Loss of pentameric symmetry of C‐reactive protein induces interleukin‐8 production through peroxynitrite signaling in human neutrophils

Abstract

Elevated plasma levels of C-reactive protein (CRP), nitrotyrosine, and IL-8 are predictive of acute cardiovascular events. However, it is unknown whether these events are linked. We studied the impact of human native CRP and bioengineered modified or monomeric CRP (mCRP) that cannot rearrange into the pentameric structure on ONOO- formation and IL-8 gene expression. Culture of human neutrophils with mCRP (0.1–50 μg/ml) for 4 h markedly increased IL-8 mRNA and protein expression. Native CRP enhanced IL-8 release only after >8 h of incubation. mCRP induced rapid increases in intracellular Ca2+ and phosphorylation of Akt, leading to concomitant increases in superoxide and NO production. These coincided with increases in L-NAME-inhibitable dihydrorhodamine oxidation and nitrotyrosine formation, indicating ONOO- formation. Neutrophils expressed only endothelial NO synthase that was unaffected by mCRP. mCRP evoked rapid, time-dependent mobilization of NF-kB and AP-1 to the nucleus. These were attenuated by L-NAME, parallel with inhibition of IL-8 mRNA expression. An anti-CD16 antibody, but not an anti-CD32 antibody, partially attenuated both mCRP and CRP-stimulated IL-8 release. These results provide a potential link between CRP, nitrosative stress and IL-8 and suggest that loss of the pentameric symmetry in CRP is a prerequisite for induction of IL-8 release from human neutrophils. (Supported by the CIHR and HSFC)