Properties and reactivity of immune complexes in rheumatoid synovial fluid

Summary Fractionation of immune complexes (IC) from rheumatoid synovial fluid revealed the presence of three different fractions of IC. The largest molecular weight form, fraction I (above 1000 Kdaltons) was predominately composed of IgG and IgM and contained both IgM-RF and IgG-RF. The other IC, fraction II (480 Kdaltons) and fraction III (330 Kdaltons), contained predominately IgG with some IgA and only significant amounts of IgG-RF. All three fractions of IC can bind Clq and stimulate human monocyte prostaglandin E (PGE) production. Fraction I IC bound Clq most readily while fraction III IC were the most effective stimulators of monocyte PGE production. IC stimulation of monocyte PGE production was inhibited by staphylococcus protein A suggesting mediation via activation of Fc receptors. It remains to be determined whether this IC reactivity has any pathologic significance.     

Basement membrane proteins in synovial membrane: Distribution in rheumatoid arthritis and synthesis by fibroblast-like cells

Summary Rheumatoid arthritis is a complex disease of unknown origin. In consequence of some immunological reactions, proliferative invading synovial tissue leads to destruction of normal joint architecture. The aim of this study was to investigate qualitative changes in extracellular matrix distribution of proliferating rheumatoid synovium and their cellular origin. Synovial tissues from 57 clinically indicated arthrotomies were investigated with immunofluorescence, using specific antibodies against extracellular matrix proteins in tissue slides and cultured cells, which were also studied for collagen biosynthesis. Results indicated that synovial fibroblast-like cells synthesize and secrete basement membrane proteins laminin and collagen type IV as e.g. endothelial cells or organogenic fibroblasts. Laminin and collagen type IV were specifically demonstrated pericellularly in the hyperplastic lining layer of active rheumatoid synovitis. These findings are discussed with respect to the possible implication of altered cell-matrix interactions in rheumatoid synovial proliferation.     

Enhanced production of prostaglandins and plasminogen activator during activation of human articular chondrocytes by products of mononuclear cells

Summary We have examined the way in which products of cultured human blood mononuclear cells activate human articular chondrocytes. Conditioned medium from mononuclear cells enhanced the production of prostaglandin E by cultured human chondrocytes and also stimulated fibrinolytic activity in these cultures. These two effects may be interrelated, since the increased fibrinolysis in response to products of mononuclear cells was partially inhibited by indomethacin, an inhibitor of prostaglandin biosynthesis. The increased fibrinolysis is probably attributable to plasminogen activator, since it was strongly dependent on the presence of plasminogen. Increased amounts of PGE and chondroitin sulphate were also released from intact fragments of cartilage exposed to medium from cultured mononuclear cells. The time course and dose dependence of these effects were studied. The addition of exogenous arachidonic acid markedly enhanced production of PGE₂.Ultrogel AcA54 was used to fractionate medium from cultured mononuclear cells and the chondrocyte-stimulating activity eluted with an apparent molecular weight between 12 000 and 25 000 daltons. Adherent and non-adherent mononuclear blood cells were also partially separated and conditioned medium from each was assayed for chondrocyte-stimulating factors. Both populations released factor(s) which increased the production of prostaglandin E by chondrocytes, but more activity came from the adherent mononuclear cells. The possible interrelationship between the chondrocyte activating factor studied here and others described in the literature is discussed.     

Binucleated and multinucleated forms of plasma cells in synovia from patients with rheumatoid arthritis

A morphological examination of synovial tissue from 25 patients with rheumatoid arthritis revealed that binucleated or multinucleated plasma cells were present in all samples and absent in synovia obtained from 16 control patients. Plasma cells containing two, three of four nuclei constitutet a mean 3% of the total plasma cell population. They were aways found amongst plasma cell infiltrates and in close association with small blood vessels. Ultrastructural analysis found no evidence of cellular membranes separating the individual nuclei in binucleated or multinucleated plasma cells, suggesting that the cells did not arise from fusion. Some of these plasma cells had a diameter approaching 100 μm, and many were in intimate contact with macrophages. The demonstration of a few cells with mitotic figures within the infiltrates suggests that the maintenance of plasma cell numbers in rheumatoid synovium may depend, in part, upon their local proliferation. Received: 25 August 1997 / Accepted: 2 October 1997     

Differential effects of IL-6 blockade tocilizumab and TNF inhibitors on angiogenesis in synovial tissues from patients with rheumatoid arthritis

Objective: To compare the influences of tocilizumab (TCZ) and TNF inhibitors (TNFi) on the angiogenesis in synovial tissues of rheumatoid arthritis (RA).

Methods: Synovial tissues were obtained during joint operations from 13 RA patients treated with TCZ for at least 4 months with or without previous use of TNFi, from 13 RA patients with TNFi alone and from 10 RA patients with only conventional synthetic DMARDs (csDMARDs). Synovial tissues were evaluated by hematoxylin and eosin stain as well as by immunohistological staining with anti-CD31 in which the microvessel densities (MVD) were quantitated. Synovial histopathology was scored for various components.

Results: The most remarkable change in the synovium with TCZ was reduced angiogenesis as well as degeneration of lining layers irrespective of the previous use of TNFi. Thus, MVD in patients treated with TCZ with or without previous TNFi were significantly decreased compared with those in patients with TNFi alone or with csDMARDs. Moreover, MVD was significantly correlated with lining layer proliferation, but not with synovial stromal proliferation or inflammatory changes.

Conclusions: These results demonstrated that inhibition of angiogenesis is a unique action of TCZ. Moreover, the data also suggest that lining layers proliferation might be closely associated with angiogenesis.     

Characterization of synovial tissue from arthritis patients: a proton magnetic resonance spectroscopic investigation

Hypoxia may contribute to the pathogenesis of synovitis in rheumatoid arthritis (RA). Magnetic resonance spectroscopy (MRS) is a technique that uses radiofrequency waves to generate a signal which allows a qualitative and quantitative assessment of the biochemical composition of tissue. MRS was used to evaluate RA synovial tissue for evidence of hypoxia and anaerobic metabolism. Synovial tissue samples obtained from eighteen RA patients and four osteoarthritis control patients undergoing total knee replacement were analyzed using proton MRS, processed for histopathology and scored for inflammation and vascularity. Spectra from severely and mildly inflamed tissue differed in peak intensity at regions 1.3 ppm (representing lactic acid and lipid), 3.0 ppm (representing creatine), 3.2 ppm (representing choline containing metabolites), and 3.8 ppm (representing carbohydrates, possibly glucose). With increasing inflammation, the intensities of the peak resonance at 1.3 ppm increased and that at 3.8 ppm decreased. The intensities of the 3.8 and 3.0 ppm peaks were reduced in highly vascular tissue. Specific MR spectral features reflect the anaerobic metabolism that is evident with progressively increasing degrees of RA synovial inflammation and vascularity. These features correlate partially with synovial histopathology.     

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

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

Expression of heat shock protein receptors on fibroblast-like synovial cells derived from rheumatoid arthritis-affected joints

We examined the membrane expression of inducible Hsp70 and HSP receptors like TLR2, TLR4, CD14, CD36, CD40 and CD91 on fibroblast-like synovial cells (SC) derived from synovial tissue in 23 patients with rheumatoid arthritis (RA), who underwent synovectomy by using flow cytometric analysis. For comparison, autologous skin fibroblasts (SF) derived from the operation wound were tested. Significantly higher Hsp70 expression was found on synovial cells than on skin fibroblasts (median SC 21.4% x SF 5.0%, P < 0.001). Both synovial cells and skin fibroblasts expressed high levels of cell surface CD91 (median SC 80.2% x SF 79.2%), however, no or low levels of CD14, CD40, TLR2, TLR4 and CD36. Further, we observed high co-expression of CD91 and Hsp70 on RA synovial cells (median 18.6%), while skin fibroblasts showed only background Hsp70 expression (median 3.9%, P < 0.001). Since we demonstrated the high prevalence of inducible Hsp70 in RA synovial fluids, we speculate that Hsp70 might be captured onto the membrane of synovial cells from the extracellular space via the CD91 receptor. The significance of the Hsp70 interaction with synovial cells via CD91 remains undefined, but may mediate other non-immune purposes.     

Immunohistochemical analysis of proliferating and antigen-presenting cells in rheumatoid synovial tissue

We analysed the proliferative activity of synovial lining cells (SLCs), the distribution of proliferating B and T lymphocytes and the relationship of proliferating B and T lymphocytes to the pattern of antigen-presenting cells (APCs) within the rheumatoid synovial tissue (n=21). The immunohistochemical detection of the proliferation-associated antigen Ki 67 revealed low proliferative activity of SCL with and without expression of the Kim 8 (CD 68) antigen. Ki 67-positive B lymphocytes could be observed within secondary follicles (2/21), in small follicular dendritic reticulum cell (FDC)-containing follicle-like aggregates (7/21) and near the enlarged synovial intima (6/21). Ki 67-positive T lymphocytes could be detected in T-lymphocyte aaggregates (8/21), in the vicinity of blood vessels (18/21) and within the enlarged synovial intima (15/21). Semiquantitative analysis showed a strong correlation between the numbers of Ki 67-positive B lymphocytes and FDCs and between the numbers of Ki 67-positive T lymphocytes and interdigitating dendritic reticulum cells (IDC). There were significant differences in the number of Ki 67-positive B and T lymphocytes, IDCs and FDCs between the two groups of rheumatoid arthritis (RA) patients with different local clinical activity. These findings demonstrate a low proliferation of SLCs with and without expression of the monocyte-specific antigen Kim 8 and imply that B and T lymphocyte proliferation occurs in the presence of FDCs and IDCs. These results indicate that the RA synovial tissue is a site for antigen-dependent proliferation and maturation of B and T lymphocytes. The atypical pattern of FDC distribution within the rheumatoid synovial tissue dysmorphic follicle may be regarded as morphological substrate for a dysmaturation compartment of B lymphocytes leading to pathogenetic autoimmune phenomena in RA patients.This paper is dedicated to Prof. Dr. H. G. Schwarzacher on the occasion of his retirement as head of the Institute of Embryology and Histology University of Vienna, Austria     

类风湿关节炎患者外周血与病变部位自身反应性T细胞的免疫学特征

目的研究类风湿关节炎(RA)外周血与病变部位自身反应性T细胞亚群的差异性。方法分析了35例RA患者滑膜液中与外周血T细胞的免疫表型、表面活化标志、Ⅱ型胶原和热休克蛋白70(HSP70)的反应频率与V茁的限制性取用。用流式细胞术分别测定滑膜液和外周血淋巴细胞表型和活化标志;采用标准3H-TdR掺入法分析了关节滑膜液中浸润的淋巴细胞对Ⅱ型胶原(CⅡ)和HSP70的反应频率,用半定量聚合酶链反应(PCR)检测了RA患者的V茁的限制性取用。结果滑膜液中CD4+T细胞与外周血中CD4+T细胞百分比相同,分别为40.0%和41.0%,滑膜液中CD8+T细胞比例升高,CD4/CD8细胞比值显著低于外周血。同时滑膜液中表达CD3和CD25的活化T细胞占(16±6)%,比外周血高。这群CD3/CD25双阳性T细胞对CⅡ和HSP70的反应频率增高。虽然外周血和滑膜液中T细胞受体均以琢茁TCR为主(70±16)%。但是进一步用流式细胞术分型检测其BV亚家族的取用特征,发现滑膜液中T细胞受体表现出限制性取用V茁14、16和17。结论在RA滑膜液中T细胞亚群明显不同于外周血;表现为活化细胞增多,对自身抗原的反应频率增高及T细胞受体的限制性取用。     

Lymphocyte infiltration and the synthesis of IgM and IgA rheumatoid factors by rheumatoid synovial membrane

Summary IgM and IgA rheumatoid factor (RF) synthesis by synovial membrane mononuclear cells was measured in 14 patients with rheumatoid arthritis (RA). The results were compared with blood mononuclear cell cultures and correlated with the intensity of lymphocyte infiltration of the synovium. IgM RF was produced by all synovial cultures compared with 56% of blood cultures; IgA RF was produced by 86% of synovial cultures and by 21% of blood cultures. A correlation was observed between synovial IgM RF synthesis, but not IgA RF synthesis, and the intensity of T cell and B cell infiltration of the synovial membrane.     

Endothelial cells are the major source of sICAM-1 in rheumatoid synovial tissue

The objective of this research was to investigate the cellular source of soluble ICAM-1 (siCAM-1) from rheumatoid synovial tissue (RS) and its relation to sICAM-1 in synovial fluid (SF) and serum, and to study the expression of ICAM-1 in isolated cells of RS. sICAM-1 was determined by using the enzyme-linked immunosorbent assay (ELISA) and Western blot analysis in supernatants from RS cultured for short periods (n = 19), in SF (n = 7) and in serum (n = 19). ICAM-1 expression, vascularization and inflammatory infiltration (CD3, CD68, CD22) were characterized immunohistochemically in cytospin preparations (n = 18), cryosections (n = 18) and in conventionally stained paraffin sections (n = 19) of RS. The degree of RS vascularization was analysed morphometrically in immunohistochemically stained cryosections (factor VIII related antigen). We found 90-kD sICAM-1 in supernatants of cultured cells, in SF and in sera. sICAM-1 in cellular supernatant correlated significantly (P < 0.01) with SF sICAM-1. The amount of sICAM in cellular supernatants showed no correlation to the score of inflammatory infiltration, but correlated significantly (P < 0.001) with the vascularization index of RS. The percentage of ICAM-1-expressing cells correlated significantly (P < 0.001) with the percentage of CD68-positive macrophages, but not with CD3- and CD22-positive lymphocytes. Macrophages, multinucleated giant cells and endothelial cells exhibited a higher expression of ICAM-1 as compared to lymphocytes and fibroblasts. The differential expression of ICAM-1 on infiltrating leucocytes and resident cells of RS indicates a functional role of ICAM-1 in the local inflammatory process. SF sICAM-1 originated in RS, but serum sICAM-1 did not. Shedding of sICAM-1 by RS was independent of inflammatory infiltration, but depended on the degree of vascularization, indicating that endothelial cells are the major source of sICAM-1 in RS. Received: 14 November 1996 / Accepted: 3 January 1997     

Infiltrations of plasma cells in synovium are highly associated with synovial fluid levels of APRIL in inflamed peripheral joints of rheumatoid arthritis

Infiltration of plasma cells can be a histopathological hallmark of articular synovium with rheumatoid arthritis (RA). A proliferation-inducing ligand (APRIL) may have key roles in homeostasis and development of B cells, and the differentiation of B cells into plasma cells. This study was designed to explore the relationships between the infiltrations of plasma cells in synovium and the synovial fluid levels of APRIL in inflamed peripheral joints of RA. Synovium and synovial fluid were sampled from 21 RA patients underwent arthroscopic synovectomy for inflamed peripheral joints. The variants of rheumatoid synovium were classified into the follicular and diffuse synovitis by hematoxylin and eosin staining, and the infiltrations of plasma cells in rheumatoid synovium were quantified under the light microscope. The synovial fluid levels of APRIL were measured with the enzyme-linked immunosorbent assay. The mean number of infiltrating plasma cells in synovium and the mean synovial fluid level of APRIL were significantly increased in follicular synovitis compared with those in diffuse synovitis (P = 0.009, and P = 0.018, respectively), and there was a highly positive association between the infiltrations of plasma cells and the synovial fluid levels of APRIL among all of the RA patients (Rs = 0.776, P < 0.001). These findings suggest that the local production of APRIL may be associated with the ectopic lymphoid neogenesis in rheumatoid synovium and may have a role in contributing to the infiltration of plasma cells in synovium within inflamed peripheral joints of RA.     

白细胞介素-23在类风湿关节炎滑膜中的表达及意义

目的白细胞介素（IL）-23由IL-23p19和IL-12p40亚单位组成，它在一些自身免疫疾病发生过程中起着重要的作用。研究分析类风湿关节炎（RA）患者关节滑膜组织中IL-23p19蛋白及其mRNA的表达，旨在探讨其在RA发病中的意义。方法应用反转录-聚合酶链反应（RT—PCR）和免疫组织化学方法检测RA患者关节滑膜组织中IL-23p19基因和蛋白的表达。并与骨关节炎（OA）患者和健康人作对照研究。结果IL-23p19mRNA和蛋白在RA患者关节滑膜组织中表达明显增高．而在OA患者中低表达，正常对照组中无表达。结论IL-23p19在RA关节滑膜组织中高表达．提示IL-23可能直接参与了RA的发病过程。     

Demonstration of lymphatics in human synovial tissue

Summary Using a cocktail of monoclonal antibodies PAL-E and DE-U-10 (anti-desmin), combined in double labelling techniques with the lectin Ulex europaeus agglutinin I (UEAI), vessels consistent with lymphatics were demonstrated in normal human synovial tissue. These vessels were negative for the monoclonal cocktail and positive for UEAI, were thin-walled and were located close to deep arterioles and venules as expected. Elastin was not found to assist identification of lymphatics in synovium. In rheumatoid arthritic synovium no vessels staining in the manner of normal lymphatics were found. This may indicate absence or change of phenotype of this type of endothelium in disease.     

Expression of membrane-type matrix metalloproteinases in synovial tissue from patients with rheumatoid arthritis or osteoarthritis

We investigated the expression of membrane-type matrix metalloproteinase (MT-MMP) and matrix metalloproteinase (MMP) mRNAs in synovial tissue from patients with rheumatoid arthritis (RA, n = 5) or osteoarthritis (OA, n = 5) by Northern blot analysis. Northern analysis demonstrated strong expression of MT1-MMP, MT3-MMP, MMP-1, and MMP-3 and weak expression of MT2-MMP and MMP-8 in synovial tissue from patients with RA or OA. MT4-MMP was not detected. No significant difference was shown in the expression of MT-MMP mRNAs between RA and OA. Synovial tissue of RA or OA patients expressed MT-MMPs as well as MMPs. These results indicate that, in addition to MMPs, MT1-MMP, MT3-MMP, and probably MT2-MMP may play a role in the degradation of bone and cartilage matrix in RA and OA. Such information may provide a clue to the development of a novel therapeutic approach targeted on the prevention of joint destruction. Received: April 30, 2000 / Accepted: September 19, 2000     

Expression and citrullination of keratin in synovial tissue of rheumatoid arthritis

Keratin is the main component of cellular intermediate filaments, and its post-translational modification plays an important role in cell differentiation and apoptosis, as well as disease states. The conversion of peptidylarginine to citrulline, termed citrullination, is particularly involved in the pathogenesis of rheumatoid arthritis (RA). Immunohistochemistry using an antibody mixture that broadly recognized various keratin forms detected cytokeratin in many cells in the area lining the synovial membrane of RA. Furthermore, double immuno-florescent labeling showed that the cells expressing cytokeratin were also positive for citrulline when they were in the vicinity of extracellular deposits or approached the exterior of the synovial membrane. Western blot analysis demonstrated citrullination of keratin purified from RA synovial tissue by immuno-precipitation. The above results indicate the presence of citrullinated cytokeratin in synovial membranes in RA.     

Hyaluronic acid production in vitro by synovial lining cells from normal and rheumatoid joints.

Organ cultures and primary cell cultures were established from synovial tissue collected from patients with rheumatoid arthritis. Hyaluronic acid measured by the incorporation of [3H]glucosamine into the polysaccharide was found to be synthesised in the cultures immediately after transfer from in-vivo to in-vitro conditions. This was in contrast to the primary cultures established from cells isolated from normal joints. The latter cells did not synthesise any detectable hyaluronate. 90-100% of the cells in primary culture were found to be esterase positive, indicating their macrophage nature. The molecular weight of the hyaluronate produced by the pathological cells was low (approximately 50 000) compared with the molecular weight of hyaluronate found in joint fluid from normal or rheumatoid joints. Cell lines of fibroblasts established from rheumatoid joints and studied after four or seven passages also produced hyaluronate of low molecular weight. It is known that similar cell lines from normal joints produce a high molecular weight polymer.     

Correlation between synovial blood flow signals and serum vascular endothelial growth factor levels in patients with refractory rheumatoid arthritis

The objective of the study is to examine the relationship between synovial blood flow signals and vascular endothelial growth factor (VEGF) involved in angiogenesis by Doppler ultrasound. Twenty-one patients meeting the diagnostic criteria of the American College of Rheumatology (ACR) were enrolled in this study. Doppler ultrasound signals of blood flow in the wrist synovial membrane were measured and classified into three grades: grade 1 = no flow; grade 2 = mild flow; grade 3 = intense flow. A significant correlation was observed between blood flow signals in the wrist synovial membrane and serum VEGF levels (r = 0.5681, P = 0.0072). These results suggest that the measurement of Doppler ultrasound signals of blood flow in the wrist synovial membrane is useful in the evaluation of angiogenesis.     

Interleukin 1 activity in the synovial fluid of patients with rheumatoid arthritis

Summary The synovial fluids (SF) of patients with rheumatoid arthritis (RA) were investigated for their effects on thymocytes of C3H/HeJ mice. Of the 20 SF tested, 17 (85%) showed an augmentation of the phytohaemagglutinin (PHA) induced thymocyte stimulation. Out of 16 SF of patients with osteoarthrosis, such an activity was detected in only one (6.25%). Further characterisation of the amplification factor revealed that (1) the SF of RA patients augmented both the PHA and the Concanavalin A response of the thymocytes (2) in the absence of mitogens, SF-treated thymocytes showed an increased uptake of ³H-thymidine, (3) the SF did not propagate the growth of an interleukin 2 dependent ovalbumin specific T cell clone, but (4) the SF were found to be required for optimal interleukin 2 release by spleen cells stimulated with suboptimal doses of lectin. Based on these biological effects the factor in the SF of RA patients is suggested to represent an interleukin 1 (IL-1). IL-1 produced in cultures by activated macrophages has been shown to stimulate T and B cell functions and to induce the production of collagenase and prostaglandins by cultured synovial cells. Both properties of IL-1 could be relevant in the pathogenesis of RA.