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Träfflista för sökning "WFRF:(Speert D. P.) srt2:(2005-2009)"

Search: WFRF:(Speert D. P.) > (2005-2009)

  • Result 1-6 of 6
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1.
  • Davidson, D. J., et al. (author)
  • IRAK-4 mutation (Q293X): rapid detection and characterization of defective post-transcriptional TLR/IL-1R responses in human myeloid and non-myeloid cells
  • 2006
  • In: J Immunol. ; 177:11, s. 8202-11
  • Journal article (peer-reviewed)abstract
    • Innate immunodeficiency has recently been reported as resulting from the Q293X IRAK-4 mutation with consequent defective TLR/IL-1R signaling. In this study we report a method for the rapid allele-specific detection of this mutation and demonstrate both cell type specificity and ligand specificity in defective IL-1R-associated kinase (IRAK)-4-deficient cellular responses, indicating differential roles for this protein in human PBMCs and primary dermal fibroblasts and in LPS, IL-1beta, and TNF-alpha signaling. We demonstrate transcriptional and post-transcriptional defects despite NF-kappaB signaling and intact MyD88-independent signaling and propose that dysfunctional complex 1 (IRAK1/TRAF6/TAK1) signaling, as a consequence of IRAK-4 deficiency, generates specific defects in MAPK activation that could underpin this patient's innate immunodeficiency. These studies demonstrate the importance of studying primary human cells bearing a clinically relevant mutation; they underscore the complexity of innate immune signaling and illuminate novel roles for IRAK-4 and the fundamental importance of accessory proinflammatory signaling to normal human innate immune responses and immunodeficiencies.
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2.
  • Bylund, Johan, 1975, et al. (author)
  • Burkholderia cenocepacia induces neutrophil necrosis in chronic granulomatous disease
  • 2005
  • In: J Immunol. ; 174:6, s. 3562-9
  • Journal article (peer-reviewed)abstract
    • Burkholderia cepacia complex is a life-threatening group of pathogens for patients with chronic granulomatous disease (CGD), whose phagocytes are unable to produce reactive oxygen species (ROS). Unlike other CGD pathogens, B. cepacia complex is particularly virulent, characteristically causing septicemia, and is the bacterial species responsible for most fatalities in these patients. We found that a nonmucoid Burkholderia cenocepacia (a predominant species in the B. cepacia complex) isolate was readily ingested by normal human neutrophils under nonopsonic conditions and promoted apoptosis in these cells. The proapoptotic effect was not due to secreted bacterial products, but was dependent on bacterial viability. Phagocytosis was associated with a robust production of ROS, and the apoptotic neutrophils could be effectively cleared by monocyte-derived macrophages. The proapoptotic effect of B. cenocepacia was independent of ROS production because neutrophils from CGD patients were rendered apoptotic to a similar degree as control cells after challenge. More importantly, neutrophils from CGD patients, but not from normal individuals, were rendered necrotic after phagocytosis of B. cenocepacia. The extreme virulence of B. cepacia complex bacteria in CGD, but not in immunocompetent hosts, could be due to its necrotic potential in the absence of ROS.
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4.
  • Bylund, Johan, 1975, et al. (author)
  • Enhanced inflammatory responses of chronic granulomatous disease leukocytes involve ROS-independent activation of NF-kappa B
  • 2007
  • In: Eur J Immunol. ; 37:4, s. 1087-96
  • Journal article (peer-reviewed)abstract
    • Reactive oxygen species (ROS) generated by the cellular NADPH-oxidase are crucial for phagocytic killing of ingested microbes and have been implicated as signaling molecules in various processes. For example, ROS are thought to be involved in activation of the transcription factor NF-kappaB, central for mediating production of proinflammatory cytokines in response to inflammatory stimuli. Several studies have demonstrated that inhibitors of the NADPH-oxidase interfere with NF-kappaB activation and production of proinflammatory cytokines. Curiously, patients with chronic granulomatous disease (CGD), an immunodeficiency characterized by an inability to produce ROS, are not only predisposed to severe infections, but also frequently develop various inflammatory complications indicative of exaggerated inflammatory responses. Here, we show that human CGD leukocytes display a hyperinflammatory phenotype with increased production of proinflammatory cytokines in response to stimulation with Toll-like receptor agonists. The hyperinflammatory phenotype was also evident in mononuclear cells from CGD mice (gp91(phox) -/-), but not in control cells in the presence of NADPH-oxidase inhibitor diphenyleneiodonium, probably reflecting NADPH-oxidase-independent effects of the inhibitor. Furthermore, we show that the major steps involved in NF-kappaB activation were intact in human CGD cells. These data indicate that ROS were nonessential for activation of NF-kappaB and their production may even attenuate inflammation.
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5.
  • Bylund, Johan, 1975, et al. (author)
  • Exopolysaccharides from Burkholderia cenocepacia inhibit neutrophil chemotaxis and scavenge reactive oxygen species
  • 2006
  • In: J Biol Chem. ; 281:5, s. 2526-32
  • Journal article (peer-reviewed)abstract
    • Bacteria belonging to the Burkholderia cepacia complex are important opportunistic pathogens in compromised hosts, particularly patients with cystic fibrosis or chronic granulomatous disease. Isolates of B. cepacia complex may produce large amounts of exopolysaccharides (EPS) that endow the bacteria with a mucoid phenotype and appear to facilitate bacterial persistence during infection. We showed that EPS from a clinical B. cenocepacia isolate interfered with the function of human neutrophils in vitro; it inhibited chemotaxis and production of reactive oxygen species (ROS), both essential components of innate neutrophil-mediated host defenses. These inhibitory effects were not due to cytotoxicity or interference with intracellular calcium signaling. EPS also inhibited enzymatic generation of ROS in cell-free systems, indicating that it scavenges these bactericidal products. B. cenocepacia EPS is structurally distinct from Pseudomonas aeruginosa alginate, yet they share the capacity to scavenge ROS and inhibit chemotaxis. These properties could explain why the two bacterial species resist clearance from the infected cystic fibrosis lung.
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6.
  • Brown, Kelly, 1973, et al. (author)
  • ROS-deficient monocytes have aberrant gene expression that correlates with inflammatory disorders of chronic granulomatous disease
  • 2008
  • In: Clin Immunol. - 1521-7035. ; 129:1, s. 90-102
  • Journal article (peer-reviewed)abstract
    • Chronic granulomatous disease is an immunodeficiency caused by an inability to produce reactive oxygen species. While the mechanism of hyper-sensitivity to infection is well understood in CGD, the basis for debilitating inflammatory disorders that arise in the absence of evident infection has not been fully explained. Herein it is demonstrated that resting and TLR-activated monocytes from individuals with CGD expressed significantly higher levels of inflammatory mediators than control cells; the expression in CGD cells resembled normal cells stimulated with lipopolysaccharide. The lack of acute illness, infection or circulating endotoxin in the blood of the CGD patients at the time of sampling was consistent with infection-free inflammation. The enhanced expression of inflammatory mediators correlated with elevated expression of NF-kappaB and was dependent on ERK1/2 signalling. The results are consistent with the hypothesis that ROS are anti-inflammatory mediators that control gene expression and potentially limit the development of sterile inflammatory disorders.
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  • Result 1-6 of 6

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