title: Selective enhancement of thrombopoietic activity of PEGylated interleukin 6 by a simple procedure using a reversible amino-protective reagent.
abstract: We developed a novel method for the chemical modification of cytokines with synthetic polymers to increase the therapeutic efficacy of the former in vivo. A pH-reversible amino-protective reagent, dimethylmaleic anhydride (DMMAn), was used for modification of interleukin-6 (IL-6) with polyethylene glycol (PEG). The novel PEG-conjugated IL-6 (DmPEG-IL-6), which had been pretreated with DMMAn before PEGylation, showed up to a 140% increase in in vitro specific activity compared with PEG-IL-6 that had been synthesized by the previous method. Moreover, DmPEG-IL-6 caused thrombopoiesis more potently in mice than PEG-IL-6. The DmPEG-IL-6 Fr.1, having 3-4 PEG chains attached to the cytokine, showed the strongest thrombopoietic effect among the DmPEG-IL-6s with different molecular sizes that were tested. PEG-IL-6 Fr.1 had a 500-fold higher potency in stimulating thrombopoiesis than native IL-6 and DmPEG-IL-6 Fr.1 achieved a threefold higher thrombopoietic effect than PEG-IL-6 Fr.1. In addition, side-effects, such as an increase in the plasma fibrinogen level, were not observed after injection of either PEG-IL-6s or DmPEG-IL-6s. These results suggest that PEGylation with DMMAn pretreatment may become a useful means for clinical cytokine delivery.
authors.affiliation: Department of Biopharmaceutics, School of Pharmaceutical Sciences, Osaka University, Osaka, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Tsunoda
authors.forename: T
authors.initials: T
authors.lastname: Ishikawa
authors.forename: M
authors.initials: M
authors.lastname: Watanabe
authors.forename: H
authors.initials: H
authors.lastname: Kamada
authors.forename: Y
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Y
authors.initials: Y
authors.lastname: Tsutsumi
authors.forename: T
authors.initials: T
authors.lastname: Hirano
authors.forename: T
authors.initials: T
authors.lastname: Mayumi
mesh_terms: D000818:Animals; D001682:Biological Availability; D004305:Dose-Response Relationship, Drug; D016503:Drug Delivery Systems / Q000379:methods*; D004357:Drug Synergism; D005340:Fibrinogen / Q000032:analysis; D006397:Hematinics / Q000008:administration & dosage* / Q000493:pharmacokinetics; D015850:Interleukin-6 / Q000008:administration & dosage* / Q000493:pharmacokinetics; D008297:Male; D008299:Maleic Anhydrides; D051379:Mice; D008809:Mice, Inbred C3H; D010976:Platelet Count; D011092:Polyethylene Glycols; D011994:Recombinant Proteins / Q000008:administration & dosage; D013501:Surface-Active Agents
chemical_list: D006397:Hematinics; D015850:Interleukin-6; D008299:Maleic Anhydrides; D011994:Recombinant Proteins; D013501:Surface-Active Agents; D011092:Polyethylene Glycols; C007474:2,3-dimethylmaleic anhydride; D005340:Fibrinogen