Liver targeting of interferon-beta with a liver-affinity polysaccharide based on metal coordination in mice.

Frequent and high-dose i.v. injections of interferon-beta (IFN-beta) have been used clinically to treat patients with viral hepatitis despite various side effects. Because side effects are caused by the systemic effects of IFN-beta, the purpose of this study was to target the drug specifically to the liver, thus reducing the adverse events. A chelating residue, diethylenetriaminepentaacetic acid (DTPA), was introduced to pullulan, a water-soluble polysaccharide with a high affinity for the liver. Murine IFN-beta could be coordinately conjugated with the DTPA-pullulan by simple mixing in an aqueous solution containing zinc ion (Zn2+). Intravenous injection of the IFN-beta-DTPA-pullulan conjugate with Zn2+ coordination enhanced liver induction of an antiviral enzyme, 2',5'-oligoadenylate synthetase (2-5AS), to a greater extent than that by free IFN-beta, although the 2-5AS levels in the liver depended on the mixing ratio of the IFN-beta/DTPA residue of DTPA-pullulan/Zn2+. In addition, the duration of the liver 2-5AS induction by the IFN-beta-DTPA-pullulan conjugate with Zn2+ coordination was longer than that by free IFN-beta. The liver targeting of IFN-beta by DTPA-pullulan with Zn2+ coordination may be a promising IFN therapy.