scholarly journals Raised Neutrophil Phospholipase A2 Activity and Defective Priming of NADPH Oxidase and Phospholipase A2 in Sickle Cell Disease

Blood ◽  
1998 ◽  
Vol 91 (9) ◽  
pp. 3423-3429 ◽  
Author(s):  
Elahe Mollapour ◽  
John B. Porter ◽  
Richard Kaczmarski ◽  
David C. Linch ◽  
Pamela J. Roberts

Abstract Intermittent painful crises due to vasoocclusion are the major clinical manifestation of sickle cell disease (SCD), but subclinical episodes may also occur. There is sparse evidence for the involvement of neutrophils in the pathophysiology of SCD, but production of cytokines by the damaged endothelium might influence neutrophil function and modulate responses to subsequent cytokine exposure. In addition, the activation of neutrophils in the microcirculation could itself exacerbate vasoocclusion. To test whether neutrophil inflammatory responses were altered in SCD, neutrophil phospholipase A2 and NADPH oxidase activity in response to in vitro priming by granulocyte-macrophage colony-stimulating factor (GM-CSF) and tumor necrosis factor-α (TNF-α) were measured both during and between painful crises. Resting levels of neutrophil phospholipase A2 activity in steady-state SCD (4.0% ± 0.5% of total cell radioactivity) were raised relative to control values (2.0% ± 0.2%, n = 10, P = .008). There was no defect of agonist-stimulated phospholipase A2 or NADPH oxidase activity in steady-state SCD; however, the ability of phospholipase A2 to respond to priming with GM-CSF was attenuated to 63% ± 17% of control values (n = 10,P = .04). Similarly, neutrophil NADPH oxidase activity after priming with GM-CSF and TNF-α was, respectively, 65% ± 11% (n = 7, P = .03) and 57% ± 7% of control (n = 10, P = .007) in steady-state disease, and was further reduced during painful vasoocclusive crises to 34% ± 9% and 25% ± 3% of control for GM-CSF and TNF-α, respectively. These data were not explained by poor splenic function or any racial factor, as normal cytokine responses were seen in splenectomized patients in remission from Hodgkin's disease and in healthy Afro-Caribbean subjects. Abnormal neutrophil cytokine priming responses were not observed in either patients with rheumatoid arthritis or iron-deficiency anemia. Our findings are indicative of an ongoing inflammatory state in SCD between painful crises involving neutrophil activation and an abnormality of cytokine-regulated neutrophil function, which may compromise the host defenses against certain microorganisms.

Blood ◽  
1998 ◽  
Vol 91 (9) ◽  
pp. 3423-3429
Author(s):  
Elahe Mollapour ◽  
John B. Porter ◽  
Richard Kaczmarski ◽  
David C. Linch ◽  
Pamela J. Roberts

Intermittent painful crises due to vasoocclusion are the major clinical manifestation of sickle cell disease (SCD), but subclinical episodes may also occur. There is sparse evidence for the involvement of neutrophils in the pathophysiology of SCD, but production of cytokines by the damaged endothelium might influence neutrophil function and modulate responses to subsequent cytokine exposure. In addition, the activation of neutrophils in the microcirculation could itself exacerbate vasoocclusion. To test whether neutrophil inflammatory responses were altered in SCD, neutrophil phospholipase A2 and NADPH oxidase activity in response to in vitro priming by granulocyte-macrophage colony-stimulating factor (GM-CSF) and tumor necrosis factor-α (TNF-α) were measured both during and between painful crises. Resting levels of neutrophil phospholipase A2 activity in steady-state SCD (4.0% ± 0.5% of total cell radioactivity) were raised relative to control values (2.0% ± 0.2%, n = 10, P = .008). There was no defect of agonist-stimulated phospholipase A2 or NADPH oxidase activity in steady-state SCD; however, the ability of phospholipase A2 to respond to priming with GM-CSF was attenuated to 63% ± 17% of control values (n = 10,P = .04). Similarly, neutrophil NADPH oxidase activity after priming with GM-CSF and TNF-α was, respectively, 65% ± 11% (n = 7, P = .03) and 57% ± 7% of control (n = 10, P = .007) in steady-state disease, and was further reduced during painful vasoocclusive crises to 34% ± 9% and 25% ± 3% of control for GM-CSF and TNF-α, respectively. These data were not explained by poor splenic function or any racial factor, as normal cytokine responses were seen in splenectomized patients in remission from Hodgkin's disease and in healthy Afro-Caribbean subjects. Abnormal neutrophil cytokine priming responses were not observed in either patients with rheumatoid arthritis or iron-deficiency anemia. Our findings are indicative of an ongoing inflammatory state in SCD between painful crises involving neutrophil activation and an abnormality of cytokine-regulated neutrophil function, which may compromise the host defenses against certain microorganisms.


Blood ◽  
2001 ◽  
Vol 97 (8) ◽  
pp. 2469-2477 ◽  
Author(s):  
Elahe Mollapour ◽  
David C. Linch ◽  
Pamela J. Roberts

Abstract Arachidonic acid (AA) generated by phospholipase A2(PLA2) is thought to be an essential cofactor for phagocyte nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity. Both enzymes are simultaneously primed by cytokines such as granulocyte-macrophage colony-stimulating factor (GM-CSF) and tumor necrosis factor–α (TNF-α). The possibility that either unprimed or cytokine-primed responses of PLA2 or NADPH oxidase to the chemotactic agents formyl-methionyl-leucyl-phenylalanine (FMLP) and complement factor 5a (C5a) could be differentially inhibited by inhibitors of the mitogen-activated protein (MAP) kinase family members p42ERK2 (PD98059) and p38SAPK(SB203580) was investigated. PD98059 inhibited the activation of p42ERK2 by GM-CSF, TNF-α, and FMLP, but it did not inhibit FMLP-stimulated superoxide production in either unprimed or primed neutrophils. There was no significant arachidonate release from unprimed neutrophils stimulated by FMLP, and arachidonate release stimulated by calcium ionophore A23187 was not inhibited by PD98059. In contrast, PD98059 inhibited both TNF-α– and GM-CSF–primed PLA2 responses stimulated by FMLP. On the other hand, SB203580 inhibited FMLP-superoxide responses in unprimed as well as TNF-α– and GM-CSF–primed neutrophils, but failed to inhibit TNF-α– and GM-CSF–primed PLA2 responses stimulated by FMLP, and additionally enhanced A23187-stimulated arachidonate release, showing that priming and activation of PLA2 and NADPH oxidase are differentially dependent on both the p38SAPK and p42ERK2 pathways. Studies using C5a as an agonist gave similar results and confirmed the findings with FMLP. In addition, methyl arachidonyl fluorophosphonate (MAFP), the dual inhibitor of c and iPLA2 enzymes, failed to inhibit superoxide production in primed cells at concentrations that inhibited arachidonate release. These data demonstrate that NADPH oxidase activity can be dissociated from AA generation and indicate a more complex role for arachidonate in neutrophil superoxide production.


Blood ◽  
2013 ◽  
Vol 121 (11) ◽  
pp. 2099-2107 ◽  
Author(s):  
Alex George ◽  
Suvarnamala Pushkaran ◽  
Diamantis G. Konstantinidis ◽  
Sebastian Koochaki ◽  
Punam Malik ◽  
...  

Key Points Sickle RBC ROS production is mediated in part by NADPH oxidase activity. Sickle RBC ROS production can be induced by plasma signaling molecules.


2014 ◽  
Vol 306 (11) ◽  
pp. F1348-F1356 ◽  
Author(s):  
Shuaishuai Zhu ◽  
Yelin Yang ◽  
Jin Hu ◽  
Lingling Qian ◽  
Yuchen Jiang ◽  
...  

Diabetic nephropathy (DN) is the leading cause of end-stage kidney disease worldwide. The purpose of this study is to investigate whether the WldS (slow Wallerian degeneration; also known as Wld) gene plays a renoprotective role during the progression of DN. Diabetes was induced in 8-wk-old male wild-type (WT) and C57BL/WldS mice by streptozotocin (STZ) injection. Blood and urinary variables including blood glucose, glycated hemoglobin (GHb), insulin, urea nitrogen, and albumin/creatinine ratio were assessed 4, 7, and 14 wk after STZ injection. Periodic acid-Schiff staining, Masson staining, and silver staining were performed for renal pathological analyses. In addition, the renal ultrastructure was observed by electron microscope. The activities of p38 and ERK signaling in renal cortical tissues were evaluated by Western blotting. NAD+/NADH ratio and NADPH oxidase activity were also measured. Moreover, the expressions of TNF-α, IL-1, and IL-6 were examined. We provide experimental evidence demonstrating that the WldS gene is expressed in kidney cells and protects against the early stage of diabetes-induced renal dysfunction and extracellular matrix accumulation through delaying the reduction of the NAD+/NADH ratio, inhibiting the activation of p38 and ERK signaling, and suppressing oxidative stress as evidenced by the decreased NADPH oxidase activity and lower expression of TNF-α, IL-1, and IL-6.


2002 ◽  
Vol 277 (28) ◽  
pp. 25385-25392 ◽  
Author(s):  
Xiaoxian Zhao ◽  
Erik A. Bey ◽  
Frans B. Wientjes ◽  
Martha K. Cathcart

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