title: The influence of methotrexate on the gene expression of the pro-inflammatory cytokine IL-12A in the therapy of rheumatoid arthritis.
abstract: OBJECTIVE
  Methotrexate (MTX) is a cornerstone in the treatment of rheumatoid arthritis (RA). Among its anti-proliferative activity, the anti-inflammatory mechanisms of MTX seem to play a major role in the treatment of RA. MTX reduces the production of pro-inflammatory cytokines such as interleukin (IL)-1, IL-2, IL-6 and interferon (INF)-γ, while the gene expression of anti-inflammatory Th2 cytokines like IL-4 and IL-10 is increased - altogether resulting in the anti-inflammatory effect. As little is known about the impact of MTX on other cytokines involved in the pathogenesis of RA, the present trial investigated the effect of MTX on IL-12A and IL-18 gene expression by peripheral blood mononuclear cells (PBMCs). For comparison, the effect on IL-6 and tumour necrosis factor (TNF) was analysed.
  
  
  METHODS
  Using real-time PCR, mRNA concentrations of pro-inflammatory cytokines were determined in PBMCs from 17 patients before and during MTX therapy. Furthermore, gene expression was correlated with clinical and pharmacokinetic parameters such as methotrexate polyglutamate concentrations (Spearman's correlation coefficient). To eliminate concomitant corticosteroids as confounding factor, a subgroup analysis for methotrexate without corticosteroids was performed in 6 patients.
  
  
  RESULTS
  MTX statistically significantly reduced the mRNA expression of IL-12A by PBMCs in rheumatoid arthritis patients (Wilcoxon-test for paired samples, p<0.046). Consistent with other reports, IL-6 was reduced under MTX treatment. Although the combination of MTX and corticosteroids significantly reduced the gene expression of IL-18, this key molecule was unaffected by MTX without corticosteroids. Our results were further supported by a negative correlation of methotrexate polyglutamate concentrations and the mRNA expression of the pro-inflammatory cytokines IL-6 and IL-12A.
  
  
  CONCLUSIONS
  We describe a novel effect of MTX reducing the gene expression of IL-12A independently of corticosteroid application in patients. This impact was further enhanced by a reduction of IL-12A-producing lymphocytes and neutrophils under MTX treatment. These results expand the understanding of the mechanism of action of the most widely used drug in RA.
authors: Medical University of Vienna, Department of Clinical Pharmacology, Vienna, Austria. eva-luise.hobl@meduniwien.ac.at
authors: Eva-Luise
authors: EL
authors: Hobl
authors: Robert M
authors: RM
authors: Mader
authors: Ludwig
authors: L
authors: Erlacher
authors: Bernhard
authors: B
authors: Duhm
authors: Monika
authors: M
authors: Mustak
authors: Hans
authors: H
authors: Bröll
authors: Petra
authors: P
authors: Högger
authors: Maria
authors: M
authors: Kalipciyan
authors: Bernd
authors: B
authors: Jilma
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use; D018501:Antirheumatic Agents / Q000493:pharmacokinetics / Q000627:therapeutic use*; D001172:Arthritis, Rheumatoid / Q000188:drug therapy* / Q000235:genetics / Q000503:physiopathology; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D005260:Female; D015870:Gene Expression / Q000187:drug effects*; D005938:Glucocorticoids / Q000627:therapeutic use; D006304:Health Status; D006801:Humans; D053765:Interleukin-12 Subunit p35 / Q000235:genetics* / Q000378:metabolism; D020382:Interleukin-18 / Q000235:genetics / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008727:Methotrexate / Q000031:analogs & derivatives / Q000097:blood / Q000493:pharmacokinetics / Q000627:therapeutic use*; D008875:Middle Aged; D011099:Polyglutamic Acid / Q000031:analogs & derivatives / Q000097:blood; D012333:RNA, Messenger / Q000378:metabolism; D012720:Severity of Illness Index; D016896:Treatment Outcome
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D018501:Antirheumatic Agents; D005938:Glucocorticoids; D053765:Interleukin-12 Subunit p35; D020382:Interleukin-18; D012333:RNA, Messenger; D011099:Polyglutamic Acid; C014085:methotrexate polyglutamate; D008727:Methotrexate