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Variability in cytokine and cell adhesion molecule staining in arthroscopic synovial biopsies: quantification using
P P Youssef1, S Triantafillou, A Parker
1Department of Pathology, Repatriation General Hospital, Daw Park, SA, Australia.
Insights
Synovial biopsies in rheumatoid arthritis (RA) show minimal variability in cytokine and cell adhesion molecule staining. This suggests a small number of biopsies accurately reflect molecular expression within a single rheumatoid knee joint.
Area of Science:
- Rheumatology
- Immunology
- Molecular Biology
Background:
- Rheumatoid arthritis (RA) is characterized by synovial inflammation.
- Cytokines and cell adhesion molecules play crucial roles in RA pathogenesis.
- Understanding molecular variability in the rheumatoid joint is essential for targeted therapies.
Purpose of the Study:
- To assess the variability of immunostaining for key cytokines and cell adhesion molecules within a single rheumatoid knee joint.
- To determine the number of synovial biopsies needed for accurate molecular expression analysis.
Main Methods:
- Multiple arthroscopic synovial biopsies (4-7 sites) were obtained from 8 RA patients.
- Immunoperoxidase staining was performed for cytokines (TNF-alpha, IL-8, IL-1beta, IL-1ra) and cell adhesion molecules (E-selectin, P-selectin, ICAM-1, PECAM).
- Immunostaining was quantified using color video image analysis.
Main Results:
- Sampling variation resulted in significant differences in cytokine staining in at most 22% of paired biopsies (typically <10%).
- No significant differences were found in intra- and interbiopsy variability for cell adhesion molecule staining in the sublining and vessels.
- Variability within a single biopsy generally mirrored variability between biopsies from different sites.
Conclusions:
- Immunostaining variability for cytokines and cell adhesion molecules within a rheumatoid joint is low.
- A limited number of synovial biopsies are sufficient to accurately assess molecular expression in RA.
- These findings support the use of targeted molecular profiling in rheumatoid knee joints.
Objective:
To investigate the variability in immunostaining for cytokines and cell adhesion molecules using multiple arthroscopically directed synovial biopsies from within a rheumatoid knee joint, quantitated by color video image analysis.
Methods:
Needle arthroscopic biopsies were taken from multiple sites (4-7 sites) around a knee joint in 8 patients with rheumatoid arthritis (RA). In 5 patients, immunoperoxidase staining for the cytokines tumor necrosis factor alpha (TNF-alpha), interleukin 8 (IL-8), and IL-1beta as well as the IL-1 receptor antagonist protein (IL-1ra) was performed. In 3 patients, immunoperoxidase staining for the cell adhesion molecules E-selectin (CD62E), P-selectin (CD62P), intercellular adhesion molecule 1 (ICAM-1, CD54), and platelet endothelial cell adhesion molecule (PECAM, CD31) was performed. Immunostaining was quantified using color video image analysis.
Results:
The overall probability of paired biopsies from the same RA knee joint being significantly different from each other due to sampling variation was at most 22% for cytokine staining (usually less than 10%). There were no significant differences between intrabiopsy and interbiopsy variability for cell adhesion molecule staining of the sublining and vessels.
Conclusion:
The variability in cytokine and cell adhesion molecule staining within any single biopsy usually reflects the variability between biopsies taken from different sites in the same rheumatoid joint when the immunostaining is quantified using color video image analysis. Therefore, only a small number of synovial biopsies are required to accurately determine the cytokine and cell adhesion molecule expression in a single joint.
