Generation of a Specific Immunological Response to FGF‐2 Does Not Affect Wound Healing or Reproduction

Abstract

Angiogenesis, the process of new capillary formation from pre‐existing vessels, has been established as an important mechanism involved in pathologic processes, such as cancer, as well as in normal physiology (Ribatti, D.; Vacca, A.; Roncali, L.; Dammacco, F. Angiogenesis under normal and pathological conditions. Haematologica 1991, 76 (4), 311–320). Basic fibroblast growth factor (FGF‐2) is a critical mediator of angiogenesis that is important for normal reproduction and wound healing. FGF‐2 mediates its pro‐angiogenic effects by binding to heparin sulfate proteoglycan in addition to a tyrosine kinase receptor (Baird, A.; Schubert, D.; Ling, N.; Guillemin, R. Receptor and heparin‐binding domain of basic fibroblast growth factor. Proc. Natl. Acad. Sci. U. S. A. 1998, 5 (7), 2324–2328; Richard, C.; Roghani, M.; Moscatelli, D. Fibroblast growth factor (FGF)‐2 mediates cell attachment through interactions with two FGF receptor‐1 isoforms and extracellular matrix or cell‐associated heparin sulfate proteoglycans. Biochem. Biophys. Res. Commun. 2000, 276 (2), 399–405; Casu, B.; Guerrini, M.; Naggi, A.; Perez, M.; Torri, G.; Ribatti, D.; Carminati, P.; Giannini, G.; Penco, S.; Pisano, C.; Belleri, M.; Rusnati, M.; Presta, M. Short heparin sequences spaced by glycol‐split urinate residues are antagonists of fibroblast growth factor 2 and angiogenesis inhibitors. Biochemistry 2002, 41 (33), 10519–10528; Murphy, P.V.; Pitt, N.; O'Brien, A.; Enright, P.M.; Dunne, A.; Wilson, S.J.; Duane, R.M.; O'Boyle, K.M. Identification of novel inhibitors of fibroblast growth factor (FGF‐2) binding to heparin and endothelial cell survival from a structurally diverse carbohybrid library. Bioorg. Med. Chem. Lett. 2002, 12 (22), 3287–3290). We developed a liposomal‐based peptide vaccine, L(HBD) that targets the heparin binding domain of the FGF‐2 molecule. This vaccine, when inoculated into mice, inhibits angiogenesis in response to FGF‐2 in a hepatic sponge model as well as tumor progression in two models of pulmonary metastatic disease. In the present studies, we further characterize the immunological and physiological responses to this vaccine. Vaccinated animals generated a specific anti‐FGF‐2 antibody (titer of 1:5000) that was able to inhibit FGF‐2 binding to heparin sulfate in a dose dependent fashion. Cell mediated immunity was evidenced by a delayed type hypersensitivity response following challenge with the heparin binding domain peptide. Despite an immune response toward FGF‐2, vaccination with L(HBD) did not result in alterations in mean time to wound healing when compared to unvaccinated animals or those treated with a liposome control. In reproductive studies, vaccinated females were not impaired in their ability to: 1) become pregnant, 2) support the growth and development of their embryos, and 3) deliver viable offspring. Furthermore, when assessed histologically, these offspring did not demonstrate any alterations in organogenesis when compared to pups born to untreated or liposome control treated females. Thus, while vaccination against FGF‐2 induces a specific FGF‐2 antibody response, and inhibits angiogenesis and tumor development in a pathological setting, it does not adversely alter normal physiological events dependent on FGF‐2.

Key Words :

• Angiogenesis
• Immunological response
• FGF‐2
• Wound healing
• Reproduction