Development of a Nascent Galectin-1 Chimeric Molecule for Studying the Role of Leukocyte Galectin-1 Ligands and Immune Disease Modulation

Abstract

Galectin-1 (Gal-1), a β-galactoside–binding lectin, plays a profound role in modulating adaptive immune responses by altering the phenotype and fate of T cells. Experimental data showing recombinant Gal-1 (rGal-1) efficacy on T cell viability and cytokine production, nevertheless, is controversial due to the necessity of using stabilizing chemicals to help retain Gal-1 structure and function. To address this drawback, we developed a mouse Gal-1 human Ig chimera (Gal-1hFc) that did not need chemical stabilization for Gal-1 ligand recognition, apoptosis induction, and cytokine modulation in a variety of leukocyte models. At high concentrations, Gal-1hFc induced apoptosis in Gal-1 ligand⁺ Th1 and Th17 cells, leukemic cells, and granulocytes from synovial fluids of patients with rheumatoid arthritis. Importantly, at low, more physiologic concentrations, Gal-1hFc retained its homodimeric form without losing functionality. Not only did Gal-1hFc–binding trigger IL-10 and Th2 cytokine expression in activated T cells, but members of the CD28 family and several other immunomodulatory molecules were upregulated. In a mouse model of contact hypersensitivity, we found that a non-Fc receptor-binding isoform of Gal-1hFc, Gal-1hFc2, alleviated T cell-dependent inflammation by increasing IL-4⁺, IL-10⁺, TGF-β⁺, and CD25^high/FoxP3⁺ T cells, and by decreasing IFN-γ⁺ and IL-17⁺ T cells. Moreover, in human skin-resident T cell cultures, Gal-1hFc diminished IL-17⁺ T cells and increased IL-4⁺ and IL-10⁺ T cells. Gal-1hFc will not only be a useful new tool for investigating the role of Gal-1 ligands in leukocyte death and cytokine stimulation, but for studying how Gal-1–Gal-1 ligand binding shapes the intensity of immune responses.