title: Inhibition of Cellular Adhesion by Immunological Targeting of Osteopontin Neoepitopes Generated through Matrix Metalloproteinase and Thrombin Cleavage.
abstract: Osteopontin (OPN), a secreted protein involved in inflammatory processes and cancer, induces cell adhesion, migration, and activation of inflammatory pathways in various cell types. Cells bind OPN via integrins at a canonical RGD region in the full length form as well as to a contiguous cryptic site that some have shown is unmasked upon thrombin or matrix metalloproteinase cleavage. Thus, the adhesive capacity of osteopontin is enhanced by proteolytic cleavage that may occur in inflammatory conditions such as obesity, atherosclerosis, rheumatoid arthritis, tumor growth and metastasis. Our aim was to inhibit cellular adhesion to recombinant truncated proteins that correspond to the N-terminal cleavage products of thrombin- or matrix metalloproteinase-cleaved OPN in vitro. We specifically targeted the cryptic integrin binding site with monoclonal antibodies and antisera induced by peptide immunization of mice. HEK 293 cells adhered markedly stronger to truncated OPN proteins than to full length OPN. Without affecting cell binding to the full length form, the raised monoclonal antibodies specifically impeded cellular adhesion to the OPN fragments. Moreover, we show that the peptides used for immunization were able to induce antisera, which impeded adhesion either to all OPN forms, including the full-length form, or selectively to the corresponding truncated recombinant proteins. In conclusion, we developed immunological tools to selectively target functional properties of protease-cleaved OPN forms, which could find applications in treatment and prevention of various inflammatory diseases and cancers.
authors: Christian Doppler Laboratory for Cardio-Metabolic Immunotherapy and Clinical Division of Endocrinology and Metabolism, Department of Medicine III, Medical University of Vienna, Vienna, Austria.
authors: Alexander
authors: A
authors: Jürets
authors: AFFiRiS AG, Vienna, Austria.
authors: Marie
authors: M
authors: Le Bras
authors: AFFiRiS AG, Vienna, Austria.
authors: Günther
authors: G
authors: Staffler
authors: Christian Doppler Laboratory for Cardio-Metabolic Immunotherapy and Clinical Division of Endocrinology and Metabolism, Department of Medicine III, Medical University of Vienna, Vienna, Austria.
authors: Gesine
authors: G
authors: Stein
authors: Christian Doppler Laboratory for Cardio-Metabolic Immunotherapy and Clinical Division of Endocrinology and Metabolism, Department of Medicine III, Medical University of Vienna, Vienna, Austria.
authors: Lukas
authors: L
authors: Leitner
authors: Christian Doppler Laboratory for Cardio-Metabolic Immunotherapy and Clinical Division of Endocrinology and Metabolism, Department of Medicine III, Medical University of Vienna, Vienna, Austria.
authors: Angelika
authors: A
authors: Neuhofer
authors: Christian Doppler Laboratory for Cardio-Metabolic Immunotherapy and Clinical Division of Endocrinology and Metabolism, Department of Medicine III, Medical University of Vienna, Vienna, Austria.
authors: Matteo
authors: M
authors: Tardelli
authors: Department of Plastic and Reconstructive Surgery, Medical University of Vienna, Vienna, Austria.
authors: Edvin
authors: E
authors: Turkof
authors: Christian Doppler Laboratory for Cardio-Metabolic Immunotherapy and Clinical Division of Endocrinology and Metabolism, Department of Medicine III, Medical University of Vienna, Vienna, Austria.
authors: Maximilian
authors: M
authors: Zeyda
authors: Christian Doppler Laboratory for Cardio-Metabolic Immunotherapy and Clinical Division of Endocrinology and Metabolism, Department of Medicine III, Medical University of Vienna, Vienna, Austria.
authors: Thomas M
authors: TM
authors: Stulnig
mesh_terms: D000818:Animals; D058846:Antibodies, Monoclonal, Murine-Derived / Q000276:immunology; D002448:Cell Adhesion / Q000235:genetics / Q000276:immunology; D000939:Epitopes / Q000235:genetics / Q000276:immunology*; D018093:Gelatinases / Q000235:genetics / Q000276:immunology*; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D053495:Osteopontin / Q000235:genetics / Q000276:immunology*; D059748:Proteolysis; D013917:Thrombin / Q000235:genetics / Q000276:immunology*
chemical_list: D058846:Antibodies, Monoclonal, Murine-Derived; D000939:Epitopes; D053495:Osteopontin; D013917:Thrombin; D018093:Gelatinases