Cytokines in rheumatoid arthritis. Potential targets for pharmacological intervention

Anti-inflammatory and anti-oxidant activities of mesenchymal stem cells in chemically induced arthritic rats

BACKGROUND

Mesenchymal stem cells (MSCs) have been extensively used as cell-based treatments for decades due to their anti-inflammatory, immunomodulatory, and healing abilities. The intent of our study was to determine the efficacy of MSCs in alleviating rheumatoid arthritis (RA) induced by Complete Freund's adjuvant (CFA) and to investigate the anti-inflammatory and antioxidant characteristics of MSCs.

METHODS AND RESULTS

Intrapedally injecting 0.1 ml of CFA directly into the footpad of the right hind paw daily for 2 days was used to induce RA. Arthritic rats received four doses of MSCs (1 × 106 cells/rat/dose) intravenously through the lateral tail vein. Our results showed that arthritic rats treated with MSCs exhibited reduced levels of paw edema. Furthermore, arthritic rats treated with MSCs exhibited a significant decrease in the levels of RF, CRP, IL-1β, TNF-α, IL-17 and ADAMTS-5, along with a significant increase in the levels of IL-4 and TIMP-3. Additionally, MSCs significantly reduced the expression of TGF-β. Both the glutathione (GSH) content and antioxidant activity of GST were enhanced by MSCs, while LPO levels were suppressed.

CONCLUSION

These findings provide further evidence that MSCs are valuable in treating RA, possibly due to their anti-inflammatory and anti-oxidative properties. Thus, MSCs have potential as a more effective therapeutic strategy for treating RA.

Effects of 1-year tofacitinib therapy on angiogenic biomarkers in rheumatoid arthritis

OBJECTIVES

Cardiovascular (CV) morbidity and mortality, and perpetuated synovial angiogenesis have been associated with RA. In our study we evaluated angiogenic factors in relation to vascular inflammation and function, and clinical markers in RA patients undergoing 1-year tofacitinib therapy.

METHODS

Thirty RA patients treated with either 5 mg or 10 mg twice daily tofacitinib were included in a 12-month follow-up study. Eventually, 26 patients completed the study and were included in data analysis. Levels of various angiogenic cytokines (TNF-α, IL-6), growth factors [VEGF, basic fibroblast (bFGF), epidermal (EGF), placental (PlGF)], cathepsin K (CathK), CXC chemokine ligand 8 (CXCL8), galectin-3 (Gal-3) and N-terminal prohormone brain natriuretic peptide (NT-proBNP) were determined at baseline, and at 6 and 12 months after initiating tofacitinib treatment. In order to assess flow-mediated vasodilation, common carotid intima-media thickness (ccIMT) and carotid-femoral pulse-wave velocity, ultrasonography was performed. Synovial and aortic inflammation was also assessed by 18F-fluorodeoxyglucose-PET/CT.

RESULTS

One-year tofacitinib therapy significantly decreased IL-6, VEGF, bFGF, EGF, PlGF and CathK, while it increased Gal-3 production (P < 0.05). bFGF, PlGF and NT-proBNP levels were higher, while platelet-endothelial cell adhesion molecule 1 (PECAM-1) levels were lower in RF-seropositive patients (P < 0.05). TNF-α, bFGF and PlGF correlated with post-treatment synovial inflammation, while aortic inflammation was rather dependent on IL-6 and PECAM-1 as determined by PET/CT (P < 0.05). In the correlation analyses, NT-proBNP, CXCL8 and Cath variables correlated with ccIMT (P < 0.05).

CONCLUSIONS

Decreasing production of bFGF, PlGF or IL-6 by 1-year tofacitinib therapy potentially inhibits synovial and aortic inflammation. Although NT-proBNP, CXCL8 and CathK were associated with ccIMT, their role in RA-associated atherosclerosis needs to be further evaluated.

Effects of tofacitinib therapy on arginine and methionine metabolites in association with vascular pathophysiology in rheumatoid arthritis: A metabolomic approach

Introduction

Rheumatoid arthritis (RA) has been associated with changes in lipid, arginine and NO metabolism with increased cardiovascular (CV) risk. The aim of this study is to evaluate the effect of tofacitinib, a Janus kinase (JAK) inhibitor, on arginine and methionine metabolism in correlation with inflammation, functional and pathological vascular changes during one-year treatment of patients with RA.

Materials and methods

Thirty RA patients with active disease were treated with either 5 mg bid or 10 mg bid tofacitinib for 12 months. We determined DAS28, CRP, IgM rheumatoid factor (RF) and anti-cyclic citrullinated peptide (CCP) levels. We assessed brachial artery flow-mediated vasodilation (FMD), carotid intima-media thickness (IMT) and pulse-wave velocity (PWV) by ultrasound at baseline and after 6 and 12 months. We also determined plasma L-arginine, L-citrulline, L-ornithine, inducible nitric oxide synthase (iNOS), asymmetric (ADMA) and symmetric dimethylarginine (SDMA), L-N-monomethyl-arginine (L-NMMA), cysteine, homocysteine, and methionine levels at these time points.

Results

Twenty-six patients (13 on each arm) completed the study. CRP, ESR and DAS28 decreased significantly during one-year treatment with tofacitinib. Arginine and ADMA showed a negative univariate correlation with CRP but not with FMD, PWV or IMT. Tofacitinib at 10 mg bid significantly increased L-arginine, L-ornithine, iNOS and methionine levels after 12 months. ADMA and SDMA levels did not change in our study. Methionine showed negative correlation with FMD at baseline and positive correlation with PWV after 12 months. No change was observed in FMD and PWV but a significant increase was measured in IMT at 6 and 12 months. Multivariate analysis indicated variable correlations of L-arginine, L-citrulline, ADMA, L-NMMA, homocysteine and methionine with DAS28, CRP, ESR and RF but not with anti-CCP after one-year treatment. With respect to vascular pathophysiology, only PWV and methionine correlated with each other.

Conclusion

One-year tofacitinib treatment suppressed systemic inflammation and improved functional status in RA. FMD, PWV have not been affected by one-year tofacitinib treatment., while IMT increased further despite treatment. Increased arginine and methionine might contribute to the anti-inflammatory effects of tofacitinib. Increased arginine availability with no changing ADMA may protect FMD and PWV from deterioration. The increase of IMT in the anti-inflammatory environment cannot be explained by arginine or methionine metabolism in this study.

Umbelliferone Ameliorates Complete Freund Adjuvant-Induced Arthritis via Reduction of NF-κB Signaling Pathway in Osteoclast Differentiation

Osteoclasts, bone-resorbing somatic cells, are directly responsible for bone destruction during rheumatoid arthritis. Complete Freund adjuvant (CFA) is a widely used animal model using rodents for studying rheumatoid arthritis (RA), which effectively manifests serious cartilage destruction and progressive bone erosion, affecting synovial joints and serious joint dysfunction. It was considered that joint injury in RA is induced through systemic inflammation pathway. Umbelliferone (UF), a coumarin derivative of Agele marmilosa, possesses anti-inflammatory activity. In the current study, we scrutinize the effect of umbelliferone on CFA-induced arthritis model and explore the possible mechanism on bone destruction. Intradermal administration of CFA (0.05 mL) was to induce RA manifestations in the experimental rats and the same oral administration of UF was received. The anti-arthritic activity of UF was determined by its inhibitory activity on various biochemical markers, viz., pro-inflammatory, inflammatory, antioxidant enzymes, and hematological parameters elevated during RA condition. We also estimated the mRNA expression of osteoclast parameters. Obtained result disclosed significant reduction in the paw edema and increment of the body weight after UF administration. UF reduce the inflammatory mediatory such as COX-2, PGE₂, NF-kB, and VEGF; pro-inflammatory cytokines include TNF-α, IL-1β, IL-6, IL-10, and IL-17 significantly. Moreover, UF treatment significantly reduced the osteoclast number via modulating the RANKL/RANK/OPG ratio. Furthermore, administration of umbelliferone significantly (P < 0.001) suppressed the NF-κB and VEGF. Collectively, our results indicated the novel role of umbelliferone in osteoclastogenesis and proved that umbelliferone is a modern therapeutic tool as a natural agent for treating arthritis and other autoimmune disorders with bone degradation.

Discovery of Potent Small-Molecule Inhibitors of Ubiquitin-Conjugating Enzyme UbcH5c from α-Santonin Derivatives

As a therapeutic target for antitumor necrosis factor (TNF)-α interventions, UbcH5c is one of the key ubiquitin-conjugating enzymes catalyzing ubiquitination during TNF-α-triggered nuclear factor kappa B (NF-κB) activation. In the present study, three series of analogues were designed and synthesized from α-santonin, and their UbcH5c inhibitory activities were screened by Western blotting and NF-κB luciferase assay. Further BIAcore, in-gel fluorescence imaging, and immunoprecipitation assays demonstrated that compound 6d exhibited robust and specific inhibition of UbcH5c, exceeding that of the positive compound 1 (IJ-5). Mechanistic investigations revealed that compound 6d preferentially bound to and inactivated UbcH5c by forming a covalent adduct with its active site Cys85. Furthermore, compound 6d exhibited potent anti-inflammatory activity against complete Freund's adjuvant-induced adjuvant arthritis in vivo. These findings suggest that the novel α-santonin-derived UbcH5c inhibitor 6d is a promising lead compound for the development of new antirheumatoid arthritis (RA) agent.

Boi-ogi-to (TJ-20), a Kampo Formula, Suppresses the Inflammatory Bone Destruction and the Expression of Cytokines in the Synovia of Ankle Joints of Adjuvant Arthritic Rats

TJ-20 is a formula consisting of 6 herbs that has been used in the clinical treatment of rheumatoid arthritis (RA) in China and Japan for centuries. However, scientific evidence of the effects of TJ-20 has not been established. In the present study, we focused on the therapeutic effects and investigated the main function of TJ-20 on adjuvant arthritis (AA), an animal model of RA, which was induced with complete Freund's adjuvant (CFA). TJ-20 was administered orally at 600 mg/kg once a day from 0, 7, and 10 days to 8 weeks after the CFA treatment. TJ-20 significantly ameliorated inflammatory progression and bone destruction in AA in a time-dependent manner. Furthermore, TJ-20 significantly reduced the increased changes in a number of macrophages and helper T cells. Moreover, TJ-20 suppressed the expression of TNF-α whereas it augmented the expression of IL-10 and attenuated Th1 cells responses in the synovia of the ankle joint. Therefore, TJ-20 regulated the expression of proinflammatory and anti-inflammatory cytokines in macrophages and Th1/Th2 balance in the synovia of ankle joints in AA rats. These results suggest the positive anti-inflammatory effect of TJ-20 and provide a scientific basis for the clinical use of TJ-20 for RA.

Colony-Specific Differences in Endocrine and Immune Responses to an Inflammatory Challenge in Female Sprague Dawley Rats

Sprague Dawley rats from different vendor colonies display divergent responses in a variety of experimental paradigms. An adjuvant-induced arthritis (AA) model of human rheumatoid arthritis was used to examine immune and endocrine responses to inflammatory challenge in Sprague Dawley rats from Charles River and Harlan colonies. Rats were injected with either complete Freund's adjuvant or physiological saline (control), weights, and paw volumes measured over 15 days, and blood and tissue were collected 16 days post-injection. Overall, Harlan rats developed more severe AA than Charles River rats. In addition, despite comparable corticosterone levels, corticosteroid binding globulin levels were lower in Harlan compared with Charles River rats in the absence of inflammation, suggesting that a lower corticosterone reservoir in Harlan rats may underlie their greater susceptibility to inflammation. With increasing AA severity, there was an increase in plasma corticosterone (total and free) and a decrease in corticosteroid binding globulin in both Charles River and Harlan rats. However, contrasting patterns of cytokine activation were observed in the hind paw, suggesting a reliance on different cytokine networks at different stages of inflammation, with Charles River rats exhibiting increased TNF-α, monocyte chemotactic protein-1 (MCP-1), keratinocyte chemoattractant/growth-regulated oncogene (KC/GRO), and IL-1β in the absence of clinical signs of arthritis, whereas Harlan had increased TNF-α, monocyte chemotactic protein-1, and IL-6 with mild to moderate arthritis. These colony-specific differences in endocrine and immune responses to AA in Sprague Dawley rats must be considered when comparing data from different laboratories and could be exploited to provide insight into physiological changes and therapeutic outcomes in arthritis and other inflammatory disorders.

A key role for Fut1-regulated angiogenesis and ICAM-1 expression in K/BxN arthritis

OBJECTIVES

Angiogenesis contributes to the pathogenesis of rheumatoid arthritis. Fucosyltransferases (Futs) are involved in angiogenesis and tumour growth. Here, we examined the role of Fut1 in angiogenesis and K/BxN serum transfer arthritis.

METHODS

We examined Fut1 expression in human dermal microvascular endothelial cells (HMVECs) by quantitative PCR. We performed a number of angiogenesis assays to determine the role of Fut1 using HMVECs, Fut1 null (Fut1(-/-)), and wild type (wt) endothelial cells (ECs) and mice. K/BxN serum transfer arthritis was performed to determine the contribution of Fut1-mediated angiogenesis in Fut1(-/-) and wt mice. A static adhesion assay was implemented with RAW264.7 (mouse macrophage cell line) and mouse ECs. Quantitative PCR, immunofluorescence and flow cytometry were performed with Fut1(-/-) and wt ECs for adhesion molecule expression.

RESULTS

Tumour necrosis factor-α induced Fut1 mRNA and protein expression in HMVECs. HMVECs transfected with Fut1 antisense oligodeoxynucleotide and Fut1(-/-) ECs formed significantly fewer tubes on Matrigel. Fut1(-/-) mice had reduced angiogenesis in Matrigel plug and sponge granuloma angiogenesis assays compared with wt mice. Fut1(-/-) mice were resistant to K/BxN serum transfer arthritis and had decreased angiogenesis and leucocyte ingress into inflamed joints. Adhesion of RAW264.7 cells to wt mouse ECs was significantly reduced when Fut1 was lacking. Fut1(-/-) ECs had decreased intercellular adhesion molecule-1 (ICAM-1) expression at mRNA and protein levels compared with wt ECs. ICAM-1 was also decreased in Fut1(-/-) arthritic ankle cryosections compared with wt ankles.

CONCLUSIONS

Fut1 plays an important role in regulating angiogenesis and ICAM-1 expression in inflammatory arthritis.

Orphan receptor GPR15/BOB is up-regulated in rheumatoid arthritis

Chemokine receptors on leukocytes mediate the recruitment and accumulation of these cells within affected joints in chronic inflammatory diseases such as rheumatoid arthritis (RA). Identification of involved receptors offers potential for development of therapeutic interventions. The objective of this study was to investigate the expression of orphan receptor GPR15/BOB in the synovium of RA and non-RA patients and in peripheral blood of RA patients and healthy donors. GPR15/BOB protein and messenger RNA expression were examined in RA and non-RA synovium by immunofluorescence and reverse-transcription polymerase chain reaction (RT-PCR) respectively. GPR15/BOB expression on peripheral blood leukocytes was analysed by flow cytometry and GPR15/BOB messenger RNA was examined in peripheral blood monocytes by RT-PCR. GPR15/BOB protein was observed in CD68+ and CD14+ macrophages in synovia, with greater expression in RA synovia. GPR15/BOB protein was expressed in all patient synovia whereas in non-RA synovia expression was low or absent. Similarly GPR15/BOB messenger RNA was detected in all RA and a minority of non-RA synovia. GPR15/BOB protein was expressed on peripheral blood leukocytes from RA and healthy individuals with increased expression by monocytes and neutrophils in RA. GPR15/BOB messenger RNA expression was confirmed in peripheral blood monocytes. In conclusion GPR15/BOB is expressed by macrophages in synovial tissue and on monocytes and neutrophils in peripheral blood, and expression is up-regulated in RA patients compared to non-RA controls. This orphan receptor on monocytes/macrophages and neutrophils may play a role in RA pathophysiology.

Protective efficacy of N-(2-hydroxyphenyl) acetamide against adjuvant-induced arthritis in rats

Rheumatoid arthritis is a chronic inflammatory joint disease characterized by synovial proliferation and tissue destruction. Proinflammatory cytokines like interleukin-1beta (IL-1β) and tumor necrosis factor-alpha (TNF-α) play a key role in the disease process and elevate energy expenditure, which further increases the joint pain and stiffness. To explore the effects of N-(2-hydroxyphenyl) acetamide (NA-2) on the development of arthritis, clinical signs, histopathology of knee joints, nociception analysis, and the serum levels of IL-1β and TNF-α were monitored. Arthritis was induced by intradermal administration of heat-killed adjuvant Mycobacterium tuberculosis H37Ra in rats. NA-2 and indomethacin treatments were started in their respective group on the same day when adjuvant was administered. Experiments were terminated when arthritic score of 4 was observed in arthritic control group. NA-2 (5 mg/kg) treatment significantly ameliorated the disease severity. Reduction in body weight and increase in paw oedema were significantly reversed in arthritic animal receiving NA-2. The nociceptive sensation was also inhibited in the NA-2 treated arthritic rats. Remission was associated with improved histology and significant decreased expression of serum proinflammatory cytokines (P < 0.05 for IL-1β and TNF-α). Based on our observations, it can be suggested that NA-2 possesses promising anti-arthritic property, and it can be used as a therapeutic agent for arthritis.

Antihyperglycemic, hypolipidemic and antioxidant activities of ethanolic extract of Commiphora mukul gum resin in fructose-fed male Wistar rats

High fructose feeding (66 % of fructose) induces type-2 diabetes in rats, which is associated with the insulin resistance, hyperinsulinemia, hypertriglyceridemia and oxidative stress. The present study was undertaken to evaluate the effect of ethanol extract of Commiphora mukul gum resin (CMEE) on blood glucose, plasma insulin, lipid profiles, reduced glutathione, lipid peroxidation, protein oxidation and enzymatic antioxidants like superoxide dismutase, catalase, glutathione reductase, glutathione peroxidase, glutathione-S-transferase in fructose-induced type-2 diabetic rats. A significant gain in body weight, hyperglycemia, hyperinsulinemia, increased lipid profiles, lipid peroxidation, protein oxidation and decreased reduced glutathione, activities of enzymatic antioxidants and insulin sensitivity (increased homeostasis assessment assay) were observed in high-fructose-induced diabetic rats. The administration of CMEE (200 mg/kg/day) daily for 60 days in high-fructose-induced diabetic rats reversed the above parameters significantly. CMEE has the ability to improve insulin sensitivity and delay the development of insulin resistance, aggravate antioxidant status in diabetic rats and may be used as an adjuvant therapy for patients with insulin resistance.

The anti-arthritic and anti-oxidative effect of NBD (6-nitro-1,3-benzodioxane) in adjuvant-induced arthritis (AIA) in rats

OBJECTIVES

The present study evaluated the anti-arthritic and anti-oxidative effects of 6-nitro-1,3-benzodioxane in the adjuvant-induced arthritis model in rats.

METHODS

Arthritis was induced in female rats by intradermal injection of MT37Ra. Arthritis was evaluated by arthritic score, body weight loss, paw volume measurement, and histological changes. The plantar test was used to evaluate the effect of NBD on hyperalgesia.

RESULTS

The hyperalgesia (p < 0.0001) and hind paw inflammation (p < 0.034) was significantly decreased with parallel increase in the body weight of the NBD-treated (25 mg/kg) group compared to arthritic control rats. The antioxidant activity analysis demonstrated that the treatment of NBD significantly suppressed the levels of nitric oxide (p < 0.001) and peroxide (p < 0.002) with a significant increase in the glutathione (p < 0.021) compared to the arthritic control group. Since the IL-1β and TNF-α are key pro-inflammatory cytokines in arthritis, we therefore measured their levels in the serum samples. In comparison to the arthritic control group, the NBD treatment significantly reduced the levels of IL-1β (p < 0.003) and TNF-α (p < 0.026).

CONCLUSION

Our results suggests that NBD is an anti-arthritic agent that not only reduces the severity of the disease process but also affects contributing factors of arthritic inflammation including free radicals and inflammatory cytokines production.

Monocytes/macrophages express chemokine receptor CCR9 in rheumatoid arthritis and CCL25 stimulates their differentiation

INTRODUCTION

Monocytes/macrophages accumulate in the rheumatoid (RA) synovium where they play a central role in inflammation and joint destruction. Identification of molecules involved in their accumulation and differentiation is important to inform therapeutic strategies. This study investigated the expression and function of chemokine receptor CCR9 in the peripheral blood (PB) and synovium of RA, non-RA patients and healthy volunteers.

METHODS

CCR9 expression on PB monocytes/macrophages was analysed by flow cytometry and in synovium by immunofluorescence. Chemokine receptor CCR9 mRNA expression was examined in RA and non-RA synovium, monocytes/macrophages from PB and synovial fluid (SF) of RA patients and PB of healthy donors using the reverse transcription polymerase chain reaction (RT-PCR). Monocyte differentiation and chemotaxis to chemokine ligand 25 (CCL25)/TECK were used to study CCR9 function.

RESULTS

CCR9 was expressed by PB monocytes/macrophages in RA and healthy donors, and increased in RA. In RA and non-RA synovia, CCR9 co-localised with cluster of differentiation 14+ (CD14+) and cluster of differentiation 68+ (CD68+) macrophages, and was more abundant in RA synovium. CCR9 mRNA was detected in the synovia of all RA patients and in some non-RA controls, and monocytes/macrophages from PB and SF of RA and healthy controls. CCL25 was detected in RA and non-RA synovia where it co-localised with CD14+ and CD68+ cells. Tumour necrosis factor alpha (TNFα) increased CCR9 expression on human acute monocytic leukemia cell line THP-1 monocytic cells. CCL25 induced a stronger monocyte differentiation in RA compared to healthy donors. CCL25 induced significant chemotaxis of PB monocytes but not consistently among individuals.

CONCLUSIONS

CCR9 expression by monocytes is increased in RA. CCL25 may be involved in the differentiation of monocytes to macrophages particularly in RA.

N-(2-hydroxy phenyl) acetamide inhibits inflammation-related cytokines and ROS in adjuvant-induced arthritic (AIA) rats

The present study was carried out to study the anti-arthritic and anti-inflammatory activity of N-(2-hydroxy phenyl) acetamide in adjuvant-induced arthritis in adult female Sprague Dawley rats. During experimental period, body weight and paw oedema volume were observed. At the end of each experiment, plasma and serum samples were collected and used for estimation of pro-inflammatory cytokines IL-1 beta and TNF-alpha and oxidative stress markers i.e., nitric oxide, peroxide and GSH. Our results suggested that, the reduction in body weight and increase in paw oedema volume were significantly retarded in the AIA rats receiving 5mg/kg and 10mg/kg doses of N-(2-hydroxy phenyl) acetamide as compared to diseased control animals. The serum levels of IL-1 beta and TNF-alpha were reduced as compared to those in the diseased control group. Treatment with N-(2-hydroxy phenyl) acetamide also altered oxidative stress markers in relation to its anti-inflammatory activity. Based on our results, it can be concluded that N-(2-hydroxy phenyl) acetamide possesses promising anti-arthritic property.

Angiogenesis in rheumatoid arthritis

Angiogenesis is the formation of new capillaries from pre-existing vessels. A number of soluble and cell-bound factors may stimulate neovascularization. The perpetuation of angiogenesis involving numerous soluble and cell surface-bound mediators has been associated with rheumatoid arthritis (RA). These angiogenic mediators, among others, include growth factors, primarily vascular endothelial growth factor (VEGF) and hypoxia-inducible factors (HIFs), as well as pro-inflammatory cytokines, various chemokines, matrix components, cell adhesion molecules, proteases and others. Among the several potential angiogenesis inhibitors, targeting of VEGF, HIF-1, angiogenic chemokines, tumor necrosis factor-alpha and the alpha(V)beta(3) integrin may attenuate the action of angiogenic mediators and thus synovial angiogenesis. In addition, some naturally produced or synthetic compounds including angiostatin, endostatin, paclitaxel, fumagillin analogues, 2-methoxyestradiol and thalidomide may be included in the management of RA.

Angiogenesis and its targeting in rheumatoid arthritis

Angiogenesis, the development of new capillaries, is involved in leukocyte ingress into the synovium during the development and progression of rheumatoid arthritis. Several soluble and cell surface-bound mediators including growth factors, cytokines, chemokines, proteolytic matrix-degrading enzymes, cell adhesion molecules and others may promote synovial neovascularization. On the other hand, endogenous angiostatic factors, such as angiostatin, endostatin, interleukin-4 (IL-4), IL-13, interferons and some angiostatic chemokines are also produced within the rheumatoid synovium, however, their effects are insufficient to control synovial angiogenesis and inflammation. Several specific and non-specific strategies have been developed to block the action of angiogenic mediators. The first line of angiostatic agents include vascular endothelial growth factor (VEGF), angiopoietin, alpha(V)beta(3) integrin antagonist, as well as non-specific angiogenesis inhibitors including traditional disease-modifying agents (DMARDs), anti-tumor necrosis factor biologics, angiostatin, endostatin, fumagillin analogues or thalidomide. Potentially any angiostatic compound could be introduced to studies using animal models of arthritis or even to human rheumatoid arthritis trials.

Mechanisms of Disease: angiogenesis in inflammatory diseases

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

Effects of a mixture of fatty acids from sugar cane (Saccharum officinarum L.) wax oil in two models of inflammation: zymosan-induced arthritis and mice tail test of psoriasis

A mixture of fatty acids obtained from sugar cane (Saccharum officinarum L.) wax oil (FAM), in which the main constituents are palmitic, oleic, linoleic, and linolenic acids, was evaluated in two models of inflammation: zymosan-induced arthritis and in the tail test for psoriasis, both on mice. In the first model, FAM significantly reduced zymozan-induced increase of beta glucuronidase (DE(50) 90+/-7 mg/kg). Histopathological studies showed inhibition in cellular infiltration and reduction of synovial hyperplasia and synovitis, whereas in the second test, histopathological and ultrastructural studies showed that topical application of FAM induced orthokeratosis with the presence of keratohyalin granules in the previously parakeratotic adult mouse tail, and without effects on epidermal thickness. The ED(50) of FAM in this model was 155+/-10 mg. The results of our studies showed that topical application of FAM exerts an important anti-inflammatory activity in both tests without evidence of irritant effects. The anti-inflamatory effects exerted by FAM may be due to its inhibitory effects on arachidonic acid metabolism. To our knowledge, this is the first report on the anti-inflammatory effect of sugar cane by-products in experimental models of arthritis and psoriasis.

Macrophages and their products in rheumatoid arthritis

PURPOSE OF REVIEW

Macrophages differentiate from peripheral-blood monocytes. Both monocytes and synovial macrophages are key players in rheumatoid arthritis. These cells are involved in the initiation and perpetuation of inflammation, leukocyte adhesion and migration, matrix degradation and angiogenesis. Macrophages express adhesion molecules, chemokine receptors and other surface antigens. They also secrete a number of chemokines, cytokines, growth factors, proteases and other mediators.

RECENT FINDINGS

Macrophage migration-inhibitory factor has drawn significant attention recently. This cytokine is involved in macrophage activation and cytokine production. Migration-inhibitory factor also regulates glucocorticoid sensitivity and may be a pathogenic link between rheumatoid arthritis and atherosclerosis. Novel macrophage-derived chemokines and chemokine receptors have been identified. Interleukin-10 may have several proinflammatory effects that may influence its action in rheumatoid arthritis. Several proteinases including cathepsin G are produced by macrophages during rheumatoid arthritis-associated inflammatory and angiogenic events. Antirheumatic drugs, imatinib, chemokine receptor inhibitors and other specific strategies may become included in the therapy of rheumatoid arthritis.

SUMMARY

Macrophages and their products are key players in the pathogenesis of rheumatoid arthritis and may be good therapeutic targets.

Accelerated Atherosclerosis in Rheumatoid Arthritis

Cardiovascular disease is a leading cause of mortality in rheumatoid arthritis (RA). Endothelial dysfunction often precedes manifest atherosclerosis. Both traditional, Framingham risk factors and inflammation-associated factors are involved in RA-associated atherosclerosis. Among imaging techniques, the early determination of common carotid intima-media thickness (ccIMT), flow-mediated vasodilation (FMD), and nitroglycerine-mediated vasodilation (NMD) may be useful to determine atherosclerosis and endothelial dysfunction. We and others found increased ccIMT and impaired FMD in RA patients. Among immunological and metabolic laboratory markers, anticyclic citrullinated peptide (anti-CCP) antibodies, IgM rheumatoid factor, circulating immune complexes, pro-inflammatory cytokines including tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6), Th0/Th1 T cells, homocysteine, dyslipidemia, decreased folate and vitamin B12 production, and impaired paraoxonase activity may all be involved in the development of vascular disease in RA. The early diagnosis of endothelial dysfunction and atherosclerosis, active immunosuppressive treatment, the use of drugs that control atherosclerosis, changes in sedentary lifestyle, and the close follow-up of RA patients may help to minimize cardiovascular risk in these individuals.

Suppression of the onset and progression of collagen-induced arthritis in rats by QFGJS, a preparation from an anti-arthritic Chinese herbal formula

QFGJS is an herbal preparation, and its pronounced effectiveness in treating adjuvant-induced arthritis (AIA) has been previously demonstrated. We herein aimed to confirm its anti-arthritic effect on collagen-induced arthritis (CIA) in rats. CIA was established in female Wistar rats with intradermal injection of type II bovine collagen at the base of the tail of animals. CIA rats were treated daily with oral administration of different doses of QFGJS beginning on the day of the induction of arthritis (day 0, the prophylactic treatment) or on the day after the onset of arthritis (day 13, the therapeutic treatment) until day 30. The results showed that prophylactic treatment with QFGJS significantly suppressed the onset of arthritis, and therapeutic treatment with QFGJS markedly reduced paw swelling and ESR levels even in the established CIA. Radiologic and histopathologic changes in the arthritic joints were also significantly reduced in the QFGJS-treated versus vehicle-treated rats. Moreover, the serum levels of pro-inflammatory cytokines TNF-alpha, IL-1beta, and IL-6 were markedly lowered in the QFGJS-treated rats. Hence, our studies demonstrate the quality, safety, and effectiveness of QFGJS as an anti-arthritic agent, which makes QFGJS a strong candidate for further clinical trials on rheumatoid arthritis (RA) patients.

The comparative study of Sprague-Dawley and Lewis rats in adjuvant-induced arthritis

The outbred Sprague-Dawley (SD) rats, similar to the inbred Lewis (LEW) rats, have been recently demonstrated to be highly susceptible to adjuvant-induced arthritis (AIA). We herein compared AIA in SD and LEW rats in terms of clinical, histological, radiological, and immuno-inflammatory features. The results showed that, following inoculation with a ground Mycobacterium tuberculosis (MT) suspension, SD and LEW rats manifested closely similar disease progression, with 100% incidence and similar severity. The development of arthritis was accompanied by significantly higher erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels than in control rats. Radiographic examination of the hind paws showed that both SD and LEW AIA rats manifested conspicuous soft tissue swelling, bone matrix resorption, periosteal new bone formation and bone erosion, while histopathological analysis of the synovial joints revealed marked cellular infiltration, angiogenesis, synovial hyperplasia, pannus formation, narrowing of joint space, and cartilage and bone destruction. Moreover, in relation to disease progression, serum tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and IL-6 levels were markedly overexpressed in both SD and LEW AIA versus control rats, and SD and LEW AIA rats exhibited divergent profiles for the expression of TNF-alpha and IL-1beta. Taken together, these results demonstrated that the SD rat AIA model shares several arthritic features with the comparable model in LEW rats. Hence, given the more favorable characteristics of SD rats than LEW rats (i.e., lower cost, wider availability, and heterogenic background), this SD rat AIA model is more cost effective and advantageous for screening and testing novel anti-arthritic agents.

CXCL16-mediated cell recruitment to rheumatoid arthritis synovial tissue and murine lymph nodes is dependent upon the MAPK pathway

OBJECTIVE

Rheumatoid arthritis (RA) is characterized by profound mononuclear cell (MNC) recruitment into synovial tissue (ST), thought to be due in part to tumor necrosis factor alpha (TNFalpha), a therapeutic target for RA. Although chemokines may also be involved, the mechanisms remain unclear. We undertook this study to examine the participation of CXCL16, a novel chemokine, in recruitment of MNCs to RA ST in vivo and to determine the signal transduction pathways mediating this process.

METHODS

Using a human RA ST-SCID mouse chimera, immunohistochemistry, enzyme-linked immunosorbent assay, real-time reverse transcription-polymerase chain reaction, flow cytometry, and in vitro chemotaxis assays, we defined the expression and function of CXCL16 and its receptor, CXCR6, as well as the signal transduction pathways utilized by them for MNC homing in vitro and in vivo.

RESULTS

CXCL16 was markedly elevated in RA synovial fluid (SF) samples, being as high as 145 ng/ml. Intense macrophage and lining cell staining for CXCL16 in RA ST correlated with increased CXCL16 messenger RNA levels in RA ST compared with those in osteoarthritis and normal ST. By fluorescence-activated cell sorting analysis, one-half of RA SF monocytes and one-third of memory lymphocytes expressed CXCR6. In vivo recruitment of human MNCs to RA ST implanted in SCID mice occurred in response to intragraft injection of human CXCL16, a response similar to that induced by TNFalpha. Lipofection of MNCs with antisense oligodeoxynucleotides for ERK-1/2 resulted in a 50% decline in recruitment to engrafted RA ST and a 5-fold decline in recruitment to regional lymph nodes. Interestingly, RA ST fibroblasts did not produce CXCL16 in response to TNFalpha in vitro, suggesting that CXCL16 protein may function in large part independently of TNFalpha.

CONCLUSION

Taken together, these results point to a unique role for CXCL16 as a premier MNC recruiter in RA and suggest additional therapeutic possibilities, targeting CXCL16, its receptor, or its signaling pathways.

Suppressive effects of QFGJS, a preparation from an anti-arthritic herbal formula, on rat experimental adjuvant-induced arthritis

To analyze the anti-arthritic effects of QFGJS (a pharmaceutical preparation from herbs) on rheumatoid arthritis, adjuvant-induced arthritis (AIA) was established in male SD rats, and two administration protocols, i.e., oral treatment with different doses of QFGJS on the day of arthritis induction or on the day when visible clinical signs of arthritis occurred, were initiated and continued until day 30. Treatments with QFGJS using both administration protocols significantly suppressed the incidence and severity of arthritis in a dose-dependent manner, showing dramatic reduction of paw swelling and ESR throughout the disease progression of AIA. Radiological and histopathological examinations showed markedly decreased tissue and bone destruction of ankle joints in the QFGJS-treated rats. The serum levels of TNF-alpha, IL-1beta, and IL-6 were significantly decreased in the QFGJS-treated rats. QFGJS demonstrates pronounced anti-arthritic effects on AIA, indicating that this herbal preparation would be a potent candidate as a novel botanical drug for further investigation.

Induction of a CXCL8 binding site on endothelial syndecan-3 in rheumatoid synovium

OBJECTIVE

To identify and characterize which endothelial heparan sulfate proteoglycans (HSPGs) bind the chemokine CXCL8 (interleukin-8) in human rheumatoid arthritis (RA) and nonrheumatoid synovia.

METHOD

CXCL8 binding to endothelial HSPGs in RA and nonrheumatoid synovia was determined by heparinase treatment followed by an in situ binding assay and autoradiography. Endothelial HSPGs were characterized by immunohistochemical analysis and quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). Phosphatidyinositol-specific phospholipase C (PI-PLC) and antibodies to HSPGs were used in in situ binding experiments to identify which HSPGs bound CXCL8.

RESULTS

The expression of heparan sulfate on microvascular endothelial cells was demonstrated in RA and nonrheumatoid synovia. Using antibodies to syndecan-1-4 and glypican-1, -3, and -4, the selective expression of syndecan-3 by endothelial cells was detected in RA and nonrheumatoid synovia. In addition, RT-PCR showed the presence of syndecan-3 messenger RNA in endothelial cells extracted from RA and nonrheumatoid synovia. (125)I-CXCL8 bound to venular endothelial cells; treatment with heparinases I and III significantly reduced this binding in RA but not nonrheumatoid synovia. (125)I-CXCL8 binding was not reduced after treatment with PI-PLC, which cleaves glycosyl phosphatidylinositol linkages, suggesting that CXCL8 did not bind to glypicans. Treatment of synovia with a syndecan-3 antibody reduced CXCL8 binding to RA but not nonrheumatoid endothelial cells; however, no reduction in binding was observed with syndecan-2 or glypican-4 antibodies.

CONCLUSION

Our results show the selective induction of a CXCL8 binding site on endothelial syndecan-3 in RA synovium. This site may be involved in leukocyte trafficking into RA synovial tissue.

Inhibition of MAP kinases by crude extract and pure compound isolated from Commiphora mukul leads to down regulation of TNF-alpha, IL-1beta and IL-2

The anti-inflammatory effect of the medicinal plant, Commiphora mukul gum was studied in peripheral blood mononuclear cells (PBMC). Bioassay-guided fractionation using conventional solvent extraction procedures, subsequent column fractionation, followed by monitoring specific activity in PBMC led to the isolation of a lead compound. Both crude ethyl acetate extract and the lead compound, thus isolated, showed inhibitory effect on proliferative response of PBMC in mitogenic lymphocyte proliferation and MLR assays. Further studies on inflammatory mediators such as IFN-gamma, IL-12, TNF-alpha, IL-1beta and NO showed down regulation, whereas no inhibition was observed in the case of anti-inflammatory cytokine IL-10. Immunoblot analysis revealed the inhibitory effect of crude ethyl acetate extract on phosphorylation of all the three mitogen activated protein kinases (MAPK) such as ERK, JNK and p38 MAPK. In contrast treatment with pure compound showed no inhibitory effect on ERK. c-fos and c-jun mRNA levels were also reduced in PMA stimulated cells on treatment with crude extract and pure compound. This reduction in c-fos and c-jun levels, when taken together with inhibition of MAPK activation, provides a possible mechanism by which both crude ethyl acetate extract and purified compound isolated from C. mukul exert its action.

The inhibitory effect of disease-modifying anti-rheumatic drugs and steroids on gliostatin/platelet-derived endothelial cell growth factor production in human fibroblast-like synoviocytes

Gliostatin/platelet-derived endothelial cell growth factor (GLS/PD-ECGF) is known to have both angiogenic and arthritogenic activities. The purpose of this study was to investigate whether disease-modifying anti-rheumatic drugs (DMARDs) and steroids are involved in the regulation of GLS expression. Fibroblast-like synoviocytes (FLSs) obtained from patients with rheumatoid arthritis (RA) were cultured and stimulated by interleukin (IL)-1beta with or without DMARDs and steroids. The expression levels of GLS were determined using the reverse transcription-polymerase chain reaction and an ELISA. In cultured rheumatoid FLSs, the expression of GLS mRNA was significantly increased by stimulation with IL-1beta. By contrast, GLS mRNA levels in IL-1beta-stimulated FLSs were reduced by treatment with aurothioglucose (AuTG) and dexamethasone (DEX). These findings indicate that AuTG and DEX have anti-rheumatic activity, which is mediated via the suppression of GLS production. Neither methotrexate (MTX) nor sulfasalazine (SSZ) had a significant influence on GLS levels in our study.

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.

Endothelial cell phenotypes in the rheumatoid synovium: activated, angiogenic, apoptotic and leaky

Endothelial cells are active participants in chronic inflammatory diseases. These cells undergo phenotypic changes that can be characterised as activated, angiogenic, apoptotic and leaky. In the present review, these phenotypes are described in the context of human rheumatoid arthritis as the disease example. Endothelial cells become activated in rheumatoid arthritis pathophysiology, expressing adhesion molecules and presenting chemokines, leading to leukocyte migration from the blood into the tissue. Endothelial cell permeability increases, leading to oedema formation and swelling of the joints. These cells proliferate as part of the angiogenic response and there is also a net increase in the turnover of endothelial cells since the number of apoptotic endothelial cells increases. The endothelium expresses various cytokines, cytokine receptors and proteases that are involved in angiogenesis, proliferation and tissue degradation. Associated with these mechanisms is a change in the spectrum of genes expressed, some of which are relatively endothelial specific and others are widely expressed by other cells in the synovium. Better knowledge of molecular and functional changes occurring in endothelial cells during chronic inflammation may lead to the development of endothelium-targeted therapies for rheumatoid arthritis and other chronic inflammatory diseases.

Role of macrophage inflammatory protein-3alpha and its ligand CCR6 in rheumatoid arthritis

We examined the expression and participation of CCR6 and its ligand MIP-3alpha in rheumatoid arthritis (RA) by ELISA, RT-PCR, real-time PCR (TaqMan) analysis, monocyte chemotaxis, and two- and four-color flow cytometry. We found that RA synovial fluid (SF) contained significantly more MIP-3alpha than osteoarthritis (OA), indicating a potential role for MIP-3alpha in RA. IL-1beta, IL-18, and TNF-alpha stimulated RA fibroblast MIP-3alpha production at 48 hours of incubation in vitro. By TaqMan analysis, there were more CCR6 mRNA transcripts in RA synovial tissue (ST) than in OA or normal (NL) ST, and elevated MIP-3alpha mRNA expression in RA compared with NL ST. By FACS analysis, there were significantly elevated percentages of CD3+/CD4+/CD45RO+/CCR6+ memory lymphocytes found in RA peripheral blood (PB) compared with NL PB or RA SF. We also found that MIP-3alpha induced monocyte chemotactic activity at 1.25 pM, consistent with concentrations of MIP-3alpha found in RA SF. Furthermore, MIP-3alpha accounted for 40% of RA SF chemotactic activity for monocytes in modified Boyden chamber assays. We confirmed that MIP-3alpha may be binding a G-coupled protein receptor because in vitro monocyte chemotaxis was inhibited by preincubation of monocytes with pertussis toxin. RA patient clinical data revealed that CD3+ lymphocyte/CCR6 expression inversely correlated with the age of the patient, indicating that CCR6 expression may be important in the development of RA at a younger age. Overall, these studies indicate that MIP-3alpha and CCR6 may function to recruit monocytes and memory lymphocytes from the RA PB to the RA joint. These results further indicate that expression of CCR6, the receptor for MIP-3alpha, can be correlated with RA development.

Autoantibodies against interleukin 1alpha in rheumatoid arthritis: association with long term radiographic outcome

OBJECTIVES

To investigate the possible association of interleukin 1alpha autoantibodies (IL1alpha aAb) with the long term course of joint erosion in patients with rheumatoid arthritis (RA).

METHODS

Serum samples from 176 patients with RA included in a prospective study over 30 years were analysed for IL1alpha aAb by binding to human [(125)I]IL1alpha. Erosions of 19 diarthrodial joints were radiographically scored by the Larsen method.

RESULTS

The relative risk (RR) of early IL1alpha aAb positive patients developing at least 30% of maximum radiographic joint destruction was significantly lower than for IL1alpha aAb negative patients, RR=0.29 (p=0.04). In rheumatoid factor positive patients RR was only 0.18 (p=0.02). Patients who seroconverted more than two years after the onset of RA showed the most aggressive development of joint erosion, with a relative risk of at least 40% of maximum radiographic joint destruction of 2.56 (p=0.048)

CONCLUSIONS

The progression of radiographic joint destruction in patients with RA is associated with, and perhaps modified by, circulating IL1alpha aAb, suggesting that IL1alpha or IL1alpha aAb, or both, have a role in the erosive processes. IL1alpha aAb appear to be of prognostic significance in RA.

Gene expression profile analysis of rheumatoid synovial fibroblast cultures revealing the overexpression of genes responsible for tumor-like growth of rheumatoid synovium

To elucidate the aberrant growth properties of rheumatoid synoviocytes, we have examined the gene expression profile of rheumatoid synovial fibroblasts (RSFs) and compared with that of normal synovial fibroblasts (NSF). Gene expression profile analysis was conducted with synoviocyte cultures obtained from five rheumatoid arthritis (RA) patients and five control cases using a commercial cDNA array containing the defined 588 cancer-related genes. The results were confirmed by real-time RT-PCR. Gene expression levels for the platelet-derived growth factor receptor alpha (PDGFRalpha), plasminogen activator inhibitor-1 (PAI-1), and stromal cell derived factor 1A (SDF1A) are constitutively augmented in RSF compared with NSF. The mRNA levels of PDGFRalpha, PAI-1, and SDF1A in RSF over NSF were 4.6-, 14-, and 2.8-fold, respectively, by real-time RT-PCR. In fact, we found that RSFs showed greater sensitivity to the cell proliferative effect of PDGF. T his aberrant gene expression profile suggests that RSF may have retained the premature phenotype of primordial synoviocytes.

Successful treatment of rheumatoid arthritis is associated with a reduction in synovial membrane cytokines and cell adhesion molecule expression

OBJECTIVE

To investigate the change in synovial membrane cytokine content and cell adhesion molecule expression in sequential biopsies from the same knee joint of patients with rheumatoid arthritis, before and following anti-rheumatic drug treatment and to assess the relationship of these changes with clinical responses to the drug treatment.

METHODS

A selected group of patients with rheumatoid arthritis, some of whom had achieved a disease remission based on American College of Rheumatology (ACR) criteria, were included in this study. Sequential synovial biopsies obtained before and throughout the treatment period were studied by immunohistochemical labelling techniques for the cellular content, production of a range of pro- and anti-inflammatory cytokines and the expression of cell adhesion molecules. The staining was quantitated using computer-assisted digital image analysis.

RESULTS

There was a decrease in tumour necrosis factor-alpha (TNFalpha) and interleukin-1beta (IL-1beta) production in the synovial membrane lining and sublining of all patients who responded to treatment. The changes in IL-1 receptor antagonist production were variable. Paradoxically, there was a trend to decreased synovial membrane production of the anti-inflammatory cytokines, IL-10 and transforming growth factor-beta (TGFbeta), while IL-4 was not detectable in any of the synovial membrane biopsies. A significant reduction in the density and total amount of E-selectin expression in the synovial membrane was seen. Similarly, intercellular adhesion molecule-1 (ICAM-1) expression in the lining and sublining was decreased in those patients who had a significant clinical response to drug treatment or attained disease remission. There were no consistent or significant changes seen in the expression of other cell adhesion molecules in the synovial membranes of these patients.

CONCLUSIONS

Successful drug treatment of rheumatoid arthritis patients is characterized at the synovial membrane level by a decrease in TNFalpha, IL-10 and TGFbeta production. Some (E-selectin and ICAM-1) but not all (P-selectin, VCAM-1, PECAM-1) cell adhesion molecules are modulated in patients who respond clinically to drug treatment. E-selectin and ICAM-1 may be important targets for the development of future drug treatments for rheumatoid arthritis.

Therapeutic relevance of altered cytokine expression

Cytokines and their receptors have numerous physiological functions. Altered concentrations of these mediators are associated with various afflictions. For example, over-expression of cytokines has been associated with altered drug concentrations and activity. Greater concentrations of cardiovascular drugs have been observed in humans and laboratory animals with various types of inflammatory disorders compared to healthy controls. Interestingly, the observed higher concentrations of drugs such as propranolol and verapamil have not been associated with increased effects. Indeed, reduced response to these cardiovascular drugs is observed, suggestive of cytokine-mediated downregulation of receptors. Increased cytokine concentrations have also been associated with decreased response to drugs used in treatment of other disorders such as AIDS, asthma and psychiatric diseases. This reduced response to drug in the presence of altered cytokine concentrations is especially relevant to the elderly population which has a greater incidence of multiple diseases and elevated concentrations of various cytokines compared to younger individuals. Furthermore, inflammatory conditions and their accompanied increased over-expression of cytokines are suggested to be the main determinants of therapeutic failure in myocardial infarction and angina. Therefore, altered cytokine concentrations may influence therapeutic outcomes of pharmacotherapy and result in treatment failure.

Update on synovitis

Rheumatoid arthritis (RA) is an inflammatory disorder associated with chronic synovitis, eventually leading to cartilage and bone destruction in the joints. Synovitis is associated with the activation of various cells in the synovium including synovial lining cells, interstitial macrophages, endothelial cells, lymphocytes, and fibroblasts. The key mechanisms underlying synovitis include inflammatory cell adhesion and activation, the production of mediators (such as cytokines, chemokines, and growth factors), angiogenesis, joint destruction, fibrosis, and bone resorption. These important events, as well as the role of inflammatory cells, cell surface molecules, and soluble mediators are updated and discussed in this review. Some aspects and strategies of current or future immunotherapy are also discussed because these animal and human trials provide information on the pathogenesis of inflammatory synovitis.

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.

Required and nonessential functions of nuclear factor-kappa B in bone cells

Nuclear factor-kappa B (NF-kappaB) is a set of five polypeptide transcription factors, called p50, p52, p65 (also called Rel A), Rel B, and c-Rel, which regulate the expression of a variety of genes involved in immune and inflammatory responses. They were originally named because they were considered essential regulators of B cell kappa light chain expression. More recent studies indicate that NF-kappaB proteins are involved in the regulation of a variety of other cell functions, including cell proliferation, responses to stress, and apoptosis. NF-kappaB heterodimers reside in the cytoplasm of cells bound to inhibitory proteins, the two commonest of which are IkappaBalpha and IkappaBbeta, which prevent NF-kappaB from entering the nucleus. When cells are stimulated, IkappaB is phosphorylated by specific IkappaB kinases and subsequently is ubiquitinated and degraded in proteosomes. This allows NF-kappaB to translocate to the nucleus to regulate the expression of a growing list of genes, including the proinflammatory cytokines, interleukin-1 (IL-1), IL-6, and tumor necrosis factor. IL-1 and tumor necrosis factor in turn also regulate the expression of NF-kappaB. Thus, once activated, NF-kappaB may be involved in upregulatory loops, which can amplify the effects of the initiating stimulus. Because these proinflammatory cytokines have been implicated in the pathogenesis of estrogen deficiency and inflammation-related bone loss, it is likely that NF-kappaB has a significant role in the increased generation and function of osteoclasts in these circumstances. However, an unexpected and essential role of NF-kappaB in the formation of osteoclasts during development was discovered recently after the generation of knockout mice, which lack the expression of the p50 and p52 subunits. This paper will describe recent studies that reveal an essential role for NF-kappaB signaling in the generation of osteoclasts and that suggest that NF-kappaB may also play a key central role in the activation and survival of osteoclasts in conditions in which osteoclastogenesis is upregulated.