Immunohistologic analysis of the distribution of cell adhesion molecules within the inflammatory synovial microenvironment

Electroporation-enhanced transdermal diclofenac sodium delivery into the knee joint in a rat model of acute arthritis

Purpose

Since electroporation (EP) can increase the permeability of biological membranes, we hypothesized that it offers an opportunity to enhance the transdermal delivery of drugs for intra-articular indications. Our aim was to compare the anti-inflammatory and analgesic efficacy of EP-combined topical administration of diclofenac sodium hydrogel (50 mg mL^-1 in 230 µL volume) with that of an equivalent dose of oral (75 mg kg^-1) and simple topical administration.

Methods

Arthritis was induced with the injection of 2% λ-carrageenan and 4% kaolin into the right knee joints of male Sprague Dawley rats. EP was applied for 8 min with 900 V high-voltage pulses for 5 ms followed by a 20 ms break. Drug penetration into the synovial fluid and plasma was detected by high-performance liquid chromatography. Leukocyte-endothelial interactions were visualized by intravital videomicroscopy on the internal surface of the synovium. Inflammation-induced thermal and mechanical hyperalgesia reactions, knee joint edema, and inflammatory enzyme activities were assessed at 24 and 48 h after arthritis induction.

Results

EP significantly increased the plasma level of diclofenac as compared with the topical controls 10 min after the 2% λ-carrageenan and 4% kaolin injection. Increased leukocyte-endothelial interactions were accompanied by joint inflammation, which was significantly reduced by oral and EP diclofenac (by 45% and by 30%, respectively) and only slightly ameliorated by simple topical diclofenac treatment (by 18%). The arthritis-related secondary hyperalgesic reactions were significantly ameliorated by oral and EP-enhanced topical diclofenac treatments. The knee cross-section area (which increased by 35%) was also reduced with both approaches. However, simple topical application did not influence the development of joint edema and secondary hyperalgesia.

Conclusion

The study provides evidence for the first time of the potent anti-inflammatory and analgesic effects of EP-enhanced topical diclofenac during arthritis. The therapeutic benefit provided by EP is comparable with that of oral diclofenac; EP is a useful alternative to conventional routes of administration.

Immunosuppression by co-stimulatory molecules: inhibition of CD2-CD48/CD58 interaction by peptides from CD2 to suppress progression of collagen-induced arthritis in mice

Targeting co-stimulatory molecules to modulate the immune response has been shown to have useful therapeutic effects for autoimmune diseases. Among the co-stimulatory molecules, CD2 and CD58 are very important in the early stages of generation of an immune response. Our goal was to utilize CD2-derived peptides to modulate protein-protein interactions between CD2 and CD58, thereby modulating the immune response. Several peptides were designed based on the structure of the CD58-binding domain of CD2 protein. Among the CD2-derived peptides, peptide 6 from the F and C β-strand region of CD2 protein exhibited inhibition of cell-cell adhesion in the nanomolar concentration range. Peptide 6 was evaluated for its ability to bind to CD58 in Caco-2 cells and to CD48 in T cells from rodents. A molecular model was proposed for binding a peptide to CD58 and CD48 using docking studies. Furthermore, in vivo studies were carried out to evaluate the therapeutic ability of the peptide to modulate the immune response in the collagen-induced arthritis (CIA) mouse model. In vivo studies indicated that peptide 6 was able to suppress the progression of CIA. Evaluation of the antigenicity of peptides in CIA and transgenic animal models indicated that this peptide is not immunogenic.

Pattern of adhesion molecule expression in labial salivary glands from patients with primary Sjögren's syndrome

The aim of this work was to examine the pattern of distribution of adhesion molecules in minor salivary glands from patients with primary Sjögren's syndrome (SS). Labial salivary gland (LSG) biopsies from 31 patients with primary SS and 21 normal subjects were examined. Cryostat sections were examined with monoclonal antibodies to different adhesion molecules using an indirect immunoperoxidase technique. There was an increased expression of ICAM-1, class IMHC, HLA-DR & DQ (p<0.05) on endothelial cells, lymphocytes, fibroblasts and salivary epithelial cells (HLA-DR far exceeds ICAM-1 (limited) epithelial expression). ELAM-1 and to a lesser extent VCAM-1 were demonstrated over some of the endothelial cells in patients, but not in controls (p<0.01). Many of the endothelial cells expressing ICAM-1, DR, DQ, ELAM-1 were high endothelial venules. CD44 was strongly expressed over epithelial cells, endothelial and infiltrating mononuclear cells, while LFA-3 was present mainly on epithelial cells, and faintly on infiltrating inflammatory cells. There was no difference between patients and controls with regard to CD44 or LFA-3 expression. The ligands for the above mentioned adhesion molecules, namely LFA-1α, LFA-1ß, LECAM-1, VLA-4ß(CD49d), CD44 and CD2 were demonstrated (variably) on the surface of infiltrating lymphocytes. CD11b and CD11c were detected over monocytes/macrophages. A proportion of lymphocytes expressed VCAM-1 and CD11c and may function as antigen presenting cells. In some biopsies these molecules were localized at the center of lymphoid follicles with the appearance of dendritic cells. Although the majority of lymphocytes were activated and strongly expressing DR and ICAM-1, they were IL-2Rα (CD25) negative. We conclude that adhesion molecules are prominent in LSG of patients with primary SS. They may play a major role by mediating the lymphocytic infiltration to the glands, retaining the lymphocytes in the glands and regulating the different immune responses in the local microenvironment of this chronic inflammatory disease.

Antigen-specific blocking of CD4-specific immunological synapse formation using BPI and current therapies for autoimmune diseases

In this review, we discuss T-cell activation, etiology, and the current therapies of autoimmune diseases (i.e., MS, T1D, and RA). T-cells are activated upon interaction with antigen-presenting cells (APC) followed by a "bull's eye"-like formation of the immunological synapse (IS) at the T-cell-APC interface. Although the various disease-modifying therapies developed so far have been shown to modulate the IS and thus help in the management of these diseases, they are also known to present some undesirable side effects. In this study, we describe a novel and selective way to suppress autoimmunity by using a bifunctional peptide inhibitor (BPI). BPI uses an intercellular adhesion molecule-1 (ICAM-1)-binding peptide to target antigenic peptides (e.g., proteolipid peptide, glutamic acid decarboxylase, and type II collagen) to the APC and therefore modulate the immune response. The central hypothesis is that BPI blocks the IS formation by simultaneously binding to major histocompatibility complex-II and ICAM-1 on the APC and selectively alters the activation of T cells from T(H)1 to T(reg) and/or T(H)2 phenotypes, leading to tolerance.

A peptide from the beta-strand region of CD2 protein that inhibits cell adhesion and suppresses arthritis in a mouse model

Cell adhesion molecules play a central role at every step of the immune response. The function of leukocytes can be regulated by modulating adhesion interactions between cell adhesion molecules to develop therapeutic agents against autoimmune diseases. Among the different cell adhesion molecules that participate in the immunologic response, CD2 and its ligand CD58 (LFA-3) are two of the best-characterized adhesion molecules mediating the immune response. To modulate the cell adhesion interaction, peptides were designed from the discontinuous epitopes of the beta-strand region of CD2 protein. The two strands were linked by a peptide bond. beta-Strands in the peptides were nucleated by inserting a beta-sheet-inducing Pro-Gly sequence with key amino acid sequences from CD2 protein that binds to CD58. Using a fluorescence assay, peptides that exhibited potential inhibitory activity in cell adhesion were evaluated for their ability to bind to CD58 protein. A model for peptide binding to CD58 protein was proposed based on docking studies. Administration of one of the peptides, P3 in collagen-induced arthritis in the mouse model, indicated that peptide P3 was able to suppress rheumatoid arthritis in mice.

The combined role of wear particles, macrophages and lymphocytes in the loosening of total joint prostheses

This review considers the causes of loosening of prosthetic joint replacement paying attention to the biological mechanisms rather than other effects that are physical, such as component fracture and other failure related to mechanical problems. Infection accounts for approximately 1.5 per cent of joint loosening and when it occurs it is a cause of serious concern to the surgeon. The loosening of prosthetic joints in the absence of infection is by far the most common reason for revision surgery and is known as aseptic loosening. While this may be multifactorial in terms of causation, and non-biological factors may contribute significantly in a particular individual, a significant part is undoubtedly played by the generation of wear debris, mainly from the bearing surfaces of the joint, and the cellular reaction to this in the implant bed. Phagocytic cells (macrophages and multinucleated giant cells) are the ones that remove foreign material from the tissues, and the ways in which these cells function in the interface between implant and bone are described. Mediators produced locally include numerous cytokines, enzymes and integrins. There is evidence for interactions between macrophages and locally recruited lymphocytes, which may or may not give rise to an immunologically mediated process.Sensitization of individuals having metal implants in place has been shown by positive skin tests or blood lymphocyte transformation tests and in these cases has been accompanied by loosening and failure of the replacement joint. The question remains as to whether this process is also present in a proportion of individuals with aseptic loosening in the absence of clearly defined clinical evidence of sensitization.Numerous studies performed by the author's group and, latterly, by others suggest that the cellular reactions detected in the tissues in cases of aseptic loosening are indeed those of contact sensitization. There is good evidence to show that a type IV cell-mediated immune reaction is taking place, with TH1 cell involvement and active antigen presentation. The extent to which sensitization is present in individual cases of aseptic loosening remains a subject for further work and this needs all the sophisticated molecular methods now available to modern biology to be applied in appropriate prospective clinical studies coupled with experimental models in vitro and in vivo. Immunological processes may play a more important part in joint loosening than previously considered.

Role of adhesion molecules in synovial inflammation

PURPOSE OF REVIEW

The ability of cells to adhere to other cells and extracellular matrix (ECM) through cellular adhesion molecules (CAMs) is central to tissue remodeling and inflammation. This review discusses the potential role of CAMs in development of synovial inflammation through regulating the recruitment of inflammatory cells via endothelial-leukocyte interactions, the organization and activation of leukocytes in the synovial sublining, and the formation and behavior of the hyperplastic synovial lining.

RECENT FINDINGS

Over the past several years valuable insight has been gained into the role of cell-cell and cell-ECM adhesive interactions in synovial organization and inflammation. Recently, cadherin-11 was identified on fibroblast-like synoviocytes and has been demonstrated to play a central role in synovial lining organization. Furthermore, studies using animal models of inflammatory arthritis have demonstrated critical roles for E- and P-selectins, CD11a/CD18 [lymphocyte function-associated antigen (LFA)-1], alpha4beta1 integrin, and cadherin-11 in the development of synovial inflammation.

SUMMARY

Cell-cell and cell-ECM interactions through CAMs play an important role in synovial inflammation. Future studies of CAMs are needed to define more thoroughly their role in synovial inflammation and their potential as therapeutic targets in the treatment of rheumatoid arthritis and related inflammatory arthritic conditions.

Molecular interactions between T cells and fibroblast-like synoviocytes: role of membrane tumor necrosis factor-alpha on cytokine-activated T cells

The mechanism of fibroblast-like synoviocyte (FLS) transformation into an inflammatory phenotype in rheumatoid arthritis (RA) is not fully understood. FLS interactions with invading leukocytes, particularly T cells, are thought to be a critical component of this pathological process. Resting T cells and T cells activated through the T-cell receptor have previously been shown to induce inflammatory cytokine production by FLS. More recently, a distinct population of T cells has been identified in RA synovium that phenotypically resembles cytokine-activated T (Tck) cells. Using time lapse microscopy, the interactions of resting, superantigen-activated, and cytokine-activated T cells with FLS were visualized. Rapid and robust adhesion of Tck and superantigen-activated T cells to FLS was observed that resulted in flattening of the T cells and a crawling movement on the FLS surface. Tck also readily activated FLS to produce interleukin IL-6 and IL-8 in a cell contact-dependent manner that was enhanced by exogenous IL-17. Although LFA-1 and ICAM-1 co-localized at the Tck-FLS synapse, blocking the LFA-1/ICAM-1 interaction did not substantially inhibit Tck effector function. However, antibody blocking of membrane tumor necrosis factor (TNF)-alpha on the Tck surface did inhibit FLS cytokine production, thus illustrating a novel mechanism for involvement of TNF-alpha in cell-cell interactions in RA synovium and for the effectiveness of TNF-alpha blockade in the treatment of RA.

Involvement of ICAM-1 in bone metabolism: a potential target in the treatment of bone diseases?

Bone diseases such as osteoporosis, osteoarthritis and rheumatoid arthritis (RA) affect a great proportion of individuals, with debilitating consequences in terms of pain and progressive limitation of function. Existing treatment of these pathologies has been unable to alter the natural evolution of the disease and, as such, a clearer understanding of the pathophysiology is necessary in order to generate new treatment alternatives. One therapeutic strategy could involve the targeting of intercellular adhesion molecule-1 (ICAM-1; CD54). In bone, ICAM-1 is expressed at the surface of osteoblasts (Obs) and its counter-receptor, leukocyte function-associated antigen-1 (LFA-1; CD11a), at the surface of osteoclast (Oc) precursors. ICAM-1 blockade between the Ob and the pre-Oc results in an inhibition of Oc recruitment and a modulation of inflammation, which could potentially help in controlling disease activity in bone pathologies. So far, clinical studies on ICAM-1 blockade in bone diseases have been limited to RA. A better understanding of the implication of this adhesion molecule in Ob/Oc interactions and inflammatory mediation in the bone pathological state, however, is needed. As new discoveries on the role of this adhesion molecule are being reported, ICAM-1 could become a potential target for other bone diseases as well.

Expression of ICAM-1, ICAM-2, NCAM-1 and VCAM-1 by human synovial cells exposed to Borrelia burgdorferi in vitro

The interaction of resident tissue cells with migratory inflammatory cells is essential for the recruitment of immune effector cells to inflammatory sites. The sustained expression of adhesion molecules in the synovium of patients with chronic Lyme arthritis seems to contribute to this chronic inflammation. Whether cell adhesion molecules influence the early steps of Borreliosis is unclear. Therefore, we examined the expression of ICAM-1, ICAM-2, VCAM-1 and NCAM-1 in synovial cells exposed to two different Borrelia burgdorferi sensu stricto strains Geho and B31. The mRNA expression of ICAM-1, ICAM-2, VCAM-1 and NCAM-1 was not changed in synovial cells exposed to B31. Whereas ICAM-2 and VCAM-1 was upregulated, NCAM-1 mRNA was downregulated and ICAM-1 mRNA was unchanged by strain Geho. The ICAM-1 protein expression on the synovial cell surface was downregulated by both strains. Differential regulation of adhesion molecule mRNA, and subsequent high turnover or elevated shedding from the cell membrane may contribute to early pathogenesis in Lyme arthritis.

Increased intraarticular interleukin-7 in rheumatoid arthritis patients stimulates cell contact-dependent activation of CD4(+) T cells and macrophages

OBJECTIVE

To determine the level of intraarticular expression of interleukin-7 (IL-7) in patients with rheumatoid arthritis (RA) and to investigate the mechanisms by which IL-7 facilitates activation of CD4(+) T cells and monocyte/macrophages in RA.

METHODS

IL-7 levels were measured in synovial fluid obtained from patients with RA and patients with osteoarthritis (OA). Immunohistologic analysis was used to assess the expression of IL-7 in synovial tissue from patients with RA. Proliferation and activation markers were determined in order to measure the effect of IL-7 on mononuclear cells, isolated CD4(+) T cells, and monocyte/macrophages from the peripheral blood and synovial fluid. Cocultures of CD4(+) T cells and monocytic cells in the absence or presence of a semipermeable membrane were performed to assess the extent to which IL-7 induces its effects, either contact dependently or via soluble mediators.

RESULTS

IL-7 levels were increased in synovial fluid from patients with RA compared with the levels in synovial fluid from patients with OA. Macrophages, fibroblasts, and endothelial cells in the joint lining tissue expressed abundant IL-7. In vitro, synovial fluid CD4(+) T cells and macrophages were hyperresponsive to IL-7 when compared with peripheral blood cells. Furthermore, IL-7 enhanced cell contact-dependent activation of CD4(+) T cells and monocyte/macrophages.

CONCLUSION

The abundant intraarticular expression of IL-7 and the stimulation by IL-7 of contact-dependent activation of CD4(+) T cells and monocytic cells indicate that this cytokine plays an important proinflammatory role in RA synovitis. Further identification of IL-7-induced pathways may improve understanding of the important interactive role of CD4(+) T cells and monocytic cells in RA.

ISIS 2302, an antisense inhibitor of intercellular adhesion molecule 1

ISIS 2302 is a 20 base phosphorothioate oligodeoxynucleotide (ODN) that inhibits intercellular adhesion molecule 1 (ICAM-1) expression through an antisense mechanism. Murine and rat analogues have been effective at doses of 0.06 - 10 mg/kg in a spectrum of models of human inflammatory diseases and allograft transplantation, and ISIS 2302 inhibits the upregulation of ICAM-1 expression in a variety of human cells in vitro. In animals, including primates, plasma distribution half-life ranges from 30 - 60 min, but tissue elimination half-lives range from 1 - 5 days, and the compound is metabolised as other nucleic acids. In a Phase I iv. study, the pharmacokinetic behaviour of ISIS 2302 was similar to that in other primates, and single and multiple every other day doses from 0.06 - 2 mg/kg infused over 2 h were well-tolerated. Phase IIa studies have been completed in Crohn's disease, rheumatoid arthritis, and psoriasis, and a combined Phase I/II renal allograft acute rejection prophylaxis study has just completed enrolment. In these studies, ISIS 2302, 0.5 - 2 mg/kg, or placebo was administered iv. every 2 - 3 days over 14 - 26 days (7 - 13 infusions) to 17 - 52 patients, with follow up for 6 months. In the Crohn's study, evidence of highly durable (5+ month) remission-inducing and steroid-sparing properties were demonstrated, without clinically important adverse events. A 300-patient, pivotal quality trial investigating the steroid-sparing and remission-inducing qualities of ISIS 2302 in patients with steroid-dependent Crohn's disease is completely enrolled, with results expected in the first half of 2000. Modest efficacy and excellent tolerability were demonstrated in the psoriasis and rheumatoid arthritis trials. A Phase IIa trial of a topical formulation in patients with psoriasis is expected to commence in late 1999, as is a trial of an enema formulation in distal ulcerative colitis. Administration by nebulisation for asthma is undergoing preclinical evaluation. Execution of future plans in organ transplantation will await the results of the ongoing Phase I/II trial.

Decrease in circulating endothelial cell adhesion molecule and thrombomodulin levels during oral iloprost treatment in rheumatoid arthritis patients: preliminary results

OBJECTIVE

Rheumatoid arthritis is a chronic inflammatory autoimmune disease with proinflammatory cytokines involved in its pathogenesis. Recently in vitro as well as in vivo studies have shown that iloprost, a stable prostacyclin analogue, can reduce the release of these cytokines. This study was performed to further investigate the anti-inflammatory effects of iloprost by determining plasma adhesion molecules as markers of endothelial cell activation, and plasma thrombomodulin as a parameter of endothelial cell injury in patients with rheumatoid arthritis receiving oral iloprost therapy.

METHODS

Plasma thrombomodulin levels and the values of the plasma adhesion molecules VCAM-1 (vascular cell adhesion molecule 1), E-selectin (CD62E), and ICAM-1 (intercellular adhesion molecule 1, CD 54) were measured by ELISA during a 7-day period of treatment with orally-administered iloprost in 14 patients with active rheumatoid arthritis. Finally, the same parameters were determined at the end of the observation period (1 week after the end of therapy). In addition, the disease activity was measured using the DAS (disease activity score) as well as the patients' self-assessed pain severity, and correlated with the changes of plasma adhesion molecule and thrombomodulin levels.

RESULTS

The plasma levels of all three adhesion molecules as well as of thrombomodulin significantly decreased under therapy with oral iloprost. After 1 week (day 7 of therapy), the mean percent changes from day 0 were -20.1% for VCAM-1 (p = 0.008), -21.2 for ICAM-1 (p = 0.003), -24.6% for E-selectin (p = 0.001), and -21.7% for thrombomodulin (p = 0.003). This decrease lasted up to 1 week after the end of therapy in the case of VCAM-1 (p = 0.023) and ICAM-1 (p = 0.001). Further analysis of the results revealed additional significant correlations between different parameters of clinical disease activity, thrombomodulin and adhesion molecules.

CONCLUSION

This study showed hints towards clinical effects in patients with rheumatoid arthritis receiving oral iloprost therapy. Pathophysiologically, the decrease of adhesion molecules points at an immunomodulating effect of iloprost. The observed thrombomodulin-lowering effect of iloprost may indicate stabilisation of endothelial cell function by diminishing endothelial cell injury.

Rheumatoid arthritis

Rheumatoid arthritis is a systemic inflammatory disorder that mainly affects the diarthrodial joint. It is the most common form of inflammatory arthritis, and has a substantial societal effect in terms of cost, disability, and lost productivity. Although the pathogenesis of rheumatoid arthritis remains incompletely understood, much insight into the cellular and molecular mechanisms involved has been gained in the past decade. On the basis of these insights, new therapies have been developed, and clinical trials have shown the efficacy of aggressive treatment of patients with active disease. In this review, we discuss improvements in our understanding of the pathophysiology of inflammatory synovitis in rheumatoid arthritis, and improvements in therapy for patients with the disorder. The past decade has seen substantial advances in these areas. Future studies will be directed at improving methods for early diagnosis and identification of patients with progressive disease, and at improving methods to identify candidates for subclasses of disease-modifying antirheumatic drugs (DMARDs). Long-term safety and efficacy data for the new DMARD agents and combination regimens will also further delineate efficacy and toxicity and thus the appropriate clinical context for use of these therapeutic approaches. The continuing elucidation of pathophysiological pathways relevant in rheumatoid arthritis, coupled with continuing advances in biotechnology and rational drug design, offer substantial hope for the continued development of increasingly potent and specific pharmacotherapy for treatment of rheumatoid arthritis.

Expression of adhesion molecules in synovia of patients with treatment-resistant lyme arthritis

The expression of adhesion molecules in synovium in patients with Lyme arthritis is surely critical in the control of Borrelia burgdorferi infection but may also have pathologic consequences. For example, molecular mimicry between a dominant T-cell epitope of B. burgdorferi outer surface protein A and an adhesion molecule, human lymphocyte function-associated antigen 1 (LFA-1), has been implicated in the pathogenesis of treatment-resistant Lyme arthritis. Using immunohistochemical methods, we examined synovial samples for expression of adhesion molecules in 29 patients with treatment-resistant Lyme arthritis and in 15 patients with rheumatoid arthritis or chronic inflammatory monoarthritis. In Lyme arthritis synovia, endothelial cells showed intense expression of P-selectin and vascular adhesion protein-1 (VAP-1). Expression of LFA-1 was also intense on infiltrating cells, particularly in lymphoid aggregates, and intercellular adhesion molecule-1 (ICAM-1) was markedly expressed on synovial lining and endothelial and infiltrating cells. Moderate expression of vascular cell adhesion molecule-1 (VCAM-1) was seen on synovial lining and endothelial cells, and mild expression of its ligand, very late antigen-4, was apparent in perivascular lymphoid infiltrates. Except for lesser expression of VCAM-1 in Lyme synovia, the levels of expression of these adhesion molecules were similar in the three patient groups. We conclude that certain adhesion molecules, including ICAM-1 and LFA-1, are expressed intensely in the synovia of patients with Lyme arthritis. Upregulation of LFA-1 on lymphocytes in this lesion may be critical in the pathogenesis of treatment-resistant Lyme arthritis.

Detection of ICAM-1 in experimentally induced colitis of ICAM-1-deficient and wild-type mice: an immunohistochemical study

Adhesion molecules (e.g. ICAM-1, CD 54) are known to be upregulated on activated vascular endothelial cells during inflammatory reactions. To study the role of ICAM-1 in intestinal inflammation in vivo, we induced acute experimental colitis in wild-type (C57BL/6) mice and ICAM-1-deficient mice, by feeding the animals with 3% dextran sodium sulphate (DSS) in drinking water for 7 days. In the control strain the immunohistochemical staining showed a very pronounced endothelial upregulation of ICAM-1 after the DSS treatment observed in areas of inflammatory infiltrate, especially in venules or arterioles of the propria and submucosa, and partly in the mesocolon. DSS-fed ICAM-1-deficient mice showed no endothelial enhancement and only faint staining of venules or capillaries approaching that encountered in the control ICAM-1-deficient animals. Our data indicate that ICAM-1 may play a crucial role in the development of acute intestinal inflammation, consistent with our finding that ICAM-1 deficiency can obviate severe forms of experimentally induced colitis in mice.

Cell-cell interactions in synovitis. Endothelial cells and immune cell migration

Leukocyte ingress into the synovium is a key process in the pathogenesis of rheumatoid arthritis and other inflammatory conditions. In this review, the role of endothelial cells in leukocyte extravasation will be discussed, including the role of the most relevant cellular adhesion molecules. These molecules play an important role in mediating leukocyte--endothelial interactions. It is likely that different adhesive pathways are involved in different steps of leukocyte adhesion to and migration through endothelia. Targeting of pathological endothelial function, including leukocyte--endothelial adhesion, may be useful for the future management of inflammatory arthritis.

Inhibitory effect of a new anti-rheumatic drug T-614 on costimulatory molecule expression, cytokine production, and antigen presentation by synovial cells

The present study was undertaken to investigate the immunoregulatory effects of T-614 (3-formylamino-7-methylsulfonylamino-6-phenoxy-4H-1-benzopyran-4-o ne) on synovial cells in vitro. Synovial cells were cultured with T-614 in the presence or absence of various cytokines. After incubation, the costimulatory molecule expression on synovial cells and cytokine production in culture supernatants were analyzed by an indirect immunofluorescence method and enzyme-linked immunosorbent assay, respectively. We also examined the effect of T-614 on the function of synovial cells as antigen-presenting cells (APCs). The costimulatory molecules including CD54, CD58, and CD106 were constitutionally expressed on the surface of synovial cells. However, neither CD80 nor CD86 nor CD102 was found on the surface, and these costimulatory molecules could not be induced by any cytokines. T-614 itself did not affect the costimulatory molecule expression and cytokine production of unstimulated synovial cells. The stimulation of synovial cells with interferon-gamma (IFN-gamma), interleukin-1beta, or 12-O-tetradecanoyl phorbol 13-acetate enhanced the expression of costimulatory molecules and the proinflammatory cytokine production of these cells. Both the up-regulated expression of these costimulatory molecules and the enhanced production of proinflammatory cytokines were significantly inhibited by T-614. Autologous T cell proliferation in response to purified protein derivative by IFN-gamma-treated synovial cells was significantly suppressed by T-614. T-614 has considerable immunosuppressive effects on synovial cells by inhibiting the costimulatory molecule expression and cytokine production of these cells and the antigen-specific T cell proliferation mediated by the synovial cells. These results suggest that T-614 plays an important immunoregulatory role in rheumatoid synovial tissues.

Establishment and characterization of nurse cell-like stromal cell lines from synovial tissues of patients with rheumatoid arthritis

OBJECTIVE

To investigate the features of synovial stromal cells established from patients with rheumatoid arthritis (RA), and to define these cells as nurse cells.

METHODS

Synovial nurse-like stromal cell lines (RA-SNCs) were established from patients with RA. These cell lines were examined for morphology, pseudoemperipolesis activity, cell surface markers, and cytokine production. The interaction between these RA-SNCs and a synovial tissue B cell clone was also examined.

RESULTS

RA-SNCs had nurse cell activity. They spontaneously produced interleukin-6 (IL-6), IL-8, granulocyte colony-stimulating factor, and granulocyte-macrophage colony-stimulating factor. Furthermore, they produced IL-1beta and tumor necrosis factor alpha and expressed higher levels of the other cytokines after coculture with the B cell clone. Proliferation and Ig production by the B cell clone were dependent on direct contact with RA-SNCs.

CONCLUSION

These results indicate that the RA-SNCs were nurse cells. The findings suggest that RA-SNCs may play an important role in the pathogenesis of RA by producing large amounts of cytokines and maintaining infiltrating lymphocytes.

T lymphocytes induce endothelial cell matrix metalloproteinase expression by a CD40L-dependent mechanism: implications for tubule formation

Neovascularization frequently accompanies chronic immune responses characterized by T cell infiltration and activation. Angiogenesis requires endothelial cells (ECs) to penetrate extracellular matrix, a process that involves matrix metalloproteinases (MMPs). We report here that activated human T cells mediate contact-dependent expression of MMPs in ECs through CD40/CD40 ligand signaling. Ligation of CD40 on ECs induced de novo expression of gelatinase B (MMP-9), increased interstitial collagenase (MMP-1) and stromelysin (MMP-3), and activated gelatinase A (MMP-2). Recombinant human CD40L induced expression of MMPs by human vascular ECs to a greater extent than did maximally effective concentrations of interleukin-1beta or tumor necrosis factor-alpha. Moreover, activation of human vascular ECs through CD40 induced tube formation in a three-dimensional fibrin matrix gel assay, an effect antagonized by a MMP inhibitor. These results demonstrated that activation of ECs by interaction with T cells induced synthesis and release of MMPs and promoted an angiogenic function of ECs via CD40L-CD40 signaling. As vascular cells at the sites of chronic inflammation, such as atherosclerotic plaques, express CD40 and its ligand, our findings suggest that ligation of CD40 on ECs can mediate aspects of vascular remodeling and neovessel formation during atherogenesis and other chronic immune reactions.

Sialyl Lewis(x) expression on IgG in rheumatoid arthritis and other arthritic conditions: a preliminary study

Both infiltrating leukocytes and soluble immunoglobulin form aggregates in synovial fluid during the inflammatory process in rheumatoid arthritis (RA). Some of these changes are probably mediated by the adhesion molecule, E-selectin, which increases its expression with disease activity. As glycosylation changes in IgG in RA are well established, the current study was undertaken to measure the expression of the carbohydrate antigen sialyl Lewis x (sLe(x)), on IgG in RA. sLe(x) is a major ligand for E-selectin. Using a recently developed ELISA, sLe(x) expression was determined in IgG isolated from 8 healthy individuals, 20 RA sufferers (10 early and 10 with more long-standing disease) and 20 patients with other rheumatic conditions (osteoarthritis, ankylosing spondylitis, systemic lupus erythematosus). S Le(x) expression on IgG was elevated above the reference range in all but one of the RA patients and this change was highly significant (P < 0.0006). Expression of this antigen on IgG was also significantly different from normal in the other arthritic groups (P < 0.02), but the changes were much less than that observed for RA. In early RA, sLe(x) was inversely correlated with parameters used to measure disease activity. This was not observed with the established RA, where there was weak positive association. These preliminary results indicate that a change in sLe(x) expression on IgG is an early finding in the development of RA, which may be important in the development of the disease or for predicting its outcome.

Cytokine-regulated expression of activated leukocyte cell adhesion molecule (CD166) on monocyte-lineage cells and in rheumatoid arthritis synovium

OBJECTIVE

To determine whether monocyte/macrophage expression of the CD6 ligand, activated leukocyte cell adhesion molecule (ALCAM) (CD166), is regulated by cytokines during inflammation in rheumatoid arthritis (RA).

METHODS

We used flow cytometry to test whether cytokines present in rheumatoid synovium could regulate ALCAM cell surface expression on peripheral blood (PB) monocytes and RA synovial fluid (SF) macrophages, and we examined ALCAM expression in situ in RA synovium by immunofluorescence.

RESULTS

The monocyte differentiation factors interleukin-3, macrophage colony-stimulating factor (M-CSF), and granulocyte-macrophage colony-stimulating factor augmented ALCAM expression on PB monocytes. ALCAM was expressed on monocyte-lineage cells in situ in inflamed synovium from patients with RA (9 of 9), but not in uninflamed synovium from patients with joint trauma (0 of 3). Furthermore, in vitro culture-induced ALCAM expression on PB monocytes and CD14+ RA SF cells was inhibited by an M-CSF neutralizing antibody.

CONCLUSION

ALCAM expression on PB and SF monocytes/macrophages is enhanced by M-CSF.

Pirfenidone induces intercellular adhesion molecule-1 (ICAM-1) down-regulation on cultured human synovial fibroblasts

Pirfenidone has been shown to modify some cytokine regulatory actions and inhibit fibroblast biochemical reactions resulting in inhibition of proliferation and collagen matrix synthesis by fibroblast. We have investigated the effect of pirfenidone on the expression of cell adhesion molecules. The synovial fibroblasts were treated with IL-1alpha in the presence or absence of pirfenidone (range 0-1000 microM), and assayed for the expression of adhesion molecules such as ICAM-1 and endothelial-leucocyte adhesion molecule-1 (E-selectin) by cell ELISA. Pirfenidone significantly down-regulated the expression of ICAM-1 on cultured synovial fibroblasts in a dose-dependent manner. In contrast, expression of E-selectin was not affected. Furthermore, we examined whether pirfenidone affects the cellular binding between cultured lymphocytes and IL-1alpha-stimulated synovial fibroblasts by in vitro binding assay and found their mutual binding was significantly suppressed in a dose-dependent manner by pirfenidone. It is speculated that down-regulation of ICAM-1 might be one of the novel mechanisms of action of pirfenidone. These data indicate a novel mechanism of action for pirfenidone to reduce the activation of synovial fibroblasts.

Expression of cell adhesion molecules and cytokines in murine antigen-induced arthritis

Adhesion molecules and cytokines are important in chronic inflammatory conditions such as rheumatoid arthritis (RA) by virtue of their role in cell activation and emigration. Using immunohistochemical techniques we studied the expression of adhesion molecules and cytokines in cryopreserved sections of murine knee joint in the course of antigen-induced arthritis, an animal model of human RA. Various adhesion molecules and cytokines are expressed in the arthritic joint tissue. LFA-1, Mac-1, CD44, ICAM-1 and P-selectin were strongly expressed in the acute phase and to a lesser degree in the chronic phase of arthritis. VLA-4 and VCAM-1 appeared to be moderately expressed on day 1, L-selectin between days 1 and 3. LFA-1, Mac-1, CD44, alpha 4-integrin, ICAM-1 and the selectins were found expressed on cells of the synovial infiltrate, LFA-1, Mac-1 and ICAM-1 on the synovial lining layer, and VCAM-1 and P-selectin on endothelial cells. Expression of E-selectin could be demonstrated throughout the experiment at a low level in cells of the acute cell infiltrate. Cytokines, especially IL-2, IL-4, IL-6, TNF, and IFN-gamma, were heavily expressed during the acute phase of arthritis in cellular infiltrate. Taken together these data demonstrate that cytokines and their activation of adhesion molecules contribute to cell infiltration and activation during the initial phase of arthritis and to the induction and progression of tissue destruction in arthritic joints. These molecules might be potential targets for novel therapeutic strategies in inflammatory and arthritic disorders.

New approaches to the management of acute and chronic cardiac allograft rejection

There are still many problems to be faced in the field of heart transplantation. Acute and chronic rejection are still the major medical obstacles. In this review, we describe recent research in this field undertaken in our laboratory. The induced intercellular adhesion molecule-1 (ICAM-1) and MHC class II antigen resulting from rejection can be visualized in vivo by radioimmunoscintigraphy. This non-invasive method is sensitive for detecting early rejection and allows quantitative assessment of rejection. Short-term administration of monoclonal antibodies to ICAM-1 and leukocyte function-associated antigen-1 (LFA-1) results in an indefinite acceptance of cardiac allografts by induction of antigen-specific tolerance, as evidenced by acceptance of the secondary skin allografts. The characteristics and possible mechanisms of this tolerance induction are discussed. Immunohistopathologic features of graft coronary arteriopathy are shown. Adhesion molecules, cytokines, and growth factors are associated with intimal hyperplasia and phenotypic transformation of smooth muscle cells in the allograft coronary arteries. Dramatic reduction in this intimal hyperplasia was demonstrated by antisense gene therapy targeting cyclin-dependent kinase 2 kinase. We hope that these investigations will contribute to the improvement of the management of patients who undergo heart transplantation.

Inhibitory effects of interleukin-10 on synovial cells of rheumatoid arthritis

This paper describes the immunoregulatory effects of interleukin-10 (IL-10) on synovial cells in vitro. Synovial cells were cultured with IL-10 in the presence or absence of various cytokines. Following incubation, the costimulatory molecule expression on synovial cells and cytokine production in culture supernatants were analysed by an indirect immunofluorescence method and enzyme-linked immunosorbent assay, respectively. We also examined the effect of IL-10 on the function of synovial cells as antigen-presenting cells (APC). Synovial cells spontaneously express several kinds of costimulatory molecule and produce various kinds of cytokines. Stimulation of synovial cells with interferon-gamma (IFN-gamma), IL-1 beta, or 12-O-tetradecanoyl phorbol 13-acetate (TPA) markedly enhanced the expression of costimulatory molecules and cytokine production of these cells. Both spontaneous and up-regulated costimulatory molecule expression and cytokine production were significantly suppressed by the addition of IL-10. Autologous T-cell proliferation was stimulated by purified protein derivative (PPD) in IFN-gamma-treated synovial cells and treatment of these synovial cells with IL-10 also suppressed T-cell proliferation. Our results suggest that IL-10 has an inhibitory effect on synovial cells and is an important immunoregulatory component of the cytokine network in rheumatoid arthritis.

New insights into the pathogenesis and treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic multisystemic inflammatory disease with autoimmune features, and of unknown cause, associated with characteristic joint deformities and increased mortality rate. The pathogenesis of this serious disease seems to be multifactorial, where several cytokines, particularly interleukin-1 and tumor necrosis factor-alpha, are strongly involved in the induction and perpetuation of the chronic inflammatory process of the joints in RA and in the systemic manifestations of the disease. Other factors, such as reactive oxygen species and metalloproteinases, may also participate in the destruction of the rheumatoid joint. Current treatments of RA are inadequate in that they only partially control established RA, and despite optimal use of current antirheumatic agents, the outcome of many patients with RA consists of pain, severe functional decline, and premature death. The gloomy recent data regarding the prognosis of RA with the use of the current treatments stress the need for new therapeutic regimens with the ability to effectively control the inflammatory process in the rheumatoid joint and to induce long-term remission or even cure. Controlling the production and the activity of the factors involved in the pathogenesis of the disease represents the major therapeutic goal. Since several factors are involved in the pathogenesis of RA, neutralizing one or some of these factors may be of only limited benefit. In this regard, interleukin-4 may be a very promising agent for an effective treatment of RA, because this cytokine is not limited by its inhibitory effects to a single factor, but rather it inhibits most of the main factors involved in the pathogenesis of the disease. Although recent data strongly support this approach with interleukin-4, controlled long-term clinical trails should be undertaken in order to prove the validity and the effectiveness of this promising approach.

The regulation of CD11b integrin levels on human blood leukocytes and leukotriene B4-stimulated skin by a specific leukotriene B4 receptor antagonist (LY293111)

CD11b is part of the beta2-integrin Mac-1 and plays an important role in neutrophil adhesion. Leukotriene B4 (LTB4) is an active upregulator of neutrophil CD11b-expression, acts as a potent chemoattractant to neutrophils and is also known to upmodulate epidermal proliferation. We performed a placebo-controlled study on LY293111, an oral LTB4 receptor antagonist. Twenty healthy male volunteers were randomised over three treatment groups that received placebo, 48 mg, or 200 mg drug twice daily for 10 days. Before and after treatment, flow cytometrical CD11b assessment was performed on in vitro LTB4-stimulated peripheral blood neutrophils. Additionally, skin biopsies were taken at 24 and 72 h after epicutaneous LTB4 application, before and after treatment. The effects on skin were assessed immunohistochemically using various markers. All observed effects were dose related. CD11b upregulation on blood neutrophils was significantly suppressed in both treatment groups compared to placebo. In skin, a significant suppression of inflammation and hyperproliferation occurred. Pronounced inhibition was observed on neutrophil migration into the epidermis and the inflammatory infiltrate was decreased. A similar but weaker response was seen in the dermis. The number of cycling cells as well as suprabasal keratin-16 expression were decreased in both treatment groups. LY293111 proved to be a potent inhibitor of LTB4-induced cutaneous inflammation and hyperproliferation. The potent antiinflammatory effect in vivo and the fact that in the present study the compound showed no clinically significant side effects make it an interesting drug in the future treatment of inflammatory conditions predominated by neutrophils.

Cytokine stimulation of T lymphocytes regulates their capacity to induce monocyte production of tumor necrosis factor-alpha, but not interleukin-10: possible relevance to pathophysiology of rheumatoid arthritis

Previous studies in the laboratory have shown that the pro-inflammatory cytokine tumor necrosis factor (TNF)-alpha plays a pivotal role in the pathogenesis of rheumatoid arthritis (RA). The mechanisms involved in regulating monocyte/macrophage cytokine production are not yet fully understood, but are thought to involve both soluble factors and cell/cell contact with other cell types. We and others have previously demonstrated that T cells activated through the T cell receptor/CD3 complex induce monocyte TNF-alpha production by contact-mediated signals. In this report, we investigated further whether T cells activated by cytokines in the absence of T cell receptor stimulation also regulate monocyte cytokine production. T cells were activated in an antigen-independent manner using the cytokines interleukin (IL)-15 or IL-2 alone, or in combination with IL-6 and TNF-alpha. Subsequently, T cells were fixed and incubated with monocytes. Fixed, cytokine-stimulated T cells induced monocytes to secrete TNF-alpha in a dose-dependent manner, but did not induce secretion of IL-10, a potent endogenous down-regulator of TNF-alpha and other pro-inflammatory cytokines. Stimulation of monocyte TNF-alpha was markedly inhibited when T cells were physically separated from monocytes within the tissue culture well, confirming that T cell contact is necessary. T cell acquisition of monocyte-activating capacity was shown to be dependent on the period of cytokine stimulation, with T cells activated for 8 days more effective than T cells activated for shorter periods. Addition of interferon-gamma or granulocyte/macrophage colony-stimulating factor to the T cell/monocyte cultures enhanced T cell induction of monocyte TNF-alpha by threefold and ninefold, respectively. The results from this model of cognate interaction suggest that cytokine-stimulated T cells, interacting with macrophages in the rheumatoid synovial membrane, may contribute to the continuous excessive production of TNF-alpha observed in the RA joint, and to the imbalance of pro-inflammatory cytokines over anti-inflammatory cytokines.

Effects of pulse methylprednisolone on cell adhesion molecules in the synovial membrane in rheumatoid arthritis. Reduced E-selectin and intercellular adhesion molecule 1 expression

OBJECTIVE

To investigate the effects of a 1,000-mg intravenous pulse of methylprednisolone succinate (MP) on cell adhesion molecule expression on the synovial vascular endothelium in patients with rheumatoid arthritis (RA).

METHODS

Sequential arthroscopic biopsy samples were taken before and 24 hours after MP administration (10 patients) and at the time of RA flare (2 patients) and after retreatment with MP (1 patient). Immunoperoxidase staining for E-selectin (CD62E), P-selectin (CD62P), intercellular adhesion molecule 1 (ICAM-1; CD54) and platelet-endothelial cell adhesion molecule (PECAM; CD31) was performed, and the staining was quantified by color video image analysis.

RESULTS

MP caused a rapid (within 24 hours) and substantial decrease in the expression of E-selectin on the synovial vascular endothelium, with a smaller reduction in ICAM-1 expression on synovial vascular endothelium and the synovial lining. There were no similar effects on synovial membrane P-selectin or PECAM expression.

CONCLUSION

A potential mechanism by which MP impairs neutrophil trafficking into inflamed RA joints might be by reducing E-selectin, and possibly, ICAM-1, expression in the synovial membrane.

Inhibitory effect of fluvastatin, an HMG-CoA reductase inhibitor, on the expression of adhesion molecules on human monocyte cell line

The effect of fluvastatin, an HMG-CoA reductase inhibitor, was investigated on the adhesive interaction between U937 cells, the human monocyte cell line, and human umbilical vein endothelial cells (HUVEC), focusing on the expression of adhesion molecules. U937 treated with fluvastatin lowered the capacity for binding to HUVEC. Fluvastatin at 0.1 microM or more inhibited the expression of lymphocyte function associated antigen-1 (LFA-1) on U937 and intercellular adhesion molecule-1 (ICAM-1) on U937. The expression of ICAM-1 on HUVEC was not inhibited by fluvastatin. The inhibitory effects of fluvastatin on the expression of adhesion molecules on U937 were completely reversed by the addition of mevalonate. Because fluvastatin did not affect the expression of other cell surface markers, CD4 and CD71, the inhibitory effects of fluvastatin on adhesion molecule expression could not be attributed to the non-specific suppression of the cell. It is conceivable that cellular interaction between monocytes and endothelial cells is inhibited by fluvastatin, mediated via reducing the expression of adhesion molecules, particularly in the side of monocyte.

Human osteoclast formation and bone resorption by monocytes and synovial macrophages in rheumatoid arthritis

OBJECTIVE

To determine whether synovial macrophages and monocytes isolated from patients with rheumatoid arthritis patients are capable of differentiating into osteoclastic bone resorbing cells; and the cellular and humoral conditions required for this to occur.

METHODS

Macrophages isolated from the synovium and monocytes from the peripheral blood of rheumatoid arthritis patients were cultured on bone slices and coverslips, in the presence and absence of UMR 106 rat osteoblast-like cells, 1,25-dihydroxy vitamin D3 (1,25(OH)2D3) and macrophage colony stimulating factor (M-CSF), and assessed for cytochemical and functional evidence of osteoclast differentiation.

RESULTS

Isolated calcitonin receptor (CTR), tartrate resistant acid phosphatase (TRAP), and vitronectin receptor (VNR) negative, CD11b and CD14 positive monocytes and macrophages differentiated into CTR, TRAP, and VNR positive multinucleated cells capable of extensive lacunar bone resorption when co-cultured for 14 d with UMR 106 cells in the presence 1,25(OH)2D3 and M-CSF.

CONCLUSIONS

Mononuclear phagocytes (monocytes and macrophages) from rheumatoid arthritis patients are capable of differentiating into multinucleated cells showing all the cytochemical and functional criteria of mature osteoclasts. Synovial macrophage-osteoclast differentiation may represent an important cellular mechanism in the bone destruction associated with rheumatoid arthritis.

Cellular adhesion molecules in rat adjuvant arthritis

OBJECTIVE

To examine adhesion molecule expression during the progression of inflammation in a rheumatoid arthritis model of adjuvant-induced arthritis (AIA) in rats.

METHODS

Immunohistochemical analysis was used to determine the distribution of the following adhesion molecules: lymphocyte function-associated antigen 1 (LFA-1; CD11a/CD18), Mac-1 and p150/95 (CD11bc/CD18), intercellular adhesion molecule 1 (ICAM-1), and CD44 in tissue sections from the ankle joints of rats with AIA. Control animals and those with AIA were killed at intervals over a 54-day period after injection with mineral oil and Mycobacterium butyricum, respectively.

RESULTS

CD44 and LFA-1 were expressed on lymphocytes, macrophages, and synovial (ST) lining cells. CD44 expression on macrophages was found to be increased compared with control animals by day 18, and was significantly increased by day 41. CD44 expression on lymphocytes significantly increased earlier, on days 11-18. Increased LFA-1 expression on macrophages occurred late, on day 41. LFA-1 expression on lymphocytes was significantly increased on days 25, 47, and 54. ST lining cells exhibited two distinct periods of increased expression, one early, on days 11-25 and one later, on days 41-54. CD11b/c was expressed on macrophages and ST lining cells, showing a significant increase on AIA rat ST lining cells compared with control animals on day 4. No differences in ICAM-1 expression on endothelial cells between rats with AIA and controls were found on any of the days examined.

CONCLUSION

CD44 expression is up-regulated on macrophages and lymphocytes during the early development of AIA, while LFA-1 expression is up-regulated later in the development of AIA. The up-regulation of CD44 and LFA-1 at different times in the development of AIA suggests an important role for these adhesion molecules in establishing and sustaining an inflammatory response in the AIA joint.

Endothelin-1 modulates the expression of adhesion molecules on fibroblast-like synovial cells (FLS)

Endothelin-1 is known to possess various biological properties. In the present study we have investigated the effects of Endothelin-1 (Et-1) on the expression of adhesion molecules ICAM-1, VCAM-1 and CD-44 by fibroblast-like synoviocytes. Cultured fibroblast-like synoviocytes were treated with Et-1 in the absence or presence of C1306, a specific endothelin-A-receptor antagonist. Cell surface expression of ICAM-1, VCAM-1 and CD-44 was determined by immunofluorescence studies, Cyto-ELISA and FACS-analysis. ICAM-1, VCAM-1 and CD-44 were constitutively expressed on cultured FLS. After incubation with Et-1 the expression of ICAM-1, VCAM-1 and CD-44 increased. The level of expression of adhesion molecules after Et-1 stimulation was similar to cytokine mediated effects (IL-1 beta, TNF-alpha). IL-1 beta showed the strongest stimulatory effect on the expression of ICAM-1, TNF-alpha preferentially induced the expression of VCAM-1 and CD-44, and Et-1 strongly stimulated the upregulation of CD-44 expression. In addition, Et-1 enhanced significantly the IL-1 beta mediated upregulation of VCAM-1 expression, whereas TNF-alpha mediated expression of VCAM-1 was downregulated by Et-1. Furthermore, the Et-1 induced expression of adhesion molecules on FLS was mediated via the endothelin-A-receptor (EtA-receptor), since C-1306, a selective endothelin-A-receptor antagonist, could block this effect. These results indicate that Et-1 has stimulating effects on FLS in vitro. The expression of adhesion molecules can be upregulated by Et-1 similar to proinflammatory cytokines. The modulating effect of Et-1 can be inhibited by the pretreatment with a selective EtA-receptor antagonist. Thus, Et-1 may have immunoregulatory functions in the recruitment of cells infiltrating the inflamed tissue.

Intercellular adhesion molecule-1 induction: a sensitive and quantitative marker for cardiac allograft rejection

OBJECTIVES

Rats with abdominal heterotopic heart transplants were studied to determine whether cardiac allograft rejection could be assessed by immunoscintigraphy targeting intercellular adhesion molecule-1 (ICAM-1), which was induced on allografted organ cells in association with rejection.

BACKGROUND

It is important to detect early rejection before development of myocyte necrosis. Although a variety of methods for the detection of cardiac rejection have been investigated, histologic inspection of biopsied samples is still used routinely for clinical diagnosis of rejection.

METHODS

DA rat (RT-1a) hearts were transplanted into PVG rats (RT-1c). Immunohistologic examination of the allografts demonstrated that ICAM-1 induction on vascular endothelial cells was observed as early as 4 days after transplantation in this combination. Thirty-nine allografted rats and seven isografted rats were studied. One day after injection of 100 microCi of 111Inlabeled anti-ICAM-1 monoclonal antibody (1A29), planar images were obtained.

RESULTS

Rejecting allografts showed increased radiotracer uptake and could be identified on the images as early as 5 days after transplantation. In contrast, nonrejecting cardiac allografts and isografts did not show specific uptake. Mildly rejecting allografts, with mononuclear cell infiltration but without significant myocyte necrosis, could be scintigraphically identified, and the level of radiotracer uptake reflected the histologic severity of rejection. Accumulation of 111In-labeled monoclonal antibody of isotype-matched irrelevant specificity was not detected in the rejecting allografts.

CONCLUSIONS

These data indicate that ICAM-1 induction can be assessed quantitatively by radioimmunoscintigraphy. Radioimmunoscitigraphy is a sensitive method for early detection and assessment of cardiac allograft rejection.

Serum intercellular adhesion molecule (ICAM-1), a marker of renal scarring in infants with vesico-ureteric reflux

OBJECTIVE

To determine if serum intercellular adhesion molecule (ICAM-1) levels correlate with renal scarring in children with vesico-ureteric reflux (VUR).

PATIENTS AND METHODS

Serum ICAM-1 levels were measured in 81 children (29 boys and 52 girls, age range 2 months-13 years) with VUR using an enzyme-linked immunosorbent assay (ELISA) and compared with levels in a control group of 24 children (16 boys and eight girls, age range 2 days-13 years) with no urological abnormalities.

RESULTS

The mean serum ICAM-1 level in the control group was 202 +/- 79 ng/mL (mean +/- 1 SD) compared with 347 +/- 96 ng/mL in children with VUR (P < 0.001). Fifteen of 26 children under 2 years of age demonstrated renal scarring while 18 of 44 children older than 2 years exhibited renal scarring. The mean serum ICAM-1 level in patients who were < 2 years of age and had renal scarring was 408 +/- ng/mL, significantly higher than in those who had no renal scarring (296 +/- 68 ng/mL, P < 0.01). In contrast, there was no difference in serum ICAM-1 levels in patients > 2 years of age with or with no renal scarring (353 +/- 87 and 325 +/- 91 ng/mL, respectively).

CONCLUSION

Serum ICAM-1 levels are significantly higher in children with VUR and may represent a valuable marker of tubular damage in younger children with VUR.

Removal of LDL from plasma by adsorption reduces adhesion molecules on mononuclear cells in patients with arteriosclerosis obliterans

BACKGROUND

There is increasing evidence that immune processes are important in the development of atherosclerosis. We investigated whether low density lipoprotein (LDL) adsorption therapy affected serum cytokine levels and the expression of adhesion molecules on peripheral blood mononuclear cells (lymphocytes and monocytes) in patients with arteriosclerotic obliterance (ASO).

METHODS AND RESULTS

LDL adsorption therapy was repeated ten times over a period of three months in ten ASO patients. The total serum cholesterol and LDL cholesterol levels were significantly reduced at the end of therapy. This was associated with a significant improvement in Fontaine's classification and ankle pressure index. We also measured serum levels of inflammatory cytokines (interleukin-1 beta (IL-1 beta), IL-6 and tissue necrosis factor alpha (TNF-alpha)) and expression of adhesion molecules (lymphocyte function-associated antigen 1 alpha (LFA-1 alpha), LFA-1 beta, CD2, very late antigen (VLA)-4, VLA-5 and CD44) on mononuclear cells in the same patients and a group of healthy subjects. Serum levels of all inflammatory cytokines were markedly higher in ASO patients compared with healthy subjects, but there was no significant difference in the level before and after LDL adsorption. VLA-4 expression on CD3+ cells, but not of other adhesion molecules, was markedly higher in ASO patients compared with healthy subjects. LDL adsorption caused a significant reduction in CD2, VLA4 and VLA-5 expression on CD3+ cells. Furthermore, VLA-4 and VLA-5 expression on monocytes diminished significantly after LDL adsorption.

CONCLUSIONS

Our results indicate that LDL adsorption-induced immunoregulation is mediated by an indirect stimulatory effect on the immune system. The results suggests that improved peripheral circulation produced by LDL adsorption may reflect improved immune dysfunctions of atherosclerotic lesions in ASO patients.

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.

Adhesion molecules in inflammatory bowel disease

The ability of leucocytes to adhere to endothelium is essential for leucocyte migration into inflammatory sites. Some of these adhesion molecules are released from the cell surface and can be detected in serum. The soluble adhesion molecules intercellular adhesion molecule 1 (ICAM-1), E selectin, and vascular cell adhesion molecule 1 (VCAM-1) were studied in the serum of patients with Crohn's disease, ulcerative colitis, and healthy controls. A second blood sample was taken from patients with active disease after one month of treatment and a third two months after remission was achieved. Tissue expression of the same adhesion molecules was studied by immunohistology. Circulating VCAM-1 concentrations were significantly higher in patients with active ulcerative colitis (n = 11, median = 165 U/ml) compared with patients with inactive ulcerative colitis (n = 10, median = 117 U/ml, p < 0.005), active Crohn's disease (n = 12, median = 124 U/ml, p < 0.02), and controls (n = 90, median = 50 U/ml, p < 0.0001). Within each disease group there were no significant differences in E selectin or ICAM-1 concentrations between the active and inactive states, however, patients with active Crohn's disease had significantly higher ICAM-1 concentrations (n = 12, median = 273 ng/ml) than controls (n = 28, median = 168, p < 0.003). VCAM-1 concentrations fell significantly from pretreatment values to remission in active ulcerative colitis (p < 0.01). In Crohn's disease there was a significant fall in ICAM-1 both during treatment (p < 0.01) and two months after remission (p < 0.02). Vascular expression of ICAM-1 occurred more often and was more intense in inflamed tissue sections from patients with ulcerative colitis and Crohn's disease than from controls. Vascular labelling with antibody to E selectin also occurred more often in patients with active inflammatory bowel disease. In conclusion, increased circulating concentrations of selected adhesion molecules are associated with inflammatory bowel disease. There is also evidence of local upregulation, particularly of ICAM-1. Differential expression of adhesion molecules in tissue may play a part in the initiation of leucocyte migration and local inflammation; the function of circulating adhesion molecules is unknown, but may play a physiological part in blocking adhesion.

Extracellular matrix of the synovial intimal cell layer

Images

Molecular cloning and chromosomal mapping of a bone marrow stromal cell surface gene, BST2, that may be involved in pre-B-cell growth

Bone marrow stromal cells regulate B-cell growth and development through their surface molecules and cytokines. In this study, we generated a mAb, RS38, that recognized a novel human membrane protein, BST-2, expressed on bone marrow stromal cell lines and synovial cell lines. We cloned a cDNA encoding BST-2 from a rheumatoid arthritis-derived synovial cell line. BST-2 is a 30- to 36-kDa type II transmembrane protein, consisting of 180 amino acids. The BST-2 gene (HGMW-approved symbol BST2) is located on chromosome 19p13.2. BST-2 is expressed not only on certain bone marrow stromal cell lines but also on various normal tissues, although its expression pattern is different from that of another bone marrow stromal cell surface molecule, BST-1. BST-2 surface expression on fibroblast cell lines facilitated the stromal cell-dependent growth of a murine bone marrow-derived pre-B-cell line, DW34. The results suggest that BST-2 may be involved in pre-B-cell growth.