Th17 Cells in Immunopathogenesis and treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by the sequestration of various leukocyte subpopulations within both the developing pannus and synovial space. The chronic nature of this disease results in inflammation of multiple joints, with subsequent destruction of the joint cartilage and erosion of bone. Identification of T helper (Th)17 cells led to breaking the dichotomy of the Th1/Th2 axis in immunopathogenesis of autoimmune diseases such as RA, and its experimental model, collagen‐induced arthritis (CIA). Th17 cells produce cytokines, including interleukin (IL)‐17, IL‐6, IL‐21, IL‐22 and tumor necrosis factor (TNF)‐α, with pro‐inflammatory effects, which appear to have a role in immunopathogenesis of RA. Regarding the wide ranging production of pro‐inflammatory cytokines and chemokines by Th17 cells, it is expected that Th17 cell could be a potent pathogenic factor in disease immunopathophysiology. Thus the identification of effector mechanisms used by Th17 cells in induction of disease lesions may open new prospects for designing a new therapeutic strategy for treatment of RA.     

Interleukin-15 inhibits sodium nitroprusside-induced apoptosis of synovial fibroblasts and vascular endothelial cells

OBJECTIVE: One of the pathologic hallmarks of juvenile rheumatoid arthritis (JRA) is a tumor-like expansion of inflamed synovial tissue, or pannus, which causes much of the joint damage in this disease. The expansion of pannus is supported by extensive formation of new blood vessels. We have previously shown that revascularization of minced JRA synovial tissues engrafted into SCID mice correlated with the intensity of inflammatory activity in the tissues and with interleukin-15 (IL-15) expression. Since synovial vascular endothelial cells (VECs) expressed IL-15 receptors, the present study was undertaken to investigate the hypothesis that IL-15 might play a role in neovascularization of the pannus. METHODS: To evaluate IL-15 for possible angiogenic activity, we assessed the ability of recombinant human IL-15 (rHuIL-15) to induce VEC growth directly and to stimulate synovial cells to produce endothelial growth factors. Since IL-15 had been shown to inhibit apoptosis of certain immune cells, we were also interested in whether it might have similar effects on VECs. Apoptosis was induced by addition of sodium nitroprusside (SNP) at 1-2 mM to >80% confluent primary VECs, and numbers of apoptotic cells were determined by annexin V assay. RESULTS: Addition of rHuIL-15 at 10-100 ng/ml to primary synovial fibroblast cultures failed to up-regulate expression of vascular endothelial growth factor and angiopoietin 1 by these cells. Although rHuIL-15 failed to induce a mitogenic response of VECs, it promoted survival of these cells on Matrigel. Preincubation of VECs with rHuIL-15 at 50 ng/ml significantly reduced the proportion of VECs undergoing apoptosis. CONCLUSION: IL-15 promotes survival of VECs on Matrigel and inhibits SNP-induced apoptosis of endothelial cells. We hypothesize that this mechanism may be relevant to the stabilization of newly formed vascular structures in JRA synovium.     

Der Interleukin-1-Rezeptorantagonist Anakinra (Kineret®) in der Behandlung mit rheumatoider Arthritis

New treatment strategies in rheumatoid arthritis are targeted to interfere with critical mediators of inflammation. Proinflammatory cytokines like IL-1 beta and TNFalpha play a crucial role in induction and maintenance of synovitis, pannus formation and bone and cartilage destruction. Within a few years, these morphological changes may lead to joint destruction and consecutively to functional impairment.Since April 2002 a recombinant human interleukin-1 receptor antagonist (Anakinra) is available in Germany for treatment of patients with rheumatoid arthritis. Anakinra (Kineret(R)) is approved for therapy in combination with methotrexate and should be applied according to guidelines established by the German Rheumatology Society for the use of biologicals in treatment of patients with rheumatoid arthritis.The approval of anakinra as a new therapeutic is based on data obtained in large multicenter, placebo-controlled, and randomised trials in comparison to placebo. Treatment of Anakinra as monotherapy or in combination with methotrexate lead to significant improvement of signs and symptoms of disease as measured by the ACR 20 (or more) response and was associated with a slower radiographic progression with regard to joint space narrowing and development of erosions. Anakinra showed a favourable safety profile with injection side reactions as the predominant side effect that occurs in 70% of patients usually after 10-12 days of treatment and that are mostly mild to moderate and self-limiting. Patients with previous pneumonia or other risk factors for pulmonary infections such as chronic obstructive lung disease seem to show a slightly increased risk of developing infectious complications of the bronchopulmonary system while being on anakinra and should be monitored appropriately. Combining IL-1ra treatment with the use of anti-TNF agents showed an increased risk of infectious complications in clinical studies and is not recommended at present. Studies are currently assessing the use of anakinra for treatment of other rheumatic diseases like psoriatic arthritis, juvenile arthritis or spondylarthropathy.     

Synovial extracellular matrix: partial characterization of matrix components and identification of type VI collagen molecular forms

Alterations in the synovial extracellular matrix (ECM) in chronic inflammatory arthritis may affect synoviocyte adhesion and may be important in the regulation of pannus growth and invasion. Immunohistochemical examination of synovium has revealed enhanced deposition of fibronectin and collagen in interstitial areas consistent with expansion of the ECM in inflammatory arthritis. In order to functionally characterize the ECM of synovium, synovial extracellular matrix was purified from pannus removed at joint replacement surgery. A prominent 140 Kd 6M guanidine extractable component was found to mediate synoviocyte adhesion in a cell-blotting assay. This 140 Kd component was identified as a form of type VI collagen. Type VI collagen appears to be a significant component of synovial ECM.     

Development and characteristics of pannus-like soft tissue in osteoarthritic articular surface in rat osteoarthritis model

OBJECTIVES: Pannus is invasive granulation tissue found on the articular cartilage having rheumatoid arthritis (RA). However, pannus-like tissue has also been found in osteoarthritis (OA). Our previous study showed that pannus-like tissue in OA (OA pannus) was frequently found in human OA samples. The purpose of the study is to investigate the development and the characteristics of OA pannus in a rat OA model. DESIGN: Ligaments of the knee joint were transected in Wister rats to induce OA. The knee joints were removed at weeks 1, 2, 4 and 6, and subjected to histological study. Samples were stained with hematoxylin and eosin (HE), Safranin-O and immuno-stained for vimentin, CD34, type II collagen and MMP-3. The whole knee joint of OA rats was implanted in SCID mice and kept for a further 3 weeks. Then the histological findings were evaluated in HE sections. RESULT: OA pannus appeared at week 2 and extend over the articular surface. OA pannus cells were positive for vimentin and/or CD34. At week 6, a part of articular surface was restored with matrix. OA pannus cells expressed MMP-3 as well as type II collagen. Histological study of rat OA knees implanted in SCID mice showed that OA pannus cells filled the joint space and invaded articular cartilage. CONCLUSIONS: The presence of OA pannus was found in a rat OA model and its features were similar to those in human OA. OA pannus had both catabolic and reparative features, and the latter feature were speculated to be dominant in the later phase of the disease under a certain environmental condition.     

磁共振成像在类风湿关节炎患者膝关节病变研究中的意义

目的　初步探讨磁共振成像 (MRI)技术在类风湿关节炎 (RA)患者膝关节病变临床诊断中的应用价值。方法　对 2 0例RA患者的 34个膝关节进行多种序列成像并分析其MRI表现。结果　MRI可清晰显示RA膝关节的滑膜增生及血管翳形成、关节软骨破坏、骨质受侵、关节囊积液、半月板及韧带异常、窝囊肿形成以及皮下结节等改变 ,并能通过血管翳的信号和强化程度判断疾病是否处于活动期。结论　与X线相比 ,MRI对RA的骨质侵蚀破坏更为敏感 (P <0 0 1)。MRI能直接显示RA患者膝关节不同时期的各种改变 ,有助于疾病的早期诊断和临床分期     

FK506 attenuates developing and established joint inflammation and suppresses interleukin 6 and nitric oxide expression in bacterial cell wall induced polyarthritis

OBJECTIVE: To determine the efficacy of therapeutic administration of FK506 (Tacrolimus) in suppressing developing and established joint inflammation, proinflammatory cytokine expression, and nitric oxide (NO) production in peptidoglycan-polysaccharide (PG/PS) induced experimental polyarthritis in rats. METHODS: Chronic joint inflammation was induced by intraperitoneal injection of PG/PS, and joint inflammation was quantified using arthritis index and paw volume. Serum and joint levels of interleukin 6 (IL-6) were measured by bioassay and Western blot analysis respectively, and serum levels of NO production were determined by the Griess procedure and the expression of the inducible isoform of nitric oxide synthase (i-NOS) in the joints was determined by Western blot analysis. RESULTS: Arthritis induced by PG/PS is biphasic, progressing through an initial acute phase and a remission phase, which is followed by a persistent chronic phase. Daily administration of FK506 initiated during the remission phase significantly attenuated the onset and development of chronic joint inflammation. We observed a significant reduction in joint inflammation and swelling, an apparent suppression of pannus development, and minimal erosive damage to the articular cartilage and subchondral bone. Fully established chronic joint inflammation was also ameliorated by daily administration of FK506. Joint swelling and inflammation was significantly reduced by 5 days post-treatment with FK506 and the erosive activity associated with the pannus appeared diminished. The elevated expression of IL-6 and NO characteristic of chronic joint inflammation in the serum and in joint tissue was significantly reduced by FK506 treatment. CONCLUSION: Therapeutic administration of FK506 has a profound antiinflammatory effect on the development of the chronic, erosive arthritis induced by PG/PS. This attenuation in joint inflammation was associated with suppression of IL-6 and NO production systemically and locally in the joints. Our data suggest that FK506 may be effective in the treatment of chronic joint inflammation associated with rheumatoid arthritis.     

Co-existent sickle cell disease and juvenile rheumatoid arthritis. Two cases with delayed diagnosis and severe destructive arthropathy

We describe 2 pediatric patients with sickle cell disease (SCD) who developed seropositive juvenile rheumatoid arthritis (JRA). Both patients have severe joint damage, the compound effect of both disease processes. The bone and cartilage destruction, which poses serious therapeutic challenges, highlights the difficulty of making a diagnosis of chronic inflammatory disease in the setting of SCD. There may be a correlation between increased levels of tumor necrosis factor-alpha in the synovial tissue of joints damaged by arthritis and local sickling. The resultant ischemia and corresponding inflammatory infiltrates could in turn worsen existing synovial proliferation and cartilage destruction as well as trigger further sickling.     

Synergy between anti-CD4 and anti-tumor necrosis factor in the amelioration of established collagen-induced arthritis.

Anti-CD4 treatment is reported to prevent collagen-induced arthritis if administered before the onset of clinical disease but has relatively little effect on established arthritis. In contrast, we have recently shown that anti-tumor necrosis factor alpha/beta (TNF) treatment reduces the severity of established arthritis. We now study the effect of combined administration of anti-CD4 monoclonal antibody (YTS 191.1.2/YTA 3.1.2) and anti-TNF monoclonal antibody (TN3-19.12) in established arthritis. Anti-CD4 treatment caused some reduction in paw-swelling but did not significantly prevent joint erosion. A suboptimal dose of anti-TNF alone had no significant effect on arthritis. In contrast, anti-CD4 plus suboptimal anti-TNF significantly reduced paw-swelling, limb involvement, and joint erosion. As previously reported, an optimal dose of anti-TNF alone inhibited paw-swelling, limb involvement, and joint erosion. However, optimal anti-TNF combined with anti-CD4 caused significantly greater reductions in paw-swelling and joint erosion than those achieved by optimal anti-TNF alone. Coadministration of anti-CD4 was also effective in preventing an antibody response to the hamster anti-TNF antibody, which may have implications for long-term therapy in human disease. Thus anti-CD4 acts synergistically with anti-TNF in ameliorating established collagen-induced arthritis and this combined therapeutic approach may provide effective long-term control of rheumatoid arthritis.     

Mechanisms of Disease: angiogenesis in inflammatory diseases

Angiogenesis, the development of new vessels, is an important process in health and disease. The perpetuation of neovascularization in inflammatory diseases, such as rheumatoid arthritis, spondyloarthropathies and some systemic autoimmune diseases, might facilitate the ingress of inflammatory cells into the synovium and, therefore, stimulate pannus formation. Disorders associated with perpetuated neovascularization are considered to be angiogenic inflammatory diseases. Several angiogenic mediators, including growth factors, cytokines, matrix metalloproteinases, matrix macromolecules, cell adhesion receptors, chemokines and chemokine receptors, have been implicated in the process of capillary formation. There is a regulatory network in inflamed tissues that is involved in the upregulation or downregulation of angiogenesis. Endogenous angiostatic factors downregulate neovascularization and might act as angiostatic agents. Furthermore, angiogenesis might be targeted by several specific approaches that could be therapeutically used to control inflammatory diseases.     

A型滑膜细胞与类风湿关节炎血管新生

类风湿关节炎(RA)是一种常见的多系统性炎症性自身免疫性疾病.RA最主要病理特征是关节滑膜血管新生和对关节破坏力极强的血管翳形成.血管的新生是个复杂的过程,多种细胞及其所分泌的细胞因子参与了此过程.近来大量的研究表明,A型滑膜细胞即滑膜巨噬细胞在RA病理过程中起着非常重要的作用,其参与了炎症和血管新生的整个过程.A型滑膜细胞表达黏附分子、趋化因子受体和多种表面抗原物质,还能分泌产生大量的细胞因子、生长因子和其它化学活性物质.它们在RA滑膜病理过程中起着关键性作用.因此,A型滑膜细胞可能将成为RA治疗很好的靶点.     

The rheumatoid knee before and after arthrocentesis and Prednisolone injection: Evaluation by Gd-enhanced MRI

Summary In patients with rheumatoid arthritis, intraarticular injection of corticosteroids is an accepted means of treating a symptomatic joint. It has previously been impossible to precisely quantitate the effects of these injections on synovial effusion and pannus. Magnetic resonance imaging (MRI) is a safe, effective means of evaluating joint anatomy, and the use of intravenous gadolinium (Gd)-containing contrast allows clear differentiation of fluid from abnormal synovial tissue. The current study utilized MRI with Gd-labeled diethylene-triamene pentacetic acid (Gd-DTPA) contrast to evaluate serial changes in 6 knees of 6 patients with rheumatoid arthritis, following arthrocentesis and intraarticular injection of prednisolone. One week after the corticosteroid was injected, 2 patients had reduction of pannus width to 20% and 68% of baseline measurements. In these same individuals, follow-up sagittal views showed decreases of total effusion and fluid-plus-pannus width. The other 4 patients, who were followed for 4 weeks, had minimal changes in fluid and synovium. Gd-DTPA-enhanced MRI permits precise assessment of effects of intraarticular injections on synovial fluid and pannus in the rheumatoid knee.     

Regulation of angiogenesis by the C-X-C chemokines interleukin-8 and epithelial neutrophil activating peptide 78 in the rheumatoid joint

OBJECTIVE: Angiogenesis, the growth of new blood vessels, is vital to the ingress of inflammatory leukocytes in rheumatoid arthritis (RA) synovial tissue and to the growth and proliferation of RA pannus. The factors that mediate the growth of new blood vessels have not been completely defined. This study examined the ability of Glu-Leu-Arg (ELR)-containing chemokines to induce angiogenesis in the RA joint. METHODS: To reflect angiogenic activity in vivo, we selected a model using whole human synovial tissue rather than isolated cells. Tissues were examined by immunohistochemistry and enzyme-linked immunosorbent assay, and tissue homogenates were immunoneutralized and assayed for their ability to induce endothelial cell chemotaxis and rat corneal neovascularization. RESULTS: Cells expressing interleukin-8 (IL-8) and epithelial neutrophil activating peptide 78 (ENA-78) were located in proximity to factor VIII-related antigen-immunopositive endothelial cells. RA homogenates produced more IL-8 and ENA-78 compared with normal synovial tissue homogenates. Moreover, homogenates from RA synovial tissue produced significantly more chemotactic activity for endothelial cells in vitro and angiogenic activity in the rat cornea in vivo than did normal synovial tissue homogenates. The effects of IL-8 and ENA-78 accounted for a significant proportion of the chemotactic activity of endothelial cells and angiogenic activity found in RA synovial tissue homogenates. CONCLUSION: These results indicate that the ELR-containing chemokines IL-8 and ENA-78 are important contributors to the angiogenic activity found in the inflamed RA joint. It is possible that efforts aimed at down-regulating these chemokines offer a novel targeted therapy for the treatment of RA.     

Evaluation of pannus and vascularization of the metacarpophalangeal and proximal interphalangeal joints in rheumatoid arthritis by high-resolution ultrasound (multidimensional linear array).

OBJECTIVE: To evaluate the extent of intraarticular vascularization and pannus formation in metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints of patients with rheumatoid arthritis (RA) by high-resolution ultrasound (US). METHODS: A newly developed, high-resolution multidimensional linear array US was utilized to obtain longitudinal and transverse scans of joints with active RA (n = 21), moderately active RA (n = 39), or inactive RA (n = 93), and of joints from healthy controls (n = 120). RESULTS: Healthy joints had no detectable pannus, whereas pannus could be detected in 52% of the joints with active RA, 82% of the joints with moderately active RA, and 67% of the joints with inactive RA. There was a significant difference in vascularization in the joints of all subgroups of RA patients and those of healthy subjects (P < 0.001). Moreover, vascularization differed significantly among the RA subgroups: inactive versus moderately active RA (P < 0.02) and inactive versus active RA (P < 0.05). Both pannus and vascularization appeared to be localized preferentially on the radial side of the joints. CONCLUSION: Evaluation of pannus and the extent of vascularization within the joints of patients with RA by high-resolution US might be helpful in the assessment of disease activity, and thus influence therapeutic strategies.     

Amelioration of collagen-induced arthritis in DBA/1J mice by recombinant TSG-6, a tumor necrosis factor/interleukin-1-inducible protein

OBJECTIVE: To examine the effect of recombinant TSG-6 on collagen-induced arthritis (CIA) in DBA/1J mice. TSG-6 is a tumor necrosis factor (TNF)/ interleukin-1 (IL-1)-inducible hyaluronan-binding protein produced by synovial cells and chondrocytes that is present in synovial fluids of patients with rheumatoid arthritis. METHODS: To determine the effect of TSG-6 on chronic inflammatory joint disease, we induced CIA in DBA/1J mice by immunization with bovine type II collagen. Animals were treated with 12 intraperitoneal doses of 200 microg of recombinant TSG-6, beginning 3 days before the expected onset of disease symptoms. Progression of arthritis was monitored by determining the disease incidence, arthritis index, and footpad swelling. Levels of IgG1, IgG2a, and IgG2b antibodies against bovine and murine type II collagen and serum concentrations of IL-6 were determined at various time points. Histologic examination of affected joints was performed approximately 20 days after the onset of arthritis. RESULTS: Treatment with recombinant TSG-6 protein had a potent ameliorative effect, manifested by decreases in the disease incidence, arthritis index, and footpad swelling. Histologic examination of affected joints in TSG-6-treated animals revealed little pannus formation and cartilage erosion, features which were conspicuous in control mice. Animals treated with recombinant TSG-6 developed significantly reduced levels of IgG1, IgG2a, and IgG2b antibodies against bovine and murine type II collagen. CONCLUSION: The antiinflammatory effect of the TNF/IL-1-inducible TSG-6 protein in murine CIA suggests a role for this protein as an endogenous regulator of the inflammatory process.     

Early abnormalities of pisiform and triquetrum in rheumatoid arthritis.

Erosions on the triquetrum and pisiform are frequent in early rheumatoid arthritis and occur characteristically at 3 sites. (a) A shallow erosion on the proximal medial triquetral "bare" area is related to synovial proliferation at the margin of the radiocarpal cavity, although compressive forces from an adjacent long ulnar styloid may be contributory; (b) an erosive abnormality on the distal medial triquetrum is related to synovial proliferation along the margin of the midcarpal joint; and (c) ring-like erosions on apposing surfaces of the triquetrum and pisiform are produced by pannus within the pisiform-triquetral compartment.     

Efficacy of daily compared to intermittent administration of IL-1Ra for protection against bone and cartilage destruction in collagen-challenged mice

OBJECTIVE: To investigate the protective effect of interleukin-1 receptor antagonist (IL-1Ra) on bone and cartilage destruction in the induction phase of collagen-induced arthritis (CIA), an animal model of rheumatoid arthritis (RA). METHODS: DBA/1J mice were immunized with type II collagen for induction of collagen-induced arthritis (CIA) and simultaneously given different intraperitoneal doses of IL-1Ra daily, thrice weekly or once a week. Clinical symptoms of arthritis were noted daily and assessed using a scoring system during the course of disease. Bone and cartilage destruction in the mice was assessed by radiographic and histological methods respectively. RESULTS: Mice injected with IL-1Ra daily were completely protected from the occurrence of arthritis after immunization with type II collagen. Moreover, these mice were also protected against bone and cartilage destruction. However, weekly or thrice weekly treatment with IL-1Ra had no effect on arthritis and bone and cartilage destruction. CONCLUSION: Daily administration of recombinant IL-1Ra, injected at the same time as arthritis induction, is effective in blocking the occurrence of inflammatory as well as destructive changes in CIA. Daily bolus injections of IL-1Ra may therefore be useful for protection against joint damage following minor joint injury, whereas the maintenance of appropriate blood levels of the antagonist may be critical for its therapeutic effect on chronic inflammatory arthritis.     

Electron microscopic studies of the cartilage-pannus junction in rheumatoid arthritis.

The junction between pannus and cartilage was examined in the rheumatoid joint. Three types of cartilage-pannus junction were observed. In one, proliferating small blood vessels, surrounded by highly cellular infiltrates, penetrated deeply into the cartilage. Degeneration of the cartilage was observed around the cellular accumulations. In the second, phagocytic and fibroblastic cells invaded the cartilage. In the third, fibrous pannus overlay the cartilage. Lysis of cartilage by infiltrating cells appeared to be a major cause of cartilage erosion in rheumatoid arthritis.     

Power Doppler sonography in the assessment of synovial tissue of the knee joint in rheumatoid arthritis: a preliminary experience

OBJECTIVE: To investigate the intra-articular vascularisation of the synovial pannus in the knee of patients with rheumatoid arthritis (RA) with power Doppler ultrasonography (PDS) and an echo contrast agent and correlate the area under the time-intensity curves with the clinical findings and laboratory measures of disease activity. METHOD: Forty two patients with RA (31 women, 11 men) with history and signs of knee arthritis, classified according to a modified index of synovitis activity (active, moderately active, and inactive), were studied. Clinical and functional assessment (number of swollen joints, intensity of pain, general health-visual analogue scale, disability index-Health Assessment Questionnaire, Ritchie articular index) and a laboratory evaluation were made on all patients. Disease activity was evaluated using the disease activity score (DAS) and the chronic arthritis systemic index (CASI) for each patient. All patients were examined with conventional ultrasonography and PDS before injection of intravenous ultrasound contrast agent (Levovist). The quantitative estimation of the vascularisation of the synovial membrane was performed with time-intensity curves and calculation of the area under the curves. RESULTS: The mean (SD) value of the area underlying time-intensity curves was 216.2 (33.4) in patients with active synovitis, 186.8 (25.8) in patients with moderately active synovitis, and 169.6 (20.6) in those with inactive synovitis. The mean value of the areas differed significantly between the patients with active and those with inactive synovitis (p<0.01). The mean value of the area under the curve of the entire group was weakly correlated with the number of swollen joints (p=0.038), but a strong correlation was found with composite indexes of disease activity such as the DAS (p=0.006) and CASI (p=0.01). No correlation was found with age, disease duration, and other laboratory and clinical variables. CONCLUSION: PDS may be a valuable tool to detect fractional vascular volume and to assist clinicians in distinguishing between inflammatory and non-inflammatory pannus. The transit of microbubbles of ultrasound contrast across a tissue can be used to estimate haemodynamic alterations and may have a role in assessing synovial activity and the therapeutic response to treatment of synovitis of the knee joint.