Light- and electron-microscopic studies of normal juvenile human synovium

Association of two functional polymorphisms in the CCR5 gene with juvenile rheumatoid arthritis

Juvenile rheumatoid arthritis (JRA) is mediated by Th1-immune responses. In children with JRA, synovial T cells express high levels of the Th1-chemokine receptor CC chemokine receptor 5 (CCR5), which has been implicated in susceptibility to rheumatoid arthritis. To test the hypothesis that genetic variation in CCR5 is associated with susceptibility to JRA, we analyzed patterns of variation in the 5'cis-regulatory region of CCR5 in 124 multiplex families from a JRA-affected sibpair registry. After sequencing the upstream region of CCR5, variants were tested for association with JRA by transmission disequilibrium testing. A single nucleotide polymorphism, C-1835T, was significantly undertransmitted to children with early-onset JRA (P<0.01). C-1835T was genotyped in 424 additional simplex and multiplex families. CCR5-1835T allele was undertransmitted in the cohort of all probands with JRA (P<0.02), as well as in those with early-onset (P<0.01) or pauciarticular JRA (P<0.05). Another variant, a 32-bp deletion in the open reading frame of CCR5 (CCR5-Delta32) was also tested in approximately 700 simplex and multiplex families. CCR5-Delta32 was also significantly undertransmitted to probands with early-onset JRA (P<0.05). Both variants are in regions under natural selection, and result in functional consequences. Our results suggest these CCR5 variants are protective against early-onset JRA.

Immunohistochemistry of normal human knee synovium: a quantitative study

OBJECTIVE

To describe the immunohistochemical characteristics of knee synovium from normal healthy subjects.

METHODS

12 healthy subjects underwent needle biopsy of knee synovium. Using antibodies directed against CD3, CD4, CD8, L26, Kp-1,and HLA-DR, detailed quantitative immunohistochemical analysis of various cell subpopulations was undertaken.

RESULTS

The mean (SD) age of the subjects was 37 (9) years (five male, seven female). All had a negative history for arthritis, no knee pain, and a totally normal joint examination except for the presence of retropatellar crepitus in five. For technical reasons staining for all immunohistochemical markers could not be achieved in all subjects. CD3+ T lymphocytes were seen in nine of 10 subjects, either diffusely or, more commonly, in perivascular areas. CD4+ cells were seen in synovium in three of seven subjects and CD8+ cells in six of eight subjects, in almost equal numbers (CD4:CD8, 1.1:1). L26+ B lymphocytes were not seen in any biopsy. Kp1+ macrophages were found in 10 of 10 subjects, predominantly in surface lining cells, and in small numbers in diffuse and perivascular locations. HLA-DR+ cells were seen in 10 of 10 subjects, predominantly in surface lining cells and diffusely, but a few were seen perivascularly.

CONCLUSIONS

Synovium from apparently normal subjects contained a wide range of different cell subpopulations but no B cells. The significance of these immune cells in normal synovium is unclear. A better understanding of their role in normal synovium may be important in analysing the transition to synovitis.

Cellular basis and oncogene expression of rheumatoid joint destruction

A new animal model for human rheumatoid arthritis is described, and the unsolved questions regarding the mechanism of primary joint destruction are discussed. Following an analysis of the types of cells and antibodies found in joints affected by rheumatoid arthritis, it is concluded that both expression of oncogenes and the presence of retroviral sequences detectable by monoclonal antibodies to HTLV I p19 and p24 sequences are associated with early abnormal proliferation of apparently transformed cells at the site of initial cartilage and/or bone destruction.

Intercellular adhesion molecule-1 (ICAM-1) is involved in the cytolytic T lymphocyte interaction with a human synovial cell line

The cell surface molecules involved in the human cytolytic T lymphocyte (CTL)-synovial cell interaction may play an important role in T cell interactions with connective tissue mesenchymal cells. To examine the molecular basis for the CTL-synovial cell interaction, we immortalized synovial cell explants to establish the cell line SYN.SPP. The SYN.SPP cell line was compared to the established B lymphoblastoid cell line JY. Cell surface immunofluorescence demonstrated significantly different levels of the immunologically relevant cell surface molecules ICAM-1 and LFA-3. Both cell lines were used to stimulate CTL precursors. After several months in culture, CTL lines stimulated by the SYN.SPP and JY cell lines demonstrated HLA class I-directed cytolytic activity. The cell surface molecules utilized by the anti-SYN.SPP and anti-JY CTL lines were identified by monoclonal antibody (MAb) inhibition. MAb recognizing the CTL cell surface molecules CD3, CD8 and LFA-1 (CD11a) significantly inhibited CTL-mediated lysis of both target cells. An interesting observation was that the anti-SYN.SPP CTL line appeared to utilize the ICAM-1 and not the LFA-3 target cell molecule. In contrast, the anti-JY CTL line utilized the LFA-3 and not the ICAM-1 membrane molecule. These results indicate that CTL interactions with connective tissue mesenchymal cells may be regulated by a unique pattern of antigen nonspecific cell-cell interaction molecules.

Ultrastructural localisation of muramidase in the human synovial membrane

The synovial intimal cell layer comprises two morphological types of cell, A and B, with an intermediate type also postulated. Type A cells show features in common with other cells of the mononuclear phagocyte system, while type B cells appear similar to fibroblasts and are assumed to have synthetic activity. Muramidase is a marker of mononuclear phagocytic cells, and we have investigated the synovial membrane for the presence of this enzyme in cells by an immunogold labelling technique. Muramidase was localised within intracytoplasmic vacuoles in subintimal macrophages and type A synoviocytes. This finding provides further evidence that type A cells are closely related to macrophages.

Quantitation of human synovial mast cells in rheumatoid arthritis and other rheumatic diseases

We examined sections of synovial membranes from 14 patients with rheumatoid arthritis (RA), 7 with other rheumatic diseases, and 10 with no apparent joint disease. Patients with RA and other rheumatic diseases had significantly more synovial mast cells/vessel than patients with no joint disease (0.49 and 0.20, respectively, versus 0.03). They also had significantly more total mast cells/10 fields than patients with no joint disease (9.9 and 5.0, respectively, versus 0.4). Within the rheumatoid group, patients with active disease had more total mast cells/10 fields than patients clinically considered to have end-stage disease (P less than 0.05). Synovial basophils were not identified in any patient. Synovial vascularity was similar for all groups (2.3 vessels/field). The role of the synovial mast cell in RA and other rheumatic diseases remains to be determined.

Ultrastructure of arthritis induced by a caprine retrovirus

The ultrastructure of early retrovirus-induced arthritis was studied sequentially in 20 goat kids inoculated with caprine arthritis-encephalitis virus. Synovial lesions began as intercellular edema and collagen fragmentation and continued as progressive mononuclear cell infiltration and lining cell hyperplasia, hypertrophy, and necrosis. At 18 through 45 days after the inoculation, lining cells contained small accumulations of virus-like particles similar to virus seen in infected tissue culture cells. No virus was seen budding from infected lining cell membranes.

Ultrastructure of human tendon sheath and synovium: implications for tumor histogenesis

Normal human tendon sheath and synovium were studied by scanning an transmission electron microscopy. The lining cells of the two tissues appear to be identical ultrastructurally. The most superficial cells (B-cells) possess long cytoplasmic extensions that clothe the membrane surface. Intermingled with deeper B-cells are the so-called A-cells, which have similar cytoplasmic features but lack long processes and instead have many filopodia. the frequent occurrence of intermediate forms indicates that the two cells form part of a morphologic spectrum. Comparison with cells of tumors that have been ascribed to synovium or tendon sheath (synovial sarcoma, epithelioid sarcoma, clear cell sarcoma) do not reveal any close similarities that might support a histogenetic relationship.

Tissue calcification and inflammation in osteoarthritis

Clinical evidence of inflammation and the presence of calcium phosphate crystals in the joint fluid are both characteristics frequently seen in osteoarthritic patients. However, the relevance of the crystal deposition to the pathogenesis of osteoarthritis remains unclear. In this study of 28 patients with advanced osteoarthritis the frequency and type of crystal deposition has been investigated and the relationship between tissue inflammation and crystal deposition has been explored. Tissue calcification, though present in all patients, is but one of several intra-articular inflammatory agents. Its relevance to inflammation in osteoarthritis is discussed.

Distribution of lysozyme in synovial tissue of patients with osteoarthritis and rheumatoid arthritis demonstrated by different enzyme histochemical methods

Lysozyme-producing cells were analysed by enzyme histochemistry in paraffin sections of synovial tissue of 60 patients with rheumatoid arthritis (RA) and 20 patients with osteoarthritis (OA). For lysozyme detection three enzyme histochemical systems - peroxidase-anti-peroxidase, alkaline phosphatase and biotin-avidin - were used in parallel experiments. Lysozyme was found to be produced by polymorphonuclear cells, mononuclear phagocytes and part of synovial lining cells. All types of lysozyme-producing cells were increased in RA compared with OA. Subgrouping of RA synovitis according to histomorphological criteria allowed the demonstration of an inverse relationship between the number of lysozyme-producing cells and the grade of proliferation of fibroblasts, called mesenchymoid transformation by Fassbender [19]. The different methods of lysozyme detection differed in specificity and sensitivity. The immunoenzymatic staining of lysozyme allows specific and quantitative evaluation of phagocytizing cells in RA and OA.