Galectin-9 signaling prolongs survival in murine lung-cancer by inducing macrophages to differentiate into plasmacytoid dendritic cell-like macrophages.

Galectin-9 (Gal-9) expanded plasmacytoid dendritic cell-like macrophages (pDC-Mϕs) in lung cancer-bearing mice and prolonged the survival. Gal-9 increased the frequency of CD11c(high) cells in M-CSF- but not GM-CSF-induced Mϕs in vitro in a Tim-3 independent manner. CD11c(high) cells differentiated with M-CSF+Gal-9 expressed pDC-Mϕ markers, such as PDCA-1 and F4/80. These cells expressed high TLR7, TLR8 and TLR9, although they exhibited decreased IFN-α mRNA levels. LPS or LLC stimulation further elevated pDC-Mϕ markers, indicating that M-CSF+Gal-9-induced Mϕs were pDC-Mϕ precursors. Moreover, LPS stimulation resulted in the increased IRF7 and E2-2 levels, suggesting that the pDC-Mϕ precursors matured into pDC-Mϕs. These matured pDC-Mϕs augmented NK cell-mediated cytotoxicity though they did not produce IFN-α upon TLR7 or TLR9 stimulation. The present results suggest that Gal-9 induces Mϕs to differentiate to pDC-Mϕs, and that this switch in differentiation favors the activation of NK cells that are able to prolong the survival of tumor-bearing mice.

Galectin-9 accelerates transforming growth factor beta3-induced differentiation of human mesenchymal stem cells to chondrocytes.

Galectin-9 (Gal-9), a beta-galactoside binding lectin, plays a crucial role in innate and adaptive immunity. In the rat collagen-induced arthritis model, administration of Gal-9 induced repair of existing cartilage injury even when joints were already swollen with cartilage destruction. We thus attempted to explore the role of Gal-9 in chondrocyte differentiation utilizing human mesenchymal stem cell (MSC) pellet cultures. During chondrogenesis induced by transforming growth factor beta3 (TGFbeta3), MSCs strongly expressed endogenous Gal-9. Expression of Gal-9 peaked on day 14 and the neutralization of endogenous Gal-9 resulted in the reduced chondrogenesis, indicating possible involvement of Gal-9 in TGFbeta-mediated chondrogenesis. In pellets, addition of Gal-9 significantly enhanced TGFbeta3-induced chondrogenesis, as evidenced by increasing proteoglycan content, but not cell proliferation. In the absence of Gal-9, collagen expression by MSCs switched from type I to type II on 28 days after stimulation with TGFbeta3. When MSCs were co-stimulated with Gal-9, the class switch occurred on day 21. In addition, Gal-9 synergistically enhanced TGFbeta3-induced phosphorylation of Smad2, though Gal-9 did not itself induce detectable Smad2 phosphorylation. These results suggest that Gal-9 has a beneficial effect on cartilage repair in injured joints by induction of differentiation of MSCs into chondrocytes.

Galectin-9 expression links to malignant potential of cervical squamous cell carcinoma.

PURPOSE: Galectin-9 (Gal-9) induces adhesion and aggregation of certain cell types and can be a prognostic factor in the patients with melanoma and breast cancer. We assessed the experiments to resolve whether Gal-9 expression in cervical neoplasm links to malignant potential of cervical squamous cell carcinoma (SCC) cells. METHODS: Gal-9 expression was examined with immunohistochemical techniques in 23 normal cervical squamous epithelia, 17 cervical intraepithelial neoplasia (CIN), and 38 cervical SCC compared to E-cadherin. CIN was divided into low-grade and high-grade squamous intraepithelial lesions (8 LSIL and 9 HSIL), and SCC was into well-, moderately and poorly differentiated SCC (6 WSCC, 20 MSCC and 12 PSCC). RESULTS: Gal-9 and E-cadherin were evidently detected in normal epithelium and endocervical glands, but those in CIN and SCC were significantly faint. Moreover, both the Gal-9 and E-cadherin expressions in HSIL were significant lower than those in LSIL, suggesting their association with malignant transformation. Unexpectedly, Gal-9 and E-cadherin in WSCC were significantly high compared to those in HSIL. Furthermore, those in SCC were inversely correlated with the grade of differentiation (WSCC >> MSCC >> PSCC), implying the possible involvement of Gal-9 and E-cadherin in the differentiation of SCC. In contrast, they were not different among the FIGO stage. Gal-9 expression was well correlated with E-cadherin expression in CIN and SCC but not in normal cervical epithelia. CONCLUSION: The present results suggest that decreased Gal-9 expression is inversely associated with malignant potential or differentiation of cervical CIN and SCC as a differentiation biomarker.

Involvement of galectin-9 in guinea pig allergic airway inflammation.

BACKGROUND: There is little information about the involvement of galectin-9 (Gal-9) in allergic inflammation. Thus, we investigated the role of Gal-9 in asthma model guinea pigs. METHODS: Airway resistance (R(aw)) was measured using a double-flow plethysmograph system. Gal-9 expression in the lung was assessed by Western blot and immunohistochemistry. Eosinophil chemotactic activity was evaluated in a chamber containing a polyvinylpyrolidone-free membrane. Cell apoptosis was analyzed on a flowcytometry with propidium iodide. RESULTS: In cloning guinea pig Gal-9 we identified three isoforms that differ only in the length of their linker peptides, just as with human Gal-9. Guinea pig Gal-9 was found to be a chemoattractant for eosinophils and to promote induction of apoptosis in sensitized but not non-sensitized T lymphocytes. In allergic airway hypersensitivity model, a low level of Gal-9 expression was observed in the nonsensitized/nonchallenged group, but upregulation was detected at 7 h after challenge and sustained up to 24 h. Such upregulation correlated with elevation of eosinophil peroxidase activity but not with increased R(aw). CONCLUSIONS: The present results provide evidence that Gal-9 is not involved in airway hypersensitivity, but is partly involved in prolonged eosinophil accumulation in the lung.

Galectin-9 inhibits CD44-hyaluronan interaction and suppresses a murine model of allergic asthma.

RATIONALE: Galectin-9 (Gal-9) belongs to the galectin family, which exhibits affinity for beta-galactosides. Gal-9 has a variety of biological activities; however, its role in allergic inflammation is unknown. OBJECTIVES: We evaluated the effect of a stable form of the human protein on allergic airway inflammation in a mite allergen-induced asthma model. METHODS: Human stable Gal-9 was given by intravenous injection to mice during antigen challenge. The effect of Gal-9 on airway inflammation and airway hyperresponsiveness (AHR) was then evaluated. MEASUREMENTS AND MAIN RESULTS: Gal-9 reduced AHR as well as Th2-associated airway inflammation. Furthermore, administration of Gal-9 as well as anti-CD44 monoclonal antibody inhibited the infiltration of peripheral blood Th2 cells into the airway. Interestingly, Gal-9 directly bound the CD44 adhesion molecule and inhibited interactions with hyaluronan (HA). Consistent with the concept that CD44-HA interactions mediate the migration of T cells into the lung, Gal-9 blocked CD44-dependent adhesion of BW5147 mouse T cells to HA. CONCLUSIONS: We conclude that Gal-9 inhibits allergic inflammation of the airway and AHR by modulating CD44-dependent leukocyte recognition of the extracellular matrix.

Carbohydrate-recognition domains of galectin-9 are involved in intermolecular interaction with galectin-9 itself and other members of the galectin family.

Galectin-9 (Gal-9) is a tandem-repeat-type member of the galectin family associated with diverse biological processes, such as apoptosis, cell aggregation, and eosinophil chemoattraction. Although the detailed sugar-binding specificity of Gal-9 has been elucidated, molecular mechanisms that underlie these functions remain to be investigated. During the course of our binding study by affinity chromatography and surface plasmon resonance (SPR) analysis, we found that human Gal-9 interacts with immobilized Gal-9 in the protein-protein interaction mode. Interestingly, this intermolecular interaction strongly depended on the activity of the carbohydrate recognition domain (CRD), because the addition of potent saccharide inhibitors abolished the binding. The presence of multimers was also confirmed by Ferguson plot analysis of result of polyacrylamide gel electrophoresis and matrix-assisted laser-desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). Moreover, this intermolecular interaction was observed between Gal-9 and other galectin members, such as Gal-3 and Gal-8, but not Gal-1. Because such properties have not been reported yet, they may explain an unidentified mechanism underlying the diverse functions of Gal-9.