The suppression of rat collagen-induced arthritis and inhibition of macrophage derived mediator release by liposomal methotrexate formulations

Inflamm Res. 2000 Apr;49(4):155-61. doi: 10.1007/s000110050575.


Objective and design: This study was designed to determine whether liposomes are suitable vehicles for the delivery of methotrexate (MTX-gamma-DMPE) for arthritis therapy.

Material or subjects: 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.

Treatment: 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antirheumatic Agents / administration & dosage
  • Antirheumatic Agents / pharmacology*
  • Arthritis / chemically induced
  • Arthritis / drug therapy*
  • Blood Cell Count
  • Collagen*
  • Cytokines / biosynthesis
  • Dinoprostone / biosynthesis
  • Drug Carriers
  • In Vitro Techniques
  • Interleukin-1 / biosynthesis
  • Liposomes
  • Macrophages / drug effects
  • Macrophages / metabolism*
  • Male
  • Methotrexate / administration & dosage
  • Methotrexate / pharmacology*
  • Rats
  • Rats, Inbred Lew


  • Antirheumatic Agents
  • Cytokines
  • Drug Carriers
  • Interleukin-1
  • Liposomes
  • Collagen
  • Dinoprostone
  • Methotrexate