Mechanisms of C-reactive protein-induced blood-brain barrier disruption

Background and Purpose - Increased mortality after stroke is associated with brain edema formation and high plasma levels of the acute phase reactant C-reactive protein (CRP). The aim of this study was to examine whether CRP directly affects blood-brain barrier stability and to analyze the underlying signaling pathways. Methods - We used a cell coculture model of the blood-brain barrier and the guinea pig isolated whole brain preparation. Results - We could show that CRP at clinically relevant concentrations (10 to 20 μg/mL) causes a disruption of the blood-brain barrier in both approaches. The results of our study further demonstrate CRP-induced activation of surface Fcγ receptors CD16/32 followed by p38-mitogen-activated protein kinase-dependent reactive oxygen species formation by the NAD(P)H-oxidase. The resulting oxidative stress increased myosin light chain kinase activity leading to an activation of the contractile machinery. Blocking myosin light chain phosphorylation prevented the CRP-induced blood-brain barrier breakdown and the disruption of tight junctions. Conclusions - Our data identify a previously unrecognized mechanism linking CRP and brain edema formation and present a signaling pathway that offers new sites of therapeutic intervention.