title: Effect of liposomally encapsulated MTX-DMPE conjugates upon TNF alpha and PGE2 release by lipopolysaccharide stimulated rat peritoneal macrophages.
abstract: The ability of liposomally encapsulated preparations of methotrexate (MTX) and three of its lipophilic derivatives (MTX-gamma-DMPE, MTX-alpha-DMPE and MTX-alpha,gamma-diDMPE) to alter mediator release by lipopolysaccharide (LPS)-stimulated rat peritoneal macrophages (PM theta) was investigated. The viability of these macrophages when incubated with approximately 6.0 nmol/10(5) cells of the respective liposomal preparations (MTX-LIPO, MTX-gamma-LIPO, MTX-alpha-LIPO and MTX-di-LIPO) for 20 h was greater than 80%. Treatment of macrophages, which had been incubated with MTX-alpha-LIPO (5.5 nmol/10(5) cells), MTX-gamma-LIPO (6.9 nmol/10(5) cells) and MTX-di-LIPO (4.5 nmol/10(5) cells) for 20 h, with antibody-coated sheep red blood cells resulted in 105 +/- 9.6%, 80.6 +/- 5.6% and 91 +/- 11.4% phagocytosis respectively (mean +/- S.E.M.). At similar concentrations of MTX-alpha-LIPO, MTX-gamma-LIPO and MTX-di-LIPO (6.5 nmol/10(5) cells), PGE2 release from LPS-stimulated rat peritoneal macrophages was inhibited by 85.3 +/- 3.7%, 68.7 +/- 0.6% and 88.8 +/- 2.2%, respectively (mean +/- S.E.M., n = 4). Incubation of these macrophages with 12, 10 and 9.4 nmol/10(5) cells of the respective liposomal preparations resulted in 89 +/- 3.3%, 62 +/- 5.5% and 85 +/- 3.9% inhibition of TNF alpha release (mean +/- S.E.M., n = 4). However, at this concentration MTX-di-LIPO was toxic. Neither MTX (20-2.5 nmol/10(5) cells) nor MTX-LIPO (5.6 nmol/10(5) cells) affected TNF alpha release from LPS-stimulated macrophages. Whilst free MTX was also ineffective at inhibiting PGE2 from these cells, incubation with MTX-LIPO at the above concentration resulted in 76.9 +/- 2.6% inhibition of the prostaglandins release.
authors.affiliation: Rheumatology Research Laboratory, University of Wales College of Medicine, Heath Park, Cardiff, UK.
authors.forename: A S
authors.initials: AS
authors.lastname: Williams
authors.forename: N
authors.initials: N
authors.lastname: Topley
authors.forename: B D
authors.initials: BD
authors.lastname: Williams
mesh_terms: D000255:Adenosine Triphosphate / Q000032:analysis; D000818:Animals; D015232:Dinoprostone / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008081:Liposomes; D017737:Macrophages, Peritoneal / Q000187:drug effects* / Q000378:metabolism; D008727:Methotrexate / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000494:pharmacology; D010587:Phagocytosis; D010714:Phosphatidylethanolamines / Q000138:chemical synthesis / Q000494:pharmacology*; D051381:Rats; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
chemical_list: D008070:Lipopolysaccharides; D008081:Liposomes; D010714:Phosphatidylethanolamines; D014409:Tumor Necrosis Factor-alpha; D000255:Adenosine Triphosphate; C047978:methotrexate-gamma-1,2-dimyristoylphosphatidylethanolamine; D015232:Dinoprostone; D008727:Methotrexate