Conformational rearrangement in C-reactive protein is required for proinflammatory actions on human endothelial cells.
BACKGROUND
C-reactive protein (CRP) has been suggested to actively amplify the inflammatory response underlying coronary heart diseases by directly activating endothelial cells. In this study, we investigated whether loss of the cyclic pentameric structure of CRP, resulting in formation of modified or monomeric CRP (mCRP), is a prerequisite for endothelial cell activation.


RESULTS
We examined the impact of native CRP and mCRP on the production of monocyte chemoattractant protein-1 (MCP-1) and interleukin-8 (IL-8), key regulators of leukocyte recruitment, and on the expression of intercellular adhesion molecule-1 (ICAM-1), E-selectin, and vascular adhesion molecule-1 (VCAM-1) in human cultured coronary artery endothelial cells (HCAECs). Incubation with mCRP for 4 hours increased MCP-1 and IL-8 secretion and mRNA levels and expression of ICAM-1, E-selectin, and VCAM-1 protein and mRNA. Significant induction occurred at 1 to 5 microg/mL, reached a maximum at 30 microg/mL, and did not require the presence of serum. Native CRP was without detectable effects at 4 hours, whereas it enhanced cytokine release after a 24-hour incubation. An anti-FcgammaRIII (CD16) but not an anti-FcgammaRII (CD32) antibody produced a 14% to 32% reduction of the mCRP effects (P<0.05). mCRP but not CRP evoked phosphorylation of p38 mitogen-activated protein kinase, and inhibition of this kinase with SB 203580 reversed the effects of mCRP. Furthermore, culture of HCAECs in the presence of SB203580 markedly decreased mCRP-stimulated E-selectin and ICAM-1-dependent adhesion of neutrophils to HCAECs (P<0.001).


CONCLUSIONS
Loss of pentameric symmetry in CRP, resulting in formation of mCRP, promotes a proinflammatory HCAEC phenotype through a p38 MAPK-dependent mechanism.
Khreiss
Tarek
T
Research Center, Maisonneuve-Rosemont Hospital and Department of Medicine , University of Montreal, Montreal, QC, Canada.
József
Levente
L
Potempa
Lawrence A
LA
Filep
János G
JG
D002097:C-Reactive Protein / Q000737:chemistry* / Q000494:pharmacology; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000096:biosynthesis; D018932:Chemokine CCL2 / Q000378:metabolism; D003331:Coronary Vessels / Q000166:cytology; D004730:Endothelium, Vascular / Q000737:chemistry / Q000166:cytology / Q000276:immunology*; D006801:Humans; D007249:Inflammation / Q000276:immunology; D016209:Interleukin-8 / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009504:Neutrophils / Q000276:immunology; D011487:Protein Conformation; D011971:Receptors, Immunologic / Q000032:analysis; D048051:p38 Mitogen-Activated Protein Kinases
C071581:CRP protein, human; D015815:Cell Adhesion Molecules; D018932:Chemokine CCL2; D016209:Interleukin-8; D011971:Receptors, Immunologic; D002097:C-Reactive Protein; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases