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* Academic Unit of Respiratory Medicine, School of Medicine and Biomedical Sciences, and
Department of Biomedical Science, University of Sheffield, Sheffield, United Kingdom; and
Pharmaceutical Biochemistry, Institute of Pharmaceutical and Medicinal Chemistry, University of Dusseldorf, Dusseldorf, Germany
Neutrophils undergo rapid constitutive apoptosis that is delayed by a range of pathogen- and host-derived inflammatory mediators. We have investigated the ability of the nucleotide ATP, to which neutrophils are exposed both in the circulation and at sites of inflammation, to modulate the lifespan of human neutrophils. We found that physiologically relevant concentrations of ATP cause a concentration-dependent delay of neutrophil apoptosis (assessed by morphology, annexin V/To-Pro3 staining, and mitochondrial membrane permeabilization). We found that even brief exposure to ATP (10 min) was sufficient to cause a long-lasting delay of apoptosis and showed that the effects were not mediated by ATP breakdown to adenosine. The P2 receptor mediating the antiapoptotic actions of ATP was identified using a combination of more selective ATP analogs, receptor expression studies, and study of downstream signaling pathways. Neutrophils were shown to express the P2Y11 receptor and inhibition of P2Y11 signaling using the antagonist NF157 abrogated the ATP-mediated delay of neutrophil apoptosis, as did inhibition of type I cAMP-dependent protein kinases activated downstream of P2Y11, without effects on constitutive apoptosis. Specific targeting of P2Y11 could retain key immune functions of neutrophils but reduce the injurious effects of increased neutrophil longevity during inflammation.
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
1 This work was supported by a British Heart Foundation Ph.D. Studentship to K.R.V. (Ref. FS/03/125/16306). I.S. holds a Medical Research Council Senior Clinical Fellowship (G116/170), and A.M.S. is supported by Programme funding from the Wellcome Trust.
2 Address correspondence and reprint requests to Dr. Moira Whyte, Academic Unit of Respiratory Medicine, School of Medicine and Biomedical Sciences, L Floor, Royal Hallamshire Hospital, Sheffield S10 2JF, U.K. E-mail address: m.k.whyte{at}sheffield.ac.uk
3 Abbreviations used in this paper: [Ca2+]i, intracellular calcium; 
βMeATP, β-methylene-ATP; ATP-
-S, AT[-thio]P; BzATP, 2'-3'-O-(4-benzoylbenzoyl)-ATP; cA-PK, cAMP-dependent protein kinases; HEK, human embryonic kidney; JC-1, 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolylcarbocyanine iodide; 2MeSATP, 2-(methylthio)-ATP; N6-MB-cAMP, N6-monobutyryladenosine-cAMP; PLC, phospholipase C; Rp-8-Br-cAMPS (Rp isomer), 8-bromoadenosine-3',5'-cyclic monophosphorothioate; U73122, 1-{6-{[17β-3-methoxyestra-1,3,4(10)-trien-17-yl]amino}hexyl}-1H-pyrrole-2,5-dione; fluo-4-AM, fluo-4-acetoxymethyl ester; EC50, half-maximal effective concentration; [cAMP]i, intracellular cAMP.
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