SALVATORE V. PIZZO, M.D., PH.D.
        

Research Summary

   The laboratory is focused in two areas, fibrinolysis and proteinase regulation.  Studies in fibrinolysis center on the role of the fibrinolytic system in tumor progression and metastasis.  We have purified and characterized the angiostatin receptor on the surface of endothelial cells.  Using affinity chromatography and mass spectral analysis we identified cell-surface associated ATP synthase as the receptor (Moser et al., Proc. Natl. Acad. Sci. USA 96: 2811-2816, 1999; 98: 6656-6661, 2001).  We have produced antibodies against the subunits of ATP-synthase including the catalytic b -chain.  A monoclonal antibody against this subunit mimics the activity of angiostatin but is more potent.  Employing purified ATP synthase we have demonstrated that this antibody and angiostatin demonstrate comparable activity in a purified system.  In parallel experiments, we have demonstrated that ATP synthase on the endothelial surface produces ATP and this activity is blocked by both angiostatin and the anti-b -chain monoclonal antibody.  Taken together these studies suggest that endothelial cell surface-associated ATP synthase is a target for the action of angiostatin.  Multiple strategies are being pursued in order to develop potential therapeutic agents. 

Studies of the proteinase inhibitor a2-macroglobulin (a2M) from this laboratory have shown that a2M is a novel targeting vehicle and adjuvant for subunit vaccines.  We have previously demonstrated that during proteolytic activation of a2M, the inhibitor's thiolester bonds incorporate antigens (Chu and Pizzo, J. Immunol. 150: 48-58, 1993).  These antigens are effectively presented to T-cells; moreover, in vivo rabbit studies demonstrate that a2M-incorporated antigens induce antibody production move effectively than complete Freund's adjuvant (Chu et al., J. Immunol. 152: 1538-1545, 1994).  More recently, we have demonstrated a novel chemical means for activating the a2M thiolesters which promotes extremely efficient antigen binding (Gron and Pizzo, Biochemistry 37: 6009-6014, 1998).  Using this technique, studies are underway to develop improved vaccines against a number of agents including HIV and hepatitis B requiring only a single dose of vaccine and at a lower dose of antigen.  Recent work is directed towards biological agents of mass destruction such as anthrax.   

Publications:

Moser, T.L., Stack, M.S., Asplin, I., Enghild, J.J., Hojrup, P., Everitt, L., Hubchak, S., Schnaper, H.W., and Pizzo, S.V.:  Angiostatin Binds ATP Synthase on the Surface of Human Endothelial Cells.    Proc. Natl. Acad. Sci. USA, 96:  2811-2816, 1999.

Moser, T.L., Kenan, D.J., Ashley, T.A., Roy, J.A., Goodman, M.D., Misra, U.K., Cheek, D.J. and Pizzo, S.V.:  Endothelial Cell-Surface F1-Fo ATP Synthase is Active in ATP Synthesis and is Inhibited by Angiostatin.   Proc. Natl. Acad. Sci, USA, 98:6656-6661, 2001.

Adlakha, C.L., Hart, J.P., and Pizzo, S.V.:  Kinetics of Nonproteolytic Incorporation of a Protein Ligand into Thermally-Activated a₂-Macroglobulin: Evidence for a Novel Nascent State.  J. Biol. Chem., 276: 41547-41552, 2001.

Misra, U.K. and Pizzo, S.V.:  Regulation of Cytosolic Phospholipase A₂ Activity in Macrophages Stimulated with Receptor-Recognized Forms of a₂-Macroglobulin:  Role in Mitogenesis and Cell Proliferation.  J. Biol. Chem.,   277: 4069-4078, 2002.

Cianciolo, G., Enghild, J. and Pizzo, S.V.:  Covalent complexes of Ag and a2M:  Evidence for Dramatically-Increased Immunogenicity.  Vaccine, 20: 534-562, 2002. 

Liao, H.X., Cianciolo, G.J., Staats, H.F., Scearce, R.M., Lapple, D.M., Stauffer, S., Thomasch, J.R., Pizzo, S.V., Montefiori, D.C., Hagen, M., Eldridge, J., and Haynes, B.F.:  Combination of Monophosphoryl Lipid A and GM-CSF Adjuvant with an HIV Envelope Immunogen Coupled to a₂-Macroglobulin Dramatically Increases HIV Envelope Subunit Immunogenicity.  Vaccine,  20: 2396-2403, 2002.

Berwin, B., Hart, J., Pizzo, S., and Nicchitta, C.V.:  CD91-Independent Cross-Presentation of GRP94(gp96)-Associated Peptides.  J. Immunol., 168, 4282-4286, 2002 (Cutting Edge Report).

Misra, U.K., Akabani, G., and Pizzo, S.V.:  The Role of cAMP-Dependent Signaling in a ₂M*-Induced Cellular Proliferation.  J. Biol. Chem., 277: 36509-36520,  2002.

Misra, U.K., Gonzalez-Gronow, M., Gawdi, G., Hart, J.P., Johnson, C.E., and Pizzo, S.V.:  The Role of Grp 78 in a ₂-Macroglobulin-Induced Signal Transduction:  Evidence from RNA Interference that the Low Density Lipoprotein-Receptor Related Protein is Associated with, but Not Necessary for, Grp 78-Mediated Signal Transduction.  J. Biol. Chem., 277: 42082-42087, 2002.