Loss of pentameric symmetry of C-reactive protein is associated with delayed apoptosis of human neutrophils.
Human neutrophil granulocytes die rapidly, and their survival is contingent upon rescue from programmed cell death by signals from the environment. Here we report that a novel signal for delaying neutrophil apoptosis is the classic acute phase reactant, C-reactive protein (CRP). However, this anti-apoptotic activity is expressed only when the cyclic pentameric structure of CRP is lost, resulting in formation of modified or monomeric CRP (mCRP), which may be formed in inflamed tissues. By contrast, native pentameric CRP and CRP peptides 77-82, 174-185, and 201-206 failed to affect neutrophil apoptosis. The apoptosis delaying action of mCRP was markedly attenuated by an antibody against the low affinity IgG immune complex receptor (CD16) but not by an anti-CD32 antibody. mCRP evoked a transient concurrent activation of the extracellular signal-regulated kinase (ERK) and phosphatidylinositol 3-kinase/Akt signaling pathways, leading to inhibition of caspase-3 and consequently to delaying apoptosis. Consistently, pharmacological inhibition of either ERK or Akt reversed the anti-apoptotic action of mCRP; however, they did not produce additive inhibition. Thus, mCRP, but not pentameric CRP or peptides derived from CRP, promotes neutrophil survival and may therefore contribute to amplification of the inflammatory response.
Research Center, Maisonneuve-Rosemont Hospital and Department of Medicine, University of Montréal, 5415 boulevard de l'Assomption, Montréal, Québec H1T 2M4, Canada.
Tarek
T
Khreiss
Levente
L
József
Shireen
S
Hossain
John S D
JS
Chan
Lawrence A
LA
Potempa
János G
JG
Filep
D000328:Adult; D017209:Apoptosis / Q000502:physiology*; D002097:C-Reactive Protein / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D002478:Cells, Cultured; D004789:Enzyme Activation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009504:Neutrophils / Q000166:cytology*; D011485:Protein Binding; D017452:Receptors, IgG / Q000378:metabolism
D017452:Receptors, IgG; D002097:C-Reactive Protein; D020928:Mitogen-Activated Protein Kinases