Localization of interleukin-1 alpha, type 1 interleukin-1 receptor and interleukin-1 receptor antagonist in the synovial membrane and cartilage/pannus junction in rheumatoid arthritis

Using monoclonal antibodies and immunohistochemical techniques we have investigated the presence and distribution of interleukin-1 alpha (IL-1 alpha), type 1 IL-1 receptor (IL-1R1) and of interleukin-1 receptor antagonist (IL-1ra) in synovial tissue from 18 rheumatoid arthritis (RA) and eight osteoarthritis (OA) patients and in eight normal synovial tissue samples. IL-1 alpha and IL-1R1 were found in all of the samples examined. In RA, there were a large number of synovial cells expressing IL-1 alpha and IL-1R1, with 85 and 90% positive cells in the lining layer, 45 and 80% in the interaggregate area, and 90% of the vascular endothelial cells. In the lymphoid aggregates, 20% of the cells contained IL-1 alpha and 70% expressed IL-1R1. IL-1 alpha and IL-1R1 expressing cells showed a similar distribution in OA synovial membrane, but there was a smaller number of positive cells in the deeper area; and the staining intensity was lower. In contrast to IL-1 alpha and IL-1R1, IL-1ra was found only in 10/18 RA, 5/8 OA and 2/8 normal tissue samples. IL-1ra was detected in 35% of RA and 45% OA lining layer cells; 25% RA and 35% OA vascular endothelium; 10% RA and 15% OA interstitial cells and 30% cells in RA lymphoid aggregate. The staining intensity in both RA and OA tissues was comparably low. The presence of IL-1ra in RA and OA tissues was confirmed by Northern blot analysis for IL-1ra mRNA.(ABSTRACT TRUNCATED AT 250 WORDS)

Systemic distribution of wear debris after hip replacement. A cause for concern?

The production of particulate wear debris is a recognised complication of joint arthroplasty, but interest has concentrated on local tissue reactions and a possible association with implant loosening. The fate of wear products in the body remains unknown, although some of the metals used in the construction of orthopaedic implants are known to have toxic and oncogenic properties. We report histological and electron-microscopic evidence from two cases which shows that metallic debris can be identified in the lymphoreticular tissues of the body distant from the hip some years after joint replacement. The increase in the use of total arthroplasty in younger patients, the development of new alloys and the use of porous coatings must raise concern for the long-term effects of the accumulation of wear debris in the body.

Immunohistochemical study of extracellular material in the aged human synovial membrane

Types III, IV, VI collagen and laminin distribution in synovial tissue of seven autopsy knee joints from old human donors (69-94 years of age) were investigated with immunocytochemical and immunohistochemical methods. The synovial intima is separated from the subintimal tissue by an intermediate fibrillar zone rich in staining for type III collagen. In the intima basement membrane-like material associated with synovial lining cells stains for type IV collagen and laminin. Fine fibrils surrounding the lining cells stain for type VI collagen. In two of the cases type VI collagen occurs mainly as long-spacing collagen, the distinct aggregated form of type VI collagen. This staining pattern was qualitatively the same in all different regions and cases investigated. However, considerable quantitative differences were seen.

Scanning electron microscopic evaluation of the arthritis in MRL/lpr mice

The articular surfaces of disarticulated knee joints from MRL/lpr and MRL/n mice, aged 4-33 weeks were examined by light microscopy (LM) and scanning electron microscopy (SEM). Light microscopy did not reliably predict SEM findings. Most of the abnormalities detected by SEM were related to surface disruption of articular cartilage. However, areas of articular cartilage covered by tightly adherent non-confluent monolayers of stellate-shaped cells with intertwining cytoplasmic processes were observed. In these areas the integrity of the underlying cartilage matrix was disrupted, with exposure of collagen fibers. These findings suggested that outgrowth of proliferating synovial cells in the joints of arthritic MRL/lpr mice may lead to cartilage destruction.

Aging of the human synovium: an in vivo and ex vivo morphological study

Age-associated changes of the human synovium have been investigated by microarthroscopy, optical and electron microscopy, immunohistochemistry, and cytochemistry. The knee joints of nineteen 15- to 56-year-old subjects, classified as normal by inspection, were carefully examined by microarthroscopy; small synovial tissue biopsy specimens from both the suprapatellar pouch and the medial tibiofemoral gutter were taken. Microarthroscopy showed that the villi were more numerous and the vascular network and cell distribution and profiles less regular in aged individuals. These data were confirmed by scanning electron microscopy, which also showed large areas of the synovial surface devoid of cells and collagen bundles in contact with the joint cavity in aged subjects. Light and transmission electron microscopy confirmed these data and allowed evaluation of the number, distribution, shape, and internal organization of cells as well as the distribution of vessels and the organization of the extracellular matrix in the full thickness of the synovium (down to 2 mm). Particular attention was paid to synovial lining cells, among which three main phenotypes could be recognized: synthetic type (present at all ages and hypertrophied in aged subjects), macrophagelike (increasing with age), and fibroblastlike. Collagen increased with age. Further studies are needed for comprehensive understanding of age-associated changes in the human synovium.

Ultrastructural morphology of early cellular changes in the synovium of primary synovial chondromatosis

Synovial tissues taken from 13 cases of synovial chondromatosis (SC) were examined by light and electron microscopy. In three of the 13 cases, early cellular changes were observed by electron microscopy. Most of the foci were independently situated within an accumulation of fine, homogenous chondroid matrix in the sublining area of the synovium. Basal laminalike material was observed in these cells. Because this material was not apparent in the mature cartilage cells, the authors postulate that the basilaminar material affects cellular cytodifferentiation in SC during the initial phase of the disease. Ultrastructurally, these cells are morphologically similar to myofibroblasts. However, proliferation of paravascular cells with distinct basal laminae and activated secretory abilities was observed around some of the vessels. These paravascular cells may be the precursor cells of the prechondroblastic cells with basal laminalike material seen in SC.

[Histopathological characteristics of rheumatoid arthritis--as a clue to elucidate its pathogenesis]

A correct histopathological diagnosis of Rheumatoid Arthritis (RA) is quite important for the decision of early phase treatment to cure it fundamentally. But, generally speaking, usual hospital pathologist is not so much experienced about RA. The purpose of this article is originally to let such pathologist familiar in RA pathology, but for the RA specialist to offer any clue to elucidate the still-unknown etio-pathogenesis of RA or to cure RA fundamentally. The "Tetralogy of RA Arthritis for pathologist" must be as follows: (1) Enormous proliferation of well-permeable granulation-tissue-type neo-vascularization, some of which became high column-endothelial and the center of primary as well as secondary follicle-like lymphoid cell cluster. (2) Lymphoid cluster in RA synovium is also pathological in function. It consisted of preferentially CD4T and B cells to produce IgG rheumatoid factor endlessly. (3) Synovial lining A and B cells proliferate as far as five layers of each, but later, the sublining D (M) and D (F) cells proliferate more and more and finally replace the lining cells. D (M) cells express macrophage marker and full of lysosome, on the contrary, D (F) cells express mesenchymal marker and contains much metalloproteinase. Both express strong Class II antigens but neither has complement activation inhibitor DAF. (4) Proliferation of these D cells with full of mesenchymal tissue destroying and inflammation accelerating activity must be playing a major role in the joint destruction of RA, some in shape of pannus and more in shape of granulation tissue in and around the bone.

[DIfferentiation of enthesis and the synovial membrane in the rat]

The development of the knee joint in Wistar rats was observed from the 14th fetal day to the 40th postnatal day by light microscopy, transmission electron microscopy and scanning electron microscopy. The differentiation of the capsular ligamentous and tendinous attachments, synovial cavity, and A and B cells were particularly compared. Capsular attachments appeared for the first time at the 15th day of fetal life. The formation of the cavity started at the 17th day of fetal life. The differentiation of A and B cells was observed by the 20th fetal day by T.E.M., and only by the 15th postnatal day by S.E.M.

Resorption of bone by inflammatory cells derived from the joint capsule of hip arthroplasties

The role of inflammatory cells in aseptic loosening and failure of cemented joint replacements is unclear. Inflammatory cells from the revision joint capsule of four failed hip arthroplasties were examined to determine their nature and resorptive capacity. The capsules contained numerous macrophages and abundant foreign-body macrophage polykaryons, distinguished from osteoclasts by their antigenic phenotype and lack of response to calcitonin. When cultured on cortical bone slices in vitro, both macrophages and macrophage polykaryons produced small resorption pits and were associated with areas of superficial resorption of the bone surface. These results indicate that foreign-body induced macrophages and macrophage polykaryons are capable of a type of low-grade bone resorption which may be of pathogenic significance in the loosening of cemented joint prosthetic components.

Hereditary chondrocalcinosis in a Tunisian family

A clinical and radiological survey of 77 members of a Tunisian family with hereditary chondrocalcinosis was performed. Articular chondrocalcinosis was documented by X-rays in 7 living members of 3 generations. No associated or secondary forms of the disease were found. Clinical features of the disease appeared early in life and radiologic involvement was extensive. The mode of inheritance appeared to be autosomal dominant with incomplete penetrance. Electron microscopy study of synovium and cartilage biopsies from one patient demonstrated calcium pyrophosphate dihydrate crystals. HLA typing revealed that all affected subjects bore the haplotype A1 B12 DR3.

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.

Long-term results of knee synovectomy in pigmented villonodular synovitis

1. Pigmented villonodular synovitis (PVS) commonly affects the knee as a monoarticular proliferative process. The etiology is not understood. 2. Partial synovectomy for localized PVS and wide synovectomy for diffuse PVS institute a favorable result, despite a rather high rate of recurrence at long-term follow-up. 3. Cases that involve bony erosion have a low incidence of recurrence but present an unsatisfactory prognosis even after curettage and wide synovectomy (postoperative progress of osteoarthritic changes).

Characterization of kinin receptors on human synovial cells and upregulation of receptor number by interleukin-1

Bradykinin has been implicated in the pathogenesis of inflammatory arthritis by virtue of its potent proinflammatory properties. We have previously shown bradykinin to be a potent stimulus for the release of prostanoids from interleukin-1 (IL-1)-treated, but not untreated, human synovial cells. We hypothesize that one mechanism by which IL-1 induces responsiveness to bradykinin is by upregulation of number or affinity of kinin receptors on human synovial cells. We performed [3H]bradykinin binding studies in intact human synovial tissue and in cultured human synovial cells. Specific, saturable [3H]bradykinin binding sites in intact synovia were identified by autoradiographic localization and were present in much higher density in rheumatoid, than in osteoarthritis, synovia. In untreated human synovial cells in culture, a single (B2) class of kinin binding sites with a Kd of 2.3 nM and Bmax of 58 +/- 9 fmol/10(6) cells was demonstrated. In matched experiments, IL-1 treatment enhanced specific [3H]bradykinin binding 1.5- to 2.0-fold above that observed in untreated cells. This enhancement was attributable to an increase in Bmax (53 +/- 4 vs. 105 +/- 24 fmol/10(6) cells in untreated and IL-1-treated cells, respectively), rather than an alteration in Kd (1.7 and 1.4 nM, respectively). The potencies of a series of kinin analogs and antagonists and unrelated peptides in displacing [3H]bradykinin from IL-1-treated cells correlated well with their abilities to induce prostanoid release. These studies provide novel information regarding the nature of kinin receptors in intact human synovia and in cultured human synovial cells, their regulation by IL-1 and their role in IL-1-treated cells in kinin-mediated prostaglandin E2 production.

Equine synovial tendon sheaths and bursae: a transmission electron microscope study

A transmission electron microscope study was undertaken to investigate the details of the synovial tendon sheath and bursal lining in horses. The lining cells appeared to be fibroblasts and were buried in a finely granular ground substance. Generally these cells had poor cytoplasmic organelles, sparse short profiles of rough endoplasmic reticulum (RER), few scattered ribosomes and, occasionally, a poorly developed Golgi complex. However, a few lining cells appeared more active, having pronounced RER with dilated cisternane. The surface of the lining cells, particularly those with dilated RER, had filipodia of different shapes, which in some instances appeared to surround a detached matrix. This feature might indicate that these cells are capable of phagocytosis. In young animals, the lining was more or less akin to that of the adult. However, the lining cells were virtually indistinguishable from the fibroblasts in the subconnective tissue.

[Differences in polyethylene wear in hip joint prostheses with ceramic- and with metal-polyethylene combination of the articulation surfaces--a study of surgical and of autopsy materials]

Pseudocapsules of artificial hip joints with ceramic- and metal on polyethylene combination of the articulating surfaces from 126 revision arthroplasties and 41 autopsies were studied histologically with semiquantitative evaluation of the polyethylene wear. The results were compared with reports of laboratory tests in the literature. We found in the autopsy specimens as well as in the biopsies from revision arthroplasties of prostheses implanted for 4 to 8 years three times less polyethylene wear particles released from the ceramic on polyethylene prostheses. The newly established synovium surrounding prostheses with ceramic heads appeared 20% reduced in thickness with minor villous transformation. Different types of metal on polyethylene prostheses revealed no differences in wear behaviour with the exception of the bipolar prostheses which showed a markedly increased polyethylene wear.

Gold treatment of rheumatoid arthritis decreases synovial expression of the endothelial leukocyte adhesion receptor ELAM-1

Leukocyte adhesion receptors on endothelial cells play an important role in the evolution of synovitis. We studied sequential synovial biopsies at Weeks 0, 2 and 12 in 11 patients with rheumatoid arthritis beginning parenteral gold therapy either alone or combined with 120 mg intramuscular methylprednisolone acetate at Weeks 0, 4 and 8 of treatment. Expression of endothelial leukocyte adhesion molecule 1 (ELAM-1) decreased on synovial blood vessels after both 2 and 12 weeks treatment (p less than 0.05), while the overall vascularity of the synovium did not change. Neutrophil numbers within the synovial membrane also decreased although this did not reach statistical significance. In contrast, there was no significant change in numbers or subset distribution of T cells or in Class II MHC expression by synovial lining cells, mononuclear cells or endothelial cells. Our results suggest that one of the early effects of intramuscular gold and glucocorticoid therapy may be a downregulation of the acute inflammatory process associated with the endothelial expression of a neutrophil adhesion receptor and the subsequent recruitment of neutrophils into the joint.

Fine structure of the human synovial lining cell in osteoarthritis: its prominent cytoskeleton

The cytoskeleton of the human osteoarthritic synovial lining cell (SLC) consists of an extensive number of vimentin intermediate filaments (IFs) in addition to microfilaments and microtubules. The IFs are especially prevalent in the SLC processes, but are commonly seen in a paranuclear arrangement. Processes, ending in numerous microvilli and blebs, project into the joint space. Scanning electron microscopy (SEM) further reveals the processes that may parallel the synovium surface for a short distance. IFs extend to the termination of such Numerous pinocytotic vesicles and extensive rough endoplasmic reticulum (rER) are characteristic of the type B cells. Lysosomes and long microvilli identify the type A cell. Punctate adherens, gap junctions, and cilia are the cell membrane specializations of the osteoarthritis (OA) synovium. A comparison with synovium from rheumatoid arthritis (RA) patients is made in order to assess the effect o this inflammatory disease on the SLC cytoskeleton, cell type relationship, and cell arrangement. The prominent cytoskeleton appears to play an important role in the architecture of the synovium. Our findings are further presented in the form of a drawing which in some aspects could describe the morphology of the normal synovium.

Pseudoseptic arthritis: an unusual presentation of neuropathic arthropathy

A 49 year old black man with scoliosis presented with bilateral shoulder swelling eventually shown to be due to neuropathic arthropathy related to underlying syringomyelia. The synovial fluid was highly inflammatory, but cultures from synovial fluid and synovial tissue were all sterile. Profuse fat droplets were noted and considered as a possible cause of the inflammation. This is an unusual presentation of neuropathic arthropathy in a patient who was also harbouring an adenocarcinoma that was undetected until later.

[The semiquantitative characteristics of the ultrastructural changes in the vessels of the microcirculatory bed of the synovial membrane in different clinical variants of rheumatoid arthritis]

Electron microscopy was used to make semiquantitative evaluation of lesions in the microvessels of the synovial membrane in patients with rheumatoid synovitis of different duration, different activity of the disease, joint and systemic form of rheumatoid arthritis, in seronegative and seropositive tests of rheumatoid patients. The synovial biopsy from patients with posttraumatic arthropathy without any clinical and morphological manifestations of synovitis served as control. Frequency of different ultrastructural changes in the vessel wall was statistically evaluated. Significant differences in the submicroscopic picture of microcirculatory lesions in immediate and late rheumatoid synovitis were discovered. Frequency and depth of destructive changes in the vessel wall persisted in the increased activity and appearance of systemic manifestations of the disease.

[The clinico-morphological characteristics of synovial membrane involvement in beta-thalassemia]

Using data on optic and electron microscopy the authors give characteristics of lesions in the synovial membrane of the knee joints in 6 patients with an intermediary form of beta-thalassemia. Multiple reduplication of the basal membrane was noted in all the vessels, the width of the noncellular component of the vessels increased several times and its stratification was clearly seen. Deposits of iron oxide were revealed in biopsy samples of the synovial membrane of all the patients. Those deposits were in the form of microgranular intracellular inclusions in phagocytosing cells of the superficial stroma of villi but more often they were found in the cytoplasm of the vessel cells and pericytes.

Morphology of the synovium during its differentiation and development in the mouse knee joint. A histochemical, SEM and TEM study

The prenatal and postnatal development of the mouse knee joint was investigated by transmission and scanning electron microscopy. In the prenatal stage, following the appearance of a narrow intercellular cleft between two skeletal elements on the 16th fetal day, clefting extended into the lateral synovial mesenchyme. In some regions, the extension of the cleft was very rapid, but in a certain region (future fat pad region), it was somewhat slower. Macrophage-like cells appeared in the synovial mesenchyme on the 16th fetal day, and then increased in number, and were distributed as if they were clustering around the presumptive clefting zone in the future fat pad region on the 17th-18th fetal day. This suggests that macrophage-like cells may participate in joint development, as they phagocytize and remove some kinds of solid extracellular matrix, and facilitate the cleft extension. In the early postnatal stage, scanning electron microscopic observations showed that there were two different types of cell in the synovial lining. One of them exhibited a surface morphology corresponding to that of macrophages: a spherical cell body and numerous pseudopodia. The other type of cell exhibited various cell shapes with many cytoplasmic processes extending along the synovial surface.

Hydroxyapatite crystals are a frequent finding in osteoarthritic synovial fluid, but are not related to increased concentrations of keratan sulfate or interleukin 1 beta

Synovial fluid (SF) was obtained from 40 patients with varying grades of osteoarthritis (OA) of the knee and examined by transmission electron microscopy to ascertain how frequently hydroxyapatite crystals (HA) were present and whether they were related to disease severity or putative markers or promoters of cartilage resorption. HA crystals were conspicuous and abundant in specimens from 21 of the 40 patients studied. Patients in whom HA was present had significantly larger effusions (13.0 +/- 8.9 vs 8.7 +/- 6.1 ml, p less than 0.05). They also tended to have radiologically more severe disease (radiological grade: 2.91 +/- 0.92 vs 2.39 +/- 0.85, p = 0.056). No difference in keratan sulfate (KS) concentrations was observed. Moreover, despite the presence in some specimens of numerous free histiocytes which were actively phagocytosing HA aggregates, the concentrations of interleukin 1 beta (IL-1 beta), a monocyte product with cartilage and bone resorbing activity, were below the limit of detection (20 pg/ml). Our results confirm that HA crystals are a common finding in patients with OA of the knee and show that HA is associated with larger effusions, but not increased SF concentrations of cartilage proteoglycan substituents (KS) or IL-1 beta.

Transforming growth factor beta 1 (TGF-beta 1) induced neutrophil recruitment to synovial tissues: implications for TGF-beta-driven synovial inflammation and hyperplasia

We have studied the consequences of introducing human recombinant transforming growth factor beta 1 (hrTGF-beta 1) into synovial tissue of the rat, to begin to better understand the significance of the fact that biologically active TGF-beta is found in human arthritic synovial effusions. Within 4-6 h after the intra-articular injection of 1 microgram of hrTGF-beta 1 into rat knee joints, extensive recruitment of polymorphonuclear leukocytes (PMNs) was observed. Cytochemistry and high resolution histological techniques were used to quantitate the influx of PMNs, which peaked 6 h post-injection. In a Boyden chamber assay, hrTGF-beta 1 at 1-10 fg/ml elicited a chemotactic response from PMNs greater in magnitude than that evoked by FMLP, establishing that TGF-beta 1 is an effective chemotactic agent for PMNs in vitro as well as in vivo. That PMNs may represent an important source of TGF-beta in inflammatory infiltrates was strongly suggested by a demonstration that stored TGF-beta 1 was secreted during phorbol myristate acetate-stimulated degranulation in vitro. Acid/ethanol extracts of human PMNs assayed by ELISA contained an average of 355 ng of TGF/beta 1 per 10(9) cells potentially available for secretion during degranulation of PMNs. [3H]Thymidine incorporation in vivo and autoradiography of tissue sections revealed that widespread cell proliferation was triggered by TGF-beta 1 injection. Synovial lining cells and cells located deep within the subsynovial connective tissue were identified as sources of at least some of the new cells that contribute to TGF-beta 1-induced hyperplasia. Our results demonstrate that TGF-beta is capable of exerting pathogenic effects on synovial tissue and that PMNs may represent a significant source of the TGF-beta present in synovial effusions.

[Ultrastructural changes in joint capsule in TMJ disturbance syndrome]

The joint capsule is one of component parts of joint. In order to clear the changes of the capsule in TMJ disturbance syndrome, we studied 3 normal capsules and 7 patient's capsules by light microscope and electron microscope. The results are: under LM, some fibrous materials are found on the surfaces of synovial membranes in TMJ disturbance syndrome. The synovial membranes in disease become thicker than usual. The connective tissue shows hyaline degeneration. Under EM, the surfaces of synovial membranes are covered by an irregular granulated or filamentous substance. Collagens are denatured or dissolved. Among fibrils amorphous moderate-electron dense materials are present. The authors think that these changes are associated with the autoimmune reaction in TMJ disturbance syndrome and increase the destruction of TMJ in this disease.

Morphologic and morphometric changes in synovial membrane associated with mechanically induced osteoarthrosis

We sought to determine whether synovial leukocytic inflammation is a primary event in mechanically induced osteoarthrosis. Repetitive impulse loading (50 ms duration at 60 Hz for 40 minutes each day) was applied to the right hindlimbs of 24 New Zealand white rabbits for 3, 6, or 9 weeks. The synovial membrane from the medial suprapatellar area was examined qualitatively using transmission electron microscopy and quantitatively using light microscopic morphometry. The results indicate that synovial inflammation is not a primary event in this mechanically induced osteoarthrosis, but synovial hyperplasia occurs prior to histologically evident cartilage destruction at 6-9 weeks.

Oxidation of thiol in the vimentin cytoskeleton

Sublethal doses of H2O2, which induces oxidative stress, cause substantial alteration to the vimentin cytoskeleton in various cell types. We have used a thiol-blot assay to assess thiol status in individual proteins from cell extracts. Vimentin thiol is oxidized in preference to other cytoskeleton proteins. Immunoblot analysis also demonstrated a loss of reactivity to an anti-vimentin monoclonal antibody under non-reducing conditions, possibly due to thiol-group oxidation. During induced oxidative stress a number of proteins become associated with the cytoskeleton extracts.

Histochemical localization of calcium with potassium pyroantimonate in the articular tissues in calcium pyrophosphate dihydrate crystal deposition disease

The ultrastructural localization of calcium in the articular cartilage, meniscus, and synovium of patients with calcium pyrophosphate dihydrate (CPPD) crystal deposition disease was examined by using potassium pyroantimonate. Focal areas with deposition of CPPD crystals in each tissue showed electron-dense precipitates of the antimony-calcium complex: (1) in the cytoplasm of hypertrophic chondrocytes around CPPD crystals, especially on the margins of intracellular lipid droplets or within electron-dense amorphous material or both; and (2) on the margins of lipid droplets and within electron-dense amorphous material in the degenerated matrix surrounding the hypertrophic chondrocytes. The slender rodlike structures consisting of electron-dense precipitates of the antimony-calcium complex, suggestive of the precursor to rodlike CPPD crystals, were also observed in the degenerated matrix. These findings suggest that the hypertrophic chondrocytes may contribute to the formation of CPPD crystals by intracellular accumulation of calcium and subsequent release of high concentration of calcium into their surrounding matrix.

[3-dimensional characterization of the synoviocytes of the human synovial intima]

The intimal synovial surface in normal conditions, using a scanning electron microscope, has been studied. The three synovial membrane types are clearly recognizable: fibrous (Fig. 8), adipose (Figs. 9 and 10) and areolar (Figs. 1 and 2); but only in the areolar type, the characterization of the main two cellular types: synoviocytes B and A, is possible. Synoviocyte B represents the constitutive element which characterizes the synovial intima; it has a cellular body of irregular shape and long cytoplasmic processes directed towards the joint cavity (Figs. 3, 4 and 5). The cellular body and the cytoplasmic processes are covered by small blebs (Fig. 6). and similar vesicles, probably of the same cellular origin, are scattered throughout the extracellular matrix. These cells are likely responsible for the specific structure of the interstitial tissue adapted to the exchanges and to the regulation of the composition of the synovial fluid (Okada et. al. 1981; Linck and Porte, 1978, 1981). Synoviocyte A is a small minority; it has many long and irregular membrane infoldings which define a complicated system of intracellular canaliculi of various depth (Fig. 7). The ultrastructural characteristics of their surface and the peculiarity of their organelle apparatus, described by other AA. (Fell et. al., 1976), demonstrate that these elements carry out a macrophagic function. The clear majority of the synoviocytes B in the intimal surface suggests that in normal conditions, the synthesizing processes prevail over the phagocytosis ones.

The morphology of synovial lining of various structures in several species as observed with scanning electron microscopy

Data concerning surface morphology of synovial lining of tendons, tendon sheaths, cruciate ligaments, infra-patellar fat pads and peripatellar synovial ridges in various species (rat, rabbit, dwarf goat, sheep, pig, dog, human) are reported on. Supportive studies with transmission electron microscopy (TEM) and light microscopy were performed. Three principal morphological appearances of the synovium are evident. On structures with a dense fibrous architecture like tendons, tendon sheaths and cruciate ligaments the intimal cells and processes are mostly slender and may tend to orientation in the length-axis of the structure. On the peri- and infrapatellar adipose tissues two principal 'extremes' are seen: one in which the contours of the fat cells are clearly visible with fungoid shaped structures in between them, and one in which the fat cell contours are not recognizable and the intima consists of cauliflower-like cells. Transitional forms exist. Several features observed on tendons and tendon sheaths which have not been reported on before are presented in this paper. A consistent classification of synovium is presented.

Antigen-induced arthritis in the rabbit: ultrastructural changes at the chondrosynovial junction

Structural changes at the chondrosynovial junction of the lateral border of the lateral femoral condyle have been studied by electron microscopy in rabbits with antigen-induced arthritis of 6 h-27 days duration. Rapid changes in the collagen fibrils of the extracellular matrix in the synovial lining and articular cartilage were noted. Collagen fibrils with unusually large diameters were observed. Overgrowth of cartilage by inflamed synovium was seen within 3-6 days of induction of arthritis and by day 12 the interface between these two tissues was largely indistinguishable. The synovial pannus at this time was fibrotic and infiltrated with plasma cells, lymphocytes and macrophages. Few polymorphonuclear leucocytes were found in the developing pannus. Macrophages were found with extended processes which enveloped neighbouring cells. Some blood vessels had thickened endothelial cells though lymphocytes were not observed in their vicinity. This study reveals the rapidity with which synovial pannus can develop and suggests that there are a number of mechanisms operating to cause cartilage breakdown in antigen-induced arthritis.

Cellular immune response toward human articular chondrocytes. T cell reactivities against chondrocyte and fibroblast membranes in destructive joint diseases

Articular cartilage is one of the major targets in destructive joint diseases in humans. We studied cellular immune reactions against cartilage cell-surface membranes, because it has recently been suggested that these represent possible antigenic structures, based upon the observation of autoantibodies with this specificity in certain joint diseases. A striking T cell reactivity toward chondrocyte membranes was found both in blood and synovial tissue from patients with rheumatoid arthritis. This reactivity was strongly dependent on the presence of monocytes and had all the characteristics of an antigen-driven process. Clonal analysis demonstrated high precursor frequencies in peripheral blood T cells that were reactive against chondrocyte membranes. This response to chondrocyte membranes greatly exceeded the T cell stimulation induced by membranes from other sources such as fibroblasts or epithelial cells. In contrast to patients with rheumatoid arthritis, individuals with osteoarthritis showed a strong peripheral blood and synovial fluid T cell response not only to chondrocyte membranes, but also to fibroblast membrane material. However, there was no reactivity to epithelial cell membranes. Normal donors generally did not show significant responses to any membrane preparation. These data indicate that there is a strong T cell reactivity toward chondrocyte membranes in destructive joint disorders, and this may significantly contribute to the pathogenetic processes that occur in these diseases.

Ultrastructural observations on Penicillium marneffei in natural human infection

The ultrastructure of Penicillium marneffei and the host response to the infection were studied in two patients. One was immunocompetent and the other an immunosuppressed renal graft recipient. In the immunocompetent patient it was observed that all the yeast cells were phagocytosed and were found either within membrane-bound vacuoles or lying freely within the cytoplasm of the macrophages. It was postulated that continuous lysosomal fusion with the phagolysosomes and multiplication of the fungi within the phagocytic vacuoles might eventually lead to the rupture of the vacuoles with release of the organisms into the cytoplasm of the macrophages. In the second patient, the immunosuppressive effects of corticosteroids might account for the large number of nonphagocytosed fungi in the tissue space, and the failure to form large phagocytic vacuoles.

Morphological aspects of the synovial membrane and the femoral epiphyseal nucleus in anemia induced experimentally (note 1)

The authors describe the macroscopic and ultra-structural changes in the synovial membrane and the growth nucleus consequent to anemia induced experimentally. In the anatomical region studied an early and a late response to the transitory anoxia is observed. The former is represented by the accentuation of the macrophagic activity of the A synoviocytes and by pictures of trabecular fragmentation. The latter is represented by hyperplasia of the synovial membrane, a reduction in the thickness of the joint cartilage, and by early and patchy calcification of the epiphyseal disc.

HIV associated arthropathy: HIV antigen demonstration in the synovial membrane

Light and electron microscopic studies were performed on the synovial membranes of 5 patients with HIV associated arthropathy. An immunoperoxidase technique with the use of monoclonal antibodies against CD4, CD8, B and DR lymphocytes, and HIV p24 antigen was also used. Mild to moderate nonspecific proliferative changes and increased vascularity of the subsynovial space were seen. Electron dense deposits and viral-like particles were not observed. Immunohistochemical staining revealed HIV p24 positive staining in cells of the synovial lining layer and in the mononuclear cells of the subsynovial space. CD4, CD8, with predominance of CD8, and B and DR cells were also present. The presence of HIV p24 antigen may be indicative of a role, yet to be defined, in the pathogenesis of HIV associated rheumatic disorders.

[Microstructure of tendon and its clinical significance]

Superficial and internal-structure of human and rat tendons were investigated under scanning electronic microscopy. Histologically, there are many pores on the synovium, under which a layer of network of fiber bands wraps the tendon. The synovial fluid propulsion system includes: Synovium----pores----network of fiber bands----space of tendon bands----space of tendon fibers. The synovial fluid is propelled through the above structure. The function of the network structure is like a sponge, it has the function of nutrition, absorption of heat, and lubrication.

Equine synovial tendon sheaths and bursae: an histological and scanning electron microscopical study

The structure of equine synovial tendon sheaths and bursae has been examined by light and scanning electron microscopy. Tissue samples were obtained from horses of various types and ages with no clinical evidence of sheath or bursal disorders. The interior of both structures was lined by a cellular layer superimposed on a vascular zone supported by a fibrous layer. The pattern of cell distribution of the lining varied from site to site within the same structure depending on the nature of the underlying tissue and on the amount of movement to which the structure was subjected. The cellular layer was predominantly fibrous in nature with scanty, widely separated fibroblasts (eg where it lines the palmar ligament, tendons and paratendons). In the mesotendon and bursal extremities, where the lining is subjected to a positive degree of movement, the cellular layer was areolar in type with well established folds populated by abundant cells oval to round in shape. In foals and yearlings, the supportive layer was mainly around the areolar with patches of adipose tissue; which were gradually replaced by fibrous tissue as the animal grew.

A monoclonal antibody (Mab 67) marks type B synoviocytes

The functionally important lining cells of the synovium (types A and B synoviocytes) are the subjects of much study but have presented problems with their characterization and microscopical identification, particularly at the light level. Type A (macrophage-like) synoviocytes, however are more easily localized than the type B (fibroblast-like) variety because of the greater availability of antimacrophage antisera. We describe, using light and electron microscopy, a monoclonal antibody which in the synovial intimal layer is specific for type B synoviocytes.

Analysis of removed autophor ceramic-on-ceramic components

Six Autophor alumina ceramic total hip arthroplasty components (5 removed for stem loosening and 1 for cup loosening) were evaluated to determine the nature and extent of wear by direct measurement, scanning electron microscopy of wear debris, and histology. Component implantation averaged 29 months (range, 8-54 months). All components had evidence of marked wear, including gross loss of material, which increased with the duration of implantation.

Ultrastructural characteristics of the human synoviocytes

The purpose of this study was to identify, by the scanning electron microscopy, the behaviour of the different cell types in the normal human synovial intima, in order to obtain information useful for interpreting pathological changes in the synovium. Our observations revealed that, in numerous areas of the synovial membrane (adipose or fibrous type), the synoviocytes were dispersed and the intercellular matrix, covered only by the cytoplasmic processes of cells deeply located, was in direct contact with the joint cavity. In the areolar type of the synovium the synoviocytes were more numerous; they tended to concentrate to give the appearance of a continuous tissue; but between the cells very large intercellular spaces were usually present. In this latter membrane type we identified the two main cellular types of the synoviocytes: A and B. B-synoviocytes were the predominant cell type of the synovium. These cells were characterized by long cytoplasmic processes, perpendicularly directed towards the joint cavity. Both the cellular body and the cytoplasmic processes were covered by small blebs and vesicles of various size. The A-synoviocytes were a small minority, rarely dispersed between the B-synoviocytes. They were characterized by numerous membrane infoldings which delimited intracellular canaliculi of various depth. Our ultrastructural observations demonstrated that, in normal conditions, the B-synoviocyte must be considered as a constitutive element which characterized the synovial intima, responsible for the specific structure of the interstitial tissue and for the regulation of the composition of the synovial fluid.(ABSTRACT TRUNCATED AT 250 WORDS)

Fatty change in the human temporomandibular joint disc. Light and electron microscopy study

Joint pain has been associated with fatty infiltration of the knee articulation. The purpose of this study is to report on the histopathological findings, especially fatty changes, that are seen in surgical specimens from the temporomandibular joints (TMJ) of patients that had persistent pain after non-surgical therapy. Forty plicated TMJ retrodiscal samples from 25 patients were used in this study. The patients were previously treated with splints for variable periods but not less than 2 months. The specimens were obtained by 2 surgeons using standard TMJ plication techniques. Control disc specimens were obtained from normal appearing cadaveric TM joints. Samples were immediately immersed in glutaraldehyde and processed for light and electron microscopic examination. The specimens were composed mainly of moderately dense tissue with cells that appeared fibroblastic and intermittent chondrocytic type cells. Fatty change, exclusively in association with the perivascular areas, was observed in 27 of 40 specimens. Electron microscopy showed fibroblasts, as well as large fat inclusions adjacent to elastin macroglobules. Fatty infiltration of the TMJ has been interpreted as a degenerative change. It is postulated that kinins and prostaglandins generated in the fat pads can pass freely in tissue fluid to adjacent, highly innervated structures thus leading to joint pain. It is further postulated that the finding of associated elastin with fatty deposition is similar to the atherosclerotic changes encountered in large blood vessels and the aorta.

Interactions of cultured rat synovial and ocular ciliary body cells with two strains of Mycoplasma arthritidis

Strains of Mycoplasma arthritidis differ in their ability to cause joint and ocular inflammations. Although the reasons for this difference are not fully understood, pathogenic mycoplasmas commonly require close associations with the cells they damage. Using 3H-uridine labeled mycoplasma, we compared cellular interactions of in vitro cultivated rat synovial and ocular ciliary body epithelial cells with two American Type Culture Collection strains of M. arthriditis shown to differ in their virulence. Radiolabeling assays gave evidence of a stronger retention capability on cultured cells by the more pathogenic strain, 14152. Scanning electron microscopy demonstrated cellular associations with the two strains of mycoplasma, with more of the 14152 adhering to both cell types. Examination by transmission electron microscopy showed evidence of contact between the more virulent 14152 strain and both cell types, but no similar evidence with the comparatively less virulent strain, 19611. The pathogenicity of different strains of M. arthritidis may vary according to their ability to closely associate with specific target cells involved in the disease process.

Chronic acquired immunodeficiency syndrome-associated arthritis: a synovial ultrastructural study

We describe a patient who developed acquired immunodeficiency syndrome-related complex, complicated by chronic, symmetric polyarthritis. Synovial biopsy showed large areas of plasma cell infiltration subjacent to the synovial lining. Ultrastructural study demonstrated tubuloreticular structures within endothelial cells, crystal-like inclusions in plasma cells, and virus-like particles located around synoviocyte fragments. Although immunologic and morphologic studies did not permit classification of these virus-like structures, the role of these possible virions in the pathogenesis of the observed synovitis remains to be determined. Surprisingly, the patient's chronic arthritis resolved with anti-retroviral treatment (azidothymidine: AZT).

[The synovial membrane in chronic juvenile arthritis. Electron microscopy study and case report]

A case report of a patient with juvenile chronic arthritis who underwent early synovectomy of the knee joint is presented. The synovial membrane was examined by light and electron microscopy. The following signs of nonspecific inflammation were observed; lympho-plasmocytic infiltrate in the ground substance of the interstitial connective tissue, increased phagocytic activity of synovial lining cells and macrophages, and neutrophilic granulocytes. The inflammatory infiltrate is presumed to have damaged the finest part of the microcirculation--the ultracirculatory system of tissue channels. Complete remission was achieved and the function of the patient's knee joint is fully preserved.

The fine structure of the fibrous zone of articular cartilage in the rat mandibular condyle

The ultrastructure of the articular fibrous zone of the rat mandibular condyle was observed at 3 and 6 weeks of age in order to investigate the histological changes that occur during the establishment of mastication after suckling. We divided the articular fibrous zone into two layers (F1 layer and F2 layer). The F1 layer was composed of fibroblast-like cells, macrophage-like cells, and the matrix which consisted of granular or fibrillar material, loosely arranged small bundles of collagen fibrils with uniform thickness of 30-50 nm, and independent microfibrils. The F1 layer was continuous with the synovial membrane without any distinct boundary in its peripheral area. Mitotic figures could infrequently be observed in the fibroblast-like cells. The cells in the F2 layer closely resembled fibroblasts. The matrix in the F2 layer mostly consisted of densely arranged bundles of collagen fibrils which are not of uniform diameter ranging 40-100 nm. Elastic fibers occurred among the collagen fibrils. The F1 layer which was observed clearly at 3 weeks almost disappeared at 6 weeks of age. It is confirmed that the F1 layer resembling the synovial membrane exists over the condyle up to the weaning period about 3 weeks of age but it degenerates before 6 weeks of age when the masticatory function is established.

Microfibrillar meshwork of the synovial lining and associated broad banded collagen: a clue to identity

The surface layer of synovial interstitium lining the rabbit knee was studied by transmission electron microscopy. Over a distance of 2-3 microns normal to the surface the interstitium contained a network of fine microfibrils (diameter 9.3 (0.7) nm, mean (SEM] which was quite dense in places (fractional area of projection 0.189 (0.023], and stained with ruthenium red. Periodic collagen fibrils were relatively scanty and fine (diameter 32 (2) nm) in this surface layer. Broad cross-striated bundles occurred in association with the microfibrils and B cells. These fibrous long spacing bundles (FLS) had a single period of 92.8 (2.8) nm with a broad dark band (37.6) (1.8) nm--so called 'zebra collagen'. Both the periodicity of the FLS and the morphological characteristics of the microfibrils are typical of type VI collagen, a widespread constituent of soft connective tissues. The functional importance of the inner microfibril network is likely to be mechanical, biochemical (glycosaminoglycan and glycoprotein entrapment), and to a very minor degree hydraulic resistance.

Rapid onset synovial inflammation and hyperplasia induced by transforming growth factor beta

After intraarticular injection of TGF-beta 1 or TGF-beta 2, marked swelling and erythema of the injected joints were apparent within 12-24 h. On a scale of 0 to 4, by day 3, the TGF-beta-treated joints had articular indices (AI) of 3.6 +/- 0.5 to 4.0 +/- 0.0 compared with no response for the vehicle-injected contralateral joints. Histopathologic evaluation revealed a predominantly mononuclear phagocyte infiltrate with some neutrophils and T lymphocytes, consistent with active inflammation. The monocytic pattern of leukocyte infiltration at 2-3 d was comparable to that seen in animals with antigen-induced arthritis after 2-3 wk. Extensive synovial fibroblast hyperplasia became apparent within 48 h, likely as a result of TGF-beta induction of growth factor synthesis by the accumulating monocytes. TGF-beta 2, a homologue of TGF-beta 1, was found to induce a similar level of synovitis and synovial hyperplasia consistent with its parallel monocyte and fibroblast chemotactic properties and ability to induce transcription and translation of monocyte/macrophage-derived growth factors. These data suggest that TGF-beta, released by platelets and activated inflammatory cells, may play a direct role in leukocyte recruitment and activation in arthritic and other chronic inflammatory lesions.

Ultrastructural changes in synovium and cartilage in experimental hemarthrosis in dogs

This paper reports electron-microscopic findings in synovium and cartilage in experimental hemarthrosis in dogs. The results are correlated with the total amount of glycosaminoglycans in the cartilage matrix, measured by the fixed-charge density method. Very early, changes are seen in the synoviocytes, similar to synovitis, and especially phagocytosis of iron-containing particles forming secondary lysosomes or siderosomes. Siderosomes are also a constant feature seen in the chondrocytes, together with changes in the rough endoplasmic reticulum and in the glycogen content, correlating with the changes in the ground substance.

Ultrastructure of transport pathways in stressed synovium of the knee in anaesthetized rabbits

1. The hydraulic conductance of the synovial lining of a rabbit knee increases greatly when intra-articular pressure (IAP) is raised above approximately 9 cmH2O (yield point). To investigate the cause, synovium was fixed in situ by perfusion at controlled IAP and prepared for transmission electron microscopy. Micrographs of synovium fixed below yield pressure (atmospheric pressure and 5 cmH2O IAP, ten joints) and above it (25 cmH2O IAP, five joints) were analysed by morphometry. 2. The discontinuous cellular lining consisted of fibroblast-like cells (67%) and macrophage-like cells (33%) separated by interstitium-filled gaps. Interstitium formed 26-36% of the surface below yield pressure. Depending on sample site the surface gaps averaged 1.9 +/- 0.2 to 2.4 +/- 0.2 microns wide below yield pressure (mean +/- S.E.M. throughout). Above yield pressure the mean gap width increased by 42-64% (P less than 0.05, analysis of variance). 3. The qualitative and quantitative composition of the lining varied with distance below the surface. In a plane 5 microns deep, the intercellular distances and interstitial area fraction were almost double those at the surface. Classic periodic collagen fibrils (diameter 50 +/- 3 nm) abounded at 5 microns depth whereas the surface interstitium was richer in Ruthenium Red-staining microfibrils (diameter 9.3 +/- 0.7 nm) associated with 93 nm period fibrous long-spacing bundles. 4. Averaging over all the tissue between the surface and the 5 microns deep plane, the mean interstitial volume fraction was 0.61 +/- 0.05 at 5 cmH2O and 0.67 +/- 0.02 at 25 cmH2O (n.s.). 5. Capillary fenestrae (8.5 +/- 1.1 per fenestrated profile) and intercellular junctions were unaltered at high IAP. The tortuosity of the capillary-to-joint cavity path was 1.50 +/- 0.01 below yield pressure and 1.86 +/- 0.24 at 25 cmH2O (n.s.). 6. Intra-articular tracers (ferrocyanide, ferritin and glycogen) permeated synovial interstitium without evidence of preferential pathways. Ferrocyanide delineated the capillary intercellular junction as a permeable channel. Ferritin and glycogen were phagocytosed by the macrophages. 7. In suprapatellar areolar synovium, the most extensive and most altered tissue, the ratio of interstitial area to path length increased maximally 4.1 times between 5 and 25 cmH2O IAP. This represents a substantial contribution to the physiologically estimated rise in interstitial conductance (14 x) but does not wholly explain it.

Detection of Borrelia in the synovial tissue from a patient with Lyme borreliosis by electron microscopy

We describe a woman who suffered for several years from joint pain with subsequent development of arthritis of her left knee. Because of these symptoms she was subjected to repeated studies including arthroscopy and menisectomy. IgG antibodies to Borrelia determined by ELISA were reported to be present and showed an increase of IgG titer to 1:1024. Histology from the last synovial biopsy disclosed only evidence of a nonspecific synovitis and marked inflammatory infiltration with lymphocytes and plasma cells. Borrelia-like structures were detected electron microscopically on semithin Epon sections from the lumen of the strongly infiltrated blood capillary. In our case the detection of Borrelia indicated the basis for increase of antibodies against Borreliae. It established the correct diagnosis and led to specific therapy of the disease after several years of unsuccessful attempts to control it.

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.