Kinetics of Redox Reactions on Ti02 and NiO Single Crystals and Oxidized Metal Surfaces

Kinetics of Fe(CN) :· /Fe(CN) :- redox reaction couple on oxidized Ti, Ni and on Ti02 and NiO single crystals has been studied by fast methods of polarization and current measurements. From experimental values of the exchange-currents and transfer coefficients a and ~. and knowing the reaction mechanism, the potential distribution in the metal-oxide film - electrolyte system for Ti has been evaluated. It has been shown, that the main difference in properties of passive oxide films on Ni and Ti lies in the character of potential distribution at the oxide-solution interface

Kinetics of Redox Reactions on Ti02 and NiO Single Crystals and Oxidized Metal Surfaces

Kinetics of Fe(CN) :· /Fe(CN) :- redox reaction couple on oxidized Ti, Ni and on Ti02 and NiO single crystals has been studied by fast methods of polarization and current measurements. From experimental values of the exchange-currents and transfer coefficients a and ~. and knowing the reaction mechanism, the potential distribution in the metal-oxide film - electrolyte system for Ti has been evaluated. It has been shown, that the main difference in properties of passive oxide films on Ni and Ti lies in the character of potential distribution at the oxide-solution interface

The effect of tumour necrosis factor-α (TNF-α) muteins on human neutrophils in vitro

Tumour necrosis factor-α (TNF-α) has been implicated as an important inflammatory mediator. In vitro, TNF-α is reported to activate human polymorphonuclear neutrophils (PMN), inducing responses such as phagocytic activity, degranulation and oxidative metabolism. Biological responses to TNF-α are initiated by its binding to specific cell surface receptors, and various studies have shown that the major TNF receptor species on PMN is the 75 kDa receptor. To verify the suggestion that the receptor binding domain includes the region close to the N-terminus of the TNF-α molecule, four TNF-α derivatives termed muteins were constructed, using a synthetic cDNA fragment substituting the N-terminal 3–7 selected hydrophilic or hydrophobic amino acids in the original TNF-α genomic DNA. Binding of muteins to PMN was assessed using monoclonal antibodies recognizing either the 55 kDa (p55) or the 75 kDa (p75) TNF receptor subtypes. Blocking by muteins of anti-p75 antibody binding to PMN was as expected from their N-terminal amino acid composition and hydrophilic properties. Hydrophilic muteins competed well with anti-TNF receptor antibodies for binding to the p75 receptor. In contrast, hydrophobic muteins were unable to block anti-p75 binding. Similarly, degranulation, chemiluminescence or enhancement of the PMN response to specific stimuli by the muteins correlated with the hydrophilic properties of the muteins. The significance of these observations in relation to the molecular structure of TNF-α is discussed

The role of vascular cell adhesion molecule 1/ very late activation antigen 4 in endothelial progenitor cell recruitment to rheumatoid arthritis synovium

Objective Marrow-derived endothelial progenitor cells (EPCs) are important in the neovascularization that occurs in diverse conditions such as cardiovascular disorders, inflammatory diseases, and neoplasms. In rheumatoid arthritis (RA), synovial neovascularization propels disease by nourishing the inflamed and hyperproliferative synovium. This study was undertaken to investigate the hypothesis that EPCs selectively home to inflamed joint tissue and may perpetuate synovial neovascularization. Methods In a collagen-induced arthritis (CIA) model, neovascularization and EPC accumulation in mouse ankle synovium was measured. In an antibody-induced arthritis model, EPC recruitment to inflamed synovium was evaluated. In a chimeric SCID mouse/human synovial tissue (ST) model, mice were engrafted subcutaneously with human ST, and EPC homing to grafts was assessed 2 days later. EPC adhesion to RA fibroblasts and RA ST was evaluated in vitro. Results In mice with CIA, cells bearing EPC markers were significantly increased in peripheral blood and accumulated in inflamed synovial pannus. EPCs were 4-fold more numerous in inflamed synovium from mice with anti–type II collagen antibody–induced arthritis versus controls. In SCID mice, EPC homing to RA ST was 3-fold greater than to normal synovium. Antibody neutralization of vascular cell adhesion molecule 1 (VCAM-1) and its ligand component Α4 integrin potently inhibited EPC adhesion to RA fibroblasts and RA ST cryosections. Conclusion These data demonstrate the selective recruitment of EPCs to inflamed joint tissue. The VCAM-1/very late activation antigen 4 adhesive system critically mediates EPC adhesion to cultured RA fibroblasts and to RA ST cryosections. These findings provide evidence of a possible role of EPCs in the synovial neovascularization that is critical to RA pathogenesis.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/56042/1/22706_ftp.pd

Disease modifying and antiangiogenic activity of 2-Methoxyestradiol in a murine model of rheumatoid arthritis

<p>Abstract</p> <p>Background</p> <p>A critical component of disease progression in rheumatoid arthritis (RA) involves neovascularization associated with pannus formation. 2-methoxyestradiol (2ME2) is a naturally occurring molecule with no known physiologic function, although at pharmacologic concentrations it has antiproliferative and antiangiogenic activities. We investigated the impact of orally administered 2ME2 on the initiation and development of proliferative synovitis using the anti-collagen monoclonal antibodies (CAIA) model.</p> <p>Methods</p> <p>Severe polyarticular arthritis was induced in Balb/c female mice by administration of 2 mg of a monoclonal antibody cocktail intravenously into the tail vein of mice. Twenty-four hours following monoclonal antibody administration, mice were injected with 25 μg of LPS (<it>E. coli </it>strain 0111:B4) via the intraperitoneal route. Treatment with 2ME2 (100, 75, 50, 25, 10, 1 mg/kg, p.o., daily), or vehicle control began 24 hrs following LPS challenge and continued to day 21. Hind limbs were harvested, sectioned and evaluated for DMARD activity and general histopathology by histomorphometric analysis and immunohistochemistry (vWF staining). In a separate study, different dosing regimens of 2ME2 (100 mg/kg; q.d. <it>vs </it>q.w. <it>vs </it>q.w. × 2) were evaluated. The effect of treatment with 2ME2 on gene expression of inflammatory cytokines and angiogenic growth factors in the joint space was evaluated 5 and 14 days after the induction of arthritis.</p> <p>Results</p> <p>Mice treated with 2ME2 beginning 24 hours post anti-collagen monoclonal antibody injection, showed a dose-dependent inhibition in mean arthritic scores. At study termination (day 21), blinded histomorphometric assessments of sectioned hind limbs demonstrated decreases in synovial inflammation, articular cartilage degradation, pannus formation, osteoclast activity and bone resorption. At the maximal efficacious dosing regimen (100 mg/kg/day), administration of 2ME2 resulted in total inhibition of the study parameters and prevented neovascularization into the joint. Examination of gene expression on dissected hind limbs from mice treated for 5 or 14 days with 2ME2 showed inhibition of inflammatory cytokine message for IL-1β, TNF-α, IL-6 and IL-17, as well as the angiogenic cytokines, VEGF and FGF-2.</p> <p>Conclusion</p> <p>These data demonstrate that in the CAIA mouse model of RA, 2ME2 has disease modifying activity that is at least partially attributable to the inhibition of neovascular development. Further, the data suggests new mechanistic points of intervention for 2ME2 in RA, specifically inhibition of inflammatory mediators and osteoclast activity.</p

TNF autovaccination induces self anti-TNF antibodies and inhibits metastasis in a murine melanoma model

TNF is a proinflammatory cytokine involved in the pathogenesis of chronic inflammatory diseases, but also in metastasis in certain types of cancer. In terms of therapy, TNF is targeted by anti-TNF neutralising monoclonal antibodies or soluble TNF receptors. Recently, a novel strategy based on the generation of self anti-TNF antibodies (TNF autovaccination) has been developed. We have previously shown that TNF autovaccination successfully generates high anti-TNF antibody titres, blocks TNF and ameliorates collagen-induced arthritis in DBA/1 mice. In this study, we examined the ability of TNF autovaccination to generate anti-TNF antibody titres and block metastasis in the murine B16F10 melanoma model. We found that immunisation of C57BL/6 mice with TNF autovaccine produces a 100-fold antibody response to TNF compared to immunisation with phosphate-buffered saline vehicle control and significantly reduces both the number (P&lt;0.01) and size of metastases (P&lt;0.01) of B16F10 melanoma cells. This effect is also observed when an anti-TNF neutralising monoclonal antibody is administered, confirming the essential role TNF plays in metastasis in this model. This study suggests that TNF autovaccination is a cheaper and highly efficient alternative that can block TNF and reduce metastasis in vivo and trials with TNF autovaccination are already underway in patients with metastatic cancer

Linking Power Doppler Ultrasound to the Presence of Th17 Cells in the Rheumatoid Arthritis Joint

Power Doppler ultrasound (PDUS) is increasingly used to assess synovitis in Rheumatoid Arthritis (RA). Prior studies have shown correlations between PDUS scores and vessel counts, but relationships with T cell immunopathology have not been described.PBMC were isolated from healthy controls (HC) or RA patients and stimulated ex vivo with PMA and ionomycin for 3 hours in the presence of Golgistop. Paired synovial fluid (SF) or synovial tissue (ST) were analysed where available. Intracellular expression of IL-17, IFNgamma, and TNFalpha by CD4+ T cells was determined by flow cytometry. Synovial blood flow was evaluated by PDUS signal at the knees, wrists and metacarpophalangeal joints of RA patients. Serum, SF and fibroblast culture supernatant levels of vascular endothelial growth factor-A (VEGF-A) were measured by ELISA. The frequency of IL17+IFNgamma-CD4+ T cells (Th17 cells) was significantly elevated in peripheral blood (PB) from RA patients vs. HC (median (IQR) 0.5 (0.28-1.59)% vs. 0.32 (0.21-0.54)%, p = 0.005). Th17 cells were further enriched (mean 6.6-fold increase) in RA SF relative to RA PB. Patients with active disease had a higher percentage of IL-17+ T cells in ST than patients in remission, suggesting a possible role for Th17 cells in active synovitis in RA. Indeed, the percentage of Th17 cells, but not Th1, in SF positively correlated with CRP (r = 0.51, p = 0.04) and local PDUS-defined synovitis (r = 0.61, p = 0.002). Furthermore, patients with high levels of IL-17+CD4+ T cells in SF had increased levels of the angiogenic factor VEGF-A in SF. Finally, IL-17, but not IFNgamma, increased VEGF-A production by RA synovial fibroblasts in vitro.Our data demonstrate a link between the presence of pro-inflammatory Th17 cells in SF and local PDUS scores, and offer a novel immunological explanation for the observation that rapid joint damage progression occurs in patients with persistent positive PDUS signal