Anti-Galectin-2 Antibody Treatment Reduces Atherosclerotic Plaque Size and Alters Macrophage Polarity.

BACKGROUND: Galectins have numerous cellular functions in immunity and inflammation. Short-term galectin-2 (Gal-2) blockade in ischemia-induced arteriogenesis shifts macrophages to an anti-inflammatory phenotype and improves perfusion. Gal-2 may also affect other macrophage-related cardiovascular diseases. OBJECTIVES: This study aims to elucidate the effects of Gal-2 inhibition in atherosclerosis. METHODS: ApoE -/- mice were given a high-cholesterol diet (HCD) for 12 weeks. After 6 weeks of HCD, intermediate atherosclerotic plaques were present. To study the effects of anti-Gal-2 nanobody treatment on the progression of existing atherosclerosis, treatment with two llama-derived anti-Gal-2 nanobodies (clones 2H8 and 2C10), or vehicle was given for the remaining 6 weeks. RESULTS: Gal-2 inhibition reduced the progression of existing atherosclerosis. Atherosclerotic plaque area in the aortic root was decreased, especially so in mice treated with 2C10 nanobodies. This clone showed reduced atherosclerosis severity as reflected by a decrease in fibrous cap atheromas in addition to decreases in plaque size.The number of plaque resident macrophages was unchanged; however, there was a significant increase in the fraction of CD206+ macrophages. 2C10 treatment also increased plaque α-smooth muscle content, and Gal-2 may have a role in modulating the inflammatory status of smooth muscle cells. Remarkably, both treatments reduced serum cholesterol concentrations including reductions in very low-density lipoprotein, low-density lipoprotein, and high-density lipoprotein while triglyceride concentrations were unchanged. CONCLUSION: Prolonged and frequent treatment with anti-Gal-2 nanobodies reduced plaque size, slowed plaque progression, and modified the phenotype of plaque macrophages toward an anti-inflammatory profile. These results hold promise for future macrophage modulating therapeutic interventions that promote arteriogenesis and reduce atherosclerosis.

Galectin-2 and -4, but not galectin-1, promote intestinal epithelial wound healing in vitro through a TGF-beta-independent mechanism.

BACKGROUND: Inflammatory bowel diseases (IBDs) are characterized by various degrees of mucosal surface damage and subsequent impairment of the intestinal barrier function. Resealing of the epithelial barrier requires intestinal cell migration and proliferation. Galectins are increasingly recognized as novel regulators of inflammation. Thus, we aimed to explore the effect of galectin-2 (Gal-2) and Gal-4 on epithelial cell function and wound healing. METHODS: Binding of Gal-2 and Gal-4 was determined by flow cytometric analysis and binding sites by SDS-PAGE electrophoresis. Cell migration by Gal-1, -2, and -4 was determined by a wound-healing assay. Cell cycle analysis and detection of apoptosis were determined by flow cytometric analysis. RESULTS: Gal-2 and Gal-4 bind to epithelial cells at the E-cadherin/beta-catenin complex. Both galectins significantly enhanced intestinal epithelial cell restitution in vitro. This enhancement of epithelial cell restitution was TGF-beta-independent. In contrast, Gal-1 decreased epithelial cell migration TGF-beta dependently. By performing cell cycle analysis, we show that Gal-2 and Gal-4 increased cyclin B1 expression and consequently cell cycle progression, while Gal-1 inhibited cell cycling. Determining the influence of Gal-2 and Gal-4 on epithelial cell apoptosis, we showed no induction of apoptosis, whereas Gal-1 significantly induced apoptosis of epithelial cells caspase-independently. CONCLUSIONS: Gal-2 and Gal-4 bind to intestinal epithelial cells and promote their restitution. Thus, our study provides for the first time evidence that these galectins play a significant role in intestinal wound-healing processes and might exert beneficial effects in diseases characterized by epithelial barrier disruption like IBDs.

Galectin-2 induces apoptosis of lamina propria T lymphocytes and ameliorates acute and chronic experimental colitis in mice.

Galectins have recently emerged as central regulators of the immune system. We have previously demonstrated that carbohydrate-dependent binding of galectin-2 induces apoptosis in activated T cells. Here, we investigate the potential therapeutic effect of galectin-2 in experimental colitis. Galectin-2 expression and its binding profile were determined by immunohistochemistry. Acute and chronic colitis was induced by dextran sodium sulfate administration and in a T-cell transfer colitis model. Apoptosis was assessed by TdT-mediated dUTP-biotin nick-end labeling, and cytokine secretion was determined by cytometric bead array. We show that galectin-2 was constitutively expressed mainly in the epithelial compartment of the mouse intestine and bind to lamina propria mononuclear cells. During colitis, galectin-2 expression was reduced, but could be restored to normal levels by immunosuppressive treatment. Galectin-2 treatment induced apoptosis of mucosal T cells and thus ameliorated acute and chronic dextran-sodium-sulfate-induced colitis and in a T-helper-cell 1-driven model of antigen-specific transfer colitis. Furthermore, the pro-inflammatory cytokine release was inhibited by galectin-2 treatment. In preliminary toxicity studies, galectin-2 was well tolerated. Our study provides evidence that galectin-2 induces apoptosis in vivo and ameliorates acute and chronic murine colitis. Furthermore, galectin-2 has no significant toxicity over a broad dose range, suggesting that it may serve as a new therapeutic agent in the treatment of inflammatory bowel disease.