Role of the endothelium in chronic inflammatory synovitis

Do IgA antibodies to Chlamydia trachomatis have protective role in humoral immunity: a study in reactive arthritis patients

Chlamydia trachomatis-induced genitourinary Reactive Arthritis (ReA) can serve as good model for host-pathogen interaction. However, due to poor antigen presentation, cell-mediated immunity does not contribute as anticipated. Present study aims to evaluate protective role of anti-C. trachomatis antibodies vis-a-vis inflammatory chlamydial Major Outer Membrane Protein (MOMP). Prospective study was undertaken in 30 patients with genitourinary ReA. 30 Rheumatoid Arthritis (RA) and 30 osteoarthritis patients constituted controls. Subjects found to be PCR-positive for C. trachomatis were investigated for presence of MOMP in Synovial Fluid (SF) by fluorescence assay while anti-C. trachomatis IgA/IgM antibodies were estimated in SF/venous blood by ELISA. C. trachomatis MOMP was evident by the presence of elementary bodies in SF of 9 ReA PCR-positive patients (30%; p < 0.05 versus controls). Local secretory IgA antibodies were detected in 12 (40%) patients with ReA (p < 0.0001 versus controls); among 12 patients with anti-chlamydial IgA antibodies, 9 showed the presence of both MOMP and IgA antibodies in SF. 58.3% ReA patients (7/12) with secretory IgA antibodies were also positive for circulatory IgA antibodies (p < 0.01 versus controls). Serum IgM antibodies were present in 4 ReA (13.3%) and in 1 RA (3.3%) patient, respectively. In conclusion, the present study suggests that in ReA patients with chronic, persistent C. trachomatis infection in synovium, the chlamydial MOMP is triggering factor for generating a protective immune response by inducing anti-C. trachomatis IgA antibodies in the SF of large number of patients.

Cytokines in the rheumatic diseases

Extensive data has accumulated over the last 10 to 15 years to implicate various cytokines in pathways of pathophysiology in rheumatic diseases. Abnormalities in cytokine production are not the cause of these diseases, but reflect continual production by immune and inflammatory cells. Cytokines are heterogeneous and function in an overlapping and redundant network. An important principle to emerge is that the net biologic response in a diseased organ or tissue reflects a balance between the local levels of proinflammatory and anti-inflammatory cytokines and factors. Thus, a chronic disease may result from the excess production of proinflammatory cytokines or the inadequate production of anti-inflammatory cytokines. This article summarizes the role of cytokines in rheumatic diseases by focusing on each disease and the involved pathways of pathophysiology.

Comparison of lymphocyte depletion and clinical effectiveness on filtration leukocytapheresis in patients with rheumatoid arthritis

We evaluated the relationship between the clinical benefit of filtration leukocytapheresis (LCP) and the number of removed leukocytes in patients with rheumatoid arthritis (RA). LCP was performed in 31 drug-resistant RA patients. LCP was carried out 3 times with 1 week separating each session. Assessment of RA before and after LCP showed a substantial and rapid improvement in tender joint counts, swollen joint counts, and patients' and physicians' assessments. Careful analysis indicated that 19 of 31 patients with RA showed > or = 20% improvement following LCP therapy. The number of leukocytes in the peripheral blood significantly decreased during each session of LCP. However, there was no significant decrease in the number of circulating blood cells during the study period. No adverse reactions or complications were noted. There was no significant difference in any indices of clinical activity and the removal rates of leukocytes between responders and nonresponders. The total numbers of removed lymphocytes in responders were significantly higher than those in nonresponders (responders 64.1 x 10(8) versus nonresponders 50.7 x10(8), p < 0.05). The relationship between clinical effectiveness and the number of removed granulocytes and monocytes was not statistically significant. Our results suggest that filtration LCP to remove leukocytes from the peripheral blood, especially lymphocytes, exerts an immunomodulatory effect in patients with RA.

Evaluation of filtration leucocytapheresis for use in the treatment of patients with rheumatoid arthritis

OBJECTIVES

To evaluate the efficacy of filtration leucocytapheresis (LCP) for rheumatoid arthritis (RA).

METHODS

LCP was carried out three times, with 1 week separating each session, in 25 drug-resistant RA patients.

RESULTS

During each session, 96, 98, 61, 84 and 8% of the granulocytes, monocytes, lymphocytes, platelets and erythrocytes, respectively, that entered the LCP filter were removed. The number of granulocytes, monocytes and lymphocytes in the peripheral blood significantly decreased during each session of LCP. However, there was no significant decrease in the number of circulating blood cells during the study period. On average, 110 x 10(8) granulocytes, 5.23 x 10(8) monocytes, and 20.5 x 10(8) lymphocytes were removed during LCP therapy. Assessment of RA before and after LCP showed a substantial and rapid improvement in the tender joints counts, swollen joint counts, and patient's and physician's assessments. No adverse reactions or complications were noted. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels decreased following LCP, although the change in the latter parameter was statistically insignificant. The concentrations of serum albumin, gamma-globulin, IgG, IgM, CH50 and rheumatoid factor titres did not change during or after LCP. Careful analysis indicated that 16 of 25 patients with RA showed > or =20% improvement following LCP therapy.

CONCLUSIONS

Our results suggest that filtration LCP to remove leucocytes from the peripheral blood exerts an immunomodulatory effect in patients with RA.

Activated T Cells Acquire Endothelial Cell Surface Determinants During Transendothelial Migration

Activated T cells acquire endothelial cell (EC) plasma membrane constituents during transendothelial migration. This was assessed using an in vitro model system in which human peripheral blood CD4+ T cells migrated through confluent monolayers of HUVEC. Flow cytometry of migrated CD4+ T cells demonstrated that activated, but not resting, T cells acquired a variety of endothelial surface determinants, including CD31, CD49d, CD54, CD61, and CD62E. The extracellular domains of these molecules were detected on migrated T cells with mAbs, including those directed to the ligand-binding regions. A number of approaches were employed to document that the acquisition of these molecules was uniquely accomplished by activated T cells and clearly involved transfer from both resting and TNF-α-activated EC. Acquisition of endothelial markers by activated T cells occurred as part of the transfer of membrane components, as migrating T cells acquired EC membranes prelabeled with the lipophilic dye, 3,3′-dihexadecyloxacarbocyanine perchlorate (DiOC-16), along with EC surface proteins. Thus, during transendothelial migration, activated T cells acquire endothelial membrane components, and as a result may deliver them to perivascular sites.

Substance P receptor (NK1) gene expression in synovial tissue in rheumatoid arthritis and osteoarthritis

The distribution of messenger RNA coding for substance P receptor (NK1) in rheumatoid synovia and the relationship between signal intensity of NK1 mRNA and clinical parameters of disease activity were investigated. The synovia from 10 patients with rheumatoid arthritis (RA) and 7 patients with osteoarthritis was investigated by in situ hybridization histochemistry. In rheumatoid synovia, strong hybridization signal of NK1 mRNA was detected in 80% of the cells in both the lining layer and the interstitial layer. Moreover, the signal intensities of NK1 mRNA positively correlated with serum C-reactive protein levels and radiographic grade of joint destruction. These results provide histochemical evidence that rheumatoid synoviocytes strongly express NK1 gene, and the positive relation of the signal intensity of NK1 mRNA with CRP and radiographic severity suggests that the facilitation of NK1 gene expression in rheumatoid synovium relate the disease progression of RA.

Target effector role of vascular endothelium in the inflammatory response: insights from the clinical trial of anti-TNF alpha antibody in rheumatoid arthritis

Rheumatoid arthritis (RA) is characterised by chronic joint inflammation and infiltration by cells from the blood, especially activated T cells and macrophages, together with formation of new blood vessels. The overgrowth of the synovial lesion results eventually in destruction of cartilage and bone. Cytokines play a major role in RA, both in systemic inflammatory processes, such as induction of acute phase protein synthesis, and in the stimulation of new blood vessel development and recruitment of leucocytes to developing lesions. The focus for the interplay of many cytokines is the endothelium, the lining layer of the vasculature. This is the primary target for circulating mediators, and it controls the traffic of cells and molecules from the bloodstream into underlying tissues. Targeting the action of individual cytokines--for example, using antibody against tumour necrosis factor alpha (TNF alpha), has been shown to be very effective in the treatment of RA. Blockade of TNF alpha activity results in deactivation of the endothelium, manifested as reduced expression of adhesion molecules and chemoattractant cytokines, leading to diminished trafficking of inflammatory cells to synovial joints. In addition anti-TNF alpha decreases circulating levels of the potent angiogenic cytokine VEGF, suggesting that new blood vessel formation, and hence the supply of nutrients to the growing synovial lesion, is also affected. These observations lend further support to the hypothesis that interruption of a component of the cytokine network in RA may modulate disease progression, and point the way towards the development of new therapeutic strategies for the treatment of chronic inflammatory disease states.

Quantitation of IL-2Rp75 (CD122) expression on mononuclear cells in rheumatic disease

OBJECTIVE

To compare expression of the p75 chain of the interleukin-2 receptor (IL-2Rp75, CD122) on peripheral and synovial mononuclear cells in rheumatoid and non-rheumatoid inflammatory arthritis.

METHODS

Peripheral blood (PBMC) and synovial (SFMC) mononuclear cells were isolated from subjects with rheumatoid arthritis (n = 16) and non-rheumatoid inflammatory arthritis (n = 12). PBMC were isolated from six healthy controls. Expression of CD122 was examined using indirect immunofluorescence and quantitative flow cytometry.

RESULTS

There was no difference in IL-2Rp75 expression on PBMC from rheumatoid arthritis patients, non-rheumatoid arthritis patients, and controls. In subjects with rheumatoid arthritis there was no difference in IL-2Rp75 expression on PBMC and SFMC. However, in the non-rheumatoid arthritis group there was an increase in IL-2Rp75 expression on SFMC compared with PBMC (P = 0.0032). On SFMC there was a greater expression of IL-2Rp75 in non-rheumatoid arthritis than in rheumatoid arthritis (P = 0.0007). Expression was greater on CD8 positive cells and in subjects with shorter duration of disease.

CONCLUSIONS

The p75 chain of the IL-2 receptor, an important T cell activation antigen, is not upregulated in synovial fluid. This appears to be a disease specific defect and provides further support for the concept of "frustrated" or incomplete T cell activation in this disease.

Regulation of adhesion molecule expression by human synovial microvascular endothelial cells in vitro

OBJECTIVE

To examine the in vitro expression of E-selectin, P-selectin, intercellular adhesion molecule 1 (ICAM-1), ICAM-2, vascular cell adhesion molecule 1 (VCAM-1), and platelet-endothelial cell adhesion molecule 1 (PECAM-1) by synovial microvascular endothelial cells (SMEC) in comparison with microvascular neonatal foreskin endothelial cells (FSE) and macrovas- cular human umbilical vein endothelial cells (HUVE).

METHODS

Cultured endothelial cells were treated for 4 hours with medium alone or tumor necrosis factor alpha (TNF alpha). The expression of endothelial adhesion molecules was evaluated by flow cytometry, cell enzyme-linked immunosorbent assay, and Northern blot analysis.

RESULTS

SMEC continuously expressed E-selectin under basal culture conditions, whereas FSE and HUVE did not. TNF alpha treatment of rheumatoid arthritis (RA) SMEC resulted in sustained peak expression of E- selectin for up to 24 hours, which subsequently declined but remained elevated even at 72 hours. In contrast, peak E-selectin expression in FSE and HUVE occurred between 4 hours and 16 hours after TNF alpha treatment and then declined to near basal levels by 24-48 hours. SMEC expressed significantly higher levels of ICAM-1 compared with HUVE under basal culture conditions. There was no difference between SMEC, FSE, and HUVE in the expression of P-selectin, VCAM-1, ICAM-2, or PECAM-1. Northern blot analysis demonstrated that the levels of E-selectin expression by TNF alpha stimulated endothelial cells correlated with their respective messenger RNA levels.

CONCLUSION

Regulation of E-selectin and ICAM-1 expression in RA synovial endothelium is different from that in neonatal foreskin and human umbilical vein endothelium. The augmented expression of adhesion molecules in RA synovial endothelium may facilitate the recruitment of leukocytes to this site.

Hormonal and pregnancy relationships to rheumatoid arthritis: convergent effects with immunologic and microvascular systems

OBJECTIVE

To review sex hormones and rheumatoid arthritis (RA) and the interrelationships between hormonal, immunological, and vascular systems.

DATA SOURCES

Publications detailing serum sex hormone levels and their HLA interactions, steroidogenesis, pregnancy, and therapeutic uses of sex hormones in RA.

STUDY SELECTION

Controlled studies of sex hormone levels in RA patients not previously treated with glucocorticoids.

DATA EXTRACTION

Mean (+/- SD) serum levels of dehydroepiandrosterone sulfate (DHEAS), testosterone (T), and estradiol (E2).

DATA SYNTHESIS

Mean (+/- SD) levels were collated into tables for women with pre-versus postmenopausal onsets of disease and men. Data were also ordered across all study groups by increasing mean levels of the control subjects. Pooled data were summarized statistically, and major sources of variation between the studies were identified.

CONCLUSIONS

Serum DHEAS, an adrenal androgen, was impressively decreased among women with premenopausal onset of RA. One study showed such deficiency years before disease onset. Serum T was somewhat decreased in the premenopausal onset group, but could be explained by decreased peripheral conversion of the lower levels of adrenal androgens. Women with postmenopausal onset of RA had modestly decreased serum DHEAS levels overall, but no difference in serum T, compared with controls. Male RA cases had consistently decreased serum levels of T, but not of DHEAS. Serum E2 was comparable in all RA versus control groups. The complex biology of pregnancy was interpreted as an example of vital interactions between hormonal, immunological, and vascular systems, as they may relate to the physiopathology of RA. The major age, sex, and hereditable determinants of RA were compared within a composite table of estimated relative risks. Elucidation of the interacting risk factors offers promising avenues of research in this complex disease.

Expression and functional significance of an activation-dependent epitope of the beta 1 integrins in chronic inflammatory diseases

The avidity of VLA integrins for their ligands can be increased by their transition to an active conformational state. This conformational change can be detected with a novel monoclonal antibody (mAb), termed 15/7, that recognizes an activation-dependent conformational epitope on the common beta 1 polypeptide of different VLA alpha beta 1 integrins. In an attempt to understand the possible role of the active conformational state of beta 1 integrins in vivo, we first investigated the expression of 15/7 epitope on T lymphocytes from patients with chronic inflammatory joint diseases. An enhanced expression of the 15/7 epitope was found in the synovial fluid (SF) T lymphocytes from these patients as compared to their peripheral blood (PB) T cells. The effect of different cytokines on the appearance of the 15/7 activation epitope in PB T lymphocytes was subsequently analyzed; interferon-gamma, interleukin-2 and, to a lower extent, tumor necrosis factor-alpha were able to induce an increased expression of the 15/7 epitope. This enhanced 15/7 expression correlated with a higher binding ability to fibronectin of cytokine-activated T cells. The presence of this activation epitope was detected in a small proportion of T lymphocytes scattered within inflammatory foci of synovial membrane from rheumatoid arthritis and thyroid glands from Hashimoto's chronic thyroiditis. We then analyzed the possible role of 15/7 epitope expression on cell adhesion in vitro. Immunofluorescence studies showed that the 15/7 epitope displayed a spot-like distribution, selectively decorating adhesive contacts of U-937 myelomonocytic cells attached to the 80 kDa proteolytic fragment of fibronectin (FN80). Furthermore, the anti-beta 1 15/7 mAb was able to induce both T lymphocyte, Jurkat and U-937 cellular binding and spreading on FN80. Altogether these results indicate that an activated conformation of beta 1 integrins is detected in vivo in lymphocyte infiltrates from chronic inflammatory conditions. The active conformations of beta 1 integrins are regulated by physiologic mediators such as cytokines, play an important role in cellular attachment and spreading, and appear to be involved in the development of inflammatory processes.

Comparison of blood and synovial fluid lymphocyte subsets in rheumatoid arthritis and osteoarthritis

Immunoregulatory T-cell deficiency is thought to underlie pathogenesis of rheumatoid arthritis (RA) as a systemic autoimmunopathy. The aim of this study was a simultaneous analysis of peripheral blood and synovial lymphocyte subsets (Ly-SS) of RA patients as compared to patients with locally active osteoarthritis (OA). Peripheral blood Ly-SS and paired synovial fluid Ly-SS from 87 RA patients were analysed by two dimensional flow cytometry (Simulset Becton Dickinson) as compared to 15 OA patients. The control group consisted of 32 healthy subjects. The peripheral blood analysis from RA and OA patients revealed a significant decrease of CD8+ T-cells and increase of CD4+: CD8+ ratio when compared to the control group. The blood of RA patients showed a significant increase of HLA DR+ and IL 2R+ T cells as compared to OA group. The synovial fluid from RA and OA patients showed a significant increase of CD3+, CD8+, HLA DR+ T-cells and decrease of CD4+:CD8+ ratio and CD19+ cells in comparison to the peripheral blood. This study shows, that the OA T-cell system seems not to be activated in peripheral blood in opposition to RA patients. Synovial fluid Ly-SS in OA, however, showed only quantitative but not qualitative differences. OA seems to be mainly a local inflammatory response depending on T-cells, when lymphocyte T activity in blood is diminished.

Pathogenic responses of bradykinin system in chronic inflammatory rheumatoid disease

Excessive release of kinin (BK) in the synovial fluid can produce oedema, pain and loss of functions due to activation of B1 and B2 kinin receptors. Activation of the kinin forming system could be mediated via injury, trauma, coagulation pathways (Hageman factor and thrombin) and immune complexes. The activated B1 and B2 receptors might cause release of other powerful non-cytokine and cytokine mediators of inflammation, e.g., PGE2, PGI2, LTs, histamine, PAF, IL-1 and TNF, derived mainly from polymorphonuclear leukocytes, macrophages, endothelial cells and synovial tissue. These mediators are capable of inducing bone and cartilage damage, hypertrophic synovitis, vessel proliferation, inflammatory cell migration and, possibly, angiogenesis in pannus formation. These pathological changes, however, are not yet defined in the human model of chronic inflammation. The role of kinins and their interacting inflammatory mediators would soon start to clarify the detailed questions they revealed in clinical and experimental models of chronic inflammatory diseases. Several B1 and B2 receptor antagonists are being synthesized in an attempt to study the molecular functions of kinins in inflammatory processes, such as rheumatoid arthritis, periodontitis, inflammatory diseases of the gut and osteomyelitis. Future development of specific potent and stable B1 and B2 receptor antagonists or combined B1 and B2 antagonists with y-IFN might serve as a pharmacological basis for more effective treatment of joint inflammatory and related diseases.

Expression and functional role of 1F7 (CD26) antigen on peripheral blood and synovial fluid T cells in rheumatoid arthritis patients

The expression and the functional role of the CD26 (1F7) T cell surface molecule, an ectoenzyme which seems to represent a functional collagen receptor of T lymphocytes and to have a role in T cell activation, were analysed in both peripheral blood (PB) and synovial fluid (SF) T cell samples from patients with active and inactive rheumatoid arthritis (RA). Although patients with active disease displayed higher percentages of PB CD26+ CD4+ T cells than inactive RA and control subjects, CD26 antigen expression on RA SF T lymphocytes was low. The anti-1F7 binding to the T cell surface, that led to CD26 antigen modulation and enhancement of both IL-2 synthesis by, and 3H-TdR incorporation of, anti-CD3- or anti-CD2-triggered PB T cells in RA and control subjects, was unable to affect significantly both expression and functional activity of RA SF T lymphocytes. Since the 1F7 antigen spontaneously reappeared on the surface of unstimulated SF T cells after 2-5 days of culturing, the low 1F7 antigen expression of anti-1F7 in the SF T cell compartment may be the result of in vivo molecule modulation exerted by the natural ligand in the joint, with important implications for T cell activation and lymphokine synthesis.

Migration and homing of lymphocytes to lymphoid and synovial tissues in proteoglycan-induced murine arthritis

OBJECTIVE

To describe the migration and homing of labeled donor lymphocytes to the lymphoid organs and synovial tissues of host animals, during the development of cartilage proteoglycan (PG)-induced arthritis adoptively transferred to syngeneic BALB/c mice.

METHODS

Lymphocytes from either nonarthritic or arthritic donor animals were labeled with either fluorescent or radioactive cell linkers (PKH-GL) and injected into syngeneic, immunosuppressed mice. The homing patterns of donor lymphocytes following the injection of labeled cells were studied by fluorescence microscopy and by measurement of radioactivity in tissue samples.

RESULTS

Lymphocytes from arthritic donors retained their ability to transfer the disease after labeling. In the lymphoid organs, arthritic and nonarthritic donor lymphocytes exhibited similar homing patterns, although remarkable differences were found in the number of homing cells derived from nonarthritic and arthritic donors. However, labeled cells only from arthritic animals migrated to the synovial tissue of the recipient mice, and their appearance was associated with the onset of arthritis.

CONCLUSION

Lymphocytes from mice with PG-induced arthritis, in contrast to lymphocytes from non-arthritic donors, exhibit preferential homing to the synovial tissue of the host. Adoptive transfer of arthritis is linked to the appearance of these cells in the synovium.

Dominant T-cell-receptor beta chain variable region V beta 14+ clones in juvenile rheumatoid arthritis

The characteristic histopathology and major histocompatibility complex associations in juvenile rheumatoid arthritis suggest an oligoclonal antigen-specific T-cell population may be critical to pathogenesis. To test this, we analyzed the T-cell repertoire of a polyarticular HLA-DR4+ juvenile rheumatoid arthritis patient with an aggressive form of disease that required arthrocentesis of the knee joints and early replacement of both hip joints. A comparison of T-cell-receptor beta chain variable region (V beta) gene expression in peripheral blood and synovial fluid performed by semiquantitation of cDNA samples amplified by the PCR revealed overexpression of the T-cell-receptor V beta 14 gene family. To determine the nature of V beta 14 overexpression, we sequenced randomly cloned amplification products derived from two synovial fluid, two synovial tissue, and three peripheral blood samples by using a V beta 14/beta chain constant region primer pair. Sequence data showed that the T-cell response in the synovia was oligoclonal. Of four clones found, one was present in all joints examined and persisted over time. This clone accounted for 67% and 74% of all V beta 14+ clones sequenced in two synovial fluid samples and 75% and 40% in two synovial tissue samples. This clone was also found at a lesser frequency in peripheral blood samples. Further studies provided evidence for the presence of oligoclonally expanded populations of T cells utilizing the V beta 14 T-cell receptor in 6 of 27 patients examined. In contrast to the remaining patients studied, 3 with a late onset polyarticular course who exhibited especially marked clonality were characterized by features typical of adult rheumatoid arthritis (IgM rheumatoid factor-positive and HLA-DR4+). These data suggest a role for V beta 14+ T cells in a group of juvenile rheumatoid arthritis patients.

Identical expression of ELAM-1, VCAM-1, and ICAM-1 in sarcoidosis and usual interstitial pneumonitis

Extravasation of leucocytes in tissues is mediated by leucocyte-endothelial cell interactions in which adhesion molecules play an important role. Until now, two pathways have been unravelled, i.e., the LFA-1/ICAM-1 and the VLA-4/VCAM-1 pathways. ELAM-1 has been shown to be involved in granulocyte accumulation and recently also in lymphocyte migration. The role of HECA-452 is under investigation. In this study we have investigated the expression of the above-mentioned adhesion molecules in lung tissue of patients with pulmonary sarcoidosis and usual interstitial pneumonitis (UIP), and in mediastinal lymph nodes of patients with sarcoidosis. ICAM-1 (CD54) was broadly distributed on the endothelium of all the vessels found in sarcoidosis and UIP. VCAM-1 was present on the endothelium of the venules, capillaries, and arterioles in both sarcoidosis and UIP. ELAM-1 reacted with endothelial cells lining venules and capillaries in chronic progressive sarcoidosis and in the active phase of UIP but not in the stationary phases of both diseases. HECA-452 activity could be detected only on high endothelial venules within sarcoid lymph nodes. In lung tissues, macrophages bearing the ICAM-1 antigen were present in sarcoid tissue but not in the interstitium and alveolar space of UIP. LFA-1 (CD11a/CD18) and VLA-4 (CD49d/CD29) were present on all leucocytes found but seemed to be more highly expressed on lymphocytes in sarcoidosis. These findings suggest that the LFA-1/ICAM-1 and VLA-4/VCAM-1 pathways are involved in leucocyte migration in both types of lung disease, while in the active phases of sarcoidosis and UIP, ELAM-1 is also involved.

T cells are responsible for the enhanced synovial cellular immune response to triggering antigen in reactive arthritis

In reactive arthritis (ReA) there is specific proliferation of synovial fluid (SF) mononuclear cells (MNC) to the triggering bacterial antigen; comparatively little or no response is seen in peripheral blood (PB). To investigate the mechanism of this elevated local immune response, we examined patients with typical ReA who showed an enhanced antigen-specific synovial immune response in bulk culture. Using separated fractions of T cells and antigen-presenting cells (APC) from PB and SF we showed that the synovial T cells rather than SF APC are responsible for the specific proliferation. By limiting dilution analysis, the frequency of T cells responding to the specific antigen was found to be significantly increased compared with the frequency of irrelevant antigen-specific T cells. Furthermore, the frequency of T cells responding to the specific antigen was higher in SF (between 1/619 and 1/4846, mean 1/2389) than in PB (between 1/1286 and 1/16,279, mean 1/7350). We conclude that the specific synovial cellular immune response in ReA is mainly due to an expansion of antigen-specific T cells within the joint. However, the non-specific hyper-reactivity of SF T cells and differences between SF and PB APC may make a more minor contribution.

The intrinsic migratory capacity of memory T cells contributes to their accumulation in rheumatoid synovium

OBJECTIVE

Mechanisms controlling the infiltration of T cells into rheumatoid synovium have not been fully characterized. These studies were undertaken to investigate the relationship between T cell phenotype and migratory capacity, so as to elucidate mechanisms that might contribute to the accumulation of T cells at inflammatory sites.

METHODS

The characteristics of in vivo migrating cells were studied by dual-immunofluorescence FACS (fluorescence-activated cell sorter) analysis of rheumatoid synovial and peripheral blood T cells. Migratory cells were also characterized using a recently developed in vitro assay, wherein peripheral blood T lymphocytes (PBTL) with the capacity to migrate through endothelial cell monolayers were retrieved and assessed.

RESULTS

Migratory CD4+ T cells from rheumatoid arthritis (RA) and normal individuals were characterized as being CD45RA-, CD29bright, CD11abright, L-selectin-, CD54+, and CD58+. Migrating RA PBTL (compared with normal PBTL), however, were significantly enriched in activated HLA-DR+ T cells. RA synovial tissue lymphocytes exhibited a similar phenotype, but with decreased surface density of CD4 and an increase in HLA-DR and VLA-1. RA synovial lymphocytes exhibited a 2-3-fold increase in migratory capacity over normal and RA PBTL:

CONCLUSION

These studies demonstrate the inherent migratory proficiency of CD4+ T cells that express a memory phenotype (CD29bright, CD11abright, and CD58+). In addition, enhanced transendothelial migration was observed for CD4+ T cells that were CD54+ and L-selectin-. These studies demonstrate that the migratory patterns of circulating lymphocytes may be correlated with their surface phenotype and that the intrinsic migratory capacity of memory T cells is one component contributing to their accumulation in the rheumatoid synovium.

Localization of tumor necrosis factor receptors in the synovial tissue and cartilage-pannus junction in patients with rheumatoid arthritis. Implications for local actions of tumor necrosis factor alpha

OBJECTIVE

We have previously described the location of tumor necrosis factor alpha (TNF alpha)-producing cells in synovial tissue and cartilage-pannus junction in rheumatoid arthritis (RA). To further understand the local actions of TNF alpha, we investigated the expression of TNF receptors (TNF-R) on cells in the same compartments in patients with RA.

METHODS

The expression of both p55 TNF-R and p75 TNF-R was determined using alkaline phosphatase-conjugated mouse anti-alkaline phosphatase (APAAP) and double immunofluorescence staining techniques with monoclonal antibodies.

RESULTS

In RA synovial membrane, both p55 TNF-R and p75 TNF-R were detectable in up to 90% of the cells in the lining layer, and were demonstrated on cells in deeper layers of the membrane, including vascular endothelial cells. Cells in lymphoid aggregates expressed both TNF-R, but with a predominant expression of p75 receptor. At the cartilage-pannus junction, the majority of pannus cells, especially those invading cartilage, expressed both the p55 and the p75 TNF-R. Sequential section and double immunofluorescence staining showed that the TNF-R-expressing cells were in the vicinity of TNF alpha-containing cells, and some TNF alpha-containing cells also expressed TNF-R. TNF-R-expressing cells were also detected in osteoarthritic and normal synovial tissue, but in smaller numbers and at a lower intensity.

CONCLUSION

These results provide histologic evidence that both p55 TNF-R and p75 TNF-R are expressed by a variety of cell types in RA synovial tissue, reflecting the fact that a wide range of cells are potential targets for TNF alpha in this tissue. This study further supports the hypothesis that TNF alpha plays a major role in the pathogenesis of RA.

The role of cytokines and their inhibitors in arthritis

The role of cytokines in inflammatory joint diseases is well documented, especially with regard to tissue destruction and remodelling. In these processes, IL-1 and TNF alpha play a prominent part by stimulating protease production. The regulation of their production, their release and their effects on target cells (e.g. synovial cells, chondrocytes and bone-derived cells) has therefore been the subject of intensive investigations. In this context a new dimension has emerged recently due to the observation of the existence of natural specific cytokine inhibitors. IL-1-ra and the soluble fragments of both TNF receptors--inhibitory by binding to TNF alpha--are natural products. These appear to be the molecules best suited for controlling the imbalance between pro- and anti-inflammatory processes. The use of the recombinant forms of these inhibitors may open new perspectives for therapeutic intervention. The fact that the respective mechanisms of action of receptor antagonists and inhibitory binding proteins differ does not rule out their complementarity. Preliminary experiments with animal models have yielded promising results which should be followed up by clinical trials.