Involvement of transient receptor potential vanilloid 1 receptors in protease-activated receptor-2-induced joint inflammation and nociception

Zs Helyes, K. Sándor, É Borbély, V. Tékus, E. Pintér, K. Elekes, D. M. Tóth, J. Szolcsányi, J. J. McDougall

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Abstract

Protease-activated receptor-2 (PAR-2) is a G-protein-coupled receptor activated through proteolytic cleavage. It is localized on epithelial, endothelial and inflammatory cells, as well as on transient receptor potential vanilloid 1 (TRPV1) receptor-expressing neurones. It plays an important role in inflammatory/nociceptive processes. Since there are few reports concerning PAR-2 function in joints, the effects of intraarticular PAR-2 activation on joint pain and inflammation were studied. Secondary hyperalgesia/allodynia, spontaneous weight distribution, swelling and inflammatory cytokine production were measured and the involvement of TRPV1 ion channels was investigated in rats and mice. Injection of the PAR-2 receptor agonist SLIGRL-NH2 into the knee decreased touch sensitivity and weight bearing of the ipsilateral hindlimb in both species. Secondary mechanical allodynia/hyperalgesia and impaired weight distribution were significantly reduced by the TRPV1 antagonist SB366791 in rats and by the genetic deletion of this receptor in mice. PAR-2 activation did not cause significant joint swelling, but increased IL-1β concentration which was not influenced by the lack of the TRPV1 channel. For comparison, intraplantar SLIGRL-NH2 evoked similar primary mechanical hyperalgesia and impaired weight distribution in both WT and TRPV1 deficient mice, but oedema was smaller in the knockouts. The inactive peptide, LRGILS-NH2, injected into either site did not induce any inflammatory or nociceptive changes. These data provide evidence for a significant role of TRPV1 receptors in secondary mechanical hyperalgesia/allodynia and spontaneous pain induced by PAR-2 receptor activation in the knee joint. Although intraplantar PAR-2 activation-induced oedema is also TRPV1 receptor-mediated, primary mechanical hyperalgesia, impaired weight distribution and IL-1β production are independent of this channel.

Original languageEnglish
Pages (from-to)351-358
Number of pages8
JournalEuropean Journal of Pain
Volume14
Issue number4
DOIs
Publication statusPublished - Apr 1 2010

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Keywords

  • Allodynia
  • Arthritis
  • Capsaicin-sensitive sensory nerves
  • Inflammatory cytokines
  • Mechanical hyperalgesia

ASJC Scopus subject areas

  • Anesthesiology and Pain Medicine

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