title: The suppression of rat collagen-induced arthritis and inhibition of macrophage derived mediator release by liposomal methotrexate formulations.
abstract: OBJECTIVE
  This study was designed to determine whether liposomes are suitable vehicles for the delivery of methotrexate (MTX-gamma-DMPE) for arthritis therapy.
  
  
  METHODS
  Liposomal formulations containing either egg lecithin (EPC), cholesterol (CHOL) and phosphatidic acid (PA) (MTX-EPC) or distearoylphosphatidylcholine (DSPC), CHOL and distearoylphosphatidylethanolamine conjugated to polyethyleneglycol (PEG) (MTX-PEG) were employed. Rat peritoneal macrophages (rPM phi) were used to test the mechanism of action of these liposomes in vitro, whilst, the rat collagen-induced arthritis (CIA) model was used to evaluate the in vivo efficacy of MTX-EPC and MTX-PEG.
  
  
  METHODS
  In vitro, rPM phi were incubated with liposomal MTX concentrations ranging from 0 to 15 microg/well. In vivo, rats were given 4 daily intravenous injections of liposomal MTX (2.5 mg/Kg).
  
  
  METHODS
  IL-1beta and prostaglandin-E2 (PGE2) release from rPM phi were quantified by immunoradiometric assay. Arthritis progression, in vivo, was measured by serial clinical score and hind paw diameter measurements.
  
  
  RESULTS
  MTX-EPC and MTX-PEG respectively (15 microg of MTX and 0.15 mg of lipid) were powerful inhibitors of both IL-1beta (77 +/- 2.3%; 79 +/- 4.0%) and PGE2 (75.5 +/- 4.9%; 68.5 +/- 2.3%) release (mean +/- SEM % inhibition) from lipopolysaccaride stimulated rPM phi. In vivo, only MTX-EPC exerted an anti-inflammatory effect, clinical score (p < 0.001) and paw diameter (p < 0.001) measurements being significantly lower than in control rats, after 2 days treatment.
  
  
  CONCLUSIONS
  MTX-EPC and MTX-PEG are potent inhibitors of pro-inflammatory mediators in vitro, but liposomes with long circulation times do not appear to have therapeutic potential for treating arthritis in vivo.
authors.affiliation: Rheumatology Research Laboratory, University of Wales College of Medicine, Cardiff, UK. wmdasw@cardiff.ac.uk
authors.forename: A
authors.initials: A
authors.lastname: Williams
authors.forename: R
authors.initials: R
authors.lastname: Goodfellow
authors.forename: N
authors.initials: N
authors.lastname: Topley
authors.forename: N
authors.initials: N
authors.lastname: Amos
authors.forename: B
authors.initials: B
authors.lastname: Williams
mesh_terms: D000818:Animals; D018501:Antirheumatic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D001168:Arthritis / Q000139:chemically induced / Q000188:drug therapy*; D001772:Blood Cell Count; D003094:Collagen; D016207:Cytokines / Q000096:biosynthesis; D015232:Dinoprostone / Q000096:biosynthesis; D004337:Drug Carriers; D066298:In Vitro Techniques; D007375:Interleukin-1 / Q000096:biosynthesis; D008081:Liposomes; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008727:Methotrexate / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D011917:Rats, Inbred Lew
chemical_list: D018501:Antirheumatic Agents; D016207:Cytokines; D004337:Drug Carriers; D007375:Interleukin-1; D008081:Liposomes; D003094:Collagen; D015232:Dinoprostone; D008727:Methotrexate