Reciprocal regulation of galectin-1 and galectin-3, glycan-binding proteins with proapoptotic activity, in human and murine T helper cell subsets.

L CAMPAGNA, MA TOSCANO, JM ILARREGUI, GA BIANCO, DO CROCI, M SALATINO, JP FEDEDA, C MALDONADO, AR KORNBLIHTT, GA RABINOVICH.

Rio de Janeiro, Brasil

Congreso; 13th International Congress of Immunology; 2007

Recently we demonstrated that T-helper (Th)-1 and Th2 cells have differential susceptibility to apoptosis induced by galectin (Gal)-1 and Gal-3, two glycan-binding proteins with immunoregulatory activity. Here we investigate, using in vitro and in vivo strategies, the impact of Th1 and Th2 polarization in the regulation of Gal-1 and Gal-3 expression and subcellular localization and the signaling pathways implicated in this process. Our results show that human Th1 cells express (fold increase:1.5) and secrete (f.i.:2.6) higher levels of Gal-1 than Th2 cells, similar results were obtained with murine cells. Conversely, Gal-3 expression but not secretion is up-regulated along Th2 polarization in human cells (f.i.:2). However, the opposite effect is observed in murine cells, where Th1-polarized lymphocytes express and secrete the highest levels of Gal-3. These results were confirmed by inducing antigen-specific Th1 and Th2 responses in vivo using bacterial (Proprionibacterium acnes) and parasite (Schistosoma egg) antigens, since higher levels of Gal-1 and Gal-3 were reached using Th1-promoting stimuli (p<0.05 and p<0.005 respectively). Using specific inhibitors of a variety of signaling pathways, we found that NF-��B is a critical regulator of the expression of both galectin genes. Furthermore, we identified a binding site for this transcription factor in the gal-1 promoter employing chromatin immunoprecipitation assays and observed a marked Gal-1 increase in HEK293 cells overexpressing p65/RelA (f.i.:6.2). Taken together, our results demonstrate the existence of a fine-tuned regulation of Gal-1 and Gal-3 in Th1 and Th2 cells, with critical implications in the survival and homeostasis of effector T cells.in vitro and in vivo strategies, the impact of Th1 and Th2 polarization in the regulation of Gal-1 and Gal-3 expression and subcellular localization and the signaling pathways implicated in this process. Our results show that human Th1 cells express (fold increase:1.5) and secrete (f.i.:2.6) higher levels of Gal-1 than Th2 cells, similar results were obtained with murine cells. Conversely, Gal-3 expression but not secretion is up-regulated along Th2 polarization in human cells (f.i.:2). However, the opposite effect is observed in murine cells, where Th1-polarized lymphocytes express and secrete the highest levels of Gal-3. These results were confirmed by inducing antigen-specific Th1 and Th2 responses in vivo using bacterial (Proprionibacterium acnes) and parasite (Schistosoma egg) antigens, since higher levels of Gal-1 and Gal-3 were reached using Th1-promoting stimuli (p<0.05 and p<0.005 respectively). Using specific inhibitors of a variety of signaling pathways, we found that NF-��B is a critical regulator of the expression of both galectin genes. Furthermore, we identified a binding site for this transcription factor in the gal-1 promoter employing chromatin immunoprecipitation assays and observed a marked Gal-1 increase in HEK293 cells overexpressing p65/RelA (f.i.:6.2). Taken together, our results demonstrate the existence of a fine-tuned regulation of Gal-1 and Gal-3 in Th1 and Th2 cells, with critical implications in the survival and homeostasis of effector T cells.in vivo using bacterial (Proprionibacterium acnes) and parasite (Schistosoma egg) antigens, since higher levels of Gal-1 and Gal-3 were reached using Th1-promoting stimuli (p<0.05 and p<0.005 respectively). Using specific inhibitors of a variety of signaling pathways, we found that NF-��B is a critical regulator of the expression of both galectin genes. Furthermore, we identified a binding site for this transcription factor in the gal-1 promoter employing chromatin immunoprecipitation assays and observed a marked Gal-1 increase in HEK293 cells overexpressing p65/RelA (f.i.:6.2). Taken together, our results demonstrate the existence of a fine-tuned regulation of Gal-1 and Gal-3 in Th1 and Th2 cells, with critical implications in the survival and homeostasis of effector T cells.��B is a critical regulator of the expression of both galectin genes. Furthermore, we identified a binding site for this transcription factor in the gal-1 promoter employing chromatin immunoprecipitation assays and observed a marked Gal-1 increase in HEK293 cells overexpressing p65/RelA (f.i.:6.2). Taken together, our results demonstrate the existence of a fine-tuned regulation of Gal-1 and Gal-3 in Th1 and Th2 cells, with critical implications in the survival and homeostasis of effector T cells.gal-1 promoter employing chromatin immunoprecipitation assays and observed a marked Gal-1 increase in HEK293 cells overexpressing p65/RelA (f.i.:6.2). Taken together, our results demonstrate the existence of a fine-tuned regulation of Gal-1 and Gal-3 in Th1 and Th2 cells, with critical implications in the survival and homeostasis of effector T cells.