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Inhibitors of mitogen-activated protein kinases downregulate COX-2 expression in human chondrocytes

Riina Nieminen1, Sari Leinonen, Aleksi Lahti

  • 1The Immunopharmacology Research Group, Medical School, University of Tampere, and Tampere University Hospital, Research Unit, Finland.

Mediators of Inflammation
|November 1, 2005
PubMed

Insights

Mitogen-activated protein kinase (MAPK) pathways Erk1/2, p38, and JNK activation increases cyclooxygenase-2 (COX-2) expression and prostaglandin E2 (PGE2) production in human chondrocytes. Inhibiting these pathways reduces inflammation markers in joint cells.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Molecular Biology

Background:

  • Rheumatoid and osteoarthritis involve cyclooxygenase-2 (COX-2) expression in cartilage, leading to pro-inflammatory prostanoid production.
  • Understanding the regulation of COX-2 in chondrocytes is crucial for developing targeted therapies for joint inflammation.

Purpose of the Study:

  • To investigate the impact of mitogen-activated protein kinase (MAPK) pathway inhibitors (Erk1/2, p38, JNK) on COX-2 expression and prostaglandin E2 (PGE2) production in human chondrocytes.
  • To elucidate the role of specific MAPK pathways in mediating IL-1beta-induced COX-2 upregulation.

Main Methods:

  • Utilized immortalized human T/C28a2 chondrocytes.
  • Administered IL-1beta to induce inflammation and subsequently applied specific MAPK pathway inhibitors (PD98059 for Erk1/2, SB203580 for p38, SP600125 for JNK).
  • Assessed COX-2 expression (protein and mRNA) and PGE2 production using various concentrations of inhibitors and control compounds; analyzed temporal effects on mRNA expression.

Main Results:

  • IL-1beta induced transient activation of Erk1/2, p38, and JNK pathways, followed by increased COX-2 expression and PGE2 production.
  • PD98059 (Erk1/2 inhibitor) dose-dependently suppressed IL-1beta-induced COX-2 expression and PGE2 production.
  • SB203580 (p38 inhibitor) inhibited COX-2 protein and mRNA expression and PGE2 synthesis at micromolar concentrations.
  • SP600125 (JNK inhibitor) dose-dependently reduced COX-2 expression and PGE2 formation, with evidence of post-transcriptional regulation impacting later mRNA levels.

Conclusions:

  • Activation of Erk1/2, p38, and JNK pathways are key signaling cascades involved in the IL-1beta-induced upregulation of COX-2 expression and PGE2 production in human chondrocytes.
  • Targeting these MAPK pathways offers a potential therapeutic strategy for managing inflammatory conditions in joints characterized by elevated COX-2 activity.

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