title: Involvement of sulfates from cruzipain, a major antigen of Trypanosoma cruzi, in the interaction with immunomodulatory molecule Siglec-E.
abstract: In order to investigate the involvement of sulfated groups in the Trypanosoma cruzi host-parasite relationship, we studied the interaction between the major cysteine proteinase of T. cruzi, cruzipain (Cz), a sulfate-containing sialylated molecule and the sialic acid-binding immunoglobulin like lectin-E (Siglec-E). To this aim, ELISA, indirect immunofluorescence assays and flow cytometry, using mouse Siglec-E-Fc fusion molecules and glycoproteins of parasites, were performed. Competition assays verified that the lectins, Maackia amurensis II (Mal II) and Siglec-E-Fc, compete for the same binding sites. Taking into account that Mal II binding remains unaltered by sulfation, we established this lectin as sialylation degree control. Proteins of an enriched microsomal fraction showed the highest binding to Siglec-E as compared with those from the other parasite subcellular fractions. ELISA assays and the affinity purification of Cz by a Siglec-E column confirmed the interaction between both molecules. The significant decrease in binding of Siglec-E-Fc to Cz and to its C-terminal domain (C-T) after desulfation of these molecules suggests that sulfates contribute to the interaction between Siglec-E-Fc and these glycoproteins. Competitive ELISA assays confirmed the involvement of sulfated epitopes in the affinity between Siglec-E and Cz, probably modified by natural protein environment. Interestingly, data from flow cytometry of untreated and chlorate-treated parasites suggested that sulfates are not primary receptors, but enhance the binding of Siglec-E to trypomastigotic forms. Altogether, our findings support the notion that sulfate-containing sialylated glycoproteins interact with Siglec-E, an ortholog protein of human Siglec-9, and might modulate the immune response of the host, favoring parasitemia and persistence of the parasite.
authors.affiliation: Área de Bioquímica de Proteínas y Glicobiología de Parásitos, Departamento de Investigación, Instituto Nacional de Parasitología "Dr. Mario Fatala Chaben", ANLIS-Malbrán, Ministerio de Salud de la Nación, Av. Paseo Colón 568 (1063), Buenos Aires, Argentina.
authors.forename: Maximiliano R
authors.initials: MR
authors.lastname: Ferrero
authors.affiliation: Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
authors.forename: Anja M
authors.initials: AM
authors.lastname: Heins
authors.affiliation: Área de Bioquímica de Proteínas y Glicobiología de Parásitos, Departamento de Investigación, Instituto Nacional de Parasitología "Dr. Mario Fatala Chaben", ANLIS-Malbrán, Ministerio de Salud de la Nación, Av. Paseo Colón 568 (1063), Buenos Aires, Argentina.
authors.forename: Luciana L
authors.initials: LL
authors.lastname: Soprano
authors.affiliation: Área de Bioquímica de Proteínas y Glicobiología de Parásitos, Departamento de Investigación, Instituto Nacional de Parasitología "Dr. Mario Fatala Chaben", ANLIS-Malbrán, Ministerio de Salud de la Nación, Av. Paseo Colón 568 (1063), Buenos Aires, Argentina.
authors.forename: Diana M
authors.initials: DM
authors.lastname: Acosta
authors.affiliation: Área de Bioquímica de Proteínas y Glicobiología de Parásitos, Departamento de Investigación, Instituto Nacional de Parasitología "Dr. Mario Fatala Chaben", ANLIS-Malbrán, Ministerio de Salud de la Nación, Av. Paseo Colón 568 (1063), Buenos Aires, Argentina.
authors.forename: Mónica I
authors.initials: MI
authors.lastname: Esteva
authors.affiliation: Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Jacobs
authors.affiliation: Área de Bioquímica de Proteínas y Glicobiología de Parásitos, Departamento de Investigación, Instituto Nacional de Parasitología "Dr. Mario Fatala Chaben", ANLIS-Malbrán, Ministerio de Salud de la Nación, Av. Paseo Colón 568 (1063), Buenos Aires, Argentina. vduschak@conicet.gov.ar.
authors.forename: Vilma G
authors.initials: VG
authors.lastname: Duschak
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000378:metabolism*; D000944:Antigens, Differentiation, B-Lymphocyte / Q000378:metabolism*; D000953:Antigens, Protozoan / Q000378:metabolism*; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D019084:Fluorescent Antibody Technique, Indirect; D054884:Host-Pathogen Interactions; D007155:Immunologic Factors / Q000378:metabolism*; D051379:Mice; D011485:Protein Binding; D015800:Protozoan Proteins; D011817:Rabbits; D013431:Sulfates / Q000378:metabolism*; D014349:Trypanosoma cruzi / Q000276:immunology*
chemical_list: D015703:Antigens, CD; D000944:Antigens, Differentiation, B-Lymphocyte; D000953:Antigens, Protozoan; D007155:Immunologic Factors; D015800:Protozoan Proteins; C422908:Siglece protein, mouse; D013431:Sulfates; D003546:Cysteine Endopeptidases; C063214:cruzipain
keywords: Cruzipain; Immunomodulation; Sialic acid; Siglecs; Sulfates; Trypanosoma cruzi