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Reduced synovial membrane macrophage numbers, ELAM-1 expression, and lining layer hyperplasia in psoriatic arthritis
Objective:
To define the immunohistologic features of the synovial membrane (SM) of patients with psoriatic arthritis (PA) and to compare them with those of an age- and disease-duration-matched population of patients with rheumatoid arthritis (RA).
Methods:
Synovial membrane needle biopsy was performed on 15 PA patients with knee involvement (8 had asymmetric oligoarthritis and 7 had symmetric polyarthritis) and on 15 RA controls. Specimens were stained with monoclonal antibodies against T cells (CD3, CD8, CD4, CD45RO), B cells (CD20), macrophages (Mac387, CD14), and cells bearing class II antigens (DAKO-DR). Vascular endothelium was examined using a polyclonal antibody to Factor VIII-related antigen, and adhesion molecule expression was examined using antibodies 1.3B6, 6.5B5, and 1.4C3, which identify endothelial leukocyte adhesion molecule 1 (ELAM-1), intercellular adhesion molecule 1 (ICAM-1), and vascular cell adhesion molecule 1 (VCAM-1), respectively.
Results:
There was significantly less lining layer hyperplasia, fewer macrophages, and a greater number of blood vessels in PA SM than in RA SM: ELAM-1 expression was less intense in PA than in RA SM, while there was no difference in expression of ICAM-1 and VCAM-1. Numbers of B cells, T cells, and T cell subsets (predominantly CD4, CD45RO T cells) were similar in both groups of patients.
Conclusion:
Our findings demonstrate important differences in the immunohistologic features of PA and RA SM: The PA SM is more vascular, ELAM-1 expression is less intense, and fewer macrophages invade the stroma and migrate to the lining layer than in RA SM: However, the lymphocytic infiltrate in the SM of both groups is similar.
Insights
Psoriatic arthritis (PA) synovial membranes show more blood vessels and fewer macrophages than rheumatoid arthritis (RA) synovial membranes. Lymphocyte infiltrates are similar in both psoriatic arthritis and rheumatoid arthritis.
Area of Science:
- Immunohistology
- Rheumatology
- Pathology
Background:
- Psoriatic arthritis (PA) and rheumatoid arthritis (RA) are chronic inflammatory joint diseases.
- Synovial membrane (SM) pathology is central to both conditions.
- Understanding differences in SM histology can inform treatment strategies.
Purpose of the Study:
- To characterize the immunohistologic features of synovial membranes in PA.
- To compare PA SM histology with that of RA SM in an age- and disease-duration-matched cohort.
Main Methods:
- Synovial membrane needle biopsies from 15 PA patients and 15 RA controls.
- Immunohistochemical staining for T cells (CD3, CD8, CD4, CD45RO), B cells (CD20), macrophages (Mac387, CD14), and HLA-DR.
- Assessment of vascular endothelium (Factor VIII-related antigen) and adhesion molecules (ELAM-1, ICAM-1, VCAM-1).
Main Results:
- PA SM exhibited significantly less lining layer hyperplasia and fewer macrophages compared to RA SM.
- A greater number of blood vessels were observed in PA SM.
- Endothelial leukocyte adhesion molecule 1 (ELAM-1) expression was less intense in PA SM, while intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) expression showed no difference.
- Numbers of B cells, T cells, and T cell subsets were similar in both groups.
Conclusions:
- PA synovial membranes are more vascularized with less intense ELAM-1 expression than RA synovial membranes.
- Fewer macrophages infiltrate the stroma and lining layer in PA compared to RA.
- Despite vascular and macrophage differences, lymphocytic infiltration of the synovial membrane is comparable between PA and RA.