Differential regulation of vascular endothelial growth factor and its receptor fms-like-tyrosine kinase is mediated by nitric oxide in rat renal mesangial cells.
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Under conditions associated with local and systemic inflammation, mesangial cells and invading immune cells are likely to be responsible for the release of large amounts of nitric oxide (NO) in the glomerulus. To further define the mechanisms of NO action in the glomerulus, we attempted to identify genes which are regulated by NO in rat glomerular mesangial cells. We identified vascular endothelial growth factor (VEGF) and its receptor fms-like tyrosine kinase (FLT-1) to be under the regulatory control of exogenously applied NO in these cells. Using S-nitroso-glutathione (GSNO) as an NO-donating agent, VEGF expression was strongly induced, whereas expression of its FLT-1 receptor simultaneously decreased. Expressional regulation of VEGF and FLT-1 mRNA was transient and occurred rapidly within 1-3 h after GSNO treatment. Expression of a second VEGF-specific receptor, fetal liver kinase-1 (FLK-1/KDR), could not be detected. The inflammatory cytokine interleukin-1beta mediated a moderate increase in VEGF expression after 24 h and had no influence on FLT-1 expression. In contrast, platelet-derived growth factor-BB and basic fibroblast growth factor had no effect on VEGF expression, but strongly induced FLT-1 mRNA levels. Obviously, there is a differential regulation of VEGF and its receptor FLT-1 by NO, cytokines and growth factors in rat mesangial cells. (+info)
Dephosphorylation of the catenins p120 and p100 in endothelial cells in response to inflammatory stimuli.
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Inflammatory mediators such as histamine and thrombin increase the tight-junction permeability of endothelial cells. Tight-junction permeability may be independently controlled, but is dependent on the adherens junction, where adhesion is achieved through homotypic interaction of cadherins, which in turn are associated with cytoplasmic proteins, the catenins. p120, also termed p120(cas)/p120(ctn), and its splice variant, p100, are catenins. p120, originally discovered as a substrate of the tyrosine kinase Src, is also a target for a protein kinase C-stimulated pathway in epithelial cells, causing its serine/threonine dephosphorylation. The present study shows that pharmacological activation of protein kinase C stimulated a similar pathway in endothelial cells. Activation of receptors for agents such as histamine (H1), thrombin and lysophosphatidic acid in the endothelial cells also caused serine/threonine dephosphorylation of p120 and p100, suggesting physiological relevance. However, protein kinase C inhibitors, although blocking the effect of pharmacological activation of protein kinase C, did not block the effects due to receptor activation. Calcium mobilization and the myosin-light-chain-kinase pathway do not participate in p120/p100 signalling. In conclusion, endothelial cells possess protein kinase C-dependent and -independent pathways regulating p120/p100 serine/threonine phosphorylation. These data describe a new connection between inflammatory agents, receptor-stimulated signalling and pathways potentially influencing intercellular adhesion in endothelial cells. (+info)
CD40 signaling of monocyte inflammatory cytokine synthesis through an ERK1/2-dependent pathway. A target of interleukin (il)-4 and il-10 anti-inflammatory action.
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Ligation of CD40 on monocytes through its interaction with CD40 ligand (CD154) present on activated T helper cells, results in activation of monocyte inflammatory cytokine synthesis and rescue of monocytes from apoptosis induced through serum deprivation. Both of these consequences of CD40 stimulation have been shown to be dependent on the induction of protein tyrosine kinase activity. CD40-mediated activation of protein tyrosine kinase activity and subsequent inflammatory cytokine production are abrogated by treatment of monocytes with the T helper type 2 cytokines interleukin 4 (IL-4) and interleukin 10 (IL-10). In the current study we demonstrate that stimulation of monocytes through CD40 resulted in the phosphorylation and activation of the extracellular signal-regulated kinases 1 and 2 (ERK1/2) mitogen-activated protein kinases, whereas phosphorylation of mitogen-activated protein kinases family members p38 and c-Jun N-terminal kinase was not observed in response to this stimuli over the time course examined. PD98059, an inhibitor of the upstream activator of ERK1/2, the MAP/ERK kinase MEK1/2, suppressed IL-1beta and tumor necrosis factor-alpha production in a dose-dependent fashion. Pretreatment of monocytes with IL-4 and IL-10 inhibited CD40-mediated activation of ERK1/2 kinase activity when used individually, and are enhanced in effectiveness when used in combination. Together, the data demonstrate that CD40-mediated induction of IL-1beta and tumor necrosis factor-alpha synthesis is dependent on a MEK/ERK pathway which is obstructed by signals generated through the action of IL-4 and IL-10. (+info)
The vitronectin receptor and its associated CD47 molecule mediates proinflammatory cytokine synthesis in human monocytes by interaction with soluble CD23.
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The vitronectin receptor, alphavbeta3 integrin, plays an important role in tumor cell invasion, angiogenesis, and phagocytosis of apoptotic cells. CD47, a member of the multispan transmembrane receptor family, physically and functionally associates with vitronectin receptor (VnR). Although vitronectin (Vn) is not a ligand of CD47, anti-CD47 and beta3 mAbs suppress Vn, but not fibronectin (Fn) binding and function. Here, we show that anti-CD47, anti-beta3 mAb and Vn, but not Fn, inhibit sCD23-mediated proinflammatory function (TNF-alpha, IL-12, and IFN-gamma release). Surprisingly, anti-CD47 and beta3 mAbs do not block sCD23 binding to alphav+beta3+ T cell lines, whereas Vn and an alphav mAb (clone AMF7) do inhibit sCD23 binding, suggesting the VnR complex may be a functional receptor for sCD23. sCD23 directly binds alphav+beta3+/CD47(-) cell lines, but coexpression of CD47 increases binding. Moreover, sCD23 binds purified alphav protein and a single human alphav chain CHO transfectant. We conclude that the VnR and its associated CD47 molecule may function as a novel receptor for sCD23 to mediate its proinflammatory activity and, as such, may be involved in the inflammatory process of the immune response. (+info)
The effects of inflammation and inflammatory mediators on nociceptive behaviour induced by ATP analogues in the rat.
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1. We have studied the behavioural effects of intraplantar injections of adenosine 5'-triphosphate (ATP) and related compounds in freely moving rats and investigated whether these nociceptive effects are augmented in the presence of inflammatory mediators. 2. We find that in normal animals ATP and analogues produce dose-dependent nocifensive behaviour (seen as bursts of elevation of the treated hindpaw), and localized thermal hyperalgesia. The rank order of potency was: alpha,beta-methyleneadenosine 5'-triphosphate (alpha,beta-methylene ATP) > 2-methylthioadenosine triphosphate (2-methylthio ATP) > ATP. After neonatal treatment with capsaicin, to destroy small calibre primary sensory neurones, nocifensive behaviour was largely absent. 3. The effects of ATP analogues were assessed in three models of peripheral sensitization: 2 h after dilute intraplantar carrageenan (0.25% w v(-1)); 24 h after irradiation of the hindpaw with ultraviolet (U.V.) B; immediately following prostaglandin E2 (PGE2) treatment. In all models the effect of alpha,beta-methylene ATP was greatly augmented. After carrageenan, significant hindpaw-lifting behaviour activity was induced by injection of only 0.05 nmol of alpha,beta-methylene ATP, some 100 times less than necessary in normal skin. 4. Our data suggest that it is much more likely that endogenous levels of ATP will reach levels capable of exciting nociceptors in inflamed versus normal skin. Our data also suggest the involvement of P2X3 receptor subunits in ATP-induced nociception. (+info)
Airway inflammatory response to ozone in subjects with different asthma severity.
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The aim of this study was to evaluate whether ozone exposure induces a similar airway inflammatory response in subjects with different degrees of asthma severity. Two groups of asthmatic subjects were studied: seven with intermittent mild asthma not requiring regular treatment (group A); and seven with persistent mild asthma requiring regular treatment with inhaled corticosteroids and long-acting beta2-agonists (group B). All subjects were exposed, in a randomized cross-over design, to air or O3 (0.26 parts per million (ppm) for 2 h with intermittent exercise); subjects in group B withdrew from regular treatment 72 h before each exposure. Before the exposure, and 1 and 2 h after the beginning of the exposure they performed a pulmonary function test, and a questionnaire was completed to obtain a total symptom score (TSS). Six hours after the end of the exposure, hypertonic saline (HS) sputum induction was conducted. Sputum cell percentages, eosinophil cationic protein (ECP) and interleukin (IL)-8 concentrations in the sputum supernatant were measured. TSS significantly increased and forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) significantly decreased after O3 exposure in comparison with air exposure in group A, whereas no changes were observed in group B except for a significant decrement of FEV1 2 h after the beginning of O3 exposure. Sputum neutrophil percentage was significantly higher after O3 exposure than after air exposure in both groups (Group A: 70.2% (28-87) versus 26.6% (8.6-73.2); Group B: 62.1% (25-82.4) versus 27.9% (14.4-54)). IL-8 was higher in sputum supernatant collected 6 h after O3 exposure than after air, only in group A. No change due to O3 has been found in sputum eosinophil percentage and ECP concentration in both groups. In conclusion, the degree of airway response to a short-term exposure to ozone is different in subjects with asthma of different severity. The available data do not allow elucidation of whether this difference depends on the severity of the disease or on the regular anti-inflammatory treatment. (+info)
Cytokines and inflammatory mediators do not indicate acute infection in cystic fibrosis.
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Various treatment regimens and difficulties with research design are encountered with cystic fibrosis (CF) because no standard diagnostic criteria exist for defining acute respiratory exacerbations. This study evaluated the role of serial monitoring of concentrations of selected cytokines and inflammatory mediators in serum and sputum as predictors of respiratory exacerbation, as useful outcome measures for CF, and to guide therapy. Interleukin-8 (IL-8), tumor necrosis factor alpha (TNF-alpha), neutrophil elastase-alpha-1-protease inhibitor complex (NE complex), protein, and alpha-1-protease inhibitor (alpha-1-PI) were measured in serum and sputum collected from CF patients during respiratory exacerbations and periods of well-being. Levels of NE complex, protein, and alpha-1-PI in sputum rose during respiratory exacerbations and fell after institution of antibiotic therapy (P = 0.078, 0.001, and 0.002, respectively). Mean (+/- standard error of the mean) levels of IL-8 and TNF-alpha were extremely high in sputum (13,780 +/- 916 and 249.4 +/- 23.5 ng/liter, respectively) but did not change significantly with clinical deterioration of the patient (P > 0.23). IL-8 and TNF-alpha were generally undetectable in serum, and therefore these measures were unhelpful. Drop in forced expiratory volume in 1 s was the only clinical or laboratory parameter that was close to being a determinant of respiratory exacerbation (P = 0.055). This study provides evidence of intense immunological activity occurring continually within the lungs of adult CF patients. Measurement of cytokines and inflammatory mediators in CF sputum is not helpful for identifying acute respiratory exacerbations. (+info)
Murine p38-delta mitogen-activated protein kinase, a developmentally regulated protein kinase that is activated by stress and proinflammatory cytokines.
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The p38 mitogen-activated protein kinases (MAPK) play a crucial role in stress and inflammatory responses and are also involved in activation of the human immunodeficiency virus gene expression. We have isolated the murine cDNA clones encoding p38-delta MAPK, and we have localized the p38-delta gene to mouse chromosome 17A3-B and human chromosome 6p21.3. By using Northern and in situ hybridization, we have examined the expression of p38-delta in the mouse adult tissues and embryos. p38-delta was expressed primarily in the lung, testis, kidney, and gut epithelium in the adult tissues. Although p38-delta was expressed predominantly in the developing gut and the septum transversum in the mouse embryo at 9.5 days, its expression began to be expanded to many specific tissues in the 12.5-day embryo. At 15.5 days, p38-delta was expressed virtually in most developing epithelia in embryos, suggesting that p38-delta is a developmentally regulated MAPK. Interestingly, p38-delta and p38-alpha were similar serine/threonine kinases but differed in substrate specificity. Overall, p38-delta resembles p38-gamma, whereas p38-beta resembles p38-alpha. Moreover, p38-delta is activated by environmental stress, extracellular stimulants, and MAPK kinase-3, -4, -6, and -7, suggesting that p38-delta is a unique stress-responsive protein kinase. (+info)