Selective enhancement of thrombopoietic activity of PEGylated interleukin 6 by a simple procedure using a reversible amino‐protective reagent

• Published in: British journal of haematology 2001-01, Vol.112 (1), p.181-188
• Main Authors: Tsunoda, S., Ishikawa, T., Watanabe, M., Kamada, H., Yamamoto, Y., Tsutsumi, Y., Hirano, T., Mayumi, T.
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Biological Availability; Blood. Blood coagulation. Reticuloendothelial system; dimethylmaleic anhydride; Dose-Response Relationship, Drug; Drug Delivery Systems - methods; Drug Synergism; fibrinogen; Fibrinogen - analysis; Hematinics - administration & dosage; Hematinics - pharmacokinetics; Hematology; interleukin 6; Interleukin-6 - administration & dosage; Interleukin-6 - pharmacokinetics; Male; Maleic Anhydrides; Medical sciences; Mice; Mice, Inbred C3H; Pharmacology. Drug treatments; platelet; Platelet Count; polyethylene glycol; Polyethylene Glycols; Recombinant Proteins - administration & dosage; Surface-Active Agents
• ISSN: 0007-1048; 1365-2141
• DOI: 10.1046/j.1365-2141.2001.02508.x

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.