Effects of<i>Anaplasma phagocytophila</i>on NADPH Oxidase Components in Human Neutrophils and HL-60 Cells

Mott, Jason; Rikihisa, Yasuko; Tsunawaki, Shohko

doi:10.1128/iai.70.3.1359-1366.2002

Cited by 68 publications

(77 citation statements)

References 33 publications

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“…Moreover, none of the genes encoding NADPH oxidase components, including CYBB (gp91 phox ) and CYBA (p22 phox ), were significantly down-regulated after A. phagocytophilum infection (Table I). These results clearly indicate that failure of A. phagocytophilum to elicit production of ROS by PMNs, or to block ROS production by a second stimulus, is not due to repression of genes encoding NADPH oxidase proteins, as previously suggested (12)(13)(14)(15).…”

Section: Expression Of Genes Encoding Nadph Oxidase Componentssupporting

confidence: 82%

“…Previous studies in promyelocytic HL60 cells suggest that the ability of A. phagocytophilum to inhibit ROS generation is linked to down-regulation of NADPH oxidase components (12)(13)(14)(15). However, this mechanism has not been demonstrated in human neutrophils.…”

Section: Expression Of Genes Encoding Nadph Oxidase Componentsmentioning

confidence: 95%

“…Studies evaluating functional alterations in A. phagocytophilum-infected PMNs suggest that the pathogen delays PMN apoptosis (6,7), minimizes proinflammatory cytokine release (8,9), and inhibits and/or fails to activate ROS production (10 -13). Mechanisms underlying the ability of A. phagocytophilum to inhibit production of PMN ROS are unclear (12)(13)(14)(15).…”

Section: P Olymorphonuclear Leukocytes (Pmnsmentioning

confidence: 99%

“…Neutrophil apoptosis was assessed by analysis of nuclear morphology (16) or with a modified TUNEL assay (Apo-BrdU; BD Biosciences), as described (15). Briefly, PMNs (2 ϫ 10 6 ) were plated directly into 24-well plates precoated with normal human serum and removed by aspiration at the desired time point.…”

Section: Neutrophil Apoptosismentioning

confidence: 99%

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Insights into Pathogen Immune Evasion Mechanisms: Anaplasma phagocytophilum Fails to Induce an Apoptosis Differentiation Program in Human Neutrophils

Borjesson

Kobayashi

Whitney

et al. 2005

The Journal of Immunology

126

168

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Polymorphonuclear leukocytes (PMNs or neutrophils) are essential to human innate host defense. However, some bacterial pathogens circumvent destruction by PMNs and thereby cause disease. Anaplasma phagocytophilum, the agent of human granulocytic anaplasmosis, survives within PMNs in part by altering normal host cell processes, such as production of reactive oxygen species (ROS) and apoptosis. To investigate the molecular basis of A. phagocytophilum survival within neutrophils, we used Affymetrix microarrays to measure global changes in human PMN gene expression following infection with A. phagocytophilum. Notably, A. phagocytophilum uptake induced fewer perturbations in host cell gene regulation compared with phagocytosis of Staphylococcus aureus. Although ingestion of A. phagocytophilum did not elicit significant PMN ROS, proinflammatory genes were gradually up-regulated, indicating delayed PMN activation rather than loss of proinflammatory capacity normally observed during phagocytosis-induced apoptosis. Importantly, ingestion of A. phagocytophilum failed to trigger the neutrophil apoptosis differentiation program that typically follows phagocytosis and ROS production. Heat-killed A. phagocytophilum caused some similar initial alterations in neutrophil gene expression and function, which included delaying normal PMN apoptosis and blocking Fas-induced programmed cell death. However, at 24 h, down-regulation of PMN gene transcription may be more reliant on active infection. Taken together, these findings suggest two separate antiapoptotic processes may work concomitantly to promote bacterial survival: 1) uptake of A. phagocytophilum fails to trigger the apoptosis differentiation program usually induced by bacteria, and 2) a protein or molecule on the pathogen surface can mediate an early delay in spontaneous neutrophil apoptosis.

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Section: Expression Of Genes Encoding Nadph Oxidase Componentssupporting

confidence: 82%

Section: Expression Of Genes Encoding Nadph Oxidase Componentsmentioning

confidence: 95%

Section: P Olymorphonuclear Leukocytes (Pmnsmentioning

confidence: 99%

Section: Neutrophil Apoptosismentioning

confidence: 99%

See 2 more Smart Citations

Insights into Pathogen Immune Evasion Mechanisms: Anaplasma phagocytophilum Fails to Induce an Apoptosis Differentiation Program in Human Neutrophils

Borjesson

Kobayashi

Whitney

et al. 2005

The Journal of Immunology

126

168

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“…Molecular biology techniques have succeeded in relating their multiple interplay with not only activation (15,36,39,57) but also down-regulation (21,48) of the oxidase. However, little is known about how microbes attack the phagocyte NADPH oxidase to evade host defense, except for some recent reports regarding salmonellosis (23,56) and human granulocytic ehrlichiosis (5,38).…”

mentioning

confidence: 99%

Fungal Metabolite Gliotoxin Inhibits Assembly of the Human Respiratory Burst NADPH Oxidase

et al. 2004

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Reactive oxygen species are a critical weapon in the killing of Aspergillus fumigatus by polymorphonuclear leukocytes (PMN), as demonstrated by severe aspergillosis in chronic granulomatous disease. In the present study, A. fumigatus-produced mycotoxins (fumagillin, gliotoxin [GT], and helvolic acid) are examined for their effects on the NADPH oxidase activity in human PMN. Of these mycotoxins, only GT significantly and stoichiometrically inhibits phorbol myristate acetate (PMA)-stimulated O 2 ؊ generation, while the other two toxins are ineffective. The inhibition is dependent on the disulfide bridge of GT, which interferes with oxidase activation but not catalysis of the activated oxidase. Specifically, GT inhibits PMA-stimulated events: p47 phox phosphorylation, its incorporation into the cytoskeleton, and the membrane translocation of p67 phox , p47 phox , and p40 phox , which are crucial steps in the assembly of the active NADPH oxidase. Thus, damage to p47 phox phosphorylation is likely a key to inhibiting NADPH oxidase activation. GT does not inhibit the membrane translocation of Rac2. The inhibition of p47 phox phosphorylation is due to the defective membrane translocation of protein kinase C (PKC) ␤II rather than an effect of GT on PKC ␤II activity, suggesting a failure of PKC ␤II to associate with the substrate, p47 phox , on the membrane. These results suggest that A. fumigatus may confront PMN by inhibiting the assembly of the NADPH oxidase with its hyphal product, GT.The best-known NADPH oxidase occurs in phagocytes and provides large quantities of reactive oxygen species (ROS) to oxidatively modify microbes as a microbicidal mechanism. The phagocyte NADPH oxidase is a highly regulated multisubunit enzyme composed of p67 phox , p47 phox , p40 phox , and Rac2 in the cytosol, as well as flavocytochrome b 558 , which consists of gp91 phox and p22 phox , in the membrane (4,9,15,29,36,39,57). The enzyme is dormant in resting cells, with these phox (for phagocyte oxidase) components being distributed to their cellular compartments. However, once phagocytes encounter invading microbes or soluble stimulants, such as phorbol myristate acetate (PMA), cytosolic phox components and Rac2 migrate to the membrane to assemble with flavocytochrome b 558 , forming the active enzyme. The activated flavocytochrome b 558 works as the catalytic redox center, where electrons are transferred from NADPH to molecular oxygen to generate O 2 Ϫ , a precursor of ROS. Recently, increasing attention has been directed toward the Nox/Duox family in nonphagocytes (33), which is composed of homologues of gp91 phox . Although the rates of ROS production are quite low in nonphagocytes, their ROS are believed to play important roles in cell signaling, hypoxic response, the immune system, etc.Over the past decade, the biochemistry of phagocyte NADPH oxidase has been intensively studied, particularly concerning the roles of Src homology 3 (SH3) domains and proline-rich regions (PRR), as well as those of other domains recently identified in...

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Ehrlichia and Anaplasma

Rikihisa

2009

Intracellular Niches of Microbes

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Effects ofAnaplasma phagocytophilaon NADPH Oxidase Components in Human Neutrophils and HL-60 Cells

Cited by 68 publications

References 33 publications

Insights into Pathogen Immune Evasion Mechanisms: Anaplasma phagocytophilum Fails to Induce an Apoptosis Differentiation Program in Human Neutrophils

Insights into Pathogen Immune Evasion Mechanisms: Anaplasma phagocytophilum Fails to Induce an Apoptosis Differentiation Program in Human Neutrophils

Fungal Metabolite Gliotoxin Inhibits Assembly of the Human Respiratory Burst NADPH Oxidase

Ehrlichia and Anaplasma

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