ABSTRACT
INTRODUCTION: Pulmonary innate immunity is impaired in cigarette smokers, because the abundant oxidants present in cigarette smoke (CS) cause injury to lung cells. Pulmonary surfactant is a unique material that is important roles in reducing surface tension in the lung and defending against invading pathogens. Oxidants reportedly cleave surfactant phospholipids, resulting in the production of oxidized phospholipids, such as 1-palmitoyl-2-(9'-oxo-nonanoyl)-glycerophosphocholine (PON-GPC). Although oxidation of surfactant lipids is thought to be involved in the pathogenesis of smoking-related lung disease, there are no reports on the effect of oxidized surfactant lipid on the immune function of macrophages. We hypothesized that cigarette smoking elevates PON-GPC levels in the lung, and that PON-GPC impairs the innate immune function of macrophages. METHODS: The levels of PON-GPC in bronchoalveolar lavage fluid (BALF) recovered from mice exposed to CS for 2 weeks (n = 7) were measured by liquid chromatography with electrospray-ionization tandem mass spectrometry. The effects of PON-GPC on inducibility of tumor necrosis factor (TNF)-α, nitric oxide (NO), and nicotinamide adenine dinucleotide phosphate (NADP(+)) production, as well as bactericidal activity, were investigated in RAW264.7 cells or primary alveolar macrophages. RESULTS: The levels of PON-GPC in BALF of mice exposed to CS were significantly elevated, compared with those of control mice. PON-GPC attenuated TNF-α, NO, and NADP(+) production in macrophages on stimulation with LPS plus IFN-γ. PON-GPC treatment attenuated the phosphorylation of p38 mitogen-activated protein kinase (MAPK). In addition, PON-GPC reduced the bactericidal activity of RAW264.7 cells. CONCLUSIONS: CS may attenuate innate immunity in the lungs through oxidization of surfactant phospholipids.
Subject(s)
Macrophages, Alveolar/immunology , Macrophages, Alveolar/metabolism , Phosphatidylcholines/immunology , Phosphatidylcholines/pharmacology , Phospholipids/chemistry , Smoking/immunology , 1,2-Dipalmitoylphosphatidylcholine/pharmacology , Animals , Apoptosis/drug effects , Bronchoalveolar Lavage Fluid/immunology , Cell Survival/drug effects , Cells, Cultured , Interferon-gamma/pharmacology , Lipopolysaccharides/pharmacology , Macrophages, Alveolar/drug effects , Male , Mice , NADP/drug effects , NADP/metabolism , Nitric Oxide/metabolism , Oxidation-Reduction , Phagocytosis/drug effects , Phosphatidylcholines/analysis , Reactive Oxygen Species/metabolism , Signal Transduction , Smoking/adverse effects , Statistics, Nonparametric , Tumor Necrosis Factor-alpha/drug effects , Tumor Necrosis Factor-alpha/metabolism , p38 Mitogen-Activated Protein Kinases/drug effects , p38 Mitogen-Activated Protein Kinases/metabolismABSTRACT
A protein kinase inhibitor UCN-01 binds with high affinity to human alpha 1-acid glycoprotein (hAGP) which may compromise the drugs therapeutic effectiveness. Liposomal formulations of UCN-01 have been evaluated as a means of reducing the impact of binding to hAGP. However, in an initial study, UCN-01 was released rapidly from liposomes added to rat plasma containing hAGP. The purpose of this study was to develop a liposomal formulation of UCN-01 that only slowly released drug. Liposomes composed of lipids with a high phase transition temperature and having an average particle size of 120 nm and above reduced leaking of UCN-01 when the formulations were evaluated by adding to rat plasma containing hAGP. Furthermore, formulations composed of larger liposomes were also more effective in vivo; in tests in which liposomal preparations were injected together with hAGP into rats, more UCN-01 was retained in liposomes for 24h after administration of 155 nm liposomes as compared to 112 nm liposomes.
Subject(s)
Antineoplastic Agents/chemistry , Protein Kinase Inhibitors/chemistry , Staurosporine/analogs & derivatives , Animals , Antineoplastic Agents/pharmacokinetics , Delayed-Action Preparations , Liposomes , Male , Orosomucoid/metabolism , Particle Size , Protein Binding , Protein Kinase Inhibitors/pharmacokinetics , Rats , Rats, Sprague-Dawley , Staurosporine/chemistry , Staurosporine/pharmacokinetics , Transition TemperatureABSTRACT
The efficacy of many drugs is improved by liposomal formulations. The greatest improvements in therapeutic benefits are achieved if the drug is retained in the liposomes for several hours after administration. Many basic drugs can be concentrated efficiently into liposomes in response to a transmembrane pH gradient. However, the rate of release from liposomal formulations is drug-dependent; for example, doxorubicin is released slowly from liposomes whereas vincristine leaks out rapidly. The aim of this study was to identify the causes of the rapid release of drugs from liposomes and then to apply this knowledge to the development of more stable formulations. Our initial focus was to explore the influence of liposomal size on the rate of release of drugs. The retention of doxorubicin within liposomes was independent of the particle size as far as this experimental condition was concerned. However, the rate of release of vincristine varied in relation to the particle size of the liposomes; vincristine was retained more effectively in larger liposomes. Experimental data generated using (31)P-NMR analysis and trap volume measurements, indicated that the number of lipid bilayers in liposomes increased as the particle size was increased. Additional lipid bilayers are likely to present a more effective barrier thereby slowing the release of drugs.
