[A histological study on the synovial tissue of rat knee joints in the experimental beta 2-microglobulin derived...

In recent years, a clinical syndrome comprising carpal tunnel syndrome, destructive spondylarthropathy, and cystic bone lesions has been recognized in the long-term hemodialysis patients. It is well known that the amyloid deposits have been found in these affected tissues and also beta 2-microglobulin (beta 2-MG) has been identified as an amyloidgenic protein. But, those problems such as the mechanisms of amyloidgenesis from beta 2-MG in vivo and the subchondral bone cysts formation are not clarified yet. If it becomes clear, it will give us a very useful information of therapeutic and prophylactic considerations to the hemodialysis related arthropathy. Since the experimental amyloidosis derived from beta 2-MG has not been reported in the past, we intended to make the experimental amyloidosis derived from beta 2-MG in rats. We have used the Sprague-Dawley strain rats (4 weeks old) and performed the 3 different procedures as follows. Procedure 1: clip renal vessels to make the experimental renal failure. Procedure 2: induce arthritis by the type II collagen induced arthritis (CIA). Procedure 3: inject beta 2-MG (10 micrograms) into the knee joint once every week for 6 weeks. We combined the above-mentioned procedures to make 5 experimental groups as follows. Group A: Procedure 1 + Procedure 3. Group B: Procedure 1 + Procedure 2. Group C: Procedure 1 + Procedure 2 + Procedure 3. Group D: Procedure 2 + Procedure 3. Group E: No treatment. After 6 weeks, they were sacrificed. We took specimens from the synovium and bone in their knee joints. First, the light microscopic specimens are stained with the Congo-red stain. When we confirmed the positive green birefringence in polarized light, we have performed the immunohistochemical stain with the monoclonal anti-amyloid P-component antibody, the anti-beta 2-MG antibody and the anti-amyloid A protein for the immunohistochemical stain subsequently. Moreover, we have used the electron microscope to confirm the amyloidfibrils in cases that the Congo-red and immunohistochemical stain of the amyloid P-component are both positive. As a result, we could confirm the amyloid fibrils in the 60% of the group C only. In this group, the amyloid deposition is observed in the inflammatory proliferated synovium in the joint as well as the subchondral bone lesion where the synovial capsule attaches to the bone. In other groups, although a certain degree of inflammation or proliferation of synovium as well as erosive changes of the joint surface are found, no amyloid deposition is confirmed.(ABSTRACT TRUNCATED AT 400 WORDS)