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Bone resorption by cells isolated from rheumatoid synovium
J S Chang1, J M Quinn, A Demaziere
1Nuffield Department of Orthopaedic Surgery, Nuffield Orthopaedic Centre, Oxford, United Kingdom.
Annals of the Rheumatic Diseases
|November 1, 1992
Summary
Macrophages in rheumatoid arthritis (RA) synovium cause bone surface roughening, a distinct form of osteolysis. This mechanism, unlike osteoclast activity, is unaffected by common bone resorption factors, highlighting a novel pathway in RA joint erosion.
Area of Science:
- Rheumatology
- Cell Biology
- Orthopedics
Background:
- Osteolysis in rheumatoid arthritis (RA) erosions is a key pathological feature.
- The specific cellular mechanisms driving bone resorption in RA remain incompletely understood.
Purpose of the Study:
- To investigate the cellular mechanisms responsible for osteolysis in rheumatoid arthritis (RA).
- To characterize the bone resorption capabilities of synovial cells from RA patients.
Main Methods:
- Synovial cells were isolated from patients with rheumatoid arthritis (RA) and osteoarthritis.
- Bone resorption was assessed using a scanning electron microscope bone resorption assay.
- Macrophage activity and response to systemic and local factors were evaluated.
Main Results:
- Macrophages were the predominant cell type isolated from RA synovium.
- RA macrophages induced significant bone surface roughening but not distinct resorption pits.
- This macrophage-mediated bone resorption was unresponsive to systemic factors (calcitonin, PTH, 1,25-dihydroxyvitamin D3) and local factors (IL-1, PGE2).
Conclusions:
- Macrophage-mediated bone resorption in RA differs qualitatively and quantitatively from osteoclast activity.
- This distinct macrophage function likely contributes significantly to the marginal erosions observed in rheumatoid arthritis.
- Understanding this mechanism may offer new therapeutic targets for RA joint destruction.