bone loss ( 4 ). Osteoprotegerin (OPG), on the other hand, is an osteoblast-secreted product of the Wnt signaling, which prevents excess osteoclastogenesis by acting as a decoy receptor for RANKL, thus inhibiting it from binding and activating its receptor RANK ( 14 ). These cellular interactions
Panagiota Klentrou, Kirina Angrish, Nafisa Awadia, Nigel Kurgan, Rozalia Kouvelioti and Bareket Falk
Jeffrey B. Driban, Easwaran Balasubramanian, Mamta Amin, Michael R. Sitler, Marvin C. Ziskin and Mary F. Barbe
Joint trauma is a risk factor for osteoarthritis (OA), which is becoming an increasingly important orthopedic concern for athletes and nonathletes alike. For advances in OA prevention, diagnosis, and treatment to occur, a greater understanding of the biochemical environment of the affected joint is needed.
To demonstrate the potential of a biochemical technique to enhance our understanding of and diagnostic capabilities for osteoarthritis.
Outpatient orthopedic practice.
8 subjects: 4 OA-knee participants (65 ± 6 y of age) and 4 normal-knee participants (54 ± 10 y) with no history of knee OA based on bilateral standing radiographs.
The independent variable was group (OA knee, normal knee).
Main Outcome Measures:
16 knee synovial-protein concentrations categorized as follows: 4 as pro-inflammatory, or catabolic, cytokines; 5 as anti-inflammatory, or protective, cytokines; 3 as catabolic enzymes; 2 as tissue inhibitors of metalloproteinases [TIMPs]; and 2 as adipokines.
Two anti-inflammatory cytokines (interleukin [IL]-13 and osteoprotegerin) and a pro-inflammatory cytokine (IL-1β) were significantly lower in the OA knees. Two catabolic enzymes (matrix metalloproteinase [MMP]-2 and MMP-3) were significantly elevated in OA knees. TIMP-2, an inhibitor of MMPs, was significantly elevated in OA knees.
Six of the 16 synovial-fluid proteins were significantly different between OA knees and normal knees in this study. Future research using a similar multiplex ELISA approach or other proteomic techniques may enable researchers and clinicians to develop more accurate biochemical profiles of synovial fluid to help diagnose OA, identify subsets of OA or individual characteristics, guide clinical decisions, and identify patients at risk for OA after knee injury.
Jennifer Dekker, Katlynne Nelson, Nigel Kurgan, Bareket Falk, Andrea Josse and Panagiota Klentrou
and secretion of the anabolic osteoprotegerin (OPG) ( 22 ). OPG is an inhibitor of bone resorption as it is a decoy receptor for the catabolic osteoclast-stimulating nuclear factor kappa-β ligand (RANKL). When RANKL binds to its associated RANK receptor on the osteoclast, the latter’s resorption