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Published on: May 24, 2024

Therapeutic promise of proteinase-activated receptor-2 antagonism in joint inflammation

Elizabeth B Kelso1, John C Lockhart, Todd Hembrough

  • 1Center for Rheumatic Diseases, Royal Infirmary, Glasgow, Scotland, United Kingdom.

The Journal of Pharmacology and Experimental Therapeutics
|November 2, 2005
PubMed

Insights

Proteinase-activated receptor-2 (PAR2) plays a key role in joint inflammation. Targeting PAR2 with novel inhibitors, including small molecules, offers a promising new therapeutic strategy for arthritis treatment.

Area of Science:

  • Immunology
  • Rheumatology
  • Molecular Biology

Background:

  • Biological therapies like tumor necrosis factor-alpha inhibitors have limitations in rheumatoid arthritis treatment, with many patients showing no response.
  • Current treatments often involve combination therapy, indicating unmet needs in rheumatoid arthritis management.

Purpose of the Study:

  • To investigate proteinase-activated receptor (PAR)-2 as a novel therapeutic target for joint inflammation.
  • To evaluate the role of PAR2 activation in inflammatory arthritis models.

Main Methods:

  • Induction of joint inflammation using intra-articular carrageenan/kaolin (C/K) injection in mice.
  • Assessment of synovial PAR2 up-regulation via immunoblotting and inhibition using small interfering RNA (siRNA).
  • Evaluation of PAR2 knockout mice response to serine proteinases and the efficacy of serine proteinase inhibitors and PAR2-targeting antibodies (B5, SAM-11).
  • Testing of a novel small molecule PAR2 antagonist (ENMD-1068).

Main Results:

  • C/K injection induced joint swelling and synovial PAR2 up-regulation.
  • siRNA-mediated inhibition of PAR2 significantly reduced joint inflammation.
  • Joint swelling induced by serine proteinases was dependent on PAR2, as shown in PAR2 knockout mice.
  • Serine proteinase inhibitors, PAR2 antiserum (B5), and PAR2 monoclonal antibody (SAM-11) attenuated inflammation.
  • The novel small molecule PAR2 antagonist ENMD-1068 dose-dependently reduced joint inflammation.

Conclusions:

  • Proteinase-activated receptor-2 (PAR2) is a critical mediator of joint inflammation.
  • Targeting PAR2, through various strategies including small molecule antagonists, represents a promising therapeutic approach for treating arthritis.

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