The potential of multiple synovial-fluid protein-concentration analyses in the assessment of knee osteoarthritis.
BACKGROUND
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.


OBJECTIVE
To demonstrate the potential of a biochemical technique to enhance our understanding of and diagnostic capabilities for osteoarthritis.


METHODS
Cross-sectional.


METHODS
Outpatient orthopedic practice.


METHODS
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.


METHODS
The independent variable was group (OA knee, normal knee).


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Division of Rheumatology, Tufts Medical Center, Boston, MA, USA.
Jeffrey B
JB
Driban
Easwaran
E
Balasubramanian
Mamta
M
Amin
Michael R
MR
Sitler
Marvin C
MC
Ziskin
Mary F
MF
Barbe
D000368:Aged; D003430:Cross-Sectional Studies; D016207:Cytokines / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D020782:Matrix Metalloproteinases / Q000378:metabolism*; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000378:metabolism*; D010865:Pilot Projects; D013582:Synovial Fluid / Q000737:chemistry* / Q000378:metabolism
D016207:Cytokines; D020782:Matrix Metalloproteinases