Nerve distribution in synovium of osteoarthritic knees

Neural elements are widely distributed in synovium of osteoarthritic knees. In medial compartmental osteoarthritic knees, medial synovium is exposed to mechanical stimuli due to osteophytes and lateral thrust, which may accumulate neuropeptides, especially substance P, in free nerve endings. Free nerve endings containing a large amount of substance P may provoke pain sensation in synovium, and release substance P to the surrounding tissue in subsynovial tissue, which induces synovitis. Neural system may modulate synovitis as well as pain pathway in osteoarthritis of the knee.     

Thrombin receptor expression in rheumatoid and osteoarthritic synovial tissue.

OBJECTIVE: To investigate the possibility that synovial cells might respond to thrombin in the inflamed human joint, using immunohistochemical detection of thrombin receptors. METHODS: Frozen sections of synovial membrane from 20 patients with rheumatoid arthritis, 16 with osteoarthritis, and four normal controls were stained using a monoclonal antibody to the human thrombin receptor. Sections were also double stained for both receptors and non-specific esterase. RESULTS: Receptor positive cells were present in rheumatoid synovia, with some cells also staining positively for non-specific esterase. In contrast, both osteoarthritic and normal synovia contained very few cells expressing receptors. CONCLUSIONS: Thrombin may mediate important pathological changes during chronic inflammatory joint disease.     

Modulation of cartilage proteoglycan synthesis by osteoarthritic synovium

Conditioned media derived from explant cultures of human osteoarthritic synovial tissue have been shown to contain preformed and newly synthesized factors of variable molecular weight which are capable on a concentration dependent basis of modulating cartilage proteoglycan metabolism. Anabolic inhibitory and stimulatory activity often appeared to coexist, a reversible down-regulation usually dominating in unfractionated preparations. The size of newly synthesized proteoglycan aggregates and monomers and the length of glycosaminoglycan chains produced in the presence of conditioned media were normal. The pattern of anabolic response did not necessarily correlate with the presence of catabolic inducing activity.     

类风湿关节炎滑膜组织中细胞外基质金属蛋白酶诱导因子的研究

目的研究类风湿关节炎(RA)患者滑膜组织中细胞外基质金属蛋白酶诱导因子(EMM-PRIN)的表达,探讨其在RA致病中的作用。方法对20例RA患者膝关节滑膜组织标本采用免疫组织化学染色和半定量反转录-聚合酶联反应(RT-PCR)法,观察RA滑膜组织中EMMPRIN的蛋白及mRNA表达。10例骨关节炎OA滑膜作为对照。结果RA滑膜内衬层的单核细胞、成纤维细胞中EMMPRIN阳性表达广泛,RA组EMMPRIN的免疫反应明显强于对照组(P<0.01)。14例RA、2例OA滑膜标本EMM-PRINmRNA表达阳性,EMMPRINmRNA表达水平RA也明显高于OA组。结论滑膜中过度表达的EMMPRIN通过上调MMPs促进关节软骨的破坏。因此选择性地抑制EMMPRIN生物活性,可能是治疗RA的新途径。     

Immunohistology of rheumatoid nodules and rheumatoid synovium.

The immunohistological features of rheumatoid nodules and rheumatoid synovium were examined using monoclonal and polyclonal antibodies raised against macrophages, HLA-DR, leucocyte common antigen, and immunoglobulin components. The palisading cells surrounding the necrotic centre of the rheumatoid nodule were shown to be HLA-DR positive leucocytes, mostly histiocytes. The inflammatory infiltrate associated with rheumatoid nodules showed many immunohistochemical similarities to that of rheumatoid synovium, including a preponderance of IgG positive plasma cells, and a similar number and microanatomical pattern of distribution of HLA-DR positive cells. The significance of these findings for the cellular immunopathology and aetiology of the rheumatoid lesion is discussed.     

The role of peroxynitrite in cyclooxygenase-2 expression of rheumatoid synovium

OBJECTIVE: Reactive oxygen intermediates play an important role in the inflammatory processes of rheumatoid arthritis. Cyclooxygenase-2 is an inducible form of an enzyme involved in prostanoid biosynthesis. This study linked peroxynitrite (ONOO-) to the signaling pathways that induce COX-2. RESULTS: Exposure of rheumatoid synovial cells to peroxynitrite resulted in COX-2 protein expression in a dose-dependent manner. RT-PCR analysis also demonstrated that COX-2 mRNA was induced in peroxynitrite-treated rheumatoid synovial cells. Dexamethasone markedly inhibited this peroxynitrite-mediated COX-2 expression at therapeutic concentrations. CONCLUSION: This study demonstrates that oxidant stress is an important inducer of COX-2 in rheumatoid synovium. This induction may contribute to the amplification of prostanoids in the rheumatoid inflammatory process.     

Laser-mediated microdissection facilitates analysis of area-specific gene expression in rheumatoid synovium

OBJECTIVE: Current approaches to analyzing gene expression in rheumatoid arthritis (RA) synovium are based on RNA isolated either from cultured synovial cells or from synovial biopsy specimens. This strategy does not, in general, allow distinction of specific gene expression between cells originating from different synovial areas, due to potential mixture of expression profiles. Therefore, we established the combination of laser-mediated microdissection (LMM) and differential display to analyze profiles of gene expression in histologically defined areas of rheumatoid synovium. The present study was undertaken to establish parameters for this technique and assess its usefulness for gene expression analysis. METHODS: Cryosections derived from RA synovial tissues were used to obtain cell samples from synovial lining versus sublining, using a microbeam laser microscope. RNA was isolated and analyzed by nested RNA arbitrarily primed-polymerase chain reaction (RAP-PCR) for differential display fingerprinting. Differentially expressed bands were cut out, and PCR products were eluted, cloned, and sequenced. Differential expression of identified sequences was confirmed by in situ hybridization and immunohistochemistry analysis. RESULTS: Microdissected sections of RA synovial tissue containing approximately 600 cells yielded enough RNA to produce a reproducible RNA fingerprint pattern. Several genes could be identified as being expressed differentially between the synovial lining and the sublining, and their expression could be confirmed at the messenger RNA and protein levels. CONCLUSION: The combination of LMM and RAP-PCR presents a valuable tool to obtain novel insights into the area-dependent differential regulation of gene expression in RA synovium. Both known and previously unknown genes were revealed with this technique. This study is the first to demonstrate the potential of this analytic strategy in the investigation of a nonmalignant, multifactorial, inflammatory disease.     

Significant correlation between thrombospondin 1 and serine proteinase expression in rheumatoid synovium

Objective. Thrombospondin 1 (TSP1) is a potent active site inhibitor of leukocyte elastase and cathepsin G. This effect is markedly dependent on the disulfidebond conformation of TSPI, with one isoform, TSPI^0.1, being the most potent. The aims of this study were to examine the expression of different disulfide-bonded isoforms of TSP1 in inflammatory environments in which elastase and cathepsin G are present in variable amounts, and to determine the relationship between these proteinases and their potential inhibitor. Methods. Immunohistochemical staining and histomorphometric analysis were used to examine adjacent sections of synovial tissue from patients with rheumatoid arthritis (RA), osteoarthritis (OA), and meniscal trauma (MT), for expression of TSPl and the TSPl^0.1 isoform, elastase, cathepsin G, and chymase. Results. TSPl localized to vessels and cells within the synovium. TSPl expression was highly up-regulated in RA (mean density 98 cells and vessels / mm², compared with 13 / mm² in OA and 17 / mm² in MT). The TSPl^0.1 isoform was found virtually exclusively in RA, with 44% of vascular TSPl staining being due to the TSPl^0.1 isoform in RA, as compared with 7% in OA (P = 0.0047). Elastase- and cathepsin G-positive cells were abundant in RA, with mean densities of 106 cells / mm² and 103 cells / mm², respectively, compared with 2 cells / mm² and 11 cells / mm² in OA. There was a wide range of both TSPl and proteinase expression within the RA group, but samples containing large numbers of elastase- and cathepsin G-positive cells also showed high expression of TSPl, especially TSPl^0.1,. A strong correlation was found between elastase or cathepsin G densities and TSPl^0.1 expression in blood vessels (r = 0.86 and r = 0.76 respectively, P < 0.01). Conclusion. TSPl^0.1, with the most potent inhibitory activity in vitro, is specifically up-regulated in RA, and this up-regulation is in proportion to the numbers of surrounding leukocytes containing elastase and cathepsin G. One role of TSPl may be to act as a matrix-based regulator of leukocyte-derived serine proteinases in vivo.     

Comparison of phenotype expression by mononuclear phagocytes within subcutaneous gouty tophi and rheumatoid nodules

Summary The mononuclear phagocyte infiltrate which occupies the gout tophus has been compared with that of the subcutaneous rheumatoid nodule. In the gout tophus, macrophage migration appears to be at a relatively low level and effectively terminates once these cells have been recruited into the corona. In the nodule the evidence suggests that both macrophage and granulocyte populations continuously migrate towards, and are progressively incorporated into, the necrotic centres. These observations indicate that chemotactic activity in rheumatoid nodules is at a higher level than in gout tophi, or that the rheumatoid mononuclear phagocyte is more responsive to such stimuli.     

Low levels of apoptosis and high FLIP expression in early rheumatoid arthritis synovium

OBJECTIVES: To define synovial apoptosis with respect to disease duration, inflammatory cell type, FLIP (FLICE-like inhibitory protein), and cytokines expression in patients with rheumatoid arthritis (RA). METHODS: Synovial biopsy specimens from 11 patients with longstanding RA (median disease duration 21 years) and eight with early RA (median disease duration five months) were investigated. Apoptosis (TUNEL method combined with morphological analysis), cell surface markers (CD3, CD68), cytokines (interleukin (IL) 1alpha, IL1beta, tumour necrosis factor alpha, and IL6), and FLIP expression were evaluated. Computer assisted image analysis was used for quantification. RESULTS: The apoptosis level in RA synovium was significantly higher in the group of patients with longstanding RA than in the patients with early RA (8.8% v 0.6%, p=0.001), while the number of macrophages and FLIP expression were higher in the group with early disease than in the group with longstanding RA (16.2% v 8.3%, p=0.02 and 31.1% v 0.2%, p=0.001 respectively). All three markers correlated significantly with disease duration (R=-0.7, p<0.001 for FLIP, R=0.6, p=0.001 for apoptosis, and R=-0.5, p<0.05 for CD68). Cytokine expression and T cell score were not significantly different in early RA from longstanding RA. No differences were seen between patients treated or not treated with corticosteroids or between patients treated or not treated with disease modifying antirheumatic drugs. CONCLUSIONS: The findings suggest that RA synovial macrophages are resistant to apoptosis in early RA and express high levels of FLIP. During natural or drug modified disease progression the apoptotic mechanism may be restored with a specific increase of synovial apoptosis in patients with longstanding arthritis.     

Non-Hodgkin's lymphoma of the synovium simulating rheumatoid arthritis

Skeletal involvement in patients with non-Hodgkin's lymphoma (NHL) is common, although direct involvement of the joints is unusual. We describe 2 adults who presented with features suggestive of a diagnosis of rheumatoid arthritis, but who were found to have diffuse NHL of the synovium. Results of a review of the literature, and assessment of the few similar cases in which NHL presented in the joint, suggest that the lymphoma may mimic either a monarticular or polyarticular synovitis, without lymphadenopathy or hepatosplenomegaly. Radiographic demonstration of associated bone destruction is the best evidence for non-Hodgkin's lymphomatous arthropathy in patients with rheumatic symptoms.     

核因子κB在类风湿关节炎滑膜组织中的表达与意义

目的检测核因子κB(NF-κB)及白细胞介素(IL)-1β、基质金属蛋白酶(MMP)-9在类风湿关节炎(RA)、骨关节炎(OA)及正常滑膜组织中的表达差异。方法反转录-聚合酶链反应(RT-PCR)检测46例滑膜组织(RA17例,OA24例,正常5例)中p65、p50、NF-κB抑制因子(IκB)及IL-1β、MMP-9的mRNA水平。免疫组织化学检测39例滑膜组织(RA14例,OA21例,正常4例)中p65的表达情况。对8例RA、6例OA滑膜组织进行滑膜细胞培养,提取核蛋白进行免疫印迹,检测p65含量。结果RA组p65、IL-1β、MMP-9的mRNA水平显著高于正常对照组(分别为P<0.05、P<0.01、P<0.05),与OA组比较差异无显著性。RA、OA与正常组之间p50、IκB的mRNA水平差异无显著性。NF-κBp65免疫组织化学染色组显示RA滑膜衬里层细胞、衬里下层浸润的炎症细胞、血管内皮细胞均有着色。RA组NF-κB活性系数显著高于OA组、正常对照组(P<0.001)。免疫印迹发现RA滑膜细胞核蛋白中p65含量显著高于OA组(P<0.05)。结论RA滑膜组织中NF-κB的表达与活化水平显著高于OA及正常滑膜组织。RA组IL-1β与MMP-9的mRNA水平显著高于正常对照。