Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0018099 (gout)
 5,192 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The activation of human neutrophils by monosodium urate and calcium pyrophosphate dihydrate crystals is believed to play a critical role in the pathogenesis of arthritides such as acute gout and pseudogout, respectively. In this study, we investigated the potential involvement of tyrosine phosphorylation in microcrystal-mediated activation of human neutrophils. Immunoblot analysis with antiphosphotyrosine antibodies demonstrated that triclinic monosodium urate and calcium pyrophosphate dihydrate crystals stimulated a time- and concentration-dependent tyrosine phosphorylation of at least five proteins (pp130, 118, 80, 70, and 60). While phosphoprotein (pp) 118 and pp70 were the major phosphorylated substrates, pp70 was the dominant one in reactivity with antiphosphotyrosine antibodies. When the temporal patterns, as well as the levels of tyrosine phosphorylation for both types of crystals were compared, monosodium urate crystals were found to be more potent activators than calcium pyrophosphate dihydrate crystals. The tyrosine phosphorylation patterns induced by microcrystals differed from those stimulated by other soluble (FMLP, C5a, or leukotriene B4) or particulate (unopsonized latex beads or zymosan) agonists which stimulated preferentially the tyrosine phosphorylation of pp118. The ratio of the intensities of pp118 and pp70 were specific of the stimulation with microcrystals when compared to those observed with the other soluble or particulate agonists. Colchicine, a drug used specifically in the treatment of gout and pseudogout, inhibited microcrystal-induced tyrosine phosphorylation, while beta- and gamma-lumicolchicine were without effect. On the other hand, colchicine failed to inhibit FMLP-induced tyrosine phosphorylation. Furthermore, while colchicine inhibited the activation of the NADPH oxidase by microcrystals, it, on the other hand, enhanced the production of superoxide anions by FMLP. Taken together, these results (a) demonstrate that tyrosine phosphorylation is involved in the mechanism of activation of human neutrophils induced by microcrystals; and (b) suggest, on the basis of the characteristics of the observed patterns of tyrosine phosphorylation, that this response may be specific to the microcrystals and relevant to their phlogistic properties.
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PMID:Crystal-induced neutrophil activation. III. Inflammatory microcrystals induce a distinct pattern of tyrosine phosphorylation in human neutrophils. 838 91

The formation and deposition of monosodium urate (MSU) microcrystals in articular and periarticular tissues is the causative agent of acute or chronic inflammatory responses known as gouty arthritis. Mononuclear phagocyte activation is involved in early triggering events of gout attacks. Because stimulated mononuclear phagocytes can constitute an important source of the inducible isoform of cyclooxygenase (COX-2), we evaluated the effects that proinflammatory microcrystals might have on COX-2 protein expression in crystal-stimulated monocytes. We found that MSU crystals, but not calcium pyrophosphate dihydrate (CPPD) crystals, induced COX-2, which correlated with the synthesis of prostaglandin E2 (PGE2) and thromboxane A2 (TXA2). Crystal-induced de novo synthesis of COX-2 was dependent on transcriptional and translational events. Inhibition of tyrosine phosphorylation, by herbimycin A, blocked crystal-induced COX-2. Similarly, an inhibitor of the p38 mitogen-activated protein kinase, SB 203580, inhibited the stimulation of COX-2. Colchicine inhibited crystal-induced COX-2. In all cases, prostanoid synthesis was concomitantly inhibited. Taken together, these results implicate COX-2 in the development of MSU-induced inflammation.
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PMID:Monosodium urate microcrystals induce cyclooxygenase-2 in human monocytes. 947 45

Src homology 2 (SH2) domains exist in many intracellular proteins and have well characterized roles in signal transduction. SH2 domains bind to phosphotyrosine (Tyr(P))-containing proteins. Although tyrosine phosphorylation is essential for protein-SH2 domain interactions, the binding specificity also derives from sequences C-terminal to the Tyr(P) residue. The high affinity and specificity of this interaction is critical for precluding aberrant cross-talk between signaling pathways. The p85alpha subunit of phosphoinositide 3-kinase (PI 3-kinase) contains two SH2 domains, and it has been proposed that in competition with Tyr(P) binding they may also mediate membrane attachment via interactions with phosphoinositide products of PI 3-kinase. We used nuclear magnetic resonance spectroscopy and biosensor experiments to investigate interactions between the p85alpha SH2 domains and phosphoinositides or inositol polyphosphates. We reported previously a similar approach when demonstrating that some pleckstrin homology domains show binding specificity for distinct phosphoinositides (Salim, K., Bottomley, M. J., Querfurth, E., Zvelebil, M. J., Gout, I., Scaife, R., Margolis, R. L., Gigg, R., Smith, C. I., Driscoll, P. C., Waterfield, M. D., and Panayotou, G. (1996) EMBO J. 15, 6241-6250). However, neither SH2 domain exhibited binding specificity for phosphoinositides in phospholipid bilayers. We show that the p85alpha SH2 domain Tyr(P) binding pockets indiscriminately accommodate phosphoinositides and inositol polyphosphates. Binding of the SH2 domains to Tyr(P) peptides was only poorly competed for by phosphoinositides or inositol polyphosphates. We conclude that these ligands do not bind p85alpha SH2 domains with high affinity or specificity. Moreover, we observed that although wortmannin blocks PI 3-kinase activity in vivo, it does not affect the ability of tyrosine-phosphorylated proteins to bind to p85alpha. Consequently phosphoinositide products of PI 3-kinase are unlikely to regulate signaling through p85alpha SH2 domains.
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PMID:Structural and biochemical evaluation of the interaction of the phosphatidylinositol 3-kinase p85alpha Src homology 2 domains with phosphoinositides and inositol polyphosphates. 1033 65

Gout affects mostly males over 40 years old and, occasionally, postmenopausal women. This pattern coincides with the pattern of iron accumulation. On the other hand, menstruating women are seldom afflicted by gout, because the monthly blood loss causes them to accumulate iron to a much lesser degree. Gout involves seven aspects: (1) uric acid overproduction from increased purines in the diet; (2) uric acid overproduction from ATP degradation; (3) uric acid overproduction from increased de novo synthesis of purines; (4) uric acid overproduction from increased DNA breakdown from cell damage; (5) decreased uric acid elimination, caused by molybdenum and sulfur binding to copper in the kidneys; (6) precipitation of sodium urate-iron crystals in the joints due to high ferritin and saturated transferrin and low CuZn-SOD and Cu-thionein in the joint; (7) development of inflammation, triggered by tyrosine bonding to the sodium-urate-iron crystals and being transformed by tyrosine kinase. Alcohol and iron greatly affect most of these aspects. Therefore, phlebotomy is suggested as therapy for gout patients, in order to eliminate the accumulated Fe. Furthermore, yearly blood donation is recommended for males with a family history of gout, so as to prevent Fe accumulation and avoid gout.
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PMID:Effect of gradual accumulation of iron, molybdenum and sulfur, slow depletion of zinc and copper, ethanol or fructose ingestion and phlebotomy in gout. 1061 42

Neutrophil-dependent inflammation dependent on monosodium urate (MSU) crystal-induced IL-8 expression occurs in gout. MSU crystals activate phagocyte Src family tyrosine kinases and the serine/threonine kinase p70s6k. Thus, using monocytic THP-1 cells, we assessed the potential for Src family kinases and p70s6k to mediate MSU-induced IL-8 expression. MSU crystals induced phosphorylation of p70s6k and the Src kinases c-Src, Lyn, Hck, and Fyn. IL-8 expression was attenuated more by the Src kinase inhibitor PP1 than by the p70s6k inhibitor rapamycin. PP1 inhibited crystal-induced phosphorylation of ERK1/2 and IkappaBalpha and suppressed IkappaB kinase (IKK) activation and NF-kappaB binding to the IL-8 promoter, signals that mediate MSU-induced IL-8 expression. Transfection of the native Src inhibitor, C-terminal Src kinase (Csk), also suppressed crystal-induced c-Src, ERK1/2, and IkappaBalpha phosphorylation and IL-8 expression. We conclude that Src family tyrosine kinase signaling plays a significant role in MSU crystal-induced IL-8 expression via stimulation of ERK1/2 pathway and NF-kappaB activation.
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PMID:Src family protein tyrosine kinase signaling mediates monosodium urate crystal-induced IL-8 expression by monocytic THP-1 cells. 1173 59

Uric acid (UA) is a purine metabolite that selectively inhibits peroxynitrite-mediated reactions implicated in the pathogenesis of multiple sclerosis (MS) and other neurodegenerative diseases. Serum UA levels are inversely associated with the incidence of MS in humans because MS patients have low serum UA levels and individuals with hyperuricemia (gout) rarely develop the disease. Moreover, the administration of UA is therapeutic in experimental allergic encephalomyelitis (EAE), an animal model of MS. Thus, raising serum UA levels in MS patients, by oral administration of a UA precursor such as inosine, may have therapeutic value. We have assessed the effects of inosine, as well as inosinic acid, on parameters relevant to the chemical reactivity of peroxynitrite and the pathogenesis of EAE. Both had no effect on chemical reactions associated with peroxynitrite, such as tyrosine nitration, or on the activation of inflammatory cells in vitro. Moreover, when mice treated with the urate oxidase inhibitor potassium oxonate were fed inosine or inosinic acid, serum UA levels were elevated markedly for a period of hours, whereas only a minor, transient increase in serum inosine was detected. Administration of inosinic acid suppressed the appearance of clinical signs of EAE and promoted recovery from ongoing disease. The therapeutic effect on animals with active EAE was associated with increased UA, but not inosine, levels in CNS tissue. We, therefore, conclude that the mode of action of inosine and inosinic acid in EAE is via their metabolism to UA.
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PMID:Therapeutic intervention in experimental allergic encephalomyelitis by administration of uric acid precursors. 1245 Nov 83

Medullary cystic kidney disease type 2 is an uncommon autosomal dominant condition characterized by juvenile onset hyperuricemia, precocious gout and chronic renal failure progressing to end-stage renal disease in the 4th through 7th decades of life. A family suffering from this condition is described. The patient in the index case presented with renal insufficiency as a child. A renal biopsy revealed tubular atrophy, and immunohistochemical staining of the tissue for uromodulin (Tamm Horsfall protein) revealed dense deposits in renal tubular cells. Genetic testing revealed a single nucleotide mutation (c.899G>A) resulting in an exchange of a cysteine residue for tyrosine (C300Y). Medullary cystic kidney disease type 2 (also known as uromodulin-associated kidney disease) likely represents a form of endoplasmic reticulum storage disease, with deposition of the abnormal uromodulin protein in the endoplasmic reticulum, leading to tubular cell atrophy and death.
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PMID:Clinico-pathologic findings in medullary cystic kidney disease type 2. 1584 1

The deposition of monosodium urate (MSU) crystals in the joints of humans leads to an extremely acute, inflammatory reaction, commonly known as gout, characterized by a massive infiltration of neutrophils. Direct interactions of MSU crystals with human neutrophils and inflammatory mediators are crucial to the induction and perpetuation of gout attacks. The intracellular signaling events initiated by the physical interaction between MSU crystals and neutrophils depend on the activation of specific tyrosine kinases (Src and Syk, in particular). In addition, PI-3Ks may be involved. The present study investigates the involvement of the PI-3K family in the mediation of the responses of human neutrophils to MSU crystals. The results obtained indicate that the interaction of MSU crystals with human neutrophils leads to the stimulation of class Ia PI-3Ks by a mechanism that is dependent on the tyrosine kinase Syk. We also found an increase in the amount of p85 associated with the Nonidet P-40-insoluble fraction derived from MSU crystal-stimulated human neutrophils. Furthermore, MSU crystals induce the formation of a complex containing p85 and Syk, which is mediated by the Src family kinases. Finally, evidence is also obtained indicating that the activation of PI-3Ks by MSU crystals is a critical element regulating phospholipase D activation and degranulation of human neutrophils. The latter response is likely to be involved in the joint and tissue damage that occurs in gouty patients.
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PMID:Crystal-induced neutrophil activation. IX. Syk-dependent activation of class Ia phosphatidylinositol 3-kinase. 1753 83

Paracetamol is used worldwide for its analgesic and antipyretic actions. It has a spectrum of action similar to that of NSAIDs and resembles particularly the COX-2 selective inhibitors. Paracetamol is, on average, a weaker analgesic than NSAIDs or COX-2 selective inhibitors but is often preferred because of its better tolerance. Despite the similarities to NSAIDs, the mode of action of paracetamol has been uncertain, but it is now generally accepted that it inhibits COX-1 and COX-2 through metabolism by the peroxidase function of these isoenzymes. This results in inhibition of phenoxyl radical formation from a critical tyrosine residue essential for the cyclooxygenase activity of COX-1 and COX-2 and prostaglandin (PG) synthesis. Paracetamol shows selectivity for inhibition of the synthesis of PGs and related factors when low levels of arachidonic acid and peroxides are available but conversely, it has little activity at substantial levels of arachidonic acid and peroxides. The result is that paracetamol does not suppress the severe inflammation of rheumatoid arthritis and acute gout but does inhibit the lesser inflammation resulting from extraction of teeth and is also active in a variety of inflammatory tests in experimental animals. Paracetamol often appears to have COX-2 selectivity. The apparent COX-2 selectivity of action of paracetamol is shown by its poor anti-platelet activity and good gastrointestinal tolerance. Unlike both non-selective NSAIDs and selective COX-2 inhibitors, paracetamol inhibits other peroxidase enzymes including myeloperoxidase. Inhibition of myeloperoxidase involves paracetamol oxidation and concomitant decreased formation of halogenating oxidants (e.g. hypochlorous acid, hypobromous acid) that may be associated with multiple inflammatory pathologies including atherosclerosis and rheumatic diseases. Paracetamol may, therefore, slow the development of these diseases. Paracetamol, NSAIDs and selective COX-2 inhibitors all have central and peripheral effects. As is the case with the NSAIDs, including the selective COX-2 inhibitors, the analgesic effects of paracetamol are reduced by inhibitors of many endogenous neurotransmitter systems including serotonergic, opioid and cannabinoid systems. There is considerable debate about the hepatotoxicity of therapeutic doses of paracetamol. Much of the toxicity may result from overuse of combinations of paracetamol with opioids which are widely used, particularly in USA.
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PMID:The modern pharmacology of paracetamol: therapeutic actions, mechanism of action, metabolism, toxicity and recent pharmacological findings. 2371 33

Qigui Tongfeng tablet (QLTFT) is a traditional Chinese medicine with good effect for treating gout. Here, network pharmacology method and molecular similarity analysis were utilized to study the effective substance basis and molecular mechanism of the QLTFT on the gout. The similarity to the medicinal compounds is reflected in the Tanimoto coefficient that gives the structural similarity of two compounds. Operationally, similar modifiers were described as pairs of concepts with a similarity score of 0. 500. The results of the molecular similarity analysis suggested that the flavonoids in QLTFT could be new leads for gout. Furthermore, complex biological systems may be represented and analyzed as computable networks. Two important properties of a network were degree and betweenness. Nodes with high degree or high betweenness may play important roles in the overall composition of a network. And the results of network analysis showed that dongbeinine, verticinone-N-oxide, verticine N-oxide, peimine, peiminine, isobaimonidine, dongbeirine, peimisine and simi-arenol which with high degree acted on xanthine dehydrogenase/oxidase, matrix metalloproteinase-9, an arachidonate 5-lipoxygenase-activating protein, tyrosine-protein kinase and etc. Inhibition of these targets can prevent the formation of uric acid, reduce inflammation by uric acid and regulate the body's immune response. Thus, these compounds may be the main effective substance basis. The research results not only reveals its molecular mechanism, but also provide a theoretical basis for the quality control of drugs and clinical application.
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PMID:[Study on effective substance basis and molecular mechanism of Qigui Tongfeng tablet using network pharmacology method]. 2666 36


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