Electron microscopic observations on the rheumatoid synovial membrane

Ultrastructure of the Synovial Membrane in Seronegative Inflammatory Arthropathies

The ultrastructure of the synovial membrane has been studied in 6 patients with seronegative inflammatory arthropathies: Reiter's (2), Crohn's (2), Whipple's (1) and Behcet's disease (1). The most striking changes were found in the synovial B cells, many containing abnormally large mitochondria with altered cristae surrounded by fibrillar material. Similar material was present in dilated endoplasmic reticulum which was the probable source of groups of extracellular fibrillar spheroidal bodies. The B cells also contained electron dense granular lysosomes of very variable size which, in common with the abnormal mitochondria, were often associated with bundles of orientated microfilaments and large golgi complexes. Light microscopy of the synovial membrane was consistent with an inflammatory arthritis, as were the high white cell counts in the synovial fluid. Systemic activity in the patients was indicated by raised ESR and C-reactive protein (CRP).

A case of rheumatoid arthritis with unilateral knee synovial hypertrophy in hemiplegia

A 64-year-old woman suffering right hemiplegia came in with pain and swelling on her left knee, general weakness and poor oral intake for 2 months. On physical examination we were able to palpate a mass with irregular margin around the left suprapatellar area. From the results of the magnetic resonance imaging (MRI), synovial proliferative disease, infectious arthritis, or gouty arthritis was suspected. We performed a blood laboratory test to detect rheumatologic diseases, knee joint aspiration, and bone scan for differential diagnosis, and were able to diagnose rheumatoid arthritis (RA) from the results of blood laboratory, physical examination, and bone scan. Consequently, we started medications for controlling RA. Herein, we report a case of rheumatoid arthritis with unilateral knee synovial hypertrophy in hemiplegia. If a right hemiplegic patient has recurrent pain on the left knee and synovial hypertrophy, and fails to respond to treatment for osteoarthritis, early detection by evaluation for rheumatic disease is crucial to prevent severe sequelae influencing rehabilitation of hemiplegia.

Use of differential subtraction method to identify genes that characterize the phenotype of cultured rheumatoid arthritis synoviocytes

OBJECTIVE

To identify the genes that characterize the distinctive phenotype of cultured rheumatoid arthritis (RA) fibroblastoid synoviocytes.

METHODS

A representational difference method was used to subtract complementary DNA (cDNA) from cultured RA fibroblastoid synoviocytes with cDNA from noninflammatory osteoarthritis synoviocytes. The genes were identified by DNA sequencing, and their relative expression was determined by Northern blot analysis.

RESULTS

Twenty-four genes were identified, including novel genes such as a human homolog of mouse semaphorin E and one homologous to N-acetylglucosamine-6-sulfatase. Eleven of these genes were constitutively overexpressed in the rheumatoid synoviocyte line, including a chemokine, stromal cell-derived factor 1, and several genes capable of mediating synoviocyte-leukocyte interactions, including vascular cell adhesion molecule 1 and Mac-2 binding protein. Three genes (lumican, biglycan, and insulin-like growth factor binding protein 5) encoded extracellular matrix components, suggesting that distinct stromal-synoviocyte interactions may be mediated by this phenotype. Two interferon-inducible genes of unknown function were also found, emphasizing the presence of activation-like features in the phenotype.

CONCLUSION

A general method for the identification of differences in patterns of gene expression revealed that cultured RA fibroblastoid synoviocytes overexpress certain proinflammatory genes that are potentially relevant to lymphocyte and monocyte entry and interactions. The features of the genes identified in these mesenchymal cells suggest that they facilitate localization of immune reactions to the joint through leukocyte chemokinesis, cell-cell adhesion, and matrix specialization. The further characterization of these genes should help in resolving whether this phenotype is the consequence of modulation and imprinting by an inflammatory milieu or, more likely, whether it reflects the intrinsic lineage characteristics of intimal lining synoviocytes.

Taxol involution of collagen-induced arthritis: ultrastructural correlation with the inhibition of synovitis and neovascularization

Collagen-induced arthritis (CIA) is an animal model of rheumatoid arthritis (RA) that can be regressed with Taxol (paclitaxel), a chemotherapeutic agent. To identify structural changes that occur with involution, the synovium from naive, untreated CIA, and Taxol-treated CIA rats were evaluated by light microscopy plus transmission and scanning electron microscopy. Analysis included detailed images of vascular networks using polymeric corrosion casts. The CIA synovium was morphologically similar to human RA synovium. In CIA, the integrity of the intimal lining is lost by Type-B synoviocytes becoming highly elongated and polarized toward the joint space, resulting in non-overlapping cellular processes and the elimination of the basal lamina. In addition, the lining expanded from a width of 6-10 microns in naives to 200-250 microns in CIA due primarily to increased numbers of both Type-A and -B synoviocytes and more interstitial matrix. Vascular corrosion casts of CIA synovium illustrated a marked increase in blood vessel volume and an extensive interconnecting vascular architecture; neovascular arrays were observed to project toward the synovial surface. In Taxol-treated CIA, the synoviocyte and neovascular components reverted to the naive synovium morphology, suggesting that this agent might be useful in the therapy of RA.

The synovial lining of the rabbit knee: a scanning electron microscopy study of specimens reinforced structurally with tannic acid

Medial and lateral synovial linings of the rabbit knee, structurally reinforced with tannic acid during fixation, were studied in the scanning electron microscope. Low-resolution micrographs revealed, in both linings, gross architecture of four types: accordion-like, lobe-like, fatty areolar, and flattened areas. In high resolution, both cellular and acellular surfaces were recorded. A novel, 'bubble-like' appearance, of unknown nature and origin, accounted for 70% of both linings. No definite correlation between anatomical location, gross type, or microarchitectural pattern was noted.

The role of chemical mediators in the pathogenesis of inflammation with emphasis on the kinin system

In recent years, numerous agents have been recognized as inflammatory mediators. In this review, however, we discuss only those having direct relevance to human inflammatory diseases These mediators are clinically important due to their proinflammatory properties such as vasodilatation, increased vascular permeability, pain and chemotaxis. They may lead to the fifth cardinal sign, loss of function in inflammatory diseases. Agonists and non-specific antagonists are used as pharmacological tools to investigate the inflammatory role of PGs, LTs, PAF, IL-1, histamine, complement, SP, PMN-leukocytes, and kallikrein-kininogen-kinin systems. Unfortunately, no compound is known which concurrently abolishes all actions and interactions of inflammatory mediators. Therefore it would be highly useful to promote efforts in developing selective and competitive antagonists against proinflammatory actions of these chemical mediators. This may help to a better understanding of the pathogenesis of inflammatory reactions, and it may also be useful for the therapy of inflammatory diseases.

Human epidermal growth factor for the stratification of synovial lining layer and neovascularisation in rheumatoid arthritis

Immunohistochemical study showed selective localisation of human epidermal growth factor (hEGF) to the synovial lining layer. Although the synovial lining layer of the rheumatoid, osteoarthritic, and traumatic joints was hEGF positive, hEGF staining was especially dense at the rheumatoid synovial lining layer; the staining increasing linearly according to the degree of stratification of the lining layer (r = 1). Human epidermal growth factor was ultrastructurally localised to cytoplasm, especially to rough endoplasmic reticulum, of the synovial lining fibroblast-like (type B) cell. Only the cell surface of macrophage-like (type A) cells was hEGF positive. When different histological variables were compared with each other a positive correlation was found between hEGF staining of the synovial lining layer and the degree of neovascularisation of rheumatoid synovium (r = 0.72). Although some lymphocytes were weakly hEGF positive, neovascularisation did not correlate with the extent of lymphocyte infiltration or of hEGF staining of lymphocytes. Lymphocyte infiltration or hEGF staining of lymphocytes did not correlate with hEGF staining of the synovial lining layer, whereas the lymphocyte infiltration correlated positively with the extent of perivascular accumulation of lymphocytes (r = 0.89). These findings suggest that (a) hEGF is synthesised by and secreted through endoplasmic reticulum and Golgi apparatus from the synovial lining type B cell; (b) hEGF is at least partially responsible for the pathogenesis of stratification of the rheumatoid synovial lining layer, and perhaps of neovascularisation of the rheumatoid synovium, whereas it is not responsible for lymphocyte accumulation to the rheumatoid synovium.

Light and electron microscopic studies on the synovial membrane in Reiter's syndrome. Immunocytochemical identification of chlamydial antigen in patients with early disease

Studies by light microscopy on synovium obtained from 11 patients with Reiter's syndrome during the first month of an episode showed proliferation of synovial lining cells, polymorphonuclear neutrophils among the synovial lining cells, increased surface fibrin, and vascular congestion. Biopsy specimens taken later showed vascular congestion and still proliferated synovial lining cells, fewer polymorphonuclear neutrophils in some, and a tendency toward increased infiltration with lymphocytes and plasma cells. Electron microscopy of samples from 8 patients during the first month of disease activity showed occlusion of vessels by platelets in 4, and fibrin or dense granular material in the vessel walls in 4. Five of the patients with arthritis of less than 4 weeks duration had unidentified intracellular and extracellular particles; some of these were highly suggestive of Chlamydia. No such particles were noted in samples from patients with more chronic cases. Using an antibody to Chlamydia trachomatis and the peroxidase-antiperoxidase technique, immunocytochemistry showed reaction product in synovial macrophages in 2 patients with arthritis of less than 4 weeks duration, but not in the 1 patient studied who had more chronic disease. These studies provide support for dramatic synovial vascular injury consistent with that caused by endotoxin and the presence of chlamydial antigen in synovial macrophages, at least in the early phases of synovitis.

Autoantibodies from rheumatoid arthritis patients recognize antigens on the synoviocyte surface

We have found autoantibodies in the sera from rheumatoid arthritis (RA) patients which recognize two cell surface antigens of approximately 70 kDa and 28 kDa from synoviocyte extracts as detected by immunoprecipitation analysis. These polypeptides were immunoprecipitated from extracts containing mainly macrophage-like synoviocytes (type A) but not from extracts of homogeneous fibroblast-like synoviocytes (type B). These autoantigens are not selectively expressed by RA synoviocytes, since both RA and non-rheumatoid synovia were reactive for RA sera. From the panel of different RA sera tested, 64% immunoprecipitated the 70 kDa band, and 27% recognized the 28 kDa polypeptide. These differences in the specificity of the sera seemed to be related to the clinical state of the donor. The sera from patients suffering from other autoimmune diseases such as autoimmune thyroiditis and systemic lupus erythematosus (SLE) do not appear to be reactive for these specificities, but sera from patients with Sjögren's syndrome, psoriatic arthritis, and Crohn's disease showed a weak cross-reactivity with the 70 kDa polypeptide. This autoreactivity against synovial cells in RA supports the idea that these cells participate in the initial immune response of the disease.

Oxygen free radicals denature human IgG and increase its reactivity with rheumatoid factor antibody

Rheumatoid inflammation is characterised by the production of rheumatoid factor antibodies directed against denatured IgG. Oxygen free radicals have the potential to denature all manner of proteins and can be generated by activated phagocytic cells in the inflamed joint. By modifying routine ELISA and nephelometric procedures for measuring rheumatoid factor, (i.e. substituting free radical altered IgG for rabbit and heat aggregated IgG as antigens) we have observed that oxygen radicals, generated by (1) UV light and (2) PMA-activated neutrophils, give rise to monomeric and polymeric forms of IgG which have increased reactivity towards IgM and IgA polyclonal rheumatoid factor antibodies. We conclude that free radical alteration of IgG may be a stimulus to the formation of immune complexes with rheumatoid factor antibody, thereby promoting and amplifying tissue damage during rheumatoid inflammation.

A review of the histopathological evidence on the pathogenesis of cartilage destruction in rheumatoid arthritis

These are three ways of cartilage destruction as summarized in Fig. 1. The relative significance of the contribution among them to the pathogenesis of cartilage destruction varies individually. It appears important here to note that chondrocytes themselves are not actively involved in the pannus formation. Chondrocytes only provide a basis for extension of the pannus by proteolytic digestion of cartilage matrix. It is however possible in some individuals that the digestion of cartilage by chondrocytes plays the predominant role in their cartilage destruction. Besides the autonomous proliferative potential of pannus tissue, it seems evident that active synovitis is the main cause of cartilage loss. This is quite important from the therapeutic view point, because we can expect to halt the disease process causing joint deformities by controlling the active synovitis.

On the presence of rheumatoid factor in joints before and after synovectomy

The presence of rheumatoid factor in synovial fluid has been investigated before and after synovectomy. The sensitized sheep cell test (SSC) and acryl fixation test were used. Fourteen patients representing 18 knee joints in which synovectomy was performed, showed the same immunologic conditions in the synovial fluid before and after the surgical procedure. The relationship between the presence of immunoglobulins and certain structural features in the synovial tissue is discussed.

Functional role in self reactivity for Ia antigens on murine synovial cells

Cultures of synovial cells from normal CBA mice were established after collagenase treatment of synovial tissue collected from the knee joint. Morphological studies using light and electron microscopy have shown that confluent monolayers are composed of 90% triangular or stellate dendritic cells with numerous microvilli and 5% secreting cells containing many dense granules. Less than 5% contaminating cells, such as fibroblasts or macrophages, are present. The class I and class II antigens of the major histocompatibility complex, detected by indirect immunofluorescence or complement-dependent cytotoxicity, are expressed on the cell surface of normal CBA synovial monolayers. Functional Ia antigens borne by synoviocytes are evidenced by the proliferative responses they elicit from syngeneic (or allogeneic) spleen cells after a 3-day co-culture. Similarly, monolayers of Ia+ synovial cells were obtained from both MRL/lpr mice, which spontaneously develop an autoimmune syndrome, and the control MRL/n mice. Spleen cells from young MRL/lpr exhibited significantly higher levels of blastogenesis in syngeneic co-cultures than those from MRL/n mice. Conversely, with advancing age the syngeneic proliferative responses declined minimally for MRL/lpr mice and were unchanged for MRL/n mice. These findings suggest that Ia+ synovial cells can effectively interact with syngeneic lymphocytes and may initiate autoimmune reactivity.

Electron microscopic study of HLA-DR and monocyte/macrophage staining cells in the rheumatoid synovial membrane

We examined synovial membrane samples from 6 rheumatoid arthritis (RA) and 3 osteoarthritis patients and from 1 normal subject, by an immunoelectron microscopic technique using anti-HLA-DR (anti-Ia) and anti-monocyte/macrophage (63D3) monoclonal antibodies. In the lining layer, the type A macrophage-like cells were strongly DR+ and 63D3+, whereas the type B fibroblast-like cells were almost completely negative. Lymphocyte-rich areas (containing more than 90% densely packed lymphocytes) showed weak and patchy DR staining of the lymphocytes. In these areas, 3-5% of the cells were macrophage-like cells which were 63D3-, a type of staining compatible with that of the interdigitating cell (IDC). In the plasma cell-containing (transitional) areas, many strongly DR+ macrophage-like cells were observed in close contact with lymphocytes and plasma cells. Ten to twenty percent of these cells were 63D3-, which suggests that they were IDC. Cells with the structural appearance of IDC were most frequently seen in those transitional areas which contained elevated concentrations (50-70%) of lymphocytes. In uninfiltrated interstitial areas, approximately 50% of the cells stained strongly with both anti-DR and 63D3 antibody, indicating that they were cells of monocyte/macrophage lineage, presumably histiocytes. This investigation has demonstrated the presence of the DR antigen in the RA synovial membrane on 1) phagocytic cells of the lining area, 2) lymphocytes and small numbers of IDC-like cells in dense, lymphocyte-rich areas, 3) large numbers of macrophage-like cells, of which some had the morphologic appearance of IDC, in transitional or plasma cell-containing areas, and 4) histiocytic cells in uninfiltrated interstitial areas. The observation of large numbers of DR+ macrophages and IDC-like cells in close contact with lymphocytes and plasma cells in the RA synovial membrane emphasizes their role in an active immune response. The observation of substantial numbers of potentially immunocompetent, DR+ histiocytic cells in uninfiltrated regions of the synovial membrane suggests that such cells may play a role in the progression of the synovial inflammatory reaction.

Relationship between iron deposits and tissue damage in the synovium: an ultrastructural study

A detailed ultrastructural study was made of the synovial iron deposits in cases of haemophilic synovitis (HS), pigmented villonodular synovitis (PVNS), rheumatoid arthritis (RA), osteoarthritis (OA), seronegative inflammatory arthritis (SNA), and in controls, to investigate the relationship between iron deposits and tissue damage. Iron was seen by electron microscopy in about 75% of synovial lining cells in HS and PVNS but only in about 25% of synovial cells from cases of RA and SNA. In cases of OA and in controls iron deposits were scarce. The iron was usually deposited within pleomorphic siderosomes and in HS was most common in type A synovial cells. In contrast, deposits in all other cases were more common in type B cells, which were frequently the predominant cell type, and siderosomes were smaller, more homogeneous, and were more common in deeper synovial tissue. Considerable tissue damage was noted in the vicinity of iron rich siderosomes in synovial A cells from cases of HS, but such deposits in B cells in the synovium from the other cases had relatively little effect. We discuss the possibility that such differences directly reflect the differing functions of type A and B synovial cells, and particularly their relative ability to produce metabolically active oxygen metabolites with tissue destructive potential in the presence of iron.

Effect of blood on the activity and persistence of antigen induced inflammation in the rat air pouch

The hypothesis that haem iron derived from synovial microbleeding has a proinflammatory effect on the synovial membrane was tested by adding autologous whole blood and fractions derived from it to a naturally remitting rat air pouch model of allergic inflammation. The induction of such a subcutaneous air pouch produces a cavity lined by mesenchymal cells comparable to the synovial membrane. Autologous whole blood was found to prolong a low grade inflammatory state, this effect being attributable to a red cell component, most probably haem iron. Whole blood in the absence of an inflammatory stimulus does not have this effect, indicating that the mechanism is one of prolonging or promoting existing allergic inflammation, rather than inducing an inflammatory response.

Synovial fluid lactate levels in septic and non-septic arthritides

Lactate concentration was studied in 383 synovial fluid specimens from patients with various arthritides. The highest concentrations of lactate occurred in non-gonococcal septic synovial fluids. High values were recorded in seropositive rheumatoid arthritis and crystal-induced arthritides, medium values in synovial fluids from seronegative rheumatoid arthritis, seronegative spondylarthritides, gonococcal arthritis and haemarthrosis, and the lowest values in aspirates from osteoarthrotic joints. There was a positive correlation between synovial pH and lactic acid concentration. These data suggest that determination of lactate in synovial fluid can be valuable in the rapid exclusion of septic arthritis. Its value for differentiating between other inflammatory arthritides is discussed.

The nature of iron deposits in haemophilic synovitis. An immunohistochemical, ultrastructural and X-ray microanalytical study

Using a computerized electron-probe X-ray microanalytical technique to measure phosphorus/iron ratios we have defined the iron saturation of ferritin in vitro from prepared ferritin standards of known iron loading. This technique has been applied to the study of 5 haemophilic synovial membranes. At light microscope level the distribution and relationship of iron/ferritin were defined using Perls' reaction and an immunoperoxidase technique respectively. The synovia from all cases contained intra and extra-cellular deposits of Perls' positive material which were granular in nature in the most superficial synovial cells. There were increasing numbers of pheomorphic (1-12 micron diameter ovate bodies in the deeper synovial layers. Immunoperoxidase ferritin staining produced a strongly positive reaction in the granular material but the ovate bodies were negative with the exception of some peripheral staining. X-ray microanalysis showed the granular material to be highly iron saturated ferritin and the ovate bodies to be almost pure iron. We suggest that iron saturated ferritin in the synovial membrane could increase/perpetuate inflammation by promoting lipid peroxidation.

Gold levels produced by treatment with auranofin and sodium aurothiomalate

Sixty-three patients with rheumatoid arthritis were randomly divided into 3 groups, and treated with either sodium aurothiomalate (Myocrisin), auranofin, or placebo. Gold levels in whole blood, plasma, and haemolysate were measured serially along with clinical and laboratory parameters of efficacy. Auranofin produced a higher ratio of haemolysate to plasma gold than Myocrisin, and it appears that the affinity of the red cell for gold is reduced during therapy with auranofin. Gold levels did not correlate with changes in the pain score, erythrocyte sedimentation rate, and C-reactive protein, nor with the development of toxicity. In the Myocrisin group the haemolysate gold level achieved was dependent on the number of cigarettes smoked. In the auranofin group there was no such correlation, but the haemolysate gold level was higher for smokers than non-smokers. The likely action of gold is discussed.

Relationship of angiogenesis factor in synovial fluid to various joint diseases

A low-molecular-weight freely dialysable angiogenesis factor has been isolated from 49 synovial fluids obtained from patients with various joint diseases. An analysis of disease type and incidence of freely dialysable angiogenesis activity showed that the osteoarthrotic group had a significantly higher incidence than all the other groups (p = 0.0332). Angiogenesis factor has also been detected in a bound form in the retentates of fluids which gave positive results for dialysable factor. The possibility that an imbalance between carrier-bound and free factor may have a causative role in disease is discussed.

Fibrin and fibronectin in rheumatoid synovial membrane and rheumatoid synovial fluid

Normal synovial membranes and synovial membranes from patients with classic rheumatoid arthritis were investigated for the presence of fibrin and fibronectin by an indirect immunoperoxidase technique. In normal synovial membranes, fibronectin was found around the monolayer of the synovial lining cells. Staining was most intense on the surface and beneath the lining cells, but not detectable in the cytoplasm. Fibronectin was also found in the cytoplasm of the endothelial cells. No staining for fibrin was found in the normal synovial membrane. In synovial membranes from patients with rheumatoid arthritis, large amounts of fibronectin were found around the multilayer of synovial lining cells, in the cytoplasm of the endothelial cells, and in argyrophilic fiber-rich connective tissue. In superficial areas denuded of synovial lining cells, high amounts of fibronectin were found incorporated in fibrin. In some areas with noninjured synovial lining cells, fibrin was also found, but in this case no fibronectin was incorporated. No fibronectin was found in connective tissue in areas with infiltration of inflammatory cells. After treatment of normal and rheumatoid synovial membranes with hyaluronidase, fibronectin was still present around the lining cells but the staining was found to be more distinct. This study relates the presence of fibrin and fibronectin in the rheumatoid synovial membrane to the high amount of these proteins, recently described, in rheumatoid synovial fluid. It also suggests that fibronectin present in the synovial membrane is produced and secreted by the endothelial cells.

Morphologic observations in the early phase of the cartilage-pannus junction. Light and electron microscopic studies of active cellular pannus

The early phase of cartilage destruction by active cellular pannus in rheumatoid joints was observed under light and electron microscopy. In the early phase of pannus formation, cartilage was covered by several layers of fibroblast-like cells. This was also the case at the advancing edge of the pannus. Invasion of the cartilage by macrophage-like cells has been observed to start beneath this layer. Observations under electron microscope demonstrated that the main cells participating in the cartilage destruction at the cartilage-pannus junction were either fibroblast-like or macrophage-like cells, and suggested the possibility that these two types of cells were derived from synovial type A and type B cells. Morphologic observations also suggested a possibility of transformation of the fibroblast-like cell into the macrophage-like cell at the cartilage-pannus junction.

Identification of three major synovial lining cell populations by monoclonal antibodies directed to Ia antigens and antigens associated with monocytes/macrophages and fibroblasts

Synovial lining cells obtained from patients with rheumatoid arthritis or non-inflammatory joint diseases were divisible into three populations according to the expression of surface antigens detected by various monoclonal antibodies. A population of cells designated type I was defined by the presence of Ia antigens. Fc receptors, five different monocyte lineage differentiation antigens, and the property of phagocytosis. The greatly increased amounts of both Ia antigens and certain monocyte lineage antigens distinguished these cells from blood monocytes. A second distinctive cell population was non-phagocytic, occasionally binucleate, and had abundant Ia antigens but lacked IgG Fc receptors, monocyte lineage antigens, B or T lymphocyte antigens, and fibroblast-associated antigens detected by reagents raised against synovial cells. This population, designated type II, accounted for approximately one-third of the synovial cells in patients with rheumatoid arthritis but few or no cells in the synovial lining of patients with non-inflammatory diseases. The Ia-positive synovial cells with a dendritic morphology were contained in this population. An additional population, designated type III, contained nearly all of the remaining cells and was defined by the presence of antigens expressed primarily on fibroblasts and by the absence of phagocytosis, demonstrable Ia antigens, and four antigens of the monocyte lineage. This population exhibited proliferative capacity, becoming the predominant cell in long-term cultures. The proportions of each population varied considerably from patient to patient.

Ultrastructure of synovial changes in rheumatoid disease and in seronegative inflammatory arthropathies

Synovial tissue has been examined by electron microscopy from patients suffering from either sero-positive or sero-negative inflammatory arthropathies to allow direct comparison of the ultrastructural changes found in these groups and to confirm and extend observations previously made in a smaller group of sero-negative arthropathies. Both groups have been compared with material from healthy controls. The sero-positive group comprised 13 cases of 'definite' or 'classical' rheumatoid arthritis. The sero-negative group consisted of 9 cases of arthritis secondary to Crohn's disease (3); Reiter's syndrome (2); Whipple's disease (1); Behcet's disease (1); Wegener's granulomatosis (1) and ankylosing spondylitis (1). The control tissue was obtained from 6 non-arthritic subjects undergoing surgery for non-inflammatory conditions. Confirmation was obtained of changes previously reported in subcellular organelles, especially in synovial B cells, in all forms of inflammatory arthritis as compared with controls. Attention is now drawn to other intracellular changes in B cells and intermediate cells which included: a marked increase of intermediate filaments and microfilaments: and proliferation of pinocytotic vesicles and rough endoplasmic reticulum. These changes were often accompanied by the presence, in the immediate environment of these cells, of extracellular microfibrillary masses but little or no accumulation of intermediate filaments. It was confirmed that synovial A cells were reduced in number but showed changes suggestive of increased phagocytic activity and also exhibited proliferation of cytoskeletal elements. Differences in these structural changes between sero-positive and sero-negative arthritis were of degree rather than of kind and no 'specific' or diagnostic differences were observed between the various forms of seronegative athropathies. The possible significance of the structural changes observed is discussed.

The tissue architecture of synovial membranes in inflammatory and non-inflammatory joint diseases. I. The localization of the major synovial cell populations as detected by monoclonal reagents directed towards Ia and monocyte-macrophage antigens

Utilizing monoclonal reagents directed towards antigens of the monocyte-macrophage lineage and Ia antigens, the tissue architecture of synovial membranes obtained from patients with non-inflammatory joint diseases and patients with rheumatoid arthritis was studied. Emphasis was placed on the localization of the type I, type II and type III synoviocytes that previously had been defined by their cell surface phenotype with regard to the expression of monocyte-macrophage lineage (M theta) and Ia antigens as well as by their phagocytic capacity or the ability to produce glycosaminoglycans. In patients with non-inflammatory joint diseases, cells with the M theta + Ia+ (type I) phenotype constituted the majority of synoviocytes immediately adjacent to the joint cavity; cells with this phenotype were also scattered in the subsynovial tissue and in the perivascular regions. The fibroblastoid type III cells defined by the absence of both M theta and Ia antigens formed the major cell population in the subsynovial tissue in this patient group. In patients with rheumatoid arthritis, the Ia+ M theta + cells were present in a characteristic double configuration forming an intensely positive layer adjacent to the intra-articular space followed by an Ia- M theta - layer that again was succeeded by an intensely Ia+ M theta + layer. Large numbers of synoviocytes bearing M theta + Ia+ antigens were also demonstrated in the diffusely inflamed subsynovial tissue, in the perivascular regions as well as around and within lymphoid infiltrates.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of in vivo administration of gold sodium thiomalate on rat macrophage function

It has been shown that gold accumulates in macrophages. In vitro studies have also shown that long-term anti-inflammatory and immuno-regulatory effects on these cells may be responsible for the effectiveness of gold in the treatment of rheumatoid arthritis. However, the relevance of this information to the in vivo circumstance is largely untested. In this study, the effect of gold sodium thiomalate (AuTM) on rat alveolar macrophage (AM) lysosomal enzymes, bacterial killing, and metabolic activities associated with phagocytosis were assessed after in vivo administration. The activities of beta-glucuronidase, acid phosphatase, and lysozyme were inhibited 1 day following a single AuTM injection (50 mg/kg, subcutaneous). However, lysozyme returned to normal, while the activities of beta-glucuronidase and acid phosphatase were elevated from 4 to 12 days thereafter. When AuTM was administered weekly for 8 weeks, the activities of acid phosphatase and beta-glucuronidase were elevated throughout, while lysozyme was largely unaffected. The increased lysosomal enzyme activities were not due to contamination of polymorphonuclear leukocytes. These long-term effects of AuTm on enzyme activity were in marked contrast to its in vitro effect which inhibited the activities of beta-glucuronidase and acid phosphatase. No effect of AuTM administration on the release of beta-glucuronidase upon phagocytosis of opsonized zymosan was observed. At 1 day following a single AuTM injection or 3 days after a second weekly injection, in vivo bactericidal activity of AM toward S. aureus was diminished. This bacterial killing defect was not due to decrease phagocytosis; the in vivo binding and ingestion of bacteria were normal. The defect correlated with imparied metabolic activities associated with phagocytosis, namely a significant decrease in the reduction of nitroblue tetrazolium and the stimulation of the hexose monophosphate shunt. This may be an attractive anti-inflammatory effect in light of the destructive potential of the reactive oxygen species produced by macrophages in an arthritic circumstance.

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.

Vascular changes in psoriatic synovium. A light and electron microscopic study

Light and electron microscopic studies were performed on the synovial membranes from the large joints of 12 patients with psoriatic arthritis. The most significant histopathologic findings were vascular changes that were characterized by endothelial cell swelling accompanied by inflammatory cell infiltration and marked thickening of the vessel wall. Fibrosis of the subsynoviocyte tissue was also prominent, especially in patients with chronic disease. Villi were not prominent, and the lining layer was not thickened. Both type A and B cells were seen; none had significant abnormalities. No electrondense deposits were observed. These findings lend further support to the theory that microvascular changes play a significant role in the pathogenesis of psoriasis and its related arthritis.

Protein synthesis in rheumatoid synovial tissue

1. Function of synoviocytes and other cells in the synovium A. Histologic Considerations 1. Electron microscopic studies 2. In vivo and in vitro phagocytosis studies 3. Fluorescent antibody staining B. Culture techniques 1. Problems posed by study of isolated cells 2. Long-term explant cultures 3. Advantages of short-term incubations of synovial fragments 4. Isolation of immunoglobulins C. Non-Immunoglobulin Products of the Synovium 1. Products of normal synovium 2. Alterations induced by rheumatoid arthritis II. The Local Immune response in Rheumatoid Synovitis A. Evidence for Active Immune Stimulation 1. Meditators of cellular immunity in synovial fluid 2. Effect of synovectomy 3. Type and amount of immunoglobulin produced B. Local Commitment of Antibody Response 1. Effect of exogenous immunization 2. Rheumatoid factors. 3. Pepsin agglutinators C. 1. Relative enrichment for IgG-3 subclass 2. Increase in lambda-light chain composition III. Pathogenetic Considerations in Rheumatoid Arthritis A. Comparison of Rheumatoid versus Experimental Immune Synovitis 1. Chronic synovitis as a local immune response. 2. Role of cartilage complexes in substaining chronic synovitis B. Significance of the Restriction in the Immunoglobulin Response in Rheumatoid Arthritis 1. Analogy with other disease states in man 2. Common antigen in RA?

Studies of serum immunoglobulin binding to synovial fibroblast cell cultures from patients with rheumatoid arthritis

Using a sensitive 125I-protein A (PrA) binding assay to detect cell surface IgG, we have studied seven different synovial fibroblast cell cultures from patients with rheumatoid arthritis (RA). When these cultures were incubated in the presence of serum from 18 autologous and allogeneic RA patients (all seropositive), we were unable to detect significant IgG binding. Since IgM rheumatoid factor (RF) can block PrA binding, sera were absorbed with aggregated IgG to remove RF without affecting the results. Similar studies on three cell lines with seven rheumatoid sera were performed by antibody-dependent cell-mediated cytotoxicity. No significant cytotoxicity was observed. Since antibodies to collagen are present in rheumatoid sera, several cultures were incubated with ascorbic acid (12.5 microgram/ml) to optimize synthesis of cell surface collagen. These culture conditions did not affect serum immunoglobulin binding by the 125I-PrA assay. Thus, we can find no evidence for a direct humoral immune mediation of synovial proliferation in rheumatoid arthritis. These data do not support the hypothesis that the inflammatory process within the synovium of RA patients is an immunologic response to a fibroblast-associated antigen in the synovial membrane.

Evidence for the presence of receptors for C3 and IgG Fc on human synovial cells

The presence of receptors for IgG Fc and fragments of C3 on primary cultures and cryostat sections of normal and rheumatoid synovial tissues was assessed. Significant proportions of large rounded cells with asteroid projections found in such cultures had receptors for both IgG Fc and fragments of C3. Moreover, Gram negative bacteria that had fixed complement, but not EAC, bound in a linear fashion on the superficial layers of synovial cryostat sections. On the basis of morphologic and histochemical criteria, the cultured cells bearing these receptors were tentatively determined to represent a subset of synovial lining cells. The possible role of such receptors on synovial lining cells in the pathogenesis of rheumatoid arthritis is discussed.

Cellular junctions in normal and inflammatory human synovial membrane revealed by tannic acid and freeze fracture

Cellular junctions between synovial cells and endothelial cells of the microvasculature were examined in 10 normal and 20 inflammatory human synovial membranes by means of tannic acid and freeze fracture, Gap junctions and desmosomes predominated on synovial cells, and tight junctions in the microvasculature. Comparison between normal and inflammatory synovial membranes did not demonstrate changes in cellular contacts that might be caused by inflammation.

Ultrastructural localization and in situ analysis of iron, bismuth, and gold inclusions

The purpose of this article is to review ultrastructural and electron probe X-ray analytical studies on metallic deposits in cells. The metals that will be dealt with are iron, bismuth, and gold, mainly because they have been extensively studied in recent years. The nature and chemical composition of endogenously (e.g., from breakdown of autologous blood) and exogenously (e.g., after a transfusion or injection of iron compounds) produced hemosiderin (i.e., iron deposits) has been the subject of time-hallowed controversies. Quite a few of these have now been resolved by ultrastructural studies and the atomic composition of such deposits has been determined by electron probe X-ray analysis. The interest in bismuth centers around the fact that this is one of the two metals (the other being lead) that produces quite large intranuclear inclusions. Here again much has been learned by ultrastructural and X-ray analytical studies. The interest in gold stems from the fact that soluble salts of this metal are used for the treatment of rheumatoid arthritis and current studies with the above-mentioned techniques indicates how gold produces its beneficial and toxic effects.

Ultrastructure of the skin of patients treated with sodium aurothiomalate

Skin biopsies from cases of rheumatoid arthritis treated with sodium aurothiomalate were examined with the electron microscope. Intralysosomal gold deposits were found in the macrophages of both normal-looking skin and from areas of erythematous rash that had developed as a toxic manifestation of gold therapy. The main difference between affected and normal-looking skin was the presence of numerous mast cells in the former. It is hence suggested that the dermatologic side-effects of gold are probably mediated by the release of vasoactive substances from mast cells and that vigorous administration of antihistamines to neutralise the liberated products of mast cells or an agent that interferes with degranulation of mast cells might have a palliative effect on the skin rash that sometimes develops during chrysotherapy.

Aurosomes produced in the synovial membrane by the oral administration of a gold compound SK & F 36914

Chlorotriethylphosphine gold (SK & F 36914) administered orally to rabbits produced aurosomes in the synovial membrane. These aurosomes were similar to aurosomes produced by parenteral or intra-articular injections of soluble gold salts such as sodium aurothiomalate and aurothioglucose. This study shows, (1) that an orally administered gold compound is capable of producing gold deposits in the synovial membrane, and (2) that such compounds may have a future in the treatment of rheumatoid arthritis.

The effects of prostaglandin E1, bradykinin and histamine on canine synovial vascular permeability

1 The relative effects of prostaglandin E1, bradykinin and histamine on canine synovial vascular permeability were investigated by a method based on the measurement of the amounts of radiolabelled dextran (molecular weight 20,000) leaking from the circulation into the synovial cavity. 2 Bradykinin, prostaglandin E1 and histamine in that order of potency all increased synovial vascular permeability. Threshold concentrations were 0.3 micrometer, 3 micrometer and 30 micrometer respectively. 3 The effects of infusion of prostaglandin E1 combined with either bradykinin or histamine were greater than mere summation.

Light and electron microscopy study of capillaries in normal and inflammatory human synovial membrane

Synovium aspirated from the knee joint by trochar was studied by light and electron microscopy in 40 cases of inflammatory arthritis and in 10 controls. The morphology of synovial capillaries, extravascular plasma diffusion, interendothelial vascular gaps, extracapillary blood cell migration, vascular congestion, endothelial hyperplasia, and obliteration of the capillary lumen by endothelial cells were compared in normal and inflammatory synovia. Inflammatory synovitis was characterised by the number and diversity of blood cells migrating through the interendothelial pathway out of the capillary lumen. Polymorphonuclear leucocytes were the blood cells most often seen at interendothelial junctions. No other capillary changes that might be related to synovial inflammation were found.

Characteristics of mononuclear cell populations in chronically inflamed synovial membranes

Mononuclear cells infiltrating synovial membranes in chronic synovitis were characterised both in situ and in cell suspensions by surface markers and histochemical techniques. T-lymphocytes were the predominant infiltrating cell in rheumatoid arthritis as well as in other forms of chronic arthritis, including ankylosing spondylitis and arthritis associated with Crohn's disease. B-lymphocytes were found exclusively in rheumatoid synovial membranes. These cells were demonstrable both in true germinal centres and, focally and diffusely, in nodular mononuclear infiltrates lacking the histochemical characteristics of germinal centres. The synovial lining cells, unlike mononuclear phagocytes, had no demonstrable receptors for C3 and Fc.