ABSTRACT
OBJECTIVES: Our aim was to investigate the effect of PEGylation on the uptake of osteoprotegerin/osteoclastogenesis inhibitory factor (OPG/OCIF) into rat liver, kidney and spleen, and human liver. METHODS: Copolymer of polyethyleneglycol allylmethylether and maleamic acid sodium salt with OCIF (poly(PEG)-OCIF) (0.5 mg/kg) was administered to rats and the concentrations of poly(PEG)-OCIF in the liver, kidney and spleen at 15 min after administration were measured by ELISA. For human liver uptake, the liver perfusion of OCIF and (3)H-labelled poly(PEG)-OCIF was conducted using fresh human liver block. KEY FINDINGS: The tissue uptake of poly(PEG)-OCIF in rats was significantly lower compared with that of OCIF. In fresh human liver perfusion, (3)H-poly(PEG)-OCIF was rarely taken up into the liver. On the other hand, more than 50% of the perfused OCIF was taken up. CONCLUSIONS: PEGylation of OCIF using poly(PEG) dramatically suppressed the uptake of OCIF into human liver as well as into rat liver and could be a promising approach for improving the pharmacokinetic and pharmacological effects of OCIF in the clinical setting.
Subject(s)
Bone Density Conservation Agents/pharmacokinetics , Liver/metabolism , Osteoprotegerin/pharmacokinetics , Polyethylene Glycols/chemistry , Animals , Biological Transport , Bone Density Conservation Agents/administration & dosage , Bone Density Conservation Agents/blood , Bone Density Conservation Agents/chemistry , Cells, Cultured , Chemistry, Pharmaceutical , Down-Regulation , Enzyme-Linked Immunosorbent Assay , Female , Heparin/metabolism , Humans , Injections, Intravenous , Kidney/metabolism , Maleates/chemistry , Mice , Osteoclasts/drug effects , Osteoprotegerin/administration & dosage , Osteoprotegerin/blood , Osteoprotegerin/chemistry , Ovariectomy , Perfusion , Rats , Rats, Sprague-Dawley , Spleen/metabolism , Tissue DistributionABSTRACT
A novel series of cathepsin K inhibitors derived from Novartis compound I is described. Optimization of the P1, P3, and P1' units led to the identification of 4-aminophenoxyacetic acid 24b with an IC(50) value of 4.8 nM, which possessed an excellent selectivity over other human cathepsins and good pharmacokinetic (PK) properties. Oral administration of compound 24b to ovariectomized (OVX) rats showed a trend toward an improvement of bone mineral density (BMD) in the femur bone.
Subject(s)
Amines/pharmacology , Cathepsins/antagonists & inhibitors , Enzyme Inhibitors/pharmacology , Administration, Oral , Amines/administration & dosage , Amines/chemistry , Animals , Bone Density/drug effects , Cathepsin B/antagonists & inhibitors , Cathepsin K , Cathepsin L , Cysteine Endopeptidases , Enzyme Activation/drug effects , Enzyme Inhibitors/administration & dosage , Enzyme Inhibitors/chemistry , Humans , Liver/metabolism , Microsomes/metabolism , Molecular Conformation , Ovariectomy , Rats , Recombinant Proteins/antagonists & inhibitors , Stereoisomerism , Structure-Activity RelationshipABSTRACT
Osteoclastogenesis inhibitory factor (OCIF) is a novel member of the Tumor Necrosis Factor Receptor superfamily and identical with Osteoprotegerin (OPG) discovered by Amgen researchers. OCIF/OPG is a decoy receptor (a soluble receptor that acts as an antagonist) that binds to osteoblast cells via Receptor Activator of NF-kappa B Ligand (RANKL) involved in the signal transduction between osteoblast cells and osteoclastic progenitor cells, eventually suppressing differentiation of the progenitor cells into osteoclasts. The balance between the OCIF/OPG and RANKL is regulated by cytokines and hormones. Studies on OCIF/OPG-RANKL system have provided important insights into the pathogenesis of human metabolic bone diseases, leading to the expectation of OCIF/OPG as a novel candidate for a therapeutic agent for metabolic bone diseases.
Subject(s)
Glycoproteins , Osteoporosis/drug therapy , Receptors, Cytoplasmic and Nuclear , Animals , Bone and Bones/metabolism , Carrier Proteins/physiology , Cell Differentiation/genetics , Clinical Trials as Topic , Drug Design , Glycoproteins/chemistry , Glycoproteins/physiology , Glycoproteins/therapeutic use , Humans , Membrane Glycoproteins/physiology , Osteoblasts , Osteoclasts/cytology , Osteoporosis/etiology , Osteoprotegerin , RANK Ligand , Receptor Activator of Nuclear Factor-kappa B , Receptors, Cytoplasmic and Nuclear/chemistry , Receptors, Cytoplasmic and Nuclear/physiology , Receptors, Cytoplasmic and Nuclear/therapeutic use , Receptors, Tumor Necrosis Factor , Signal Transduction/geneticsABSTRACT
Rat models of immobilization-induced osteopenia are characterized by uncoupling of bone metabolism, i.e., increased bone resorption and decreased bone formation in trabecular bone. Using such a rat model, the efficacy of osteoclastogenesis inhibitory factor (OCIF)/osteoprotegerin, a novel secreted protein that inhibits osteoclastogenesis, in reducing bone loss was investigated. Male Fischer rats were neurectomized and injected intramuscularly with either OCIF (0.2, 1.0, or 5.0 mg/kg body weight) or vehicle once daily for 7 days. On the eighth day after sciatic neurectomy, significant bone loss was observed in the vehicle-injected rats. OCIF ameliorated the decrease in bone mineral density (BMD) of both the proximal and distal femur in a dose-dependent manner. OCIF also ameliorated the decrease in bone strength of the femoral neck at the highest dose. A high correlation (r = 0.805) was detected between the BMD of the distal femur and the bone strength of the femoral neck. When OCIF was administered intermittently to the immobilized rats twice weekly (on days 1 and 4) after immobilization, it also ameliorated the decrease in BMD of the distal femur. These results suggest that OCIF has therapeutic potential for the treatment of immobilization-induced osteopenia.
