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

Systematic Review: Targeted Molecular Imaging of Angiogenesis and Its Mediators in Rheumatoid Arthritis

Extensive angiogenesis is a characteristic feature in the synovial tissue of rheumatoid arthritis (RA) from a very early stage of the disease onward and constitutes a crucial event for the development of the proliferative synovium. This process is markedly intensified in patients with prolonged disease duration, high disease activity, disease severity, and significant inflammatory cell infiltration. Angiogenesis is therefore an interesting target for the development of new therapeutic approaches as well as disease monitoring strategies in RA. To this end, nuclear imaging modalities represent valuable non-invasive tools that can selectively target molecular markers of angiogenesis and accurately and quantitatively track molecular changes in multiple joints simultaneously. This systematic review summarizes the imaging markers used for single photon emission computed tomography (SPECT) and/or positron emission tomography (PET) approaches, targeting pathways and mediators involved in synovial neo-angiogenesis in RA.

The Relationship Between Serum Angiogenic Factor Levels and Disease Activity in Rheumatoid Arthritis

Objectives

This study aims to evaluate the relationship between serum angiogenic factor levels and disease activity in patients with rheumatoid arthritis (RA) using both clinical and dynamic wrist magnetic resonance imaging (MRI) data.

Patients and methods

Simultaneous serum angiogenesis markers [vascular endothelial growth factor (VEGF), angiopoietin-1 (ANG1), ANG2, and tyrosine-protein kinase receptor for angiopoietin (Tie-2)] were studied in 40 patients with RA (13 males, 27 females; mean age 51.1±10.8 years; range, 23 to 69 years) and 20 healthy controls (11 males, 9 females; mean age 47.3±12.8 years; range, 29 to 69 years) and dynamic contrast-enhanced wrist MRI was performed in 40 RA patients and seven controls. Rate of early in 55th second (REE) and Relative enhancement (REt) values were calculated from the signal time curve values obtained from the analysis of images. In clinical assessment, duration of morning stiffness, patient pain assessment [visual analog scale (VAS)], physician and patient global assessments (VAS) were recorded. The number of tender joints and swollen joints were determined. Disease activity score 28 and Ritchie scores were calculated. Health assessment questionnaire was used for functional evaluation. Anti-cyclic citrullinated peptide, rheumatoid factor, erythrocyte sedimentation rate and high sensitive C-reactive protein analyses were performed.

Results

Serum VEGF, REE and REt values were significantly higher in RA patients than healthy controls (p=0.002, p=0.00, p=0.00, respectively). There was no significant correlation between serum angiogenesis markers and clinical parameters or REE and REt (p>0.05). VEGF value correlated positively with disease duration (p=0.024).

Conclusion

Serum VEGF was higher in RA patients. While its level was associated with disease duration, no significant correlation was found with disease activity. As a diagnostic test, dynamic contrast-enhanced MRI was a valuable method for showing disease activity.

Kaempferol targeting on the fibroblast growth factor receptor 3-ribosomal S6 kinase 2 signaling axis prevents the development of rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic inflammatory disease that mainly affects the synovial joints. Although involvement of the fibroblast growth factor (FGF) signaling pathway has been suggested as an important modulator in RA development, no clear evidence has been provided. In this study, we found that synovial fluid basic FGF (bFGF) concentration was significantly higher in RA than in osteoarthritis (OA) patients. bFGF stimulates proliferation and migration of human fibroblast-like synoviocytes (FLSs) by activation of the bFGF-FGF receptor 3 (FGFR3)-ribosomal S6 kinase 2 (RSK2) signaling axis. Moreover, a molecular docking study revealed that kaempferol inhibited FGFR3 activity by binding to the active pocket of the FGFR3 kinase domain. Kaempferol forms hydrogen bonds with the FGFR3 backbone oxygen of Glu555 and Ala558 and the side chain of Lys508. Notably, the inhibition of bFGF-FGFR3-RSK2 signaling by kaempferol suppresses the proliferation and migration of RA FLSs and the release of activated T-cell-mediated inflammatory cytokines, such as IL-17, IL-21, and TNF-α. We further found that activated phospho-FGFR3 and -RSK2 were more highly observed in RA than in OA synovium. The hyperplastic lining and sublining lymphoid aggregate layers of RA synovium showed p-RSK2-expressing CD68⁺ macrophages with high frequency, while pRSK2-expressing CD4⁺ T-cells was observed at a lower frequency. Notably, kaempferol administration in collagen-induced arthritis mice relieved the frequency and severity of arthritis. Kaempferol reduced osteoclast differentiation in vitro and in vivo relative to the controls and was associated with the inhibition of osteoclast markers, such as tartrate-resistant acid phosphatase, integrin β3, and MMP9. Conclusively, our data suggest that bFGF-induced FGFR3-RSK2 signaling may play a critical role during the initiation and progression of RA in terms of FLS proliferation and enhanced osteoclastogenesis, and that kaempferol may be effective as a new treatment for RA.

Analysis of Drug Effects on Primary Human Coronary Artery Endothelial Cells Activated by Serum Amyloid A

Background

RA patients have a higher incidence of cardiovascular diseases compared to the general population. Serum amyloid A (SAA) is an acute-phase protein, upregulated in sera of RA patients.

Aim

To determine the effects of medications on SAA-stimulated human coronary artery endothelial cells (HCAEC).

Methods

HCAEC were preincubated for 2 h with medications from sterile ampules (dexamethasone, methotrexate, certolizumab pegol, and etanercept), dissolved in medium (captopril) or DMSO (etoricoxib, rosiglitazone, meloxicam, fluvastatin, and diclofenac). Human recombinant apo-SAA was used to stimulate HCAEC at a final 1000 nM concentration for 24 hours. IL-6, IL-8, sVCAM-1, and PAI-1 were measured by ELISA. The number of viable cells was determined colorimetrically.

Results

SAA-stimulated levels of released IL-6, IL-8, and sVCAM-1 from HCAEC were significantly attenuated by methotrexate, fluvastatin, and etoricoxib. Both certolizumab pegol and etanercept significantly decreased PAI-1 by an average of 43%. Rosiglitazone significantly inhibited sVCAM-1 by 58%.

Conclusion

We observed marked influence of fluvastatin on lowering cytokine production in SAA-activated HCAEC. Methotrexate showed strong beneficial effects for lowering released Il-6, IL-8, and sVCAM-1. Interesting duality was observed for NSAIDs, with meloxicam exhibiting opposite-trend effects from diclofenac and etoricoxib. This represents unique insight into specific responsiveness of inflammatory-driven HCAEC relevant to atherosclerosis.

Monitoring Therapy Response of Experimental Arthritis with Radiolabeled Tracers Targeting Fibroblasts, Macrophages, or Integrin αvβ3

Rheumatoid arthritis is an autoimmune disease resulting in chronic synovial inflammation. Molecular imaging could be used to monitor therapy response, thus enabling tailored therapy regimens and enhancing therapeutic outcome. Here, we hypothesized that response to etanercept could be monitored by radionuclide imaging in arthritic mice. We tested 3 different targets, namely fibroblast activation protein (FAP), macrophages, and integrin αvβ3.

METHODS

Male DBA/1J mice with collagen-induced arthritis were treated with etanercept. SPECT/CT scans were acquired at 1, 24, and 48 h after injection of (111)In-RGD2 (integrin αvβ3), (111)In-anti-F4/80-A3-1 (antimurine macrophage antibody), or (111)In-28H1 (anti-FAP antibody), respectively, with nonspecific controls included. Mice were dissected after the last scan, and scans were analyzed quantitatively and were correlated with macroscopic scoring.

RESULTS

Experimental arthritis was imaged with (111)In-28H1 (anti-FAP), (111)In-anti-F4/80-A3-1, and (111)In-RGD2. Tracer uptake in joints correlated with arthritis score. Treatment decreased joint uptake of tracers from 23 ± 15, 8 ± 4, and 2 ± 1 percentage injected dose per gram (%ID/g) to 11 ± 11 (P < 0.001), 4 ± 4 (P < 0.001), and 1 ± 0.2 %ID/g (P < 0.01) for (111)In-28H1, (111)In-anti-F4/80-A3-1, and (111)In-RGD2, respectively. Arthritis-to-blood ratios (in mice with arthritis score 2 per joint) were higher for (111)In-28H1 (5.5 ± 1; excluding values > 25), (111)In-anti-F4/80-A3-1 (10.4 ± 4), and (111)In-RGD2 (7.2 ± 1) than for control (111)In-DP47GS (0.7 ± 0.5; P = 0.002), (111)In-rat IgG2b (0.5 ± 0.2; P = 0.002), or coinjection of excess RGD2 (3.5), indicating specific uptake of all tracers in arthritic joints.

CONCLUSION

(111)In-28H1, (111)In-anti-F4/80-A3-1, and (111)In-RGD2 can be used to specifically monitor the response to therapy in experimental arthritis at the molecular level. Further studies, however, still need to be performed.

Synovial tissue response to treatment in rheumatoid arthritis

The recognition of the synovial tissue, as the primary target of inflammation in RA, has driven research in this field, not only to clarify the disease pathogenesis but also to evaluate local changes in response to treatment. Special interest has been given to the identification of sensitive synovial biomarkers that could be of help in demonstrating proof of principle in early stages of drug development. Synovial sublining macrophages have been shown to correlate with scores for disease activity in cross-sectional studies. Moreover, decreased disease activity as measured by the disease activity score evaluated in 28 joints (DAS28) after effective treatment, has consistently been associated with a reduction of the number of CD68+ synovial sublining macrophages across different therapies. This observation highlights a possible final common pathway in the mechanism of action of various therapies and supports the notion that macrophages have a central role in RA pathogenesis.

When considering experimental therapies, the study of serial synovial biopsies in relatively small numbers of patients, in the context of proof of principle trials, successfully distinguished between effective and ineffective treatments. This attractive approach can be used during early drug development for screening proposes, supporting which new treatments have higher probability to be beneficial in a large scale clinical trial.

In this paper we review the effects of RA treatments on the synovial tissue, including targeted therapies, with particular attention to their effect on synovial biomarkers.

Endothelial FAK as a therapeutic target in disease

Focal adhesions (FA) are important mediators of endothelial cytoskeletal interactions with the extracellular matrix (ECM) via transmembrane receptors, integrins and integrin-associated intracellular proteins. This communication is essential for a variety of cell processes including EC barrier regulation and is mediated by the non-receptor protein tyrosine kinase, focal adhesion kinase (FAK). As FA mediate the basic response of EC to a variety of stimuli and FAK is essential to these responses, the idea of targeting EC FAK as a therapeutic strategy for an assortment of diseases is highly promising. In particular, inhibition of FAK could prove beneficial in a variety of cancers via effects on EC proliferation and angiogenesis, in acute lung injury (ALI) via the attenuation of lung vascular permeability, and in rheumatoid arthritis via reductions in synovial angiogenesis. In addition, there are potential therapeutic benefits of FAK inhibition in cardiovascular disease and diabetic nephropathy as well. Several drugs that target EC FAK are now in existence and include agents currently under investigation in preclinical models as well as drugs that are readily available such as the sphingolipid analog FTY720 and statins. As the role of EC FAK in the pathogenesis of a variety of diseases continues to be explored and new insights are revealed, drug targeting of FAK will continue to be an important area of investigation and may ultimately lead to highly novel and effective strategies to treat these diseases.

Characterization of golimumab, a human monoclonal antibody specific for human tumor necrosis factor α

We prepared and characterized golimumab (CNTO148), a human IgG1 tumor necrosis factor alpha (TNFα) antagonist monoclonal antibody chosen for clinical development based on its molecular properties. Golimumab was compared with infliximab, adalimumab and etanercept for affinity and in vitro TNFα neutralization. The affinity of golimumab for soluble human TNFα, as determined by surface plasmon resonance, was similar to that of etanercept (18 pM versus 11 pM), greater than that of infliximab (44 pM) and significantly greater than that of adalimumab (127 pM, p=0.018).  The concentration of golimumab necessary to neutralize TNFα-induced E-selectin expression on human endothelial cells by 50% was significantly less than those for infliximab (3.2 fold; p=0.017) and adalimumab (3.3-fold; p=0.008) and comparable to that for etanercept. The conformational stability of golimumab was greater than that of infliximab (primary melting temperature [Tm] 74.8 °C vs. 69.5 °C) as assessed by differential scanning calorimetry.  In addition, golimumab showed minimal aggregation over the intended shelf life when formulated as a high concentration liquid product (100 mg/mL) for subcutaneous administration.  In vivo, golimumab at doses of 1 and 10 mg/kg significantly delayed disease progression in a mouse model of human TNFα-induced arthritis when compared with untreated mice, while infliximab was effective only at 10 mg/kg. Golimumab also significantly reduced histological scores for arthritis severity and cartilage damage, as well as serum levels of pro-inflammatory cytokines and chemokines associated with arthritis. Thus, we have demonstrated that golimumab is a highly stable human monoclonal antibody with high affinity and capacity to neutralize human TNFα in vitro and in vivo.

Characterization of golimumab, a human monoclonal antibody specific for human tumor necrosis factor α

We prepared and characterized golimumab (CNTO148), a human IgG1 tumor necrosis factor alpha (TNFα) antagonist monoclonal antibody chosen for clinical development based on its molecular properties. Golimumab was compared with infliximab, adalimumab and etanercept for affinity and in vitro TNFα neutralization. The affinity of golimumab for soluble human TNFα, as determined by surface plasmon resonance, was similar to that of etanercept (18 pM versus 11 pM), greater than that of infliximab (44 pM) and significantly greater than that of adalimumab (127 pM, p=0.018).  The concentration of golimumab necessary to neutralize TNFα-induced E-selectin expression on human endothelial cells by 50% was significantly less than those for infliximab (3.2 fold; p=0.017) and adalimumab (3.3-fold; p=0.008) and comparable to that for etanercept. The conformational stability of golimumab was greater than that of infliximab (primary melting temperature [Tm] 74.8 °C vs. 69.5 °C) as assessed by differential scanning calorimetry.  In addition, golimumab showed minimal aggregation over the intended shelf life when formulated as a high concentration liquid product (100 mg/mL) for subcutaneous administration.  In vivo, golimumab at doses of 1 and 10 mg/kg significantly delayed disease progression in a mouse model of human TNFα-induced arthritis when compared with untreated mice, while infliximab was effective only at 10 mg/kg. Golimumab also significantly reduced histological scores for arthritis severity and cartilage damage, as well as serum levels of pro-inflammatory cytokines and chemokines associated with arthritis. Thus, we have demonstrated that golimumab is a highly stable human monoclonal antibody with high affinity and capacity to neutralize human TNFα in vitro and in vivo.

Angiogenesis in psoriatic skin and its modifications after administration of etanercept: videocapillaroscopic, histological and immunohistochemical evaluation

Several studies suggest that microangiopathy plays a crucial role in the pathogenesis of psoriasis. TNFalpha up-regulates the genetic transcription of VEGF, a pro-angiogenetic cytokine over-expressed in psoriatic skin, which promotes micrangiopathic modifications in psoriatic plaque. Etanercept is a chimeric protein used in the treatment of psoriasis and other immunomediated disorders, which blocks inflammatory response by interfering in the binding of TNF-alpha to its receptors. Starting from this data, we retain that etanercept can improve microangiopathy in psoriatic skin by reducing the synthesis of pro-angiogenetic chemokine VEGF. The aims of the study are: to verify the effect of etanercept on cutaneous en plaque capillaries in vivo using intra-vital videocapillaroscopy analysis, to evaluate the relation between the en plaque videocapillaroscopic pattern and the immunohistochemical cutaneous expression of VEGF in psoriasis, and finally to correlate all these in data with clinical disease activity. Eighteen patients (10 male and 8 female, mean age 51, range 21-60) suffering from stable, en plaque type psoriasis, involving at least 10 percent of body surface area (BSA), and not responsive to conventional therapy were included in the study. All the enrolled patients received etanercept 50mg/twice/week, subcutaneously, for 12 weeks, and were carefully followed up for clinical response with PASI score and DLQI index both before (T0) and after 12 weeks (T12) of treatment with etanercept. A well demarcated psoriatic plaque of the extensor surface of upper extremities was chosen to perform an intra-vital videocapillaroscopy analysis (IVCP), and a skin biopsy for immunohistochemical study both at T0 and T12 in all the included patients, in order to evaluate the presence of microangiopathy and its modification after therapy. All the patients experienced a clinical improvement of cutaneous disease with a significant decrease of PASI score (p<0.0001) and DLQI level (p<0.0001), throughout the twelve weeks of treatment. On IVCP analysis, microangiopathy dramatically decreased (p<0.0001), this modification being significantly related with PASI and DLQI decrease at T12. Immunohistochemical expression of VEGF decreased significantly from T0 to T12 (p<0.0001), and was related with a reduction of psoriatic microangiopathy at T12. The results of our videocapillaroscopic and immunohistochemical investigation confirm that the therapeutic potentiality of etanercept is based also on its capability to promote the regression of psoriatic microangiopathy. Moreover, according to these considerations, videocapillaroscopic evaluation of psoriatic plaque, both before and after treatment with etancercept, may be a useful tool to objectively demonstrate its effect on microcirculation.

Vascular Endothelial Growth Factor (VEGF) in Autoimmune Diseases

Vascular endothelial growth factor (VEGF) is a potent stimulating factor for angiogenesis and vascular permeability. There are eight isoforms with different and sometimes overlapping functions. The mechanisms of action are under investigation with emerging insights into overlapping pathways and cross-talk between other receptors such as the neuropilins, which were not previously associated to angiogenesis. VEGF has important physiological actions on embryonic development, healing, and menstrual cycle. It also has a great role in pathological conditions that are associated to autoimmune diseases. There is considerable evidence in various autoimmune diseases such as in systemic lupus erythematosus, rheumatoid arthritis, and multiple sclerosis of an interrelationship between the VEGF system and theses disorders. Serum levels of VEGF correlate with disease activity in a large number of autoimmune diseases and fall with the use of standard therapy. We raised the possible future therapeutic strategies in autoimmune diseases with the anti-VEGF or anti-VEGFR (receptor). So far, this therapy has been used in cancer and macular ocular degeneration in diabetes. This review outlines the evidence for VEGF participation in various autoimmune diseases and proposes lines for future research in this field.

Characterization and development of a peptide substrate-based phosphate transfer assay for the human vascular endothelial growth factor receptor-2 tyrosine kinase

Vascular endothelial growth factor (VEGF), a critical regulator in angiogenesis, exerts its angiogenic effect via binding to its receptor, VEGF receptor-2 tyrosine kinase (VEGFR2) or kinase insert domain-containing receptor (Kdr), on the surface of endothelial cells. Kdr-mediated signaling plays an important role in the proliferation, migration, differentiation, and survival of endothelial cells. Therefore, the inhibition of this signaling pathway represents a promising therapeutic approach for the discovery of novel anticancer agents by destabilizing the progression of solid tumors via abrogating tumor-induced angiogenesis. To explore Kdr as an anticancer target and further characterize the enzyme, we purified a cytoplasmic domain of human Kdr (Kdr-CD) and characterized its autophosphorylation activity. We also designed and synthesized peptides containing amino acid sequences corresponding to the autophosphorylation sites of Kdr and developed a simple, robust, high-throughput assay for measuring the phosphate transfer activity of the enzyme. This assay was validated by the experiments showing that the phosphate transfer activity of the purified Kdr-CD required Mg2+ or Mn2+ and preactivation by adenosine 5'-triphosphate (ATP) and was inhibited by known Kdr inhibitors. Using this assay, we examined effects of Mg2+ and Mn2+ on the enzyme activity; optimized the concentrations of Kdr-CD, peptide and ATP substrates, and metal ions in the assay; and determined the kinetic properties of the enzyme for the peptide and ATP as well as IC50 values of two known Kdr inhibitors. Thus, the results of these studies have validated the utilities of this assay for biochemical characterizations of the enzyme and its inhibitors. This approach of designing peptides corresponding to the autophosphorylation sites of Kdr as substrates for the enzyme has general practical implications to other kinases.

Transgenic delivery of VEGF to mouse skin leads to an inflammatory condition resembling human psoriasis

Gene therapy approaches involving vascular endothelial growth factor (VEGF) to promote therapeutic angiogenesis are under consideration for conditions ranging from ischemic heart disease to nonhealing skin ulcers. Here we make the surprising observation that the transgenic delivery of VEGF to the skin results in a profound inflammatory skin condition with many of the cellular and molecular features of psoriasis, including the characteristic vascular changes, epidermal alterations, and inflammatory infiltrates. Even longstanding psoriatic disease remains dependent on the transgenic VEGF in this model because it can be effectively reversed by the addition of VEGF Trap, a potent VEGF antagonist. Previous attempts to faithfully replicate the psoriatic phenotype through the transgenic delivery of epidermal keratinocyte growth factors or inflammatory mediators generated phenotypes with only partial resemblance to human psoriasis, leaving unanswered questions about the etiology of this disease. The ability of transgenic VEGF to induce a psoriasiform phenotype suggests a new etiology and treatment approach for this disease and further substantiates emerging concerns about possible proinflammatory adverse effects that might be associated with therapeutic attempts to deliver VEGF.

Treatment of severe recalcitrant plaque psoriasis with single-dose intravenous tumour necrosis factor-alpha antibody (infliximab)

Infliximab is a chimeric anti-tumour necrosis factor-alpha antibody that has been demonstrated to have marked efficacy in the treatment of psoriasis. Seven patients with chronic plaque psoriasis were treated with single-dose intravenous infliximab (5 mg/kg), and the Psoriasis Area and Severity Index (PASI) and Dermatology Life Questionnaire Index (DLQI) were used as a measure of treatment efficacy. There was an average improvement in PASI scores of 69% at 2 weeks post infusion. There was an improvement in DLQI of 61%. Four of the seven patients were also seen at 10 weeks post infusion and the improvement in PASI and DLQI was sustained. All patients tolerated the initial infusion well without adverse events. The results indicate that single-dose infliximab is an effective and efficacious therapy for recalcitrant psoriasis and has a prolonged therapeutic effect.

Inhibition of interleukin-1 but not tumor necrosis factor suppresses neovascularization in rat models of corneal angiogenesis and adjuvant arthritis

OBJECTIVE

To assess the capacities of the cytokine inhibitors interleukin-1 receptor antagonist (IL-1Ra; anakinra) and PEGylated soluble tumor necrosis factor receptor I (PEG sTNFRI; pegsunercept) to suppress neovascularization.

METHODS

A corneal angiogenesis assay was performed by implanting nylon discs impregnated with an angiogenic stimulator (basic fibroblast growth factor or vascular endothelial growth factor) into one cornea of female Sprague-Dawley rats. Animals were treated with IL-1Ra or PEG sTNFRI for 7 days, after which new vessels were quantified. In a parallel study, male Lewis rats with mycobacteria-induced adjuvant-induced arthritis were treated with IL-1Ra or PEG sTNFRI for 7 days beginning at disease onset, after which scores for inflammation and bone erosion as well as capillary counts were acquired from sections of arthritic hind paws.

RESULTS

Treatment with IL-1Ra yielded a dose-dependent reduction in growth factor-induced corneal angiogenesis, while PEG sTNFRI did not. IL-1Ra, but not PEG sTNFRI, significantly reduced the number of capillaries in arthritic paws, even though both anticytokines reduced inflammation and bone erosion to a similar degree.

CONCLUSION

These data support a major role for IL-1, but not TNFalpha, in angiogenesis and suggest that an additional antiarthritic mechanism afforded by IL-1 inhibitors, but not anti-TNF agents, is the suppression of the angiogenic component of pannus.

Infliximab: an updated review of its use in Crohn's disease and rheumatoid arthritis

Infliximab is a chimeric monoclonal antibody that binds to tumour necrosis factor-alpha (TNFalpha) and neutralises its effects. TNFalpha plays an important role in the development of both Crohn's disease and rheumatoid arthritis. In a large, double-blind, randomised study involving patients with active, refractory Crohn's disease, significantly more recipients of intravenous infliximab, compared with placebo, achieved a clinical response after 4 weeks' follow-up. Moreover, infliximab administration was associated with a rapid improvement in endoscopic and histological findings in clinical trials involving patients with active, refractory Crohn's disease. The results of the A Crohn's Disease Clinical Trial Evaluating Infliximab in a New Long-Term Treatment Regimen (ACCENT) I study showed that maintenance infliximab therapy prolonged response and remission in patients with moderate to severe Crohn's disease. In patients with enterocutaneous fistulae associated with Crohn's disease who were involved in a double-blind, randomised study, significantly more patients who received multiple infusions of infliximab, compared with placebo, experienced a > or=50% reduction from baseline in the number of draining fistulae at > or =2 consecutive study visits. In patients with active rheumatoid arthritis refractory to treatment with methotrexate who were enrolled in a large, double-blind, randomised study [the Anti-TNF Trial in Rheumatoid Arthritis with Concomitant Therapy (ATTRACT) study], American College of Rheumatology (ACR) 20, 50 and 70% response rates were seen in significantly more patients who received multiple infusions of infliximab plus methotrexate, compared with methotrexate plus placebo, after 30 and 54 weeks' treatment. Moreover, the ACR 20% response rate was maintained after 102 weeks' treatment. In addition, significantly less radiographic progression was seen in infliximab plus methotrexate, compared with methotrexate plus placebo, recipients after 54 weeks' treatment. Infliximab therapy was also associated with improvements in health-related quality of life in patients with Crohn's disease or rheumatoid arthritis. Infliximab was generally well tolerated in clinical trials with the most common adverse events including upper respiratory tract infection, headache, nausea, coughing, sinusitis and diarrhoea. Infliximab therapy may be associated with an increased risk of reactivation of tuberculosis in patients with latent disease. In conclusion, infliximab is an important treatment option in patients with active Crohn's disease who have not responded to conventional therapy and in patients with Crohn's disease who have fistulae. Moreover, infliximab plus methotrexate is effective in patients with active rheumatoid arthritis who have not responded adequately to traditional disease-modifying antirheumatic drugs, in terms of reducing symptoms and signs, improving physical function and delaying the progression of structural damage.

Rheumatoid arthritis: developing pharmacological therapies

Rheumatoid arthritis (RA) is a chronic inflammatory disease that, despite recent advances in therapy, still results in significant morbidity, mortality and disability. The aetiology remains unknown and past therapies, although helpful for the majority of patients, have been suboptimal. The recent introduction of newer agents has changed the treatment paradigm of RA. COX-2 inhibitors, anti-TNF agents and interleukin-1 antagonists have allowed us to treat RA more effectively with relatively low risk of side effects. Investigations of other possible treatment pathways, such as inhibition of angiogenesis, may produce still better treatment and rapid unraveling of the immune system and how it relates to RA greatly enhances the opportunities for improved therapeutics in RA.

Serum and synovial fluid concentration of vascular endothelial growth factor in juvenile idiopathic arthritides

OBJECTIVE

To evaluate the role of vascular endothelial growth factor (VEGF) in the pathogenesis of local joint inflammation in juvenile idiopathic arthritis (JIA).

METHODS

Sera from 50 patients affected with JIA and 10 age-matched healthy controls were tested with a commercial ELISA for VEGF. Corresponding synovial fluid (SF) concentrations of VEGF and p75 soluble tumour necrosis factor receptor (sTNFR) were evaluated in 20 active JIA patients.

RESULTS

Serum concentrations of VEGF were significantly higher in patients with active polyarticular disease than in patients with active and inactive oligoarticular disease and healthy controls. In JIA patients, serum concentrations of VEGF displayed a significant correlation with a number of clinical and laboratory parameters of disease activity. VEGF concentrations in SF were significantly higher than those detected in corresponding sera. Moreover, a clear correlation was found between corresponding SF and serum VEGF concentrations. In SF, VEGF showed a strong positive correlation with p75 sTNFR.

CONCLUSIONS

Concentrations of VEGF in SF in patients with JIA are higher than corresponding serum concentrations, suggesting that this pro-angiogenic factor may have a major role in the outgrowth of hyperplastic pannus and tissue damage at the site of tissue inflammation.

Fibroblast growth factor-2 determines severity of joint disease in adjuvant-induced arthritis in rats

Rheumatoid arthritis (RA), a systemic inflammatory disease of unknown etiology, mainly affects synovial joints. Although angiogenic growth factors, including fibroblast growth factor-2 (FGF-2) and vascular endothelial growth factor (VEGF), may play a critical role in the development and progression of RA joint disease, little information is now available regarding their exact role in initiation and/or progression of RA. In this study, we show that both polypeptides were up-regulated in the rat joint synovial tissue of an adjuvant-induced model of arthritis (AIA), as well as human subjects with RA. FGF-2 overexpression via Sendai virus-mediated gene transfer significantly worsened clinical symptoms and signs of rat AIA, including hind paw swelling and radiological bone destruction, as well as histological findings based on inflammatory reaction, synovial angiogenesis, pannus formation, and osteocartilaginous destruction, associated with up-regulation of endogenous VEGF. FGF-2 gene transfer to non-AIA joints was without effect. These findings suggested that FGF-2 modulated disease progression, but did not affect initiation. Reverse experiments using anti-FGF-2-neutralizing rabbit IgG attenuated clinical symptoms and histopathological abnormalities of AIA joints. To our knowledge, this is the first report indicating direct in vivo evidence of disease-modulatory effects of FGF-2 in AIA, as probably associated with endogenous VEGF function. FGF-2 may prove to be a possible therapeutic target to treat subjects with RA.

Combined genomic and antisense analysis reveals that the transcription factor Erg is implicated in endothelial cell differentiation

It has recently been shown that the transcription factor Erg, an Ets family member, drives constitutive expression of the intercellular adhesion molecule 2 (ICAM-2) in human umbilical vein endothelial cells (HUVECs) and that its expression is down-regulated by the pleiotropic cytokine tumor necrosis factor alpha (TNF-alpha). To identify other Erg target genes and to define its function in the endothelium, a combined approach of antisense oligonucleotides (GeneBloc) and differential gene expression was used. Treatment of HUVECs with Erg-specific GeneBloc for 24, 48, and 72 hours suppressed Erg mRNA and protein levels at all time points. Total RNA extracted from HUVECs treated with Erg-specific or control GeneBloc was analyzed for differences in gene expression using high-density, sequence-verified cDNA arrays containing 482 relevant genes. Inhibition of Erg expression resulted in decreased expression of ICAM-2, as predicted. Four more genes decreased in Erg-deficient HUVECs were the extracellular matrix proteins SPARC and thrombospondin, the adhesive glycoprotein von Willebrand factor, and the small GTPase RhoA. Each of these molecules has been directly or indirectly linked to angiogenesis because of its role in vascular remodeling, adhesion, or shape change. Therefore, the role of Erg in vascular remodeling was tested in an in vitro model, and the results showed that HUVECs treated with Erg GeneBloc had a decreased ability to form tubulelike structures when grown on Matrigel. These results suggest that Erg may be a mediator of the TNF-alpha effects on angiogenesis in vivo.

Immunohistochemical localization of vascular endothelial growth factor, transforming growth factor alpha, and transforming growth factor beta1 in human corneas with neovascularization

PURPOSE

To analyze presence and distribution of vascular endothelial growth factor (VEGF), transforming growth factor (TGF)alpha, and TGFbeta1 in human corneas with neovascularization due to different corneal diseases.

METHODS

Indirect immunohistochemistry for VEGF, TGFalpha, and TGFbeta1, was performed on paraffin-embedded corneas obtained by keratoplasty. Corneas from each of the four main groups of histopathologic diagnoses associated with corneal neovascularization were analyzed (scarring after keratitis, graft rejection/insufficiency, acute necrotizing keratitis, scarring after mechanical/chemical injury). Subclassification of inflammatory infiltrates was done using immunohistochemistry for CD3 (T-lymphocytes) and CD68 (macrophages).

RESULTS

The analyzed angiogenic factors were detectable in corneas from all four histopathologic groups in a similar distribution; capillary endothelial cells, stromal and intravascular inflammatory cells (T-lymphocytes, macrophages), and basal corneal epithelial cells stained positive for the tested angiogenic factors.

CONCLUSION

The angiogenic factors VEGF, TGFalpha, and TGFbeta1 are detectable in human corneas with neovascularization. Their distribution is quite uniform in different corneal diseases, resulting in corneal angiogenesis. An antiangiogenic therapy inhibiting corneal neovascularization by antagonizing angiogenic factors would have to counteract several angiogenic factors.

Review article: the clinical role of anti-TNFalpha antibody treatment in Crohn's disease

The recent licensing of anti-TNFalpha antibody treatment offers the potential to radically alter the course of severe Crohn's disease using genetically-engineered drugs directed against a specific inflammatory mediator. Controlled randomized trials have demonstrated clinical benefit associated with tissue healing in patients with active intestinal disease and fistulae, often when conventional therapies were unsuccessful. This therapy is expensive, however, and long-term efficacy and safety data are still awaited. This review considers the nature of this therapy and the current evidence for its clinical benefit and adverse effects. The treatment is also considered in the context of available immunosuppressive agents, with suggestions about its practical application.

Macrophages in rheumatoid arthritis

The abundance and activation of macrophages in the inflamed synovial membrane/pannus significantly correlates with the severity of rheumatoid arthritis (RA). Although unlikely to be the 'initiators' of RA (if not as antigen-presenting cells in early disease), macrophages possess widespread pro-inflammatory, destructive, and remodeling capabilities that can critically contribute to acute and chronic disease. Also, activation of the monocytic lineage is not locally restricted, but extends to systemic parts of the mononuclear phagocyte system. Thus, selective counteraction of macrophage activation remains an efficacious approach to diminish local and systemic inflammation, as well as to prevent irreversible joint damage.

Investigational treatments in rheumatoid arthritis

The active search for new treatment modalities of established rheumatoid arthritis have created a dynamic period for rheumatology. Both promising pharmaceutical products and targeted interventions with products of the biotechnology industry are being developed. Leflunomide and the selective blockade of the cytokine tumour necrosis factor (TNF) have recently been registered in several countries and others will follow. Like all new therapeutic strategies much remains to be learned about the optimal use of these therapies and their possible limitations. The success of these interventions have shown that a complex disease such as rheumatoid arthritis that is refractory to conventional treatment can be modulated by new therapeutic strategies. This experience has also resulted in further searches for new drugs that influence those pathogenetic pathways affected by the interventions found to be effective.

Etanercept: a review of its use in rheumatoid arthritis

Etanercept, a fusion protein consisting of the extracellular ligand-binding domain of the 75kD receptor for tumour necrosis factor-alpha and the constant portion of human IgG1, is administered by subcutaneous injection and is the first specific anti-cytokine therapy approved for rheumatoid arthritis. In patients with active rheumatoid arthritis [American College of Rheumatology (ACR) functional class I to III] who had failed to respond to previous treatment with > or = 1 disease-modifying antirheumatic drug (DMARD), etanercept, alone or in combination with methotrexate, produced improvements in all components included in the ACR core set of disease activity measures. A dose-response effect was apparent with etanercept 0.25 to 16 mg/m2 twice weekly in a randomised, double-blind study in 180 patients. The mean number of swollen or tender joints at the end of the 12-week study decreased by >50% in patients treated with etanercept 16 mg/m2 twice weekly and by <25% in patients treated with placebo. In a 24-week multicentre, randomised, double-blind study in 234 patients who were not allowed to use DMARDs, etanercept 10 or 25mg twice weekly had a rapid onset of effect. Significantly more patients treated with etanercept 25mg twice weekly than placebo experienced 20 (ACR 20), 50 (ACR 50) or 70% (ACR 70) improvement in ACR criteria after 3 and 6 months. Limited evidence suggests that the therapeutic effects of etanercept are maintained for up to 2 years. Etanercept 25mg twice weekly produced significant improvement in patients receiving oral or subcutaneous methotrexate 10 to 25 mg/week in a multicentre, randomised, double-blind, placebo-controlled study. A significantly greater proportion of patients treated with etanercept plus methotrexate (71%) than placebo plus methotrexate (27%) achieved the ACR 20 criteria after 6 months. Moreover, 39 and 15% of patients treated with etanercept plus methotrexate, but no placebo plus methotrexate recipients, had achieved the ACR 50 and ACR 70 criteria at this time. Etanercept 0.4 mg/kg twice weekly reduced disease activity in a preliminary, noncomparative study in 69 children aged > or =4 years with refractory juvenile rheumatoid arthritis. Although the overall frequency of infections was similar in patients treated with etanercept or placebo, upper respiratory tract infections were more common in patients treated with etanercept (29%) than placebo (16%). Injection site reactions occurred more frequently in etanercept- than placebo-treated patients, but did not bias the results of any study.

CONCLUSIONS

When etanercept is administered alone or in combination with methotrexate in patients with refractory rheumatoid arthritis, significant reductions in disease activity occur within 2 weeks and are sustained for at least 6 months. Thus, etanercept appears to be particularly well suited for use in patients who fail to respond to treatment with DMARDs.

A role for angiogenesis in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic debilitating disease characterized by distinct autoimmune, inflammatory and fibrovascular components which lead to synovial proliferation and joint destruction. However, existing treatments specifically target only autoimmune and inflammatory components despite the fact that neovascularization of the inflamed synovium is a hallmark of rheumatoid arthritis. Angiogenesis may contribute to synovial growth, leukocyte recruitment and tissue remodeling, thus potentiating disease progression. Although no therapies currently target angiogenesis, several existing therapies have anti-angiogenic activity. Recent advances in anti-angiogenic strategies in oncology, including the identification of integrin alpha v beta 3 as a crucial effector of angiogenesis, suggest a means to assess the role of angiogenesis in rheumatoid arthritis. Synovial endothelial cells have been shown to express integrin alpha v beta 3, suggesting that these cells may be targeted for angiogenesis inhibition. Prior studies in rat arthritis models have shown benefit after the addition of broad spectrum integrin antagonists. However, formal assessment of integrin-targeted anti-angiogenic activity is now underway. These controlled studies will be important in assessing the efficacy of therapies which target angiogenesis in RA.

Decreased angiogenesis and arthritic disease in rabbits treated with an alphavbeta3 antagonist

Rheumatoid arthritis (RA) is an inflammatory disease associated with intense angiogenesis and vascular expression of integrin alphavbeta3. Intra-articular administration of a cyclic peptide antagonist of integrin alphavbeta3 to rabbits with antigen-induced arthritis early in disease resulted in inhibition of synovial angiogenesis and reduced synovial cell infiltrate, pannus formation, and cartilage erosions. These effects were not associated with lymphopenia or impairment of leukocyte function. Furthermore, when administered in chronic, preexisting disease, the alphavbeta3 antagonist effectively diminished arthritis severity and was associated with a quantitative increase in apoptosis of the angiogenic blood vessels. Therefore, angiogenesis appears to be a central factor in the initiation and persistence of arthritic disease, and antagonists of integrin alphavbeta3 may represent a novel therapeutic strategy for RA.