Differential effects of FK506 and methotrexate on inflammatory cytokine levels in rat adjuvant-induced arthritis

J Rheumatol. 2003 Oct;30(10):2193-200.


Objective: To investigate the effects of prophylactic and therapeutic treatments with FK506 (tacrolimus), an immunosuppressive drug that specifically inhibits T cell activation, and methotrexate (MTX) on inflammatory cytokines, tumor necrosis factor (TNF)-a, interleukin (IL)-1beta, and IL-6 levels in rat adjuvant-induced arthritis (AIA).

Methods: AIA was induced in female Lewis rats. Arthritis was assessed by hindpaw swelling. TNF-a, IL-1beta, and IL-6 levels in paw extracts were determined by ELISA. To assess the effects on cytokine levels, rats were treated prophylactically with FK506 (3 mg/kg) or MTX (0.1 mg/kg) from day 1 to day 17, and therapeutically with FK506 (5 mg/kg) or MTX (1 mg/kg) from day 15 to day 17 (3-day treatment) or day 15 to 20 (6-day treatment) by oral administration.

Results: TNF-a, IL-1beta, and IL-6 levels in paw tissue were found to significantly increase between day 15 and day 21 after adjuvant injection, when the arthritis was in a developed stage. Prophylactic treatment with FK506 and MTX suppressed arthritis and reduced the levels of those inflammatory cytokines. FK506 caused a marked reduction of TNF-a and IL-1beta levels in paw tissue even in short-term (3-day) therapeutic treatment. It reduced all levels of TNF-a, IL-1beta, and IL-6 in paws in 6-day therapeutic treatment. In contrast, therapeutic treatment with MTX affected neither TNF-a or IL-6 levels in paws. MTX reduced IL-1beta levels only in the 6-day treatment.

Conclusion: FK506 is more effective than MTX in reducing elevated levels of inflammatory cytokines TNF-a, IL-1beta, and IL-6 in established stages of AIA. Our findings suggest that inhibition of T cell activation results in a rapid reduction of inflammatory cytokine levels even after the arthritis is established in AIA.

MeSH terms

  • Animals
  • Arthritis, Experimental / drug therapy*
  • Arthritis, Experimental / metabolism
  • Arthritis, Experimental / pathology
  • Cytokines / metabolism*
  • Disease Models, Animal
  • Dose-Response Relationship, Drug
  • Drug Administration Schedule
  • Edema / drug therapy
  • Edema / pathology
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Hindlimb / drug effects
  • Hindlimb / metabolism
  • Hindlimb / pathology
  • Immunosuppressive Agents / administration & dosage
  • Immunosuppressive Agents / therapeutic use*
  • Interleukin-1 / metabolism
  • Interleukin-6 / metabolism
  • Methotrexate / administration & dosage
  • Methotrexate / therapeutic use*
  • Rats
  • Rats, Inbred Lew
  • Tacrolimus / administration & dosage
  • Tacrolimus / therapeutic use*
  • Tumor Necrosis Factor-alpha / analysis


  • Cytokines
  • Immunosuppressive Agents
  • Interleukin-1
  • Interleukin-6
  • Tumor Necrosis Factor-alpha
  • Tacrolimus
  • Methotrexate