Receptor-based antidote for diphtheria

Infect Immun. 2002 May;70(5):2344-50. doi: 10.1128/IAI.70.5.2344-2350.2002.

Abstract

Although equine diphtheria antitoxin may be an effective therapy for human diphtheria, its use often induces serum sickness. We describe here a strategy for developing an alternative treatment based on the human diphtheria toxin (DT) receptor/heparin-binding epidermal growth factor-like growth factor (HB-EGF) precursor. Recombinant mature human HB-EGF acts as a soluble receptor analog, binding radioiodinated DT and preventing its binding to the cellular DT receptor/HB-EGF precursor. However, the possibility existed that radioiodinated DT-HB-EGF complexes associate with cells due to the binding of the heparin-binding domain of recombinant HB-EGF to cell surface heparan sulfate proteoglycans. This possibility was confirmed by performing DT binding studies in the presence of heparin. A recombinant truncated HB-EGF (residues 106 to 149), which lacks most of the heparin-binding domain, showed an essentially heparin-independent binding of radioiodinated DT to cells. Furthermore, it was a more effective inhibitor of DT binding than was recombinant mature HB-EGF. Since mature HB-EGF is a known ligand for the EGF receptor and is thus highly mitogenic (tumorigenic), we then changed amino acid residues in the EGF-like domain of the recombinant truncated HB-EGF and demonstrated that this DT receptor analog (I117A/L148A) displayed a low mitogenic effect. The truncated (I117A/L148A) HB-EGF protein retained high DT binding affinity, as confirmed by using surface plasmon resonance. Our results suggest that the truncated (I117A/L148A) HB-EGF protein could be an effective, safe antidote for human diphtheria.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 3T3 Cells
  • Amino Acid Sequence
  • Animals
  • Antidotes / therapeutic use*
  • Diphtheria / drug therapy*
  • Diphtheria Toxin / metabolism
  • Epidermal Growth Factor / metabolism
  • Epidermal Growth Factor / pharmacology
  • Epidermal Growth Factor / therapeutic use*
  • Heparin / pharmacology
  • Heparin-binding EGF-like Growth Factor
  • Intercellular Signaling Peptides and Proteins
  • Mice
  • Mitogens / pharmacology
  • Molecular Sequence Data
  • Receptors, Cell Surface / metabolism*

Substances

  • Antidotes
  • Diphtheria Toxin
  • HBEGF protein, human
  • Hbegf protein, mouse
  • Heparin-binding EGF-like Growth Factor
  • Intercellular Signaling Peptides and Proteins
  • Mitogens
  • Receptors, Cell Surface
  • Epidermal Growth Factor
  • Heparin