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Synovial membrane and fluid morphologic alterations in early rheumatoid arthritis: microvascular injury and
Abstract:
Eight patients have been studied during the first 6 weeks of rheumatoid synovitis. All of them exhibited microvascular injury, which was manifested by gaps between endothelial cells, vascular occlusion, erythrocyte extravasation, or endothelial cell injury. In four patients, a variety of virus-like particles were found associated with the endothelium or perivascular cells. In two cases, particles were seen in electron-dense deposits in vessel walls. Lymphocytes and PMN infiltrated the synovial membranes, but plasma cells were uncommon. Evidence of phagocytosis was prominent in synovial lining cells and other large mononuclear cells, but not in PMN. These observations are consistent with injury to synovium and, specifically, synovial vessels as an early stage in RA synovitis. The virus-like particles require further investigation, because nonviral cell components remain very difficult to distinguish in electron microscopy tissue sections.
Insights
Early rheumatoid synovitis involves microvascular injury and potential virus-like particles in the synovium. Further research is needed to confirm the nature of these particles in rheumatoid arthritis development.
Area of Science:
- Rheumatology
- Pathology
- Microbiology
Background:
- Rheumatoid synovitis is a complex inflammatory condition affecting the joints.
- Early pathological changes in rheumatoid arthritis (RA) are not fully understood.
- Microvascular alterations may play a crucial role in the initial stages of RA.
Purpose of the Study:
- To investigate the early microvascular and cellular changes in rheumatoid synovitis.
- To identify any potential infectious agents or unusual structures in early RA synovium.
- To correlate pathological findings with the early stages of rheumatoid arthritis.
Main Methods:
- Electron microscopy was used to examine synovial tissue from eight patients with early rheumatoid synovitis.
- Histopathological analysis focused on endothelial cells, vascular integrity, and cellular infiltration.
- Identification and characterization of virus-like particles were performed using electron microscopy.
Main Results:
- All eight patients showed evidence of microvascular injury, including endothelial gaps, vascular occlusion, and erythrocyte extravasation.
- Virus-like particles were observed in four patients, associated with endothelial or perivascular cells, and in vessel wall deposits in two cases.
- Synovial infiltration included lymphocytes and polymorphonuclear neutrophils (PMN), with prominent phagocytosis by synovial lining cells and mononuclear cells.
Conclusions:
- The findings suggest that microvascular injury is an early feature of rheumatoid synovitis.
- The presence of virus-like particles warrants further investigation to determine their role in RA pathogenesis.
- Distinguishing nonviral cellular components from actual viral particles remains a challenge in electron microscopy.