RECIPROCAL REGULATION OF GALECTIN-1 AND GALECTIN-3, GLYCAN-BINDING PROTEINS WITH PRO-APOPTOTIC ACTIVITY, IN HUMAN AND MURINE T HELPER CELL SUBSETS

L. CAMPAGNA; M. TOSCANO; J. ILARREGUI; G. BIANCO; D. CROCI; M. SALATINO; J. FEDEDA; C. MALDONADO; A.R. KORNBLIHTT; G. RABINOVICH

RIO DE JANEIRO

Congreso; 13TH INTERNATIONAL CONGRESS OF IMMUNOLOGY; 2007

ICI 2007

Reciprocal regulation of galectin-1 and galectin-3, glycan-binding proteins with pro-apoptotic activity, in human and murine T helper cell subsets   L. Campagna1, M.A. Toscano1, J.M. Ilarregui1, G.A. Bianco1, D.O. Croci1, M. Salatino1, J.P. Fededa2, C. Maldonado3, A.R. Kornblihtt2, G.A. Rabinovich1   1Division of immunogenetics, Hospital de Clínicas “José de San Martín”, Faculty of Medicine, University of Buenos Aires, Buenos Aires, Argentina.   2Laboratory of Phisiology and Molecular Biology, Faculty of Exact and Natural Sciences, University of Buenos Aires, Buenos Aires, Argentina.   3Center of Electron Microscopy, School of Medical Sciences, National University of Córdoba, Córdoba, Argentina.     We have recently demonstrated that T helper 1 (Th1) and T helper 2 (Th2) cells have a differential susceptibility to galectin-1 (Gal-1) and galectin-3 (Gal-3), two members of the galectin family with affinity for b-galactosides, induced cell death. The goal of this study was to evaluate the differential expression and ultrastructural localization of Gal-1 and Gal-3 in Th1 and Th2 polarized cells and to investigate the signaling pathways involved in this process. Human and murine mononuclear cells were polarized in vitro and the kinetics of expression and secretion of Gal-1 and Gal-3 during this period was established by Western Blot. The ultrastructural localization was studied using flow citometry, confocal and inmunoelectron microscopy. Human Th1 cells expressed and secreted higher levels of Gal-1 than Th2 cells. Similar results were obtained with polarized murine cells. Gal-3 was upregulated in human Th2 cells, and no secretion of this protein was detected. However, the opposite was observed with murine cells, where Th1-polarized lymphocytes expressed and secreted higher levels of Gal-3 than Th2 cells. These results were confirmed inducing Th1 and Th2 immune responses in vivo with PAA (P. acnes antigens) and SEA (S. mansoni egg antigen) respectively. Finally, the signal transduction events involved in this process were studied using selective inhibitors for ERK1/2, PI-3K/AKT, p38, calcineurin/NFAT and NF-kB. We observed that NF-kB was implicated in the regulation of both galectin genes. Furthermore, a binding site for this transcription factor was identified in the promoter of Lgals-1 employing a ChIP assay and a marked increase in the levels of Gal-1 was observed in HEK 293 cells overexpressing p65/RelA. Taken together, our results demonstrate the existence of a fine-tuned regulation for Gal-1 and Gal-3 in Th1 and Th2 cells, having profound implications in the survival and homeostasis of these populations.