infiltrating cells associated to LGALS9 expression were evaluated using gene set enrichment analysis (GSEA) and tumour immune estimation resource (TIMER). 2) Independently, galectin-9 was identified in 40 SCC samples by immunohistochemistry and optical density quantified using ImagePro® software.

Results

The LGALS9 gene showed increased expression in cervical cancer samples. A higher expression level in SCC was related to better overall survival and to early clinical stages. GSEA showed that tumours with higher expression of LGALS9 were enriched in immune pathways such as interferon_alpha_response, and complement, the analysis of TIMER database showed a positive correlation between the expression level of LGALS9 and the abundance of tumour infiltrating immune cells. In addition, higher expression of galectin-9 was found in biopsies of SCC patients at early clinical stages, showing a trend of better survival.

Conclusion

Higher expression levels of LGALS9 and galectin-9 in SCC were related to early clinical stages and better prognosis. GSEA and TIMER analysis suggested that galectin-9 could play an antitumor role in cervical SCC.

Deficient Complement Opsonization Impairs Mycobacterium avium Killing by Neutrophils in Cystic Fibrosis

Nontuberculous mycobacteria (NTM), including Mycobacterium avium, are clinically important pathogens in cystic fibrosis (CF). The innate immune response to M. avium remains incompletely understood. We evaluated the role of complement opsonization in neutrophil-mediated killing of M. avium. Killing assays were performed using neutrophils from healthy donors (HDs) and persons with CF (pwCF). Clinical isolates of M. avium were opsonized with plasma from HDs or pwCF, which was intact or heat-treated to inactivate complement. HD neutrophils had killing activity against M. avium opsonized with intact HD plasma and killing was significantly reduced when M. avium was opsonized with heat-inactivated HD plasma. When opsonized with HD plasma, CF neutrophils had killing activity against M. avium that was not different than HD neutrophils. When opsonized with intact plasma from pwCF, HD neutrophil killing of M. avium was significantly reduced. Opsonization of M. avium with C3-depleted serum or IgM-depleted plasma resulted in significantly reduced killing. Plasma C3 levels were elevated in pwCF with NTM infection compared to pwCF without NTM infection. These studies demonstrate that human neutrophils efficiently kill M. avium when opsonized in the presence of plasma factors from HD that include C3 and IgM. Killing efficiency is significantly lower when the bacteria are opsonized with plasma from pwCF. This indicates a novel role for opsonization in neutrophil killing of M. avium and a deficiency in complement opsonization as a mechanism of impaired M. avium killing in CF. IMPORTANCE Mycobacterium avium is a member of a group of bacterial species termed nontuberculous mycobacteria (NTM) that cause lung disease in certain populations, including persons with cystic fibrosis (CF). NTM infections are challenging to diagnose and can be even more difficult to treat. This study investigated how the immune system responds to M. avium infection in CF. We found that neutrophils, the most abundant immune cell in the lungs in CF, can effectively kill M. avium in individuals both with and without CF. Another component of the immune response called the complement system is also required for this process. Levels of complement proteins are altered in persons with CF who have a history of NTM compared to those without a history of NTM infection. These results add to our understanding of how the immune system responds to M. avium, which can help pave the way toward better diagnostic and treatment strategies.

The sweet side of wound healing: galectins as promising therapeutic targets in hemostasis, inflammation, proliferation, and maturation/remodeling

INTRODUCTION

Understanding the molecular and cellular processes involved in skin wound healing may pave the way for the development of innovative approaches to transforming the identified natural effectors into therapeutic tools. Based on the extensive involvement of the ga(lactoside-binding)lectin family in (patho)physiological processes, it has been well established that galectins are involved in a wide range of cell-cell and cell-matrix interactions.

AREAS COVERED

In the present paper, we provide an overview of the biological role of galectins in repair and regeneration, focusing on four main phases (hemostasis, inflammation, proliferation, and maturation/remodeling) of skin repair using basic wound models (open excision vs. sutured incision).

EXPERT OPINION

The reported data make a strong case for directing further efforts to treat excisional and incisional wounds differently. Functions of galectins essentially result from their modular presentation. In fact, Gal-1 seems to play a role in the early phases of healing (anti-inflammatory) and wound contraction, Gal-3 accelerates re-epithelization and increases tensile strength (scar inductor). Galectins have also become subject of redesigning by engineering to optimize the activity. Clinically relevant, these new tools derived from the carbohydrate recognition domain platform may also prove helpful for other purposes, such as potent antibacterial agglutinins and opsonins.

Galectokines: The Promiscuous Relationship between Galectins and Cytokines

Galectins, a family of glycan-binding proteins, are well-known for their role in shaping the immune microenvironment. They can directly affect the activity and survival of different immune cell subtypes. Recent evidence suggests that galectins also indirectly affect the immune response by binding to members of another immunoregulatory protein family, i.e., cytokines. Such galectin-cytokine heterodimers, here referred to as galectokines, add a new layer of complexity to the regulation of immune homeostasis. Here, we summarize the current knowledge with regard to galectokine formation and function. We describe the known and potential mechanisms by which galectokines can help to shape the immune microenvironment. Finally, the outstanding questions and challenges for future research regarding the role of galectokines in immunomodulation are discussed.

Detection of Reactive Oxygen Species in Human Neutrophils Under Various Conditions of Exposure to Galectin

Reactive oxygen species (ROS) have been extensively studied in biology in the past years. This class of molecules can be derived from endogenous sources (e.g., phagocytic cells as neutrophils, eosinophils, monocytes, macrophages, and organelles as mitochondria and peroxisomes) and participate in physiological and pathological conditions. The beneficial and harmful effects of ROS depend on redox regulation, which establishes the balance between their production and the activity of antioxidant systems to prevent oxidative stress in vivo. Neutrophils are the immune effectors most well depicted with an intense oxidative burst in response to tissue inflammation. Several proteins and members of the galectin family are involved in this fine modulation of ROS production by neutrophils. Interestingly, studies have indicated that Galectin-1 (Gal-1) can up- or downregulate ROS production by neutrophils even when exposed to N-formyl-Met-Leu-Phe (fMLP) or Phorbol Myristate Acetate (PMA), both of which are potent neutrophil stimulants that trigger high levels of ROS production. Similarly, Galectin-3 (Gal-3) induces ROS in neutrophils from a sterile or nonsterile inflammatory environment, possibly creating a negative loop that could control ROS production. Besides, superoxide production is also induced by Galectin-8 (Gal-8) and Galectin-9 (Gal-9) in neutrophils but in a different manner. We describe herein the luminol and lucigenin-dependent chemiluminescence technique by using a luminometer as a method of assessment to measure ROS production by human neutrophils isolated and exposed to purified human recombinant Gal-1. The protocol described herein could be applied for the investigation of the role of other galectins in the modulation of ROS production by neutrophils.

Galectin-9 Triggers Neutrophil-Mediated Anticancer Immunity

In earlier studies, galectin-9 (Gal-9) was identified as a multifaceted player in both adaptive and innate immunity. Further, Gal-9 had direct cytotoxic and tumor-selective activity towards cancer cell lines of various origins. In the current study, we identified that treatment with Gal-9 triggered pronounced membrane alterations in cancer cells. Specifically, phosphatidyl serine (PS) was rapidly externalized, and the anti-phagocytic regulator, CD47, was downregulated within minutes. In line with this, treatment of mixed neutrophil/tumor cell cultures with Gal-9 triggered trogocytosis and augmented antibody-dependent cellular phagocytosis of cancer cells. Interestingly, this pro-trogocytic effect was also due to the Gal-9-mediated activation of neutrophils with upregulation of adhesion markers and mobilization of gelatinase, secretory, and specific granules. These activation events were accompanied by a decrease in cancer cell adhesion in mixed cultures of leukocytes and cancer cells. Further, prominent cytotoxicity was detected when leukocytes were mixed with pre-adhered cancer cells, which was abrogated when neutrophils were depleted. Taken together, Gal-9 treatment potently activated neutrophil-mediated anticancer immunity, resulting in the elimination of epithelial cancer cells.

Galectin-9 mediates neutrophil capture and adhesion in a CD44 and β2 integrin-dependent manner

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.

Functional role of galectin-9 in directing human innate immune reactions to Gram-negative bacteria and T cell apoptosis

Galectin-9 is a member of the galectin family of proteins, which were first identified to specifically bind to carbohydrates containing β-galactosides. Galectin-9 is conserved through evolution and recent evidence demonstrated its involvement in innate immune reactions to bacterial infections as well as the suppression of cytotoxic immune responses of T and natural killer cells. However, the molecular mechanisms underlying such differential immunological functions of galectin-9 remain largely unknown. In this work we confirmed that soluble galectin-9 derived from macrophages binds to Gram-negative bacteria by interacting with lipopolysaccharide (LPS), which forms their cell wall. This opsonisation effect most likely interferes with the mobility of bacteria leading to their phagocytosis by innate immune cells. Galectin-9-dependent opsonisation also promotes the innate immune reactions of macrophages to these bacteria and significantly enhances the production of pro-inflammatory cytokines - interleukin (IL) 6, IL-1β and tumour necrosis factor alpha (TNF-α). In contrast, galectin-9 did not bind peptidoglycan (PGN), which forms the cell wall of Gram-positive bacteria. Moreover, galectin-9 associated with cellular surfaces (studied in primary human embryonic cells) was not involved in the interaction with bacteria or bacterial colonisation. However, galectin-9 expressed on the surface of primary human embryonic cells, as well as soluble forms of galectin-9, were able to target T lymphocytes and caused apoptosis in T cells expressing granzyme B. Furthermore, "opsonisation" of T cells by galectin-9 led to the translocation of phosphatidylserine onto the cell surface and subsequent phagocytosis by macrophages through Tim-3, the receptor, which recognises both galectin-9 and phosphatidylserine as ligands.

A human receptor occupancy assay to measure anti-PD-1 binding in patients with prior anti-PD-1

Receptor occupancy (RO) assessment by flow cytometry is an important pharmacodynamic (PD) biomarker in the clinical development of large molecules such as monoclonal therapeutic antibodies (mAbs). The total‐drug‐bound RO assay format directly assesses mAb binding to cell surface targets using anti‐drug detection antibodies. Here, we generated a flow cytometry detection antibody specifically binding to mAbs of the IgG₁ P329GLALA backbone. Using this reagent, we developed a total‐drug‐bound RO assay format for RG7769, a bi‐specific P329GLALA containing mAb targeting PD‐1 and TIM3 on T cells. In its fit‐for‐purpose validated version, this RO assay has been used in the Phase‐I dose escalation study of RG7769, informing on peripheral T cell RO and RG7769 antibody binding capacity (ABC). We assessed RG7769 RO in checkpoint‐inhibitor (CPI) naïve patients and anti‐PD‐1 CPI experienced patients using our novel assay. Here, we show that in both groups, complete T cell RO can be achieved (~100%). However, we found that the maximum number of T cell binding sites for RG7769 pre‐dosing was roughly twofold lower in patients recently having undergone anti‐PD‐1 treatment. We show that this is due to steric hindrance exerted by competing mAbs masking the available drug binding sites. Our findings highlight the importance of quantitative mAb assessment in addition to relative RO especially in the context of patients who have previously received anti‐PD‐1 treatment.

Identification of Common Genes and Pathways in Eight Fibrosis Diseases

Acute and chronic inflammation often leads to fibrosis, which is also the common and final pathological outcome of chronic inflammatory diseases. To explore the common genes and pathogenic pathways among different fibrotic diseases, we collected all the reported genes of the eight fibrotic diseases: eye fibrosis, heart fibrosis, hepatic fibrosis, intestinal fibrosis, lung fibrosis, pancreas fibrosis, renal fibrosis, and skin fibrosis. We calculated the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) enrichment scores of all fibrotic disease genes. Each gene was encoded using KEGG and GO enrichment scores, which reflected how much a gene can affect this function. For each fibrotic disease, by comparing the KEGG and GO enrichment scores between reported disease genes and other genes using the Monte Carlo feature selection (MCFS) method, the key KEGG and GO features were identified. We compared the gene overlaps among eight fibrotic diseases and connective tissue growth factor (CTGF) was finally identified as the common key molecule. The key KEGG and GO features of the eight fibrotic diseases were all screened by MCFS method. Moreover, we interestingly found overlaps of pathways between renal fibrosis and skin fibrosis, such as GO:1901890-positive regulation of cell junction assembly, as well as common regulatory genes, such as CTGF, which is the key molecule regulating fibrogenesis. We hope to offer a new insight into the cellular and molecular mechanisms underlying fibrosis and therefore help leading to the development of new drugs, which specifically delay or even improve the symptoms of fibrosis.

Galectin-9 as a biomarker of disease severity

Galectin-9 (Gal-9) is a β-galactoside binding lectin known for its immunomodulatory role in various microbial infections. Gal-9 is expressed in all organ systems and localized in the nucleus, cell surface, cytoplasm and the extracellular matrix. It mediates host-pathogen interactions and regulates cell signalling via binding to its receptors. Gal-9 is involved in many physiological functions such as cell growth, differentiation, adhesion, communication and death. However, recent studies have emphasized on the elevated levels of Gal-9 in autoimmune disorders, viral infections, parasitic invasion, cancer, acute liver failure, atopic dermatitis, chronic kidney disease, type-2 diabetes, coronary artery disease, atherosclerosis and benign infertility-related gynecological disorders. In this paper we have reviewed the potential of Gal-9 as a reliable, sensitive and non-invasive biomarker of disease severity. Tracking changes in Gal-9 levels and its implementation as a biomarker in clinical practice will be an important tool to monitor disease activity and facilitate personalized treatment decisions.

Molecular Identification and mRNA Expression Profiles of Galectin-9 Gene in Red Sea Bream (Pagrus major) Infected with Pathogens

Galectin (Gal) is a member of a family of β-galactoside-binding lectin. The members of this family play important roles in the recognition of carbohydrate ligands and in various other biological processes. In this study, we identified the gene encoding Gal-9 in Pagrus major (PmGal-9) and analyzed its expression in various tissues after pathogen challenge. Alignment analysis revealed that the two galactose-binding lectin domains of the deduced protein were highly conserved among all the teleosts. Phylogenetic analysis revealed that PmGal-9 is most closely related to the Gal-9 gene of gilthead sea bream. PmGal-9 was ubiquitously expressed in all tissues analyzed but was predominantly expressed in the spleen, head kidney, and intestine. After challenges with major microbial pathogens (Edwardsiella piscicida, Streptococcus iniae, or red sea bream iridovirus) of red sea bream, PmGal-9 mRNA expression was significantly regulated in most immune-related tissues. These results suggested that PmGal-9 not only plays an important role in the immune system of red sea bream but is also a possible inflammatory marker for pathogenic diseases.

Potential Role of the Galectin-9/TIM-3 Axis in the Disparate Progression of SARS-CoV-2 in a Married Couple: A Case Report

We report the disparate clinical progression of a couple infected by SARS-CoV-2 based on their immune checkpoint (IC) levels and immune cell distribution in blood from admission to exitus in patient 1 and from admission to discharge and recovery in patient 2. A detailed clinical follow-up accompanied by a longitudinal analysis of immune phenotypes and IC levels is shown. The continuous increase in the soluble IC ligand galectin-9 (Gal-9) and the increment in T-cell immunoglobulin and mucin domain-containing 3 (TIM-3) protein in T cells in patient 1 suggests an activation of the Gal-9/TIM-3 axis and, subsequently, a potential cell exhaustion in this patient that did not occur in patient 2. Our data indicate that the Gal-9/TIM-3 axis could be a potential target in this clinical setting, along with a patent effector memory T-cell reduction.

Altered Degranulation and pH of Neutrophil Phagosomes Impacts Antimicrobial Efficiency in Cystic Fibrosis

Studies have endeavored to understand the cause for impaired antimicrobial killing by neutrophils of people with cystic fibrosis (PWCF). The aim of this study was to focus on the bacterial phagosome. Possible alterations in degranulation of cytoplasmic granules and changes in pH were assessed. Circulating neutrophils were purified from PWCF (n = 28), PWCF receiving ivacaftor therapy (n = 10), and healthy controls (n = 28). Degranulation was assessed by Western blot analysis and flow cytometry. The pH of phagosomes was determined by use of BCECF-AM-labelled Staphylococcus aureus or SNARF labelled Candida albicans. The antibacterial effect of all treatments tested was determined by colony forming units enumeration. Bacterial killing by CF and healthy control neutrophils were found to differ (p = 0.0006). By use of flow cytometry and subcellular fractionation the kinetics of intraphagosomal degranulation were found to be significantly altered in CF phagosomes, as demonstrated by increased primary granule CD63 (p = 0.0001) and myeloperoxidase (MPO) content (p = 0.03). In contrast, decreased secondary and tertiary granule CD66b (p = 0.002) and decreased hCAP-18 and MMP-9 (p = 0.02), were observed. After 8 min phagocytosis the pH in phagosomes of neutrophils of PWCF was significantly elevated (p = 0.0001), and the percentage of viable bacteria was significantly increased compared to HC (p = 0.002). Results demonstrate that the recorded alterations in phagosomal pH generate suboptimal conditions for MPO related peroxidase, and α-defensin and azurocidine enzymatic killing of Staphylococcus aureus and Pseudomonas aeruginosa. The pattern of dysregulated MPO degranulation (p = 0.02) and prolonged phagosomal alkalinization in CF neutrophils were normalized in vivo following treatment with the ion channel potentiator ivacaftor (p = 0.04). Our results confirm that alterations of circulating neutrophils from PWCF are corrected by CFTR modulator therapy, and raise a question related to possible delayed proton channel activity in CF.

Genotype C/C 13910 of the Lactase Gene as a Risk Factor for the Formation of Insulin-Resistant Obesity in Children

INTRODUCTION

To reduce the risk of insulin resistance in obesity in children with lactase gene genotypes, we studied the factors that stimulate the chronic inflammatory process.

MATERIAL AND METHODS

109 children 6-18 years of age were investigated. The main group (n = 56) was presented by children with signs of insulin-resistant obesity according to the criteria of the European Society of Endocrinology and the Pediatric Endocrine Society. The control group (n = 53) included obese children without insulin resistance. A comprehensive clinical examination, food diary analysis, genotyping of the lactase gene by means of the polymerase chain reaction, the Immunochemical Test Method with Electrochemiluminescent Detection of basal insulinemia, Hydrogen breath test with lactose load, sequential analysis, ROC analysis were carried out.

RESULTS

Clinical manifestations of lactose maldigestion in a child increased the risk of possible insulin resistance (prognostic coefficient (PC +2.6), as well as the presence of the lactase C/C 13910 gene genotype (PC +5.8) did. The genotype C/T 13910 in children had a protective effect on the risk of obesity (PC -2.9). The lowest risk of insulin-resistant obesity in observed among children with the genotype T/T 13910 (PC -12).

CONCLUSION

The presence of the C/C 13910 genotype of the lactase gene is the main factor formation of insulin resistance in children's obesity. What is known? The genotype C/C 13910 of the lactase gene as a risk factor for the chronic inflammatory process in the body. What is New? Genotype C/C 13910 of the lactase gene as a risk factor for insulin-resistant obesity in children.

Galectin-9 Is a Possible Promoter of Immunopathology in Rheumatoid Arthritis by Activation of Peptidyl Arginine Deiminase 4 (PAD-4) in Granulocytes

The aetiology of rheumatoid arthritis (RA) is unknown, but citrullination of proteins is thought to be an initiating event. In addition, it is increasingly evident that the lung can be a potential site for the generation of autoimmune triggers before the development of joint disease. Here, we identified that serum levels of galectin-9 (Gal-9), a pleiotropic immunomodulatory protein, are elevated in RA patients, and are even further increased in patients with comorbid bronchiectasis, a lung disease caused by chronic inflammation. The serum concentrations of Gal-9 correlate with C-reactive protein levels and DAS-28 score. Gal-9 activated polymorphonuclear leukocytes (granulocytes) in vitro, which was characterized by increased cytokine secretion, migration, and survival. Further, granulocytes treated with Gal-9 upregulated expression of peptidyl arginine deiminase 4 (PAD-4), a key enzyme required for RA-associated citrullination of proteins. Correspondingly, treatment with Gal-9 triggered citrullination of intracellular granulocyte proteins that are known contributors to RA pathogenesis (i.e., myeloperoxidase, alpha-enolase, MMP-9, lactoferrin). In conclusion, this study identifies for the first time an immunomodulatory protein, Gal-9, that triggers activation of granulocytes leading to increased PAD-4 expression and generation of citrullinated autoantigens. This pathway may represent a potentially important mechanism for development of RA.

The Sweet-Side of Leukocytes: Galectins as Master Regulators of Neutrophil Function

Among responders to microbial invasion, neutrophils represent one of the earliest and perhaps most important factors that contribute to initial host defense. Effective neutrophil immunity requires their rapid mobilization to the site of infection, which requires efficient extravasation, activation, chemotaxis, phagocytosis, and eventual killing of potential microbial pathogens. Following pathogen elimination, neutrophils must be eliminated to prevent additional host injury and subsequent exacerbation of the inflammatory response. Galectins, expressed in nearly every tissue and regulated by unique sensitivity to oxidative and proteolytic inactivation, appear to influence nearly every aspect of neutrophil function. In this review, we will examine the impact of galectins on neutrophils, with a particular focus on the unique biochemical traits that allow galectin family members to spatially and temporally regulate neutrophil function.

Galectin-9 Alleviates LPS-Induced Preeclampsia-Like Impairment in Rats via Switching Decidual Macrophage Polarization to M2 Subtype

Dysfunction of decidual macrophages (DMs) is considered a critical event in the pathogenesis of pre-eclampsia (PE). T cell immunoglobulin mucin 3 (Tim-3) is an important negative regulatory molecule that induces immune tolerance by interacting with its ligand Galectin-9 (Gal-9) and thus modulating function of various immune cells, including macrophages. However, the regulatory effects of Tim-3/Gal-9 signaling on DMs polarization and its role in PE remain unclear. In this study, we established a PE-like rat model by administering 1.0 μg/kg lipopolysaccharide (LPS) to normal pregnant Sprague-Dawley rats via the tail vein at embryonic day 5 (E5). Apart from the pre-eclamptic manifestations, increased M1 subtype and decreased M2 subtype were observed at the maternal-fetal interface, as well as increased pro-inflammatory cytokines (TNF-α and IL-1β) and reduced anti-inflammatory cytokines (TGF-β and IL-10). Moreover, the expression of Tim-3 in DMs and that of Gal-9 at the maternal-fetal interface were reduced. After administration of recombinant Galectin-9 (rGal-9) protein, we found that liver and renal injuries and maternofetal placental functional deficiency, including inadequate trophoblast cells invasion, impaired spiral artery remodeling and fetal capillary development, were reversed. In addition, the polarization of DMs was inclined to M2 subtype, which was similar to the polarization of DMs in the control rats but contrary to the PE-like rats. Interestingly, at E9, the expression of Tim-3 in DMs and that of Gal-9 at the maternal-fetal interface were significantly increased in the rGal-9 protein intervention group. Taken together, our findings show that administration of rGal-9 protein can alleviate the PE-like rat manifestations induced by LPS. This finding may be related to the activation of the Tim-3/Gal-9 signaling pathway, which promotes DMs polarization dominantly shifting to M2 subtype. Moreover, upregulation of Tim-3 in DMs and Gal-9 at the maternal-fetal interface at E9 suggests that Tim-3/Gal-9 pathway may play some important roles in early pregnancy and even embryo development.

The Role of Collectins and Galectins in Lung Innate Immune Defense

Different families of endogenous lectins use complementary defense strategies against pathogens. They may recognize non-self glycans typically found on pathogens and/or host glycans. The collectin and galectin families are prominent examples of these two lectin categories. Collectins are C-type lectins that contain a carbohydrate recognition domain and a collagen-like domain. Members of this group include surfactant protein A (SP-A) and D (SP-D), secreted by the alveolar epithelium to the alveolar fluid. Lung collectins bind to several microorganisms, which results in pathogen aggregation and/or killing, and enhances phagocytosis of pathogens by alveolar macrophages. Moreover, SP-A and SP-D influence macrophage responses, contributing to resolution of inflammation, and SP-A is essential for tissue-repair functions of macrophages. Galectins also function by interacting directly with pathogens or by modulating the immune system in response to the infection. Direct binding may result in enhanced or impaired infection of target cells, or can have microbicidal effects. Immunomodulatory effects of galectins include recruitment of immune cells to the site of infection, promotion of neutrophil function, and stimulation of the bactericidal activity of infected macrophages. Moreover, intracellular galectins can serve as danger receptors, promoting autophagy of the invading pathogen. This review will focus on the role of collectins and galectins in pathogen clearance and immune response activation in infectious diseases of the respiratory system.

The impact of alpha-1 antitrypsin augmentation therapy on neutrophil-driven respiratory disease in deficient individuals

Alpha-1 antitrypsin (AAT) is the most abundant serine protease inhibitor circulating in the blood. AAT deficiency (AATD) is an autosomal codominant condition affecting an estimated 3.4 million individuals worldwide. The clinical disease associated with AATD can present in a number of ways including COPD, liver disease, panniculitis and antineutrophil cytoplasmic antibody vasculitis. AATD is the only proven genetic risk factor for the development of COPD, and deficient individuals who smoke are disposed to more aggressive disease. Principally, AAT is a serine protease inhibitor; however, over the past number of years, the assessment of AAT as simply an antiprotease has evolved, and it is now recognized that AAT has significant anti-inflammatory properties affecting a wide range of cells, including the circulating neutrophil.

Interleukin 8 activity influences the efficacy of adenoviral oncolytic immunotherapy in cancer patients

After the landmark approval of T-VEC, oncolytic viruses are finding their way to the clinics. However, response rates have still room for improvement, and unfortunately there are currently no available markers to predict responses for oncolytic immunotherapy. Interleukin 8 (IL-8) production is upregulated in many cancers and it also connects to several pathways that have been shown to impair the efficacy of adenoviral immunotherapy. We studied the role of IL-8 in 103 cancer patients treated with oncolytic adenoviruses. We found high baseline serum IL-8 concentration to be independently associated with poor prognosis (p<0.001). Further, normal baseline IL-8 was associated with improved prognostic potential of calculation of the neutrophil-to-lymphocyte ratio (p<0.001). Interestingly, a decrease in IL-8 concentration after treatment with oncolytic adenovirus predicted better overall survival (p<0.001) and higher response rate, although this difference was not significant (p=0.066). We studied the combination of adenovirus and IL-8 neutralizing antibody ex vivo in single cell suspensions and in co-cultures of tumor-associated CD15+ neutrophils and CD3+ tumor-infiltrating lymphocytes derived from fresh patient tumor samples. These results indicate a role for IL-8 as a biomarker in oncolytic virotherapy, but additionally provide a rationale for targeting IL-8 to improve treatment efficacy. In conclusion, curtailing the activity of IL-8 systemically or locally in the tumor microenvironment could improve anti-tumor immune responses resulting in enhanced efficacy of adenoviral immunotherapy of cancer.

Negative regulation of Nod-like receptor protein 3 inflammasome activation by T cell Ig mucin-3 protects against peritonitis

The Nod-like receptor protein 3 (NLRP3) inflammasome plays roles in host defence against invading pathogens and in the development of autoimmune damage. Strict regulation of these responses is important to avoid detrimental effects. Here, we demonstrate that T cell Ig mucin-3 (Tim-3), an immune checkpoint inhibitor, inhibits NLRP3 inflammasome activation by damping basal and lipopolysaccharide-induced nuclear factor-κB-mediated up-regulation of NLRP3 and interleukin-1β during the priming step and basal and ATP/lipopolysaccharide-induced ATP production, K⁺ efflux, and reactive oxygen species production during the activation step. Residues Y256/Y263 in the C-terminal region of Tim-3 are required for these inhibitory effects on the NLRP3 inflammasome. In mice with alum-induced peritonitis, blockade of Tim-3 exacerbates peritonitis by overcoming the inhibitory effect of Tim-3 on NLRP3 inflammasome activation, while transgenic expression of Tim-3 attenuates inflammation by inhibiting NLRP3 inflammasome activation. Our results show that Tim-3 is a critical negative regulator of NLRP3 inflammasome and provides a potential target for intervention of diseases with uncontrolled inflammasome activation.

Protective effect of Galectin-9 in murine model of lung emphysema: Involvement of neutrophil migration and MMP-9 production

Purpose

Chronic obstructive pulmonary disease (COPD) is characterized by irreversible airflow obstruction and pulmonary emphysema. Persistent inflammation and remodeling of the lungs and airways result in reduced lung function and a lower quality of life. Galectin (Gal)-9 plays a crucial role as an immune modulator in various diseases. However, its role in the pathogenesis of pulmonary emphysema is unknown. This study investigates whether Gal-9 is involved in pulmonary inflammation and changes in emphysema in a porcine pancreatic elastase (PPE)-induced emphysema model.

Materials and methods

Gal-9 was administered to mice subcutaneously once daily from 1 day before PPE instillation to day 5. During the development of emphysema, lung tissue and bronchoalveolar lavage fluid (BALF) were collected. Histological and cytological findings, concentrations of chemokines and matrix metalloproteinases (MMPs) in the BALF, and the influence of Gal-9 treatment on neutrophils were analyzed.

Results

Gal-9 suppressed the pathological changes of PPE-induced emphysema. The mean linear intercept (Lm) of Gal-9-treated emphysema mice was significantly lower than that of PBS-treated emphysema mice (66.1 ± 3.3 μm vs. 118.8 ± 14.8 μm, respectively; p < 0.01). Gal-9 decreased the number of neutrophils and levels of MMP-9, MMP-2 and tissue inhibitor of metalloproteinases (TIMP)-1 in the BALF. The number of neutrophils in the BALF correlated significantly with MMPs levels. Interestingly, Gal-9 pretreatment in vitro inhibited the chemotactic activity of neutrophils and MMP-9 production from neutrophils. Furthermore, in Gal-9-deficient mice, PPE-induced emphysema progressed significantly compared with that in wild–type (WT) mice (108.7 ± 6.58 μm vs. 77.19 ± 6.97 μm, respectively; p < 0.01).

Conclusions

These results suggest that Gal-9 protects PPE-induced inflammation and emphysema by inhibiting the infiltration of neutrophils and decreasing MMPs levels. Exogenous Gal-9 could be a potential therapeutic agent for COPD.

Galectin-9: From cell biology to complex disease dynamics

Galectins is a family of non-classically secreted, beta-galactoside-binding proteins that has recently received considerable attention in the spatio-temporal regulation of surface 'signal lattice' organization, membrane dynamics, cell-adhesion and disease therapeutics. Galectin-9 is a unique member of this family, with two non-homologous carbohydrate recognition domains joined by a linker peptide sequence of variable lengths, generating isoforms with distinct properties and functions in both physiological and pathological settings, such as during development, immune reaction, neoplastic transformations and metastasis. In this review, we summarize the latest knowledge on the structure, receptors, cellular targets, trafficking pathways and functional properties of galectin-9 and discuss how galectin-9-mediated signalling cascades can be exploited in cancers and immunotherapies.

Blockage of Galectin-receptor Interactions by α-lactose Exacerbates Plasmodium berghei-induced Pulmonary Immunopathology

Malaria-associated acute lung injury (ALI) is a frequent complication of severe malaria that is often caused by "excessive" immune responses. To better understand the mechanism of ALI in malaria infection, here we investigated the roles of galectin (Gal)-1, 3, 8, 9 and the receptors of Gal-9 (Tim-3, CD44, CD137, and PDI) in malaria-induced ALI. We injected alpha (α)-lactose into mice-infected with Plasmodium berghei ANKA (PbANKA) to block galectins and found significantly elevated total proteins in bronchoalveolar lavage fluid, higher parasitemia and tissue parasite burden, and increased numbers of CD68(+) alveolar macrophages as well as apoptotic cells in the lungs after blockage. Additionally, mRNA levels of Gal-9, Tim-3, CD44, CD137, and PDI were significantly increased in the lungs at day 5 after infection, and the levels of CD137, IFN-α, IFN-β, IFN-γ, IL-4, and IL-10 in the lungs were also increased after α-lactose treatment. Similarly, the levels of Gal-9, Tim-3, IFN-α, IFN-β, IFN-γ, and IL-10 were all significantly increased in murine peritoneal macrophages co-cultured with PbANKA-infected red blood cells in vitro; but only IFN-α and IFN-β were significantly increased after α-lactose treatment. Our data indicate that Gal-9 interaction with its multiple receptors play an important role in murine malaria-associated ALI.

Tim-3 promotes tumor-promoting M2 macrophage polarization by binding to STAT1 and suppressing the STAT1-miR-155 signaling axis

T cell Ig mucin-3 (Tim-3), an immune checkpoint inhibitor, shows therapeutic potential. However, the molecular mechanism by which Tim-3 regulates immune responses remains to be determined. In particular, very little is known about how Tim-3 works in innate immune cells. Here, we demonstrated that Tim-3 is involved in the development of tumor-promoting M2 macrophages in colon cancer. Manipulation of the Tim-3 pathway significantly affected the polarization status of intestinal macrophages and the progression of colon cancer. The Tim-3 signaling pathway in macrophages was explored using microarray, co-immunoprecipitation, gene mutation, and high-content analysis. For the first time, we demonstrated that Tim-3 polarizes macrophages by directly binding to STAT1 via residue Y256 and Y263 in its intracellular tail and inhibiting the STAT1-miR-155-SOCS1 signaling axis. We also identified a new signaling adaptor of Tim-3 in macrophages, and, by modulating the Tim-3 pathway, demonstrated the feasibility of altering macrophage polarization as a potential tool for treating this kind of disease.

Inhaled hypertonic saline for cystic fibrosis: Reviewing the potential evidence for modulation of neutrophil signalling and function

Cystic fibrosis (CF) is a multisystem disorder with significantly shortened life expectancy. The major cause of mortality and morbidity is lung disease with increasing pulmonary exacerbations and decline in lung function predicting significantly poorer outcomes. The pathogenesis of lung disease in CF is characterised in part by decreased airway surface liquid volume and subsequent failure of normal mucociliary clearance. This leads to accumulation of viscous mucus in the CF airway, providing an ideal environment for bacterial pathogens to grow and colonise, propagating airway inflammation in CF. The use of nebulised hypertonic saline (HTS) treatments has been shown to improve mucus clearance in CF and impact positively upon exacerbations, quality of life, and lung function. Several mechanisms of HTS likely improve outcome, resulting in clinically relevant enhancement in disease parameters related to increase in mucociliary clearance. There is increasing evidence to suggest that HTS is also beneficial through its anti-inflammatory properties and its ability to reduce bacterial activity and biofilm formation. This review will first describe the use of HTS in treatment of CF focusing on its efficacy and tolerability. The emphasis will then change to the potential benefits of aerosolized HTS for the attenuation of receptor mediated neutrophil functions, including down-regulation of oxidative burst activity, adhesion molecule expression, and the suppression of neutrophil degranulation of proteolytic enzymes.

Alarmin function of galectin-9 in murine respiratory tularemia

Sepsis is a complex immune disorder that is characterized by systemic hyperinflammation. Alarmins, which are multifunctional endogenous factors, have been implicated in exacerbation of inflammation in many immune disorders including sepsis. Here we show that Galectin-9, a host endogenous β-galactoside binding lectin, functions as an alarmin capable of mediating inflammatory response during sepsis resulting from pulmonary infection with Francisella novicida, a Gram negative bacterial pathogen. Our results show that this galectin is upregulated and is likely released during tissue damage in the lungs of F. novicida infected septic mice. In vitro, purified recombinant galectin-9 exacerbated F. novicida-induced production of the inflammatory mediators by macrophages and neutrophils. Concomitantly, Galectin-9 deficient (Gal-9^-/-) mice exhibited improved lung pathology, reduced cell death and reduced leukocyte infiltration, particularly neutrophils, in their lungs. This positively correlated with overall improved survival of F. novicida infected Gal-9^-/- mice as compared to their wild-type counterparts. Collectively, these findings suggest that galectin-9 functions as a novel alarmin by augmenting the inflammatory response in sepsis development during pulmonary F. novicida infection.

Inflammation in cystic fibrosis lung disease: Pathogenesis and therapy

Lung disease is the major cause of morbidity and mortality in patients with cystic fibrosis (CF). Although CF lung disease is primarily an infectious disorder, the associated inflammation is both intense and ineffective at clearing pathogens. Persistent high-intensity inflammation leads to permanent structural damage of the CF airways and impaired lung function that eventually results in respiratory failure and death. Several defective inflammatory responses have been linked to cystic fibrosis transmembrane conductance regulator (CFTR) deficiency including innate and acquired immunity dysregulation, cell membrane lipid abnormalities, various transcription factor signaling defects, as well as altered kinase and toll-like receptor responses. The inflammation of the CF lung is dominated by neutrophils that release oxidants and proteases, particularly elastase. Neutrophil elastase in the CF airway secretions precedes the appearance of bronchiectasis, and correlates with lung function deterioration and respiratory exacerbations. Anti-inflammatory therapies are therefore of particular interest for CF lung disease but must be carefully studied to avoid suppressing critical elements of the inflammatory response and thus worsening infection. This review examines the role of inflammation in the pathogenesis of CF lung disease, summarizes the results of past clinical trials and explores promising new anti-inflammatory options.

T cells are Smad'ly in love with galectin-9

In this issue of Immunity, Wu et al. (2014) report that galectin-9 is required for the formation and stability of iTreg cells. Galectin-9 interacts with CD44 in association with TGF-β receptors to drive both Foxp3 and galectin-9 expression in a positive-feedforward loop involving Smad3 activation.