Galectin-3 plays a modulatory role in the life span and activation of murine neutrophils during early Toxoplasma gondii infection Celene M.O.S. Alves a , Deise A.O. Silva a , Ana Elisa C.S. Azzolini b , Cleni M. Marzocchi-Machado c , Julianne V. Carvalho a , Ana Cl  audia A.M. Pajuaba a , Yara Maria Lucisano-Valim b , Roger Chammas d , Fu-Tong Liu e , Maria C. Roque-Barreira f , Jos  e R. Mineo a,Ã a Laboratory of Immunoparasitology, Institute of Biomedical Sciences, Universidade Federal de Uberlˆ andia, Uberlˆ andia, Brazil b Laboratory of Immunochemistry, Department of Physics and Chemistry, Faculdade de Ciˆ encias Farmacˆ euticas de Ribeir ~ ao Preto, Universidade de S ~ ao Paulo, Ribeir ~ ao Preto, Brazil c Department of Clinical, Toxicological and Bromatological Analysis, Faculdade de Ciˆ encias Farmacˆ euticas de Ribeir ~ ao Preto, Universidade de S ~ ao Paulo, Ribeir ~ ao Preto, Brazil d Laboratory of Experimental Oncology, Faculdade de Medicina, Universidade de S ~ ao Paulo, S ~ ao Paulo, Brazil e Department of Dermatology, School of Medicine, University of California-Davis, Sacramento, USA f Laboratory of Glycobiology, Departamento de Biologia Celular e Molecular e Bioagentes Patogˆ enicos, Faculdade de Medicina de Ribeir ~ ao Preto, Universidade de S ~ ao Paulo, Ribeir ~ ao Preto, Brazil article info Article history: Received 3 July 2009 Received in revised form 3 August 2009 Accepted 6 August 2009 Keywords: Apoptosis Cell viability Galectin-3 Neutrophils Reactive oxygen species Toxoplasma gondii abstract Galectins are b-galactoside-binding lectins involved in several biological processes and galectin-3 (Gal-3) is related to modulation of immune and inflammatory responses. This study aimed to evaluate the role of Gal-3 in the life span and biological functions of murine neutrophils during in vitro infection by virulent Toxoplasma gondii RH strain. Inflammatory peritoneal neutrophils (Nf) from C57BL/6 wild- type (WT) and Gal-3 knockout (KO) mice were cultured in the presence or absence of parasites and analyzed for phosphatidylserine (PS) exposure and cell death using Annexin-V and propidium iodide staining, and cell viability by MTT assay. Cell toxicities determined by lactate dehydrogenase (LDH), degranulation by lysozyme release, and cytokine production were measured in Nf culture super- natants. Phorbol myristate acetate (PMA)- or zymosan-dependent reactive oxygen species (ROS) were measured in Nf cultures. Our results demonstrated that Gal-3 is involved in the increase of the viable Nf number and the decrease of PS exposure and cell death following T. gondii infection. We also observed that Gal-3 downmodulates T. gondii-induced Nf toxicity as well as Nf degranulation regardless of infection. Furthermore, Gal-3 expression by Nf was associated with increased levels of IL-10 in the beginning and decreased levels of TNF-a later on, regardless of parasite infection, as well as with decreased levels of IL-6 and increased IL-12 levels, following early parasite infection. Our results also showed that Gal-3 suppresses PMA- but not zymosan-induced ROS generation in Nf following T. gondii infection. In conclusion, Gal-3 plays an important modulatory role by interfering in Nf life span and activation during early T. gondii infection. & 2009 Elsevier GmbH. All rights reserved. Introduction Galectins are a family of b-galactoside-binding animal lectins that are involved in a large number of biological processes, including regulation of cell growth and apoptosis, neoplastic transformation, and inflammatory responses (Cummings and Liu 2009; Liu and Hsu 2007). Galectin-3 (Gal-3) is one of the best characterized members of this family and is widely distributed in tissues and various epithelial, dendritic, and inflammatory cells (Liu and Hsu 2007). Gal-3 expression has been correlated with cell proliferation and differentiation, apoptosis, cell adhesion, activation of various cell types (Stowell et al. 2008; Liu and Hsu 2007), and also considered an important factor in the interaction of host cells with microorganisms (Vasta 2009), suggesting a key role for this molecule in the modulation of immune reactions and inflammatory responses. Toxoplasma gondii is an obligate intracellular protozoan parasite that causes congenital infections in newborns and opportunistic infections in immunocompromised patients. This parasite is able to induce a potent innate immune response involving dendritic cells, macrophages, neutrophils, natural killer (NK) cells, Toll-like receptors (TLRs), cytokine production, and activation of effective antimicrobial mechanisms (Miller et al. 2009). Neutrophils destroy invading microorganisms through respira- tory burst, including the generation of reactive oxygen species ARTICLE IN PRESS Contents lists available at ScienceDirect journal homepage: www.elsevier.de/imbio Immunobiology 0171-2985/$ - see front matter & 2009 Elsevier GmbH. All rights reserved. doi:10.1016/j.imbio.2009.08.001 Ã Corresponding author. Tel.: +55 34 3218 2058; fax: +55 34 3218 2333. E-mail address: jrmineo@ufu.br (J.R. Mineo). Immunobiology 215 (2010) 475–485