Inflammation and joint destruction may be linked to the generation of cartilage metabolites of ADAMTS-5 through activation of toll-like receptors

  • Osteoarthritis Cartilage. 2020 May;28(5):658-668. doi: 10.1016/j.joca.2019.11.002.
N Sharma  1 ,  P Drobinski  2 ,  A Kayed  3 ,  Z Chen  4 ,  C F Kjelgaard-Petersen  5 ,  T Gantzel  6 ,  M A Karsdal  7 ,  M Michaelis  8 ,  C Ladel  9 ,  A C Bay-Jensen  10 ,  S Lindemann  11 ,  C S Thudium  12
Affiliations
  • 1. Rheumatology, Nordic Bioscience, Herlev Hovedgade 207, DK-2730, Herlev, Denmark; Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen N, Denmark. Electronic address: [email protected].
  • 2. Rheumatology, Nordic Bioscience, Herlev Hovedgade 207, DK-2730, Herlev, Denmark; Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen N, Denmark. Electronic address: [email protected].
  • 3. Rheumatology, Nordic Bioscience, Herlev Hovedgade 207, DK-2730, Herlev, Denmark; Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen N, Denmark. Electronic address: [email protected].
  • 4. Rheumatology, Nordic Bioscience, Herlev Hovedgade 207, DK-2730, Herlev, Denmark; Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen N, Denmark. Electronic address: [email protected].
  • 5. Rheumatology, Nordic Bioscience, Herlev Hovedgade 207, DK-2730, Herlev, Denmark. Electronic address: [email protected].
  • 6. Orthopaedic Surgery Unit, Gentofte University Hospital, Gentofte, Denmark. Electronic address: [email protected].
  • 7. Rheumatology, Nordic Bioscience, Herlev Hovedgade 207, DK-2730, Herlev, Denmark. Electronic address: [email protected].
  • 8. Head of Osteoarthritis Research and Early Clinical Development, Merck KGaA, Darmstadt, Germany. Electronic address: [email protected].
  • 9. Clinical Biomarker & Diagnostics Lead, Merck KGaA, Darmstadt, Germany. Electronic address: [email protected].
  • 10. Rheumatology, Nordic Bioscience, Herlev Hovedgade 207, DK-2730, Herlev, Denmark. Electronic address: [email protected].
  • 11. Head of Exploratory Osteoarthritis, Merck KGaA, Darmstadt, Germany. Electronic address: [email protected].
  • 12. Rheumatology, Nordic Bioscience, Herlev Hovedgade 207, DK-2730, Herlev, Denmark. Electronic address: [email protected].
PMID: 31734268 DOI: 10.1016/j.joca.2019.11.002
Abstract

Objective: Links between pain and joint degradation are poorly understood. We investigated the role of activation of Toll-like receptors (TLR) by cartilage metabolites in initiating and maintaining the inflammatory loop in OA causing joint destruction.

Methods: Synovial membrane explants (SMEs) were prepared from OA patients' synovial biopsies. SMEs were cultured for 10 days under following conditions: culture medium alone, OSM + TNFα, TLR2 Agonist - Pam2CSK4, Pam3CSK4 or synthetic aggrecan 32-mer, TLR4 Agonist - Lipid A. Release of pro-inflammatory and degradation biomarkers (acMMP3 and C3M) were measured by ELISA in conditioned media along with IL-6. Additionally, human cartilage was digested with ADAMTS-5, with or without the ADAMTS-5 inhibiting nanobody - M6495. Digested cartilage solution (DCS) and synthetic 32-mer were tested for TLR activation in SEAP based TLR reporter assay.

Results: Western blotting confirmed TLR2 and TLR4 in untreated OA synovial biopsies. TLR agonists showed an increase in release of biomarkers - acMMP3 and C3M in SME. Synthetic 32-mer showed no activation in the TLR reporter assay. ADAMTS-5 degraded cartilage fragments activated TLR2 in vitro. Adding M6495 - an anti-ADAMTS-5 inhibiting nanobody®, blocked ADAMTS-5-mediated DCS TLR2 activation.

Conclusion: TLR2 is expressed in synovium of OA patients and their activation by synthetic ligands causes increased tissue turnover. ADAMTS-5-mediated cartilage degradation leads to release of aggrecan fragments which activates the TLR2 receptor in vitro. M6495 suppressed cartilage degradation by ADAMTS-5, limiting the activation of TLR2. In conclusion, pain and joint destruction may be linked to generation of ADAMTS-5 cartilage metabolites.

Keywords
Inflammation; Innate immunity; Osteoarthritis (OA); Synovial membrane; Toll like receptors (TLRs).
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