Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0003873 (rheumatoid arthritis)
 53,068 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The activation of sphingomyelinase and the generation of ceramide has been proposed to mediate tumor necrosis factor-alpha (TNF-alpha)-induced nuclear factor (NF)-kappaB activation through its second messenger ceramide. Ceramide may also be an important regulator of cell growth, senescence, and apoptosis. Aberrant cell proliferation and apoptosis have been implicated in the rampant fibroblast proliferation and pannus formation characteristic of rheumatoid arthritis. However, the role of TNF-alpha and the sphingomyelinase pathway in the process have not been determined. The objective of this study was to determine whether TNF-alpha activates the sphingomyelin pathway in human synovial fibroblasts (HSF) and the potential role of ceramide in HSF proliferation and apoptosis. Cultured human synovial fibroblasts were stimulated with exogenous TNF-alpha, sphingomyelinase, and ceramide. Apoptosis was assessed by cell morphology and annexin V labeling. NF-kappaB and stress kinase pathway activation were determined by immunoblotting techniques. Sphingomyelinase activation was determined by quantitation of sphingomyelin and ceramide radioactivity in [14C]serine-prelabeled HSF cells. The addition of TNF-alpha (50 ng/ml) to HSF did not elicit detectable sphingomyelinase activation. TNF-alpha was shown to activate NF-kappaB (p65 translocation and degradation of IkappaBalpha) and the stress kinase pathway (phosphorylation of ATF-2, p38, and c-jun). In contrast, exogenous ceramide had no effect on these signaling pathways nor did ceramide stimulate the generation of interleukin-6 or interleukin-8. High concentrations of ceramide (> or =25 micromol/L) were cytotoxic, whereas lower concentrations of ceramide inhibited cell cycle progression. Thus, although TNF-alpha stimulates the NF-kappaB and stress kinase pathways in HSF, these effects of TNF-alpha are not associated with sphingomyelinase turnover or induction of apoptosis.
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PMID:Synovial fibroblasts and the sphingomyelinase pathway: sphingomyelin turnover and ceramide generation are not signaling mechanisms for the actions of tumor necrosis factor-alpha. 946 77

The synovium in rheumatoid arthritis (RA) is characterized by an increase in lining layer thickness and infiltration of inflammatory cells into the sublining area. Fibroblasts in the lining layer develop the appearance of "transformed cells", under the influence of proto-oncogenes involved in the regulation of the cell cycle. Fibroblast and macrophage-derived cytokines such as IL-1 and TNF-alpha are present abundantly in the rheumatoid synovium and stimulate these cells to produce destructive enzymes. Other cytokines such as IL-4 and IL-10 represent a physiological attempt to reverse the inflammatory process. Adhesion molecules facilitate both the migration of cells to the joint as well as the attachment of synovium to bone and cartilage. Joint destruction is mediated by enzymes such as serine proteases, matrix metalloproteinases (MMPs) and the cathepsins. Treatments directed against various components of the inflammatory cascade have shown promise. Inhibition of MMPs or adhesion molecules, blockade of IL-1 or TNF-alpha and the use of anti-Fas antibodies to induce apoptosis offer new possibilities for the treatment of RA. More recently, the employment of genes with antiarthritic properties has shown therapeutic potential.
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PMID:Mechanism of joint destruction in rheumatoid arthritis. 951 Sep 39

Activated CTLs and NK cells induce apoptosis via multiple mechanisms, including that termed granule exocytosis. The latter pathway consists of vectorial secretion of perforin and a family of granule-associated serine proteases (granzymes) to the target cell. To establish whether granzymes are released extracellularly during cytolytic reactions in vivo, ELISAs that measure the native enzymes were developed and were found to specifically detect granzyme A (GrA) and granzyme B (GrB) at picogram concentrations. Low levels of GrA and GrB were present in plasma of healthy individuals (GrA, 33.5 pg/ml (median); GrB, 11.5 pg/ml (median)), whereas significantly higher levels were present in patients with ongoing CTL response, i.e., patients suffering from infections by EBV or HIV type 1. Markedly elevated levels were also noted in synovial fluid of patients with active rheumatoid arthritis. The measurement of soluble granzymes should be useful to assess clinical disorders associated with activated CTL and NK cells. Furthermore, these results suggest that granzymes mediate biologic effects beyond their described role in apoptotic cell death.
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PMID:Extracellular granzymes A and B in humans: detection of native species during CTL responses in vitro and in vivo. 953 25

Rheumatoid factors (RF) recognize conformational determinants located within the Fc portion of IgG. By analyzing a panel of monoclonal rheumatoid arthritis (RA)-derived RFs, we previously demonstrated that the somatically generated light chain complementarity-determining region 3 (CDR3) contributes to RF specificity. We have now generated a panel of heavy chain mutants of the B'20 Ab, a high affinity RA-derived IgM RF. B'20 also binds avidly to protein A and weakly to ssDNA and tetanus toxoid. B9601, a RF negative Ab that is highly homologous to B'20 but does not bind any of the Ags tested, and RC1, a low affinity polyreactive RF, were used to generate heavy chain mutants with framework (FR) and CDR switches. The mutated heavy chains were cotransfected into a myeloma cell line with the germline counterpart of the B'20 light chain, and the expressed Ig tested for antigenic specificity. We show that both RF specificity and polyreactivity of B'20 is dependent on its unique heavy chain CDR3 region. Replacement with a B9601 CDR3 shortened to the same length as the B'20 CDR3, and with only 5 amino acid differences, did not restore Fc binding. Conversely, absence of protein A binding of B9601 is due to the presence of a serine residue at position 82a in the B9601 heavy chain FR3 region. Together, our data suggest that Ig gene recombination events can generate B cells with autoantibody specificities in the preimmune repertoire. Abnormal release, activation, expansion, or mutation of such cells might all contribute to the generation of a high titer RF response in patients with RA.
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PMID:Rheumatoid factor specificity of a VH3-encoded antibody is dependent on the heavy chain CDR3 region and is independent of protein A binding. 972 22

It has been shown that cells with high affinity very late Ag (VLA)-integrins have up-regulated expression of a beta1-subunit epitope, which is detected by 15/7 mAb. In this study, we demonstrate that soluble VCAM-1 (sVCAM-1) exhibits chemotactic activity of T cells with high affinity VLA-4 against VCAM-1, such as Jurkat T cells and IL-2-dependent T cells. Moreover, we found that T cells in the synovial fluid show high basal migration in the absence of sVCAM-1, compared with peripheral blood T cells in patients with rheumatoid arthritis. Among T cells in the synovial fluid, CD45RO+ memory T cells, in response to sVCAM-1, showed a much higher than basal migratory response when compared with CD45RA+ naive cells, while no significant difference was observed between CD4+ and CD8+ T cells. The chemotactic activity of sVCAM-1 is inhibited in the presence of anti-VCAM-1 and anti-VLA-4, which interfered with the binding between VCAM-1 and VLA-4. Inhibition studies using various kinase inhibitors (C3 exoenzyme, KN62, and H7) show that Rho, Ca2+/calmodulin-dependent kinase II, and protein kinase C are involved in signal transduction in sVCAM-1-induced chemotaxis, respectively, whereas tyrosine kinase seems to play a lesser role, since genistein showed only partial inhibition of T cell chemotaxis. Western blot analysis using an anti-phospho-serine mAb (MO82) reveals that Ser82 in the vimentin is phosphorylated specifically by Ca2+/calmodulin-dependent kinase II through sVCAM-1 activation in the IL-2 dependent T cells. Collectively, by inducing migration and recruitment of T cells through several kinase activations, sVCAM-1 contributes to the development of the inflammation of synovial lesion.
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PMID:Soluble VCAM-1 induces chemotaxis of Jurkat and synovial fluid T cells bearing high affinity very late antigen-4. 979 28

Circulating insulin-like growth factor binding protein-3 (IGFBP-3) proteolytic activity is normally low but increases in serum from pregnant women and from patients with various pathologies. In contrast, we have recently reported that outside the circulation, such activity is normally high but decreases in various pathologies. We have now compared components of the IGFBP-3 proteolytic system revealed after size fractionation of serum and extravascular fluids with different intrinsic levels of such activity. Normal serum, serum from pregnant women, and synovial fluid from patients with rheumatoid arthritis revealed high and low molecular weight (MW) areas of activity. However, only the low MW activity was apparent in interstitial fluid from normal skin (N Inst F) or psoriatic lesions (P Inst F) and in synovial fluid from normal volunteers (N Syn F) or patients with osteoarthritis (OA Syn F). Addition of inhibitors revealed both areas to comprise more than one enzyme, including serine proteases and metalloproteinases; both could also be inhibited by P Inst F, NS, RA Syn F, and inhibitory fractions from the separation of the latter two. These findings demonstrate low and high MW regions of proteolytic activity, which may contribute to the IGFBP-3 protease system, the former always present, whereas the latter seems to be retained within the circulation apart from inflammatory conditions. The variations apparent in IGFBP-3 protease activity in the intact samples related to the presence of an inhibitor, which may protect IGFBP-3 from proteolysis, rather than to changes in the component proteases.
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PMID:Active and inhibitory components of the insulin-like growth factor binding protein-3 protease system in adult serum, interstitial, and synovial fluid. 983 13

Granzyme B is the prototypic member of the granzymes, a family of trypsin-like serine proteinases localized in the dense cytoplasmic granules of activated natural killer cells and cytotoxic T lymphocytes. Granzyme B directly triggers apoptosis in target cells by activating the caspase pathway, and has been implicated in the etiology of rheumatoid arthritis. Human granzyme B expressed in a baculovirus system has been crystallized without inhibitor and its structure has been determined to 3.1 A resolution, after considerably improving the diffraction power of the crystals by controlled humidity changes. The granzyme B structure reveals an overall fold similar to that found in cathepsin G and human chymase. The guanidinium group of Arg226, anchored at the back of the S1-specificity pocket, can form a salt bridge with the P1-Asp side chain of a bound peptide substrate. The architecture of the substrate binding site of granzyme B appears to be designed to accommodate and cleave hexapeptides such as the sequence Ile-Glu-Thr-Asp-/Ser-Gly present in the activation site of pro-caspase-3, a proven physiological substrate of granzyme B. These granzyme B crystals, with fully accessible active sites, are well suited for soaking with small synthetic inhibitors that might be used for a treatment of chronic inflammatory disorders.
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PMID:Crystal structure of the caspase activator human granzyme B, a proteinase highly specific for an Asp-P1 residue. 1120 55

We measured and compared the activities of various kinds of proteinases, such as cysteine, serine, aspartic, and metalloproteinases, in synovial fluids of 16 patients with rheumatoid arthritis (RA) and 18 patients with osteoarthritis (OA). More than 19-fold higher activity of cathepsin B and about 6-fold higher activity of prolylendopeptidase, compared to those of OA, were accumulated in RA fluid. Moreover, levels of cathepsins B and S using the corresponding sandwich enzyme immunoassays were statistically higher in RA fluid than those in OA. Significant amounts of 41-kDa and 35-kDa procathepsin L were detected in RA fluid using gelatin zymography, while 41-kDa enzyme alone was detected in OA. Cathepsin B in RA fluid could degrade collagen, and this degradation was suppressed by the addition of CA-074, a specific inhibitor of cathepsin B. Therefore, cathepsin B may participate in joint destruction of RA, and its inhibitor may be effective for RA care.
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PMID:Significance of cathepsin B accumulation in synovial fluid of rheumatoid arthritis. 1132 3

The serine proteinase elastase is located in the azurophil granules of mature circulating polymorphonuclear neutrophils. This neutrophil elastase or NE is a potent non specific serine protease which plays a role as bactericidal agent and in the degradation of immune complexes by intraphagosomal processes. It promotes inflammation when the granule contents are secreted in the extracellular environment. In certain pathological circumstances, an imbalance between NE and its major plasmatic inhibitor alpha 1-PI (formerly, alpha 1-antitrypsin) leads to abnormal tissue destruction and disease development. Genetic or acquired alpha 1-PI deficiency is thought to be involved in the pathogenesis of pulmonary emphysema. A variety of degenerative and degradative disorders are also associated to uncontrolled proteolysis by NE (rheumatoid arthritis, glomerulonephritis, adult respiratory distress symptom, psoriasis, cancer). Numerous inhibitors of NE have been reported. Various molecules are currently undergoing clinical trials for emphysema and other pulmonary diseases.
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PMID:[Elastase inhibitors]. 1172 26

The receptor for advanced glycation end products (RAGE) and its proinflammatory S100/calgranulin ligands are enriched in joints of subjects with rheumatoid arthritis (RA) and amplify the immune/inflammatory response. In a model of inflammatory arthritis, blockade of RAGE in mice immunized and challenged with bovine type II collagen suppressed clinical and histologic evidence of arthritis, in parallel with diminished levels of TNF-alpha, IL-6, and matrix metalloproteinases (MMP) 3, 9 and 13 in affected tissues. Allelic variation within key domains of RAGE may influence these proinflammatory mechanisms, thereby predisposing individuals to heightened inflammatory responses. A polymorphism of the RAGE gene within the ligand-binding domain of the receptor has been identified, consisting of a glycine to serine change at position 82. Cells bearing the RAGE 82S allele displayed enhanced binding and cytokine/MMP generation following ligation by a prototypic S100/calgranulin compared with cells expressing the RAGE 82G allele. In human subjects, a case-control study demonstrated an increased prevalence of the 82S allele in patients with RA compared with control subjects. These data suggest that RAGE 82S upregulates the inflammatory response upon engagement of S100/calgranulins, and, thereby, may contribute to enhanced proinflammatory mechanisms in immune/inflammatory diseases.
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PMID:RAGE and arthritis: the G82S polymorphism amplifies the inflammatory response. 1207 Jul 74


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